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1/*
2 * drivers/base/dd.c - The core device/driver interactions.
3 *
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.
7 *
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'.
11 *
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.
16 *
17 * This file is released under the GPLv2
18 */
19
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>
27#include <scsi/scsi_scan.h>
28
29#include "base.h"
30#include "power/power.h"
31
32/*
33 * Deferred Probe infrastructure.
34 *
35 * Sometimes driver probe order matters, but the kernel doesn't always have
36 * dependency information which means some drivers will get probed before a
37 * resource it depends on is available. For example, an SDHCI driver may
38 * first need a GPIO line from an i2c GPIO controller before it can be
39 * initialized. If a required resource is not available yet, a driver can
40 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
41 *
42 * Deferred probe maintains two lists of devices, a pending list and an active
43 * list. A driver returning -EPROBE_DEFER causes the device to be added to the
44 * pending list. A successful driver probe will trigger moving all devices
45 * from the pending to the active list so that the workqueue will eventually
46 * retry them.
47 *
48 * The deferred_probe_mutex must be held any time the deferred_probe_*_list
49 * of the (struct device*)->p->deferred_probe pointers are manipulated
50 */
51static DEFINE_MUTEX(deferred_probe_mutex);
52static LIST_HEAD(deferred_probe_pending_list);
53static LIST_HEAD(deferred_probe_active_list);
54static struct workqueue_struct *deferred_wq;
55
56/**
57 * deferred_probe_work_func() - Retry probing devices in the active list.
58 */
59static void deferred_probe_work_func(struct work_struct *work)
60{
61 struct device *dev;
62 struct device_private *private;
63 /*
64 * This block processes every device in the deferred 'active' list.
65 * Each device is removed from the active list and passed to
66 * bus_probe_device() to re-attempt the probe. The loop continues
67 * until every device in the active list is removed and retried.
68 *
69 * Note: Once the device is removed from the list and the mutex is
70 * released, it is possible for the device get freed by another thread
71 * and cause a illegal pointer dereference. This code uses
72 * get/put_device() to ensure the device structure cannot disappear
73 * from under our feet.
74 */
75 mutex_lock(&deferred_probe_mutex);
76 while (!list_empty(&deferred_probe_active_list)) {
77 private = list_first_entry(&deferred_probe_active_list,
78 typeof(*dev->p), deferred_probe);
79 dev = private->device;
80 list_del_init(&private->deferred_probe);
81
82 get_device(dev);
83
84 /*
85 * Drop the mutex while probing each device; the probe path may
86 * manipulate the deferred list
87 */
88 mutex_unlock(&deferred_probe_mutex);
89 dev_dbg(dev, "Retrying from deferred list\n");
90 bus_probe_device(dev);
91 mutex_lock(&deferred_probe_mutex);
92
93 put_device(dev);
94 }
95 mutex_unlock(&deferred_probe_mutex);
96}
97static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
98
99static void driver_deferred_probe_add(struct device *dev)
100{
101 mutex_lock(&deferred_probe_mutex);
102 if (list_empty(&dev->p->deferred_probe)) {
103 dev_dbg(dev, "Added to deferred list\n");
104 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
105 }
106 mutex_unlock(&deferred_probe_mutex);
107}
108
109void driver_deferred_probe_del(struct device *dev)
110{
111 mutex_lock(&deferred_probe_mutex);
112 if (!list_empty(&dev->p->deferred_probe)) {
113 dev_dbg(dev, "Removed from deferred list\n");
114 list_del_init(&dev->p->deferred_probe);
115 }
116 mutex_unlock(&deferred_probe_mutex);
117}
118
119static bool driver_deferred_probe_enable = false;
120/**
121 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
122 *
123 * This functions moves all devices from the pending list to the active
124 * list and schedules the deferred probe workqueue to process them. It
125 * should be called anytime a driver is successfully bound to a device.
126 */
127static void driver_deferred_probe_trigger(void)
128{
129 if (!driver_deferred_probe_enable)
130 return;
131
132 /*
133 * A successful probe means that all the devices in the pending list
134 * should be triggered to be reprobed. Move all the deferred devices
135 * into the active list so they can be retried by the workqueue
136 */
137 mutex_lock(&deferred_probe_mutex);
138 list_splice_tail_init(&deferred_probe_pending_list,
139 &deferred_probe_active_list);
140 mutex_unlock(&deferred_probe_mutex);
141
142 /*
143 * Kick the re-probe thread. It may already be scheduled, but it is
144 * safe to kick it again.
145 */
146 queue_work(deferred_wq, &deferred_probe_work);
147}
148
149/**
150 * deferred_probe_initcall() - Enable probing of deferred devices
151 *
152 * We don't want to get in the way when the bulk of drivers are getting probed.
153 * Instead, this initcall makes sure that deferred probing is delayed until
154 * late_initcall time.
