summaryrefslogtreecommitdiff
path: root/drivers/base/dd.c
blob: b25bcab2a26bd2adb8e7e975d7ff9f4cc5ea0cca (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
// SPDX-License-Identifier: GPL-2.0
/*
 * drivers/base/dd.c - The core device/driver interactions.
 *
 * This file contains the (sometimes tricky) code that controls the
 * interactions between devices and drivers, which primarily includes
 * driver binding and unbinding.
 *
 * All of this code used to exist in drivers/base/bus.c, but was
 * relocated to here in the name of compartmentalization (since it wasn't
 * strictly code just for the 'struct bus_type'.
 *
 * Copyright (c) 2002-5 Patrick Mochel
 * Copyright (c) 2002-3 Open Source Development Labs
 * Copyright (c) 2007-2009 Greg Kroah-Hartman <gregkh@suse.de>
 * Copyright (c) 2007-2009 Novell Inc.
 */

#include <linux/debugfs.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/wait.h>
#include <linux/async.h>
#include <linux/pm_runtime.h>
#include <linux/pinctrl/devinfo.h>

#include "base.h"
#include "power/power.h"

/*
 * Deferred Probe infrastructure.
 *
 * Sometimes driver probe order matters, but the kernel doesn't always have
 * dependency information which means some drivers will get probed before a
 * resource it depends on is available.  For example, an SDHCI driver may
 * first need a GPIO line from an i2c GPIO controller before it can be
 * initialized.  If a required resource is not available yet, a driver can
 * request probing to be deferred by returning -EPROBE_DEFER from its probe hook
 *
 * Deferred probe maintains two lists of devices, a pending list and an active
 * list.  A driver returning -EPROBE_DEFER causes the device to be added to the
 * pending list.  A successful driver probe will trigger moving all devices
 * from the pending to the active list so that the workqueue will eventually
 * retry them.
 *
 * The deferred_probe_mutex must be held any time the deferred_probe_*_list
 * of the (struct device*)->p->deferred_probe pointers are manipulated
 */
static DEFINE_MUTEX(deferred_probe_mutex);
static LIST_HEAD(deferred_probe_pending_list);
static LIST_HEAD(deferred_probe_active_list);
static atomic_t deferred_trigger_count = ATOMIC_INIT(0);
static struct dentry *deferred_devices;
static bool initcalls_done;

/* Save the async probe drivers' name from kernel cmdline */
#define ASYNC_DRV_NAMES_MAX_LEN	256
static char async_probe_drv_names[ASYNC_DRV_NAMES_MAX_LEN];

/*
 * In some cases, like suspend to RAM or hibernation, It might be reasonable
 * to prohibit probing of devices as it could be unsafe.
 * Once defer_all_probes is true all drivers probes will be forcibly deferred.
 */
static bool defer_all_probes;

/*
 * deferred_probe_work_func() - Retry probing devices in the active list.
 */
static void deferred_probe_work_func(struct work_struct *work)
{
	struct device *dev;
	struct device_private *private;
	/*
	 * This block processes every device in the deferred 'active' list.
	 * Each device is removed from the active list and passed to
	 * bus_probe_device() to re-attempt the probe.  The loop continues
	 * until every device in the active list is removed and retried.
	 *
	 * Note: Once the device is removed from the list and the mutex is
	 * released, it is possible for the device get freed by another thread
	 * and cause a illegal pointer dereference.  This code uses
	 * get/put_device() to ensure the device structure cannot disappear
	 * from under our feet.
	 */
	mutex_lock(&deferred_probe_mutex);
	while (!list_empty(&deferred_probe_active_list)) {
		private = list_first_entry(&deferred_probe_active_list,
					typeof(*dev->p), deferred_probe);
		dev = private->device;
		list_del_init(&private->deferred_probe);

		get_device(dev);

		/*
		 * Drop the mutex while probing each device; the probe path may
		 * manipulate the deferred list
		 */
		mutex_unlock(&deferred_probe_mutex);

