aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/base/power/main.c
blob: 03bde7524bc33fd32530ed37bf31240c8d36b8a8 (plain) (blame)
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
/*
 * drivers/base/power/main.c - Where the driver meets power management.
 *
 * Copyright (c) 2003 Patrick Mochel
 * Copyright (c) 2003 Open Source Development Lab
 *
 * This file is released under the GPLv2
 *
 *
 * The driver model core calls device_pm_add() when a device is registered.
 * This will intialize the embedded device_pm_info object in the device
 * and add it to the list of power-controlled devices. sysfs entries for
 * controlling device power management will also be added.
 *
 * A separate list is used for keeping track of power info, because the power
 * domain dependencies may differ from the ancestral dependencies that the
 * subsystem list maintains.
 */

#include <linux/device.h>
#include <linux/kallsyms.h>
#include <linux/mutex.h>
#include <linux/pm.h>
#include <linux/resume-trace.h>
#include <linux/rwsem.h>

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

/*
 * The entries in the dpm_list list are in a depth first order, simply
 * because children are guaranteed to be discovered after parents, and
 * are inserted at the back of the list on discovery.
 *
 * Since device_pm_add() may be called with a device semaphore held,
 * we must never try to acquire a device semaphore while holding
 * dpm_list_mutex.
 */

LIST_HEAD(dpm_list);

static DEFINE_MUTEX(dpm_list_mtx);

/*
 * Set once the preparation of devices for a PM transition has started, reset
 * before starting to resume devices.  Protected by dpm_list_mtx.
 */
static bool transition_started;

/**
 *	device_pm_lock - lock the list of active devices used by the PM core
 */
void device_pm_lock(void)
{
	mutex_lock(&dpm_list_mtx);
}

/**
 *	device_pm_unlock - unlock the list of active devices used by the PM core
 */
void device_pm_unlock(void)
{
	mutex_unlock(&dpm_list_mtx);
}

/**
 *	device_pm_add - add a device to the list of active devices
 *	@dev:	Device to be added to the list
 */
void device_pm_add(struct device *dev)
{
	pr_debug("PM: Adding info for %s:%s\n",
		 dev->bus ? dev->bus->name : "No Bus",
		 kobject_name(&dev->kobj));
	mutex_lock(&dpm_list_mtx);
	if (dev->parent) {
		if (dev->parent->power.status >= DPM_SUSPENDING)
			dev_warn(dev, "parent %s should not be sleeping\n",
				dev->parent->bus_id);
	} else if (transition_started) {
		/*
		 * We refuse to register parentless devices while a PM
		 * transition is in progress in order to avoid leaving them
		 * unhandled down the road
		 */
		WARN_ON(true);
	}

	list_add_tail(&dev->power.entry, &dpm_list);
	mutex_unlock(&dpm_list_mtx);
}

/**
 *	device_pm_remove - remove a device from the list of active devices
 *	@dev:	Device to be removed from the list
 *
 *	This function also removes the device's PM-related sysfs attributes.
 */
void device_pm_remove(struct device *dev)
{
	pr_debug("PM: Removing info for %s:%s\n",
		 dev->bus ? dev->bus->name : "No Bus",
		 kobject_name(&dev->kobj));
	mutex_lock(&dpm_list_mtx);
	list_del_init(&dev->power.entry);
	mutex_unlock(&dpm_list_mtx);
}

/**
 *	pm_op - execute the PM operation appropiate for given PM event
 *	@dev:	Device.
 *	@ops:	PM operations to choose from.
 *	@state:	PM transition of the system being carried out.
 */
static int pm_op(struct device *dev, struct pm_ops *ops, pm_message_t state)
{
	int error = 0;

	switch (state.event) {
#ifdef CONFIG_SUSPEND
	case PM_EVENT_SUSPEND:
		if (ops->suspend) {
			error = ops->suspend(dev);
			suspend_report_result(ops->suspend, error);
		}
		break;
	case PM_EVENT_RESUME:
		if (ops->resume) {
			error = ops->resume(dev);
			suspend_report_result(ops->resume, error);
		}
		break;
#endif /* CONFIG_SUSPEND */
#ifdef CONFIG_HIBERNATION
	case PM_EVENT_FREEZE:
	case PM_EVENT_QUIESCE:
		if (ops->freeze) {
			error = ops->freeze(dev);
			suspend_report_result(ops->freeze, error);
		}
		break;
	case PM_EVENT_HIBERNATE:
		if (ops->poweroff) {
			error = ops->poweroff(dev);
			suspend_report_result(ops->poweroff, error);
		}
		break;
	case PM_EVENT_THAW:
	case PM_EVENT_RECOVER:
		if (ops->thaw) {
			error = ops->thaw(dev);
			suspend_report_result(ops->thaw, error);
		}
		break;
	case PM_EVENT_RESTORE:
		if (ops->restore) {
			error = ops->restore(dev);
			suspend_report_result(ops->restore, error);
		}
		break;
#endif /* CONFIG_HIBERNATION */
	default:
		error = -EINVAL;
	}
	return error;
}

