summaryrefslogtreecommitdiffstats
path: root/kernel/power/main.c
blob: d6140ed15d0b17098e8e28ec981e33759a26790a (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 * kernel/power/main.c - PM subsystem core functionality.
 *
 * Copyright (c) 2003 Patrick Mochel
 * Copyright (c) 2003 Open Source Development Lab
 */

#include <linux/export.h>
#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/pm-trace.h>
#include <linux/workqueue.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/suspend.h>
#include <linux/syscalls.h>
#include <linux/pm_runtime.h>

#include "power.h"

#ifdef CONFIG_PM_SLEEP

void lock_system_sleep(void)
{
	current->flags |= PF_FREEZER_SKIP;
	mutex_lock(&system_transition_mutex);
}
EXPORT_SYMBOL_GPL(lock_system_sleep);

void unlock_system_sleep(void)
{
	/*
	 * Don't use freezer_count() because we don't want the call to
	 * try_to_freeze() here.
	 *
	 * Reason:
	 * Fundamentally, we just don't need it, because freezing condition
	 * doesn't come into effect until we release the
	 * system_transition_mutex lock, since the freezer always works with
	 * system_transition_mutex held.
	 *
	 * More importantly, in the case of hibernation,
	 * unlock_system_sleep() gets called in snapshot_read() and
	 * snapshot_write() when the freezing condition is still in effect.
	 * Which means, if we use try_to_freeze() here, it would make them
	 * enter the refrigerator, thus causing hibernation to lockup.
	 */
	current->flags &= ~PF_FREEZER_SKIP;
	mutex_unlock(&system_transition_mutex);
}
EXPORT_SYMBOL_GPL(unlock_system_sleep);

void ksys_sync_helper(void)
{
	ktime_t start;
	long elapsed_msecs;

	start = ktime_get();
	ksys_sync();
	elapsed_msecs = ktime_to_ms(ktime_sub(ktime_get(), start));
	pr_info("Filesystems sync: %ld.%03ld seconds\n",
		elapsed_msecs / MSEC_PER_SEC, elapsed_msecs % MSEC_PER_SEC);
}
EXPORT_SYMBOL_GPL(ksys_sync_helper);

/* Routines for PM-transition notifications */

static BLOCKING_NOTIFIER_HEAD(pm_chain_head);

int register_pm_notifier(struct notifier_block *nb)
{
	return blocking_notifier_chain_register(&pm_chain_head, nb);
}
EXPORT_SYMBOL_GPL(register_pm_notifier);

int unregister_pm_notifier(struct notifier_block *nb)
{
	return blocking_notifier_chain_unregister(&pm_chain_head, nb);
}
EXPORT_SYMBOL_GPL(unregister_pm_notifier);

int pm_notifier_call_chain_robust(unsigned long val_up, unsigned long val_down)
{
	int ret;

	ret = blocking_notifier_call_chain_robust(&pm_chain_head, val_up, val_down, NULL);

	return notifier_to_errno(ret);
}

int pm_notifier_call_chain(unsigned long val)
{
	return blocking_notifier_call_chain(&pm_chain_head, val, NULL);
}

/* If set, devices may be suspended and resumed asynchronously. */
int pm_async_enabled = 1;

static ssize_t pm_async_show(struct kobject *kobj, struct kobj_attribute *attr,
			     char *buf)
{
	return sprintf(buf, "%d\n", pm_async_enabled);
}

static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
			      const char *buf, size_t n)
{
	unsigned long val;

	if (kstrtoul(buf, 10, &val))
		return -EINVAL;

	if (val > 1)
		return -EINVAL;

	pm_async_enabled = val;
	return n;
}

power_attr(pm_async);

#ifdef CONFIG_SUSPEND
static ssize_t mem_sleep_show(struct kobject *kobj, struct kobj_attribute *attr,
			      char *buf)
{
	char *s = buf;
	suspend_state_t i;

	for (i = PM_SUSPEND_MIN; i < PM_SUSPEND_MAX; i++)
		if (mem_sleep_states[i]) {
			const char *label = mem_sleep_states[i];

			if (mem_sleep_current == i)
				s += sprintf(s, "[%s] ", label);
			else
				s += sprintf(s, "%s ", label);
		}

