2 * drivers/base/dd.c - The core device/driver interactions.
4 * This file contains the (sometimes tricky) code that controls the
5 * interactions between devices and drivers, which primarily includes
6 * driver binding and unbinding.
8 * All of this code used to exist in drivers/base/bus.c, but was
9 * relocated to here in the name of compartmentalization (since it wasn't
10 * strictly code just for the 'struct bus_type'.
12 * Copyright (c) 2002-5 Patrick Mochel
13 * Copyright (c) 2002-3 Open Source Development Labs
14 * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
15 * Copyright (c) 2007-2009 Novell Inc.
17 * This file is released under the GPLv2
20 #include <linux/device.h>
21 #include <linux/delay.h>
22 #include <linux/module.h>
23 #include <linux/kthread.h>
24 #include <linux/wait.h>
25 #include <linux/async.h>
26 #include <linux/pm_runtime.h>
29 #include "power/power.h"
32 * Deferred Probe infrastructure.
34 * Sometimes driver probe order matters, but the kernel doesn't always have
35 * dependency information which means some drivers will get probed before a
36 * resource it depends on is available. For example, an SDHCI driver may
37 * first need a GPIO line from an i2c GPIO controller before it can be
38 * initialized. If a required resource is not available yet, a driver can
39 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
41 * Deferred probe maintains two lists of devices, a pending list and an active
42 * list. A driver returning -EPROBE_DEFER causes the device to be added to the
43 * pending list. A successful driver probe will trigger moving all devices
44 * from the pending to the active list so that the workqueue will eventually
47 * The deferred_probe_mutex must be held any time the deferred_probe_*_list
48 * of the (struct device*)->p->deferred_probe pointers are manipulated
50 static DEFINE_MUTEX(deferred_probe_mutex
);
51 static LIST_HEAD(deferred_probe_pending_list
);
52 static LIST_HEAD(deferred_probe_active_list
);
53 static struct workqueue_struct
*deferred_wq
;
56 * deferred_probe_work_func() - Retry probing devices in the active list.
58 static void deferred_probe_work_func(struct work_struct
*work
)
61 struct device_private
*private;
63 * This block processes every device in the deferred 'active' list.
64 * Each device is removed from the active list and passed to
65 * bus_probe_device() to re-attempt the probe. The loop continues
66 * until every device in the active list is removed and retried.
68 * Note: Once the device is removed from the list and the mutex is
69 * released, it is possible for the device get freed by another thread
70 * and cause a illegal pointer dereference. This code uses
71 * get/put_device() to ensure the device structure cannot disappear
72 * from under our feet.
74 mutex_lock(&deferred_probe_mutex
);
75 while (!list_empty(&deferred_probe_active_list
)) {
76 private = list_first_entry(&deferred_probe_active_list
,
77 typeof(*dev
->p
), deferred_probe
);
78 dev
= private->device
;
79 list_del_init(&private->deferred_probe
);
84 * Drop the mutex while probing each device; the probe path may
85 * manipulate the deferred list
87 mutex_unlock(&deferred_probe_mutex
);
88 dev_dbg(dev
, "Retrying from deferred list\n");
89 bus_probe_device(dev
);
90 mutex_lock(&deferred_probe_mutex
);
94 mutex_unlock(&deferred_probe_mutex
);
96 static DECLARE_WORK(deferred_probe_work
, deferred_probe_work_func
);
98 static void driver_deferred_probe_add(struct device
*dev
)
100 mutex_lock(&deferred_probe_mutex
);
101 if (list_empty(&dev
->p
->deferred_probe
)) {
102 dev_dbg(dev
, "Added to deferred list\n");
103 list_add(&dev
->p
->deferred_probe
, &deferred_probe_pending_list
);
105 mutex_unlock(&deferred_probe_mutex
);
108 void driver_deferred_probe_del(struct device
*dev
)
110 mutex_lock(&deferred_probe_mutex
);
111 if (!list_empty(&dev
->p
->deferred_probe
)) {
112 dev_dbg(dev
, "Removed from deferred list\n");
113 list_del_init(&dev
->p
->deferred_probe
);
115 mutex_unlock(&deferred_probe_mutex
);
118 static bool driver_deferred_probe_enable
= false;
120 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
122 * This functions moves all devices from the pending list to the active
123 * list and schedules the deferred probe workqueue to process them. It
124 * should be called anytime a driver is successfully bound to a device.
