1 // SPDX-License-Identifier: GPL-2.0
3 * drivers/base/core.c - core driver model code (device registration, etc)
5 * Copyright (c) 2002-3 Patrick Mochel
6 * Copyright (c) 2002-3 Open Source Development Labs
7 * Copyright (c) 2006 Greg Kroah-Hartman <gregkh@suse.de>
8 * Copyright (c) 2006 Novell, Inc.
11 #include <linux/acpi.h>
12 #include <linux/cpufreq.h>
13 #include <linux/device.h>
14 #include <linux/err.h>
15 #include <linux/fwnode.h>
16 #include <linux/init.h>
17 #include <linux/module.h>
18 #include <linux/slab.h>
19 #include <linux/string.h>
20 #include <linux/kdev_t.h>
21 #include <linux/notifier.h>
23 #include <linux/of_device.h>
24 #include <linux/genhd.h>
25 #include <linux/mutex.h>
26 #include <linux/pm_runtime.h>
27 #include <linux/netdevice.h>
28 #include <linux/sched/signal.h>
29 #include <linux/sched/mm.h>
30 #include <linux/sysfs.h>
33 #include "power/power.h"
35 #ifdef CONFIG_SYSFS_DEPRECATED
36 #ifdef CONFIG_SYSFS_DEPRECATED_V2
37 long sysfs_deprecated = 1;
39 long sysfs_deprecated = 0;
41 static int __init sysfs_deprecated_setup(char *arg)
43 return kstrtol(arg, 10, &sysfs_deprecated);
45 early_param("sysfs.deprecated", sysfs_deprecated_setup);
48 /* Device links support. */
49 static LIST_HEAD(wait_for_suppliers);
50 static DEFINE_MUTEX(wfs_lock);
51 static LIST_HEAD(deferred_sync);
52 static unsigned int defer_sync_state_count = 1;
53 static unsigned int defer_fw_devlink_count;
54 static LIST_HEAD(deferred_fw_devlink);
55 static DEFINE_MUTEX(defer_fw_devlink_lock);
56 static bool fw_devlink_is_permissive(void);
59 static DEFINE_MUTEX(device_links_lock);
60 DEFINE_STATIC_SRCU(device_links_srcu);
62 static inline void device_links_write_lock(void)
64 mutex_lock(&device_links_lock);
67 static inline void device_links_write_unlock(void)
69 mutex_unlock(&device_links_lock);
72 int device_links_read_lock(void) __acquires(&device_links_srcu)
74 return srcu_read_lock(&device_links_srcu);
77 void device_links_read_unlock(int idx) __releases(&device_links_srcu)
79 srcu_read_unlock(&device_links_srcu, idx);
82 int device_links_read_lock_held(void)
84 return srcu_read_lock_held(&device_links_srcu);
86 #else /* !CONFIG_SRCU */
87 static DECLARE_RWSEM(device_links_lock);
89 static inline void device_links_write_lock(void)
91 down_write(&device_links_lock);
94 static inline void device_links_write_unlock(void)
96 up_write(&device_links_lock);
99 int device_links_read_lock(void)
101 down_read(&device_links_lock);
105 void device_links_read_unlock(int not_used)
107 up_read(&device_links_lock);
110 #ifdef CONFIG_DEBUG_LOCK_ALLOC
111 int device_links_read_lock_held(void)
113 return lockdep_is_held(&device_links_lock);
116 #endif /* !CONFIG_SRCU */
119 * device_is_dependent - Check if one device depends on another one
120 * @dev: Device to check dependencies for.
121 * @target: Device to check against.
123 * Check if @target depends on @dev or any device dependent on it (its child or
124 * its consumer etc). Return 1 if that is the case or 0 otherwise.
126 int device_is_dependent(struct device *dev, void *target)
128 struct device_link *link;
134 ret = device_for_each_child(dev, target, device_is_dependent);
138 list_for_each_entry(link, &dev->links.consumers, s_node) {
139 if (link->flags == (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED))
142 if (link->consumer == target)
145 ret = device_is_dependent(link->consumer, target);
152 static void device_link_init_status(struct device_link *link,
153 struct device *consumer,
154 struct device *supplier)
156 switch (supplier->links.status) {
158 switch (consumer->links.status) {
161 * A consumer driver can create a link to a supplier
162 * that has not completed its probing yet as long as it
163 * knows that the supplier is already functional (for
164 * example, it has just acquired some resources from the
167 link->status = DL_STATE_CONSUMER_PROBE;
170 link->status = DL_STATE_DORMANT;
174 case DL_DEV_DRIVER_BOUND:
175 switch (consumer->links.status) {
177 link->status = DL_STATE_CONSUMER_PROBE;
179 case DL_DEV_DRIVER_BOUND:
180 link->status = DL_STATE_ACTIVE;
183 link->status = DL_STATE_AVAILABLE;
187 case DL_DEV_UNBINDING:
188 link->status = DL_STATE_SUPPLIER_UNBIND;
191 link->status = DL_STATE_DORMANT;
196 static int device_reorder_to_tail(struct device *dev, void *not_used)
198 struct device_link *link;
201 * Devices that have not been registered yet will be put to the ends
202 * of the lists during the registration, so skip them here.
204 if (device_is_registered(dev))
205 devices_kset_move_last(dev);
207 if (device_pm_initialized(dev))
208 device_pm_move_last(dev);
210 device_for_each_child(dev, NULL, device_reorder_to_tail);
211 list_for_each_entry(link, &dev->links.consumers, s_node) {
212 if (link->flags == (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED))
214 device_reorder_to_tail(link->consumer, NULL);
221 * device_pm_move_to_tail - Move set of devices to the end of device lists
222 * @dev: Device to move
224 * This is a device_reorder_to_tail() wrapper taking the requisite locks.
226 * It moves the @dev along with all of its children and all of its consumers
227 * to the ends of the device_kset and dpm_list, recursively.
229 void device_pm_move_to_tail(struct device *dev)
233 idx = device_links_read_lock();
235 device_reorder_to_tail(dev, NULL);
237 device_links_read_unlock(idx);
240 #define to_devlink(dev) container_of((dev), struct device_link, link_dev)
242 static ssize_t status_show(struct device *dev,
243 struct device_attribute *attr, char *buf)
247 switch (to_devlink(dev)->status) {
249 output = "not tracked";
251 case DL_STATE_DORMANT:
254 case DL_STATE_AVAILABLE:
255 output = "available";
257 case DL_STATE_CONSUMER_PROBE:
258 output = "consumer probing";
260 case DL_STATE_ACTIVE:
263 case DL_STATE_SUPPLIER_UNBIND:
264 output = "supplier unbinding";
271 return sysfs_emit(buf, "%s\n", output);
273 static DEVICE_ATTR_RO(status);
275 static ssize_t auto_remove_on_show(struct device *dev,
276 struct device_attribute *attr, char *buf)
278 struct device_link *link = to_devlink(dev);
281 if (link->flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
282 output = "supplier unbind";
283 else if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER)
284 output = "consumer unbind";
288 return sysfs_emit(buf, "%s\n", output);
290 static DEVICE_ATTR_RO(auto_remove_on);
292 static ssize_t runtime_pm_show(struct device *dev,
293 struct device_attribute *attr, char *buf)
295 struct device_link *link = to_devlink(dev);
297 return sysfs_emit(buf, "%d\n", !!(link->flags & DL_FLAG_PM_RUNTIME));
299 static DEVICE_ATTR_RO(runtime_pm);
301 static ssize_t sync_state_only_show(struct device *dev,
302 struct device_attribute *attr, char *buf)
304 struct device_link *link = to_devlink(dev);
306 return sysfs_emit(buf, "%d\n",
307 !!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
309 static DEVICE_ATTR_RO(sync_state_only);
311 static struct attribute *devlink_attrs[] = {
312 &dev_attr_status.attr,
313 &dev_attr_auto_remove_on.attr,
314 &dev_attr_runtime_pm.attr,
315 &dev_attr_sync_state_only.attr,
318 ATTRIBUTE_GROUPS(devlink);
320 static void device_link_free(struct device_link *link)
322 while (refcount_dec_not_one(&link->rpm_active))
323 pm_runtime_put(link->supplier);
325 put_device(link->consumer);
326 put_device(link->supplier);
331 static void __device_link_free_srcu(struct rcu_head *rhead)
333 device_link_free(container_of(rhead, struct device_link, rcu_head));
336 static void devlink_dev_release(struct device *dev)
338 struct device_link *link = to_devlink(dev);
340 call_srcu(&device_links_srcu, &link->rcu_head, __device_link_free_srcu);
343 static void devlink_dev_release(struct device *dev)
345 device_link_free(to_devlink(dev));
349 static struct class devlink_class = {
351 .owner = THIS_MODULE,
352 .dev_groups = devlink_groups,
353 .dev_release = devlink_dev_release,
356 static int devlink_add_symlinks(struct device *dev,
357 struct class_interface *class_intf)
361 struct device_link *link = to_devlink(dev);
362 struct device *sup = link->supplier;
363 struct device *con = link->consumer;
366 len = max(strlen(dev_name(sup)), strlen(dev_name(con)));
367 len += strlen("supplier:") + 1;
368 buf = kzalloc(len, GFP_KERNEL);
372 ret = sysfs_create_link(&link->link_dev.kobj, &sup->kobj, "supplier");
376 ret = sysfs_create_link(&link->link_dev.kobj, &con->kobj, "consumer");
380 snprintf(buf, len, "consumer:%s", dev_name(con));
381 ret = sysfs_create_link(&sup->kobj, &link->link_dev.kobj, buf);
385 snprintf(buf, len, "supplier:%s", dev_name(sup));
386 ret = sysfs_create_link(&con->kobj, &link->link_dev.kobj, buf);
393 snprintf(buf, len, "consumer:%s", dev_name(con));
394 sysfs_remove_link(&sup->kobj, buf);
396 sysfs_remove_link(&link->link_dev.kobj, "consumer");
398 sysfs_remove_link(&link->link_dev.kobj, "supplier");
404 static void devlink_remove_symlinks(struct device *dev,
405 struct class_interface *class_intf)
407 struct device_link *link = to_devlink(dev);
409 struct device *sup = link->supplier;
410 struct device *con = link->consumer;
413 sysfs_remove_link(&link->link_dev.kobj, "consumer");
414 sysfs_remove_link(&link->link_dev.kobj, "supplier");
416 len = max(strlen(dev_name(sup)), strlen(dev_name(con)));
417 len += strlen("supplier:") + 1;
418 buf = kzalloc(len, GFP_KERNEL);
420 WARN(1, "Unable to properly free device link symlinks!\n");
424 snprintf(buf, len, "supplier:%s", dev_name(sup));
425 sysfs_remove_link(&con->kobj, buf);
426 snprintf(buf, len, "consumer:%s", dev_name(con));
427 sysfs_remove_link(&sup->kobj, buf);
431 static struct class_interface devlink_class_intf = {
432 .class = &devlink_class,
433 .add_dev = devlink_add_symlinks,
434 .remove_dev = devlink_remove_symlinks,
437 static int __init devlink_class_init(void)
441 ret = class_register(&devlink_class);
445 ret = class_interface_register(&devlink_class_intf);
447 class_unregister(&devlink_class);
451 postcore_initcall(devlink_class_init);
453 #define DL_MANAGED_LINK_FLAGS (DL_FLAG_AUTOREMOVE_CONSUMER | \
454 DL_FLAG_AUTOREMOVE_SUPPLIER | \
455 DL_FLAG_AUTOPROBE_CONSUMER | \
456 DL_FLAG_SYNC_STATE_ONLY)
458 #define DL_ADD_VALID_FLAGS (DL_MANAGED_LINK_FLAGS | DL_FLAG_STATELESS | \
459 DL_FLAG_PM_RUNTIME | DL_FLAG_RPM_ACTIVE)
462 * device_link_add - Create a link between two devices.
463 * @consumer: Consumer end of the link.
464 * @supplier: Supplier end of the link.
465 * @flags: Link flags.
467 * The caller is responsible for the proper synchronization of the link creation
468 * with runtime PM. First, setting the DL_FLAG_PM_RUNTIME flag will cause the
469 * runtime PM framework to take the link into account. Second, if the
470 * DL_FLAG_RPM_ACTIVE flag is set in addition to it, the supplier devices will
471 * be forced into the active metastate and reference-counted upon the creation
472 * of the link. If DL_FLAG_PM_RUNTIME is not set, DL_FLAG_RPM_ACTIVE will be
475 * If DL_FLAG_STATELESS is set in @flags, the caller of this function is
476 * expected to release the link returned by it directly with the help of either
477 * device_link_del() or device_link_remove().
479 * If that flag is not set, however, the caller of this function is handing the
480 * management of the link over to the driver core entirely and its return value
481 * can only be used to check whether or not the link is present. In that case,
482 * the DL_FLAG_AUTOREMOVE_CONSUMER and DL_FLAG_AUTOREMOVE_SUPPLIER device link
483 * flags can be used to indicate to the driver core when the link can be safely
484 * deleted. Namely, setting one of them in @flags indicates to the driver core
485 * that the link is not going to be used (by the given caller of this function)
486 * after unbinding the consumer or supplier driver, respectively, from its
487 * device, so the link can be deleted at that point. If none of them is set,
488 * the link will be maintained until one of the devices pointed to by it (either
489 * the consumer or the supplier) is unregistered.
491 * Also, if DL_FLAG_STATELESS, DL_FLAG_AUTOREMOVE_CONSUMER and
492 * DL_FLAG_AUTOREMOVE_SUPPLIER are not set in @flags (that is, a persistent
493 * managed device link is being added), the DL_FLAG_AUTOPROBE_CONSUMER flag can
494 * be used to request the driver core to automaticall probe for a consmer
495 * driver after successfully binding a driver to the supplier device.
497 * The combination of DL_FLAG_STATELESS and one of DL_FLAG_AUTOREMOVE_CONSUMER,
498 * DL_FLAG_AUTOREMOVE_SUPPLIER, or DL_FLAG_AUTOPROBE_CONSUMER set in @flags at
499 * the same time is invalid and will cause NULL to be returned upfront.
500 * However, if a device link between the given @consumer and @supplier pair
501 * exists already when this function is called for them, the existing link will
502 * be returned regardless of its current type and status (the link's flags may
503 * be modified then). The caller of this function is then expected to treat
504 * the link as though it has just been created, so (in particular) if
505 * DL_FLAG_STATELESS was passed in @flags, the link needs to be released
506 * explicitly when not needed any more (as stated above).
508 * A side effect of the link creation is re-ordering of dpm_list and the
509 * devices_kset list by moving the consumer device and all devices depending
510 * on it to the ends of these lists (that does not happen to devices that have
511 * not been registered when this function is called).
513 * The supplier device is required to be registered when this function is called
514 * and NULL will be returned if that is not the case. The consumer device need
515 * not be registered, however.
