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
= false;
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
);
511 static int call_driver_probe(struct device
*dev
, struct device_driver
*drv
)
516 ret
= dev
->bus
->probe(dev
);
518 ret
= drv
->probe(dev
);
524 /* Driver requested deferred probing */
525 dev_dbg(dev
, "Driver %s requests probe deferral\n", drv
->name
);
529 pr_debug("%s: probe of %s rejects match %d\n",
530 drv
->name
, dev_name(dev
), ret
);
533 /* driver matched but the probe failed */
534 pr_warn("%s: probe of %s failed with error %d\n",
535 drv
->name
, dev_name(dev
), ret
);
542 static int really_probe(struct device
*dev
, struct device_driver
*drv
)
544 bool test_remove
= IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE
) &&
545 !drv
->suppress_bind_attrs
;
548 if (defer_all_probes
) {
550 * Value of defer_all_probes can be set only by
551 * device_block_probing() which, in turn, will call
552 * wait_for_device_probe() right after that to avoid any races.
554 dev_dbg(dev
, "Driver %s force probe deferral\n", drv
->name
);
555 return -EPROBE_DEFER
;
558 ret
= device_links_check_suppliers(dev
);
562 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
563 drv
->bus
->name
, __func__
, drv
->name
, dev_name(dev
));
564 if (!list_empty(&dev
->devres_head
)) {
565 dev_crit(dev
, "Resources present before probing\n");
573 /* If using pinctrl, bind pins now before probing */
574 ret
= pinctrl_bind_pins(dev
);
576 goto pinctrl_bind_failed
;
578 if (dev
->bus
->dma_configure
) {
579 ret
= dev
->bus
->dma_configure(dev
);
584 ret
= driver_sysfs_add(dev
);
586 pr_err("%s: driver_sysfs_add(%s) failed\n",
587 __func__
, dev_name(dev
));
591 if (dev
->pm_domain
&& dev
->pm_domain
->activate
) {
592 ret
= dev
->pm_domain
->activate(dev
);
597 ret
= call_driver_probe(dev
, drv
);
600 * Return probe errors as positive values so that the callers
601 * can distinguish them from other errors.
607 ret
= device_add_groups(dev
, drv
->dev_groups
);
609 dev_err(dev
, "device_add_groups() failed\n");
610 goto dev_groups_failed
;
613 if (dev_has_sync_state(dev
)) {
614 ret
= device_create_file(dev
, &dev_attr_state_synced
);
616 dev_err(dev
, "state_synced sysfs add failed\n");
617 goto dev_sysfs_state_synced_failed
;
624 device_remove_file(dev
, &dev_attr_state_synced
);
625 device_remove_groups(dev
, drv
->dev_groups
);
627 if (dev
->bus
->remove
)
628 dev
->bus
->remove(dev
);
629 else if (drv
->remove
)
632 devres_release_all(dev
);
633 arch_teardown_dma_ops(dev
);
634 kfree(dev
->dma_range_map
);
635 dev
->dma_range_map
= NULL
;
636 driver_sysfs_remove(dev
);
638 dev_set_drvdata(dev
, NULL
);
639 if (dev
->pm_domain
&& dev
->pm_domain
->dismiss
)
640 dev
->pm_domain
->dismiss(dev
);
641 pm_runtime_reinit(dev
);
646 pinctrl_init_done(dev
);
648 if (dev
->pm_domain
&& dev
->pm_domain
->sync
)
649 dev
->pm_domain
->sync(dev
);
652 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
653 drv
->bus
->name
, __func__
, dev_name(dev
), drv
->name
);
656 dev_sysfs_state_synced_failed
:
657 device_remove_groups(dev
, drv
->dev_groups
);
659 if (dev
->bus
->remove
)
660 dev
->bus
->remove(dev
);
661 else if (drv
->remove
)
665 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
666 BUS_NOTIFY_DRIVER_NOT_BOUND
, dev
);
668 device_links_no_driver(dev
);
669 devres_release_all(dev
);
670 arch_teardown_dma_ops(dev
);
671 kfree(dev
->dma_range_map
);
672 dev
->dma_range_map
= NULL
;
673 driver_sysfs_remove(dev
);
675 dev_set_drvdata(dev
, NULL
);
676 if (dev
->pm_domain
&& dev
->pm_domain
->dismiss
)
677 dev
->pm_domain
->dismiss(dev
);
678 pm_runtime_reinit(dev
);
679 dev_pm_set_driver_flags(dev
, 0);
685 * For initcall_debug, show the driver probe time.
