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);
101 * Drop the mutex while probing each device; the probe path may
102 * manipulate the deferred list
104 mutex_unlock(&deferred_probe_mutex);
107 * Force the device to the end of the dpm_list since
108 * the PM code assumes that the order we add things to
109 * the list is a good order for suspend but deferred
110 * probe makes that very unsafe.
112 device_pm_move_to_tail(dev);
114 dev_dbg(dev, "Retrying from deferred list\n");
115 bus_probe_device(dev);
116 mutex_lock(&deferred_probe_mutex);
120 mutex_unlock(&deferred_probe_mutex);
122 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
124 void driver_deferred_probe_add(struct device *dev)
126 mutex_lock(&deferred_probe_mutex);
127 if (list_empty(&dev->p->deferred_probe)) {
128 dev_dbg(dev, "Added to deferred list\n");
129 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
131 mutex_unlock(&deferred_probe_mutex);
134 void driver_deferred_probe_del(struct device *dev)
136 mutex_lock(&deferred_probe_mutex);
137 if (!list_empty(&dev->p->deferred_probe)) {
138 dev_dbg(dev, "Removed from deferred list\n");
139 list_del_init(&dev->p->deferred_probe);
140 kfree(dev->p->deferred_probe_reason);
141 dev->p->deferred_probe_reason = NULL;
143 mutex_unlock(&deferred_probe_mutex);
146 static bool driver_deferred_probe_enable = false;
148 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
150 * This functions moves all devices from the pending list to the active
151 * list and schedules the deferred probe workqueue to process them. It
152 * should be called anytime a driver is successfully bound to a device.
154 * Note, there is a race condition in multi-threaded probe. In the case where
155 * more than one device is probing at the same time, it is possible for one
156 * probe to complete successfully while another is about to defer. If the second
157 * depends on the first, then it will get put on the pending list after the
158 * trigger event has already occurred and will be stuck there.
160 * The atomic 'deferred_trigger_count' is used to determine if a successful
161 * trigger has occurred in the midst of probing a driver. If the trigger count
162 * changes in the midst of a probe, then deferred processing should be triggered
165 static void driver_deferred_probe_trigger(void)
167 if (!driver_deferred_probe_enable)
171 * A successful probe means that all the devices in the pending list
172 * should be triggered to be reprobed. Move all the deferred devices
173 * into the active list so they can be retried by the workqueue
175 mutex_lock(&deferred_probe_mutex);
176 atomic_inc(&deferred_trigger_count);
177 list_splice_tail_init(&deferred_probe_pending_list,
178 &deferred_probe_active_list);
179 mutex_unlock(&deferred_probe_mutex);
182 * Kick the re-probe thread. It may already be scheduled, but it is
183 * safe to kick it again.
185 schedule_work(&deferred_probe_work);
189 * device_block_probing() - Block/defer device's probes
191 * It will disable probing of devices and defer their probes instead.
193 void device_block_probing(void)
195 defer_all_probes = true;
196 /* sync with probes to avoid races. */
197 wait_for_device_probe();
201 * device_unblock_probing() - Unblock/enable device's probes
203 * It will restore normal behavior and trigger re-probing of deferred
206 void device_unblock_probing(void)
208 defer_all_probes = false;
209 driver_deferred_probe_trigger();
213 * device_set_deferred_probe_reason() - Set defer probe reason message for device
214 * @dev: the pointer to the struct device
215 * @vaf: the pointer to va_format structure with message
217 void device_set_deferred_probe_reason(const struct device *dev, struct va_format *vaf)
219 const char *drv = dev_driver_string(dev);
221 mutex_lock(&deferred_probe_mutex);
223 kfree(dev->p->deferred_probe_reason);
224 dev->p->deferred_probe_reason = kasprintf(GFP_KERNEL, "%s: %pV", drv, vaf);
226 mutex_unlock(&deferred_probe_mutex);
230 * deferred_devs_show() - Show the devices in the deferred probe pending list.
