From 75f353b61342b5847c7f6d8499fd6301dce09845 Mon Sep 17 00:00:00 2001 From: Grant Likely Date: Tue, 24 Jun 2014 16:13:47 +0100 Subject: of/platform: Fix of_platform_device_destroy iteration of devices of_platform_destroy does not work properly, since the tree population test was iterating on all devices having as its parent the given platform device. The check was intended to check whether any other platform or amba devices created by of_platform_populate were still populated, but instead checked for every kind of device. This is wrong, since platform devices typically create a subsystem regular device and set themselves as parents. Instead, go ahead and call the unregister functions for any devices created with of_platform_populate. The driver core will take care of unbinding drivers, and drivers are responsible for getting rid of any child devices that weren't created by of_platform_populate. Signed-off-by: Grant Likely Signed-off-by: Pantelis Antoniou --- drivers/of/platform.c | 32 +++++++++----------------------- 1 file changed, 9 insertions(+), 23 deletions(-) (limited to 'drivers/of') diff --git a/drivers/of/platform.c b/drivers/of/platform.c index 500436f9be7f..0197725e033a 100644 --- a/drivers/of/platform.c +++ b/drivers/of/platform.c @@ -422,6 +422,7 @@ static int of_platform_bus_create(struct device_node *bus, break; } } + of_node_set_flag(bus, OF_POPULATED_BUS); return rc; } @@ -508,19 +509,13 @@ EXPORT_SYMBOL_GPL(of_platform_populate); static int of_platform_device_destroy(struct device *dev, void *data) { - bool *children_left = data; - /* Do not touch devices not populated from the device tree */ - if (!dev->of_node || !of_node_check_flag(dev->of_node, OF_POPULATED)) { - *children_left = true; + if (!dev->of_node || !of_node_check_flag(dev->of_node, OF_POPULATED)) return 0; - } - /* Recurse, but don't touch this device if it has any children left */ - if (of_platform_depopulate(dev) != 0) { - *children_left = true; - return 0; - } + /* Recurse for any nodes that were treated as busses */ + if (of_node_check_flag(dev->of_node, OF_POPULATED_BUS)) + device_for_each_child(dev, NULL, of_platform_device_destroy); if (dev->bus == &platform_bus_type) platform_device_unregister(to_platform_device(dev)); @@ -528,19 +523,15 @@ static int of_platform_device_destroy(struct device *dev, void *data) else if (dev->bus == &amba_bustype) amba_device_unregister(to_amba_device(dev)); #endif - else { - *children_left = true; - return 0; - } of_node_clear_flag(dev->of_node, OF_POPULATED); - + of_node_clear_flag(dev->of_node, OF_POPULATED_BUS); return 0; } /** * of_platform_depopulate() - Remove devices populated from device tree - * @parent: device which childred will be removed + * @parent: device which children will be removed * * Complementary to of_platform_populate(), this function removes children * of the given device (and, recurrently, their children) that have been @@ -550,14 +541,9 @@ static int of_platform_device_destroy(struct device *dev, void *data) * Returns 0 when all children devices have been removed or * -EBUSY when some children remained. */ -int of_platform_depopulate(struct device *parent) +void of_platform_depopulate(struct device *parent) { - bool children_left = false; - - device_for_each_child(parent, &children_left, - of_platform_device_destroy); - - return children_left ? -EBUSY : 0; + device_for_each_child(parent, NULL, of_platform_device_destroy); } EXPORT_SYMBOL_GPL(of_platform_depopulate); -- cgit From c05aba2bd5f9dd3f363611ff844513de1341ac60 Mon Sep 17 00:00:00 2001 From: Pantelis Antoniou Date: Fri, 4 Jul 2014 19:58:03 +0300 Subject: of: rename of_aliases_mutex to just of_mutex We're overloading usage of of_aliases_mutex for sysfs changes, so rename to something that is more generic. Signed-off-by: Pantelis Antoniou Signed-off-by: Grant Likely --- drivers/of/base.c | 19 +++++++++---------- drivers/of/device.c | 4 ++-- drivers/of/of_private.h | 2 +- 3 files changed, 12 insertions(+), 13 deletions(-) (limited to 'drivers/of') diff --git a/drivers/of/base.c b/drivers/of/base.c index b9864806e9b8..e48a1b90a392 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -40,10 +40,9 @@ static struct device_node *of_stdout; static struct kset *of_kset; /* - * Used to protect the of_aliases; but also overloaded to hold off addition of - * nodes to sysfs + * Used to protect the of_aliases, to hold off addition of nodes to sysfs */ -DEFINE_MUTEX(of_aliases_mutex); +DEFINE_MUTEX(of_mutex); /* use when traversing tree through the allnext, child, sibling, * or parent members of struct device_node. @@ -255,13 +254,13 @@ int of_node_add(struct device_node *np) * Grab the mutex here so that in a race condition between of_init() and * of_node_add(), node addition will still be consistent. */ - mutex_lock(&of_aliases_mutex); + mutex_lock(&of_mutex); if (of_kset) rc = __of_node_add(np); else /* This scenario may be perfectly valid, but report it anyway */ pr_info("of_node_add(%s) before of_init()\n", np->full_name); - mutex_unlock(&of_aliases_mutex); + mutex_unlock(&of_mutex); return rc; } @@ -289,15 +288,15 @@ static int __init of_init(void) struct device_node *np; /* Create the kset, and register existing nodes */ - mutex_lock(&of_aliases_mutex); + mutex_lock(&of_mutex); of_kset = kset_create_and_add("devicetree", NULL, firmware_kobj); if (!of_kset) { - mutex_unlock(&of_aliases_mutex); + mutex_unlock(&of_mutex); return -ENOMEM; } for_each_of_allnodes(np) __of_node_add(np); - mutex_unlock(&of_aliases_mutex); + mutex_unlock(&of_mutex); /* Symlink in /proc as required by userspace ABI */ if (of_allnodes) @@ -2122,7 +2121,7 @@ int of_alias_get_id(struct device_node *np, const char *stem) struct alias_prop *app; int id = -ENODEV; - mutex_lock(&of_aliases_mutex); + mutex_lock(&of_mutex); list_for_each_entry(app, &aliases_lookup, link) { if (strcmp(app->stem, stem) != 0) continue; @@ -2132,7 +2131,7 @@ int of_alias_get_id(struct device_node *np, const char *stem) break; } } - mutex_unlock(&of_aliases_mutex); + mutex_unlock(&of_mutex); return id; } diff --git a/drivers/of/device.c b/drivers/of/device.c index dafb9736ab9b..46d6c75c1404 100644 --- a/drivers/of/device.c +++ b/drivers/of/device.c @@ -160,7 +160,7 @@ void of_device_uevent(struct device *dev, struct kobj_uevent_env *env) add_uevent_var(env, "OF_COMPATIBLE_N=%d", seen); seen = 0; - mutex_lock(&of_aliases_mutex); + mutex_lock(&of_mutex); list_for_each_entry(app, &aliases_lookup, link) { if (dev->of_node == app->np) { add_uevent_var(env, "OF_ALIAS_%d=%s", seen, @@ -168,7 +168,7 @@ void of_device_uevent(struct device *dev, struct kobj_uevent_env *env) seen++; } } - mutex_unlock(&of_aliases_mutex); + mutex_unlock(&of_mutex); } int of_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env) diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index ff350c8fa7ac..fcc70e74dfe0 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -31,6 +31,6 @@ struct alias_prop { char stem[0]; }; -extern struct mutex of_aliases_mutex; +extern struct mutex of_mutex; extern struct list_head aliases_lookup; #endif /* _LINUX_OF_PRIVATE_H */ -- cgit From 6afc0dc381573559251de9a8259404f49e6aed14 Mon Sep 17 00:00:00 2001 From: Grant Likely Date: Thu, 26 Jun 2014 15:40:48 +0100 Subject: of: Move CONFIG_OF_DYNAMIC code into a separate file Split the dynamic device tree code into a separate file to make it really clear what features CONFIF_OF_DYNAMIC add to the kernel. Without CONFIG_OF_DYNAMIC only properties can be changed, and notifiers do not get sent. Enabling it turns on reference counting, notifiers and the ability to add and remove nodes. v2: Moved of_node_release() into dynamic.c Signed-off-by: Grant Likely Signed-off-by: Pantelis Antoniou Cc: Rob Herring --- drivers/of/Makefile | 1 + drivers/of/base.c | 230 +----------------------------------------------- drivers/of/dynamic.c | 216 +++++++++++++++++++++++++++++++++++++++++++++ drivers/of/of_private.h | 18 ++++ 4 files changed, 236 insertions(+), 229 deletions(-) create mode 100644 drivers/of/dynamic.c (limited to 'drivers/of') diff --git a/drivers/of/Makefile b/drivers/of/Makefile index 099b1fb00af4..08e6c0f79806 100644 --- a/drivers/of/Makefile +++ b/drivers/of/Makefile @@ -1,4 +1,5 @@ obj-y = base.o device.o platform.o +obj-$(CONFIG_OF_DYNAMIC) += dynamic.o obj-$(CONFIG_OF_FLATTREE) += fdt.o obj-$(CONFIG_OF_EARLY_FLATTREE) += fdt_address.o obj-$(CONFIG_OF_PROMTREE) += pdt.o diff --git a/drivers/of/base.c