diff options
| -rw-r--r-- | MAINTAINERS | 8 | ||||
| -rw-r--r-- | drivers/platform/surface/Kconfig | 2 | ||||
| -rw-r--r-- | drivers/platform/surface/Makefile | 1 | ||||
| -rw-r--r-- | drivers/platform/surface/aggregator/Kconfig | 42 | ||||
| -rw-r--r-- | drivers/platform/surface/aggregator/Makefile | 10 | ||||
| -rw-r--r-- | drivers/platform/surface/aggregator/controller.c | 2504 | ||||
| -rw-r--r-- | drivers/platform/surface/aggregator/controller.h | 276 | ||||
| -rw-r--r-- | drivers/platform/surface/aggregator/core.c | 787 | ||||
| -rw-r--r-- | drivers/platform/surface/aggregator/ssh_msgb.h | 205 | ||||
| -rw-r--r-- | drivers/platform/surface/aggregator/ssh_packet_layer.c | 1710 | ||||
| -rw-r--r-- | drivers/platform/surface/aggregator/ssh_packet_layer.h | 187 | ||||
| -rw-r--r-- | drivers/platform/surface/aggregator/ssh_parser.c | 228 | ||||
| -rw-r--r-- | drivers/platform/surface/aggregator/ssh_parser.h | 154 | ||||
| -rw-r--r-- | drivers/platform/surface/aggregator/ssh_request_layer.c | 1211 | ||||
| -rw-r--r-- | drivers/platform/surface/aggregator/ssh_request_layer.h | 143 | ||||
| -rw-r--r-- | include/linux/surface_aggregator/controller.h | 824 | ||||
| -rw-r--r-- | include/linux/surface_aggregator/serial_hub.h | 672 |
17 files changed, 8964 insertions, 0 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index 546aa66428c9..845a245f562c 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -11813,6 +11813,14 @@ L: platform-driver-x86@vger.kernel.org S: Supported F: drivers/platform/surface/surfacepro3_button.c +MICROSOFT SURFACE SYSTEM AGGREGATOR SUBSYSTEM +M: Maximilian Luz <luzmaximilian@gmail.com> +S: Maintained +W: https://github.com/linux-surface/surface-aggregator-module +C: irc://chat.freenode.net/##linux-surface +F: drivers/platform/surface/aggregator/ +F: include/linux/surface_aggregator/ + MICROTEK X6 SCANNER M: Oliver Neukum <oliver@neukum.org> S: Maintained diff --git a/drivers/platform/surface/Kconfig b/drivers/platform/surface/Kconfig index 2c941cdac9ee..2916a47b130e 100644 --- a/drivers/platform/surface/Kconfig +++ b/drivers/platform/surface/Kconfig @@ -56,4 +56,6 @@ config SURFACE_PRO3_BUTTON help This driver handles the power/home/volume buttons on the Microsoft Surface Pro 3/4 tablet. +source "drivers/platform/surface/aggregator/Kconfig" + endif # SURFACE_PLATFORMS diff --git a/drivers/platform/surface/Makefile b/drivers/platform/surface/Makefile index cedfb027ded1..034134fe0264 100644 --- a/drivers/platform/surface/Makefile +++ b/drivers/platform/surface/Makefile @@ -7,5 +7,6 @@ obj-$(CONFIG_SURFACE3_WMI) += surface3-wmi.o obj-$(CONFIG_SURFACE_3_BUTTON) += surface3_button.o obj-$(CONFIG_SURFACE_3_POWER_OPREGION) += surface3_power.o +obj-$(CONFIG_SURFACE_AGGREGATOR) += aggregator/ obj-$(CONFIG_SURFACE_GPE) += surface_gpe.o obj-$(CONFIG_SURFACE_PRO3_BUTTON) += surfacepro3_button.o diff --git a/drivers/platform/surface/aggregator/Kconfig b/drivers/platform/surface/aggregator/Kconfig new file mode 100644 index 000000000000..e9f4ad96e40a --- /dev/null +++ b/drivers/platform/surface/aggregator/Kconfig @@ -0,0 +1,42 @@ +# SPDX-License-Identifier: GPL-2.0+ +# Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + +menuconfig SURFACE_AGGREGATOR + tristate "Microsoft Surface System Aggregator Module Subsystem and Drivers" + depends on SERIAL_DEV_BUS + select CRC_CCITT + help + The Surface System Aggregator Module (Surface SAM or SSAM) is an + embedded controller (EC) found on 5th- and later-generation Microsoft + Surface devices (i.e. Surface Pro 5, Surface Book 2, Surface Laptop, + and newer, with exception of Surface Go series devices). + + Depending on the device in question, this EC provides varying + functionality, including: + - EC access from ACPI via Surface ACPI Notify (5th- and 6th-generation) + - battery status information (all devices) + - thermal sensor access (all devices) + - performance mode / cooling mode control (all devices) + - clipboard detachment system control (Surface Book 2 and 3) + - HID / keyboard input (Surface Laptops, Surface Book 3) + + This option controls whether the Surface SAM subsystem core will be + built. This includes a driver for the Surface Serial Hub (SSH), which + is the device responsible for the communication with the EC, and a + basic kernel interface exposing the EC functionality to other client + drivers, i.e. allowing them to make requests to the EC and receive + events from it. Selecting this option alone will not provide any + client drivers and therefore no functionality beyond the in-kernel + interface. Said functionality is the responsibility of the respective + client drivers. + + Note: While 4th-generation Surface devices also make use of a SAM EC, + due to a difference in the communication interface of the controller, + only 5th and later generations are currently supported. Specifically, + devices using SAM-over-SSH are supported, whereas devices using + SAM-over-HID, which is used on the 4th generation, are currently not + supported. + + Choose m if you want to build the SAM subsystem core and SSH driver as + module, y if you want to build it into the kernel and n if you don't + want it at all. diff --git a/drivers/platform/surface/aggregator/Makefile b/drivers/platform/surface/aggregator/Makefile new file mode 100644 index 000000000000..faad18d4a7f2 --- /dev/null +++ b/drivers/platform/surface/aggregator/Makefile @@ -0,0 +1,10 @@ +# SPDX-License-Identifier: GPL-2.0+ +# Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + +obj-$(CONFIG_SURFACE_AGGREGATOR) += surface_aggregator.o + +surface_aggregator-objs := core.o +surface_aggregator-objs += ssh_parser.o +surface_aggregator-objs += ssh_packet_layer.o +surface_aggregator-objs += ssh_request_layer.o +surface_aggregator-objs += controller.o diff --git a/drivers/platform/surface/aggregator/controller.c b/drivers/platform/surface/aggregator/controller.c new file mode 100644 index 000000000000..488318cf2098 --- /dev/null +++ b/drivers/platform/surface/aggregator/controller.c @@ -0,0 +1,2504 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Main SSAM/SSH controller structure and functionality. + * + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#include <linux/acpi.h> +#include <linux/atomic.h> +#include <linux/completion.h> +#include <linux/gpio/consumer.h> +#include <linux/interrupt.h> +#include <linux/kref.h> +#include <linux/limits.h> +#include <linux/list.h> +#include <linux/lockdep.h> +#include <linux/mutex.h> +#include <linux/rculist.h> +#include <linux/rbtree.h> +#include <linux/rwsem.h> +#include <linux/serdev.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/srcu.h> +#include <linux/types.h> +#include <linux/workqueue.h> + +#include <linux/surface_aggregator/controller.h> +#include <linux/surface_aggregator/serial_hub.h> + +#include "controller.h" +#include "ssh_msgb.h" +#include "ssh_request_layer.h" + + +/* -- Safe counters. -------------------------------------------------------- */ + +/** + * ssh_seq_reset() - Reset/initialize sequence ID counter. + * @c: The counter to reset. + */ +static void ssh_seq_reset(struct ssh_seq_counter *c) +{ + WRITE_ONCE(c->value, 0); +} + +/** + * ssh_seq_next() - Get next sequence ID. + * @c: The counter providing the sequence IDs. + * + * Return: Returns the next sequence ID of the counter. + */ +static u8 ssh_seq_next(struct ssh_seq_counter *c) +{ + u8 old = READ_ONCE(c->value); + u8 new = old + 1; + u8 ret; + + while (unlikely((ret = cmpxchg(&c->value, old, new)) != old)) { + old = ret; + new = old + 1; + } + + return old; +} + +/** + * ssh_rqid_reset() - Reset/initialize request ID counter. + * @c: The counter to reset. + */ +static void ssh_rqid_reset(struct ssh_rqid_counter *c) +{ + WRITE_ONCE(c->value, 0); +} + +/** + * ssh_rqid_next() - Get next request ID. + * @c: The counter providing the request IDs. + * + * Return: Returns the next request ID of the counter, skipping any reserved + * request IDs. + */ +static u16 ssh_rqid_next(struct ssh_rqid_counter *c) +{ + u16 old = READ_ONCE(c->value); + u16 new = ssh_rqid_next_valid(old); + u16 ret; + + while (unlikely((ret = cmpxchg(&c->value, old, new)) != old)) { + old = ret; + new = ssh_rqid_next_valid(old); + } + + return old; +} + + +/* -- Event notifier/callbacks. --------------------------------------------- */ +/* + * The notifier system is based on linux/notifier.h, specifically the SRCU + * implementation. The difference to that is, that some bits of the notifier + * call return value can be tracked across multiple calls. This is done so + * that handling of events can be tracked and a warning can be issued in case + * an event goes unhandled. The idea of that warning is that it should help + * discover and identify new/currently unimplemented features. + */ + +/** + * ssam_event_matches_notifier() - Test if an event matches a notifier. + * @n: The event notifier to test against. + * @event: The event to test. + * + * Return: Returns %true if the given event matches the given notifier + * according to the rules set in the notifier's event mask, %false otherwise. + */ +static bool ssam_event_matches_notifier(const struct ssam_event_notifier *n, + const struct ssam_event *event) +{ + bool match = n->event.id.target_category == event->target_category; + + if (n->event.mask & SSAM_EVENT_MASK_TARGET) + match &= n->event.reg.target_id == event->target_id; + + if (n->event.mask & SSAM_EVENT_MASK_INSTANCE) + match &= n->event.id.instance == event->instance_id; + + return match; +} + +/** + * ssam_nfblk_call_chain() - Call event notifier callbacks of the given chain. + * @nh: The notifier head for which the notifier callbacks should be called. + * @event: The event data provided to the callbacks. + * + * Call all registered notifier callbacks in order of their priority until + * either no notifier is left or a notifier returns a value with the + * %SSAM_NOTIF_STOP bit set. Note that this bit is automatically set via + * ssam_notifier_from_errno() on any non-zero error value. + * + * Return: Returns the notifier status value, which contains the notifier + * status bits (%SSAM_NOTIF_HANDLED and %SSAM_NOTIF_STOP) as well as a + * potential error value returned from the last executed notifier callback. + * Use ssam_notifier_to_errno() to convert this value to the original error + * value. + */ +static int ssam_nfblk_call_chain(struct ssam_nf_head *nh, struct ssam_event *event) +{ + struct ssam_event_notifier *nf; + int ret = 0, idx; + + idx = srcu_read_lock(&nh->srcu); + + list_for_each_entry_rcu(nf, &nh->head, base.node, + srcu_read_lock_held(&nh->srcu)) { + if (ssam_event_matches_notifier(nf, event)) { + ret = (ret & SSAM_NOTIF_STATE_MASK) | nf->base.fn(nf, event); + if (ret & SSAM_NOTIF_STOP) + break; + } + } + + srcu_read_unlock(&nh->srcu, idx); + return ret; +} + +/** + * ssam_nfblk_insert() - Insert a new notifier block into the given notifier + * list. + * @nh: The notifier head into which the block should be inserted. + * @nb: The notifier block to add. + * + * Note: This function must be synchronized by the caller with respect to other + * insert, find, and/or remove calls by holding ``struct ssam_nf.lock``. + * + * Return: Returns zero on success, %-EEXIST if the notifier block has already + * been registered. + */ +static int ssam_nfblk_insert(struct ssam_nf_head *nh, struct ssam_notifier_block *nb) +{ + struct ssam_notifier_block *p; + struct list_head *h; + + /* Runs under lock, no need for RCU variant. */ + list_for_each(h, &nh->head) { + p = list_entry(h, struct ssam_notifier_block, node); + + if (unlikely(p == nb)) { + WARN(1, "double register detected"); + return -EEXIST; + } + + if (nb->priority > p->priority) + break; + } + + list_add_tail_rcu(&nb->node, h); + return 0; +} + +/** + * ssam_nfblk_find() - Check if a notifier block is registered on the given + * notifier head. + * list. + * @nh: The notifier head on which to search. + * @nb: The notifier block to search for. + * + * Note: This function must be synchronized by the caller with respect to other + * insert, find, and/or remove calls by holding ``struct ssam_nf.lock``. + * + * Return: Returns true if the given notifier block is registered on the given + * notifier head, false otherwise. + */ +static bool ssam_nfblk_find(struct ssam_nf_head *nh, struct ssam_notifier_block *nb) +{ + struct ssam_notifier_block *p; + + /* Runs under lock, no need for RCU variant. */ + list_for_each_entry(p, &nh->head, node) { + if (p == nb) + return true; + } + + return false; +} + +/** + * ssam_nfblk_remove() - Remove a notifier block from its notifier list. + * @nb: The notifier block to be removed. + * + * Note: This function must be synchronized by the caller with respect to + * other insert, find, and/or remove calls by holding ``struct ssam_nf.lock``. + * Furthermore, the caller _must_ ensure SRCU synchronization by calling + * synchronize_srcu() with ``nh->srcu`` after leaving the critical section, to + * ensure that the removed notifier block is not in use any more. + */ +static void ssam_nfblk_remove(struct ssam_notifier_block *nb) +{ + list_del_rcu(&nb->node); +} + +/** + * ssam_nf_head_init() - Initialize the given notifier head. + * @nh: The notifier head to initialize. + */ +static int ssam_nf_head_init(struct ssam_nf_head *nh) +{ + int status; + + status = init_srcu_struct(&nh->srcu); + if (status) + return status; + + INIT_LIST_HEAD(&nh->head); + return 0; +} + +/** + * ssam_nf_head_destroy() - Deinitialize the given notifier head. + * @nh: The notifier head to deinitialize. + */ +static void ssam_nf_head_destroy(struct ssam_nf_head *nh) +{ + cleanup_srcu_struct(&nh->srcu); +} + + +/* -- Event/notification registry. ------------------------------------------ */ + +/** + * struct ssam_nf_refcount_key - Key used for event activation reference + * counting. + * @reg: The registry via which the event is enabled/disabled. + * @id: The ID uniquely describing the event. + */ +struct ssam_nf_refcount_key { + struct ssam_event_registry reg; + struct ssam_event_id id; +}; + +/** + * struct ssam_nf_refcount_entry - RB-tree entry for reference counting event + * activations. + * @node: The node of this entry in the rb-tree. + * @key: The key of the event. + * @refcount: The reference-count of the event. + * @flags: The flags used when enabling the event. + */ +struct ssam_nf_refcount_entry { + struct rb_node node; + struct ssam_nf_refcount_key key; + int refcount; + u8 flags; +}; + +/** + * ssam_nf_refcount_inc() - Increment reference-/activation-count of the given + * event. + * @nf: The notifier system reference. + * @reg: The registry used to enable/disable the event. + * @id: The event ID. + * + * Increments the reference-/activation-count associated with the specified + * event type/ID, allocating a new entry for this event ID if necessary. A + * newly allocated entry will have a refcount of one. + * + * Note: ``nf->lock`` must be held when calling this function. + * + * Return: Returns the refcount entry on success. Returns an error pointer + * with %-ENOSPC if there have already been %INT_MAX events of the specified + * ID and type registered, or %-ENOMEM if the entry could not be allocated. + */ +static struct ssam_nf_refcount_entry * +ssam_nf_refcount_inc(struct ssam_nf *nf, struct ssam_event_registry reg, + struct ssam_event_id id) +{ + struct ssam_nf_refcount_entry *entry; + struct ssam_nf_refcount_key key; + struct rb_node **link = &nf->refcount.rb_node; + struct rb_node *parent = NULL; + int cmp; + + lockdep_assert_held(&nf->lock); + + key.reg = reg; + key.id = id; + + while (*link) { + entry = rb_entry(*link, struct ssam_nf_refcount_entry, node); + parent = *link; + + cmp = memcmp(&key, &entry->key, sizeof(key)); + if (cmp < 0) { + link = &(*link)->rb_left; + } else if (cmp > 0) { + link = &(*link)->rb_right; + } else if (entry->refcount < INT_MAX) { + entry->refcount++; + return entry; + } else { + WARN_ON(1); + return ERR_PTR(-ENOSPC); + } + } + + entry = kzalloc(sizeof(*entry), GFP_KERNEL); + if (!entry) + return ERR_PTR(-ENOMEM); + + entry->key = key; + entry->refcount = 1; + + rb_link_node(&entry->node, parent, link); + rb_insert_color(&entry->node, &nf->refcount); + + return entry; +} + +/** + * ssam_nf_refcount_dec() - Decrement reference-/activation-count of the given + * event. + * @nf: The notifier system reference. + * @reg: The registry used to enable/disable the event. + * @id: The event ID. + * + * Decrements the reference-/activation-count of the specified event, + * returning its entry. If the returned entry has a refcount of zero, the + * caller is responsible for freeing it using kfree(). + * + * Note: ``nf->lock`` must be held when calling this function. + * + * Return: Returns the refcount entry on success or %NULL if the entry has not + * been found. + */ +static struct ssam_nf_refcount_entry * +ssam_nf_refcount_dec(struct ssam_nf *nf, struct ssam_event_registry reg, + struct ssam_event_id id) +{ + struct ssam_nf_refcount_entry *entry; + struct ssam_nf_refcount_key key; + struct rb_node *node = nf->refcount.rb_node; + int cmp; + + lockdep_assert_held(&nf->lock); + + key.reg = reg; + key.id = id; + + while (node) { + entry = rb_entry(node, struct ssam_nf_refcount_entry, node); + + cmp = memcmp(&key, &entry->key, sizeof(key)); + if (cmp < 0) { + node = node->rb_left; + } else if (cmp > 0) { + node = node->rb_right; + } else { + entry->refcount--; + if (entry->refcount == 0) + rb_erase(&entry->node, &nf->refcount); + + return entry; + } + } + + return NULL; +} + +/** + * ssam_nf_refcount_empty() - Test if the notification system has any + * enabled/active events. + * @nf: The notification system. + */ +static bool ssam_nf_refcount_empty(struct ssam_nf *nf) +{ + return RB_EMPTY_ROOT(&nf->refcount); +} + +/** + * ssam_nf_call() - Call notification callbacks for the provided event. + * @nf: The notifier system + * @dev: The associated device, only used for logging. + * @rqid: The request ID of the event. + * @event: The event provided to the callbacks. + * + * Execute registered callbacks in order of their priority until either no + * callback is left or a callback returns a value with the %SSAM_NOTIF_STOP + * bit set. Note that this bit is set automatically when converting non-zero + * error values via ssam_notifier_from_errno() to notifier values. + * + * Also note that any callback that could handle an event should return a value + * with bit %SSAM_NOTIF_HANDLED set, indicating that the event does not go + * unhandled/ignored. In case no registered callback could handle an event, + * this function will emit a warning. + * + * In case a callback failed, this function will emit an error message. + */ +static void ssam_nf_call(struct ssam_nf *nf, struct device *dev, u16 rqid, + struct ssam_event *event) +{ + struct ssam_nf_head *nf_head; + int status, nf_ret; + + if (!ssh_rqid_is_event(rqid)) { + dev_warn(dev, "event: unsupported rqid: %#06x\n", rqid); + return; + } + + nf_head = &nf->head[ssh_rqid_to_event(rqid)]; + nf_ret = ssam_nfblk_call_chain(nf_head, event); + status = ssam_notifier_to_errno(nf_ret); + + if (status < 0) { + dev_err(dev, + "event: error handling event: %d (tc: %#04x, tid: %#04x, cid: %#04x, iid: %#04x)\n", + status, event->target_category, event->target_id, + event->command_id, event->instance_id); + } else if (!(nf_ret & SSAM_NOTIF_HANDLED)) { + dev_warn(dev, + "event: unhandled event (rqid: %#04x, tc: %#04x, tid: %#04x, cid: %#04x, iid: %#04x)\n", + rqid, event->target_category, event->target_id, + event->command_id, event->instance_id); + } +} + +/** + * ssam_nf_init() - Initialize the notifier system. + * @nf: The notifier system to initialize. + */ +static int ssam_nf_init(struct ssam_nf *nf) +{ + int i, status; + + for (i = 0; i < SSH_NUM_EVENTS; i++) { + status = ssam_nf_head_init(&nf->head[i]); + if (status) + break; + } + + if (status) { + while (i--) + ssam_nf_head_destroy(&nf->head[i]); + + return status; + } + + mutex_init(&nf->lock); + return 0; +} + +/** + * ssam_nf_destroy() - Deinitialize the notifier system. + * @nf: The notifier system to deinitialize. + */ +static void ssam_nf_destroy(struct ssam_nf *nf) +{ + int i; + + for (i = 0; i < SSH_NUM_EVENTS; i++) + ssam_nf_head_destroy(&nf->head[i]); + + mutex_destroy(&nf->lock); +} + + +/* -- Event/async request completion system. -------------------------------- */ + +#define SSAM_CPLT_WQ_NAME "ssam_cpltq" + +/* + * SSAM_CPLT_WQ_BATCH - Maximum number of event item completions executed per + * work execution. Used to prevent livelocking of the workqueue. Value chosen + * via educated guess, may be adjusted. + */ +#define SSAM_CPLT_WQ_BATCH 10 + +/** + * ssam_event_item_alloc() - Allocate an event item with the given payload size. + * @len: The event payload length. + * @flags: The flags used for allocation. + * + * Allocate an event item with the given payload size. Sets the item + * operations and payload length values. The item free callback (``ops.free``) + * should not be overwritten after this call. + * + * Return: Returns the newly allocated event item. + */ +static struct ssam_event_item *ssam_event_item_alloc(size_t len, gfp_t flags) +{ + struct ssam_event_item *item; + + item = kzalloc(struct_size(item, event.data, len), flags); + if (!item) + return NULL; + + item->event.length = len; + return item; +} + +/** + * ssam_event_queue_push() - Push an event item to the event queue. + * @q: The event queue. + * @item: The item to add. + */ +static void ssam_event_queue_push(struct ssam_event_queue *q, + struct ssam_event_item *item) +{ + spin_lock(&q->lock); + list_add_tail(&item->node, &q->head); + spin_unlock(&q->lock); +} + +/** + * ssam_event_queue_pop() - Pop the next event item from the event queue. + * @q: The event queue. + * + * Returns and removes the next event item from the queue. Returns %NULL If + * there is no event item left. + */ +static struct ssam_event_item *ssam_event_queue_pop(struct ssam_event_queue *q) +{ + struct ssam_event_item *item; + + spin_lock(&q->lock); + item = list_first_entry_or_null(&q->head, struct ssam_event_item, node); + if (item) + list_del(&item->node); + spin_unlock(&q->lock); + + return item; +} + +/** + * ssam_event_queue_is_empty() - Check if the event queue is empty. + * @q: The event queue. + */ +static bool ssam_event_queue_is_empty(struct ssam_event_queue *q) +{ + bool empty; + + spin_lock(&q->lock); + empty = list_empty(&q->head); + spin_unlock(&q->lock); + + return empty; +} + +/** + * ssam_cplt_get_event_queue() - Get the event queue for the given parameters. + * @cplt: The completion system on which to look for the queue. + * @tid: The target ID of the queue. + * @rqid: The request ID representing the event ID for which to get the queue. + * + * Return: Returns the event queue corresponding to the event type described + * by the given parameters. If the request ID does not represent an event, + * this function returns %NULL. If the target ID is not supported, this + * function will fall back to the default target ID (``tid = 1``). + */ +static +struct ssam_event_queue *ssam_cplt_get_event_queue(struct ssam_cplt *cplt, + u8 tid, u16 rqid) +{ + u16 event = ssh_rqid_to_event(rqid); + u16 tidx = ssh_tid_to_index(tid); + + if (!ssh_rqid_is_event(rqid)) { + dev_err(cplt->dev, "event: unsupported request ID: %#06x\n", rqid); + return NULL; + } + + if (!ssh_tid_is_valid(tid)) { + dev_warn(cplt->dev, "event: unsupported target ID: %u\n", tid); + tidx = 0; + } + + return &cplt->event.target[tidx].queue[event]; +} + +/** + * ssam_cplt_submit() - Submit a work item to the completion system workqueue. + * @cplt: The completion system. + * @work: The work item to submit. + */ +static bool ssam_cplt_submit(struct ssam_cplt *cplt, struct work_struct *work) +{ + return queue_work(cplt->wq, work); +} + +/** + * ssam_cplt_submit_event() - Submit an event to the completion system. + * @cplt: The completion system. + * @item: The event item to submit. + * + * Submits the event to the completion system by queuing it on the event item + * queue and queuing the respective event queue work item on the completion + * workqueue, which will eventually complete the event. + * + * Return: Returns zero on success, %-EINVAL if there is no event queue that + * can handle the given event item. + */ +static int ssam_cplt_submit_event(struct ssam_cplt *cplt, + struct ssam_event_item *item) +{ + struct ssam_event_queue *evq; + + evq = ssam_cplt_get_event_queue(cplt, item->event.target_id, item->rqid); + if (!evq) + return -EINVAL; + + ssam_event_queue_push(evq, item); + ssam_cplt_submit(cplt, &evq->work); + return 0; +} + +/** + * ssam_cplt_flush() - Flush the completion system. + * @cplt: The completion system. + * + * Flush the completion system by waiting until all currently submitted work + * items have been completed. + * + * Note: This function does not guarantee that all events will have been + * handled once this call terminates. In case of a larger number of + * to-be-completed events, the event queue work function may re-schedule its + * work item, which this flush operation will ignore. + * + * This operation is only intended to, during normal operation prior to + * shutdown, try to complete most events and requests to get them out of the + * system while the system is still fully operational. It does not aim to + * provide any guarantee that all of them have been handled. + */ +static void ssam_cplt_flush(struct ssam_cplt *cplt) +{ + flush_workqueue(cplt->wq); +} + +static void ssam_event_queue_work_fn(struct work_struct *work) +{ + struct ssam_event_queue *queue; + struct ssam_event_item *item; + struct ssam_nf *nf; + struct device *dev; + unsigned int iterations = SSAM_CPLT_WQ_BATCH; + + queue = container_of(work, struct ssam_event_queue, work); + nf = &queue->cplt->event.notif; + dev = queue->cplt->dev; + + /* Limit number of processed events to avoid livelocking. */ + do { + item = ssam_event_queue_pop(queue); + if (!item) + return; + + ssam_nf_call(nf, dev, item->rqid, &item->event); + kfree(item); + } while (--iterations); + + if (!ssam_event_queue_is_empty(queue)) + ssam_cplt_submit(queue->cplt, &queue->work); +} + +/** + * ssam_event_queue_init() - Initialize an event queue. + * @cplt: The completion system on which the queue resides. + * @evq: The event queue to initialize. + */ +static void ssam_event_queue_init(struct ssam_cplt *cplt, + struct ssam_event_queue *evq) +{ + evq->cplt = cplt; + spin_lock_init(&evq->lock); + INIT_LIST_HEAD(&evq->head); + INIT_WORK(&evq->work, ssam_event_queue_work_fn); +} + +/** + * ssam_cplt_init() - Initialize completion system. + * @cplt: The completion system to initialize. + * @dev: The device used for logging. + */ +static int ssam_cplt_init(struct ssam_cplt *cplt, struct device *dev) +{ + struct ssam_event_target *target; + int status, c, i; + + cplt->dev = dev; + + cplt->wq = create_workqueue(SSAM_CPLT_WQ_NAME); + if (!cplt->wq) + return -ENOMEM; + + for (c = 0; c < ARRAY_SIZE(cplt->event.target); c++) { + target = &cplt->event.target[c]; + + for (i = 0; i < ARRAY_SIZE(target->queue); i++) + ssam_event_queue_init(cplt, &target->queue[i]); + } + + status = ssam_nf_init(&cplt->event.notif); + if (status) + destroy_workqueue(cplt->wq); + + return status; +} + +/** + * ssam_cplt_destroy() - Deinitialize the completion system. + * @cplt: The completion system to deinitialize. + * + * Deinitialize the given completion system and ensure that all pending, i.e. + * yet-to-be-completed, event items and requests have been handled. + */ +static void ssam_cplt_destroy(struct ssam_cplt *cplt) +{ + /* + * Note: destroy_workqueue ensures that all currently queued work will + * be fully completed and the workqueue drained. This means that this + * call will inherently also free any queued ssam_event_items, thus we + * don't have to take care of that here explicitly. + */ + destroy_workqueue(cplt->wq); + ssam_nf_destroy(&cplt->event.notif); +} + + +/* -- Main SSAM device structures. ------------------------------------------ */ + +/** + * ssam_controller_device() - Get the &struct device associated with this + * controller. + * @c: The controller for which to get the device. + * + * Return: Returns the &struct device associated with this controller, + * providing its lower-level transport. + */ +struct device *ssam_controller_device(struct ssam_controller *c) +{ + return ssh_rtl_get_device(&c->rtl); +} +EXPORT_SYMBOL_GPL(ssam_controller_device); + +static void __ssam_controller_release(struct kref *kref) +{ + struct ssam_controller *ctrl = to_ssam_controller(kref, kref); + + /* + * The lock-call here is to satisfy lockdep. At this point we really + * expect this to be the last remaining reference to the controller. + * Anything else is a bug. + */ + ssam_controller_lock(ctrl); + ssam_controller_destroy(ctrl); + ssam_controller_unlock(ctrl); + + kfree(ctrl); +} + +/** + * ssam_controller_get() - Increment reference count of controller. + * @c: The controller. + * + * Return: Returns the controller provided as input. + */ +struct ssam_controller *ssam_controller_get(struct ssam_controller *c) +{ + if (c) + kref_get(&c->kref); + return c; +} +EXPORT_SYMBOL_GPL(ssam_controller_get); + +/** + * ssam_controller_put() - Decrement reference count of controller. + * @c: The controller. + */ +void ssam_controller_put(struct ssam_controller *c) +{ + if (c) + kref_put(&c->kref, __ssam_controller_release); +} +EXPORT_SYMBOL_GPL(ssam_controller_put); + +/** + * ssam_controller_statelock() - Lock the controller against state transitions. + * @c: The controller to lock. + * + * Lock the controller against state transitions. Holding this lock guarantees + * that the controller will not transition between states, i.e. if the + * controller is in state "started", when this lock has been acquired, it will + * remain in this state at least until the lock has been released. + * + * Multiple clients may concurrently hold this lock. In other words: The + * ``statelock`` functions represent the read-lock part of a r/w-semaphore. + * Actions causing state transitions of the controller must be executed while + * holding the write-part of this r/w-semaphore (see ssam_controller_lock() + * and ssam_controller_unlock() for that). + * + * See ssam_controller_stateunlock() for the corresponding unlock function. + */ +void ssam_controller_statelock(struct ssam_controller *c) +{ + down_read(&c->lock); +} +EXPORT_SYMBOL_GPL(ssam_controller_statelock); + +/** + * ssam_controller_stateunlock() - Unlock controller state transitions. + * @c: The controller to unlock. + * + * See ssam_controller_statelock() for the corresponding lock function. + */ +void ssam_controller_stateunlock(struct ssam_controller *c) +{ + up_read(&c->lock); +} +EXPORT_SYMBOL_GPL(ssam_controller_stateunlock); + +/** + * ssam_controller_lock() - Acquire the main controller lock. + * @c: The controller to lock. + * + * This lock must be held for any state transitions, including transition to + * suspend/resumed states and during shutdown. See ssam_controller_statelock() + * for more details on controller locking. + * + * See ssam_controller_unlock() for the corresponding unlock function. + */ +void ssam_controller_lock(struct ssam_controller *c) +{ + down_write(&c->lock); +} + +/* + * ssam_controller_unlock() - Release the main controller lock. + * @c: The controller to unlock. + * + * See ssam_controller_lock() for the corresponding lock function. + */ +void ssam_controller_unlock(struct ssam_controller *c) +{ + up_write(&c->lock); +} + +static void ssam_handle_event(struct ssh_rtl *rtl, + const struct ssh_command *cmd, + const struct ssam_span *data) +{ + struct ssam_controller *ctrl = to_ssam_controller(rtl, rtl); + struct ssam_event_item *item; + + item = ssam_event_item_alloc(data->len, GFP_KERNEL); + if (!item) + return; + + item->rqid = get_unaligned_le16(&cmd->rqid); + item->event.target_category = cmd->tc; + item->event.target_id = cmd->tid_in; + item->event.command_id = cmd->cid; + item->event.instance_id = cmd->iid; + memcpy(&item->event.data[0], data->ptr, data->len); + + if (WARN_ON(ssam_cplt_submit_event(&ctrl->cplt, item))) + kfree(item); +} + +static const struct ssh_rtl_ops ssam_rtl_ops = { + .handle_event = ssam_handle_event, +}; + +static bool ssam_notifier_is_empty(struct ssam_controller *ctrl); +static void ssam_notifier_unregister_all(struct ssam_controller *ctrl); + +#define SSAM_SSH_DSM_REVISION 0 + +/* d5e383e1-d892-4a76-89fc-f6aaae7ed5b5 */ +static const guid_t SSAM_SSH_DSM_GUID = + GUID_INIT(0xd5e383e1, 0xd892, 0x4a76, + 0x89, 0xfc, 0xf6, 0xaa, 0xae, 0x7e, 0xd5, 0xb5); + +enum ssh_dsm_fn { + SSH_DSM_FN_SSH_POWER_PROFILE = 0x05, + SSH_DSM_FN_SCREEN_ON_SLEEP_IDLE_TIMEOUT = 0x06, + SSH_DSM_FN_SCREEN_OFF_SLEEP_IDLE_TIMEOUT = 0x07, + SSH_DSM_FN_D3_CLOSES_HANDLE = 0x08, + SSH_DSM_FN_SSH_BUFFER_SIZE = 0x09, +}; + +static int ssam_dsm_get_functions(acpi_handle handle, u64 *funcs) +{ + union acpi_object *obj; + u64 mask = 0; + int i; + + *funcs = 0; + + /* + * The _DSM function is only present on newer models. It is not + * present on 5th and 6th generation devices (i.e. up to and including + * Surface Pro 6, Surface Laptop 2, Surface Book 2). + * + * If the _DSM is not present, indicate that no function is supported. + * This will result in default values being set. + */ + if (!acpi_has_method(handle, "_DSM")) + return 0; + + obj = acpi_evaluate_dsm_typed(handle, &SSAM_SSH_DSM_GUID, + SSAM_SSH_DSM_REVISION, 0, NULL, + ACPI_TYPE_BUFFER); + if (!obj) + return -EIO; + + for (i = 0; i < obj->buffer.length && i < 8; i++) + mask |= (((u64)obj->buffer.pointer[i]) << (i * 8)); + + if (mask & BIT(0)) + *funcs = mask; + + ACPI_FREE(obj); + return 0; +} + +static int ssam_dsm_load_u32(acpi_handle handle, u64 funcs, u64 func, u32 *ret) +{ + union acpi_object *obj; + u64 val; + + if (!