687 static int really_probe_debug(struct device
*dev
, struct device_driver
*drv
)
689 ktime_t calltime
, rettime
;
692 calltime
= ktime_get();
693 ret
= really_probe(dev
, drv
);
694 rettime
= ktime_get();
695 pr_debug("probe of %s returned %d after %lld usecs\n",
696 dev_name(dev
), ret
, ktime_us_delta(rettime
, calltime
));
702 * Determine if the probe sequence is finished or not.
704 * Should somehow figure out how to use a semaphore, not an atomic variable...
706 int driver_probe_done(void)
708 int local_probe_count
= atomic_read(&probe_count
);
710 pr_debug("%s: probe_count = %d\n", __func__
, local_probe_count
);
711 if (local_probe_count
)
717 * wait_for_device_probe
718 * Wait for device probing to be completed.
720 void wait_for_device_probe(void)
722 /* wait for probe timeout */
723 wait_event(probe_timeout_waitqueue
, !driver_deferred_probe_timeout
);
725 /* wait for the deferred probe workqueue to finish */
726 flush_work(&deferred_probe_work
);
728 /* wait for the known devices to complete their probing */
729 wait_event(probe_waitqueue
, atomic_read(&probe_count
) == 0);
730 async_synchronize_full();
732 EXPORT_SYMBOL_GPL(wait_for_device_probe
);
734 static int __driver_probe_device(struct device_driver
*drv
, struct device
*dev
)
738 if (dev
->p
->dead
|| !device_is_registered(dev
))
743 dev
->can_match
= true;
744 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
745 drv
->bus
->name
, __func__
, dev_name(dev
), drv
->name
);
747 pm_runtime_get_suppliers(dev
);
749 pm_runtime_get_sync(dev
->parent
);
751 pm_runtime_barrier(dev
);
753 ret
= really_probe_debug(dev
, drv
);
755 ret
= really_probe(dev
, drv
);
756 pm_request_idle(dev
);
759 pm_runtime_put(dev
->parent
);
761 pm_runtime_put_suppliers(dev
);
766 * driver_probe_device - attempt to bind device & driver together
767 * @drv: driver to bind a device to
768 * @dev: device to try to bind to the driver
770 * This function returns -ENODEV if the device is not registered, -EBUSY if it
771 * already has a driver, 0 if the device is bound successfully and a positive
772 * (inverted) error code for failures from the ->probe method.
774 * This function must be called with @dev lock held. When called for a
775 * USB interface, @dev->parent lock must be held as well.
777 * If the device has a parent, runtime-resume the parent before driver probing.
779 static int driver_probe_device(struct device_driver
*drv
, struct device
*dev
)
781 int trigger_count
= atomic_read(&deferred_trigger_count
);
784 atomic_inc(&probe_count
);
785 ret
= __driver_probe_device(drv
, dev
);
786 if (ret
== -EPROBE_DEFER
|| ret
== EPROBE_DEFER
) {
787 driver_deferred_probe_add(dev
);
790 * Did a trigger occur while probing? Need to re-trigger if yes
792 if (trigger_count
!= atomic_read(&deferred_trigger_count
) &&
794 driver_deferred_probe_trigger();
796 atomic_dec(&probe_count
);
797 wake_up_all(&probe_waitqueue
);
801 static inline bool cmdline_requested_async_probing(const char *drv_name
)
803 return parse_option_str(async_probe_drv_names
, drv_name
);
806 /* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
807 static int __init
save_async_options(char *buf
)
809 if (strlen(buf
) >= ASYNC_DRV_NAMES_MAX_LEN
)
810 pr_warn("Too long list of driver names for 'driver_async_probe'!\n");
812 strlcpy(async_probe_drv_names
, buf
, ASYNC_DRV_NAMES_MAX_LEN
);
815 __setup("driver_async_probe=", save_async_options
);
817 bool driver_allows_async_probing(struct device_driver
*drv
)
819 switch (drv
->probe_type
) {
820 case PROBE_PREFER_ASYNCHRONOUS
:
823 case PROBE_FORCE_SYNCHRONOUS
:
827 if (cmdline_requested_async_probing(drv
->name
))
830 if (module_requested_async_probing(drv
->owner
))
837 struct device_attach_data
{
841 * Indicates whether we are are considering asynchronous probing or
842 * not. Only initial binding after device or driver registration
843 * (including deferral processing) may be done asynchronously, the
844 * rest is always synchronous, as we expect it is being done by
845 * request from userspace.
