xref: /linux/include/linux/pm.h (revision ff10fca5ceacf7bc59636f5ab808e775d1717167)
1 /*
2  *  pm.h - Power management interface
3  *
4  *  Copyright (C) 2000 Andrew Henroid
5  *
6  *  This program is free software; you can redistribute it and/or modify
7  *  it under the terms of the GNU General Public License as published by
8  *  the Free Software Foundation; either version 2 of the License, or
9  *  (at your option) any later version.
10  *
11  *  This program is distributed in the hope that it will be useful,
12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  *  GNU General Public License for more details.
15  *
16  *  You should have received a copy of the GNU General Public License
17  *  along with this program; if not, write to the Free Software
18  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19  */
20 
21 #ifndef _LINUX_PM_H
22 #define _LINUX_PM_H
23 
24 #include <linux/list.h>
25 #include <linux/workqueue.h>
26 #include <linux/spinlock.h>
27 #include <linux/wait.h>
28 #include <linux/timer.h>
29 #include <linux/completion.h>
30 
31 /*
32  * Callbacks for platform drivers to implement.
33  */
34 extern void (*pm_idle)(void);
35 extern void (*pm_power_off)(void);
36 extern void (*pm_power_off_prepare)(void);
37 
38 /*
39  * Device power management
40  */
41 
42 struct device;
43 
44 #ifdef CONFIG_PM
45 extern const char power_group_name[];		/* = "power" */
46 #else
47 #define power_group_name	NULL
48 #endif
49 
50 typedef struct pm_message {
51 	int event;
52 } pm_message_t;
53 
54 /**
55  * struct dev_pm_ops - device PM callbacks
56  *
57  * Several driver power state transitions are externally visible, affecting
58  * the state of pending I/O queues and (for drivers that touch hardware)
59  * interrupts, wakeups, DMA, and other hardware state.  There may also be
60  * internal transitions to various low power modes, which are transparent
61  * to the rest of the driver stack (such as a driver that's ON gating off
62  * clocks which are not in active use).
63  *
64  * The externally visible transitions are handled with the help of the following
65  * callbacks included in this structure:
66  *
67  * @prepare: Prepare the device for the upcoming transition, but do NOT change
68  *	its hardware state.  Prevent new children of the device from being
69  *	registered after @prepare() returns (the driver's subsystem and
70  *	generally the rest of the kernel is supposed to prevent new calls to the
71  *	probe method from being made too once @prepare() has succeeded).  If
72  *	@prepare() detects a situation it cannot handle (e.g. registration of a
73  *	child already in progress), it may return -EAGAIN, so that the PM core
74  *	can execute it once again (e.g. after the new child has been registered)
75  *	to recover from the race condition.  This method is executed for all
76  *	kinds of suspend transitions and is followed by one of the suspend
77  *	callbacks: @suspend(), @freeze(), or @poweroff().
78  *	The PM core executes @prepare() for all devices before starting to
79  *	execute suspend callbacks for any of them, so drivers may assume all of
80  *	the other devices to be present and functional while @prepare() is being
81  *	executed.  In particular, it is safe to make GFP_KERNEL memory
82  *	allocations from within @prepare().  However, drivers may NOT assume
83  *	anything about the availability of the user space at that time and it
84  *	is not correct to request firmware from within @prepare() (it's too
85  *	late to do that).  [To work around this limitation, drivers may
86  *	register suspend and hibernation notifiers that are executed before the
87  *	freezing of tasks.]
88  *
89  * @complete: Undo the changes made by @prepare().  This method is executed for
90  *	all kinds of resume transitions, following one of the resume callbacks:
91  *	@resume(), @thaw(), @restore().  Also called if the state transition
92  *	fails before the driver's suspend callback (@suspend(), @freeze(),
93  *	@poweroff()) can be executed (e.g. if the suspend callback fails for one
94  *	of the other devices that the PM core has unsuccessfully attempted to
95  *	suspend earlier).
