1 // SPDX-License-Identifier: GPL-2.0
3 * drivers/base/dd.c - The core device/driver interactions.
5 * This file contains the (sometimes tricky) code that controls the
6 * interactions between devices and drivers, which primarily includes
7 * driver binding and unbinding.
9 * All of this code used to exist in drivers/base/bus.c, but was
10 * relocated to here in the name of compartmentalization (since it wasn't
11 * strictly code just for the 'struct bus_type'.
13 * Copyright (c) 2002-5 Patrick Mochel
14 * Copyright (c) 2002-3 Open Source Development Labs
15 * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
16 * Copyright (c) 2007-2009 Novell Inc.
19 #include <linux/debugfs.h>
20 #include <linux/device.h>
21 #include <linux/delay.h>
22 #include <linux/dma-map-ops.h>
23 #include <linux/init.h>
24 #include <linux/module.h>
25 #include <linux/kthread.h>
26 #include <linux/wait.h>
27 #include <linux/async.h>
28 #include <linux/pm_runtime.h>
29 #include <linux/pinctrl/devinfo.h>
30 #include <linux/slab.h>
33 #include "power/power.h"
36 * Deferred Probe infrastructure.
38 * Sometimes driver probe order matters, but the kernel doesn't always have
39 * dependency information which means some drivers will get probed before a
40 * resource it depends on is available. For example, an SDHCI driver may
41 * first need a GPIO line from an i2c GPIO controller before it can be
42 * initialized. If a required resource is not available yet, a driver can
43 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
45 * Deferred probe maintains two lists of devices, a pending list and an active
46 * list. A driver returning -EPROBE_DEFER causes the device to be added to the
47 * pending list. A successful driver probe will trigger moving all devices
48 * from the pending to the active list so that the workqueue will eventually
51 * The deferred_probe_mutex must be held any time the deferred_probe_*_list
52 * of the (struct device*)->p->deferred_probe pointers are manipulated
54 static DEFINE_MUTEX(deferred_probe_mutex);
55 static LIST_HEAD(deferred_probe_pending_list);
56 static LIST_HEAD(deferred_probe_active_list);
57 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
58 static struct dentry *deferred_devices;
59 static bool initcalls_done;
61 /* Save the async probe drivers' name from kernel cmdline */
62 #define ASYNC_DRV_NAMES_MAX_LEN 256
63 static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
66 * In some cases, like suspend to RAM or hibernation, It might be reasonable
67 * to prohibit probing of devices as it could be unsafe.
68 * Once defer_all_probes is true all drivers probes will be forcibly deferred.
70 static bool defer_all_probes;
73 * deferred_probe_work_func() - Retry probing devices in the active list.
75 static void deferred_probe_work_func(struct work_struct *work)
78 struct device_private *private;
80 * This block processes every device in the deferred 'active' list.
81 * Each device is removed from the active list and passed to
82 * bus_probe_device() to re-attempt the probe. The loop continues
83 * until every device in the active list is removed and retried.
85 * Note: Once the device is removed from the list and the mutex is
86 * released, it is possible for the device get freed by another thread
87 * and cause a illegal pointer dereference. This code uses
88 * get/put_device() to ensure the device structure cannot disappear
89 * from under our feet.
91 mutex_lock(&deferred_probe_mutex);
92 while (!list_empty(&deferred_probe_active_list)) {
93 private = list_first_entry(&deferred_probe_active_list,
94 typeof(*dev->p), deferred_probe);
95 dev = private->device;
96 list_del_init(&private->deferred_probe);
100 kfree(dev->p->deferred_probe_reason);
101 dev->p->deferred_probe_reason = NULL;
104 * Drop the mutex while probing each device; the probe path may
105 * manipulate the deferred list
107 mutex_unlock(&deferred_probe_mutex);
110 * Force the device to the end of the dpm_list since
111 * the PM code assumes that the order we add things to
112 * the list is a good order for suspend but deferred
113 * probe makes that very unsafe.
