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-mapping.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>
32 #include "power/power.h"
35 * Deferred Probe infrastructure.
37 * Sometimes driver probe order matters, but the kernel doesn't always have
38 * dependency information which means some drivers will get probed before a
39 * resource it depends on is available. For example, an SDHCI driver may
40 * first need a GPIO line from an i2c GPIO controller before it can be
41 * initialized. If a required resource is not available yet, a driver can
42 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
44 * Deferred probe maintains two lists of devices, a pending list and an active
45 * list. A driver returning -EPROBE_DEFER causes the device to be added to the
46 * pending list. A successful driver probe will trigger moving all devices
47 * from the pending to the active list so that the workqueue will eventually
50 * The deferred_probe_mutex must be held any time the deferred_probe_*_list
51 * of the (struct device*)->p->deferred_probe pointers are manipulated
53 static DEFINE_MUTEX(deferred_probe_mutex
);
54 static LIST_HEAD(deferred_probe_pending_list
);
55 static LIST_HEAD(deferred_probe_active_list
);
56 static atomic_t deferred_trigger_count
= ATOMIC_INIT(0);
57 static struct dentry
*deferred_devices
;
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
;
72 * deferred_probe_work_func() - Retry probing devices in the active list.
74 static void deferred_probe_work_func(struct work_struct
*work
)
77 struct device_private
*private;
79 * This block processes every device in the deferred 'active' list.
80 * Each device is removed from the active list and passed to
81 * bus_probe_device() to re-attempt the probe. The loop continues
82 * until every device in the active list is removed and retried.
84 * Note: Once the device is removed from the list and the mutex is
85 * released, it is possible for the device get freed by another thread
86 * and cause a illegal pointer dereference. This code uses
87 * get/put_device() to ensure the device structure cannot disappear
88 * from under our feet.
90 mutex_lock(&deferred_probe_mutex
);
91 while (!list_empty(&deferred_probe_active_list
)) {
92 private = list_first_entry(&deferred_probe_active_list
,
93 typeof(*dev
->p
), deferred_probe
);
94 dev
= private->device
;
95 list_del_init(&private->deferred_probe
);
100 * Drop the mutex while probing each device; the probe path may
101 * manipulate the deferred list
103 mutex_unlock(&deferred_probe_mutex
);
106 * Force the device to the end of the dpm_list since
107 * the PM code assumes that the order we add things to
108 * the list is a good order for suspend but deferred
109 * probe makes that very unsafe.
111 device_pm_move_to_tail(dev
);
113 dev_dbg(dev
, "Retrying from deferred list\n");
114 bus_probe_device(dev
);
115 mutex_lock(&deferred_probe_mutex
);
119 mutex_unlock(&deferred_probe_mutex
);
121 static DECLARE_WORK(deferred_probe_work
, deferred_probe_work_func
);
123 void driver_deferred_probe_add(struct device
*dev
)
125 mutex_lock(&deferred_probe_mutex
);
126 if (list_empty(&dev
->p
->deferred_probe
)) {
127 dev_dbg(dev
, "Added to deferred list\n");
128 list_add_tail(&dev
->p
->deferred_probe
, &deferred_probe_pending_list
);
130 mutex_unlock(&deferred_probe_mutex
);
133 void driver_deferred_probe_del(struct device
*dev
)
135 mutex_lock(&deferred_probe_mutex
);
136 if (!list_empty(&dev
->p
->deferred_probe
)) {
137 dev_dbg(dev
, "Removed from deferred list\n");
138 list_del_init(&dev
->p
->deferred_probe
);
140 mutex_unlock(&deferred_probe_mutex
);
143 static bool driver_deferred_probe_enable
= false;
145 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
147 * This functions moves all devices from the pending list to the active
148 * list and schedules the deferred probe workqueue to process them. It
149 * should be called anytime a driver is successfully bound to a device.
