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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 <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 * deferred_probe_work_func() - Retry probing devices in the active list.
59 */
60static void deferred_probe_work_func(struct work_struct *work)
61{
62 struct device *dev;
63 struct device_private *private;
64 /*
65 * This block processes every device in the deferred 'active' list.
66 * Each device is removed from the active list and passed to
67 * bus_probe_device() to re-attempt the probe. The loop continues
68 * until every device in the active list is removed and retried.
69 *
70 * Note: Once the device is removed from the list and the mutex is
71 * released, it is possible for the device get freed by another thread
72 * and cause a illegal pointer dereference. This code uses
73 * get/put_device() to ensure the device structure cannot disappear
74 * from under our feet.
75 */
76 mutex_lock(&deferred_probe_mutex);
77 while (!list_empty(&deferred_probe_active_list)) {
78 private = list_first_entry(&deferred_probe_active_list,
79 typeof(*dev->p), deferred_probe);
80 dev = private->device;
81 list_del_init(&private->deferred_probe);
82
83 get_device(dev);
84
85 /*
86 * Drop the mutex while probing each device; the probe path may
87 * manipulate the deferred list
88 */
89 mutex_unlock(&deferred_probe_mutex);
90
91 /*
92 * Force the device to the end of the dpm_list since
93 * the PM code assumes that the order we add things to
94 * the list is a good order for suspend but deferred
95 * probe makes that very unsafe.
96 */
97 device_pm_lock();
98 device_pm_move_last(dev);
99 device_pm_unlock();
100
101 dev_dbg(dev, "Retrying from deferred list\n");
102 bus_probe_device(dev);
103
104 mutex_lock(&deferred_probe_mutex);
105
106 put_device(dev);
107 }
108 mutex_unlock(&deferred_probe_mutex);
109}
110static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
111
112static void driver_deferred_probe_add(struct device *dev)
113{
114 mutex_lock(&deferred_probe_mutex);
115 if (list_empty(&dev->p->deferred_probe)) {
116 dev_dbg(dev, "Added to deferred list\n");
117 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
118 }
119 mutex_unlock(&deferred_probe_mutex);
120}
121
122void driver_deferred_probe_del(struct device *dev)
123{
124 mutex_lock(&deferred_probe_mutex);
125 if (!list_empty(&dev->p->deferred_probe)) {
126 dev_dbg(dev, "Removed from deferred list\n");
127 list_del_init(&dev->p->deferred_probe);
128 }
129 mutex_unlock(&deferred_probe_mutex);
130}
131
132static bool driver_deferred_probe_enable = false;
133/**
134 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
135 *
136 * This functions moves all devices from the pending list to the active
137 * list and schedules the deferred probe workqueue to process them. It
138 * should be called anytime a driver is successfully bound to a device.
139 *
140 * Note, there is a race condition in multi-threaded probe. In the case where
141 * more than one device is probing at the same time, it is possible for one
142 * probe to complete successfully while another is about to defer. If the second
143 * depends on the first, then it will get put on the pending list after the
144 * trigger event has already occured and will be stuck there.
145 *
146 * The atomic 'deferred_trigger_count' is used to determine if a successful
147 * trigger has occurred in the midst of probing a driver. If the trigger count
148 * changes in the midst of a probe, then deferred processing should be triggered
149 * again.
150 */
151static void driver_deferred_probe_trigger(void)
152{
153 if (!driver_deferred_probe_enable)
154 return;
155
156 /*
157 * A successful probe means that all the devices in the pending list
158 * should be triggered to be reprobed. Move all the deferred devices
159 * into the active list so they can be retried by the workqueue
160 */
161 mutex_lock(&deferred_probe_mutex);
162 atomic_inc(&deferred_trigger_count);
163 list_splice_tail_init(&deferred_probe_pending_list,
164 &deferred_probe_active_list);
165 mutex_unlock(&deferred_probe_mutex);
166
167 /*
168 * Kick the re-probe thread. It may already be scheduled, but it is
169 * safe to kick it again.
170 */
171 queue_work(deferred_wq, &deferred_probe_work);
172}
173
174/**
175 * deferred_probe_initcall() - Enable probing of deferred devices
176 *
177 * We don't want to get in the way when the bulk of drivers are getting probed.