155 */
156static int deferred_probe_initcall(void)
157{
158 deferred_wq = create_singlethread_workqueue("deferwq");
159 if (WARN_ON(!deferred_wq))
160 return -ENOMEM;
161
162 driver_deferred_probe_enable = true;
163 driver_deferred_probe_trigger();
164 return 0;
165}
166late_initcall(deferred_probe_initcall);
167
168static void driver_bound(struct device *dev)
169{
170 if (klist_node_attached(&dev->p->knode_driver)) {
171 printk(KERN_WARNING "%s: device %s already bound\n",
172 __func__, kobject_name(&dev->kobj));
173 return;
174 }
175
176 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev_name(dev),
177 __func__, dev->driver->name);
178
179 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
180
181 /*
182 * Make sure the device is no longer in one of the deferred lists and
183 * kick off retrying all pending devices
184 */
185 driver_deferred_probe_del(dev);
186 driver_deferred_probe_trigger();
187
188 if (dev->bus)
189 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
190 BUS_NOTIFY_BOUND_DRIVER, dev);
191}
192
193static int driver_sysfs_add(struct device *dev)
194{
195 int ret;
196
197 if (dev->bus)
198 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
199 BUS_NOTIFY_BIND_DRIVER, dev);
200
201 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
202 kobject_name(&dev->kobj));
203 if (ret == 0) {
204 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
205 "driver");
206 if (ret)
207 sysfs_remove_link(&dev->driver->p->kobj,
208 kobject_name(&dev->kobj));
209 }
210 return ret;
211}
212
213static void driver_sysfs_remove(struct device *dev)
214{
215 struct device_driver *drv = dev->driver;
216
217 if (drv) {
218 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
219 sysfs_remove_link(&dev->kobj, "driver");
220 }
221}
222
223/**
224 * device_bind_driver - bind a driver to one device.
225 * @dev: device.
226 *
227 * Allow manual attachment of a driver to a device.
228 * Caller must have already set @dev->driver.
229 *
230 * Note that this does not modify the bus reference count
231 * nor take the bus's rwsem. Please verify those are accounted
232 * for before calling this. (It is ok to call with no other effort
233 * from a driver's probe() method.)
234 *
235 * This function must be called with the device lock held.
236 */
237int device_bind_driver(struct device *dev)
238{
239 int ret;
240
241 ret = driver_sysfs_add(dev);
242 if (!ret)
243 driver_bound(dev);
244 return ret;
245}
246EXPORT_SYMBOL_GPL(device_bind_driver);
247
248static atomic_t probe_count = ATOMIC_INIT(0);
249static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
250
251static int really_probe(struct device *dev, struct device_driver *drv)
252{
253 int ret = 0;
254
255 atomic_inc(&probe_count);
256 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
257 drv->bus->name, __func__, drv->name, dev_name(dev));
258 WARN_ON(!list_empty(&dev->devres_head));
259
260 dev->driver = drv;
261 if (driver_sysfs_add(dev)) {
262 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
263 __func__, dev_name(dev));
264 goto probe_failed;
265 }
266
267 if (dev->bus->probe) {
268 ret = dev->bus->probe(dev);
269 if (ret)
270 goto probe_failed;
271 } else if (drv->probe) {
272 ret = drv->probe(dev);
273 if (ret)
274 goto probe_failed;
275 }
276
277 driver_bound(dev);
278 ret = 1;
279 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
280 drv->bus->name, __func__, dev_name(dev), drv->name);
281 goto done;
282
283probe_failed:
284 devres_release_all(dev);
285 driver_sysfs_remove(dev);
286 dev->driver = NULL;
287
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 */
294 printk(KERN_WARNING
295 "%s: probe of %s failed with error %d\n",
296 drv->name, dev_name(dev), ret);
297 } else {
298 pr_debug("%s: probe of %s rejects match %d\n",
299 drv->name, dev_name(dev), ret);
300 }
301 /*
302 * Ignore errors returned by ->probe so that the next driver can try
303 * its luck.
304 */
305 ret = 0;
306done:
307 atomic_dec(&probe_count);
308 wake_up(&probe_waitqueue);
309 return ret;
310}
311
312/**
313 * driver_probe_done
314 * Determine if the probe sequence is finished or not.
315 *
316 * Should somehow figure out how to use a semaphore, not an atomic variable...
317 */
318int driver_probe_done(void)
319{
320 pr_debug("%s: probe_count = %d\n", __func__,
321 atomic_read(&probe_count));
322 if (atomic_read(&probe_count))
323 return -EBUSY;
324 return 0;
325}
326
327/**
328 * wait_for_device_probe
329 * Wait for device probing to be completed.
330 */
331void wait_for_device_probe(void)
332{
333 /* wait for the known devices to complete their probing */
334 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
335 async_synchronize_full();
336 scsi_complete_async_scans();
337}
338EXPORT_SYMBOL_GPL(wait_for_device_probe);
339
340/**
341 * driver_probe_device - attempt to bind device & driver together
342 * @drv: driver to bind a device to
343 * @dev: device to try to bind to the driver
344 *
345 * This function returns -ENODEV if the device is not registered,
346 * 1 if the device is bound successfully and 0 otherwise.
347 *
348 * This function must be called with @dev lock held. When called for a
349 * USB interface, @dev->parent lock must be held as well.
350 */
351int driver_probe_device(struct device_driver *drv, struct device *dev)
352{
353 int ret = 0;
354
355 if (!device_is_registered(dev))
356 return -ENODEV;
357
358 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
359 drv->bus->name, __func__, dev_name(dev), drv->name);
360
361 pm_runtime_get_noresume(dev);
362 pm_runtime_barrier(dev);
363 ret = really_probe(dev, drv);
364 pm_runtime_put_sync(dev);
365
366 return ret;
367}
368
369static int __device_attach(struct device_driver *drv, void *data)
370{
371 struct device *dev = data;
372
373 if (!driver_match_device(drv, dev))
374 return 0;
375
376 return driver_probe_device(drv, dev);
377}
378
379/**
380 * device_attach - try to attach device to a driver.