/**
 *	pm_noirq_op - execute the PM operation appropiate for given PM event
 *	@dev:	Device.
 *	@ops:	PM operations to choose from.
 *	@state: PM transition of the system being carried out.
 *
 *	The operation is executed with interrupts disabled by the only remaining
 *	functional CPU in the system.
 */
static int pm_noirq_op(struct device *dev, struct pm_ext_ops *ops,
			pm_message_t state)
{
	int error = 0;

	switch (state.event) {
#ifdef CONFIG_SUSPEND
	case PM_EVENT_SUSPEND:
		if (ops->suspend_noirq) {
			error = ops->suspend_noirq(dev);
			suspend_report_result(ops->suspend_noirq, error);
		}
		break;
	case PM_EVENT_RESUME:
		if (ops->resume_noirq) {
			error = ops->resume_noirq(dev);
			suspend_report_result(ops->resume_noirq, error);
		}
		break;
#endif /* CONFIG_SUSPEND */
#ifdef CONFIG_HIBERNATION
	case PM_EVENT_FREEZE:
	case PM_EVENT_QUIESCE:
		if (ops->freeze_noirq) {
			error = ops->freeze_noirq(dev);
			suspend_report_result(ops->freeze_noirq, error);
		}
		break;
	case PM_EVENT_HIBERNATE:
		if (ops->poweroff_noirq) {
			error = ops->poweroff_noirq(dev);
			suspend_report_result(ops->poweroff_noirq, error);
		}
		break;
	case PM_EVENT_THAW:
	case PM_EVENT_RECOVER:
		if (ops->thaw_noirq) {
			error = ops->thaw_noirq(dev);
			suspend_report_result(ops->thaw_noirq, error);
		}
		break;
	case PM_EVENT_RESTORE:
		if (ops->restore_noirq) {
			error = ops->restore_noirq(dev);
			suspend_report_result(ops->restore_noirq, error);
		}
		break;
#endif /* CONFIG_HIBERNATION */
	default:
		error = -EINVAL;
	}
	return error;
}

static char *pm_verb(int event)
{
	switch (event) {
	case PM_EVENT_SUSPEND:
		return "suspend";
	case PM_EVENT_RESUME:
		return "resume";
	case PM_EVENT_FREEZE:
		return "freeze";
	case PM_EVENT_QUIESCE:
		return "quiesce";
	case PM_EVENT_HIBERNATE:
		return "hibernate";
	case PM_EVENT_THAW:
		return "thaw";
	case PM_EVENT_RESTORE:
		return "restore";
	case PM_EVENT_RECOVER:
		return "recover";
	default:
		return "(unknown PM event)";
	}
}

static void pm_dev_dbg(struct device *dev, pm_message_t state, char *info)
{
	dev_dbg(dev, "%s%s%s\n", info, pm_verb(state.event),
		((state.event & PM_EVENT_SLEEP) && device_may_wakeup(dev)) ?
		", may wakeup" : "");
}

static void pm_dev_err(struct device *dev, pm_message_t state, char *info,
			int error)
{
	printk(KERN_ERR "PM: Device %s failed to %s%s: error %d\n",
		kobject_name(&dev->kobj), pm_verb(state.event), info, error);
}

/*------------------------- Resume routines -------------------------*/

/**
 *	resume_device_noirq - Power on one device (early resume).
 *	@dev:	Device.
 *	@state: PM transition of the system being carried out.
 *
 *	Must be called with interrupts disabled.
 */
static int resume_device_noirq(struct device *dev, pm_message_t state)
{
	int error = 0;

	TRACE_DEVICE(dev);
	TRACE_RESUME(0);

	if (!dev->bus)
		goto End;

	if (dev->bus->pm) {
		pm_dev_dbg(dev, state, "EARLY ");
		error = pm_noirq_op(dev, dev->bus->pm, state);
	} else if (dev->bus->resume_early) {
		pm_dev_dbg(dev, state, "legacy EARLY ");
		error = dev->bus->resume_early(dev);
	}
 End:
	TRACE_RESUME(error);
	return error;
}