232 static int deferred_devs_show(struct seq_file *s, void *data)
234 struct device_private *curr;
236 mutex_lock(&deferred_probe_mutex);
238 list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
239 seq_printf(s, "%s\t%s", dev_name(curr->device),
240 curr->device->p->deferred_probe_reason ?: "\n");
242 mutex_unlock(&deferred_probe_mutex);
246 DEFINE_SHOW_ATTRIBUTE(deferred_devs);
248 int driver_deferred_probe_timeout;
249 EXPORT_SYMBOL_GPL(driver_deferred_probe_timeout);
250 static DECLARE_WAIT_QUEUE_HEAD(probe_timeout_waitqueue);
252 static int __init deferred_probe_timeout_setup(char *str)
256 if (!kstrtoint(str, 10, &timeout))
257 driver_deferred_probe_timeout = timeout;
260 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup);
263 * driver_deferred_probe_check_state() - Check deferred probe state
264 * @dev: device to check
267 * -ENODEV if initcalls have completed and modules are disabled.
268 * -ETIMEDOUT if the deferred probe timeout was set and has expired
269 * and modules are enabled.
270 * -EPROBE_DEFER in other cases.
272 * Drivers or subsystems can opt-in to calling this function instead of directly
273 * returning -EPROBE_DEFER.
275 int driver_deferred_probe_check_state(struct device *dev)
277 if (!IS_ENABLED(CONFIG_MODULES) && initcalls_done) {
278 dev_warn(dev, "ignoring dependency for device, assuming no driver\n");
282 if (!driver_deferred_probe_timeout && initcalls_done) {
283 dev_warn(dev, "deferred probe timeout, ignoring dependency\n");
287 return -EPROBE_DEFER;
290 static void deferred_probe_timeout_work_func(struct work_struct *work)
292 struct device_private *private, *p;
294 driver_deferred_probe_timeout = 0;
295 driver_deferred_probe_trigger();
296 flush_work(&deferred_probe_work);
298 list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe)
299 dev_info(private->device, "deferred probe pending\n");
300 wake_up_all(&probe_timeout_waitqueue);
302 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);
305 * deferred_probe_initcall() - Enable probing of deferred devices
307 * We don't want to get in the way when the bulk of drivers are getting probed.
308 * Instead, this initcall makes sure that deferred probing is delayed until
309 * late_initcall time.
311 static int deferred_probe_initcall(void)
313 deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL,
314 NULL, &deferred_devs_fops);
316 driver_deferred_probe_enable = true;
317 driver_deferred_probe_trigger();
318 /* Sort as many dependencies as possible before exiting initcalls */
319 flush_work(&deferred_probe_work);
320 initcalls_done = true;
323 * Trigger deferred probe again, this time we won't defer anything
326 driver_deferred_probe_trigger();
327 flush_work(&deferred_probe_work);
329 if (driver_deferred_probe_timeout > 0) {
330 schedule_delayed_work(&deferred_probe_timeout_work,
331 driver_deferred_probe_timeout * HZ);
335 late_initcall(deferred_probe_initcall);
337 static void __exit deferred_probe_exit(void)
339 debugfs_remove_recursive(deferred_devices);
341 __exitcall(deferred_probe_exit);
344 * device_is_bound() - Check if device is bound to a driver
345 * @dev: device to check
347 * Returns true if passed device has already finished probing successfully
350 * This function must be called with the device lock held.