381 * @dev: device.
382 *
383 * Walk the list of drivers that the bus has and call
384 * driver_probe_device() for each pair. If a compatible
385 * pair is found, break out and return.
386 *
387 * Returns 1 if the device was bound to a driver;
388 * 0 if no matching driver was found;
389 * -ENODEV if the device is not registered.
390 *
391 * When called for a USB interface, @dev->parent lock must be held.
392 */
393int device_attach(struct device *dev)
394{
395 int ret = 0;
396
397 device_lock(dev);
398 if (dev->driver) {
399 if (klist_node_attached(&dev->p->knode_driver)) {
400 ret = 1;
401 goto out_unlock;
402 }
403 ret = device_bind_driver(dev);
404 if (ret == 0)
405 ret = 1;
406 else {
407 dev->driver = NULL;
408 ret = 0;
409 }
410 } else {
411 pm_runtime_get_noresume(dev);
412 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
413 pm_runtime_put_sync(dev);
414 }
415out_unlock:
416 device_unlock(dev);
417 return ret;
418}
419EXPORT_SYMBOL_GPL(device_attach);
420
421static int __driver_attach(struct device *dev, void *data)
422{
423 struct device_driver *drv = data;
424
425 /*
426 * Lock device and try to bind to it. We drop the error
427 * here and always return 0, because we need to keep trying
428 * to bind to devices and some drivers will return an error
429 * simply if it didn't support the device.
430 *
431 * driver_probe_device() will spit a warning if there
432 * is an error.
433 */
434
435 if (!driver_match_device(drv, dev))
436 return 0;
437
438 if (dev->parent) /* Needed for USB */
439 device_lock(dev->parent);
440 device_lock(dev);
441 if (!dev->driver)
442 driver_probe_device(drv, dev);
443 device_unlock(dev);
444 if (dev->parent)
445 device_unlock(dev->parent);
446
447 return 0;
448}
449
450/**
451 * driver_attach - try to bind driver to devices.
452 * @drv: driver.
453 *
454 * Walk the list of devices that the bus has on it and try to
455 * match the driver with each one. If driver_probe_device()
456 * returns 0 and the @dev->driver is set, we've found a
457 * compatible pair.
458 */
459int driver_attach(struct device_driver *drv)
460{
461 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
462}
463EXPORT_SYMBOL_GPL(driver_attach);
464
465/*
466 * __device_release_driver() must be called with @dev lock held.
467 * When called for a USB interface, @dev->parent lock must be held as well.
468 */
469static void __device_release_driver(struct device *dev)
470{
471 struct device_driver *drv;
472
473 drv = dev->driver;
474 if (drv) {
475 pm_runtime_get_sync(dev);
476
477 driver_sysfs_remove(dev);
478
479 if (dev->bus)
480 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
481 BUS_NOTIFY_UNBIND_DRIVER,
482 dev);
483
484 pm_runtime_put_sync(dev);
485
486 if (dev->bus && dev->bus->remove)
487 dev->bus->remove(dev);
488 else if (drv->remove)
489 drv->remove(dev);
490 devres_release_all(dev);
491 dev->driver = NULL;
492 klist_remove(&dev->p->knode_driver);
493 if (dev->bus)
494 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
495 BUS_NOTIFY_UNBOUND_DRIVER,
496 dev);
497
498 }
499}
500
501/**
502 * device_release_driver - manually detach device from driver.
503 * @dev: device.
504 *
505 * Manually detach device from driver.
506 * When called for a USB interface, @dev->parent lock must be held.
507 */
508void device_release_driver(struct device *dev)
509{
510 /*
511 * If anyone calls device_release_driver() recursively from
512 * within their ->remove callback for the same device, they
513 * will deadlock right here.
514 */
515 device_lock(dev);
516 __device_release_driver(dev);
517 device_unlock(dev);
518}
519EXPORT_SYMBOL_GPL(device_release_driver);
520
521/**
522 * driver_detach - detach driver from all devices it controls.
523 * @drv: driver.
524 */
525void driver_detach(struct device_driver *drv)
526{
527 struct device_private *dev_prv;
528 struct device *dev;
529
530 for (;;) {
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);
534 break;
535 }
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;
540 get_device(dev);
541 spin_unlock(&drv->p->klist_devices.k_lock);
542
543 if (dev->parent) /* Needed for USB */
544 device_lock(dev->parent);
545 device_lock(dev);
546 if (dev->driver == drv)
547 __device_release_driver(dev);
548 device_unlock(dev);
549 if (dev->parent)
550 device_unlock(dev->parent);
551 put_device(dev);
552 }
553}
554
555/*
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...
558 */
559void *dev_get_drvdata(const struct device *dev)
560{
561 if (dev && dev->p)
562 return dev->p->driver_data;
563 return NULL;
564}
565EXPORT_SYMBOL(dev_get_drvdata);
566
567int dev_set_drvdata(struct device *dev, void *data)
568{
569 int error;
570
571 if (!dev->p) {
572 error = device_private_init(dev);
573 if (error)
574 return error;
575 }
576 dev->p->driver_data = data;
577 return 0;
578}
579EXPORT_SYMBOL(dev_set_drvdata);
1/*
2 * drivers/base/dd.c - The core device/driver interactions.