850 * Indicates if we are binding synchronous or asynchronous drivers.
851 * When asynchronous probing is enabled we'll execute 2 passes
852 * over drivers: first pass doing synchronous probing and second
853 * doing asynchronous probing (if synchronous did not succeed -
854 * most likely because there was no driver requiring synchronous
855 * probing - and we found asynchronous driver during first pass).
856 * The 2 passes are done because we can't shoot asynchronous
857 * probe for given device and driver from bus_for_each_drv() since
858 * driver pointer is not guaranteed to stay valid once
859 * bus_for_each_drv() iterates to the next driver on the bus.
864 * We'll set have_async to 'true' if, while scanning for matching
865 * driver, we'll encounter one that requests asynchronous probing.
870 static int __device_attach_driver(struct device_driver
*drv
, void *_data
)
872 struct device_attach_data
*data
= _data
;
873 struct device
*dev
= data
->dev
;
877 ret
= driver_match_device(drv
, dev
);
881 } else if (ret
== -EPROBE_DEFER
) {
882 dev_dbg(dev
, "Device match requests probe deferral\n");
883 dev
->can_match
= true;
884 driver_deferred_probe_add(dev
);
885 } else if (ret
< 0) {
886 dev_dbg(dev
, "Bus failed to match device: %d\n", ret
);
888 } /* ret > 0 means positive match */
890 async_allowed
= driver_allows_async_probing(drv
);
893 data
->have_async
= true;
895 if (data
->check_async
&& async_allowed
!= data
->want_async
)
899 * Ignore errors returned by ->probe so that the next driver can try
902 ret
= driver_probe_device(drv
, dev
);
908 static void __device_attach_async_helper(void *_dev
, async_cookie_t cookie
)
910 struct device
*dev
= _dev
;
911 struct device_attach_data data
= {
920 * Check if device has already been removed or claimed. This may
921 * happen with driver loading, device discovery/registration,
922 * and deferred probe processing happens all at once with
925 if (dev
->p
->dead
|| dev
->driver
)
929 pm_runtime_get_sync(dev
->parent
);
931 bus_for_each_drv(dev
->bus
, NULL
, &data
, __device_attach_driver
);
932 dev_dbg(dev
, "async probe completed\n");
934 pm_request_idle(dev
);
937 pm_runtime_put(dev
->parent
);
944 static int __device_attach(struct device
*dev
, bool allow_async
)
951 } else if (dev
->driver
) {
952 if (device_is_bound(dev
)) {
956 ret
= device_bind_driver(dev
);
964 struct device_attach_data data
= {
966 .check_async
= allow_async
,
971 pm_runtime_get_sync(dev
->parent
);
973 ret
= bus_for_each_drv(dev
->bus
, NULL
, &data
,
974 __device_attach_driver
);
975 if (!ret
&& allow_async
&& data
.have_async
) {
977 * If we could not find appropriate driver
978 * synchronously and we are allowed to do
979 * async probes and there are drivers that
980 * want to probe asynchronously, we'll
983 dev_dbg(dev
, "scheduling asynchronous probe\n");
985 async_schedule_dev(__device_attach_async_helper
, dev
);
987 pm_request_idle(dev
);
991 pm_runtime_put(dev
->parent
);
999 * device_attach - try to attach device to a driver.
1002 * Walk the list of drivers that the bus has and call
1003 * driver_probe_device() for each pair. If a compatible
1004 * pair is found, break out and return.
1006 * Returns 1 if the device was bound to a driver;
1007 * 0 if no matching driver was found;
1008 * -ENODEV if the device is not registered.
1010 * When called for a USB interface, @dev->parent lock must be held.