		/*
		 * Force the device to the end of the dpm_list since
		 * the PM code assumes that the order we add things to
		 * the list is a good order for suspend but deferred
		 * probe makes that very unsafe.
		 */
		device_pm_move_to_tail(dev);

		dev_dbg(dev, "Retrying from deferred list\n");
		bus_probe_device(dev);
		mutex_lock(&deferred_probe_mutex);

		put_device(dev);
	}
	mutex_unlock(&deferred_probe_mutex);
}
static DECLARE_WORK(deferred_probe_work, deferred_probe_work_func);

void driver_deferred_probe_add(struct device *dev)
{
	mutex_lock(&deferred_probe_mutex);
	if (list_empty(&dev->p->deferred_probe)) {
		dev_dbg(dev, "Added to deferred list\n");
		list_add_tail(&dev->p->deferred_probe, &deferred_probe_pending_list);
	}
	mutex_unlock(&deferred_probe_mutex);
}

void driver_deferred_probe_del(struct device *dev)
{
	mutex_lock(&deferred_probe_mutex);
	if (!list_empty(&dev->p->deferred_probe)) {
		dev_dbg(dev, "Removed from deferred list\n");
		list_del_init(&dev->p->deferred_probe);
	}
	mutex_unlock(&deferred_probe_mutex);
}

static bool driver_deferred_probe_enable = false;
/**
 * driver_deferred_probe_trigger() - Kick off re-probing deferred devices
 *
 * This functions moves all devices from the pending list to the active
 * list and schedules the deferred probe workqueue to process them.  It
 * should be called anytime a driver is successfully bound to a device.
 *
 * Note, there is a race condition in multi-threaded probe. In the case where
 * more than one device is probing at the same time, it is possible for one
 * probe to complete successfully while another is about to defer. If the second
 * depends on the first, then it will get put on the pending list after the
 * trigger event has already occurred and will be stuck there.
 *
 * The atomic 'deferred_trigger_count' is used to determine if a successful
 * trigger has occurred in the midst of probing a driver. If the trigger count
 * changes in the midst of a probe, then deferred processing should be triggered
 * again.
 */
static void driver_deferred_probe_trigger(void)
{
	if (!driver_deferred_probe_enable)
		return;

	/*
	 * A successful probe means that all the devices in the pending list
	 * should be triggered to be reprobed.  Move all the deferred devices
	 * into the active list so they can be retried by the workqueue
	 */
	mutex_lock(&deferred_probe_mutex);
	atomic_inc(&deferred_trigger_count);
	list_splice_tail_init(&deferred_probe_pending_list,
			      &deferred_probe_active_list);
	mutex_unlock(&deferred_probe_mutex);

	/*
	 * Kick the re-probe thread.  It may already be scheduled, but it is
	 * safe to kick it again.
	 */
	schedule_work(&deferred_probe_work);
}

/**
 * device_block_probing() - Block/defer device's probes
 *
 *	It will disable probing of devices and defer their probes instead.
 */
void device_block_probing(void)
{
	defer_all_probes = true;
	/* sync with probes to avoid races. */
	wait_for_device_probe();
}

/**
 * device_unblock_probing() - Unblock/enable device's probes
 *
 *	It will restore normal behavior and trigger re-probing of deferred
 * devices.
 */
void device_unblock_probing(void)
{
	defer_all_probes = false;
	driver_deferred_probe_trigger();
}

/*
 * deferred_devs_show() - Show the devices in the deferred probe pending list.
 */
static int deferred_devs_show(struct seq_file *s, void *data)
{
	struct device_private *curr;

	mutex_lock(&deferred_probe_mutex);

	list_for_each_entry(curr, &deferred_probe_pending_list, deferred_probe)
		seq_printf(s, "%s\n", dev_name(curr->device));

	mutex_unlock(&deferred_probe_mutex);

	return 0;
}
DEFINE_SHOW_ATTRIBUTE(deferred_devs);

static int deferred_probe_timeout = -1;
static int __init deferred_probe_timeout_setup(char *str)
{
	int timeout;

	if (!kstrtoint(str, 10, &timeout))
		deferred_probe_timeout = timeout;
	return 1;
}
__setup("deferred_probe_timeout=", deferred_probe_timeout_setup);

static int __driver_deferred_probe_check_state(struct device *dev)
{
	if (!initcalls_done)
		return -EPROBE_DEFER;

	if (!deferred_probe_timeout) {
		dev_WARN(dev, "deferred probe timeout, ignoring dependency");
		return -ETIMEDOUT;
	}

	return 0;
}

/**
 * driver_deferred_probe_check_state() - Check deferred probe state
 * @dev: device to check
 *
 * Returns -ENODEV if init is done and all built-in drivers have had a chance
 * to probe (i.e. initcalls are done), -ETIMEDOUT if deferred probe debug
 * timeout has expired, or -EPROBE_DEFER if none of those conditions are met.
 *
 * Drivers or subsystems can opt-in to calling this function instead of directly
 * returning -EPROBE_DEFER.
 */
int driver_deferred_probe_check_state(struct device *dev)
{
	int ret;

	ret = __driver_deferred_probe_check_state(dev);
	if (ret < 0)
		return ret;

	dev_warn(dev, "ignoring dependency for device, assuming no driver");