3 *
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.
7 *
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'.
11 *
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.
16 *
17 * This file is released under the GPLv2
18 */
19
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>
27#include <linux/pinctrl/devinfo.h>
28
29#include "base.h"
30#include "power/power.h"
31
32/*
33 * Deferred Probe infrastructure.
34 *
35 * Sometimes driver probe order matters, but the kernel doesn't always have
36 * dependency information which means some drivers will get probed before a
37 * resource it depends on is available. For example, an SDHCI driver may
38 * first need a GPIO line from an i2c GPIO controller before it can be
39 * initialized. If a required resource is not available yet, a driver can
40 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
41 *
42 * Deferred probe maintains two lists of devices, a pending list and an active
43 * list. A driver returning -EPROBE_DEFER causes the device to be added to the
44 * pending list. A successful driver probe will trigger moving all devices
45 * from the pending to the active list so that the workqueue will eventually
46 * retry them.
47 *
48 * The deferred_probe_mutex must be held any time the deferred_probe_*_list
49 * of the (struct device*)->p->deferred_probe pointers are manipulated
50 */
51static DEFINE_MUTEX(deferred_probe_mutex);
52static LIST_HEAD(deferred_probe_pending_list);
53static LIST_HEAD(deferred_probe_active_list);
54static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
55
56/*
57 * In some cases, like suspend to RAM or hibernation, It might be reasonable
58 * to prohibit probing of devices as it could be unsafe.
59 * Once defer_all_probes is true all drivers probes will be forcibly deferred.
60 */
61static bool defer_all_probes;
62
63/*
64 * deferred_probe_work_func() - Retry probing devices in the active list.
65 */
66static void deferred_probe_work_func(struct work_struct *work)
67{
68 struct device *dev;
69 struct device_private *private;
70 /*
71 * This block processes every device in the deferred 'active' list.
72 * Each device is removed from the active list and passed to
73 * bus_probe_device() to re-attempt the probe. The loop continues
74 * until every device in the active list is removed and retried.
75 *
76 * Note: Once the device is removed from the list and the mutex is
77 * released, it is possible for the device get freed by another thread
78 * and cause a illegal pointer dereference. This code uses
79 * get/put_device() to ensure the device structure cannot disappear
80 * from under our feet.
81 */
82 mutex_lock(&deferred_probe_mutex);
83 while (!list_empty(&deferred_probe_active_list)) {
84 private = list_first_entry(&deferred_probe_active_list,
85 typeof(*dev->p), deferred_probe);
86 dev = private->device;
87 list_del_init(&private->deferred_probe);
88
89 get_device(dev);
90
91 /*
92 * Drop the mutex while probing each device; the probe path may
93 * manipulate the deferred list
94 */
95 mutex_unlock(&deferred_probe_mutex);
96
97 /*
98 * Force the device to the end of the dpm_list since
99 * the PM code assumes that the order we add things to
100 * the list is a good order for suspend but deferred
101 * probe makes that very unsafe.
102 */
103 device_pm_lock();
104 device_pm_move_last(dev);
105 device_pm_unlock();
106
107 dev_dbg(dev, "Retrying from deferred list\n");
108 bus_probe_device(dev);
109
110 mutex_lock(&deferred_probe_mutex);
111
112 put_device(dev);
113 }
114 mutex_unlock(&deferred_probe_mutex);
115}
116static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
117
118static void driver_deferred_probe_add(struct device *dev)
119{
120 mutex_lock(&deferred_probe_mutex);
121 if (list_empty(&dev->p->deferred_probe)) {
122 dev_dbg(dev, "Added to deferred list\n");
123 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
124 }
125 mutex_unlock(&deferred_probe_mutex);
126}
127
128void driver_deferred_probe_del(struct device *dev)
129{
130 mutex_lock(&deferred_probe_mutex);
131 if (!list_empty(&dev->p->deferred_probe)) {
132 dev_dbg(dev, "Removed from deferred list\n");
133 list_del_init(&dev->p->deferred_probe);
134 }
135 mutex_unlock(&deferred_probe_mutex);
136}
137
138static bool driver_deferred_probe_enable = false;
139/**
140 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
141 *
142 * This functions moves all devices from the pending list to the active
143 * list and schedules the deferred probe workqueue to process them. It
144 * should be called anytime a driver is successfully bound to a device.
145 *
146 * Note, there is a race condition in multi-threaded probe. In the case where
147 * more than one device is probing at the same time, it is possible for one
148 * probe to complete successfully while another is about to defer. If the second
149 * depends on the first, then it will get put on the pending list after the
150 * trigger event has already occurred and will be stuck there.
151 *
152 * The atomic 'deferred_trigger_count' is used to determine if a successful
153 * trigger has occurred in the midst of probing a driver. If the trigger count
154 * changes in the midst of a probe, then deferred processing should be triggered
155 * again.
156 */
157static void driver_deferred_probe_trigger(void)
158{
159 if (!driver_deferred_probe_enable)
160 return;
161
162 /*
163 * A successful probe means that all the devices in the pending list
164 * should be triggered to be reprobed. Move all the deferred devices
165 * into the active list so they can be retried by the workqueue
166 */
167 mutex_lock(&deferred_probe_mutex);
168 atomic_inc(&deferred_trigger_count);
169 list_splice_tail_init(&deferred_probe_pending_list,
170 &deferred_probe_active_list);
171 mutex_unlock(&deferred_probe_mutex);
172
173 /*
174 * Kick the re-probe thread. It may already be scheduled, but it is
175 * safe to kick it again.