	/* Convert the last space to a newline if needed. */
	if (s != buf)
		*(s-1) = '\n';

	return (s - buf);
}

static suspend_state_t decode_suspend_state(const char *buf, size_t n)
{
	suspend_state_t state;
	char *p;
	int len;

	p = memchr(buf, '\n', n);
	len = p ? p - buf : n;

	for (state = PM_SUSPEND_MIN; state < PM_SUSPEND_MAX; state++) {
		const char *label = mem_sleep_states[state];

		if (label && len == strlen(label) && !strncmp(buf, label, len))
			return state;
	}

	return PM_SUSPEND_ON;
}

static ssize_t mem_sleep_store(struct kobject *kobj, struct kobj_attribute *attr,
			       const char *buf, size_t n)
{
	suspend_state_t state;
	int error;

	error = pm_autosleep_lock();
	if (error)
		return error;

	if (pm_autosleep_state() > PM_SUSPEND_ON) {
		error = -EBUSY;
		goto out;
	}

	state = decode_suspend_state(buf, n);
	if (state < PM_SUSPEND_MAX && state > PM_SUSPEND_ON)
		mem_sleep_current = state;
	else
		error = -EINVAL;

 out:
	pm_autosleep_unlock();
	return error ? error : n;
}

power_attr(mem_sleep);

/*
 * sync_on_suspend: invoke ksys_sync_helper() before suspend.
 *
 * show() returns whether ksys_sync_helper() is invoked before suspend.
 * store() accepts 0 or 1.  0 disables ksys_sync_helper() and 1 enables it.
 */
bool sync_on_suspend_enabled = !IS_ENABLED(CONFIG_SUSPEND_SKIP_SYNC);

static ssize_t sync_on_suspend_show(struct kobject *kobj,
				   struct kobj_attribute *attr, char *buf)
{
	return sprintf(buf, "%d\n", sync_on_suspend_enabled);
}

static ssize_t sync_on_suspend_store(struct kobject *kobj,
				    struct kobj_attribute *attr,
				    const char *buf, size_t n)
{
	unsigned long val;

	if (kstrtoul(buf, 10, &val))
		return -EINVAL;

	if (val > 1)
		return -EINVAL;

	sync_on_suspend_enabled = !!val;
	return n;
}

power_attr(sync_on_suspend);
#endif /* CONFIG_SUSPEND */

#ifdef CONFIG_PM_SLEEP_DEBUG
int pm_test_level = TEST_NONE;

static const char * const pm_tests[__TEST_AFTER_LAST] = {
	[TEST_NONE] = "none",
	[TEST_CORE] = "core",
	[TEST_CPUS] = "processors",
	[TEST_PLATFORM] = "platform",
	[TEST_DEVICES] = "devices",
	[TEST_FREEZER] = "freezer",
};

static ssize_t pm_test_show(struct kobject *kobj, struct kobj_attribute *attr,
				char *buf)
{
	char *s = buf;
	int level;

	for (level = TEST_FIRST; level <= TEST_MAX; level++)
		if (pm_tests[level]) {
			if (level == pm_test_level)
				s += sprintf(s, "[%s] ", pm_tests[level]);
			else
				s += sprintf(s, "%s ", pm_tests[level]);
		}

	if (s != buf)
		/* convert the last space to a newline */
		*(s-1) = '\n';

	return (s - buf);
}

static ssize_t pm_test_store(struct kobject *kobj, struct kobj_attribute *attr,
				const char *buf, size_t n)
{
	const char * const *s;
	int level;
	char *p;
	int len;
	int error = -EINVAL;

	p = memchr(buf, '\n', n);
	len = p ? p - buf : n;

	lock_system_sleep();

	level = TEST_FIRST;
	for (s = &pm_tests[level]; level <= TEST_MAX; s++, level++)
		if (*s && len == strlen(*s) && !strncmp(buf, *s, len)) {
			pm_test_level = level;
			error = 0;
			break;
		}

	unlock_system_sleep();

	return error ? error : n;
}

power_attr(pm_test);
#endif /* CONFIG_PM_SLEEP_DEBUG */

static char *suspend_step_name(enum suspend_stat_step step)
{
	switch (step) {
	case SUSPEND_FREEZE:
		return "freeze";
	case SUSPEND_PREPARE:
		return "prepare";
	case SUSPEND_SUSPEND:
		return "suspend";
	case SUSPEND_SUSPEND_NOIRQ:
		return "suspend_noirq";
	case SUSPEND_RESUME_NOIRQ:
		return "resume_noirq";
	case SUSPEND_RESUME:
		return "resume";
	default:
		return "";
	}
}