	return -ENODEV;
}

/**
 * driver_deferred_probe_check_state_continue() - check deferred probe state
 * @dev: device to check
 *
 * Returns -ETIMEDOUT if deferred probe debug timeout has expired, or
 * -EPROBE_DEFER otherwise.
 *
 * Drivers or subsystems can opt-in to calling this function instead of
 * directly returning -EPROBE_DEFER.
 *
 * This is similar to driver_deferred_probe_check_state(), but it allows the
 * subsystem to keep deferring probe after built-in drivers have had a chance
 * to probe. One scenario where that is useful is if built-in drivers rely on
 * resources that are provided by modular drivers.
 */
int driver_deferred_probe_check_state_continue(struct device *dev)
{
	int ret;

	ret = __driver_deferred_probe_check_state(dev);
	if (ret < 0)
		return ret;

	return -EPROBE_DEFER;
}

static void deferred_probe_timeout_work_func(struct work_struct *work)
{
	struct device_private *private, *p;

	deferred_probe_timeout = 0;
	driver_deferred_probe_trigger();
	flush_work(&deferred_probe_work);

	list_for_each_entry_safe(private, p, &deferred_probe_pending_list, deferred_probe)
		dev_info(private->device, "deferred probe pending");
}
static DECLARE_DELAYED_WORK(deferred_probe_timeout_work, deferred_probe_timeout_work_func);

/**
 * deferred_probe_initcall() - Enable probing of deferred devices
 *
 * We don't want to get in the way when the bulk of drivers are getting probed.
 * Instead, this initcall makes sure that deferred probing is delayed until
 * late_initcall time.
 */
static int deferred_probe_initcall(void)
{
	deferred_devices = debugfs_create_file("devices_deferred", 0444, NULL,
					       NULL, &deferred_devs_fops);

	driver_deferred_probe_enable = true;
	driver_deferred_probe_trigger();
	/* Sort as many dependencies as possible before exiting initcalls */
	flush_work(&deferred_probe_work);
	initcalls_done = true;

	/*
	 * Trigger deferred probe again, this time we won't defer anything
	 * that is optional
	 */
	driver_deferred_probe_trigger();
	flush_work(&deferred_probe_work);

	if (deferred_probe_timeout > 0) {
		schedule_delayed_work(&deferred_probe_timeout_work,
			deferred_probe_timeout * HZ);
	}
	return 0;
}
late_initcall(deferred_probe_initcall);

static void __exit deferred_probe_exit(void)
{
	debugfs_remove_recursive(deferred_devices);
}
__exitcall(deferred_probe_exit);

/**
 * device_is_bound() - Check if device is bound to a driver
 * @dev: device to check
 *
 * Returns true if passed device has already finished probing successfully
 * against a driver.
 *
 * This function must be called with the device lock held.
 */
bool device_is_bound(struct device *dev)
{
	return dev->p && klist_node_attached(&dev->p->knode_driver);
}

static void driver_bound(struct device *dev)
{
	if (device_is_bound(dev)) {
		printk(KERN_WARNING "%s: device %s already bound\n",
			__func__, kobject_name(&dev->kobj));
		return;
	}

	pr_debug("driver: '%s': %s: bound to device '%s'\n", dev->driver->name,
		 __func__, dev_name(dev));

	klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
	device_links_driver_bound(dev);

	device_pm_check_callbacks(dev);

	/*
	 * Make sure the device is no longer in one of the deferred lists and
	 * kick off retrying all pending devices
	 */
	driver_deferred_probe_del(dev);
	driver_deferred_probe_trigger();

	if (dev->bus)
		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
					     BUS_NOTIFY_BOUND_DRIVER, dev);

	kobject_uevent(&dev->kobj, KOBJ_BIND);
}

static ssize_t coredump_store(struct device *dev, struct device_attribute *attr,
			    const char *buf, size_t count)
{
	device_lock(dev);
	dev->driver->coredump(dev);
	device_unlock(dev);

	return count;
}
static DEVICE_ATTR_WO(coredump);

static int driver_sysfs_add(struct device *dev)
{
	int ret;

	if (dev->bus)
		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
					     BUS_NOTIFY_BIND_DRIVER, dev);

	ret = sysfs_create_link(&dev->driver->p->kobj, &dev->kobj,
				kobject_name(&dev->kobj));
	if (ret)
		goto fail;

	ret = sysfs_create_link(&dev->kobj, &dev->driver->p->kobj,
				"driver");
	if (ret)
		goto rm_dev;

	if (!IS_ENABLED(CONFIG_DEV_COREDUMP) || !dev->driver->coredump ||
	    !device_create_file(dev, &dev_attr_coredump))
		return 0;

	sysfs_remove_link(&dev->kobj, "driver");

rm_dev:
	sysfs_remove_link(&dev->driver->p->kobj,
			  kobject_name(&dev->kobj));

fail:
	return ret;
}

static void driver_sysfs_remove(struct device *dev)
{
	struct device_driver *drv = dev->driver;

	if (drv) {
		if (drv->coredump)
			device_remove_file(dev, &dev_attr_coredump);
		sysfs_remove_link(&drv->p->kobj, kobject_name(&dev->kobj));
		sysfs_remove_link(&dev->kobj, "driver");
	}
}