176 */
177 schedule_work(&deferred_probe_work);
178}
179
180/**
181 * device_block_probing() - Block/defere device's probes
182 *
183 * It will disable probing of devices and defer their probes instead.
184 */
185void device_block_probing(void)
186{
187 defer_all_probes = true;
188 /* sync with probes to avoid races. */
189 wait_for_device_probe();
190}
191
192/**
193 * device_unblock_probing() - Unblock/enable device's probes
194 *
195 * It will restore normal behavior and trigger re-probing of deferred
196 * devices.
197 */
198void device_unblock_probing(void)
199{
200 defer_all_probes = false;
201 driver_deferred_probe_trigger();
202}
203
204/**
205 * deferred_probe_initcall() - Enable probing of deferred devices
206 *
207 * We don't want to get in the way when the bulk of drivers are getting probed.
208 * Instead, this initcall makes sure that deferred probing is delayed until
209 * late_initcall time.
210 */
211static int deferred_probe_initcall(void)
212{
213 driver_deferred_probe_enable = true;
214 driver_deferred_probe_trigger();
215 /* Sort as many dependencies as possible before exiting initcalls */
216 flush_work(&deferred_probe_work);
217 return 0;
218}
219late_initcall(deferred_probe_initcall);
220
221/**
222 * device_is_bound() - Check if device is bound to a driver
223 * @dev: device to check
224 *
225 * Returns true if passed device has already finished probing successfully
226 * against a driver.
227 *
228 * This function must be called with the device lock held.
229 */
230bool device_is_bound(struct device *dev)
231{
232 return dev->p && klist_node_attached(&dev->p->knode_driver);
233}
234
235static void driver_bound(struct device *dev)
236{
237 if (device_is_bound(dev)) {
238 printk(KERN_WARNING "%s: device %s already bound\n",
239 __func__, kobject_name(&dev->kobj));
240 return;
241 }
242
243 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
244 __func__, dev_name(dev));
245
246 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
247 device_links_driver_bound(dev);
248
249 device_pm_check_callbacks(dev);
250
251 /*
252 * Make sure the device is no longer in one of the deferred lists and
253 * kick off retrying all pending devices
254 */
255 driver_deferred_probe_del(dev);
256 driver_deferred_probe_trigger();
257
258 if (dev->bus)
259 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
260 BUS_NOTIFY_BOUND_DRIVER, dev);
261}
262
263static int driver_sysfs_add(struct device *dev)
264{
265 int ret;
266
267 if (dev->bus)
268 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
269 BUS_NOTIFY_BIND_DRIVER, dev);
270
271 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
272 kobject_name(&dev->kobj));
273 if (ret == 0) {
274 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
275 "driver");
276 if (ret)
277 sysfs_remove_link(&dev->driver->p->kobj,
278 kobject_name(&dev->kobj));
279 }
280 return ret;
281}
282
283static void driver_sysfs_remove(struct device *dev)
284{
285 struct device_driver *drv = dev->driver;
286
287 if (drv) {
288 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
289 sysfs_remove_link(&dev->kobj, "driver");
290 }
291}
292
293/**
294 * device_bind_driver - bind a driver to one device.
295 * @dev: device.
296 *
297 * Allow manual attachment of a driver to a device.
298 * Caller must have already set @dev->driver.
299 *
300 * Note that this does not modify the bus reference count
301 * nor take the bus's rwsem. Please verify those are accounted
302 * for before calling this. (It is ok to call with no other effort
303 * from a driver's probe() method.)
304 *
305 * This function must be called with the device lock held.
306 */
307int device_bind_driver(struct device *dev)
308{
309 int ret;
310
311 ret = driver_sysfs_add(dev);
312 if (!ret)
313 driver_bound(dev);
314 else if (dev->bus)
315 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
316 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
317 return ret;
318}
319EXPORT_SYMBOL_GPL(device_bind_driver);
320
321static atomic_t probe_count = ATOMIC_INIT(0);
322static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
323
324static int really_probe(struct device *dev, struct device_driver *drv)
325{
326 int ret = -EPROBE_DEFER;
327 int local_trigger_count = atomic_read(&deferred_trigger_count);
328 bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
329 !drv->suppress_bind_attrs;
330
331 if (defer_all_probes) {
332 /*
333 * Value of defer_all_probes can be set only by
334 * device_defer_all_probes_enable() which, in turn, will call
335 * wait_for_device_probe() right after that to avoid any races.
