45575e134696280b4b2de4635b9631f1737b0f58
[muen/linux.git] / drivers / base / dd.c
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/dma-mapping.h>
23 #include <linux/init.h>
24 #include <linux/module.h>
25 #include <linux/kthread.h>
26 #include <linux/wait.h>
27 #include <linux/async.h>
28 #include <linux/pm_runtime.h>
29 #include <linux/pinctrl/devinfo.h>
30
31 #include "base.h"
32 #include "power/power.h"
33
34 /*
35  * Deferred Probe infrastructure.
36  *
37  * Sometimes driver probe order matters, but the kernel doesn't always have
38  * dependency information which means some drivers will get probed before a
39  * resource it depends on is available.  For example, an SDHCI driver may
40  * first need a GPIO line from an i2c GPIO controller before it can be
41  * initialized.  If a required resource is not available yet, a driver can
42  * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
43  *
44  * Deferred probe maintains two lists of devices, a pending list and an active
45  * list.  A driver returning -EPROBE_DEFER causes the device to be added to the
46  * pending list.  A successful driver probe will trigger moving all devices
47  * from the pending to the active list so that the workqueue will eventually
48  * retry them.
49  *
50  * The deferred_probe_mutex must be held any time the deferred_probe_*_list
51  * of the (struct device*)->p->deferred_probe pointers are manipulated
52  */
53 static DEFINE_MUTEX(deferred_probe_mutex);
54 static LIST_HEAD(deferred_probe_pending_list);
55 static LIST_HEAD(deferred_probe_active_list);
56 static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
57 static bool initcalls_done;
58
59 /*
60  * In some cases, like suspend to RAM or hibernation, It might be reasonable
61  * to prohibit probing of devices as it could be unsafe.
62  * Once defer_all_probes is true all drivers probes will be forcibly deferred.
63  */
64 static bool defer_all_probes;
65
66 /*
67  * For initcall_debug, show the deferred probes executed in late_initcall
68  * processing.
69  */
70 static void deferred_probe_debug(struct device *dev)
71 {
72         ktime_t calltime, delta, rettime;
73         unsigned long long duration;
74
75         printk(KERN_DEBUG "deferred probe %s @ %i\n", dev_name(dev),
76                task_pid_nr(current));
77         calltime = ktime_get();
78         bus_probe_device(dev);
79         rettime = ktime_get();
80         delta = ktime_sub(rettime, calltime);
81         duration = (unsigned long long) ktime_to_ns(delta) >> 10;
82         printk(KERN_DEBUG "deferred probe %s returned after %lld usecs\n",
83                dev_name(dev), duration);
84 }
85
86 /*
87  * deferred_probe_work_func() - Retry probing devices in the active list.
88  */
89 static void deferred_probe_work_func(struct work_struct *work)
90 {
91         struct device *dev;
92         struct device_private *private;
93         /*
94          * This block processes every device in the deferred 'active' list.
95          * Each device is removed from the active list and passed to
96          * bus_probe_device() to re-attempt the probe.  The loop continues
97          * until every device in the active list is removed and retried.
98          *
99          * Note: Once the device is removed from the list and the mutex is
100          * released, it is possible for the device get freed by another thread
101          * and cause a illegal pointer dereference.  This code uses
102          * get/put_device() to ensure the device structure cannot disappear
103          * from under our feet.
104          */
105         mutex_lock(&deferred_probe_mutex);
106         while (!list_empty(&deferred_probe_active_list)) {
107                 private = list_first_entry(&deferred_probe_active_list,
108                                         typeof(*dev->p), deferred_probe);
109                 dev = private->device;
110                 list_del_init(&private->deferred_probe);
111
112                 get_device(dev);
113
114                 /*
115                  * Drop the mutex while probing each device; the probe path may
116                  * manipulate the deferred list
117                  */
118                 mutex_unlock(&deferred_probe_mutex);
119
120                 /*
121                  * Force the device to the end of the dpm_list since
122                  * the PM code assumes that the order we add things to
123                  * the list is a good order for suspend but deferred
124                  * probe makes that very unsafe.