b/drivers/of/base.c index e48a1b90a392..0d8955605738 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -88,79 +88,7 @@ int __weak of_node_to_nid(struct device_node *np) } #endif -#if defined(CONFIG_OF_DYNAMIC) -/** - * of_node_get - Increment refcount of a node - * @node: Node to inc refcount, NULL is supported to - * simplify writing of callers - * - * Returns node. - */ -struct device_node *of_node_get(struct device_node *node) -{ - if (node) - kobject_get(&node->kobj); - return node; -} -EXPORT_SYMBOL(of_node_get); - -static inline struct device_node *kobj_to_device_node(struct kobject *kobj) -{ - return container_of(kobj, struct device_node, kobj); -} - -/** - * of_node_release - release a dynamically allocated node - * @kref: kref element of the node to be released - * - * In of_node_put() this function is passed to kref_put() - * as the destructor. - */ -static void of_node_release(struct kobject *kobj) -{ - struct device_node *node = kobj_to_device_node(kobj); - struct property *prop = node->properties; - - /* We should never be releasing nodes that haven't been detached. */ - if (!of_node_check_flag(node, OF_DETACHED)) { - pr_err("ERROR: Bad of_node_put() on %s\n", node->full_name); - dump_stack(); - return; - } - - if (!of_node_check_flag(node, OF_DYNAMIC)) - return; - - while (prop) { - struct property *next = prop->next; - kfree(prop->name); - kfree(prop->value); - kfree(prop); - prop = next; - - if (!prop) { - prop = node->deadprops; - node->deadprops = NULL; - } - } - kfree(node->full_name); - kfree(node->data); - kfree(node); -} - -/** - * of_node_put - Decrement refcount of a node - * @node: Node to dec refcount, NULL is supported to - * simplify writing of callers - * - */ -void of_node_put(struct device_node *node) -{ - if (node) - kobject_put(&node->kobj); -} -EXPORT_SYMBOL(of_node_put); -#else +#ifndef CONFIG_OF_DYNAMIC static void of_node_release(struct kobject *kobj) { /* Without CONFIG_OF_DYNAMIC, no nodes gets freed */ @@ -264,25 +192,6 @@ int of_node_add(struct device_node *np) return rc; } -#if defined(CONFIG_OF_DYNAMIC) -static void of_node_remove(struct device_node *np) -{ - struct property *pp; - - BUG_ON(!of_node_is_initialized(np)); - - /* only remove properties if on sysfs */ - if (of_node_is_attached(np)) { - for_each_property_of_node(np, pp) - sysfs_remove_bin_file(&np->kobj, &pp->attr); - kobject_del(&np->kobj); - } - - /* finally remove the kobj_init ref */ - of_node_put(np); -} -#endif - static int __init of_init(void) { struct device_node *np; @@ -1747,28 +1656,6 @@ int of_count_phandle_with_args(const struct device_node *np, const char *list_na } EXPORT_SYMBOL(of_count_phandle_with_args); -#if defined(CONFIG_OF_DYNAMIC) -static int of_property_notify(int action, struct device_node *np, - struct property *prop) -{ - struct of_prop_reconfig pr; - - /* only call notifiers if the node is attached */ - if (!of_node_is_attached(np)) - return 0; - - pr.dn = np; - pr.prop = prop; - return of_reconfig_notify(action, &pr); -} -#else -static int of_property_notify(int action, struct device_node *np, - struct property *prop) -{ - return 0; -} -#endif - /** * __of_add_property - Add a property to a node without lock operations */ @@ -1915,121 +1802,6 @@ int of_update_property(struct device_node *np, struct property *newprop) return 0; } -#if defined(CONFIG_OF_DYNAMIC) -/* - * Support for dynamic device trees. - * - * On some platforms, the device tree can be manipulated at runtime. - * The routines in this section support adding, removing and changing - * device tree nodes. - */ - -static BLOCKING_NOTIFIER_HEAD(of_reconfig_chain); - -int of_reconfig_notifier_register(struct notifier_block *nb) -{ - return blocking_notifier_chain_register(&of_reconfig_chain, nb); -} -EXPORT_SYMBOL_GPL(of_reconfig_notifier_register); - -int of_reconfig_notifier_unregister(struct notifier_block *nb) -{ - return blocking_notifier_chain_unregister(&of_reconfig_chain, nb); -} -EXPORT_SYMBOL_GPL(of_reconfig_notifier_unregister); - -int of_reconfig_notify(unsigned long action, void *p) -{ - int rc; - - rc = blocking_notifier_call_chain(&of_reconfig_chain, action, p); - return notifier_to_errno(rc); -} - -/** - * of_attach_node - Plug a device node into the tree and global list. - */ -int of_attach_node(struct device_node *np) -{ - unsigned long flags; - int rc; - - rc = of_reconfig_notify(OF_RECONFIG_ATTACH_NODE, np); - if (rc) - return rc; - - raw_spin_lock_irqsave(&devtree_lock, flags); - np->sibling = np->parent->child; - np->allnext = np->parent->allnext; - np->parent->allnext = np; - np->parent->child = np; - of_node_clear_flag(np, OF_DETACHED); - raw_spin_unlock_irqrestore(&devtree_lock, flags); - - of_node_add(np); - return 0; -} - -/** - * of_detach_node - "Unplug" a node from the device tree. - * - * The caller must hold a reference to the node. The memory associated with - * the node is not freed until its refcount goes to zero. - */ -int of_detach_node(struct device_node *np) -{ - struct device_node *parent; - unsigned long flags; - int rc = 0; - - rc = of_reconfig_notify(OF_RECONFIG_DETACH_NODE, np); - if (rc) - return rc; - - raw_spin_lock_irqsave(&devtree_lock, flags); - - if (of_node_check_flag(np, OF_DETACHED)) { - /* someone already detached it */ - raw_spin_unlock_irqrestore(&devtree_lock, flags); - return rc; - } - - parent = np->parent; - if (!parent) { - raw_spin_unlock_irqrestore(&devtree_lock, flags); - return rc; - } - - if (of_allnodes == np) - of_allnodes = np->allnext; - else { - struct device_node *prev; - for (prev = of_allnodes; - prev->allnext != np; - prev = prev->allnext) - ; - prev->allnext = np->allnext; - } - - if (parent->child == np) - parent->child = np->sibling; - else { - struct device_node *prevsib; - for (prevsib = np->parent->child; - prevsib->sibling != np; - prevsib = prevsib->sibling) - ; - prevsib->sibling = np->sibling; - } - - of_node_set_flag(np, OF_DETACHED); - raw_spin_unlock_irqrestore(&devtree_lock, flags); - - of_node_remove(np); - return rc; -} -#endif /* defined(CONFIG_OF_DYNAMIC) */ - static void of_alias_add(struct alias_prop *ap, struct device_node *np, int id, const char *stem, int stem_len) { diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c new file mode 100644 index 000000000000..125994330437 --- /dev/null +++ b/drivers/of/dynamic.c @@ -0,0 +1,216 @@ +/* + * Support for dynamic device trees. + * + * On some platforms, the device tree can be manipulated at runtime. + * The routines in this section support adding, removing and changing + * device tree nodes. + */ + +#include +#include +#include +#include +#include + +#include "of_private.h" + +/** + * of_node_get() - Increment refcount of a node + * @node: Node to inc refcount, NULL is supported to simplify writing of + * callers + * + * Returns node. + */ +struct device_node *of_node_get(struct device_node *node) +{ + if (node) + kobject_get(&node->kobj); + return node; +} +EXPORT_SYMBOL(of_node_get); + +/** + * of_node_put() - Decrement refcount of a node + * @node: Node to dec refcount, NULL is supported to simplify writing of + * callers + */ +void of_node_put(struct device_node *node) +{ + if (node) + kobject_put(&node->kobj); +} +EXPORT_SYMBOL(of_node_put); + +static void of_node_remove(struct device_node *np) +{ + struct property *pp; + + BUG_ON(!of_node_is_initialized(np)); + + /* only remove properties if on sysfs */ + if (of_node_is_attached(np)) { + for_each_property_of_node(np, pp) + sysfs_remove_bin_file(&np->kobj, &pp->attr); + kobject_del(&np->kobj); + } + + /* finally remove the kobj_init ref */ + of_node_put(np); +} + +static BLOCKING_NOTIFIER_HEAD(of_reconfig_chain); + +int of_reconfig_notifier_register(struct notifier_block *nb) +{ + return blocking_notifier_chain_register(&of_reconfig_chain, nb); +} +EXPORT_SYMBOL_GPL(of_reconfig_notifier_register); + +int of_reconfig_notifier_unregister(struct notifier_block *nb) +{ + return blocking_notifier_chain_unregister(&of_reconfig_chain, nb); +} +EXPORT_SYMBOL_GPL(of_reconfig_notifier_unregister); + +int of_reconfig_notify(unsigned long action, void *p) +{ + int rc; + + rc = blocking_notifier_call_chain(&of_reconfig_chain, action, p); + return notifier_to_errno(rc); +} + +int of_property_notify(int action, struct device_node *np, + struct property *prop) +{ + struct of_prop_reconfig pr; + + /* only call notifiers if the node is attached */ + if (!of_node_is_attached(np)) + return 0; + + pr.dn = np; + pr.prop = prop; + return