(funcs & BIT(func))) + return 0; /* Not supported, leave *ret at its default value */ + + obj = acpi_evaluate_dsm_typed(handle, &SSAM_SSH_DSM_GUID, + SSAM_SSH_DSM_REVISION, func, NULL, + ACPI_TYPE_INTEGER); + if (!obj) + return -EIO; + + val = obj->integer.value; + ACPI_FREE(obj); + + if (val > U32_MAX) + return -ERANGE; + + *ret = val; + return 0; +} + +/** + * ssam_controller_caps_load_from_acpi() - Load controller capabilities from + * ACPI _DSM. + * @handle: The handle of the ACPI controller/SSH device. + * @caps: Where to store the capabilities in. + * + * Initializes the given controller capabilities with default values, then + * checks and, if the respective _DSM functions are available, loads the + * actual capabilities from the _DSM. + * + * Return: Returns zero on success, a negative error code on failure. + */ +static +int ssam_controller_caps_load_from_acpi(acpi_handle handle, + struct ssam_controller_caps *caps) +{ + u32 d3_closes_handle = false; + u64 funcs; + int status; + + /* Set defaults. */ + caps->ssh_power_profile = U32_MAX; + caps->screen_on_sleep_idle_timeout = U32_MAX; + caps->screen_off_sleep_idle_timeout = U32_MAX; + caps->d3_closes_handle = false; + caps->ssh_buffer_size = U32_MAX; + + /* Pre-load supported DSM functions. */ + status = ssam_dsm_get_functions(handle, &funcs); + if (status) + return status; + + /* Load actual values from ACPI, if present. */ + status = ssam_dsm_load_u32(handle, funcs, SSH_DSM_FN_SSH_POWER_PROFILE, + &caps->ssh_power_profile); + if (status) + return status; + + status = ssam_dsm_load_u32(handle, funcs, + SSH_DSM_FN_SCREEN_ON_SLEEP_IDLE_TIMEOUT, + &caps->screen_on_sleep_idle_timeout); + if (status) + return status; + + status = ssam_dsm_load_u32(handle, funcs, + SSH_DSM_FN_SCREEN_OFF_SLEEP_IDLE_TIMEOUT, + &caps->screen_off_sleep_idle_timeout); + if (status) + return status; + + status = ssam_dsm_load_u32(handle, funcs, SSH_DSM_FN_D3_CLOSES_HANDLE, + &d3_closes_handle); + if (status) + return status; + + caps->d3_closes_handle = !!d3_closes_handle; + + status = ssam_dsm_load_u32(handle, funcs, SSH_DSM_FN_SSH_BUFFER_SIZE, + &caps->ssh_buffer_size); + if (status) + return status; + + return 0; +} + +/** + * ssam_controller_init() - Initialize SSAM controller. + * @ctrl: The controller to initialize. + * @serdev: The serial device representing the underlying data transport. + * + * Initializes the given controller. Does neither start receiver nor + * transmitter threads. After this call, the controller has to be hooked up to + * the serdev core separately via &struct serdev_device_ops, relaying calls to + * ssam_controller_receive_buf() and ssam_controller_write_wakeup(). Once the + * controller has been hooked up, transmitter and receiver threads may be + * started via ssam_controller_start(). These setup steps need to be completed + * before controller can be used for requests. + */ +int ssam_controller_init(struct ssam_controller *ctrl, + struct serdev_device *serdev) +{ + acpi_handle handle = ACPI_HANDLE(&serdev->dev); + int status; + + init_rwsem(&ctrl->lock); + kref_init(&ctrl->kref); + + status = ssam_controller_caps_load_from_acpi(handle, &ctrl->caps); + if (status) + return status; + + dev_dbg(&serdev->dev, + "device capabilities:\n" + " ssh_power_profile: %u\n" + " ssh_buffer_size: %u\n" + " screen_on_sleep_idle_timeout: %u\n" + " screen_off_sleep_idle_timeout: %u\n" + " d3_closes_handle: %u\n", + ctrl->caps.ssh_power_profile, + ctrl->caps.ssh_buffer_size, + ctrl->caps.screen_on_sleep_idle_timeout, + ctrl->caps.screen_off_sleep_idle_timeout, + ctrl->caps.d3_closes_handle); + + ssh_seq_reset(&ctrl->counter.seq); + ssh_rqid_reset(&ctrl->counter.rqid); + + /* Initialize event/request completion system. */ + status = ssam_cplt_init(&ctrl->cplt, &serdev->dev); + if (status) + return status; + + /* Initialize request and packet transport layers. */ + status = ssh_rtl_init(&ctrl->rtl, serdev, &ssam_rtl_ops); + if (status) { + ssam_cplt_destroy(&ctrl->cplt); + return status; + } + + /* + * Set state via write_once even though we expect to be in an + * exclusive context, due to smoke-testing in + * ssam_request_sync_submit(). + */ + WRITE_ONCE(ctrl->state, SSAM_CONTROLLER_INITIALIZED); + return 0; +} + +/** + * ssam_controller_start() - Start the receiver and transmitter threads of the + * controller. + * @ctrl: The controller. + * + * Note: When this function is called, the controller should be properly + * hooked up to the serdev core via &struct serdev_device_ops. Please refer + * to ssam_controller_init() for more details on controller initialization. + * + * This function must be called with the main controller lock held (i.e. by + * calling ssam_controller_lock()). + */ +int ssam_controller_start(struct ssam_controller *ctrl) +{ + int status; + + lockdep_assert_held_write(&ctrl->lock); + + if (ctrl->state != SSAM_CONTROLLER_INITIALIZED) + return -EINVAL; + + status = ssh_rtl_start(&ctrl->rtl); + if (status) + return status; + + /* + * Set state via write_once even though we expect to be locked/in an + * exclusive context, due to smoke-testing in + * ssam_request_sync_submit(). + */ + WRITE_ONCE(ctrl->state, SSAM_CONTROLLER_STARTED); + return 0; +} + +/* + * SSAM_CTRL_SHUTDOWN_FLUSH_TIMEOUT - Timeout for flushing requests during + * shutdown. + * + * Chosen to be larger than one full request timeout, including packets timing + * out. This value should give ample time to complete any outstanding requests + * during normal operation and account for the odd package timeout. + */ +#define SSAM_CTRL_SHUTDOWN_FLUSH_TIMEOUT msecs_to_jiffies(5000) + +/** + * ssam_controller_shutdown() - Shut down the controller. + * @ctrl: The controller. + * + * Shuts down the controller by flushing all pending requests and stopping the + * transmitter and receiver threads. All requests submitted after this call + * will fail with %-ESHUTDOWN. While it is discouraged to do so, this function + * is safe to use in parallel with ongoing request submission. + * + * In the course of this shutdown procedure, all currently registered + * notifiers will be unregistered. It is, however, strongly recommended to not + * rely on this behavior, and instead the party registering the notifier + * should unregister it before the controller gets shut down, e.g. via the + * SSAM bus which guarantees client devices to be removed before a shutdown. + * + * Note that events may still be pending after this call, but, due to the + * notifiers being unregistered, these events will be dropped when the + * controller is subsequently destroyed via ssam_controller_destroy(). + * + * This function must be called with the main controller lock held (i.e. by + * calling ssam_controller_lock()). + */ +void ssam_controller_shutdown(struct ssam_controller *ctrl) +{ + enum ssam_controller_state s = ctrl->state; + int status; + + lockdep_assert_held_write(&ctrl->lock); + + if (s == SSAM_CONTROLLER_UNINITIALIZED || s == SSAM_CONTROLLER_STOPPED) + return; + + /* + * Try to flush pending events and requests while everything still + * works. Note: There may still be packets and/or requests in the + * system after this call (e.g. via control packets submitted by the + * packet transport layer or flush timeout / failure, ...). Those will + * be handled with the ssh_rtl_shutdown() call below. + */ + status = ssh_rtl_flush(&ctrl->rtl, SSAM_CTRL_SHUTDOWN_FLUSH_TIMEOUT); + if (status) { + ssam_err(ctrl, "failed to flush request transport layer: %d\n", + status); + } + + /* Try to flush all currently completing requests and events. */ + ssam_cplt_flush(&ctrl->cplt); + + /* + * We expect all notifiers to have been removed by the respective client + * driver that set them up at this point. If this warning occurs, some + * client driver has not done that... + */ + WARN_ON(!ssam_notifier_is_empty(ctrl)); + + /* + * Nevertheless, we should still take care of drivers that don't behave + * well. Thus disable all enabled events, unregister all notifiers. + */ + ssam_notifier_unregister_all(ctrl); + + /* + * Cancel remaining requests. Ensure no new ones can be queued and stop + * threads. + */ + ssh_rtl_shutdown(&ctrl->rtl); + + /* + * Set state via write_once even though we expect to be locked/in an + * exclusive context, due to smoke-testing in + * ssam_request_sync_submit(). + */ + WRITE_ONCE(ctrl->state, SSAM_CONTROLLER_STOPPED); + ctrl->rtl.ptl.serdev = NULL; +} + +/** + * ssam_controller_destroy() - Destroy the controller and free its resources. + * @ctrl: The controller. + * + * Ensures that all resources associated with the controller get freed. This + * function should only be called after the controller has been stopped via + * ssam_controller_shutdown(). In general, this function should not be called + * directly. The only valid place to call this function directly is during + * initialization, before the controller has been fully initialized and passed + * to other processes. This function is called automatically when the + * reference count of the controller reaches zero. + * + * This function must be called with the main controller lock held (i.e. by + * calling ssam_controller_lock()). + */ +void ssam_controller_destroy(struct ssam_controller *ctrl) +{ + lockdep_assert_held_write(&ctrl->lock); + + if (ctrl->state == SSAM_CONTROLLER_UNINITIALIZED) + return; + + WARN_ON(ctrl->state != SSAM_CONTROLLER_STOPPED); + + /* + * Note: New events could still have been received after the previous + * flush in ssam_controller_shutdown, before the request transport layer + * has been shut down. At this point, after the shutdown, we can be sure + * that no new events will be queued. The call to ssam_cplt_destroy will + * ensure that those remaining are being completed and freed. + */ + + /* Actually free resources. */ + ssam_cplt_destroy(&ctrl->cplt); + ssh_rtl_destroy(&ctrl->rtl); + + /* + * Set state via write_once even though we expect to be locked/in an + * exclusive context, due to smoke-testing in + * ssam_request_sync_submit(). + */ + WRITE_ONCE(ctrl->state, SSAM_CONTROLLER_UNINITIALIZED); +} + +/** + * ssam_controller_suspend() - Suspend the controller. + * @ctrl: The controller to suspend. + * + * Marks the controller as suspended. Note that display-off and D0-exit + * notifications have to be sent manually before transitioning the controller + * into the suspended state via this function. + * + * See ssam_controller_resume() for the corresponding resume function. + * + * Return: Returns %-EINVAL if the controller is currently not in the + * "started" state. + */ +int ssam_controller_suspend(struct ssam_controller *ctrl) +{ + ssam_controller_lock(ctrl); + + if (ctrl->state != SSAM_CONTROLLER_STARTED) { + ssam_controller_unlock(ctrl); + return -EINVAL; + } + + ssam_dbg(ctrl, "pm: suspending controller\n"); + + /* + * Set state via write_once even though we're locked, due to + * smoke-testing in ssam_request_sync_submit(). + */ + WRITE_ONCE(ctrl->state, SSAM_CONTROLLER_SUSPENDED); + + ssam_controller_unlock(ctrl); + return 0; +} + +/** + * ssam_controller_resume() - Resume the controller from suspend. + * @ctrl: The controller to resume. + * + * Resume the controller from the suspended state it was put into via + * ssam_controller_suspend(). This function does not issue display-on and + * D0-entry notifications. If required, those have to be sent manually after + * this call. + * + * Return: Returns %-EINVAL if the controller is currently not suspended. + */ +int ssam_controller_resume(struct ssam_controller *ctrl) +{ + ssam_controller_lock(ctrl); + + if (ctrl->state != SSAM_CONTROLLER_SUSPENDED) { + ssam_controller_unlock(ctrl); + return -EINVAL; + } + + ssam_dbg(ctrl, "pm: resuming controller\n"); + + /* + * Set state via write_once even though we're locked, due to + * smoke-testing in ssam_request_sync_submit(). + */ + WRITE_ONCE(ctrl->state, SSAM_CONTROLLER_STARTED); + + ssam_controller_unlock(ctrl); + return 0; +} + + +/* -- Top-level request interface ------------------------------------------- */ + +/** + * ssam_request_write_data() - Construct and write SAM request message to + * buffer. + * @buf: The buffer to write the data to. + * @ctrl: The controller via which the request will be sent. + * @spec: The request data and specification. + * + * Constructs a SAM/SSH request message and writes it to the provided buffer. + * The request and transport counters, specifically RQID and SEQ, will be set + * in this call. These counters are obtained from the controller. It is thus + * only valid to send the resulting message via the controller specified here. + * + * For calculation of the required buffer size, refer to the + * SSH_COMMAND_MESSAGE_LENGTH() macro. + * + * Return: Returns the number of bytes used in the buffer on success. Returns + * %-EINVAL if the payload length provided in the request specification is too + * large (larger than %SSH_COMMAND_MAX_PAYLOAD_SIZE) or if the provided buffer + * is too small. + */ +ssize_t ssam_request_write_data(struct ssam_span *buf, + struct ssam_controller *ctrl, + const struct ssam_request *spec) +{ + struct msgbuf msgb; + u16 rqid; + u8 seq; + + if (spec->length > SSH_COMMAND_MAX_PAYLOAD_SIZE) + return -EINVAL; + + if (SSH_COMMAND_MESSAGE_LENGTH(spec->length) > buf->len) + return -EINVAL; + + msgb_init(&msgb, buf->ptr, buf->len); + seq = ssh_seq_next(&ctrl->counter.seq); + rqid = ssh_rqid_next(&ctrl->counter.rqid); + msgb_push_cmd(&msgb, seq, rqid, spec); + + return msgb_bytes_used(&msgb); +} +EXPORT_SYMBOL_GPL(ssam_request_write_data); + +static void ssam_request_sync_complete(struct ssh_request *rqst, + const struct ssh_command *cmd, + const struct ssam_span *data, int status) +{ + struct ssh_rtl *rtl = ssh_request_rtl(rqst); + struct ssam_request_sync *r; + + r = container_of(rqst, struct ssam_request_sync, base); + r->status = status; + + if (r->resp) + r->resp->length = 0; + + if (status) { + rtl_dbg_cond(rtl, "rsp: request failed: %d\n", status); + return; + } + + if (!data) /* Handle requests without a response. */ + return; + + if (!r->resp || !r->resp->pointer) { + if (data->len) + rtl_warn(rtl, "rsp: no response buffer provided, dropping data\n"); + return; + } + + if (data->len > r->resp->capacity) { + rtl_err(rtl, + "rsp: response buffer too small, capacity: %zu bytes, got: %zu bytes\n", + r->resp->capacity, data->len); + r->status = -ENOSPC; + return; + } + + r->resp->length = data->len; + memcpy(r->resp->pointer, data->ptr, data->len); +} + +static void ssam_request_sync_release(struct ssh_request *rqst) +{ + complete_all(&container_of(rqst, struct ssam_request_sync, base)->comp); +} + +static const struct ssh_request_ops ssam_request_sync_ops = { + .release = ssam_request_sync_release, + .complete = ssam_request_sync_complete, +}; + +/** + * ssam_request_sync_alloc() - Allocate a synchronous request. + * @payload_len: The length of the request payload. + * @flags: Flags used for allocation. + * @rqst: Where to store the pointer to the allocated request. + * @buffer: Where to store the buffer descriptor for the message buffer of + * the request. + * + * Allocates a synchronous request with corresponding message buffer. The + * request still needs to be initialized ssam_request_sync_init() before + * it can be submitted, and the message buffer data must still be set to the + * returned buffer via ssam_request_sync_set_data() after it has been filled, + * if need be with adjusted message length. + * + * After use, the request and its corresponding message buffer should be freed + * via ssam_request_sync_free(). The buffer must not be freed separately. + * + * Return: Returns zero on success, %-ENOMEM if the request could not be + * allocated. + */ +int ssam_request_sync_alloc(size_t payload_len, gfp_t flags, + struct ssam_request_sync **rqst, + struct ssam_span *buffer) +{ + size_t msglen = SSH_COMMAND_MESSAGE_LENGTH(payload_len); + + *rqst = kzalloc(sizeof(**rqst) + msglen, flags); + if (!*rqst) + return -ENOMEM; + + buffer->ptr = (u8 *)(*rqst + 1); + buffer->len = msglen; + + return 0; +} +EXPORT_SYMBOL_GPL(ssam_request_sync_alloc); + +/** + * ssam_request_sync_free() - Free a synchronous request. + * @rqst: The request to be freed. + * + * Free a synchronous request and its corresponding buffer allocated with + * ssam_request_sync_alloc(). Do not use for requests allocated on the stack + * or via any other function. + * + * Warning: The caller must ensure that the request is not in use any more. + * I.e. the caller must ensure that it has the only reference to the request + * and the request is not currently pending. This means that the caller has + * either never submitted the request, request submission has failed, or the + * caller has waited until the submitted request has been completed via + * ssam_request_sync_wait(). + */ +void ssam_request_sync_free(struct ssam_request_sync *rqst) +{ + kfree(rqst); +} +EXPORT_SYMBOL_GPL(ssam_request_sync_free); + +/** + * ssam_request_sync_init() - Initialize a synchronous request struct. + * @rqst: The request to initialize. + * @flags: The request flags. + * + * Initializes the given request struct. Does not initialize the request + * message data. This has to be done explicitly after this call via + * ssam_request_sync_set_data() and the actual message data has to be written + * via ssam_request_write_data(). + * + * Return: Returns zero on success or %-EINVAL if the given flags are invalid. + */ +int ssam_request_sync_init(struct ssam_request_sync *rqst, + enum ssam_request_flags flags) +{ + int status; + + status = ssh_request_init(&rqst->base, flags, &ssam_request_sync_ops); + if (status) + return status; + + init_completion(&rqst->comp); + rqst->resp = NULL; + rqst->status = 0; + + return 0; +} +EXPORT_SYMBOL_GPL(ssam_request_sync_init); + +/** + * ssam_request_sync_submit() - Submit a synchronous request. + * @ctrl: The controller with which to submit the request. + * @rqst: The request to submit. + * + * Submit a synchronous request. The request has to be initialized and + * properly set up, including response buffer (may be %NULL if no response is + * expected) and command message data. This function does not wait for the + * request to be completed. + * + * If this function succeeds, ssam_request_sync_wait() must be used to ensure + * that the request has been completed before the response data can be + * accessed and/or the request can be freed. On failure, the request may + * immediately be freed. + * + * This function may only be used if the controller is active, i.e. has been + * initialized and not suspended. + */ +int ssam_request_sync_submit(struct ssam_controller *ctrl, + struct ssam_request_sync *rqst) +{ + int status; + + /* + * This is only a superficial check. In general, the caller needs to + * ensure that the controller is initialized and is not (and does not + * get) suspended during use, i.e. until the request has been completed + * (if _absolutely_ necessary, by use of ssam_controller_statelock/ + * ssam_controller_stateunlock, but something like ssam_client_link + * should be preferred as this needs to last until the request has been + * completed). + * + * Note that it is actually safe to use this function while the + * controller is in the process of being shut down (as ssh_rtl_submit + * is safe with regards to this), but it is generally discouraged to do + * so. + */ + if (WARN_ON(READ_ONCE(ctrl->state) != SSAM_CONTROLLER_STARTED)) { + ssh_request_put(&rqst->base); + return -ENODEV; + } + + status = ssh_rtl_submit(&ctrl->rtl, &rqst->base); + ssh_request_put(&rqst->base); + + return status; +} +EXPORT_SYMBOL_GPL(ssam_request_sync_submit); + +/** + * ssam_request_sync() - Execute a synchronous request. + * @ctrl: The controller via which the request will be submitted. + * @spec: The request specification and payload. + * @rsp: The response buffer. + * + * Allocates a synchronous request with its message data buffer on the heap + * via ssam_request_sync_alloc(), fully initializes it via the provided + * request specification, submits it, and finally waits for its completion + * before freeing it and returning its status. + * + * Return: Returns the status of the request or any failure during setup. + */ +int ssam_request_sync(struct ssam_controller *ctrl, + const struct ssam_request *spec, + struct ssam_response *rsp) +{ + struct ssam_request_sync *rqst; + struct ssam_span buf; + ssize_t len; + int status; + + status = ssam_request_sync_alloc(spec->length, GFP_KERNEL, &rqst, &buf); + if (status) + return status; + + status = ssam_request_sync_init(rqst, spec->flags); + if (status) + return status; + + ssam_request_sync_set_resp(rqst, rsp); + + len = ssam_request_write_data(&buf, ctrl, spec); + if (len < 0) { + ssam_request_sync_free(rqst); + return len; + } + + ssam_request_sync_set_data(rqst, buf.ptr, len); + + status = ssam_request_sync_submit(ctrl, rqst); + if (!status) + status = ssam_request_sync_wait(rqst); + + ssam_request_sync_free(rqst); + return status; +} +EXPORT_SYMBOL_GPL(ssam_request_sync); + +/** + * ssam_request_sync_with_buffer() - Execute a synchronous request with the + * provided buffer as back-end for the message buffer. + * @ctrl: The controller via which the request will be submitted. + * @spec: The request specification and payload. + * @rsp: The response buffer. + * @buf: The buffer for the request message data. + * + * Allocates a synchronous request struct on the stack, fully initializes it + * using the provided buffer as message data buffer, submits it, and then + * waits for its completion before returning its status. The + * SSH_COMMAND_MESSAGE_LENGTH() macro can be used to compute the required + * message buffer size. + * + * This function does essentially the same as ssam_request_sync(), but instead + * of dynamically allocating the request and message data buffer, it uses the + * provided message data buffer and stores the (small) request struct on the + * heap. + * + * Return: Returns the status of the request or any failure during setup. + */ +int ssam_request_sync_with_buffer(struct ssam_controller *ctrl, + const struct ssam_request *spec, + struct ssam_response *rsp, + struct ssam_span *buf) +{ + struct ssam_request_sync rqst; + ssize_t len; + int status; + + status = ssam_request_sync_init(&rqst, spec->flags); + if (status) + return status; + + ssam_request_sync_set_resp(&rqst, rsp); + + len = ssam_request_write_data(buf, ctrl, spec); + if (len < 0) + return len; + + ssam_request_sync_set_data(&rqst, buf->ptr, len); + + status = ssam_request_sync_submit(ctrl, &rqst); + if (!status) + status = ssam_request_sync_wait(&rqst); + + return status; +} +EXPORT_SYMBOL_GPL(ssam_request_sync_with_buffer); + + +/* -- Internal SAM requests. ------------------------------------------------ */ + +static SSAM_DEFINE_SYNC_REQUEST_R(ssam_ssh_get_firmware_version, __le32, { + .target_category = SSAM_SSH_TC_SAM, + .target_id = 0x01, + .command_id = 0x13, + .instance_id = 0x00, +}); + +static SSAM_DEFINE_SYNC_REQUEST_R(ssam_ssh_notif_display_off, u8, { + .target_category = SSAM_SSH_TC_SAM, + .target_id = 0x01, + .command_id = 0x15, + .instance_id = 0x00, +}); + +static SSAM_DEFINE_SYNC_REQUEST_R(ssam_ssh_notif_display_on, u8, { + .target_category = SSAM_SSH_TC_SAM, + .target_id = 0x01, + .command_id = 0x16, + .instance_id = 0x00, +}); + +static SSAM_DEFINE_SYNC_REQUEST_R(ssam_ssh_notif_d0_exit, u8, { + .target_category = SSAM_SSH_TC_SAM, + .target_id = 0x01, + .command_id = 0x33, + .instance_id = 0x00, +}); + +static SSAM_DEFINE_SYNC_REQUEST_R(ssam_ssh_notif_d0_entry, u8, { + .target_category = SSAM_SSH_TC_SAM, + .target_id = 0x01, + .command_id = 0x34, + .instance_id = 0x00, +}); + +/** + * struct ssh_notification_params - Command payload to enable/disable SSH + * notifications. + * @target_category: The target category for which notifications should be + * enabled/disabled. + * @flags: Flags determining how notifications are being sent. + * @request_id: The request ID that is used to send these notifications. + * @instance_id: The specific instance in the given target category for + * which notifications should be enabled. + */ +struct ssh_notification_params { + u8 target_category; + u8 flags; + __le16 request_id; + u8 instance_id; +} __packed; + +static_assert(sizeof(struct ssh_notification_params) == 5); + +static int __ssam_ssh_event_request(struct ssam_controller *ctrl, + struct ssam_event_registry reg, u8 cid, + struct ssam_event_id id, u8 flags) +{ + struct ssh_notification_params params; + struct ssam_request rqst; + struct ssam_response result; + int status; + + u16 rqid = ssh_tc_to_rqid(id.target_category); + u8 buf = 0; + + /* Only allow RQIDs that lie within the event spectrum. */ + if (!ssh_rqid_is_event(rqid)) + return -EINVAL; + + params.target_category = id.target_category; + params.instance_id = id.instance; + params.flags = flags; + put_unaligned_le16(rqid, ¶ms.request_id); + + rqst.target_category = reg.target_category; + rqst.target_id = reg.target_id; + rqst.command_id = cid; + rqst.instance_id = 0x00; + rqst.flags = SSAM_REQUEST_HAS_RESPONSE; + rqst.length = sizeof(params); + rqst.payload = (u8 *)¶ms; + + result.capacity = sizeof(buf); + result.length = 0; + result.pointer = &buf; + + status = ssam_retry(ssam_request_sync_onstack, ctrl, &rqst, &result, + sizeof(params)); + + return status < 0 ? status : buf; +} + +/** + * ssam_ssh_event_enable() - Enable SSH event. + * @ctrl: The controller for which to enable the event. + * @reg: The event registry describing what request to use for enabling and + * disabling the event. + * @id: The event identifier. + * @flags: The event flags. + * + * Enables the specified event on the EC. This function does not manage + * reference counting of enabled events and is basically only a wrapper for + * the raw EC request. If the specified event is already enabled, the EC will + * ignore this request. + * + * Return: Returns the status of the executed SAM request (zero on success and + * negative on direct failure) or %-EPROTO if the request response indicates a + * failure. + */ +static int ssam_ssh_event_enable(struct ssam_controller *ctrl, + struct ssam_event_registry reg, + struct ssam_event_id id, u8 flags) +{ + int status; + + status = __ssam_ssh_event_request(ctrl, reg, reg.cid_enable, id, flags); + + if (status < 0 && status != -EINVAL) { + ssam_err(ctrl, + "failed to enable event source (tc: %#04x, iid: %#04x, reg: %#04x)\n", + id.target_category, id.instance, reg.target_category); + } + + if (status > 0) { + ssam_err(ctrl, + "unexpected result while enabling event source: %#04x (tc: %#04x, iid: %#04x, reg: %#04x)\n", + status, id.target_category, id.instance, reg.target_category); + return -EPROTO; + } + + return status; +} + +/** + * ssam_ssh_event_disable() - Disable SSH event. + * @ctrl: The controller for which to disable the event. + * @reg: The event registry describing what request to use for enabling and + * disabling the event (must be same as used when enabling the event). + * @id: The event identifier. + * @flags: The event flags (likely ignored for disabling of events). + * + * Disables the specified event on the EC. This function does not manage + * reference counting of enabled events and is basically only a wrapper for + * the raw EC request. If the specified event is already disabled, the EC will + * ignore this request. + * + * Return: Returns the status of the executed SAM request (zero on success and + * negative on direct failure) or %-EPROTO if the request response indicates a + * failure. + */ +static int ssam_ssh_event_disable(struct ssam_controller *ctrl, + struct ssam_event_registry reg, + struct ssam_event_id id, u8 flags) +{ + int status; + + status = __ssam_ssh_event_request(ctrl, reg, reg.cid_enable, id, flags); + + if (status < 0 && status != -EINVAL) { + ssam_err(ctrl, + "failed to disable event source (tc: %#04x, iid: %#04x, reg: %#04x)\n", + id.target_category, id.instance, reg.target_category); + } + + if (status > 0) { + ssam_err(ctrl, + "unexpected result while disabling event source: %#04x (tc: %#04x, iid: %#04x, reg: %#04x)\n", + status, id.target_category, id.instance, reg.target_category); + return -EPROTO; + } + + return status; +} + + +/* -- Wrappers for internal SAM requests. ----------------------------------- */ + +/** + * ssam_get_firmware_version() - Get the SAM/EC firmware version. + * @ctrl: The controller. + * @version: Where to store the version number. + * + * Return: Returns zero on success or the status of the executed SAM request + * if that request failed. + */ +int ssam_get_firmware_version(struct ssam_controller *ctrl, u32 *version) +{ + __le32 __version; + int status; + + status = ssam_retry(ssam_ssh_get_firmware_version, ctrl, &__version); + if (status) + return status; + + *version = le32_to_cpu(__version); + return 0; +} + +/** + * ssam_ctrl_notif_display_off() - Notify EC that the display has been turned + * off. + * @ctrl: The controller. + * + * Notify the EC that the display has been turned off and the driver may enter + * a lower-power state. This will prevent events from being sent directly. + * Rather, the EC signals an event by pulling the wakeup GPIO high for as long + * as there are pending events. The events then need to be manually released, + * one by one, via the GPIO callback request. All pending events accumulated + * during this state can also be released by issuing the display-on + * notification, e.g. via ssam_ctrl_notif_display_on(), which will also reset + * the GPIO. + * + * On some devices, specifically ones with an integrated keyboard, the keyboard + * backlight will be turned off by this call. + * + * This function will only send the display-off notification command if + * display notifications are supported by the EC. Currently all known devices + * support these notifications. + * + * Use ssam_ctrl_notif_display_on() to reverse the effects of this function. + * + * Return: Returns zero on success or if no request has been executed, the + * status of the executed SAM request if that request failed, or %-EPROTO if + * an unexpected response has been received. + */ +int ssam_ctrl_notif_display_off(struct ssam_controller *ctrl) +{ + int status; + u8 response; + + ssam_dbg(ctrl, "pm: notifying display off\n"); + + status = ssam_retry(ssam_ssh_notif_display_off, ctrl, &response); + if (status) + return status; + + if (response != 0) { + ssam_err(ctrl, "unexpected response from display-off notification: %#04x\n", + response); + return -EPROTO; + } + + return 0; +} + +/** + * ssam_ctrl_notif_display_on() - Notify EC that the display has been turned on. + * @ctrl: The controller. + * + * Notify the EC that the display has been turned back on and the driver has + * exited its lower-power state. This notification is the counterpart to the + * display-off notification sent via ssam_ctrl_notif_display_off() and will + * reverse its effects, including resetting events to their default behavior. + * + * This function will only send the display-on notification command if display + * notifications are supported by the EC. Currently all known devices support + * these notifications. + * + * See ssam_ctrl_notif_display_off() for more details. + * + * Return: Returns zero on success or if no request has been executed, the + * status of the executed SAM request if that request failed, or %-EPROTO if + * an unexpected response has been received. + */ +int ssam_ctrl_notif_display_on(struct ssam_controller *ctrl) +{ + int status; + u8 response; + + ssam_dbg(ctrl, "pm: notifying display on\n"); + + status = ssam_retry(ssam_ssh_notif_display_on, ctrl, &response); + if (status) + return status; + + if (response != 0) { + ssam_err(ctrl, "unexpected response from display-on notification: %#04x\n", + response); + return -EPROTO; + } + + return 0; +} + +/** + * ssam_ctrl_notif_d0_exit() - Notify EC that the driver/device exits the D0 + * power state. + * @ctrl: The controller + * + * Notifies the EC that the driver prepares to exit the D0 power state in + * favor of a lower-power state. Exact effects of this function related to the + * EC are currently unknown. + * + * This function will only send the D0-exit notification command if D0-state + * notifications are supported by the EC. Only newer Surface generations + * support these notifications. + * + * Use ssam_ctrl_notif_d0_entry() to reverse the effects of this function. + * + * Return: Returns zero on success or if no request has been executed, the + * status of the executed SAM request if that request failed, or %-EPROTO if + * an unexpected response has been received. + */ +int ssam_ctrl_notif_d0_exit(struct ssam_controller *ctrl) +{ + int status; + u8 response; + + if (!ctrl->caps.d3_closes_handle) + return 0; + + ssam_dbg(ctrl, "pm: notifying D0 exit\n"); + + status = ssam_retry(ssam_ssh_notif_d0_exit, ctrl, &response); + if (status) + return status; + + if (response != 0) { + ssam_err(ctrl, "unexpected response from D0-exit notification: %#04x\n", + response); + return -EPROTO; + } + + return 0; +} + +/** + * ssam_ctrl_notif_d0_entry() - Notify EC that the driver/device enters the D0 + * power state. + * @ctrl: The controller + * + * Notifies the EC that the driver has exited a lower-power state and entered + * the D0 power state. Exact effects of this function related to the EC are + * currently unknown. + * + * This function will only send the D0-entry notification command if D0-state + * notifications are supported by the EC. Only newer Surface generations + * support these notifications. + * + * See ssam_ctrl_notif_d0_exit() for more details. + * + * Return: Returns zero on success or if no request has been executed, the + * status of the executed SAM request if that request failed, or %-EPROTO if + * an unexpected response has been received. + */ +int ssam_ctrl_notif_d0_entry(struct ssam_controller *ctrl) +{ + int status; + u8 response; + + if (!ctrl->caps.d3_closes_handle) + return 0; + + ssam_dbg(ctrl, "pm: notifying D0 entry\n"); + + status = ssam_retry(ssam_ssh_notif_d0_entry, ctrl, &response); + if (status) + return status; + + if (response != 0) { + ssam_err(ctrl, "unexpected response from D0-entry notification: %#04x\n", + response); + return -EPROTO; + } + + return 0; +} + + +/* -- Top-level event registry interface. ----------------------------------- */ + +/** + * ssam_notifier_register() - Register an event notifier. + * @ctrl: The controller to register the notifier on. + * @n: The event notifier to register. + * + * Register an event notifier and increment the usage counter of the + * associated SAM event. If the event was previously not enabled, it will be + * enabled during this call. + * + * Return: Returns zero on success, %-ENOSPC if there have already been + * %INT_MAX notifiers for the event ID/type associated with the notifier block + * registered, %-ENOMEM if the corresponding event entry could not be + * allocated. If this is the first time that a notifier block is registered + * for the specific associated event, returns the status of the event-enable + * EC-command. + */ +int ssam_notifier_register(struct ssam_controller *ctrl, + struct ssam_event_notifier *n) +{ + u16 rqid = ssh_tc_to_rqid(n->event.id.target_category); + struct ssam_nf_refcount_entry *entry; + struct ssam_nf_head *nf_head; + struct ssam_nf *nf; + int status; + + if (!ssh_rqid_is_event(rqid)) + return -EINVAL; + + nf = &ctrl->cplt.event.notif; + nf_head = &nf->head[ssh_rqid_to_event(rqid)]; + + mutex_lock(&nf->lock); + + entry = ssam_nf_refcount_inc(nf, n->event.reg, n->event.id); + if (IS_ERR(entry)) { + mutex_unlock(&nf->lock); + return PTR_ERR(entry); + } + + ssam_dbg(ctrl, "enabling event (reg: %#04x, tc: %#04x, iid: %#04x, rc: %d)\n", + n->event.reg.target_category, n->event.id.target_category, + n->event.id.instance, entry->refcount); + + status = ssam_nfblk_insert(nf_head, &n->base); + if (status) { + entry = ssam_nf_refcount_dec(nf, n->event.reg, n->event.id); + if (entry->refcount == 0) + kfree(entry); + + mutex_unlock(&nf->lock); + return status; + } + + if (entry->refcount == 1) { + status = ssam_ssh_event_enable(ctrl, n->event.reg, n->event.id, + n->event.flags); + if (status) { + ssam_nfblk_remove(&n->base); + kfree(ssam_nf_refcount_dec(nf, n->event.reg, n->event.id)); + mutex_unlock(&nf->lock); + synchronize_srcu(&nf_head->srcu); + return status; + } + + entry->flags = n->event.flags; + + } else if (entry->flags != n->event.flags) { + ssam_warn(ctrl, + "inconsistent flags when enabling event: got %#04x, expected %#04x (reg: %#04x, tc: %#04x, iid: %#04x)\n", + n->event.flags, entry->flags, n->event.reg.target_category, + n->event.id.target_category, n->event.id.instance); + } + + mutex_unlock(&nf->lock); + return 0; +} +EXPORT_SYMBOL_GPL(ssam_notifier_register); + +/** + * ssam_notifier_unregister() - Unregister an event notifier. + * @ctrl: The controller the notifier has been registered on. + * @n: The event notifier to unregister. + * + * Unregister an event notifier and decrement the usage counter of the + * associated SAM event. If the usage counter reaches zero, the event will be + * disabled. + * + * Return: Returns zero on success, %-ENOENT if the given notifier block has + * not been registered on the controller. If the given notifier block was the + * last one associated with its specific event, returns the status of the + * event-disable EC-command. + */ +int ssam_notifier_unregister(struct ssam_controller *ctrl, + struct ssam_event_notifier *n) +{ + u16 rqid = ssh_tc_to_rqid(n->event.id.target_category); + struct ssam_nf_refcount_entry *entry; + struct ssam_nf_head *nf_head; + struct ssam_nf *nf; + int status = 0; + + if (!ssh_rqid_is_event(rqid)) + return -EINVAL; + + nf = &ctrl->cplt.event.notif; + nf_head = &nf->head[ssh_rqid_to_event(rqid)]; + + mutex_lock(&nf->lock); + + if (!ssam_nfblk_find(nf_head, &n->base)) { + mutex_unlock(&nf->lock); + return -ENOENT; + } + + entry = ssam_nf_refcount_dec(nf, n->event.reg, n->event.id); + if (WARN_ON(!entry)) { + /* + * If this does not return an