96  *	The PM core executes @complete() after it has executed the appropriate
97  *	resume callback for all devices.
98  *
99  * @suspend: Executed before putting the system into a sleep state in which the
100  *	contents of main memory are preserved.  Quiesce the device, put it into
101  *	a low power state appropriate for the upcoming system state (such as
102  *	PCI_D3hot), and enable wakeup events as appropriate.
103  *
104  * @resume: Executed after waking the system up from a sleep state in which the
105  *	contents of main memory were preserved.  Put the device into the
106  *	appropriate state, according to the information saved in memory by the
107  *	preceding @suspend().  The driver starts working again, responding to
108  *	hardware events and software requests.  The hardware may have gone
109  *	through a power-off reset, or it may have maintained state from the
110  *	previous suspend() which the driver may rely on while resuming.  On most
111  *	platforms, there are no restrictions on availability of resources like
112  *	clocks during @resume().
113  *
114  * @freeze: Hibernation-specific, executed before creating a hibernation image.
115  *	Quiesce operations so that a consistent image can be created, but do NOT
116  *	otherwise put the device into a low power device state and do NOT emit
117  *	system wakeup events.  Save in main memory the device settings to be
118  *	used by @restore() during the subsequent resume from hibernation or by
119  *	the subsequent @thaw(), if the creation of the image or the restoration
120  *	of main memory contents from it fails.
121  *
122  * @thaw: Hibernation-specific, executed after creating a hibernation image OR
123  *	if the creation of the image fails.  Also executed after a failing
124  *	attempt to restore the contents of main memory from such an image.
125  *	Undo the changes made by the preceding @freeze(), so the device can be
126  *	operated in the same way as immediately before the call to @freeze().
127  *
128  * @poweroff: Hibernation-specific, executed after saving a hibernation image.
129  *	Quiesce the device, put it into a low power state appropriate for the
130  *	upcoming system state (such as PCI_D3hot), and enable wakeup events as
131  *	appropriate.
132  *
133  * @restore: Hibernation-specific, executed after restoring the contents of main
134  *	memory from a hibernation image.  Driver starts working again,
135  *	responding to hardware events and software requests.  Drivers may NOT
136  *	make ANY assumptions about the hardware state right prior to @restore().
137  *	On most platforms, there are no restrictions on availability of
138  *	resources like clocks during @restore().
139  *
140  * @suspend_noirq: Complete the operations of ->suspend() by carrying out any
141  *	actions required for suspending the device that need interrupts to be
142  *	disabled
143  *
144  * @resume_noirq: Prepare for the execution of ->resume() by carrying out any
145  *	actions required for resuming the device that need interrupts to be
146  *	disabled
147  *
148  * @freeze_noirq: Complete the operations of ->freeze() by carrying out any
149  *	actions required for freezing the device that need interrupts to be
150  *	disabled
151  *
152  * @thaw_noirq: Prepare for the execution of ->thaw() by carrying out any
153  *	actions required for thawing the device that need interrupts to be
154  *	disabled
155  *
156  * @poweroff_noirq: Complete the operations of ->poweroff() by carrying out any
157  *	actions required for handling the device that need interrupts to be
158  *	disabled
159  *
160  * @restore_noirq: Prepare for the execution of ->restore() by carrying out any
161  *	actions required for restoring the operations of the device that need
162  *	interrupts to be disabled
163  *
164  * All of the above callbacks, except for @complete(), return error codes.
165  * However, the error codes returned by the resume operations, @resume(),
166  * @thaw(), @restore(), @resume_noirq(), @thaw_noirq(), and @restore_noirq() do
167  * not cause the PM core to abort the resume transition during which they are
168  * returned.  The error codes returned in that cases are only printed by the PM
169  * core to the system logs for debugging purposes.  Still, it is recommended
170  * that drivers only return error codes from their resume methods in case of an
171  * unrecoverable failure (i.e. when the device being handled refuses to resume
172  * and becomes unusable) to allow us to modify the PM core in the future, so
173  * that it can avoid attempting to handle devices that failed to resume and
174  * their children.