115 device_pm_move_to_tail(dev);
117 dev_dbg(dev, "Retrying from deferred list\n");
118 bus_probe_device(dev);
119 mutex_lock(&deferred_probe_mutex);
123 mutex_unlock(&deferred_probe_mutex);
125 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
127 void driver_deferred_probe_add(struct device *dev)
129 mutex_lock(&deferred_probe_mutex);
130 if (list_empty(&dev->p->deferred_probe)) {
131 dev_dbg(dev, "Added to deferred list\n");
132 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
134 mutex_unlock(&deferred_probe_mutex);
137 void driver_deferred_probe_del(struct device *dev)
139 mutex_lock(&deferred_probe_mutex);
140 if (!list_empty(&dev->p->deferred_probe)) {
141 dev_dbg(dev, "Removed from deferred list\n");
142 list_del_init(&dev->p->deferred_probe);
143 kfree(dev->p->deferred_probe_reason);
144 dev->p->deferred_probe_reason = NULL;
146 mutex_unlock(&deferred_probe_mutex);
149 static bool driver_deferred_probe_enable = false;
151 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
153 * This functions moves all devices from the pending list to the active
154 * list and schedules the deferred probe workqueue to process them. It
155 * should be called anytime a driver is successfully bound to a device.
157 * Note, there is a race condition in multi-threaded probe. In the case where
158 * more than one device is probing at the same time, it is possible for one
159 * probe to complete successfully while another is about to defer. If the second
160 * depends on the first, then it will get put on the pending list after the
161 * trigger event has already occurred and will be stuck there.
163 * The atomic 'deferred_trigger_count' is used to determine if a successful
164 * trigger has occurred in the midst of probing a driver. If the trigger count
165 * changes in the midst of a probe, then deferred processing should be triggered
168 static void driver_deferred_probe_trigger(void)
170 if (!driver_deferred_probe_enable)
174 * A successful probe means that all the devices in the pending list
175 * should be triggered to be reprobed. Move all the deferred devices
176 * into the active list so they can be retried by the workqueue
178 mutex_lock(&deferred_probe_mutex);
179 atomic_inc(&deferred_trigger_count);
180 list_splice_tail_init(&deferred_probe_pending_list,
181 &deferred_probe_active_list);
182 mutex_unlock(&deferred_probe_mutex);
185 * Kick the re-probe thread. It may already be scheduled, but it is
186 * safe to kick it again.
188 schedule_work(&deferred_probe_work);
192 * device_block_probing() - Block/defer device's probes
194 * It will disable probing of devices and defer their probes instead.
196 void device_block_probing(void)
198 defer_all_probes = true;
199 /* sync with probes to avoid races. */
200 wait_for_device_probe();
204 * device_unblock_probing() - Unblock/enable device's probes
206 * It will restore normal behavior and trigger re-probing of deferred
209 void device_unblock_probing(void)
211 defer_all_probes = false;
212 driver_deferred_probe_trigger();
216 * device_set_deferred_probe_reason() - Set defer probe reason message for device
217 * @dev: the pointer to the struct device
218 * @vaf: the pointer to va_format structure with message
220 void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
222 const char *drv = dev_driver_string(dev);
224 mutex_lock(&deferred_probe_mutex);
226 kfree(dev->p->deferred_probe_reason);
227 dev->p->deferred_probe_reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
229 mutex_unlock(&deferred_probe_mutex);
233 * deferred_devs_show() - Show the devices in the deferred probe pending list.