entry, there's a logic error + * somewhere: The notifier block is registered, but the event + * refcount entry is not there. Remove the notifier block + * anyways. + */ + status = -ENOENT; + goto remove; + } + + ssam_dbg(ctrl, "disabling event (reg: %#04x, tc: %#04x, iid: %#04x, rc: %d)\n", + n->event.reg.target_category, n->event.id.target_category, + n->event.id.instance, entry->refcount); + + if (entry->flags != n->event.flags) { + ssam_warn(ctrl, + "inconsistent flags when disabling event: got %#04x, expected %#04x (reg: %#04x, tc: %#04x, iid: %#04x)\n", + n->event.flags, entry->flags, n->event.reg.target_category, + n->event.id.target_category, n->event.id.instance); + } + + if (entry->refcount == 0) { + status = ssam_ssh_event_disable(ctrl, n->event.reg, n->event.id, + n->event.flags); + kfree(entry); + } + +remove: + ssam_nfblk_remove(&n->base); + mutex_unlock(&nf->lock); + synchronize_srcu(&nf_head->srcu); + + return status; +} +EXPORT_SYMBOL_GPL(ssam_notifier_unregister); + +/** + * ssam_notifier_disable_registered() - Disable events for all registered + * notifiers. + * @ctrl: The controller for which to disable the notifiers/events. + * + * Disables events for all currently registered notifiers. In case of an error + * (EC command failing), all previously disabled events will be restored and + * the error code returned. + * + * This function is intended to disable all events prior to hibernation entry. + * See ssam_notifier_restore_registered() to restore/re-enable all events + * disabled with this function. + * + * Note that this function will not disable events for notifiers registered + * after calling this function. It should thus be made sure that no new + * notifiers are going to be added after this call and before the corresponding + * call to ssam_notifier_restore_registered(). + * + * Return: Returns zero on success. In case of failure returns the error code + * returned by the failed EC command to disable an event. + */ +int ssam_notifier_disable_registered(struct ssam_controller *ctrl) +{ + struct ssam_nf *nf = &ctrl->cplt.event.notif; + struct rb_node *n; + int status; + + mutex_lock(&nf->lock); + for (n = rb_first(&nf->refcount); n; n = rb_next(n)) { + struct ssam_nf_refcount_entry *e; + + e = rb_entry(n, struct ssam_nf_refcount_entry, node); + status = ssam_ssh_event_disable(ctrl, e->key.reg, + e->key.id, e->flags); + if (status) + goto err; + } + mutex_unlock(&nf->lock); + + return 0; + +err: + for (n = rb_prev(n); n; n = rb_prev(n)) { + struct ssam_nf_refcount_entry *e; + + e = rb_entry(n, struct ssam_nf_refcount_entry, node); + ssam_ssh_event_enable(ctrl, e->key.reg, e->key.id, e->flags); + } + mutex_unlock(&nf->lock); + + return status; +} + +/** + * ssam_notifier_restore_registered() - Restore/re-enable events for all + * registered notifiers. + * @ctrl: The controller for which to restore the notifiers/events. + * + * Restores/re-enables all events for which notifiers have been registered on + * the given controller. In case of a failure, the error is logged and the + * function continues to try and enable the remaining events. + * + * This function is intended to restore/re-enable all registered events after + * hibernation. See ssam_notifier_disable_registered() for the counter part + * disabling the events and more details. + */ +void ssam_notifier_restore_registered(struct ssam_controller *ctrl) +{ + struct ssam_nf *nf = &ctrl->cplt.event.notif; + struct rb_node *n; + + mutex_lock(&nf->lock); + for (n = rb_first(&nf->refcount); n; n = rb_next(n)) { + struct ssam_nf_refcount_entry *e; + + e = rb_entry(n, struct ssam_nf_refcount_entry, node); + + /* Ignore errors, will get logged in call. */ + ssam_ssh_event_enable(ctrl, e->key.reg, e->key.id, e->flags); + } + mutex_unlock(&nf->lock); +} + +/** + * ssam_notifier_is_empty() - Check if there are any registered notifiers. + * @ctrl: The controller to check on. + * + * Return: Returns %true if there are currently no notifiers registered on the + * controller, %false otherwise. + */ +static bool ssam_notifier_is_empty(struct ssam_controller *ctrl) +{ + struct ssam_nf *nf = &ctrl->cplt.event.notif; + bool result; + + mutex_lock(&nf->lock); + result = ssam_nf_refcount_empty(nf); + mutex_unlock(&nf->lock); + + return result; +} + +/** + * ssam_notifier_unregister_all() - Unregister all currently registered + * notifiers. + * @ctrl: The controller to unregister the notifiers on. + * + * Unregisters all currently registered notifiers. This function is used to + * ensure that all notifiers will be unregistered and associated + * entries/resources freed when the controller is being shut down. + */ +static void ssam_notifier_unregister_all(struct ssam_controller *ctrl) +{ + struct ssam_nf *nf = &ctrl->cplt.event.notif; + struct ssam_nf_refcount_entry *e, *n; + + mutex_lock(&nf->lock); + rbtree_postorder_for_each_entry_safe(e, n, &nf->refcount, node) { + /* Ignore errors, will get logged in call. */ + ssam_ssh_event_disable(ctrl, e->key.reg, e->key.id, e->flags); + kfree(e); + } + nf->refcount = RB_ROOT; + mutex_unlock(&nf->lock); +} + + +/* -- Wakeup IRQ. ----------------------------------------------------------- */ + +static irqreturn_t ssam_irq_handle(int irq, void *dev_id) +{ + struct ssam_controller *ctrl = dev_id; + + ssam_dbg(ctrl, "pm: wake irq triggered\n"); + + /* + * Note: Proper wakeup detection is currently unimplemented. + * When the EC is in display-off or any other non-D0 state, it + * does not send events/notifications to the host. Instead it + * signals that there are events available via the wakeup IRQ. + * This driver is responsible for calling back to the EC to + * release these events one-by-one. + * + * This IRQ should not cause a full system resume by its own. + * Instead, events should be handled by their respective subsystem + * drivers, which in turn should signal whether a full system + * resume should be performed. + * + * TODO: Send GPIO callback command repeatedly to EC until callback + * returns 0x00. Return flag of callback is "has more events". + * Each time the command is sent, one event is "released". Once + * all events have been released (return = 0x00), the GPIO is + * re-armed. Detect wakeup events during this process, go back to + * sleep if no wakeup event has been received. + */ + + return IRQ_HANDLED; +} + +/** + * ssam_irq_setup() - Set up SAM EC wakeup-GPIO interrupt. + * @ctrl: The controller for which the IRQ should be set up. + * + * Set up an IRQ for the wakeup-GPIO pin of the SAM EC. This IRQ can be used + * to wake the device from a low power state. + * + * Note that this IRQ can only be triggered while the EC is in the display-off + * state. In this state, events are not sent to the host in the usual way. + * Instead the wakeup-GPIO gets pulled to "high" as long as there are pending + * events and these events need to be released one-by-one via the GPIO + * callback request, either until there are no events left and the GPIO is + * reset, or all at once by transitioning the EC out of the display-off state, + * which will also clear the GPIO. + * + * Not all events, however, should trigger a full system wakeup. Instead the + * driver should, if necessary, inspect and forward each event to the + * corresponding subsystem, which in turn should decide if the system needs to + * be woken up. This logic has not been implemented yet, thus wakeup by this + * IRQ should be disabled by default to avoid spurious wake-ups, caused, for + * example, by the remaining battery percentage changing. Refer to comments in + * this function and comments in the corresponding IRQ handler for more + * details on how this should be implemented. + * + * See also ssam_ctrl_notif_display_off() and ssam_ctrl_notif_display_off() + * for functions to transition the EC into and out of the display-off state as + * well as more details on it. + * + * The IRQ is disabled by default and has to be enabled before it can wake up + * the device from suspend via ssam_irq_arm_for_wakeup(). On teardown, the IRQ + * should be freed via ssam_irq_free(). + */ +int ssam_irq_setup(struct ssam_controller *ctrl) +{ + struct device *dev = ssam_controller_device(ctrl); + struct gpio_desc *gpiod; + int irq; + int status; + + /* + * The actual GPIO interrupt is declared in ACPI as TRIGGER_HIGH. + * However, the GPIO line only gets reset by sending the GPIO callback + * command to SAM (or alternatively the display-on notification). As + * proper handling for this interrupt is not implemented yet, leaving + * the IRQ at TRIGGER_HIGH would cause an IRQ storm (as the callback + * never gets sent and thus the line never gets reset). To avoid this, + * mark the IRQ as TRIGGER_RISING for now, only creating a single + * interrupt, and let the SAM resume callback during the controller + * resume process clear it. + */ + const int irqf = IRQF_SHARED | IRQF_ONESHOT | IRQF_TRIGGER_RISING; + + gpiod = gpiod_get(dev, "ssam_wakeup-int", GPIOD_ASIS); + if (IS_ERR(gpiod)) + return PTR_ERR(gpiod); + + irq = gpiod_to_irq(gpiod); + gpiod_put(gpiod); + + if (irq < 0) + return irq; + + status = request_threaded_irq(irq, NULL, ssam_irq_handle, irqf, + "ssam_wakeup", ctrl); + if (status) + return status; + + ctrl->irq.num = irq; + disable_irq(ctrl->irq.num); + return 0; +} + +/** + * ssam_irq_free() - Free SAM EC wakeup-GPIO interrupt. + * @ctrl: The controller for which the IRQ should be freed. + * + * Free the wakeup-GPIO IRQ previously set-up via ssam_irq_setup(). + */ +void ssam_irq_free(struct ssam_controller *ctrl) +{ + free_irq(ctrl->irq.num, ctrl); + ctrl->irq.num = -1; +} + +/** + * ssam_irq_arm_for_wakeup() - Arm the EC IRQ for wakeup, if enabled. + * @ctrl: The controller for which the IRQ should be armed. + * + * Sets up the IRQ so that it can be used to wake the device. Specifically, + * this function enables the irq and then, if the device is allowed to wake up + * the system, calls enable_irq_wake(). See ssam_irq_disarm_wakeup() for the + * corresponding function to disable the IRQ. + * + * This function is intended to arm the IRQ before entering S2idle suspend. + * + * Note: calls to ssam_irq_arm_for_wakeup() and ssam_irq_disarm_wakeup() must + * be balanced. + */ +int ssam_irq_arm_for_wakeup(struct ssam_controller *ctrl) +{ + struct device *dev = ssam_controller_device(ctrl); + int status; + + enable_irq(ctrl->irq.num); + if (device_may_wakeup(dev)) { + status = enable_irq_wake(ctrl->irq.num); + if (status) { + ssam_err(ctrl, "failed to enable wake IRQ: %d\n", status); + disable_irq(ctrl->irq.num); + return status; + } + + ctrl->irq.wakeup_enabled = true; + } else { + ctrl->irq.wakeup_enabled = false; + } + + return 0; +} + +/** + * ssam_irq_disarm_wakeup() - Disarm the wakeup IRQ. + * @ctrl: The controller for which the IRQ should be disarmed. + * + * Disarm the IRQ previously set up for wake via ssam_irq_arm_for_wakeup(). + * + * This function is intended to disarm the IRQ after exiting S2idle suspend. + * + * Note: calls to ssam_irq_arm_for_wakeup() and ssam_irq_disarm_wakeup() must + * be balanced. + */ +void ssam_irq_disarm_wakeup(struct ssam_controller *ctrl) +{ + int status; + + if (ctrl->irq.wakeup_enabled) { + status = disable_irq_wake(ctrl->irq.num); + if (status) + ssam_err(ctrl, "failed to disable wake IRQ: %d\n", status); + + ctrl->irq.wakeup_enabled = false; + } + disable_irq(ctrl->irq.num); +} diff --git a/drivers/platform/surface/aggregator/controller.h b/drivers/platform/surface/aggregator/controller.h new file mode 100644 index 000000000000..5ee9e966f1d7 --- /dev/null +++ b/drivers/platform/surface/aggregator/controller.h @@ -0,0 +1,276 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * Main SSAM/SSH controller structure and functionality. + * + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#ifndef _SURFACE_AGGREGATOR_CONTROLLER_H +#define _SURFACE_AGGREGATOR_CONTROLLER_H + +#include <linux/kref.h> +#include <linux/list.h> +#include <linux/mutex.h> +#include <linux/rbtree.h> +#include <linux/rwsem.h> +#include <linux/serdev.h> +#include <linux/spinlock.h> +#include <linux/srcu.h> +#include <linux/types.h> +#include <linux/workqueue.h> + +#include <linux/surface_aggregator/controller.h> +#include <linux/surface_aggregator/serial_hub.h> + +#include "ssh_request_layer.h" + + +/* -- Safe counters. -------------------------------------------------------- */ + +/** + * struct ssh_seq_counter - Safe counter for SSH sequence IDs. + * @value: The current counter value. + */ +struct ssh_seq_counter { + u8 value; +}; + +/** + * struct ssh_rqid_counter - Safe counter for SSH request IDs. + * @value: The current counter value. + */ +struct ssh_rqid_counter { + u16 value; +}; + + +/* -- Event/notification system. -------------------------------------------- */ + +/** + * struct ssam_nf_head - Notifier head for SSAM events. + * @srcu: The SRCU struct for synchronization. + * @head: List-head for notifier blocks registered under this head. + */ +struct ssam_nf_head { + struct srcu_struct srcu; + struct list_head head; +}; + +/** + * struct ssam_nf - Notifier callback- and activation-registry for SSAM events. + * @lock: Lock guarding (de-)registration of notifier blocks. Note: This + * lock does not need to be held for notifier calls, only + * registration and deregistration. + * @refcount: The root of the RB-tree used for reference-counting enabled + * events/notifications. + * @head: The list of notifier heads for event/notification callbacks. + */ +struct ssam_nf { + struct mutex lock; + struct rb_root refcount; + struct ssam_nf_head head[SSH_NUM_EVENTS]; +}; + + +/* -- Event/async request completion system. -------------------------------- */ + +struct ssam_cplt; + +/** + * struct ssam_event_item - Struct for event queuing and completion. + * @node: The node in the queue. + * @rqid: The request ID of the event. + * @event: Actual event data. + */ +struct ssam_event_item { + struct list_head node; + u16 rqid; + + struct ssam_event event; /* must be last */ +}; + +/** + * struct ssam_event_queue - Queue for completing received events. + * @cplt: Reference to the completion system on which this queue is active. + * @lock: The lock for any operation on the queue. + * @head: The list-head of the queue. + * @work: The &struct work_struct performing completion work for this queue. + */ +struct ssam_event_queue { + struct ssam_cplt *cplt; + + spinlock_t lock; + struct list_head head; + struct work_struct work; +}; + +/** + * struct ssam_event_target - Set of queues for a single SSH target ID. + * @queue: The array of queues, one queue per event ID. + */ +struct ssam_event_target { + struct ssam_event_queue queue[SSH_NUM_EVENTS]; +}; + +/** + * struct ssam_cplt - SSAM event/async request completion system. + * @dev: The device with which this system is associated. Only used + * for logging. + * @wq: The &struct workqueue_struct on which all completion work + * items are queued. + * @event: Event completion management. + * @event.target: Array of &struct ssam_event_target, one for each target. + * @event.notif: Notifier callbacks and event activation reference counting. + */ +struct ssam_cplt { + struct device *dev; + struct workqueue_struct *wq; + + struct { + struct ssam_event_target target[SSH_NUM_TARGETS]; + struct ssam_nf notif; + } event; +}; + + +/* -- Main SSAM device structures. ------------------------------------------ */ + +/** + * enum ssam_controller_state - State values for &struct ssam_controller. + * @SSAM_CONTROLLER_UNINITIALIZED: + * The controller has not been initialized yet or has been deinitialized. + * @SSAM_CONTROLLER_INITIALIZED: + * The controller is initialized, but has not been started yet. + * @SSAM_CONTROLLER_STARTED: + * The controller has been started and is ready to use. + * @SSAM_CONTROLLER_STOPPED: + * The controller has been stopped. + * @SSAM_CONTROLLER_SUSPENDED: + * The controller has been suspended. + */ +enum ssam_controller_state { + SSAM_CONTROLLER_UNINITIALIZED, + SSAM_CONTROLLER_INITIALIZED, + SSAM_CONTROLLER_STARTED, + SSAM_CONTROLLER_STOPPED, + SSAM_CONTROLLER_SUSPENDED, +}; + +/** + * struct ssam_controller_caps - Controller device capabilities. + * @ssh_power_profile: SSH power profile. + * @ssh_buffer_size: SSH driver UART buffer size. + * @screen_on_sleep_idle_timeout: SAM UART screen-on sleep idle timeout. + * @screen_off_sleep_idle_timeout: SAM UART screen-off sleep idle timeout. + * @d3_closes_handle: SAM closes UART handle in D3. + * + * Controller and SSH device capabilities found in ACPI. + */ +struct ssam_controller_caps { + u32 ssh_power_profile; + u32 ssh_buffer_size; + u32 screen_on_sleep_idle_timeout; + u32 screen_off_sleep_idle_timeout; + u32 d3_closes_handle:1; +}; + +/** + * struct ssam_controller - SSAM controller device. + * @kref: Reference count of the controller. + * @lock: Main lock for the controller, used to guard state changes. + * @state: Controller state. + * @rtl: Request transport layer for SSH I/O. + * @cplt: Completion system for SSH/SSAM events and asynchronous requests. + * @counter: Safe SSH message ID counters. + * @counter.seq: Sequence ID counter. + * @counter.rqid: Request ID counter. + * @irq: Wakeup IRQ resources. + * @irq.num: The wakeup IRQ number. + * @irq.wakeup_enabled: Whether wakeup by IRQ is enabled during suspend. + * @caps: The controller device capabilities. + */ +struct ssam_controller { + struct kref kref; + + struct rw_semaphore lock; + enum ssam_controller_state state; + + struct ssh_rtl rtl; + struct ssam_cplt cplt; + + struct { + struct ssh_seq_counter seq; + struct ssh_rqid_counter rqid; + } counter; + + struct { + int num; + bool wakeup_enabled; + } irq; + + struct ssam_controller_caps caps; +}; + +#define to_ssam_controller(ptr, member) \ + container_of(ptr, struct ssam_controller, member) + +#define ssam_dbg(ctrl, fmt, ...) rtl_dbg(&(ctrl)->rtl, fmt, ##__VA_ARGS__) +#define ssam_info(ctrl, fmt, ...) rtl_info(&(ctrl)->rtl, fmt, ##__VA_ARGS__) +#define ssam_warn(ctrl, fmt, ...) rtl_warn(&(ctrl)->rtl, fmt, ##__VA_ARGS__) +#define ssam_err(ctrl, fmt, ...) rtl_err(&(ctrl)->rtl, fmt, ##__VA_ARGS__) + +/** + * ssam_controller_receive_buf() - Provide input-data to the controller. + * @ctrl: The controller. + * @buf: The input buffer. + * @n: The number of bytes in the input buffer. + * + * Provide input data to be evaluated by the controller, which has been + * received via the lower-level transport. + * + * Return: Returns the number of bytes consumed, or, if the packet transport + * layer of the controller has been shut down, %-ESHUTDOWN. + */ +static inline +int ssam_controller_receive_buf(struct ssam_controller *ctrl, + const unsigned char *buf, size_t n) +{ + return ssh_ptl_rx_rcvbuf(&ctrl->rtl.ptl, buf, n); +} + +/** + * ssam_controller_write_wakeup() - Notify the controller that the underlying + * device has space available for data to be written. + * @ctrl: The controller. + */ +static inline void ssam_controller_write_wakeup(struct ssam_controller *ctrl) +{ + ssh_ptl_tx_wakeup_transfer(&ctrl->rtl.ptl); +} + +int ssam_controller_init(struct ssam_controller *ctrl, struct serdev_device *s); +int ssam_controller_start(struct ssam_controller *ctrl); +void ssam_controller_shutdown(struct ssam_controller *ctrl); +void ssam_controller_destroy(struct ssam_controller *ctrl); + +int ssam_notifier_disable_registered(struct ssam_controller *ctrl); +void ssam_notifier_restore_registered(struct ssam_controller *ctrl); + +int ssam_irq_setup(struct ssam_controller *ctrl); +void ssam_irq_free(struct ssam_controller *ctrl); +int ssam_irq_arm_for_wakeup(struct ssam_controller *ctrl); +void ssam_irq_disarm_wakeup(struct ssam_controller *ctrl); + +void ssam_controller_lock(struct ssam_controller *c); +void ssam_controller_unlock(struct ssam_controller *c); + +int ssam_get_firmware_version(struct ssam_controller *ctrl, u32 *version); +int ssam_ctrl_notif_display_off(struct ssam_controller *ctrl); +int ssam_ctrl_notif_display_on(struct ssam_controller *ctrl); +int ssam_ctrl_notif_d0_exit(struct ssam_controller *ctrl); +int ssam_ctrl_notif_d0_entry(struct ssam_controller *ctrl); + +int ssam_controller_suspend(struct ssam_controller *ctrl); +int ssam_controller_resume(struct ssam_controller *ctrl); + +#endif /* _SURFACE_AGGREGATOR_CONTROLLER_H */ diff --git a/drivers/platform/surface/aggregator/core.c b/drivers/platform/surface/aggregator/core.c new file mode 100644 index 000000000000..18e0e9e34e7b --- /dev/null +++ b/drivers/platform/surface/aggregator/core.c @@ -0,0 +1,787 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Surface Serial Hub (SSH) driver for communication with the Surface/System + * Aggregator Module (SSAM/SAM). + * + * Provides access to a SAM-over-SSH connected EC via a controller device. + * Handles communication via requests as well as enabling, disabling, and + * relaying of events. + * + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#include <linux/acpi.h> +#include <linux/atomic.h> +#include <linux/completion.h> +#include <linux/gpio/consumer.h> +#include <linux/kernel.h> +#include <linux/kref.h> +#include <linux/module.h> +#include <linux/pm.h> +#include <linux/serdev.h> +#include <linux/sysfs.h> + +#include <linux/surface_aggregator/controller.h> +#include "controller.h" + + +/* -- Static controller reference. ------------------------------------------ */ + +/* + * Main controller reference. The corresponding lock must be held while + * accessing (reading/writing) the reference. + */ +static struct ssam_controller *__ssam_controller; +static DEFINE_SPINLOCK(__ssam_controller_lock); + +/** + * ssam_get_controller() - Get reference to SSAM controller. + * + * Returns a reference to the SSAM controller of the system or %NULL if there + * is none, it hasn't been set up yet, or it has already been unregistered. + * This function automatically increments the reference count of the + * controller, thus the calling party must ensure that ssam_controller_put() + * is called when it doesn't need the controller any more. + */ +struct ssam_controller *ssam_get_controller(void) +{ + struct ssam_controller *ctrl; + + spin_lock(&__ssam_controller_lock); + + ctrl = __ssam_controller; + if (!ctrl) + goto out; + + if (WARN_ON(!kref_get_unless_zero(&ctrl->kref))) + ctrl = NULL; + +out: + spin_unlock(&__ssam_controller_lock); + return ctrl; +} +EXPORT_SYMBOL_GPL(ssam_get_controller); + +/** + * ssam_try_set_controller() - Try to set the main controller reference. + * @ctrl: The controller to which the reference should point. + * + * Set the main controller reference to the given pointer if the reference + * hasn't been set already. + * + * Return: Returns zero on success or %-EEXIST if the reference has already + * been set. + */ +static int ssam_try_set_controller(struct ssam_controller *ctrl) +{ + int status = 0; + + spin_lock(&__ssam_controller_lock); + if (!__ssam_controller) + __ssam_controller = ctrl; + else + status = -EEXIST; + spin_unlock(&__ssam_controller_lock); + + return status; +} + +/** + * ssam_clear_controller() - Remove/clear the main controller reference. + * + * Clears the main controller reference, i.e. sets it to %NULL. This function + * should be called before the controller is shut down. + */ +static void ssam_clear_controller(void) +{ + spin_lock(&__ssam_controller_lock); + __ssam_controller = NULL; + spin_unlock(&__ssam_controller_lock); +} + +/** + * ssam_client_link() - Link an arbitrary client device to the controller. + * @c: The controller to link to. + * @client: The client device. + * + * Link an arbitrary client device to the controller by creating a device link + * between it as consumer and the controller device as provider. This function + * can be used for non-SSAM devices (or SSAM devices not registered as child + * under the controller) to guarantee that the controller is valid for as long + * as the driver of the client device is bound, and that proper suspend and + * resume ordering is guaranteed. + * + * The device link does not have to be destructed manually. It is removed + * automatically once the driver of the client device unbinds. + * + * Return: Returns zero on success, %-ENODEV if the controller is not ready or + * going to be removed soon, or %-ENOMEM if the device link could not be + * created for other reasons. + */ +int ssam_client_link(struct ssam_controller *c, struct device *client) +{ + const u32 flags = DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_CONSUMER; + struct device_link *link; + struct device *ctrldev; + + ssam_controller_statelock(c); + + if (c->state != SSAM_CONTROLLER_STARTED) { + ssam_controller_stateunlock(c); + return -ENODEV; + } + + ctrldev = ssam_controller_device(c); + if (!ctrldev) { + ssam_controller_stateunlock(c); + return -ENODEV; + } + + link = device_link_add(client, ctrldev, flags); + if (!link) { + ssam_controller_stateunlock(c); + return -ENOMEM; + } + + /* + * Return -ENODEV if supplier driver is on its way to be removed. In + * this case, the controller won't be around for much longer and the + * device link is not going to save us any more, as unbinding is + * already in progress. + */ + if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND) { + ssam_controller_stateunlock(c); + return -ENODEV; + } + + ssam_controller_stateunlock(c); + return 0; +} +EXPORT_SYMBOL_GPL(ssam_client_link); + +/** + * ssam_client_bind() - Bind an arbitrary client device to the controller. + * @client: The client device. + * + * Link an arbitrary client device to the controller by creating a device link + * between it as consumer and the main controller device as provider. This + * function can be used for non-SSAM devices to guarantee that the controller + * returned by this function is valid for as long as the driver of the client + * device is bound, and that proper suspend and resume ordering is guaranteed. + * + * This function does essentially the same as ssam_client_link(), except that + * it first fetches the main controller reference, then creates the link, and + * finally returns this reference. Note that this function does not increment + * the reference counter of the controller, as, due to the link, the + * controller lifetime is assured as long as the driver of the client device + * is bound. + * + * It is not valid to use the controller reference obtained by this method + * outside of the driver bound to the client device at the time of calling + * this function, without first incrementing the reference count of the + * controller via ssam_controller_get(). Even after doing this, care must be + * taken that requests are only submitted and notifiers are only + * (un-)registered when the controller is active and not suspended. In other + * words: The device link only lives as long as the client driver is bound and + * any guarantees enforced by this link (e.g. active controller state) can + * only be relied upon as long as this link exists and may need to be enforced + * in other ways afterwards. + * + * The created device link does not have to be destructed manually. It is + * removed automatically once the driver of the client device unbinds. + * + * Return: Returns the controller on success, an error pointer with %-ENODEV + * if the controller is not present, not ready or going to be removed soon, or + * %-ENOMEM if the device link could not be created for other reasons. + */ +struct ssam_controller *ssam_client_bind(struct device *client) +{ + struct ssam_controller *c; + int status; + + c = ssam_get_controller(); + if (!c) + return ERR_PTR(-ENODEV); + + status = ssam_client_link(c, client); + + /* + * Note that we can drop our controller reference in both success and + * failure cases: On success, we have bound the controller lifetime + * inherently to the client driver lifetime, i.e. it the controller is + * now guaranteed to outlive the client driver. On failure, we're not + * going to use the controller any more. + */ + ssam_controller_put(c); + + return status >= 0 ? c : ERR_PTR(status); +} +EXPORT_SYMBOL_GPL(ssam_client_bind); + + +/* -- Glue layer (serdev_device -> ssam_controller). ------------------------ */ + +static int ssam_receive_buf(struct serdev_device *dev, const unsigned char *buf, + size_t n) +{ + struct ssam_controller *ctrl; + + ctrl = serdev_device_get_drvdata(dev); + return ssam_controller_receive_buf(ctrl, buf, n); +} + +static void ssam_write_wakeup(struct serdev_device *dev) +{ + ssam_controller_write_wakeup(serdev_device_get_drvdata(dev)); +} + +static const struct serdev_device_ops ssam_serdev_ops = { + .receive_buf = ssam_receive_buf, + .write_wakeup = ssam_write_wakeup, +}; + + +/* -- SysFS and misc. ------------------------------------------------------- */ + +static int ssam_log_firmware_version(struct ssam_controller *ctrl) +{ + u32 version, a, b, c; + int status; + + status = ssam_get_firmware_version(ctrl, &version); + if (status) + return status; + + a = (version >> 24) & 0xff; + b = ((version >> 8) & 0xffff); + c = version & 0xff; + + ssam_info(ctrl, "SAM firmware version: %u.%u.%u\n", a, b, c); + return 0; +} + +static ssize_t firmware_version_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct ssam_controller *ctrl = dev_get_drvdata(dev); + u32 version, a, b, c; + int status; + + status = ssam_get_firmware_version(ctrl, &version); + if (status < 0) + return status; + + a = (version >> 24) & 0xff; + b = ((version >> 8) & 0xffff); + c = version & 0xff; + + return sysfs_emit(buf, "%u.%u.%u\n", a, b, c); +} +static DEVICE_ATTR_RO(firmware_version); + +static struct attribute *ssam_sam_attrs[] = { + &dev_attr_firmware_version.attr, + NULL +}; + +static const struct attribute_group ssam_sam_group = { + .name = "sam", + .attrs = ssam_sam_attrs, +}; + + +/* -- ACPI based device setup. ---------------------------------------------- */ + +static acpi_status ssam_serdev_setup_via_acpi_crs(struct acpi_resource *rsc, + void *ctx) +{ + struct serdev_device *serdev = ctx; + struct acpi_resource_common_serialbus *serial; + struct acpi_resource_uart_serialbus *uart; + bool flow_control; + int status = 0; + + if (rsc->type != ACPI_RESOURCE_TYPE_SERIAL_BUS) + return AE_OK; + + serial = &rsc->data.common_serial_bus; + if (serial->type != ACPI_RESOURCE_SERIAL_TYPE_UART) + return AE_OK; + + uart = &rsc->data.uart_serial_bus; + + /* Set up serdev device. */ + serdev_device_set_baudrate(serdev, uart->default_baud_rate); + + /* serdev currently only supports RTSCTS flow control. */ + if (uart->flow_control & (~((u8)ACPI_UART_FLOW_CONTROL_HW))) { + dev_warn(&serdev->dev, "setup: unsupported flow control (value: %#04x)\n", + uart->flow_control); + } + + /* Set RTSCTS flow control. */ + flow_control = uart->flow_control & ACPI_UART_FLOW_CONTROL_HW; + serdev_device_set_flow_control(serdev, flow_control); + + /* serdev currently only supports EVEN/ODD parity. */ + switch (uart->parity) { + case ACPI_UART_PARITY_NONE: + status = serdev_device_set_parity(serdev, SERDEV_PARITY_NONE); + break; + case ACPI_UART_PARITY_EVEN: + status = serdev_device_set_parity(serdev, SERDEV_PARITY_EVEN); + break; + case ACPI_UART_PARITY_ODD: + status = serdev_device_set_parity(serdev, SERDEV_PARITY_ODD); + break; + default: + dev_warn(&serdev->dev, "setup: unsupported parity (value: %#04x)\n", + uart->parity); + break; + } + + if (status) { + dev_err(&serdev->dev, "setup: failed to set parity (value: %#04x, error: %d)\n", + uart->parity, status); + return AE_ERROR; + } + + /* We've found the resource and are done. */ + return AE_CTRL_TERMINATE; +} + +static acpi_status ssam_serdev_setup_via_acpi(acpi_handle handle, + struct serdev_device *serdev) +{ + return acpi_walk_resources(handle, METHOD_NAME__CRS, + ssam_serdev_setup_via_acpi_crs, serdev); +} + + +/* -- Power management. ----------------------------------------------------- */ + +static void ssam_serial_hub_shutdown(struct device *dev) +{ + struct ssam_controller *c = dev_get_drvdata(dev); + int status; + + /* + * Try to disable notifiers, signal display-off and D0-exit, ignore any + * errors. + * + * Note: It has not been established yet if this is actually + * necessary/useful for shutdown. + */ + + status = ssam_notifier_disable_registered(c); + if (status) { + ssam_err(c, "pm: failed to disable notifiers for shutdown: %d\n", + status); + } + + status = ssam_ctrl_notif_display_off(c); + if (status) + ssam_err(c, "pm: display-off notification failed: %d\n", status); + + status = ssam_ctrl_notif_d0_exit(c); + if (status) + ssam_err(c, "pm: D0-exit notification failed: %d\n", status); +} + +#ifdef CONFIG_PM_SLEEP + +static int ssam_serial_hub_pm_prepare(struct device *dev) +{ + struct ssam_controller *c = dev_get_drvdata(dev); + int status; + + /* + * Try to signal display-off, This will quiesce events. + * + * Note: Signaling display-off/display-on should normally be done from + * some sort of display state notifier. As that is not available, + * signal it here. + */ + + status = ssam_ctrl_notif_display_off(c); + if (status) + ssam_err(c, "pm: display-off notification failed: %d\n", status); + + return status; +} + +static void ssam_serial_hub_pm_complete(struct device *dev) +{ + struct ssam_controller *c = dev_get_drvdata(dev); + int status; + + /* + * Try to signal display-on. This will restore events. + * + * Note: Signaling display-off/display-on should normally be done from + * some sort of display state notifier. As that is not available, + * signal it here. + */ + + status = ssam_ctrl_notif_display_on(c); + if (status) + ssam_err(c, "pm: display-on notification failed: %d\n", status); +} + +static int ssam_serial_hub_pm_suspend(struct device *dev) +{ + struct ssam_controller *c = dev_get_drvdata(dev); + int status; + + /* + * Try to signal D0-exit, enable IRQ wakeup if specified. Abort on + * error. + */ + + status = ssam_ctrl_notif_d0_exit(c); + if (status) { + ssam_err(c, "pm: D0-exit notification failed: %d\n", status); + goto err_notif; + } + + status = ssam_irq_arm_for_wakeup(c); + if (status) + goto err_irq; + + WARN_ON(ssam_controller_suspend(c)); + return 0; + +err_irq: + ssam_ctrl_notif_d0_entry(c); +err_notif: + ssam_ctrl_notif_display_on(c); + return status; +} + +static int ssam_serial_hub_pm_resume(struct device *dev) +{ + struct ssam_controller *c = dev_get_drvdata(dev); + int status; + + WARN_ON(ssam_controller_resume(c)); + + /* + * Try to disable IRQ wakeup (if specified) and signal D0-entry. In + * case of errors, log them and try to restore normal operation state + * as far as possible. + * + * Note: Signaling display-off/display-on should normally be done from + * some sort of display state notifier. As that is not available, + * signal it here. + */ + + ssam_irq_disarm_wakeup(c); + + status = ssam_ctrl_notif_d0_entry(c); + if (status) + ssam_err(c, "pm: D0-entry notification failed: %d\n", status); + + return 0; +} + +static int ssam_serial_hub_pm_freeze(struct device *dev) +{ + struct ssam_controller *c = dev_get_drvdata(dev); + int status; + + /* + * During hibernation image creation, we only have to ensure that the + * EC doesn't send us any events. This is done via the display-off + * and D0-exit notifications. Note that this sets up the wakeup IRQ + * on the EC side, however, we have disabled it by default on our side + * and won't enable it here. + * + * See ssam_serial_hub_poweroff() for more details on the hibernation + * process. + */ + + status = ssam_ctrl_notif_d0_exit(c); + if (status) { + ssam_err(c, "pm: D0-exit notification failed: %d\n", status); + ssam_ctrl_notif_display_on(c); + return status; + } + + WARN_ON(ssam_controller_suspend(c)); + return 0; +} + +static int ssam_serial_hub_pm_thaw(struct device *dev) +{ + struct ssam_controller *c = dev_get_drvdata(dev); + int status; + + WARN_ON(ssam_controller_resume(c)); + + status = ssam_ctrl_notif_d0_entry(c); + if (status) + ssam_err(c, "pm: D0-exit notification failed: %d\n", status); + + return status; +} + +static int ssam_serial_hub_pm_poweroff(struct device *dev) +{ + struct ssam_controller *c = dev_get_drvdata(dev); + int status; + + /* + * When entering hibernation and powering off the system, the EC, at + * least on some models, may disable events. Without us taking care of + * that, this leads to events not being enabled/restored when the + * system resumes from hibernation, resulting SAM-HID subsystem devices + * (i.e. keyboard, touchpad) not working, AC-plug/AC-unplug events being + * gone, etc. + * + * To avoid these issues, we disable all registered events here (this is + * likely not actually required) and restore them during the drivers PM + * restore callback. + * + * Wakeup from the EC interrupt is not supported during hibernation, + * so don't arm the IRQ here. + */ + + status = ssam_notifier_disable_registered(c); + if (status) { + ssam_err(c, "pm: failed to disable notifiers for hibernation: %d\n", + status); + return status; + } + + status = ssam_ctrl_notif_d0_exit(c); + if (status) { + ssam_err(c, "pm: D0-exit notification failed: %d\n", status); + ssam_notifier_restore_registered(c); + return status; + } + + WARN_ON(ssam_controller_suspend(c)); + return 0; +} + +static int ssam_serial_hub_pm_restore(struct device *dev) +{ + struct ssam_controller *c = dev_get_drvdata(dev); + int status; + + /* + * Ignore but log errors, try to restore state as much as possible in + * case of failures. See ssam_serial_hub_poweroff() for more details on + * the hibernation process. + */ + + WARN_ON(ssam_controller_resume(c)); + + status = ssam_ctrl_notif_d0_entry(c); + if (status) + ssam_err(c, "pm: D0-entry notification failed: %d\n", status); + + ssam_notifier_restore_registered(c); + return 0; +} + +static const struct dev_pm_ops ssam_serial_hub_pm_ops = { + .prepare = ssam_serial_hub_pm_prepare, + .complete = ssam_serial_hub_pm_complete, + .suspend = ssam_serial_hub_pm_suspend, + .resume = ssam_serial_hub_pm_resume, + .freeze = ssam_serial_hub_pm_freeze, + .thaw = ssam_serial_hub_pm_thaw, + .poweroff = ssam_serial_hub_pm_poweroff, + .restore = ssam_serial_hub_pm_restore, +}; + +#else /* CONFIG_PM_SLEEP */ + +static const struct dev_pm_ops ssam_serial_hub_pm_ops = { }; + +#endif /* CONFIG_PM_SLEEP */ + + +/* -- Device/driver setup. -------------------------------------------------- */ + +static const struct acpi_gpio_params gpio_ssam_wakeup_int = { 0, 0, false }; +static const struct acpi_gpio_params gpio_ssam_wakeup = { 1, 0, false }; + +static const struct acpi_gpio_mapping ssam_acpi_gpios[] = { + { "ssam_wakeup-int-gpio", &gpio_ssam_wakeup_int, 1 }, + { "ssam_wakeup-gpio", &gpio_ssam_wakeup, 1 }, + { }, +}; + +static int ssam_serial_hub_probe(struct serdev_device *serdev) +{ + struct ssam_controller *ctrl; + acpi_handle *ssh = ACPI_HANDLE(&serdev->dev); + acpi_status astatus; + int status; + + if (gpiod_count(&serdev->dev, NULL) < 0) + return -ENODEV; + + status = devm_acpi_dev_add_driver_gpios(&serdev->dev, ssam_acpi_gpios); + if (status) + return status; + + /* Allocate controller. */ + ctrl = kzalloc(sizeof(*ctrl), GFP_KERNEL); + if (!ctrl) + return -ENOMEM; + + /* Initialize controller. */ + status = ssam_controller_init(ctrl, serdev); + if (status) + goto err_ctrl_init; + + ssam_controller_lock(ctrl); + + /* Set up serdev device. */ + serdev_device_set_drvdata(serdev, ctrl); + serdev_device_set_client_ops(serdev, &ssam_serdev_ops); + status = serdev_device_open(serdev); + if (status) + goto err_devopen; + + astatus = ssam_serdev_setup_via_acpi(ssh, serdev); + if (ACPI_FAILURE(astatus)) { + status = -ENXIO; + goto err_devinit; + } + + /* Start controller. */ + status = ssam_controller_start(ctrl); + if (status) + goto err_devinit; + + ssam_controller_unlock(ctrl); + + /* + * Initial SAM requests: Log version and notify default/init power + * states. + */ + status = ssam_log_firmware_version(ctrl); + if (status) + goto err_initrq; + + status = ssam_ctrl_notif_d0_entry(ctrl); + if (status) + goto err_initrq; + + status = ssam_ctrl_notif_display_on(ctrl); + if (status) + goto err_initrq; + + status = sysfs_create_group(&serdev->dev.kobj, &ssam_sam_group); + if (status) + goto err_initrq; + + /* Set up IRQ. */ + status = ssam_irq_setup(ctrl); + if (status) + goto err_irq; + + /* Finally, set main controller reference. */ + status = ssam_try_set_controller(ctrl); + if (WARN_ON(status)) /* Currently, we're the only provider. */ + goto err_mainref; + + /* + * TODO: The EC can wake up the system via the associated GPIO interrupt + * in multiple situations. One of which is the remaining battery + * capacity falling below a certain threshold. Normally, we should + * use the device_init_wakeup function, however, the EC also seems + * to have other reasons for waking up the system and it seems + * that Windows has additional checks whether the system should be + * resumed. In short, this causes some spurious unwanted wake-ups. + * For now let's thus default power/wakeup to false. + */ + device_set_wakeup_capable(&serdev->dev, true); + acpi_walk_dep_device_list(ssh); + + return 0; + +err_mainref: + ssam_irq_free(ctrl); +err_irq: + sysfs_remove_group(&serdev->dev.kobj, &ssam_sam_group); +err_initrq: + ssam_controller_lock(ctrl); + ssam_controller_shutdown(ctrl); +err_devinit: + serdev_device_close(serdev); +err_devopen: + ssam_controller_destroy(ctrl); + ssam_controller_unlock(ctrl); +err_ctrl_init: + kfree(ctrl); + return status; +} + +static void ssam_serial_hub_remove(struct serdev_device *serdev) +{ + struct ssam_controller *ctrl = serdev_device_get_drvdata(serdev); + int status; + + /* Clear static reference so that no one else can get a new one. */ + ssam_clear_controller(); + + /* Disable and free IRQ. */ + ssam_irq_free(ctrl); + + sysfs_remove_group(&serdev->dev.kobj, &ssam_sam_group); + ssam_controller_lock(ctrl); + + /* Act as if suspending to silence events. */ + status = ssam_ctrl_notif_display_off(ctrl); + if (status) { + dev_err(&serdev->dev, "display-off notification failed: %d\n", + status); + } + + status = ssam_ctrl_notif_d0_exit(ctrl); + if (status) { + dev_err(&serdev->dev, "D0-exit notification failed: %d\n", + status); + } + + /* Shut down controller and remove serdev device reference from it. */ + ssam_controller_shutdown(ctrl); + + /* Shut down actual transport. */ + serdev_device_wait_until_sent(serdev, 0); + serdev_device_close(serdev); + + /* Drop our controller reference. */ + ssam_controller_unlock(ctrl); + ssam_controller_put(ctrl); + + device_set_wakeup_capable(&serdev->dev, false); +} + +static const struct acpi_device_id ssam_serial_hub_match[] = { + { "MSHW0084", 0 }, + { }, +}; +MODULE_DEVICE_TABLE(acpi, ssam_serial_hub_match); + +static struct serdev_device_driver ssam_serial_hub = { + .probe = ssam_serial_hub_probe, + .remove = ssam_serial_hub_remove, + .driver = { + .name = "surface_serial_hub", + .acpi_match_table = ssam_serial_hub_match, + .pm = &ssam_serial_hub_pm_ops, + .shutdown = ssam_serial_hub_shutdown, + .probe_type = PROBE_PREFER_ASYNCHRONOUS, + }, +}; +module_serdev_device_driver(ssam_serial_hub); + +MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>"); +MODULE_DESCRIPTION("Subsystem and Surface Serial Hub driver for Surface System Aggregator Module"); +MODULE_LICENSE("GPL"); diff --git a/drivers/platform/surface/aggregator/ssh_msgb.h b/drivers/platform/surface/aggregator/ssh_msgb.h new file mode 100644 index 000000000000..1221f642dda1 --- /dev/null +++ b/drivers/platform/surface/aggregator/ssh_msgb.h @@ -0,0 +1,205 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * SSH message builder functions. + * + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#ifndef _SURFACE_AGGREGATOR_SSH_MSGB_H +#define _SURFACE_AGGREGATOR_SSH_MSGB_H + +#include <asm/unaligned.h> +#include <linux/types.h> + +#include <linux/surface_aggregator/controller.h> +#include <linux/surface_aggregator/serial_hub.h> + +/** + * struct msgbuf - Buffer struct to construct SSH messages. + * @begin: Pointer to the beginning of the allocated buffer space. + * @end: Pointer to the end (one past last element) of the allocated buffer + * space. + * @ptr: Pointer to the first free element in the buffer. + */ +struct msgbuf { + u8 *begin; + u8 *end; + u8 *ptr; +}; + +/** + * msgb_init() - Initialize the given message buffer struct. + * @msgb: The buffer struct to initialize + * @ptr: Pointer to the underlying memory by which the buffer will be backed. + * @cap: Size of the underlying memory. + * + * Initialize the given message buffer struct using the provided memory as + * backing. + */ +static inline void msgb_init(struct msgbuf *msgb, u8 *ptr, size_t cap) +{ + msgb->begin = ptr; + msgb->end = ptr + cap; + msgb->ptr = ptr; +} + +/** + * msgb_bytes_used() - Return the current number of bytes used in the buffer. + * @msgb: The message buffer. + */ +static inline size_t msgb_bytes_used(const struct msgbuf *msgb) +{ + return msgb->ptr - msgb->begin; +} + +static inline void __msgb_push_u8(struct msgbuf *msgb, u8 value) +{ + *msgb->ptr = value; + msgb->ptr += sizeof(u8); +} + +static inline void __msgb_push_u16(struct msgbuf *msgb, u16 value) +{ + put_unaligned_le16(value, msgb->ptr); + msgb->ptr += sizeof(u16); +} + +/** + * msgb_push_u16() - Push a u16 value to the buffer. + * @msgb: The message buffer. + * @value: The value to push to the buffer. + */ +static inline void msgb_push_u16(struct msgbuf *msgb, u16 value) +{ + if (WARN_ON(msgb->ptr + sizeof(u16) > msgb->end)) + return; + + __msgb_push_u16(msgb, value); +} + +/** + * msgb_push_syn() - Push SSH SYN bytes to the buffer. + * @msgb: The message buffer. + */ +static inline void msgb_push_syn(struct msgbuf *msgb) +{ + msgb_push_u16(msgb, SSH_MSG_SYN); +} + +/** + * msgb_push_buf() - Push raw data to the buffer. + * @msgb: The message buffer. + * @buf: The data to push to the buffer. + * @len: The length of the data to push to the buffer. + */ +static inline void msgb_push_buf(struct msgbuf *msgb, const u8 *buf, size_t len) +{ + msgb->ptr = memcpy(msgb->ptr, buf, len) + len; +} + +/** + * msgb_push_crc() - Compute CRC and push it to the buffer. + * @msgb: The message buffer. + * @buf: The data for which the CRC should be computed. + * @len: The length of the data for which the CRC should be computed. + */ +static inline void msgb_push_crc(struct msgbuf *msgb, const u8 *buf, size_t len) +{ + msgb_push_u16(msgb, ssh_crc(buf, len)); +} + +/** + * msgb_push_frame() - Push a SSH message frame header to the buffer. + * @msgb: The message buffer + * @ty: The type of the frame. + * @len: The length of the payload of the frame. + * @seq: The sequence ID of the frame/packet. + */ +static inline void msgb_push_frame(struct msgbuf *msgb, u8 ty, u16 len, u8 seq) +{ + u8 *const begin = msgb->ptr; + + if (WARN_ON(msgb->ptr + sizeof(struct ssh_frame) > msgb->end)) + return; + + __msgb_push_u8(msgb, ty); /* Frame type. */ + __msgb_push_u16(msgb, len); /* Frame payload length. */ + __msgb_push_u8(msgb, seq); /* Frame sequence ID. */ + + msgb_push_crc(msgb, begin, msgb->ptr - begin); +} + +/** + * msgb_push_ack() - Push a SSH ACK frame to the buffer. + * @msgb: The message buffer + * @seq: The sequence ID of the frame/packet to be ACKed. + */ +static inline void msgb_push_ack(struct msgbuf *msgb, u8 seq) +{ + /* SYN. */ + msgb_push_syn(msgb); + + /* ACK-type frame + CRC. */ + msgb_push_frame(msgb, SSH_FRAME_TYPE_ACK, 0x00, seq); + + /* Payload CRC (ACK-type frames do not have a payload). */ + msgb_push_crc(msgb, msgb->ptr, 0); +} + +/** + * msgb_push_nak() - Push a SSH NAK frame to the buffer. + * @msgb: The message buffer + */ +static inline void msgb_push_nak(struct msgbuf *msgb) +{ + /* SYN. */ + msgb_push_syn(msgb); + + /* NAK-type frame + CRC. */ + msgb_push_frame(msgb, SSH_FRAME_TYPE_NAK, 0x00, 0x00); + + /* Payload CRC (ACK-type frames do not have a payload). */ + msgb_push_crc(msgb, msgb->ptr, 0); +} + +/** + * msgb_push_cmd() - Push a SSH command frame with payload to the buffer. + * @msgb: The message buffer. + * @seq: The sequence ID (SEQ) of the frame/packet. + * @rqid: The request ID (RQID) of the request contained in the frame. + * @rqst: The request to wrap in the frame. + */ +static inline void msgb_push_cmd(struct msgbuf *msgb, u8 seq, u16 rqid, + const struct ssam_request *rqst) +{ + const u8 type = SSH_FRAME_TYPE_DATA_SEQ; + u8 *cmd; + + /* SYN. */ + msgb_push_syn(msgb); + + /* Command frame + CRC. */ + msgb_push_frame(msgb, type, sizeof(struct ssh_command) + rqst->length, seq); + + /* Frame payload: Command struct + payload. */ + if (WARN_ON(msgb->ptr + sizeof(struct ssh_command) > msgb->end)) + return; + + cmd = msgb->ptr; + + __msgb_push_u8(msgb, SSH_PLD_TYPE_CMD); /* Payload type. */ + __msgb_push_u8(msgb, rqst->target_category); /* Target category. */ + __msgb_push_u8(msgb, rqst->target_id); /* Target ID (out). */ + __msgb_push_u8(msgb, 0x00); /* Target ID (in). */ + __msgb_push_u8(msgb, rqst->instance_id); /* Instance ID. */ + __msgb_push_u16(msgb, rqid); /* Request ID. */ + __msgb_push_u8(msgb, rqst->command_id); /* Command ID. */ + + /* Command payload. */ + msgb_push_buf(msgb, rqst->payload, rqst->length); + + /* CRC for command struct + payload. */ + msgb_push_crc(msgb, cmd, msgb->ptr - cmd); +} + +#endif /* _SURFACE_AGGREGATOR_SSH_MSGB_H */ diff --git a/drivers/platform/surface/aggregator/ssh_packet_layer.c b/drivers/platform/surface/aggregator/ssh_packet_layer.c new file mode 100644 index 000000000000..66e38fdc7963 --- /dev/null +++ b/drivers/platform/surface/aggregator/ssh_packet_layer.c @@ -0,0 +1,1710 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * SSH packet transport layer. + * + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#include <asm/unaligned.h> +#include <linux/atomic.h> +#include <linux/jiffies.h> +#include <linux/kfifo.h> +#include <linux/kref.h> +#include <linux/kthread.h> +#include <linux/ktime.h> +#include <linux/limits.h> +#include <linux/list.h> +#include <linux/lockdep.h> +#include <linux/serdev.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/workqueue.h> + +#include <linux/surface_aggregator/serial_hub.h> + +#include "ssh_msgb.h" +#include "ssh_packet_layer.h" +#include "ssh_parser.h" + +/* + * To simplify reasoning about the code below, we define a few concepts. The + * system below is similar to a state-machine for packets, however, there are + * too many states to explicitly write them down. To (somewhat) manage the + * states and packets we rely on flags, reference counting, and some simple + * concepts. State transitions are triggered by actions. + * + * >> Actions << + * + * - submit + * - transmission start (process next item in queue) + * - transmission finished (guaranteed to never be parallel to transmission + * start) + * - ACK received + * - NAK received (this is equivalent to issuing re-submit for all pending + * packets) + * - timeout (this is equivalent to re-issuing a submit or canceling) + * - cancel (non-pending and pending) + * + * >> Data Structures, Packet Ownership, General Overview << + * + * The code below employs two main data structures: The packet queue, + * containing all packets scheduled for transmission, and the set of pending + * packets, containing all packets awaiting an ACK. + * + * Shared ownership of a packet is controlled via reference counting. Inside + * the transport system are a total of five packet owners: + * + * - the packet queue, + * - the pending set, + * - the transmitter thread, + * - the receiver thread (via ACKing), and + * - the timeout work item. + * + * Normal operation is as follows: The initial reference of the packet is + * obtained by submitting the packet and queuing it. The receiver thread takes + * packets from the queue. By doing this, it does not increment the refcount + * but takes over the reference (removing it from the queue). If the packet is + * sequenced (i.e. needs to be ACKed by the client), the transmitter thread + * sets-up the timeout and adds the packet to the pending set before starting + * to transmit it. As the timeout is handled by a reaper task, no additional + * reference for it is needed. After the transmit is done, the reference held + * by the transmitter thread is dropped. If the packet is unsequenced (i.e. + * does not need an ACK), the packet is completed by the transmitter thread + * before dropping that reference. + * + * On receival of an ACK, the receiver thread removes and obtains the + * reference to the packet from the pending set. The receiver thread will then + * complete the packet and drop its reference. + * + * On receival of a NAK, the receiver thread re-submits all currently pending + * packets. + * + * Packet timeouts are detected by the timeout reaper. This is a task, + * scheduled depending on the earliest packet timeout expiration date, + * checking all currently pending packets if their timeout has expired. If the + * timeout of a packet has expired, it is re-submitted and the number of tries + * of this packet is incremented. If this number reaches its limit, the packet + * will be completed with a failure. + * + * On transmission failure (such as repeated packet timeouts), the completion + * callback is immediately run by on thread on which the error was detected. + * + * To ensure that a packet eventually leaves the system it is marked as + * "locked" directly before it is going to be completed or when it is + * canceled. Marking a packet as "locked" has the effect that passing and + * creating new references of the packet is disallowed. This means that the + * packet cannot be added to the queue, the pending set, and the timeout, or + * be picked up by the transmitter thread or receiver thread. To remove a + * packet from the system it has to be marked as locked and subsequently all + * references from the data structures (queue, pending) have to be removed. + * References held by threads will eventually be dropped automatically as + * their execution progresses. + * + * Note that the packet completion callback is, in case of success and for a + * sequenced packet, guaranteed to run on the receiver thread, thus providing + * a way to reliably identify responses to the packet. The packet completion + * callback is only run once and it does not indicate that the packet has + * fully left the system (for this, one should rely on the release method, + * triggered when the reference count of the packet reaches zero). In case of + * re-submission (and with somewhat unlikely timing), it may be possible that + * the packet is being re-transmitted while the completion callback runs. + * Completion will occur both on success and internal error, as well as when + * the packet is canceled. + * + * >> Flags << + * + * Flags are used to indicate the state and progression of a packet. Some flags + * have stricter guarantees than other: + * + * - locked + * Indicates if the packet is locked. If the packet is locked, passing and/or + * creating additional references to the packet is forbidden. The packet thus + * may not be queued, dequeued, or removed or added to the pending set. Note + * that the packet state flags may still change (e.g. it may be marked as + * ACKed, transmitted, ...). + * + * - completed + * Indicates if the packet completion callback has been executed or is about + * to be executed. This flag is used to ensure that the packet completion + * callback is only run once. + * + * - queued + * Indicates if a packet is present in the submission queue or not. This flag + * must only be modified with the queue lock held, and must be coherent to the + * presence of the packet in the queue. + * + * - pending + * Indicates if a packet is present in the set of pending packets or not. + * This flag must only be modified with the pending lock held, and must be + * coherent to the presence of the packet in the pending set. + * + * - transmitting + * Indicates if the packet is currently transmitting. In case of + * re-transmissions, it is only safe to wait on the "transmitted" completion + * after this flag has been set. The completion will be set both in success + * and error case. + * + * - transmitted + * Indicates if the packet has been transmitted. This flag is not cleared by + * the system, thus it indicates the first transmission only. + * + * - acked + * Indicates if the packet has been acknowledged by the client. There are no + * other guarantees given. For example, the packet may still be canceled + * and/or the completion may be triggered an error even though this bit is + * set. Rely on the status provided to the completion callback instead. + * + * - canceled + * Indicates if the packet has been canceled from the outside. There are no + * other guarantees given. Specifically, the packet may be completed by + * another part of the system before the cancellation attempts to complete it. + * + * >> General Notes << + * + * - To avoid deadlocks, if both queue and pending locks are required, the + * pending lock must be acquired before the queue lock. + * + * - The packet priority must be accessed only while holding the queue lock. + * + * - The packet timestamp must be accessed only while holding the pending + * lock. + */ + +/* + * SSH_PTL_MAX_PACKET_TRIES - Maximum transmission attempts for packet. + * + * Maximum number of transmission attempts per sequenced packet in case of + * time-outs. Must be smaller than 16. If the packet times out after this + * amount of tries, the packet will be completed with %-ETIMEDOUT as status + * code. + */ +#define SSH_PTL_MAX_PACKET_TRIES 3 + +/* + * SSH_PTL_TX_TIMEOUT - Packet transmission timeout. + * + * Timeout in jiffies for packet transmission via the underlying serial + * device. If transmitting the packet takes longer than this timeout, the + * packet will be completed with -ETIMEDOUT. It will not be re-submitted. + */ +#define SSH_PTL_TX_TIMEOUT HZ + +/* + * SSH_PTL_PACKET_TIMEOUT - Packet response timeout. + * + * Timeout as ktime_t delta for ACKs. If we have not received an ACK in this + * time-frame after starting transmission, the packet will be re-submitted. + */ +#define SSH_PTL_PACKET_TIMEOUT ms_to_ktime(1000) + +/* + * SSH_PTL_PACKET_TIMEOUT_RESOLUTION - Packet timeout granularity. + * + * Time-resolution for timeouts. Should be larger than one jiffy to avoid + * direct re-scheduling of reaper work_struct. + */ +#define SSH_PTL_PACKET_TIMEOUT_RESOLUTION ms_to_ktime(max(2000 / HZ, 50)) + +/* + * SSH_PTL_MAX_PENDING - Maximum number of pending packets. + * + * Maximum number of sequenced packets concurrently waiting for an ACK. + * Packets marked as blocking will not be transmitted while this limit is + * reached. + */ +#define SSH_PTL_MAX_PENDING 1 + +/* + * SSH_PTL_RX_BUF_LEN - Evaluation-buffer size in bytes. + */ +#define SSH_PTL_RX_BUF_LEN 4096 + +/* + * SSH_PTL_RX_FIFO_LEN - Fifo input-buffer size in bytes. + */ +#define SSH_PTL_RX_FIFO_LEN 4096 + +static void __ssh_ptl_packet_release(struct kref *kref) +{ + struct ssh_packet *p = container_of(kref, struct ssh_packet, refcnt); + + ptl_dbg_cond(p->ptl, "ptl: releasing packet %p\n", p); + p->ops->release(p); +} + +/** + * ssh_packet_get() - Increment reference count of packet. + * @packet: The packet to increment the reference count of. + * + * Increments the reference count of the given packet. See ssh_packet_put() + * for the counter-part of this function. + * + * Return: Returns the packet provided as input. + */ +struct ssh_packet *ssh_packet_get(struct ssh_packet *packet) +{ + if (packet) + kref_get(&packet->refcnt); + return packet; +} +EXPORT_SYMBOL_GPL(ssh_packet_get); + +/** + * ssh_packet_put() - Decrement reference count of packet. + * @packet: The packet to decrement the reference count of. + * + * If the reference count reaches zero, the ``release`` callback specified in + * the packet's &struct ssh_packet_ops, i.e. ``packet->ops->release``, will be + * called. + * + * See ssh_packet_get() for the counter-part of this function. + */ +void ssh_packet_put(struct ssh_packet *packet) +{ + if (packet) + kref_put(&packet->refcnt, __ssh_ptl_packet_release); +} +EXPORT_SYMBOL_GPL(ssh_packet_put); + +static u8 ssh_packet_get_seq(struct ssh_packet *packet) +{ + return packet->data.ptr[SSH_MSGOFFSET_FRAME(seq)]; +} + +/** + * ssh_packet_init() - Initialize SSH packet. + * @packet: The packet to initialize. + * @type: Type-flags of the packet. + * @priority: Priority of the packet. See SSH_PACKET_PRIORITY() for details. + * @ops: Packet operations. + * + * Initializes the given SSH packet. Sets the transmission buffer pointer to + * %NULL and the transmission buffer length to zero. For data-type packets, + * this buffer has to be set separately via ssh_packet_set_data() before + * submission, and must contain a valid SSH message, i.e. frame with optional + * payload of any type. + */ +void ssh_packet_init(struct ssh_packet *packet, unsigned long type, + u8 priority, const struct ssh_packet_ops *ops) +{ + kref_init(&packet->refcnt); + + packet->ptl = NULL; + INIT_LIST_HEAD(&packet->queue_node); + INIT_LIST_HEAD(&packet->pending_node); + + packet->state = type & SSH_PACKET_FLAGS_TY_MASK; + packet->priority = priority; + packet->timestamp = KTIME_MAX; + + packet->data.ptr = NULL; + packet->data.len = 0; + + packet->ops = ops; +} + +/** + * ssh_ctrl_packet_alloc() - Allocate control packet. + * @packet: Where the pointer to the newly allocated packet should be stored. + * @buffer: The buffer corresponding to this packet. + * @flags: Flags used for allocation. + * + * Allocates a packet and corresponding transport buffer. Sets the packet's + * buffer reference to the allocated buffer. The packet must be freed via + * ssh_ctrl_packet_free(), which will also free the corresponding buffer. The + * corresponding buffer must not be freed separately. Intended to be used with + * %ssh_ptl_ctrl_packet_ops as packet operations. + * + * Return: Returns zero on success, %-ENOMEM if the allocation failed. + */ +static int ssh_ctrl_packet_alloc(struct ssh_packet **packet, + struct ssam_span *buffer, gfp_t flags) +{ + *packet = kzalloc(sizeof(**packet) + SSH_MSG_LEN_CTRL, flags); + if (!*packet) + return -ENOMEM; + + buffer->ptr = (u8 *)(*packet + 1); + buffer->len = SSH_MSG_LEN_CTRL; + + return 0; +} + +/** + * ssh_ctrl_packet_free() - Free control packet. + * @p: The packet to free. + */ +static void ssh_ctrl_packet_free(struct ssh_packet *p) +{ + kfree(p); +} + +static const struct ssh_packet_ops ssh_ptl_ctrl_packet_ops = { + .complete = NULL, + .release = ssh_ctrl_packet_free, +}; + +static void ssh_ptl_timeout_reaper_mod(struct ssh_ptl *ptl, ktime_t now, + ktime_t expires) +{ + unsigned long delta = msecs_to_jiffies(ktime_ms_delta(expires, now)); + ktime_t aexp = ktime_add(expires, SSH_PTL_PACKET_TIMEOUT_RESOLUTION); + + spin_lock(&ptl->rtx_timeout.lock); + + /* Re-adjust / schedule reaper only if it is above resolution delta. */ + if (ktime_before(aexp, ptl->rtx_timeout.expires)) { + ptl->rtx_timeout.expires = expires; + mod_delayed_work(system_wq, &ptl->rtx_timeout.reaper, delta); + } + + spin_unlock(&ptl->rtx_timeout.lock); +} + +/* Must be called with queue lock held. */ +static void ssh_packet_next_try(struct ssh_packet *p) +{ + u8 base = ssh_packet_priority_get_base(p->priority); + u8 try = ssh_packet_priority_get_try(p->priority); + + lockdep_assert_held(&p->ptl->queue.lock); + + p->priority = __SSH_PACKET_PRIORITY(base, try + 1); +} + +/* Must be called with queue lock held. */ +static struct list_head *__ssh_ptl_queue_find_entrypoint(struct ssh_packet *p) +{ + struct list_head *head; + struct ssh_packet *q; + + lockdep_assert_held(&p->ptl->queue.lock); + + /* + * We generally assume that there are less control (ACK/NAK) packets + * and re-submitted data packets as there are normal data packets (at + * least in situations in which many packets are queued; if there + * aren't many packets queued the decision on how to iterate should be + * basically irrelevant; the number of control/data packets is more or + * less limited via the maximum number of pending packets). Thus, when + * inserting a control or re-submitted data packet, (determined by + * their priority), we search from front to back. Normal data packets + * are, usually queued directly at the tail of the queue, so for those + * search from back to front. + */ + + if (p->priority > SSH_PACKET_PRIORITY(DATA, 0)) { + list_for_each(head, &p->ptl->queue.head) { + q = list_entry(head, struct ssh_packet, queue_node); + + if (q->priority < p->priority) + break; + } + } else { + list_for_each_prev(head, &p->ptl->queue.head) { + q = list_entry(head, struct ssh_packet, queue_node); + + if (q->priority >= p->priority) { + head = head->next; + break; + } + } + } + + return head; +} + +/* Must be called with queue lock held. */ +static int __ssh_ptl_queue_push(struct ssh_packet *packet) +{ + struct ssh_ptl *ptl = packet->ptl; + struct list_head *head; + + lockdep_assert_held(&ptl->queue.lock); + + if (test_bit(SSH_PTL_SF_SHUTDOWN_BIT, &ptl->state)) + return -ESHUTDOWN; + + /* Avoid further transitions when canceling/completing. */ + if (test_bit(SSH_PACKET_SF_LOCKED_BIT, &packet->state)) + return -EINVAL; + + /* If this packet has already been queued, do not add it. */ + if (test_and_set_bit(SSH_PACKET_SF_QUEUED_BIT, &packet->state)) + return -EALREADY; + + head = __ssh_ptl_queue_find_entrypoint(packet); + + list_add_tail(&ssh_packet_get(packet)->queue_node, head); + return 0; +} + +static int ssh_ptl_queue_push(struct ssh_packet *packet) +{ + int status; + + spin_lock(&packet->ptl->queue.lock); + status = __ssh_ptl_queue_push(packet); + spin_unlock(&packet->ptl->queue.lock); + + return status; +} + +static void ssh_ptl_queue_remove(struct ssh_packet *packet) +{ + struct ssh_ptl *ptl = packet->ptl; + + spin_lock(&ptl->queue.lock); + + if (!test_and_clear_bit(SSH_PACKET_SF_QUEUED_BIT, &packet->state)) { + spin_unlock(&ptl->queue.lock); + return; + } + + list_del(&packet->queue_node); + + spin_unlock(&ptl->queue.lock); + ssh_packet_put(packet); +} + +static void ssh_ptl_pending_push(struct ssh_packet *p) +{ + struct ssh_ptl *ptl = p->ptl; + const ktime_t timestamp = ktime_get_coarse_boottime(); + const ktime_t timeout = ptl->rtx_timeout.timeout; + + /* + * Note: We can get the time for the timestamp before acquiring the + * lock as this is the only place we're setting it and this function + * is called only from the transmitter thread. Thus it is not possible + * to overwrite the timestamp with an outdated value below. + */ + + spin_lock(&ptl->pending.lock); + + /* If we are canceling/completing this packet, do not add it. */ + if (test_bit(SSH_PACKET_SF_LOCKED_BIT, &p->state)) { + spin_unlock(&ptl->pending.lock); + return; + } + + /* + * On re-submission, the packet has already been added the pending + * set. We still need to update the timestamp as the packet timeout is + * reset for each (re-)submission. + */ + p->timestamp = timestamp; + + /* In case it is already pending (e.g. re-submission), do not add it. */ + if (!test_and_set_bit(SSH_PACKET_SF_PENDING_BIT, &p->state)) { + atomic_inc(&ptl->pending.count); + list_add_tail(&ssh_packet_get(p)->pending_node, &ptl->pending.head); + } + + spin_unlock(&ptl->pending.lock); + + /* Arm/update timeout reaper. */ + ssh_ptl_timeout_reaper_mod(ptl, timestamp, timestamp + timeout); +} + +static void ssh_ptl_pending_remove(struct ssh_packet *packet) +{ + struct ssh_ptl *ptl = packet->ptl; + + spin_lock(&ptl->pending.lock); + + if (!test_and_clear_bit(SSH_PACKET_SF_PENDING_BIT, &packet->state)) { + spin_unlock(&ptl->pending.lock); + return; + } + + list_del(&packet->pending_node); + atomic_dec(&ptl->pending.count); + + spin_unlock(&ptl->pending.lock); + + ssh_packet_put(packet); +} + +/* Warning: Does not check/set "completed" bit. */ +static void __ssh_ptl_complete(struct ssh_packet *p, int status) +{ + struct ssh_ptl *ptl = READ_ONCE(p->ptl); + + ptl_dbg_cond(ptl, "ptl: completing packet %p (status: %d)\n", p, status); + + if (p->ops->complete) + p->ops->complete(p, status); +} + +static void ssh_ptl_remove_and_complete(struct ssh_packet *p, int status) +{ + /* + * A call to this function should in general be preceded by + * set_bit(SSH_PACKET_SF_LOCKED_BIT, &p->flags) to avoid re-adding the + * packet to the structures it's going to be removed from. + * + * The set_bit call does not need explicit memory barriers as the + * implicit barrier of the test_and_set_bit() call below ensure that the + * flag is visible before we actually attempt to remove the packet. + */ + + if (test_and_set_bit(SSH_PACKET_SF_COMPLETED_BIT, &p->state)) + return; + + ssh_ptl_queue_remove(p); + ssh_ptl_pending_remove(p); + + __ssh_ptl_complete(p, status); +} + +static bool ssh_ptl_tx_can_process(struct ssh_packet *packet) +{ + struct ssh_ptl *ptl = packet->ptl; + + if (test_bit(SSH_PACKET_TY_FLUSH_BIT, &packet->state)) + return !atomic_read(&ptl->pending.count); + + /* We can always process non-blocking packets. */ + if (!test_bit(SSH_PACKET_TY_BLOCKING_BIT, &packet->state)) + return true; + + /* If we are already waiting for this packet, send it again. */ + if (test_bit(SSH_PACKET_SF_PENDING_BIT, &packet->state)) + return true; + + /* Otherwise: Check if we have the capacity to send. */ + return atomic_read(&ptl->pending.count) < SSH_PTL_MAX_PENDING; +} + +static struct ssh_packet *ssh_ptl_tx_pop(struct ssh_ptl *ptl) +{ + struct ssh_packet *packet = ERR_PTR(-ENOENT); + struct ssh_packet *p, *n; + + spin_lock(&ptl->queue.lock); + list_for_each_entry_safe(p, n, &ptl->queue.head, queue_node) { + /* + * If we are canceling or completing this packet, ignore it. + * It's going to be removed from this queue shortly. + */ + if (test_bit(SSH_PACKET_SF_LOCKED_BIT, &p->state)) + continue; + + /* + * Packets should be ordered non-blocking/to-be-resent first. + * If we cannot process this packet, assume that we can't + * process any following packet either and abort. + */ + if (!ssh_ptl_tx_can_process(p)) { + packet = ERR_PTR(-EBUSY); + break; + } + + /* + * We are allowed to change the state now. Remove it from the + * queue and mark it as being transmitted. + */ + + list_del(&p->queue_node); + + set_bit(SSH_PACKET_SF_TRANSMITTING_BIT, &p->state); + /* Ensure that state never gets zero. */ + smp_mb__before_atomic(); + clear_bit(SSH_PACKET_SF_QUEUED_BIT, &p->state); + + /* + * Update number of tries. This directly influences the + * priority in case the packet is re-submitted (e.g. via + * timeout/NAK). Note that all reads and writes to the + * priority after the first submission are guarded by the + * queue lock. + */ + ssh_packet_next_try(p); + + packet = p; + break; + } + spin_unlock(&ptl->queue.lock); + + return packet; +} + +static struct ssh_packet *ssh_ptl_tx_next(struct ssh_ptl *ptl) +{ + struct ssh_packet *p; + + p = ssh_ptl_tx_pop(ptl); + if (IS_ERR(p)) + return p; + + if (test_bit(SSH_PACKET_TY_SEQUENCED_BIT, &p->state)) { + ptl_dbg(ptl, "ptl: transmitting sequenced packet %p\n", p); + ssh_ptl_pending_push(p); + } else { + ptl_dbg(ptl, "ptl: transmitting non-sequenced packet %p\n", p); + } + + return p; +} + +static void ssh_ptl_tx_compl_success(struct ssh_packet *packet) +{ + struct ssh_ptl *ptl = packet->ptl; + + ptl_dbg(ptl, "ptl: successfully transmitted packet %p\n", packet); + + /* Transition state to "transmitted". */ + set_bit(SSH_PACKET_SF_TRANSMITTED_BIT, &packet->state); + /* Ensure that state never gets zero. */ + smp_mb__before_atomic(); + clear_bit(SSH_PACKET_SF_TRANSMITTING_BIT, &packet->state); + + /* If the packet is unsequenced, we're done: Lock and complete. */ + if (!test_bit(SSH_PACKET_TY_SEQUENCED_BIT, &packet->state)) { + set_bit(SSH_PACKET_SF_LOCKED_BIT, &packet->state); + ssh_ptl_remove_and_complete(packet, 0); + } + + /* + * Notify that a packet transmission has finished. In general we're only + * waiting for one packet (if any), so wake_up_all should be fine. + */ + wake_up_all(&ptl->tx.packet_wq); +} + +static void ssh_ptl_tx_compl_error(struct ssh_packet *packet, int status) +{ + /* Transmission failure: Lock the packet and try to complete it. */ + set_bit(SSH_PACKET_SF_LOCKED_BIT, &packet->state); + /* Ensure that state never gets zero. */ + smp_mb__before_atomic(); + clear_bit(SSH_PACKET_SF_TRANSMITTING_BIT, &packet->state); + + ptl_err(packet->ptl, "ptl: transmission error: %d\n", status); + ptl_dbg(packet->ptl, "ptl: failed to transmit packet: %p\n", packet); + + ssh_ptl_remove_and_complete(packet, status); + + /* + * Notify that a packet transmission has finished. In general we're only + * waiting for one packet (if any), so wake_up_all should be fine. + */ + wake_up_all(&packet->ptl->tx.packet_wq); +} + +static long ssh_ptl_tx_wait_packet(struct ssh_ptl *ptl) +{ + int status; + + status = wait_for_completion_interruptible(&ptl->tx.thread_cplt_pkt); + reinit_completion(&ptl->tx.thread_cplt_pkt); + + /* + * Ensure completion is cleared before continuing to avoid lost update + * problems. + */ + smp_mb__after_atomic(); + + return status; +} + +static long ssh_ptl_tx_wait_transfer(struct ssh_ptl *ptl, long timeout) +{ + long status; + + status = wait_for_completion_interruptible_timeout(&ptl->tx.thread_cplt_tx, + timeout); + reinit_completion(&ptl->tx.thread_cplt_tx); + + /* + * Ensure completion is cleared before continuing to avoid lost update + * problems. + */ + smp_mb__after_atomic(); + + return status; +} + +static int ssh_ptl_tx_packet(struct ssh_ptl *ptl, struct ssh_packet *packet) +{ + long timeout = SSH_PTL_TX_TIMEOUT; + size_t offset = 0; + + /* Note: Flush-packets don't have any data. */ + if (unlikely(!packet->data.ptr)) + return 0; + + ptl_dbg(ptl, "tx: sending data (length: %zu)\n", packet->data.len); + print_hex_dump_debug("tx: ", DUMP_PREFIX_OFFSET, 16, 1, + packet->data.ptr, packet->data.len, false); + + do { + ssize_t status, len; + u8 *buf; + + buf = packet->data.ptr + offset; + len = packet->data.len - offset; + + status = serdev_device_write_buf(ptl->serdev, buf, len); + if (status < 0) + return status; + + if (status == len) + return 0; + + offset += status; + + timeout = ssh_ptl_tx_wait_transfer(ptl, timeout); + if (kthread_should_stop() || !atomic_read(&ptl->tx.running)) + return -ESHUTDOWN; + + if (timeout < 0) + return -EINTR; + + if (timeout == 0) + return -ETIMEDOUT; + } while (true); +} + +static int ssh_ptl_tx_threadfn(void *data) +{ + struct ssh_ptl *ptl = data; + + while (!kthread_should_stop() && atomic_read(&ptl->tx.running)) { + struct ssh_packet *packet; + int status; + + /* Try to get the next packet. */ + packet = ssh_ptl_tx_next(ptl); + + /* If no packet can be processed, we are done. */ + if (IS_ERR(packet)) { + ssh_ptl_tx_wait_packet(ptl); + continue; + } + + /* Transfer and complete packet. */ + status = ssh_ptl_tx_packet(ptl, packet); + if (status) + ssh_ptl_tx_compl_error(packet, status); + else + ssh_ptl_tx_compl_success(packet); + + ssh_packet_put(packet); + } + + return 0; +} + +/** + * ssh_ptl_tx_wakeup_packet() - Wake up packet transmitter thread for new + * packet. + * @ptl: The packet transport layer. + * + * Wakes up the packet transmitter thread, notifying it that a new packet has + * arrived and is ready for transfer. If the packet transport layer has been + * shut down, calls to this function will be ignored. + */ +static void ssh_ptl_tx_wakeup_packet(struct ssh_ptl *ptl) +{ + if (test_bit(SSH_PTL_SF_SHUTDOWN_BIT, &ptl->state)) + return; + + complete(&ptl->tx.thread_cplt_pkt); +} + +/** + * ssh_ptl_tx_start() - Start packet transmitter thread. + * @ptl: The packet transport layer. + * + * Return: Returns zero on success, a negative error code on failure. + */ +int ssh_ptl_tx_start(struct ssh_ptl *ptl) +{ + atomic_set_release(&ptl->tx.running, 1); + + ptl->tx.thread = kthread_run(ssh_ptl_tx_threadfn, ptl, "ssam_serial_hub-tx"); + if (IS_ERR(ptl->tx.thread)) + return PTR_ERR(ptl->tx.thread); + + return 0; +} + +/** + * ssh_ptl_tx_stop() - Stop packet transmitter thread. + * @ptl: The packet transport layer. + * + * Return: Returns zero on success, a negative error code on failure. + */ +int ssh_ptl_tx_stop(struct ssh_ptl *ptl) +{ + int status = 0; + + if (!IS_ERR_OR_NULL(ptl->tx.thread)) { + /* Tell thread to stop. */ + atomic_set_release(&ptl->tx.running, 0); + + /* + * Wake up thread in case it is paused. Do not use wakeup + * helpers as this may be called when the shutdown bit has + * already been set. + */ + complete(&ptl->tx.thread_cplt_pkt); + complete(&ptl->tx.thread_cplt_tx); + + /* Finally, wait for thread to stop. */ + status = kthread_stop(ptl->tx.thread); + ptl->tx.thread = NULL; + } + + return status; +} + +static struct ssh_packet *ssh_ptl_ack_pop(struct ssh_ptl *ptl, u8 seq_id) +{ + struct ssh_packet *packet = ERR_PTR(-ENOENT); + struct ssh_packet *p, *n; + + spin_lock(&ptl->pending.lock); + list_for_each_entry_safe(p, n, &ptl->pending.head, pending_node) { + /* + * We generally expect packets to be in order, so first packet + * to be added to pending is first to be sent, is first to be + * ACKed. + */ + if (unlikely(ssh_packet_get_seq(p) != seq_id)) + continue; + + /* + * In case we receive an ACK while handling a transmission + * error completion. The packet will be removed shortly. + */ + if (unlikely(test_bit(SSH_PACKET_SF_LOCKED_BIT, &p->state))) { + packet = ERR_PTR(-EPERM); + break; + } + + /* + * Mark the packet as ACKed and remove it from pending by + * removing its node and decrementing the pending counter. + */ + set_bit(SSH_PACKET_SF_ACKED_BIT, &p->state); + /* Ensure that state never gets zero. */ + smp_mb__before_atomic(); + clear_bit(SSH_PACKET_SF_PENDING_BIT, &p->state); + + atomic_dec(&ptl->pending.count); + list_del(&p->pending_node); + packet = p; + + break; + } + spin_unlock(&ptl->pending.lock); + + return packet; +} + +static void ssh_ptl_wait_until_transmitted(struct ssh_packet *packet) +{ + wait_event(packet->ptl->tx.packet_wq, + test_bit(SSH_PACKET_SF_TRANSMITTED_BIT, &packet->state) || + test_bit(SSH_PACKET_SF_LOCKED_BIT, &packet->state)); +} + +static void ssh_ptl_acknowledge(struct ssh_ptl *ptl, u8 seq) +{ + struct ssh_packet *p; + + p = ssh_ptl_ack_pop(ptl, seq); + if (IS_ERR(p)) { + if (PTR_ERR(p) == -ENOENT) { + /* + * The packet has not been found in the set of pending + * packets. + */ + ptl_warn(ptl, "ptl: received ACK for non-pending packet\n"); + } else { + /* + * The packet is pending, but we are not allowed to take + * it because it has been locked. + */ + WARN_ON(PTR_ERR(p) != -EPERM); + } + return; + } + + ptl_dbg(ptl, "ptl: received ACK for packet %p\n", p); + + /* + * It is possible that the packet has been transmitted, but the state + * has not been updated from "transmitting" to "transmitted" yet. + * In that case, we need to wait for this transition to occur in order + * to determine between success or failure. + * + * On transmission failure, the packet will be locked after this call. + * On success, the transmitted bit will be set. + */ + ssh_ptl_wait_until_transmitted(p); + + /* + * The packet will already be locked in case of a transmission error or + * cancellation. Let the transmitter or cancellation issuer complete the + * packet. + */ + if (unlikely(test_and_set_bit(SSH_PACKET_SF_LOCKED_BIT, &p->state))) { + if (unlikely(!test_bit(SSH_PACKET_SF_TRANSMITTED_BIT, &p->state))) + ptl_err(ptl, "ptl: received ACK before packet had been fully transmitted\n"); + + ssh_packet_put(p); + return; + } + + ssh_ptl_remove_and_complete(p, 0); + ssh_packet_put(p); + + if (atomic_read(&ptl->pending.count) < SSH_PTL_MAX_PENDING) + ssh_ptl_tx_wakeup_packet(ptl); +} + +/** + * ssh_ptl_submit() - Submit a packet to the transport layer. + * @ptl: The packet transport layer to submit the packet to. + * @p: The packet to submit. + * + * Submits a new packet to the transport layer, queuing it to be sent. This + * function should not be used for re-submission. + * + * Return: Returns zero on success, %-EINVAL if a packet field is invalid or + * the packet has been canceled prior to submission, %-EALREADY if the packet + * has already been submitted, or %-ESHUTDOWN if the packet transport layer + * has been shut down. + */ +int ssh_ptl_submit(struct ssh_ptl *ptl, struct ssh_packet *p) +{ + struct ssh_ptl *ptl_old; + int status; + + /* Validate packet fields. */ + if (test_bit(SSH_PACKET_TY_FLUSH_BIT, &p->state)) { + if (p->data.ptr || test_bit(SSH_PACKET_TY_SEQUENCED_BIT, &p->state)) + return -EINVAL; + } else if (!p->data.ptr) { + return -EINVAL; + } + + /* + * The ptl reference only gets set on or before the first submission. + * After the first submission, it has to be read-only. + * + * Note that ptl may already be set from upper-layer request + * submission, thus we cannot expect it to be NULL. + */ + ptl_old = READ_ONCE(p->ptl); + if (!ptl_old) + WRITE_ONCE(p->ptl, ptl); + else if (WARN_ON(ptl_old != ptl)) + return -EALREADY; /* Submitted on different PTL. */ + + status = ssh_ptl_queue_push(p); + if (status) + return status; + + if (!test_bit(SSH_PACKET_TY_BLOCKING_BIT, &p->state) || + (atomic_read(&ptl->pending.count) < SSH_PTL_MAX_PENDING)) + ssh_ptl_tx_wakeup_packet(ptl); + + return 0; +} + +/* + * __ssh_ptl_resubmit() - Re-submit a packet to the transport layer. + * @packet: The packet to re-submit. + * + * Re-submits the given packet: Checks if it can be re-submitted and queues it + * if it can, resetting the packet timestamp in the process. Must be called + * with the pending lock held. + * + * Return: Returns %-ECANCELED if the packet has exceeded its number of tries, + * %-EINVAL if the packet has been locked, %-EALREADY if the packet is already + * on the queue, and %-ESHUTDOWN if the transmission layer has been shut down. + */ +static int __ssh_ptl_resubmit(struct ssh_packet *packet) +{ + int status; + u8 try; + + lockdep_assert_held(&packet->ptl->pending.lock); + + spin_lock(&packet->ptl->queue.lock); + + /* Check if the packet is out of tries. */ + try = ssh_packet_priority_get_try(packet->priority); + if (try >= SSH_PTL_MAX_PACKET_TRIES) { + spin_unlock(&packet->ptl->queue.lock); + return -ECANCELED; + } + + status = __ssh_ptl_queue_push(packet); + if (status) { + /* + * An error here indicates that the packet has either already + * been queued, been locked, or the transport layer is being + * shut down. In all cases: Ignore the error. + */ + spin_unlock(&packet->ptl->queue.lock); + return status; + } + + packet->timestamp = KTIME_MAX; + + spin_unlock(&packet->ptl->queue.lock); + return 0; +} + +static void ssh_ptl_resubmit_pending(struct ssh_ptl *ptl) +{ + struct ssh_packet *p; + bool resub = false; + + /* + * Note: We deliberately do not remove/attempt to cancel and complete + * packets that are out of tires in this function. The packet will be + * eventually canceled and completed by the timeout. Removing the packet + * here could lead to overly eager cancellation if the packet has not + * been re-transmitted yet but the tries-counter already updated (i.e + * ssh_ptl_tx_next() removed the packet from the queue and updated the + * counter, but re-transmission for the last try has not actually + * started yet). + */ + + spin_lock(&ptl->pending.lock); + + /* Re-queue all pending packets. */ + list_for_each_entry(p, &ptl->pending.head, pending_node) { + /* + * Re-submission fails if the packet is out of tries, has been + * locked, is already queued, or the layer is being shut down. + * No need to re-schedule tx-thread in those cases. + */ + if (!__ssh_ptl_resubmit(p)) + resub = true; + } + + spin_unlock(&ptl->pending.lock); + + if (resub) + ssh_ptl_tx_wakeup_packet(ptl); +} + +/** + * ssh_ptl_cancel() - Cancel a packet. + * @p: The packet to cancel. + * + * Cancels a packet. There are no guarantees on when completion and release + * callbacks will be called. This may occur during execution of this function + * or may occur at any point later. + * + * Note that it is not guaranteed that the packet will actually be canceled if + * the packet is concurrently completed by another process. The only guarantee + * of this function is that the packet will be completed (with success, + * failure, or cancellation) and released from the transport layer in a + * reasonable time-frame. + * + * May be called before the packet has been submitted, in which case any later + * packet submission fails. + */ +void ssh_ptl_cancel(struct ssh_packet *p) +{ + if (test_and_set_bit(SSH_PACKET_SF_CANCELED_BIT, &p->state)) + return; + + /* + * Lock packet and commit with memory barrier. If this packet has + * already been locked, it's going to be removed and completed by + * another party, which should have precedence. + */ + if (test_and_set_bit(SSH_PACKET_SF_LOCKED_BIT, &p->state)) + return; + + /* + * By marking the packet as locked and employing the implicit memory + * barrier of test_and_set_bit, we have guaranteed that, at this point, + * the packet cannot be added to the queue any more. + * + * In case the packet has never been submitted, packet->ptl is NULL. If + * the packet is currently being submitted, packet->ptl may be NULL or + * non-NULL. Due marking the packet as locked above and committing with + * the memory barrier, we have guaranteed that, if packet->ptl is NULL, + * the packet will never be added to the queue. If packet->ptl is + * non-NULL, we don't have any guarantees. + */ + + if (READ_ONCE(p->ptl)) { + ssh_ptl_remove_and_complete(p, -ECANCELED); + + if (atomic_read(&p->ptl->pending.count) < SSH_PTL_MAX_PENDING) + ssh_ptl_tx_wakeup_packet(p->ptl); + + } else if (!test_and_set_bit(SSH_PACKET_SF_COMPLETED_BIT, &p->state)) { + __ssh_ptl_complete(p, -ECANCELED); + } +} + +/* Must be called with pending lock held */ +static ktime_t ssh_packet_get_expiration(struct ssh_packet *p, ktime_t timeout) +{ + lockdep_assert_held(&p->ptl->pending.lock); + + if (p->timestamp != KTIME_MAX) + return ktime_add(p->timestamp, timeout); + else + return KTIME_MAX; +} + +static void ssh_ptl_timeout_reap(struct work_struct *work) +{ + struct ssh_ptl *ptl = to_ssh_ptl(work, rtx_timeout.reaper.work); + struct ssh_packet *p, *n; + LIST_HEAD(claimed); + ktime_t now = ktime_get_coarse_boottime(); + ktime_t timeout = ptl->rtx_timeout.timeout; + ktime_t next = KTIME_MAX; + bool resub = false; + int status; + + /* + * Mark reaper as "not pending". This is done before checking any + * packets to avoid lost-update type problems. + */ + spin_lock(&ptl->rtx_timeout.lock); + ptl->rtx_timeout.expires = KTIME_MAX; + spin_unlock(&ptl->rtx_timeout.lock); + + spin_lock(&ptl->pending.lock); + + list_for_each_entry_safe(p, n, &ptl->pending.head, pending_node) { + ktime_t expires = ssh_packet_get_expiration(p, timeout); + + /* + * Check if the timeout hasn't expired yet. Find out next + * expiration date to be handled after this run. + */ + if (ktime_after(expires, now)) { + next = ktime_before(expires, next) ? expires : next; + continue; + } + + status = __ssh_ptl_resubmit(p); + + /* + * Re-submission fails if the packet is out of tries, has been + * locked, is already queued, or the layer is being shut down. + * No need to re-schedule tx-thread in those cases. + */ + if (!status) + resub = true; + + /* Go to next packet if this packet is not out of tries. */ + if (status != -ECANCELED) + continue; + + /* No more tries left: Cancel the packet. */ + + /* + * If someone else has locked the packet already, don't use it + * and let the other party complete it. + */ + if (test_and_set_bit(SSH_PACKET_SF_LOCKED_BIT, &p->state)) + continue; + + /* + * We have now marked the packet as locked. Thus it cannot be + * added to the pending list again after we've removed it here. + * We can therefore re-use the pending_node of this packet + * temporarily. + */ + + clear_bit(SSH_PACKET_SF_PENDING_BIT, &p->state); + + atomic_dec(&ptl->pending.count); + list_del(&p->pending_node); + + list_add_tail(&p->pending_node, &claimed); + } + + spin_unlock(&ptl->pending.lock); + + /* Cancel and complete the packet. */ + list_for_each_entry_safe(p, n, &claimed, pending_node) { + if (!test_and_set_bit(SSH_PACKET_SF_COMPLETED_BIT, &p->state)) { + ssh_ptl_queue_remove(p); + __ssh_ptl_complete(p, -ETIMEDOUT); + } + + /* + * Drop the reference we've obtained by removing it from + * the pending set. + */ + list_del(&p->pending_node); + ssh_packet_put(p); + } + + /* Ensure that reaper doesn't run again immediately. */ + next = max(next, ktime_add(now, SSH_PTL_PACKET_TIMEOUT_RESOLUTION)); + if (next != KTIME_MAX) + ssh_ptl_timeout_reaper_mod(ptl, now, next); + + if (resub) + ssh_ptl_tx_wakeup_packet(ptl); +} + +static bool ssh_ptl_rx_retransmit_check(struct ssh_ptl *ptl, u8 seq) +{ + int i; + + /* + * Check if SEQ has been seen recently (i.e. packet was + * re-transmitted and we should ignore it). + */ + for (i = 0; i < ARRAY_SIZE(ptl->rx.blocked.seqs); i++) { + if (likely(ptl->rx.blocked.seqs[i] != seq)) + continue; + + ptl_dbg(ptl, "ptl: ignoring repeated data packet\n"); + return true; + } + + /* Update list of blocked sequence IDs. */ + ptl->rx.blocked.seqs[ptl->rx.blocked.offset] = seq; + ptl->rx.blocked.offset = (ptl->rx.blocked.offset + 1) + % ARRAY_SIZE(ptl->rx.blocked.seqs); + + return false; +} + +static void ssh_ptl_rx_dataframe(struct ssh_ptl *ptl, + const struct ssh_frame *frame, + const struct ssam_span *payload) +{ + if (ssh_ptl_rx_retransmit_check(ptl, frame->seq)) + return; + + ptl->ops.data_received(ptl, payload); +} + +static void ssh_ptl_send_ack(struct ssh_ptl *ptl, u8 seq) +{ + struct ssh_packet *packet; + struct ssam_span buf; + struct msgbuf msgb; + int status; + + status = ssh_ctrl_packet_alloc(&packet, &buf, GFP_KERNEL); + if (status) { + ptl_err(ptl, "ptl: failed to allocate ACK packet\n"); + return; + } + + ssh_packet_init(packet, 0, SSH_PACKET_PRIORITY(ACK, 0), + &ssh_ptl_ctrl_packet_ops); + + msgb_init(&msgb, buf.ptr, buf.len); + msgb_push_ack(&msgb, seq); + ssh_packet_set_data(packet, msgb.begin, msgb_bytes_used(&msgb)); + + ssh_ptl_submit(ptl, packet); + ssh_packet_put(packet); +} + +static void ssh_ptl_send_nak(struct ssh_ptl *ptl) +{ + struct ssh_packet *packet; + struct ssam_span buf; + struct msgbuf msgb; + int status; + + status = ssh_ctrl_packet_alloc(&packet, &buf, GFP_KERNEL); + if (status) { + ptl_err(ptl, "ptl: failed to allocate NAK packet\n"); + return; + } + + ssh_packet_init(packet, 0, SSH_PACKET_PRIORITY(NAK, 0), + &ssh_ptl_ctrl_packet_ops); + + msgb_init(&msgb, buf.ptr, buf.len); + msgb_push_nak(&msgb); + ssh_packet_set_data(packet, msgb.begin, msgb_bytes_used(&msgb)); + + ssh_ptl_submit(ptl, packet); + ssh_packet_put(packet); +} + +static size_t ssh_ptl_rx_eval(struct ssh_ptl *ptl, struct ssam_span *source) +{ + struct ssh_frame *frame; + struct ssam_span payload; + struct ssam_span aligned; + bool syn_found; + int status; + + /* Find SYN. */ + syn_found = sshp_find_syn(source, &aligned); + + if (unlikely(aligned.ptr - source->ptr) > 0) { + ptl_warn(ptl, "rx: parser: invalid start of frame, skipping\n"); + + /* + * Notes: + * - This might send multiple NAKs in case the communication + * starts with an invalid SYN and is broken down into multiple + * pieces. This should generally be handled fine, we just + * might receive duplicate data in this case, which is + * detected when handling data frames. + * - This path will also be executed on invalid CRCs: When an + * invalid CRC is encountered, the code below will skip data + * until directly after the SYN. This causes the search for + * the next SYN, which is generally not placed directly after + * the last one. + * + * Open question: Should we send this in case of invalid + * payload CRCs if the frame-type is non-sequential (current + * implementation) or should we drop that frame without + * telling the EC? + */ + ssh_ptl_send_nak(ptl); + } + + if (unlikely(!syn_found)) + return aligned.ptr - source->ptr; + + /* Parse and validate frame. */ + status = sshp_parse_frame(&ptl->serdev->dev, &aligned, &frame, &payload, + SSH_PTL_RX_BUF_LEN); + if (status) /* Invalid frame: skip to next SYN. */ + return aligned.ptr - source->ptr + sizeof(u16); + if (!frame) /* Not enough data. */ + return aligned.ptr - source->ptr; + + switch (frame->type) { + case SSH_FRAME_TYPE_ACK: + ssh_ptl_acknowledge(ptl, frame->seq); + break; + + case SSH_FRAME_TYPE_NAK: + ssh_ptl_resubmit_pending(ptl); + break; + + case SSH_FRAME_TYPE_DATA_SEQ: + ssh_ptl_send_ack(ptl, frame->seq); + fallthrough; + + case SSH_FRAME_TYPE_DATA_NSQ: + ssh_ptl_rx_dataframe(ptl, frame, &payload); + break; + + default: + ptl_warn(ptl, "ptl: received frame with unknown type %#04x\n", + frame->type); + break; + } + + return aligned.ptr - source->ptr + SSH_MESSAGE_LENGTH(frame->len); +} + +static int ssh_ptl_rx_threadfn(void *data) +{ + struct ssh_ptl *ptl = data; + + while (true) { + struct ssam_span span; + size_t offs = 0; + size_t n; + + wait_event_interruptible(ptl->rx.wq, + !kfifo_is_empty(&ptl->rx.fifo) || + kthread_should_stop()); + if (kthread_should_stop()) + break; + + /* Copy from fifo to evaluation buffer. */ + n = sshp_buf_read_from_fifo(&ptl->rx.buf, &ptl->rx.fifo); + + ptl_dbg(ptl, "rx: received data (size: %zu)\n", n); + print_hex_dump_debug("rx: ", DUMP_PREFIX_OFFSET, 16, 1, + ptl->rx.buf.ptr + ptl->rx.buf.len - n, + n, false); + + /* Parse until we need more bytes or buffer is empty. */ + while (offs < ptl->rx.buf.len) { + sshp_buf_span_from(&ptl->rx.buf, offs, &span); + n = ssh_ptl_rx_eval(ptl, &span); + if (n == 0) + break; /* Need more bytes. */ + + offs += n; + } + + /* Throw away the evaluated parts. */ + sshp_buf_drop(&ptl->rx.buf, offs); + } + + return 0; +} + +static void ssh_ptl_rx_wakeup(struct ssh_ptl *ptl) +{ + wake_up(&ptl->rx.wq); +} + +/** + * ssh_ptl_rx_start() - Start packet transport layer receiver thread. + * @ptl: The packet transport layer. + * + * Return: Returns zero on success, a negative error code on failure. + */ +int ssh_ptl_rx_start(struct ssh_ptl *ptl) +{ + if (ptl->rx.thread) + return 0; + + ptl->rx.thread = kthread_run(ssh_ptl_rx_threadfn, ptl, + "ssam_serial_hub-rx"); + if (IS_ERR(ptl->rx.thread)) + return PTR_ERR(ptl->rx.thread); + + return 0; +} + +/** + * ssh_ptl_rx_stop() - Stop packet transport layer receiver thread. + * @ptl: The packet transport layer. + * + * Return: Returns zero on success, a negative error code on failure. + */ +int ssh_ptl_rx_stop(struct ssh_ptl *ptl) +{ + int status = 0; + + if (ptl->rx.thread) { + status = kthread_stop(ptl->rx.thread); + ptl->rx.thread = NULL; + } + + return status; +} + +/** + * ssh_ptl_rx_rcvbuf() - Push data from lower-layer transport to the packet + * layer. + * @ptl: The packet transport layer. + * @buf: Pointer to the data to push to the layer. + * @n: Size of the data to push to the layer, in bytes. + * + * Pushes data from a lower-layer transport to the receiver fifo buffer of the + * packet layer and notifies the receiver thread. Calls to this function are + * ignored once the packet layer has been shut down. + * + * Return: Returns the number of bytes transferred (positive or zero) on + * success. Returns %-ESHUTDOWN if the packet layer has been shut down. + */ +int ssh_ptl_rx_rcvbuf(struct ssh_ptl *ptl, const u8 *buf, size_t n) +{ + int used; + + if (test_bit(SSH_PTL_SF_SHUTDOWN_BIT, &ptl->state)) + return -ESHUTDOWN; + + used = kfifo_in(&ptl->rx.fifo, buf, n); + if (used) + ssh_ptl_rx_wakeup(ptl); + + return used; +} + +/** + * ssh_ptl_shutdown() - Shut down the packet transport layer. + * @ptl: The packet transport layer. + * + * Shuts down the packet transport layer, removing and canceling all queued + * and pending packets. Packets canceled by this operation will be completed + * with %-ESHUTDOWN as status. Receiver and transmitter threads will be + * stopped. + * + * As a result of this function, the transport layer will be marked as shut + * down. Submission of packets after the transport layer has been shut down + * will fail with %-ESHUTDOWN. + */ +void ssh_ptl_shutdown(struct ssh_ptl *ptl) +{ + LIST_HEAD(complete_q); + LIST_HEAD(complete_p); + struct ssh_packet *p, *n; + int status; + + /* Ensure that no new packets (including ACK/NAK) can be submitted. */ + set_bit(SSH_PTL_SF_SHUTDOWN_BIT, &ptl->state); + /* + * Ensure that the layer gets marked as shut-down before actually + * stopping it. In combination with the check in ssh_ptl_queue_push(), + * this guarantees that no new packets can be added and all already + * queued packets are properly canceled. In combination with the check + * in ssh_ptl_rx_rcvbuf(), this guarantees that received data is + * properly cut off. + */ + smp_mb__after_atomic(); + + status = ssh_ptl_rx_stop(ptl); + if (status) + ptl_err(ptl, "ptl: failed to stop receiver thread\n"); + + status = ssh_ptl_tx_stop(ptl); + if (status) + ptl_err(ptl, "ptl: failed to stop transmitter thread\n"); + + cancel_delayed_work_sync(&ptl->rtx_timeout.reaper); + + /* + * At this point, all threads have been stopped. This means that the + * only references to packets from inside the system are in the queue + * and pending set. + * + * Note: We still need locks here because someone could still be + * canceling packets. + * + * Note 2: We can re-use queue_node (or pending_node) if we mark the + * packet as locked an then remove it from the queue (or pending set + * respectively). Marking the packet as locked avoids re-queuing + * (which should already be prevented by having stopped the treads...) + * and not setting QUEUED_BIT (or PENDING_BIT) prevents removal from a + * new list via other threads (e.g. cancellation). + * + * Note 3: There may be overlap between complete_p and complete_q. + * This is handled via test_and_set_bit() on the "completed" flag + * (also handles cancellation). + */ + + /* Mark queued packets as locked and move them to complete_q. */ + spin_lock(&ptl->queue.lock); + list_for_each_entry_safe(p, n, &ptl->queue.head, queue_node) { + set_bit(SSH_PACKET_SF_LOCKED_BIT, &p->state); + /* Ensure that state does not get zero. */ + smp_mb__before_atomic(); + clear_bit(SSH_PACKET_SF_QUEUED_BIT, &p->state); + + list_del(&p->queue_node); + list_add_tail(&p->queue_node, &complete_q); + } + spin_unlock(&ptl->queue.lock); + + /* Mark pending packets as locked and move them to complete_p. */ + spin_lock(&ptl->pending.lock); + list_for_each_entry_safe(p, n, &ptl->pending.head, pending_node) { + set_bit(SSH_PACKET_SF_LOCKED_BIT, &p->state); + /* Ensure that state does not get zero. */ + smp_mb__before_atomic(); + clear_bit(SSH_PACKET_SF_PENDING_BIT, &p->state); + + list_del(&p->pending_node); + list_add_tail(&p->pending_node, &complete_q); + } + atomic_set(&ptl->pending.count, 0); + spin_unlock(&ptl->pending.lock); + + /* Complete and drop packets on complete_q. */ + list_for_each_entry(p, &complete_q, queue_node) { + if (!test_and_set_bit(SSH_PACKET_SF_COMPLETED_BIT, &p->state)) + __ssh_ptl_complete(p, -ESHUTDOWN); + + ssh_packet_put(p); + } + + /* Complete and drop packets on complete_p. */ + list_for_each_entry(p, &complete_p, pending_node) { + if (!test_and_set_bit(SSH_PACKET_SF_COMPLETED_BIT, &p->state)) + __ssh_ptl_complete(p, -ESHUTDOWN); + + ssh_packet_put(p); + } + + /* + * At this point we have guaranteed that the system doesn't reference + * any packets any more. + */ +} + +/** + * ssh_ptl_init() - Initialize packet transport layer. + * @ptl: The packet transport layer to initialize. + * @serdev: The underlying serial device, i.e. the lower-level transport. + * @ops: Packet layer operations. + * + * Initializes the given packet transport layer. Transmitter and receiver + * threads must be started separately via ssh_ptl_tx_start() and + * ssh_ptl_rx_start(), after the packet-layer has been initialized and the + * lower-level transport layer has been set up. + * + * Return: Returns zero on success and a nonzero error code on failure. + */ +int ssh_ptl_init(struct ssh_ptl *ptl, struct serdev_device *serdev, + struct ssh_ptl_ops *ops) +{ + int i, status; + + ptl->serdev = serdev; + ptl->state = 0; + + spin_lock_init(&ptl->queue.lock); + INIT_LIST_HEAD(&ptl->queue.head); + + spin_lock_init(&ptl->pending.lock); + INIT_LIST_HEAD(&ptl->pending.head); + atomic_set_release(&ptl->pending.count, 0); + + ptl->tx.thread = NULL; + atomic_set(&ptl->tx.running, 0); + init_completion(&ptl->tx.thread_cplt_pkt); + init_completion(&ptl->tx.thread_cplt_tx); + init_waitqueue_head(&ptl->tx.packet_wq); + + ptl->rx.thread = NULL; + init_waitqueue_head(&ptl->rx.wq); + + spin_lock_init(&ptl->rtx_timeout.lock); + ptl->rtx_timeout.timeout = SSH_PTL_PACKET_TIMEOUT; + ptl->rtx_timeout.expires = KTIME_MAX; + INIT_DELAYED_WORK(&ptl->rtx_timeout.reaper, ssh_ptl_timeout_reap); + + ptl->ops = *ops; + + /* Initialize list of recent/blocked SEQs with invalid sequence IDs. */ + for (i = 0; i < ARRAY_SIZE(ptl->rx.blocked.seqs); i++) + ptl->rx.blocked.seqs[i] = U16_MAX; + ptl->rx.blocked.offset = 0; + + status = kfifo_alloc(&ptl->rx.fifo, SSH_PTL_RX_FIFO_LEN, GFP_KERNEL); + if (status) + return status; + + status = sshp_buf_alloc(&ptl->rx.buf, SSH_PTL_RX_BUF_LEN, GFP_KERNEL); + if (status) + kfifo_free(&ptl->rx.fifo); + + return status; +} + +/** + * ssh_ptl_destroy() - Deinitialize packet transport layer. + * @ptl: The packet transport layer to deinitialize. + * + * Deinitializes the given packet transport layer and frees resources + * associated with it. If receiver and/or transmitter threads have been + * started, the layer must first be shut down via ssh_ptl_shutdown() before + * this function can be called. + */ +void ssh_ptl_destroy(struct ssh_ptl *ptl) +{ + kfifo_free(&ptl->rx.fifo); + sshp_buf_free(&ptl->rx.buf); +} diff --git a/drivers/platform/surface/aggregator/ssh_packet_layer.h b/drivers/platform/surface/aggregator/ssh_packet_layer.h new file mode 100644 index 000000000000..058f111292ca --- /dev/null +++ b/drivers/platform/surface/aggregator/ssh_packet_layer.h @@ -0,0 +1,187 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * SSH packet transport layer. + * + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#ifndef _SURFACE_AGGREGATOR_SSH_PACKET_LAYER_H +#define _SURFACE_AGGREGATOR_SSH_PACKET_LAYER_H + +#include <linux/atomic.h> +#include <linux/kfifo.h> +#include <linux/ktime.h> +#include <linux/list.h> +#include <linux/serdev.h> +#include <linux/spinlock.h> +#include <linux/types.h> +#include <linux/wait.h> +#include <linux/workqueue.h> + +#include <linux/surface_aggregator/serial_hub.h> +#include "ssh_parser.h" + +/** + * enum ssh_ptl_state_flags - State-flags for &struct ssh_ptl. + * + * @SSH_PTL_SF_SHUTDOWN_BIT: + * Indicates that the packet transport layer has been shut down or is + * being shut down and should not accept any new packets/data. + */ +enum ssh_ptl_state_flags { + SSH_PTL_SF_SHUTDOWN_BIT, +}; + +/** + * struct ssh_ptl_ops - Callback operations for packet transport layer. + * @data_received: Function called when a data-packet has been received. Both, + * the packet layer on which the packet has been received and + * the packet's payload data are provided to this function. + */ +struct ssh_ptl_ops { + void (*data_received)(struct ssh_ptl *p, const struct ssam_span *data); +}; + +/** + * struct ssh_ptl - SSH packet transport layer. + * @serdev: Serial device providing the underlying data transport. + * @state: State(-flags) of the transport layer. + * @queue: Packet submission queue. + * @queue.lock: Lock for modifying the packet submission queue. + * @queue.head: List-head of the packet submission queue. + * @pending: Set/list of pending packets. + * @pending.lock: Lock for modifying the pending set. + * @pending.head: List-head of the pending set/list. + * @pending.count: Number of currently pending packets. + * @tx: Transmitter subsystem. + * @tx.running: Flag indicating (desired) transmitter thread state. + * @tx.thread: Transmitter thread. + * @tx.thread_cplt_tx: Completion for transmitter thread waiting on transfer. + * @tx.thread_cplt_pkt: Completion for transmitter thread waiting on packets. + * @tx.packet_wq: Waitqueue-head for packet transmit completion. + * @rx: Receiver subsystem. + * @rx.thread: Receiver thread. + * @rx.wq: Waitqueue-head for receiver thread. + * @rx.fifo: Buffer for receiving data/pushing data to receiver thread. + * @rx.buf: Buffer for evaluating data on receiver thread. + * @rx.blocked: List of recent/blocked sequence IDs to detect retransmission. + * @rx.blocked.seqs: Array of blocked sequence IDs. + * @rx.blocked.offset: Offset indicating where a new ID should be inserted. + * @rtx_timeout: Retransmission timeout subsystem. + * @rtx_timeout.lock: Lock for modifying the retransmission timeout reaper. + * @rtx_timeout.timeout: Timeout interval for retransmission. + * @rtx_timeout.expires: Time specifying when the reaper work is next scheduled. + * @rtx_timeout.reaper: Work performing timeout checks and subsequent actions. + * @ops: Packet layer operations. + */ +struct ssh_ptl { + struct serdev_device *serdev; + unsigned long state; + + struct { + spinlock_t lock; + struct list_head head; + } queue; + + struct { + spinlock_t lock; + struct list_head head; + atomic_t count; + } pending; + + struct { + atomic_t running; + struct task_struct *thread; + struct completion thread_cplt_tx; + struct completion thread_cplt_pkt; + struct wait_queue_head packet_wq; + } tx; + + struct { + struct task_struct *thread; + struct wait_queue_head wq; + struct kfifo fifo; + struct sshp_buf buf; + + struct { + u16 seqs[8]; + u16 offset; + } blocked; + } rx; + + struct { + spinlock_t lock; + ktime_t timeout; + ktime_t expires; + struct delayed_work reaper; + } rtx_timeout; + + struct ssh_ptl_ops ops; +}; + +#define __ssam_prcond(func, p, fmt, ...) \ + do { \ + typeof(p) __p = (p); \ + \ + if (__p) \ + func(__p, fmt, ##__VA_ARGS__); \ + } while (0) + +#define ptl_dbg(p, fmt, ...) dev_dbg(&(p)->serdev->dev, fmt, ##__VA_ARGS__) +#define ptl_info(p, fmt, ...) dev_info(&(p)->serdev->dev, fmt, ##__VA_ARGS__) +#define ptl_warn(p, fmt, ...) dev_warn(&(p)->serdev->dev, fmt, ##__VA_ARGS__) +#define ptl_err(p, fmt, ...) dev_err(&(p)->serdev->dev, fmt, ##__VA_ARGS__) +#define ptl_dbg_cond(p, fmt, ...) __ssam_prcond(ptl_dbg, p, fmt, ##__VA_ARGS__) + +#define to_ssh_ptl(ptr, member) \ + container_of(ptr, struct ssh_ptl, member) + +int ssh_ptl_init(struct ssh_ptl *ptl, struct serdev_device *serdev, + struct ssh_ptl_ops *ops); + +void ssh_ptl_destroy(struct ssh_ptl *ptl); + +/** + * ssh_ptl_get_device() - Get device associated with packet transport layer. + * @ptl: The packet transport layer. + * + * Return: Returns the device on which the given packet transport layer builds + * upon. + */ +static inline struct device *ssh_ptl_get_device(struct ssh_ptl *ptl) +{ + return ptl->serdev ? &ptl->serdev->dev : NULL; +} + +int ssh_ptl_tx_start(struct ssh_ptl *ptl); +int ssh_ptl_tx_stop(struct ssh_ptl *ptl); +int ssh_ptl_rx_start(struct ssh_ptl *ptl); +int ssh_ptl_rx_stop(struct ssh_ptl *ptl); +void ssh_ptl_shutdown(struct ssh_ptl *ptl); + +int ssh_ptl_submit(struct ssh_ptl *ptl, struct ssh_packet *p); +void ssh_ptl_cancel(struct ssh_packet *p); + +int ssh_ptl_rx_rcvbuf(struct ssh_ptl *ptl, const u8 *buf, size_t n); + +/** + * ssh_ptl_tx_wakeup_transfer() - Wake up packet transmitter thread for + * transfer. + * @ptl: The packet transport layer. + * + * Wakes up the packet transmitter thread, notifying it that the underlying + * transport has more space for data to be transmitted. If the packet + * transport layer has been shut down, calls to this function will be ignored. + */ +static inline void ssh_ptl_tx_wakeup_transfer(struct ssh_ptl *ptl) +{ + if (test_bit(SSH_PTL_SF_SHUTDOWN_BIT, &ptl->state)) + return; + + complete(&ptl->tx.thread_cplt_tx); +} + +void ssh_packet_init(struct ssh_packet *packet, unsigned long type, + u8 priority, const struct ssh_packet_ops *ops); + +#endif /* _SURFACE_AGGREGATOR_SSH_PACKET_LAYER_H */ diff --git a/drivers/platform/surface/aggregator/ssh_parser.c b/drivers/platform/surface/aggregator/ssh_parser.c new file mode 100644 index 000000000000..e2dead8de94a --- /dev/null +++ b/drivers/platform/surface/aggregator/ssh_parser.c @@ -0,0 +1,228 