517 struct device_link *device_link_add(struct device *consumer,
518 struct device *supplier, u32 flags)
520 struct device_link *link;
522 if (!consumer || !supplier || flags & ~DL_ADD_VALID_FLAGS ||
523 (flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) ||
524 (flags & DL_FLAG_SYNC_STATE_ONLY &&
525 flags != DL_FLAG_SYNC_STATE_ONLY) ||
526 (flags & DL_FLAG_AUTOPROBE_CONSUMER &&
527 flags & (DL_FLAG_AUTOREMOVE_CONSUMER |
528 DL_FLAG_AUTOREMOVE_SUPPLIER)))
531 if (flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) {
532 if (pm_runtime_get_sync(supplier) < 0) {
533 pm_runtime_put_noidle(supplier);
538 if (!(flags & DL_FLAG_STATELESS))
539 flags |= DL_FLAG_MANAGED;
541 device_links_write_lock();
545 * If the supplier has not been fully registered yet or there is a
546 * reverse (non-SYNC_STATE_ONLY) dependency between the consumer and
547 * the supplier already in the graph, return NULL. If the link is a
548 * SYNC_STATE_ONLY link, we don't check for reverse dependencies
549 * because it only affects sync_state() callbacks.
551 if (!device_pm_initialized(supplier)
552 || (!(flags & DL_FLAG_SYNC_STATE_ONLY) &&
553 device_is_dependent(consumer, supplier))) {
559 * DL_FLAG_AUTOREMOVE_SUPPLIER indicates that the link will be needed
560 * longer than for DL_FLAG_AUTOREMOVE_CONSUMER and setting them both
561 * together doesn't make sense, so prefer DL_FLAG_AUTOREMOVE_SUPPLIER.
563 if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
564 flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
566 list_for_each_entry(link, &supplier->links.consumers, s_node) {
567 if (link->consumer != consumer)
570 if (flags & DL_FLAG_PM_RUNTIME) {
571 if (!(link->flags & DL_FLAG_PM_RUNTIME)) {
572 pm_runtime_new_link(consumer);
573 link->flags |= DL_FLAG_PM_RUNTIME;
575 if (flags & DL_FLAG_RPM_ACTIVE)
576 refcount_inc(&link->rpm_active);
579 if (flags & DL_FLAG_STATELESS) {
580 kref_get(&link->kref);
581 if (link->flags & DL_FLAG_SYNC_STATE_ONLY &&
582 !(link->flags & DL_FLAG_STATELESS)) {
583 link->flags |= DL_FLAG_STATELESS;
586 link->flags |= DL_FLAG_STATELESS;
592 * If the life time of the link following from the new flags is
593 * longer than indicated by the flags of the existing link,
594 * update the existing link to stay around longer.
596 if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER) {
597 if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
598 link->flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
599 link->flags |= DL_FLAG_AUTOREMOVE_SUPPLIER;
601 } else if (!(flags & DL_FLAG_AUTOREMOVE_CONSUMER)) {
602 link->flags &= ~(DL_FLAG_AUTOREMOVE_CONSUMER |
603 DL_FLAG_AUTOREMOVE_SUPPLIER);
605 if (!(link->flags & DL_FLAG_MANAGED)) {
606 kref_get(&link->kref);
607 link->flags |= DL_FLAG_MANAGED;
608 device_link_init_status(link, consumer, supplier);
610 if (link->flags & DL_FLAG_SYNC_STATE_ONLY &&
611 !(flags & DL_FLAG_SYNC_STATE_ONLY)) {
612 link->flags &= ~DL_FLAG_SYNC_STATE_ONLY;
619 link = kzalloc(sizeof(*link), GFP_KERNEL);
623 refcount_set(&link->rpm_active, 1);
625 get_device(supplier);
626 link->supplier = supplier;
627 INIT_LIST_HEAD(&link->s_node);
628 get_device(consumer);
629 link->consumer = consumer;
630 INIT_LIST_HEAD(&link->c_node);
632 kref_init(&link->kref);
634 link->link_dev.class = &devlink_class;
635 device_set_pm_not_required(&link->link_dev);
636 dev_set_name(&link->link_dev, "%s--%s",
637 dev_name(supplier), dev_name(consumer));
638 if (device_register(&link->link_dev)) {
639 put_device(consumer);
640 put_device(supplier);
646 if (flags & DL_FLAG_PM_RUNTIME) {
647 if (flags & DL_FLAG_RPM_ACTIVE)
648 refcount_inc(&link->rpm_active);
650 pm_runtime_new_link(consumer);
653 /* Determine the initial link state. */
654 if (flags & DL_FLAG_STATELESS)
655 link->status = DL_STATE_NONE;
657 device_link_init_status(link, consumer, supplier);
660 * Some callers expect the link creation during consumer driver probe to
661 * resume the supplier even without DL_FLAG_RPM_ACTIVE.
663 if (link->status == DL_STATE_CONSUMER_PROBE &&
664 flags & DL_FLAG_PM_RUNTIME)
665 pm_runtime_resume(supplier);
667 list_add_tail_rcu(&link->s_node, &supplier->links.consumers);
668 list_add_tail_rcu(&link->c_node, &consumer->links.suppliers);
670 if (flags & DL_FLAG_SYNC_STATE_ONLY) {
672 "Linked as a sync state only consumer to %s\n",
679 * Move the consumer and all of the devices depending on it to the end
680 * of dpm_list and the devices_kset list.
682 * It is necessary to hold dpm_list locked throughout all that or else
683 * we may end up suspending with a wrong ordering of it.
685 device_reorder_to_tail(consumer, NULL);
687 dev_dbg(consumer, "Linked as a consumer to %s\n", dev_name(supplier));
691 device_links_write_unlock();
693 if ((flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) && !link)
694 pm_runtime_put(supplier);
698 EXPORT_SYMBOL_GPL(device_link_add);
701 * device_link_wait_for_supplier - Add device to wait_for_suppliers list
702 * @consumer: Consumer device
704 * Marks the @consumer device as waiting for suppliers to become available by
705 * adding it to the wait_for_suppliers list. The consumer device will never be
706 * probed until it's removed from the wait_for_suppliers list.
708 * The caller is responsible for adding the links to the supplier devices once
709 * they are available and removing the @consumer device from the
710 * wait_for_suppliers list once links to all the suppliers have been created.
712 * This function is NOT meant to be called from the probe function of the
713 * consumer but rather from code that creates/adds the consumer device.
715 static void device_link_wait_for_supplier(struct device *consumer,
718 mutex_lock(&wfs_lock);
719 list_add_tail(&consumer->links.needs_suppliers, &wait_for_suppliers);
720 consumer->links.need_for_probe = need_for_probe;
721 mutex_unlock(&wfs_lock);
724 static void device_link_wait_for_mandatory_supplier(struct device *consumer)
726 device_link_wait_for_supplier(consumer, true);
729 static void device_link_wait_for_optional_supplier(struct device *consumer)
731 device_link_wait_for_supplier(consumer, false);
735 * device_link_add_missing_supplier_links - Add links from consumer devices to
736 * supplier devices, leaving any
737 * consumer with inactive suppliers on
738 * the wait_for_suppliers list
740 * Loops through all consumers waiting on suppliers and tries to add all their
741 * supplier links. If that succeeds, the consumer device is removed from
742 * wait_for_suppliers list. Otherwise, they are left in the wait_for_suppliers
743 * list. Devices left on the wait_for_suppliers list will not be probed.
745 * The fwnode add_links callback is expected to return 0 if it has found and
746 * added all the supplier links for the consumer device. It should return an
747 * error if it isn't able to do so.
749 * The caller of device_link_wait_for_supplier() is expected to call this once
750 * it's aware of potential suppliers becoming available.
752 static void device_link_add_missing_supplier_links(void)
754 struct device *dev, *tmp;
756 mutex_lock(&wfs_lock);
757 list_for_each_entry_safe(dev, tmp, &wait_for_suppliers,
758 links.needs_suppliers) {
759 int ret = fwnode_call_int_op(dev->fwnode, add_links, dev);
761 list_del_init(&dev->links.needs_suppliers);
762 else if (ret != -ENODEV || fw_devlink_is_permissive())
763 dev->links.need_for_probe = false;
765 mutex_unlock(&wfs_lock);
769 static void __device_link_del(struct kref *kref)
771 struct device_link *link = container_of(kref, struct device_link, kref);
773 dev_dbg(link->consumer, "Dropping the link to %s\n",
774 dev_name(link->supplier));
776 pm_runtime_drop_link(link);
778 list_del_rcu(&link->s_node);
779 list_del_rcu(&link->c_node);
780 device_unregister(&link->link_dev);
782 #else /* !CONFIG_SRCU */
783 static void __device_link_del(struct kref *kref)
785 struct device_link *link = container_of(kref, struct device_link, kref);
787 dev_info(link->consumer, "Dropping the link to %s\n",
788 dev_name(link->supplier));
790 pm_runtime_drop_link(link);
792 list_del(&link->s_node);
793 list_del(&link->c_node);
794 device_unregister(&link->link_dev);
796 #endif /* !CONFIG_SRCU */
798 static void device_link_put_kref(struct device_link *link)
800 if (link->flags & DL_FLAG_STATELESS)
801 kref_put(&link->kref, __device_link_del);
803 WARN(1, "Unable to drop a managed device link reference\n");
807 * device_link_del - Delete a stateless link between two devices.
808 * @link: Device link to delete.
810 * The caller must ensure proper synchronization of this function with runtime
811 * PM. If the link was added multiple times, it needs to be deleted as often.
812 * Care is required for hotplugged devices: Their links are purged on removal
813 * and calling device_link_del() is then no longer allowed.
815 void device_link_del(struct device_link *link)
817 device_links_write_lock();
818 device_link_put_kref(link);
819 device_links_write_unlock();
821 EXPORT_SYMBOL_GPL(device_link_del);
824 * device_link_remove - Delete a stateless link between two devices.
825 * @consumer: Consumer end of the link.
826 * @supplier: Supplier end of the link.
828 * The caller must ensure proper synchronization of this function with runtime
831 void device_link_remove(void *consumer, struct device *supplier)
833 struct device_link *link;
835 if (WARN_ON(consumer == supplier))
838 device_links_write_lock();
840 list_for_each_entry(link, &supplier->links.consumers, s_node) {
841 if (link->consumer == consumer) {
842 device_link_put_kref(link);
847 device_links_write_unlock();
849 EXPORT_SYMBOL_GPL(device_link_remove);
851 static void device_links_missing_supplier(struct device *dev)
853 struct device_link *link;
855 list_for_each_entry(link, &dev->links.suppliers, c_node) {
856 if (link->status != DL_STATE_CONSUMER_PROBE)
859 if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
860 WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
862 WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
863 WRITE_ONCE(link->status, DL_STATE_DORMANT);
869 * device_links_check_suppliers - Check presence of supplier drivers.
870 * @dev: Consumer device.
872 * Check links from this device to any suppliers. Walk the list of the device's
873 * links to suppliers and see if all of them are available. If not, simply
874 * return -EPROBE_DEFER.
876 * We need to guarantee that the supplier will not go away after the check has
877 * been positive here. It only can go away in __device_release_driver() and
878 * that function checks the device's links to consumers. This means we need to
879 * mark the link as "consumer probe in progress" to make the supplier removal
880 * wait for us to complete (or bad things may happen).
882 * Links without the DL_FLAG_MANAGED flag set are ignored.
884 int device_links_check_suppliers(struct device *dev)
886 struct device_link *link;
890 * Device waiting for supplier to become available is not allowed to
893 mutex_lock(&wfs_lock);
894 if (!list_empty(&dev->links.needs_suppliers) &&
895 dev->links.need_for_probe) {
896 mutex_unlock(&wfs_lock);
897 return -EPROBE_DEFER;
899 mutex_unlock(&wfs_lock);
901 device_links_write_lock();
903 list_for_each_entry(link, &dev->links.suppliers, c_node) {
904 if (!(link->flags & DL_FLAG_MANAGED))
907 if (link->status != DL_STATE_AVAILABLE &&
908 !(link->flags & DL_FLAG_SYNC_STATE_ONLY)) {
909 device_links_missing_supplier(dev);
913 WRITE_ONCE(link->status, DL_STATE_CONSUMER_PROBE);
915 dev->links.status = DL_DEV_PROBING;
917 device_links_write_unlock();
922 * __device_links_queue_sync_state - Queue a device for sync_state() callback
923 * @dev: Device to call sync_state() on
924 * @list: List head to queue the @dev on
926 * Queues a device for a sync_state() callback when the device links write lock
927 * isn't held. This allows the sync_state() execution flow to use device links
928 * APIs. The caller must ensure this function is called with
929 * device_links_write_lock() held.
931 * This function does a get_device() to make sure the device is not freed while
934 * So the caller must also ensure that device_links_flush_sync_list() is called
935 * as soon as the caller releases device_links_write_lock(). This is necessary
936 * to make sure the sync_state() is called in a timely fashion and the
937 * put_device() is called on this device.
939 static void __device_links_queue_sync_state(struct device *dev,
940 struct list_head *list)
942 struct device_link *link;
944 if (!dev_has_sync_state(dev))
946 if (dev->state_synced)
949 list_for_each_entry(link, &dev->links.consumers, s_node) {
950 if (!(link->flags & DL_FLAG_MANAGED))
952 if (link->status != DL_STATE_ACTIVE)
957 * Set the flag here to avoid adding the same device to a list more
958 * than once. This can happen if new consumers get added to the device
959 * and probed before the list is flushed.
961 dev->state_synced = true;
963 if (WARN_ON(!list_empty(&dev->links.defer_hook)))
967 list_add_tail(&dev->links.defer_hook, list);
971 * device_links_flush_sync_list - Call sync_state() on a list of devices
972 * @list: List of devices to call sync_state() on
973 * @dont_lock_dev: Device for which lock is already held by the caller
975 * Calls sync_state() on all the devices that have been queued for it. This
976 * function is used in conjunction with __device_links_queue_sync_state(). The
977 * @dont_lock_dev parameter is useful when this function is called from a
978 * context where a device lock is already held.
980 static void device_links_flush_sync_list(struct list_head *list,
981 struct device *dont_lock_dev)
983 struct device *dev, *tmp;
985 list_for_each_entry_safe(dev, tmp, list, links.defer_hook) {
986 list_del_init(&dev->links.defer_hook);
988 if (dev != dont_lock_dev)
991 if (dev->bus->sync_state)
992 dev->bus->sync_state(dev);
993 else if (dev->driver && dev->driver->sync_state)
994 dev->driver->sync_state(dev);
996 if (dev != dont_lock_dev)
1003 void device_links_supplier_sync_state_pause(void)
1005 device_links_write_lock();
1006 defer_sync_state_count++;
1007 device_links_write_unlock();
1010 void device_links_supplier_sync_state_resume(void)
1012 struct device *dev, *tmp;
1013 LIST_HEAD(sync_list);
1015 device_links_write_lock();
1016 if (!defer_sync_state_count) {
1017 WARN(true, "Unmatched sync_state pause/resume!");
1020 defer_sync_state_count--;
1021 if (defer_sync_state_count)
1024 list_for_each_entry_safe(dev, tmp, &deferred_sync, links.defer_hook) {
1026 * Delete from deferred_sync list before queuing it to
1027 * sync_list because defer_hook is used for both lists.