352 bool device_is_bound(struct device *dev)
354 return dev->p && klist_node_attached(&dev->p->knode_driver);
357 static void driver_bound(struct device *dev)
359 if (device_is_bound(dev)) {
360 pr_warn("%s: device %s already bound\n",
361 __func__, kobject_name(&dev->kobj));
365 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
366 __func__, dev_name(dev));
368 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
369 device_links_driver_bound(dev);
371 device_pm_check_callbacks(dev);
374 * Make sure the device is no longer in one of the deferred lists and
375 * kick off retrying all pending devices
377 driver_deferred_probe_del(dev);
378 driver_deferred_probe_trigger();
381 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
382 BUS_NOTIFY_BOUND_DRIVER, dev);
384 kobject_uevent(&dev->kobj, KOBJ_BIND);
387 static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
388 const char *buf, size_t count)
391 dev->driver->coredump(dev);
396 static DEVICE_ATTR_WO(coredump);
398 static int driver_sysfs_add(struct device *dev)
403 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
404 BUS_NOTIFY_BIND_DRIVER, dev);
406 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
407 kobject_name(&dev->kobj));
411 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
416 if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
417 !device_create_file(dev, &dev_attr_coredump))
420 sysfs_remove_link(&dev->kobj, "driver");
423 sysfs_remove_link(&dev->driver->p->kobj,
424 kobject_name(&dev->kobj));
430 static void driver_sysfs_remove(struct device *dev)
432 struct device_driver *drv = dev->driver;
436 device_remove_file(dev, &dev_attr_coredump);
437 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
438 sysfs_remove_link(&dev->kobj, "driver");
443 * device_bind_driver - bind a driver to one device.
446 * Allow manual attachment of a driver to a device.
447 * Caller must have already set @dev->driver.
449 * Note that this does not modify the bus reference count.
450 * Please verify that is accounted for before calling this.
451 * (It is ok to call with no other effort from a driver's probe() method.)
453 * This function must be called with the device lock held.
455 int device_bind_driver(struct device *dev)
459 ret = driver_sysfs_add(dev);
463 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
464 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
467 EXPORT_SYMBOL_GPL(device_bind_driver);
469 static atomic_t probe_count = ATOMIC_INIT(0);
470 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
472 static void driver_deferred_probe_add_trigger(struct device *dev,
473 int local_trigger_count)
475 driver_deferred_probe_add(dev);
476 /* Did a trigger occur while probing? Need to re-trigger if yes */
477 if (local_trigger_count != atomic_read(&deferred_trigger_count))
478 driver_deferred_probe_trigger();
481 static ssize_t state_synced_show(struct device *dev,
482 struct device_attribute *attr, char *buf)
487 val = dev->state_synced;
490 return sysfs_emit(buf, "%u\n", val);
492 static DEVICE_ATTR_RO(state_synced);
494 static int really_probe(struct device *dev, struct device_driver *drv)
496 int ret = -EPROBE_DEFER;
497 int local_trigger_count = atomic_read(&deferred_trigger_count);
498 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
499 !drv->suppress_bind_attrs;
501 if (defer_all_probes) {
503 * Value of defer_all_probes can be set only by
504 * device_block_probing() which, in turn, will call
505 * wait_for_device_probe() right after that to avoid any races.
507 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
508 driver_deferred_probe_add(dev);
512 ret = device_links_check_suppliers(dev);
513 if (ret == -EPROBE_DEFER)
514 driver_deferred_probe_add_trigger(dev, local_trigger_count);
518 atomic_inc(&probe_count);
519 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
520 drv->bus->name, __func__, drv->name, dev_name(dev));
521 if (!list_empty(&dev->devres_head)) {
522 dev_crit(dev, "Resources present before probing\n");
530 /* If using pinctrl, bind pins now before probing */
531 ret = pinctrl_bind_pins(dev);
533 goto pinctrl_bind_failed;
535 if (dev->bus->dma_configure) {