125                  */
126                 device_pm_lock();
127                 device_pm_move_last(dev);
128                 device_pm_unlock();
129
130                 dev_dbg(dev, "Retrying from deferred list\n");
131                 if (initcall_debug && !initcalls_done)
132                         deferred_probe_debug(dev);
133                 else
134                         bus_probe_device(dev);
135
136                 mutex_lock(&deferred_probe_mutex);
137
138                 put_device(dev);
139         }
140         mutex_unlock(&deferred_probe_mutex);
141 }
142 static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);
143
144 static void driver_deferred_probe_add(struct device *dev)
145 {
146         mutex_lock(&deferred_probe_mutex);
147         if (list_empty(&dev->p->deferred_probe)) {
148                 dev_dbg(dev, "Added to deferred list\n");
149                 list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
150         }
151         mutex_unlock(&deferred_probe_mutex);
152 }
153
154 void driver_deferred_probe_del(struct device *dev)
155 {
156         mutex_lock(&deferred_probe_mutex);
157         if (!list_empty(&dev->p->deferred_probe)) {
158                 dev_dbg(dev, "Removed from deferred list\n");
159                 list_del_init(&dev->p->deferred_probe);
160         }
161         mutex_unlock(&deferred_probe_mutex);
162 }
163
164 static bool driver_deferred_probe_enable = false;
165 /**
166  * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
167  *
168  * This functions moves all devices from the pending list to the active
169  * list and schedules the deferred probe workqueue to process them.  It
170  * should be called anytime a driver is successfully bound to a device.
171  *
172  * Note, there is a race condition in multi-threaded probe. In the case where
173  * more than one device is probing at the same time, it is possible for one
174  * probe to complete successfully while another is about to defer. If the second
175  * depends on the first, then it will get put on the pending list after the
176  * trigger event has already occurred and will be stuck there.
177  *
178  * The atomic 'deferred_trigger_count' is used to determine if a successful
179  * trigger has occurred in the midst of probing a driver. If the trigger count
180  * changes in the midst of a probe, then deferred processing should be triggered
181  * again.
182  */
183 static void driver_deferred_probe_trigger(void)
184 {
185         if (!driver_deferred_probe_enable)
186                 return;
187
188         /*
189          * A successful probe means that all the devices in the pending list
190          * should be triggered to be reprobed.  Move all the deferred devices
191          * into the active list so they can be retried by the workqueue
192          */
193         mutex_lock(&deferred_probe_mutex);
194         atomic_inc(&deferred_trigger_count);
195         list_splice_tail_init(&deferred_probe_pending_list,
196                               &deferred_probe_active_list);
197         mutex_unlock(&deferred_probe_mutex);
198
199         /*
200          * Kick the re-probe thread.  It may already be scheduled, but it is
201          * safe to kick it again.
202          */
203         schedule_work(&deferred_probe_work);
204 }
205
206 /**
207  * device_block_probing() - Block/defere device's probes
208  *
209  *      It will disable probing of devices and defer their probes instead.
210  */
211 void device_block_probing(void)
212 {
213         defer_all_probes = true;
214         /* sync with probes to avoid races. */
215         wait_for_device_probe();
216 }
217
218 /**
219  * device_unblock_probing() - Unblock/enable device's probes
220  *
221  *      It will restore normal behavior and trigger re-probing of deferred
222  * devices.
223  */
224 void device_unblock_probing(void)
225 {
226         defer_all_probes = false;
227         driver_deferred_probe_trigger();
228 }
229
230 /**
231  * deferred_probe_initcall() - Enable probing of deferred devices
232  *
233  * We don't want to get in the way when the bulk of drivers are getting probed.
234  * Instead, this initcall makes sure that deferred probing is delayed until
235  * late_initcall time.
236  */
237 static int deferred_probe_initcall(void)
238 {
239         driver_deferred_probe_enable = true;
240         driver_deferred_probe_trigger();
241         /* Sort as many dependencies as possible before exiting initcalls */
242         flush_work(&deferred_probe_work);
243         initcalls_done = true;
244         return 0;
245 }
246 late_initcall(deferred_probe_initcall);
247
248 /**
249  * device_is_bound() - Check if device is bound to a driver
250  * @dev: device to check
251  *
252  * Returns true if passed device has already finished probing successfully
253  * against a driver.
