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 bool initcalls_done;
60 /* Save the async probe drivers' name from kernel cmdline */
61 #define ASYNC_DRV_NAMES_MAX_LEN 256
62 static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];
65 * In some cases, like suspend to RAM or hibernation, It might be reasonable
66 * to prohibit probing of devices as it could be unsafe.
67 * Once defer_all_probes is true all drivers probes will be forcibly deferred.
69 static bool defer_all_probes;
71 static void __device_set_deferred_probe_reason(const struct device *dev, char *reason)
73 kfree(dev->p->deferred_probe_reason);
74 dev->p->deferred_probe_reason = reason;
78 * deferred_probe_work_func() - Retry probing devices in the active list.
80 static void deferred_probe_work_func(struct work_struct *work)
83 struct device_private *private;
85 * This block processes every device in the deferred 'active' list.
86 * Each device is removed from the active list and passed to
87 * bus_probe_device() to re-attempt the probe. The loop continues
88 * until every device in the active list is removed and retried.
90 * Note: Once the device is removed from the list and the mutex is
91 * released, it is possible for the device get freed by another thread
92 * and cause a illegal pointer dereference. This code uses
93 * get/put_device() to ensure the device structure cannot disappear
94 * from under our feet.
96 mutex_lock(&deferred_probe_mutex);
97 while (!list_empty(&deferred_probe_active_list)) {
98 private = list_first_entry(&deferred_probe_active_list,
99 typeof(*dev->p), deferred_probe);
100 dev = private->device;
101 list_del_init(&private->deferred_probe);
105 __device_set_deferred_probe_reason(dev, NULL);
108 * Drop the mutex while probing each device; the probe path may
109 * manipulate the deferred list
111 mutex_unlock(&deferred_probe_mutex);
114 * Force the device to the end of the dpm_list since
115 * the PM code assumes that the order we add things to
116 * the list is a good order for suspend but deferred
117 * probe makes that very unsafe.
119 device_pm_move_to_tail(dev);
121 dev_dbg(dev, "Retrying from deferred list\n");
122 bus_probe_device(dev);
123 mutex_lock(&deferred_probe_mutex);
127 mutex_unlock(&deferred_probe_mutex);
129 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
131 void driver_deferred_probe_add(struct device *dev)
136 mutex_lock(&deferred_probe_mutex);
137 if (list_empty(&dev->p->deferred_probe)) {
138 dev_dbg(dev, "Added to deferred list\n");
139 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
141 mutex_unlock(&deferred_probe_mutex);
144 void driver_deferred_probe_del(struct device *dev)
146 mutex_lock(&deferred_probe_mutex);
147 if (!list_empty(&dev->p->deferred_probe)) {
148 dev_dbg(dev, "Removed from deferred list\n");
149 list_del_init(&dev->p->deferred_probe);
150 __device_set_deferred_probe_reason(dev, NULL);
152 mutex_unlock(&deferred_probe_mutex);
155 static bool driver_deferred_probe_enable;
157 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
159 * This functions moves all devices from the pending list to the active
160 * list and schedules the deferred probe workqueue to process them. It
161 * should be called anytime a driver is successfully bound to a device.
163 * Note, there is a race condition in multi-threaded probe. In the case where
164 * more than one device is probing at the same time, it is possible for one
165 * probe to complete successfully while another is about to defer. If the second
166 * depends on the first, then it will get put on the pending list after the
167 * trigger event has already occurred and will be stuck there.
169 * The atomic 'deferred_trigger_count' is used to determine if a successful
170 * trigger has occurred in the midst of probing a driver. If the trigger count
171 * changes in the midst of a probe, then deferred processing should be triggered
174 static void driver_deferred_probe_trigger(void)
176 if (!driver_deferred_probe_enable)
180 * A successful probe means that all the devices in the pending list
181 * should be triggered to be reprobed. Move all the deferred devices
182 * into the active list so they can be retried by the workqueue
184 mutex_lock(&deferred_probe_mutex);
185 atomic_inc(&deferred_trigger_count);
186 list_splice_tail_init(&deferred_probe_pending_list,
187 &deferred_probe_active_list);
188 mutex_unlock(&deferred_probe_mutex);
191 * Kick the re-probe thread. It may already be scheduled, but it is
192 * safe to kick it again.