/**
 *	dpm_power_up - Power on all regular (non-sysdev) devices.
 *	@state: PM transition of the system being carried out.
 *
 *	Execute the appropriate "noirq resume" callback for all devices marked
 *	as DPM_OFF_IRQ.
 *
 *	Must be called with interrupts disabled and only one CPU running.
 */
static void dpm_power_up(pm_message_t state)
{
	struct device *dev;

	list_for_each_entry(dev, &dpm_list, power.entry)
		if (dev->power.status > DPM_OFF) {
			int error;

			dev->power.status = DPM_OFF;
			error = resume_device_noirq(dev, state);
			if (error)
				pm_dev_err(dev, state, " early", error);
		}
}

/**
 *	device_power_up - Turn on all devices that need special attention.
 *	@state: PM transition of the system being carried out.
 *
 *	Power on system devices, then devices that required we shut them down
 *	with interrupts disabled.
 *
 *	Must be called with interrupts disabled.
 */
void device_power_up(pm_message_t state)
{
	sysdev_resume();
	dpm_power_up(state);
}
EXPORT_SYMBOL_GPL(device_power_up);

/**
 *	resume_device - Restore state for one device.
 *	@dev:	Device.
 *	@state: PM transition of the system being carried out.
 */
static int resume_device(struct device *dev, pm_message_t state)
{
	int error = 0;

	TRACE_DEVICE(dev);
	TRACE_RESUME(0);

	down(&dev->sem);

	if (dev->bus) {
		if (dev->bus->pm) {
			pm_dev_dbg(dev, state, "");
			error = pm_op(dev, &dev->bus->pm->base, state);
		} else if (dev->bus->resume) {
			pm_dev_dbg(dev, state, "legacy ");
			error = dev->bus->resume(dev);
		}
		if (error)
			goto End;
	}

	if (dev->type) {
		if (dev->type->pm) {
			pm_dev_dbg(dev, state, "type ");
			error = pm_op(dev, dev->type->pm, state);
		} else if (dev->type->resume) {
			pm_dev_dbg(dev, state, "legacy type ");
			error = dev->type->resume(dev);
		}
		if (error)
			goto End;
	}

	if (dev->class) {
		if (dev->class->pm) {
			pm_dev_dbg(dev, state, "class ");
			error = pm_op(dev, dev->class->pm, state);
		} else if (dev->class->resume) {
			pm_dev_dbg(dev, state, "legacy class ");
			error = dev->class->resume(dev);
		}
	}
 End:
	up(&dev->sem);

	TRACE_RESUME(error);
	return error;
}

/**
 *	dpm_resume - Resume every device.
 *	@state: PM transition of the system being carried out.
 *
 *	Execute the appropriate "resume" callback for all devices the status of
 *	which indicates that they are inactive.
 */
static void dpm_resume(pm_message_t state)
{
	struct list_head list;

	INIT_LIST_HEAD(&list);
	mutex_lock(&dpm_list_mtx);
	transition_started = false;
	while (!list_empty(&dpm_list)) {
		struct device *dev = to_device(dpm_list.next);

		get_device(dev);
		if (dev->power.status >= DPM_OFF) {
			int error;

			dev->power.status = DPM_RESUMING;
			mutex_unlock(&dpm_list_mtx);

			error = resume_device(dev, state);

			mutex_lock(&dpm_list_mtx);
			if (error)
				pm_dev_err(dev, state, "", error);
		} else if (dev->power.status == DPM_SUSPENDING) {
			/* Allow new children of the device to be registered */
			dev->power.status = DPM_RESUMING;
		}
		if (!list_empty(&dev->power.entry))
			list_move_tail(&dev->power.entry, &list);
		put_device(dev);
	}
	list_splice(&list, &dpm_list);
	mutex_unlock(&dpm_list_mtx);
}

/**
 *	complete_device - Complete a PM transition for given device
 *	@dev:	Device.
 *	@state: PM transition of the system being carried out.
 */
static void complete_device(struct device *dev, pm_message_t state)
{
	down(&dev->sem);

	if (dev->class && dev->class->pm && dev->class->pm->complete) {
		pm_dev_dbg(dev, state, "completing class ");
		dev->class->pm->complete(dev);
	}

	if (dev->type && dev->type->pm && dev->type->pm->complete) {
		pm_dev_dbg(dev, state, "completing type ");
		dev->type->pm->complete(dev);
	}

	if (dev->bus && dev->bus->pm && dev->bus->pm->base.complete) {
		pm_dev_dbg(dev, state, "completing ");
		dev->bus->pm->base.complete(dev);
	}

	up(&dev->sem);
}

/**
 *	dpm_complete - Complete a PM transition for all devices.
 *	@state: PM transition of the system being carried out.
 *
 *	Execute the ->complete() callbacks for all devices that are not marked
 *	as DPM_ON.
 */
static void dpm_complete(pm_message_t state)
{
	struct list_head list;