1029 list_del_init(&dev->links.defer_hook);
1030 __device_links_queue_sync_state(dev, &sync_list);
1033 device_links_write_unlock();
1035 device_links_flush_sync_list(&sync_list, NULL);
1038 static int sync_state_resume_initcall(void)
1040 device_links_supplier_sync_state_resume();
1043 late_initcall(sync_state_resume_initcall);
1045 static void __device_links_supplier_defer_sync(struct device *sup)
1047 if (list_empty(&sup->links.defer_hook) && dev_has_sync_state(sup))
1048 list_add_tail(&sup->links.defer_hook, &deferred_sync);
1051 static void device_link_drop_managed(struct device_link *link)
1053 link->flags &= ~DL_FLAG_MANAGED;
1054 WRITE_ONCE(link->status, DL_STATE_NONE);
1055 kref_put(&link->kref, __device_link_del);
1058 static ssize_t waiting_for_supplier_show(struct device *dev,
1059 struct device_attribute *attr,
1065 val = !list_empty(&dev->links.needs_suppliers)
1066 && dev->links.need_for_probe;
1068 return sysfs_emit(buf, "%u\n", val);
1070 static DEVICE_ATTR_RO(waiting_for_supplier);
1073 * device_links_driver_bound - Update device links after probing its driver.
1074 * @dev: Device to update the links for.
1076 * The probe has been successful, so update links from this device to any
1077 * consumers by changing their status to "available".
1079 * Also change the status of @dev's links to suppliers to "active".
1081 * Links without the DL_FLAG_MANAGED flag set are ignored.
1083 void device_links_driver_bound(struct device *dev)
1085 struct device_link *link, *ln;
1086 LIST_HEAD(sync_list);
1089 * If a device probes successfully, it's expected to have created all
1090 * the device links it needs to or make new device links as it needs
1091 * them. So, it no longer needs to wait on any suppliers.
1093 mutex_lock(&wfs_lock);
1094 list_del_init(&dev->links.needs_suppliers);
1095 mutex_unlock(&wfs_lock);
1096 device_remove_file(dev, &dev_attr_waiting_for_supplier);
1098 device_links_write_lock();
1100 list_for_each_entry(link, &dev->links.consumers, s_node) {
1101 if (!(link->flags & DL_FLAG_MANAGED))
1105 * Links created during consumer probe may be in the "consumer
1106 * probe" state to start with if the supplier is still probing
1107 * when they are created and they may become "active" if the
1108 * consumer probe returns first. Skip them here.
1110 if (link->status == DL_STATE_CONSUMER_PROBE ||
1111 link->status == DL_STATE_ACTIVE)
1114 WARN_ON(link->status != DL_STATE_DORMANT);
1115 WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
1117 if (link->flags & DL_FLAG_AUTOPROBE_CONSUMER)
1118 driver_deferred_probe_add(link->consumer);
1121 if (defer_sync_state_count)
1122 __device_links_supplier_defer_sync(dev);
1124 __device_links_queue_sync_state(dev, &sync_list);
1126 list_for_each_entry_safe(link, ln, &dev->links.suppliers, c_node) {
1127 struct device *supplier;
1129 if (!(link->flags & DL_FLAG_MANAGED))
1132 supplier = link->supplier;
1133 if (link->flags & DL_FLAG_SYNC_STATE_ONLY) {
1135 * When DL_FLAG_SYNC_STATE_ONLY is set, it means no
1136 * other DL_MANAGED_LINK_FLAGS have been set. So, it's
1137 * save to drop the managed link completely.
1139 device_link_drop_managed(link);
1141 WARN_ON(link->status != DL_STATE_CONSUMER_PROBE);
1142 WRITE_ONCE(link->status, DL_STATE_ACTIVE);
1146 * This needs to be done even for the deleted
1147 * DL_FLAG_SYNC_STATE_ONLY device link in case it was the last
1148 * device link that was preventing the supplier from getting a
1149 * sync_state() call.
1151 if (defer_sync_state_count)
1152 __device_links_supplier_defer_sync(supplier);
1154 __device_links_queue_sync_state(supplier, &sync_list);
1157 dev->links.status = DL_DEV_DRIVER_BOUND;
1159 device_links_write_unlock();
1161 device_links_flush_sync_list(&sync_list, dev);
1165 * __device_links_no_driver - Update links of a device without a driver.
1166 * @dev: Device without a drvier.
1168 * Delete all non-persistent links from this device to any suppliers.
1170 * Persistent links stay around, but their status is changed to "available",
1171 * unless they already are in the "supplier unbind in progress" state in which
1172 * case they need not be updated.
1174 * Links without the DL_FLAG_MANAGED flag set are ignored.
1176 static void __device_links_no_driver(struct device *dev)
1178 struct device_link *link, *ln;
1180 list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
1181 if (!(link->flags & DL_FLAG_MANAGED))
1184 if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
1185 device_link_drop_managed(link);
1189 if (link->status != DL_STATE_CONSUMER_PROBE &&
1190 link->status != DL_STATE_ACTIVE)
1193 if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
1194 WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
1196 WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
1197 WRITE_ONCE(link->status, DL_STATE_DORMANT);
1201 dev->links.status = DL_DEV_NO_DRIVER;
1205 * device_links_no_driver - Update links after failing driver probe.
1206 * @dev: Device whose driver has just failed to probe.
1208 * Clean up leftover links to consumers for @dev and invoke
1209 * %__device_links_no_driver() to update links to suppliers for it as
1212 * Links without the DL_FLAG_MANAGED flag set are ignored.
1214 void device_links_no_driver(struct device *dev)
1216 struct device_link *link;
1218 device_links_write_lock();
1220 list_for_each_entry(link, &dev->links.consumers, s_node) {
1221 if (!(link->flags & DL_FLAG_MANAGED))
1225 * The probe has failed, so if the status of the link is
1226 * "consumer probe" or "active", it must have been added by
1227 * a probing consumer while this device was still probing.
1228 * Change its state to "dormant", as it represents a valid
1229 * relationship, but it is not functionally meaningful.
1231 if (link->status == DL_STATE_CONSUMER_PROBE ||
1232 link->status == DL_STATE_ACTIVE)
1233 WRITE_ONCE(link->status, DL_STATE_DORMANT);
1236 __device_links_no_driver(dev);
1238 device_links_write_unlock();
1242 * device_links_driver_cleanup - Update links after driver removal.
1243 * @dev: Device whose driver has just gone away.
1245 * Update links to consumers for @dev by changing their status to "dormant" and
1246 * invoke %__device_links_no_driver() to update links to suppliers for it as
1249 * Links without the DL_FLAG_MANAGED flag set are ignored.
1251 void device_links_driver_cleanup(struct device *dev)
1253 struct device_link *link, *ln;
1255 device_links_write_lock();
1257 list_for_each_entry_safe(link, ln, &dev->links.consumers, s_node) {
1258 if (!(link->flags & DL_FLAG_MANAGED))
1261 WARN_ON(link->flags & DL_FLAG_AUTOREMOVE_CONSUMER);
1262 WARN_ON(link->status != DL_STATE_SUPPLIER_UNBIND);
1265 * autoremove the links between this @dev and its consumer
1266 * devices that are not active, i.e. where the link state
1267 * has moved to DL_STATE_SUPPLIER_UNBIND.
1269 if (link->status == DL_STATE_SUPPLIER_UNBIND &&
1270 link->flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
1271 device_link_drop_managed(link);
1273 WRITE_ONCE(link->status, DL_STATE_DORMANT);
1276 list_del_init(&dev->links.defer_hook);
1277 __device_links_no_driver(dev);
1279 device_links_write_unlock();
1283 * device_links_busy - Check if there are any busy links to consumers.
1284 * @dev: Device to check.
1286 * Check each consumer of the device and return 'true' if its link's status
1287 * is one of "consumer probe" or "active" (meaning that the given consumer is
1288 * probing right now or its driver is present). Otherwise, change the link
1289 * state to "supplier unbind" to prevent the consumer from being probed
1290 * successfully going forward.
1292 * Return 'false' if there are no probing or active consumers.
1294 * Links without the DL_FLAG_MANAGED flag set are ignored.
1296 bool device_links_busy(struct device *dev)
1298 struct device_link *link;
1301 device_links_write_lock();
1303 list_for_each_entry(link, &dev->links.consumers, s_node) {
1304 if (!(link->flags & DL_FLAG_MANAGED))
1307 if (link->status == DL_STATE_CONSUMER_PROBE
1308 || link->status == DL_STATE_ACTIVE) {
1312 WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
1315 dev->links.status = DL_DEV_UNBINDING;
1317 device_links_write_unlock();
1322 * device_links_unbind_consumers - Force unbind consumers of the given device.
1323 * @dev: Device to unbind the consumers of.
1325 * Walk the list of links to consumers for @dev and if any of them is in the
1326 * "consumer probe" state, wait for all device probes in progress to complete
1329 * If that's not the case, change the status of the link to "supplier unbind"
1330 * and check if the link was in the "active" state. If so, force the consumer
1331 * driver to unbind and start over (the consumer will not re-probe as we have
1332 * changed the state of the link already).
1334 * Links without the DL_FLAG_MANAGED flag set are ignored.
1336 void device_links_unbind_consumers(struct device *dev)
1338 struct device_link *link;
1341 device_links_write_lock();
1343 list_for_each_entry(link, &dev->links.consumers, s_node) {
1344 enum device_link_state status;
1346 if (!(link->flags & DL_FLAG_MANAGED) ||
1347 link->flags & DL_FLAG_SYNC_STATE_ONLY)
1350 status = link->status;
1351 if (status == DL_STATE_CONSUMER_PROBE) {
1352 device_links_write_unlock();
1354 wait_for_device_probe();
1357 WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
1358 if (status == DL_STATE_ACTIVE) {
1359 struct device *consumer = link->consumer;
1361 get_device(consumer);
1363 device_links_write_unlock();
1365 device_release_driver_internal(consumer, NULL,
1367 put_device(consumer);
1372 device_links_write_unlock();
1376 * device_links_purge - Delete existing links to other devices.
1377 * @dev: Target device.
1379 static void device_links_purge(struct device *dev)
1381 struct device_link *link, *ln;
1383 if (dev->class == &devlink_class)
1386 mutex_lock(&wfs_lock);
1387 list_del_init(&dev->links.needs_suppliers);
1388 mutex_unlock(&wfs_lock);
1391 * Delete all of the remaining links from this device to any other
1392 * devices (either consumers or suppliers).
1394 device_links_write_lock();
1396 list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
1397 WARN_ON(link->status == DL_STATE_ACTIVE);
1398 __device_link_del(&link->kref);
1401 list_for_each_entry_safe_reverse(link, ln, &dev->links.consumers, s_node) {
1402 WARN_ON(link->status != DL_STATE_DORMANT &&
1403 link->status != DL_STATE_NONE);
1404 __device_link_del(&link->kref);
1407 device_links_write_unlock();
1410 static u32 fw_devlink_flags = DL_FLAG_SYNC_STATE_ONLY;
1411 static int __init fw_devlink_setup(char *arg)
1416 if (strcmp(arg, "off") == 0) {
1417 fw_devlink_flags = 0;
1418 } else if (strcmp(arg, "permissive") == 0) {
1419 fw_devlink_flags = DL_FLAG_SYNC_STATE_ONLY;
1420 } else if (strcmp(arg, "on") == 0) {
1421 fw_devlink_flags = DL_FLAG_AUTOPROBE_CONSUMER;
1422 } else if (strcmp(arg, "rpm") == 0) {
1423 fw_devlink_flags = DL_FLAG_AUTOPROBE_CONSUMER |
1428 early_param("fw_devlink", fw_devlink_setup);
1430 u32 fw_devlink_get_flags(void)
1432 return fw_devlink_flags;
1435 static bool fw_devlink_is_permissive(void)
1437 return fw_devlink_flags == DL_FLAG_SYNC_STATE_ONLY;
1440 static void fw_devlink_link_device(struct device *dev)
1444 if (!fw_devlink_flags)
1447 mutex_lock(&defer_fw_devlink_lock);
1448 if (!defer_fw_devlink_count)
1449 device_link_add_missing_supplier_links();
1452 * The device's fwnode not having add_links() doesn't affect if other
1453 * consumers can find this device as a supplier. So, this check is
1454 * intentionally placed after device_link_add_missing_supplier_links().
1456 if (!fwnode_has_op(dev->fwnode, add_links))
1460 * If fw_devlink is being deferred, assume all devices have mandatory
1461 * suppliers they need to link to later. Then, when the fw_devlink is
1462 * resumed, all these devices will get a chance to try and link to any
1463 * suppliers they have.
1465 if (!defer_fw_devlink_count) {
1466 fw_ret = fwnode_call_int_op(dev->fwnode, add_links, dev);
1467 if (fw_ret == -ENODEV && fw_devlink_is_permissive())
1472 * defer_hook is not used to add device to deferred_sync list
1473 * until device is bound. Since deferred fw devlink also blocks
1474 * probing, same list hook can be used for deferred_fw_devlink.
1476 list_add_tail(&dev->links.defer_hook, &deferred_fw_devlink);
1479 if (fw_ret == -ENODEV)
1480 device_link_wait_for_mandatory_supplier(dev);
1482 device_link_wait_for_optional_supplier(dev);
1485 mutex_unlock(&defer_fw_devlink_lock);
1489 * fw_devlink_pause - Pause parsing of fwnode to create device links
1491 * Calling this function defers any fwnode parsing to create device links until
1492 * fw_devlink_resume() is called. Both these functions are ref counted and the
1493 * caller needs to match the calls.
1495 * While fw_devlink is paused:
1496 * - Any device that is added won't have its fwnode parsed to create device
1498 * - The probe of the device will also be deferred during this period.
1499 * - Any devices that were already added, but waiting for suppliers won't be
1500 * able to link to newly added devices.
1502 * Once fw_devlink_resume():
1503 * - All the fwnodes that was not parsed will be parsed.
1504 * - All the devices that were deferred probing will be reattempted if they
1505 * aren't waiting for any more suppliers.
1507 * This pair of functions, is mainly meant to optimize the parsing of fwnodes
1508 * when a lot of devices that need to link to each other are added in a short
1509 * interval of time. For example, adding all the top level devices in a system.