126 static void driver_deferred_probe_trigger(void)
128 if (!driver_deferred_probe_enable
)
132 * A successful probe means that all the devices in the pending list
133 * should be triggered to be reprobed. Move all the deferred devices
134 * into the active list so they can be retried by the workqueue
136 mutex_lock(&deferred_probe_mutex
);
137 list_splice_tail_init(&deferred_probe_pending_list
,
138 &deferred_probe_active_list
);
139 mutex_unlock(&deferred_probe_mutex
);
142 * Kick the re-probe thread. It may already be scheduled, but it is
143 * safe to kick it again.
145 queue_work(deferred_wq
, &deferred_probe_work
);
149 * deferred_probe_initcall() - Enable probing of deferred devices
151 * We don't want to get in the way when the bulk of drivers are getting probed.
152 * Instead, this initcall makes sure that deferred probing is delayed until
153 * late_initcall time.
155 static int deferred_probe_initcall(void)
157 deferred_wq
= create_singlethread_workqueue("deferwq");
158 if (WARN_ON(!deferred_wq
))
161 driver_deferred_probe_enable
= true;
162 driver_deferred_probe_trigger();
165 late_initcall(deferred_probe_initcall
);
167 static void driver_bound(struct device
*dev
)
169 if (klist_node_attached(&dev
->p
->knode_driver
)) {
170 printk(KERN_WARNING
"%s: device %s already bound\n",
171 __func__
, kobject_name(&dev
->kobj
));
175 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev_name(dev
),
176 __func__
, dev
->driver
->name
);
178 klist_add_tail(&dev
->p
->knode_driver
, &dev
->driver
->p
->klist_devices
);
181 * Make sure the device is no longer in one of the deferred lists and
182 * kick off retrying all pending devices
184 driver_deferred_probe_del(dev
);
185 driver_deferred_probe_trigger();
188 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
189 BUS_NOTIFY_BOUND_DRIVER
, dev
);
192 static int driver_sysfs_add(struct device
*dev
)
197 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
198 BUS_NOTIFY_BIND_DRIVER
, dev
);
200 ret
= sysfs_create_link(&dev
->driver
->p
->kobj
, &dev
->kobj
,
201 kobject_name(&dev
->kobj
));
203 ret
= sysfs_create_link(&dev
->kobj
, &dev
->driver
->p
->kobj
,
206 sysfs_remove_link(&dev
->driver
->p
->kobj
,
207 kobject_name(&dev
->kobj
));
212 static void driver_sysfs_remove(struct device
*dev
)
214 struct device_driver
*drv
= dev
->driver
;
217 sysfs_remove_link(&drv
->p
->kobj
, kobject_name(&dev
->kobj
));
218 sysfs_remove_link(&dev
->kobj
, "driver");
223 * device_bind_driver - bind a driver to one device.
226 * Allow manual attachment of a driver to a device.
227 * Caller must have already set @dev->driver.
229 * Note that this does not modify the bus reference count
230 * nor take the bus's rwsem. Please verify those are accounted
231 * for before calling this. (It is ok to call with no other effort
232 * from a driver's probe() method.)
234 * This function must be called with the device lock held.