#define suspend_attr(_name)					\
static ssize_t _name##_show(struct kobject *kobj,		\
		struct kobj_attribute *attr, char *buf)		\
{								\
	return sprintf(buf, "%d\n", suspend_stats._name);	\
}								\
static struct kobj_attribute _name = __ATTR_RO(_name)

suspend_attr(success);
suspend_attr(fail);
suspend_attr(failed_freeze);
suspend_attr(failed_prepare);
suspend_attr(failed_suspend);
suspend_attr(failed_suspend_late);
suspend_attr(failed_suspend_noirq);
suspend_attr(failed_resume);
suspend_attr(failed_resume_early);
suspend_attr(failed_resume_noirq);

static ssize_t last_failed_dev_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	int index;
	char *last_failed_dev = NULL;

	index = suspend_stats.last_failed_dev + REC_FAILED_NUM - 1;
	index %= REC_FAILED_NUM;
	last_failed_dev = suspend_stats.failed_devs[index];

	return sprintf(buf, "%s\n", last_failed_dev);
}
static struct kobj_attribute last_failed_dev = __ATTR_RO(last_failed_dev);

static ssize_t last_failed_errno_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	int index;
	int last_failed_errno;

	index = suspend_stats.last_failed_errno + REC_FAILED_NUM - 1;
	index %= REC_FAILED_NUM;
	last_failed_errno = suspend_stats.errno[index];

	return sprintf(buf, "%d\n", last_failed_errno);
}
static struct kobj_attribute last_failed_errno = __ATTR_RO(last_failed_errno);

static ssize_t last_failed_step_show(struct kobject *kobj,
		struct kobj_attribute *attr, char *buf)
{
	int index;
	enum suspend_stat_step step;
	char *last_failed_step = NULL;

	index = suspend_stats.last_failed_step + REC_FAILED_NUM - 1;
	index %= REC_FAILED_NUM;
	step = suspend_stats.failed_steps[index];
	last_failed_step = suspend_step_name(step);

	return sprintf(buf, "%s\n", last_failed_step);
}
static struct kobj_attribute last_failed_step = __ATTR_RO(last_failed_step);

static struct attribute *suspend_attrs[] = {
	&success.attr,
	&fail.attr,
	&failed_freeze.attr,
	&failed_prepare.attr,
	&failed_suspend.attr,
	&failed_suspend_late.attr,
	&failed_suspend_noirq.attr,
	&failed_resume.attr,
	&failed_resume_early.attr,
	&failed_resume_noirq.attr,
	&last_failed_dev.attr,
	&last_failed_errno.attr,
	&last_failed_step.attr,
	NULL,
};

static struct attribute_group suspend_attr_group = {
	.name = "suspend_stats",
	.attrs = suspend_attrs,
};

#ifdef CONFIG_DEBUG_FS
static int suspend_stats_show(struct seq_file *s, void *unused)
{
	int i, index, last_dev, last_errno, last_step;