194 queue_work(system_unbound_wq, &deferred_probe_work);
198 * device_block_probing() - Block/defer device's probes
200 * It will disable probing of devices and defer their probes instead.
202 void device_block_probing(void)
204 defer_all_probes = true;
205 /* sync with probes to avoid races. */
206 wait_for_device_probe();
210 * device_unblock_probing() - Unblock/enable device's probes
212 * It will restore normal behavior and trigger re-probing of deferred
215 void device_unblock_probing(void)
217 defer_all_probes = false;
218 driver_deferred_probe_trigger();
222 * device_set_deferred_probe_reason() - Set defer probe reason message for device
223 * @dev: the pointer to the struct device
224 * @vaf: the pointer to va_format structure with message
226 void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
228 const char *drv = dev_driver_string(dev);
231 mutex_lock(&deferred_probe_mutex);
233 reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
234 __device_set_deferred_probe_reason(dev, reason);
236 mutex_unlock(&deferred_probe_mutex);
240 * deferred_devs_show() - Show the devices in the deferred probe pending list.
242 static int deferred_devs_show(struct seq_file *s, void *data)
244 struct device_private *curr;
246 mutex_lock(&deferred_probe_mutex);
248 list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
249 seq_printf(s, "%s\t%s", dev_name(curr->device),
250 curr->device->p->deferred_probe_reason ?: "\n");
252 mutex_unlock(&deferred_probe_mutex);
256 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
258 int driver_deferred_probe_timeout;
259 EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
260 static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue);
262 static int __init deferred_probe_timeout_setup(char *str)
266 if (!kstrtoint(str, 10, &timeout))
267 driver_deferred_probe_timeout = timeout;
270 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
273 * driver_deferred_probe_check_state() - Check deferred probe state
274 * @dev: device to check
277 * * -ENODEV if initcalls have completed and modules are disabled.
278 * * -ETIMEDOUT if the deferred probe timeout was set and has expired
279 * and modules are enabled.
280 * * -EPROBE_DEFER in other cases.
282 * Drivers or subsystems can opt-in to calling this function instead of directly
283 * returning -EPROBE_DEFER.
285 int driver_deferred_probe_check_state(struct device *dev)
287 if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
288 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
292 if (!driver_deferred_probe_timeout && initcalls_done) {
293 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
297 return -EPROBE_DEFER;
299 EXPORT_SYMBOL_GPL(driver_deferred_probe_check_state);
301 static void deferred_probe_timeout_work_func(struct work_struct *work)
303 struct device_private *p;
305 fw_devlink_drivers_done();
307 driver_deferred_probe_timeout = 0;
308 driver_deferred_probe_trigger();
309 flush_work(&deferred_probe_work);
311 mutex_lock(&deferred_probe_mutex);
312 list_for_each_entry(p, &deferred_probe_pending_list, deferred_probe)
313 dev_info(p->device, "deferred probe pending\n");
314 mutex_unlock(&deferred_probe_mutex);
315 wake_up_all(&probe_timeout_waitqueue);
317 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
320 * deferred_probe_initcall() - Enable probing of deferred devices
322 * We don't want to get in the way when the bulk of drivers are getting probed.
323 * Instead, this initcall makes sure that deferred probing is delayed until
324 * late_initcall time.
326 static int deferred_probe_initcall(void)
328 debugfs_create_file("devices_deferred", 0444, NULL, NULL,
329 &deferred_devs_fops);
331 driver_deferred_probe_enable = true;
332 driver_deferred_probe_trigger();
333 /* Sort as many dependencies as possible before exiting initcalls */
334 flush_work(&deferred_probe_work);
335 initcalls_done = true;
337 if (!IS_ENABLED(CONFIG_MODULES))
338 fw_devlink_drivers_done();
341 * Trigger deferred probe again, this time we won't defer anything
344 driver_deferred_probe_trigger();
345 flush_work(&deferred_probe_work);
347 if (driver_deferred_probe_timeout > 0) {
348 schedule_delayed_work(&deferred_probe_timeout_work,
349 driver_deferred_probe_timeout * HZ);
353 late_initcall(deferred_probe_initcall);
355 static void __exit deferred_probe_exit(void)
357 debugfs_remove_recursive(debugfs_lookup("devices_deferred", NULL));
359 __exitcall(deferred_probe_exit);
362 * device_is_bound() - Check if device is bound to a driver
363 * @dev: device to check
365 * Returns true if passed device has already finished probing successfully
368 * This function must be called with the device lock held.