1511 * For example, if N devices are added and:
1512 * - All the consumers are added before their suppliers
1513 * - All the suppliers of the N devices are part of the N devices
1517 * - With the use of fw_devlink_pause() and fw_devlink_resume(), each device
1518 * will only need one parsing of its fwnode because it is guaranteed to find
1519 * all the supplier devices already registered and ready to link to. It won't
1520 * have to do another pass later to find one or more suppliers it couldn't
1521 * find in the first parse of the fwnode. So, we'll only need O(N) fwnode
1524 * - Without the use of fw_devlink_pause() and fw_devlink_resume(), we would
1525 * end up doing O(N^2) parses of fwnodes because every device that's added is
1526 * guaranteed to trigger a parse of the fwnode of every device added before
1527 * it. This O(N^2) parse is made worse by the fact that when a fwnode of a
1528 * device is parsed, all it descendant devices might need to have their
1529 * fwnodes parsed too (even if the devices themselves aren't added).
1531 void fw_devlink_pause(void)
1533 mutex_lock(&defer_fw_devlink_lock);
1534 defer_fw_devlink_count++;
1535 mutex_unlock(&defer_fw_devlink_lock);
1538 /** fw_devlink_resume - Resume parsing of fwnode to create device links
1540 * This function is used in conjunction with fw_devlink_pause() and is ref
1541 * counted. See documentation for fw_devlink_pause() for more details.
1543 void fw_devlink_resume(void)
1545 struct device *dev, *tmp;
1546 LIST_HEAD(probe_list);
1548 mutex_lock(&defer_fw_devlink_lock);
1549 if (!defer_fw_devlink_count) {
1550 WARN(true, "Unmatched fw_devlink pause/resume!");
1554 defer_fw_devlink_count--;
1555 if (defer_fw_devlink_count)
1558 device_link_add_missing_supplier_links();
1559 list_splice_tail_init(&deferred_fw_devlink, &probe_list);
1561 mutex_unlock(&defer_fw_devlink_lock);
1564 * bus_probe_device() can cause new devices to get added and they'll
1565 * try to grab defer_fw_devlink_lock. So, this needs to be done outside
1566 * the defer_fw_devlink_lock.
1568 list_for_each_entry_safe(dev, tmp, &probe_list, links.defer_hook) {
1569 list_del_init(&dev->links.defer_hook);
1570 bus_probe_device(dev);
1573 /* Device links support end. */
1575 int (*platform_notify)(struct device *dev) = NULL;
1576 int (*platform_notify_remove)(struct device *dev) = NULL;
1577 static struct kobject *dev_kobj;
1578 struct kobject *sysfs_dev_char_kobj;
1579 struct kobject *sysfs_dev_block_kobj;
1581 static DEFINE_MUTEX(device_hotplug_lock);
1583 void lock_device_hotplug(void)
1585 mutex_lock(&device_hotplug_lock);
1588 void unlock_device_hotplug(void)
1590 mutex_unlock(&device_hotplug_lock);
1593 int lock_device_hotplug_sysfs(void)
1595 if (mutex_trylock(&device_hotplug_lock))
1598 /* Avoid busy looping (5 ms of sleep should do). */
1600 return restart_syscall();
1604 static inline int device_is_not_partition(struct device *dev)
1606 return !(dev->type == &part_type);
1609 static inline int device_is_not_partition(struct device *dev)
1616 device_platform_notify(struct device *dev, enum kobject_action action)
1620 ret = acpi_platform_notify(dev, action);
1624 ret = software_node_notify(dev, action);
1628 if (platform_notify && action == KOBJ_ADD)
1629 platform_notify(dev);
1630 else if (platform_notify_remove && action == KOBJ_REMOVE)
1631 platform_notify_remove(dev);
1636 * dev_driver_string - Return a device's driver name, if at all possible
1637 * @dev: struct device to get the name of
1639 * Will return the device's driver's name if it is bound to a device. If
1640 * the device is not bound to a driver, it will return the name of the bus
1641 * it is attached to. If it is not attached to a bus either, an empty
1642 * string will be returned.
1644 const char *dev_driver_string(const struct device *dev)
1646 struct device_driver *drv;
1648 /* dev->driver can change to NULL underneath us because of unbinding,
1649 * so be careful about accessing it. dev->bus and dev->class should
1650 * never change once they are set, so they don't need special care.
1652 drv = READ_ONCE(dev->driver);
1653 return drv ? drv->name :
1654 (dev->bus ? dev->bus->name :
1655 (dev->class ? dev->class->name : ""));
1657 EXPORT_SYMBOL(dev_driver_string);
1659 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
1661 static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
1664 struct device_attribute *dev_attr = to_dev_attr(attr);
1665 struct device *dev = kobj_to_dev(kobj);
1669 ret = dev_attr->show(dev, dev_attr, buf);
1670 if (ret >= (ssize_t)PAGE_SIZE) {
1671 printk("dev_attr_show: %pS returned bad count\n",
1677 static ssize_t dev_attr_store(struct kobject *kobj, struct attribute *attr,
1678 const char *buf, size_t count)
1680 struct device_attribute *dev_attr = to_dev_attr(attr);
1681 struct device *dev = kobj_to_dev(kobj);
1684 if (dev_attr->store)
1685 ret = dev_attr->store(dev, dev_attr, buf, count);
1689 static const struct sysfs_ops dev_sysfs_ops = {
1690 .show = dev_attr_show,
1691 .store = dev_attr_store,
1694 #define to_ext_attr(x) container_of(x, struct dev_ext_attribute, attr)
1696 ssize_t device_store_ulong(struct device *dev,
1697 struct device_attribute *attr,
1698 const char *buf, size_t size)
1700 struct dev_ext_attribute *ea = to_ext_attr(attr);
1704 ret = kstrtoul(buf, 0, &new);
1707 *(unsigned long *)(ea->var) = new;
1708 /* Always return full write size even if we didn't consume all */
1711 EXPORT_SYMBOL_GPL(device_store_ulong);
1713 ssize_t device_show_ulong(struct device *dev,
1714 struct device_attribute *attr,
1717 struct dev_ext_attribute *ea = to_ext_attr(attr);
1718 return sysfs_emit(buf, "%lx\n", *(unsigned long *)(ea->var));
1720 EXPORT_SYMBOL_GPL(device_show_ulong);
1722 ssize_t device_store_int(struct device *dev,
1723 struct device_attribute *attr,
1724 const char *buf, size_t size)
1726 struct dev_ext_attribute *ea = to_ext_attr(attr);
1730 ret = kstrtol(buf, 0, &new);
1734 if (new > INT_MAX || new < INT_MIN)
1736 *(int *)(ea->var) = new;
1737 /* Always return full write size even if we didn't consume all */
1740 EXPORT_SYMBOL_GPL(device_store_int);
1742 ssize_t device_show_int(struct device *dev,
1743 struct device_attribute *attr,
1746 struct dev_ext_attribute *ea = to_ext_attr(attr);
1748 return sysfs_emit(buf, "%d\n", *(int *)(ea->var));
1750 EXPORT_SYMBOL_GPL(device_show_int);
1752 ssize_t device_store_bool(struct device *dev, struct device_attribute *attr,
1753 const char *buf, size_t size)
1755 struct dev_ext_attribute *ea = to_ext_attr(attr);
1757 if (strtobool(buf, ea->var) < 0)
1762 EXPORT_SYMBOL_GPL(device_store_bool);
1764 ssize_t device_show_bool(struct device *dev, struct device_attribute *attr,
1767 struct dev_ext_attribute *ea = to_ext_attr(attr);
1769 return sysfs_emit(buf, "%d\n", *(bool *)(ea->var));
1771 EXPORT_SYMBOL_GPL(device_show_bool);
1774 * device_release - free device structure.
1775 * @kobj: device's kobject.
1777 * This is called once the reference count for the object
1778 * reaches 0. We forward the call to the device's release
1779 * method, which should handle actually freeing the structure.
1781 static void device_release(struct kobject *kobj)
1783 struct device *dev = kobj_to_dev(kobj);
1784 struct device_private *p = dev->p;
1787 * Some platform devices are driven without driver attached
1788 * and managed resources may have been acquired. Make sure
1789 * all resources are released.
1791 * Drivers still can add resources into device after device
1792 * is deleted but alive, so release devres here to avoid
1793 * possible memory leak.
1795 devres_release_all(dev);
1797 kfree(dev->dma_range_map);
1801 else if (dev->type && dev->type->release)
1802 dev->type->release(dev);
1803 else if (dev->class && dev->class->dev_release)
1804 dev->class->dev_release(dev);
1806 WARN(1, KERN_ERR "Device '%s' does not have a release() function, it is broken and must be fixed. See Documentation/core-api/kobject.rst.\n",
1811 static const void *device_namespace(struct kobject *kobj)
1813 struct device *dev = kobj_to_dev(kobj);
1814 const void *ns = NULL;
1816 if (dev->class && dev->class->ns_type)
1817 ns = dev->class->namespace(dev);
1822 static void device_get_ownership(struct kobject *kobj, kuid_t *uid, kgid_t *gid)
1824 struct device *dev = kobj_to_dev(kobj);
1826 if (dev->class && dev->class->get_ownership)
1827 dev->class->get_ownership(dev, uid, gid);
1830 static struct kobj_type device_ktype = {
1831 .release = device_release,
1832 .sysfs_ops = &dev_sysfs_ops,
1833 .namespace = device_namespace,
1834 .get_ownership = device_get_ownership,
1838 static int dev_uevent_filter(struct kset *kset, struct kobject *kobj)
1840 struct kobj_type *ktype = get_ktype(kobj);
1842 if (ktype == &device_ktype) {
1843 struct device *dev = kobj_to_dev(kobj);
1852 static const char *dev_uevent_name(struct kset *kset, struct kobject *kobj)
1854 struct device *dev = kobj_to_dev(kobj);
1857 return dev->bus->name;
1859 return dev->class->name;
1863 static int dev_uevent(struct kset *kset, struct kobject *kobj,
1864 struct kobj_uevent_env *env)
1866 struct device *dev = kobj_to_dev(kobj);
1869 /* add device node properties if present */
1870 if (MAJOR(dev->devt)) {
1874 kuid_t uid = GLOBAL_ROOT_UID;
1875 kgid_t gid = GLOBAL_ROOT_GID;
1877 add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
1878 add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
1879 name = device_get_devnode(dev, &mode, &uid, &gid, &tmp);
1881 add_uevent_var(env, "DEVNAME=%s", name);
1883 add_uevent_var(env, "DEVMODE=%#o", mode & 0777);
1884 if (!uid_eq(uid, GLOBAL_ROOT_UID))
1885 add_uevent_var(env, "DEVUID=%u", from_kuid(&init_user_ns, uid));
1886 if (!gid_eq(gid, GLOBAL_ROOT_GID))
1887 add_uevent_var(env, "DEVGID=%u", from_kgid(&init_user_ns, gid));
1892 if (dev->type && dev->type->name)
1893 add_uevent_var(env, "DEVTYPE=%s", dev->type->name);
1896 add_uevent_var(env, "DRIVER=%s", dev->driver->name);
1898 /* Add common DT information about the device */
1899 of_device_uevent(dev, env);
1901 /* have the bus specific function add its stuff */
1902 if (dev->bus && dev->bus->uevent) {
1903 retval = dev->bus->uevent(dev, env);
1905 pr_debug("device: '%s': %s: bus uevent() returned %d\n",
1906 dev_name(dev), __func__, retval);
1909 /* have the class specific function add its stuff */
1910 if (dev->class && dev->class->dev_uevent) {
1911 retval = dev->class->dev_uevent(dev, env);
1913 pr_debug("device: '%s': %s: class uevent() "
1914 "returned %d\n", dev_name(dev),
1918 /* have the device type specific function add its stuff */
1919 if (dev->type && dev->type->uevent) {
1920 retval = dev->type->uevent(dev, env);
1922 pr_debug("device: '%s': %s: dev_type uevent() "
1923 "returned %d\n", dev_name(dev),
1930 static const struct kset_uevent_ops device_uevent_ops = {
1931 .filter = dev_uevent_filter,
1932 .name = dev_uevent_name,
1933 .uevent = dev_uevent,
1936 static ssize_t uevent_show(struct device *dev, struct device_attribute *attr,
1939 struct kobject *top_kobj;
1941 struct kobj_uevent_env *env = NULL;
1946 /* search the kset, the device belongs to */
1947 top_kobj = &dev->kobj;
1948 while (!top_kobj->kset && top_kobj->parent)
1949 top_kobj = top_kobj->parent;
1950 if (!top_kobj->kset)
1953 kset = top_kobj->kset;
1954 if (!kset->uevent_ops || !kset->uevent_ops->uevent)
1957 /* respect filter */
1958 if (kset->uevent_ops && kset->uevent_ops->filter)
1959 if (!kset->uevent_ops->filter(kset, &dev->kobj))
1962 env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
1966 /* let the kset specific function add its keys */
1967 retval = kset->uevent_ops->uevent(kset, &dev->kobj, env);
1971 /* copy keys to file */
1972 for (i = 0; i < env->envp_idx; i++)
1973 len += sysfs_emit_at(buf, len, "%s\n", env->envp[i]);
1979 static ssize_t uevent_store(struct device *dev, struct device_attribute *attr,
1980 const char *buf, size_t count)
1984 rc = kobject_synth_uevent(&dev->kobj, buf, count);
1987 dev_err(dev, "uevent: failed to send synthetic uevent\n");
1993 static DEVICE_ATTR_RW(uevent);
1995 static ssize_t online_show(struct device *dev, struct device_attribute *attr,
2001 val = !dev->offline;
2003 return sysfs_emit(buf, "%u\n", val);
2006 static ssize_t online_store(struct device *dev, struct device_attribute *attr,
2007 const char *buf, size_t count)
2012 ret = strtobool(buf, &val);
2016 ret = lock_device_hotplug_sysfs();
2020 ret = val ? device_online(dev) : device_offline(dev);
2021 unlock_device_hotplug();
2022 return ret < 0 ? ret : count;
2024 static DEVICE_ATTR_RW(online);
2026 int device_add_groups(struct device *dev, const struct attribute_group **groups)
2028 return sysfs_create_groups(&dev->kobj, groups);
2030 EXPORT_SYMBOL_GPL(device_add_groups);
2032 void device_remove_groups(struct device *dev,
2033 const struct attribute_group **groups)
2035 sysfs_remove_groups(&dev->kobj, groups);
2037 EXPORT_SYMBOL_GPL(device_remove_groups);
2039 union device_attr_group_devres {
2040 const struct attribute_group *group;
2041 const struct attribute_group **groups;
2044 static int devm_attr_group_match(struct device *dev, void *res, void *data)
2046 return ((union device_attr_group_devres *)res)->group == data;
2049 static void devm_attr_group_remove(struct device *dev, void *res)
2051 union device_attr_group_devres *devres = res;
2052 const struct attribute_group *group = devres->group;
2054 dev_dbg(dev, "%s: removing group %p\n", __func__, group);
2055 sysfs_remove_group(&dev->kobj, group);
2058 static void devm_attr_groups_remove(struct device *dev, void *res)
2060 union device_attr_group_devres *devres = res;
2061 const struct attribute_group **groups = devres->groups;
2063 dev_dbg(dev, "%s: removing groups %p\n", __func__, groups);
2064 sysfs_remove_groups(&dev->kobj, groups);
2068 * devm_device_add_group - given a device, create a managed attribute group
2069 * @dev: The device to create the group for
2070 * @grp: The attribute group to create
2072 * This function creates a group for the first time. It will explicitly
2073 * warn and error if any of the attribute files being created already exist.