175  *
176  * It is allowed to unregister devices while the above callbacks are being
177  * executed.  However, it is not allowed to unregister a device from within any
178  * of its own callbacks.
179  *
180  * There also are the following callbacks related to run-time power management
181  * of devices:
182  *
183  * @runtime_suspend: Prepare the device for a condition in which it won't be
184  *	able to communicate with the CPU(s) and RAM due to power management.
185  *	This need not mean that the device should be put into a low power state.
186  *	For example, if the device is behind a link which is about to be turned
187  *	off, the device may remain at full power.  If the device does go to low
188  *	power and is capable of generating run-time wake-up events, remote
189  *	wake-up (i.e., a hardware mechanism allowing the device to request a
190  *	change of its power state via a wake-up event, such as PCI PME) should
191  *	be enabled for it.
192  *
193  * @runtime_resume: Put the device into the fully active state in response to a
194  *	wake-up event generated by hardware or at the request of software.  If
195  *	necessary, put the device into the full power state and restore its
196  *	registers, so that it is fully operational.
197  *
198  * @runtime_idle: Device appears to be inactive and it might be put into a low
199  *	power state if all of the necessary conditions are satisfied.  Check
200  *	these conditions and handle the device as appropriate, possibly queueing
201  *	a suspend request for it.  The return value is ignored by the PM core.
202  */
203 
204 struct dev_pm_ops {
205 	int (*prepare)(struct device *dev);
206 	void (*complete)(struct device *dev);
207 	int (*suspend)(struct device *dev);
208 	int (*resume)(struct device *dev);
209 	int (*freeze)(struct device *dev);
210 	int (*thaw)(struct device *dev);
211 	int (*poweroff)(struct device *dev);
212 	int (*restore)(struct device *dev);
213 	int (*suspend_noirq)(struct device *dev);
214 	int (*resume_noirq)(struct device *dev);
215 	int (*freeze_noirq)(struct device *dev);
216 	int (*thaw_noirq)(struct device *dev);
217 	int (*poweroff_noirq)(struct device *dev);
218 	int (*restore_noirq)(struct device *dev);
219 	int (*runtime_suspend)(struct device *dev);
220 	int (*runtime_resume)(struct device *dev);
221 	int (*runtime_idle)(struct device *dev);
222 };
223 
224 #ifdef CONFIG_PM_SLEEP
225 #define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
226 	.suspend = suspend_fn, \
227 	.resume = resume_fn, \
228 	.freeze = suspend_fn, \
229 	.thaw = resume_fn, \
230 	.poweroff = suspend_fn, \
231 	.restore = resume_fn,
232 #else
233 #define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
234 #endif
235 
236 #ifdef CONFIG_PM_RUNTIME
237 #define SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) \
238 	.runtime_suspend = suspend_fn, \
239 	.runtime_resume = resume_fn, \
240 	.runtime_idle = idle_fn,
241 #else
242 #define SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn)
243 #endif
244 
245 /*
246  * Use this if you want to use the same suspend and resume callbacks for suspend
247  * to RAM and hibernation.
248  */
249 #define SIMPLE_DEV_PM_OPS(name, suspend_fn, resume_fn) \
250 const struct dev_pm_ops name = { \
251 	SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
252 }
253 
254 /*
255  * Use this for defining a set of PM operations to be used in all situations
256  * (sustem suspend, hibernation or runtime PM).
257  */
258 #define UNIVERSAL_DEV_PM_OPS(name, suspend_fn, resume_fn, idle_fn) \
259 const struct dev_pm_ops name = { \
260 	SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
261 	SET_RUNTIME_PM_OPS(suspend_fn, resume_fn, idle_fn) \
262 }
263 
264 /*
265  * Use this for subsystems (bus types, device types, device classes) that don't
266  * need any special suspend/resume handling in addition to invoking the PM
267  * callbacks provided by device drivers supporting both the system sleep PM and
268  * runtime PM, make the pm member point to generic_subsys_pm_ops.