178 * Instead, this initcall makes sure that deferred probing is delayed until
179 * late_initcall time.
180 */
181static int deferred_probe_initcall(void)
182{
183 deferred_wq = create_singlethread_workqueue("deferwq");
184 if (WARN_ON(!deferred_wq))
185 return -ENOMEM;
186
187 driver_deferred_probe_enable = true;
188 driver_deferred_probe_trigger();
189 /* Sort as many dependencies as possible before exiting initcalls */
190 flush_workqueue(deferred_wq);
191 return 0;
192}
193late_initcall(deferred_probe_initcall);
194
195static void driver_bound(struct device *dev)
196{
197 if (klist_node_attached(&dev->p->knode_driver)) {
198 printk(KERN_WARNING "%s: device %s already bound\n",
199 __func__, kobject_name(&dev->kobj));
200 return;
201 }
202
203 pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
204 __func__, dev_name(dev));
205
206 klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
207
208 /*
209 * Make sure the device is no longer in one of the deferred lists and
210 * kick off retrying all pending devices
211 */
212 driver_deferred_probe_del(dev);
213 driver_deferred_probe_trigger();
214
215 if (dev->bus)
216 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
217 BUS_NOTIFY_BOUND_DRIVER, dev);
218}
219
220static int driver_sysfs_add(struct device *dev)
221{
222 int ret;
223
224 if (dev->bus)
225 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
226 BUS_NOTIFY_BIND_DRIVER, dev);
227
228 ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
229 kobject_name(&dev->kobj));
230 if (ret == 0) {
231 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
232 "driver");
233 if (ret)
234 sysfs_remove_link(&dev->driver->p->kobj,
235 kobject_name(&dev->kobj));
236 }
237 return ret;
238}
239
240static void driver_sysfs_remove(struct device *dev)
241{
242 struct device_driver *drv = dev->driver;
243
244 if (drv) {
245 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
246 sysfs_remove_link(&dev->kobj, "driver");
247 }
248}
249
250/**
251 * device_bind_driver - bind a driver to one device.
252 * @dev: device.
253 *
254 * Allow manual attachment of a driver to a device.
255 * Caller must have already set @dev->driver.
256 *
257 * Note that this does not modify the bus reference count
258 * nor take the bus's rwsem. Please verify those are accounted
259 * for before calling this. (It is ok to call with no other effort
260 * from a driver's probe() method.)
261 *
262 * This function must be called with the device lock held.
263 */
264int device_bind_driver(struct device *dev)
265{
266 int ret;
267
268 ret = driver_sysfs_add(dev);
269 if (!ret)
270 driver_bound(dev);
271 return ret;
272}
273EXPORT_SYMBOL_GPL(device_bind_driver);
274
275static atomic_t probe_count = ATOMIC_INIT(0);
276static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
277
278static int really_probe(struct device *dev, struct device_driver *drv)
279{
280 int ret = 0;
281 int local_trigger_count = atomic_read(&deferred_trigger_count);
282
283 atomic_inc(&probe_count);
284 pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
285 drv->bus->name, __func__, drv->name, dev_name(dev));
286 WARN_ON(!list_empty(&dev->devres_head));
287
288 dev->driver = drv;
289
290 /* If using pinctrl, bind pins now before probing */
291 ret = pinctrl_bind_pins(dev);
292 if (ret)
293 goto probe_failed;
294
295 if (driver_sysfs_add(dev)) {
296 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
297 __func__, dev_name(dev));
298 goto probe_failed;
299 }
300
301 if (dev->bus->probe) {
302 ret = dev->bus->probe(dev);
303 if (ret)
304 goto probe_failed;
305 } else if (drv->probe) {
306 ret = drv->probe(dev);
307 if (ret)
308 goto probe_failed;
309 }
310
311 driver_bound(dev);
312 ret = 1;
313 pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
314 drv->bus->name, __func__, dev_name(dev), drv->name);
315 goto done;
316
317probe_failed:
318 devres_release_all(dev);
319 driver_sysfs_remove(dev);
320 dev->driver = NULL;
321 dev_set_drvdata(dev, NULL);
322
323 if (ret == -EPROBE_DEFER) {
324 /* Driver requested deferred probing */
325 dev_info(dev, "Driver %s requests probe deferral\n", drv->name);
326 driver_deferred_probe_add(dev);
327 /* Did a trigger occur while probing? Need to re-trigger if yes */
328 if (local_trigger_count != atomic_read(&deferred_trigger_count))
329 driver_deferred_probe_trigger();
330 } else if (ret != -ENODEV && ret != -ENXIO) {
331 /* driver matched but the probe failed */
332 printk(KERN_WARNING
333 "%s: probe of %s failed with error %d\n",
334 drv->name, dev_name(dev), ret);
335 } else {
336 pr_debug("%s: probe of %s rejects match %d\n",
337 drv->name, dev_name(dev), ret);
338 }
339 /*
340 * Ignore errors returned by ->probe so that the next driver can try
341 * its luck.