	last_dev = suspend_stats.last_failed_dev + REC_FAILED_NUM - 1;
	last_dev %= REC_FAILED_NUM;
	last_errno = suspend_stats.last_failed_errno + REC_FAILED_NUM - 1;
	last_errno %= REC_FAILED_NUM;
	last_step = suspend_stats.last_failed_step + REC_FAILED_NUM - 1;
	last_step %= REC_FAILED_NUM;
	seq_printf(s, "%s: %d\n%s: %d\n%s: %d\n%s: %d\n%s: %d\n"
			"%s: %d\n%s: %d\n%s: %d\n%s: %d\n%s: %d\n",
			"success", suspend_stats.success,
			"fail", suspend_stats.fail,
			"failed_freeze", suspend_stats.failed_freeze,
			"failed_prepare", suspend_stats.failed_prepare,
			"failed_suspend", suspend_stats.failed_suspend,
			"failed_suspend_late",
				suspend_stats.failed_suspend_late,
			"failed_suspend_noirq",
				suspend_stats.failed_suspend_noirq,
			"failed_resume", suspend_stats.failed_resume,
			"failed_resume_early",
				suspend_stats.failed_resume_early,
			"failed_resume_noirq",
				suspend_stats.failed_resume_noirq);
	seq_printf(s,	"failures:\n  last_failed_dev:\t%-s\n",
			suspend_stats.failed_devs[last_dev]);
	for (i = 1; i < REC_FAILED_NUM; i++) {
		index = last_dev + REC_FAILED_NUM - i;
		index %= REC_FAILED_NUM;
		seq_printf(s, "\t\t\t%-s\n",
			suspend_stats.failed_devs[index]);
	}
	seq_printf(s,	"  last_failed_errno:\t%-d\n",
			suspend_stats.errno[last_errno]);
	for (i = 1; i < REC_FAILED_NUM; i++) {
		index = last_errno + REC_FAILED_NUM - i;
		index %= REC_FAILED_NUM;
		seq_printf(s, "\t\t\t%-d\n",
			suspend_stats.errno[index]);
	}
	seq_printf(s,	"  last_failed_step:\t%-s\n",
			suspend_step_name(
				suspend_stats.failed_steps[last_step]));
	for (i = 1; i < REC_FAILED_NUM; i++) {
		index = last_step + REC_FAILED_NUM - i;
		index %= REC_FAILED_NUM;
		seq_printf(s, "\t\t\t%-s\n",
			suspend_step_name(
				suspend_stats.failed_steps[index]));
	}

	return 0;
}
DEFINE_SHOW_ATTRIBUTE(suspend_stats);

static int __init pm_debugfs_init(void)
{
	debugfs_create_file("suspend_stats", S_IFREG | S_IRUGO,
			NULL, NULL, &suspend_stats_fops);
	return 0;
}

late_initcall(pm_debugfs_init);
#endif /* CONFIG_DEBUG_FS */

#endif /* CONFIG_PM_SLEEP */

#ifdef CONFIG_PM_SLEEP_DEBUG
/*
 * pm_print_times: print time taken by devices to suspend and resume.
 *
 * show() returns whether printing of suspend and resume times is enabled.
 * store() accepts 0 or 1.  0 disables printing and 1 enables it.
 */
bool pm_print_times_enabled;

static ssize_t pm_print_times_show(struct kobject *kobj,
				   struct kobj_attribute *attr, char *buf)
{
	return sprintf(buf, "%d\n", pm_print_times_enabled);
}

static ssize_t pm_print_times_store(struct kobject *kobj,
				    struct kobj_attribute *attr,
				    const char *buf, size_t n)
{
	unsigned long val;

	if (kstrtoul(buf, 10, &val))
		return -EINVAL;

	if (val > 1)
		return -EINVAL;

	pm_print_times_enabled = !!val;
	return n;
}

power_attr(pm_print_times);

static inline void pm_print_times_init(void)
{
	pm_print_times_enabled = !!initcall_debug;
}

static ssize_t pm_wakeup_irq_show(struct kobject *kobj,
					struct kobj_attribute *attr,
					char *buf)
{
	if (!pm_wakeup_irq())
		return -ENODATA;

	return sprintf(buf, "%u\n", pm_wakeup_irq());
}

power_attr_ro(pm_wakeup_irq);

bool pm_debug_messages_on __read_mostly;

static ssize_t pm_debug_messages_show(struct kobject *kobj,
				      struct kobj_attribute *attr, char *buf)
{
	return sprintf(buf, "%d\n", pm_debug_messages_on);
}

static ssize_t pm_debug_messages_store(struct kobject *kobj,
				       struct kobj_attribute *attr,
				       const char *buf, size_t n)
{
	unsigned long val;

	if (kstrtoul(buf, 10, &val))
		return -EINVAL;

	if (val > 1)
		return -EINVAL;

	pm_debug_messages_on = !!val;
	return n;
}

power_attr(pm_debug_messages);

static int __init pm_debug_messages_setup(char *str)
{
	pm_debug_messages_on = true;
	return 1;
}
__setup("pm_debug_messages", pm_debug_messages_setup);