1012 int device_attach(struct device
*dev
)
1014 return __device_attach(dev
, false);
1016 EXPORT_SYMBOL_GPL(device_attach
);
1018 void device_initial_probe(struct device
*dev
)
1020 __device_attach(dev
, true);
1024 * __device_driver_lock - acquire locks needed to manipulate dev->drv
1025 * @dev: Device we will update driver info for
1026 * @parent: Parent device. Needed if the bus requires parent lock
1028 * This function will take the required locks for manipulating dev->drv.
1029 * Normally this will just be the @dev lock, but when called for a USB
1030 * interface, @parent lock will be held as well.
1032 static void __device_driver_lock(struct device
*dev
, struct device
*parent
)
1034 if (parent
&& dev
->bus
->need_parent_lock
)
1035 device_lock(parent
);
1040 * __device_driver_unlock - release locks needed to manipulate dev->drv
1041 * @dev: Device we will update driver info for
1042 * @parent: Parent device. Needed if the bus requires parent lock
1044 * This function will release the required locks for manipulating dev->drv.
1045 * Normally this will just be the the @dev lock, but when called for a
1046 * USB interface, @parent lock will be released as well.
1048 static void __device_driver_unlock(struct device
*dev
, struct device
*parent
)
1051 if (parent
&& dev
->bus
->need_parent_lock
)
1052 device_unlock(parent
);
1056 * device_driver_attach - attach a specific driver to a specific device
1057 * @drv: Driver to attach
1058 * @dev: Device to attach it to
1060 * Manually attach driver to a device. Will acquire both @dev lock and
1061 * @dev->parent lock if needed. Returns 0 on success, -ERR on failure.
1063 int device_driver_attach(struct device_driver
*drv
, struct device
*dev
)
1067 __device_driver_lock(dev
, dev
->parent
);
1068 ret
= __driver_probe_device(drv
, dev
);
1069 __device_driver_unlock(dev
, dev
->parent
);
1071 /* also return probe errors as normal negative errnos */
1074 if (ret
== -EPROBE_DEFER
)
1078 EXPORT_SYMBOL_GPL(device_driver_attach
);
1080 static void __driver_attach_async_helper(void *_dev
, async_cookie_t cookie
)
1082 struct device
*dev
= _dev
;
1083 struct device_driver
*drv
;
1086 __device_driver_lock(dev
, dev
->parent
);
1087 drv
= dev
->p
->async_driver
;
1088 ret
= driver_probe_device(drv
, dev
);
1089 __device_driver_unlock(dev
, dev
->parent
);
1091 dev_dbg(dev
, "driver %s async attach completed: %d\n", drv
->name
, ret
);
1096 static int __driver_attach(struct device
*dev
, void *data
)
1098 struct device_driver
*drv
= data
;
1102 * Lock device and try to bind to it. We drop the error
1103 * here and always return 0, because we need to keep trying
1104 * to bind to devices and some drivers will return an error
1105 * simply if it didn't support the device.
1107 * driver_probe_device() will spit a warning if there
1111 ret
= driver_match_device(drv
, dev
);
1115 } else if (ret
== -EPROBE_DEFER
) {
1116 dev_dbg(dev
, "Device match requests probe deferral\n");
1117 dev
->can_match
= true;
1118 driver_deferred_probe_add(dev
);
1119 } else if (ret
< 0) {
1120 dev_dbg(dev
, "Bus failed to match device: %d\n", ret
);
1122 } /* ret > 0 means positive match */
1124 if (driver_allows_async_probing(drv
)) {
1126 * Instead of probing the device synchronously we will
1127 * probe it asynchronously to allow for more parallelism.
1129 * We only take the device lock here in order to guarantee
1130 * that the dev->driver and async_driver fields are protected
1132 dev_dbg(dev
, "probing driver %s asynchronously\n", drv
->name
);
1136 dev
->p
->async_driver
= drv
;
1137 async_schedule_dev(__driver_attach_async_helper
, dev
);
1143 __device_driver_lock(dev
, dev
->parent
);
1144 driver_probe_device(drv
, dev
);
1145 __device_driver_unlock(dev
, dev
->parent
);
1151 * driver_attach - try to bind driver to devices.
1154 * Walk the list of devices that the bus has on it and try to
1155 * match the driver with each one. If driver_probe_device()
1156 * returns 0 and the @dev->driver is set, we've found a
1159 int driver_attach(struct device_driver
*drv
)
1161 return bus_for_each_dev(drv
->bus
, NULL
, drv
, __driver_attach
);
1163 EXPORT_SYMBOL_GPL(driver_attach
);
1166 * __device_release_driver() must be called with @dev lock held.