151 * Note, there is a race condition in multi-threaded probe. In the case where
152 * more than one device is probing at the same time, it is possible for one
153 * probe to complete successfully while another is about to defer. If the second
154 * depends on the first, then it will get put on the pending list after the
155 * trigger event has already occurred and will be stuck there.
157 * The atomic 'deferred_trigger_count' is used to determine if a successful
158 * trigger has occurred in the midst of probing a driver. If the trigger count
159 * changes in the midst of a probe, then deferred processing should be triggered
162 static void driver_deferred_probe_trigger(void)
164 if (!driver_deferred_probe_enable
)
168 * A successful probe means that all the devices in the pending list
169 * should be triggered to be reprobed. Move all the deferred devices
170 * into the active list so they can be retried by the workqueue
172 mutex_lock(&deferred_probe_mutex
);
173 atomic_inc(&deferred_trigger_count
);
174 list_splice_tail_init(&deferred_probe_pending_list
,
175 &deferred_probe_active_list
);
176 mutex_unlock(&deferred_probe_mutex
);
179 * Kick the re-probe thread. It may already be scheduled, but it is
180 * safe to kick it again.
182 schedule_work(&deferred_probe_work
);
186 * device_block_probing() - Block/defer device's probes
188 * It will disable probing of devices and defer their probes instead.
190 void device_block_probing(void)
192 defer_all_probes
= true;
193 /* sync with probes to avoid races. */
194 wait_for_device_probe();
198 * device_unblock_probing() - Unblock/enable device's probes
200 * It will restore normal behavior and trigger re-probing of deferred
203 void device_unblock_probing(void)
205 defer_all_probes
= false;
206 driver_deferred_probe_trigger();
210 * deferred_devs_show() - Show the devices in the deferred probe pending list.
212 static int deferred_devs_show(struct seq_file
*s
, void *data
)
214 struct device_private
*curr
;
216 mutex_lock(&deferred_probe_mutex
);
218 list_for_each_entry(curr
, &deferred_probe_pending_list
, deferred_probe
)
219 seq_printf(s
, "%s\n", dev_name(curr
->device
));
221 mutex_unlock(&deferred_probe_mutex
);
225 DEFINE_SHOW_ATTRIBUTE(deferred_devs
);
227 static int deferred_probe_timeout
= -1;
228 static int __init
deferred_probe_timeout_setup(char *str
)
232 if (!kstrtoint(str
, 10, &timeout
))
233 deferred_probe_timeout
= timeout
;
236 __setup("deferred_probe_timeout=", deferred_probe_timeout_setup
);
239 * driver_deferred_probe_check_state() - Check deferred probe state
240 * @dev: device to check
242 * Returns -ENODEV if init is done and all built-in drivers have had a chance
243 * to probe (i.e. initcalls are done), -ETIMEDOUT if deferred probe debug
244 * timeout has expired, or -EPROBE_DEFER if none of those conditions are met.
246 * Drivers or subsystems can opt-in to calling this function instead of directly
247 * returning -EPROBE_DEFER.
249 int driver_deferred_probe_check_state(struct device
*dev
)
251 if (initcalls_done
) {
252 if (!deferred_probe_timeout
) {
253 dev_WARN(dev
, "deferred probe timeout, ignoring dependency");
256 dev_warn(dev
, "ignoring dependency for device, assuming no driver");
259 return -EPROBE_DEFER
;
262 static void deferred_probe_timeout_work_func(struct work_struct
*work
)
264 struct device_private
*private, *p
;
266 deferred_probe_timeout
= 0;
267 driver_deferred_probe_trigger();
268 flush_work(&deferred_probe_work
);
270 list_for_each_entry_safe(private, p
, &deferred_probe_pending_list
, deferred_probe
)
271 dev_info(private->device
, "deferred probe pending");
273 static DECLARE_DELAYED_WORK(deferred_probe_timeout_work
, deferred_probe_timeout_work_func
);
276 * deferred_probe_initcall() - Enable probing of deferred devices
278 * We don't want to get in the way when the bulk of drivers are getting probed.
279 * Instead, this initcall makes sure that deferred probing is delayed until
280 * late_initcall time.