/**
 * device_bind_driver - bind a driver to one device.
 * @dev: device.
 *
 * Allow manual attachment of a driver to a device.
 * Caller must have already set @dev->driver.
 *
 * Note that this does not modify the bus reference count
 * nor take the bus's rwsem. Please verify those are accounted
 * for before calling this. (It is ok to call with no other effort
 * from a driver's probe() method.)
 *
 * This function must be called with the device lock held.
 */
int device_bind_driver(struct device *dev)
{
	int ret;

	ret = driver_sysfs_add(dev);
	if (!ret)
		driver_bound(dev);
	else if (dev->bus)
		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
					     BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
	return ret;
}
EXPORT_SYMBOL_GPL(device_bind_driver);

static atomic_t probe_count = ATOMIC_INIT(0);
static DECLARE_WAIT_QUEUE_HEAD(probe_waitqueue);

static void driver_deferred_probe_add_trigger(struct device *dev,
					      int local_trigger_count)
{
	driver_deferred_probe_add(dev);
	/* Did a trigger occur while probing? Need to re-trigger if yes */
	if (local_trigger_count != atomic_read(&deferred_trigger_count))
		driver_deferred_probe_trigger();
}

static int really_probe(struct device *dev, struct device_driver *drv)
{
	int ret = -EPROBE_DEFER;
	int local_trigger_count = atomic_read(&deferred_trigger_count);
	bool test_remove = IS_ENABLED(CONFIG_DEBUG_TEST_DRIVER_REMOVE) &&
			   !drv->suppress_bind_attrs;

	if (defer_all_probes) {
		/*
		 * Value of defer_all_probes can be set only by
		 * device_block_probing() which, in turn, will call
		 * wait_for_device_probe() right after that to avoid any races.
		 */
		dev_dbg(dev, "Driver %s force probe deferral\n", drv->name);
		driver_deferred_probe_add(dev);
		return ret;
	}

	ret = device_links_check_suppliers(dev);
	if (ret == -EPROBE_DEFER)
		driver_deferred_probe_add_trigger(dev, local_trigger_count);
	if (ret)
		return ret;

	atomic_inc(&probe_count);
	pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
		 drv->bus->name, __func__, drv->name, dev_name(dev));
	if (!list_empty(&dev->devres_head)) {
		dev_crit(dev, "Resources present before probing\n");
		return -EBUSY;
	}

re_probe:
	dev->driver = drv;

	/* If using pinctrl, bind pins now before probing */
	ret = pinctrl_bind_pins(dev);
	if (ret)
		goto pinctrl_bind_failed;

	if (dev->bus->dma_configure) {
		ret = dev->bus->dma_configure(dev);
		if (ret)
			goto probe_failed;
	}

	if (driver_sysfs_add(dev)) {
		printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
			__func__, dev_name(dev));
		goto probe_failed;
	}

	if (dev->pm_domain && dev->pm_domain->activate) {
		ret = dev->pm_domain->activate(dev);
		if (ret)
			goto probe_failed;
	}

	if (dev->bus->probe) {
		ret = dev->bus->probe(dev);
		if (ret)
			goto probe_failed;
	} else if (drv->probe) {
		ret = drv->probe(dev);
		if (ret)
			goto probe_failed;
	}

	if (device_add_groups(dev, drv->dev_groups)) {
		dev_err(dev, "device_add_groups() failed\n");
		goto dev_groups_failed;
	}

	if (test_remove) {
		test_remove = false;

		device_remove_groups(dev, drv->dev_groups);

		if (dev->bus->remove)
			dev->bus->remove(dev);
		else if (drv->remove)
			drv->remove(dev);

		devres_release_all(dev);
		driver_sysfs_remove(dev);
		dev->driver = NULL;
		dev_set_drvdata(dev, NULL);
		if (dev->pm_domain && dev->pm_domain->dismiss)
			dev->pm_domain->dismiss(dev);
		pm_runtime_reinit(dev);

		goto re_probe;
	}

	pinctrl_init_done(dev);