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * SSH message parser. + * + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#include <asm/unaligned.h> +#include <linux/compiler.h> +#include <linux/device.h> +#include <linux/types.h> + +#include <linux/surface_aggregator/serial_hub.h> +#include "ssh_parser.h" + +/** + * sshp_validate_crc() - Validate a CRC in raw message data. + * @src: The span of data over which the CRC should be computed. + * @crc: The pointer to the expected u16 CRC value. + * + * Computes the CRC of the provided data span (@src), compares it to the CRC + * stored at the given address (@crc), and returns the result of this + * comparison, i.e. %true if equal. This function is intended to run on raw + * input/message data. + * + * Return: Returns %true if the computed CRC matches the stored CRC, %false + * otherwise. + */ +static bool sshp_validate_crc(const struct ssam_span *src, const u8 *crc) +{ + u16 actual = ssh_crc(src->ptr, src->len); + u16 expected = get_unaligned_le16(crc); + + return actual == expected; +} + +/** + * sshp_starts_with_syn() - Check if the given data starts with SSH SYN bytes. + * @src: The data span to check the start of. + */ +static bool sshp_starts_with_syn(const struct ssam_span *src) +{ + return src->len >= 2 && get_unaligned_le16(src->ptr) == SSH_MSG_SYN; +} + +/** + * sshp_find_syn() - Find SSH SYN bytes in the given data span. + * @src: The data span to search in. + * @rem: The span (output) indicating the remaining data, starting with SSH + * SYN bytes, if found. + * + * Search for SSH SYN bytes in the given source span. If found, set the @rem + * span to the remaining data, starting with the first SYN bytes and capped by + * the source span length, and return %true. This function does not copy any + * data, but rather only sets pointers to the respective start addresses and + * length values. + * + * If no SSH SYN bytes could be found, set the @rem span to the zero-length + * span at the end of the source span and return %false. + * + * If partial SSH SYN bytes could be found at the end of the source span, set + * the @rem span to cover these partial SYN bytes, capped by the end of the + * source span, and return %false. This function should then be re-run once + * more data is available. + * + * Return: Returns %true if a complete SSH SYN sequence could be found, + * %false otherwise. + */ +bool sshp_find_syn(const struct ssam_span *src, struct ssam_span *rem) +{ + size_t i; + + for (i = 0; i < src->len - 1; i++) { + if (likely(get_unaligned_le16(src->ptr + i) == SSH_MSG_SYN)) { + rem->ptr = src->ptr + i; + rem->len = src->len - i; + return true; + } + } + + if (unlikely(src->ptr[src->len - 1] == (SSH_MSG_SYN & 0xff))) { + rem->ptr = src->ptr + src->len - 1; + rem->len = 1; + return false; + } + + rem->ptr = src->ptr + src->len; + rem->len = 0; + return false; +} + +/** + * sshp_parse_frame() - Parse SSH frame. + * @dev: The device used for logging. + * @source: The source to parse from. + * @frame: The parsed frame (output). + * @payload: The parsed payload (output). + * @maxlen: The maximum supported message length. + * + * Parses and validates a SSH frame, including its payload, from the given + * source. Sets the provided @frame pointer to the start of the frame and + * writes the limits of the frame payload to the provided @payload span + * pointer. + * + * This function does not copy any data, but rather only validates the message + * data and sets pointers (and length values) to indicate the respective parts. + * + * If no complete SSH frame could be found, the frame pointer will be set to + * the %NULL pointer and the payload span will be set to the null span (start + * pointer %NULL, size zero). + * + * Return: Returns zero on success or if the frame is incomplete, %-ENOMSG if + * the start of the message is invalid, %-EBADMSG if any (frame-header or + * payload) CRC is invalid, or %-EMSGSIZE if the SSH message is bigger than + * the maximum message length specified in the @maxlen parameter. + */ +int sshp_parse_frame(const struct device *dev, const struct ssam_span *source, + struct ssh_frame **frame, struct ssam_span *payload, + size_t maxlen) +{ + struct ssam_span sf; + struct ssam_span sp; + + /* Initialize output. */ + *frame = NULL; + payload->ptr = NULL; + payload->len = 0; + + if (!sshp_starts_with_syn(source)) { + dev_warn(dev, "rx: parser: invalid start of frame\n"); + return -ENOMSG; + } + + /* Check for minimum packet length. */ + if (unlikely(source->len < SSH_MESSAGE_LENGTH(0))) { + dev_dbg(dev, "rx: parser: not enough data for frame\n"); + return 0; + } + + /* Pin down frame. */ + sf.ptr = source->ptr + sizeof(u16); + sf.len = sizeof(struct ssh_frame); + + /* Validate frame CRC. */ + if (unlikely(!sshp_validate_crc(&sf, sf.ptr + sf.len))) { + dev_warn(dev, "rx: parser: invalid frame CRC\n"); + return -EBADMSG; + } + + /* Ensure packet does not exceed maximum length. */ + sp.len = get_unaligned_le16(&((struct ssh_frame *)sf.ptr)->len); + if (unlikely(SSH_MESSAGE_LENGTH(sp.len) > maxlen)) { + dev_warn(dev, "rx: parser: frame too large: %llu bytes\n", + SSH_MESSAGE_LENGTH(sp.len)); + return -EMSGSIZE; + } + + /* Pin down payload. */ + sp.ptr = sf.ptr + sf.len + sizeof(u16); + + /* Check for frame + payload length. */ + if (source->len < SSH_MESSAGE_LENGTH(sp.len)) { + dev_dbg(dev, "rx: parser: not enough data for payload\n"); + return 0; + } + + /* Validate payload CRC. */ + if (unlikely(!sshp_validate_crc(&sp, sp.ptr + sp.len))) { + dev_warn(dev, "rx: parser: invalid payload CRC\n"); + return -EBADMSG; + } + + *frame = (struct ssh_frame *)sf.ptr; + *payload = sp; + + dev_dbg(dev, "rx: parser: valid frame found (type: %#04x, len: %u)\n", + (*frame)->type, (*frame)->len); + + return 0; +} + +/** + * sshp_parse_command() - Parse SSH command frame payload. + * @dev: The device used for logging. + * @source: The source to parse from. + * @command: The parsed command (output). + * @command_data: The parsed command data/payload (output). + * + * Parses and validates a SSH command frame payload. Sets the @command pointer + * to the command header and the @command_data span to the command data (i.e. + * payload of the command). This will result in a zero-length span if the + * command does not have any associated data/payload. This function does not + * check the frame-payload-type field, which should be checked by the caller + * before calling this function. + * + * The @source parameter should be the complete frame payload, e.g. returned + * by the sshp_parse_frame() command. + * + * This function does not copy any data, but rather only validates the frame + * payload data and sets pointers (and length values) to indicate the + * respective parts. + * + * Return: Returns zero on success or %-ENOMSG if @source does not represent a + * valid command-type frame payload, i.e. is too short. + */ +int sshp_parse_command(const struct device *dev, const struct ssam_span *source, + struct ssh_command **command, + struct ssam_span *command_data) +{ + /* Check for minimum length. */ + if (unlikely(source->len < sizeof(struct ssh_command))) { + *command = NULL; + command_data->ptr = NULL; + command_data->len = 0; + + dev_err(dev, "rx: parser: command payload is too short\n"); + return -ENOMSG; + } + + *command = (struct ssh_command *)source->ptr; + command_data->ptr = source->ptr + sizeof(struct ssh_command); + command_data->len = source->len - sizeof(struct ssh_command); + + dev_dbg(dev, "rx: parser: valid command found (tc: %#04x, cid: %#04x)\n", + (*command)->tc, (*command)->cid); + + return 0; +} diff --git a/drivers/platform/surface/aggregator/ssh_parser.h b/drivers/platform/surface/aggregator/ssh_parser.h new file mode 100644 index 000000000000..63c38d350988 --- /dev/null +++ b/drivers/platform/surface/aggregator/ssh_parser.h @@ -0,0 +1,154 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * SSH message parser. + * + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#ifndef _SURFACE_AGGREGATOR_SSH_PARSER_H +#define _SURFACE_AGGREGATOR_SSH_PARSER_H + +#include <linux/device.h> +#include <linux/kfifo.h> +#include <linux/slab.h> +#include <linux/types.h> + +#include <linux/surface_aggregator/serial_hub.h> + +/** + * struct sshp_buf - Parser buffer for SSH messages. + * @ptr: Pointer to the beginning of the buffer. + * @len: Number of bytes used in the buffer. + * @cap: Maximum capacity of the buffer. + */ +struct sshp_buf { + u8 *ptr; + size_t len; + size_t cap; +}; + +/** + * sshp_buf_init() - Initialize a SSH parser buffer. + * @buf: The buffer to initialize. + * @ptr: The memory backing the buffer. + * @cap: The length of the memory backing the buffer, i.e. its capacity. + * + * Initializes the buffer with the given memory as backing and set its used + * length to zero. + */ +static inline void sshp_buf_init(struct sshp_buf *buf, u8 *ptr, size_t cap) +{ + buf->ptr = ptr; + buf->len = 0; + buf->cap = cap; +} + +/** + * sshp_buf_alloc() - Allocate and initialize a SSH parser buffer. + * @buf: The buffer to initialize/allocate to. + * @cap: The desired capacity of the buffer. + * @flags: The flags used for allocating the memory. + * + * Allocates @cap bytes and initializes the provided buffer struct with the + * allocated memory. + * + * Return: Returns zero on success and %-ENOMEM if allocation failed. + */ +static inline int sshp_buf_alloc(struct sshp_buf *buf, size_t cap, gfp_t flags) +{ + u8 *ptr; + + ptr = kzalloc(cap, flags); + if (!ptr) + return -ENOMEM; + + sshp_buf_init(buf, ptr, cap); + return 0; +} + +/** + * sshp_buf_free() - Free a SSH parser buffer. + * @buf: The buffer to free. + * + * Frees a SSH parser buffer by freeing the memory backing it and then + * resetting its pointer to %NULL and length and capacity to zero. Intended to + * free a buffer previously allocated with sshp_buf_alloc(). + */ +static inline void sshp_buf_free(struct sshp_buf *buf) +{ + kfree(buf->ptr); + buf->ptr = NULL; + buf->len = 0; + buf->cap = 0; +} + +/** + * sshp_buf_drop() - Drop data from the beginning of the buffer. + * @buf: The buffer to drop data from. + * @n: The number of bytes to drop. + * + * Drops the first @n bytes from the buffer. Re-aligns any remaining data to + * the beginning of the buffer. + */ +static inline void sshp_buf_drop(struct sshp_buf *buf, size_t n) +{ + memmove(buf->ptr, buf->ptr + n, buf->len - n); + buf->len -= n; +} + +/** + * sshp_buf_read_from_fifo() - Transfer data from a fifo to the buffer. + * @buf: The buffer to write the data into. + * @fifo: The fifo to read the data from. + * + * Transfers the data contained in the fifo to the buffer, removing it from + * the fifo. This function will try to transfer as much data as possible, + * limited either by the remaining space in the buffer or by the number of + * bytes available in the fifo. + * + * Return: Returns the number of bytes transferred. + */ +static inline size_t sshp_buf_read_from_fifo(struct sshp_buf *buf, + struct kfifo *fifo) +{ + size_t n; + + n = kfifo_out(fifo, buf->ptr + buf->len, buf->cap - buf->len); + buf->len += n; + + return n; +} + +/** + * sshp_buf_span_from() - Initialize a span from the given buffer and offset. + * @buf: The buffer to create the span from. + * @offset: The offset in the buffer at which the span should start. + * @span: The span to initialize (output). + * + * Initializes the provided span to point to the memory at the given offset in + * the buffer, with the length of the span being capped by the number of bytes + * used in the buffer after the offset (i.e. bytes remaining after the + * offset). + * + * Warning: This function does not validate that @offset is less than or equal + * to the number of bytes used in the buffer or the buffer capacity. This must + * be guaranteed by the caller. + */ +static inline void sshp_buf_span_from(struct sshp_buf *buf, size_t offset, + struct ssam_span *span) +{ + span->ptr = buf->ptr + offset; + span->len = buf->len - offset; +} + +bool sshp_find_syn(const struct ssam_span *src, struct ssam_span *rem); + +int sshp_parse_frame(const struct device *dev, const struct ssam_span *source, + struct ssh_frame **frame, struct ssam_span *payload, + size_t maxlen); + +int sshp_parse_command(const struct device *dev, const struct ssam_span *source, + struct ssh_command **command, + struct ssam_span *command_data); + +#endif /* _SURFACE_AGGREGATOR_SSH_PARSER_h */ diff --git a/drivers/platform/surface/aggregator/ssh_request_layer.c b/drivers/platform/surface/aggregator/ssh_request_layer.c new file mode 100644 index 000000000000..66c839a995f3 --- /dev/null +++ b/drivers/platform/surface/aggregator/ssh_request_layer.c @@ -0,0 +1,1211 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * SSH request transport layer. + * + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#include <asm/unaligned.h> +#include <linux/atomic.h> +#include <linux/completion.h> +#include <linux/ktime.h> +#include <linux/limits.h> +#include <linux/list.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/types.h> +#include <linux/workqueue.h> + +#include <linux/surface_aggregator/serial_hub.h> +#include <linux/surface_aggregator/controller.h> + +#include "ssh_packet_layer.h" +#include "ssh_request_layer.h" + +/* + * SSH_RTL_REQUEST_TIMEOUT - Request timeout. + * + * Timeout as ktime_t delta for request responses. If we have not received a + * response in this time-frame after finishing the underlying packet + * transmission, the request will be completed with %-ETIMEDOUT as status + * code. + */ +#define SSH_RTL_REQUEST_TIMEOUT ms_to_ktime(3000) + +/* + * SSH_RTL_REQUEST_TIMEOUT_RESOLUTION - Request timeout granularity. + * + * Time-resolution for timeouts. Should be larger than one jiffy to avoid + * direct re-scheduling of reaper work_struct. + */ +#define SSH_RTL_REQUEST_TIMEOUT_RESOLUTION ms_to_ktime(max(2000 / HZ, 50)) + +/* + * SSH_RTL_MAX_PENDING - Maximum number of pending requests. + * + * Maximum number of requests concurrently waiting to be completed (i.e. + * waiting for the corresponding packet transmission to finish if they don't + * have a response or waiting for a response if they have one). + */ +#define SSH_RTL_MAX_PENDING 3 + +/* + * SSH_RTL_TX_BATCH - Maximum number of requests processed per work execution. + * Used to prevent livelocking of the workqueue. Value chosen via educated + * guess, may be adjusted. + */ +#define SSH_RTL_TX_BATCH 10 + +static u16 ssh_request_get_rqid(struct ssh_request *rqst) +{ + return get_unaligned_le16(rqst->packet.data.ptr + + SSH_MSGOFFSET_COMMAND(rqid)); +} + +static u32 ssh_request_get_rqid_safe(struct ssh_request *rqst) +{ + if (!rqst->packet.data.ptr) + return U32_MAX; + + return ssh_request_get_rqid(rqst); +} + +static void ssh_rtl_queue_remove(struct ssh_request *rqst) +{ + struct ssh_rtl *rtl = ssh_request_rtl(rqst); + + spin_lock(&rtl->queue.lock); + + if (!test_and_clear_bit(SSH_REQUEST_SF_QUEUED_BIT, &rqst->state)) { + spin_unlock(&rtl->queue.lock); + return; + } + + list_del(&rqst->node); + + spin_unlock(&rtl->queue.lock); + ssh_request_put(rqst); +} + +static bool ssh_rtl_queue_empty(struct ssh_rtl *rtl) +{ + bool empty; + + spin_lock(&rtl->queue.lock); + empty = list_empty(&rtl->queue.head); + spin_unlock(&rtl->queue.lock); + + return empty; +} + +static void ssh_rtl_pending_remove(struct ssh_request *rqst) +{ + struct ssh_rtl *rtl = ssh_request_rtl(rqst); + + spin_lock(&rtl->pending.lock); + + if (!test_and_clear_bit(SSH_REQUEST_SF_PENDING_BIT, &rqst->state)) { + spin_unlock(&rtl->pending.lock); + return; + } + + atomic_dec(&rtl->pending.count); + list_del(&rqst->node); + + spin_unlock(&rtl->pending.lock); + + ssh_request_put(rqst); +} + +static int ssh_rtl_tx_pending_push(struct ssh_request *rqst) +{ + struct ssh_rtl *rtl = ssh_request_rtl(rqst); + + spin_lock(&rtl->pending.lock); + + if (test_bit(SSH_REQUEST_SF_LOCKED_BIT, &rqst->state)) { + spin_unlock(&rtl->pending.lock); + return -EINVAL; + } + + if (test_and_set_bit(SSH_REQUEST_SF_PENDING_BIT, &rqst->state)) { + spin_unlock(&rtl->pending.lock); + return -EALREADY; + } + + atomic_inc(&rtl->pending.count); + list_add_tail(&ssh_request_get(rqst)->node, &rtl->pending.head); + + spin_unlock(&rtl->pending.lock); + return 0; +} + +static void ssh_rtl_complete_with_status(struct ssh_request *rqst, int status) +{ + struct ssh_rtl *rtl = ssh_request_rtl(rqst); + + /* rtl/ptl may not be set if we're canceling before submitting. */ + rtl_dbg_cond(rtl, "rtl: completing request (rqid: %#06x, status: %d)\n", + ssh_request_get_rqid_safe(rqst), status); + + rqst->ops->complete(rqst, NULL, NULL, status); +} + +static void ssh_rtl_complete_with_rsp(struct ssh_request *rqst, + const struct ssh_command *cmd, + const struct ssam_span *data) +{ + struct ssh_rtl *rtl = ssh_request_rtl(rqst); + + rtl_dbg(rtl, "rtl: completing request with response (rqid: %#06x)\n", + ssh_request_get_rqid(rqst)); + + rqst->ops->complete(rqst, cmd, data, 0); +} + +static bool ssh_rtl_tx_can_process(struct ssh_request *rqst) +{ + struct ssh_rtl *rtl = ssh_request_rtl(rqst); + + if (test_bit(SSH_REQUEST_TY_FLUSH_BIT, &rqst->state)) + return !atomic_read(&rtl->pending.count); + + return atomic_read(&rtl->pending.count) < SSH_RTL_MAX_PENDING; +} + +static struct ssh_request *ssh_rtl_tx_next(struct ssh_rtl *rtl) +{ + struct ssh_request *rqst = ERR_PTR(-ENOENT); + struct ssh_request *p, *n; + + spin_lock(&rtl->queue.lock); + + /* Find first non-locked request and remove it. */ + list_for_each_entry_safe(p, n, &rtl->queue.head, node) { + if (unlikely(test_bit(SSH_REQUEST_SF_LOCKED_BIT, &p->state))) + continue; + + if (!ssh_rtl_tx_can_process(p)) { + rqst = ERR_PTR(-EBUSY); + break; + } + + /* Remove from queue and mark as transmitting. */ + set_bit(SSH_REQUEST_SF_TRANSMITTING_BIT, &p->state); + /* Ensure state never gets zero. */ + smp_mb__before_atomic(); + clear_bit(SSH_REQUEST_SF_QUEUED_BIT, &p->state); + + list_del(&p->node); + + rqst = p; + break; + } + + spin_unlock(&rtl->queue.lock); + return rqst; +} + +static int ssh_rtl_tx_try_process_one(struct ssh_rtl *rtl) +{ + struct ssh_request *rqst; + int status; + + /* Get and prepare next request for transmit. */ + rqst = ssh_rtl_tx_next(rtl); + if (IS_ERR(rqst)) + return PTR_ERR(rqst); + + /* Add it to/mark it as pending. */ + status = ssh_rtl_tx_pending_push(rqst); + if (status) { + ssh_request_put(rqst); + return -EAGAIN; + } + + /* Submit packet. */ + status = ssh_ptl_submit(&rtl->ptl, &rqst->packet); + if (status == -ESHUTDOWN) { + /* + * Packet has been refused due to the packet layer shutting + * down. Complete it here. + */ + set_bit(SSH_REQUEST_SF_LOCKED_BIT, &rqst->state); + /* + * Note: A barrier is not required here, as there are only two + * references in the system at this point: The one that we have, + * and the other one that belongs to the pending set. Due to the + * request being marked as "transmitting", our process is the + * only one allowed to remove the pending node and change the + * state. Normally, the task would fall to the packet callback, + * but as this is a path where submission failed, this callback + * will never be executed. + */ + + ssh_rtl_pending_remove(rqst); + ssh_rtl_complete_with_status(rqst, -ESHUTDOWN); + + ssh_request_put(rqst); + return -ESHUTDOWN; + + } else if (status) { + /* + * If submitting the packet failed and the packet layer isn't + * shutting down, the packet has either been submitted/queued + * before (-EALREADY, which cannot happen as we have + * guaranteed that requests cannot be re-submitted), or the + * packet was marked as locked (-EINVAL). To mark the packet + * locked at this stage, the request, and thus the packets + * itself, had to have been canceled. Simply drop the + * reference. Cancellation itself will remove it from the set + * of pending requests. + */ + + WARN_ON(status != -EINVAL); + + ssh_request_put(rqst); + return -EAGAIN; + } + + ssh_request_put(rqst); + return 0; +} + +static bool ssh_rtl_tx_schedule(struct ssh_rtl *rtl) +{ + if (atomic_read(&rtl->pending.count) >= SSH_RTL_MAX_PENDING) + return false; + + if (ssh_rtl_queue_empty(rtl)) + return false; + + return schedule_work(&rtl->tx.work); +} + +static void ssh_rtl_tx_work_fn(struct work_struct *work) +{ + struct ssh_rtl *rtl = to_ssh_rtl(work, tx.work); + unsigned int iterations = SSH_RTL_TX_BATCH; + int status; + + /* + * Try to be nice and not block/live-lock the workqueue: Run a maximum + * of 10 tries, then re-submit if necessary. This should not be + * necessary for normal execution, but guarantee it anyway. + */ + do { + status = ssh_rtl_tx_try_process_one(rtl); + if (status == -ENOENT || status == -EBUSY) + return; /* No more requests to process. */ + + if (status == -ESHUTDOWN) { + /* + * Packet system shutting down. No new packets can be + * transmitted. Return silently, the party initiating + * the shutdown should handle the rest. + */ + return; + } + + WARN_ON(status != 0 && status != -EAGAIN); + } while (--iterations); + + /* Out of tries, reschedule. */ + ssh_rtl_tx_schedule(rtl); +} + +/** + * ssh_rtl_submit() - Submit a request to the transport layer. + * @rtl: The request transport layer. + * @rqst: The request to submit. + * + * Submits a request to the transport layer. A single request may not be + * submitted multiple times without reinitializing it. + * + * Return: Returns zero on success, %-EINVAL if the request type is invalid or + * the request has been canceled prior to submission, %-EALREADY if the + * request has already been submitted, or %-ESHUTDOWN in case the request + * transport layer has been shut down. + */ +int ssh_rtl_submit(struct ssh_rtl *rtl, struct ssh_request *rqst) +{ + /* + * Ensure that requests expecting a response are sequenced. If this + * invariant ever changes, see the comment in ssh_rtl_complete() on what + * is required to be changed in the code. + */ + if (test_bit(SSH_REQUEST_TY_HAS_RESPONSE_BIT, &rqst->state)) + if (!test_bit(SSH_PACKET_TY_SEQUENCED_BIT, &rqst->packet.state)) + return -EINVAL; + + spin_lock(&rtl->queue.lock); + + /* + * Try to set ptl and check if this request has already been submitted. + * + * Must be inside lock as we might run into a lost update problem + * otherwise: If this were outside of the lock, cancellation in + * ssh_rtl_cancel_nonpending() may run after we've set the ptl + * reference but before we enter the lock. In that case, we'd detect + * that the request is being added to the queue and would try to remove + * it from that, but removal might fail because it hasn't actually been + * added yet. By putting this cmpxchg in the critical section, we + * ensure that the queuing detection only triggers when we are already + * in the critical section and the remove process will wait until the + * push operation has been completed (via lock) due to that. Only then, + * we can safely try to remove it. + */ + if (cmpxchg(&rqst->packet.ptl, NULL, &rtl->ptl)) { + spin_unlock(&rtl->queue.lock); + return -EALREADY; + } + + /* + * Ensure that we set ptl reference before we continue modifying state. + * This is required for non-pending cancellation. This barrier is paired + * with the one in ssh_rtl_cancel_nonpending(). + * + * By setting the ptl reference before we test for "locked", we can + * check if the "locked" test may have already run. See comments in + * ssh_rtl_cancel_nonpending() for more detail. + */ + smp_mb__after_atomic(); + + if (test_bit(SSH_RTL_SF_SHUTDOWN_BIT, &rtl->state)) { + spin_unlock(&rtl->queue.lock); + return -ESHUTDOWN; + } + + if (test_bit(SSH_REQUEST_SF_LOCKED_BIT, &rqst->state)) { + spin_unlock(&rtl->queue.lock); + return -EINVAL; + } + + set_bit(SSH_REQUEST_SF_QUEUED_BIT, &rqst->state); + list_add_tail(&ssh_request_get(rqst)->node, &rtl->queue.head); + + spin_unlock(&rtl->queue.lock); + + ssh_rtl_tx_schedule(rtl); + return 0; +} + +static void ssh_rtl_timeout_reaper_mod(struct ssh_rtl *rtl, ktime_t now, + ktime_t expires) +{ + unsigned long delta = msecs_to_jiffies(ktime_ms_delta(expires, now)); + ktime_t aexp = ktime_add(expires, SSH_RTL_REQUEST_TIMEOUT_RESOLUTION); + + spin_lock(&rtl->rtx_timeout.lock); + + /* Re-adjust / schedule reaper only if it is above resolution delta. */ + if (ktime_before(aexp, rtl->rtx_timeout.expires)) { + rtl->rtx_timeout.expires = expires; + mod_delayed_work(system_wq, &rtl->rtx_timeout.reaper, delta); + } + + spin_unlock(&rtl->rtx_timeout.lock); +} + +static void ssh_rtl_timeout_start(struct ssh_request *rqst) +{ + struct ssh_rtl *rtl = ssh_request_rtl(rqst); + ktime_t timestamp = ktime_get_coarse_boottime(); + ktime_t timeout = rtl->rtx_timeout.timeout; + + if (test_bit(SSH_REQUEST_SF_LOCKED_BIT, &rqst->state)) + return; + + /* + * Note: The timestamp gets set only once. This happens on the packet + * callback. All other access to it is read-only. + */ + WRITE_ONCE(rqst->timestamp, timestamp); + /* + * Ensure timestamp is set before starting the reaper. Paired with + * implicit barrier following check on ssh_request_get_expiration() in + * ssh_rtl_timeout_reap. + */ + smp_mb__after_atomic(); + + ssh_rtl_timeout_reaper_mod(rtl, timestamp, timestamp + timeout); +} + +static void ssh_rtl_complete(struct ssh_rtl *rtl, + const struct ssh_command *command, + const struct ssam_span *command_data) +{ + struct ssh_request *r = NULL; + struct ssh_request *p, *n; + u16 rqid = get_unaligned_le16(&command->rqid); + + /* + * Get request from pending based on request ID and mark it as response + * received and locked. + */ + spin_lock(&rtl->pending.lock); + list_for_each_entry_safe(p, n, &rtl->pending.head, node) { + /* We generally expect requests to be processed in order. */ + if (unlikely(ssh_request_get_rqid(p) != rqid)) + continue; + + /* + * Mark as "response received" and "locked" as we're going to + * complete it. + */ + set_bit(SSH_REQUEST_SF_LOCKED_BIT, &p->state); + set_bit(SSH_REQUEST_SF_RSPRCVD_BIT, &p->state); + /* Ensure state never gets zero. */ + smp_mb__before_atomic(); + clear_bit(SSH_REQUEST_SF_PENDING_BIT, &p->state); + + atomic_dec(&rtl->pending.count); + list_del(&p->node); + + r = p; + break; + } + spin_unlock(&rtl->pending.lock); + + if (!r) { + rtl_warn(rtl, "rtl: dropping unexpected command message (rqid = %#06x)\n", + rqid); + return; + } + + /* If the request hasn't been completed yet, we will do this now. */ + if (test_and_set_bit(SSH_REQUEST_SF_COMPLETED_BIT, &r->state)) { + ssh_request_put(r); + ssh_rtl_tx_schedule(rtl); + return; + } + + /* + * Make sure the request has been transmitted. In case of a sequenced + * request, we are guaranteed that the completion callback will run on + * the receiver thread directly when the ACK for the packet has been + * received. Similarly, this function is guaranteed to run on the + * receiver thread. Thus we are guaranteed that if the packet has been + * successfully transmitted and received an ACK, the transmitted flag + * has been set and is visible here. + * + * We are currently not handling unsequenced packets here, as those + * should never expect a response as ensured in ssh_rtl_submit. If this + * ever changes, one would have to test for + * + * (r->state & (transmitting | transmitted)) + * + * on unsequenced packets to determine if they could have been + * transmitted. There are no synchronization guarantees as in the + * sequenced case, since, in this case, the callback function will not + * run on the same thread. Thus an exact determination is impossible. + */ + if (!test_bit(SSH_REQUEST_SF_TRANSMITTED_BIT, &r->state)) { + rtl_err(rtl, "rtl: received response before ACK for request (rqid = %#06x)\n", + rqid); + + /* + * NB: Timeout has already been canceled, request already been + * removed from pending and marked as locked and completed. As + * we receive a "false" response, the packet might still be + * queued though. + */ + ssh_rtl_queue_remove(r); + + ssh_rtl_complete_with_status(r, -EREMOTEIO); + ssh_request_put(r); + + ssh_rtl_tx_schedule(rtl); + return; + } + + /* + * NB: Timeout has already been canceled, request already been + * removed from pending and marked as locked and completed. The request + * can also not be queued any more, as it has been marked as + * transmitting and later transmitted. Thus no need to remove it from + * anywhere. + */ + + ssh_rtl_complete_with_rsp(r, command, command_data); + ssh_request_put(r); + + ssh_rtl_tx_schedule(rtl); +} + +static bool ssh_rtl_cancel_nonpending(struct ssh_request *r) +{ + struct ssh_rtl *rtl; + unsigned long flags, fixed; + bool remove; + + /* + * Handle unsubmitted request: Try to mark the packet as locked, + * expecting the state to be zero (i.e. unsubmitted). Note that, if + * setting the state worked, we might still be adding the packet to the + * queue in a currently executing submit call. In that case, however, + * ptl reference must have been set previously, as locked is checked + * after setting ptl. Furthermore, when the ptl reference is set, the + * submission process is guaranteed to have entered the critical + * section. Thus only if we successfully locked this request and ptl is + * NULL, we have successfully removed the request, i.e. we are + * guaranteed that, due to the "locked" check in ssh_rtl_submit(), the + * packet will never be added. Otherwise, we need to try and grab it + * from the queue, where we are now guaranteed that the packet is or has + * been due to the critical section. + * + * Note that if the cmpxchg() fails, we are guaranteed that ptl has + * been set and is non-NULL, as states can only be nonzero after this + * has been set. Also note that we need to fetch the static (type) + * flags to ensure that they don't cause the cmpxchg() to fail. + */ + fixed = READ_ONCE(r->state) & SSH_REQUEST_FLAGS_TY_MASK; + flags = cmpxchg(&r->state, fixed, SSH_REQUEST_SF_LOCKED_BIT); + + /* + * Force correct ordering with regards to state and ptl reference access + * to safe-guard cancellation to concurrent submission against a + * lost-update problem. First try to exchange state, then also check + * ptl if that worked. This barrier is paired with the + * one in ssh_rtl_submit(). + */ + smp_mb__after_atomic(); + + if (flags == fixed && !READ_ONCE(r->packet.ptl)) { + if (test_and_set_bit(SSH_REQUEST_SF_COMPLETED_BIT, &r->state)) + return true; + + ssh_rtl_complete_with_status(r, -ECANCELED); + return true; + } + + rtl = ssh_request_rtl(r); + spin_lock(&rtl->queue.lock); + + /* + * Note: 1) Requests cannot be re-submitted. 2) If a request is + * queued, it cannot be "transmitting"/"pending" yet. Thus, if we + * successfully remove the request here, we have removed all its + * occurrences in the system. + */ + + remove = test_and_clear_bit(SSH_REQUEST_SF_QUEUED_BIT, &r->state); + if (!remove) { + spin_unlock(&rtl->queue.lock); + return false; + } + + set_bit(SSH_REQUEST_SF_LOCKED_BIT, &r->state); + list_del(&r->node); + + spin_unlock(&rtl->queue.lock); + + ssh_request_put(r); /* Drop reference obtained from queue. */ + + if (test_and_set_bit(SSH_REQUEST_SF_COMPLETED_BIT, &r->state)) + return true; + + ssh_rtl_complete_with_status(r, -ECANCELED); + return true; +} + +static bool ssh_rtl_cancel_pending(struct ssh_request *r) +{ + /* If the packet is already locked, it's going to be removed shortly. */ + if (test_and_set_bit(SSH_REQUEST_SF_LOCKED_BIT, &r->state)) + return true; + + /* + * Now that we have locked the packet, we have guaranteed that it can't + * be added to the system any more. If ptl is NULL, the locked + * check in ssh_rtl_submit() has not been run and any submission, + * currently in progress or called later, won't add the packet. Thus we + * can directly complete it. + * + * The implicit memory barrier of test_and_set_bit() should be enough + * to ensure that the correct order (first lock, then check ptl) is + * ensured. This is paired with the barrier in ssh_rtl_submit(). + */ + if (!READ_ONCE(r->packet.ptl)) { + if (test_and_set_bit(SSH_REQUEST_SF_COMPLETED_BIT, &r->state)) + return true; + + ssh_rtl_complete_with_status(r, -ECANCELED); + return true; + } + + /* + * Try to cancel the packet. If the packet has not been completed yet, + * this will subsequently (and synchronously) call the completion + * callback of the packet, which will complete the request. + */ + ssh_ptl_cancel(&r->packet); + + /* + * If the packet has been completed with success, i.e. has not been + * canceled by the above call, the request may not have been completed + * yet (may be waiting for a response). Check if we need to do this + * here. + */ + if (test_and_set_bit(SSH_REQUEST_SF_COMPLETED_BIT, &r->state)) + return true; + + ssh_rtl_queue_remove(r); + ssh_rtl_pending_remove(r); + ssh_rtl_complete_with_status(r, -ECANCELED); + + return true; +} + +/** + * ssh_rtl_cancel() - Cancel request. + * @rqst: The request to cancel. + * @pending: Whether to also cancel pending requests. + * + * Cancels the given request. If @pending is %false, this will not cancel + * pending requests, i.e. requests that have already been submitted to the + * packet layer but not been completed yet. If @pending is %true, this will + * cancel the given request regardless of the state it is in. + * + * If the request has been canceled by calling this function, both completion + * and release callbacks of the request will be executed in a reasonable + * time-frame. This may happen during execution of this function, however, + * there is no guarantee for this. For example, a request currently + * transmitting will be canceled/completed only after transmission has + * completed, and the respective callbacks will be executed on the transmitter + * thread, which may happen during, but also some time after execution of the + * cancel function. + * + * Return: Returns %true if the given request has been canceled or completed, + * either by this function or prior to calling this function, %false + * otherwise. If @pending is %true, this function will always return %true. + */ +bool ssh_rtl_cancel(struct ssh_request *rqst, bool pending) +{ + struct ssh_rtl *rtl; + bool canceled; + + if (test_and_set_bit(SSH_REQUEST_SF_CANCELED_BIT, &rqst->state)) + return true; + + if (pending) + canceled = ssh_rtl_cancel_pending(rqst); + else + canceled = ssh_rtl_cancel_nonpending(rqst); + + /* Note: rtl may be NULL if request has not been submitted yet. */ + rtl = ssh_request_rtl(rqst); + if (canceled && rtl) + ssh_rtl_tx_schedule(rtl); + + return canceled; +} + +static void ssh_rtl_packet_callback(struct ssh_packet *p, int status) +{ + struct ssh_request *r = to_ssh_request(p); + + if (unlikely(status)) { + set_bit(SSH_REQUEST_SF_LOCKED_BIT, &r->state); + + if (test_and_set_bit(SSH_REQUEST_SF_COMPLETED_BIT, &r->state)) + return; + + /* + * The packet may get canceled even though it has not been + * submitted yet. The request may still be queued. Check the + * queue and remove it if necessary. As the timeout would have + * been started in this function on success, there's no need + * to cancel it here. + */ + ssh_rtl_queue_remove(r); + ssh_rtl_pending_remove(r); + ssh_rtl_complete_with_status(r, status); + + ssh_rtl_tx_schedule(ssh_request_rtl(r)); + return; + } + + /* Update state: Mark as transmitted and clear transmitting. */ + set_bit(SSH_REQUEST_SF_TRANSMITTED_BIT, &r->state); + /* Ensure state never gets zero. */ + smp_mb__before_atomic(); + clear_bit(SSH_REQUEST_SF_TRANSMITTING_BIT, &r->state); + + /* If we expect a response, we just need to start the timeout. */ + if (test_bit(SSH_REQUEST_TY_HAS_RESPONSE_BIT, &r->state)) { + /* + * Note: This is the only place where the timestamp gets set, + * all other access to it is read-only. + */ + ssh_rtl_timeout_start(r); + return; + } + + /* + * If we don't expect a response, lock, remove, and complete the + * request. Note that, at this point, the request is guaranteed to have + * left the queue and no timeout has been started. Thus we only need to + * remove it from pending. If the request has already been completed (it + * may have been canceled) return. + */ + + set_bit(SSH_REQUEST_SF_LOCKED_BIT, &r->state); + if (test_and_set_bit(SSH_REQUEST_SF_COMPLETED_BIT, &r->state)) + return; + + ssh_rtl_pending_remove(r); + ssh_rtl_complete_with_status(r, 0); + + ssh_rtl_tx_schedule(ssh_request_rtl(r)); +} + +static ktime_t ssh_request_get_expiration(struct ssh_request *r, ktime_t timeout) +{ + ktime_t timestamp = READ_ONCE(r->timestamp); + + if (timestamp != KTIME_MAX) + return ktime_add(timestamp, timeout); + else + return KTIME_MAX; +} + +static void ssh_rtl_timeout_reap(struct work_struct *work) +{ + struct ssh_rtl *rtl = to_ssh_rtl(work, rtx_timeout.reaper.work); + struct ssh_request *r, *n; + LIST_HEAD(claimed); + ktime_t now = ktime_get_coarse_boottime(); + ktime_t timeout = rtl->rtx_timeout.timeout; + ktime_t next = KTIME_MAX; + + /* + * Mark reaper as "not pending". This is done before checking any + * requests to avoid lost-update type problems. + */ + spin_lock(&rtl->rtx_timeout.lock); + rtl->rtx_timeout.expires = KTIME_MAX; + spin_unlock(&rtl->rtx_timeout.lock); + + spin_lock(&rtl->pending.lock); + list_for_each_entry_safe(r, n, &rtl->pending.head, node) { + ktime_t expires = ssh_request_get_expiration(r, timeout); + + /* + * Check if the timeout hasn't expired yet. Find out next + * expiration date to be handled after this run. + */ + if (ktime_after(expires, now)) { + next = ktime_before(expires, next) ? expires : next; + continue; + } + + /* Avoid further transitions if locked. */ + if (test_and_set_bit(SSH_REQUEST_SF_LOCKED_BIT, &r->state)) + continue; + + /* + * We have now marked the packet as locked. Thus it cannot be + * added to the pending or queued lists again after we've + * removed it here. We can therefore re-use the node of this + * packet temporarily. + */ + + clear_bit(SSH_REQUEST_SF_PENDING_BIT, &r->state); + + atomic_dec(&rtl->pending.count); + list_del(&r->node); + + list_add_tail(&r->node, &claimed); + } + spin_unlock(&rtl->pending.lock); + + /* Cancel and complete the request. */ + list_for_each_entry_safe(r, n, &claimed, node) { + /* + * At this point we've removed the packet from pending. This + * means that we've obtained the last (only) reference of the + * system to it. Thus we can just complete it. + */ + if (!test_and_set_bit(SSH_REQUEST_SF_COMPLETED_BIT, &r->state)) + ssh_rtl_complete_with_status(r, -ETIMEDOUT); + + /* + * Drop the reference we've obtained by removing it from the + * pending set. + */ + list_del(&r->node); + ssh_request_put(r); + } + + /* Ensure that the reaper doesn't run again immediately. */ + next = max(next, ktime_add(now, SSH_RTL_REQUEST_TIMEOUT_RESOLUTION)); + if (next != KTIME_MAX) + ssh_rtl_timeout_reaper_mod(rtl, now, next); + + ssh_rtl_tx_schedule(rtl); +} + +static void ssh_rtl_rx_event(struct ssh_rtl *rtl, const struct ssh_command *cmd, + const struct ssam_span *data) +{ + rtl_dbg(rtl, "rtl: handling event (rqid: %#06x)\n", + get_unaligned_le16(&cmd->rqid)); + + rtl->ops.handle_event(rtl, cmd, data); +} + +static void ssh_rtl_rx_command(struct ssh_ptl *p, const struct ssam_span *data) +{ + struct ssh_rtl *rtl = to_ssh_rtl(p, ptl); + struct device *dev = &p->serdev->dev; + struct ssh_command *command; + struct ssam_span command_data; + + if (sshp_parse_command(dev, data, &command, &command_data)) + return; + + if (ssh_rqid_is_event(get_unaligned_le16(&command->rqid))) + ssh_rtl_rx_event(rtl, command, &command_data); + else + ssh_rtl_complete(rtl, command, &command_data); +} + +static void ssh_rtl_rx_data(struct ssh_ptl *p, const struct ssam_span *data) +{ + if (!data->len) { + ptl_err(p, "rtl: rx: no data frame payload\n"); + return; + } + + switch (data->ptr[0]) { + case SSH_PLD_TYPE_CMD: + ssh_rtl_rx_command(p, data); + break; + + default: + ptl_err(p, "rtl: rx: unknown frame payload type (type: %#04x)\n", + data->ptr[0]); + break; + } +} + +static void ssh_rtl_packet_release(struct ssh_packet *p) +{ + struct ssh_request *rqst; + + rqst = to_ssh_request(p); + rqst->ops->release(rqst); +} + +static const struct ssh_packet_ops ssh_rtl_packet_ops = { + .complete = ssh_rtl_packet_callback, + .release = ssh_rtl_packet_release, +}; + +/** + * ssh_request_init() - Initialize SSH request. + * @rqst: The request to initialize. + * @flags: Request flags, determining the type of the request. + * @ops: Request operations. + * + * Initializes the given SSH request and underlying packet. Sets the message + * buffer pointer to %NULL and the message buffer length to zero. This buffer + * has to be set separately via ssh_request_set_data() before submission and + * must contain a valid SSH request message. + * + * Return: Returns zero on success or %-EINVAL if the given flags are invalid. + */ +int ssh_request_init(struct ssh_request *rqst, enum ssam_request_flags flags, + const struct ssh_request_ops *ops) +{ + unsigned long type = BIT(SSH_PACKET_TY_BLOCKING_BIT); + + /* Unsequenced requests cannot have a response. */ + if (flags & SSAM_REQUEST_UNSEQUENCED && flags & SSAM_REQUEST_HAS_RESPONSE) + return -EINVAL; + + if (!