269  */
270 #ifdef CONFIG_PM_OPS
271 extern struct dev_pm_ops generic_subsys_pm_ops;
272 #define GENERIC_SUBSYS_PM_OPS	(&generic_subsys_pm_ops)
273 #else
274 #define GENERIC_SUBSYS_PM_OPS	NULL
275 #endif
276 
277 /**
278  * PM_EVENT_ messages
279  *
280  * The following PM_EVENT_ messages are defined for the internal use of the PM
281  * core, in order to provide a mechanism allowing the high level suspend and
282  * hibernation code to convey the necessary information to the device PM core
283  * code:
284  *
285  * ON		No transition.
286  *
287  * FREEZE 	System is going to hibernate, call ->prepare() and ->freeze()
288  *		for all devices.
289  *
290  * SUSPEND	System is going to suspend, call ->prepare() and ->suspend()
291  *		for all devices.
292  *
293  * HIBERNATE	Hibernation image has been saved, call ->prepare() and
294  *		->poweroff() for all devices.
295  *
296  * QUIESCE	Contents of main memory are going to be restored from a (loaded)
297  *		hibernation image, call ->prepare() and ->freeze() for all
298  *		devices.
299  *
300  * RESUME	System is resuming, call ->resume() and ->complete() for all
301  *		devices.
302  *
303  * THAW		Hibernation image has been created, call ->thaw() and
304  *		->complete() for all devices.
305  *
306  * RESTORE	Contents of main memory have been restored from a hibernation
307  *		image, call ->restore() and ->complete() for all devices.
308  *
309  * RECOVER	Creation of a hibernation image or restoration of the main
310  *		memory contents from a hibernation image has failed, call
311  *		->thaw() and ->complete() for all devices.
312  *
313  * The following PM_EVENT_ messages are defined for internal use by
314  * kernel subsystems.  They are never issued by the PM core.
315  *
316  * USER_SUSPEND		Manual selective suspend was issued by userspace.
317  *
318  * USER_RESUME		Manual selective resume was issued by userspace.
319  *
320  * REMOTE_WAKEUP	Remote-wakeup request was received from the device.
321  *
322  * AUTO_SUSPEND		Automatic (device idle) runtime suspend was
323  *			initiated by the subsystem.
324  *
325  * AUTO_RESUME		Automatic (device needed) runtime resume was
326  *			requested by a driver.
327  */
328 
329 #define PM_EVENT_ON		0x0000
330 #define PM_EVENT_FREEZE 	0x0001
331 #define PM_EVENT_SUSPEND	0x0002
332 #define PM_EVENT_HIBERNATE	0x0004
333 #define PM_EVENT_QUIESCE	0x0008
334 #define PM_EVENT_RESUME		0x0010
335 #define PM_EVENT_THAW		0x0020
336 #define PM_EVENT_RESTORE	0x0040
337 #define PM_EVENT_RECOVER	0x0080
338 #define PM_EVENT_USER		0x0100
339 #define PM_EVENT_REMOTE		0x0200
340 #define PM_EVENT_AUTO		0x0400
341 
342 #define PM_EVENT_SLEEP		(PM_EVENT_SUSPEND | PM_EVENT_HIBERNATE)
343 #define PM_EVENT_USER_SUSPEND	(PM_EVENT_USER | PM_EVENT_SUSPEND)
344 #define PM_EVENT_USER_RESUME	(PM_EVENT_USER | PM_EVENT_RESUME)
345 #define PM_EVENT_REMOTE_RESUME	(PM_EVENT_REMOTE | PM_EVENT_RESUME)
346 #define PM_EVENT_AUTO_SUSPEND	(PM_EVENT_AUTO | PM_EVENT_SUSPEND)
347 #define PM_EVENT_AUTO_RESUME	(PM_EVENT_AUTO | PM_EVENT_RESUME)