336 */
337 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
338 driver_deferred_probe_add(dev);
339 return ret;
340 }
341
342 ret = device_links_check_suppliers(dev);
343 if (ret)
344 return ret;
345
346 atomic_inc(&probe_count);
347 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
348 drv->bus->name, __func__, drv->name, dev_name(dev));
349 WARN_ON(!list_empty(&dev->devres_head));
350
351re_probe:
352 dev->driver = drv;
353
354 /* If using pinctrl, bind pins now before probing */
355 ret = pinctrl_bind_pins(dev);
356 if (ret)
357 goto pinctrl_bind_failed;
358
359 if (driver_sysfs_add(dev)) {
360 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
361 __func__, dev_name(dev));
362 goto probe_failed;
363 }
364
365 if (dev->pm_domain && dev->pm_domain->activate) {
366 ret = dev->pm_domain->activate(dev);
367 if (ret)
368 goto probe_failed;
369 }
370
371 /*
372 * Ensure devices are listed in devices_kset in correct order
373 * It's important to move Dev to the end of devices_kset before
374 * calling .probe, because it could be recursive and parent Dev
375 * should always go first
376 */
377 devices_kset_move_last(dev);
378
379 if (dev->bus->probe) {
380 ret = dev->bus->probe(dev);
381 if (ret)
382 goto probe_failed;
383 } else if (drv->probe) {
384 ret = drv->probe(dev);
385 if (ret)
386 goto probe_failed;
387 }
388
389 if (test_remove) {
390 test_remove = false;
391
392 if (dev->bus->remove)
393 dev->bus->remove(dev);
394 else if (drv->remove)
395 drv->remove(dev);
396
397 devres_release_all(dev);
398 driver_sysfs_remove(dev);
399 dev->driver = NULL;
400 dev_set_drvdata(dev, NULL);
401 if (dev->pm_domain && dev->pm_domain->dismiss)
402 dev->pm_domain->dismiss(dev);
403 pm_runtime_reinit(dev);
404
405 goto re_probe;
406 }
407
408 pinctrl_init_done(dev);
409
410 if (dev->pm_domain && dev->pm_domain->sync)
411 dev->pm_domain->sync(dev);
412
413 driver_bound(dev);
414 ret = 1;
415 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
416 drv->bus->name, __func__, dev_name(dev), drv->name);
417 goto done;
418
419probe_failed:
420 if (dev->bus)
421 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
422 BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
423pinctrl_bind_failed:
424 device_links_no_driver(dev);
425 devres_release_all(dev);
426 driver_sysfs_remove(dev);
427 dev->driver = NULL;
428 dev_set_drvdata(dev, NULL);
429 if (dev->pm_domain && dev->pm_domain->dismiss)
430 dev->pm_domain->dismiss(dev);
431 pm_runtime_reinit(dev);
432
433 switch (ret) {
434 case -EPROBE_DEFER:
435 /* Driver requested deferred probing */
436 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
437 driver_deferred_probe_add(dev);
438 /* Did a trigger occur while probing? Need to re-trigger if yes */
439 if (local_trigger_count != atomic_read(&deferred_trigger_count))
440 driver_deferred_probe_trigger();
441 break;
442 case -ENODEV:
443 case -ENXIO:
444 pr_debug("%s: probe of %s rejects match %d\n",
445 drv->name, dev_name(dev), ret);
446 break;
447 default:
448 /* driver matched but the probe failed */
449 printk(KERN_WARNING
450 "%s: probe of %s failed with error %d\n",
451 drv->name, dev_name(dev), ret);
452 }
453 /*
454 * Ignore errors returned by ->probe so that the next driver can try
455 * its luck.
456 */
457 ret = 0;
458done:
459 atomic_dec(&probe_count);
460 wake_up(&probe_waitqueue);
461 return ret;
462}
463
464/**
465 * driver_probe_done
466 * Determine if the probe sequence is finished or not.
467 *
468 * Should somehow figure out how to use a semaphore, not an atomic variable...
469 */
470int driver_probe_done(void)
471{
472 pr_debug("%s: probe_count = %d\n", __func__,
473 atomic_read(&probe_count));
474 if (atomic_read(&probe_count))
475 return -EBUSY;
476 return 0;
477}
478
479/**
480 * wait_for_device_probe
481 * Wait for device probing to be completed.
482 */
483void wait_for_device_probe(void)
484{
485 /* wait for the deferred probe workqueue to finish */
486 flush_work(&deferred_probe_work);
487
488 /* wait for the known devices to complete their probing */
489 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
490 async_synchronize_full();
491}
492EXPORT_SYMBOL_GPL(wait_for_device_probe);
493
494/**
495 * driver_probe_device - attempt to bind device & driver together
496 * @drv: driver to bind a device to
497 * @dev: device to try to bind to the driver
498 *
499 * This function returns -ENODEV if the device is not registered,
500 * 1 if the device is bound successfully and 0 otherwise.
501 *
502 * This function must be called with @dev lock held. When called for a
503 * USB interface, @dev->parent lock must be held as well.
504 *
505 * If the device has a parent, runtime-resume the parent before driver probing.
506 */
507int driver_probe_device(struct device_driver *drv, struct device *dev)
508{
509 int ret = 0;
510
511 if (!device_is_registered(dev))
512 return -ENODEV;
513
514 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
515 drv->bus->name, __func__, dev_name(dev), drv->name);
516
517 pm_runtime_get_suppliers(dev);
518 if (dev->parent)
519 pm_runtime_get_sync(dev->parent);
520
521 pm_runtime_barrier(dev);
522 ret = really_probe(dev, drv);
523 pm_request_idle(dev);
524
525 if (dev->parent)
526 pm_runtime_put(dev->parent);
527
528 pm_runtime_put_suppliers(dev);
529 return ret;
530}
531
532bool driver_allows_async_probing(struct device_driver *drv)
533{
534 switch (drv->probe_type) {
535 case PROBE_PREFER_ASYNCHRONOUS:
536 return true;
537
538 case PROBE_FORCE_SYNCHRONOUS:
539 return false;
540
541 default:
542 if (module_requested_async_probing(drv->owner))
543 return true;
544
545 return false;
546 }
547}
548
549struct device_attach_data {
550 struct device *dev;
551
552 /*
553 * Indicates whether we are are considering asynchronous probing or
554 * not. Only initial binding after device or driver registration
555 * (including deferral processing) may be done asynchronously, the
556 * rest is always synchronous, as we expect it is being done by
557 * request from userspace.
