summaryrefslogtreecommitdiff
path: root/drivers/base/power/wakeup.c
blob: 71c5528e1c357a81112c6f79b1e91f013a58e3aa (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
/*
 * drivers/base/power/wakeup.c - System wakeup events framework
 *
 * Copyright (c) 2010 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
 *
 * This file is released under the GPLv2.
 */

#include <linux/device.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/capability.h>
#include <linux/suspend.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>

#include "power.h"

#define TIMEOUT		100

/*
 * If set, the suspend/hibernate code will abort transitions to a sleep state
 * if wakeup events are registered during or immediately before the transition.
 */
bool events_check_enabled;

/* The counter of registered wakeup events. */
static atomic_t event_count = ATOMIC_INIT(0);
/* A preserved old value of event_count. */
static unsigned int saved_count;
/* The counter of wakeup events being processed. */
static atomic_t events_in_progress = ATOMIC_INIT(0);

static DEFINE_SPINLOCK(events_lock);

static void pm_wakeup_timer_fn(unsigned long data);

static LIST_HEAD(wakeup_sources);

/**
 * wakeup_source_create - Create a struct wakeup_source object.
 * @name: Name of the new wakeup source.
 */
struct wakeup_source *wakeup_source_create(const char *name)
{
	struct wakeup_source *ws;

	ws = kzalloc(sizeof(*ws), GFP_KERNEL);
	if (!ws)
		return NULL;

	spin_lock_init(&ws->lock);
	if (name)
		ws->name = kstrdup(name, GFP_KERNEL);

	return ws;
}
EXPORT_SYMBOL_GPL(wakeup_source_create);

/**
 * wakeup_source_destroy - Destroy a struct wakeup_source object.
 * @ws: Wakeup source to destroy.
 */
void wakeup_source_destroy(struct wakeup_source *ws)
{
	if (!ws)
		return;

	spin_lock_irq(&ws->lock);
	while (ws->active) {
		spin_unlock_irq(&ws->lock);

		schedule_timeout_interruptible(msecs_to_jiffies(TIMEOUT));

		spin_lock_irq(&ws->lock);
	}
	spin_unlock_irq(&ws->lock);

	kfree(ws->name);
	kfree(ws);
}
EXPORT_SYMBOL_GPL(wakeup_source_destroy);

/**
 * wakeup_source_add - Add given object to the list of wakeup sources.
 * @ws: Wakeup source object to add to the list.
 */
void wakeup_source_add(struct wakeup_source *ws)
{
	if (WARN_ON(!ws))
		return;

	setup_timer(&ws->timer, pm_wakeup_timer_fn, (unsigned long)ws);
	ws->active = false;

	spin_lock_irq(&events_lock);
	list_add_rcu(&ws->entry, &wakeup_sources);
	spin_unlock_irq(&events_lock);
	synchronize_rcu();
}
EXPORT_SYMBOL_GPL(wakeup_source_add);

/**
 * wakeup_source_remove - Remove given object from the wakeup sources list.
 * @ws: Wakeup source object to remove from the list.
 */
void wakeup_source_remove(struct wakeup_source *ws)
{
	if (WARN_ON(!ws))
		return;

	spin_lock_irq(&events_lock);
	list_del_rcu(&ws->entry);
	spin_unlock_irq(&events_lock);
	synchronize_rcu();
}
EXPORT_SYMBOL_GPL(wakeup_source_remove);

/**
 * wakeup_source_register - Create wakeup source and add it to the list.
 * @name: Name of the wakeup source to register.
 */
struct wakeup_source *wakeup_source_register(const char *name)
{
	struct wakeup_source *ws;

	ws = wakeup_source_create(name);
	if (ws)
		wakeup_source_add(ws);

	return ws;
}
EXPORT_SYMBOL_GPL(wakeup_source_register);

/**
 * wakeup_source_unregister - Remove wakeup source from the list and remove it.
 * @ws: Wakeup source object to unregister.
 */
void wakeup_source_unregister(struct wakeup_source *ws)
{
	wakeup_source_remove(ws);
	wakeup_source_destroy(ws);
}
EXPORT_SYMBOL_GPL(wakeup_source_unregister);