	INIT_LIST_HEAD(&list);
	mutex_lock(&dpm_list_mtx);
	while (!list_empty(&dpm_list)) {
		struct device *dev = to_device(dpm_list.prev);

		get_device(dev);
		if (dev->power.status > DPM_ON) {
			dev->power.status = DPM_ON;
			mutex_unlock(&dpm_list_mtx);

			complete_device(dev, state);

			mutex_lock(&dpm_list_mtx);
		}
		if (!list_empty(&dev->power.entry))
			list_move(&dev->power.entry, &list);
		put_device(dev);
	}
	list_splice(&list, &dpm_list);
	mutex_unlock(&dpm_list_mtx);
}

/**
 *	device_resume - Restore state of each device in system.
 *	@state: PM transition of the system being carried out.
 *
 *	Resume all the devices, unlock them all, and allow new
 *	devices to be registered once again.
 */
void device_resume(pm_message_t state)
{
	might_sleep();
	dpm_resume(state);
	dpm_complete(state);
}
EXPORT_SYMBOL_GPL(device_resume);


/*------------------------- Suspend routines -------------------------*/

/**
 *	resume_event - return a PM message representing the resume event
 *	               corresponding to given sleep state.
 *	@sleep_state: PM message representing a sleep state.
 */
static pm_message_t resume_event(pm_message_t sleep_state)
{
	switch (sleep_state.event) {
	case PM_EVENT_SUSPEND:
		return PMSG_RESUME;
	case PM_EVENT_FREEZE:
	case PM_EVENT_QUIESCE:
		return PMSG_RECOVER;
	case PM_EVENT_HIBERNATE:
		return PMSG_RESTORE;
	}
	return PMSG_ON;
}

/**
 *	suspend_device_noirq - Shut down one device (late suspend).
 *	@dev:	Device.
 *	@state: PM transition of the system being carried out.
 *
 *	This is called with interrupts off and only a single CPU running.
 */
static int suspend_device_noirq(struct device *dev, pm_message_t state)
{
	int error = 0;

	if (!dev->bus)
		return 0;

	if (dev->bus->pm) {
		pm_dev_dbg(dev, state, "LATE ");
		error = pm_noirq_op(dev, dev->bus->pm, state);
	} else if (dev->bus->suspend_late) {
		pm_dev_dbg(dev, state, "legacy LATE ");
		error = dev->bus->suspend_late(dev, state);
		suspend_report_result(dev->bus->suspend_late, error);
	}
	return error;
}

/**
 *	device_power_down - Shut down special devices.
 *	@state: PM transition of the system being carried out.
 *
 *	Power down devices that require interrupts to be disabled.
 *	Then power down system devices.
 *
 *	Must be called with interrupts disabled and only one CPU running.
 */
int device_power_down(pm_message_t state)
{
	struct device *dev;
	int error = 0;

	list_for_each_entry_reverse(dev, &dpm_list, power.entry) {
		error = suspend_device_noirq(dev, state);
		if (error) {
			pm_dev_err(dev, state, " late", error);
			break;
		}
		dev->power.status = DPM_OFF_IRQ;
	}
	if (!error)
		error = sysdev_suspend(state);
	if (error)
		dpm_power_up(resume_event(state));
	return error;
}
EXPORT_SYMBOL_GPL(device_power_down);

/**
 *	suspend_device - Save state of one device.
 *	@dev:	Device.
 *	@state: PM transition of the system being carried out.
 */
static int suspend_device(struct device *dev, pm_message_t state)
{
	int error = 0;

	down(&dev->sem);

	if (dev->class) {
		if (dev->class->pm) {
			pm_dev_dbg(dev, state, "class ");
			error = pm_op(dev, dev->class->pm, state);
		} else if (dev->class->suspend) {
			pm_dev_dbg(dev, state, "legacy class ");
			error = dev->class->suspend(dev, state);
			suspend_report_result(dev->class->suspend, error);
		}
		if (error)
			goto End;
	}

	if (dev->type) {
		if (dev->type->pm) {
			pm_dev_dbg(dev, state, "type ");
			error = pm_op(dev, dev->type->pm, state);
		} else if (dev->type->suspend) {
			pm_dev_dbg(dev, state, "legacy type ");
			error = dev->type->suspend(dev, state);
			suspend_report_result(dev->type->suspend, error);
		}
		if (error)
			goto End;
	}