of_reconfig_notify(action, &pr); +} + +/** + * of_attach_node() - Plug a device node into the tree and global list. + */ +int of_attach_node(struct device_node *np) +{ + unsigned long flags; + int rc; + + rc = of_reconfig_notify(OF_RECONFIG_ATTACH_NODE, np); + if (rc) + return rc; + + raw_spin_lock_irqsave(&devtree_lock, flags); + np->sibling = np->parent->child; + np->allnext = np->parent->allnext; + np->parent->allnext = np; + np->parent->child = np; + of_node_clear_flag(np, OF_DETACHED); + raw_spin_unlock_irqrestore(&devtree_lock, flags); + + of_node_add(np); + return 0; +} + +/** + * of_detach_node() - "Unplug" a node from the device tree. + * + * The caller must hold a reference to the node. The memory associated with + * the node is not freed until its refcount goes to zero. + */ +int of_detach_node(struct device_node *np) +{ + struct device_node *parent; + unsigned long flags; + int rc = 0; + + rc = of_reconfig_notify(OF_RECONFIG_DETACH_NODE, np); + if (rc) + return rc; + + raw_spin_lock_irqsave(&devtree_lock, flags); + + if (of_node_check_flag(np, OF_DETACHED)) { + /* someone already detached it */ + raw_spin_unlock_irqrestore(&devtree_lock, flags); + return rc; + } + + parent = np->parent; + if (!parent) { + raw_spin_unlock_irqrestore(&devtree_lock, flags); + return rc; + } + + if (of_allnodes == np) + of_allnodes = np->allnext; + else { + struct device_node *prev; + for (prev = of_allnodes; + prev->allnext != np; + prev = prev->allnext) + ; + prev->allnext = np->allnext; + } + + if (parent->child == np) + parent->child = np->sibling; + else { + struct device_node *prevsib; + for (prevsib = np->parent->child; + prevsib->sibling != np; + prevsib = prevsib->sibling) + ; + prevsib->sibling = np->sibling; + } + + of_node_set_flag(np, OF_DETACHED); + raw_spin_unlock_irqrestore(&devtree_lock, flags); + + of_node_remove(np); + return rc; +} + +/** + * of_node_release() - release a dynamically allocated node + * @kref: kref element of the node to be released + * + * In of_node_put() this function is passed to kref_put() as the destructor. + */ +void of_node_release(struct kobject *kobj) +{ + struct device_node *node = kobj_to_device_node(kobj); + struct property *prop = node->properties; + + /* We should never be releasing nodes that haven't been detached. */ + if (!of_node_check_flag(node, OF_DETACHED)) { + pr_err("ERROR: Bad of_node_put() on %s\n", node->full_name); + dump_stack(); + return; + } + + if (!of_node_check_flag(node, OF_DYNAMIC)) + return; + + while (prop) { + struct property *next = prop->next; + kfree(prop->name); + kfree(prop->value); + kfree(prop); + prop = next; + + if (!prop) { + prop = node->deadprops; + node->deadprops = NULL; + } + } + kfree(node->full_name); + kfree(node->data); + kfree(node); +} diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index fcc70e74dfe0..c270f2037779 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -33,4 +33,22 @@ struct alias_prop { extern struct mutex of_mutex; extern struct list_head aliases_lookup; + +static inline struct device_node *kobj_to_device_node(struct kobject *kobj) +{ + return container_of(kobj, struct device_node, kobj); +} + +#if defined(CONFIG_OF_DYNAMIC) +extern int of_property_notify(int action, struct device_node *np, + struct property *prop); +extern void of_node_release(struct kobject *kobj); +#else /* CONFIG_OF_DYNAMIC */ +static inline int of_property_notify(int action, struct device_node *np, + struct property *prop) +{ + return 0; +} +#endif /* CONFIG_OF_DYNAMIC */ + #endif /* _LINUX_OF_PRIVATE_H */ -- cgit From 698433963b98d6de7b102c242805c99fda4fa1fb Mon Sep 17 00:00:00 2001 From: Pantelis Antoniou Date: Fri, 4 Jul 2014 19:58:47 +0300 Subject: OF: Utility helper functions for dynamic nodes Introduce helper functions for working with the live DT tree, all of them related to dynamically adding/removing nodes and properties. __of_prop_dup() copies a property dynamically __of_node_alloc() creates an empty node Bug fix about prop->len == 0 by Ionut Nicu Signed-off-by: Pantelis Antoniou [glikely: Added unittest for of_copy_property and dropped fine-grained allocations] [glikely: removed name, type and phandle arguments from __of_node_alloc] Signed-off-by: Grant Likely --- drivers/of/dynamic.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++++ drivers/of/of_private.h | 10 +++++++ drivers/of/selftest.c | 28 ++++++++++++++++++ 3 files changed, 115 insertions(+) (limited to 'drivers/of') diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c index 125994330437..e0c4c6e25980 100644 --- a/drivers/of/dynamic.c +++ b/drivers/of/dynamic.c @@ -214,3 +214,80 @@ void of_node_release(struct kobject *kobj) kfree(node->data); kfree(node); } + +/** + * __of_prop_dup - Copy a property dynamically. + * @prop: Property to copy + * @allocflags: Allocation flags (typically pass GFP_KERNEL) + * + * Copy a property by dynamically allocating the memory of both the + * property stucture and the property name & contents. The property's + * flags have the OF_DYNAMIC bit set so that we can differentiate between + * dynamically allocated properties and not. + * Returns the newly allocated property or NULL on out of memory error. + */ +struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags) +{ + struct property *new; + + new = kzalloc(sizeof(*new), allocflags); + if (!new) + return NULL; + + /* + * NOTE: There is no check for zero length value. + * In case of a boolean property This will allocate a value + * of zero bytes. We do this to work around the use + * of of_get_property() calls on boolean values. + */ + new->name = kstrdup(prop->name, allocflags); + new->value = kmemdup(prop->value, prop->length, allocflags); + new->length = prop->length; + if (!new->name || !new->value) + goto err_free; + + /* mark the property as dynamic */ + of_property_set_flag(new, OF_DYNAMIC); + + return new; + + err_free: + kfree(new->name); + kfree(new->value); + kfree(new); + return NULL; +} + +/** + * __of_node_alloc() - Create an empty device node dynamically. + * @full_name: Full name of the new device node + * @allocflags: Allocation flags (typically pass GFP_KERNEL) + * + * Create an empty device tree node, suitable for further modification. + * The node data are dynamically allocated and all the node flags + * have the OF_DYNAMIC & OF_DETACHED bits set. + * Returns the newly allocated node or NULL on out of memory error. + */ +struct device_node *__of_node_alloc(const char *full_name, gfp_t allocflags) +{ + struct device_node *node; + + node = kzalloc(sizeof(*node), allocflags); + if (!node) + return NULL; + + node->full_name = kstrdup(full_name, allocflags); + of_node_set_flag(node, OF_DYNAMIC); + of_node_set_flag(node, OF_DETACHED); + if (!node->full_name) + goto err_free; + + of_node_init(node); + + return node; + + err_free: + kfree(node->full_name); + kfree(node); + return NULL; +} diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index c270f2037779..1799ed2b3808 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -51,4 +51,14 @@ static inline int of_property_notify(int action, struct device_node *np, } #endif /* CONFIG_OF_DYNAMIC */ +/** + * General utilities for working with live trees. + * + * All functions with two leading underscores operate + * without taking node references, so you either have to + * own the devtree lock or work on detached trees only. + */ +struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags); +struct device_node *__of_node_alloc(const char *full_name, gfp_t allocflags); + #endif /* _LINUX_OF_PRIVATE_H */ diff --git a/drivers/of/selftest.c b/drivers/of/selftest.c index 077314eebb95..ee2166f0f36a 100644 --- a/drivers/of/selftest.c +++ b/drivers/of/selftest.c @@ -16,6 +16,8 @@ #include #include +#include "of_private.h" + static struct selftest_results { int passed; int failed; @@ -266,6 +268,31 @@ static void __init of_selftest_property_match_string(void) selftest(rc == -EILSEQ, "unterminated string; rc=%i", rc); } +#define propcmp(p1, p2) (((p1)->length == (p2)->length) && \ + (p1)->value && (p2)->value && \ + !memcmp((p1)->value, (p2)->value, (p1)->length) && \ + !strcmp((p1)->name, (p2)->name)) +static void __init of_selftest_property_copy(void) +{ +#ifdef CONFIG_OF_DYNAMIC + struct property p1 = { .name = "p1", .length = 0, .value = "" }; + struct property p2 = { .name = "p2", .length = 5, .value = "abcd" }; + struct property *new; + + new = __of_prop_dup(&p1, GFP_KERNEL); + selftest(new && propcmp(&p1, new), "empty property didn't copy correctly\n"); + kfree(new->value); + kfree(new->name); + kfree(new); + + new = __of_prop_dup(&p2, GFP_KERNEL); + selftest(new && propcmp(&p2, new), "non-empty property didn't copy correctly\n"); + kfree(new->value); + kfree(new->name); + kfree(new); +#endif +} + static void __init of_selftest_parse_interrupts(void) { struct device_node *np; @@ -533,6 +560,7 @@ static int __init of_selftest(void) of_selftest_dynamic(); of_selftest_parse_phandle_with_args(); of_selftest_property_match_string(); + of_selftest_property_copy(); of_selftest_parse_interrupts(); of_selftest_parse_interrupts_extended(); of_selftest_match_node(); -- cgit From d8c50088417ebf61ad8b132caad20d10f7736034 Mon Sep 17 00:00:00 2001 From: Pantelis Antoniou Date: Fri, 4 Jul 2014 19:58:46 +0300 Subject: of: Create unlocked versions of node and property add/remove functions The DT overlay code will need to manipulate nodes and properties while already holding the devicetree lock, or on nodes that are not yet attached to the tree, but the current helper functions don't allow that. Extract the core behaviour from the accessors and create the following unlocked variants. The unlocked variants require either the lock to already be held or for the nodes to be detached from the tree. Changes to live nodes will not get updated in sysfs, so the caller must arrange for housekeeping to take place after dropping the lock. The new functions are: __of_add_property(), __of_remove_property(), __of_update_property(), __of_attach_node() and __of_detach_node(). Signed-off-by: Pantelis Antoniou [Remove unnecessary diff hunks and rewrite commit text] Signed-off-by: Grant Likely --- drivers/of/base.c | 91 +++++++++++++++++++++++++++++-------------------- drivers/of/dynamic.c | 63 ++++++++++++++++++---------------- drivers/of/of_private.h | 8 +++++ 3 files changed, 96 insertions(+), 66 deletions(-) (limited to 'drivers/of') diff --git a/drivers/of/base.c b/drivers/of/base.c index 0d8955605738..b403f9d98461 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -1659,7 +1659,7 @@ EXPORT_SYMBOL(of_count_phandle_with_args); /** * __of_add_property - Add a property to a node without lock operations */ -static int __of_add_property(struct device_node *np, struct property *prop) +int __of_add_property(struct device_node *np, struct property *prop) { struct property **next; @@ -1701,6 +1701,25 @@ int of_add_property(struct device_node *np, struct property *prop) return rc; } +int __of_remove_property(struct device_node *np, struct property *prop) +{ + struct property **next; + + for (next = &np->properties; *next; next = &(*next)->next) { + if (*next == prop) + break; + } + if (*next == NULL) + return -ENODEV; + + /* found the node */ + *next = prop->next; + prop->next = np->deadprops; + np->deadprops = prop; + + return 0; +} + /** * of_remove_property - Remove a property from a node. * @@ -1711,9 +1730,7 @@ int of_add_property(struct device_node *np, struct property *prop) */ int of_remove_property(struct device_node *np, struct property *prop) { - struct property **next; unsigned long flags; - int found = 0; int rc; rc = of_property_notify(OF_RECONFIG_REMOVE_PROPERTY, np, prop); @@ -1721,22 +1738,11 @@ int of_remove_property(struct device_node *np, struct property *prop) return rc; raw_spin_lock_irqsave(&devtree_lock, flags); - next = &np->properties; - while (*next) { - if (*next == prop) { - /* found the node */ - *next = prop->next; - prop->next = np->deadprops; - np->deadprops = prop; - found = 1; - break; - } - next = &(*next)->next; - } + rc = __of_remove_property(np, prop); raw_spin_unlock_irqrestore(&devtree_lock, flags); - if (!found) - return -ENODEV; + if (rc) + return rc; /* at early boot, bail hear and defer setup to of_init() */ if (!of_kset) @@ -1747,6 +1753,32 @@ int of_remove_property(struct device_node *np, struct property *prop) return 0; } +int __of_update_property(struct device_node *np, struct property *newprop, + struct property **oldpropp) +{ + struct property **next, *oldprop; + + for (next = &np->properties; *next; next = &(*next)->next) { + if (of_prop_cmp((*next)->name, newprop->name) == 0) + break; + } + *oldpropp = oldprop = *next; + + if (oldprop) { + /* replace the node */ + newprop->next = oldprop->next; + *next = newprop; + oldprop->next = np->deadprops; + np->deadprops = oldprop; + } else { + /* new node */ + newprop->next = NULL; + *next = newprop; + } + + return 0; +} + /* * of_update_property - Update a property in a node, if the property does * not exist, add it. @@ -1758,34 +1790,19 @@ int of_remove_property(struct device_node *np, struct property *prop) */ int of_update_property(struct device_node *np, struct property *newprop) { - struct property **next, *oldprop; + struct property *oldprop; unsigned long flags; int rc; + if (!newprop->name) + return -EINVAL; + rc = of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop); if (rc) return rc; - if (!newprop->name) - return -EINVAL; - raw_spin_lock_irqsave(&devtree_lock, flags); - next = &np->properties; - oldprop = __of_find_property(np, newprop->name, NULL); - if (!oldprop) { - /* add the new node */ - rc = __of_add_property(np, newprop); - } else while (*next) { - /* replace the node */ - if (*next == oldprop) { - newprop->next = oldprop->next; - *next = newprop; - oldprop->next = np->deadprops; - np->deadprops = oldprop; - break; - } - next = &(*next)->next; - } + rc = __of_update_property(np, newprop, &oldprop); raw_spin_unlock_irqrestore(&devtree_lock, flags); if (rc) return rc; diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c index e0c4c6e25980..75fcc66fcefd 100644 --- a/drivers/of/dynamic.c +++ b/drivers/of/dynamic.c @@ -94,6 +94,15 @@ int of_property_notify(int action, struct device_node *np, return of_reconfig_notify(action, &pr); } +void __of_attach_node(struct device_node *np) +{ + np->sibling = np->parent->child; + np->allnext = np->parent->allnext; + np->parent->allnext = np; + np->parent->child = np; + of_node_clear_flag(np, OF_DETACHED); +} + /** * of_attach_node() - Plug a device node into the tree and global list. */ @@ -107,46 +116,23 @@ int of_attach_node(struct device_node *np) return rc; raw_spin_lock_irqsave(&devtree_lock, flags); - np->sibling = np->parent->child; - np->allnext = np->parent->allnext; - np->parent->allnext = np; - np->parent->child = np; - of_node_clear_flag(np, OF_DETACHED); + __of_attach_node(np); raw_spin_unlock_irqrestore(&devtree_lock, flags); of_node_add(np); return 0; } -/** - * of_detach_node() - "Unplug" a node from the device tree. - * - * The caller must hold a reference to the node. The memory associated with - * the node is not freed until its refcount goes to zero. - */ -int of_detach_node(struct device_node *np) +void __of_detach_node(struct device_node *np) { struct device_node *parent; - unsigned long flags; - int rc = 0; - - rc = of_reconfig_notify(OF_RECONFIG_DETACH_NODE, np); - if (rc) - return rc; - raw_spin_lock_irqsave(&devtree_lock, flags); - - if (of_node_check_flag(np, OF_DETACHED)) { - /* someone already detached it */ - raw_spin_unlock_irqrestore(&devtree_lock, flags); - return rc; - } + if (WARN_ON(of_node_check_flag(np, OF_DETACHED))) + return; parent = np->parent; - if (!parent) { - raw_spin_unlock_irqrestore(&devtree_lock, flags); - return rc; - } + if (WARN_ON(!parent)) + return; if (of_allnodes == np) of_allnodes = np->allnext; @@ -171,6 +157,25 @@ int of_detach_node(struct device_node *np) } of_node_set_flag(np, OF_DETACHED); +} + +/** + * of_detach_node() - "Unplug" a node from the device tree. + * + * The caller must hold a reference to the node. The memory associated with + * the node is not freed until its refcount goes to zero. + */ +int of_detach_node(struct device_node *np) +{ + unsigned long flags; + int rc = 0; + + rc = of_reconfig_notify(OF_RECONFIG_DETACH_NODE, np); + if (rc) + return rc; + + raw_spin_lock_irqsave(&devtree_lock, flags); + __of_detach_node(np); raw_spin_unlock_irqrestore(&devtree_lock, flags); of_node_remove(np); diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index 1799ed2b3808..0f6089722af9 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -61,4 +61,12 @@ static inline int of_property_notify(int action, struct device_node *np, struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags); struct device_node *__of_node_alloc(const char *full_name, gfp_t allocflags); +extern int __of_add_property(struct device_node *np, struct property *prop); +extern int __of_remove_property(struct device_node *np, struct property *prop); +extern int __of_update_property(struct device_node *np, + struct property *newprop, struct property **oldprop); + +extern void __of_attach_node(struct device_node *np); +extern void __of_detach_node(struct device_node *np); + #endif /* _LINUX_OF_PRIVATE_H */ -- cgit From 8a2b22a2595bf89d4396530edf8388159fad9d83 Mon Sep 17 00:00:00 2001 From: Grant Likely Date: Wed, 23 Jul 2014 17:05:06 -0600 Subject: of: Make devicetree sysfs update functions consistent. All of the DT modification functions are split into two parts, the first part manipulates the DT data structure, and the second part updates sysfs, but the code isn't very consistent about how the second half is called. They don't all enforce the same rules about when it is valid to update sysfs, and there isn't any clarity on locking. The transactional DT modification feature that is coming also needs access to these functions so that it can perform all the structure changes together, and then all the sysfs updates as a second stage instead of doing each one at a time. Fix up the second have by creating a separate __of_*_sysfs() function for each of the helpers. The new functions have consistent naming (ie. of_node_add() becomes __of_attach_node_sysfs()) and all of them now defer if of_init hasn't been called yet. Callers of the new functions must hold the of_mutex to ensure there are no race conditions with of_init(). The mutex ensures that there will only ever be one writer to the tree at any given time. There can still be any number of readers and the raw_spin_lock is still used to make sure access to the data structure is still consistent. Finally, put the function prototypes into of_private.h so they are accessible to the transaction code. Signed-off-by: Pantelis Antoniou [grant.likely: Changed suffix from _post to _sysfs to match existing code] [grant.likely: Reorganized to eliminate trivial wrappers] Signed-off-by: Grant Likely --- drivers/of/base.c | 96 +++++++++++++++++++++++++------------------------ drivers/of/dynamic.c | 12 +++++-- drivers/of/of_private.h | 10 ++++++ 3 files changed, 69 insertions(+), 49 deletions(-) (limited to 'drivers/of') diff --git a/drivers/of/base.c b/drivers/of/base.c index b403f9d98461..ad4929cbd876 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -37,10 +37,13 @@ struct device_node *of_chosen; struct device_node *of_aliases; static struct device_node *of_stdout; -static struct kset *of_kset; +struct kset *of_kset; /* - * Used to protect the of_aliases, to hold off addition of nodes to sysfs + * Used to protect the of_aliases, to hold off addition of nodes to sysfs. + * This mutex must be held whenever modifications are being made to the + * device tree. The of_{attach,detach}_node() and + * of_{add,remove,update}_property() helpers make sure this happens. */ DEFINE_MUTEX(of_mutex); @@ -127,13 +130,16 @@ static const char *safe_name(struct kobject *kobj, const char *orig_name) return name; } -static int __of_add_property_sysfs(struct device_node *np, struct property *pp) +int __of_add_property_sysfs(struct device_node *np, struct property *pp) { int rc; /* Important: Don't leak passwords */ bool secure = strncmp(pp->name, "security-", 9) == 0; + if (!of_kset || !of_node_is_attached(np)) + return 0; + sysfs_bin_attr_init(&pp->attr); pp->attr.attr.name = safe_name(&np->kobj, pp->name); pp->attr.attr.mode = secure ? S_IRUSR : S_IRUGO; @@ -145,12 +151,15 @@ static int __of_add_property_sysfs(struct device_node *np, struct property *pp) return rc; } -static int __of_node_add(struct device_node *np) +int __of_attach_node_sysfs(struct device_node *np) { const char *name; struct property *pp; int rc; + if (!of_kset) + return 0; + np->kobj.kset = of_kset; if (!np->parent) { /* Nodes without parents are new top level trees */ @@ -172,26 +181,6 @@ static int __of_node_add(struct device_node *np) return 0; } -int of_node_add(struct device_node *np) -{ - int rc = 0; - - BUG_ON(!of_node_is_initialized(np)); - - /* - * Grab the mutex here so that in a race condition between of_init() and - * of_node_add(), node addition will still be consistent. - */ - mutex_lock(&of_mutex); - if (of_kset) - rc = __of_node_add(np); - else - /* This scenario may be perfectly valid, but report it anyway */ - pr_info("of_node_add(%s) before of_init()\n", np->full_name); - mutex_unlock(&of_mutex); - return rc; -} - static int __init of_init(void) { struct device_node *np; @@ -204,7 +193,7 @@ static int __init of_init(void) return -ENOMEM; } for_each_of_allnodes(np) - __of_node_add(np); + __of_attach_node_sysfs(np); mutex_unlock(&of_mutex); /* Symlink in /proc as required by userspace ABI */ @@ -1689,15 +1678,17 @@ int of_add_property(struct device_node *np, struct property *prop) if (rc) return rc; + mutex_lock(&of_mutex); + raw_spin_lock_irqsave(&devtree_lock, flags); rc = __of_add_property(np, prop); raw_spin_unlock_irqrestore(&devtree_lock, flags); - if (rc) - return rc; - if (of_node_is_attached(np)) + if (!rc) __of_add_property_sysfs(np, prop); + mutex_unlock(&of_mutex); + return rc; } @@ -1720,6 +1711,13 @@ int __of_remove_property(struct device_node *np, struct property *prop) return 0; } +void __of_remove_property_sysfs(struct device_node *np, struct property *prop) +{ + /* at early boot, bail here and defer setup to of_init() */ + if (of_kset && of_node_is_attached(np)) + sysfs_remove_bin_file(&np->kobj, &prop->attr); +} + /** * of_remove_property - Remove a property from a node. * @@ -1737,20 +1735,18 @@ int of_remove_property(struct device_node *np, struct property *prop) if (rc) return rc; + mutex_lock(&of_mutex); + raw_spin_lock_irqsave(&devtree_lock, flags); rc = __of_remove_property(np, prop); raw_spin_unlock_irqrestore(&devtree_lock, flags); - if (rc) - return rc; - - /* at early boot, bail hear and defer setup to of_init() */ - if (!of_kset) - return 0; + if (!rc) + __of_remove_property_sysfs(np, prop); - sysfs_remove_bin_file(&np->kobj, &prop->attr); + mutex_unlock(&of_mutex); - return 0; + return rc; } int __of_update_property(struct device_node *np, struct property *newprop, @@ -1779,6 +1775,18 @@ int __of_update_property(struct device_node *np, struct property *newprop, return 0; } +void __of_update_property_sysfs(struct device_node *np, struct property *newprop, + struct property *oldprop) +{ + /* At early boot, bail out and defer setup to of_init() */ + if (!of_kset) + return; + + if (oldprop) + sysfs_remove_bin_file(&np->kobj, &oldprop->attr); + __of_add_property_sysfs(np, newprop); +} + /* * of_update_property - Update a property in a node, if the property does * not exist, add it. @@ -1801,22 +1809,18 @@ int of_update_property(struct device_node *np, struct property *newprop) if (rc) return rc; + mutex_lock(&of_mutex); + raw_spin_lock_irqsave(&devtree_lock, flags); rc = __of_update_property(np, newprop, &oldprop); raw_spin_unlock_irqrestore(&devtree_lock, flags); - if (rc) - return rc; - /* At early boot, bail out and defer setup to of_init() */ - if (!of_kset) - return 0; + if (!rc) + __of_update_property_sysfs(np, newprop, oldprop); - /* Update the sysfs attribute */ - if (oldprop) - sysfs_remove_bin_file(&np->kobj, &oldprop->attr); - __of_add_property_sysfs(np, newprop); + mutex_unlock(&of_mutex); - return 0; + return rc; } static void of_alias_add(struct alias_prop *ap, struct device_node *np, diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c index 75fcc66fcefd..c875787fa394 100644 --- a/drivers/of/dynamic.c +++ b/drivers/of/dynamic.c @@ -41,11 +41,13 @@ void of_node_put(struct device_node *node) } EXPORT_SYMBOL(of_node_put); -static void of_node_remove(struct device_node *np) +void __of_detach_node_sysfs(struct device_node *np) { struct property *pp; BUG_ON(!of_node_is_initialized(np)); + if (!of_kset) + return; /* only remove properties if on sysfs */ if (of_node_is_attached(np)) { @@ -115,11 +117,13 @@ int of_attach_node(struct device_node *np) if (rc) return rc; + mutex_lock(&of_mutex); raw_spin_lock_irqsave(&devtree_lock, flags); __of_attach_node(np); raw_spin_unlock_irqrestore(&devtree_lock, flags); - of_node_add(np); + __of_attach_node_sysfs(np); + mutex_unlock(&of_mutex); return 0; } @@ -174,11 +178,13 @@ int of_detach_node(struct device_node *np) if (rc) return rc; + mutex_lock(&of_mutex); raw_spin_lock_irqsave(&devtree_lock, flags); __of_detach_node(np); raw_spin_unlock_irqrestore(&devtree_lock, flags); - of_node_remove(np); + __of_detach_node_sysfs(np); + mutex_unlock(&of_mutex); return