/**
 * __pm_pr_dbg - Print a suspend debug message to the kernel log.
 * @defer: Whether or not to use printk_deferred() to print the message.
 * @fmt: Message format.
 *
 * The message will be emitted if enabled through the pm_debug_messages
 * sysfs attribute.
 */
void __pm_pr_dbg(bool defer, const char *fmt, ...)
{
	struct va_format vaf;
	va_list args;

	if (!pm_debug_messages_on)
		return;

	va_start(args, fmt);

	vaf.fmt = fmt;
	vaf.va = &args;

	if (defer)
		printk_deferred(KERN_DEBUG "PM: %pV", &vaf);
	else
		printk(KERN_DEBUG "PM: %pV", &vaf);

	va_end(args);
}

#else /* !CONFIG_PM_SLEEP_DEBUG */
static inline void pm_print_times_init(void) {}
#endif /* CONFIG_PM_SLEEP_DEBUG */

struct kobject *power_kobj;

/**
 * state - control system sleep states.
 *
 * show() returns available sleep state labels, which may be "mem", "standby",
 * "freeze" and "disk" (hibernation).
 * See Documentation/admin-guide/pm/sleep-states.rst for a description of
 * what they mean.
 *
 * store() accepts one of those strings, translates it into the proper
 * enumerated value, and initiates a suspend transition.
 */
static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr,
			  char *buf)
{
	char *s = buf;
#ifdef CONFIG_SUSPEND
	suspend_state_t i;

	for (i = PM_SUSPEND_MIN; i < PM_SUSPEND_MAX; i++)
		if (pm_states[i])
			s += sprintf(s,"%s ", pm_states[i]);

#endif
	if (hibernation_available())
		s += sprintf(s, "disk ");
	if (s != buf)
		/* convert the last space to a newline */
		*(s-1) = '\n';
	return (s - buf);
}

static suspend_state_t decode_state(const char *buf, size_t n)
{
#ifdef CONFIG_SUSPEND
	suspend_state_t state;
#endif
	char *p;
	int len;

	p = memchr(buf, '\n', n);
	len = p ? p - buf : n;

	/* Check hibernation first. */
	if (len == 4 && str_has_prefix(buf, "disk"))
		return PM_SUSPEND_MAX;

#ifdef CONFIG_SUSPEND
	for (state = PM_SUSPEND_MIN; state < PM_SUSPEND_MAX; state++) {
		const char *label = pm_states[state];

		if (label && len == strlen(label) && !strncmp(buf, label, len))
			return state;
	}
#endif

	return PM_SUSPEND_ON;
}

static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
			   const char *buf, size_t n)
{
	suspend_state_t state;
	int error;

	error = pm_autosleep_lock();
	if (error)
		return error;

	if (pm_autosleep_state() > PM_SUSPEND_ON) {
		error = -EBUSY;
		goto out;
	}

	state = decode_state(buf, n);
	if (state < PM_SUSPEND_MAX) {
		if (state == PM_SUSPEND_MEM)
			state = mem_sleep_current;

		error = pm_suspend(state);
	} else if (state == PM_SUSPEND_MAX) {
		error = hibernate();
	} else {
		error = -EINVAL;
	}

 out:
	pm_autosleep_unlock();
	return error ? error : n;
}

power_attr(state);