2075 * Returns 0 on success or error code on failure.
2077 int devm_device_add_group(struct device *dev, const struct attribute_group *grp)
2079 union device_attr_group_devres *devres;
2082 devres = devres_alloc(devm_attr_group_remove,
2083 sizeof(*devres), GFP_KERNEL);
2087 error = sysfs_create_group(&dev->kobj, grp);
2089 devres_free(devres);
2093 devres->group = grp;
2094 devres_add(dev, devres);
2097 EXPORT_SYMBOL_GPL(devm_device_add_group);
2100 * devm_device_remove_group: remove a managed group from a device
2101 * @dev: device to remove the group from
2102 * @grp: group to remove
2104 * This function removes a group of attributes from a device. The attributes
2105 * previously have to have been created for this group, otherwise it will fail.
2107 void devm_device_remove_group(struct device *dev,
2108 const struct attribute_group *grp)
2110 WARN_ON(devres_release(dev, devm_attr_group_remove,
2111 devm_attr_group_match,
2112 /* cast away const */ (void *)grp));
2114 EXPORT_SYMBOL_GPL(devm_device_remove_group);
2117 * devm_device_add_groups - create a bunch of managed attribute groups
2118 * @dev: The device to create the group for
2119 * @groups: The attribute groups to create, NULL terminated
2121 * This function creates a bunch of managed attribute groups. If an error
2122 * occurs when creating a group, all previously created groups will be
2123 * removed, unwinding everything back to the original state when this
2124 * function was called. It will explicitly warn and error if any of the
2125 * attribute files being created already exist.
2127 * Returns 0 on success or error code from sysfs_create_group on failure.
2129 int devm_device_add_groups(struct device *dev,
2130 const struct attribute_group **groups)
2132 union device_attr_group_devres *devres;
2135 devres = devres_alloc(devm_attr_groups_remove,
2136 sizeof(*devres), GFP_KERNEL);
2140 error = sysfs_create_groups(&dev->kobj, groups);
2142 devres_free(devres);
2146 devres->groups = groups;
2147 devres_add(dev, devres);
2150 EXPORT_SYMBOL_GPL(devm_device_add_groups);
2153 * devm_device_remove_groups - remove a list of managed groups
2155 * @dev: The device for the groups to be removed from
2156 * @groups: NULL terminated list of groups to be removed
2158 * If groups is not NULL, remove the specified groups from the device.
2160 void devm_device_remove_groups(struct device *dev,
2161 const struct attribute_group **groups)
2163 WARN_ON(devres_release(dev, devm_attr_groups_remove,
2164 devm_attr_group_match,
2165 /* cast away const */ (void *)groups));
2167 EXPORT_SYMBOL_GPL(devm_device_remove_groups);
2169 static int device_add_attrs(struct device *dev)
2171 struct class *class = dev->class;
2172 const struct device_type *type = dev->type;
2176 error = device_add_groups(dev, class->dev_groups);
2182 error = device_add_groups(dev, type->groups);
2184 goto err_remove_class_groups;
2187 error = device_add_groups(dev, dev->groups);
2189 goto err_remove_type_groups;
2191 if (device_supports_offline(dev) && !dev->offline_disabled) {
2192 error = device_create_file(dev, &dev_attr_online);
2194 goto err_remove_dev_groups;
2197 if (fw_devlink_flags && !fw_devlink_is_permissive()) {
2198 error = device_create_file(dev, &dev_attr_waiting_for_supplier);
2200 goto err_remove_dev_online;
2205 err_remove_dev_online:
2206 device_remove_file(dev, &dev_attr_online);
2207 err_remove_dev_groups:
2208 device_remove_groups(dev, dev->groups);
2209 err_remove_type_groups:
2211 device_remove_groups(dev, type->groups);
2212 err_remove_class_groups:
2214 device_remove_groups(dev, class->dev_groups);
2219 static void device_remove_attrs(struct device *dev)
2221 struct class *class = dev->class;
2222 const struct device_type *type = dev->type;
2224 device_remove_file(dev, &dev_attr_waiting_for_supplier);
2225 device_remove_file(dev, &dev_attr_online);
2226 device_remove_groups(dev, dev->groups);
2229 device_remove_groups(dev, type->groups);
2232 device_remove_groups(dev, class->dev_groups);
2235 static ssize_t dev_show(struct device *dev, struct device_attribute *attr,
2238 return print_dev_t(buf, dev->devt);
2240 static DEVICE_ATTR_RO(dev);
2243 struct kset *devices_kset;
2246 * devices_kset_move_before - Move device in the devices_kset's list.
2247 * @deva: Device to move.
2248 * @devb: Device @deva should come before.
2250 static void devices_kset_move_before(struct device *deva, struct device *devb)
2254 pr_debug("devices_kset: Moving %s before %s\n",
2255 dev_name(deva), dev_name(devb));
2256 spin_lock(&devices_kset->list_lock);
2257 list_move_tail(&deva->kobj.entry, &devb->kobj.entry);
2258 spin_unlock(&devices_kset->list_lock);
2262 * devices_kset_move_after - Move device in the devices_kset's list.
2263 * @deva: Device to move
2264 * @devb: Device @deva should come after.
2266 static void devices_kset_move_after(struct device *deva, struct device *devb)
2270 pr_debug("devices_kset: Moving %s after %s\n",
2271 dev_name(deva), dev_name(devb));
2272 spin_lock(&devices_kset->list_lock);
2273 list_move(&deva->kobj.entry, &devb->kobj.entry);
2274 spin_unlock(&devices_kset->list_lock);
2278 * devices_kset_move_last - move the device to the end of devices_kset's list.
2279 * @dev: device to move
2281 void devices_kset_move_last(struct device *dev)
2285 pr_debug("devices_kset: Moving %s to end of list\n", dev_name(dev));
2286 spin_lock(&devices_kset->list_lock);
2287 list_move_tail(&dev->kobj.entry, &devices_kset->list);
2288 spin_unlock(&devices_kset->list_lock);
2292 * device_create_file - create sysfs attribute file for device.
2294 * @attr: device attribute descriptor.
2296 int device_create_file(struct device *dev,
2297 const struct device_attribute *attr)
2302 WARN(((attr->attr.mode & S_IWUGO) && !attr->store),
2303 "Attribute %s: write permission without 'store'\n",
2305 WARN(((attr->attr.mode & S_IRUGO) && !attr->show),
2306 "Attribute %s: read permission without 'show'\n",
2308 error = sysfs_create_file(&dev->kobj, &attr->attr);
2313 EXPORT_SYMBOL_GPL(device_create_file);
2316 * device_remove_file - remove sysfs attribute file.
2318 * @attr: device attribute descriptor.
2320 void device_remove_file(struct device *dev,
2321 const struct device_attribute *attr)
2324 sysfs_remove_file(&dev->kobj, &attr->attr);
2326 EXPORT_SYMBOL_GPL(device_remove_file);
2329 * device_remove_file_self - remove sysfs attribute file from its own method.
2331 * @attr: device attribute descriptor.
2333 * See kernfs_remove_self() for details.
2335 bool device_remove_file_self(struct device *dev,
2336 const struct device_attribute *attr)
2339 return sysfs_remove_file_self(&dev->kobj, &attr->attr);
2343 EXPORT_SYMBOL_GPL(device_remove_file_self);
2346 * device_create_bin_file - create sysfs binary attribute file for device.
2348 * @attr: device binary attribute descriptor.
2350 int device_create_bin_file(struct device *dev,
2351 const struct bin_attribute *attr)
2353 int error = -EINVAL;
2355 error = sysfs_create_bin_file(&dev->kobj, attr);
2358 EXPORT_SYMBOL_GPL(device_create_bin_file);
2361 * device_remove_bin_file - remove sysfs binary attribute file
2363 * @attr: device binary attribute descriptor.
2365 void device_remove_bin_file(struct device *dev,
2366 const struct bin_attribute *attr)
2369 sysfs_remove_bin_file(&dev->kobj, attr);
2371 EXPORT_SYMBOL_GPL(device_remove_bin_file);
2373 static void klist_children_get(struct klist_node *n)
2375 struct device_private *p = to_device_private_parent(n);
2376 struct device *dev = p->device;
2381 static void klist_children_put(struct klist_node *n)
2383 struct device_private *p = to_device_private_parent(n);
2384 struct device *dev = p->device;
2390 * device_initialize - init device structure.
2393 * This prepares the device for use by other layers by initializing
2395 * It is the first half of device_register(), if called by
2396 * that function, though it can also be called separately, so one
2397 * may use @dev's fields. In particular, get_device()/put_device()
2398 * may be used for reference counting of @dev after calling this
2401 * All fields in @dev must be initialized by the caller to 0, except
2402 * for those explicitly set to some other value. The simplest
2403 * approach is to use kzalloc() to allocate the structure containing
2406 * NOTE: Use put_device() to give up your reference instead of freeing
2407 * @dev directly once you have called this function.
2409 void device_initialize(struct device *dev)
2411 dev->kobj.kset = devices_kset;
2412 kobject_init(&dev->kobj, &device_ktype);
2413 INIT_LIST_HEAD(&dev->dma_pools);
2414 mutex_init(&dev->mutex);
2415 #ifdef CONFIG_PROVE_LOCKING
2416 mutex_init(&dev->lockdep_mutex);
2418 lockdep_set_novalidate_class(&dev->mutex);
2419 spin_lock_init(&dev->devres_lock);
2420 INIT_LIST_HEAD(&dev->devres_head);
2421 device_pm_init(dev);
2422 set_dev_node(dev, -1);
2423 #ifdef CONFIG_GENERIC_MSI_IRQ
2424 INIT_LIST_HEAD(&dev->msi_list);
2426 INIT_LIST_HEAD(&dev->links.consumers);
2427 INIT_LIST_HEAD(&dev->links.suppliers);
2428 INIT_LIST_HEAD(&dev->links.needs_suppliers);
2429 INIT_LIST_HEAD(&dev->links.defer_hook);
2430 dev->links.status = DL_DEV_NO_DRIVER;
2432 EXPORT_SYMBOL_GPL(device_initialize);
2434 struct kobject *virtual_device_parent(struct device *dev)
2436 static struct kobject *virtual_dir = NULL;
2439 virtual_dir = kobject_create_and_add("virtual",
2440 &devices_kset->kobj);
2446 struct kobject kobj;
2447 struct class *class;
2450 #define to_class_dir(obj) container_of(obj, struct class_dir, kobj)
2452 static void class_dir_release(struct kobject *kobj)
2454 struct class_dir *dir = to_class_dir(kobj);
2459 struct kobj_ns_type_operations *class_dir_child_ns_type(struct kobject *kobj)
2461 struct class_dir *dir = to_class_dir(kobj);
2462 return dir->class->ns_type;
2465 static struct kobj_type class_dir_ktype = {
2466 .release = class_dir_release,
2467 .sysfs_ops = &kobj_sysfs_ops,
2468 .child_ns_type = class_dir_child_ns_type
2471 static struct kobject *
2472 class_dir_create_and_add(struct class *class, struct kobject *parent_kobj)
2474 struct class_dir *dir;
2477 dir = kzalloc(sizeof(*dir), GFP_KERNEL);
2479 return ERR_PTR(-ENOMEM);
2482 kobject_init(&dir->kobj, &class_dir_ktype);
2484 dir->kobj.kset = &class->p->glue_dirs;
2486 retval = kobject_add(&dir->kobj, parent_kobj, "%s", class->name);
2488 kobject_put(&dir->kobj);
2489 return ERR_PTR(retval);
2494 static DEFINE_MUTEX(gdp_mutex);
2496 static struct kobject *get_device_parent(struct device *dev,
2497 struct device *parent)
2500 struct kobject *kobj = NULL;
2501 struct kobject *parent_kobj;
2505 /* block disks show up in /sys/block */
2506 if (sysfs_deprecated && dev->class == &block_class) {
2507 if (parent && parent->class == &block_class)
2508 return &parent->kobj;
2509 return &block_class.p->subsys.kobj;
2514 * If we have no parent, we live in "virtual".
2515 * Class-devices with a non class-device as parent, live
2516 * in a "glue" directory to prevent namespace collisions.
2519 parent_kobj = virtual_device_parent(dev);
2520 else if (parent->class && !dev->class->ns_type)
2521 return &parent->kobj;
2523 parent_kobj = &parent->kobj;
2525 mutex_lock(&gdp_mutex);
2527 /* find our class-directory at the parent and reference it */
2528 spin_lock(&dev->class->p->glue_dirs.list_lock);
2529 list_for_each_entry(k, &dev->class->p->glue_dirs.list, entry)
2530 if (k->parent == parent_kobj) {
2531 kobj = kobject_get(k);
2534 spin_unlock(&dev->class->p->glue_dirs.list_lock);
2536 mutex_unlock(&gdp_mutex);
2540 /* or create a new class-directory at the parent device */
2541 k = class_dir_create_and_add(dev->class, parent_kobj);
2542 /* do not emit an uevent for this simple "glue" directory */
2543 mutex_unlock(&gdp_mutex);
2547 /* subsystems can specify a default root directory for their devices */
2548 if (!parent && dev->bus && dev->bus->dev_root)
2549 return &dev->bus->dev_root->kobj;
2552 return &parent->kobj;
2556 static inline bool live_in_glue_dir(struct kobject *kobj,
2559 if (!kobj || !dev->class ||
2560 kobj->kset != &dev->class->p->glue_dirs)
2565 static inline struct kobject *get_glue_dir(struct device *dev)
2567 return dev->kobj.parent;
2571 * make sure cleaning up dir as the last step, we need to make
2572 * sure .release handler of kobject is run with holding the
2575 static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
2579 /* see if we live in a "glue" directory */
2580 if (!live_in_glue_dir(glue_dir, dev))
2583 mutex_lock(&gdp_mutex);
2585 * There is a race condition between removing glue directory
2586 * and adding a new device under the glue directory.