254  *
255  * This function must be called with the device lock held.
256  */
257 bool device_is_bound(struct device *dev)
258 {
259         return dev->p && klist_node_attached(&dev->p->knode_driver);
260 }
261
262 static void driver_bound(struct device *dev)
263 {
264         if (device_is_bound(dev)) {
265                 printk(KERN_WARNING "%s: device %s already bound\n",
266                         __func__, kobject_name(&dev->kobj));
267                 return;
268         }
269
270         pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
271                  __func__, dev_name(dev));
272
273         klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
274         device_links_driver_bound(dev);
275
276         device_pm_check_callbacks(dev);
277
278         /*
279          * Make sure the device is no longer in one of the deferred lists and
280          * kick off retrying all pending devices
281          */
282         driver_deferred_probe_del(dev);
283         driver_deferred_probe_trigger();
284
285         if (dev->bus)
286                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
287                                              BUS_NOTIFY_BOUND_DRIVER, dev);
288
289         kobject_uevent(&dev->kobj, KOBJ_BIND);
290 }
291
292 static int driver_sysfs_add(struct device *dev)
293 {
294         int ret;
295
296         if (dev->bus)
297                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
298                                              BUS_NOTIFY_BIND_DRIVER, dev);
299
300         ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
301                           kobject_name(&dev->kobj));
302         if (ret == 0) {
303                 ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
304                                         "driver");
305                 if (ret)
306                         sysfs_remove_link(&dev->driver->p->kobj,
307                                         kobject_name(&dev->kobj));
308         }
309         return ret;
310 }
311
312 static void driver_sysfs_remove(struct device *dev)
313 {
314         struct device_driver *drv = dev->driver;
315
316         if (drv) {
317                 sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
318                 sysfs_remove_link(&dev->kobj, "driver");
319         }
320 }
321
322 /**
323  * device_bind_driver - bind a driver to one device.
324  * @dev: device.
325  *
326  * Allow manual attachment of a driver to a device.
327  * Caller must have already set @dev->driver.
328  *
329  * Note that this does not modify the bus reference count
330  * nor take the bus's rwsem. Please verify those are accounted
331  * for before calling this. (It is ok to call with no other effort
332  * from a driver's probe() method.)
333  *
334  * This function must be called with the device lock held.
335  */
336 int device_bind_driver(struct device *dev)
337 {
338         int ret;
339
340         ret = driver_sysfs_add(dev);
341         if (!ret)
342                 driver_bound(dev);
343         else if (dev->bus)
344                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
345                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
346         return ret;
347 }
348 EXPORT_SYMBOL_GPL(device_bind_driver);
349
350 static atomic_t probe_count = ATOMIC_INIT(0);
351 static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);
352
353 static int really_probe(struct device *dev, struct device_driver *drv)
354 {
355         int ret = -EPROBE_DEFER;
356         int local_trigger_count = atomic_read(&deferred_trigger_count);
357         bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
358                            !drv->suppress_bind_attrs;
359
360         if (defer_all_probes) {
361                 /*
362                  * Value of defer_all_probes can be set only by
363                  * device_defer_all_probes_enable() which, in turn, will call
364                  * wait_for_device_probe() right after that to avoid any races.
