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/kstrtox.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
20 #include <linux/kdev_t.h>
21 #include <linux/notifier.h>
23 #include <linux/of_device.h>
24 #include <linux/blkdev.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/string_helpers.h>
31 #include <linux/swiotlb.h>
32 #include <linux/sysfs.h>
33 #include <linux/dma-map-ops.h> /* for dma_default_coherent */
36 #include "physical_location.h"
37 #include "power/power.h"
39 /* Device links support. */
40 static LIST_HEAD(deferred_sync);
41 static unsigned int defer_sync_state_count = 1;
42 static DEFINE_MUTEX(fwnode_link_lock);
43 static bool fw_devlink_is_permissive(void);
44 static void __fw_devlink_link_to_consumers(struct device *dev);
45 static bool fw_devlink_drv_reg_done;
46 static bool fw_devlink_best_effort;
47 static struct workqueue_struct *device_link_wq;
50 * __fwnode_link_add - Create a link between two fwnode_handles.
51 * @con: Consumer end of the link.
52 * @sup: Supplier end of the link.
55 * Create a fwnode link between fwnode handles @con and @sup. The fwnode link
56 * represents the detail that the firmware lists @sup fwnode as supplying a
59 * The driver core will use the fwnode link to create a device link between the
60 * two device objects corresponding to @con and @sup when they are created. The
61 * driver core will automatically delete the fwnode link between @con and @sup
64 * Attempts to create duplicate links between the same pair of fwnode handles
65 * are ignored and there is no reference counting.
67 static int __fwnode_link_add(struct fwnode_handle *con,
68 struct fwnode_handle *sup, u8 flags)
70 struct fwnode_link *link;
72 list_for_each_entry(link, &sup->consumers, s_hook)
73 if (link->consumer == con) {
78 link = kzalloc(sizeof(*link), GFP_KERNEL);
83 INIT_LIST_HEAD(&link->s_hook);
85 INIT_LIST_HEAD(&link->c_hook);
88 list_add(&link->s_hook, &sup->consumers);
89 list_add(&link->c_hook, &con->suppliers);
90 pr_debug("%pfwf Linked as a fwnode consumer to %pfwf\n",
96 int fwnode_link_add(struct fwnode_handle *con, struct fwnode_handle *sup,
101 mutex_lock(&fwnode_link_lock);
102 ret = __fwnode_link_add(con, sup, flags);
103 mutex_unlock(&fwnode_link_lock);
108 * __fwnode_link_del - Delete a link between two fwnode_handles.
109 * @link: the fwnode_link to be deleted
111 * The fwnode_link_lock needs to be held when this function is called.
113 static void __fwnode_link_del(struct fwnode_link *link)
115 pr_debug("%pfwf Dropping the fwnode link to %pfwf\n",
116 link->consumer, link->supplier);
117 list_del(&link->s_hook);
118 list_del(&link->c_hook);
123 * __fwnode_link_cycle - Mark a fwnode link as being part of a cycle.
124 * @link: the fwnode_link to be marked
126 * The fwnode_link_lock needs to be held when this function is called.
128 static void __fwnode_link_cycle(struct fwnode_link *link)
130 pr_debug("%pfwf: cycle: depends on %pfwf\n",
131 link->consumer, link->supplier);
132 link->flags |= FWLINK_FLAG_CYCLE;
136 * fwnode_links_purge_suppliers - Delete all supplier links of fwnode_handle.
137 * @fwnode: fwnode whose supplier links need to be deleted
139 * Deletes all supplier links connecting directly to @fwnode.
141 static void fwnode_links_purge_suppliers(struct fwnode_handle *fwnode)
143 struct fwnode_link *link, *tmp;
145 mutex_lock(&fwnode_link_lock);
146 list_for_each_entry_safe(link, tmp, &fwnode->suppliers, c_hook)
147 __fwnode_link_del(link);
148 mutex_unlock(&fwnode_link_lock);
152 * fwnode_links_purge_consumers - Delete all consumer links of fwnode_handle.
153 * @fwnode: fwnode whose consumer links need to be deleted
155 * Deletes all consumer links connecting directly to @fwnode.
157 static void fwnode_links_purge_consumers(struct fwnode_handle *fwnode)
159 struct fwnode_link *link, *tmp;
161 mutex_lock(&fwnode_link_lock);
162 list_for_each_entry_safe(link, tmp, &fwnode->consumers, s_hook)
163 __fwnode_link_del(link);
164 mutex_unlock(&fwnode_link_lock);
168 * fwnode_links_purge - Delete all links connected to a fwnode_handle.
169 * @fwnode: fwnode whose links needs to be deleted
171 * Deletes all links connecting directly to a fwnode.
173 void fwnode_links_purge(struct fwnode_handle *fwnode)
175 fwnode_links_purge_suppliers(fwnode);
176 fwnode_links_purge_consumers(fwnode);
179 void fw_devlink_purge_absent_suppliers(struct fwnode_handle *fwnode)
181 struct fwnode_handle *child;
183 /* Don't purge consumer links of an added child */
187 fwnode->flags |= FWNODE_FLAG_NOT_DEVICE;
188 fwnode_links_purge_consumers(fwnode);
190 fwnode_for_each_available_child_node(fwnode, child)
191 fw_devlink_purge_absent_suppliers(child);
193 EXPORT_SYMBOL_GPL(fw_devlink_purge_absent_suppliers);
196 * __fwnode_links_move_consumers - Move consumer from @from to @to fwnode_handle
197 * @from: move consumers away from this fwnode
198 * @to: move consumers to this fwnode
200 * Move all consumer links from @from fwnode to @to fwnode.
202 static void __fwnode_links_move_consumers(struct fwnode_handle *from,
203 struct fwnode_handle *to)
205 struct fwnode_link *link, *tmp;
207 list_for_each_entry_safe(link, tmp, &from->consumers, s_hook) {
208 __fwnode_link_add(link->consumer, to, link->flags);
209 __fwnode_link_del(link);
214 * __fw_devlink_pickup_dangling_consumers - Pick up dangling consumers
215 * @fwnode: fwnode from which to pick up dangling consumers
216 * @new_sup: fwnode of new supplier
218 * If the @fwnode has a corresponding struct device and the device supports
219 * probing (that is, added to a bus), then we want to let fw_devlink create
220 * MANAGED device links to this device, so leave @fwnode and its descendant's
221 * fwnode links alone.
223 * Otherwise, move its consumers to the new supplier @new_sup.
225 static void __fw_devlink_pickup_dangling_consumers(struct fwnode_handle *fwnode,
226 struct fwnode_handle *new_sup)
228 struct fwnode_handle *child;
230 if (fwnode->dev && fwnode->dev->bus)
233 fwnode->flags |= FWNODE_FLAG_NOT_DEVICE;
234 __fwnode_links_move_consumers(fwnode, new_sup);
236 fwnode_for_each_available_child_node(fwnode, child)
237 __fw_devlink_pickup_dangling_consumers(child, new_sup);
240 static DEFINE_MUTEX(device_links_lock);
241 DEFINE_STATIC_SRCU(device_links_srcu);
243 static inline void device_links_write_lock(void)
245 mutex_lock(&device_links_lock);
248 static inline void device_links_write_unlock(void)
250 mutex_unlock(&device_links_lock);
253 int device_links_read_lock(void) __acquires(&device_links_srcu)
255 return srcu_read_lock(&device_links_srcu);
258 void device_links_read_unlock(int idx) __releases(&device_links_srcu)
260 srcu_read_unlock(&device_links_srcu, idx);
263 int device_links_read_lock_held(void)
265 return srcu_read_lock_held(&device_links_srcu);
268 static void device_link_synchronize_removal(void)
270 synchronize_srcu(&device_links_srcu);
273 static void device_link_remove_from_lists(struct device_link *link)
275 list_del_rcu(&link->s_node);
276 list_del_rcu(&link->c_node);
279 static bool device_is_ancestor(struct device *dev, struct device *target)
281 while (target->parent) {
282 target = target->parent;
289 #define DL_MARKER_FLAGS (DL_FLAG_INFERRED | \
292 static inline bool device_link_flag_is_sync_state_only(u32 flags)
294 return (flags & ~DL_MARKER_FLAGS) == DL_FLAG_SYNC_STATE_ONLY;
298 * device_is_dependent - Check if one device depends on another one
299 * @dev: Device to check dependencies for.
300 * @target: Device to check against.
302 * Check if @target depends on @dev or any device dependent on it (its child or
303 * its consumer etc). Return 1 if that is the case or 0 otherwise.
305 static int device_is_dependent(struct device *dev, void *target)
307 struct device_link *link;
311 * The "ancestors" check is needed to catch the case when the target
312 * device has not been completely initialized yet and it is still
313 * missing from the list of children of its parent device.
315 if (dev == target || device_is_ancestor(dev, target))
318 ret = device_for_each_child(dev, target, device_is_dependent);
322 list_for_each_entry(link, &dev->links.consumers, s_node) {
323 if (device_link_flag_is_sync_state_only(link->flags))
326 if (link->consumer == target)
329 ret = device_is_dependent(link->consumer, target);
336 static void device_link_init_status(struct device_link *link,
337 struct device *consumer,
338 struct device *supplier)
340 switch (supplier->links.status) {
342 switch (consumer->links.status) {
345 * A consumer driver can create a link to a supplier
346 * that has not completed its probing yet as long as it
347 * knows that the supplier is already functional (for
348 * example, it has just acquired some resources from the
351 link->status = DL_STATE_CONSUMER_PROBE;
354 link->status = DL_STATE_DORMANT;
358 case DL_DEV_DRIVER_BOUND:
359 switch (consumer->links.status) {
361 link->status = DL_STATE_CONSUMER_PROBE;
363 case DL_DEV_DRIVER_BOUND:
364 link->status = DL_STATE_ACTIVE;
367 link->status = DL_STATE_AVAILABLE;
371 case DL_DEV_UNBINDING:
372 link->status = DL_STATE_SUPPLIER_UNBIND;
375 link->status = DL_STATE_DORMANT;
380 static int device_reorder_to_tail(struct device *dev, void *not_used)
382 struct device_link *link;
385 * Devices that have not been registered yet will be put to the ends
386 * of the lists during the registration, so skip them here.
388 if (device_is_registered(dev))
389 devices_kset_move_last(dev);
391 if (device_pm_initialized(dev))
392 device_pm_move_last(dev);
394 device_for_each_child(dev, NULL, device_reorder_to_tail);
395 list_for_each_entry(link, &dev->links.consumers, s_node) {
396 if (device_link_flag_is_sync_state_only(link->flags))
398 device_reorder_to_tail(link->consumer, NULL);
405 * device_pm_move_to_tail - Move set of devices to the end of device lists
406 * @dev: Device to move
408 * This is a device_reorder_to_tail() wrapper taking the requisite locks.
410 * It moves the @dev along with all of its children and all of its consumers
411 * to the ends of the device_kset and dpm_list, recursively.
413 void device_pm_move_to_tail(struct device *dev)
417 idx = device_links_read_lock();
419 device_reorder_to_tail(dev, NULL);
421 device_links_read_unlock(idx);
424 #define to_devlink(dev) container_of((dev), struct device_link, link_dev)
426 static ssize_t status_show(struct device *dev,
427 struct device_attribute *attr, char *buf)
431 switch (to_devlink(dev)->status) {
433 output = "not tracked";
435 case DL_STATE_DORMANT:
438 case DL_STATE_AVAILABLE:
439 output = "available";
441 case DL_STATE_CONSUMER_PROBE:
442 output = "consumer probing";
444 case DL_STATE_ACTIVE:
447 case DL_STATE_SUPPLIER_UNBIND:
448 output = "supplier unbinding";
455 return sysfs_emit(buf, "%s\n", output);
457 static DEVICE_ATTR_RO(status);
459 static ssize_t auto_remove_on_show(struct device *dev,
460 struct device_attribute *attr, char *buf)
462 struct device_link *link = to_devlink(dev);
465 if (link->flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
466 output = "supplier unbind";
467 else if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER)
468 output = "consumer unbind";
472 return sysfs_emit(buf, "%s\n", output);
474 static DEVICE_ATTR_RO(auto_remove_on);
476 static ssize_t runtime_pm_show(struct device *dev,
477 struct device_attribute *attr, char *buf)
479 struct device_link *link = to_devlink(dev);
481 return sysfs_emit(buf, "%d\n", !!(link->flags & DL_FLAG_PM_RUNTIME));
483 static DEVICE_ATTR_RO(runtime_pm);
485 static ssize_t sync_state_only_show(struct device *dev,
486 struct device_attribute *attr, char *buf)
488 struct device_link *link = to_devlink(dev);
490 return sysfs_emit(buf, "%d\n",
491 !!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
493 static DEVICE_ATTR_RO(sync_state_only);
495 static struct attribute *devlink_attrs[] = {
496 &dev_attr_status.attr,
497 &dev_attr_auto_remove_on.attr,
498 &dev_attr_runtime_pm.attr,
499 &dev_attr_sync_state_only.attr,
502 ATTRIBUTE_GROUPS(devlink);
504 static void device_link_release_fn(struct work_struct *work)
506 struct device_link *link = container_of(work, struct device_link, rm_work);
508 /* Ensure that all references to the link object have been dropped. */
509 device_link_synchronize_removal();
511 pm_runtime_release_supplier(link);
513 * If supplier_preactivated is set, the link has been dropped between
514 * the pm_runtime_get_suppliers() and pm_runtime_put_suppliers() calls
515 * in __driver_probe_device(). In that case, drop the supplier's
516 * PM-runtime usage counter to remove the reference taken by
517 * pm_runtime_get_suppliers().
519 if (link->supplier_preactivated)
520 pm_runtime_put_noidle(link->supplier);
522 pm_request_idle(link->supplier);
524 put_device(link->consumer);
525 put_device(link->supplier);
529 static void devlink_dev_release(struct device *dev)
531 struct device_link *link = to_devlink(dev);
533 INIT_WORK(&link->rm_work, device_link_release_fn);
535 * It may take a while to complete this work because of the SRCU
536 * synchronization in device_link_release_fn() and if the consumer or
537 * supplier devices get deleted when it runs, so put it into the
538 * dedicated workqueue.
540 queue_work(device_link_wq, &link->rm_work);
544 * device_link_wait_removal - Wait for ongoing devlink removal jobs to terminate
546 void device_link_wait_removal(void)
549 * devlink removal jobs are queued in the dedicated work queue.
550 * To be sure that all removal jobs are terminated, ensure that any
551 * scheduled work has run to completion.
553 flush_workqueue(device_link_wq);
555 EXPORT_SYMBOL_GPL(device_link_wait_removal);
557 static struct class devlink_class = {
559 .dev_groups = devlink_groups,
560 .dev_release = devlink_dev_release,
563 static int devlink_add_symlinks(struct device *dev)
567 struct device_link *link = to_devlink(dev);
568 struct device *sup = link->supplier;
569 struct device *con = link->consumer;
572 len = max(strlen(dev_bus_name(sup)) + strlen(dev_name(sup)),
573 strlen(dev_bus_name(con)) + strlen(dev_name(con)));
575 len += strlen("supplier:") + 1;
576 buf = kzalloc(len, GFP_KERNEL);
580 ret = sysfs_create_link(&link->link_dev.kobj, &sup->kobj, "supplier");
584 ret = sysfs_create_link(&link->link_dev.kobj, &con->kobj, "consumer");
588 snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con));
589 ret = sysfs_create_link(&sup->kobj, &link->link_dev.kobj, buf);
593 snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup));
594 ret = sysfs_create_link(&con->kobj, &link->link_dev.kobj, buf);
601 snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con));
602 sysfs_remove_link(&sup->kobj, buf);
604 sysfs_remove_link(&link->link_dev.kobj, "consumer");
606 sysfs_remove_link(&link->link_dev.kobj, "supplier");
612 static void devlink_remove_symlinks(struct device *dev)
614 struct device_link *link = to_devlink(dev);
616 struct device *sup = link->supplier;
617 struct device *con = link->consumer;
620 sysfs_remove_link(&link->link_dev.kobj, "consumer");
621 sysfs_remove_link(&link->link_dev.kobj, "supplier");
623 len = max(strlen(dev_bus_name(sup)) + strlen(dev_name(sup)),
624 strlen(dev_bus_name(con)) + strlen(dev_name(con)));
626 len += strlen("supplier:") + 1;
627 buf = kzalloc(len, GFP_KERNEL);
629 WARN(1, "Unable to properly free device link symlinks!\n");
633 if (device_is_registered(con)) {
634 snprintf(buf, len, "supplier:%s:%s", dev_bus_name(sup), dev_name(sup));
635 sysfs_remove_link(&con->kobj, buf);
637 snprintf(buf, len, "consumer:%s:%s", dev_bus_name(con), dev_name(con));
638 sysfs_remove_link(&sup->kobj, buf);
642 static struct class_interface devlink_class_intf = {
643 .class = &devlink_class,
644 .add_dev = devlink_add_symlinks,
645 .remove_dev = devlink_remove_symlinks,
648 static int __init devlink_class_init(void)
652 ret = class_register(&devlink_class);
656 ret = class_interface_register(&devlink_class_intf);
658 class_unregister(&devlink_class);
662 postcore_initcall(devlink_class_init);
664 #define DL_MANAGED_LINK_FLAGS (DL_FLAG_AUTOREMOVE_CONSUMER | \
665 DL_FLAG_AUTOREMOVE_SUPPLIER | \
666 DL_FLAG_AUTOPROBE_CONSUMER | \
667 DL_FLAG_SYNC_STATE_ONLY | \
671 #define DL_ADD_VALID_FLAGS (DL_MANAGED_LINK_FLAGS | DL_FLAG_STATELESS | \
672 DL_FLAG_PM_RUNTIME | DL_FLAG_RPM_ACTIVE)
675 * device_link_add - Create a link between two devices.
676 * @consumer: Consumer end of the link.
677 * @supplier: Supplier end of the link.
678 * @flags: Link flags.