558 */
559 bool check_async;
560
561 /*
562 * Indicates if we are binding synchronous or asynchronous drivers.
563 * When asynchronous probing is enabled we'll execute 2 passes
564 * over drivers: first pass doing synchronous probing and second
565 * doing asynchronous probing (if synchronous did not succeed -
566 * most likely because there was no driver requiring synchronous
567 * probing - and we found asynchronous driver during first pass).
568 * The 2 passes are done because we can't shoot asynchronous
569 * probe for given device and driver from bus_for_each_drv() since
570 * driver pointer is not guaranteed to stay valid once
571 * bus_for_each_drv() iterates to the next driver on the bus.
572 */
573 bool want_async;
574
575 /*
576 * We'll set have_async to 'true' if, while scanning for matching
577 * driver, we'll encounter one that requests asynchronous probing.
578 */
579 bool have_async;
580};
581
582static int __device_attach_driver(struct device_driver *drv, void *_data)
583{
584 struct device_attach_data *data = _data;
585 struct device *dev = data->dev;
586 bool async_allowed;
587 int ret;
588
589 /*
590 * Check if device has already been claimed. This may
591 * happen with driver loading, device discovery/registration,
592 * and deferred probe processing happens all at once with
593 * multiple threads.
594 */
595 if (dev->driver)
596 return -EBUSY;
597
598 ret = driver_match_device(drv, dev);
599 if (ret == 0) {
600 /* no match */
601 return 0;
602 } else if (ret == -EPROBE_DEFER) {
603 dev_dbg(dev, "Device match requests probe deferral\n");
604 driver_deferred_probe_add(dev);
605 } else if (ret < 0) {
606 dev_dbg(dev, "Bus failed to match device: %d", ret);
607 return ret;
608 } /* ret > 0 means positive match */
609
610 async_allowed = driver_allows_async_probing(drv);
611
612 if (async_allowed)
613 data->have_async = true;
614
615 if (data->check_async && async_allowed != data->want_async)
616 return 0;
617
618 return driver_probe_device(drv, dev);
619}
620
621static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
622{
623 struct device *dev = _dev;
624 struct device_attach_data data = {
625 .dev = dev,
626 .check_async = true,
627 .want_async = true,
628 };
629
630 device_lock(dev);
631
632 if (dev->parent)
633 pm_runtime_get_sync(dev->parent);
634
635 bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
636 dev_dbg(dev, "async probe completed\n");
637
638 pm_request_idle(dev);
639
640 if (dev->parent)
641 pm_runtime_put(dev->parent);
642
643 device_unlock(dev);
644
645 put_device(dev);
646}
647
648static int __device_attach(struct device *dev, bool allow_async)
649{
650 int ret = 0;
651
652 device_lock(dev);
653 if (dev->driver) {
654 if (device_is_bound(dev)) {
655 ret = 1;
656 goto out_unlock;
657 }
658 ret = device_bind_driver(dev);
659 if (ret == 0)
660 ret = 1;
661 else {
662 dev->driver = NULL;
663 ret = 0;
664 }
665 } else {
666 struct device_attach_data data = {
667 .dev = dev,
668 .check_async = allow_async,
669 .want_async = false,
670 };
671
672 if (dev->parent)
673 pm_runtime_get_sync(dev->parent);
674
675 ret = bus_for_each_drv(dev->bus, NULL, &data,
676 __device_attach_driver);
677 if (!ret && allow_async && data.have_async) {
678 /*
679 * If we could not find appropriate driver
680 * synchronously and we are allowed to do
681 * async probes and there are drivers that
682 * want to probe asynchronously, we'll
683 * try them.
684 */
685 dev_dbg(dev, "scheduling asynchronous probe\n");
686 get_device(dev);
687 async_schedule(__device_attach_async_helper, dev);
688 } else {
689 pm_request_idle(dev);
690 }
691
692 if (dev->parent)
693 pm_runtime_put(dev->parent);
694 }
695out_unlock:
696 device_unlock(dev);
697 return ret;
698}
699
700/**
701 * device_attach - try to attach device to a driver.
702 * @dev: device.
703 *
704 * Walk the list of drivers that the bus has and call
705 * driver_probe_device() for each pair. If a compatible
706 * pair is found, break out and return.
707 *
708 * Returns 1 if the device was bound to a driver;
709 * 0 if no matching driver was found;
710 * -ENODEV if the device is not registered.
711 *
712 * When called for a USB interface, @dev->parent lock must be held.
713 */
714int device_attach(struct device *dev)
715{
716 return __device_attach(dev, false);
717}
718EXPORT_SYMBOL_GPL(device_attach);
719
720void device_initial_probe(struct device *dev)
721{
722 __device_attach(dev, true);
723}
724
725static int __driver_attach(struct device *dev, void *data)
726{
727 struct device_driver *drv = data;
728 int ret;
729
730 /*
731 * Lock device and try to bind to it. We drop the error
732 * here and always return 0, because we need to keep trying
733 * to bind to devices and some drivers will return an error
734 * simply if it didn't support the device.