2591 * get_device_parent()
2592 * class_dir_create_and_add()
2593 * kobject_add_internal()
2594 * create_dir() // create glue_dir
2597 * get_device_parent()
2598 * kobject_get() // get glue_dir
2601 * cleanup_glue_dir()
2602 * kobject_del(glue_dir)
2605 * kobject_add_internal()
2606 * create_dir() // in glue_dir
2607 * sysfs_create_dir_ns()
2608 * kernfs_create_dir_ns(sd)
2610 * sysfs_remove_dir() // glue_dir->sd=NULL
2611 * sysfs_put() // free glue_dir->sd
2614 * kernfs_new_node(sd)
2615 * kernfs_get(glue_dir)
2619 * Before CPU1 remove last child device under glue dir, if CPU2 add
2620 * a new device under glue dir, the glue_dir kobject reference count
2621 * will be increase to 2 in kobject_get(k). And CPU2 has been called
2622 * kernfs_create_dir_ns(). Meanwhile, CPU1 call sysfs_remove_dir()
2623 * and sysfs_put(). This result in glue_dir->sd is freed.
2625 * Then the CPU2 will see a stale "empty" but still potentially used
2626 * glue dir around in kernfs_new_node().
2628 * In order to avoid this happening, we also should make sure that
2629 * kernfs_node for glue_dir is released in CPU1 only when refcount
2630 * for glue_dir kobj is 1.
2632 ref = kref_read(&glue_dir->kref);
2633 if (!kobject_has_children(glue_dir) && !--ref)
2634 kobject_del(glue_dir);
2635 kobject_put(glue_dir);
2636 mutex_unlock(&gdp_mutex);
2639 static int device_add_class_symlinks(struct device *dev)
2641 struct device_node *of_node = dev_of_node(dev);
2645 error = sysfs_create_link(&dev->kobj, of_node_kobj(of_node), "of_node");
2647 dev_warn(dev, "Error %d creating of_node link\n",error);
2648 /* An error here doesn't warrant bringing down the device */
2654 error = sysfs_create_link(&dev->kobj,
2655 &dev->class->p->subsys.kobj,
2660 if (dev->parent && device_is_not_partition(dev)) {
2661 error = sysfs_create_link(&dev->kobj, &dev->parent->kobj,
2668 /* /sys/block has directories and does not need symlinks */
2669 if (sysfs_deprecated && dev->class == &block_class)
2673 /* link in the class directory pointing to the device */
2674 error = sysfs_create_link(&dev->class->p->subsys.kobj,
2675 &dev->kobj, dev_name(dev));
2682 sysfs_remove_link(&dev->kobj, "device");
2685 sysfs_remove_link(&dev->kobj, "subsystem");
2687 sysfs_remove_link(&dev->kobj, "of_node");
2691 static void device_remove_class_symlinks(struct device *dev)
2693 if (dev_of_node(dev))
2694 sysfs_remove_link(&dev->kobj, "of_node");
2699 if (dev->parent && device_is_not_partition(dev))
2700 sysfs_remove_link(&dev->kobj, "device");
2701 sysfs_remove_link(&dev->kobj, "subsystem");
2703 if (sysfs_deprecated && dev->class == &block_class)
2706 sysfs_delete_link(&dev->class->p->subsys.kobj, &dev->kobj, dev_name(dev));
2710 * dev_set_name - set a device name
2712 * @fmt: format string for the device's name
2714 int dev_set_name(struct device *dev, const char *fmt, ...)
2719 va_start(vargs, fmt);
2720 err = kobject_set_name_vargs(&dev->kobj, fmt, vargs);
2724 EXPORT_SYMBOL_GPL(dev_set_name);
2727 * device_to_dev_kobj - select a /sys/dev/ directory for the device
2730 * By default we select char/ for new entries. Setting class->dev_obj
2731 * to NULL prevents an entry from being created. class->dev_kobj must
2732 * be set (or cleared) before any devices are registered to the class
2733 * otherwise device_create_sys_dev_entry() and
2734 * device_remove_sys_dev_entry() will disagree about the presence of
2737 static struct kobject *device_to_dev_kobj(struct device *dev)
2739 struct kobject *kobj;
2742 kobj = dev->class->dev_kobj;
2744 kobj = sysfs_dev_char_kobj;
2749 static int device_create_sys_dev_entry(struct device *dev)
2751 struct kobject *kobj = device_to_dev_kobj(dev);
2756 format_dev_t(devt_str, dev->devt);
2757 error = sysfs_create_link(kobj, &dev->kobj, devt_str);
2763 static void device_remove_sys_dev_entry(struct device *dev)
2765 struct kobject *kobj = device_to_dev_kobj(dev);
2769 format_dev_t(devt_str, dev->devt);
2770 sysfs_remove_link(kobj, devt_str);
2774 static int device_private_init(struct device *dev)
2776 dev->p = kzalloc(sizeof(*dev->p), GFP_KERNEL);
2779 dev->p->device = dev;
2780 klist_init(&dev->p->klist_children, klist_children_get,
2781 klist_children_put);
2782 INIT_LIST_HEAD(&dev->p->deferred_probe);
2787 * device_add - add device to device hierarchy.
2790 * This is part 2 of device_register(), though may be called
2791 * separately _iff_ device_initialize() has been called separately.
2793 * This adds @dev to the kobject hierarchy via kobject_add(), adds it
2794 * to the global and sibling lists for the device, then
2795 * adds it to the other relevant subsystems of the driver model.
2797 * Do not call this routine or device_register() more than once for
2798 * any device structure. The driver model core is not designed to work
2799 * with devices that get unregistered and then spring back to life.
2800 * (Among other things, it's very hard to guarantee that all references
2801 * to the previous incarnation of @dev have been dropped.) Allocate
2802 * and register a fresh new struct device instead.
2804 * NOTE: _Never_ directly free @dev after calling this function, even
2805 * if it returned an error! Always use put_device() to give up your
2806 * reference instead.
2808 * Rule of thumb is: if device_add() succeeds, you should call
2809 * device_del() when you want to get rid of it. If device_add() has
2810 * *not* succeeded, use *only* put_device() to drop the reference
2813 int device_add(struct device *dev)
2815 struct device *parent;
2816 struct kobject *kobj;
2817 struct class_interface *class_intf;
2818 int error = -EINVAL;
2819 struct kobject *glue_dir = NULL;
2821 dev = get_device(dev);
2826 error = device_private_init(dev);
2832 * for statically allocated devices, which should all be converted
2833 * some day, we need to initialize the name. We prevent reading back
2834 * the name, and force the use of dev_name()
2836 if (dev->init_name) {
2837 dev_set_name(dev, "%s", dev->init_name);
2838 dev->init_name = NULL;
2841 /* subsystems can specify simple device enumeration */
2842 if (!dev_name(dev) && dev->bus && dev->bus->dev_name)
2843 dev_set_name(dev, "%s%u", dev->bus->dev_name, dev->id);
2845 if (!dev_name(dev)) {
2850 pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
2852 parent = get_device(dev->parent);
2853 kobj = get_device_parent(dev, parent);
2855 error = PTR_ERR(kobj);
2859 dev->kobj.parent = kobj;
2861 /* use parent numa_node */
2862 if (parent && (dev_to_node(dev) == NUMA_NO_NODE))
2863 set_dev_node(dev, dev_to_node(parent));
2865 /* first, register with generic layer. */
2866 /* we require the name to be set before, and pass NULL */
2867 error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);
2869 glue_dir = get_glue_dir(dev);
2873 /* notify platform of device entry */
2874 error = device_platform_notify(dev, KOBJ_ADD);
2876 goto platform_error;
2878 error = device_create_file(dev, &dev_attr_uevent);
2882 error = device_add_class_symlinks(dev);
2885 error = device_add_attrs(dev);
2888 error = bus_add_device(dev);
2891 error = dpm_sysfs_add(dev);
2896 if (MAJOR(dev->devt)) {
2897 error = device_create_file(dev, &dev_attr_dev);
2901 error = device_create_sys_dev_entry(dev);
2905 devtmpfs_create_node(dev);
2908 /* Notify clients of device addition. This call must come
2909 * after dpm_sysfs_add() and before kobject_uevent().
2912 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
2913 BUS_NOTIFY_ADD_DEVICE, dev);
2915 kobject_uevent(&dev->kobj, KOBJ_ADD);
2918 * Check if any of the other devices (consumers) have been waiting for
2919 * this device (supplier) to be added so that they can create a device
2922 * This needs to happen after device_pm_add() because device_link_add()
2923 * requires the supplier be registered before it's called.
2925 * But this also needs to happen before bus_probe_device() to make sure
2926 * waiting consumers can link to it before the driver is bound to the
2927 * device and the driver sync_state callback is called for this device.
2929 if (dev->fwnode && !dev->fwnode->dev) {
2930 dev->fwnode->dev = dev;
2931 fw_devlink_link_device(dev);
2934 bus_probe_device(dev);
2936 klist_add_tail(&dev->p->knode_parent,
2937 &parent->p->klist_children);
2940 mutex_lock(&dev->class->p->mutex);
2941 /* tie the class to the device */
2942 klist_add_tail(&dev->p->knode_class,
2943 &dev->class->p->klist_devices);
2945 /* notify any interfaces that the device is here */
2946 list_for_each_entry(class_intf,
2947 &dev->class->p->interfaces, node)
2948 if (class_intf->add_dev)
2949 class_intf->add_dev(dev, class_intf);
2950 mutex_unlock(&dev->class->p->mutex);
2956 if (MAJOR(dev->devt))
2957 device_remove_file(dev, &dev_attr_dev);
2959 device_pm_remove(dev);
2960 dpm_sysfs_remove(dev);
2962 bus_remove_device(dev);
2964 device_remove_attrs(dev);
2966 device_remove_class_symlinks(dev);
2968 device_remove_file(dev, &dev_attr_uevent);
2970 device_platform_notify(dev, KOBJ_REMOVE);
2972 kobject_uevent(&dev->kobj, KOBJ_REMOVE);
2973 glue_dir = get_glue_dir(dev);
2974 kobject_del(&dev->kobj);
2976 cleanup_glue_dir(dev, glue_dir);
2984 EXPORT_SYMBOL_GPL(device_add);
2987 * device_register - register a device with the system.
2988 * @dev: pointer to the device structure
2990 * This happens in two clean steps - initialize the device
2991 * and add it to the system. The two steps can be called
2992 * separately, but this is the easiest and most common.
2993 * I.e. you should only call the two helpers separately if
2994 * have a clearly defined need to use and refcount the device
2995 * before it is added to the hierarchy.
2997 * For more information, see the kerneldoc for device_initialize()
3000 * NOTE: _Never_ directly free @dev after calling this function, even
3001 * if it returned an error! Always use put_device() to give up the
3002 * reference initialized in this function instead.
3004 int device_register(struct device *dev)
3006 device_initialize(dev);
3007 return device_add(dev);
3009 EXPORT_SYMBOL_GPL(device_register);
3012 * get_device - increment reference count for device.
3015 * This simply forwards the call to kobject_get(), though
3016 * we do take care to provide for the case that we get a NULL
3017 * pointer passed in.
3019 struct device *get_device(struct device *dev)
3021 return dev ? kobj_to_dev(kobject_get(&dev->kobj)) : NULL;
3023 EXPORT_SYMBOL_GPL(get_device);
3026 * put_device - decrement reference count.
3027 * @dev: device in question.
3029 void put_device(struct device *dev)
3031 /* might_sleep(); */
3033 kobject_put(&dev->kobj);
3035 EXPORT_SYMBOL_GPL(put_device);
3037 bool kill_device(struct device *dev)
3040 * Require the device lock and set the "dead" flag to guarantee that
3041 * the update behavior is consistent with the other bitfields near
3042 * it and that we cannot have an asynchronous probe routine trying
3043 * to run while we are tearing out the bus/class/sysfs from
3044 * underneath the device.
3046 lockdep_assert_held(&dev->mutex);
3050 dev->p->dead = true;
3053 EXPORT_SYMBOL_GPL(kill_device);
3056 * device_del - delete device from system.
3059 * This is the first part of the device unregistration
3060 * sequence. This removes the device from the lists we control
3061 * from here, has it removed from the other driver model
3062 * subsystems it was added to in device_add(), and removes it
3063 * from the kobject hierarchy.
3065 * NOTE: this should be called manually _iff_ device_add() was
3066 * also called manually.
3068 void device_del(struct device *dev)
3070 struct device *parent = dev->parent;
3071 struct kobject *glue_dir = NULL;
3072 struct class_interface *class_intf;
3073 unsigned int noio_flag;
3079 if (dev->fwnode && dev->fwnode->dev == dev)
3080 dev->fwnode->dev = NULL;
3082 /* Notify clients of device removal. This call must come
3083 * before dpm_sysfs_remove().
3085 noio_flag = memalloc_noio_save();
3087 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
3088 BUS_NOTIFY_DEL_DEVICE, dev);
3090 dpm_sysfs_remove(dev);
3092 klist_del(&dev->p->knode_parent);
3093 if (MAJOR(dev->devt)) {
3094 devtmpfs_delete_node(dev);
3095 device_remove_sys_dev_entry(dev);
3096 device_remove_file(dev, &dev_attr_dev);
3099 device_remove_class_symlinks(dev);
3101 mutex_lock(&dev->class->p->mutex);
3102 /* notify any interfaces that the device is now gone */
3103 list_for_each_entry(class_intf,
3104 &dev->class->p->interfaces, node)
3105 if (class_intf->remove_dev)
3106 class_intf->remove_dev(dev, class_intf);
3107 /* remove the device from the class list */
3108 klist_del(&dev->p->knode_class);
3109 mutex_unlock(&dev->class->p->mutex);
3111 device_remove_file(dev, &dev_attr_uevent);
3112 device_remove_attrs(dev);
3113 bus_remove_device(dev);
3114 device_pm_remove(dev);
3115 driver_deferred_probe_del(dev);
3116 device_platform_notify(dev, KOBJ_REMOVE);
3117 device_remove_properties(dev);
3118 device_links_purge(dev);
3121 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
3122 BUS_NOTIFY_REMOVED_DEVICE, dev);
3123 kobject_uevent(&dev->kobj, KOBJ_REMOVE);
3124 glue_dir = get_glue_dir(dev);
3125 kobject_del(&dev->kobj);
3126 cleanup_glue_dir(dev, glue_dir);
3127 memalloc_noio_restore(noio_flag);
3130 EXPORT_SYMBOL_GPL(device_del);
3133 * device_unregister - unregister device from system.
3134 * @dev: device going away.
3136 * We do this in two parts, like we do device_register(). First,
3137 * we remove it from all the subsystems with device_del(), then
3138 * we decrement the reference count via put_device(). If that
3139 * is the final reference count, the device will be cleaned up
3140 * via device_release() above. Otherwise, the structure will
3141 * stick around until the final reference to the device is dropped.