282 static int deferred_probe_initcall(void)
284 deferred_devices
= debugfs_create_file("devices_deferred", 0444, NULL
,
285 NULL
, &deferred_devs_fops
);
287 driver_deferred_probe_enable
= true;
288 driver_deferred_probe_trigger();
289 /* Sort as many dependencies as possible before exiting initcalls */
290 flush_work(&deferred_probe_work
);
291 initcalls_done
= true;
294 * Trigger deferred probe again, this time we won't defer anything
297 driver_deferred_probe_trigger();
298 flush_work(&deferred_probe_work
);
300 if (deferred_probe_timeout
> 0) {
301 schedule_delayed_work(&deferred_probe_timeout_work
,
302 deferred_probe_timeout
* HZ
);
306 late_initcall(deferred_probe_initcall
);
308 static void __exit
deferred_probe_exit(void)
310 debugfs_remove_recursive(deferred_devices
);
312 __exitcall(deferred_probe_exit
);
315 * device_is_bound() - Check if device is bound to a driver
316 * @dev: device to check
318 * Returns true if passed device has already finished probing successfully
321 * This function must be called with the device lock held.
323 bool device_is_bound(struct device
*dev
)
325 return dev
->p
&& klist_node_attached(&dev
->p
->knode_driver
);
328 static void driver_bound(struct device
*dev
)
330 if (device_is_bound(dev
)) {
331 printk(KERN_WARNING
"%s: device %s already bound\n",
332 __func__
, kobject_name(&dev
->kobj
));
336 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev
->driver
->name
,
337 __func__
, dev_name(dev
));
339 klist_add_tail(&dev
->p
->knode_driver
, &dev
->driver
->p
->klist_devices
);
340 device_links_driver_bound(dev
);
342 device_pm_check_callbacks(dev
);
345 * Make sure the device is no longer in one of the deferred lists and
346 * kick off retrying all pending devices
348 driver_deferred_probe_del(dev
);
349 driver_deferred_probe_trigger();
352 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
353 BUS_NOTIFY_BOUND_DRIVER
, dev
);
355 kobject_uevent(&dev
->kobj
, KOBJ_BIND
);
358 static ssize_t
coredump_store(struct device
*dev
, struct device_attribute
*attr
,
359 const char *buf
, size_t count
)
362 dev
->driver
->coredump(dev
);
367 static DEVICE_ATTR_WO(coredump
);
369 static int driver_sysfs_add(struct device
*dev
)
374 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
375 BUS_NOTIFY_BIND_DRIVER
, dev
);
377 ret
= sysfs_create_link(&dev
->driver
->p
->kobj
, &dev
->kobj
,
378 kobject_name(&dev
->kobj
));
382 ret
= sysfs_create_link(&dev
->kobj
, &dev
->driver
->p
->kobj
,
387 if (!IS_ENABLED(CONFIG_DEV_COREDUMP
) || !dev
->driver
->coredump
||
388 !device_create_file(dev
, &dev_attr_coredump
))
391 sysfs_remove_link(&dev
->kobj
, "driver");
394 sysfs_remove_link(&dev
->driver
->p
->kobj
,
395 kobject_name(&dev
->kobj
));
401 static void driver_sysfs_remove(struct device
*dev
)
403 struct device_driver
*drv
= dev
->driver
;
407 device_remove_file(dev
, &dev_attr_coredump
);
408 sysfs_remove_link(&drv
->p
->kobj
, kobject_name(&dev
->kobj
));
409 sysfs_remove_link(&dev
->kobj
, "driver");
414 * device_bind_driver - bind a driver to one device.
417 * Allow manual attachment of a driver to a device.
418 * Caller must have already set @dev->driver.
420 * Note that this does not modify the bus reference count
421 * nor take the bus's rwsem. Please verify those are accounted
422 * for before calling this. (It is ok to call with no other effort
423 * from a driver's probe() method.)
425 * This function must be called with the device lock held.