#ifdef CONFIG_PM_SLEEP
/*
 * The 'wakeup_count' attribute, along with the functions defined in
 * drivers/base/power/wakeup.c, provides a means by which wakeup events can be
 * handled in a non-racy way.
 *
 * If a wakeup event occurs when the system is in a sleep state, it simply is
 * woken up.  In turn, if an event that would wake the system up from a sleep
 * state occurs when it is undergoing a transition to that sleep state, the
 * transition should be aborted.  Moreover, if such an event occurs when the
 * system is in the working state, an attempt to start a transition to the
 * given sleep state should fail during certain period after the detection of
 * the event.  Using the 'state' attribute alone is not sufficient to satisfy
 * these requirements, because a wakeup event may occur exactly when 'state'
 * is being written to and may be delivered to user space right before it is
 * frozen, so the event will remain only partially processed until the system is
 * woken up by another event.  In particular, it won't cause the transition to
 * a sleep state to be aborted.
 *
 * This difficulty may be overcome if user space uses 'wakeup_count' before
 * writing to 'state'.  It first should read from 'wakeup_count' and store
 * the read value.  Then, after carrying out its own preparations for the system
 * transition to a sleep state, it should write the stored value to
 * 'wakeup_count'.  If that fails, at least one wakeup event has occurred since
 * 'wakeup_count' was read and 'state' should not be written to.  Otherwise, it
 * is allowed to write to 'state', but the transition will be aborted if there
 * are any wakeup events detected after 'wakeup_count' was written to.
 */

static ssize_t wakeup_count_show(struct kobject *kobj,
				struct kobj_attribute *attr,
				char *buf)
{
	unsigned int val;

	return pm_get_wakeup_count(&val, true) ?
		sprintf(buf, "%u\n", val) : -EINTR;
}

static ssize_t wakeup_count_store(struct kobject *kobj,
				struct kobj_attribute *attr,
				const char *buf, size_t n)
{
	unsigned int val;
	int error;

	error = pm_autosleep_lock();
	if (error)
		return error;

	if (pm_autosleep_state() > PM_SUSPEND_ON) {
		error = -EBUSY;
		goto out;
	}

	error = -EINVAL;
	if (sscanf(buf, "%u", &val) == 1) {
		if (pm_save_wakeup_count(val))
			error = n;
		else
			pm_print_active_wakeup_sources();
	}

 out:
	pm_autosleep_unlock();
	return error;
}

power_attr(wakeup_count);

#ifdef CONFIG_PM_AUTOSLEEP
static ssize_t autosleep_show(struct kobject *kobj,
			      struct kobj_attribute *attr,
			      char *buf)
{
	suspend_state_t state = pm_autosleep_state();

	if (state == PM_SUSPEND_ON)
		return sprintf(buf, "off\n");

#ifdef CONFIG_SUSPEND
	if (state < PM_SUSPEND_MAX)
		return sprintf(buf, "%s\n", pm_states[state] ?
					pm_states[state] : "error");
#endif
#ifdef CONFIG_HIBERNATION
	return sprintf(buf, "disk\n");
#else
	return sprintf(buf, "error");
#endif
}

static ssize_t autosleep_store(struct kobject *kobj,
			       struct kobj_attribute *attr,
			       const char *buf, size_t n)
{
	suspend_state_t state = decode_state(buf, n);
	int error;

	if (state == PM_SUSPEND_ON
	    && strcmp(buf, "off") && strcmp(buf, "off\n"))
		return -EINVAL;

	if (state == PM_SUSPEND_MEM)
		state = mem_sleep_current;

	error = pm_autosleep_set_state(state);
	return error ? error : n;
}

power_attr(autosleep);
#endif /* CONFIG_PM_AUTOSLEEP */

#ifdef CONFIG_PM_WAKELOCKS
static ssize_t wake_lock_show(struct kobject *kobj,
			      struct kobj_attribute *attr,
			      char *buf)
{
	return pm_show_wakelocks(buf, true);
}

static ssize_t wake_lock_store(struct kobject *kobj,
			       struct kobj_attribute *attr,
			       const char *buf, size_t n)
{
	int error = pm_wake_lock(buf);
	return error ? error : n;
}

power_attr(wake_lock);

static ssize_t wake_unlock_show(struct kobject *kobj,
				struct kobj_attribute *attr,
				char *buf)
{
	return pm_show_wakelocks(buf, false);
}

static ssize_t wake_unlock_store(struct kobject *kobj,
				 struct kobj_attribute *attr,
				 const char *buf, size_t n)
{
	int error = pm_wake_unlock(buf);
	return error ? error : n;
}

power_attr(wake_unlock);