365                  */
366                 dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
367                 driver_deferred_probe_add(dev);
368                 return ret;
369         }
370
371         ret = device_links_check_suppliers(dev);
372         if (ret)
373                 return ret;
374
375         atomic_inc(&probe_count);
376         pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
377                  drv->bus->name, __func__, drv->name, dev_name(dev));
378         WARN_ON(!list_empty(&dev->devres_head));
379
380 re_probe:
381         dev->driver = drv;
382
383         /* If using pinctrl, bind pins now before probing */
384         ret = pinctrl_bind_pins(dev);
385         if (ret)
386                 goto pinctrl_bind_failed;
387
388         ret = dma_configure(dev);
389         if (ret)
390                 goto dma_failed;
391
392         if (driver_sysfs_add(dev)) {
393                 printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
394                         __func__, dev_name(dev));
395                 goto probe_failed;
396         }
397
398         if (dev->pm_domain && dev->pm_domain->activate) {
399                 ret = dev->pm_domain->activate(dev);
400                 if (ret)
401                         goto probe_failed;
402         }
403
404         /*
405          * Ensure devices are listed in devices_kset in correct order
406          * It's important to move Dev to the end of devices_kset before
407          * calling .probe, because it could be recursive and parent Dev
408          * should always go first
409          */
410         devices_kset_move_last(dev);
411
412         if (dev->bus->probe) {
413                 ret = dev->bus->probe(dev);
414                 if (ret)
415                         goto probe_failed;
416         } else if (drv->probe) {
417                 ret = drv->probe(dev);
418                 if (ret)
419                         goto probe_failed;
420         }
421
422         if (test_remove) {
423                 test_remove = false;
424
425                 if (dev->bus->remove)
426                         dev->bus->remove(dev);
427                 else if (drv->remove)
428                         drv->remove(dev);
429
430                 devres_release_all(dev);
431                 driver_sysfs_remove(dev);
432                 dev->driver = NULL;
433                 dev_set_drvdata(dev, NULL);
434                 if (dev->pm_domain && dev->pm_domain->dismiss)
435                         dev->pm_domain->dismiss(dev);
436                 pm_runtime_reinit(dev);
437
438                 goto re_probe;
439         }
440
441         pinctrl_init_done(dev);
442
443         if (dev->pm_domain && dev->pm_domain->sync)
444                 dev->pm_domain->sync(dev);
445
446         driver_bound(dev);
447         ret = 1;
448         pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
449                  drv->bus->name, __func__, dev_name(dev), drv->name);
450         goto done;
451
452 probe_failed:
453         dma_deconfigure(dev);
454 dma_failed:
455         if (dev->bus)
456                 blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
457                                              BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
458 pinctrl_bind_failed:
459         device_links_no_driver(dev);
460         devres_release_all(dev);
461         driver_sysfs_remove(dev);
462         dev->driver = NULL;
463         dev_set_drvdata(dev, NULL);
464         if (dev->pm_domain && dev->pm_domain->dismiss)
465                 dev->pm_domain->dismiss(dev);
466         pm_runtime_reinit(dev);
467         dev_pm_set_driver_flags(dev, 0);
468
469         switch (ret) {
470         case -EPROBE_DEFER:
471                 /* Driver requested deferred probing */
472                 dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
473                 driver_deferred_probe_add(dev);
474                 /* Did a trigger occur while probing? Need to re-trigger if yes */
475                 if (local_trigger_count != atomic_read(&deferred_trigger_count))
476                         driver_deferred_probe_trigger();
477                 break;
478         case -ENODEV:
479         case -ENXIO:
480                 pr_debug("%s: probe of %s rejects match %d\n",
481                          drv->name, dev_name(dev), ret);
482                 break;
483         default:
484                 /* driver matched but the probe failed */
485                 printk(KERN_WARNING
486                        "%s: probe of %s failed with error %d\n",
487                        drv->name, dev_name(dev), ret);
488         }
489         /*
490          * Ignore errors returned by ->probe so that the next driver can try
491          * its luck.
492          */
493         ret = 0;
494 done:
495         atomic_dec(&probe_count);
496         wake_up(&probe_waitqueue);
497         return ret;
498 }
499
500 /**
501  * driver_probe_done
502  * Determine if the probe sequence is finished or not.
503  *
504  * Should somehow figure out how to use a semaphore, not an atomic variable...
505  */
506 int driver_probe_done(void)
507 {
508         pr_debug("%s: probe_count = %d\n", __func__,
509                  atomic_read(&probe_count));
510         if (atomic_read(&probe_count))
511                 return -EBUSY;
512         return 0;
513 }
514
515 /**
516  * wait_for_device_probe
517  * Wait for device probing to be completed.
518  */
519 void wait_for_device_probe(void)
520 {
521         /* wait for the deferred probe workqueue to finish */
522         flush_work(&deferred_probe_work);
523
524         /* wait for the known devices to complete their probing */
525         wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
526         async_synchronize_full();
527 }
528 EXPORT_SYMBOL_GPL(wait_for_device_probe);
529
530 /**
531  * driver_probe_device - attempt to bind device & driver together
532  * @drv: driver to bind a device to
533  * @dev: device to try to bind to the driver
534  *
535  * This function returns -ENODEV if the device is not registered,
536  * 1 if the device is bound successfully and 0 otherwise.