680 * The caller is responsible for the proper synchronization of the link creation
681 * with runtime PM. First, setting the DL_FLAG_PM_RUNTIME flag will cause the
682 * runtime PM framework to take the link into account. Second, if the
683 * DL_FLAG_RPM_ACTIVE flag is set in addition to it, the supplier devices will
684 * be forced into the active meta state and reference-counted upon the creation
685 * of the link. If DL_FLAG_PM_RUNTIME is not set, DL_FLAG_RPM_ACTIVE will be
688 * If DL_FLAG_STATELESS is set in @flags, the caller of this function is
689 * expected to release the link returned by it directly with the help of either
690 * device_link_del() or device_link_remove().
692 * If that flag is not set, however, the caller of this function is handing the
693 * management of the link over to the driver core entirely and its return value
694 * can only be used to check whether or not the link is present. In that case,
695 * the DL_FLAG_AUTOREMOVE_CONSUMER and DL_FLAG_AUTOREMOVE_SUPPLIER device link
696 * flags can be used to indicate to the driver core when the link can be safely
697 * deleted. Namely, setting one of them in @flags indicates to the driver core
698 * that the link is not going to be used (by the given caller of this function)
699 * after unbinding the consumer or supplier driver, respectively, from its
700 * device, so the link can be deleted at that point. If none of them is set,
701 * the link will be maintained until one of the devices pointed to by it (either
702 * the consumer or the supplier) is unregistered.
704 * Also, if DL_FLAG_STATELESS, DL_FLAG_AUTOREMOVE_CONSUMER and
705 * DL_FLAG_AUTOREMOVE_SUPPLIER are not set in @flags (that is, a persistent
706 * managed device link is being added), the DL_FLAG_AUTOPROBE_CONSUMER flag can
707 * be used to request the driver core to automatically probe for a consumer
708 * driver after successfully binding a driver to the supplier device.
710 * The combination of DL_FLAG_STATELESS and one of DL_FLAG_AUTOREMOVE_CONSUMER,
711 * DL_FLAG_AUTOREMOVE_SUPPLIER, or DL_FLAG_AUTOPROBE_CONSUMER set in @flags at
712 * the same time is invalid and will cause NULL to be returned upfront.
713 * However, if a device link between the given @consumer and @supplier pair
714 * exists already when this function is called for them, the existing link will
715 * be returned regardless of its current type and status (the link's flags may
716 * be modified then). The caller of this function is then expected to treat
717 * the link as though it has just been created, so (in particular) if
718 * DL_FLAG_STATELESS was passed in @flags, the link needs to be released
719 * explicitly when not needed any more (as stated above).
721 * A side effect of the link creation is re-ordering of dpm_list and the
722 * devices_kset list by moving the consumer device and all devices depending
723 * on it to the ends of these lists (that does not happen to devices that have
724 * not been registered when this function is called).
726 * The supplier device is required to be registered when this function is called
727 * and NULL will be returned if that is not the case. The consumer device need
728 * not be registered, however.
730 struct device_link *device_link_add(struct device *consumer,
731 struct device *supplier, u32 flags)
733 struct device_link *link;
735 if (!consumer || !supplier || consumer == supplier ||
736 flags & ~DL_ADD_VALID_FLAGS ||
737 (flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) ||
738 (flags & DL_FLAG_AUTOPROBE_CONSUMER &&
739 flags & (DL_FLAG_AUTOREMOVE_CONSUMER |
740 DL_FLAG_AUTOREMOVE_SUPPLIER)))
743 if (flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) {
744 if (pm_runtime_get_sync(supplier) < 0) {
745 pm_runtime_put_noidle(supplier);
750 if (!(flags & DL_FLAG_STATELESS))
751 flags |= DL_FLAG_MANAGED;
753 if (flags & DL_FLAG_SYNC_STATE_ONLY &&
754 !device_link_flag_is_sync_state_only(flags))
757 device_links_write_lock();
761 * If the supplier has not been fully registered yet or there is a
762 * reverse (non-SYNC_STATE_ONLY) dependency between the consumer and
763 * the supplier already in the graph, return NULL. If the link is a
764 * SYNC_STATE_ONLY link, we don't check for reverse dependencies
765 * because it only affects sync_state() callbacks.
767 if (!device_pm_initialized(supplier)
768 || (!(flags & DL_FLAG_SYNC_STATE_ONLY) &&
769 device_is_dependent(consumer, supplier))) {
775 * SYNC_STATE_ONLY links are useless once a consumer device has probed.
776 * So, only create it if the consumer hasn't probed yet.
778 if (flags & DL_FLAG_SYNC_STATE_ONLY &&
779 consumer->links.status != DL_DEV_NO_DRIVER &&
780 consumer->links.status != DL_DEV_PROBING) {
786 * DL_FLAG_AUTOREMOVE_SUPPLIER indicates that the link will be needed
787 * longer than for DL_FLAG_AUTOREMOVE_CONSUMER and setting them both
788 * together doesn't make sense, so prefer DL_FLAG_AUTOREMOVE_SUPPLIER.
790 if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
791 flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
793 list_for_each_entry(link, &supplier->links.consumers, s_node) {
794 if (link->consumer != consumer)
797 if (link->flags & DL_FLAG_INFERRED &&
798 !(flags & DL_FLAG_INFERRED))
799 link->flags &= ~DL_FLAG_INFERRED;
801 if (flags & DL_FLAG_PM_RUNTIME) {
802 if (!(link->flags & DL_FLAG_PM_RUNTIME)) {
803 pm_runtime_new_link(consumer);
804 link->flags |= DL_FLAG_PM_RUNTIME;
806 if (flags & DL_FLAG_RPM_ACTIVE)
807 refcount_inc(&link->rpm_active);
810 if (flags & DL_FLAG_STATELESS) {
811 kref_get(&link->kref);
812 if (link->flags & DL_FLAG_SYNC_STATE_ONLY &&
813 !(link->flags & DL_FLAG_STATELESS)) {
814 link->flags |= DL_FLAG_STATELESS;
817 link->flags |= DL_FLAG_STATELESS;
823 * If the life time of the link following from the new flags is
824 * longer than indicated by the flags of the existing link,
825 * update the existing link to stay around longer.
827 if (flags & DL_FLAG_AUTOREMOVE_SUPPLIER) {
828 if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
829 link->flags &= ~DL_FLAG_AUTOREMOVE_CONSUMER;
830 link->flags |= DL_FLAG_AUTOREMOVE_SUPPLIER;
832 } else if (!(flags & DL_FLAG_AUTOREMOVE_CONSUMER)) {
833 link->flags &= ~(DL_FLAG_AUTOREMOVE_CONSUMER |
834 DL_FLAG_AUTOREMOVE_SUPPLIER);
836 if (!(link->flags & DL_FLAG_MANAGED)) {
837 kref_get(&link->kref);
838 link->flags |= DL_FLAG_MANAGED;
839 device_link_init_status(link, consumer, supplier);
841 if (link->flags & DL_FLAG_SYNC_STATE_ONLY &&
842 !(flags & DL_FLAG_SYNC_STATE_ONLY)) {
843 link->flags &= ~DL_FLAG_SYNC_STATE_ONLY;
850 link = kzalloc(sizeof(*link), GFP_KERNEL);
854 refcount_set(&link->rpm_active, 1);
856 get_device(supplier);
857 link->supplier = supplier;
858 INIT_LIST_HEAD(&link->s_node);
859 get_device(consumer);
860 link->consumer = consumer;
861 INIT_LIST_HEAD(&link->c_node);
863 kref_init(&link->kref);
865 link->link_dev.class = &devlink_class;
866 device_set_pm_not_required(&link->link_dev);
867 dev_set_name(&link->link_dev, "%s:%s--%s:%s",
868 dev_bus_name(supplier), dev_name(supplier),
869 dev_bus_name(consumer), dev_name(consumer));
870 if (device_register(&link->link_dev)) {
871 put_device(&link->link_dev);
876 if (flags & DL_FLAG_PM_RUNTIME) {
877 if (flags & DL_FLAG_RPM_ACTIVE)
878 refcount_inc(&link->rpm_active);
880 pm_runtime_new_link(consumer);
883 /* Determine the initial link state. */
884 if (flags & DL_FLAG_STATELESS)
885 link->status = DL_STATE_NONE;
887 device_link_init_status(link, consumer, supplier);
890 * Some callers expect the link creation during consumer driver probe to
891 * resume the supplier even without DL_FLAG_RPM_ACTIVE.
893 if (link->status == DL_STATE_CONSUMER_PROBE &&
894 flags & DL_FLAG_PM_RUNTIME)
895 pm_runtime_resume(supplier);
897 list_add_tail_rcu(&link->s_node, &supplier->links.consumers);
898 list_add_tail_rcu(&link->c_node, &consumer->links.suppliers);
900 if (flags & DL_FLAG_SYNC_STATE_ONLY) {
902 "Linked as a sync state only consumer to %s\n",
909 * Move the consumer and all of the devices depending on it to the end
910 * of dpm_list and the devices_kset list.
912 * It is necessary to hold dpm_list locked throughout all that or else
913 * we may end up suspending with a wrong ordering of it.
915 device_reorder_to_tail(consumer, NULL);
917 dev_dbg(consumer, "Linked as a consumer to %s\n", dev_name(supplier));
921 device_links_write_unlock();
923 if ((flags & DL_FLAG_PM_RUNTIME && flags & DL_FLAG_RPM_ACTIVE) && !link)
924 pm_runtime_put(supplier);
928 EXPORT_SYMBOL_GPL(device_link_add);
930 static void __device_link_del(struct kref *kref)
932 struct device_link *link = container_of(kref, struct device_link, kref);
934 dev_dbg(link->consumer, "Dropping the link to %s\n",
935 dev_name(link->supplier));
937 pm_runtime_drop_link(link);
939 device_link_remove_from_lists(link);
940 device_unregister(&link->link_dev);
943 static void device_link_put_kref(struct device_link *link)
945 if (link->flags & DL_FLAG_STATELESS)
946 kref_put(&link->kref, __device_link_del);
947 else if (!device_is_registered(link->consumer))
948 __device_link_del(&link->kref);
950 WARN(1, "Unable to drop a managed device link reference\n");
954 * device_link_del - Delete a stateless link between two devices.
955 * @link: Device link to delete.
957 * The caller must ensure proper synchronization of this function with runtime
958 * PM. If the link was added multiple times, it needs to be deleted as often.
959 * Care is required for hotplugged devices: Their links are purged on removal
960 * and calling device_link_del() is then no longer allowed.
962 void device_link_del(struct device_link *link)
964 device_links_write_lock();
965 device_link_put_kref(link);
966 device_links_write_unlock();
968 EXPORT_SYMBOL_GPL(device_link_del);
971 * device_link_remove - Delete a stateless link between two devices.
972 * @consumer: Consumer end of the link.
973 * @supplier: Supplier end of the link.
975 * The caller must ensure proper synchronization of this function with runtime
978 void device_link_remove(void *consumer, struct device *supplier)
980 struct device_link *link;
982 if (WARN_ON(consumer == supplier))
985 device_links_write_lock();
987 list_for_each_entry(link, &supplier->links.consumers, s_node) {
988 if (link->consumer == consumer) {
989 device_link_put_kref(link);
994 device_links_write_unlock();
996 EXPORT_SYMBOL_GPL(device_link_remove);
998 static void device_links_missing_supplier(struct device *dev)
1000 struct device_link *link;
1002 list_for_each_entry(link, &dev->links.suppliers, c_node) {
1003 if (link->status != DL_STATE_CONSUMER_PROBE)
1006 if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
1007 WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
1009 WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
1010 WRITE_ONCE(link->status, DL_STATE_DORMANT);
1015 static bool dev_is_best_effort(struct device *dev)
1017 return (fw_devlink_best_effort && dev->can_match) ||
1018 (dev->fwnode && (dev->fwnode->flags & FWNODE_FLAG_BEST_EFFORT));
1021 static struct fwnode_handle *fwnode_links_check_suppliers(
1022 struct fwnode_handle *fwnode)
1024 struct fwnode_link *link;
1026 if (!fwnode || fw_devlink_is_permissive())
1029 list_for_each_entry(link, &fwnode->suppliers, c_hook)
1031 (FWLINK_FLAG_CYCLE | FWLINK_FLAG_IGNORE)))
1032 return link->supplier;
1038 * device_links_check_suppliers - Check presence of supplier drivers.
1039 * @dev: Consumer device.
1041 * Check links from this device to any suppliers. Walk the list of the device's
1042 * links to suppliers and see if all of them are available. If not, simply
1043 * return -EPROBE_DEFER.
1045 * We need to guarantee that the supplier will not go away after the check has
1046 * been positive here. It only can go away in __device_release_driver() and
1047 * that function checks the device's links to consumers. This means we need to
1048 * mark the link as "consumer probe in progress" to make the supplier removal
1049 * wait for us to complete (or bad things may happen).
1051 * Links without the DL_FLAG_MANAGED flag set are ignored.
1053 int device_links_check_suppliers(struct device *dev)
1055 struct device_link *link;
1056 int ret = 0, fwnode_ret = 0;
1057 struct fwnode_handle *sup_fw;
1060 * Device waiting for supplier to become available is not allowed to
1063 mutex_lock(&fwnode_link_lock);
1064 sup_fw = fwnode_links_check_suppliers(dev->fwnode);
1066 if (!dev_is_best_effort(dev)) {
1067 fwnode_ret = -EPROBE_DEFER;
1068 dev_err_probe(dev, -EPROBE_DEFER,
1069 "wait for supplier %pfwf\n", sup_fw);
1071 fwnode_ret = -EAGAIN;
1074 mutex_unlock(&fwnode_link_lock);
1075 if (fwnode_ret == -EPROBE_DEFER)
1078 device_links_write_lock();
1080 list_for_each_entry(link, &dev->links.suppliers, c_node) {
1081 if (!(link->flags & DL_FLAG_MANAGED))
1084 if (link->status != DL_STATE_AVAILABLE &&
1085 !(link->flags & DL_FLAG_SYNC_STATE_ONLY)) {
1087 if (dev_is_best_effort(dev) &&
1088 link->flags & DL_FLAG_INFERRED &&
1089 !link->supplier->can_match) {
1094 device_links_missing_supplier(dev);
1095 dev_err_probe(dev, -EPROBE_DEFER,
1096 "supplier %s not ready\n",
1097 dev_name(link->supplier));
1098 ret = -EPROBE_DEFER;
1101 WRITE_ONCE(link->status, DL_STATE_CONSUMER_PROBE);
1103 dev->links.status = DL_DEV_PROBING;
1105 device_links_write_unlock();
1107 return ret ? ret : fwnode_ret;
1111 * __device_links_queue_sync_state - Queue a device for sync_state() callback
1112 * @dev: Device to call sync_state() on
1113 * @list: List head to queue the @dev on
1115 * Queues a device for a sync_state() callback when the device links write lock
1116 * isn't held. This allows the sync_state() execution flow to use device links
1117 * APIs. The caller must ensure this function is called with
1118 * device_links_write_lock() held.
1120 * This function does a get_device() to make sure the device is not freed while
1123 * So the caller must also ensure that device_links_flush_sync_list() is called
1124 * as soon as the caller releases device_links_write_lock(). This is necessary
1125 * to make sure the sync_state() is called in a timely fashion and the
1126 * put_device() is called on this device.
1128 static void __device_links_queue_sync_state(struct device *dev,
1129 struct list_head *list)
1131 struct device_link *link;
1133 if (!dev_has_sync_state(dev))
1135 if (dev->state_synced)
1138 list_for_each_entry(link, &dev->links.consumers, s_node) {
1139 if (!(link->flags & DL_FLAG_MANAGED))
1141 if (link->status != DL_STATE_ACTIVE)
1146 * Set the flag here to avoid adding the same device to a list more
1147 * than once. This can happen if new consumers get added to the device
1148 * and probed before the list is flushed.
1150 dev->state_synced = true;
1152 if (WARN_ON(!list_empty(&dev->links.defer_sync)))
1156 list_add_tail(&dev->links.defer_sync, list);
1160 * device_links_flush_sync_list - Call sync_state() on a list of devices
1161 * @list: List of devices to call sync_state() on
1162 * @dont_lock_dev: Device for which lock is already held by the caller
1164 * Calls sync_state() on all the devices that have been queued for it. This
1165 * function is used in conjunction with __device_links_queue_sync_state(). The
1166 * @dont_lock_dev parameter is useful when this function is called from a
1167 * context where a device lock is already held.
1169 static void device_links_flush_sync_list(struct list_head *list,
1170 struct device *dont_lock_dev)
1172 struct device *dev, *tmp;
1174 list_for_each_entry_safe(dev, tmp, list, links.defer_sync) {
1175 list_del_init(&dev->links.defer_sync);
1177 if (dev != dont_lock_dev)
1180 dev_sync_state(dev);
1182 if (dev != dont_lock_dev)
1189 void device_links_supplier_sync_state_pause(void)
1191 device_links_write_lock();
1192 defer_sync_state_count++;
1193 device_links_write_unlock();
1196 void device_links_supplier_sync_state_resume(void)
1198 struct device *dev, *tmp;
1199 LIST_HEAD(sync_list);
1201 device_links_write_lock();
1202 if (!defer_sync_state_count) {
1203 WARN(true, "Unmatched sync_state pause/resume!");
1206 defer_sync_state_count--;
1207 if (defer_sync_state_count)
1210 list_for_each_entry_safe(dev, tmp, &deferred_sync, links.defer_sync) {
1212 * Delete from deferred_sync list before queuing it to
1213 * sync_list because defer_sync is used for both lists.
1215 list_del_init(&dev->links.defer_sync);
1216 __device_links_queue_sync_state(dev, &sync_list);
1219 device_links_write_unlock();
1221 device_links_flush_sync_list(&sync_list, NULL);
1224 static int sync_state_resume_initcall(void)
1226 device_links_supplier_sync_state_resume();
1229 late_initcall(sync_state_resume_initcall);
1231 static void __device_links_supplier_defer_sync(struct device *sup)
1233 if (list_empty(&sup->links.defer_sync) && dev_has_sync_state(sup))
1234 list_add_tail(&sup->links.defer_sync, &deferred_sync);
1237 static void device_link_drop_managed(struct device_link *link)
1239 link->flags &= ~DL_FLAG_MANAGED;
1240 WRITE_ONCE(link->status, DL_STATE_NONE);
1241 kref_put(&link->kref, __device_link_del);
1244 static ssize_t waiting_for_supplier_show(struct device *dev,
1245 struct device_attribute *attr,
1251 mutex_lock(&fwnode_link_lock);
1252 val = !!fwnode_links_check_suppliers(dev->fwnode);
1253 mutex_unlock(&fwnode_link_lock);
1255 return sysfs_emit(buf, "%u\n", val);
1257 static DEVICE_ATTR_RO(waiting_for_supplier);
1260 * device_links_force_bind - Prepares device to be force bound
1261 * @dev: Consumer device.