1167 * When called for a USB interface, @dev->parent lock must be held as well.
1169 static void __device_release_driver(struct device
*dev
, struct device
*parent
)
1171 struct device_driver
*drv
;
1175 pm_runtime_get_sync(dev
);
1177 while (device_links_busy(dev
)) {
1178 __device_driver_unlock(dev
, parent
);
1180 device_links_unbind_consumers(dev
);
1182 __device_driver_lock(dev
, parent
);
1184 * A concurrent invocation of the same function might
1185 * have released the driver successfully while this one
1186 * was waiting, so check for that.
1188 if (dev
->driver
!= drv
) {
1189 pm_runtime_put(dev
);
1194 driver_sysfs_remove(dev
);
1197 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
1198 BUS_NOTIFY_UNBIND_DRIVER
,
1201 pm_runtime_put_sync(dev
);
1203 device_remove_file(dev
, &dev_attr_state_synced
);
1204 device_remove_groups(dev
, drv
->dev_groups
);
1206 if (dev
->bus
&& dev
->bus
->remove
)
1207 dev
->bus
->remove(dev
);
1208 else if (drv
->remove
)
1211 device_links_driver_cleanup(dev
);
1213 devres_release_all(dev
);
1214 arch_teardown_dma_ops(dev
);
1215 kfree(dev
->dma_range_map
);
1216 dev
->dma_range_map
= NULL
;
1218 dev_set_drvdata(dev
, NULL
);
1219 if (dev
->pm_domain
&& dev
->pm_domain
->dismiss
)
1220 dev
->pm_domain
->dismiss(dev
);
1221 pm_runtime_reinit(dev
);
1222 dev_pm_set_driver_flags(dev
, 0);
1224 klist_remove(&dev
->p
->knode_driver
);
1225 device_pm_check_callbacks(dev
);
1227 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
1228 BUS_NOTIFY_UNBOUND_DRIVER
,
1231 kobject_uevent(&dev
->kobj
, KOBJ_UNBIND
);
1235 void device_release_driver_internal(struct device
*dev
,
1236 struct device_driver
*drv
,
1237 struct device
*parent
)
1239 __device_driver_lock(dev
, parent
);
1241 if (!drv
|| drv
== dev
->driver
)
1242 __device_release_driver(dev
, parent
);
1244 __device_driver_unlock(dev
, parent
);
1248 * device_release_driver - manually detach device from driver.
1251 * Manually detach device from driver.
1252 * When called for a USB interface, @dev->parent lock must be held.
1254 * If this function is to be called with @dev->parent lock held, ensure that
1255 * the device's consumers are unbound in advance or that their locks can be
1256 * acquired under the @dev->parent lock.
1258 void device_release_driver(struct device
*dev
)
1261 * If anyone calls device_release_driver() recursively from
1262 * within their ->remove callback for the same device, they
1263 * will deadlock right here.
1265 device_release_driver_internal(dev
, NULL
, NULL
);
1267 EXPORT_SYMBOL_GPL(device_release_driver
);
1270 * device_driver_detach - detach driver from a specific device
1271 * @dev: device to detach driver from
1273 * Detach driver from device. Will acquire both @dev lock and @dev->parent
1276 void device_driver_detach(struct device
*dev
)
1278 device_release_driver_internal(dev
, NULL
, dev
->parent
);
1282 * driver_detach - detach driver from all devices it controls.
1285 void driver_detach(struct device_driver
*drv
)
1287 struct device_private
*dev_prv
;
1290 if (driver_allows_async_probing(drv
))
1291 async_synchronize_full();
1294 spin_lock(&drv
->p
->klist_devices
.k_lock
);
1295 if (list_empty(&drv
->p
->klist_devices
.k_list
)) {
1296 spin_unlock(&drv
->p
->klist_devices
.k_lock
);
1299 dev_prv
= list_last_entry(&drv
->p
->klist_devices
.k_list
,
1300 struct device_private
,
1301 knode_driver
.n_node
);
1302 dev
= dev_prv
->device
;
1304 spin_unlock(&drv
->p
->klist_devices
.k_lock
);
1305 device_release_driver_internal(dev
, drv
, dev
->parent
);