236 int device_bind_driver(struct device
*dev
)
240 ret
= driver_sysfs_add(dev
);
245 EXPORT_SYMBOL_GPL(device_bind_driver
);
247 static atomic_t probe_count
= ATOMIC_INIT(0);
248 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue
);
250 static int really_probe(struct device
*dev
, struct device_driver
*drv
)
254 atomic_inc(&probe_count
);
255 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
256 drv
->bus
->name
, __func__
, drv
->name
, dev_name(dev
));
257 WARN_ON(!list_empty(&dev
->devres_head
));
260 if (driver_sysfs_add(dev
)) {
261 printk(KERN_ERR
"%s: driver_sysfs_add(%s) failed\n",
262 __func__
, dev_name(dev
));
266 if (dev
->bus
->probe
) {
267 ret
= dev
->bus
->probe(dev
);
270 } else if (drv
->probe
) {
271 ret
= drv
->probe(dev
);
278 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
279 drv
->bus
->name
, __func__
, dev_name(dev
), drv
->name
);
283 devres_release_all(dev
);
284 driver_sysfs_remove(dev
);
286 dev_set_drvdata(dev
, NULL
);
288 if (ret
== -EPROBE_DEFER
) {
289 /* Driver requested deferred probing */
290 dev_info(dev
, "Driver %s requests probe deferral\n", drv
->name
);
291 driver_deferred_probe_add(dev
);
292 } else if (ret
!= -ENODEV
&& ret
!= -ENXIO
) {
293 /* driver matched but the probe failed */
295 "%s: probe of %s failed with error %d\n",
296 drv
->name
, dev_name(dev
), ret
);
298 pr_debug("%s: probe of %s rejects match %d\n",
299 drv
->name
, dev_name(dev
), ret
);
302 * Ignore errors returned by ->probe so that the next driver can try
307 atomic_dec(&probe_count
);
308 wake_up(&probe_waitqueue
);
314 * Determine if the probe sequence is finished or not.
316 * Should somehow figure out how to use a semaphore, not an atomic variable...
318 int driver_probe_done(void)
320 pr_debug("%s: probe_count = %d\n", __func__
,
321 atomic_read(&probe_count
));
322 if (atomic_read(&probe_count
))
328 * wait_for_device_probe
329 * Wait for device probing to be completed.
331 void wait_for_device_probe(void)
333 /* wait for the known devices to complete their probing */
334 wait_event(probe_waitqueue
, atomic_read(&probe_count
) == 0);
335 async_synchronize_full();
337 EXPORT_SYMBOL_GPL(wait_for_device_probe
);
340 * driver_probe_device - attempt to bind device & driver together
341 * @drv: driver to bind a device to
342 * @dev: device to try to bind to the driver
344 * This function returns -ENODEV if the device is not registered,
345 * 1 if the device is bound successfully and 0 otherwise.
347 * This function must be called with @dev lock held. When called for a
348 * USB interface, @dev->parent lock must be held as well.
350 int driver_probe_device(struct device_driver
*drv
, struct device
*dev
)
354 if (!device_is_registered(dev
))
357 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
358 drv
->bus
->name
, __func__
, dev_name(dev
), drv
->name
);
360 pm_runtime_get_noresume(dev
);
361 pm_runtime_barrier(dev
);
362 ret
= really_probe(dev
, drv
);
363 pm_runtime_put_sync(dev
);
368 static int __device_attach(struct device_driver
*drv
, void *data
)
370 struct device
*dev
= data
;
372 if (!driver_match_device(drv
, dev
))
375 return driver_probe_device(drv
, dev
);
379 * device_attach - try to attach device to a driver.
382 * Walk the list of drivers that the bus has and call
383 * driver_probe_device() for each pair. If a compatible
384 * pair is found, break out and return.
386 * Returns 1 if the device was bound to a driver;
387 * 0 if no matching driver was found;
388 * -ENODEV if the device is not registered.
390 * When called for a USB interface, @dev->parent lock must be held.