1263 * device_bind_driver() force binds a device to a driver without calling any
1264 * driver probe functions. So the consumer really isn't going to wait for any
1265 * supplier before it's bound to the driver. We still want the device link
1266 * states to be sensible when this happens.
1268 * In preparation for device_bind_driver(), this function goes through each
1269 * supplier device links and checks if the supplier is bound. If it is, then
1270 * the device link status is set to CONSUMER_PROBE. Otherwise, the device link
1271 * is dropped. Links without the DL_FLAG_MANAGED flag set are ignored.
1273 void device_links_force_bind(struct device *dev)
1275 struct device_link *link, *ln;
1277 device_links_write_lock();
1279 list_for_each_entry_safe(link, ln, &dev->links.suppliers, c_node) {
1280 if (!(link->flags & DL_FLAG_MANAGED))
1283 if (link->status != DL_STATE_AVAILABLE) {
1284 device_link_drop_managed(link);
1287 WRITE_ONCE(link->status, DL_STATE_CONSUMER_PROBE);
1289 dev->links.status = DL_DEV_PROBING;
1291 device_links_write_unlock();
1295 * device_links_driver_bound - Update device links after probing its driver.
1296 * @dev: Device to update the links for.
1298 * The probe has been successful, so update links from this device to any
1299 * consumers by changing their status to "available".
1301 * Also change the status of @dev's links to suppliers to "active".
1303 * Links without the DL_FLAG_MANAGED flag set are ignored.
1305 void device_links_driver_bound(struct device *dev)
1307 struct device_link *link, *ln;
1308 LIST_HEAD(sync_list);
1311 * If a device binds successfully, it's expected to have created all
1312 * the device links it needs to or make new device links as it needs
1313 * them. So, fw_devlink no longer needs to create device links to any
1314 * of the device's suppliers.
1316 * Also, if a child firmware node of this bound device is not added as a
1317 * device by now, assume it is never going to be added. Make this bound
1318 * device the fallback supplier to the dangling consumers of the child
1319 * firmware node because this bound device is probably implementing the
1320 * child firmware node functionality and we don't want the dangling
1321 * consumers to defer probe indefinitely waiting for a device for the
1322 * child firmware node.
1324 if (dev->fwnode && dev->fwnode->dev == dev) {
1325 struct fwnode_handle *child;
1326 fwnode_links_purge_suppliers(dev->fwnode);
1327 mutex_lock(&fwnode_link_lock);
1328 fwnode_for_each_available_child_node(dev->fwnode, child)
1329 __fw_devlink_pickup_dangling_consumers(child,
1331 __fw_devlink_link_to_consumers(dev);
1332 mutex_unlock(&fwnode_link_lock);
1334 device_remove_file(dev, &dev_attr_waiting_for_supplier);
1336 device_links_write_lock();
1338 list_for_each_entry(link, &dev->links.consumers, s_node) {
1339 if (!(link->flags & DL_FLAG_MANAGED))
1343 * Links created during consumer probe may be in the "consumer
1344 * probe" state to start with if the supplier is still probing
1345 * when they are created and they may become "active" if the
1346 * consumer probe returns first. Skip them here.
1348 if (link->status == DL_STATE_CONSUMER_PROBE ||
1349 link->status == DL_STATE_ACTIVE)
1352 WARN_ON(link->status != DL_STATE_DORMANT);
1353 WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
1355 if (link->flags & DL_FLAG_AUTOPROBE_CONSUMER)
1356 driver_deferred_probe_add(link->consumer);
1359 if (defer_sync_state_count)
1360 __device_links_supplier_defer_sync(dev);
1362 __device_links_queue_sync_state(dev, &sync_list);
1364 list_for_each_entry_safe(link, ln, &dev->links.suppliers, c_node) {
1365 struct device *supplier;
1367 if (!(link->flags & DL_FLAG_MANAGED))
1370 supplier = link->supplier;
1371 if (link->flags & DL_FLAG_SYNC_STATE_ONLY) {
1373 * When DL_FLAG_SYNC_STATE_ONLY is set, it means no
1374 * other DL_MANAGED_LINK_FLAGS have been set. So, it's
1375 * save to drop the managed link completely.
1377 device_link_drop_managed(link);
1378 } else if (dev_is_best_effort(dev) &&
1379 link->flags & DL_FLAG_INFERRED &&
1380 link->status != DL_STATE_CONSUMER_PROBE &&
1381 !link->supplier->can_match) {
1383 * When dev_is_best_effort() is true, we ignore device
1384 * links to suppliers that don't have a driver. If the
1385 * consumer device still managed to probe, there's no
1386 * point in maintaining a device link in a weird state
1387 * (consumer probed before supplier). So delete it.
1389 device_link_drop_managed(link);
1391 WARN_ON(link->status != DL_STATE_CONSUMER_PROBE);
1392 WRITE_ONCE(link->status, DL_STATE_ACTIVE);
1396 * This needs to be done even for the deleted
1397 * DL_FLAG_SYNC_STATE_ONLY device link in case it was the last
1398 * device link that was preventing the supplier from getting a
1399 * sync_state() call.
1401 if (defer_sync_state_count)
1402 __device_links_supplier_defer_sync(supplier);
1404 __device_links_queue_sync_state(supplier, &sync_list);
1407 dev->links.status = DL_DEV_DRIVER_BOUND;
1409 device_links_write_unlock();
1411 device_links_flush_sync_list(&sync_list, dev);
1415 * __device_links_no_driver - Update links of a device without a driver.
1416 * @dev: Device without a drvier.
1418 * Delete all non-persistent links from this device to any suppliers.
1420 * Persistent links stay around, but their status is changed to "available",
1421 * unless they already are in the "supplier unbind in progress" state in which
1422 * case they need not be updated.
1424 * Links without the DL_FLAG_MANAGED flag set are ignored.
1426 static void __device_links_no_driver(struct device *dev)
1428 struct device_link *link, *ln;
1430 list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
1431 if (!(link->flags & DL_FLAG_MANAGED))
1434 if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
1435 device_link_drop_managed(link);
1439 if (link->status != DL_STATE_CONSUMER_PROBE &&
1440 link->status != DL_STATE_ACTIVE)
1443 if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
1444 WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
1446 WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
1447 WRITE_ONCE(link->status, DL_STATE_DORMANT);
1451 dev->links.status = DL_DEV_NO_DRIVER;
1455 * device_links_no_driver - Update links after failing driver probe.
1456 * @dev: Device whose driver has just failed to probe.
1458 * Clean up leftover links to consumers for @dev and invoke
1459 * %__device_links_no_driver() to update links to suppliers for it as
1462 * Links without the DL_FLAG_MANAGED flag set are ignored.
1464 void device_links_no_driver(struct device *dev)
1466 struct device_link *link;
1468 device_links_write_lock();
1470 list_for_each_entry(link, &dev->links.consumers, s_node) {
1471 if (!(link->flags & DL_FLAG_MANAGED))
1475 * The probe has failed, so if the status of the link is
1476 * "consumer probe" or "active", it must have been added by
1477 * a probing consumer while this device was still probing.
1478 * Change its state to "dormant", as it represents a valid
1479 * relationship, but it is not functionally meaningful.
1481 if (link->status == DL_STATE_CONSUMER_PROBE ||
1482 link->status == DL_STATE_ACTIVE)
1483 WRITE_ONCE(link->status, DL_STATE_DORMANT);
1486 __device_links_no_driver(dev);
1488 device_links_write_unlock();
1492 * device_links_driver_cleanup - Update links after driver removal.
1493 * @dev: Device whose driver has just gone away.
1495 * Update links to consumers for @dev by changing their status to "dormant" and
1496 * invoke %__device_links_no_driver() to update links to suppliers for it as
1499 * Links without the DL_FLAG_MANAGED flag set are ignored.
1501 void device_links_driver_cleanup(struct device *dev)
1503 struct device_link *link, *ln;
1505 device_links_write_lock();
1507 list_for_each_entry_safe(link, ln, &dev->links.consumers, s_node) {
1508 if (!(link->flags & DL_FLAG_MANAGED))
1511 WARN_ON(link->flags & DL_FLAG_AUTOREMOVE_CONSUMER);
1512 WARN_ON(link->status != DL_STATE_SUPPLIER_UNBIND);
1515 * autoremove the links between this @dev and its consumer
1516 * devices that are not active, i.e. where the link state
1517 * has moved to DL_STATE_SUPPLIER_UNBIND.
1519 if (link->status == DL_STATE_SUPPLIER_UNBIND &&
1520 link->flags & DL_FLAG_AUTOREMOVE_SUPPLIER)
1521 device_link_drop_managed(link);
1523 WRITE_ONCE(link->status, DL_STATE_DORMANT);
1526 list_del_init(&dev->links.defer_sync);
1527 __device_links_no_driver(dev);
1529 device_links_write_unlock();
1533 * device_links_busy - Check if there are any busy links to consumers.
1534 * @dev: Device to check.
1536 * Check each consumer of the device and return 'true' if its link's status
1537 * is one of "consumer probe" or "active" (meaning that the given consumer is
1538 * probing right now or its driver is present). Otherwise, change the link
1539 * state to "supplier unbind" to prevent the consumer from being probed
1540 * successfully going forward.
1542 * Return 'false' if there are no probing or active consumers.
1544 * Links without the DL_FLAG_MANAGED flag set are ignored.
1546 bool device_links_busy(struct device *dev)
1548 struct device_link *link;
1551 device_links_write_lock();
1553 list_for_each_entry(link, &dev->links.consumers, s_node) {
1554 if (!(link->flags & DL_FLAG_MANAGED))
1557 if (link->status == DL_STATE_CONSUMER_PROBE
1558 || link->status == DL_STATE_ACTIVE) {
1562 WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
1565 dev->links.status = DL_DEV_UNBINDING;
1567 device_links_write_unlock();
1572 * device_links_unbind_consumers - Force unbind consumers of the given device.
1573 * @dev: Device to unbind the consumers of.
1575 * Walk the list of links to consumers for @dev and if any of them is in the
1576 * "consumer probe" state, wait for all device probes in progress to complete
1579 * If that's not the case, change the status of the link to "supplier unbind"
1580 * and check if the link was in the "active" state. If so, force the consumer
1581 * driver to unbind and start over (the consumer will not re-probe as we have
1582 * changed the state of the link already).
1584 * Links without the DL_FLAG_MANAGED flag set are ignored.
1586 void device_links_unbind_consumers(struct device *dev)
1588 struct device_link *link;
1591 device_links_write_lock();
1593 list_for_each_entry(link, &dev->links.consumers, s_node) {
1594 enum device_link_state status;
1596 if (!(link->flags & DL_FLAG_MANAGED) ||
1597 link->flags & DL_FLAG_SYNC_STATE_ONLY)
1600 status = link->status;
1601 if (status == DL_STATE_CONSUMER_PROBE) {
1602 device_links_write_unlock();
1604 wait_for_device_probe();
1607 WRITE_ONCE(link->status, DL_STATE_SUPPLIER_UNBIND);
1608 if (status == DL_STATE_ACTIVE) {
1609 struct device *consumer = link->consumer;
1611 get_device(consumer);
1613 device_links_write_unlock();
1615 device_release_driver_internal(consumer, NULL,
1617 put_device(consumer);
1622 device_links_write_unlock();
1626 * device_links_purge - Delete existing links to other devices.
1627 * @dev: Target device.
1629 static void device_links_purge(struct device *dev)
1631 struct device_link *link, *ln;
1633 if (dev->class == &devlink_class)
1637 * Delete all of the remaining links from this device to any other
1638 * devices (either consumers or suppliers).
1640 device_links_write_lock();
1642 list_for_each_entry_safe_reverse(link, ln, &dev->links.suppliers, c_node) {
1643 WARN_ON(link->status == DL_STATE_ACTIVE);
1644 __device_link_del(&link->kref);
1647 list_for_each_entry_safe_reverse(link, ln, &dev->links.consumers, s_node) {
1648 WARN_ON(link->status != DL_STATE_DORMANT &&
1649 link->status != DL_STATE_NONE);
1650 __device_link_del(&link->kref);
1653 device_links_write_unlock();
1656 #define FW_DEVLINK_FLAGS_PERMISSIVE (DL_FLAG_INFERRED | \
1657 DL_FLAG_SYNC_STATE_ONLY)
1658 #define FW_DEVLINK_FLAGS_ON (DL_FLAG_INFERRED | \
1659 DL_FLAG_AUTOPROBE_CONSUMER)
1660 #define FW_DEVLINK_FLAGS_RPM (FW_DEVLINK_FLAGS_ON | \
1663 static u32 fw_devlink_flags = FW_DEVLINK_FLAGS_RPM;
1664 static int __init fw_devlink_setup(char *arg)
1669 if (strcmp(arg, "off") == 0) {
1670 fw_devlink_flags = 0;
1671 } else if (strcmp(arg, "permissive") == 0) {
1672 fw_devlink_flags = FW_DEVLINK_FLAGS_PERMISSIVE;
1673 } else if (strcmp(arg, "on") == 0) {
1674 fw_devlink_flags = FW_DEVLINK_FLAGS_ON;
1675 } else if (strcmp(arg, "rpm") == 0) {
1676 fw_devlink_flags = FW_DEVLINK_FLAGS_RPM;
1680 early_param("fw_devlink", fw_devlink_setup);
1682 static bool fw_devlink_strict;
1683 static int __init fw_devlink_strict_setup(char *arg)
1685 return kstrtobool(arg, &fw_devlink_strict);
1687 early_param("fw_devlink.strict", fw_devlink_strict_setup);
1689 #define FW_DEVLINK_SYNC_STATE_STRICT 0
1690 #define FW_DEVLINK_SYNC_STATE_TIMEOUT 1
1692 #ifndef CONFIG_FW_DEVLINK_SYNC_STATE_TIMEOUT
1693 static int fw_devlink_sync_state;
1695 static int fw_devlink_sync_state = FW_DEVLINK_SYNC_STATE_TIMEOUT;
1698 static int __init fw_devlink_sync_state_setup(char *arg)
1703 if (strcmp(arg, "strict") == 0) {
1704 fw_devlink_sync_state = FW_DEVLINK_SYNC_STATE_STRICT;
1706 } else if (strcmp(arg, "timeout") == 0) {
1707 fw_devlink_sync_state = FW_DEVLINK_SYNC_STATE_TIMEOUT;
1712 early_param("fw_devlink.sync_state", fw_devlink_sync_state_setup);
1714 static inline u32 fw_devlink_get_flags(u8 fwlink_flags)
1716 if (fwlink_flags & FWLINK_FLAG_CYCLE)
1717 return FW_DEVLINK_FLAGS_PERMISSIVE | DL_FLAG_CYCLE;
1719 return fw_devlink_flags;
1722 static bool fw_devlink_is_permissive(void)
1724 return fw_devlink_flags == FW_DEVLINK_FLAGS_PERMISSIVE;
1727 bool fw_devlink_is_strict(void)
1729 return fw_devlink_strict && !fw_devlink_is_permissive();
1732 static void fw_devlink_parse_fwnode(struct fwnode_handle *fwnode)
1734 if (fwnode->flags & FWNODE_FLAG_LINKS_ADDED)
1737 fwnode_call_int_op(fwnode, add_links);
1738 fwnode->flags |= FWNODE_FLAG_LINKS_ADDED;
1741 static void fw_devlink_parse_fwtree(struct fwnode_handle *fwnode)
1743 struct fwnode_handle *child = NULL;
1745 fw_devlink_parse_fwnode(fwnode);
1747 while ((child = fwnode_get_next_available_child_node(fwnode, child)))
1748 fw_devlink_parse_fwtree(child);
1751 static void fw_devlink_relax_link(struct device_link *link)
1753 if (!(link->flags & DL_FLAG_INFERRED))
1756 if (device_link_flag_is_sync_state_only(link->flags))
1759 pm_runtime_drop_link(link);
1760 link->flags = DL_FLAG_MANAGED | FW_DEVLINK_FLAGS_PERMISSIVE;
1761 dev_dbg(link->consumer, "Relaxing link with %s\n",
1762 dev_name(link->supplier));
1765 static int fw_devlink_no_driver(struct device *dev, void *data)
1767 struct device_link *link = to_devlink(dev);
1769 if (!link->supplier->can_match)
1770 fw_devlink_relax_link(link);
1775 void fw_devlink_drivers_done(void)
1777 fw_devlink_drv_reg_done = true;
1778 device_links_write_lock();
1779 class_for_each_device(&devlink_class, NULL, NULL,
1780 fw_devlink_no_driver);
1781 device_links_write_unlock();
1784 static int fw_devlink_dev_sync_state(struct device *dev, void *data)
1786 struct device_link *link = to_devlink(dev);
1787 struct device *sup = link->supplier;
1789 if (!(link->flags & DL_FLAG_MANAGED) ||
1790 link->status == DL_STATE_ACTIVE || sup->state_synced ||
1791 !dev_has_sync_state(sup))
1794 if (fw_devlink_sync_state == FW_DEVLINK_SYNC_STATE_STRICT) {
1795 dev_warn(sup, "sync_state() pending due to %s\n",
1796 dev_name(link->consumer));
1800 if (!list_empty(&sup->links.defer_sync))
1803 dev_warn(sup, "Timed out. Forcing sync_state()\n");
1804 sup->state_synced = true;
1806 list_add_tail(&sup->links.defer_sync, data);
1811 void fw_devlink_probing_done(void)
1813 LIST_HEAD(sync_list);
1815 device_links_write_lock();
1816 class_for_each_device(&devlink_class, NULL, &sync_list,
1817 fw_devlink_dev_sync_state);
1818 device_links_write_unlock();
1819 device_links_flush_sync_list(&sync_list, NULL);
1823 * wait_for_init_devices_probe - Try to probe any device needed for init
1825 * Some devices might need to be probed and bound successfully before the kernel
1826 * boot sequence can finish and move on to init/userspace. For example, a
1827 * network interface might need to be bound to be able to mount a NFS rootfs.