536 ret = dev->bus->dma_configure(dev);
541 if (driver_sysfs_add(dev)) {
542 pr_err("%s: driver_sysfs_add(%s) failed\n",
543 __func__, dev_name(dev));
547 if (dev->pm_domain && dev->pm_domain->activate) {
548 ret = dev->pm_domain->activate(dev);
553 if (dev->bus->probe) {
554 ret = dev->bus->probe(dev);
557 } else if (drv->probe) {
558 ret = drv->probe(dev);
563 if (device_add_groups(dev, drv->dev_groups)) {
564 dev_err(dev, "device_add_groups() failed\n");
565 goto dev_groups_failed;
568 if (dev_has_sync_state(dev) &&
569 device_create_file(dev, &dev_attr_state_synced)) {
570 dev_err(dev, "state_synced sysfs add failed\n");
571 goto dev_sysfs_state_synced_failed;
577 device_remove_file(dev, &dev_attr_state_synced);
578 device_remove_groups(dev, drv->dev_groups);
580 if (dev->bus->remove)
581 dev->bus->remove(dev);
582 else if (drv->remove)
585 devres_release_all(dev);
586 driver_sysfs_remove(dev);
588 dev_set_drvdata(dev, NULL);
589 if (dev->pm_domain && dev->pm_domain->dismiss)
590 dev->pm_domain->dismiss(dev);
591 pm_runtime_reinit(dev);
596 pinctrl_init_done(dev);
598 if (dev->pm_domain && dev->pm_domain->sync)
599 dev->pm_domain->sync(dev);
603 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
604 drv->bus->name, __func__, dev_name(dev), drv->name);
607 dev_sysfs_state_synced_failed:
608 device_remove_groups(dev, drv->dev_groups);
610 if (dev->bus->remove)
611 dev->bus->remove(dev);
612 else if (drv->remove)
615 kfree(dev->dma_range_map);
616 dev->dma_range_map = NULL;
618 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
619 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
621 device_links_no_driver(dev);
622 devres_release_all(dev);
623 arch_teardown_dma_ops(dev);
624 driver_sysfs_remove(dev);
626 dev_set_drvdata(dev, NULL);
627 if (dev->pm_domain && dev->pm_domain->dismiss)
628 dev->pm_domain->dismiss(dev);
629 pm_runtime_reinit(dev);
630 dev_pm_set_driver_flags(dev, 0);
634 /* Driver requested deferred probing */
635 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
636 driver_deferred_probe_add_trigger(dev, local_trigger_count);
640 pr_debug("%s: probe of %s rejects match %d\n",
641 drv->name, dev_name(dev), ret);
644 /* driver matched but the probe failed */
645 pr_warn("%s: probe of %s failed with error %d\n",
646 drv->name, dev_name(dev), ret);
649 * Ignore errors returned by ->probe so that the next driver can try
654 atomic_dec(&probe_count);
655 wake_up_all(&probe_waitqueue);
660 * For initcall_debug, show the driver probe time.
662 static int really_probe_debug(struct device *dev, struct device_driver *drv)
664 ktime_t calltime, rettime;
667 calltime = ktime_get();
668 ret = really_probe(dev, drv);
669 rettime = ktime_get();
670 pr_debug("probe of %s returned %d after %lld usecs\n",
671 dev_name(dev), ret, ktime_us_delta(rettime, calltime));
677 * Determine if the probe sequence is finished or not.
679 * Should somehow figure out how to use a semaphore, not an atomic variable...
681 int driver_probe_done(void)
683 int local_probe_count = atomic_read(&probe_count);
685 pr_debug("%s: probe_count = %d\n", __func__, local_probe_count);
686 if (local_probe_count)
692 * wait_for_device_probe
693 * Wait for device probing to be completed.
695 void wait_for_device_probe(void)
697 /* wait for probe timeout */
698 wait_event(probe_timeout_waitqueue, !driver_deferred_probe_timeout);
700 /* wait for the deferred probe workqueue to finish */
701 flush_work(&deferred_probe_work);
703 /* wait for the known devices to complete their probing */
704 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
705 async_synchronize_full();
707 EXPORT_SYMBOL_GPL(wait_for_device_probe);
710 * driver_probe_device - attempt to bind device & driver together
711 * @drv: driver to bind a device to
712 * @dev: device to try to bind to the driver
714 * This function returns -ENODEV if the device is not registered,
715 * 1 if the device is bound successfully and 0 otherwise.
717 * This function must be called with @dev lock held. When called for a
718 * USB interface, @dev->parent lock must be held as well.
720 * If the device has a parent, runtime-resume the parent before driver probing.
