summaryrefslogtreecommitdiffstats
path: root/drivers/base/power/main.c
blob: 5630af302b2fc154862235ed03d0f24feabb02a2 (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
/*
 * 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 different set of lists than the global subsystem list are used to
 * keep track of power info because we use different lists to hold
 * devices based on what stage of the power management process they
 * are in. The power domain dependencies may also 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_active 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.
 *
 * All the other lists are kept in the same order, for consistency.
 * However the lists aren't always traversed in the same order.
 * Semaphores must be acquired from the top (i.e., front) down
 * and released in the opposite order.  Devices must be suspended
 * from the bottom (i.e., end) up and resumed in the opposite order.
 * That way no parent will be suspended while it still has an active
 * child.
 *
 * 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_active);
static LIST_HEAD(dpm_off);
static LIST_HEAD(dpm_off_irq);
static LIST_HEAD(dpm_destroy);

static DEFINE_MUTEX(dpm_list_mtx);

/* 'true' if all devices have been suspended, protected by dpm_list_mtx */
static bool all_sleeping;

/**
 *	device_pm_add - add a device to the list of active devices
 *	@dev:	Device to be added to the list
 */
int device_pm_add(struct device *dev)
{
	int error = 0;

	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 && dev->parent->power.sleeping) || all_sleeping) {
		if (dev->parent->power.sleeping)
			dev_warn(dev,
				"parent %s is sleeping, will not add\n",
				dev->parent->bus_id);
		else
			dev_warn(dev, "devices are sleeping, will not add\n");
		WARN_ON(true);
		error = -EBUSY;
	} else {
		error = dpm_sysfs_add(dev);
		if (!error)
			list_add_tail(&dev->power.entry, &dpm_active);
	}
	mutex_unlock(&dpm_list_mtx);
	return error;
}

/**
 *	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);
	dpm_sysfs_remove(dev);
	list_del_init(&dev->power.entry);
	mutex_unlock(&dpm_list_mtx);
}

/**
 *	device_pm_schedule_removal - schedule the removal of a suspended device
 *	@dev:	Device to destroy
 *
 *	Moves the device to the dpm_destroy list for further processing by
 *	unregister_dropped_devices().
 */
void device_pm_schedule_removal(struct device *dev)
{
	pr_debug("PM: Preparing for removal: %s:%s\n",
		dev->bus ? dev->bus->name : "No Bus",
		kobject_name(&dev->kobj));
	mutex_lock(&dpm_list_mtx);
	list_move_tail(&dev->power.entry, &dpm_destroy);
	mutex_unlock(&dpm_list_mtx);
}
EXPORT_SYMBOL_GPL(device_pm_schedule_removal);

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

/**
 *	resume_device_early - Power on one device (early resume).
 *	@dev:	Device.
 *
 *	Must be called with interrupts disabled.
 */
static int resume_device_early(struct device *dev)
{
	int error = 0;

	TRACE_DEVICE(dev);
	TRACE_RESUME(0);

	if (dev->bus && dev->bus->resume_early) {
		dev_dbg(dev, "EARLY resume\n");
		error = dev->bus->resume_early(dev);
	}

	TRACE_RESUME(error);
	return error;
}

/**
 *	dpm_power_up - Power on all regular (non-sysdev) devices.
 *
 *	Walk the dpm_off_irq list and power each device up. This
 *	is used for devices that required they be powered down with
 *	interrupts disabled. As devices are powered on, they are moved
 *	to the dpm_off list.
 *
 *	Must be called with interrupts disabled and only one CPU running.
 */
static void dpm_power_up(void)
{

	while (!list_empty(&dpm_off_irq)) {
		struct list_head *entry = dpm_off_irq.next;
		struct device *dev = to_device(entry);

		list_move_tail(entry, &dpm_off);
		resume_device_early(dev);
	}
}

/**
 *	device_power_up - Turn on all devices that need special attention.
 *
 *	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(void)
{
	sysdev_resume();
	dpm_power_up();
}
EXPORT_SYMBOL_GPL(device_power_up);

/**
 *	resume_device - Restore state for one device.
 *	@dev:	Device.
 *
 */
static int resume_device(struct device *dev)
{
	int error = 0;

	TRACE_DEVICE(dev);
	TRACE_RESUME(0);

	down(&dev->sem);

	if (dev->bus && dev->bus->resume) {
		dev_dbg(dev,"resuming\n");
		error = dev->bus->resume(dev);
	}

	if (!error && dev->type && dev->type->resume) {
		dev_dbg(dev,"resuming\n");
		error = dev->type->resume(dev);
	}

	if (!error && dev->class && dev->class->resume) {
		dev_dbg(dev,"class resume\n");
		error = dev->class->resume(dev);
	}

	up(&dev->sem);

	TRACE_RESUME(error);
	return error;
}

/**
 *	dpm_resume - Resume every device.
 *
 *	Resume the devices that have either not gone through
 *	the late suspend, or that did go through it but also
 *	went through the early resume.
 *
 *	Take devices from the dpm_off_list, resume them,
 *	and put them on the dpm_locked list.
 */
static void dpm_resume(void)
{
	mutex_lock(&dpm_list_mtx);
	all_sleeping = false;
	while(!list_empty(&dpm_off)) {
		struct list_head *entry = dpm_off.next;
		struct device *dev = to_device(entry);

		list_move_tail(entry, &dpm_active);
		dev->power.sleeping = false;
		mutex_unlock(&dpm_list_mtx);
		resume_device(dev);
		mutex_lock(&dpm_list_mtx);
	}
	mutex_unlock(&dpm_list_mtx);
}