1829 * With fw_devlink=on by default, some of these devices might be blocked from
1830 * probing because they are waiting on a optional supplier that doesn't have a
1831 * driver. While fw_devlink will eventually identify such devices and unblock
1832 * the probing automatically, it might be too late by the time it unblocks the
1833 * probing of devices. For example, the IP4 autoconfig might timeout before
1834 * fw_devlink unblocks probing of the network interface.
1836 * This function is available to temporarily try and probe all devices that have
1837 * a driver even if some of their suppliers haven't been added or don't have
1840 * The drivers can then decide which of the suppliers are optional vs mandatory
1841 * and probe the device if possible. By the time this function returns, all such
1842 * "best effort" probes are guaranteed to be completed. If a device successfully
1843 * probes in this mode, we delete all fw_devlink discovered dependencies of that
1844 * device where the supplier hasn't yet probed successfully because they have to
1845 * be optional dependencies.
1847 * Any devices that didn't successfully probe go back to being treated as if
1848 * this function was never called.
1850 * This also means that some devices that aren't needed for init and could have
1851 * waited for their optional supplier to probe (when the supplier's module is
1852 * loaded later on) would end up probing prematurely with limited functionality.
1853 * So call this function only when boot would fail without it.
1855 void __init wait_for_init_devices_probe(void)
1857 if (!fw_devlink_flags || fw_devlink_is_permissive())
1861 * Wait for all ongoing probes to finish so that the "best effort" is
1862 * only applied to devices that can't probe otherwise.
1864 wait_for_device_probe();
1866 pr_info("Trying to probe devices needed for running init ...\n");
1867 fw_devlink_best_effort = true;
1868 driver_deferred_probe_trigger();
1871 * Wait for all "best effort" probes to finish before going back to
1872 * normal enforcement.
1874 wait_for_device_probe();
1875 fw_devlink_best_effort = false;
1878 static void fw_devlink_unblock_consumers(struct device *dev)
1880 struct device_link *link;
1882 if (!fw_devlink_flags || fw_devlink_is_permissive())
1885 device_links_write_lock();
1886 list_for_each_entry(link, &dev->links.consumers, s_node)
1887 fw_devlink_relax_link(link);
1888 device_links_write_unlock();
1891 #define get_dev_from_fwnode(fwnode) get_device((fwnode)->dev)
1893 static bool fwnode_init_without_drv(struct fwnode_handle *fwnode)
1898 if (!(fwnode->flags & FWNODE_FLAG_INITIALIZED))
1901 dev = get_dev_from_fwnode(fwnode);
1902 ret = !dev || dev->links.status == DL_DEV_NO_DRIVER;
1908 static bool fwnode_ancestor_init_without_drv(struct fwnode_handle *fwnode)
1910 struct fwnode_handle *parent;
1912 fwnode_for_each_parent_node(fwnode, parent) {
1913 if (fwnode_init_without_drv(parent)) {
1914 fwnode_handle_put(parent);
1923 * fwnode_is_ancestor_of - Test if @ancestor is ancestor of @child
1924 * @ancestor: Firmware which is tested for being an ancestor
1925 * @child: Firmware which is tested for being the child
1927 * A node is considered an ancestor of itself too.
1929 * Return: true if @ancestor is an ancestor of @child. Otherwise, returns false.
1931 static bool fwnode_is_ancestor_of(const struct fwnode_handle *ancestor,
1932 const struct fwnode_handle *child)
1934 struct fwnode_handle *parent;
1936 if (IS_ERR_OR_NULL(ancestor))
1939 if (child == ancestor)
1942 fwnode_for_each_parent_node(child, parent) {
1943 if (parent == ancestor) {
1944 fwnode_handle_put(parent);
1952 * fwnode_get_next_parent_dev - Find device of closest ancestor fwnode
1953 * @fwnode: firmware node
1955 * Given a firmware node (@fwnode), this function finds its closest ancestor
1956 * firmware node that has a corresponding struct device and returns that struct
1959 * The caller is responsible for calling put_device() on the returned device
1962 * Return: a pointer to the device of the @fwnode's closest ancestor.
1964 static struct device *fwnode_get_next_parent_dev(const struct fwnode_handle *fwnode)
1966 struct fwnode_handle *parent;
1969 fwnode_for_each_parent_node(fwnode, parent) {
1970 dev = get_dev_from_fwnode(parent);
1972 fwnode_handle_put(parent);
1980 * __fw_devlink_relax_cycles - Relax and mark dependency cycles.
1981 * @con: Potential consumer device.
1982 * @sup_handle: Potential supplier's fwnode.
1984 * Needs to be called with fwnode_lock and device link lock held.
1986 * Check if @sup_handle or any of its ancestors or suppliers direct/indirectly
1987 * depend on @con. This function can detect multiple cyles between @sup_handle
1988 * and @con. When such dependency cycles are found, convert all device links
1989 * created solely by fw_devlink into SYNC_STATE_ONLY device links. Also, mark
1990 * all fwnode links in the cycle with FWLINK_FLAG_CYCLE so that when they are
1991 * converted into a device link in the future, they are created as
1992 * SYNC_STATE_ONLY device links. This is the equivalent of doing
1993 * fw_devlink=permissive just between the devices in the cycle. We need to do
1994 * this because, at this point, fw_devlink can't tell which of these
1995 * dependencies is not a real dependency.
1997 * Return true if one or more cycles were found. Otherwise, return false.
1999 static bool __fw_devlink_relax_cycles(struct device *con,
2000 struct fwnode_handle *sup_handle)
2002 struct device *sup_dev = NULL, *par_dev = NULL;
2003 struct fwnode_link *link;
2004 struct device_link *dev_link;
2011 * We aren't trying to find all cycles. Just a cycle between con and
2014 if (sup_handle->flags & FWNODE_FLAG_VISITED)
2017 sup_handle->flags |= FWNODE_FLAG_VISITED;
2019 sup_dev = get_dev_from_fwnode(sup_handle);
2021 /* Termination condition. */
2022 if (sup_dev == con) {
2023 pr_debug("----- cycle: start -----\n");
2029 * If sup_dev is bound to a driver and @con hasn't started binding to a
2030 * driver, sup_dev can't be a consumer of @con. So, no need to check
2033 if (sup_dev && sup_dev->links.status == DL_DEV_DRIVER_BOUND &&
2034 con->links.status == DL_DEV_NO_DRIVER) {
2039 list_for_each_entry(link, &sup_handle->suppliers, c_hook) {
2040 if (link->flags & FWLINK_FLAG_IGNORE)
2043 if (__fw_devlink_relax_cycles(con, link->supplier)) {
2044 __fwnode_link_cycle(link);
2050 * Give priority to device parent over fwnode parent to account for any
2051 * quirks in how fwnodes are converted to devices.
2054 par_dev = get_device(sup_dev->parent);
2056 par_dev = fwnode_get_next_parent_dev(sup_handle);
2058 if (par_dev && __fw_devlink_relax_cycles(con, par_dev->fwnode)) {
2059 pr_debug("%pfwf: cycle: child of %pfwf\n", sup_handle,
2067 list_for_each_entry(dev_link, &sup_dev->links.suppliers, c_node) {
2069 * Ignore a SYNC_STATE_ONLY flag only if it wasn't marked as
2070 * such due to a cycle.
2072 if (device_link_flag_is_sync_state_only(dev_link->flags) &&
2073 !(dev_link->flags & DL_FLAG_CYCLE))
2076 if (__fw_devlink_relax_cycles(con,
2077 dev_link->supplier->fwnode)) {
2078 pr_debug("%pfwf: cycle: depends on %pfwf\n", sup_handle,
2079 dev_link->supplier->fwnode);
2080 fw_devlink_relax_link(dev_link);
2081 dev_link->flags |= DL_FLAG_CYCLE;
2087 sup_handle->flags &= ~FWNODE_FLAG_VISITED;
2088 put_device(sup_dev);
2089 put_device(par_dev);
2094 * fw_devlink_create_devlink - Create a device link from a consumer to fwnode
2095 * @con: consumer device for the device link
2096 * @sup_handle: fwnode handle of supplier
2097 * @link: fwnode link that's being converted to a device link
2099 * This function will try to create a device link between the consumer device
2100 * @con and the supplier device represented by @sup_handle.
2102 * The supplier has to be provided as a fwnode because incorrect cycles in
2103 * fwnode links can sometimes cause the supplier device to never be created.
2104 * This function detects such cases and returns an error if it cannot create a
2105 * device link from the consumer to a missing supplier.
2108 * 0 on successfully creating a device link
2109 * -EINVAL if the device link cannot be created as expected
2110 * -EAGAIN if the device link cannot be created right now, but it may be
2111 * possible to do that in the future
2113 static int fw_devlink_create_devlink(struct device *con,
2114 struct fwnode_handle *sup_handle,
2115 struct fwnode_link *link)
2117 struct device *sup_dev;
2121 if (link->flags & FWLINK_FLAG_IGNORE)
2124 if (con->fwnode == link->consumer)
2125 flags = fw_devlink_get_flags(link->flags);
2127 flags = FW_DEVLINK_FLAGS_PERMISSIVE;
2130 * In some cases, a device P might also be a supplier to its child node
2131 * C. However, this would defer the probe of C until the probe of P
2132 * completes successfully. This is perfectly fine in the device driver
2133 * model. device_add() doesn't guarantee probe completion of the device
2134 * by the time it returns.
2136 * However, there are a few drivers that assume C will finish probing
2137 * as soon as it's added and before P finishes probing. So, we provide
2138 * a flag to let fw_devlink know not to delay the probe of C until the
2139 * probe of P completes successfully.
2141 * When such a flag is set, we can't create device links where P is the
2142 * supplier of C as that would delay the probe of C.
2144 if (sup_handle->flags & FWNODE_FLAG_NEEDS_CHILD_BOUND_ON_ADD &&
2145 fwnode_is_ancestor_of(sup_handle, con->fwnode))
2149 * SYNC_STATE_ONLY device links don't block probing and supports cycles.
2150 * So, one might expect that cycle detection isn't necessary for them.
2151 * However, if the device link was marked as SYNC_STATE_ONLY because
2152 * it's part of a cycle, then we still need to do cycle detection. This
2153 * is because the consumer and supplier might be part of multiple cycles
2154 * and we need to detect all those cycles.
2156 if (!device_link_flag_is_sync_state_only(flags) ||
2157 flags & DL_FLAG_CYCLE) {
2158 device_links_write_lock();
2159 if (__fw_devlink_relax_cycles(con, sup_handle)) {
2160 __fwnode_link_cycle(link);
2161 flags = fw_devlink_get_flags(link->flags);
2162 pr_debug("----- cycle: end -----\n");
2163 dev_info(con, "Fixed dependency cycle(s) with %pfwf\n",
2166 device_links_write_unlock();
2169 if (sup_handle->flags & FWNODE_FLAG_NOT_DEVICE)
2170 sup_dev = fwnode_get_next_parent_dev(sup_handle);
2172 sup_dev = get_dev_from_fwnode(sup_handle);
2176 * If it's one of those drivers that don't actually bind to
2177 * their device using driver core, then don't wait on this
2178 * supplier device indefinitely.
2180 if (sup_dev->links.status == DL_DEV_NO_DRIVER &&
2181 sup_handle->flags & FWNODE_FLAG_INITIALIZED) {
2183 "Not linking %pfwf - dev might never probe\n",
2189 if (con != sup_dev && !device_link_add(con, sup_dev, flags)) {
2190 dev_err(con, "Failed to create device link (0x%x) with %s\n",
2191 flags, dev_name(sup_dev));
2199 * Supplier or supplier's ancestor already initialized without a struct
2200 * device or being probed by a driver.
2202 if (fwnode_init_without_drv(sup_handle) ||
2203 fwnode_ancestor_init_without_drv(sup_handle)) {
2204 dev_dbg(con, "Not linking %pfwf - might never become dev\n",
2211 put_device(sup_dev);
2216 * __fw_devlink_link_to_consumers - Create device links to consumers of a device
2217 * @dev: Device that needs to be linked to its consumers
2219 * This function looks at all the consumer fwnodes of @dev and creates device
2220 * links between the consumer device and @dev (supplier).
2222 * If the consumer device has not been added yet, then this function creates a
2223 * SYNC_STATE_ONLY link between @dev (supplier) and the closest ancestor device
2224 * of the consumer fwnode. This is necessary to make sure @dev doesn't get a
2225 * sync_state() callback before the real consumer device gets to be added and
2228 * Once device links are created from the real consumer to @dev (supplier), the
2229 * fwnode links are deleted.
2231 static void __fw_devlink_link_to_consumers(struct device *dev)
2233 struct fwnode_handle *fwnode = dev->fwnode;
2234 struct fwnode_link *link, *tmp;
2236 list_for_each_entry_safe(link, tmp, &fwnode->consumers, s_hook) {
2237 struct device *con_dev;
2238 bool own_link = true;
2241 con_dev = get_dev_from_fwnode(link->consumer);
2243 * If consumer device is not available yet, make a "proxy"
2244 * SYNC_STATE_ONLY link from the consumer's parent device to
2245 * the supplier device. This is necessary to make sure the
2246 * supplier doesn't get a sync_state() callback before the real
2247 * consumer can create a device link to the supplier.
2249 * This proxy link step is needed to handle the case where the
2250 * consumer's parent device is added before the supplier.
2253 con_dev = fwnode_get_next_parent_dev(link->consumer);
2255 * However, if the consumer's parent device is also the
2256 * parent of the supplier, don't create a
2257 * consumer-supplier link from the parent to its child
2258 * device. Such a dependency is impossible.
2261 fwnode_is_ancestor_of(con_dev->fwnode, fwnode)) {
2262 put_device(con_dev);
2272 ret = fw_devlink_create_devlink(con_dev, fwnode, link);
2273 put_device(con_dev);
2274 if (!own_link || ret == -EAGAIN)
2277 __fwnode_link_del(link);
2282 * __fw_devlink_link_to_suppliers - Create device links to suppliers of a device
2283 * @dev: The consumer device that needs to be linked to its suppliers
2284 * @fwnode: Root of the fwnode tree that is used to create device links
2286 * This function looks at all the supplier fwnodes of fwnode tree rooted at
2287 * @fwnode and creates device links between @dev (consumer) and all the
2288 * supplier devices of the entire fwnode tree at @fwnode.
2290 * The function creates normal (non-SYNC_STATE_ONLY) device links between @dev
2291 * and the real suppliers of @dev. Once these device links are created, the
2292 * fwnode links are deleted.
2294 * In addition, it also looks at all the suppliers of the entire fwnode tree
2295 * because some of the child devices of @dev that have not been added yet
2296 * (because @dev hasn't probed) might already have their suppliers added to
2297 * driver core. So, this function creates SYNC_STATE_ONLY device links between
2298 * @dev (consumer) and these suppliers to make sure they don't execute their
2299 * sync_state() callbacks before these child devices have a chance to create
2300 * their device links. The fwnode links that correspond to the child devices
2301 * aren't delete because they are needed later to create the device links
2302 * between the real consumer and supplier devices.
2304 static void __fw_devlink_link_to_suppliers(struct device *dev,
2305 struct fwnode_handle *fwnode)
2307 bool own_link = (dev->fwnode == fwnode);
2308 struct fwnode_link *link, *tmp;
2309 struct fwnode_handle *child = NULL;
2311 list_for_each_entry_safe(link, tmp, &fwnode->suppliers, c_hook) {
2313 struct fwnode_handle *sup = link->supplier;
2315 ret = fw_devlink_create_devlink(dev, sup, link);
2316 if (!own_link || ret == -EAGAIN)
2319 __fwnode_link_del(link);
2323 * Make "proxy" SYNC_STATE_ONLY device links to represent the needs of
2324 * all the descendants. This proxy link step is needed to handle the
2325 * case where the supplier is added before the consumer's parent device
2328 while ((child = fwnode_get_next_available_child_node(fwnode, child)))
2329 __fw_devlink_link_to_suppliers(dev, child);
2332 static void fw_devlink_link_device(struct device *dev)
2334 struct fwnode_handle *fwnode = dev->fwnode;
2336 if (!fw_devlink_flags)
2339 fw_devlink_parse_fwtree(fwnode);
2341 mutex_lock(&fwnode_link_lock);
2342 __fw_devlink_link_to_consumers(dev);
2343 __fw_devlink_link_to_suppliers(dev, fwnode);
2344 mutex_unlock(&fwnode_link_lock);
2347 /* Device links support end. */
2349 static struct kobject *dev_kobj;
2352 static struct kobject *sysfs_dev_char_kobj;
2354 /* /sys/dev/block */
2355 static struct kobject *sysfs_dev_block_kobj;
2357 static DEFINE_MUTEX(device_hotplug_lock);
2359 void lock_device_hotplug(void)
2361 mutex_lock(&device_hotplug_lock);
2364 void unlock_device_hotplug(void)
2366 mutex_unlock(&device_hotplug_lock);
2369 int lock_device_hotplug_sysfs(void)
2371 if (mutex_trylock(&device_hotplug_lock))
2374 /* Avoid busy looping (5 ms of sleep should do). */
2376 return restart_syscall();
2380 static inline int device_is_not_partition(struct device *dev)
2382 return !(dev->type == &part_type);
2385 static inline int device_is_not_partition(struct device *dev)
2391 static void device_platform_notify(struct device *dev)
2393 acpi_device_notify(dev);
2395 software_node_notify(dev);
2398 static void device_platform_notify_remove(struct device *dev)
2400 software_node_notify_remove(dev);
2402 acpi_device_notify_remove(dev);
2406 * dev_driver_string - Return a device's driver name, if at all possible
2407 * @dev: struct device to get the name of
2409 * Will return the device's driver's name if it is bound to a device. If
2410 * the device is not bound to a driver, it will return the name of the bus
2411 * it is attached to. If it is not attached to a bus either, an empty
2412 * string will be returned.