235 static int deferred_devs_show(struct seq_file *s, void *data)
237 struct device_private *curr;
239 mutex_lock(&deferred_probe_mutex);
241 list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
242 seq_printf(s, "%s\t%s", dev_name(curr->device),
243 curr->device->p->deferred_probe_reason ?: "\n");
245 mutex_unlock(&deferred_probe_mutex);
249 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
251 int driver_deferred_probe_timeout;
252 EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
254 static int __init deferred_probe_timeout_setup(char *str)
258 if (!kstrtoint(str, 10, &timeout))
259 driver_deferred_probe_timeout = timeout;
262 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
265 * driver_deferred_probe_check_state() - Check deferred probe state
266 * @dev: device to check
269 * -ENODEV if initcalls have completed and modules are disabled.
270 * -ETIMEDOUT if the deferred probe timeout was set and has expired
271 * and modules are enabled.
272 * -EPROBE_DEFER in other cases.
274 * Drivers or subsystems can opt-in to calling this function instead of directly
275 * returning -EPROBE_DEFER.
277 int driver_deferred_probe_check_state(struct device *dev)
279 if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
280 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
284 if (!driver_deferred_probe_timeout && initcalls_done) {
285 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
289 return -EPROBE_DEFER;
292 static void deferred_probe_timeout_work_func(struct work_struct *work)
294 struct device_private *p;
296 driver_deferred_probe_timeout = 0;
297 driver_deferred_probe_trigger();
298 flush_work(&deferred_probe_work);
300 mutex_lock(&deferred_probe_mutex);
301 list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
302 dev_info(p->device, "deferred probe pending\n");
303 mutex_unlock(&deferred_probe_mutex);
305 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
308 * deferred_probe_initcall() - Enable probing of deferred devices
310 * We don't want to get in the way when the bulk of drivers are getting probed.
311 * Instead, this initcall makes sure that deferred probing is delayed until
312 * late_initcall time.
314 static int deferred_probe_initcall(void)
316 deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL,
317 NULL, &deferred_devs_fops);
319 driver_deferred_probe_enable = true;
320 driver_deferred_probe_trigger();
321 /* Sort as many dependencies as possible before exiting initcalls */
322 flush_work(&deferred_probe_work);
323 initcalls_done = true;
326 * Trigger deferred probe again, this time we won't defer anything
329 driver_deferred_probe_trigger();
330 flush_work(&deferred_probe_work);
332 if (driver_deferred_probe_timeout > 0) {
333 schedule_delayed_work(&deferred_probe_timeout_work,
334 driver_deferred_probe_timeout * HZ);
338 late_initcall(deferred_probe_initcall);
340 static void __exit deferred_probe_exit(void)
342 debugfs_remove_recursive(deferred_devices);
344 __exitcall(deferred_probe_exit);
347 * device_is_bound() - Check if device is bound to a driver
348 * @dev: device to check
350 * Returns true if passed device has already finished probing successfully
353 * This function must be called with the device lock held.
355 bool device_is_bound(struct device *dev)
357 return dev->p && klist_node_attached(&dev->p->knode_driver);
360 static void driver_bound(struct device *dev)
362 if (device_is_bound(dev)) {
363 pr_warn("%s: device %s already bound\n",
364 __func__, kobject_name(&dev->kobj));
368 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
369 __func__, dev_name(dev));
371 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
372 device_links_driver_bound(dev);
374 device_pm_check_callbacks(dev);
377 * Make sure the device is no longer in one of the deferred lists and
378 * kick off retrying all pending devices
380 driver_deferred_probe_del(dev);
381 driver_deferred_probe_trigger();
384 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
385 BUS_NOTIFY_BOUND_DRIVER, dev);
387 kobject_uevent(&dev->kobj, KOBJ_BIND);
390 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
391 const char *buf, size_t count)
394 dev->driver->coredump(dev);
399 static DEVICE_ATTR_WO(coredump);
401 static int driver_sysfs_add(struct device *dev)
406 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
407 BUS_NOTIFY_BIND_DRIVER, dev);
409 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
410 kobject_name(&dev->kobj));
414 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
419 if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
420 !device_create_file(dev, &dev_attr_coredump))
423 sysfs_remove_link(&dev->kobj, "driver");
426 sysfs_remove_link(&dev->driver->p->kobj,
427 kobject_name(&dev->kobj));
433 static void driver_sysfs_remove(struct device *dev)
435 struct device_driver *drv = dev->driver;
439 device_remove_file(dev, &dev_attr_coredump);
440 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
441 sysfs_remove_link(&dev->kobj, "driver");
446 * device_bind_driver - bind a driver to one device.