722 static int driver_probe_device(struct device_driver *drv, struct device *dev)
726 if (!device_is_registered(dev))
729 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
730 drv->bus->name, __func__, dev_name(dev), drv->name);
732 pm_runtime_get_suppliers(dev);
734 pm_runtime_get_sync(dev->parent);
736 pm_runtime_barrier(dev);
738 ret = really_probe_debug(dev, drv);
740 ret = really_probe(dev, drv);
741 pm_request_idle(dev);
744 pm_runtime_put(dev->parent);
746 pm_runtime_put_suppliers(dev);
750 static inline bool cmdline_requested_async_probing(const char *drv_name)
752 return parse_option_str(async_probe_drv_names, drv_name);
755 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
756 static int __init save_async_options(char *buf)
758 if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
759 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
761 strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
764 __setup("driver_async_probe=", save_async_options);
766 bool driver_allows_async_probing(struct device_driver *drv)
768 switch (drv->probe_type) {
769 case PROBE_PREFER_ASYNCHRONOUS:
772 case PROBE_FORCE_SYNCHRONOUS:
776 if (cmdline_requested_async_probing(drv->name))
779 if (module_requested_async_probing(drv->owner))
786 struct device_attach_data {
790 * Indicates whether we are are considering asynchronous probing or
791 * not. Only initial binding after device or driver registration
792 * (including deferral processing) may be done asynchronously, the
793 * rest is always synchronous, as we expect it is being done by
794 * request from userspace.
799 * Indicates if we are binding synchronous or asynchronous drivers.
800 * When asynchronous probing is enabled we'll execute 2 passes
801 * over drivers: first pass doing synchronous probing and second
802 * doing asynchronous probing (if synchronous did not succeed -
803 * most likely because there was no driver requiring synchronous
804 * probing - and we found asynchronous driver during first pass).
805 * The 2 passes are done because we can't shoot asynchronous
806 * probe for given device and driver from bus_for_each_drv() since
807 * driver pointer is not guaranteed to stay valid once
808 * bus_for_each_drv() iterates to the next driver on the bus.
813 * We'll set have_async to 'true' if, while scanning for matching
814 * driver, we'll encounter one that requests asynchronous probing.
819 static int __device_attach_driver(struct device_driver *drv, void *_data)
821 struct device_attach_data *data = _data;
822 struct device *dev = data->dev;
826 ret = driver_match_device(drv, dev);
830 } else if (ret == -EPROBE_DEFER) {
831 dev_dbg(dev, "Device match requests probe deferral\n");
832 driver_deferred_probe_add(dev);
833 } else if (ret < 0) {
834 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
836 } /* ret > 0 means positive match */
838 async_allowed = driver_allows_async_probing(drv);
841 data->have_async = true;
843 if (data->check_async && async_allowed != data->want_async)
846 return driver_probe_device(drv, dev);
849 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
851 struct device *dev = _dev;
852 struct device_attach_data data = {
861 * Check if device has already been removed or claimed. This may
862 * happen with driver loading, device discovery/registration,
863 * and deferred probe processing happens all at once with
866 if (dev->p->dead || dev->driver)
870 pm_runtime_get_sync(dev->parent);
872 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
873 dev_dbg(dev, "async probe completed\n");
875 pm_request_idle(dev);
878 pm_runtime_put(dev->parent);
885 static int __device_attach(struct device *dev, bool allow_async)
892 } else if (dev->driver) {
893 if (device_is_bound(dev)) {
897 ret = device_bind_driver(dev);
905 struct device_attach_data data = {
907 .check_async = allow_async,
912 pm_runtime_get_sync(dev->parent);
914 ret = bus_for_each_drv(dev->bus, NULL, &data,
915 __device_attach_driver);
916 if (!ret && allow_async && data.have_async) {
918 * If we could not find appropriate driver
919 * synchronously and we are allowed to do
920 * async probes and there are drivers that
921 * want to probe asynchronously, we'll
924 dev_dbg(dev, "scheduling asynchronous probe\n");
926 async_schedule_dev(__device_attach_async_helper, dev);
928 pm_request_idle(dev);
932 pm_runtime_put(dev->parent);
940 * device_attach - try to attach device to a driver.