2414 const char *dev_driver_string(const struct device *dev)
2416 struct device_driver *drv;
2418 /* dev->driver can change to NULL underneath us because of unbinding,
2419 * so be careful about accessing it. dev->bus and dev->class should
2420 * never change once they are set, so they don't need special care.
2422 drv = READ_ONCE(dev->driver);
2423 return drv ? drv->name : dev_bus_name(dev);
2425 EXPORT_SYMBOL(dev_driver_string);
2427 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
2429 static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr,
2432 struct device_attribute *dev_attr = to_dev_attr(attr);
2433 struct device *dev = kobj_to_dev(kobj);
2437 ret = dev_attr->show(dev, dev_attr, buf);
2438 if (ret >= (ssize_t)PAGE_SIZE) {
2439 printk("dev_attr_show: %pS returned bad count\n",
2445 static ssize_t dev_attr_store(struct kobject *kobj, struct attribute *attr,
2446 const char *buf, size_t count)
2448 struct device_attribute *dev_attr = to_dev_attr(attr);
2449 struct device *dev = kobj_to_dev(kobj);
2452 if (dev_attr->store)
2453 ret = dev_attr->store(dev, dev_attr, buf, count);
2457 static const struct sysfs_ops dev_sysfs_ops = {
2458 .show = dev_attr_show,
2459 .store = dev_attr_store,
2462 #define to_ext_attr(x) container_of(x, struct dev_ext_attribute, attr)
2464 ssize_t device_store_ulong(struct device *dev,
2465 struct device_attribute *attr,
2466 const char *buf, size_t size)
2468 struct dev_ext_attribute *ea = to_ext_attr(attr);
2472 ret = kstrtoul(buf, 0, &new);
2475 *(unsigned long *)(ea->var) = new;
2476 /* Always return full write size even if we didn't consume all */
2479 EXPORT_SYMBOL_GPL(device_store_ulong);
2481 ssize_t device_show_ulong(struct device *dev,
2482 struct device_attribute *attr,
2485 struct dev_ext_attribute *ea = to_ext_attr(attr);
2486 return sysfs_emit(buf, "%lx\n", *(unsigned long *)(ea->var));
2488 EXPORT_SYMBOL_GPL(device_show_ulong);
2490 ssize_t device_store_int(struct device *dev,
2491 struct device_attribute *attr,
2492 const char *buf, size_t size)
2494 struct dev_ext_attribute *ea = to_ext_attr(attr);
2498 ret = kstrtol(buf, 0, &new);
2502 if (new > INT_MAX || new < INT_MIN)
2504 *(int *)(ea->var) = new;
2505 /* Always return full write size even if we didn't consume all */
2508 EXPORT_SYMBOL_GPL(device_store_int);
2510 ssize_t device_show_int(struct device *dev,
2511 struct device_attribute *attr,
2514 struct dev_ext_attribute *ea = to_ext_attr(attr);
2516 return sysfs_emit(buf, "%d\n", *(int *)(ea->var));
2518 EXPORT_SYMBOL_GPL(device_show_int);
2520 ssize_t device_store_bool(struct device *dev, struct device_attribute *attr,
2521 const char *buf, size_t size)
2523 struct dev_ext_attribute *ea = to_ext_attr(attr);
2525 if (kstrtobool(buf, ea->var) < 0)
2530 EXPORT_SYMBOL_GPL(device_store_bool);
2532 ssize_t device_show_bool(struct device *dev, struct device_attribute *attr,
2535 struct dev_ext_attribute *ea = to_ext_attr(attr);
2537 return sysfs_emit(buf, "%d\n", *(bool *)(ea->var));
2539 EXPORT_SYMBOL_GPL(device_show_bool);
2541 ssize_t device_show_string(struct device *dev,
2542 struct device_attribute *attr, char *buf)
2544 struct dev_ext_attribute *ea = to_ext_attr(attr);
2546 return sysfs_emit(buf, "%s\n", (char *)ea->var);
2548 EXPORT_SYMBOL_GPL(device_show_string);
2551 * device_release - free device structure.
2552 * @kobj: device's kobject.
2554 * This is called once the reference count for the object
2555 * reaches 0. We forward the call to the device's release
2556 * method, which should handle actually freeing the structure.
2558 static void device_release(struct kobject *kobj)
2560 struct device *dev = kobj_to_dev(kobj);
2561 struct device_private *p = dev->p;
2564 * Some platform devices are driven without driver attached
2565 * and managed resources may have been acquired. Make sure
2566 * all resources are released.
2568 * Drivers still can add resources into device after device
2569 * is deleted but alive, so release devres here to avoid
2570 * possible memory leak.
2572 devres_release_all(dev);
2574 kfree(dev->dma_range_map);
2578 else if (dev->type && dev->type->release)
2579 dev->type->release(dev);
2580 else if (dev->class && dev->class->dev_release)
2581 dev->class->dev_release(dev);
2583 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",
2588 static const void *device_namespace(const struct kobject *kobj)
2590 const struct device *dev = kobj_to_dev(kobj);
2591 const void *ns = NULL;
2593 if (dev->class && dev->class->ns_type)
2594 ns = dev->class->namespace(dev);
2599 static void device_get_ownership(const struct kobject *kobj, kuid_t *uid, kgid_t *gid)
2601 const struct device *dev = kobj_to_dev(kobj);
2603 if (dev->class && dev->class->get_ownership)
2604 dev->class->get_ownership(dev, uid, gid);
2607 static const struct kobj_type device_ktype = {
2608 .release = device_release,
2609 .sysfs_ops = &dev_sysfs_ops,
2610 .namespace = device_namespace,
2611 .get_ownership = device_get_ownership,
2615 static int dev_uevent_filter(const struct kobject *kobj)
2617 const struct kobj_type *ktype = get_ktype(kobj);
2619 if (ktype == &device_ktype) {
2620 const struct device *dev = kobj_to_dev(kobj);
2629 static const char *dev_uevent_name(const struct kobject *kobj)
2631 const struct device *dev = kobj_to_dev(kobj);
2634 return dev->bus->name;
2636 return dev->class->name;
2640 static int dev_uevent(const struct kobject *kobj, struct kobj_uevent_env *env)
2642 const struct device *dev = kobj_to_dev(kobj);
2645 /* add device node properties if present */
2646 if (MAJOR(dev->devt)) {
2650 kuid_t uid = GLOBAL_ROOT_UID;
2651 kgid_t gid = GLOBAL_ROOT_GID;
2653 add_uevent_var(env, "MAJOR=%u", MAJOR(dev->devt));
2654 add_uevent_var(env, "MINOR=%u", MINOR(dev->devt));
2655 name = device_get_devnode(dev, &mode, &uid, &gid, &tmp);
2657 add_uevent_var(env, "DEVNAME=%s", name);
2659 add_uevent_var(env, "DEVMODE=%#o", mode & 0777);
2660 if (!uid_eq(uid, GLOBAL_ROOT_UID))
2661 add_uevent_var(env, "DEVUID=%u", from_kuid(&init_user_ns, uid));
2662 if (!gid_eq(gid, GLOBAL_ROOT_GID))
2663 add_uevent_var(env, "DEVGID=%u", from_kgid(&init_user_ns, gid));
2668 if (dev->type && dev->type->name)
2669 add_uevent_var(env, "DEVTYPE=%s", dev->type->name);
2672 add_uevent_var(env, "DRIVER=%s", dev->driver->name);
2674 /* Add common DT information about the device */
2675 of_device_uevent(dev, env);
2677 /* have the bus specific function add its stuff */
2678 if (dev->bus && dev->bus->uevent) {
2679 retval = dev->bus->uevent(dev, env);
2681 pr_debug("device: '%s': %s: bus uevent() returned %d\n",
2682 dev_name(dev), __func__, retval);
2685 /* have the class specific function add its stuff */
2686 if (dev->class && dev->class->dev_uevent) {
2687 retval = dev->class->dev_uevent(dev, env);
2689 pr_debug("device: '%s': %s: class uevent() "
2690 "returned %d\n", dev_name(dev),
2694 /* have the device type specific function add its stuff */
2695 if (dev->type && dev->type->uevent) {
2696 retval = dev->type->uevent(dev, env);
2698 pr_debug("device: '%s': %s: dev_type uevent() "
2699 "returned %d\n", dev_name(dev),
2706 static const struct kset_uevent_ops device_uevent_ops = {
2707 .filter = dev_uevent_filter,
2708 .name = dev_uevent_name,
2709 .uevent = dev_uevent,
2712 static ssize_t uevent_show(struct device *dev, struct device_attribute *attr,
2715 struct kobject *top_kobj;
2717 struct kobj_uevent_env *env = NULL;
2722 /* search the kset, the device belongs to */
2723 top_kobj = &dev->kobj;
2724 while (!top_kobj->kset && top_kobj->parent)
2725 top_kobj = top_kobj->parent;
2726 if (!top_kobj->kset)
2729 kset = top_kobj->kset;
2730 if (!kset->uevent_ops || !kset->uevent_ops->uevent)
2733 /* respect filter */
2734 if (kset->uevent_ops && kset->uevent_ops->filter)
2735 if (!kset->uevent_ops->filter(&dev->kobj))
2738 env = kzalloc(sizeof(struct kobj_uevent_env), GFP_KERNEL);
2742 /* let the kset specific function add its keys */
2743 retval = kset->uevent_ops->uevent(&dev->kobj, env);
2747 /* copy keys to file */
2748 for (i = 0; i < env->envp_idx; i++)
2749 len += sysfs_emit_at(buf, len, "%s\n", env->envp[i]);
2755 static ssize_t uevent_store(struct device *dev, struct device_attribute *attr,
2756 const char *buf, size_t count)
2760 rc = kobject_synth_uevent(&dev->kobj, buf, count);
2763 dev_err(dev, "uevent: failed to send synthetic uevent: %d\n", rc);
2769 static DEVICE_ATTR_RW(uevent);
2771 static ssize_t online_show(struct device *dev, struct device_attribute *attr,
2777 val = !dev->offline;
2779 return sysfs_emit(buf, "%u\n", val);
2782 static ssize_t online_store(struct device *dev, struct device_attribute *attr,
2783 const char *buf, size_t count)
2788 ret = kstrtobool(buf, &val);
2792 ret = lock_device_hotplug_sysfs();
2796 ret = val ? device_online(dev) : device_offline(dev);
2797 unlock_device_hotplug();
2798 return ret < 0 ? ret : count;
2800 static DEVICE_ATTR_RW(online);
2802 static ssize_t removable_show(struct device *dev, struct device_attribute *attr,
2807 switch (dev->removable) {
2808 case DEVICE_REMOVABLE:
2817 return sysfs_emit(buf, "%s\n", loc);
2819 static DEVICE_ATTR_RO(removable);
2821 int device_add_groups(struct device *dev, const struct attribute_group **groups)
2823 return sysfs_create_groups(&dev->kobj, groups);
2825 EXPORT_SYMBOL_GPL(device_add_groups);
2827 void device_remove_groups(struct device *dev,
2828 const struct attribute_group **groups)
2830 sysfs_remove_groups(&dev->kobj, groups);
2832 EXPORT_SYMBOL_GPL(device_remove_groups);
2834 union device_attr_group_devres {
2835 const struct attribute_group *group;
2836 const struct attribute_group **groups;
2839 static void devm_attr_group_remove(struct device *dev, void *res)
2841 union device_attr_group_devres *devres = res;
2842 const struct attribute_group *group = devres->group;
2844 dev_dbg(dev, "%s: removing group %p\n", __func__, group);
2845 sysfs_remove_group(&dev->kobj, group);
2848 static void devm_attr_groups_remove(struct device *dev, void *res)
2850 union device_attr_group_devres *devres = res;
2851 const struct attribute_group **groups = devres->groups;
2853 dev_dbg(dev, "%s: removing groups %p\n", __func__, groups);
2854 sysfs_remove_groups(&dev->kobj, groups);
2858 * devm_device_add_group - given a device, create a managed attribute group
2859 * @dev: The device to create the group for
2860 * @grp: The attribute group to create
2862 * This function creates a group for the first time. It will explicitly
2863 * warn and error if any of the attribute files being created already exist.
2865 * Returns 0 on success or error code on failure.
2867 int devm_device_add_group(struct device *dev, const struct attribute_group *grp)
2869 union device_attr_group_devres *devres;
2872 devres = devres_alloc(devm_attr_group_remove,
2873 sizeof(*devres), GFP_KERNEL);
2877 error = sysfs_create_group(&dev->kobj, grp);
2879 devres_free(devres);
2883 devres->group = grp;
2884 devres_add(dev, devres);
2887 EXPORT_SYMBOL_GPL(devm_device_add_group);
2890 * devm_device_add_groups - create a bunch of managed attribute groups
2891 * @dev: The device to create the group for
2892 * @groups: The attribute groups to create, NULL terminated
2894 * This function creates a bunch of managed attribute groups. If an error
2895 * occurs when creating a group, all previously created groups will be
2896 * removed, unwinding everything back to the original state when this
2897 * function was called. It will explicitly warn and error if any of the
2898 * attribute files being created already exist.
2900 * Returns 0 on success or error code from sysfs_create_group on failure.
2902 int devm_device_add_groups(struct device *dev,
2903 const struct attribute_group **groups)
2905 union device_attr_group_devres *devres;
2908 devres = devres_alloc(devm_attr_groups_remove,
2909 sizeof(*devres), GFP_KERNEL);
2913 error = sysfs_create_groups(&dev->kobj, groups);
2915 devres_free(devres);
2919 devres->groups = groups;
2920 devres_add(dev, devres);
2923 EXPORT_SYMBOL_GPL(devm_device_add_groups);
2925 static int device_add_attrs(struct device *dev)
2927 const struct class *class = dev->class;
2928 const struct device_type *type = dev->type;
2932 error = device_add_groups(dev, class->dev_groups);
2938 error = device_add_groups(dev, type->groups);
2940 goto err_remove_class_groups;
2943 error = device_add_groups(dev, dev->groups);
2945 goto err_remove_type_groups;
2947 if (device_supports_offline(dev) && !dev->offline_disabled) {
2948 error = device_create_file(dev, &dev_attr_online);
2950 goto err_remove_dev_groups;
2953 if (fw_devlink_flags && !fw_devlink_is_permissive() && dev->fwnode) {
2954 error = device_create_file(dev, &dev_attr_waiting_for_supplier);
2956 goto err_remove_dev_online;
2959 if (dev_removable_is_valid(dev)) {
2960 error = device_create_file(dev, &dev_attr_removable);
2962 goto err_remove_dev_waiting_for_supplier;
2965 if (dev_add_physical_location(dev)) {
2966 error = device_add_group(dev,
2967 &dev_attr_physical_location_group);
2969 goto err_remove_dev_removable;
2974 err_remove_dev_removable:
2975 device_remove_file(dev, &dev_attr_removable);
2976 err_remove_dev_waiting_for_supplier:
2977 device_remove_file(dev, &dev_attr_waiting_for_supplier);
2978 err_remove_dev_online:
2979 device_remove_file(dev, &dev_attr_online);
2980 err_remove_dev_groups:
2981 device_remove_groups(dev, dev->groups);
2982 err_remove_type_groups:
2984 device_remove_groups(dev, type->groups);
2985 err_remove_class_groups:
2987 device_remove_groups(dev, class->dev_groups);
2992 static void device_remove_attrs(struct device *dev)
2994 const struct class *class = dev->class;
2995 const struct device_type *type = dev->type;
2997 if (dev->physical_location) {
2998 device_remove_group(dev, &dev_attr_physical_location_group);
2999 kfree(dev->physical_location);
3002 device_remove_file(dev, &dev_attr_removable);
3003 device_remove_file(dev, &dev_attr_waiting_for_supplier);
3004 device_remove_file(dev, &dev_attr_online);
3005 device_remove_groups(dev, dev->groups);
3008 device_remove_groups(dev, type->groups);
3011 device_remove_groups(dev, class->dev_groups);
3014 static ssize_t dev_show(struct device *dev, struct device_attribute *attr,
3017 return print_dev_t(buf, dev->devt);
3019 static DEVICE_ATTR_RO(dev);
3022 struct kset *devices_kset;
3025 * devices_kset_move_before - Move device in the devices_kset's list.
3026 * @deva: Device to move.
3027 * @devb: Device @deva should come before.
3029 static void devices_kset_move_before(struct device *deva, struct device *devb)
3033 pr_debug("devices_kset: Moving %s before %s\n",
3034 dev_name(deva), dev_name(devb));
3035 spin_lock(&devices_kset->list_lock);
3036 list_move_tail(&deva->kobj.entry, &devb->kobj.entry);
3037 spin_unlock(&devices_kset->list_lock);
3041 * devices_kset_move_after - Move device in the devices_kset's list.
3042 * @deva: Device to move
3043 * @devb: Device @deva should come after.
3045 static void devices_kset_move_after(struct device *deva, struct device *devb)
3049 pr_debug("devices_kset: Moving %s after %s\n",
3050 dev_name(deva), dev_name(devb));
3051 spin_lock(&devices_kset->list_lock);
3052 list_move(&deva->kobj.entry, &devb->kobj.entry);
3053 spin_unlock(&devices_kset->list_lock);
3057 * devices_kset_move_last - move the device to the end of devices_kset's list.
3058 * @dev: device to move
3060 void devices_kset_move_last(struct device *dev)
3064 pr_debug("devices_kset: Moving %s to end of list\n", dev_name(dev));
3065 spin_lock(&devices_kset->list_lock);
3066 list_move_tail(&dev->kobj.entry, &devices_kset->list);
3067 spin_unlock(&devices_kset->list_lock);
3071 * device_create_file - create sysfs attribute file for device.
3073 * @attr: device attribute descriptor.
3075 int device_create_file(struct device *dev,
3076 const struct device_attribute *attr)
3081 WARN(((attr->attr.mode & S_IWUGO) && !attr->store),
3082 "Attribute %s: write permission without 'store'\n",
3084 WARN(((attr->attr.mode & S_IRUGO) && !attr->show),
3085 "Attribute %s: read permission without 'show'\n",
3087 error = sysfs_create_file(&dev->kobj, &attr->attr);
3092 EXPORT_SYMBOL_GPL(device_create_file);
3095 * device_remove_file - remove sysfs attribute file.