537  *
538  * This function must be called with @dev lock held.  When called for a
539  * USB interface, @dev->parent lock must be held as well.
540  *
541  * If the device has a parent, runtime-resume the parent before driver probing.
542  */
543 int driver_probe_device(struct device_driver *drv, struct device *dev)
544 {
545         int ret = 0;
546
547         if (!device_is_registered(dev))
548                 return -ENODEV;
549
550         pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
551                  drv->bus->name, __func__, dev_name(dev), drv->name);
552
553         pm_runtime_get_suppliers(dev);
554         if (dev->parent)
555                 pm_runtime_get_sync(dev->parent);
556
557         pm_runtime_barrier(dev);
558         ret = really_probe(dev, drv);
559         pm_request_idle(dev);
560
561         if (dev->parent)
562                 pm_runtime_put(dev->parent);
563
564         pm_runtime_put_suppliers(dev);
565         return ret;
566 }
567
568 bool driver_allows_async_probing(struct device_driver *drv)
569 {
570         switch (drv->probe_type) {
571         case PROBE_PREFER_ASYNCHRONOUS:
572                 return true;
573
574         case PROBE_FORCE_SYNCHRONOUS:
575                 return false;
576
577         default:
578                 if (module_requested_async_probing(drv->owner))
579                         return true;
580
581                 return false;
582         }
583 }
584
585 struct device_attach_data {
586         struct device *dev;
587
588         /*
589          * Indicates whether we are are considering asynchronous probing or
590          * not. Only initial binding after device or driver registration
591          * (including deferral processing) may be done asynchronously, the
592          * rest is always synchronous, as we expect it is being done by
593          * request from userspace.
594          */
595         bool check_async;
596
597         /*
598          * Indicates if we are binding synchronous or asynchronous drivers.
599          * When asynchronous probing is enabled we'll execute 2 passes
600          * over drivers: first pass doing synchronous probing and second
601          * doing asynchronous probing (if synchronous did not succeed -
602          * most likely because there was no driver requiring synchronous
603          * probing - and we found asynchronous driver during first pass).
604          * The 2 passes are done because we can't shoot asynchronous
605          * probe for given device and driver from bus_for_each_drv() since
606          * driver pointer is not guaranteed to stay valid once
607          * bus_for_each_drv() iterates to the next driver on the bus.
608          */
609         bool want_async;
610
611         /*
612          * We'll set have_async to 'true' if, while scanning for matching
613          * driver, we'll encounter one that requests asynchronous probing.
614          */
615         bool have_async;
616 };
617
618 static int __device_attach_driver(struct device_driver *drv, void *_data)
619 {
620         struct device_attach_data *data = _data;
621         struct device *dev = data->dev;
622         bool async_allowed;
623         int ret;
624
625         /*
626          * Check if device has already been claimed. This may
627          * happen with driver loading, device discovery/registration,
628          * and deferred probe processing happens all at once with
629          * multiple threads.