943 * Walk the list of drivers that the bus has and call
944 * driver_probe_device() for each pair. If a compatible
945 * pair is found, break out and return.
947 * Returns 1 if the device was bound to a driver;
948 * 0 if no matching driver was found;
949 * -ENODEV if the device is not registered.
951 * When called for a USB interface, @dev->parent lock must be held.
953 int device_attach(struct device *dev)
955 return __device_attach(dev, false);
957 EXPORT_SYMBOL_GPL(device_attach);
959 void device_initial_probe(struct device *dev)
961 __device_attach(dev, true);
965 * __device_driver_lock - acquire locks needed to manipulate dev->drv
966 * @dev: Device we will update driver info for
967 * @parent: Parent device. Needed if the bus requires parent lock
969 * This function will take the required locks for manipulating dev->drv.
970 * Normally this will just be the @dev lock, but when called for a USB
971 * interface, @parent lock will be held as well.
973 static void __device_driver_lock(struct device *dev, struct device *parent)
975 if (parent && dev->bus->need_parent_lock)
981 * __device_driver_unlock - release locks needed to manipulate dev->drv
982 * @dev: Device we will update driver info for
983 * @parent: Parent device. Needed if the bus requires parent lock
985 * This function will release the required locks for manipulating dev->drv.
986 * Normally this will just be the the @dev lock, but when called for a
987 * USB interface, @parent lock will be released as well.
989 static void __device_driver_unlock(struct device *dev, struct device *parent)
992 if (parent && dev->bus->need_parent_lock)
993 device_unlock(parent);
997 * device_driver_attach - attach a specific driver to a specific device
998 * @drv: Driver to attach
999 * @dev: Device to attach it to
1001 * Manually attach driver to a device. Will acquire both @dev lock and
1002 * @dev->parent lock if needed.
1004 int device_driver_attach(struct device_driver *drv, struct device *dev)
1008 __device_driver_lock(dev, dev->parent);
1011 * If device has been removed or someone has already successfully
1012 * bound a driver before us just skip the driver probe call.
1014 if (!dev->p->dead && !dev->driver)
1015 ret = driver_probe_device(drv, dev);
1017 __device_driver_unlock(dev, dev->parent);
1022 static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
1024 struct device *dev = _dev;
1025 struct device_driver *drv;
1028 __device_driver_lock(dev, dev->parent);
1030 drv = dev->p->async_driver;
1033 * If device has been removed or someone has already successfully
1034 * bound a driver before us just skip the driver probe call.
1036 if (!dev->p->dead && !dev->driver)
1037 ret = driver_probe_device(drv, dev);
1039 __device_driver_unlock(dev, dev->parent);
1041 dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);
1046 static int __driver_attach(struct device *dev, void *data)
1048 struct device_driver *drv = data;
1052 * Lock device and try to bind to it. We drop the error
1053 * here and always return 0, because we need to keep trying
1054 * to bind to devices and some drivers will return an error
1055 * simply if it didn't support the device.
1057 * driver_probe_device() will spit a warning if there
1061 ret = driver_match_device(drv, dev);
1065 } else if (ret == -EPROBE_DEFER) {
1066 dev_dbg(dev, "Device match requests probe deferral\n");
1067 driver_deferred_probe_add(dev);
1068 } else if (ret < 0) {
1069 dev_dbg(dev, "Bus failed to match device: %d\n", ret);
1071 } /* ret > 0 means positive match */
1073 if (driver_allows_async_probing(drv)) {
1075 * Instead of probing the device synchronously we will
1076 * probe it asynchronously to allow for more parallelism.
1078 * We only take the device lock here in order to guarantee
1079 * that the dev->driver and async_driver fields are protected
1081 dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
1085 dev->p->async_driver = drv;
1086 async_schedule_dev(__driver_attach_async_helper, dev);
1092 device_driver_attach(drv, dev);
1098 * driver_attach - try to bind driver to devices.