370 bool device_is_bound(struct device *dev)
372 return dev->p && klist_node_attached(&dev->p->knode_driver);
375 static void driver_bound(struct device *dev)
377 if (device_is_bound(dev)) {
378 pr_warn("%s: device %s already bound\n",
379 __func__, kobject_name(&dev->kobj));
383 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
384 __func__, dev_name(dev));
386 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
387 device_links_driver_bound(dev);
389 device_pm_check_callbacks(dev);
392 * Make sure the device is no longer in one of the deferred lists and
393 * kick off retrying all pending devices
395 driver_deferred_probe_del(dev);
396 driver_deferred_probe_trigger();
399 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
400 BUS_NOTIFY_BOUND_DRIVER, dev);
402 kobject_uevent(&dev->kobj, KOBJ_BIND);
405 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
406 const char *buf, size_t count)
409 dev->driver->coredump(dev);
414 static DEVICE_ATTR_WO(coredump);
416 static int driver_sysfs_add(struct device *dev)
421 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
422 BUS_NOTIFY_BIND_DRIVER, dev);
424 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
425 kobject_name(&dev->kobj));
429 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
434 if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump)
437 ret = device_create_file(dev, &dev_attr_coredump);
441 sysfs_remove_link(&dev->kobj, "driver");
444 sysfs_remove_link(&dev->driver->p->kobj,
445 kobject_name(&dev->kobj));
451 static void driver_sysfs_remove(struct device *dev)
453 struct device_driver *drv = dev->driver;
457 device_remove_file(dev, &dev_attr_coredump);
458 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
459 sysfs_remove_link(&dev->kobj, "driver");
464 * device_bind_driver - bind a driver to one device.
467 * Allow manual attachment of a driver to a device.
468 * Caller must have already set @dev->driver.
470 * Note that this does not modify the bus reference count.
471 * Please verify that is accounted for before calling this.
472 * (It is ok to call with no other effort from a driver's probe() method.)
474 * This function must be called with the device lock held.
476 * Callers should prefer to use device_driver_attach() instead.
478 int device_bind_driver(struct device *dev)
482 ret = driver_sysfs_add(dev);
484 device_links_force_bind(dev);
488 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
489 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
492 EXPORT_SYMBOL_GPL(device_bind_driver);
494 static atomic_t probe_count = ATOMIC_INIT(0);
495 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
497 static ssize_t state_synced_show(struct device *dev,
498 struct device_attribute *attr, char *buf)
503 val = dev->state_synced;
506 return sysfs_emit(buf, "%u\n", val);
508 static DEVICE_ATTR_RO(state_synced);
510 static void device_unbind_cleanup(struct device *dev)
512 devres_release_all(dev);
513 arch_teardown_dma_ops(dev);
514 kfree(dev->dma_range_map);
515 dev->dma_range_map = NULL;
517 dev_set_drvdata(dev, NULL);
518 if (dev->pm_domain && dev->pm_domain->dismiss)
519 dev->pm_domain->dismiss(dev);
520 pm_runtime_reinit(dev);
521 dev_pm_set_driver_flags(dev, 0);
524 static void device_remove(struct device *dev)
526 device_remove_file(dev, &dev_attr_state_synced);
527 device_remove_groups(dev, dev->driver->dev_groups);
529 if (dev->bus && dev->bus->remove)
530 dev->bus->remove(dev);
531 else if (dev->driver->remove)
532 dev->driver->remove(dev);
535 static int call_driver_probe(struct device *dev, struct device_driver *drv)
540 ret = dev->bus->probe(dev);
542 ret = drv->probe(dev);
548 /* Driver requested deferred probing */
549 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
553 pr_debug("%s: probe of %s rejects match %d\n",
554 drv->name, dev_name(dev), ret);
557 /* driver matched but the probe failed */
558 pr_warn("%s: probe of %s failed with error %d\n",
559 drv->name, dev_name(dev), ret);
566 static int really_probe(struct device *dev, struct device_driver *drv)
568 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
569 !drv->suppress_bind_attrs;
572 if (defer_all_probes) {
574 * Value of defer_all_probes can be set only by
575 * device_block_probing() which, in turn, will call
576 * wait_for_device_probe() right after that to avoid any races.