630          */
631         if (dev->driver)
632                 return -EBUSY;
633
634         ret = driver_match_device(drv, dev);
635         if (ret == 0) {
636                 /* no match */
637                 return 0;
638         } else if (ret == -EPROBE_DEFER) {
639                 dev_dbg(dev, "Device match requests probe deferral\n");
640                 driver_deferred_probe_add(dev);
641         } else if (ret < 0) {
642                 dev_dbg(dev, "Bus failed to match device: %d", ret);
643                 return ret;
644         } /* ret > 0 means positive match */
645
646         async_allowed = driver_allows_async_probing(drv);
647
648         if (async_allowed)
649                 data->have_async = true;
650
651         if (data->check_async && async_allowed != data->want_async)
652                 return 0;
653
654         return driver_probe_device(drv, dev);
655 }
656
657 static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
658 {
659         struct device *dev = _dev;
660         struct device_attach_data data = {
661                 .dev            = dev,
662                 .check_async    = true,
663                 .want_async     = true,
664         };
665
666         device_lock(dev);
667
668         if (dev->parent)
669                 pm_runtime_get_sync(dev->parent);
670
671         bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
672         dev_dbg(dev, "async probe completed\n");
673
674         pm_request_idle(dev);
675
676         if (dev->parent)
677                 pm_runtime_put(dev->parent);
678
679         device_unlock(dev);
680
681         put_device(dev);
682 }
683
684 static int __device_attach(struct device *dev, bool allow_async)
685 {
686         int ret = 0;
687
688         device_lock(dev);
689         if (dev->driver) {
690                 if (device_is_bound(dev)) {
691                         ret = 1;
692                         goto out_unlock;
693                 }
694                 ret = device_bind_driver(dev);
695                 if (ret == 0)
696                         ret = 1;
697                 else {
698                         dev->driver = NULL;
699                         ret = 0;
700                 }
701         } else {
702                 struct device_attach_data data = {
703                         .dev = dev,
704                         .check_async = allow_async,
705                         .want_async = false,
706                 };
707
708                 if (dev->parent)
709                         pm_runtime_get_sync(dev->parent);
710
711                 ret = bus_for_each_drv(dev->bus, NULL, &data,
712                                         __device_attach_driver);
713                 if (!ret && allow_async && data.have_async) {
714                         /*
715                          * If we could not find appropriate driver
716                          * synchronously and we are allowed to do
717                          * async probes and there are drivers that
718                          * want to probe asynchronously, we'll
719                          * try them.
720                          */
721                         dev_dbg(dev, "scheduling asynchronous probe\n");
722                         get_device(dev);
723                         async_schedule(__device_attach_async_helper, dev);
724                 } else {
725                         pm_request_idle(dev);
726                 }
727
728                 if (dev->parent)
729                         pm_runtime_put(dev->parent);
730         }
731 out_unlock:
732         device_unlock(dev);
733         return ret;
734 }
735
736 /**
737  * device_attach - try to attach device to a driver.
738  * @dev: device.
739  *
740  * Walk the list of drivers that the bus has and call
741  * driver_probe_device() for each pair. If a compatible
742  * pair is found, break out and return.
743  *
744  * Returns 1 if the device was bound to a driver;
745  * 0 if no matching driver was found;
746  * -ENODEV if the device is not registered.
747  *
748  * When called for a USB interface, @dev->parent lock must be held.
749  */
750 int device_attach(struct device *dev)
751 {
752         return __device_attach(dev, false);
753 }
754 EXPORT_SYMBOL_GPL(device_attach);
755
756 void device_initial_probe(struct device *dev)
757 {
758         __device_attach(dev, true);
759 }
760
761 static int __driver_attach(struct device *dev, void *data)
762 {
763         struct device_driver *drv = data;
764         int ret;
765
766         /*
767          * Lock device and try to bind to it. We drop the error
768          * here and always return 0, because we need to keep trying
769          * to bind to devices and some drivers will return an error
770          * simply if it didn't support the device.
771          *
772          * driver_probe_device() will spit a warning if there
773          * is an error.
774          */
775
776         ret = driver_match_device(drv, dev);
777         if (ret == 0) {
778                 /* no match */
779                 return 0;
780         } else if (ret == -EPROBE_DEFER) {
781                 dev_dbg(dev, "Device match requests probe deferral\n");
782                 driver_deferred_probe_add(dev);
783         } else if (ret < 0) {
784                 dev_dbg(dev, "Bus failed to match device: %d", ret);
785                 return ret;
786         } /* ret > 0 means positive match */
787
788         if (dev->parent)        /* Needed for USB */
789                 device_lock(dev->parent);
790         device_lock(dev);
791         if (!dev->driver)
792                 driver_probe_device(drv, dev);
793         device_unlock(dev);
794         if (dev->parent)
795                 device_unlock(dev->parent);
796
797         return 0;
798 }
799
800 /**
801  * driver_attach - try to bind driver to devices.
802  * @drv: driver.
803  *
804  * Walk the list of devices that the bus has on it and try to
805  * match the driver with each one.  If driver_probe_device()
806  * returns 0 and the @dev->driver is set, we've found a
807  * compatible pair.
808  */
809 int driver_attach(struct device_driver *drv)
810 {
811         return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
812 }
813 EXPORT_SYMBOL_GPL(driver_attach);
814
815 /*
816  * __device_release_driver() must be called with @dev lock held.