#endif /* CONFIG_PM_WAKELOCKS */
#endif /* CONFIG_PM_SLEEP */

#ifdef CONFIG_PM_TRACE
int pm_trace_enabled;

static ssize_t pm_trace_show(struct kobject *kobj, struct kobj_attribute *attr,
			     char *buf)
{
	return sprintf(buf, "%d\n", pm_trace_enabled);
}

static ssize_t
pm_trace_store(struct kobject *kobj, struct kobj_attribute *attr,
	       const char *buf, size_t n)
{
	int val;

	if (sscanf(buf, "%d", &val) == 1) {
		pm_trace_enabled = !!val;
		if (pm_trace_enabled) {
			pr_warn("PM: Enabling pm_trace changes system date and time during resume.\n"
				"PM: Correct system time has to be restored manually after resume.\n");
		}
		return n;
	}
	return -EINVAL;
}

power_attr(pm_trace);

static ssize_t pm_trace_dev_match_show(struct kobject *kobj,
				       struct kobj_attribute *attr,
				       char *buf)
{
	return show_trace_dev_match(buf, PAGE_SIZE);
}

power_attr_ro(pm_trace_dev_match);

#endif /* CONFIG_PM_TRACE */

#ifdef CONFIG_FREEZER
static ssize_t pm_freeze_timeout_show(struct kobject *kobj,
				      struct kobj_attribute *attr, char *buf)
{
	return sprintf(buf, "%u\n", freeze_timeout_msecs);
}

static ssize_t pm_freeze_timeout_store(struct kobject *kobj,
				       struct kobj_attribute *attr,
				       const char *buf, size_t n)
{
	unsigned long val;

	if (kstrtoul(buf, 10, &val))
		return -EINVAL;

	freeze_timeout_msecs = val;
	return n;
}

power_attr(pm_freeze_timeout);

#endif	/* CONFIG_FREEZER*/

static struct attribute * g[] = {
	&state_attr.attr,
#ifdef CONFIG_PM_TRACE
	&pm_trace_attr.attr,
	&pm_trace_dev_match_attr.attr,
#endif
#ifdef CONFIG_PM_SLEEP
	&pm_async_attr.attr,
	&wakeup_count_attr.attr,
#ifdef CONFIG_SUSPEND
	&mem_sleep_attr.attr,
	&sync_on_suspend_attr.attr,
#endif
#ifdef CONFIG_PM_AUTOSLEEP
	&autosleep_attr.attr,
#endif
#ifdef CONFIG_PM_WAKELOCKS
	&wake_lock_attr.attr,
	&wake_unlock_attr.attr,
#endif
#ifdef CONFIG_PM_SLEEP_DEBUG
	&pm_test_attr.attr,
	&pm_print_times_attr.attr,
	&pm_wakeup_irq_attr.attr,
	&pm_debug_messages_attr.attr,
#endif
#endif
#ifdef CONFIG_FREEZER
	&pm_freeze_timeout_attr.attr,
#endif
	NULL,
};

static const struct attribute_group attr_group = {
	.attrs = g,
};

static const struct attribute_group *attr_groups[] = {
	&attr_group,
#ifdef CONFIG_PM_SLEEP
	&suspend_attr_group,
#endif
	NULL,
};

struct workqueue_struct *pm_wq;
EXPORT_SYMBOL_GPL(pm_wq);

static int __init pm_start_workqueue(void)
{
	pm_wq = alloc_workqueue("pm", WQ_FREEZABLE, 0);

	return pm_wq ? 0 : -ENOMEM;
}

static int __init pm_init(void)
{
	int error = pm_start_workqueue();
	if (error)
		return error;
	hibernate_image_size_init();
	hibernate_reserved_size_init();
	pm_states_init();
	power_kobj = kobject_create_and_add("power", NULL);
	if (!power_kobj)
		return -ENOMEM;
	error = sysfs_create_groups(power_kobj, attr_groups);
	if (error)
		return error;
	pm_print_times_init();
	return pm_autosleep_init();
}

core_initcall(pm_init);