427 int device_bind_driver(struct device
*dev
)
431 ret
= driver_sysfs_add(dev
);
435 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
436 BUS_NOTIFY_DRIVER_NOT_BOUND
, dev
);
439 EXPORT_SYMBOL_GPL(device_bind_driver
);
441 static atomic_t probe_count
= ATOMIC_INIT(0);
442 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue
);
444 static void driver_deferred_probe_add_trigger(struct device
*dev
,
445 int local_trigger_count
)
447 driver_deferred_probe_add(dev
);
448 /* Did a trigger occur while probing? Need to re-trigger if yes */
449 if (local_trigger_count
!= atomic_read(&deferred_trigger_count
))
450 driver_deferred_probe_trigger();
453 static int really_probe(struct device
*dev
, struct device_driver
*drv
)
455 int ret
= -EPROBE_DEFER
;
456 int local_trigger_count
= atomic_read(&deferred_trigger_count
);
457 bool test_remove
= IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE
) &&
458 !drv
->suppress_bind_attrs
;
460 if (defer_all_probes
) {
462 * Value of defer_all_probes can be set only by
463 * device_block_probing() which, in turn, will call
464 * wait_for_device_probe() right after that to avoid any races.
466 dev_dbg(dev
, "Driver %s force probe deferral\n", drv
->name
);
467 driver_deferred_probe_add(dev
);
471 ret
= device_links_check_suppliers(dev
);
472 if (ret
== -EPROBE_DEFER
)
473 driver_deferred_probe_add_trigger(dev
, local_trigger_count
);
477 atomic_inc(&probe_count
);
478 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
479 drv
->bus
->name
, __func__
, drv
->name
, dev_name(dev
));
480 WARN_ON(!list_empty(&dev
->devres_head
));
485 /* If using pinctrl, bind pins now before probing */
486 ret
= pinctrl_bind_pins(dev
);
488 goto pinctrl_bind_failed
;
490 if (dev
->bus
->dma_configure
) {
491 ret
= dev
->bus
->dma_configure(dev
);
496 if (driver_sysfs_add(dev
)) {
497 printk(KERN_ERR
"%s: driver_sysfs_add(%s) failed\n",
498 __func__
, dev_name(dev
));
502 if (dev
->pm_domain
&& dev
->pm_domain
->activate
) {
503 ret
= dev
->pm_domain
->activate(dev
);
508 if (dev
->bus
->probe
) {
509 ret
= dev
->bus
->probe(dev
);
512 } else if (drv
->probe
) {
513 ret
= drv
->probe(dev
);
521 if (dev
->bus
->remove
)
522 dev
->bus
->remove(dev
);
523 else if (drv
->remove
)
526 devres_release_all(dev
);
527 driver_sysfs_remove(dev
);
529 dev_set_drvdata(dev
, NULL
);
530 if (dev
->pm_domain
&& dev
->pm_domain
->dismiss
)
531 dev
->pm_domain
->dismiss(dev
);
532 pm_runtime_reinit(dev
);
537 pinctrl_init_done(dev
);
539 if (dev
->pm_domain
&& dev
->pm_domain
->sync
)
540 dev
->pm_domain
->sync(dev
);
544 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
545 drv
->bus
->name
, __func__
, dev_name(dev
), drv
->name
);
549 arch_teardown_dma_ops(dev
);
552 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
553 BUS_NOTIFY_DRIVER_NOT_BOUND
, dev
);
555 device_links_no_driver(dev
);
556 devres_release_all(dev
);
557 driver_sysfs_remove(dev
);
559 dev_set_drvdata(dev
, NULL
);
560 if (dev
->pm_domain
&& dev
->pm_domain
->dismiss
)
561 dev
->pm_domain
->dismiss(dev
);
562 pm_runtime_reinit(dev
);
563 dev_pm_set_driver_flags(dev
, 0);
567 /* Driver requested deferred probing */
568 dev_dbg(dev
, "Driver %s requests probe deferral\n", drv
->name
);
569 driver_deferred_probe_add_trigger(dev
, local_trigger_count
);
573 pr_debug("%s: probe of %s rejects match %d\n",
574 drv
->name
, dev_name(dev
), ret
);
577 /* driver matched but the probe failed */
579 "%s: probe of %s failed with error %d\n",
580 drv
->name
, dev_name(dev
), ret
);
583 * Ignore errors returned by ->probe so that the next driver can try
588 atomic_dec(&probe_count
);
589 wake_up(&probe_waitqueue
);
594 * For initcall_debug, show the driver probe time.