578 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
579 return -EPROBE_DEFER;
582 ret = device_links_check_suppliers(dev);
586 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
587 drv->bus->name, __func__, drv->name, dev_name(dev));
588 if (!list_empty(&dev->devres_head)) {
589 dev_crit(dev, "Resources present before probing\n");
597 /* If using pinctrl, bind pins now before probing */
598 ret = pinctrl_bind_pins(dev);
600 goto pinctrl_bind_failed;
602 if (dev->bus->dma_configure) {
603 ret = dev->bus->dma_configure(dev);
605 goto pinctrl_bind_failed;
608 ret = driver_sysfs_add(dev);
610 pr_err("%s: driver_sysfs_add(%s) failed\n",
611 __func__, dev_name(dev));
615 if (dev->pm_domain && dev->pm_domain->activate) {
616 ret = dev->pm_domain->activate(dev);
621 ret = call_driver_probe(dev, drv);
624 * Return probe errors as positive values so that the callers
625 * can distinguish them from other errors.
631 ret = device_add_groups(dev, drv->dev_groups);
633 dev_err(dev, "device_add_groups() failed\n");
634 goto dev_groups_failed;
637 if (dev_has_sync_state(dev)) {
638 ret = device_create_file(dev, &dev_attr_state_synced);
640 dev_err(dev, "state_synced sysfs add failed\n");
641 goto dev_sysfs_state_synced_failed;
649 driver_sysfs_remove(dev);
650 device_unbind_cleanup(dev);
655 pinctrl_init_done(dev);
657 if (dev->pm_domain && dev->pm_domain->sync)
658 dev->pm_domain->sync(dev);
661 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
662 drv->bus->name, __func__, dev_name(dev), drv->name);
665 dev_sysfs_state_synced_failed:
669 driver_sysfs_remove(dev);
672 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
673 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
675 device_links_no_driver(dev);
676 device_unbind_cleanup(dev);
682 * For initcall_debug, show the driver probe time.
684 static int really_probe_debug(struct device *dev, struct device_driver *drv)
686 ktime_t calltime, rettime;
689 calltime = ktime_get();
690 ret = really_probe(dev, drv);
691 rettime = ktime_get();
692 pr_debug("probe of %s returned %d after %lld usecs\n",
693 dev_name(dev), ret, ktime_us_delta(rettime, calltime));
699 * Determine if the probe sequence is finished or not.
701 * Should somehow figure out how to use a semaphore, not an atomic variable...
703 int driver_probe_done(void)
705 int local_probe_count = atomic_read(&probe_count);
707 pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
708 if (local_probe_count)
714 * wait_for_device_probe
715 * Wait for device probing to be completed.
717 void wait_for_device_probe(void)
719 /* wait for probe timeout */
720 wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout);
722 /* wait for the deferred probe workqueue to finish */
723 flush_work(&deferred_probe_work);
725 /* wait for the known devices to complete their probing */
726 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
727 async_synchronize_full();
729 EXPORT_SYMBOL_GPL(wait_for_device_probe);
731 static int __driver_probe_device(struct device_driver *drv, struct device *dev)
735 if (dev->p->dead || !device_is_registered(dev))
740 dev->can_match = true;
741 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
742 drv->bus->name, __func__, dev_name(dev), drv->name);
744 pm_runtime_get_suppliers(dev);
746 pm_runtime_get_sync(dev->parent);
748 pm_runtime_barrier(dev);
750 ret = really_probe_debug(dev, drv);
752 ret = really_probe(dev, drv);
753 pm_request_idle(dev);
756 pm_runtime_put(dev->parent);
758 pm_runtime_put_suppliers(dev);
763 * driver_probe_device - attempt to bind device & driver together
764 * @drv: driver to bind a device to
765 * @dev: device to try to bind to the driver
767 * This function returns -ENODEV if the device is not registered, -EBUSY if it
768 * already has a driver, 0 if the device is bound successfully and a positive
769 * (inverted) error code for failures from the ->probe method.