342 */
343 ret = 0;
344done:
345 atomic_dec(&probe_count);
346 wake_up(&probe_waitqueue);
347 return ret;
348}
349
350/**
351 * driver_probe_done
352 * Determine if the probe sequence is finished or not.
353 *
354 * Should somehow figure out how to use a semaphore, not an atomic variable...
355 */
356int driver_probe_done(void)
357{
358 pr_debug("%s: probe_count = %d\n", __func__,
359 atomic_read(&probe_count));
360 if (atomic_read(&probe_count))
361 return -EBUSY;
362 return 0;
363}
364
365/**
366 * wait_for_device_probe
367 * Wait for device probing to be completed.
368 */
369void wait_for_device_probe(void)
370{
371 /* wait for the known devices to complete their probing */
372 wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
373 async_synchronize_full();
374}
375EXPORT_SYMBOL_GPL(wait_for_device_probe);
376
377/**
378 * driver_probe_device - attempt to bind device & driver together
379 * @drv: driver to bind a device to
380 * @dev: device to try to bind to the driver
381 *
382 * This function returns -ENODEV if the device is not registered,
383 * 1 if the device is bound successfully and 0 otherwise.
384 *
385 * This function must be called with @dev lock held. When called for a
386 * USB interface, @dev->parent lock must be held as well.
387 */
388int driver_probe_device(struct device_driver *drv, struct device *dev)
389{
390 int ret = 0;
391
392 if (!device_is_registered(dev))
393 return -ENODEV;
394
395 pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
396 drv->bus->name, __func__, dev_name(dev), drv->name);
397
398 pm_runtime_barrier(dev);
399 ret = really_probe(dev, drv);
400 pm_request_idle(dev);
401
402 return ret;
403}
404
405static int __device_attach(struct device_driver *drv, void *data)
406{
407 struct device *dev = data;
408
409 if (!driver_match_device(drv, dev))
410 return 0;
411
412 return driver_probe_device(drv, dev);
413}
414
415/**
416 * device_attach - try to attach device to a driver.
417 * @dev: device.
418 *
419 * Walk the list of drivers that the bus has and call
420 * driver_probe_device() for each pair. If a compatible
421 * pair is found, break out and return.
422 *
423 * Returns 1 if the device was bound to a driver;
424 * 0 if no matching driver was found;
425 * -ENODEV if the device is not registered.
426 *
427 * When called for a USB interface, @dev->parent lock must be held.
428 */
429int device_attach(struct device *dev)
430{
431 int ret = 0;
432
433 device_lock(dev);
434 if (dev->driver) {
435 if (klist_node_attached(&dev->p->knode_driver)) {
436 ret = 1;
437 goto out_unlock;
438 }
439 ret = device_bind_driver(dev);
440 if (ret == 0)
441 ret = 1;
442 else {
443 dev->driver = NULL;
444 ret = 0;
445 }
446 } else {
447 ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
448 pm_request_idle(dev);
449 }
450out_unlock:
451 device_unlock(dev);
452 return ret;
453}
454EXPORT_SYMBOL_GPL(device_attach);
455
456static int __driver_attach(struct device *dev, void *data)
457{
458 struct device_driver *drv = data;
459
460 /*
461 * Lock device and try to bind to it. We drop the error
462 * here and always return 0, because we need to keep trying
463 * to bind to devices and some drivers will return an error
464 * simply if it didn't support the device.