348 
349 #define PMSG_ON		((struct pm_message){ .event = PM_EVENT_ON, })
350 #define PMSG_FREEZE	((struct pm_message){ .event = PM_EVENT_FREEZE, })
351 #define PMSG_QUIESCE	((struct pm_message){ .event = PM_EVENT_QUIESCE, })
352 #define PMSG_SUSPEND	((struct pm_message){ .event = PM_EVENT_SUSPEND, })
353 #define PMSG_HIBERNATE	((struct pm_message){ .event = PM_EVENT_HIBERNATE, })
354 #define PMSG_RESUME	((struct pm_message){ .event = PM_EVENT_RESUME, })
355 #define PMSG_THAW	((struct pm_message){ .event = PM_EVENT_THAW, })
356 #define PMSG_RESTORE	((struct pm_message){ .event = PM_EVENT_RESTORE, })
357 #define PMSG_RECOVER	((struct pm_message){ .event = PM_EVENT_RECOVER, })
358 #define PMSG_USER_SUSPEND	((struct pm_message) \
359 					{ .event = PM_EVENT_USER_SUSPEND, })
360 #define PMSG_USER_RESUME	((struct pm_message) \
361 					{ .event = PM_EVENT_USER_RESUME, })
362 #define PMSG_REMOTE_RESUME	((struct pm_message) \
363 					{ .event = PM_EVENT_REMOTE_RESUME, })
364 #define PMSG_AUTO_SUSPEND	((struct pm_message) \
365 					{ .event = PM_EVENT_AUTO_SUSPEND, })
366 #define PMSG_AUTO_RESUME	((struct pm_message) \
367 					{ .event = PM_EVENT_AUTO_RESUME, })
368 
369 /**
370  * Device power management states
371  *
372  * These state labels are used internally by the PM core to indicate the current
373  * status of a device with respect to the PM core operations.
374  *
375  * DPM_ON		Device is regarded as operational.  Set this way
376  *			initially and when ->complete() is about to be called.
377  *			Also set when ->prepare() fails.
378  *
379  * DPM_PREPARING	Device is going to be prepared for a PM transition.  Set
380  *			when ->prepare() is about to be called.
381  *
382  * DPM_RESUMING		Device is going to be resumed.  Set when ->resume(),
383  *			->thaw(), or ->restore() is about to be called.
384  *
385  * DPM_SUSPENDING	Device has been prepared for a power transition.  Set
386  *			when ->prepare() has just succeeded.
387  *
388  * DPM_OFF		Device is regarded as inactive.  Set immediately after
389  *			->suspend(), ->freeze(), or ->poweroff() has succeeded.
390  *			Also set when ->resume()_noirq, ->thaw_noirq(), or
391  *			->restore_noirq() is about to be called.
392  *
393  * DPM_OFF_IRQ		Device is in a "deep sleep".  Set immediately after
394  *			->suspend_noirq(), ->freeze_noirq(), or
395  *			->poweroff_noirq() has just succeeded.
396  */
397 
398 enum dpm_state {
399 	DPM_INVALID,
400 	DPM_ON,
401 	DPM_PREPARING,
402 	DPM_RESUMING,
403 	DPM_SUSPENDING,
404 	DPM_OFF,
405 	DPM_OFF_IRQ,
406 };
407 
408 /**
409  * Device run-time power management status.
410  *
411  * These status labels are used internally by the PM core to indicate the
412  * current status of a device with respect to the PM core operations.  They do
413  * not reflect the actual power state of the device or its status as seen by the
414  * driver.
415  *
416  * RPM_ACTIVE		Device is fully operational.  Indicates that the device
417  *			bus type's ->runtime_resume() callback has completed
418  *			successfully.