449 * Allow manual attachment of a driver to a device.
450 * Caller must have already set @dev->driver.
452 * Note that this does not modify the bus reference count.
453 * Please verify that is accounted for before calling this.
454 * (It is ok to call with no other effort from a driver's probe() method.)
456 * This function must be called with the device lock held.
458 int device_bind_driver(struct device *dev)
462 ret = driver_sysfs_add(dev);
466 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
467 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
470 EXPORT_SYMBOL_GPL(device_bind_driver);
472 static atomic_t probe_count = ATOMIC_INIT(0);
473 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
475 static void driver_deferred_probe_add_trigger(struct device *dev,
476 int local_trigger_count)
478 driver_deferred_probe_add(dev);
479 /* Did a trigger occur while probing? Need to re-trigger if yes */
480 if (local_trigger_count != atomic_read(&deferred_trigger_count))
481 driver_deferred_probe_trigger();
484 static ssize_t state_synced_show(struct device *dev,
485 struct device_attribute *attr, char *buf)
490 val = dev->state_synced;
493 return sysfs_emit(buf, "%u\n", val);
495 static DEVICE_ATTR_RO(state_synced);
497 static int really_probe(struct device *dev, struct device_driver *drv)
499 int ret = -EPROBE_DEFER;
500 int local_trigger_count = atomic_read(&deferred_trigger_count);
501 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
502 !drv->suppress_bind_attrs;
504 if (defer_all_probes) {
506 * Value of defer_all_probes can be set only by
507 * device_block_probing() which, in turn, will call
508 * wait_for_device_probe() right after that to avoid any races.
510 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
511 driver_deferred_probe_add(dev);
515 ret = device_links_check_suppliers(dev);
516 if (ret == -EPROBE_DEFER)
517 driver_deferred_probe_add_trigger(dev, local_trigger_count);
521 atomic_inc(&probe_count);
522 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
523 drv->bus->name, __func__, drv->name, dev_name(dev));
524 if (!list_empty(&dev->devres_head)) {
525 dev_crit(dev, "Resources present before probing\n");
533 /* If using pinctrl, bind pins now before probing */
534 ret = pinctrl_bind_pins(dev);
536 goto pinctrl_bind_failed;
538 if (dev->bus->dma_configure) {
539 ret = dev->bus->dma_configure(dev);
544 ret = driver_sysfs_add(dev);
546 pr_err("%s: driver_sysfs_add(%s) failed\n",
547 __func__, dev_name(dev));
551 if (dev->pm_domain && dev->pm_domain->activate) {
552 ret = dev->pm_domain->activate(dev);
557 if (dev->bus->probe) {
558 ret = dev->bus->probe(dev);
561 } else if (drv->probe) {
562 ret = drv->probe(dev);
567 ret = device_add_groups(dev, drv->dev_groups);
569 dev_err(dev, "device_add_groups() failed\n");
570 goto dev_groups_failed;
573 if (dev_has_sync_state(dev)) {
574 ret = device_create_file(dev, &dev_attr_state_synced);
576 dev_err(dev, "state_synced sysfs add failed\n");
577 goto dev_sysfs_state_synced_failed;
584 device_remove_file(dev, &dev_attr_state_synced);
585 device_remove_groups(dev, drv->dev_groups);
587 if (dev->bus->remove)
588 dev->bus->remove(dev);
589 else if (drv->remove)
592 devres_release_all(dev);
593 arch_teardown_dma_ops(dev);