596 static int really_probe_debug(struct device
*dev
, struct device_driver
*drv
)
598 ktime_t calltime
, delta
, rettime
;
601 calltime
= ktime_get();
602 ret
= really_probe(dev
, drv
);
603 rettime
= ktime_get();
604 delta
= ktime_sub(rettime
, calltime
);
605 printk(KERN_DEBUG
"probe of %s returned %d after %lld usecs\n",
606 dev_name(dev
), ret
, (s64
) ktime_to_us(delta
));
612 * Determine if the probe sequence is finished or not.
614 * Should somehow figure out how to use a semaphore, not an atomic variable...
616 int driver_probe_done(void)
618 pr_debug("%s: probe_count = %d\n", __func__
,
619 atomic_read(&probe_count
));
620 if (atomic_read(&probe_count
))
626 * wait_for_device_probe
627 * Wait for device probing to be completed.
629 void wait_for_device_probe(void)
631 /* wait for the deferred probe workqueue to finish */
632 flush_work(&deferred_probe_work
);
634 /* wait for the known devices to complete their probing */
635 wait_event(probe_waitqueue
, atomic_read(&probe_count
) == 0);
636 async_synchronize_full();
638 EXPORT_SYMBOL_GPL(wait_for_device_probe
);
641 * driver_probe_device - attempt to bind device & driver together
642 * @drv: driver to bind a device to
643 * @dev: device to try to bind to the driver
645 * This function returns -ENODEV if the device is not registered,
646 * 1 if the device is bound successfully and 0 otherwise.
648 * This function must be called with @dev lock held. When called for a
649 * USB interface, @dev->parent lock must be held as well.
651 * If the device has a parent, runtime-resume the parent before driver probing.
653 int driver_probe_device(struct device_driver
*drv
, struct device
*dev
)
657 if (!device_is_registered(dev
))
660 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
661 drv
->bus
->name
, __func__
, dev_name(dev
), drv
->name
);
663 pm_runtime_get_suppliers(dev
);
665 pm_runtime_get_sync(dev
->parent
);
667 pm_runtime_barrier(dev
);
669 ret
= really_probe_debug(dev
, drv
);
671 ret
= really_probe(dev
, drv
);
672 pm_request_idle(dev
);
675 pm_runtime_put(dev
->parent
);
677 pm_runtime_put_suppliers(dev
);
681 static inline bool cmdline_requested_async_probing(const char *drv_name
)
683 return parse_option_str(async_probe_drv_names
, drv_name
);
686 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
687 static int __init
save_async_options(char *buf
)
689 if (strlen(buf
) >= ASYNC_DRV_NAMES_MAX_LEN
)
691 "Too long list of driver names for 'driver_async_probe'!\n");
693 strlcpy(async_probe_drv_names
, buf
, ASYNC_DRV_NAMES_MAX_LEN
);
696 __setup("driver_async_probe=", save_async_options
);
698 bool driver_allows_async_probing(struct device_driver
*drv
)
700 switch (drv
->probe_type
) {
701 case PROBE_PREFER_ASYNCHRONOUS
:
704 case PROBE_FORCE_SYNCHRONOUS
:
708 if (cmdline_requested_async_probing(drv
->name
))
711 if (module_requested_async_probing(drv
->owner
))
718 struct device_attach_data
{
722 * Indicates whether we are are considering asynchronous probing or
723 * not. Only initial binding after device or driver registration
724 * (including deferral processing) may be done asynchronously, the
725 * rest is always synchronous, as we expect it is being done by
726 * request from userspace.