419  *
420  * RPM_SUSPENDED	Device bus type's ->runtime_suspend() callback has
421  *			completed successfully.  The device is regarded as
422  *			suspended.
423  *
424  * RPM_RESUMING		Device bus type's ->runtime_resume() callback is being
425  *			executed.
426  *
427  * RPM_SUSPENDING	Device bus type's ->runtime_suspend() callback is being
428  *			executed.
429  */
430 
431 enum rpm_status {
432 	RPM_ACTIVE = 0,
433 	RPM_RESUMING,
434 	RPM_SUSPENDED,
435 	RPM_SUSPENDING,
436 };
437 
438 /**
439  * Device run-time power management request types.
440  *
441  * RPM_REQ_NONE		Do nothing.
442  *
443  * RPM_REQ_IDLE		Run the device bus type's ->runtime_idle() callback
444  *
445  * RPM_REQ_SUSPEND	Run the device bus type's ->runtime_suspend() callback
446  *
447  * RPM_REQ_AUTOSUSPEND	Same as RPM_REQ_SUSPEND, but not until the device has
448  *			been inactive for as long as power.autosuspend_delay
449  *
450  * RPM_REQ_RESUME	Run the device bus type's ->runtime_resume() callback
451  */
452 
453 enum rpm_request {
454 	RPM_REQ_NONE = 0,
455 	RPM_REQ_IDLE,
456 	RPM_REQ_SUSPEND,
457 	RPM_REQ_AUTOSUSPEND,
458 	RPM_REQ_RESUME,
459 };
460 
461 struct wakeup_source;
462 
463 struct dev_pm_info {
464 	pm_message_t		power_state;
465 	unsigned int		can_wakeup:1;
466 	unsigned		async_suspend:1;
467 	enum dpm_state		status;		/* Owned by the PM core */
468 	spinlock_t		lock;
469 #ifdef CONFIG_PM_SLEEP
470 	struct list_head	entry;
471 	struct completion	completion;
472 	struct wakeup_source	*wakeup;
473 #endif
474 #ifdef CONFIG_PM_RUNTIME
475 	struct timer_list	suspend_timer;
476 	unsigned long		timer_expires;
477 	struct work_struct	work;
478 	wait_queue_head_t	wait_queue;
479 	atomic_t		usage_count;
480 	atomic_t		child_count;
481 	unsigned int		disable_depth:3;
482 	unsigned int		ignore_children:1;
483 	unsigned int		idle_notification:1;
484 	unsigned int		request_pending:1;
485 	unsigned int		deferred_resume:1;
486 	unsigned int		run_wake:1;
487 	unsigned int		runtime_auto:1;
488 	unsigned int		no_callbacks:1;
489 	unsigned int		use_autosuspend:1;
490 	unsigned int		timer_autosuspends:1;
491 	enum rpm_request	request;
492 	enum rpm_status		runtime_status;
493 	int			runtime_error;
494 	int			autosuspend_delay;
495 	unsigned long		last_busy;
496 	unsigned long		active_jiffies;
497 	unsigned long		suspended_jiffies;
498 	unsigned long		accounting_timestamp;
499 #endif
500 };
501 
502 extern void update_pm_runtime_accounting(struct device *dev);
503 
504 
505 /*
506  * The PM_EVENT_ messages are also used by drivers implementing the legacy
507  * suspend framework, based on the ->suspend() and ->resume() callbacks common
508  * for suspend and hibernation transitions, according to the rules below.
509  */
510 
511 /* Necessary, because several drivers use PM_EVENT_PRETHAW */
512 #define PM_EVENT_PRETHAW PM_EVENT_QUIESCE
513 
514 /*
515  * One transition is triggered by resume(), after a suspend() call; the
516  * message is implicit:
517  *
518  * ON		Driver starts working again, responding to hardware events
519  * 		and software requests.  The hardware may have gone through
520  * 		a power-off reset, or it may have maintained state from the
521  * 		previous suspend() which the driver will rely on while
522  * 		resuming.  On most platforms, there are no restrictions on
523  * 		availability of resources like clocks during resume().