771 * This function must be called with @dev lock held. When called for a
772 * USB interface, @dev->parent lock must be held as well.
774 * If the device has a parent, runtime-resume the parent before driver probing.
776 static int driver_probe_device(struct device_driver *drv, struct device *dev)
778 int trigger_count = atomic_read(&deferred_trigger_count);
781 atomic_inc(&probe_count);
782 ret = __driver_probe_device(drv, dev);
783 if (ret == -EPROBE_DEFER || ret == EPROBE_DEFER) {
784 driver_deferred_probe_add(dev);
787 * Did a trigger occur while probing? Need to re-trigger if yes
789 if (trigger_count != atomic_read(&deferred_trigger_count) &&
791 driver_deferred_probe_trigger();
793 atomic_dec(&probe_count);
794 wake_up_all(&probe_waitqueue);
798 static inline bool cmdline_requested_async_probing(const char *drv_name)
800 return parse_option_str(async_probe_drv_names, drv_name);
803 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
804 static int __init save_async_options(char *buf)
806 if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
807 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
809 strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
812 __setup("driver_async_probe=", save_async_options);
814 bool driver_allows_async_probing(struct device_driver *drv)
816 switch (drv->probe_type) {
817 case PROBE_PREFER_ASYNCHRONOUS:
820 case PROBE_FORCE_SYNCHRONOUS:
824 if (cmdline_requested_async_probing(drv->name))
827 if (module_requested_async_probing(drv->owner))
834 struct device_attach_data {
838 * Indicates whether we are considering asynchronous probing or
839 * not. Only initial binding after device or driver registration
840 * (including deferral processing) may be done asynchronously, the
841 * rest is always synchronous, as we expect it is being done by
842 * request from userspace.
847 * Indicates if we are binding synchronous or asynchronous drivers.
848 * When asynchronous probing is enabled we'll execute 2 passes
849 * over drivers: first pass doing synchronous probing and second
850 * doing asynchronous probing (if synchronous did not succeed -
851 * most likely because there was no driver requiring synchronous
852 * probing - and we found asynchronous driver during first pass).
853 * The 2 passes are done because we can't shoot asynchronous
854 * probe for given device and driver from bus_for_each_drv() since
855 * driver pointer is not guaranteed to stay valid once
856 * bus_for_each_drv() iterates to the next driver on the bus.
861 * We'll set have_async to 'true' if, while scanning for matching
862 * driver, we'll encounter one that requests asynchronous probing.
867 static int __device_attach_driver(struct device_driver *drv, void *_data)
869 struct device_attach_data *data = _data;
870 struct device *dev = data->dev;
874 ret = driver_match_device(drv, dev);
878 } else if (ret == -EPROBE_DEFER) {
879 dev_dbg(dev, "Device match requests probe deferral\n");
880 dev->can_match = true;
881 driver_deferred_probe_add(dev);
882 } else if (ret < 0) {
883 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
885 } /* ret > 0 means positive match */
887 async_allowed = driver_allows_async_probing(drv);
890 data->have_async = true;
892 if (data->check_async && async_allowed != data->want_async)
896 * Ignore errors returned by ->probe so that the next driver can try
899 ret = driver_probe_device(drv, dev);
905 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
907 struct device *dev = _dev;
908 struct device_attach_data data = {
917 * Check if device has already been removed or claimed. This may
918 * happen with driver loading, device discovery/registration,
919 * and deferred probe processing happens all at once with
922 if (dev->p->dead || dev->driver)
926 pm_runtime_get_sync(dev->parent);
928 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
929 dev_dbg(dev, "async probe completed\n");
931 pm_request_idle(dev);
934 pm_runtime_put(dev->parent);
941 static int __device_attach(struct device *dev, bool allow_async)
948 } else if (dev->driver) {
949 if (device_is_bound(dev)) {
953 ret = device_bind_driver(dev);
961 struct device_attach_data data = {
963 .check_async = allow_async,
968 pm_runtime_get_sync(dev->parent);
970 ret = bus_for_each_drv(dev->bus, NULL, &data,
971 __device_attach_driver);
972 if (!ret && allow_async && data.have_async) {
974 * If we could not find appropriate driver
975 * synchronously and we are allowed to do
976 * async probes and there are drivers that
977 * want to probe asynchronously, we'll
980 dev_dbg(dev, "scheduling asynchronous probe\n");
982 async_schedule_dev(__device_attach_async_helper, dev);
984 pm_request_idle(dev);
988 pm_runtime_put(dev->parent);
996 * device_attach - try to attach device to a driver.