392 int device_attach(struct device
*dev
)
398 if (klist_node_attached(&dev
->p
->knode_driver
)) {
402 ret
= device_bind_driver(dev
);
410 pm_runtime_get_noresume(dev
);
411 ret
= bus_for_each_drv(dev
->bus
, NULL
, dev
, __device_attach
);
412 pm_runtime_put_sync(dev
);
418 EXPORT_SYMBOL_GPL(device_attach
);
420 static int __driver_attach(struct device
*dev
, void *data
)
422 struct device_driver
*drv
= data
;
425 * Lock device and try to bind to it. We drop the error
426 * here and always return 0, because we need to keep trying
427 * to bind to devices and some drivers will return an error
428 * simply if it didn't support the device.
430 * driver_probe_device() will spit a warning if there
434 if (!driver_match_device(drv
, dev
))
437 if (dev
->parent
) /* Needed for USB */
438 device_lock(dev
->parent
);
441 driver_probe_device(drv
, dev
);
444 device_unlock(dev
->parent
);
450 * driver_attach - try to bind driver to devices.
453 * Walk the list of devices that the bus has on it and try to
454 * match the driver with each one. If driver_probe_device()
455 * returns 0 and the @dev->driver is set, we've found a
458 int driver_attach(struct device_driver
*drv
)
460 return bus_for_each_dev(drv
->bus
, NULL
, drv
, __driver_attach
);
462 EXPORT_SYMBOL_GPL(driver_attach
);
465 * __device_release_driver() must be called with @dev lock held.
466 * When called for a USB interface, @dev->parent lock must be held as well.
468 static void __device_release_driver(struct device
*dev
)
470 struct device_driver
*drv
;
474 pm_runtime_get_sync(dev
);
476 driver_sysfs_remove(dev
);
479 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
480 BUS_NOTIFY_UNBIND_DRIVER
,
483 pm_runtime_put_sync(dev
);
485 if (dev
->bus
&& dev
->bus
->remove
)
486 dev
->bus
->remove(dev
);
487 else if (drv
->remove
)
489 devres_release_all(dev
);
491 dev_set_drvdata(dev
, NULL
);
492 klist_remove(&dev
->p
->knode_driver
);
494 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
495 BUS_NOTIFY_UNBOUND_DRIVER
,
502 * device_release_driver - manually detach device from driver.
505 * Manually detach device from driver.
506 * When called for a USB interface, @dev->parent lock must be held.
508 void device_release_driver(struct device
*dev
)
511 * If anyone calls device_release_driver() recursively from
512 * within their ->remove callback for the same device, they
513 * will deadlock right here.
516 __device_release_driver(dev
);
519 EXPORT_SYMBOL_GPL(device_release_driver
);
522 * driver_detach - detach driver from all devices it controls.
525 void driver_detach(struct device_driver
*drv
)
527 struct device_private
*dev_prv
;
531 spin_lock(&drv
->p
->klist_devices
.k_lock
);
532 if (list_empty(&drv
->p
->klist_devices
.k_list
)) {
533 spin_unlock(&drv
->p
->klist_devices
.k_lock
);
536 dev_prv
= list_entry(drv
->p
->klist_devices
.k_list
.prev
,
537 struct device_private
,
538 knode_driver
.n_node
);
539 dev
= dev_prv
->device
;
541 spin_unlock(&drv
->p
->klist_devices
.k_lock
);
543 if (dev
->parent
) /* Needed for USB */
544 device_lock(dev
->parent
);
546 if (dev
->driver
== drv
)
547 __device_release_driver(dev
);
550 device_unlock(dev
->parent
);
556 * These exports can't be _GPL due to .h files using this within them, and it
557 * might break something that was previously working...
559 void *dev_get_drvdata(const struct device
*dev
)
562 return dev
->p
->driver_data
;
565 EXPORT_SYMBOL(dev_get_drvdata
);
567 int dev_set_drvdata(struct device
*dev
, void *data
)
572 error
= device_private_init(dev
);
576 dev
->p
->driver_data
= data
;
579 EXPORT_SYMBOL(dev_set_drvdata
);