465 *
466 * driver_probe_device() will spit a warning if there
467 * is an error.
468 */
469
470 if (!driver_match_device(drv, dev))
471 return 0;
472
473 if (dev->parent) /* Needed for USB */
474 device_lock(dev->parent);
475 device_lock(dev);
476 if (!dev->driver)
477 driver_probe_device(drv, dev);
478 device_unlock(dev);
479 if (dev->parent)
480 device_unlock(dev->parent);
481
482 return 0;
483}
484
485/**
486 * driver_attach - try to bind driver to devices.
487 * @drv: driver.
488 *
489 * Walk the list of devices that the bus has on it and try to
490 * match the driver with each one. If driver_probe_device()
491 * returns 0 and the @dev->driver is set, we've found a
492 * compatible pair.
493 */
494int driver_attach(struct device_driver *drv)
495{
496 return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
497}
498EXPORT_SYMBOL_GPL(driver_attach);
499
500/*
501 * __device_release_driver() must be called with @dev lock held.
502 * When called for a USB interface, @dev->parent lock must be held as well.
503 */
504static void __device_release_driver(struct device *dev)
505{
506 struct device_driver *drv;
507
508 drv = dev->driver;
509 if (drv) {
510 pm_runtime_get_sync(dev);
511
512 driver_sysfs_remove(dev);
513
514 if (dev->bus)
515 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
516 BUS_NOTIFY_UNBIND_DRIVER,
517 dev);
518
519 pm_runtime_put_sync(dev);
520
521 if (dev->bus && dev->bus->remove)
522 dev->bus->remove(dev);
523 else if (drv->remove)
524 drv->remove(dev);
525 devres_release_all(dev);
526 dev->driver = NULL;
527 dev_set_drvdata(dev, NULL);
528 klist_remove(&dev->p->knode_driver);
529 if (dev->bus)
530 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
531 BUS_NOTIFY_UNBOUND_DRIVER,
532 dev);
533
534 }
535}
536
537/**
538 * device_release_driver - manually detach device from driver.
539 * @dev: device.
540 *
541 * Manually detach device from driver.
542 * When called for a USB interface, @dev->parent lock must be held.
543 */
544void device_release_driver(struct device *dev)
545{
546 /*
547 * If anyone calls device_release_driver() recursively from
548 * within their ->remove callback for the same device, they
549 * will deadlock right here.
550 */
551 device_lock(dev);
552 __device_release_driver(dev);
553 device_unlock(dev);
554}
555EXPORT_SYMBOL_GPL(device_release_driver);
556
557/**
558 * driver_detach - detach driver from all devices it controls.
559 * @drv: driver.
560 */
561void driver_detach(struct device_driver *drv)
562{
563 struct device_private *dev_prv;
564 struct device *dev;
565
566 for (;;) {
567 spin_lock(&drv->p->klist_devices.k_lock);
568 if (list_empty(&drv->p->klist_devices.k_list)) {
569 spin_unlock(&drv->p->klist_devices.k_lock);
570 break;
571 }
572 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
573 struct device_private,
574 knode_driver.n_node);
575 dev = dev_prv->device;
576 get_device(dev);
577 spin_unlock(&drv->p->klist_devices.k_lock);
578
579 if (dev->parent) /* Needed for USB */
580 device_lock(dev->parent);
581 device_lock(dev);
582 if (dev->driver == drv)
583 __device_release_driver(dev);
584 device_unlock(dev);
585 if (dev->parent)
586 device_unlock(dev->parent);
587 put_device(dev);
588 }
589}
590
591/*
592 * These exports can't be _GPL due to .h files using this within them, and it
593 * might break something that was previously working...
594 */
595void *dev_get_drvdata(const struct device *dev)
596{
597 if (dev && dev->p)
598 return dev->p->driver_data;
599 return NULL;
600}
601EXPORT_SYMBOL(dev_get_drvdata);
602
603int dev_set_drvdata(struct device *dev, void *data)
604{
605 int error;
606
607 if (!dev->p) {
608 error = device_private_init(dev);
609 if (error)
610 return error;
611 }
612 dev->p->driver_data = data;
613 return 0;
614}
615EXPORT_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}