1101 * Walk the list of devices that the bus has on it and try to
1102 * match the driver with each one. If driver_probe_device()
1103 * returns 0 and the @dev->driver is set, we've found a
1106 int driver_attach(struct device_driver *drv)
1108 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
1110 EXPORT_SYMBOL_GPL(driver_attach);
1113 * __device_release_driver() must be called with @dev lock held.
1114 * When called for a USB interface, @dev->parent lock must be held as well.
1116 static void __device_release_driver(struct device *dev, struct device *parent)
1118 struct device_driver *drv;
1122 pm_runtime_get_sync(dev);
1124 while (device_links_busy(dev)) {
1125 __device_driver_unlock(dev, parent);
1127 device_links_unbind_consumers(dev);
1129 __device_driver_lock(dev, parent);
1131 * A concurrent invocation of the same function might
1132 * have released the driver successfully while this one
1133 * was waiting, so check for that.
1135 if (dev->driver != drv) {
1136 pm_runtime_put(dev);
1141 driver_sysfs_remove(dev);
1144 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1145 BUS_NOTIFY_UNBIND_DRIVER,
1148 pm_runtime_put_sync(dev);
1150 device_remove_file(dev, &dev_attr_state_synced);
1151 device_remove_groups(dev, drv->dev_groups);
1153 if (dev->bus && dev->bus->remove)
1154 dev->bus->remove(dev);
1155 else if (drv->remove)
1158 device_links_driver_cleanup(dev);
1160 devres_release_all(dev);
1161 arch_teardown_dma_ops(dev);
1163 dev_set_drvdata(dev, NULL);
1164 if (dev->pm_domain && dev->pm_domain->dismiss)
1165 dev->pm_domain->dismiss(dev);
1166 pm_runtime_reinit(dev);
1167 dev_pm_set_driver_flags(dev, 0);
1169 klist_remove(&dev->p->knode_driver);
1170 device_pm_check_callbacks(dev);
1172 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
1173 BUS_NOTIFY_UNBOUND_DRIVER,
1176 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
1180 void device_release_driver_internal(struct device *dev,
1181 struct device_driver *drv,
1182 struct device *parent)
1184 __device_driver_lock(dev, parent);
1186 if (!drv || drv == dev->driver)
1187 __device_release_driver(dev, parent);
1189 __device_driver_unlock(dev, parent);
1193 * device_release_driver - manually detach device from driver.
1196 * Manually detach device from driver.
1197 * When called for a USB interface, @dev->parent lock must be held.
1199 * If this function is to be called with @dev->parent lock held, ensure that
1200 * the device's consumers are unbound in advance or that their locks can be
1201 * acquired under the @dev->parent lock.
1203 void device_release_driver(struct device *dev)
1206 * If anyone calls device_release_driver() recursively from
1207 * within their ->remove callback for the same device, they
1208 * will deadlock right here.
1210 device_release_driver_internal(dev, NULL, NULL);
1212 EXPORT_SYMBOL_GPL(device_release_driver);
1215 * device_driver_detach - detach driver from a specific device
1216 * @dev: device to detach driver from
1218 * Detach driver from device. Will acquire both @dev lock and @dev->parent
1221 void device_driver_detach(struct device *dev)
1223 device_release_driver_internal(dev, NULL, dev->parent);
1227 * driver_detach - detach driver from all devices it controls.
1230 void driver_detach(struct device_driver *drv)
1232 struct device_private *dev_prv;
1235 if (driver_allows_async_probing(drv))
1236 async_synchronize_full();
1239 spin_lock(&drv->p->klist_devices.k_lock);
1240 if (list_empty(&drv->p->klist_devices.k_list)) {
1241 spin_unlock(&drv->p->klist_devices.k_lock);
1244 dev_prv = list_last_entry(&drv->p->klist_devices.k_list,
1245 struct device_private,
1246 knode_driver.n_node);
1247 dev = dev_prv->device;
1249 spin_unlock(&drv->p->klist_devices.k_lock);
1250 device_release_driver_internal(dev, drv, dev->parent);