999 * Walk the list of drivers that the bus has and call
1000 * driver_probe_device() for each pair. If a compatible
1001 * pair is found, break out and return.
1003 * Returns 1 if the device was bound to a driver;
1004 * 0 if no matching driver was found;
1005 * -ENODEV if the device is not registered.
1007 * When called for a USB interface, @dev->parent lock must be held.
1009 int device_attach(struct device *dev)
1011 return __device_attach(dev, false);
1013 EXPORT_SYMBOL_GPL(device_attach);
1015 void device_initial_probe(struct device *dev)
1017 __device_attach(dev, true);
1021 * __device_driver_lock - acquire locks needed to manipulate dev->drv
1022 * @dev: Device we will update driver info for
1023 * @parent: Parent device. Needed if the bus requires parent lock
1025 * This function will take the required locks for manipulating dev->drv.
1026 * Normally this will just be the @dev lock, but when called for a USB
1027 * interface, @parent lock will be held as well.
1029 static void __device_driver_lock(struct device *dev, struct device *parent)
1031 if (parent && dev->bus->need_parent_lock)
1032 device_lock(parent);
1037 * __device_driver_unlock - release locks needed to manipulate dev->drv
1038 * @dev: Device we will update driver info for
1039 * @parent: Parent device. Needed if the bus requires parent lock
1041 * This function will release the required locks for manipulating dev->drv.
1042 * Normally this will just be the @dev lock, but when called for a
1043 * USB interface, @parent lock will be released as well.
1045 static void __device_driver_unlock(struct device *dev, struct device *parent)
1048 if (parent && dev->bus->need_parent_lock)
1049 device_unlock(parent);
1053 * device_driver_attach - attach a specific driver to a specific device
1054 * @drv: Driver to attach
1055 * @dev: Device to attach it to
1057 * Manually attach driver to a device. Will acquire both @dev lock and
1058 * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1060 int device_driver_attach(struct device_driver *drv, struct device *dev)
1064 __device_driver_lock(dev, dev->parent);
1065 ret = __driver_probe_device(drv, dev);
1066 __device_driver_unlock(dev, dev->parent);
1068 /* also return probe errors as normal negative errnos */
1071 if (ret == -EPROBE_DEFER)
1075 EXPORT_SYMBOL_GPL(device_driver_attach);
1077 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1079 struct device *dev = _dev;
1080 struct device_driver *drv;
1083 __device_driver_lock(dev, dev->parent);
1084 drv = dev->p->async_driver;
1085 dev->p->async_driver = NULL;
1086 ret = driver_probe_device(drv, dev);
1087 __device_driver_unlock(dev, dev->parent);
1089 dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1094 static int __driver_attach(struct device *dev, void *data)
1096 struct device_driver *drv = data;
1100 * Lock device and try to bind to it. We drop the error
1101 * here and always return 0, because we need to keep trying
1102 * to bind to devices and some drivers will return an error
1103 * simply if it didn't support the device.
1105 * driver_probe_device() will spit a warning if there
1109 ret = driver_match_device(drv, dev);
1113 } else if (ret == -EPROBE_DEFER) {
1114 dev_dbg(dev, "Device match requests probe deferral\n");
1115 dev->can_match = true;
1116 driver_deferred_probe_add(dev);
1117 } else if (ret < 0) {
1118 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1120 } /* ret > 0 means positive match */
1122 if (driver_allows_async_probing(drv)) {
1124 * Instead of probing the device synchronously we will
1125 * probe it asynchronously to allow for more parallelism.