731 * Indicates if we are binding synchronous or asynchronous drivers.
732 * When asynchronous probing is enabled we'll execute 2 passes
733 * over drivers: first pass doing synchronous probing and second
734 * doing asynchronous probing (if synchronous did not succeed -
735 * most likely because there was no driver requiring synchronous
736 * probing - and we found asynchronous driver during first pass).
737 * The 2 passes are done because we can't shoot asynchronous
738 * probe for given device and driver from bus_for_each_drv() since
739 * driver pointer is not guaranteed to stay valid once
740 * bus_for_each_drv() iterates to the next driver on the bus.
745 * We'll set have_async to 'true' if, while scanning for matching
746 * driver, we'll encounter one that requests asynchronous probing.
751 static int __device_attach_driver(struct device_driver
*drv
, void *_data
)
753 struct device_attach_data
*data
= _data
;
754 struct device
*dev
= data
->dev
;
758 ret
= driver_match_device(drv
, dev
);
762 } else if (ret
== -EPROBE_DEFER
) {
763 dev_dbg(dev
, "Device match requests probe deferral\n");
764 driver_deferred_probe_add(dev
);
765 } else if (ret
< 0) {
766 dev_dbg(dev
, "Bus failed to match device: %d", ret
);
768 } /* ret > 0 means positive match */
770 async_allowed
= driver_allows_async_probing(drv
);
773 data
->have_async
= true;
775 if (data
->check_async
&& async_allowed
!= data
->want_async
)
778 return driver_probe_device(drv
, dev
);
781 static void __device_attach_async_helper(void *_dev
, async_cookie_t cookie
)
783 struct device
*dev
= _dev
;
784 struct device_attach_data data
= {
793 * Check if device has already been removed or claimed. This may
794 * happen with driver loading, device discovery/registration,
795 * and deferred probe processing happens all at once with
798 if (dev
->p
->dead
|| dev
->driver
)
802 pm_runtime_get_sync(dev
->parent
);
804 bus_for_each_drv(dev
->bus
, NULL
, &data
, __device_attach_driver
);
805 dev_dbg(dev
, "async probe completed\n");
807 pm_request_idle(dev
);
810 pm_runtime_put(dev
->parent
);
817 static int __device_attach(struct device
*dev
, bool allow_async
)
823 if (device_is_bound(dev
)) {
827 ret
= device_bind_driver(dev
);
835 struct device_attach_data data
= {
837 .check_async
= allow_async
,
842 pm_runtime_get_sync(dev
->parent
);
844 ret
= bus_for_each_drv(dev
->bus
, NULL
, &data
,
845 __device_attach_driver
);
846 if (!ret
&& allow_async
&& data
.have_async
) {
848 * If we could not find appropriate driver
849 * synchronously and we are allowed to do
850 * async probes and there are drivers that
851 * want to probe asynchronously, we'll
854 dev_dbg(dev
, "scheduling asynchronous probe\n");
856 async_schedule_dev(__device_attach_async_helper
, dev
);
858 pm_request_idle(dev
);
862 pm_runtime_put(dev
->parent
);
870 * device_attach - try to attach device to a driver.
873 * Walk the list of drivers that the bus has and call
874 * driver_probe_device() for each pair. If a compatible
875 * pair is found, break out and return.
877 * Returns 1 if the device was bound to a driver;
878 * 0 if no matching driver was found;
879 * -ENODEV if the device is not registered.
881 * When called for a USB interface, @dev->parent lock must be held.
883 int device_attach(struct device
*dev
)
885 return __device_attach(dev
, false);
887 EXPORT_SYMBOL_GPL(device_attach
);
889 void device_initial_probe(struct device
*dev
)
891 __device_attach(dev
, true);
895 * __device_driver_lock - acquire locks needed to manipulate dev->drv
896 * @dev: Device we will update driver info for
897 * @parent: Parent device. Needed if the bus requires parent lock
899 * This function will take the required locks for manipulating dev->drv.
