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