594 kfree(dev->dma_range_map);
595 dev->dma_range_map = NULL;
596 driver_sysfs_remove(dev);
598 dev_set_drvdata(dev, NULL);
599 if (dev->pm_domain && dev->pm_domain->dismiss)
600 dev->pm_domain->dismiss(dev);
601 pm_runtime_reinit(dev);
606 pinctrl_init_done(dev);
608 if (dev->pm_domain && dev->pm_domain->sync)
609 dev->pm_domain->sync(dev);
613 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
614 drv->bus->name, __func__, dev_name(dev), drv->name);
617 dev_sysfs_state_synced_failed:
618 device_remove_groups(dev, drv->dev_groups);
620 if (dev->bus->remove)
621 dev->bus->remove(dev);
622 else if (drv->remove)
626 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
627 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
629 device_links_no_driver(dev);
630 devres_release_all(dev);
631 arch_teardown_dma_ops(dev);
632 kfree(dev->dma_range_map);
633 dev->dma_range_map = NULL;
634 driver_sysfs_remove(dev);
636 dev_set_drvdata(dev, NULL);
637 if (dev->pm_domain && dev->pm_domain->dismiss)
638 dev->pm_domain->dismiss(dev);
639 pm_runtime_reinit(dev);
640 dev_pm_set_driver_flags(dev, 0);
644 /* Driver requested deferred probing */
645 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
646 driver_deferred_probe_add_trigger(dev, local_trigger_count);
650 pr_debug("%s: probe of %s rejects match %d\n",
651 drv->name, dev_name(dev), ret);
654 /* driver matched but the probe failed */
655 pr_warn("%s: probe of %s failed with error %d\n",
656 drv->name, dev_name(dev), ret);
659 * Ignore errors returned by ->probe so that the next driver can try
664 atomic_dec(&probe_count);
665 wake_up_all(&probe_waitqueue);
670 * For initcall_debug, show the driver probe time.
672 static int really_probe_debug(struct device *dev, struct device_driver *drv)
674 ktime_t calltime, rettime;
677 calltime = ktime_get();
678 ret = really_probe(dev, drv);
679 rettime = ktime_get();
680 pr_debug("probe of %s returned %d after %lld usecs\n",
681 dev_name(dev), ret, ktime_us_delta(rettime, calltime));
687 * Determine if the probe sequence is finished or not.
689 * Should somehow figure out how to use a semaphore, not an atomic variable...
691 int driver_probe_done(void)
693 int local_probe_count = atomic_read(&probe_count);
695 pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
696 if (local_probe_count)
702 * wait_for_device_probe
703 * Wait for device probing to be completed.
705 void wait_for_device_probe(void)
707 /* wait for the deferred probe workqueue to finish */
708 flush_work(&deferred_probe_work);
710 /* wait for the known devices to complete their probing */
711 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
712 async_synchronize_full();
714 EXPORT_SYMBOL_GPL(wait_for_device_probe);
717 * driver_probe_device - attempt to bind device & driver together
718 * @drv: driver to bind a device to
719 * @dev: device to try to bind to the driver
721 * This function returns -ENODEV if the device is not registered,
722 * 1 if the device is bound successfully and 0 otherwise.
724 * This function must be called with @dev lock held. When called for a
725 * USB interface, @dev->parent lock must be held as well.
727 * If the device has a parent, runtime-resume the parent before driver probing.