3097 * @attr: device attribute descriptor.
3099 void device_remove_file(struct device *dev,
3100 const struct device_attribute *attr)
3103 sysfs_remove_file(&dev->kobj, &attr->attr);
3105 EXPORT_SYMBOL_GPL(device_remove_file);
3108 * device_remove_file_self - remove sysfs attribute file from its own method.
3110 * @attr: device attribute descriptor.
3112 * See kernfs_remove_self() for details.
3114 bool device_remove_file_self(struct device *dev,
3115 const struct device_attribute *attr)
3118 return sysfs_remove_file_self(&dev->kobj, &attr->attr);
3122 EXPORT_SYMBOL_GPL(device_remove_file_self);
3125 * device_create_bin_file - create sysfs binary attribute file for device.
3127 * @attr: device binary attribute descriptor.
3129 int device_create_bin_file(struct device *dev,
3130 const struct bin_attribute *attr)
3132 int error = -EINVAL;
3134 error = sysfs_create_bin_file(&dev->kobj, attr);
3137 EXPORT_SYMBOL_GPL(device_create_bin_file);
3140 * device_remove_bin_file - remove sysfs binary attribute file
3142 * @attr: device binary attribute descriptor.
3144 void device_remove_bin_file(struct device *dev,
3145 const struct bin_attribute *attr)
3148 sysfs_remove_bin_file(&dev->kobj, attr);
3150 EXPORT_SYMBOL_GPL(device_remove_bin_file);
3152 static void klist_children_get(struct klist_node *n)
3154 struct device_private *p = to_device_private_parent(n);
3155 struct device *dev = p->device;
3160 static void klist_children_put(struct klist_node *n)
3162 struct device_private *p = to_device_private_parent(n);
3163 struct device *dev = p->device;
3169 * device_initialize - init device structure.
3172 * This prepares the device for use by other layers by initializing
3174 * It is the first half of device_register(), if called by
3175 * that function, though it can also be called separately, so one
3176 * may use @dev's fields. In particular, get_device()/put_device()
3177 * may be used for reference counting of @dev after calling this
3180 * All fields in @dev must be initialized by the caller to 0, except
3181 * for those explicitly set to some other value. The simplest
3182 * approach is to use kzalloc() to allocate the structure containing
3185 * NOTE: Use put_device() to give up your reference instead of freeing
3186 * @dev directly once you have called this function.
3188 void device_initialize(struct device *dev)
3190 dev->kobj.kset = devices_kset;
3191 kobject_init(&dev->kobj, &device_ktype);
3192 INIT_LIST_HEAD(&dev->dma_pools);
3193 mutex_init(&dev->mutex);
3194 lockdep_set_novalidate_class(&dev->mutex);
3195 spin_lock_init(&dev->devres_lock);
3196 INIT_LIST_HEAD(&dev->devres_head);
3197 device_pm_init(dev);
3198 set_dev_node(dev, NUMA_NO_NODE);
3199 INIT_LIST_HEAD(&dev->links.consumers);
3200 INIT_LIST_HEAD(&dev->links.suppliers);
3201 INIT_LIST_HEAD(&dev->links.defer_sync);
3202 dev->links.status = DL_DEV_NO_DRIVER;
3203 #if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
3204 defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
3205 defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL)
3206 dev->dma_coherent = dma_default_coherent;
3208 swiotlb_dev_init(dev);
3210 EXPORT_SYMBOL_GPL(device_initialize);
3212 struct kobject *virtual_device_parent(struct device *dev)
3214 static struct kobject *virtual_dir = NULL;
3217 virtual_dir = kobject_create_and_add("virtual",
3218 &devices_kset->kobj);
3224 struct kobject kobj;
3225 const struct class *class;
3228 #define to_class_dir(obj) container_of(obj, struct class_dir, kobj)
3230 static void class_dir_release(struct kobject *kobj)
3232 struct class_dir *dir = to_class_dir(kobj);
3237 struct kobj_ns_type_operations *class_dir_child_ns_type(const struct kobject *kobj)
3239 const struct class_dir *dir = to_class_dir(kobj);
3240 return dir->class->ns_type;
3243 static const struct kobj_type class_dir_ktype = {
3244 .release = class_dir_release,
3245 .sysfs_ops = &kobj_sysfs_ops,
3246 .child_ns_type = class_dir_child_ns_type
3249 static struct kobject *class_dir_create_and_add(struct subsys_private *sp,
3250 struct kobject *parent_kobj)
3252 struct class_dir *dir;
3255 dir = kzalloc(sizeof(*dir), GFP_KERNEL);
3257 return ERR_PTR(-ENOMEM);
3259 dir->class = sp->class;
3260 kobject_init(&dir->kobj, &class_dir_ktype);
3262 dir->kobj.kset = &sp->glue_dirs;
3264 retval = kobject_add(&dir->kobj, parent_kobj, "%s", sp->class->name);
3266 kobject_put(&dir->kobj);
3267 return ERR_PTR(retval);
3272 static DEFINE_MUTEX(gdp_mutex);
3274 static struct kobject *get_device_parent(struct device *dev,
3275 struct device *parent)
3277 struct subsys_private *sp = class_to_subsys(dev->class);
3278 struct kobject *kobj = NULL;
3281 struct kobject *parent_kobj;
3285 * If we have no parent, we live in "virtual".
3286 * Class-devices with a non class-device as parent, live
3287 * in a "glue" directory to prevent namespace collisions.
3290 parent_kobj = virtual_device_parent(dev);
3291 else if (parent->class && !dev->class->ns_type) {
3293 return &parent->kobj;
3295 parent_kobj = &parent->kobj;
3298 mutex_lock(&gdp_mutex);
3300 /* find our class-directory at the parent and reference it */
3301 spin_lock(&sp->glue_dirs.list_lock);
3302 list_for_each_entry(k, &sp->glue_dirs.list, entry)
3303 if (k->parent == parent_kobj) {
3304 kobj = kobject_get(k);
3307 spin_unlock(&sp->glue_dirs.list_lock);
3309 mutex_unlock(&gdp_mutex);
3314 /* or create a new class-directory at the parent device */
3315 k = class_dir_create_and_add(sp, parent_kobj);
3316 /* do not emit an uevent for this simple "glue" directory */
3317 mutex_unlock(&gdp_mutex);
3322 /* subsystems can specify a default root directory for their devices */
3323 if (!parent && dev->bus) {
3324 struct device *dev_root = bus_get_dev_root(dev->bus);
3327 kobj = &dev_root->kobj;
3328 put_device(dev_root);
3334 return &parent->kobj;
3338 static inline bool live_in_glue_dir(struct kobject *kobj,
3341 struct subsys_private *sp;
3344 if (!kobj || !dev->class)
3347 sp = class_to_subsys(dev->class);
3351 if (kobj->kset == &sp->glue_dirs)
3360 static inline struct kobject *get_glue_dir(struct device *dev)
3362 return dev->kobj.parent;
3366 * kobject_has_children - Returns whether a kobject has children.
3367 * @kobj: the object to test
3369 * This will return whether a kobject has other kobjects as children.
3371 * It does NOT account for the presence of attribute files, only sub
3372 * directories. It also assumes there is no concurrent addition or
3373 * removal of such children, and thus relies on external locking.
3375 static inline bool kobject_has_children(struct kobject *kobj)
3377 WARN_ON_ONCE(kref_read(&kobj->kref) == 0);
3379 return kobj->sd && kobj->sd->dir.subdirs;
3383 * make sure cleaning up dir as the last step, we need to make
3384 * sure .release handler of kobject is run with holding the
3387 static void cleanup_glue_dir(struct device *dev, struct kobject *glue_dir)
3391 /* see if we live in a "glue" directory */
3392 if (!live_in_glue_dir(glue_dir, dev))
3395 mutex_lock(&gdp_mutex);
3397 * There is a race condition between removing glue directory
3398 * and adding a new device under the glue directory.
3403 * get_device_parent()
3404 * class_dir_create_and_add()
3405 * kobject_add_internal()
3406 * create_dir() // create glue_dir
3409 * get_device_parent()
3410 * kobject_get() // get glue_dir
3413 * cleanup_glue_dir()
3414 * kobject_del(glue_dir)
3417 * kobject_add_internal()
3418 * create_dir() // in glue_dir
3419 * sysfs_create_dir_ns()
3420 * kernfs_create_dir_ns(sd)
3422 * sysfs_remove_dir() // glue_dir->sd=NULL
3423 * sysfs_put() // free glue_dir->sd
3426 * kernfs_new_node(sd)
3427 * kernfs_get(glue_dir)
3431 * Before CPU1 remove last child device under glue dir, if CPU2 add
3432 * a new device under glue dir, the glue_dir kobject reference count
3433 * will be increase to 2 in kobject_get(k). And CPU2 has been called
3434 * kernfs_create_dir_ns(). Meanwhile, CPU1 call sysfs_remove_dir()
3435 * and sysfs_put(). This result in glue_dir->sd is freed.
3437 * Then the CPU2 will see a stale "empty" but still potentially used
3438 * glue dir around in kernfs_new_node().
3440 * In order to avoid this happening, we also should make sure that
3441 * kernfs_node for glue_dir is released in CPU1 only when refcount
3442 * for glue_dir kobj is 1.
3444 ref = kref_read(&glue_dir->kref);
3445 if (!kobject_has_children(glue_dir) && !--ref)
3446 kobject_del(glue_dir);
3447 kobject_put(glue_dir);
3448 mutex_unlock(&gdp_mutex);
3451 static int device_add_class_symlinks(struct device *dev)
3453 struct device_node *of_node = dev_of_node(dev);
3454 struct subsys_private *sp;
3458 error = sysfs_create_link(&dev->kobj, of_node_kobj(of_node), "of_node");
3460 dev_warn(dev, "Error %d creating of_node link\n",error);
3461 /* An error here doesn't warrant bringing down the device */
3464 sp = class_to_subsys(dev->class);
3468 error = sysfs_create_link(&dev->kobj, &sp->subsys.kobj, "subsystem");
3472 if (dev->parent && device_is_not_partition(dev)) {
3473 error = sysfs_create_link(&dev->kobj, &dev->parent->kobj,
3479 /* link in the class directory pointing to the device */
3480 error = sysfs_create_link(&sp->subsys.kobj, &dev->kobj, dev_name(dev));
3486 sysfs_remove_link(&dev->kobj, "device");
3488 sysfs_remove_link(&dev->kobj, "subsystem");
3490 sysfs_remove_link(&dev->kobj, "of_node");
3496 static void device_remove_class_symlinks(struct device *dev)
3498 struct subsys_private *sp = class_to_subsys(dev->class);
3500 if (dev_of_node(dev))
3501 sysfs_remove_link(&dev->kobj, "of_node");
3506 if (dev->parent && device_is_not_partition(dev))
3507 sysfs_remove_link(&dev->kobj, "device");
3508 sysfs_remove_link(&dev->kobj, "subsystem");
3509 sysfs_delete_link(&sp->subsys.kobj, &dev->kobj, dev_name(dev));
3514 * dev_set_name - set a device name
3516 * @fmt: format string for the device's name
3518 int dev_set_name(struct device *dev, const char *fmt, ...)
3523 va_start(vargs, fmt);
3524 err = kobject_set_name_vargs(&dev->kobj, fmt, vargs);
3528 EXPORT_SYMBOL_GPL(dev_set_name);
3530 /* select a /sys/dev/ directory for the device */
3531 static struct kobject *device_to_dev_kobj(struct device *dev)
3533 if (is_blockdev(dev))
3534 return sysfs_dev_block_kobj;
3536 return sysfs_dev_char_kobj;
3539 static int device_create_sys_dev_entry(struct device *dev)
3541 struct kobject *kobj = device_to_dev_kobj(dev);
3546 format_dev_t(devt_str, dev->devt);
3547 error = sysfs_create_link(kobj, &dev->kobj, devt_str);
3553 static void device_remove_sys_dev_entry(struct device *dev)
3555 struct kobject *kobj = device_to_dev_kobj(dev);
3559 format_dev_t(devt_str, dev->devt);
3560 sysfs_remove_link(kobj, devt_str);
3564 static int device_private_init(struct device *dev)
3566 dev->p = kzalloc(sizeof(*dev->p), GFP_KERNEL);
3569 dev->p->device = dev;
3570 klist_init(&dev->p->klist_children, klist_children_get,
3571 klist_children_put);
3572 INIT_LIST_HEAD(&dev->p->deferred_probe);
3577 * device_add - add device to device hierarchy.
3580 * This is part 2 of device_register(), though may be called
3581 * separately _iff_ device_initialize() has been called separately.
3583 * This adds @dev to the kobject hierarchy via kobject_add(), adds it
3584 * to the global and sibling lists for the device, then
3585 * adds it to the other relevant subsystems of the driver model.
3587 * Do not call this routine or device_register() more than once for
3588 * any device structure. The driver model core is not designed to work
3589 * with devices that get unregistered and then spring back to life.
3590 * (Among other things, it's very hard to guarantee that all references
3591 * to the previous incarnation of @dev have been dropped.) Allocate
3592 * and register a fresh new struct device instead.
3594 * NOTE: _Never_ directly free @dev after calling this function, even
3595 * if it returned an error! Always use put_device() to give up your
3596 * reference instead.
3598 * Rule of thumb is: if device_add() succeeds, you should call
3599 * device_del() when you want to get rid of it. If device_add() has
3600 * *not* succeeded, use *only* put_device() to drop the reference
3603 int device_add(struct device *dev)
3605 struct subsys_private *sp;
3606 struct device *parent;
3607 struct kobject *kobj;
3608 struct class_interface *class_intf;
3609 int error = -EINVAL;
3610 struct kobject *glue_dir = NULL;
3612 dev = get_device(dev);
3617 error = device_private_init(dev);
3623 * for statically allocated devices, which should all be converted
3624 * some day, we need to initialize the name. We prevent reading back
3625 * the name, and force the use of dev_name()
3627 if (dev->init_name) {
3628 error = dev_set_name(dev, "%s", dev->init_name);
3629 dev->init_name = NULL;
3634 /* subsystems can specify simple device enumeration */
3635 else if (dev->bus && dev->bus->dev_name)
3636 error = dev_set_name(dev, "%s%u", dev->bus->dev_name, dev->id);
3642 pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
3644 parent = get_device(dev->parent);
3645 kobj = get_device_parent(dev, parent);
3647 error = PTR_ERR(kobj);
3651 dev->kobj.parent = kobj;
3653 /* use parent numa_node */
3654 if (parent && (dev_to_node(dev) == NUMA_NO_NODE))
3655 set_dev_node(dev, dev_to_node(parent));
3657 /* first, register with generic layer. */
3658 /* we require the name to be set before, and pass NULL */
3659 error = kobject_add(&dev->kobj, dev->kobj.parent, NULL);
3665 /* notify platform of device entry */
3666 device_platform_notify(dev);
3668 error = device_create_file(dev, &dev_attr_uevent);
3672 error = device_add_class_symlinks(dev);
3675 error = device_add_attrs(dev);
3678 error = bus_add_device(dev);
3681 error = dpm_sysfs_add(dev);
3686 if (MAJOR(dev->devt)) {
3687 error = device_create_file(dev, &dev_attr_dev);
3691 error = device_create_sys_dev_entry(dev);
3695 devtmpfs_create_node(dev);
3698 /* Notify clients of device addition. This call must come
3699 * after dpm_sysfs_add() and before kobject_uevent().
3701 bus_notify(dev, BUS_NOTIFY_ADD_DEVICE);
3702 kobject_uevent(&dev->kobj, KOBJ_ADD);
3705 * Check if any of the other devices (consumers) have been waiting for
3706 * this device (supplier) to be added so that they can create a device
3709 * This needs to happen after device_pm_add() because device_link_add()
3710 * requires the supplier be registered before it's called.
3712 * But this also needs to happen before bus_probe_device() to make sure
3713 * waiting consumers can link to it before the driver is bound to the
3714 * device and the driver sync_state callback is called for this device.
3716 if (dev->fwnode && !dev->fwnode->dev) {
3717 dev->fwnode->dev = dev;
3718 fw_devlink_link_device(dev);
3721 bus_probe_device(dev);
3724 * If all driver registration is done and a newly added device doesn't
3725 * match with any driver, don't block its consumers from probing in
3726 * case the consumer device is able to operate without this supplier.
3728 if (dev->fwnode && fw_devlink_drv_reg_done && !dev->can_match)
3729 fw_devlink_unblock_consumers(dev);
3732 klist_add_tail(&dev->p->knode_parent,
3733 &parent->p->klist_children);
3735 sp = class_to_subsys(dev->class);
3737 mutex_lock(&sp->mutex);
3738 /* tie the class to the device */
3739 klist_add_tail(&dev->p->knode_class, &sp->klist_devices);
3741 /* notify any interfaces that the device is here */
3742 list_for_each_entry(class_intf, &sp->interfaces, node)
3743 if (class_intf->add_dev)
3744 class_intf->add_dev(dev);
3745 mutex_unlock(&sp->mutex);
3752 if (MAJOR(dev->devt))
3753 device_remove_file(dev, &dev_attr_dev);
3755 device_pm_remove(dev);
3756 dpm_sysfs_remove(dev);
3759 bus_remove_device(dev);
3761 device_remove_attrs(dev);
3763 device_remove_class_symlinks(dev);
3765 device_remove_file(dev, &dev_attr_uevent);
3767 device_platform_notify_remove(dev);
3768 kobject_uevent(&dev->kobj, KOBJ_REMOVE);
3769 glue_dir = get_glue_dir(dev);
3770 kobject_del(&dev->kobj);
3772 cleanup_glue_dir(dev, glue_dir);
3780 EXPORT_SYMBOL_GPL(device_add);
3783 * device_register - register a device with the system.
3784 * @dev: pointer to the device structure
3786 * This happens in two clean steps - initialize the device
3787 * and add it to the system. The two steps can be called
3788 * separately, but this is the easiest and most common.
3789 * I.e. you should only call the two helpers separately if
3790 * have a clearly defined need to use and refcount the device
3791 * before it is added to the hierarchy.