rc; } diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index 0f6089722af9..0d99ba8caeed 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -33,6 +33,8 @@ struct alias_prop { extern struct mutex of_mutex; extern struct list_head aliases_lookup; +extern struct kset *of_kset; + static inline struct device_node *kobj_to_device_node(struct kobject *kobj) { @@ -62,11 +64,19 @@ struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags); struct device_node *__of_node_alloc(const char *full_name, gfp_t allocflags); extern int __of_add_property(struct device_node *np, struct property *prop); +extern int __of_add_property_sysfs(struct device_node *np, + struct property *prop); extern int __of_remove_property(struct device_node *np, struct property *prop); +extern void __of_remove_property_sysfs(struct device_node *np, + struct property *prop); extern int __of_update_property(struct device_node *np, struct property *newprop, struct property **oldprop); +extern void __of_update_property_sysfs(struct device_node *np, + struct property *newprop, struct property *oldprop); extern void __of_attach_node(struct device_node *np); +extern int __of_attach_node_sysfs(struct device_node *np); extern void __of_detach_node(struct device_node *np); +extern void __of_detach_node_sysfs(struct device_node *np); #endif /* _LINUX_OF_PRIVATE_H */ -- cgit From 6162dbe49a451f96431a23b4821f05e3bd925bc1 Mon Sep 17 00:00:00 2001 From: Grant Likely Date: Wed, 16 Jul 2014 08:48:46 -0600 Subject: of: Make sure attached nodes don't carry along extra children The child pointer does not get cleared when attaching new nodes which could cause the tree to be inconsistent. Clear the child pointer in __of_attach_node() to be absolutely sure that the structure remains in a consistent layout. Signed-off-by: Grant Likely --- drivers/of/dynamic.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/of') diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c index c875787fa394..b96d83100987 100644 --- a/drivers/of/dynamic.c +++ b/drivers/of/dynamic.c @@ -98,6 +98,7 @@ int of_property_notify(int action, struct device_node *np, void __of_attach_node(struct device_node *np) { + np->child = NULL; np->sibling = np->parent->child; np->allnext = np->parent->allnext; np->parent->allnext = np; -- cgit From a25095d451ece23b1fef34474f3230100db7aa05 Mon Sep 17 00:00:00 2001 From: Grant Likely Date: Tue, 15 Jul 2014 23:25:43 -0600 Subject: of: Move dynamic node fixups out of powerpc and into common code PowerPC does an odd thing with dynamic nodes. It uses a notifier to catch new node additions and set some of the values like name and type. This makes no sense since that same code can be put directly into of_attach_node(). Besides, all dynamic node users need this, not just powerpc. Fix this problem by moving the logic out of arch/powerpc and into drivers/of/dynamic.c. It is also important to remove this notifier because we want to move the firing of notifiers from before the tree is modified to after so that the receiver gets a consistent view of the tree, but that is incompatible with notifiers that modify the node. Signed-off-by: Grant Likely Cc: Nathan Fontenot Cc: Benjamin Herrenschmidt --- drivers/of/base.c | 4 ++-- drivers/of/dynamic.c | 13 +++++++++++++ drivers/of/of_private.h | 2 ++ 3 files changed, 17 insertions(+), 2 deletions(-) (limited to 'drivers/of') diff --git a/drivers/of/base.c b/drivers/of/base.c index ad4929cbd876..ededf8e33145 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -266,8 +266,8 @@ EXPORT_SYMBOL(of_find_all_nodes); * Find a property with a given name for a given node * and return the value. */ -static const void *__of_get_property(const struct device_node *np, - const char *name, int *lenp) +const void *__of_get_property(const struct device_node *np, + const char *name, int *lenp) { struct property *pp = __of_find_property(np, name, lenp); diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c index b96d83100987..7c020b9a3317 100644 --- a/drivers/of/dynamic.c +++ b/drivers/of/dynamic.c @@ -98,6 +98,19 @@ int of_property_notify(int action, struct device_node *np, void __of_attach_node(struct device_node *np) { + const __be32 *phandle; + int sz; + + np->name = __of_get_property(np, "name", NULL) ? : ""; + np->type = __of_get_property(np, "device_type", NULL) ? : ""; + + phandle = __of_get_property(np, "phandle", &sz); + if (!phandle) + phandle = __of_get_property(np, "linux,phandle", &sz); + if (IS_ENABLED(PPC_PSERIES) && !phandle) + phandle = __of_get_property(np, "ibm,phandle", &sz); + np->phandle = (phandle && (sz >= 4)) ? be32_to_cpup(phandle) : 0; + np->child = NULL; np->sibling = np->parent->child; np->allnext = np->parent->allnext; diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index 0d99ba8caeed..8129c0e58d70 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -63,6 +63,8 @@ static inline int of_property_notify(int action, struct device_node *np, struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags); struct device_node *__of_node_alloc(const char *full_name, gfp_t allocflags); +extern const void *__of_get_property(const struct device_node *np, + const char *name, int *lenp); extern int __of_add_property(struct device_node *np, struct property *prop); extern int __of_add_property_sysfs(struct device_node *np, struct property *prop); -- cgit From 259092a35c7e11f1d4616b0f5b3ba7b851fe4fa6 Mon Sep 17 00:00:00 2001 From: Grant Likely Date: Wed, 16 Jul 2014 12:48:23 -0600 Subject: of: Reorder device tree changes and notifiers Currently, devicetree reconfig notifiers get emitted before the change is applied to the tree, but that behaviour is problematic if the receiver wants the determine the new state of the tree. The current users don't care, but the changeset code to follow will be making multiple changes at once. Reorder notifiers to get emitted after the change has been applied to the tree so that callbacks see the new tree state. At the same time, fixup the existing callbacks to expect the new order. There are a few callbacks that compare the old and new values of a changed property. Put both property pointers into the of_prop_reconfig structure. The current notifiers also allow the notifier callback to fail and cancel the change to the tree, but that feature isn't actually used. It really isn't valid to ignore a tree modification provided by firmware anyway, so remove the ability to cancel a change to the tree. Signed-off-by: Grant Likely Cc: Nathan Fontenot --- drivers/of/base.c | 21 +++++++++------------ drivers/of/dynamic.c | 18 ++++++++---------- drivers/of/of_private.h | 4 ++-- 3 files changed, 19 insertions(+), 24 deletions(-) (limited to 'drivers/of') diff --git a/drivers/of/base.c b/drivers/of/base.c index ededf8e33145..a7ad1013edfa 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -1674,10 +1674,6 @@ int of_add_property(struct device_node *np, struct property *prop) unsigned long flags; int rc; - rc = of_property_notify(OF_RECONFIG_ADD_PROPERTY, np, prop); - if (rc) - return rc; - mutex_lock(&of_mutex); raw_spin_lock_irqsave(&devtree_lock, flags); @@ -1689,6 +1685,9 @@ int of_add_property(struct device_node *np, struct property *prop) mutex_unlock(&of_mutex); + if (!rc) + of_property_notify(OF_RECONFIG_ADD_PROPERTY, np, prop, NULL); + return rc; } @@ -1731,10 +1730,6 @@ int of_remove_property(struct device_node *np, struct property *prop) unsigned long flags; int rc; - rc = of_property_notify(OF_RECONFIG_REMOVE_PROPERTY, np, prop); - if (rc) - return rc; - mutex_lock(&of_mutex); raw_spin_lock_irqsave(&devtree_lock, flags); @@ -1746,6 +1741,9 @@ int of_remove_property(struct device_node *np, struct property *prop) mutex_unlock(&of_mutex); + if (!rc) + of_property_notify(OF_RECONFIG_REMOVE_PROPERTY, np, prop, NULL); + return rc; } @@ -1805,10 +1803,6 @@ int of_update_property(struct device_node *np, struct property *newprop) if (!newprop->name) return -EINVAL; - rc = of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop); - if (rc) - return rc; - mutex_lock(&of_mutex); raw_spin_lock_irqsave(&devtree_lock, flags); @@ -1820,6 +1814,9 @@ int of_update_property(struct device_node *np, struct property *newprop) mutex_unlock(&of_mutex); + if (!rc) + of_property_notify(OF_RECONFIG_UPDATE_PROPERTY, np, newprop, oldprop); + return rc; } diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c