/**
 * device_wakeup_attach - Attach a wakeup source object to a device object.
 * @dev: Device to handle.
 * @ws: Wakeup source object to attach to @dev.
 *
 * This causes @dev to be treated as a wakeup device.
 */
static int device_wakeup_attach(struct device *dev, struct wakeup_source *ws)
{
	spin_lock_irq(&dev->power.lock);
	if (dev->power.wakeup) {
		spin_unlock_irq(&dev->power.lock);
		return -EEXIST;
	}
	dev->power.wakeup = ws;
	spin_unlock_irq(&dev->power.lock);
	return 0;
}

/**
 * device_wakeup_enable - Enable given device to be a wakeup source.
 * @dev: Device to handle.
 *
 * Create a wakeup source object, register it and attach it to @dev.
 */
int device_wakeup_enable(struct device *dev)
{
	struct wakeup_source *ws;
	int ret;

	if (!dev || !dev->power.can_wakeup)
		return -EINVAL;

	ws = wakeup_source_register(dev_name(dev));
	if (!ws)
		return -ENOMEM;

	ret = device_wakeup_attach(dev, ws);
	if (ret)
		wakeup_source_unregister(ws);

	return ret;
}
EXPORT_SYMBOL_GPL(device_wakeup_enable);

/**
 * device_wakeup_detach - Detach a device's wakeup source object from it.
 * @dev: Device to detach the wakeup source object from.
 *
 * After it returns, @dev will not be treated as a wakeup device any more.
 */
static struct wakeup_source *device_wakeup_detach(struct device *dev)
{
	struct wakeup_source *ws;

	spin_lock_irq(&dev->power.lock);
	ws = dev->power.wakeup;
	dev->power.wakeup = NULL;
	spin_unlock_irq(&dev->power.lock);
	return ws;
}

/**
 * device_wakeup_disable - Do not regard a device as a wakeup source any more.
 * @dev: Device to handle.
 *
 * Detach the @dev's wakeup source object from it, unregister this wakeup source
 * object and destroy it.
 */
int device_wakeup_disable(struct device *dev)
{
	struct wakeup_source *ws;

	if (!dev || !dev->power.can_wakeup)
		return -EINVAL;

	ws = device_wakeup_detach(dev);
	if (ws)
		wakeup_source_unregister(ws);

	return 0;
}
EXPORT_SYMBOL_GPL(device_wakeup_disable);

/**
 * device_init_wakeup - Device wakeup initialization.
 * @dev: Device to handle.
 * @enable: Whether or not to enable @dev as a wakeup device.
 *
 * By default, most devices should leave wakeup disabled.  The exceptions are
 * devices that everyone expects to be wakeup sources: keyboards, power buttons,
 * possibly network interfaces, etc.
 */
int device_init_wakeup(struct device *dev, bool enable)
{
	int ret = 0;

	if (enable) {
		device_set_wakeup_capable(dev, true);
		ret = device_wakeup_enable(dev);
	} else {
		device_set_wakeup_capable(dev, false);
	}

	return ret;
}
EXPORT_SYMBOL_GPL(device_init_wakeup);

/**
 * device_set_wakeup_enable - Enable or disable a device to wake up the system.
 * @dev: Device to handle.
 */
int device_set_wakeup_enable(struct device *dev, bool enable)
{
	if (!dev || !dev->power.can_wakeup)
		return -EINVAL;

	return enable ? device_wakeup_enable(dev) : device_wakeup_disable(dev);
}
EXPORT_SYMBOL_GPL(device_set_wakeup_enable);

/*
 * The functions below use the observation that each wakeup event starts a
 * period in which the system should not be suspended.  The moment this period
 * will end depends on how the wakeup event is going to be processed after being
 * detected and all of the possible cases can be divided into two distinct
 * groups.
 *
 * First, a wakeup event may be detected by the same functional unit that will
 * carry out the entire processing of it and possibly will pass it to user space
 * for further processing.  In that case the functional unit that has detected
 * the event may later "close" the "no suspend" period associated with it
 * directly as soon as it has been dealt with.  The pair of pm_stay_awake() and
 * pm_relax(), balanced with each other, is supposed to be used in such
 * situations.
 *
 * Second, a wakeup event may be detected by one functional unit and processed
 * by another one.  In that case the unit that has detected it cannot really
 * "close" the "no suspend" period associated with it, unless it knows in
 * advance what's going to happen to the event during processing.  This
 * knowledge, however, may not be available to it, so it can simply specify time
 * to wait before the system can be suspended and pass it as the second
 * argument of pm_wakeup_event().
 *
 * It is valid to call pm_relax() after pm_wakeup_event(), in which case the
 * "no suspend" period will be ended either by the pm_relax(), or by the timer
 * function executed when the timer expires, whichever comes first.
 */