735 *
736 * driver_probe_device() will spit a warning if there
737 * is an error.
738 */
739
740 ret = driver_match_device(drv, dev);
741 if (ret == 0) {
742 /* no match */
743 return 0;
744 } else if (ret == -EPROBE_DEFER) {
745 dev_dbg(dev, "Device match requests probe deferral\n");
746 driver_deferred_probe_add(dev);
747 } else if (ret < 0) {
748 dev_dbg(dev, "Bus failed to match device: %d", ret);
749 return ret;
750 } /* ret > 0 means positive match */
751
752 if (dev->parent) /* Needed for USB */
753 device_lock(dev->parent);
754 device_lock(dev);
755 if (!dev->driver)
756 driver_probe_device(drv, dev);
757 device_unlock(dev);
758 if (dev->parent)
759 device_unlock(dev->parent);
760
761 return 0;
762}
763
764/**
765 * driver_attach - try to bind driver to devices.
766 * @drv: driver.
767 *
768 * Walk the list of devices that the bus has on it and try to
769 * match the driver with each one. If driver_probe_device()
770 * returns 0 and the @dev->driver is set, we've found a
771 * compatible pair.
772 */
773int driver_attach(struct device_driver *drv)
774{
775 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
776}
777EXPORT_SYMBOL_GPL(driver_attach);
778
779/*
780 * __device_release_driver() must be called with @dev lock held.
781 * When called for a USB interface, @dev->parent lock must be held as well.
782 */
783static void __device_release_driver(struct device *dev, struct device *parent)
784{
785 struct device_driver *drv;
786
787 drv = dev->driver;
788 if (drv) {
789 if (driver_allows_async_probing(drv))
790 async_synchronize_full();
791
792 while (device_links_busy(dev)) {
793 device_unlock(dev);
794 if (parent)
795 device_unlock(parent);
796
797 device_links_unbind_consumers(dev);
798 if (parent)
799 device_lock(parent);
800
801 device_lock(dev);
802 /*
803 * A concurrent invocation of the same function might
804 * have released the driver successfully while this one
805 * was waiting, so check for that.
806 */
807 if (dev->driver != drv)
808 return;
809 }
810
811 pm_runtime_get_sync(dev);
812 pm_runtime_clean_up_links(dev);
813
814 driver_sysfs_remove(dev);
815
816 if (dev->bus)
817 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
818 BUS_NOTIFY_UNBIND_DRIVER,
819 dev);
820
821 pm_runtime_put_sync(dev);
822
823 if (dev->bus && dev->bus->remove)
824 dev->bus->remove(dev);
825 else if (drv->remove)
826 drv->remove(dev);
827
828 device_links_driver_cleanup(dev);
829 devres_release_all(dev);
830 dev->driver = NULL;
831 dev_set_drvdata(dev, NULL);
832 if (dev->pm_domain && dev->pm_domain->dismiss)
833 dev->pm_domain->dismiss(dev);
834 pm_runtime_reinit(dev);
835
836 klist_remove(&dev->p->knode_driver);
837 device_pm_check_callbacks(dev);
838 if (dev->bus)
839 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
840 BUS_NOTIFY_UNBOUND_DRIVER,
841 dev);
842 }
843}
844
845void device_release_driver_internal(struct device *dev,
846 struct device_driver *drv,
847 struct device *parent)
848{
849 if (parent)
850 device_lock(parent);
851
852 device_lock(dev);
853 if (!drv || drv == dev->driver)
854 __device_release_driver(dev, parent);
855
856 device_unlock(dev);
857 if (parent)
858 device_unlock(parent);
859}
860
861/**
862 * device_release_driver - manually detach device from driver.
863 * @dev: device.
864 *
865 * Manually detach device from driver.
866 * When called for a USB interface, @dev->parent lock must be held.
867 *
868 * If this function is to be called with @dev->parent lock held, ensure that
869 * the device's consumers are unbound in advance or that their locks can be
870 * acquired under the @dev->parent lock.
871 */
872void device_release_driver(struct device *dev)
873{
874 /*
875 * If anyone calls device_release_driver() recursively from
876 * within their ->remove callback for the same device, they
877 * will deadlock right here.
878 */
879 device_release_driver_internal(dev, NULL, NULL);
880}
881EXPORT_SYMBOL_GPL(device_release_driver);
882
883/**
884 * driver_detach - detach driver from all devices it controls.
885 * @drv: driver.
886 */
887void driver_detach(struct device_driver *drv)
888{
889 struct device_private *dev_prv;
890 struct device *dev;
891
892 for (;;) {
893 spin_lock(&drv->p->klist_devices.k_lock);
894 if (list_empty(&drv->p->klist_devices.k_list)) {
895 spin_unlock(&drv->p->klist_devices.k_lock);
896 break;
897 }
898 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
899 struct device_private,
900 knode_driver.n_node);
901 dev = dev_prv->device;
902 get_device(dev);
903 spin_unlock(&drv->p->klist_devices.k_lock);
904 device_release_driver_internal(dev, drv, dev->parent);
905 put_device(dev);
906 }
907}