900 * Normally this will just be the @dev lock, but when called for a USB
901 * interface, @parent lock will be held as well.
903 static void __device_driver_lock(struct device
*dev
, struct device
*parent
)
905 if (parent
&& dev
->bus
->need_parent_lock
)
911 * __device_driver_unlock - release locks needed to manipulate dev->drv
912 * @dev: Device we will update driver info for
913 * @parent: Parent device. Needed if the bus requires parent lock
915 * This function will release the required locks for manipulating dev->drv.
916 * Normally this will just be the the @dev lock, but when called for a
917 * USB interface, @parent lock will be released as well.
919 static void __device_driver_unlock(struct device
*dev
, struct device
*parent
)
922 if (parent
&& dev
->bus
->need_parent_lock
)
923 device_unlock(parent
);
927 * device_driver_attach - attach a specific driver to a specific device
928 * @drv: Driver to attach
929 * @dev: Device to attach it to
931 * Manually attach driver to a device. Will acquire both @dev lock and
932 * @dev->parent lock if needed.
934 int device_driver_attach(struct device_driver
*drv
, struct device
*dev
)
938 __device_driver_lock(dev
, dev
->parent
);
941 * If device has been removed or someone has already successfully
942 * bound a driver before us just skip the driver probe call.
944 if (!dev
->p
->dead
&& !dev
->driver
)
945 ret
= driver_probe_device(drv
, dev
);
947 __device_driver_unlock(dev
, dev
->parent
);
952 static void __driver_attach_async_helper(void *_dev
, async_cookie_t cookie
)
954 struct device
*dev
= _dev
;
955 struct device_driver
*drv
;
958 __device_driver_lock(dev
, dev
->parent
);
960 drv
= dev
->p
->async_driver
;
963 * If device has been removed or someone has already successfully
964 * bound a driver before us just skip the driver probe call.
966 if (!dev
->p
->dead
&& !dev
->driver
)
967 ret
= driver_probe_device(drv
, dev
);
969 __device_driver_unlock(dev
, dev
->parent
);
971 dev_dbg(dev
, "driver %s async attach completed: %d\n", drv
->name
, ret
);
976 static int __driver_attach(struct device
*dev
, void *data
)
978 struct device_driver
*drv
= data
;
982 * Lock device and try to bind to it. We drop the error
983 * here and always return 0, because we need to keep trying
984 * to bind to devices and some drivers will return an error
985 * simply if it didn't support the device.
987 * driver_probe_device() will spit a warning if there
991 ret
= driver_match_device(drv
, dev
);
995 } else if (ret
== -EPROBE_DEFER
) {
996 dev_dbg(dev
, "Device match requests probe deferral\n");
997 driver_deferred_probe_add(dev
);
998 } else if (ret
< 0) {
999 dev_dbg(dev
, "Bus failed to match device: %d", ret
);
1001 } /* ret > 0 means positive match */
1003 if (driver_allows_async_probing(drv
)) {
1005 * Instead of probing the device synchronously we will
1006 * probe it asynchronously to allow for more parallelism.
1008 * We only take the device lock here in order to guarantee
1009 * that the dev->driver and async_driver fields are protected
1011 dev_dbg(dev
, "probing driver %s asynchronously\n", drv
->name
);
1015 dev
->p
->async_driver
= drv
;
1016 async_schedule_dev(__driver_attach_async_helper
, dev
);
1022 device_driver_attach(drv
, dev
);
1028 * driver_attach - try to bind driver to devices.
1031 * Walk the list of devices that the bus has on it and try to
1032 * match the driver with each one. If driver_probe_device()
1033 * returns 0 and the @dev->driver is set, we've found a
1036 int driver_attach(struct device_driver
*drv
)
1038 return bus_for_each_dev(drv
->bus
, NULL
, drv
, __driver_attach
);
1040 EXPORT_SYMBOL_GPL(driver_attach
);
1043 * __device_release_driver() must be called with @dev lock held.