(flags & SSAM_REQUEST_UNSEQUENCED)) + type |= BIT(SSH_PACKET_TY_SEQUENCED_BIT); + + ssh_packet_init(&rqst->packet, type, SSH_PACKET_PRIORITY(DATA, 0), + &ssh_rtl_packet_ops); + + INIT_LIST_HEAD(&rqst->node); + + rqst->state = 0; + if (flags & SSAM_REQUEST_HAS_RESPONSE) + rqst->state |= BIT(SSH_REQUEST_TY_HAS_RESPONSE_BIT); + + rqst->timestamp = KTIME_MAX; + rqst->ops = ops; + + return 0; +} + +/** + * ssh_rtl_init() - Initialize request transport layer. + * @rtl: The request transport layer to initialize. + * @serdev: The underlying serial device, i.e. the lower-level transport. + * @ops: Request transport layer operations. + * + * Initializes the given request transport layer and associated packet + * transport layer. Transmitter and receiver threads must be started + * separately via ssh_rtl_tx_start() and ssh_rtl_rx_start(), after the + * request-layer has been initialized and the lower-level serial device layer + * has been set up. + * + * Return: Returns zero on success and a nonzero error code on failure. + */ +int ssh_rtl_init(struct ssh_rtl *rtl, struct serdev_device *serdev, + const struct ssh_rtl_ops *ops) +{ + struct ssh_ptl_ops ptl_ops; + int status; + + ptl_ops.data_received = ssh_rtl_rx_data; + + status = ssh_ptl_init(&rtl->ptl, serdev, &ptl_ops); + if (status) + return status; + + spin_lock_init(&rtl->queue.lock); + INIT_LIST_HEAD(&rtl->queue.head); + + spin_lock_init(&rtl->pending.lock); + INIT_LIST_HEAD(&rtl->pending.head); + atomic_set_release(&rtl->pending.count, 0); + + INIT_WORK(&rtl->tx.work, ssh_rtl_tx_work_fn); + + spin_lock_init(&rtl->rtx_timeout.lock); + rtl->rtx_timeout.timeout = SSH_RTL_REQUEST_TIMEOUT; + rtl->rtx_timeout.expires = KTIME_MAX; + INIT_DELAYED_WORK(&rtl->rtx_timeout.reaper, ssh_rtl_timeout_reap); + + rtl->ops = *ops; + + return 0; +} + +/** + * ssh_rtl_destroy() - Deinitialize request transport layer. + * @rtl: The request transport layer to deinitialize. + * + * Deinitializes the given request transport layer and frees resources + * associated with it. If receiver and/or transmitter threads have been + * started, the layer must first be shut down via ssh_rtl_shutdown() before + * this function can be called. + */ +void ssh_rtl_destroy(struct ssh_rtl *rtl) +{ + ssh_ptl_destroy(&rtl->ptl); +} + +/** + * ssh_rtl_tx_start() - Start request transmitter and receiver. + * @rtl: The request transport layer. + * + * Return: Returns zero on success, a negative error code on failure. + */ +int ssh_rtl_start(struct ssh_rtl *rtl) +{ + int status; + + status = ssh_ptl_tx_start(&rtl->ptl); + if (status) + return status; + + ssh_rtl_tx_schedule(rtl); + + status = ssh_ptl_rx_start(&rtl->ptl); + if (status) { + ssh_rtl_flush(rtl, msecs_to_jiffies(5000)); + ssh_ptl_tx_stop(&rtl->ptl); + return status; + } + + return 0; +} + +struct ssh_flush_request { + struct ssh_request base; + struct completion completion; + int status; +}; + +static void ssh_rtl_flush_request_complete(struct ssh_request *r, + const struct ssh_command *cmd, + const struct ssam_span *data, + int status) +{ + struct ssh_flush_request *rqst; + + rqst = container_of(r, struct ssh_flush_request, base); + rqst->status = status; +} + +static void ssh_rtl_flush_request_release(struct ssh_request *r) +{ + struct ssh_flush_request *rqst; + + rqst = container_of(r, struct ssh_flush_request, base); + complete_all(&rqst->completion); +} + +static const struct ssh_request_ops ssh_rtl_flush_request_ops = { + .complete = ssh_rtl_flush_request_complete, + .release = ssh_rtl_flush_request_release, +}; + +/** + * ssh_rtl_flush() - Flush the request transport layer. + * @rtl: request transport layer + * @timeout: timeout for the flush operation in jiffies + * + * Queue a special flush request and wait for its completion. This request + * will be completed after all other currently queued and pending requests + * have been completed. Instead of a normal data packet, this request submits + * a special flush packet, meaning that upon completion, also the underlying + * packet transport layer has been flushed. + * + * Flushing the request layer guarantees that all previously submitted + * requests have been fully completed before this call returns. Additionally, + * flushing blocks execution of all later submitted requests until the flush + * has been completed. + * + * If the caller ensures that no new requests are submitted after a call to + * this function, the request transport layer is guaranteed to have no + * remaining requests when this call returns. The same guarantee does not hold + * for the packet layer, on which control packets may still be queued after + * this call. + * + * Return: Returns zero on success, %-ETIMEDOUT if the flush timed out and has + * been canceled as a result of the timeout, or %-ESHUTDOWN if the packet + * and/or request transport layer has been shut down before this call. May + * also return %-EINTR if the underlying packet transmission has been + * interrupted. + */ +int ssh_rtl_flush(struct ssh_rtl *rtl, unsigned long timeout) +{ + const unsigned int init_flags = SSAM_REQUEST_UNSEQUENCED; + struct ssh_flush_request rqst; + int status; + + ssh_request_init(&rqst.base, init_flags, &ssh_rtl_flush_request_ops); + rqst.base.packet.state |= BIT(SSH_PACKET_TY_FLUSH_BIT); + rqst.base.packet.priority = SSH_PACKET_PRIORITY(FLUSH, 0); + rqst.base.state |= BIT(SSH_REQUEST_TY_FLUSH_BIT); + + init_completion(&rqst.completion); + + status = ssh_rtl_submit(rtl, &rqst.base); + if (status) + return status; + + ssh_request_put(&rqst.base); + + if (!wait_for_completion_timeout(&rqst.completion, timeout)) { + ssh_rtl_cancel(&rqst.base, true); + wait_for_completion(&rqst.completion); + } + + WARN_ON(rqst.status != 0 && rqst.status != -ECANCELED && + rqst.status != -ESHUTDOWN && rqst.status != -EINTR); + + return rqst.status == -ECANCELED ? -ETIMEDOUT : rqst.status; +} + +/** + * ssh_rtl_shutdown() - Shut down request transport layer. + * @rtl: The request transport layer. + * + * Shuts down the request transport layer, removing and canceling all queued + * and pending requests. Requests canceled by this operation will be completed + * with %-ESHUTDOWN as status. Receiver and transmitter threads will be + * stopped, the lower-level packet layer will be shutdown. + * + * As a result of this function, the transport layer will be marked as shut + * down. Submission of requests after the transport layer has been shut down + * will fail with %-ESHUTDOWN. + */ +void ssh_rtl_shutdown(struct ssh_rtl *rtl) +{ + struct ssh_request *r, *n; + LIST_HEAD(claimed); + int pending; + + set_bit(SSH_RTL_SF_SHUTDOWN_BIT, &rtl->state); + /* + * Ensure that the layer gets marked as shut-down before actually + * stopping it. In combination with the check in ssh_rtl_submit(), + * this guarantees that no new requests can be added and all already + * queued requests are properly canceled. + */ + smp_mb__after_atomic(); + + /* Remove requests from queue. */ + spin_lock(&rtl->queue.lock); + list_for_each_entry_safe(r, n, &rtl->queue.head, node) { + set_bit(SSH_REQUEST_SF_LOCKED_BIT, &r->state); + /* Ensure state never gets zero. */ + smp_mb__before_atomic(); + clear_bit(SSH_REQUEST_SF_QUEUED_BIT, &r->state); + + list_del(&r->node); + list_add_tail(&r->node, &claimed); + } + spin_unlock(&rtl->queue.lock); + + /* + * We have now guaranteed that the queue is empty and no more new + * requests can be submitted (i.e. it will stay empty). This means that + * calling ssh_rtl_tx_schedule() will not schedule tx.work any more. So + * we can simply call cancel_work_sync() on tx.work here and when that + * returns, we've locked it down. This also means that after this call, + * we don't submit any more packets to the underlying packet layer, so + * we can also shut that down. + */ + + cancel_work_sync(&rtl->tx.work); + ssh_ptl_shutdown(&rtl->ptl); + cancel_delayed_work_sync(&rtl->rtx_timeout.reaper); + + /* + * Shutting down the packet layer should also have canceled all + * requests. Thus the pending set should be empty. Attempt to handle + * this gracefully anyways, even though this should be dead code. + */ + + pending = atomic_read(&rtl->pending.count); + if (WARN_ON(pending)) { + spin_lock(&rtl->pending.lock); + list_for_each_entry_safe(r, n, &rtl->pending.head, node) { + set_bit(SSH_REQUEST_SF_LOCKED_BIT, &r->state); + /* Ensure state never gets zero. */ + smp_mb__before_atomic(); + clear_bit(SSH_REQUEST_SF_PENDING_BIT, &r->state); + + list_del(&r->node); + list_add_tail(&r->node, &claimed); + } + spin_unlock(&rtl->pending.lock); + } + + /* Finally, cancel and complete the requests we claimed before. */ + list_for_each_entry_safe(r, n, &claimed, node) { + /* + * We need test_and_set() because we still might compete with + * cancellation. + */ + if (!test_and_set_bit(SSH_REQUEST_SF_COMPLETED_BIT, &r->state)) + ssh_rtl_complete_with_status(r, -ESHUTDOWN); + + /* + * Drop the reference we've obtained by removing it from the + * lists. + */ + list_del(&r->node); + ssh_request_put(r); + } +} diff --git a/drivers/platform/surface/aggregator/ssh_request_layer.h b/drivers/platform/surface/aggregator/ssh_request_layer.h new file mode 100644 index 000000000000..cb35815858d1 --- /dev/null +++ b/drivers/platform/surface/aggregator/ssh_request_layer.h @@ -0,0 +1,143 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * SSH request transport layer. + * + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#ifndef _SURFACE_AGGREGATOR_SSH_REQUEST_LAYER_H +#define _SURFACE_AGGREGATOR_SSH_REQUEST_LAYER_H + +#include <linux/atomic.h> +#include <linux/ktime.h> +#include <linux/list.h> +#include <linux/spinlock.h> +#include <linux/workqueue.h> + +#include <linux/surface_aggregator/serial_hub.h> +#include <linux/surface_aggregator/controller.h> + +#include "ssh_packet_layer.h" + +/** + * enum ssh_rtl_state_flags - State-flags for &struct ssh_rtl. + * + * @SSH_RTL_SF_SHUTDOWN_BIT: + * Indicates that the request transport layer has been shut down or is + * being shut down and should not accept any new requests. + */ +enum ssh_rtl_state_flags { + SSH_RTL_SF_SHUTDOWN_BIT, +}; + +/** + * struct ssh_rtl_ops - Callback operations for request transport layer. + * @handle_event: Function called when a SSH event has been received. The + * specified function takes the request layer, received command + * struct, and corresponding payload as arguments. If the event + * has no payload, the payload span is empty (not %NULL). + */ +struct ssh_rtl_ops { + void (*handle_event)(struct ssh_rtl *rtl, const struct ssh_command *cmd, + const struct ssam_span *data); +}; + +/** + * struct ssh_rtl - SSH request transport layer. + * @ptl: Underlying packet transport layer. + * @state: State(-flags) of the transport layer. + * @queue: Request submission queue. + * @queue.lock: Lock for modifying the request submission queue. + * @queue.head: List-head of the request submission queue. + * @pending: Set/list of pending requests. + * @pending.lock: Lock for modifying the request set. + * @pending.head: List-head of the pending set/list. + * @pending.count: Number of currently pending requests. + * @tx: Transmitter subsystem. + * @tx.work: Transmitter work item. + * @rtx_timeout: Retransmission timeout subsystem. + * @rtx_timeout.lock: Lock for modifying the retransmission timeout reaper. + * @rtx_timeout.timeout: Timeout interval for retransmission. + * @rtx_timeout.expires: Time specifying when the reaper work is next scheduled. + * @rtx_timeout.reaper: Work performing timeout checks and subsequent actions. + * @ops: Request layer operations. + */ +struct ssh_rtl { + struct ssh_ptl ptl; + unsigned long state; + + struct { + spinlock_t lock; + struct list_head head; + } queue; + + struct { + spinlock_t lock; + struct list_head head; + atomic_t count; + } pending; + + struct { + struct work_struct work; + } tx; + + struct { + spinlock_t lock; + ktime_t timeout; + ktime_t expires; + struct delayed_work reaper; + } rtx_timeout; + + struct ssh_rtl_ops ops; +}; + +#define rtl_dbg(r, fmt, ...) ptl_dbg(&(r)->ptl, fmt, ##__VA_ARGS__) +#define rtl_info(p, fmt, ...) ptl_info(&(p)->ptl, fmt, ##__VA_ARGS__) +#define rtl_warn(r, fmt, ...) ptl_warn(&(r)->ptl, fmt, ##__VA_ARGS__) +#define rtl_err(r, fmt, ...) ptl_err(&(r)->ptl, fmt, ##__VA_ARGS__) +#define rtl_dbg_cond(r, fmt, ...) __ssam_prcond(rtl_dbg, r, fmt, ##__VA_ARGS__) + +#define to_ssh_rtl(ptr, member) \ + container_of(ptr, struct ssh_rtl, member) + +/** + * ssh_rtl_get_device() - Get device associated with request transport layer. + * @rtl: The request transport layer. + * + * Return: Returns the device on which the given request transport layer + * builds upon. + */ +static inline struct device *ssh_rtl_get_device(struct ssh_rtl *rtl) +{ + return ssh_ptl_get_device(&rtl->ptl); +} + +/** + * ssh_request_rtl() - Get request transport layer associated with request. + * @rqst: The request to get the request transport layer reference for. + * + * Return: Returns the &struct ssh_rtl associated with the given SSH request. + */ +static inline struct ssh_rtl *ssh_request_rtl(struct ssh_request *rqst) +{ + struct ssh_ptl *ptl; + + ptl = READ_ONCE(rqst->packet.ptl); + return likely(ptl) ? to_ssh_rtl(ptl, ptl) : NULL; +} + +int ssh_rtl_submit(struct ssh_rtl *rtl, struct ssh_request *rqst); +bool ssh_rtl_cancel(struct ssh_request *rqst, bool pending); + +int ssh_rtl_init(struct ssh_rtl *rtl, struct serdev_device *serdev, + const struct ssh_rtl_ops *ops); + +int ssh_rtl_start(struct ssh_rtl *rtl); +int ssh_rtl_flush(struct ssh_rtl *rtl, unsigned long timeout); +void ssh_rtl_shutdown(struct ssh_rtl *rtl); +void ssh_rtl_destroy(struct ssh_rtl *rtl); + +int ssh_request_init(struct ssh_request *rqst, enum ssam_request_flags flags, + const struct ssh_request_ops *ops); + +#endif /* _SURFACE_AGGREGATOR_SSH_REQUEST_LAYER_H */ diff --git a/include/linux/surface_aggregator/controller.h b/include/linux/surface_aggregator/controller.h new file mode 100644 index 000000000000..f4b1ba887384 --- /dev/null +++ b/include/linux/surface_aggregator/controller.h @@ -0,0 +1,824 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * Surface System Aggregator Module (SSAM) controller interface. + * + * Main communication interface for the SSAM EC. Provides a controller + * managing access and communication to and from the SSAM EC, as well as main + * communication structures and definitions. + * + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#ifndef _LINUX_SURFACE_AGGREGATOR_CONTROLLER_H +#define _LINUX_SURFACE_AGGREGATOR_CONTROLLER_H + +#include <linux/completion.h> +#include <linux/device.h> +#include <linux/types.h> + +#include <linux/surface_aggregator/serial_hub.h> + + +/* -- Main data types and definitions --------------------------------------- */ + +/** + * enum ssam_event_flags - Flags for enabling/disabling SAM events + * @SSAM_EVENT_SEQUENCED: The event will be sent via a sequenced data frame. + */ +enum ssam_event_flags { + SSAM_EVENT_SEQUENCED = BIT(0), +}; + +/** + * struct ssam_event - SAM event sent from the EC to the host. + * @target_category: Target category of the event source. See &enum ssam_ssh_tc. + * @target_id: Target ID of the event source. + * @command_id: Command ID of the event. + * @instance_id: Instance ID of the event source. + * @length: Length of the event payload in bytes. + * @data: Event payload data. + */ +struct ssam_event { + u8 target_category; + u8 target_id; + u8 command_id; + u8 instance_id; + u16 length; + u8 data[]; +}; + +/** + * enum ssam_request_flags - Flags for SAM requests. + * + * @SSAM_REQUEST_HAS_RESPONSE: + * Specifies that the request expects a response. If not set, the request + * will be directly completed after its underlying packet has been + * transmitted. If set, the request transport system waits for a response + * of the request. + * + * @SSAM_REQUEST_UNSEQUENCED: + * Specifies that the request should be transmitted via an unsequenced + * packet. If set, the request must not have a response, meaning that this + * flag and the %SSAM_REQUEST_HAS_RESPONSE flag are mutually exclusive. + */ +enum ssam_request_flags { + SSAM_REQUEST_HAS_RESPONSE = BIT(0), + SSAM_REQUEST_UNSEQUENCED = BIT(1), +}; + +/** + * struct ssam_request - SAM request description. + * @target_category: Category of the request's target. See &enum ssam_ssh_tc. + * @target_id: ID of the request's target. + * @command_id: Command ID of the request. + * @instance_id: Instance ID of the request's target. + * @flags: Flags for the request. See &enum ssam_request_flags. + * @length: Length of the request payload in bytes. + * @payload: Request payload data. + * + * This struct fully describes a SAM request with payload. It is intended to + * help set up the actual transport struct, e.g. &struct ssam_request_sync, + * and specifically its raw message data via ssam_request_write_data(). + */ +struct ssam_request { + u8 target_category; + u8 target_id; + u8 command_id; + u8 instance_id; + u16 flags; + u16 length; + const u8 *payload; +}; + +/** + * struct ssam_response - Response buffer for SAM request. + * @capacity: Capacity of the buffer, in bytes. + * @length: Length of the actual data stored in the memory pointed to by + * @pointer, in bytes. Set by the transport system. + * @pointer: Pointer to the buffer's memory, storing the response payload data. + */ +struct ssam_response { + size_t capacity; + size_t length; + u8 *pointer; +}; + +struct ssam_controller; + +struct ssam_controller *ssam_get_controller(void); +struct ssam_controller *ssam_client_bind(struct device *client); +int ssam_client_link(struct ssam_controller *ctrl, struct device *client); + +struct device *ssam_controller_device(struct ssam_controller *c); + +struct ssam_controller *ssam_controller_get(struct ssam_controller *c); +void ssam_controller_put(struct ssam_controller *c); + +void ssam_controller_statelock(struct ssam_controller *c); +void ssam_controller_stateunlock(struct ssam_controller *c); + +ssize_t ssam_request_write_data(struct ssam_span *buf, + struct ssam_controller *ctrl, + const struct ssam_request *spec); + + +/* -- Synchronous request interface. ---------------------------------------- */ + +/** + * struct ssam_request_sync - Synchronous SAM request struct. + * @base: Underlying SSH request. + * @comp: Completion used to signal full completion of the request. After the + * request has been submitted, this struct may only be modified or + * deallocated after the completion has been signaled. + * request has been submitted, + * @resp: Buffer to store the response. + * @status: Status of the request, set after the base request has been + * completed or has failed. + */ +struct ssam_request_sync { + struct ssh_request base; + struct completion comp; + struct ssam_response *resp; + int status; +}; + +int ssam_request_sync_alloc(size_t payload_len, gfp_t flags, + struct ssam_request_sync **rqst, + struct ssam_span *buffer); + +void ssam_request_sync_free(struct ssam_request_sync *rqst); + +int ssam_request_sync_init(struct ssam_request_sync *rqst, + enum ssam_request_flags flags); + +/** + * ssam_request_sync_set_data - Set message data of a synchronous request. + * @rqst: The request. + * @ptr: Pointer to the request message data. + * @len: Length of the request message data. + * + * Set the request message data of a synchronous request. The provided buffer + * needs to live until the request has been completed. + */ +static inline void ssam_request_sync_set_data(struct ssam_request_sync *rqst, + u8 *ptr, size_t len) +{ + ssh_request_set_data(&rqst->base, ptr, len); +} + +/** + * ssam_request_sync_set_resp - Set response buffer of a synchronous request. + * @rqst: The request. + * @resp: The response buffer. + * + * Sets the response buffer of a synchronous request. This buffer will store + * the response of the request after it has been completed. May be %NULL if no + * response is expected. + */ +static inline void ssam_request_sync_set_resp(struct ssam_request_sync *rqst, + struct ssam_response *resp) +{ + rqst->resp = resp; +} + +int ssam_request_sync_submit(struct ssam_controller *ctrl, + struct ssam_request_sync *rqst); + +/** + * ssam_request_sync_wait - Wait for completion of a synchronous request. + * @rqst: The request to wait for. + * + * Wait for completion and release of a synchronous request. After this + * function terminates, the request is guaranteed to have left the transport + * system. After successful submission of a request, this function must be + * called before accessing the response of the request, freeing the request, + * or freeing any of the buffers associated with the request. + * + * This function must not be called if the request has not been submitted yet + * and may lead to a deadlock/infinite wait if a subsequent request submission + * fails in that case, due to the completion never triggering. + * + * Return: Returns the status of the given request, which is set on completion + * of the packet. This value is zero on success and negative on failure. + */ +static inline int ssam_request_sync_wait(struct ssam_request_sync *rqst) +{ + wait_for_completion(&rqst->comp); + return rqst->status; +} + +int ssam_request_sync(struct ssam_controller *ctrl, + const struct ssam_request *spec, + struct ssam_response *rsp); + +int ssam_request_sync_with_buffer(struct ssam_controller *ctrl, + const struct ssam_request *spec, + struct ssam_response *rsp, + struct ssam_span *buf); + +/** + * ssam_request_sync_onstack - Execute a synchronous request on the stack. + * @ctrl: The controller via which the request is submitted. + * @rqst: The request specification. + * @rsp: The response buffer. + * @payload_len: The (maximum) request payload length. + * + * Allocates a synchronous request with specified payload length on the stack, + * fully initializes it via the provided request specification, submits it, + * and finally waits for its completion before returning its status. This + * helper macro essentially allocates the request message buffer on the stack + * and then calls ssam_request_sync_with_buffer(). + * + * Note: The @payload_len parameter specifies the maximum payload length, used + * for buffer allocation. The actual payload length may be smaller. + * + * Return: Returns the status of the request or any failure during setup, i.e. + * zero on success and a negative value on failure. + */ +#define ssam_request_sync_onstack(ctrl, rqst, rsp, payload_len) \ + ({ \ + u8 __data[SSH_COMMAND_MESSAGE_LENGTH(payload_len)]; \ + struct ssam_span __buf = { &__data[0], ARRAY_SIZE(__data) }; \ + \ + ssam_request_sync_with_buffer(ctrl, rqst, rsp, &__buf); \ + }) + +/** + * __ssam_retry - Retry request in case of I/O errors or timeouts. + * @request: The request function to execute. Must return an integer. + * @n: Number of tries. + * @args: Arguments for the request function. + * + * Executes the given request function, i.e. calls @request. In case the + * request returns %-EREMOTEIO (indicates I/O error) or %-ETIMEDOUT (request + * or underlying packet timed out), @request will be re-executed again, up to + * @n times in total. + * + * Return: Returns the return value of the last execution of @request. + */ +#define __ssam_retry(request, n, args...) \ + ({ \ + int __i, __s = 0; \ + \ + for (__i = (n); __i > 0; __i--) { \ + __s = request(args); \ + if (__s != -ETIMEDOUT && __s != -EREMOTEIO) \ + break; \ + } \ + __s; \ + }) + +/** + * ssam_retry - Retry request in case of I/O errors or timeouts up to three + * times in total. + * @request: The request function to execute. Must return an integer. + * @args: Arguments for the request function. + * + * Executes the given request function, i.e. calls @request. In case the + * request returns %-EREMOTEIO (indicates I/O error) or -%ETIMEDOUT (request + * or underlying packet timed out), @request will be re-executed again, up to + * three times in total. + * + * See __ssam_retry() for a more generic macro for this purpose. + * + * Return: Returns the return value of the last execution of @request. + */ +#define ssam_retry(request, args...) \ + __ssam_retry(request, 3, args) + +/** + * struct ssam_request_spec - Blue-print specification of SAM request. + * @target_category: Category of the request's target. See &enum ssam_ssh_tc. + * @target_id: ID of the request's target. + * @command_id: Command ID of the request. + * @instance_id: Instance ID of the request's target. + * @flags: Flags for the request. See &enum ssam_request_flags. + * + * Blue-print specification for a SAM request. This struct describes the + * unique static parameters of a request (i.e. type) without specifying any of + * its instance-specific data (e.g. payload). It is intended to be used as base + * for defining simple request functions via the + * ``SSAM_DEFINE_SYNC_REQUEST_x()`` family of macros. + */ +struct ssam_request_spec { + u8 target_category; + u8 target_id; + u8 command_id; + u8 instance_id; + u8 flags; +}; + +/** + * struct ssam_request_spec_md - Blue-print specification for multi-device SAM + * request. + * @target_category: Category of the request's target. See &enum ssam_ssh_tc. + * @command_id: Command ID of the request. + * @flags: Flags for the request. See &enum ssam_request_flags. + * + * Blue-print specification for a multi-device SAM request, i.e. a request + * that is applicable to multiple device instances, described by their + * individual target and instance IDs. This struct describes the unique static + * parameters of a request (i.e. type) without specifying any of its + * instance-specific data (e.g. payload) and without specifying any of its + * device specific IDs (i.e. target and instance ID). It is intended to be + * used as base for defining simple multi-device request functions via the + * ``SSAM_DEFINE_SYNC_REQUEST_MD_x()`` and ``SSAM_DEFINE_SYNC_REQUEST_CL_x()`` + * families of macros. + */ +struct ssam_request_spec_md { + u8 target_category; + u8 command_id; + u8 flags; +}; + +/** + * SSAM_DEFINE_SYNC_REQUEST_N() - Define synchronous SAM request function + * with neither argument nor return value. + * @name: Name of the generated function. + * @spec: Specification (&struct ssam_request_spec) defining the request. + * + * Defines a function executing the synchronous SAM request specified by + * @spec, with the request having neither argument nor return value. The + * generated function takes care of setting up the request struct and buffer + * allocation, as well as execution of the request itself, returning once the + * request has been fully completed. The required transport buffer will be + * allocated on the stack. + * + * The generated function is defined as ``int name(struct ssam_controller + * *ctrl)``, returning the status of the request, which is zero on success and + * negative on failure. The ``ctrl`` parameter is the controller via which the + * request is being sent. + * + * Refer to ssam_request_sync_onstack() for more details on the behavior of + * the generated function. + */ +#define SSAM_DEFINE_SYNC_REQUEST_N(name, spec...) \ + int name(struct ssam_controller *ctrl) \ + { \ + struct ssam_request_spec s = (struct ssam_request_spec)spec; \ + struct ssam_request rqst; \ + \ + rqst.target_category = s.target_category; \ + rqst.target_id = s.target_id; \ + rqst.command_id = s.command_id; \ + rqst.instance_id = s.instance_id; \ + rqst.flags = s.flags; \ + rqst.length = 0; \ + rqst.payload = NULL; \ + \ + return ssam_request_sync_onstack(ctrl, &rqst, NULL, 0); \ + } + +/** + * SSAM_DEFINE_SYNC_REQUEST_W() - Define synchronous SAM request function with + * argument. + * @name: Name of the generated function. + * @atype: Type of the request's argument. + * @spec: Specification (&struct ssam_request_spec) defining the request. + * + * Defines a function executing the synchronous SAM request specified by + * @spec, with the request taking an argument of type @atype and having no + * return value. The generated function takes care of setting up the request + * struct, buffer allocation, as well as execution of the request itself, + * returning once the request has been fully completed. The required transport + * buffer will be allocated on the stack. + * + * The generated function is defined as ``int name(struct ssam_controller + * *ctrl, const atype *arg)``, returning the status of the request, which is + * zero on success and negative on failure. The ``ctrl`` parameter is the + * controller via which the request is sent. The request argument is specified + * via the ``arg`` pointer. + * + * Refer to ssam_request_sync_onstack() for more details on the behavior of + * the generated function. + */ +#define SSAM_DEFINE_SYNC_REQUEST_W(name, atype, spec...) \ + int name(struct ssam_controller *ctrl, const atype *arg) \ + { \ + struct ssam_request_spec s = (struct ssam_request_spec)spec; \ + struct ssam_request rqst; \ + \ + rqst.target_category = s.target_category; \ + rqst.target_id = s.target_id; \ + rqst.command_id = s.command_id; \ + rqst.instance_id = s.instance_id; \ + rqst.flags = s.flags; \ + rqst.length = sizeof(atype); \ + rqst.payload = (u8 *)arg; \ + \ + return ssam_request_sync_onstack(ctrl, &rqst, NULL, \ + sizeof(atype)); \ + } + +/** + * SSAM_DEFINE_SYNC_REQUEST_R() - Define synchronous SAM request function with + * return value. + * @name: Name of the generated function. + * @rtype: Type of the request's return value. + * @spec: Specification (&struct ssam_request_spec) defining the request. + * + * Defines a function executing the synchronous SAM request specified by + * @spec, with the request taking no argument but having a return value of + * type @rtype. The generated function takes care of setting up the request + * and response structs, buffer allocation, as well as execution of the + * request itself, returning once the request has been fully completed. The + * required transport buffer will be allocated on the stack. + * + * The generated function is defined as ``int name(struct ssam_controller + * *ctrl, rtype *ret)``, returning the status of the request, which is zero on + * success and negative on failure. The ``ctrl`` parameter is the controller + * via which the request is sent. The request's return value is written to the + * memory pointed to by the ``ret`` parameter. + * + * Refer to ssam_request_sync_onstack() for more details on the behavior of + * the generated function. + */ +#define SSAM_DEFINE_SYNC_REQUEST_R(name, rtype, spec...) \ + int name(struct ssam_controller *ctrl, rtype *ret) \ + { \ + struct ssam_request_spec s = (struct ssam_request_spec)spec; \ + struct ssam_request rqst; \ + struct ssam_response rsp; \ + int status; \ + \ + rqst.target_category = s.target_category; \ + rqst.target_id = s.target_id; \ + rqst.command_id = s.command_id; \ + rqst.instance_id = s.instance_id; \ + rqst.flags = s.flags | SSAM_REQUEST_HAS_RESPONSE; \ + rqst.length = 0; \ + rqst.payload = NULL; \ + \ + rsp.capacity = sizeof(rtype); \ + rsp.length = 0; \ + rsp.pointer = (u8 *)ret; \ + \ + status = ssam_request_sync_onstack(ctrl, &rqst, &rsp, 0); \ + if (status) \ + return status; \ + \ + if (rsp.length != sizeof(rtype)) { \ + struct device *dev = ssam_controller_device(ctrl); \ + dev_err(dev, \ + "rqst: invalid response length, expected %zu, got %zu (tc: %#04x, cid: %#04x)", \ + sizeof(rtype), rsp.length, rqst.target_category,\ + rqst.command_id); \ + return -EIO; \ + } \ + \ + return 0; \ + } + +/** + * SSAM_DEFINE_SYNC_REQUEST_MD_N() - Define synchronous multi-device SAM + * request function with neither argument nor return value. + * @name: Name of the generated function. + * @spec: Specification (&struct ssam_request_spec_md) defining the request. + * + * Defines a function executing the synchronous SAM request specified by + * @spec, with the request having neither argument nor return value. Device + * specifying parameters are not hard-coded, but instead must be provided to + * the function. The generated function takes care of setting up the request + * struct, buffer allocation, as well as execution of the request itself, + * returning once the request has been fully completed. The required transport + * buffer will be allocated on the stack. + * + * The generated function is defined as ``int name(struct ssam_controller + * *ctrl, u8 tid, u8 iid)``, returning the status of the request, which is + * zero on success and negative on failure. The ``ctrl`` parameter is the + * controller via which the request is sent, ``tid`` the target ID for the + * request, and ``iid`` the instance ID. + * + * Refer to ssam_request_sync_onstack() for more details on the behavior of + * the generated function. + */ +#define SSAM_DEFINE_SYNC_REQUEST_MD_N(name, spec...) \ + int name(struct ssam_controller *ctrl, u8 tid, u8 iid) \ + { \ + struct ssam_request_spec_md s = (struct ssam_request_spec_md)spec; \ + struct ssam_request rqst; \ + \ + rqst.target_category = s.target_category; \ + rqst.target_id = tid; \ + rqst.command_id = s.command_id; \ + rqst.instance_id = iid; \ + rqst.flags = s.flags; \ + rqst.length = 0; \ + rqst.payload = NULL; \ + \ + return ssam_request_sync_onstack(ctrl, &rqst, NULL, 0); \ + } + +/** + * SSAM_DEFINE_SYNC_REQUEST_MD_W() - Define synchronous multi-device SAM + * request function with argument. + * @name: Name of the generated function. + * @atype: Type of the request's argument. + * @spec: Specification (&struct ssam_request_spec_md) defining the request. + * + * Defines a function executing the synchronous SAM request specified by + * @spec, with the request taking an argument of type @atype and having no + * return value. Device specifying parameters are not hard-coded, but instead + * must be provided to the function. The generated function takes care of + * setting up the request struct, buffer allocation, as well as execution of + * the request itself, returning once the request has been fully completed. + * The required transport buffer will be allocated on the stack. + * + * The generated function is defined as ``int name(struct ssam_controller + * *ctrl, u8 tid, u8 iid, const atype *arg)``, returning the status of the + * request, which is zero on success and negative on failure. The ``ctrl`` + * parameter is the controller via which the request is sent, ``tid`` the + * target ID for the request, and ``iid`` the instance ID. The request argument + * is specified via the ``arg`` pointer. + * + * Refer to ssam_request_sync_onstack() for more details on the behavior of + * the generated function. + */ +#define SSAM_DEFINE_SYNC_REQUEST_MD_W(name, atype, spec...) \ + int name(struct ssam_controller *ctrl, u8 tid, u8 iid, const atype *arg)\ + { \ + struct ssam_request_spec_md s = (struct ssam_request_spec_md)spec; \ + struct ssam_request rqst; \ + \ + rqst.target_category = s.target_category; \ + rqst.target_id = tid; \ + rqst.command_id = s.command_id; \ + rqst.instance_id = iid; \ + rqst.flags = s.flags; \ + rqst.length = sizeof(atype); \ + rqst.payload = (u8 *)arg; \ + \ + return ssam_request_sync_onstack(ctrl, &rqst, NULL, \ + sizeof(atype)); \ + } + +/** + * SSAM_DEFINE_SYNC_REQUEST_MD_R() - Define synchronous multi-device SAM + * request function with return value. + * @name: Name of the generated function. + * @rtype: Type of the request's return value. + * @spec: Specification (&struct ssam_request_spec_md) defining the request. + * + * Defines a function executing the synchronous SAM request specified by + * @spec, with the request taking no argument but having a return value of + * type @rtype. Device specifying parameters are not hard-coded, but instead + * must be provided to the function. The generated function takes care of + * setting up the request and response structs, buffer allocation, as well as + * execution of the request itself, returning once the request has been fully + * completed. The required transport buffer will be allocated on the stack. + * + * The generated function is defined as ``int name(struct ssam_controller + * *ctrl, u8 tid, u8 iid, rtype *ret)``, returning the status of the request, + * which is zero on success and negative on failure. The ``ctrl`` parameter is + * the controller via which the request is sent, ``tid`` the target ID for the + * request, and ``iid`` the instance ID. The request's return value is written + * to the memory pointed to by the ``ret`` parameter. + * + * Refer to ssam_request_sync_onstack() for more details on the behavior of + * the generated function. + */ +#define SSAM_DEFINE_SYNC_REQUEST_MD_R(name, rtype, spec...) \ + int name(struct ssam_controller *ctrl, u8 tid, u8 iid, rtype *ret) \ + { \ + struct ssam_request_spec_md s = (struct ssam_request_spec_md)spec; \ + struct ssam_request rqst; \ + struct ssam_response rsp; \ + int status; \ + \ + rqst.target_category = s.target_category; \ + rqst.target_id = tid; \ + rqst.command_id = s.command_id; \ + rqst.instance_id = iid; \ + rqst.flags = s.flags | SSAM_REQUEST_HAS_RESPONSE; \ + rqst.length = 0; \ + rqst.payload = NULL; \ + \ + rsp.capacity = sizeof(rtype); \ + rsp.length = 0; \ + rsp.pointer = (u8 *)ret; \ + \ + status = ssam_request_sync_onstack(ctrl, &rqst, &rsp, 0); \ + if (status) \ + return status; \ + \ + if (rsp.length != sizeof(rtype)) { \ + struct device *dev = ssam_controller_device(ctrl); \ + dev_err(dev, \ + "rqst: invalid response length, expected %zu, got %zu (tc: %#04x, cid: %#04x)", \ + sizeof(rtype), rsp.length, rqst.target_category,\ + rqst.command_id); \ + return -EIO; \ + } \ + \ + return 0; \ + } + + +/* -- Event notifier/callbacks. --------------------------------------------- */ + +#define SSAM_NOTIF_STATE_SHIFT 2 +#define SSAM_NOTIF_STATE_MASK ((1 << SSAM_NOTIF_STATE_SHIFT) - 1) + +/** + * enum ssam_notif_flags - Flags used in return values from SSAM notifier + * callback functions. + * + * @SSAM_NOTIF_HANDLED: + * Indicates that the notification has been handled. This flag should be + * set by the handler if the handler can act/has acted upon the event + * provided to it. This flag should not be set if the handler is not a + * primary handler intended for the provided event. + * + * If this flag has not been set by any handler after the notifier chain + * has been traversed, a warning will be emitted, stating that the event + * has not been handled. + * + * @SSAM_NOTIF_STOP: + * Indicates that the notifier traversal should stop. If this flag is + * returned from a notifier callback, notifier chain traversal will + * immediately stop and any remaining notifiers will not be called. This + * flag is automatically set when ssam_notifier_from_errno() is called + * with a negative error value. + */ +enum ssam_notif_flags { + SSAM_NOTIF_HANDLED = BIT(0), + SSAM_NOTIF_STOP = BIT(1), +}; + +struct ssam_event_notifier; + +typedef u32 (*ssam_notifier_fn_t)(struct ssam_event_notifier *nf, + const struct ssam_event *event); + +/** + * struct ssam_notifier_block - Base notifier block for SSAM event + * notifications. + * @node: The node for the list of notifiers. + * @fn: The callback function of this notifier. This function takes the + * respective notifier block and event as input and should return + * a notifier value, which can either be obtained from the flags + * provided in &enum ssam_notif_flags, converted from a standard + * error value via ssam_notifier_from_errno(), or a combination of + * both (e.g. ``ssam_notifier_from_errno(e) | SSAM_NOTIF_HANDLED``). + * @priority: Priority value determining the order in which notifier callbacks + * will be called. A higher value means higher priority, i.e. the + * associated callback will be executed earlier than other (lower + * priority) callbacks. + */ +struct ssam_notifier_block { + struct list_head node; + ssam_notifier_fn_t fn; + int priority; +}; + +/** + * ssam_notifier_from_errno() - Convert standard error value to notifier + * return code. + * @err: The error code to convert, must be negative (in case of failure) or + * zero (in case of success). + * + * Return: Returns the notifier return value obtained by converting the + * specified @err value. In case @err is negative, the %SSAM_NOTIF_STOP flag + * will be set, causing notifier call chain traversal to abort. + */ +static inline u32 ssam_notifier_from_errno(int err) +{ + if (WARN_ON(err > 0) || err == 0) + return 0; + else + return ((-err) << SSAM_NOTIF_STATE_SHIFT) | SSAM_NOTIF_STOP; +} + +/** + * ssam_notifier_to_errno() - Convert notifier return code to standard error + * value. + * @ret: The notifier return value to convert. + * + * Return: Returns the negative error value encoded in @ret or zero if @ret + * indicates success. + */ +static inline int ssam_notifier_to_errno(u32 ret) +{ + return -(ret >> SSAM_NOTIF_STATE_SHIFT); +} + + +/* -- Event/notification registry. ------------------------------------------ */ + +/** + * struct ssam_event_registry - Registry specification used for enabling events. + * @target_category: Target category for the event registry requests. + * @target_id: Target ID for the event registry requests. + * @cid_enable: Command ID for the event-enable request. + * @cid_disable: Command ID for the event-disable request. + * + * This struct describes a SAM event registry via the minimal collection of + * SAM IDs specifying the requests to use for enabling and disabling an event. + * The individual event to be enabled/disabled itself is specified via &struct + * ssam_event_id. + */ +struct ssam_event_registry { + u8 target_category; + u8 target_id; + u8 cid_enable; + u8 cid_disable; +}; + +/** + * struct ssam_event_id - Unique event ID used for enabling events. + * @target_category: Target category of the event source. + * @instance: Instance ID of the event source. + * + * This struct specifies the event to be enabled/disabled via an externally + * provided registry. It does not specify the registry to be used itself, this + * is done via &struct ssam_event_registry. + */ +struct ssam_event_id { + u8 target_category; + u8 instance; +}; + +/** + * enum ssam_event_mask - Flags specifying how events are matched to notifiers. + * + * @SSAM_EVENT_MASK_NONE: + * Run the callback for any event with matching target category. Do not + * do any additional filtering. + * + * @SSAM_EVENT_MASK_TARGET: + * In addition to filtering by target category, only execute the notifier + * callback for events with a target ID matching to the one of the + * registry used for enabling/disabling the event. + * + * @SSAM_EVENT_MASK_INSTANCE: + * In addition to filtering by target category, only execute the notifier + * callback for events with an instance ID matching to the instance ID + * used when enabling the event. + * + * @SSAM_EVENT_MASK_STRICT: + * Do all the filtering above. + */ +enum ssam_event_mask { + SSAM_EVENT_MASK_TARGET = BIT(0), + SSAM_EVENT_MASK_INSTANCE = BIT(1), + + SSAM_EVENT_MASK_NONE = 0, + SSAM_EVENT_MASK_STRICT = + SSAM_EVENT_MASK_TARGET + | SSAM_EVENT_MASK_INSTANCE, +}; + +/** + * SSAM_EVENT_REGISTRY() - Define a new event registry. + * @tc: Target category for the event registry requests. + * @tid: Target ID for the event registry requests. + * @cid_en: Command ID for the event-enable request. + * @cid_dis: Command ID for the event-disable request. + * + * Return: Returns the &struct ssam_event_registry specified by the given + * parameters. + */ +#define SSAM_EVENT_REGISTRY(tc, tid, cid_en, cid_dis) \ + ((struct ssam_event_registry) { \ + .target_category = (tc), \ + .target_id = (tid), \ + .cid_enable = (cid_en), \ + .cid_disable = (cid_dis), \ + }) + +#define SSAM_EVENT_REGISTRY_SAM \ + SSAM_EVENT_REGISTRY(SSAM_SSH_TC_SAM, 0x01, 0x0b, 0x0c) + +#define SSAM_EVENT_REGISTRY_KIP \ + SSAM_EVENT_REGISTRY(SSAM_SSH_TC_KIP, 0x02, 0x27, 0x28) + +#define SSAM_EVENT_REGISTRY_REG \ + SSAM_EVENT_REGISTRY(SSAM_SSH_TC_REG, 0x02, 0x01, 0x02) + +/** + * struct ssam_event_notifier - Notifier block for SSAM events. + * @base: The base notifier block with callback function and priority. + * @event: The event for which this block will receive notifications. + * @event.reg: Registry via which the event will be enabled/disabled. + * @event.id: ID specifying the event. + * @event.mask: Flags determining how events are matched to the notifier. + * @event.flags: Flags used for enabling the event. + */ +struct ssam_event_notifier { + struct ssam_notifier_block base; + + struct { + struct ssam_event_registry reg; + struct ssam_event_id id; + enum ssam_event_mask mask; + u8 flags; + } event; +}; + +int ssam_notifier_register(struct ssam_controller *ctrl, + struct ssam_event_notifier *n); + +int ssam_notifier_unregister(struct ssam_controller *ctrl, + struct ssam_event_notifier *n); + +#endif /* _LINUX_SURFACE_AGGREGATOR_CONTROLLER_H */ diff --git a/include/linux/surface_aggregator/serial_hub.h b/include/linux/surface_aggregator/serial_hub.h new file mode 100644 index 000000000000..64276fbfa1d5 --- /dev/null +++ b/include/linux/surface_aggregator/serial_hub.h @@ -0,0 +1,672 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * Surface Serial Hub (SSH) protocol and communication interface. + * + * Lower-level communication layers and SSH protocol definitions for the + * Surface System Aggregator Module (SSAM). Provides the interface for basic + * packet- and request-based communication with the SSAM EC via SSH. + * + * Copyright (C) 2019-2020 Maximilian Luz <luzmaximilian@gmail.com> + */ + +#ifndef _LINUX_SURFACE_AGGREGATOR_SERIAL_HUB_H +#define _LINUX_SURFACE_AGGREGATOR_SERIAL_HUB_H + +#include <linux/crc-ccitt.h> +#include <linux/kref.h> +#include <linux/ktime.h> +#include <linux/list.h> +#include <linux/types.h> + + +/* -- Data structures for SAM-over-SSH communication. ----------------------- */ + +/** + * enum ssh_frame_type - Frame types for SSH frames. + * + * @SSH_FRAME_TYPE_DATA_SEQ: + * Indicates a data frame, followed by a payload with the length specified + * in the ``struct ssh_frame.len`` field. This frame is sequenced, meaning + * that an ACK is required. + * + * @SSH_FRAME_TYPE_DATA_NSQ: + * Same as %SSH_FRAME_TYPE_DATA_SEQ, but unsequenced, meaning that the + * message does not have to be ACKed. + * + * @SSH_FRAME_TYPE_ACK: + * Indicates an ACK message. + * + * @SSH_FRAME_TYPE_NAK: + * Indicates an error response for previously sent frame. In general, this + * means that the frame and/or payload is malformed, e.g. a CRC is wrong. + * For command-type payloads, this can also mean that the command is + * invalid. + */ +enum ssh_frame_type { + SSH_FRAME_TYPE_DATA_SEQ = 0x80, + SSH_FRAME_TYPE_DATA_NSQ = 0x00, + SSH_FRAME_TYPE_ACK = 0x40, + SSH_FRAME_TYPE_NAK = 0x04, +}; + +/** + * struct ssh_frame - SSH communication frame. + * @type: The type of the frame. See &enum ssh_frame_type. + * @len: The length of the frame payload directly following the CRC for this + * frame. Does not include the final CRC for that payload. + * @seq: The sequence number for this message/exchange. + */ +struct ssh_frame { + u8 type; + __le16 len; + u8 seq; +} __packed; + +static_assert(sizeof(struct ssh_frame) == 4); + +/* + * SSH_FRAME_MAX_PAYLOAD_SIZE - Maximum SSH frame payload length in bytes. + * + * This is the physical maximum length of the protocol. Implementations may + * set a more constrained limit. + */ +#define SSH_FRAME_MAX_PAYLOAD_SIZE U16_MAX + +/** + * enum ssh_payload_type - Type indicator for the SSH payload. + * @SSH_PLD_TYPE_CMD: The payload is a command structure with optional command + * payload. + */ +enum ssh_payload_type { + SSH_PLD_TYPE_CMD = 0x80, +}; + +/** + * struct ssh_command - Payload of a command-type frame. + * @type: The type of the payload. See &enum ssh_payload_type. Should be + * SSH_PLD_TYPE_CMD for this struct. + * @tc: Command target category. + * @tid_out: Output target ID. Should be zero if this an incoming (EC to host) + * message. + * @tid_in: Input target ID. Should be zero if this is an outgoing (host to + * EC) message. + * @iid: Instance ID. + * @rqid: Request ID. Used to match requests with responses and differentiate + * between responses and events. + * @cid: Command ID. + */ +struct ssh_command { + u8 type; + u8 tc; + u8 tid_out; + u8 tid_in; + u8 iid; + __le16 rqid; + u8 cid; +} __packed; + +static_assert(sizeof(struct ssh_command) == 8); + +/* + * SSH_COMMAND_MAX_PAYLOAD_SIZE - Maximum SSH command payload length in bytes. + * + * This is the physical maximum length of the protocol. Implementations may + * set a more constrained limit. + */ +#define SSH_COMMAND_MAX_PAYLOAD_SIZE \ + (SSH_FRAME_MAX_PAYLOAD_SIZE - sizeof(struct ssh_command)) + +/* + * SSH_MSG_LEN_BASE - Base-length of a SSH message. + * + * This is the minimum number of bytes required to form a message. The actual + * message length is SSH_MSG_LEN_BASE plus the length of the frame payload. + */ +#define SSH_MSG_LEN_BASE (sizeof(struct ssh_frame) + 3ull * sizeof(u16)) + +/* + * SSH_MSG_LEN_CTRL - Length of a SSH control message. + * + * This is the length of a SSH control message, which is equal to a SSH + * message without any payload. + */ +#define SSH_MSG_LEN_CTRL SSH_MSG_LEN_BASE + +/** + * SSH_MESSAGE_LENGTH() - Compute length of SSH message. + * @payload_size: Length of the payload inside the SSH frame. + * + * Return: Returns the length of a SSH message with payload of specified size. + */ +#define SSH_MESSAGE_LENGTH(payload_size) (SSH_MSG_LEN_BASE + (payload_size)) + +/** + * SSH_COMMAND_MESSAGE_LENGTH() - Compute length of SSH command message. + * @payload_size: Length of the command payload. + * + * Return: Returns the length of a SSH command message with command payload of + * specified size. + */ +#define SSH_COMMAND_MESSAGE_LENGTH(payload_size) \ + SSH_MESSAGE_LENGTH(sizeof(struct ssh_command) + (payload_size)) + +/** + * SSH_MSGOFFSET_FRAME() - Compute offset in SSH message to specified field in + * frame. + * @field: The field for which the offset should be computed. + * + * Return: Returns the offset of the specified &struct ssh_frame field in the + * raw SSH message data as. Takes SYN bytes (u16) preceding the frame into + * account. + */ +#define SSH_MSGOFFSET_FRAME(field) \ + (sizeof(u16) + offsetof(struct ssh_frame, field)) + +/** + * SSH_MSGOFFSET_COMMAND() - Compute offset in SSH message to specified field + * in command. + * @field: The field for which the offset should be computed. + * + * Return: Returns the offset of the specified &struct ssh_command field in + * the raw SSH message data. Takes SYN bytes (u16) preceding the frame and the + * frame CRC (u16) between frame and command into account. + */ +#define SSH_MSGOFFSET_COMMAND(field) \ + (2ull * sizeof(u16) + sizeof(struct ssh_frame) \ + + offsetof(struct ssh_command, field)) + +/* + * SSH_MSG_SYN - SSH message synchronization (SYN) bytes as u16. + */ +#define SSH_MSG_SYN ((u16)0x55aa) + +/** + * ssh_crc() - Compute CRC for SSH messages. + * @buf: The pointer pointing to the data for which the CRC should be computed. + * @len: The length of the data for which the CRC should be computed. + * + * Return: Returns the CRC computed on the provided data, as used for SSH + * messages. + */ +static inline u16 ssh_crc(const u8 *buf, size_t len) +{ + return crc_ccitt_false(0xffff, buf, len); +} + +/* + * SSH_NUM_EVENTS - The number of reserved event IDs. + * + * The number of reserved event IDs, used for registering an SSH event + * handler. Valid event IDs are numbers below or equal to this value, with + * exception of zero, which is not an event ID. Thus, this is also the + * absolute maximum number of event handlers that can be registered. + */ +#define SSH_NUM_EVENTS 34 + +/* + * SSH_NUM_TARGETS - The number of communication targets used in the protocol. + */ +#define SSH_NUM_TARGETS 2 + +/** + * ssh_rqid_next_valid() - Return the next valid request ID. + * @rqid: The current request ID. + * + * Return: Returns the next valid request ID, following the current request ID + * provided to this function. This function skips any request IDs reserved for + * events. + */ +static inline u16 ssh_rqid_next_valid(u16 rqid) +{ + return rqid > 0 ? rqid + 1u : rqid + SSH_NUM_EVENTS + 1u; +} + +/** + * ssh_rqid_to_event() - Convert request ID to its corresponding event ID. + * @rqid: The request ID to convert. + */ +static inline u16 ssh_rqid_to_event(u16 rqid) +{ + return rqid - 1u; +} + +/** + * ssh_rqid_is_event() - Check if given request ID is a valid event ID. + * @rqid: The request ID to check. + */ +static inline bool ssh_rqid_is_event(u16 rqid) +{ + return ssh_rqid_to_event(rqid) < SSH_NUM_EVENTS; +} + +/** + * ssh_tc_to_rqid() - Convert target category to its corresponding request ID. + * @tc: The target category to convert. + */ +static inline u16 ssh_tc_to_rqid(u8 tc) +{ + return tc; +} + +/** + * ssh_tid_to_index() - Convert target ID to its corresponding target index. + * @tid: The target ID to convert. + */ +static inline u8 ssh_tid_to_index(u8 tid) +{ + return tid - 1u; +} + +/** + * ssh_tid_is_valid() - Check if target ID is valid/supported. + * @tid: The target ID to check. + */ +static inline bool ssh_tid_is_valid(u8 tid) +{ + return ssh_tid_to_index(tid) < SSH_NUM_TARGETS; +} + +/** + * struct ssam_span - Reference to a buffer region. + * @ptr: Pointer to the buffer region. + * @len: Length of the buffer region. + * + * A reference to a (non-owned) buffer segment, consisting of pointer and + * length. Use of this struct indicates non-owned data, i.e. data of which the + * life-time is managed (i.e. it is allocated/freed) via another pointer. + */ +struct ssam_span { + u8 *ptr; + size_t len; +}; + +/* + * Known SSH/EC target categories. + * + * List of currently known target category values; "Known" as in we know they + * exist and are valid on at least some device/model. Detailed functionality + * or the full category name is only known for some of these categories and + * is detailed in the respective comment below. + * + * These values and abbreviations have been extracted from strings inside the + * Windows driver. + */ +enum ssam_ssh_tc { + /* Category 0x00 is invalid for EC use. */ + SSAM_SSH_TC_SAM = 0x01, /* Generic system functionality, real-time clock. */ + SSAM_SSH_TC_BAT = 0x02, /* Battery/power subsystem. */ + SSAM_SSH_TC_TMP = 0x03, /* Thermal subsystem. */ + SSAM_SSH_TC_PMC = 0x04, + SSAM_SSH_TC_FAN = 0x05, + SSAM_SSH_TC_PoM = 0x06, + SSAM_SSH_TC_DBG = 0x07, + SSAM_SSH_TC_KBD = 0x08, /* Legacy keyboard (Laptop 1/2). */ + SSAM_SSH_TC_FWU = 0x09, + SSAM_SSH_TC_UNI = 0x0a, + SSAM_SSH_TC_LPC = 0x0b, + SSAM_SSH_TC_TCL = 0x0c, + SSAM_SSH_TC_SFL = 0x0d, + SSAM_SSH_TC_KIP = 0x0e, + SSAM_SSH_TC_EXT = 0x0f, + SSAM_SSH_TC_BLD = 0x10, + SSAM_SSH_TC_BAS = 0x11, /* Detachment system (Surface Book 2/3). */ + SSAM_SSH_TC_SEN = 0x12, + SSAM_SSH_TC_SRQ = 0x13, + SSAM_SSH_TC_MCU = 0x14, + SSAM_SSH_TC_HID = 0x15, /* Generic HID input subsystem. */ + SSAM_SSH_TC_TCH = 0x16, + SSAM_SSH_TC_BKL = 0x17, + SSAM_SSH_TC_TAM = 0x18, + SSAM_SSH_TC_ACC = 0x19, + SSAM_SSH_TC_UFI = 0x1a, + SSAM_SSH_TC_USC = 0x1b, + SSAM_SSH_TC_PEN = 0x1c, + SSAM_SSH_TC_VID = 0x1d, + SSAM_SSH_TC_AUD = 0x1e, + SSAM_SSH_TC_SMC = 0x1f, + SSAM_SSH_TC_KPD = 0x20, + SSAM_SSH_TC_REG = 0x21, /* Extended event registry. */ +}; + + +/* -- Packet transport layer (ptl). ----------------------------------------- */ + +/** + * enum ssh_packet_base_priority - Base priorities for &struct ssh_packet. + * @SSH_PACKET_PRIORITY_FLUSH: Base priority for flush packets. + * @SSH_PACKET_PRIORITY_DATA: Base priority for normal data packets. + * @SSH_PACKET_PRIORITY_NAK: Base priority for NAK packets. + * @SSH_PACKET_PRIORITY_ACK: Base priority for ACK packets. + */ +enum ssh_packet_base_priority { + SSH_PACKET_PRIORITY_FLUSH = 0, /* same as DATA to sequence flush */ + SSH_PACKET_PRIORITY_DATA = 0, + SSH_PACKET_PRIORITY_NAK = 1, + SSH_PACKET_PRIORITY_ACK = 2, +}; + +/* + * Same as SSH_PACKET_PRIORITY() below, only with actual values. + */ +#define __SSH_PACKET_PRIORITY(base, try) \ + (((base) << 4) | ((try) & 0x0f)) + +/** + * SSH_PACKET_PRIORITY() - Compute packet priority from base priority and + * number of tries. + * @base: The base priority as suffix of &enum ssh_packet_base_priority, e.g. + * ``FLUSH``, ``DATA``, ``ACK``, or ``NAK``. + * @try: The number of tries (must be less than 16). + * + * Compute the combined packet priority. The combined priority is dominated by + * the base priority, whereas the number of (re-)tries decides the precedence + * of packets with the same base priority, giving higher priority to packets + * that already have more tries. + * + * Return: Returns the computed priority as value fitting inside a &u8. A + * higher number means a higher priority. + */ +#define SSH_PACKET_PRIORITY(base, try) \ + __SSH_PACKET_PRIORITY(SSH_PACKET_PRIORITY_##base, (try)) + +/** + * ssh_packet_priority_get_try() - Get number of tries from packet priority. + * @priority: The packet priority. + * + * Return: Returns the number of tries encoded in the specified packet + * priority. + */ +static inline u8 ssh_packet_priority_get_try(u8 priority) +{ + return priority & 0x0f; +} + +/** + * ssh_packet_priority_get_base - Get base priority from packet priority. + * @priority: The packet priority. + * + * Return: Returns the base priority encoded in the given packet priority. + */ +static inline u8 ssh_packet_priority_get_base(u8 priority) +{ + return (priority & 0xf0) >> 4; +} + +enum ssh_packet_flags { + /* state flags */ + SSH_PACKET_SF_LOCKED_BIT, + SSH_PACKET_SF_QUEUED_BIT, + SSH_PACKET_SF_PENDING_BIT, + SSH_PACKET_SF_TRANSMITTING_BIT, + SSH_PACKET_SF_TRANSMITTED_BIT, + SSH_PACKET_SF_ACKED_BIT, + SSH_PACKET_SF_CANCELED_BIT, + SSH_PACKET_SF_COMPLETED_BIT, + + /* type flags */ + SSH_PACKET_TY_FLUSH_BIT, + SSH_PACKET_TY_SEQUENCED_BIT, + SSH_PACKET_TY_BLOCKING_BIT, + + /* mask for state flags */ + SSH_PACKET_FLAGS_SF_MASK = + BIT(SSH_PACKET_SF_LOCKED_BIT) + | BIT(SSH_PACKET_SF_QUEUED_BIT) + | BIT(SSH_PACKET_SF_PENDING_BIT) + | BIT(SSH_PACKET_SF_TRANSMITTING_BIT) + | BIT(SSH_PACKET_SF_TRANSMITTED_BIT) + | BIT(SSH_PACKET_SF_ACKED_BIT) + | BIT(SSH_PACKET_SF_CANCELED_BIT) + | BIT(SSH_PACKET_SF_COMPLETED_BIT), + + /* mask for type flags */ + SSH_PACKET_FLAGS_TY_MASK = + BIT(SSH_PACKET_TY_FLUSH_BIT) + | BIT(SSH_PACKET_TY_SEQUENCED_BIT) + | BIT(SSH_PACKET_TY_BLOCKING_BIT), +}; + +struct ssh_ptl; +struct ssh_packet; + +/** + * struct ssh_packet_ops - Callback operations for a SSH packet. + * @release: Function called when the packet reference count reaches zero. + * This callback must be relied upon to ensure that the packet has + * left the transport system(s). + * @complete: Function called when the packet is completed, either with + * success or failure. In case of failure, the reason for the + * failure is indicated by the value of the provided status code + * argument. This value will be zero in case of success. Note that + * a call to this callback does not guarantee that the packet is + * not in use by the transport system any more. + */ +struct ssh_packet_ops { + void (*release)(struct ssh_packet *p); + void (*complete)(struct ssh_packet *p, int status); +}; + +/** + * struct ssh_packet - SSH transport packet. + * @ptl: Pointer to the packet transport layer. May be %NULL if the packet + * (or enclosing request) has not been submitted yet. + * @refcnt: Reference count of the packet. + * @priority: Priority of the packet. Must be computed via + * SSH_PACKET_PRIORITY(). Must only be accessed while holding the + * queue lock after first submission. + * @data: Raw message data. + * @data.len: Length of the raw message data. + * @data.ptr: Pointer to the raw message data buffer. + * @state: State and type flags describing current packet state (dynamic) + * and type (static). See &enum ssh_packet_flags for possible + * options. + * @timestamp: Timestamp specifying when the latest transmission of a + * currently pending packet has been started. May be %KTIME_MAX + * before or in-between transmission attempts. Used for the packet + * timeout implementation. Must only be accessed while holding the + * pending lock after first submission. + * @queue_node: The list node for the packet queue. + * @pending_node: The list node for the set of pending packets. + * @ops: Packet operations. + */ +struct ssh_packet { + struct ssh_ptl *ptl; + struct kref refcnt; + + u8 priority; + + struct { + size_t len; + u8 *ptr; + } data; + + unsigned long state; + ktime_t timestamp; + + struct list_head queue_node; + struct list_head pending_node; + + const struct ssh_packet_ops *ops; +}; + +struct ssh_packet *ssh_packet_get(struct ssh_packet *p); +void ssh_packet_put(struct ssh_packet *p); + +/** + * ssh_packet_set_data() - Set raw message data of packet. + * @p: The packet for which the message data should be set. + * @ptr: Pointer to the memory holding the message data. + * @len: Length of the message data. + * + * Sets the raw message data buffer of the packet to the provided memory. The + * memory is not copied. Instead, the caller is responsible for management + * (i.e. allocation and deallocation) of the memory. The caller must ensure + * that the provided memory is valid and contains a valid SSH message, + * starting from the time of submission of the packet until the ``release`` + * callback has been called. During this time, the memory may not be altered + * in any way. + */ +static inline void ssh_packet_set_data(struct ssh_packet *p, u8 *ptr, size_t len) +{ + p->data.ptr = ptr; + p->data.len = len; +} + + +/* -- Request transport layer (rtl). ---------------------------------------- */ + +enum ssh_request_flags { + /* state flags */ + SSH_REQUEST_SF_LOCKED_BIT, + SSH_REQUEST_SF_QUEUED_BIT, + SSH_REQUEST_SF_PENDING_BIT, + SSH_REQUEST_SF_TRANSMITTING_BIT, + SSH_REQUEST_SF_TRANSMITTED_BIT, + SSH_REQUEST_SF_RSPRCVD_BIT, + SSH_REQUEST_SF_CANCELED_BIT, + SSH_REQUEST_SF_COMPLETED_BIT, + + /* type flags */ + SSH_REQUEST_TY_FLUSH_BIT, + SSH_REQUEST_TY_HAS_RESPONSE_BIT, + + /* mask for state flags */ + SSH_REQUEST_FLAGS_SF_MASK = + BIT(SSH_REQUEST_SF_LOCKED_BIT) + | BIT(SSH_REQUEST_SF_QUEUED_BIT) + | BIT(SSH_REQUEST_SF_PENDING_BIT) + | BIT(SSH_REQUEST_SF_TRANSMITTING_BIT) + | BIT(SSH_REQUEST_SF_TRANSMITTED_BIT) + | BIT(SSH_REQUEST_SF_RSPRCVD_BIT) + | BIT(SSH_REQUEST_SF_CANCELED_BIT) + | BIT(SSH_REQUEST_SF_COMPLETED_BIT), + + /* mask for type flags */ + SSH_REQUEST_FLAGS_TY_MASK = + BIT(SSH_REQUEST_TY_FLUSH_BIT) + | BIT(SSH_REQUEST_TY_HAS_RESPONSE_BIT), +}; + +struct ssh_rtl; +struct ssh_request; + +/** + * struct ssh_request_ops - Callback operations for a SSH request. + * @release: Function called when the request's reference count reaches zero. + * This callback must be relied upon to ensure that the request has + * left the transport systems (both, packet an request systems). + * @complete: Function called when the request is completed, either with + * success or failure. The command data for the request response + * is provided via the &struct ssh_command parameter (``cmd``), + * the command payload of the request response via the &struct + * ssh_span parameter (``data``). + * + * If the request does not have any response or has not been + * completed with success, both ``cmd`` and ``data`` parameters will + * be NULL. If the request response does not have any command + * payload, the ``data`` span will be an empty (zero-length) span. + * + * In case of failure, the reason for the failure is indicated by + * the value of the provided status code argument (``status``). This + * value will be zero in case of success and a regular errno + * otherwise. + * + * Note that a call to this callback does not guarantee that the + * request is not in use by the transport systems any more. + */ +struct ssh_request_ops { + void (*release)(struct ssh_request *rqst); + void (*complete)(struct ssh_request *rqst, + const struct ssh_command *cmd, + const struct ssam_span *data, int status); +}; + +/** + * struct ssh_request - SSH transport request. + * @packet: The underlying SSH transport packet. + * @node: List node for the request queue and pending set. + * @state: State and type flags describing current request state (dynamic) + * and type (static). See &enum ssh_request_flags for possible + * options. + * @timestamp: Timestamp specifying when we start waiting on the response of + * the request. This is set once the underlying packet has been + * completed and may be %KTIME_MAX before that, or when the request + * does not expect a response. Used for the request timeout + * implementation. + * @ops: Request Operations. + */ +struct ssh_request { + struct ssh_packet packet; + struct list_head node; + + unsigned long state; + ktime_t timestamp; + + const struct ssh_request_ops *ops; +}; + +/** + * to_ssh_request() - Cast a SSH packet to its enclosing SSH request. + * @p: The packet to cast. + * + * Casts the given &struct ssh_packet to its enclosing &struct ssh_request. + * The caller is responsible for making sure that the packet is actually + * wrapped in a &struct ssh_request. + * + * Return: Returns the &struct ssh_request wrapping the provided packet. + */ +static inline struct ssh_request *to_ssh_request(struct ssh_packet *p) +{ + return container_of(p, struct ssh_request, packet); +} + +/** + * ssh_request_get() - Increment reference count of request. + * @r: The request to increment the reference count of. + * + * Increments the reference count of the given request by incrementing the + * reference count of the underlying &struct ssh_packet, enclosed in it. + * + * See also ssh_request_put(), ssh_packet_get(). + * + * Return: Returns the request provided as input. + */ +static inline struct ssh_request *ssh_request_get(struct ssh_request *r) +{ + return r ? to_ssh_request(ssh_packet_get(&r->packet)) : NULL; +} + +/** + * ssh_request_put() - Decrement reference count of request. + * @r: The request to decrement the reference count of. + * + * Decrements the reference count of the given request by decrementing the + * reference count of the underlying &struct ssh_packet, enclosed in it. If + * the reference count reaches zero, the ``release`` callback specified in the + * request's &struct ssh_request_ops, i.e. ``r->ops->release``, will be + * called. + * + * See also ssh_request_get(), ssh_packet_put(). + */ +static inline void ssh_request_put(struct ssh_request *r) +{ + if (r) + ssh_packet_put(&r->packet); +} + +/** + * ssh_request_set_data() - Set raw message data of request. + * @r: The request for which the message data should be set. + * @ptr: Pointer to the memory holding the message data. + * @len: Length of the message data. + * + * Sets the raw message data buffer of the underlying packet to the specified + * buffer. Does not copy the actual message data, just sets the buffer pointer + * and length. Refer to ssh_packet_set_data() for more details. + */ +static inline void ssh_request_set_data(struct ssh_request *r, u8 *ptr, size_t len) +{ + ssh_packet_set_data(&r->packet, ptr, len); +} + +#endif /* _LINUX_SURFACE_AGGREGATOR_SERIAL_HUB_H */ |