817  * When called for a USB interface, @dev->parent lock must be held as well.
818  */
819 static void __device_release_driver(struct device *dev, struct device *parent)
820 {
821         struct device_driver *drv;
822
823         drv = dev->driver;
824         if (drv) {
825                 if (driver_allows_async_probing(drv))
826                         async_synchronize_full();
827
828                 while (device_links_busy(dev)) {
829                         device_unlock(dev);
830                         if (parent)
831                                 device_unlock(parent);
832
833                         device_links_unbind_consumers(dev);
834                         if (parent)
835                                 device_lock(parent);
836
837                         device_lock(dev);
838                         /*
839                          * A concurrent invocation of the same function might
840                          * have released the driver successfully while this one
841                          * was waiting, so check for that.
842                          */
843                         if (dev->driver != drv)
844                                 return;
845                 }
846
847                 pm_runtime_get_sync(dev);
848                 pm_runtime_clean_up_links(dev);
849
850                 driver_sysfs_remove(dev);
851
852                 if (dev->bus)
853                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
854                                                      BUS_NOTIFY_UNBIND_DRIVER,
855                                                      dev);
856
857                 pm_runtime_put_sync(dev);
858
859                 if (dev->bus && dev->bus->remove)
860                         dev->bus->remove(dev);
861                 else if (drv->remove)
862                         drv->remove(dev);
863
864                 device_links_driver_cleanup(dev);
865                 dma_deconfigure(dev);
866
867                 devres_release_all(dev);
868                 dev->driver = NULL;
869                 dev_set_drvdata(dev, NULL);
870                 if (dev->pm_domain && dev->pm_domain->dismiss)
871                         dev->pm_domain->dismiss(dev);
872                 pm_runtime_reinit(dev);
873                 dev_pm_set_driver_flags(dev, 0);
874
875                 klist_remove(&dev->p->knode_driver);
876                 device_pm_check_callbacks(dev);
877                 if (dev->bus)
878                         blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
879                                                      BUS_NOTIFY_UNBOUND_DRIVER,
880                                                      dev);
881
882                 kobject_uevent(&dev->kobj, KOBJ_UNBIND);
883         }
884 }
885
886 void device_release_driver_internal(struct device *dev,
887                                     struct device_driver *drv,
888                                     struct device *parent)
889 {
890         if (parent)
891                 device_lock(parent);
892
893         device_lock(dev);
894         if (!drv || drv == dev->driver)
895                 __device_release_driver(dev, parent);
896
897         device_unlock(dev);
898         if (parent)
899                 device_unlock(parent);
900 }
901
902 /**
903  * device_release_driver - manually detach device from driver.
904  * @dev: device.
905  *
906  * Manually detach device from driver.
907  * When called for a USB interface, @dev->parent lock must be held.
908  *
909  * If this function is to be called with @dev->parent lock held, ensure that
910  * the device's consumers are unbound in advance or that their locks can be
911  * acquired under the @dev->parent lock.
912  */
913 void device_release_driver(struct device *dev)
914 {
915         /*
916          * If anyone calls device_release_driver() recursively from
917          * within their ->remove callback for the same device, they
918          * will deadlock right here.
919          */
920         device_release_driver_internal(dev, NULL, NULL);
921 }
922 EXPORT_SYMBOL_GPL(device_release_driver);
923
924 /**
925  * driver_detach - detach driver from all devices it controls.
926  * @drv: driver.
927  */
928 void driver_detach(struct device_driver *drv)
929 {
930         struct device_private *dev_prv;
931         struct device *dev;
932
933         for (;;) {
934                 spin_lock(&drv->p->klist_devices.k_lock);
935                 if (list_empty(&drv->p->klist_devices.k_list)) {
936                         spin_unlock(&drv->p->klist_devices.k_lock);
937                         break;
938                 }
939                 dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
940                                      struct device_private,
941                                      knode_driver.n_node);
942                 dev = dev_prv->device;
943                 get_device(dev);
944                 spin_unlock(&drv->p->klist_devices.k_lock);
945                 device_release_driver_internal(dev, drv, dev->parent);
946                 put_device(dev);
947         }
948 }