/**
 * wakup_source_activate - Mark given wakeup source as active.
 * @ws: Wakeup source to handle.
 *
 * Update the @ws' statistics and, if @ws has just been activated, notify the PM
 * core of the event by incrementing the counter of of wakeup events being
 * processed.
 */
static void wakeup_source_activate(struct wakeup_source *ws)
{
	ws->active = true;
	ws->active_count++;
	ws->timer_expires = jiffies;
	ws->last_time = ktime_get();

	atomic_inc(&events_in_progress);
}

/**
 * __pm_stay_awake - Notify the PM core of a wakeup event.
 * @ws: Wakeup source object associated with the source of the event.
 *
 * It is safe to call this function from interrupt context.
 */
void __pm_stay_awake(struct wakeup_source *ws)
{
	unsigned long flags;

	if (!ws)
		return;

	spin_lock_irqsave(&ws->lock, flags);
	ws->event_count++;
	if (!ws->active)
		wakeup_source_activate(ws);
	spin_unlock_irqrestore(&ws->lock, flags);
}
EXPORT_SYMBOL_GPL(__pm_stay_awake);

/**
 * pm_stay_awake - Notify the PM core that a wakeup event is being processed.
 * @dev: Device the wakeup event is related to.
 *
 * Notify the PM core of a wakeup event (signaled by @dev) by calling
 * __pm_stay_awake for the @dev's wakeup source object.
 *
 * Call this function after detecting of a wakeup event if pm_relax() is going
 * to be called directly after processing the event (and possibly passing it to
 * user space for further processing).
 */
void pm_stay_awake(struct device *dev)
{
	unsigned long flags;

	if (!dev)
		return;

	spin_lock_irqsave(&dev->power.lock, flags);
	__pm_stay_awake(dev->power.wakeup);
	spin_unlock_irqrestore(&dev->power.lock, flags);
}
EXPORT_SYMBOL_GPL(pm_stay_awake);

/**
 * wakup_source_deactivate - Mark given wakeup source as inactive.
 * @ws: Wakeup source to handle.
 *
 * Update the @ws' statistics and notify the PM core that the wakeup source has
 * become inactive by decrementing the counter of wakeup events being processed
 * and incrementing the counter of registered wakeup events.
 */
static void wakeup_source_deactivate(struct wakeup_source *ws)
{
	ktime_t duration;
	ktime_t now;

	ws->relax_count++;
	/*
	 * __pm_relax() may be called directly or from a timer function.
	 * If it is called directly right after the timer function has been
	 * started, but before the timer function calls __pm_relax(), it is
	 * possible that __pm_stay_awake() will be called in the meantime and
	 * will set ws->active.  Then, ws->active may be cleared immediately
	 * by the __pm_relax() called from the timer function, but in such a
	 * case ws->relax_count will be different from ws->active_count.
	 */
	if (ws->relax_count != ws->active_count) {
		ws->relax_count--;
		return;
	}

	ws->active = false;

	now = ktime_get();
	duration = ktime_sub(now, ws->last_time);
	ws->total_time = ktime_add(ws->total_time, duration);
	if (ktime_to_ns(duration) > ktime_to_ns(ws->max_time))
		ws->max_time = duration;

	del_timer(&ws->timer);

	/*
	 * event_count has to be incremented before events_in_progress is
	 * modified, so that the callers of pm_check_wakeup_events() and
	 * pm_save_wakeup_count() don't see the old value of event_count and
	 * events_in_progress equal to zero at the same time.
	 */
	atomic_inc(&event_count);
	smp_mb__before_atomic_dec();
	atomic_dec(&events_in_progress);
}

/**
 * __pm_relax - Notify the PM core that processing of a wakeup event has ended.
 * @ws: Wakeup source object associated with the source of the event.
 *
 * Call this function for wakeup events whose processing started with calling
 * __pm_stay_awake().
 *
 * It is safe to call it from interrupt context.
 */
void __pm_relax(struct wakeup_source *ws)
{
	unsigned long flags;

	if (!ws)
		return;

	spin_lock_irqsave(&ws->lock, flags);
	if (ws->active)
		wakeup_source_deactivate(ws);
	spin_unlock_irqrestore(&ws->lock, flags);
}
EXPORT_SYMBOL_GPL(__pm_relax);