729 int driver_probe_device(struct device_driver *drv, struct device *dev)
733 if (!device_is_registered(dev))
736 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
737 drv->bus->name, __func__, dev_name(dev), drv->name);
739 pm_runtime_get_suppliers(dev);
741 pm_runtime_get_sync(dev->parent);
743 pm_runtime_barrier(dev);
745 ret = really_probe_debug(dev, drv);
747 ret = really_probe(dev, drv);
748 pm_request_idle(dev);
751 pm_runtime_put(dev->parent);
753 pm_runtime_put_suppliers(dev);
757 static inline bool cmdline_requested_async_probing(const char *drv_name)
759 return parse_option_str(async_probe_drv_names, drv_name);
762 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
763 static int __init save_async_options(char *buf)
765 if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
766 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
768 strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
771 __setup("driver_async_probe=", save_async_options);
773 bool driver_allows_async_probing(struct device_driver *drv)
775 switch (drv->probe_type) {
776 case PROBE_PREFER_ASYNCHRONOUS:
779 case PROBE_FORCE_SYNCHRONOUS:
783 if (cmdline_requested_async_probing(drv->name))
786 if (module_requested_async_probing(drv->owner))
793 struct device_attach_data {
797 * Indicates whether we are are considering asynchronous probing or
798 * not. Only initial binding after device or driver registration
799 * (including deferral processing) may be done asynchronously, the
800 * rest is always synchronous, as we expect it is being done by
801 * request from userspace.
806 * Indicates if we are binding synchronous or asynchronous drivers.
807 * When asynchronous probing is enabled we'll execute 2 passes
808 * over drivers: first pass doing synchronous probing and second
809 * doing asynchronous probing (if synchronous did not succeed -
810 * most likely because there was no driver requiring synchronous
811 * probing - and we found asynchronous driver during first pass).
812 * The 2 passes are done because we can't shoot asynchronous
813 * probe for given device and driver from bus_for_each_drv() since
814 * driver pointer is not guaranteed to stay valid once
815 * bus_for_each_drv() iterates to the next driver on the bus.
820 * We'll set have_async to 'true' if, while scanning for matching
821 * driver, we'll encounter one that requests asynchronous probing.
826 static int __device_attach_driver(struct device_driver *drv, void *_data)
828 struct device_attach_data *data = _data;
829 struct device *dev = data->dev;
833 ret = driver_match_device(drv, dev);
837 } else if (ret == -EPROBE_DEFER) {
838 dev_dbg(dev, "Device match requests probe deferral\n");
839 driver_deferred_probe_add(dev);
841 * Device can't match with a driver right now, so don't attempt
842 * to match or bind with other drivers on the bus.
845 } else if (ret < 0) {
846 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
848 } /* ret > 0 means positive match */
850 async_allowed = driver_allows_async_probing(drv);
853 data->have_async = true;
855 if (data->check_async && async_allowed != data->want_async)
858 return driver_probe_device(drv, dev);
861 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
863 struct device *dev = _dev;
864 struct device_attach_data data = {
873 * Check if device has already been removed or claimed. This may
874 * happen with driver loading, device discovery/registration,
875 * and deferred probe processing happens all at once with
878 if (dev->p->dead || dev->driver)
882 pm_runtime_get_sync(dev->parent);
884 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
885 dev_dbg(dev, "async probe completed\n");
887 pm_request_idle(dev);
890 pm_runtime_put(dev->parent);
897 static int __device_attach(struct device *dev, bool allow_async)
905 } else if (dev->driver) {
906 if (device_is_bound(dev)) {
910 ret = device_bind_driver(dev);
918 struct device_attach_data data = {
920 .check_async = allow_async,
925 pm_runtime_get_sync(dev->parent);
927 ret = bus_for_each_drv(dev->bus, NULL, &data,
928 __device_attach_driver);
929 if (!ret && allow_async && data.have_async) {
931 * If we could not find appropriate driver
932 * synchronously and we are allowed to do
933 * async probes and there are drivers that
934 * want to probe asynchronously, we'll
937 dev_dbg(dev, "scheduling asynchronous probe\n");
941 pm_request_idle(dev);
945 pm_runtime_put(dev->parent);
950 async_schedule_dev(__device_attach_async_helper, dev);
955 * device_attach - try to attach device to a driver.
958 * Walk the list of drivers that the bus has and call
959 * driver_probe_device() for each pair. If a compatible
960 * pair is found, break out and return.