index 7c020b9a3317..7bd5501736a6 100644 --- a/drivers/of/dynamic.c +++ b/drivers/of/dynamic.c @@ -83,7 +83,7 @@ int of_reconfig_notify(unsigned long action, void *p) } int of_property_notify(int action, struct device_node *np, - struct property *prop) + struct property *prop, struct property *oldprop) { struct of_prop_reconfig pr; @@ -93,6 +93,7 @@ int of_property_notify(int action, struct device_node *np, pr.dn = np; pr.prop = prop; + pr.old_prop = oldprop; return of_reconfig_notify(action, &pr); } @@ -125,11 +126,6 @@ void __of_attach_node(struct device_node *np) int of_attach_node(struct device_node *np) { unsigned long flags; - int rc; - - rc = of_reconfig_notify(OF_RECONFIG_ATTACH_NODE, np); - if (rc) - return rc; mutex_lock(&of_mutex); raw_spin_lock_irqsave(&devtree_lock, flags); @@ -138,6 +134,9 @@ int of_attach_node(struct device_node *np) __of_attach_node_sysfs(np); mutex_unlock(&of_mutex); + + of_reconfig_notify(OF_RECONFIG_ATTACH_NODE, np); + return 0; } @@ -188,10 +187,6 @@ int of_detach_node(struct device_node *np) unsigned long flags; int rc = 0; - rc = of_reconfig_notify(OF_RECONFIG_DETACH_NODE, np); - if (rc) - return rc; - mutex_lock(&of_mutex); raw_spin_lock_irqsave(&devtree_lock, flags); __of_detach_node(np); @@ -199,6 +194,9 @@ int of_detach_node(struct device_node *np) __of_detach_node_sysfs(np); mutex_unlock(&of_mutex); + + of_reconfig_notify(OF_RECONFIG_DETACH_NODE, np); + return rc; } diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index 8129c0e58d70..f69ccb1fa308 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -43,11 +43,11 @@ static inline struct device_node *kobj_to_device_node(struct kobject *kobj) #if defined(CONFIG_OF_DYNAMIC) extern int of_property_notify(int action, struct device_node *np, - struct property *prop); + struct property *prop, struct property *old_prop); extern void of_node_release(struct kobject *kobj); #else /* CONFIG_OF_DYNAMIC */ static inline int of_property_notify(int action, struct device_node *np, - struct property *prop) + struct property *prop, struct property *old_prop) { return 0; } -- cgit From 201c910bd6898d81d4ac6685d0f421b7e10f3c5d Mon Sep 17 00:00:00 2001 From: Pantelis Antoniou Date: Fri, 4 Jul 2014 19:58:49 +0300 Subject: of: Transactional DT support. Introducing DT transactional support. A DT transaction is a method which allows one to apply changes in the live tree, in such a way that either the full set of changes take effect, or the state of the tree can be rolled-back to the state it was before it was attempted. An applied transaction can be rolled-back at any time. Documentation is in Documentation/devicetree/changesets.txt Signed-off-by: Pantelis Antoniou [glikely: Removed device notifiers and reworked to be more consistent] Signed-off-by: Grant Likely --- drivers/of/dynamic.c | 344 ++++++++++++++++++++++++++++++++ drivers/of/of_private.h | 9 + drivers/of/selftest.c | 51 +++++ drivers/of/testcase-data/testcases.dtsi | 10 + 4 files changed, 414 insertions(+) (limited to 'drivers/of') diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c index 7bd5501736a6..c1002b7be786 100644 --- a/drivers/of/dynamic.c +++ b/drivers/of/dynamic.c @@ -314,3 +314,347 @@ struct device_node *__of_node_alloc(const char *full_name, gfp_t allocflags) kfree(node); return NULL; } + +static void __of_changeset_entry_destroy(struct of_changeset_entry *ce) +{ + of_node_put(ce->np); + list_del(&ce->node); + kfree(ce); +} + +#ifdef DEBUG +static void __of_changeset_entry_dump(struct of_changeset_entry *ce) +{ + switch (ce->action) { + case OF_RECONFIG_ADD_PROPERTY: + pr_debug("%p: %s %s/%s\n", + ce, "ADD_PROPERTY ", ce->np->full_name, + ce->prop->name); + break; + case OF_RECONFIG_REMOVE_PROPERTY: + pr_debug("%p: %s %s/%s\n", + ce, "REMOVE_PROPERTY", ce->np->full_name, + ce->prop->name); + break; + case OF_RECONFIG_UPDATE_PROPERTY: + pr_debug("%p: %s %s/%s\n", + ce, "UPDATE_PROPERTY", ce->np->full_name, + ce->prop->name); + break; + case OF_RECONFIG_ATTACH_NODE: + pr_debug("%p: %s %s\n", + ce, "ATTACH_NODE ", ce->np->full_name); + break; + case OF_RECONFIG_DETACH_NODE: + pr_debug("%p: %s %s\n", + ce, "DETACH_NODE ", ce->np->full_name); + break; + } +} +#else +static inline void __of_changeset_entry_dump(struct of_changeset_entry *ce) +{ + /* empty */ +} +#endif + +static void __of_changeset_entry_invert(struct of_changeset_entry *ce, + struct of_changeset_entry *rce) +{ + memcpy(rce, ce, sizeof(*rce)); + + switch (ce->action) { + case OF_RECONFIG_ATTACH_NODE: + rce->action = OF_RECONFIG_DETACH_NODE; + break; + case OF_RECONFIG_DETACH_NODE: + rce->action = OF_RECONFIG_ATTACH_NODE; + break; + case OF_RECONFIG_ADD_PROPERTY: + rce->action = OF_RECONFIG_REMOVE_PROPERTY; + break; + case OF_RECONFIG_REMOVE_PROPERTY: + rce->action = OF_RECONFIG_ADD_PROPERTY; + break; + case OF_RECONFIG_UPDATE_PROPERTY: + rce->old_prop = ce->prop; + rce->prop = ce->old_prop; + break; + } +} + +static void __of_changeset_entry_notify(struct of_changeset_entry *ce, bool revert) +{ + struct of_changeset_entry ce_inverted; + int ret; + + if (revert) { + __of_changeset_entry_invert(ce, &ce_inverted); + ce = &ce_inverted; + } + + switch (ce->action) { + case OF_RECONFIG_ATTACH_NODE: + case OF_RECONFIG_DETACH_NODE: + ret = of_reconfig_notify(ce->action, ce->np); + break; + case OF_RECONFIG_ADD_PROPERTY: + case OF_RECONFIG_REMOVE_PROPERTY: + case OF_RECONFIG_UPDATE_PROPERTY: + ret = of_property_notify(ce->action, ce->np, ce->prop, ce->old_prop); + break; + default: + pr_err("%s: invalid devicetree changeset action: %i\n", __func__, + (int)ce->action); + return; + } + + if (ret) + pr_err("%s: notifier error @%s\n", __func__, ce->np->full_name); +} + +static int __of_changeset_entry_apply(struct of_changeset_entry *ce) +{ + struct property *old_prop, **propp; + unsigned long flags; + int ret = 0; + + __of_changeset_entry_dump(ce); + + raw_spin_lock_irqsave(&devtree_lock, flags); + switch (ce->action) { + case OF_RECONFIG_ATTACH_NODE: + __of_attach_node(ce->np); + break; + case OF_RECONFIG_DETACH_NODE: + __of_detach_node(ce->np); + break; + case OF_RECONFIG_ADD_PROPERTY: + /* If the property is in deadprops then it must be removed */ + for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) { + if (*propp == ce->prop) { + *propp = ce->prop->next; + ce->prop->next = NULL; + break; + } + } + + ret = __of_add_property(ce->np, ce->prop); + if (ret) { + pr_err("%s: add_property failed @%s/%s\n", + __func__, ce->np->full_name, + ce->prop->name); + break; + } + break; + case OF_RECONFIG_REMOVE_PROPERTY: + ret = __of_remove_property(ce->np, ce->prop); + if (ret) { + pr_err("%s: remove_property failed @%s/%s\n", + __func__, ce->np->full_name, + ce->prop->name); + break; + } + break; + + case OF_RECONFIG_UPDATE_PROPERTY: + /* If the property is in deadprops then it must be removed */ + for (propp = &ce->np->deadprops; *propp; propp = &(*propp)->next) { + if (*propp == ce->prop) { + *propp = ce->prop->next; + ce->prop->next = NULL; + break; + } + } + + ret = __of_update_property(ce->np, ce->prop, &old_prop); + if (ret) { + pr_err("%s: update_property failed @%s/%s\n", + __func__, ce->np->full_name, + ce->prop->name); + break; + } + break; + default: + ret = -EINVAL; + } + raw_spin_unlock_irqrestore(&devtree_lock, flags); + + if (ret) + return ret; + + switch (ce->action) { + case OF_RECONFIG_ATTACH_NODE: + __of_attach_node_sysfs(ce->np); + break; + case OF_RECONFIG_DETACH_NODE: + __of_detach_node_sysfs(ce->np); + break; + case OF_RECONFIG_ADD_PROPERTY: + /* ignore duplicate names */ + __of_add_property_sysfs(ce->np, ce->prop); + break; + case OF_RECONFIG_REMOVE_PROPERTY: + __of_remove_property_sysfs(ce->np, ce->prop); + break; + case OF_RECONFIG_UPDATE_PROPERTY: + __of_update_property_sysfs(ce->np, ce->prop, ce->old_prop); + break; + } + + return 0; +} + +static inline int __of_changeset_entry_revert(struct of_changeset_entry *ce) +{ + struct of_changeset_entry ce_inverted; + + __of_changeset_entry_invert(ce, &ce_inverted); + return __of_changeset_entry_apply(&ce_inverted); +} + +/** + * of_changeset_init - Initialize a changeset for use + * + * @ocs: changeset pointer + * + * Initialize a changeset structure + */ +void of_changeset_init(struct of_changeset *ocs) +{ + memset(ocs, 0, sizeof(*ocs)); + INIT_LIST_HEAD(&ocs->entries); +} + +/** + * of_changeset_destroy - Destroy a changeset + * + * @ocs: changeset pointer + * + * Destroys a changeset. Note that if a changeset is applied, + * its changes to the tree cannot be reverted. + */ +void of_changeset_destroy(struct of_changeset *ocs) +{ + struct of_changeset_entry *ce, *cen; + + list_for_each_entry_safe_reverse(ce, cen, &ocs->entries, node) + __of_changeset_entry_destroy(ce); +} + +/** + * of_changeset_apply - Applies a changeset + * + * @ocs: changeset pointer + * + * Applies a changeset to the live tree. + * Any side-effects of live tree state changes are applied here on + * sucess, like creation/destruction of devices and side-effects + * like creation of sysfs properties and directories. + * Returns 0 on success, a negative error value in case of an error. + * On error the partially applied effects are reverted. + */ +int of_changeset_apply(struct of_changeset *ocs) +{ + struct of_changeset_entry *ce; + int ret; + + /* perform the rest of the work */ + pr_debug("of_changeset: applying...