/**
 *	unregister_dropped_devices - Unregister devices scheduled for removal
 *
 *	Unregister all devices on the dpm_destroy list.
 */
static void unregister_dropped_devices(void)
{
	mutex_lock(&dpm_list_mtx);
	while (!list_empty(&dpm_destroy)) {
		struct list_head *entry = dpm_destroy.next;
		struct device *dev = to_device(entry);

		mutex_unlock(&dpm_list_mtx);
		/* This also removes the device from the list */
		device_unregister(dev);
		mutex_lock(&dpm_list_mtx);
	}
	mutex_unlock(&dpm_list_mtx);
}

/**
 *	device_resume - Restore state of each device in system.
 *
 *	Resume all the devices, unlock them all, and allow new
 *	devices to be registered once again.
 */
void device_resume(void)
{
	might_sleep();
	dpm_resume();
	unregister_dropped_devices();
}
EXPORT_SYMBOL_GPL(device_resume);


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

static inline char *suspend_verb(u32 event)
{
	switch (event) {
	case PM_EVENT_SUSPEND:	return "suspend";
	case PM_EVENT_FREEZE:	return "freeze";
	case PM_EVENT_PRETHAW:	return "prethaw";
	default:		return "(unknown suspend event)";
	}
}

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

/**
 *	suspend_device_late - Shut down one device (late suspend).
 *	@dev:	Device.
 *	@state:	Power state device is entering.
 *
 *	This is called with interrupts off and only a single CPU running.
 */
static int suspend_device_late(struct device *dev, pm_message_t state)
{
	int error = 0;

	if (dev->bus && dev->bus->suspend_late) {
		suspend_device_dbg(dev, state, "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:		Power state to enter.
 *
 *	Power down devices that require interrupts to be disabled
 *	and move them from the dpm_off list to the dpm_off_irq list.
 *	Then power down system devices.
 *
 *	Must be called with interrupts disabled and only one CPU running.
 */
int device_power_down(pm_message_t state)
{
	int error = 0;

	while (!list_empty(&dpm_off)) {
		struct list_head *entry = dpm_off.prev;
		struct device *dev = to_device(entry);

		error = suspend_device_late(dev, state);
		if (error) {
			printk(KERN_ERR "Could not power down device %s: "
					"error %d\n",
					kobject_name(&dev->kobj), error);
			break;
		}
		if (!list_empty(&dev->power.entry))
			list_move(&dev->power.entry, &dpm_off_irq);
	}

	if (!error)
		error = sysdev_suspend(state);
	if (error)
		dpm_power_up();
	return error;
}
EXPORT_SYMBOL_GPL(device_power_down);

/**
 *	suspend_device - Save state of one device.
 *	@dev:	Device.
 *	@state:	Power state device is entering.
 */
static int suspend_device(struct device *dev, pm_message_t state)
{
	int error = 0;

	down(&dev->sem);

	if (dev->class && dev->class->suspend) {
		suspend_device_dbg(dev, state, "class ");
		error = dev->class->suspend(dev, state);
		suspend_report_result(dev->class->suspend, error);
	}

	if (!error && dev->type && dev->type->suspend) {
		suspend_device_dbg(dev, state, "type ");
		error = dev->type->suspend(dev, state);
		suspend_report_result(dev->type->suspend, error);
	}

	if (!error && dev->bus && dev->bus->suspend) {
		suspend_device_dbg(dev, state, "");
		error = dev->bus->suspend(dev, state);
		suspend_report_result(dev->bus->suspend, error);
	}

	up(&dev->sem);

	return error;
}

/**
 *	dpm_suspend - Suspend every device.
 *	@state:	Power state to put each device in.
 *
 *	Walk the dpm_locked list.  Suspend each device and move it
 *	to the dpm_off list.
 *
 *	(For historical reasons, if it returns -EAGAIN, that used to mean
 *	that the device would be called again with interrupts disabled.
 *	These days, we use the "suspend_late()" callback for that, so we
 *	print a warning and consider it an error).
 */
static int dpm_suspend(pm_message_t state)
{
	int error = 0;

	mutex_lock(&dpm_list_mtx);
	while (!list_empty(&dpm_active)) {
		struct list_head *entry = dpm_active.prev;
		struct device *dev = to_device(entry);

		WARN_ON(dev->parent && dev->parent->power.sleeping);

		dev->power.sleeping = true;
		mutex_unlock(&dpm_list_mtx);
		error = suspend_device(dev, state);
		mutex_lock(&dpm_list_mtx);
		if (error) {
			printk(KERN_ERR "Could not suspend device %s: "
					"error %d%s\n",
					kobject_name(&dev->kobj),
					error,
					(error == -EAGAIN ?
					" (please convert to suspend_late)" :
					""));
			dev->power.sleeping = false;
			break;
		}
		if (!list_empty(&dev->power.entry))
			list_move(&dev->power.entry, &dpm_off);
	}
	if (!error)
		all_sleeping = true;
	mutex_unlock(&dpm_list_mtx);

	return error;
}

/**
 *	device_suspend - Save state and stop all devices in system.
 *	@state: new power management state
 *
 *	Prevent new devices from being registered, then lock all devices
 *	and suspend them.
 */
int device_suspend(pm_message_t state)
{
	int error;

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

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