	if (dev->bus) {
		if (dev->bus->pm) {
			pm_dev_dbg(dev, state, "");
			error = pm_op(dev, &dev->bus->pm->base, state);
		} else if (dev->bus->suspend) {
			pm_dev_dbg(dev, state, "legacy ");
			error = dev->bus->suspend(dev, state);
			suspend_report_result(dev->bus->suspend, error);
		}
	}
 End:
	up(&dev->sem);

	return error;
}

/**
 *	dpm_suspend - Suspend every device.
 *	@state: PM transition of the system being carried out.
 *
 *	Execute the appropriate "suspend" callbacks for all devices.
 */
static int dpm_suspend(pm_message_t state)
{
	struct list_head list;
	int error = 0;

	INIT_LIST_HEAD(&list);
	mutex_lock(&dpm_list_mtx);
	while (!list_empty(&dpm_list)) {
		struct device *dev = to_device(dpm_list.prev);

		get_device(dev);
		mutex_unlock(&dpm_list_mtx);

		error = suspend_device(dev, state);

		mutex_lock(&dpm_list_mtx);
		if (error) {
			pm_dev_err(dev, state, "", error);
			put_device(dev);
			break;
		}
		dev->power.status = DPM_OFF;
		if (!list_empty(&dev->power.entry))
			list_move(&dev->power.entry, &list);
		put_device(dev);
	}
	list_splice(&list, dpm_list.prev);
	mutex_unlock(&dpm_list_mtx);
	return error;
}

/**
 *	prepare_device - Execute the ->prepare() callback(s) for given device.
 *	@dev:	Device.
 *	@state: PM transition of the system being carried out.
 */
static int prepare_device(struct device *dev, pm_message_t state)
{
	int error = 0;

	down(&dev->sem);

	if (dev->bus && dev->bus->pm && dev->bus->pm->base.prepare) {
		pm_dev_dbg(dev, state, "preparing ");
		error = dev->bus->pm->base.prepare(dev);
		suspend_report_result(dev->bus->pm->base.prepare, error);
		if (error)
			goto End;
	}

	if (dev->type && dev->type->pm && dev->type->pm->prepare) {
		pm_dev_dbg(dev, state, "preparing type ");
		error = dev->type->pm->prepare(dev);
		suspend_report_result(dev->type->pm->prepare, error);
		if (error)
			goto End;
	}

	if (dev->class && dev->class->pm && dev->class->pm->prepare) {
		pm_dev_dbg(dev, state, "preparing class ");
		error = dev->class->pm->prepare(dev);
		suspend_report_result(dev->class->pm->prepare, error);
	}
 End:
	up(&dev->sem);

	return error;
}

/**
 *	dpm_prepare - Prepare all devices for a PM transition.
 *	@state: PM transition of the system being carried out.
 *
 *	Execute the ->prepare() callback for all devices.
 */
static int dpm_prepare(pm_message_t state)
{
	struct list_head list;
	int error = 0;

	INIT_LIST_HEAD(&list);
	mutex_lock(&dpm_list_mtx);
	transition_started = true;
	while (!list_empty(&dpm_list)) {
		struct device *dev = to_device(dpm_list.next);

		get_device(dev);
		dev->power.status = DPM_PREPARING;
		mutex_unlock(&dpm_list_mtx);

		error = prepare_device(dev, state);

		mutex_lock(&dpm_list_mtx);
		if (error) {
			dev->power.status = DPM_ON;
			if (error == -EAGAIN) {
				put_device(dev);
				continue;
			}
			printk(KERN_ERR "PM: Failed to prepare device %s "
				"for power transition: error %d\n",
				kobject_name(&dev->kobj), error);
			put_device(dev);
			break;
		}
		dev->power.status = DPM_SUSPENDING;
		if (!list_empty(&dev->power.entry))
			list_move_tail(&dev->power.entry, &list);
		put_device(dev);
	}
	list_splice(&list, &dpm_list);
	mutex_unlock(&dpm_list_mtx);
	return error;
}

/**
 *	device_suspend - Save state and stop all devices in system.
 *	@state: PM transition of the system being carried out.
 *
 *	Prepare and suspend all devices.
 */
int device_suspend(pm_message_t state)
{
	int error;

	might_sleep();
	error = dpm_prepare(state);
	if (!error)
		error = dpm_suspend(state);
	return error;
}
EXPORT_SYMBOL_GPL(device_suspend);

void __suspend_report_result(const char *function, void *fn, int ret)
{
	if (ret)
		printk(KERN_ERR "%s(): %pF returns %d\n", function, fn, ret);
}
EXPORT_SYMBOL_GPL(__suspend_report_result);