1127 * We only take the device lock here in order to guarantee
1128 * that the dev->driver and async_driver fields are protected
1130 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1132 if (!dev->driver && !dev->p->async_driver) {
1134 dev->p->async_driver = drv;
1135 async_schedule_dev(__driver_attach_async_helper, dev);
1141 __device_driver_lock(dev, dev->parent);
1142 driver_probe_device(drv, dev);
1143 __device_driver_unlock(dev, dev->parent);
1149 * driver_attach - try to bind driver to devices.
1152 * Walk the list of devices that the bus has on it and try to
1153 * match the driver with each one. If driver_probe_device()
1154 * returns 0 and the @dev->driver is set, we've found a
1157 int driver_attach(struct device_driver *drv)
1159 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1161 EXPORT_SYMBOL_GPL(driver_attach);
1164 * __device_release_driver() must be called with @dev lock held.
1165 * When called for a USB interface, @dev->parent lock must be held as well.
1167 static void __device_release_driver(struct device *dev, struct device *parent)
1169 struct device_driver *drv;
1173 pm_runtime_get_sync(dev);
1175 while (device_links_busy(dev)) {
1176 __device_driver_unlock(dev, parent);
1178 device_links_unbind_consumers(dev);
1180 __device_driver_lock(dev, parent);
1182 * A concurrent invocation of the same function might
1183 * have released the driver successfully while this one
1184 * was waiting, so check for that.
1186 if (dev->driver != drv) {
1187 pm_runtime_put(dev);
1192 driver_sysfs_remove(dev);
1195 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1196 BUS_NOTIFY_UNBIND_DRIVER,
1199 pm_runtime_put_sync(dev);
1203 device_links_driver_cleanup(dev);
1204 device_unbind_cleanup(dev);
1206 klist_remove(&dev->p->knode_driver);
1207 device_pm_check_callbacks(dev);
1209 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1210 BUS_NOTIFY_UNBOUND_DRIVER,
1213 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1217 void device_release_driver_internal(struct device *dev,
1218 struct device_driver *drv,
1219 struct device *parent)
1221 __device_driver_lock(dev, parent);
1223 if (!drv || drv == dev->driver)
1224 __device_release_driver(dev, parent);
1226 __device_driver_unlock(dev, parent);
1230 * device_release_driver - manually detach device from driver.
1233 * Manually detach device from driver.
1234 * When called for a USB interface, @dev->parent lock must be held.
1236 * If this function is to be called with @dev->parent lock held, ensure that
1237 * the device's consumers are unbound in advance or that their locks can be
1238 * acquired under the @dev->parent lock.
1240 void device_release_driver(struct device *dev)
1243 * If anyone calls device_release_driver() recursively from
1244 * within their ->remove callback for the same device, they
1245 * will deadlock right here.
1247 device_release_driver_internal(dev, NULL, NULL);
1249 EXPORT_SYMBOL_GPL(device_release_driver);
1252 * device_driver_detach - detach driver from a specific device
1253 * @dev: device to detach driver from
1255 * Detach driver from device. Will acquire both @dev lock and @dev->parent
1258 void device_driver_detach(struct device *dev)
1260 device_release_driver_internal(dev, NULL, dev->parent);
1264 * driver_detach - detach driver from all devices it controls.
1267 void driver_detach(struct device_driver *drv)
1269 struct device_private *dev_prv;
1272 if (driver_allows_async_probing(drv))
1273 async_synchronize_full();
1276 spin_lock(&drv->p->klist_devices.k_lock);
1277 if (list_empty(&drv->p->klist_devices.k_list)) {
1278 spin_unlock(&drv->p->klist_devices.k_lock);
1281 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1282 struct device_private,
1283 knode_driver.n_node);
1284 dev = dev_prv->device;
1286 spin_unlock(&drv->p->klist_devices.k_lock);
1287 device_release_driver_internal(dev, drv, dev->parent);