3143 void device_unregister(struct device *dev)
3145 pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
3149 EXPORT_SYMBOL_GPL(device_unregister);
3151 static struct device *prev_device(struct klist_iter *i)
3153 struct klist_node *n = klist_prev(i);
3154 struct device *dev = NULL;
3155 struct device_private *p;
3158 p = to_device_private_parent(n);
3164 static struct device *next_device(struct klist_iter *i)
3166 struct klist_node *n = klist_next(i);
3167 struct device *dev = NULL;
3168 struct device_private *p;
3171 p = to_device_private_parent(n);
3178 * device_get_devnode - path of device node file
3180 * @mode: returned file access mode
3181 * @uid: returned file owner
3182 * @gid: returned file group
3183 * @tmp: possibly allocated string
3185 * Return the relative path of a possible device node.
3186 * Non-default names may need to allocate a memory to compose
3187 * a name. This memory is returned in tmp and needs to be
3188 * freed by the caller.
3190 const char *device_get_devnode(struct device *dev,
3191 umode_t *mode, kuid_t *uid, kgid_t *gid,
3198 /* the device type may provide a specific name */
3199 if (dev->type && dev->type->devnode)
3200 *tmp = dev->type->devnode(dev, mode, uid, gid);
3204 /* the class may provide a specific name */
3205 if (dev->class && dev->class->devnode)
3206 *tmp = dev->class->devnode(dev, mode);
3210 /* return name without allocation, tmp == NULL */
3211 if (strchr(dev_name(dev), '!') == NULL)
3212 return dev_name(dev);
3214 /* replace '!' in the name with '/' */
3215 s = kstrdup(dev_name(dev), GFP_KERNEL);
3218 strreplace(s, '!', '/');
3223 * device_for_each_child - device child iterator.
3224 * @parent: parent struct device.
3225 * @fn: function to be called for each device.
3226 * @data: data for the callback.
3228 * Iterate over @parent's child devices, and call @fn for each,
3231 * We check the return of @fn each time. If it returns anything
3232 * other than 0, we break out and return that value.
3234 int device_for_each_child(struct device *parent, void *data,
3235 int (*fn)(struct device *dev, void *data))
3237 struct klist_iter i;
3238 struct device *child;
3244 klist_iter_init(&parent->p->klist_children, &i);
3245 while (!error && (child = next_device(&i)))
3246 error = fn(child, data);
3247 klist_iter_exit(&i);
3250 EXPORT_SYMBOL_GPL(device_for_each_child);
3253 * device_for_each_child_reverse - device child iterator in reversed order.
3254 * @parent: parent struct device.
3255 * @fn: function to be called for each device.
3256 * @data: data for the callback.
3258 * Iterate over @parent's child devices, and call @fn for each,
3261 * We check the return of @fn each time. If it returns anything
3262 * other than 0, we break out and return that value.
3264 int device_for_each_child_reverse(struct device *parent, void *data,
3265 int (*fn)(struct device *dev, void *data))
3267 struct klist_iter i;
3268 struct device *child;
3274 klist_iter_init(&parent->p->klist_children, &i);
3275 while ((child = prev_device(&i)) && !error)
3276 error = fn(child, data);
3277 klist_iter_exit(&i);
3280 EXPORT_SYMBOL_GPL(device_for_each_child_reverse);
3283 * device_find_child - device iterator for locating a particular device.
3284 * @parent: parent struct device
3285 * @match: Callback function to check device
3286 * @data: Data to pass to match function
3288 * This is similar to the device_for_each_child() function above, but it
3289 * returns a reference to a device that is 'found' for later use, as
3290 * determined by the @match callback.
3292 * The callback should return 0 if the device doesn't match and non-zero
3293 * if it does. If the callback returns non-zero and a reference to the
3294 * current device can be obtained, this function will return to the caller
3295 * and not iterate over any more devices.
3297 * NOTE: you will need to drop the reference with put_device() after use.
3299 struct device *device_find_child(struct device *parent, void *data,
3300 int (*match)(struct device *dev, void *data))
3302 struct klist_iter i;
3303 struct device *child;
3308 klist_iter_init(&parent->p->klist_children, &i);
3309 while ((child = next_device(&i)))
3310 if (match(child, data) && get_device(child))
3312 klist_iter_exit(&i);
3315 EXPORT_SYMBOL_GPL(device_find_child);
3318 * device_find_child_by_name - device iterator for locating a child device.
3319 * @parent: parent struct device
3320 * @name: name of the child device
3322 * This is similar to the device_find_child() function above, but it
3323 * returns a reference to a device that has the name @name.
3325 * NOTE: you will need to drop the reference with put_device() after use.
3327 struct device *device_find_child_by_name(struct device *parent,
3330 struct klist_iter i;
3331 struct device *child;
3336 klist_iter_init(&parent->p->klist_children, &i);
3337 while ((child = next_device(&i)))
3338 if (sysfs_streq(dev_name(child), name) && get_device(child))
3340 klist_iter_exit(&i);
3343 EXPORT_SYMBOL_GPL(device_find_child_by_name);
3345 int __init devices_init(void)
3347 devices_kset = kset_create_and_add("devices", &device_uevent_ops, NULL);
3350 dev_kobj = kobject_create_and_add("dev", NULL);
3353 sysfs_dev_block_kobj = kobject_create_and_add("block", dev_kobj);
3354 if (!sysfs_dev_block_kobj)
3355 goto block_kobj_err;
3356 sysfs_dev_char_kobj = kobject_create_and_add("char", dev_kobj);
3357 if (!sysfs_dev_char_kobj)
3363 kobject_put(sysfs_dev_block_kobj);
3365 kobject_put(dev_kobj);
3367 kset_unregister(devices_kset);
3371 static int device_check_offline(struct device *dev, void *not_used)
3375 ret = device_for_each_child(dev, NULL, device_check_offline);
3379 return device_supports_offline(dev) && !dev->offline ? -EBUSY : 0;
3383 * device_offline - Prepare the device for hot-removal.
3384 * @dev: Device to be put offline.
3386 * Execute the device bus type's .offline() callback, if present, to prepare
3387 * the device for a subsequent hot-removal. If that succeeds, the device must
3388 * not be used until either it is removed or its bus type's .online() callback
3391 * Call under device_hotplug_lock.
3393 int device_offline(struct device *dev)
3397 if (dev->offline_disabled)
3400 ret = device_for_each_child(dev, NULL, device_check_offline);
3405 if (device_supports_offline(dev)) {
3409 ret = dev->bus->offline(dev);
3411 kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
3412 dev->offline = true;
3422 * device_online - Put the device back online after successful device_offline().
3423 * @dev: Device to be put back online.
3425 * If device_offline() has been successfully executed for @dev, but the device
3426 * has not been removed subsequently, execute its bus type's .online() callback
3427 * to indicate that the device can be used again.
3429 * Call under device_hotplug_lock.
3431 int device_online(struct device *dev)
3436 if (device_supports_offline(dev)) {
3438 ret = dev->bus->online(dev);
3440 kobject_uevent(&dev->kobj, KOBJ_ONLINE);
3441 dev->offline = false;
3452 struct root_device {
3454 struct module *owner;
3457 static inline struct root_device *to_root_device(struct device *d)
3459 return container_of(d, struct root_device, dev);
3462 static void root_device_release(struct device *dev)
3464 kfree(to_root_device(dev));
3468 * __root_device_register - allocate and register a root device
3469 * @name: root device name
3470 * @owner: owner module of the root device, usually THIS_MODULE
3472 * This function allocates a root device and registers it
3473 * using device_register(). In order to free the returned
3474 * device, use root_device_unregister().
3476 * Root devices are dummy devices which allow other devices
3477 * to be grouped under /sys/devices. Use this function to
3478 * allocate a root device and then use it as the parent of
3479 * any device which should appear under /sys/devices/{name}
3481 * The /sys/devices/{name} directory will also contain a
3482 * 'module' symlink which points to the @owner directory
3485 * Returns &struct device pointer on success, or ERR_PTR() on error.
3487 * Note: You probably want to use root_device_register().
3489 struct device *__root_device_register(const char *name, struct module *owner)
3491 struct root_device *root;
3494 root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
3496 return ERR_PTR(err);
3498 err = dev_set_name(&root->dev, "%s", name);
3501 return ERR_PTR(err);
3504 root->dev.release = root_device_release;
3506 err = device_register(&root->dev);
3508 put_device(&root->dev);
3509 return ERR_PTR(err);
3512 #ifdef CONFIG_MODULES /* gotta find a "cleaner" way to do this */
3514 struct module_kobject *mk = &owner->mkobj;
3516 err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
3518 device_unregister(&root->dev);
3519 return ERR_PTR(err);
3521 root->owner = owner;
3527 EXPORT_SYMBOL_GPL(__root_device_register);
3530 * root_device_unregister - unregister and free a root device
3531 * @dev: device going away
3533 * This function unregisters and cleans up a device that was created by
3534 * root_device_register().
3536 void root_device_unregister(struct device *dev)
3538 struct root_device *root = to_root_device(dev);
3541 sysfs_remove_link(&root->dev.kobj, "module");
3543 device_unregister(dev);
3545 EXPORT_SYMBOL_GPL(root_device_unregister);
3548 static void device_create_release(struct device *dev)
3550 pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
3554 static __printf(6, 0) struct device *
3555 device_create_groups_vargs(struct class *class, struct device *parent,
3556 dev_t devt, void *drvdata,
3557 const struct attribute_group **groups,
3558 const char *fmt, va_list args)
3560 struct device *dev = NULL;
3561 int retval = -ENODEV;
3563 if (class == NULL || IS_ERR(class))
3566 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
3572 device_initialize(dev);
3575 dev->parent = parent;
3576 dev->groups = groups;
3577 dev->release = device_create_release;
3578 dev_set_drvdata(dev, drvdata);
3580 retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
3584 retval = device_add(dev);
3592 return ERR_PTR(retval);
3596 * device_create - creates a device and registers it with sysfs
3597 * @class: pointer to the struct class that this device should be registered to
3598 * @parent: pointer to the parent struct device of this new device, if any
3599 * @devt: the dev_t for the char device to be added
3600 * @drvdata: the data to be added to the device for callbacks
3601 * @fmt: string for the device's name
3603 * This function can be used by char device classes. A struct device
3604 * will be created in sysfs, registered to the specified class.
3606 * A "dev" file will be created, showing the dev_t for the device, if
3607 * the dev_t is not 0,0.
3608 * If a pointer to a parent struct device is passed in, the newly created
3609 * struct device will be a child of that device in sysfs.
3610 * The pointer to the struct device will be returned from the call.
3611 * Any further sysfs files that might be required can be created using this
3614 * Returns &struct device pointer on success, or ERR_PTR() on error.
3616 * Note: the struct class passed to this function must have previously
3617 * been created with a call to class_create().
3619 struct device *device_create(struct class *class, struct device *parent,
3620 dev_t devt, void *drvdata, const char *fmt, ...)
3625 va_start(vargs, fmt);
3626 dev = device_create_groups_vargs(class, parent, devt, drvdata, NULL,
3631 EXPORT_SYMBOL_GPL(device_create);
3634 * device_create_with_groups - creates a device and registers it with sysfs
3635 * @class: pointer to the struct class that this device should be registered to
3636 * @parent: pointer to the parent struct device of this new device, if any
3637 * @devt: the dev_t for the char device to be added
3638 * @drvdata: the data to be added to the device for callbacks
3639 * @groups: NULL-terminated list of attribute groups to be created
3640 * @fmt: string for the device's name
3642 * This function can be used by char device classes. A struct device
3643 * will be created in sysfs, registered to the specified class.
3644 * Additional attributes specified in the groups parameter will also
3645 * be created automatically.
3647 * A "dev" file will be created, showing the dev_t for the device, if
3648 * the dev_t is not 0,0.
3649 * If a pointer to a parent struct device is passed in, the newly created
3650 * struct device will be a child of that device in sysfs.
3651 * The pointer to the struct device will be returned from the call.
3652 * Any further sysfs files that might be required can be created using this
3655 * Returns &struct device pointer on success, or ERR_PTR() on error.
3657 * Note: the struct class passed to this function must have previously
3658 * been created with a call to class_create().
3660 struct device *device_create_with_groups(struct class *class,
3661 struct device *parent, dev_t devt,
3663 const struct attribute_group **groups,
3664 const char *fmt, ...)
3669 va_start(vargs, fmt);
3670 dev = device_create_groups_vargs(class, parent, devt, drvdata, groups,
3675 EXPORT_SYMBOL_GPL(device_create_with_groups);
3678 * device_destroy - removes a device that was created with device_create()
3679 * @class: pointer to the struct class that this device was registered with
3680 * @devt: the dev_t of the device that was previously registered
3682 * This call unregisters and cleans up a device that was created with a
3683 * call to device_create().
3685 void device_destroy(struct class *class, dev_t devt)
3689 dev = class_find_device_by_devt(class, devt);
3692 device_unregister(dev);
3695 EXPORT_SYMBOL_GPL(device_destroy);
3698 * device_rename - renames a device
3699 * @dev: the pointer to the struct device to be renamed
3700 * @new_name: the new name of the device
3702 * It is the responsibility of the caller to provide mutual
3703 * exclusion between two different calls of device_rename
3704 * on the same device to ensure that new_name is valid and
3705 * won't conflict with other devices.
3707 * Note: Don't call this function. Currently, the networking layer calls this
3708 * function, but that will change. The following text from Kay Sievers offers
3711 * Renaming devices is racy at many levels, symlinks and other stuff are not
3712 * replaced atomically, and you get a "move" uevent, but it's not easy to
3713 * connect the event to the old and new device. Device nodes are not renamed at
3714 * all, there isn't even support for that in the kernel now.
3716 * In the meantime, during renaming, your target name might be taken by another
3717 * driver, creating conflicts. Or the old name is taken directly after you
3718 * renamed it -- then you get events for the same DEVPATH, before you even see
3719 * the "move" event. It's just a mess, and nothing new should ever rely on
3720 * kernel device renaming. Besides that, it's not even implemented now for
3721 * other things than (driver-core wise very simple) network devices.
