diff options
Diffstat (limited to 'drivers/firmware')
| -rw-r--r-- | drivers/firmware/arm_scmi/Kconfig | 11 | ||||
| -rw-r--r-- | drivers/firmware/arm_scmi/Makefile | 1 | ||||
| -rw-r--r-- | drivers/firmware/arm_scmi/common.h | 3 | ||||
| -rw-r--r-- | drivers/firmware/arm_scmi/driver.c | 3 | ||||
| -rw-r--r-- | drivers/firmware/arm_scmi/virtio.c | 491 |
5 files changed, 509 insertions, 0 deletions
diff --git a/drivers/firmware/arm_scmi/Kconfig b/drivers/firmware/arm_scmi/Kconfig index 24fed705b02c..7f4d2435503b 100644 --- a/drivers/firmware/arm_scmi/Kconfig +++ b/drivers/firmware/arm_scmi/Kconfig @@ -66,6 +66,17 @@ config ARM_SCMI_TRANSPORT_SMC If you want the ARM SCMI PROTOCOL stack to include support for a transport based on SMC, answer Y. +config ARM_SCMI_TRANSPORT_VIRTIO + bool "SCMI transport based on VirtIO" + depends on VIRTIO + select ARM_SCMI_HAVE_TRANSPORT + select ARM_SCMI_HAVE_MSG + help + This enables the virtio based transport for SCMI. + + If you want the ARM SCMI PROTOCOL stack to include support for a + transport based on VirtIO, answer Y. + endif #ARM_SCMI_PROTOCOL config ARM_SCMI_POWER_DOMAIN diff --git a/drivers/firmware/arm_scmi/Makefile b/drivers/firmware/arm_scmi/Makefile index aaad9f6589aa..1dcf123d64ab 100644 --- a/drivers/firmware/arm_scmi/Makefile +++ b/drivers/firmware/arm_scmi/Makefile @@ -5,6 +5,7 @@ scmi-transport-$(CONFIG_ARM_SCMI_HAVE_SHMEM) = shmem.o scmi-transport-$(CONFIG_ARM_SCMI_TRANSPORT_MAILBOX) += mailbox.o scmi-transport-$(CONFIG_ARM_SCMI_TRANSPORT_SMC) += smc.o scmi-transport-$(CONFIG_ARM_SCMI_HAVE_MSG) += msg.o +scmi-transport-$(CONFIG_ARM_SCMI_TRANSPORT_VIRTIO) += virtio.o scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o system.o voltage.o scmi-module-objs := $(scmi-bus-y) $(scmi-driver-y) $(scmi-protocols-y) \ $(scmi-transport-y) diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h index 7864c21269b0..dea1bfbe1052 100644 --- a/drivers/firmware/arm_scmi/common.h +++ b/drivers/firmware/arm_scmi/common.h @@ -418,6 +418,9 @@ extern const struct scmi_desc scmi_mailbox_desc; #ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC extern const struct scmi_desc scmi_smc_desc; #endif +#ifdef CONFIG_ARM_SCMI_TRANSPORT_VIRTIO +extern const struct scmi_desc scmi_virtio_desc; +#endif void scmi_rx_callback(struct scmi_chan_info *cinfo, u32 msg_hdr, void *priv); void scmi_free_channel(struct scmi_chan_info *cinfo, struct idr *idr, int id); diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c index aaca01a4d752..00fcacd06562 100644 --- a/drivers/firmware/arm_scmi/driver.c +++ b/drivers/firmware/arm_scmi/driver.c @@ -1984,6 +1984,9 @@ static const struct of_device_id scmi_of_match[] = { #ifdef CONFIG_ARM_SCMI_TRANSPORT_SMC { .compatible = "arm,scmi-smc", .data = &scmi_smc_desc}, #endif +#ifdef CONFIG_ARM_SCMI_TRANSPORT_VIRTIO + { .compatible = "arm,scmi-virtio", .data = &scmi_virtio_desc}, +#endif { /* Sentinel */ }, }; diff --git a/drivers/firmware/arm_scmi/virtio.c b/drivers/firmware/arm_scmi/virtio.c new file mode 100644 index 000000000000..3dacf794b177 --- /dev/null +++ b/drivers/firmware/arm_scmi/virtio.c @@ -0,0 +1,491 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Virtio Transport driver for Arm System Control and Management Interface + * (SCMI). + * + * Copyright (C) 2020-2021 OpenSynergy. + * Copyright (C) 2021 ARM Ltd. + */ + +/** + * DOC: Theory of Operation + * + * The scmi-virtio transport implements a driver for the virtio SCMI device. + * + * There is one Tx channel (virtio cmdq, A2P channel) and at most one Rx + * channel (virtio eventq, P2A channel). Each channel is implemented through a + * virtqueue. Access to each virtqueue is protected by spinlocks. + */ + +#include <linux/errno.h> +#include <linux/slab.h> +#include <linux/virtio.h> +#include <linux/virtio_config.h> + +#include <uapi/linux/virtio_ids.h> +#include <uapi/linux/virtio_scmi.h> + +#include "common.h" + +#define VIRTIO_SCMI_MAX_MSG_SIZE 128 /* Value may be increased. */ +#define VIRTIO_SCMI_MAX_PDU_SIZE \ + (VIRTIO_SCMI_MAX_MSG_SIZE + SCMI_MSG_MAX_PROT_OVERHEAD) +#define DESCRIPTORS_PER_TX_MSG 2 + +/** + * struct scmi_vio_channel - Transport channel information + * + * @vqueue: Associated virtqueue + * @cinfo: SCMI Tx or Rx channel + * @free_list: List of unused scmi_vio_msg, maintained for Tx channels only + * @is_rx: Whether channel is an Rx channel + * @ready: Whether transport user is ready to hear about channel + * @max_msg: Maximum number of pending messages for this channel. + * @lock: Protects access to all members except ready. + * @ready_lock: Protects access to ready. If required, it must be taken before + * lock. + */ +struct scmi_vio_channel { + struct virtqueue *vqueue; + struct scmi_chan_info *cinfo; + struct list_head free_list; + bool is_rx; + bool ready; + unsigned int max_msg; + /* lock to protect access to all members except ready. */ + spinlock_t lock; + /* lock to rotects access to ready flag. */ + spinlock_t ready_lock; +}; + +/** + * struct scmi_vio_msg - Transport PDU information + * + * @request: SDU used for commands + * @input: SDU used for (delayed) responses and notifications + * @list: List which scmi_vio_msg may be part of + * @rx_len: Input SDU size in bytes, once input has been received + */ +struct scmi_vio_msg { + struct scmi_msg_payld *request; + struct scmi_msg_payld *input; + struct list_head list; + unsigned int rx_len; +}; + +/* Only one SCMI VirtIO device can possibly exist */ +static struct virtio_device *scmi_vdev; + +static bool scmi_vio_have_vq_rx(struct virtio_device *vdev) +{ + return virtio_has_feature(vdev, VIRTIO_SCMI_F_P2A_CHANNELS); +} + +static int scmi_vio_feed_vq_rx(struct scmi_vio_channel *vioch, + struct scmi_vio_msg *msg) +{ + struct scatterlist sg_in; + int rc; + unsigned long flags; + + sg_init_one(&sg_in, msg->input, VIRTIO_SCMI_MAX_PDU_SIZE); + + spin_lock_irqsave(&vioch->lock, flags); + + rc = virtqueue_add_inbuf(vioch->vqueue, &sg_in, 1, msg, GFP_ATOMIC); + if (rc) + dev_err_once(vioch->cinfo->dev, + "failed to add to virtqueue (%d)\n", rc); + else + virtqueue_kick(vioch->vqueue); + + spin_unlock_irqrestore(&vioch->lock, flags); + + return rc; +} + +static void scmi_finalize_message(struct scmi_vio_channel *vioch, + struct scmi_vio_msg *msg) +{ + if (vioch->is_rx) { + scmi_vio_feed_vq_rx(vioch, msg); + } else { + unsigned long flags; + + spin_lock_irqsave(&vioch->lock, flags); + list_add(&msg->list, &vioch->free_list); + spin_unlock_irqrestore(&vioch->lock, flags); + } +} + +static void scmi_vio_complete_cb(struct virtqueue *vqueue) +{ + unsigned long ready_flags; + unsigned long flags; + unsigned int length; + struct scmi_vio_channel *vioch; + struct scmi_vio_msg *msg; + bool cb_enabled = true; + + if (WARN_ON_ONCE(!vqueue->vdev->priv)) + return; + vioch = &((struct scmi_vio_channel *)vqueue->vdev->priv)[vqueue->index]; + + for (;;) { + spin_lock_irqsave(&vioch->ready_lock, ready_flags); + + if (!vioch->ready) { + if (!cb_enabled) + (void)virtqueue_enable_cb(vqueue); + goto unlock_ready_out; + } + + spin_lock_irqsave(&vioch->lock, flags); + if (cb_enabled) { + virtqueue_disable_cb(vqueue); + cb_enabled = false; + } + msg = virtqueue_get_buf(vqueue, &length); + if (!msg) { + if (virtqueue_enable_cb(vqueue)) + goto unlock_out; + cb_enabled = true; + } + spin_unlock_irqrestore(&vioch->lock, flags); + + if (msg) { + msg->rx_len = length; + scmi_rx_callback(vioch->cinfo, + msg_read_header(msg->input), msg); + + scmi_finalize_message(vioch, msg); + } + + spin_unlock_irqrestore(&vioch->ready_lock, ready_flags); + } + +unlock_out: + spin_unlock_irqrestore(&vioch->lock, flags); +unlock_ready_out: + spin_unlock_irqrestore(&vioch->ready_lock, ready_flags); +} + +static const char *const scmi_vio_vqueue_names[] = { "tx", "rx" }; + +static vq_callback_t *scmi_vio_complete_callbacks[] = { + scmi_vio_complete_cb, + scmi_vio_complete_cb +}; + +static unsigned int virtio_get_max_msg(struct scmi_chan_info *base_cinfo) +{ + struct scmi_vio_channel *vioch = base_cinfo->transport_info; + + return vioch->max_msg; +} + +static int virtio_link_supplier(struct device *dev) +{ + if (!scmi_vdev) { + dev_notice_once(dev, + "Deferring probe after not finding a bound scmi-virtio device\n"); + return -EPROBE_DEFER; + } + + if (!device_link_add(dev, &scmi_vdev->dev, + DL_FLAG_AUTOREMOVE_CONSUMER)) { + dev_err(dev, "Adding link to supplier virtio device failed\n"); + return -ECANCELED; + } + + return 0; +} + +static bool virtio_chan_available(struct device *dev, int idx) +{ + struct scmi_vio_channel *channels, *vioch = NULL; + + if (WARN_ON_ONCE(!scmi_vdev)) + return false; + + channels = (struct scmi_vio_channel *)scmi_vdev->priv; + + switch (idx) { + case VIRTIO_SCMI_VQ_TX: + vioch = &channels[VIRTIO_SCMI_VQ_TX]; + break; + case VIRTIO_SCMI_VQ_RX: + if (scmi_vio_have_vq_rx(scmi_vdev)) + vioch = &channels[VIRTIO_SCMI_VQ_RX]; + break; + default: + return false; + } + + return vioch && !vioch->cinfo ? true : false; +} + +static int virtio_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, + bool tx) +{ + unsigned long flags; + struct scmi_vio_channel *vioch; + int index = tx ? VIRTIO_SCMI_VQ_TX : VIRTIO_SCMI_VQ_RX; + int i; + + if (!scmi_vdev) + return -EPROBE_DEFER; + + vioch = &((struct scmi_vio_channel *)scmi_vdev->priv)[index]; + + for (i = 0; i < vioch->max_msg; i++) { + struct scmi_vio_msg *msg; + + msg = devm_kzalloc(cinfo->dev, sizeof(*msg), GFP_KERNEL); + if (!msg) + return -ENOMEM; + + if (tx) { + msg->request = devm_kzalloc(cinfo->dev, + VIRTIO_SCMI_MAX_PDU_SIZE, + GFP_KERNEL); + if (!msg->request) + return -ENOMEM; + } + + msg->input = devm_kzalloc(cinfo->dev, VIRTIO_SCMI_MAX_PDU_SIZE, + GFP_KERNEL); + if (!msg->input) + return -ENOMEM; + + if (tx) { + spin_lock_irqsave(&vioch->lock, flags); + list_add_tail(&msg->list, &vioch->free_list); + spin_unlock_irqrestore(&vioch->lock, flags); + } else { + scmi_vio_feed_vq_rx(vioch, msg); + } + } + + spin_lock_irqsave(&vioch->lock, flags); + cinfo->transport_info = vioch; + /* Indirectly setting channel not available any more */ + vioch->cinfo = cinfo; + spin_unlock_irqrestore(&vioch->lock, flags); + + spin_lock_irqsave(&vioch->ready_lock, flags); + vioch->ready = true; + spin_unlock_irqrestore(&vioch->ready_lock, flags); + + return 0; +} + +static int virtio_chan_free(int id, void *p, void *data) +{ + unsigned long flags; + struct scmi_chan_info *cinfo = p; + struct scmi_vio_channel *vioch = cinfo->transport_info; + + spin_lock_irqsave(&vioch->ready_lock, flags); + vioch->ready = false; + spin_unlock_irqrestore(&vioch->ready_lock, flags); + + scmi_free_channel(cinfo, data, id); + + spin_lock_irqsave(&vioch->lock, flags); + vioch->cinfo = NULL; + spin_unlock_irqrestore(&vioch->lock, flags); + + return 0; +} + +static int virtio_send_message(struct scmi_chan_info *cinfo, + struct scmi_xfer *xfer) +{ + struct scmi_vio_channel *vioch = cinfo->transport_info; + struct scatterlist sg_out; + struct scatterlist sg_in; + struct scatterlist *sgs[DESCRIPTORS_PER_TX_MSG] = { &sg_out, &sg_in }; + unsigned long flags; + int rc; + struct scmi_vio_msg *msg; + + spin_lock_irqsave(&vioch->lock, flags); + + if (list_empty(&vioch->free_list)) { + spin_unlock_irqrestore(&vioch->lock, flags); + return -EBUSY; + } + + msg = list_first_entry(&vioch->free_list, typeof(*msg), list); + list_del(&msg->list); + + msg_tx_prepare(msg->request, xfer); + + sg_init_one(&sg_out, msg->request, msg_command_size(xfer)); + sg_init_one(&sg_in, msg->input, msg_response_size(xfer)); + + rc = virtqueue_add_sgs(vioch->vqueue, sgs, 1, 1, msg, GFP_ATOMIC); + if (rc) { + list_add(&msg->list, &vioch->free_list); + dev_err_once(vioch->cinfo->dev, + "%s() failed to add to virtqueue (%d)\n", __func__, + rc); + } else { + virtqueue_kick(vioch->vqueue); + } + + spin_unlock_irqrestore(&vioch->lock, flags); + + return rc; +} + +static void virtio_fetch_response(struct scmi_chan_info *cinfo, + struct scmi_xfer *xfer) +{ + struct scmi_vio_msg *msg = xfer->priv; + + if (msg) { + msg_fetch_response(msg->input, msg->rx_len, xfer); + xfer->priv = NULL; + } +} + +static void virtio_fetch_notification(struct scmi_chan_info *cinfo, + size_t max_len, struct scmi_xfer *xfer) +{ + struct scmi_vio_msg *msg = xfer->priv; + + if (msg) { + msg_fetch_notification(msg->input, msg->rx_len, max_len, xfer); + xfer->priv = NULL; + } +} + +static const struct scmi_transport_ops scmi_virtio_ops = { + .link_supplier = virtio_link_supplier, + .chan_available = virtio_chan_available, + .chan_setup = virtio_chan_setup, + .chan_free = virtio_chan_free, + .get_max_msg = virtio_get_max_msg, + .send_message = virtio_send_message, + .fetch_response = virtio_fetch_response, + .fetch_notification = virtio_fetch_notification, +}; + +static int scmi_vio_probe(struct virtio_device *vdev) +{ + struct device *dev = &vdev->dev; + struct scmi_vio_channel *channels; + bool have_vq_rx; + int vq_cnt; + int i; + int ret; + struct virtqueue *vqs[VIRTIO_SCMI_VQ_MAX_CNT]; + + /* Only one SCMI VirtiO device allowed */ + if (scmi_vdev) + return -EINVAL; + + have_vq_rx = scmi_vio_have_vq_rx(vdev); + vq_cnt = have_vq_rx ? VIRTIO_SCMI_VQ_MAX_CNT : 1; + + channels = devm_kcalloc(dev, vq_cnt, sizeof(*channels), GFP_KERNEL); + if (!channels) + return -ENOMEM; + + if (have_vq_rx) + channels[VIRTIO_SCMI_VQ_RX].is_rx = true; + + ret = virtio_find_vqs(vdev, vq_cnt, vqs, scmi_vio_complete_callbacks, + scmi_vio_vqueue_names, NULL); + if (ret) { + dev_err(dev, "Failed to get %d virtqueue(s)\n", vq_cnt); + return ret; + } + + for (i = 0; i < vq_cnt; i++) { + unsigned int sz; + + spin_lock_init(&channels[i].lock); + spin_lock_init(&channels[i].ready_lock); + INIT_LIST_HEAD(&channels[i].free_list); + channels[i].vqueue = vqs[i]; + + sz = virtqueue_get_vring_size(channels[i].vqueue); + /* Tx messages need multiple descriptors. */ + if (!channels[i].is_rx) + sz /= DESCRIPTORS_PER_TX_MSG; + + if (sz > MSG_TOKEN_MAX) { + dev_info_once(dev, + "%s virtqueue could hold %d messages. Only %ld allowed to be pending.\n", + channels[i].is_rx ? "rx" : "tx", + sz, MSG_TOKEN_MAX); + sz = MSG_TOKEN_MAX; + } + channels[i].max_msg = sz; + } + + vdev->priv = channels; + scmi_vdev = vdev; + + return 0; +} + +static void scmi_vio_remove(struct virtio_device *vdev) +{ + vdev->config->reset(vdev); + vdev->config->del_vqs(vdev); + scmi_vdev = NULL; +} + +static int scmi_vio_validate(struct virtio_device *vdev) +{ + if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) { + dev_err(&vdev->dev, + "device does not comply with spec version 1.x\n"); + return -EINVAL; + } + + return 0; +} + +static unsigned int features[] = { + VIRTIO_SCMI_F_P2A_CHANNELS, +}; + +static const struct virtio_device_id id_table[] = { + { VIRTIO_ID_SCMI, VIRTIO_DEV_ANY_ID }, + { 0 } +}; + +static struct virtio_driver virtio_scmi_driver = { + .driver.name = "scmi-virtio", + .driver.owner = THIS_MODULE, + .feature_table = features, + .feature_table_size = ARRAY_SIZE(features), + .id_table = id_table, + .probe = scmi_vio_probe, + .remove = scmi_vio_remove, + .validate = scmi_vio_validate, +}; + +static int __init virtio_scmi_init(void) +{ + return register_virtio_driver(&virtio_scmi_driver); +} + +static void __exit virtio_scmi_exit(void) +{ + unregister_virtio_driver(&virtio_scmi_driver); +} + +const struct scmi_desc scmi_virtio_desc = { + .transport_init = virtio_scmi_init, + .transport_exit = virtio_scmi_exit, + .ops = &scmi_virtio_ops, + .max_rx_timeout_ms = 60000, /* for non-realtime virtio devices */ + .max_msg = 0, /* overridden by virtio_get_max_msg() */ + .max_msg_size = VIRTIO_SCMI_MAX_MSG_SIZE, +}; |