/**
 * pm_relax - Notify the PM core that processing of a wakeup event has ended.
 * @dev: Device that signaled the event.
 *
 * Execute __pm_relax() for the @dev's wakeup source object.
 */
void pm_relax(struct device *dev)
{
	unsigned long flags;

	if (!dev)
		return;

	spin_lock_irqsave(&dev->power.lock, flags);
	__pm_relax(dev->power.wakeup);
	spin_unlock_irqrestore(&dev->power.lock, flags);
}
EXPORT_SYMBOL_GPL(pm_relax);

/**
 * pm_wakeup_timer_fn - Delayed finalization of a wakeup event.
 * @data: Address of the wakeup source object associated with the event source.
 *
 * Call __pm_relax() for the wakeup source whose address is stored in @data.
 */
static void pm_wakeup_timer_fn(unsigned long data)
{
	__pm_relax((struct wakeup_source *)data);
}

/**
 * __pm_wakeup_event - Notify the PM core of a wakeup event.
 * @ws: Wakeup source object associated with the event source.
 * @msec: Anticipated event processing time (in milliseconds).
 *
 * Notify the PM core of a wakeup event whose source is @ws that will take
 * approximately @msec milliseconds to be processed by the kernel.  If @ws is
 * not active, activate it.  If @msec is nonzero, set up the @ws' timer to
 * execute pm_wakeup_timer_fn() in future.
 *
 * It is safe to call this function from interrupt context.
 */
void __pm_wakeup_event(struct wakeup_source *ws, unsigned int msec)
{
	unsigned long flags;
	unsigned long expires;

	if (!ws)
		return;

	spin_lock_irqsave(&ws->lock, flags);

	ws->event_count++;
	if (!ws->active)
		wakeup_source_activate(ws);

	if (!msec) {
		wakeup_source_deactivate(ws);
		goto unlock;
	}

	expires = jiffies + msecs_to_jiffies(msec);
	if (!expires)
		expires = 1;

	if (time_after(expires, ws->timer_expires)) {
		mod_timer(&ws->timer, expires);
		ws->timer_expires = expires;
	}

 unlock:
	spin_unlock_irqrestore(&ws->lock, flags);
}
EXPORT_SYMBOL_GPL(__pm_wakeup_event);


/**
 * pm_wakeup_event - Notify the PM core of a wakeup event.
 * @dev: Device the wakeup event is related to.
 * @msec: Anticipated event processing time (in milliseconds).
 *
 * Call __pm_wakeup_event() for the @dev's wakeup source object.
 */
void pm_wakeup_event(struct device *dev, unsigned int msec)
{
	unsigned long flags;

	if (!dev)
		return;

	spin_lock_irqsave(&dev->power.lock, flags);
	__pm_wakeup_event(dev->power.wakeup, msec);
	spin_unlock_irqrestore(&dev->power.lock, flags);
}
EXPORT_SYMBOL_GPL(pm_wakeup_event);

/**
 * pm_wakeup_update_hit_counts - Update hit counts of all active wakeup sources.
 */
static void pm_wakeup_update_hit_counts(void)
{
	unsigned long flags;
	struct wakeup_source *ws;

	rcu_read_lock();
	list_for_each_entry_rcu(ws, &wakeup_sources, entry) {
		spin_lock_irqsave(&ws->lock, flags);
		if (ws->active)
			ws->hit_count++;
		spin_unlock_irqrestore(&ws->lock, flags);
	}
	rcu_read_unlock();
}

/**
 * pm_check_wakeup_events - Check for new wakeup events.
 *
 * Compare the current number of registered wakeup events with its preserved
 * value from the past to check if new wakeup events have been registered since
 * the old value was stored.  Check if the current number of wakeup events being
 * processed is zero.
 */
bool pm_check_wakeup_events(void)
{
	unsigned long flags;
	bool ret = true;

	spin_lock_irqsave(&events_lock, flags);
	if (events_check_enabled) {
		ret = ((unsigned int)atomic_read(&event_count) == saved_count)
			&& !atomic_read(&events_in_progress);
		events_check_enabled = ret;
	}
	spin_unlock_irqrestore(&events_lock, flags);
	if (!ret)
		pm_wakeup_update_hit_counts();
	return ret;
}