	if (dev->pm_domain && dev->pm_domain->sync)
		dev->pm_domain->sync(dev);

	driver_bound(dev);
	ret = 1;
	pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
		 drv->bus->name, __func__, dev_name(dev), drv->name);
	goto done;

dev_groups_failed:
	if (dev->bus->remove)
		dev->bus->remove(dev);
	else if (drv->remove)
		drv->remove(dev);
probe_failed:
	if (dev->bus)
		blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
					     BUS_NOTIFY_DRIVER_NOT_BOUND, dev);
pinctrl_bind_failed:
	device_links_no_driver(dev);
	devres_release_all(dev);
	arch_teardown_dma_ops(dev);
	driver_sysfs_remove(dev);
	dev->driver = NULL;
	dev_set_drvdata(dev, NULL);
	if (dev->pm_domain && dev->pm_domain->dismiss)
		dev->pm_domain->dismiss(dev);
	pm_runtime_reinit(dev);
	dev_pm_set_driver_flags(dev, 0);

	switch (ret) {
	case -EPROBE_DEFER:
		/* Driver requested deferred probing */
		dev_dbg(dev, "Driver %s requests probe deferral\n", drv->name);
		driver_deferred_probe_add_trigger(dev, local_trigger_count);
		break;
	case -ENODEV:
	case -ENXIO:
		pr_debug("%s: probe of %s rejects match %d\n",
			 drv->name, dev_name(dev), ret);
		break;
	default:
		/* driver matched but the probe failed */
		printk(KERN_WARNING
		       "%s: probe of %s failed with error %d\n",
		       drv->name, dev_name(dev), ret);
	}
	/*
	 * Ignore errors returned by ->probe so that the next driver can try
	 * its luck.
	 */
	ret = 0;
done:
	atomic_dec(&probe_count);
	wake_up(&probe_waitqueue);
	return ret;
}

/*
 * For initcall_debug, show the driver probe time.
 */
static int really_probe_debug(struct device *dev, struct device_driver *drv)
{
	ktime_t calltime, delta, rettime;
	int ret;

	calltime = ktime_get();
	ret = really_probe(dev, drv);
	rettime = ktime_get();
	delta = ktime_sub(rettime, calltime);
	printk(KERN_DEBUG "probe of %s returned %d after %lld usecs\n",
	       dev_name(dev), ret, (s64) ktime_to_us(delta));
	return ret;
}

/**
 * driver_probe_done
 * Determine if the probe sequence is finished or not.
 *
 * Should somehow figure out how to use a semaphore, not an atomic variable...
 */
int driver_probe_done(void)
{
	pr_debug("%s: probe_count = %d\n", __func__,
		 atomic_read(&probe_count));
	if (atomic_read(&probe_count))
		return -EBUSY;
	return 0;
}

/**
 * wait_for_device_probe
 * Wait for device probing to be completed.
 */
void wait_for_device_probe(void)
{
	/* wait for the deferred probe workqueue to finish */
	flush_work(&deferred_probe_work);

	/* wait for the known devices to complete their probing */
	wait_event(probe_waitqueue, atomic_read(&probe_count) == 0);
	async_synchronize_full();
}
EXPORT_SYMBOL_GPL(wait_for_device_probe);

/**
 * driver_probe_device - attempt to bind device & driver together
 * @drv: driver to bind a device to
 * @dev: device to try to bind to the driver
 *
 * This function returns -ENODEV if the device is not registered,
 * 1 if the device is bound successfully and 0 otherwise.
 *
 * This function must be called with @dev lock held.  When called for a
 * USB interface, @dev->parent lock must be held as well.
 *
 * If the device has a parent, runtime-resume the parent before driver probing.
 */
int driver_probe_device(struct device_driver *drv, struct device *dev)
{
	int ret = 0;

	if (!device_is_registered(dev))
		return -ENODEV;

	pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
		 drv->bus->name, __func__, dev_name(dev), drv->name);

	pm_runtime_get_suppliers(dev);
	if (dev->parent)
		pm_runtime_get_sync(dev->parent);

	pm_runtime_barrier(dev);
	if (initcall_debug)
		ret = really_probe_debug(dev, drv);
	else
		ret = really_probe(dev, drv);
	pm_request_idle(dev);

	if (dev->parent)
		pm_runtime_put(dev->parent);

	pm_runtime_put_suppliers(dev);
	return ret;
}

static inline bool cmdline_requested_async_probing(const char *drv_name)
{
	return parse_option_str(async_probe_drv_names, drv_name);
}