3793 * For more information, see the kerneldoc for device_initialize()
3796 * NOTE: _Never_ directly free @dev after calling this function, even
3797 * if it returned an error! Always use put_device() to give up the
3798 * reference initialized in this function instead.
3800 int device_register(struct device *dev)
3802 device_initialize(dev);
3803 return device_add(dev);
3805 EXPORT_SYMBOL_GPL(device_register);
3808 * get_device - increment reference count for device.
3811 * This simply forwards the call to kobject_get(), though
3812 * we do take care to provide for the case that we get a NULL
3813 * pointer passed in.
3815 struct device *get_device(struct device *dev)
3817 return dev ? kobj_to_dev(kobject_get(&dev->kobj)) : NULL;
3819 EXPORT_SYMBOL_GPL(get_device);
3822 * put_device - decrement reference count.
3823 * @dev: device in question.
3825 void put_device(struct device *dev)
3827 /* might_sleep(); */
3829 kobject_put(&dev->kobj);
3831 EXPORT_SYMBOL_GPL(put_device);
3833 bool kill_device(struct device *dev)
3836 * Require the device lock and set the "dead" flag to guarantee that
3837 * the update behavior is consistent with the other bitfields near
3838 * it and that we cannot have an asynchronous probe routine trying
3839 * to run while we are tearing out the bus/class/sysfs from
3840 * underneath the device.
3842 device_lock_assert(dev);
3846 dev->p->dead = true;
3849 EXPORT_SYMBOL_GPL(kill_device);
3852 * device_del - delete device from system.
3855 * This is the first part of the device unregistration
3856 * sequence. This removes the device from the lists we control
3857 * from here, has it removed from the other driver model
3858 * subsystems it was added to in device_add(), and removes it
3859 * from the kobject hierarchy.
3861 * NOTE: this should be called manually _iff_ device_add() was
3862 * also called manually.
3864 void device_del(struct device *dev)
3866 struct subsys_private *sp;
3867 struct device *parent = dev->parent;
3868 struct kobject *glue_dir = NULL;
3869 struct class_interface *class_intf;
3870 unsigned int noio_flag;
3876 if (dev->fwnode && dev->fwnode->dev == dev)
3877 dev->fwnode->dev = NULL;
3879 /* Notify clients of device removal. This call must come
3880 * before dpm_sysfs_remove().
3882 noio_flag = memalloc_noio_save();
3883 bus_notify(dev, BUS_NOTIFY_DEL_DEVICE);
3885 dpm_sysfs_remove(dev);
3887 klist_del(&dev->p->knode_parent);
3888 if (MAJOR(dev->devt)) {
3889 devtmpfs_delete_node(dev);
3890 device_remove_sys_dev_entry(dev);
3891 device_remove_file(dev, &dev_attr_dev);
3894 sp = class_to_subsys(dev->class);
3896 device_remove_class_symlinks(dev);
3898 mutex_lock(&sp->mutex);
3899 /* notify any interfaces that the device is now gone */
3900 list_for_each_entry(class_intf, &sp->interfaces, node)
3901 if (class_intf->remove_dev)
3902 class_intf->remove_dev(dev);
3903 /* remove the device from the class list */
3904 klist_del(&dev->p->knode_class);
3905 mutex_unlock(&sp->mutex);
3908 device_remove_file(dev, &dev_attr_uevent);
3909 device_remove_attrs(dev);
3910 bus_remove_device(dev);
3911 device_pm_remove(dev);
3912 driver_deferred_probe_del(dev);
3913 device_platform_notify_remove(dev);
3914 device_links_purge(dev);
3917 * If a device does not have a driver attached, we need to clean
3918 * up any managed resources. We do this in device_release(), but
3919 * it's never called (and we leak the device) if a managed
3920 * resource holds a reference to the device. So release all
3921 * managed resources here, like we do in driver_detach(). We
3922 * still need to do so again in device_release() in case someone
3923 * adds a new resource after this point, though.
3925 devres_release_all(dev);
3927 bus_notify(dev, BUS_NOTIFY_REMOVED_DEVICE);
3928 kobject_uevent(&dev->kobj, KOBJ_REMOVE);
3929 glue_dir = get_glue_dir(dev);
3930 kobject_del(&dev->kobj);
3931 cleanup_glue_dir(dev, glue_dir);
3932 memalloc_noio_restore(noio_flag);
3935 EXPORT_SYMBOL_GPL(device_del);
3938 * device_unregister - unregister device from system.
3939 * @dev: device going away.
3941 * We do this in two parts, like we do device_register(). First,
3942 * we remove it from all the subsystems with device_del(), then
3943 * we decrement the reference count via put_device(). If that
3944 * is the final reference count, the device will be cleaned up
3945 * via device_release() above. Otherwise, the structure will
3946 * stick around until the final reference to the device is dropped.
3948 void device_unregister(struct device *dev)
3950 pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
3954 EXPORT_SYMBOL_GPL(device_unregister);
3956 static struct device *prev_device(struct klist_iter *i)
3958 struct klist_node *n = klist_prev(i);
3959 struct device *dev = NULL;
3960 struct device_private *p;
3963 p = to_device_private_parent(n);
3969 static struct device *next_device(struct klist_iter *i)
3971 struct klist_node *n = klist_next(i);
3972 struct device *dev = NULL;
3973 struct device_private *p;
3976 p = to_device_private_parent(n);
3983 * device_get_devnode - path of device node file
3985 * @mode: returned file access mode
3986 * @uid: returned file owner
3987 * @gid: returned file group
3988 * @tmp: possibly allocated string
3990 * Return the relative path of a possible device node.
3991 * Non-default names may need to allocate a memory to compose
3992 * a name. This memory is returned in tmp and needs to be
3993 * freed by the caller.
3995 const char *device_get_devnode(const struct device *dev,
3996 umode_t *mode, kuid_t *uid, kgid_t *gid,
4003 /* the device type may provide a specific name */
4004 if (dev->type && dev->type->devnode)
4005 *tmp = dev->type->devnode(dev, mode, uid, gid);
4009 /* the class may provide a specific name */
4010 if (dev->class && dev->class->devnode)
4011 *tmp = dev->class->devnode(dev, mode);
4015 /* return name without allocation, tmp == NULL */
4016 if (strchr(dev_name(dev), '!') == NULL)
4017 return dev_name(dev);
4019 /* replace '!' in the name with '/' */
4020 s = kstrdup_and_replace(dev_name(dev), '!', '/', GFP_KERNEL);
4027 * device_for_each_child - device child iterator.
4028 * @parent: parent struct device.
4029 * @fn: function to be called for each device.
4030 * @data: data for the callback.
4032 * Iterate over @parent's child devices, and call @fn for each,
4035 * We check the return of @fn each time. If it returns anything
4036 * other than 0, we break out and return that value.
4038 int device_for_each_child(struct device *parent, void *data,
4039 int (*fn)(struct device *dev, void *data))
4041 struct klist_iter i;
4042 struct device *child;
4048 klist_iter_init(&parent->p->klist_children, &i);
4049 while (!error && (child = next_device(&i)))
4050 error = fn(child, data);
4051 klist_iter_exit(&i);
4054 EXPORT_SYMBOL_GPL(device_for_each_child);
4057 * device_for_each_child_reverse - device child iterator in reversed order.
4058 * @parent: parent struct device.
4059 * @fn: function to be called for each device.
4060 * @data: data for the callback.
4062 * Iterate over @parent's child devices, and call @fn for each,
4065 * We check the return of @fn each time. If it returns anything
4066 * other than 0, we break out and return that value.
4068 int device_for_each_child_reverse(struct device *parent, void *data,
4069 int (*fn)(struct device *dev, void *data))
4071 struct klist_iter i;
4072 struct device *child;
4078 klist_iter_init(&parent->p->klist_children, &i);
4079 while ((child = prev_device(&i)) && !error)
4080 error = fn(child, data);
4081 klist_iter_exit(&i);
4084 EXPORT_SYMBOL_GPL(device_for_each_child_reverse);
4087 * device_find_child - device iterator for locating a particular device.
4088 * @parent: parent struct device
4089 * @match: Callback function to check device
4090 * @data: Data to pass to match function
4092 * This is similar to the device_for_each_child() function above, but it
4093 * returns a reference to a device that is 'found' for later use, as
4094 * determined by the @match callback.
4096 * The callback should return 0 if the device doesn't match and non-zero
4097 * if it does. If the callback returns non-zero and a reference to the
4098 * current device can be obtained, this function will return to the caller
4099 * and not iterate over any more devices.
4101 * NOTE: you will need to drop the reference with put_device() after use.
4103 struct device *device_find_child(struct device *parent, void *data,
4104 int (*match)(struct device *dev, void *data))
4106 struct klist_iter i;
4107 struct device *child;
4112 klist_iter_init(&parent->p->klist_children, &i);
4113 while ((child = next_device(&i)))
4114 if (match(child, data) && get_device(child))
4116 klist_iter_exit(&i);
4119 EXPORT_SYMBOL_GPL(device_find_child);
4122 * device_find_child_by_name - device iterator for locating a child device.
4123 * @parent: parent struct device
4124 * @name: name of the child device
4126 * This is similar to the device_find_child() function above, but it
4127 * returns a reference to a device that has the name @name.
4129 * NOTE: you will need to drop the reference with put_device() after use.
4131 struct device *device_find_child_by_name(struct device *parent,
4134 struct klist_iter i;
4135 struct device *child;
4140 klist_iter_init(&parent->p->klist_children, &i);
4141 while ((child = next_device(&i)))
4142 if (sysfs_streq(dev_name(child), name) && get_device(child))
4144 klist_iter_exit(&i);
4147 EXPORT_SYMBOL_GPL(device_find_child_by_name);
4149 static int match_any(struct device *dev, void *unused)
4155 * device_find_any_child - device iterator for locating a child device, if any.
4156 * @parent: parent struct device
4158 * This is similar to the device_find_child() function above, but it
4159 * returns a reference to a child device, if any.
4161 * NOTE: you will need to drop the reference with put_device() after use.
4163 struct device *device_find_any_child(struct device *parent)
4165 return device_find_child(parent, NULL, match_any);
4167 EXPORT_SYMBOL_GPL(device_find_any_child);
4169 int __init devices_init(void)
4171 devices_kset = kset_create_and_add("devices", &device_uevent_ops, NULL);
4174 dev_kobj = kobject_create_and_add("dev", NULL);
4177 sysfs_dev_block_kobj = kobject_create_and_add("block", dev_kobj);
4178 if (!sysfs_dev_block_kobj)
4179 goto block_kobj_err;
4180 sysfs_dev_char_kobj = kobject_create_and_add("char", dev_kobj);
4181 if (!sysfs_dev_char_kobj)
4183 device_link_wq = alloc_workqueue("device_link_wq", 0, 0);
4184 if (!device_link_wq)
4190 kobject_put(sysfs_dev_char_kobj);
4192 kobject_put(sysfs_dev_block_kobj);
4194 kobject_put(dev_kobj);
4196 kset_unregister(devices_kset);
4200 static int device_check_offline(struct device *dev, void *not_used)
4204 ret = device_for_each_child(dev, NULL, device_check_offline);
4208 return device_supports_offline(dev) && !dev->offline ? -EBUSY : 0;
4212 * device_offline - Prepare the device for hot-removal.
4213 * @dev: Device to be put offline.
4215 * Execute the device bus type's .offline() callback, if present, to prepare
4216 * the device for a subsequent hot-removal. If that succeeds, the device must
4217 * not be used until either it is removed or its bus type's .online() callback
4220 * Call under device_hotplug_lock.
4222 int device_offline(struct device *dev)
4226 if (dev->offline_disabled)
4229 ret = device_for_each_child(dev, NULL, device_check_offline);
4234 if (device_supports_offline(dev)) {
4238 ret = dev->bus->offline(dev);
4240 kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
4241 dev->offline = true;
4251 * device_online - Put the device back online after successful device_offline().
4252 * @dev: Device to be put back online.
4254 * If device_offline() has been successfully executed for @dev, but the device
4255 * has not been removed subsequently, execute its bus type's .online() callback
4256 * to indicate that the device can be used again.
4258 * Call under device_hotplug_lock.
4260 int device_online(struct device *dev)
4265 if (device_supports_offline(dev)) {
4267 ret = dev->bus->online(dev);
4269 kobject_uevent(&dev->kobj, KOBJ_ONLINE);
4270 dev->offline = false;
4281 struct root_device {
4283 struct module *owner;
4286 static inline struct root_device *to_root_device(struct device *d)
4288 return container_of(d, struct root_device, dev);
4291 static void root_device_release(struct device *dev)
4293 kfree(to_root_device(dev));
4297 * __root_device_register - allocate and register a root device
4298 * @name: root device name
4299 * @owner: owner module of the root device, usually THIS_MODULE
4301 * This function allocates a root device and registers it
4302 * using device_register(). In order to free the returned
4303 * device, use root_device_unregister().
4305 * Root devices are dummy devices which allow other devices
4306 * to be grouped under /sys/devices. Use this function to
4307 * allocate a root device and then use it as the parent of
4308 * any device which should appear under /sys/devices/{name}
4310 * The /sys/devices/{name} directory will also contain a
4311 * 'module' symlink which points to the @owner directory
4314 * Returns &struct device pointer on success, or ERR_PTR() on error.
4316 * Note: You probably want to use root_device_register().
4318 struct device *__root_device_register(const char *name, struct module *owner)
4320 struct root_device *root;
4323 root = kzalloc(sizeof(struct root_device), GFP_KERNEL);
4325 return ERR_PTR(err);
4327 err = dev_set_name(&root->dev, "%s", name);
4330 return ERR_PTR(err);
4333 root->dev.release = root_device_release;
4335 err = device_register(&root->dev);
4337 put_device(&root->dev);
4338 return ERR_PTR(err);
4341 #ifdef CONFIG_MODULES /* gotta find a "cleaner" way to do this */
4343 struct module_kobject *mk = &owner->mkobj;
4345 err = sysfs_create_link(&root->dev.kobj, &mk->kobj, "module");
4347 device_unregister(&root->dev);
4348 return ERR_PTR(err);
4350 root->owner = owner;
4356 EXPORT_SYMBOL_GPL(__root_device_register);
4359 * root_device_unregister - unregister and free a root device
4360 * @dev: device going away
4362 * This function unregisters and cleans up a device that was created by
4363 * root_device_register().
4365 void root_device_unregister(struct device *dev)
4367 struct root_device *root = to_root_device(dev);
4370 sysfs_remove_link(&root->dev.kobj, "module");
4372 device_unregister(dev);
4374 EXPORT_SYMBOL_GPL(root_device_unregister);
4377 static void device_create_release(struct device *dev)
4379 pr_debug("device: '%s': %s\n", dev_name(dev), __func__);
4383 static __printf(6, 0) struct device *
4384 device_create_groups_vargs(const struct class *class, struct device *parent,
4385 dev_t devt, void *drvdata,
4386 const struct attribute_group **groups,
4387 const char *fmt, va_list args)
4389 struct device *dev = NULL;
4390 int retval = -ENODEV;
4392 if (IS_ERR_OR_NULL(class))
4395 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
4401 device_initialize(dev);
4404 dev->parent = parent;
4405 dev->groups = groups;
4406 dev->release = device_create_release;
4407 dev_set_drvdata(dev, drvdata);
4409 retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
4413 retval = device_add(dev);
4421 return ERR_PTR(retval);
4425 * device_create - creates a device and registers it with sysfs
4426 * @class: pointer to the struct class that this device should be registered to
4427 * @parent: pointer to the parent struct device of this new device, if any
4428 * @devt: the dev_t for the char device to be added
4429 * @drvdata: the data to be added to the device for callbacks
4430 * @fmt: string for the device's name
4432 * This function can be used by char device classes. A struct device
4433 * will be created in sysfs, registered to the specified class.
4435 * A "dev" file will be created, showing the dev_t for the device, if
4436 * the dev_t is not 0,0.
4437 * If a pointer to a parent struct device is passed in, the newly created
4438 * struct device will be a child of that device in sysfs.
4439 * The pointer to the struct device will be returned from the call.
4440 * Any further sysfs files that might be required can be created using this
4443 * Returns &struct device pointer on success, or ERR_PTR() on error.
4445 struct device *device_create(const struct class *class, struct device *parent,
4446 dev_t devt, void *drvdata, const char *fmt, ...)
4451 va_start(vargs, fmt);
4452 dev = device_create_groups_vargs(class, parent, devt, drvdata, NULL,
4457 EXPORT_SYMBOL_GPL(device_create);
4460 * device_create_with_groups - creates a device and registers it with sysfs
4461 * @class: pointer to the struct class that this device should be registered to
4462 * @parent: pointer to the parent struct device of this new device, if any
4463 * @devt: the dev_t for the char device to be added
4464 * @drvdata: the data to be added to the device for callbacks
4465 * @groups: NULL-terminated list of attribute groups to be created
4466 * @fmt: string for the device's name
4468 * This function can be used by char device classes. A struct device
4469 * will be created in sysfs, registered to the specified class.
4470 * Additional attributes specified in the groups parameter will also
4471 * be created automatically.
4473 * A "dev" file will be created, showing the dev_t for the device, if
4474 * the dev_t is not 0,0.
4475 * If a pointer to a parent struct device is passed in, the newly created
4476 * struct device will be a child of that device in sysfs.
4477 * The pointer to the struct device will be returned from the call.
4478 * Any further sysfs files that might be required can be created using this
4481 * Returns &struct device pointer on success, or ERR_PTR() on error.
4483 struct device *device_create_with_groups(const struct class *class,
4484 struct device *parent, dev_t devt,
4486 const struct attribute_group **groups,
4487 const char *fmt, ...)
4492 va_start(vargs, fmt);
4493 dev = device_create_groups_vargs(class, parent, devt, drvdata, groups,
4498 EXPORT_SYMBOL_GPL(device_create_with_groups);
4501 * device_destroy - removes a device that was created with device_create()
4502 * @class: pointer to the struct class that this device was registered with
4503 * @devt: the dev_t of the device that was previously registered
4505 * This call unregisters and cleans up a device that was created with a
4506 * call to device_create().