/**
 * pm_get_wakeup_count - Read the number of registered wakeup events.
 * @count: Address to store the value at.
 *
 * Store the number of registered wakeup events at the address in @count.  Block
 * if the current number of wakeup events being processed is nonzero.
 *
 * Return false if the wait for the number of wakeup events being processed to
 * drop down to zero has been interrupted by a signal (and the current number
 * of wakeup events being processed is still nonzero).  Otherwise return true.
 */
bool pm_get_wakeup_count(unsigned int *count)
{
	bool ret;

	if (capable(CAP_SYS_ADMIN))
		events_check_enabled = false;

	while (atomic_read(&events_in_progress) && !signal_pending(current)) {
		pm_wakeup_update_hit_counts();
		schedule_timeout_interruptible(msecs_to_jiffies(TIMEOUT));
	}

	ret = !atomic_read(&events_in_progress);
	*count = atomic_read(&event_count);
	return ret;
}

/**
 * pm_save_wakeup_count - Save the current number of registered wakeup events.
 * @count: Value to compare with the current number of registered wakeup events.
 *
 * If @count is equal to the current number of registered wakeup events and the
 * current number of wakeup events being processed is zero, store @count as the
 * old number of registered wakeup events to be used by pm_check_wakeup_events()
 * and return true.  Otherwise return false.
 */
bool pm_save_wakeup_count(unsigned int count)
{
	bool ret = false;

	spin_lock_irq(&events_lock);
	if (count == (unsigned int)atomic_read(&event_count)
	    && !atomic_read(&events_in_progress)) {
		saved_count = count;
		events_check_enabled = true;
		ret = true;
	}
	spin_unlock_irq(&events_lock);
	if (!ret)
		pm_wakeup_update_hit_counts();
	return ret;
}

static struct dentry *wakeup_sources_stats_dentry;

/**
 * print_wakeup_source_stats - Print wakeup source statistics information.
 * @m: seq_file to print the statistics into.
 * @ws: Wakeup source object to print the statistics for.
 */
static int print_wakeup_source_stats(struct seq_file *m,
				     struct wakeup_source *ws)
{
	unsigned long flags;
	ktime_t total_time;
	ktime_t max_time;
	unsigned long active_count;
	ktime_t active_time;
	int ret;

	spin_lock_irqsave(&ws->lock, flags);

	total_time = ws->total_time;
	max_time = ws->max_time;
	active_count = ws->active_count;
	if (ws->active) {
		active_time = ktime_sub(ktime_get(), ws->last_time);
		total_time = ktime_add(total_time, active_time);
		if (active_time.tv64 > max_time.tv64)
			max_time = active_time;
	} else {
		active_time = ktime_set(0, 0);
	}

	ret = seq_printf(m, "%-12s\t%lu\t\t%lu\t\t%lu\t\t"
			"%lld\t\t%lld\t\t%lld\t\t%lld\n",
			ws->name, active_count, ws->event_count, ws->hit_count,
			ktime_to_ms(active_time), ktime_to_ms(total_time),
			ktime_to_ms(max_time), ktime_to_ms(ws->last_time));

	spin_unlock_irqrestore(&ws->lock, flags);

	return ret;
}

/**
 * wakeup_sources_stats_show - Print wakeup sources statistics information.
 * @m: seq_file to print the statistics into.
 */
static int wakeup_sources_stats_show(struct seq_file *m, void *unused)
{
	struct wakeup_source *ws;

	seq_puts(m, "name\t\tactive_count\tevent_count\thit_count\t"
		"active_since\ttotal_time\tmax_time\tlast_change\n");

	rcu_read_lock();
	list_for_each_entry_rcu(ws, &wakeup_sources, entry)
		print_wakeup_source_stats(m, ws);
	rcu_read_unlock();

	return 0;
}

static int wakeup_sources_stats_open(struct inode *inode, struct file *file)
{
	return single_open(file, wakeup_sources_stats_show, NULL);
}

static const struct file_operations wakeup_sources_stats_fops = {
	.owner = THIS_MODULE,
	.open = wakeup_sources_stats_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = single_release,
};

static int __init wakeup_sources_debugfs_init(void)
{
	wakeup_sources_stats_dentry = debugfs_create_file("wakeup_sources",
			S_IRUGO, NULL, NULL, &wakeup_sources_stats_fops);
	return 0;
}

postcore_initcall(wakeup_sources_debugfs_init);