/* The option format is "driver_async_probe=drv_name1,drv_name2,..." */
static int __init save_async_options(char *buf)
{
	if (strlen(buf) >= ASYNC_DRV_NAMES_MAX_LEN)
		printk(KERN_WARNING
			"Too long list of driver names for 'driver_async_probe'!\n");

	strlcpy(async_probe_drv_names, buf, ASYNC_DRV_NAMES_MAX_LEN);
	return 0;
}
__setup("driver_async_probe=", save_async_options);

bool driver_allows_async_probing(struct device_driver *drv)
{
	switch (drv->probe_type) {
	case PROBE_PREFER_ASYNCHRONOUS:
		return true;

	case PROBE_FORCE_SYNCHRONOUS:
		return false;

	default:
		if (cmdline_requested_async_probing(drv->name))
			return true;

		if (module_requested_async_probing(drv->owner))
			return true;

		return false;
	}
}

struct device_attach_data {
	struct device *dev;

	/*
	 * Indicates whether we are are considering asynchronous probing or
	 * not. Only initial binding after device or driver registration
	 * (including deferral processing) may be done asynchronously, the
	 * rest is always synchronous, as we expect it is being done by
	 * request from userspace.
	 */
	bool check_async;

	/*
	 * Indicates if we are binding synchronous or asynchronous drivers.
	 * When asynchronous probing is enabled we'll execute 2 passes
	 * over drivers: first pass doing synchronous probing and second
	 * doing asynchronous probing (if synchronous did not succeed -
	 * most likely because there was no driver requiring synchronous
	 * probing - and we found asynchronous driver during first pass).
	 * The 2 passes are done because we can't shoot asynchronous
	 * probe for given device and driver from bus_for_each_drv() since
	 * driver pointer is not guaranteed to stay valid once
	 * bus_for_each_drv() iterates to the next driver on the bus.
	 */
	bool want_async;

	/*
	 * We'll set have_async to 'true' if, while scanning for matching
	 * driver, we'll encounter one that requests asynchronous probing.
	 */
	bool have_async;
};

static int __device_attach_driver(struct device_driver *drv, void *_data)
{
	struct device_attach_data *data = _data;
	struct device *dev = data->dev;
	bool async_allowed;
	int ret;

	ret = driver_match_device(drv, dev);
	if (ret == 0) {
		/* no match */
		return 0;
	} else if (ret == -EPROBE_DEFER) {
		dev_dbg(dev, "Device match requests probe deferral\n");
		driver_deferred_probe_add(dev);
	} else if (ret < 0) {
		dev_dbg(dev, "Bus failed to match device: %d", ret);
		return ret;
	} /* ret > 0 means positive match */

	async_allowed = driver_allows_async_probing(drv);

	if (async_allowed)
		data->have_async = true;

	if (data->check_async && async_allowed != data->want_async)
		return 0;

	return driver_probe_device(drv, dev);
}

static void __device_attach_async_helper(void *_dev, async_cookie_t cookie)
{
	struct device *dev = _dev;
	struct device_attach_data data = {
		.dev		= dev,
		.check_async	= true,
		.want_async	= true,
	};

	device_lock(dev);

	/*
	 * Check if device has already been removed or claimed. This may
	 * happen with driver loading, device discovery/registration,
	 * and deferred probe processing happens all at once with
	 * multiple threads.
	 */
	if (dev->p->dead || dev->driver)
		goto out_unlock;

	if (dev->parent)
		pm_runtime_get_sync(dev->parent);

	bus_for_each_drv(dev->bus, NULL, &data, __device_attach_driver);
	dev_dbg(dev, "async probe completed\n");

	pm_request_idle(dev);

	if (dev->parent)
		pm_runtime_put(dev->parent);
out_unlock:
	device_unlock(dev);

	put_device(dev);
}

static int __device_attach(struct device *dev, bool allow_async)
{
	int ret = 0;

	device_lock(dev);
	if (dev->driver) {
		if (device_is_bound(dev)) {
			ret = 1;
			goto out_unlock;
		}
		ret = device_bind_driver(dev);
		if (ret == 0)
			ret = 1;
		else {
			dev->driver = NULL;
			ret = 0;
		}
	} else {
		struct device_attach_data data = {
			.dev = dev,
			.check_async = allow_async,
			.want_async = false,
		};

		if (dev->parent)
			pm_runtime_get_sync(dev->parent);

		ret = bus_for_each_drv(dev->bus, NULL, &data,
					__device_attach_driver);
		if (!ret && allow_async && data.have_async) {
			/*
			 * If we could not find appropriate driver
			 * synchronously and we are allowed to do
			 * async probes and there are drivers that
			 * want to probe asynchronously, we'll
			 * try them.
			 */
			dev_dbg(dev, "scheduling asynchronous probe\n");
			get_device(dev);
			async_schedule_dev(__device_attach_async_helper, dev);
		} else {
			pm_request_idle(dev);
		}

		if (dev->parent)
			pm_runtime_put(dev->parent);
	}
out_unlock:
	device_unlock(dev);
	return ret;
}