1044 * When called for a USB interface, @dev->parent lock must be held as well.
1046 static void __device_release_driver(struct device
*dev
, struct device
*parent
)
1048 struct device_driver
*drv
;
1052 while (device_links_busy(dev
)) {
1053 __device_driver_unlock(dev
, parent
);
1055 device_links_unbind_consumers(dev
);
1057 __device_driver_lock(dev
, parent
);
1059 * A concurrent invocation of the same function might
1060 * have released the driver successfully while this one
1061 * was waiting, so check for that.
1063 if (dev
->driver
!= drv
)
1067 pm_runtime_get_sync(dev
);
1068 pm_runtime_clean_up_links(dev
);
1070 driver_sysfs_remove(dev
);
1073 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
1074 BUS_NOTIFY_UNBIND_DRIVER
,
1077 pm_runtime_put_sync(dev
);
1079 if (dev
->bus
&& dev
->bus
->remove
)
1080 dev
->bus
->remove(dev
);
1081 else if (drv
->remove
)
1084 device_links_driver_cleanup(dev
);
1086 devres_release_all(dev
);
1087 arch_teardown_dma_ops(dev
);
1089 dev_set_drvdata(dev
, NULL
);
1090 if (dev
->pm_domain
&& dev
->pm_domain
->dismiss
)
1091 dev
->pm_domain
->dismiss(dev
);
1092 pm_runtime_reinit(dev
);
1093 dev_pm_set_driver_flags(dev
, 0);
1095 klist_remove(&dev
->p
->knode_driver
);
1096 device_pm_check_callbacks(dev
);
1098 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
1099 BUS_NOTIFY_UNBOUND_DRIVER
,
1102 kobject_uevent(&dev
->kobj
, KOBJ_UNBIND
);
1106 void device_release_driver_internal(struct device
*dev
,
1107 struct device_driver
*drv
,
1108 struct device
*parent
)
1110 __device_driver_lock(dev
, parent
);
1112 if (!drv
|| drv
== dev
->driver
)
1113 __device_release_driver(dev
, parent
);
1115 __device_driver_unlock(dev
, parent
);
1119 * device_release_driver - manually detach device from driver.
1122 * Manually detach device from driver.
1123 * When called for a USB interface, @dev->parent lock must be held.
1125 * If this function is to be called with @dev->parent lock held, ensure that
1126 * the device's consumers are unbound in advance or that their locks can be
1127 * acquired under the @dev->parent lock.
1129 void device_release_driver(struct device
*dev
)
1132 * If anyone calls device_release_driver() recursively from
1133 * within their ->remove callback for the same device, they
1134 * will deadlock right here.
1136 device_release_driver_internal(dev
, NULL
, NULL
);
1138 EXPORT_SYMBOL_GPL(device_release_driver
);
1141 * device_driver_detach - detach driver from a specific device
1142 * @dev: device to detach driver from
1144 * Detach driver from device. Will acquire both @dev lock and @dev->parent
1147 void device_driver_detach(struct device
*dev
)
1149 device_release_driver_internal(dev
, NULL
, dev
->parent
);
1153 * driver_detach - detach driver from all devices it controls.
1156 void driver_detach(struct device_driver
*drv
)
1158 struct device_private
*dev_prv
;
1161 if (driver_allows_async_probing(drv
))
1162 async_synchronize_full();
1165 spin_lock(&drv
->p
->klist_devices
.k_lock
);
1166 if (list_empty(&drv
->p
->klist_devices
.k_list
)) {
1167 spin_unlock(&drv
->p
->klist_devices
.k_lock
);
1170 dev_prv
= list_entry(drv
->p
->klist_devices
.k_list
.prev
,
1171 struct device_private
,
1172 knode_driver
.n_node
);
1173 dev
= dev_prv
->device
;
1175 spin_unlock(&drv
->p
->klist_devices
.k_lock
);
1176 device_release_driver_internal(dev
, drv
, dev
->parent
);