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
);
287 if (ret
== -EPROBE_DEFER
) {
288 /* Driver requested deferred probing */
289 dev_info(dev
, "Driver %s requests probe deferral\n", drv
->name
);
290 driver_deferred_probe_add(dev
);
291 } else if (ret
!= -ENODEV
&& ret
!= -ENXIO
) {
292 /* driver matched but the probe failed */
294 "%s: probe of %s failed with error %d\n",
295 drv
->name
, dev_name(dev
), ret
);
297 pr_debug("%s: probe of %s rejects match %d\n",
298 drv
->name
, dev_name(dev
), ret
);
301 * Ignore errors returned by ->probe so that the next driver can try
306 atomic_dec(&probe_count
);
307 wake_up(&probe_waitqueue
);
313 * Determine if the probe sequence is finished or not.
315 * Should somehow figure out how to use a semaphore, not an atomic variable...
317 int driver_probe_done(void)
319 pr_debug("%s: probe_count = %d\n", __func__
,
320 atomic_read(&probe_count
));
321 if (atomic_read(&probe_count
))
327 * wait_for_device_probe
328 * Wait for device probing to be completed.
330 void wait_for_device_probe(void)
332 /* wait for the known devices to complete their probing */
333 wait_event(probe_waitqueue
, atomic_read(&probe_count
) == 0);
334 async_synchronize_full();
336 EXPORT_SYMBOL_GPL(wait_for_device_probe
);
339 * driver_probe_device - attempt to bind device & driver together
340 * @drv: driver to bind a device to
341 * @dev: device to try to bind to the driver
343 * This function returns -ENODEV if the device is not registered,
344 * 1 if the device is bound successfully and 0 otherwise.
346 * This function must be called with @dev lock held. When called for a
347 * USB interface, @dev->parent lock must be held as well.
349 int driver_probe_device(struct device_driver
*drv
, struct device
*dev
)
353 if (!device_is_registered(dev
))
356 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
357 drv
->bus
->name
, __func__
, dev_name(dev
), drv
->name
);
359 pm_runtime_get_noresume(dev
);
360 pm_runtime_barrier(dev
);
361 ret
= really_probe(dev
, drv
);
362 pm_runtime_put_sync(dev
);
367 static int __device_attach(struct device_driver
*drv
, void *data
)
369 struct device
*dev
= data
;
371 if (!driver_match_device(drv
, dev
))
374 return driver_probe_device(drv
, dev
);
378 * device_attach - try to attach device to a driver.
381 * Walk the list of drivers that the bus has and call
382 * driver_probe_device() for each pair. If a compatible
383 * pair is found, break out and return.
385 * Returns 1 if the device was bound to a driver;
386 * 0 if no matching driver was found;
387 * -ENODEV if the device is not registered.
389 * When called for a USB interface, @dev->parent lock must be held.
391 int device_attach(struct device
*dev
)
397 if (klist_node_attached(&dev
->p
->knode_driver
)) {
401 ret
= device_bind_driver(dev
);
409 pm_runtime_get_noresume(dev
);
410 ret
= bus_for_each_drv(dev
->bus
, NULL
, dev
, __device_attach
);
411 pm_runtime_put_sync(dev
);
417 EXPORT_SYMBOL_GPL(device_attach
);
419 static int __driver_attach(struct device
*dev
, void *data
)
421 struct device_driver
*drv
= data
;
424 * Lock device and try to bind to it. We drop the error
425 * here and always return 0, because we need to keep trying
426 * to bind to devices and some drivers will return an error
427 * simply if it didn't support the device.
429 * driver_probe_device() will spit a warning if there
433 if (!driver_match_device(drv
, dev
))
436 if (dev
->parent
) /* Needed for USB */
437 device_lock(dev
->parent
);
440 driver_probe_device(drv
, dev
);
443 device_unlock(dev
->parent
);
449 * driver_attach - try to bind driver to devices.
452 * Walk the list of devices that the bus has on it and try to
453 * match the driver with each one. If driver_probe_device()
454 * returns 0 and the @dev->driver is set, we've found a
457 int driver_attach(struct device_driver
*drv
)
459 return bus_for_each_dev(drv
->bus
, NULL
, drv
, __driver_attach
);
461 EXPORT_SYMBOL_GPL(driver_attach
);
464 * __device_release_driver() must be called with @dev lock held.
465 * When called for a USB interface, @dev->parent lock must be held as well.
467 static void __device_release_driver(struct device
*dev
)
469 struct device_driver
*drv
;
473 pm_runtime_get_sync(dev
);
475 driver_sysfs_remove(dev
);
478 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
479 BUS_NOTIFY_UNBIND_DRIVER
,
482 pm_runtime_put_sync(dev
);
484 if (dev
->bus
&& dev
->bus
->remove
)
485 dev
->bus
->remove(dev
);
486 else if (drv
->remove
)
488 devres_release_all(dev
);
490 klist_remove(&dev
->p
->knode_driver
);
492 blocking_notifier_call_chain(&dev
->bus
->p
->bus_notifier
,
493 BUS_NOTIFY_UNBOUND_DRIVER
,
500 * device_release_driver - manually detach device from driver.
503 * Manually detach device from driver.
504 * When called for a USB interface, @dev->parent lock must be held.
506 void device_release_driver(struct device
*dev
)
509 * If anyone calls device_release_driver() recursively from
510 * within their ->remove callback for the same device, they
511 * will deadlock right here.
514 __device_release_driver(dev
);
517 EXPORT_SYMBOL_GPL(device_release_driver
);
520 * driver_detach - detach driver from all devices it controls.
523 void driver_detach(struct device_driver
*drv
)
525 struct device_private
*dev_prv
;
529 spin_lock(&drv
->p
->klist_devices
.k_lock
);
530 if (list_empty(&drv
->p
->klist_devices
.k_list
)) {
531 spin_unlock(&drv
->p
->klist_devices
.k_lock
);
534 dev_prv
= list_entry(drv
->p
->klist_devices
.k_list
.prev
,
535 struct device_private
,
536 knode_driver
.n_node
);
537 dev
= dev_prv
->device
;
539 spin_unlock(&drv
->p
->klist_devices
.k_lock
);
541 if (dev
->parent
) /* Needed for USB */
542 device_lock(dev
->parent
);
544 if (dev
->driver
== drv
)
545 __device_release_driver(dev
);
548 device_unlock(dev
->parent
);
554 * These exports can't be _GPL due to .h files using this within them, and it
555 * might break something that was previously working...
557 void *dev_get_drvdata(const struct device
*dev
)
560 return dev
->p
->driver_data
;
563 EXPORT_SYMBOL(dev_get_drvdata
);
565 int dev_set_drvdata(struct device
*dev
, void *data
)
570 error
= device_private_init(dev
);
574 dev
->p
->driver_data
= data
;
577 EXPORT_SYMBOL(dev_set_drvdata
);