/**
 * device_attach - try to attach device to a driver.
 * @dev: device.
 *
 * Walk the list of drivers that the bus has and call
 * driver_probe_device() for each pair. If a compatible
 * pair is found, break out and return.
 *
 * Returns 1 if the device was bound to a driver;
 * 0 if no matching driver was found;
 * -ENODEV if the device is not registered.
 *
 * When called for a USB interface, @dev->parent lock must be held.
 */
int device_attach(struct device *dev)
{
	return __device_attach(dev, false);
}
EXPORT_SYMBOL_GPL(device_attach);

void device_initial_probe(struct device *dev)
{
	__device_attach(dev, true);
}

/*
 * __device_driver_lock - acquire locks needed to manipulate dev->drv
 * @dev: Device we will update driver info for
 * @parent: Parent device. Needed if the bus requires parent lock
 *
 * This function will take the required locks for manipulating dev->drv.
 * Normally this will just be the @dev lock, but when called for a USB
 * interface, @parent lock will be held as well.
 */
static void __device_driver_lock(struct device *dev, struct device *parent)
{
	if (parent && dev->bus->need_parent_lock)
		device_lock(parent);
	device_lock(dev);
}

/*
 * __device_driver_unlock - release locks needed to manipulate dev->drv
 * @dev: Device we will update driver info for
 * @parent: Parent device. Needed if the bus requires parent lock
 *
 * This function will release the required locks for manipulating dev->drv.
 * Normally this will just be the the @dev lock, but when called for a
 * USB interface, @parent lock will be released as well.
 */
static void __device_driver_unlock(struct device *dev, struct device *parent)
{
	device_unlock(dev);
	if (parent && dev->bus->need_parent_lock)
		device_unlock(parent);
}

/**
 * device_driver_attach - attach a specific driver to a specific device
 * @drv: Driver to attach
 * @dev: Device to attach it to
 *
 * Manually attach driver to a device. Will acquire both @dev lock and
 * @dev->parent lock if needed.
 */
int device_driver_attach(struct device_driver *drv, struct device *dev)
{
	int ret = 0;

	__device_driver_lock(dev, dev->parent);

	/*
	 * If device has been removed or someone has already successfully
	 * bound a driver before us just skip the driver probe call.
	 */
	if (!dev->p->dead && !dev->driver)
		ret = driver_probe_device(drv, dev);

	__device_driver_unlock(dev, dev->parent);

	return ret;
}

static void __driver_attach_async_helper(void *_dev, async_cookie_t cookie)
{
	struct device *dev = _dev;
	struct device_driver *drv;
	int ret = 0;

	__device_driver_lock(dev, dev->parent);

	drv = dev->p->async_driver;

	/*
	 * If device has been removed or someone has already successfully
	 * bound a driver before us just skip the driver probe call.
	 */
	if (!dev->p->dead && !dev->driver)
		ret = driver_probe_device(drv, dev);

	__device_driver_unlock(dev, dev->parent);

	dev_dbg(dev, "driver %s async attach completed: %d\n", drv->name, ret);

	put_device(dev);
}

static int __driver_attach(struct device *dev, void *data)
{
	struct device_driver *drv = data;
	int ret;

	/*
	 * Lock device and try to bind to it. We drop the error
	 * here and always return 0, because we need to keep trying
	 * to bind to devices and some drivers will return an error
	 * simply if it didn't support the device.
	 *
	 * driver_probe_device() will spit a warning if there
	 * is an error.
	 */

	ret = driver_match_device(drv, dev);
	if (ret == 0) {
		/* no match */
		return 0;
	} else if (ret == -EPROBE_DEFER) {
		dev_dbg(dev, "Device match requests probe deferral\n");
		driver_deferred_probe_add(dev);
	} else if (ret < 0) {
		dev_dbg(dev, "Bus failed to match device: %d", ret);
		return ret;
	} /* ret > 0 means positive match */

	if (driver_allows_async_probing(drv)) {
		/*
		 * Instead of probing the device synchronously we will
		 * probe it asynchronously to allow for more parallelism.
		 *
		 * We only take the device lock here in order to guarantee
		 * that the dev->driver and async_driver fields are protected
		 */
		dev_dbg(dev, "probing driver %s asynchronously\n", drv->name);
		device_lock(dev);
		if (!dev->driver) {
			get_device(dev);
			dev->p->async_driver = drv;
			async_schedule_dev(__driver_attach_async_helper, dev);
		}
		device_unlock(dev);
		return 0;
	}

	device_driver_attach(drv, dev);

	return 0;
}

/**
 * driver_attach - try to bind driver to devices.
 * @drv: driver.
 *
 * Walk the list of devices that the bus has on it and try to
 * match the driver with each one.  If driver_probe_device()
 * returns 0 and the @dev->driver is set, we've found a
 * compatible pair.
 */
int driver_attach(struct device_driver *drv)
{
	return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);
}
EXPORT_SYMBOL_GPL(driver_attach);