\n"); + list_for_each_entry(ce, &ocs->entries, node) { + ret = __of_changeset_entry_apply(ce); + if (ret) { + pr_err("%s: Error applying changeset (%d)\n", __func__, ret); + list_for_each_entry_continue_reverse(ce, &ocs->entries, node) + __of_changeset_entry_revert(ce); + return ret; + } + } + pr_debug("of_changeset: applied, emitting notifiers.\n"); + + /* drop the global lock while emitting notifiers */ + mutex_unlock(&of_mutex); + list_for_each_entry(ce, &ocs->entries, node) + __of_changeset_entry_notify(ce, 0); + mutex_lock(&of_mutex); + pr_debug("of_changeset: notifiers sent.\n"); + + return 0; +} + +/** + * of_changeset_revert - Reverts an applied changeset + * + * @ocs: changeset pointer + * + * Reverts a changeset returning the state of the tree to what it + * was before the application. + * Any side-effects like creation/destruction of devices and + * removal of sysfs properties and directories are applied. + * Returns 0 on success, a negative error value in case of an error. + */ +int of_changeset_revert(struct of_changeset *ocs) +{ + struct of_changeset_entry *ce; + int ret; + + pr_debug("of_changeset: reverting...\n"); + list_for_each_entry_reverse(ce, &ocs->entries, node) { + ret = __of_changeset_entry_revert(ce); + if (ret) { + pr_err("%s: Error reverting changeset (%d)\n", __func__, ret); + list_for_each_entry_continue(ce, &ocs->entries, node) + __of_changeset_entry_apply(ce); + return ret; + } + } + pr_debug("of_changeset: reverted, emitting notifiers.\n"); + + /* drop the global lock while emitting notifiers */ + mutex_unlock(&of_mutex); + list_for_each_entry_reverse(ce, &ocs->entries, node) + __of_changeset_entry_notify(ce, 1); + mutex_lock(&of_mutex); + pr_debug("of_changeset: notifiers sent.\n"); + + return 0; +} + +/** + * of_changeset_action - Perform a changeset action + * + * @ocs: changeset pointer + * @action: action to perform + * @np: Pointer to device node + * @prop: Pointer to property + * + * On action being one of: + * + OF_RECONFIG_ATTACH_NODE + * + OF_RECONFIG_DETACH_NODE, + * + OF_RECONFIG_ADD_PROPERTY + * + OF_RECONFIG_REMOVE_PROPERTY, + * + OF_RECONFIG_UPDATE_PROPERTY + * Returns 0 on success, a negative error value in case of an error. + */ +int of_changeset_action(struct of_changeset *ocs, unsigned long action, + struct device_node *np, struct property *prop) +{ + struct of_changeset_entry *ce; + + ce = kzalloc(sizeof(*ce), GFP_KERNEL); + if (!ce) { + pr_err("%s: Failed to allocate\n", __func__); + return -ENOMEM; + } + /* get a reference to the node */ + ce->action = action; + ce->np = of_node_get(np); + ce->prop = prop; + + if (action == OF_RECONFIG_UPDATE_PROPERTY && prop) + ce->old_prop = of_find_property(np, prop->name, NULL); + + /* add it to the list */ + list_add_tail(&ce->node, &ocs->entries); + return 0; +} diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h index f69ccb1fa308..858e0a5d9a11 100644 --- a/drivers/of/of_private.h +++ b/drivers/of/of_private.h @@ -81,4 +81,13 @@ extern int __of_attach_node_sysfs(struct device_node *np); extern void __of_detach_node(struct device_node *np); extern void __of_detach_node_sysfs(struct device_node *np); +/* iterators for transactions, used for overlays */ +/* forward iterator */ +#define for_each_transaction_entry(_oft, _te) \ + list_for_each_entry(_te, &(_oft)->te_list, node) + +/* reverse iterator */ +#define for_each_transaction_entry_reverse(_oft, _te) \ + list_for_each_entry_reverse(_te, &(_oft)->te_list, node) + #endif /* _LINUX_OF_PRIVATE_H */ diff --git a/drivers/of/selftest.c b/drivers/of/selftest.c index ee2166f0f36a..04e39a183e53 100644 --- a/drivers/of/selftest.c +++ b/drivers/of/selftest.c @@ -293,6 +293,56 @@ static void __init of_selftest_property_copy(void) #endif } +static void __init of_selftest_changeset(void) +{ +#ifdef CONFIG_OF_DYNAMIC + struct property *ppadd, padd = { .name = "prop-add", .length = 0, .value = "" }; + struct property *ppupdate, pupdate = { .name = "prop-update", .length = 5, .value = "abcd" }; + struct property *ppremove; + struct device_node *n1, *n2, *n21, *nremove, *parent; + struct of_changeset chgset; + + of_changeset_init(&chgset); + n1 = __of_node_alloc("/testcase-data/changeset/n1", GFP_KERNEL); + selftest(n1, "testcase setup failure\n"); + n2 = __of_node_alloc("/testcase-data/changeset/n2", GFP_KERNEL); + selftest(n2, "testcase setup failure\n"); + n21 = __of_node_alloc("/testcase-data/changeset/n2/n21", GFP_KERNEL); + selftest(n21, "testcase setup failure %p\n", n21); + nremove = of_find_node_by_path("/testcase-data/changeset/node-remove"); + selftest(nremove, "testcase setup failure\n"); + ppadd = __of_prop_dup(&padd, GFP_KERNEL); + selftest(ppadd, "testcase setup failure\n"); + ppupdate = __of_prop_dup(&pupdate, GFP_KERNEL); + selftest(ppupdate, "testcase setup failure\n"); + parent = nremove->parent; + n1->parent = parent; + n2->parent = parent; + n21->parent = n2; + n2->child = n21; + ppremove = of_find_property(parent, "prop-remove", NULL); + selftest(ppremove, "failed to find removal prop"); + + of_changeset_init(&chgset); + selftest(!of_changeset_attach_node(&chgset, n1), "fail attach n1\n"); + selftest(!of_changeset_attach_node(&chgset, n2), "fail attach n2\n"); + selftest(!of_changeset_detach_node(&chgset, nremove), "fail remove node\n"); + selftest(!of_changeset_attach_node(&chgset, n21), "fail attach n21\n"); + selftest(!of_changeset_add_property(&chgset, parent, ppadd), "fail add prop\n"); + selftest(!of_changeset_update_property(&chgset, parent, ppupdate), "fail update prop\n"); + selftest(!of_changeset_remove_property(&chgset, parent, ppremove), "fail remove prop\n"); + mutex_lock(&of_mutex); + selftest(!of_changeset_apply(&chgset), "apply failed\n"); + mutex_unlock(&of_mutex); + + mutex_lock(&of_mutex); + selftest(!of_changeset_revert(&chgset), "revert failed\n"); + mutex_unlock(&of_mutex); + + of_changeset_destroy(&chgset); +#endif +} + static void __init of_selftest_parse_interrupts(void) { struct device_node *np; @@ -561,6 +611,7 @@ static int __init of_selftest(void) of_selftest_parse_phandle_with_args(); of_selftest_property_match_string(); of_selftest_property_copy(); + of_selftest_changeset(); of_selftest_parse_interrupts(); of_selftest_parse_interrupts_extended(); of_selftest_match_node(); diff --git a/drivers/of/testcase-data/testcases.dtsi b/drivers/of/testcase-data/testcases.dtsi index 6d8d980ac858..669bb07df142 100644 --- a/drivers/of/testcase-data/testcases.dtsi +++ b/drivers/of/testcase-data/testcases.dtsi @@ -1,3 +1,13 @@ +/ { + testcase-data { + changeset { + prop-update = "hello"; + prop-remove = "world"; + node-remove { + }; + }; + }; +}; #include "tests-phandle.dtsi" #include "tests-interrupts.dtsi" #include "tests-match.dtsi" -- cgit From b6ae5dc54b0a5c542d06d46b9083ceb70bf7e083 Mon Sep 17 00:00:00 2001 From: Grant Likely Date: Sat, 26 Jul 2014 10:58:43 -0600 Subject: of: typo fix in __of_prop_dup() Fix a trivial typo in a comment block. Signed-off-by: Grant Likely --- drivers/of/dynamic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/of') diff --git a/drivers/of/dynamic.c b/drivers/of/dynamic.c index c1002b7be786..54fecc49a1fe 100644 --- a/drivers/of/dynamic.c +++ b/drivers/of/dynamic.c @@ -259,7 +259,7 @@ struct property *__of_prop_dup(const struct property *prop, gfp_t allocflags) /* * NOTE: There is no check for zero length value. - * In case of a boolean property This will allocate a value + * In case of a boolean property, this will allocate a value * of zero bytes. We do this to work around the use * of of_get_property() calls on boolean values. */ -- cgit