962 * Returns 1 if the device was bound to a driver;
963 * 0 if no matching driver was found;
964 * -ENODEV if the device is not registered.
966 * When called for a USB interface, @dev->parent lock must be held.
968 int device_attach(struct device *dev)
970 return __device_attach(dev, false);
972 EXPORT_SYMBOL_GPL(device_attach);
974 void device_initial_probe(struct device *dev)
976 __device_attach(dev, true);
980 * __device_driver_lock - acquire locks needed to manipulate dev->drv
981 * @dev: Device we will update driver info for
982 * @parent: Parent device. Needed if the bus requires parent lock
984 * This function will take the required locks for manipulating dev->drv.
985 * Normally this will just be the @dev lock, but when called for a USB
986 * interface, @parent lock will be held as well.
988 static void __device_driver_lock(struct device *dev, struct device *parent)
990 if (parent && dev->bus->need_parent_lock)
996 * __device_driver_unlock - release locks needed to manipulate dev->drv
997 * @dev: Device we will update driver info for
998 * @parent: Parent device. Needed if the bus requires parent lock
1000 * This function will release the required locks for manipulating dev->drv.
1001 * Normally this will just be the the @dev lock, but when called for a
1002 * USB interface, @parent lock will be released as well.
1004 static void __device_driver_unlock(struct device *dev, struct device *parent)
1007 if (parent && dev->bus->need_parent_lock)
1008 device_unlock(parent);
1012 * device_driver_attach - attach a specific driver to a specific device
1013 * @drv: Driver to attach
1014 * @dev: Device to attach it to
1016 * Manually attach driver to a device. Will acquire both @dev lock and
1017 * @dev->parent lock if needed.
1019 int device_driver_attach(struct device_driver *drv, struct device *dev)
1023 __device_driver_lock(dev, dev->parent);
1026 * If device has been removed or someone has already successfully
1027 * bound a driver before us just skip the driver probe call.
1029 if (!dev->p->dead && !dev->driver)
1030 ret = driver_probe_device(drv, dev);
1032 __device_driver_unlock(dev, dev->parent);
1037 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1039 struct device *dev = _dev;
1040 struct device_driver *drv;
1043 __device_driver_lock(dev, dev->parent);
1045 drv = dev->p->async_driver;
1048 * If device has been removed or someone has already successfully
1049 * bound a driver before us just skip the driver probe call.
1051 if (!dev->p->dead && !dev->driver)
1052 ret = driver_probe_device(drv, dev);
1054 __device_driver_unlock(dev, dev->parent);
1056 dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1061 static int __driver_attach(struct device *dev, void *data)
1063 struct device_driver *drv = data;
1068 * Lock device and try to bind to it. We drop the error
1069 * here and always return 0, because we need to keep trying
1070 * to bind to devices and some drivers will return an error
1071 * simply if it didn't support the device.
1073 * driver_probe_device() will spit a warning if there
1077 ret = driver_match_device(drv, dev);
1081 } else if (ret == -EPROBE_DEFER) {
1082 dev_dbg(dev, "Device match requests probe deferral\n");
1083 driver_deferred_probe_add(dev);
1085 * Driver could not match with device, but may match with
1086 * another device on the bus.
1089 } else if (ret < 0) {
1090 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1092 } /* ret > 0 means positive match */
1094 if (driver_allows_async_probing(drv)) {
1096 * Instead of probing the device synchronously we will
1097 * probe it asynchronously to allow for more parallelism.
1099 * We only take the device lock here in order to guarantee
1100 * that the dev->driver and async_driver fields are protected
1102 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1106 dev->p->async_driver = drv;
1111 async_schedule_dev(__driver_attach_async_helper, dev);
1115 device_driver_attach(drv, dev);
1121 * driver_attach - try to bind driver to devices.