3723 * We are currently about to change network renaming in udev to completely
3724 * disallow renaming of devices in the same namespace as the kernel uses,
3725 * because we can't solve the problems properly, that arise with swapping names
3726 * of multiple interfaces without races. Means, renaming of eth[0-9]* will only
3727 * be allowed to some other name than eth[0-9]*, for the aforementioned
3730 * Make up a "real" name in the driver before you register anything, or add
3731 * some other attributes for userspace to find the device, or use udev to add
3732 * symlinks -- but never rename kernel devices later, it's a complete mess. We
3733 * don't even want to get into that and try to implement the missing pieces in
3734 * the core. We really have other pieces to fix in the driver core mess. :)
3736 int device_rename(struct device *dev, const char *new_name)
3738 struct kobject *kobj = &dev->kobj;
3739 char *old_device_name = NULL;
3742 dev = get_device(dev);
3746 dev_dbg(dev, "renaming to %s\n", new_name);
3748 old_device_name = kstrdup(dev_name(dev), GFP_KERNEL);
3749 if (!old_device_name) {
3755 error = sysfs_rename_link_ns(&dev->class->p->subsys.kobj,
3756 kobj, old_device_name,
3757 new_name, kobject_namespace(kobj));
3762 error = kobject_rename(kobj, new_name);
3769 kfree(old_device_name);
3773 EXPORT_SYMBOL_GPL(device_rename);
3775 static int device_move_class_links(struct device *dev,
3776 struct device *old_parent,
3777 struct device *new_parent)
3782 sysfs_remove_link(&dev->kobj, "device");
3784 error = sysfs_create_link(&dev->kobj, &new_parent->kobj,
3790 * device_move - moves a device to a new parent
3791 * @dev: the pointer to the struct device to be moved
3792 * @new_parent: the new parent of the device (can be NULL)
3793 * @dpm_order: how to reorder the dpm_list
3795 int device_move(struct device *dev, struct device *new_parent,
3796 enum dpm_order dpm_order)
3799 struct device *old_parent;
3800 struct kobject *new_parent_kobj;
3802 dev = get_device(dev);
3807 new_parent = get_device(new_parent);
3808 new_parent_kobj = get_device_parent(dev, new_parent);
3809 if (IS_ERR(new_parent_kobj)) {
3810 error = PTR_ERR(new_parent_kobj);
3811 put_device(new_parent);
3815 pr_debug("device: '%s': %s: moving to '%s'\n", dev_name(dev),
3816 __func__, new_parent ? dev_name(new_parent) : "<NULL>");
3817 error = kobject_move(&dev->kobj, new_parent_kobj);
3819 cleanup_glue_dir(dev, new_parent_kobj);
3820 put_device(new_parent);
3823 old_parent = dev->parent;
3824 dev->parent = new_parent;
3826 klist_remove(&dev->p->knode_parent);
3828 klist_add_tail(&dev->p->knode_parent,
3829 &new_parent->p->klist_children);
3830 set_dev_node(dev, dev_to_node(new_parent));
3834 error = device_move_class_links(dev, old_parent, new_parent);
3836 /* We ignore errors on cleanup since we're hosed anyway... */
3837 device_move_class_links(dev, new_parent, old_parent);
3838 if (!kobject_move(&dev->kobj, &old_parent->kobj)) {
3840 klist_remove(&dev->p->knode_parent);
3841 dev->parent = old_parent;
3843 klist_add_tail(&dev->p->knode_parent,
3844 &old_parent->p->klist_children);
3845 set_dev_node(dev, dev_to_node(old_parent));
3848 cleanup_glue_dir(dev, new_parent_kobj);
3849 put_device(new_parent);
3853 switch (dpm_order) {
3854 case DPM_ORDER_NONE:
3856 case DPM_ORDER_DEV_AFTER_PARENT:
3857 device_pm_move_after(dev, new_parent);
3858 devices_kset_move_after(dev, new_parent);
3860 case DPM_ORDER_PARENT_BEFORE_DEV:
3861 device_pm_move_before(new_parent, dev);
3862 devices_kset_move_before(new_parent, dev);
3864 case DPM_ORDER_DEV_LAST:
3865 device_pm_move_last(dev);
3866 devices_kset_move_last(dev);
3870 put_device(old_parent);
3876 EXPORT_SYMBOL_GPL(device_move);
3878 static int device_attrs_change_owner(struct device *dev, kuid_t kuid,
3881 struct kobject *kobj = &dev->kobj;
3882 struct class *class = dev->class;
3883 const struct device_type *type = dev->type;
3888 * Change the device groups of the device class for @dev to
3891 error = sysfs_groups_change_owner(kobj, class->dev_groups, kuid,
3899 * Change the device groups of the device type for @dev to
3902 error = sysfs_groups_change_owner(kobj, type->groups, kuid,
3908 /* Change the device groups of @dev to @kuid/@kgid. */
3909 error = sysfs_groups_change_owner(kobj, dev->groups, kuid, kgid);
3913 if (device_supports_offline(dev) && !dev->offline_disabled) {
3914 /* Change online device attributes of @dev to @kuid/@kgid. */
3915 error = sysfs_file_change_owner(kobj, dev_attr_online.attr.name,
3925 * device_change_owner - change the owner of an existing device.
3927 * @kuid: new owner's kuid
3928 * @kgid: new owner's kgid
3930 * This changes the owner of @dev and its corresponding sysfs entries to
3931 * @kuid/@kgid. This function closely mirrors how @dev was added via driver
3934 * Returns 0 on success or error code on failure.
3936 int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
3939 struct kobject *kobj = &dev->kobj;
3941 dev = get_device(dev);
3946 * Change the kobject and the default attributes and groups of the
3947 * ktype associated with it to @kuid/@kgid.
3949 error = sysfs_change_owner(kobj, kuid, kgid);
3954 * Change the uevent file for @dev to the new owner. The uevent file
3955 * was created in a separate step when @dev got added and we mirror
3958 error = sysfs_file_change_owner(kobj, dev_attr_uevent.attr.name, kuid,
3964 * Change the device groups, the device groups associated with the
3965 * device class, and the groups associated with the device type of @dev
3968 error = device_attrs_change_owner(dev, kuid, kgid);
3972 error = dpm_sysfs_change_owner(dev, kuid, kgid);
3977 if (sysfs_deprecated && dev->class == &block_class)
3982 * Change the owner of the symlink located in the class directory of
3983 * the device class associated with @dev which points to the actual
3984 * directory entry for @dev to @kuid/@kgid. This ensures that the
3985 * symlink shows the same permissions as its target.
3987 error = sysfs_link_change_owner(&dev->class->p->subsys.kobj, &dev->kobj,
3988 dev_name(dev), kuid, kgid);
3996 EXPORT_SYMBOL_GPL(device_change_owner);
3999 * device_shutdown - call ->shutdown() on each device to shutdown.
4001 void device_shutdown(void)
4003 struct device *dev, *parent;
4005 wait_for_device_probe();
4006 device_block_probing();
4010 spin_lock(&devices_kset->list_lock);
4012 * Walk the devices list backward, shutting down each in turn.
4013 * Beware that device unplug events may also start pulling
4014 * devices offline, even as the system is shutting down.
4016 while (!list_empty(&devices_kset->list)) {
4017 dev = list_entry(devices_kset->list.prev, struct device,
4021 * hold reference count of device's parent to
4022 * prevent it from being freed because parent's
4023 * lock is to be held
4025 parent = get_device(dev->parent);
4028 * Make sure the device is off the kset list, in the
4029 * event that dev->*->shutdown() doesn't remove it.
4031 list_del_init(&dev->kobj.entry);
4032 spin_unlock(&devices_kset->list_lock);
4034 /* hold lock to avoid race with probe/release */
4036 device_lock(parent);
4039 /* Don't allow any more runtime suspends */
4040 pm_runtime_get_noresume(dev);
4041 pm_runtime_barrier(dev);
4043 if (dev->class && dev->class->shutdown_pre) {
4045 dev_info(dev, "shutdown_pre\n");
4046 dev->class->shutdown_pre(dev);
4048 if (dev->bus && dev->bus->shutdown) {
4050 dev_info(dev, "shutdown\n");
4051 dev->bus->shutdown(dev);
4052 } else if (dev->driver && dev->driver->shutdown) {
4054 dev_info(dev, "shutdown\n");
4055 dev->driver->shutdown(dev);
4060 device_unlock(parent);
4065 spin_lock(&devices_kset->list_lock);
4067 spin_unlock(&devices_kset->list_lock);
4071 * Device logging functions
4074 #ifdef CONFIG_PRINTK
4076 set_dev_info(const struct device *dev, struct dev_printk_info *dev_info)
4080 memset(dev_info, 0, sizeof(*dev_info));
4083 subsys = dev->class->name;
4085 subsys = dev->bus->name;
4089 strscpy(dev_info->subsystem, subsys, sizeof(dev_info->subsystem));
4092 * Add device identifier DEVICE=:
4096 * +sound:card0 subsystem:devname
4098 if (MAJOR(dev->devt)) {
4101 if (strcmp(subsys, "block") == 0)
4106 snprintf(dev_info->device, sizeof(dev_info->device),
4107 "%c%u:%u", c, MAJOR(dev->devt), MINOR(dev->devt));
4108 } else if (strcmp(subsys, "net") == 0) {
4109 struct net_device *net = to_net_dev(dev);
4111 snprintf(dev_info->device, sizeof(dev_info->device),
4112 "n%u", net->ifindex);
4114 snprintf(dev_info->device, sizeof(dev_info->device),
4115 "+%s:%s", subsys, dev_name(dev));
4119 int dev_vprintk_emit(int level, const struct device *dev,
4120 const char *fmt, va_list args)
4122 struct dev_printk_info dev_info;
4124 set_dev_info(dev, &dev_info);
4126 return vprintk_emit(0, level, &dev_info, fmt, args);
4128 EXPORT_SYMBOL(dev_vprintk_emit);
4130 int dev_printk_emit(int level, const struct device *dev, const char *fmt, ...)
4135 va_start(args, fmt);
4137 r = dev_vprintk_emit(level, dev, fmt, args);
4143 EXPORT_SYMBOL(dev_printk_emit);
4145 static void __dev_printk(const char *level, const struct device *dev,
4146 struct va_format *vaf)
4149 dev_printk_emit(level[1] - '0', dev, "%s %s: %pV",
4150 dev_driver_string(dev), dev_name(dev), vaf);
4152 printk("%s(NULL device *): %pV", level, vaf);
4155 void dev_printk(const char *level, const struct device *dev,
4156 const char *fmt, ...)
4158 struct va_format vaf;
4161 va_start(args, fmt);
4166 __dev_printk(level, dev, &vaf);
4170 EXPORT_SYMBOL(dev_printk);
4172 #define define_dev_printk_level(func, kern_level) \
4173 void func(const struct device *dev, const char *fmt, ...) \
4175 struct va_format vaf; \
4178 va_start(args, fmt); \
4183 __dev_printk(kern_level, dev, &vaf); \
4187 EXPORT_SYMBOL(func);
4189 define_dev_printk_level(_dev_emerg, KERN_EMERG);
4190 define_dev_printk_level(_dev_alert, KERN_ALERT);
4191 define_dev_printk_level(_dev_crit, KERN_CRIT);
4192 define_dev_printk_level(_dev_err, KERN_ERR);
4193 define_dev_printk_level(_dev_warn, KERN_WARNING);
4194 define_dev_printk_level(_dev_notice, KERN_NOTICE);
4195 define_dev_printk_level(_dev_info, KERN_INFO);
4200 * dev_err_probe - probe error check and log helper
4201 * @dev: the pointer to the struct device
4202 * @err: error value to test
4203 * @fmt: printf-style format string
4204 * @...: arguments as specified in the format string
4206 * This helper implements common pattern present in probe functions for error
4207 * checking: print debug or error message depending if the error value is
4208 * -EPROBE_DEFER and propagate error upwards.
4209 * In case of -EPROBE_DEFER it sets also defer probe reason, which can be
4210 * checked later by reading devices_deferred debugfs attribute.
4211 * It replaces code sequence::
4213 * if (err != -EPROBE_DEFER)
4214 * dev_err(dev, ...);
4216 * dev_dbg(dev, ...);
4221 * return dev_err_probe(dev, err, ...);
4226 int dev_err_probe(const struct device *dev, int err, const char *fmt, ...)
4228 struct va_format vaf;
4231 va_start(args, fmt);
4235 if (err != -EPROBE_DEFER) {
4236 dev_err(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
4238 device_set_deferred_probe_reason(dev, &vaf);
4239 dev_dbg(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
4246 EXPORT_SYMBOL_GPL(dev_err_probe);
4248 static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
4250 return fwnode && !IS_ERR(fwnode->secondary);
4254 * set_primary_fwnode - Change the primary firmware node of a given device.
4255 * @dev: Device to handle.
4256 * @fwnode: New primary firmware node of the device.
4258 * Set the device's firmware node pointer to @fwnode, but if a secondary
4259 * firmware node of the device is present, preserve it.
4261 void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
4263 struct device *parent = dev->parent;
4264 struct fwnode_handle *fn = dev->fwnode;
4267 if (fwnode_is_primary(fn))
4271 WARN_ON(fwnode->secondary);
4272 fwnode->secondary = fn;
4274 dev->fwnode = fwnode;
4276 if (fwnode_is_primary(fn)) {
4277 dev->fwnode = fn->secondary;
4278 if (!(parent && fn == parent->fwnode))
4279 fn->secondary = ERR_PTR(-ENODEV);
4285 EXPORT_SYMBOL_GPL(set_primary_fwnode);
4288 * set_secondary_fwnode - Change the secondary firmware node of a given device.
4289 * @dev: Device to handle.
4290 * @fwnode: New secondary firmware node of the device.
4292 * If a primary firmware node of the device is present, set its secondary
4293 * pointer to @fwnode. Otherwise, set the device's firmware node pointer to
4296 void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
4299 fwnode->secondary = ERR_PTR(-ENODEV);
4301 if (fwnode_is_primary(dev->fwnode))
4302 dev->fwnode->secondary = fwnode;
4304 dev->fwnode = fwnode;
4306 EXPORT_SYMBOL_GPL(set_secondary_fwnode);
4309 * device_set_of_node_from_dev - reuse device-tree node of another device
4310 * @dev: device whose device-tree node is being set
4311 * @dev2: device whose device-tree node is being reused
4313 * Takes another reference to the new device-tree node after first dropping
4314 * any reference held to the old node.
4316 void device_set_of_node_from_dev(struct device *dev, const struct device *dev2)
4318 of_node_put(dev->of_node);
4319 dev->of_node = of_node_get(dev2->of_node);
4320 dev->of_node_reused = true;
4322 EXPORT_SYMBOL_GPL(device_set_of_node_from_dev);
4324 int device_match_name(struct device *dev, const void *name)
4326 return sysfs_streq(dev_name(dev), name);
4328 EXPORT_SYMBOL_GPL(device_match_name);
4330 int device_match_of_node(struct device *dev, const void *np)
4332 return dev->of_node == np;
4334 EXPORT_SYMBOL_GPL(device_match_of_node);
4336 int device_match_fwnode(struct device *dev, const void *fwnode)
4338 return dev_fwnode(dev) == fwnode;
4340 EXPORT_SYMBOL_GPL(device_match_fwnode);
4342 int device_match_devt(struct device *dev, const void *pdevt)
4344 return dev->devt == *(dev_t *)pdevt;
4346 EXPORT_SYMBOL_GPL(device_match_devt);
4348 int device_match_acpi_dev(struct device *dev, const void *adev)
4350 return ACPI_COMPANION(dev) == adev;
4352 EXPORT_SYMBOL(device_match_acpi_dev);
4354 int device_match_any(struct device *dev, const void *unused)
4358 EXPORT_SYMBOL_GPL(device_match_any);