524  *
525  * Other transitions are triggered by messages sent using suspend().  All
526  * these transitions quiesce the driver, so that I/O queues are inactive.
527  * That commonly entails turning off IRQs and DMA; there may be rules
528  * about how to quiesce that are specific to the bus or the device's type.
529  * (For example, network drivers mark the link state.)  Other details may
530  * differ according to the message:
531  *
532  * SUSPEND	Quiesce, enter a low power device state appropriate for
533  * 		the upcoming system state (such as PCI_D3hot), and enable
534  * 		wakeup events as appropriate.
535  *
536  * HIBERNATE	Enter a low power device state appropriate for the hibernation
537  * 		state (eg. ACPI S4) and enable wakeup events as appropriate.
538  *
539  * FREEZE	Quiesce operations so that a consistent image can be saved;
540  * 		but do NOT otherwise enter a low power device state, and do
541  * 		NOT emit system wakeup events.
542  *
543  * PRETHAW	Quiesce as if for FREEZE; additionally, prepare for restoring
544  * 		the system from a snapshot taken after an earlier FREEZE.
545  * 		Some drivers will need to reset their hardware state instead
546  * 		of preserving it, to ensure that it's never mistaken for the
547  * 		state which that earlier snapshot had set up.
548  *
549  * A minimally power-aware driver treats all messages as SUSPEND, fully
550  * reinitializes its device during resume() -- whether or not it was reset
551  * during the suspend/resume cycle -- and can't issue wakeup events.
552  *
553  * More power-aware drivers may also use low power states at runtime as
554  * well as during system sleep states like PM_SUSPEND_STANDBY.  They may
555  * be able to use wakeup events to exit from runtime low-power states,
556  * or from system low-power states such as standby or suspend-to-RAM.
557  */
558 
559 #ifdef CONFIG_PM_SLEEP
560 extern void device_pm_lock(void);
561 extern int sysdev_resume(void);
562 extern void dpm_resume_noirq(pm_message_t state);
563 extern void dpm_resume_end(pm_message_t state);
564 
565 extern void device_pm_unlock(void);
566 extern int sysdev_suspend(pm_message_t state);
567 extern int dpm_suspend_noirq(pm_message_t state);
568 extern int dpm_suspend_start(pm_message_t state);
569 
570 extern void __suspend_report_result(const char *function, void *fn, int ret);
571 
572 #define suspend_report_result(fn, ret)					\
573 	do {								\
574 		__suspend_report_result(__func__, fn, ret);		\
575 	} while (0)
576 
577 extern int device_pm_wait_for_dev(struct device *sub, struct device *dev);
578 #else /* !CONFIG_PM_SLEEP */
579 
580 #define device_pm_lock() do {} while (0)
581 #define device_pm_unlock() do {} while (0)
582 
583 static inline int dpm_suspend_start(pm_message_t state)
584 {
585 	return 0;
586 }
587 
588 #define suspend_report_result(fn, ret)		do {} while (0)
589 
590 static inline int device_pm_wait_for_dev(struct device *a, struct device *b)
591 {
592 	return 0;
593 }
594 #endif /* !CONFIG_PM_SLEEP */
595 
596 /* How to reorder dpm_list after device_move() */
597 enum dpm_order {
598 	DPM_ORDER_NONE,
599 	DPM_ORDER_DEV_AFTER_PARENT,
600 	DPM_ORDER_PARENT_BEFORE_DEV,
601 	DPM_ORDER_DEV_LAST,
602 };
603 
604 /*
605  * Global Power Management flags
606  * Used to keep APM and ACPI from both being active
607  */
608 extern unsigned int	pm_flags;
609 
610 #define PM_APM	1
611 #define PM_ACPI	2
612 
613 #endif /* _LINUX_PM_H */
614