4508 void device_destroy(const struct class *class, dev_t devt)
4512 dev = class_find_device_by_devt(class, devt);
4515 device_unregister(dev);
4518 EXPORT_SYMBOL_GPL(device_destroy);
4521 * device_rename - renames a device
4522 * @dev: the pointer to the struct device to be renamed
4523 * @new_name: the new name of the device
4525 * It is the responsibility of the caller to provide mutual
4526 * exclusion between two different calls of device_rename
4527 * on the same device to ensure that new_name is valid and
4528 * won't conflict with other devices.
4530 * Note: given that some subsystems (networking and infiniband) use this
4531 * function, with no immediate plans for this to change, we cannot assume or
4532 * require that this function not be called at all.
4534 * However, if you're writing new code, do not call this function. The following
4535 * text from Kay Sievers offers some insight:
4537 * Renaming devices is racy at many levels, symlinks and other stuff are not
4538 * replaced atomically, and you get a "move" uevent, but it's not easy to
4539 * connect the event to the old and new device. Device nodes are not renamed at
4540 * all, there isn't even support for that in the kernel now.
4542 * In the meantime, during renaming, your target name might be taken by another
4543 * driver, creating conflicts. Or the old name is taken directly after you
4544 * renamed it -- then you get events for the same DEVPATH, before you even see
4545 * the "move" event. It's just a mess, and nothing new should ever rely on
4546 * kernel device renaming. Besides that, it's not even implemented now for
4547 * other things than (driver-core wise very simple) network devices.
4549 * Make up a "real" name in the driver before you register anything, or add
4550 * some other attributes for userspace to find the device, or use udev to add
4551 * symlinks -- but never rename kernel devices later, it's a complete mess. We
4552 * don't even want to get into that and try to implement the missing pieces in
4553 * the core. We really have other pieces to fix in the driver core mess. :)
4555 int device_rename(struct device *dev, const char *new_name)
4557 struct kobject *kobj = &dev->kobj;
4558 char *old_device_name = NULL;
4561 dev = get_device(dev);
4565 dev_dbg(dev, "renaming to %s\n", new_name);
4567 old_device_name = kstrdup(dev_name(dev), GFP_KERNEL);
4568 if (!old_device_name) {
4574 struct subsys_private *sp = class_to_subsys(dev->class);
4581 error = sysfs_rename_link_ns(&sp->subsys.kobj, kobj, old_device_name,
4582 new_name, kobject_namespace(kobj));
4588 error = kobject_rename(kobj, new_name);
4595 kfree(old_device_name);
4599 EXPORT_SYMBOL_GPL(device_rename);
4601 static int device_move_class_links(struct device *dev,
4602 struct device *old_parent,
4603 struct device *new_parent)
4608 sysfs_remove_link(&dev->kobj, "device");
4610 error = sysfs_create_link(&dev->kobj, &new_parent->kobj,
4616 * device_move - moves a device to a new parent
4617 * @dev: the pointer to the struct device to be moved
4618 * @new_parent: the new parent of the device (can be NULL)
4619 * @dpm_order: how to reorder the dpm_list
4621 int device_move(struct device *dev, struct device *new_parent,
4622 enum dpm_order dpm_order)
4625 struct device *old_parent;
4626 struct kobject *new_parent_kobj;
4628 dev = get_device(dev);
4633 new_parent = get_device(new_parent);
4634 new_parent_kobj = get_device_parent(dev, new_parent);
4635 if (IS_ERR(new_parent_kobj)) {
4636 error = PTR_ERR(new_parent_kobj);
4637 put_device(new_parent);
4641 pr_debug("device: '%s': %s: moving to '%s'\n", dev_name(dev),
4642 __func__, new_parent ? dev_name(new_parent) : "<NULL>");
4643 error = kobject_move(&dev->kobj, new_parent_kobj);
4645 cleanup_glue_dir(dev, new_parent_kobj);
4646 put_device(new_parent);
4649 old_parent = dev->parent;
4650 dev->parent = new_parent;
4652 klist_remove(&dev->p->knode_parent);
4654 klist_add_tail(&dev->p->knode_parent,
4655 &new_parent->p->klist_children);
4656 set_dev_node(dev, dev_to_node(new_parent));
4660 error = device_move_class_links(dev, old_parent, new_parent);
4662 /* We ignore errors on cleanup since we're hosed anyway... */
4663 device_move_class_links(dev, new_parent, old_parent);
4664 if (!kobject_move(&dev->kobj, &old_parent->kobj)) {
4666 klist_remove(&dev->p->knode_parent);
4667 dev->parent = old_parent;
4669 klist_add_tail(&dev->p->knode_parent,
4670 &old_parent->p->klist_children);
4671 set_dev_node(dev, dev_to_node(old_parent));
4674 cleanup_glue_dir(dev, new_parent_kobj);
4675 put_device(new_parent);
4679 switch (dpm_order) {
4680 case DPM_ORDER_NONE:
4682 case DPM_ORDER_DEV_AFTER_PARENT:
4683 device_pm_move_after(dev, new_parent);
4684 devices_kset_move_after(dev, new_parent);
4686 case DPM_ORDER_PARENT_BEFORE_DEV:
4687 device_pm_move_before(new_parent, dev);
4688 devices_kset_move_before(new_parent, dev);
4690 case DPM_ORDER_DEV_LAST:
4691 device_pm_move_last(dev);
4692 devices_kset_move_last(dev);
4696 put_device(old_parent);
4702 EXPORT_SYMBOL_GPL(device_move);
4704 static int device_attrs_change_owner(struct device *dev, kuid_t kuid,
4707 struct kobject *kobj = &dev->kobj;
4708 const struct class *class = dev->class;
4709 const struct device_type *type = dev->type;
4714 * Change the device groups of the device class for @dev to
4717 error = sysfs_groups_change_owner(kobj, class->dev_groups, kuid,
4725 * Change the device groups of the device type for @dev to
4728 error = sysfs_groups_change_owner(kobj, type->groups, kuid,
4734 /* Change the device groups of @dev to @kuid/@kgid. */
4735 error = sysfs_groups_change_owner(kobj, dev->groups, kuid, kgid);
4739 if (device_supports_offline(dev) && !dev->offline_disabled) {
4740 /* Change online device attributes of @dev to @kuid/@kgid. */
4741 error = sysfs_file_change_owner(kobj, dev_attr_online.attr.name,
4751 * device_change_owner - change the owner of an existing device.
4753 * @kuid: new owner's kuid
4754 * @kgid: new owner's kgid
4756 * This changes the owner of @dev and its corresponding sysfs entries to
4757 * @kuid/@kgid. This function closely mirrors how @dev was added via driver
4760 * Returns 0 on success or error code on failure.
4762 int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
4765 struct kobject *kobj = &dev->kobj;
4766 struct subsys_private *sp;
4768 dev = get_device(dev);
4773 * Change the kobject and the default attributes and groups of the
4774 * ktype associated with it to @kuid/@kgid.
4776 error = sysfs_change_owner(kobj, kuid, kgid);
4781 * Change the uevent file for @dev to the new owner. The uevent file
4782 * was created in a separate step when @dev got added and we mirror
4785 error = sysfs_file_change_owner(kobj, dev_attr_uevent.attr.name, kuid,
4791 * Change the device groups, the device groups associated with the
4792 * device class, and the groups associated with the device type of @dev
4795 error = device_attrs_change_owner(dev, kuid, kgid);
4799 error = dpm_sysfs_change_owner(dev, kuid, kgid);
4804 * Change the owner of the symlink located in the class directory of
4805 * the device class associated with @dev which points to the actual
4806 * directory entry for @dev to @kuid/@kgid. This ensures that the
4807 * symlink shows the same permissions as its target.
4809 sp = class_to_subsys(dev->class);
4814 error = sysfs_link_change_owner(&sp->subsys.kobj, &dev->kobj, dev_name(dev), kuid, kgid);
4821 EXPORT_SYMBOL_GPL(device_change_owner);
4824 * device_shutdown - call ->shutdown() on each device to shutdown.
4826 void device_shutdown(void)
4828 struct device *dev, *parent;
4830 wait_for_device_probe();
4831 device_block_probing();
4835 spin_lock(&devices_kset->list_lock);
4837 * Walk the devices list backward, shutting down each in turn.
4838 * Beware that device unplug events may also start pulling
4839 * devices offline, even as the system is shutting down.
4841 while (!list_empty(&devices_kset->list)) {
4842 dev = list_entry(devices_kset->list.prev, struct device,
4846 * hold reference count of device's parent to
4847 * prevent it from being freed because parent's
4848 * lock is to be held
4850 parent = get_device(dev->parent);
4853 * Make sure the device is off the kset list, in the
4854 * event that dev->*->shutdown() doesn't remove it.
4856 list_del_init(&dev->kobj.entry);
4857 spin_unlock(&devices_kset->list_lock);
4859 /* hold lock to avoid race with probe/release */
4861 device_lock(parent);
4864 /* Don't allow any more runtime suspends */
4865 pm_runtime_get_noresume(dev);
4866 pm_runtime_barrier(dev);
4868 if (dev->class && dev->class->shutdown_pre) {
4870 dev_info(dev, "shutdown_pre\n");
4871 dev->class->shutdown_pre(dev);
4873 if (dev->bus && dev->bus->shutdown) {
4875 dev_info(dev, "shutdown\n");
4876 dev->bus->shutdown(dev);
4877 } else if (dev->driver && dev->driver->shutdown) {
4879 dev_info(dev, "shutdown\n");
4880 dev->driver->shutdown(dev);
4885 device_unlock(parent);
4890 spin_lock(&devices_kset->list_lock);
4892 spin_unlock(&devices_kset->list_lock);
4896 * Device logging functions
4899 #ifdef CONFIG_PRINTK
4901 set_dev_info(const struct device *dev, struct dev_printk_info *dev_info)
4905 memset(dev_info, 0, sizeof(*dev_info));
4908 subsys = dev->class->name;
4910 subsys = dev->bus->name;
4914 strscpy(dev_info->subsystem, subsys, sizeof(dev_info->subsystem));
4917 * Add device identifier DEVICE=:
4921 * +sound:card0 subsystem:devname
4923 if (MAJOR(dev->devt)) {
4926 if (strcmp(subsys, "block") == 0)
4931 snprintf(dev_info->device, sizeof(dev_info->device),
4932 "%c%u:%u", c, MAJOR(dev->devt), MINOR(dev->devt));
4933 } else if (strcmp(subsys, "net") == 0) {
4934 struct net_device *net = to_net_dev(dev);
4936 snprintf(dev_info->device, sizeof(dev_info->device),
4937 "n%u", net->ifindex);
4939 snprintf(dev_info->device, sizeof(dev_info->device),
4940 "+%s:%s", subsys, dev_name(dev));
4944 int dev_vprintk_emit(int level, const struct device *dev,
4945 const char *fmt, va_list args)
4947 struct dev_printk_info dev_info;
4949 set_dev_info(dev, &dev_info);
4951 return vprintk_emit(0, level, &dev_info, fmt, args);
4953 EXPORT_SYMBOL(dev_vprintk_emit);
4955 int dev_printk_emit(int level, const struct device *dev, const char *fmt, ...)
4960 va_start(args, fmt);
4962 r = dev_vprintk_emit(level, dev, fmt, args);
4968 EXPORT_SYMBOL(dev_printk_emit);
4970 static void __dev_printk(const char *level, const struct device *dev,
4971 struct va_format *vaf)
4974 dev_printk_emit(level[1] - '0', dev, "%s %s: %pV",
4975 dev_driver_string(dev), dev_name(dev), vaf);
4977 printk("%s(NULL device *): %pV", level, vaf);
4980 void _dev_printk(const char *level, const struct device *dev,
4981 const char *fmt, ...)
4983 struct va_format vaf;
4986 va_start(args, fmt);
4991 __dev_printk(level, dev, &vaf);
4995 EXPORT_SYMBOL(_dev_printk);
4997 #define define_dev_printk_level(func, kern_level) \
4998 void func(const struct device *dev, const char *fmt, ...) \
5000 struct va_format vaf; \
5003 va_start(args, fmt); \
5008 __dev_printk(kern_level, dev, &vaf); \
5012 EXPORT_SYMBOL(func);
5014 define_dev_printk_level(_dev_emerg, KERN_EMERG);
5015 define_dev_printk_level(_dev_alert, KERN_ALERT);
5016 define_dev_printk_level(_dev_crit, KERN_CRIT);
5017 define_dev_printk_level(_dev_err, KERN_ERR);
5018 define_dev_printk_level(_dev_warn, KERN_WARNING);
5019 define_dev_printk_level(_dev_notice, KERN_NOTICE);
5020 define_dev_printk_level(_dev_info, KERN_INFO);
5025 * dev_err_probe - probe error check and log helper
5026 * @dev: the pointer to the struct device
5027 * @err: error value to test
5028 * @fmt: printf-style format string
5029 * @...: arguments as specified in the format string
5031 * This helper implements common pattern present in probe functions for error
5032 * checking: print debug or error message depending if the error value is
5033 * -EPROBE_DEFER and propagate error upwards.
5034 * In case of -EPROBE_DEFER it sets also defer probe reason, which can be
5035 * checked later by reading devices_deferred debugfs attribute.
5036 * It replaces code sequence::
5038 * if (err != -EPROBE_DEFER)
5039 * dev_err(dev, ...);
5041 * dev_dbg(dev, ...);
5046 * return dev_err_probe(dev, err, ...);
5048 * Using this helper in your probe function is totally fine even if @err is
5049 * known to never be -EPROBE_DEFER.
5050 * The benefit compared to a normal dev_err() is the standardized format
5051 * of the error code, it being emitted symbolically (i.e. you get "EAGAIN"
5052 * instead of "-35") and the fact that the error code is returned which allows
5053 * more compact error paths.
5057 int dev_err_probe(const struct device *dev, int err, const char *fmt, ...)
5059 struct va_format vaf;
5062 va_start(args, fmt);
5066 if (err != -EPROBE_DEFER) {
5067 dev_err(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
5069 device_set_deferred_probe_reason(dev, &vaf);
5070 dev_dbg(dev, "error %pe: %pV", ERR_PTR(err), &vaf);
5077 EXPORT_SYMBOL_GPL(dev_err_probe);
5079 static inline bool fwnode_is_primary(struct fwnode_handle *fwnode)
5081 return fwnode && !IS_ERR(fwnode->secondary);
5085 * set_primary_fwnode - Change the primary firmware node of a given device.
5086 * @dev: Device to handle.
5087 * @fwnode: New primary firmware node of the device.
5089 * Set the device's firmware node pointer to @fwnode, but if a secondary
5090 * firmware node of the device is present, preserve it.
5092 * Valid fwnode cases are:
5093 * - primary --> secondary --> -ENODEV
5094 * - primary --> NULL
5095 * - secondary --> -ENODEV
5098 void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
5100 struct device *parent = dev->parent;
5101 struct fwnode_handle *fn = dev->fwnode;
5104 if (fwnode_is_primary(fn))
5108 WARN_ON(fwnode->secondary);
5109 fwnode->secondary = fn;
5111 dev->fwnode = fwnode;
5113 if (fwnode_is_primary(fn)) {
5114 dev->fwnode = fn->secondary;
5116 /* Skip nullifying fn->secondary if the primary is shared */
5117 if (parent && fn == parent->fwnode)
5120 /* Set fn->secondary = NULL, so fn remains the primary fwnode */
5121 fn->secondary = NULL;
5127 EXPORT_SYMBOL_GPL(set_primary_fwnode);
5130 * set_secondary_fwnode - Change the secondary firmware node of a given device.
5131 * @dev: Device to handle.
5132 * @fwnode: New secondary firmware node of the device.
5134 * If a primary firmware node of the device is present, set its secondary
5135 * pointer to @fwnode. Otherwise, set the device's firmware node pointer to
5138 void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
5141 fwnode->secondary = ERR_PTR(-ENODEV);
5143 if (fwnode_is_primary(dev->fwnode))
5144 dev->fwnode->secondary = fwnode;
5146 dev->fwnode = fwnode;
5148 EXPORT_SYMBOL_GPL(set_secondary_fwnode);
5151 * device_set_of_node_from_dev - reuse device-tree node of another device
5152 * @dev: device whose device-tree node is being set
5153 * @dev2: device whose device-tree node is being reused
5155 * Takes another reference to the new device-tree node after first dropping
5156 * any reference held to the old node.
5158 void device_set_of_node_from_dev(struct device *dev, const struct device *dev2)
5160 of_node_put(dev->of_node);
5161 dev->of_node = of_node_get(dev2->of_node);
5162 dev->of_node_reused = true;
5164 EXPORT_SYMBOL_GPL(device_set_of_node_from_dev);
5166 void device_set_node(struct device *dev, struct fwnode_handle *fwnode)
5168 dev->fwnode = fwnode;
5169 dev->of_node = to_of_node(fwnode);
5171 EXPORT_SYMBOL_GPL(device_set_node);
5173 int device_match_name(struct device *dev, const void *name)
5175 return sysfs_streq(dev_name(dev), name);
5177 EXPORT_SYMBOL_GPL(device_match_name);
5179 int device_match_of_node(struct device *dev, const void *np)
5181 return dev->of_node == np;
5183 EXPORT_SYMBOL_GPL(device_match_of_node);
5185 int device_match_fwnode(struct device *dev, const void *fwnode)
5187 return dev_fwnode(dev) == fwnode;
5189 EXPORT_SYMBOL_GPL(device_match_fwnode);
5191 int device_match_devt(struct device *dev, const void *pdevt)
5193 return dev->devt == *(dev_t *)pdevt;
5195 EXPORT_SYMBOL_GPL(device_match_devt);
5197 int device_match_acpi_dev(struct device *dev, const void *adev)
5199 return ACPI_COMPANION(dev) == adev;
5201 EXPORT_SYMBOL(device_match_acpi_dev);
5203 int device_match_acpi_handle(struct device *dev, const void *handle)
5205 return ACPI_HANDLE(dev) == handle;
5207 EXPORT_SYMBOL(device_match_acpi_handle);
5209 int device_match_any(struct device *dev, const void *unused)
5213 EXPORT_SYMBOL_GPL(device_match_any);