/*
 * __device_release_driver() must be called with @dev lock held.
 * When called for a USB interface, @dev->parent lock must be held as well.
 */
static void __device_release_driver(struct device *dev, struct device *parent)
{
	struct device_driver *drv;

	drv = dev->driver;
	if (drv) {
		while (device_links_busy(dev)) {
			__device_driver_unlock(dev, parent);

			device_links_unbind_consumers(dev);

			__device_driver_lock(dev, parent);
			/*
			 * A concurrent invocation of the same function might
			 * have released the driver successfully while this one
			 * was waiting, so check for that.
			 */
			if (dev->driver != drv)
				return;
		}

		pm_runtime_get_sync(dev);
		pm_runtime_clean_up_links(dev);

		driver_sysfs_remove(dev);

		if (dev->bus)
			blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
						     BUS_NOTIFY_UNBIND_DRIVER,
						     dev);

		pm_runtime_put_sync(dev);

		device_remove_groups(dev, drv->dev_groups);

		if (dev->bus && dev->bus->remove)
			dev->bus->remove(dev);
		else if (drv->remove)
			drv->remove(dev);

		device_links_driver_cleanup(dev);

		devres_release_all(dev);
		arch_teardown_dma_ops(dev);
		dev->driver = NULL;
		dev_set_drvdata(dev, NULL);
		if (dev->pm_domain && dev->pm_domain->dismiss)
			dev->pm_domain->dismiss(dev);
		pm_runtime_reinit(dev);
		dev_pm_set_driver_flags(dev, 0);

		klist_remove(&dev->p->knode_driver);
		device_pm_check_callbacks(dev);
		if (dev->bus)
			blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
						     BUS_NOTIFY_UNBOUND_DRIVER,
						     dev);

		kobject_uevent(&dev->kobj, KOBJ_UNBIND);
	}
}

void device_release_driver_internal(struct device *dev,
				    struct device_driver *drv,
				    struct device *parent)
{
	__device_driver_lock(dev, parent);

	if (!drv || drv == dev->driver)
		__device_release_driver(dev, parent);

	__device_driver_unlock(dev, parent);
}

/**
 * device_release_driver - manually detach device from driver.
 * @dev: device.
 *
 * Manually detach device from driver.
 * When called for a USB interface, @dev->parent lock must be held.
 *
 * If this function is to be called with @dev->parent lock held, ensure that
 * the device's consumers are unbound in advance or that their locks can be
 * acquired under the @dev->parent lock.
 */
void device_release_driver(struct device *dev)
{
	/*
	 * If anyone calls device_release_driver() recursively from
	 * within their ->remove callback for the same device, they
	 * will deadlock right here.
	 */
	device_release_driver_internal(dev, NULL, NULL);
}
EXPORT_SYMBOL_GPL(device_release_driver);

/**
 * device_driver_detach - detach driver from a specific device
 * @dev: device to detach driver from
 *
 * Detach driver from device. Will acquire both @dev lock and @dev->parent
 * lock if needed.
 */
void device_driver_detach(struct device *dev)
{
	device_release_driver_internal(dev, NULL, dev->parent);
}

/**
 * driver_detach - detach driver from all devices it controls.
 * @drv: driver.
 */
void driver_detach(struct device_driver *drv)
{
	struct device_private *dev_prv;
	struct device *dev;

	if (driver_allows_async_probing(drv))
		async_synchronize_full();

	for (;;) {
		spin_lock(&drv->p->klist_devices.k_lock);
		if (list_empty(&drv->p->klist_devices.k_list)) {
			spin_unlock(&drv->p->klist_devices.k_lock);
			break;
		}
		dev_prv = list_entry(drv->p->klist_devices.k_list.prev,
				     struct device_private,
				     knode_driver.n_node);
		dev = dev_prv->device;
		get_device(dev);
		spin_unlock(&drv->p->klist_devices.k_lock);
		device_release_driver_internal(dev, drv, dev->parent);
		put_device(dev);
	}
}