1124 * Walk the list of devices that the bus has on it and try to
1125 * match the driver with each one. If driver_probe_device()
1126 * returns 0 and the @dev->driver is set, we've found a
1129 int driver_attach(struct device_driver *drv)
1131 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1133 EXPORT_SYMBOL_GPL(driver_attach);
1136 * __device_release_driver() must be called with @dev lock held.
1137 * When called for a USB interface, @dev->parent lock must be held as well.
1139 static void __device_release_driver(struct device *dev, struct device *parent)
1141 struct device_driver *drv;
1145 pm_runtime_get_sync(dev);
1147 while (device_links_busy(dev)) {
1148 __device_driver_unlock(dev, parent);
1150 device_links_unbind_consumers(dev);
1152 __device_driver_lock(dev, parent);
1154 * A concurrent invocation of the same function might
1155 * have released the driver successfully while this one
1156 * was waiting, so check for that.
1158 if (dev->driver != drv) {
1159 pm_runtime_put(dev);
1164 driver_sysfs_remove(dev);
1167 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1168 BUS_NOTIFY_UNBIND_DRIVER,
1171 pm_runtime_put_sync(dev);
1173 device_remove_file(dev, &dev_attr_state_synced);
1174 device_remove_groups(dev, drv->dev_groups);
1176 if (dev->bus && dev->bus->remove)
1177 dev->bus->remove(dev);
1178 else if (drv->remove)
1181 device_links_driver_cleanup(dev);
1183 devres_release_all(dev);
1184 arch_teardown_dma_ops(dev);
1185 kfree(dev->dma_range_map);
1186 dev->dma_range_map = NULL;
1188 dev_set_drvdata(dev, NULL);
1189 if (dev->pm_domain && dev->pm_domain->dismiss)
1190 dev->pm_domain->dismiss(dev);
1191 pm_runtime_reinit(dev);
1192 dev_pm_set_driver_flags(dev, 0);
1194 klist_remove(&dev->p->knode_driver);
1195 device_pm_check_callbacks(dev);
1197 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1198 BUS_NOTIFY_UNBOUND_DRIVER,
1201 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1205 void device_release_driver_internal(struct device *dev,
1206 struct device_driver *drv,
1207 struct device *parent)
1209 __device_driver_lock(dev, parent);
1211 if (!drv || drv == dev->driver)
1212 __device_release_driver(dev, parent);
1214 __device_driver_unlock(dev, parent);
1218 * device_release_driver - manually detach device from driver.
1221 * Manually detach device from driver.
1222 * When called for a USB interface, @dev->parent lock must be held.
1224 * If this function is to be called with @dev->parent lock held, ensure that
1225 * the device's consumers are unbound in advance or that their locks can be
1226 * acquired under the @dev->parent lock.
1228 void device_release_driver(struct device *dev)
1231 * If anyone calls device_release_driver() recursively from
1232 * within their ->remove callback for the same device, they
1233 * will deadlock right here.
1235 device_release_driver_internal(dev, NULL, NULL);
1237 EXPORT_SYMBOL_GPL(device_release_driver);
1240 * device_driver_detach - detach driver from a specific device
1241 * @dev: device to detach driver from
1243 * Detach driver from device. Will acquire both @dev lock and @dev->parent
1246 void device_driver_detach(struct device *dev)
1248 device_release_driver_internal(dev, NULL, dev->parent);
1252 * driver_detach - detach driver from all devices it controls.
1255 void driver_detach(struct device_driver *drv)
1257 struct device_private *dev_prv;
1260 if (driver_allows_async_probing(drv))
1261 async_synchronize_full();
1264 spin_lock(&drv->p->klist_devices.k_lock);
1265 if (list_empty(&drv->p->klist_devices.k_list)) {
1266 spin_unlock(&drv->p->klist_devices.k_lock);
1269 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1270 struct device_private,
1271 knode_driver.n_node);
1272 dev = dev_prv->device;
1274 spin_unlock(&drv->p->klist_devices.k_lock);
1275 device_release_driver_internal(dev, drv, dev->parent);