include/linux/pm.h

1 /* SPDX-License-Identifier: GPL-2.0-or-later */
3  *  pm.h - Power management interface
39  * Device power management
45 extern const char power_group_name[];		/* = "power" */
55  * struct dev_pm_ops - device PM callbacks.
57  * @prepare: The principal role of this callback is to prevent new children of
62  *	registration of a child already in progress), it may return -EAGAIN, so
72  *	runtime-suspended and it may be left in that state during the entire
77  *	The PM core executes subsystem-level @prepare() for all devices before
95  *	The PM core executes subsystem-level @complete() after it has executed
103  *	@complete() can check the power.direct_complete flag of the device to
110  *	type), but generally the device must be quiescent after subsystem-level
112  *	Subsystem-level @suspend() is executed for all devices after invoking
113  *	subsystem-level @prepare() for all of them.
123  *	requests (the device itself may be left in a low-power state, waiting
128  *	Subsystem-level @resume() is executed for all devices after invoking
129  *	subsystem-level @resume_noirq() for all of them.
135  * @freeze: Hibernation-specific, executed before creating a hibernation image.
137  *	wakeup events or change its power state.  The majority of subsystems
138  *	(with the notable exception of the PCI bus type) expect the driver-level
141  *	Subsystem-level @freeze() is executed for all devices after invoking
142  *	subsystem-level @prepare() for all of them.
146  *	events or change its power state.
148  * @thaw: Hibernation-specific, executed after creating a hibernation image OR
153  *	Subsystem-level @thaw() is executed for all devices after invoking
154  *	subsystem-level @thaw_noirq() for all of them.  It also may be executed
160  * @poweroff: Hibernation-specific, executed after saving a hibernation image.
163  *	Subsystem-level @poweroff() is executed for all devices after invoking
164  *	subsystem-level @prepare() for all of them.
169  * @restore: Hibernation-specific, executed after restoring the contents of main
178  *	It generally is expected that the device will be in a low-power state
179  *	(appropriate for the target system sleep state) after subsystem-level
184  *	put the device into the low-power state and configure it to generate
197  *	The power state of the device should not be changed by either @freeze(),
215  *	able to communicate with the CPU(s) and RAM due to power management.
216  *	This need not mean that the device should be put into a low-power state.
218  *	off, the device may remain at full power.  If the device does go to low
219  *	power and is capable of generating runtime wakeup events, remote wakeup
221  *	its power state via an interrupt) should be enabled for it.
225  *	necessary, put the device into the full-power state and restore its
229  *	low-power state if all of the necessary conditions are satisfied.
233  * Several device power state transitions are externally visible, affecting
236  * internal transitions to various low-power modes which are transparent
243  * domains, device types, classes and bus types.  They are the subsystem-level
246  * have to collaborate with the subsystem-level callbacks to achieve the goals
262  * executed.  However, a callback routine MUST NOT try to unregister the device
267  * There also are callbacks related to runtime power management of devices.
269  * (PM domains, device types, classes and bus types) and the subsystem-level
274  * Refer to Documentation/power/runtime_pm.rst for more information about the
275  * role of the @runtime_suspend(), @runtime_resume() and @runtime_idle()
276  * callbacks in device runtime power management.
393  * FREEZE	System is going to hibernate, call ->prepare() and ->freeze()
396  * SUSPEND	System is going to suspend, call ->prepare() and ->suspend()
399  * HIBERNATE	Hibernation image has been saved, call ->prepare() and
400  *		->poweroff() for all devices.
403  *		hibernation image, call ->prepare() and ->freeze() for all
406  * RESUME	System is resuming, call ->resume() and ->complete() for all
409  * THAW		Hibernation image has been created, call ->thaw() and
410  *		->complete() for all devices.
413  *		image, call ->restore() and ->complete() for all devices.
417  *		->thaw() and ->complete() for all devices.
426  * REMOTE_WAKEUP	Remote-wakeup request was received from the device.
435 #define PM_EVENT_INVALID	(-1)
480  * Device run-time power management status.
484  * not reflect the actual power state of the device or its status as seen by the
488  *			bus type's ->runtime_resume() callback has completed
491  * RPM_SUSPENDED	Device bus type's ->runtime_suspend() callback has
495  * RPM_RESUMING		Device bus type's ->runtime_resume() callback is being
498  * RPM_SUSPENDING	Device bus type's ->runtime_suspend() callback is being
510  * Device run-time power management request types.
514  * RPM_REQ_IDLE		Run the device bus type's ->runtime_idle() callback
516  * RPM_REQ_SUSPEND	Run the device bus type's ->runtime_suspend() callback
519  *			been inactive for as long as power.autosuspend_delay
521  * RPM_REQ_RESUME	Run the device bus type's ->runtime_resume() callback
553  * NO_DIRECT_COMPLETE: Do not apply direct-complete optimization to the device.
554  * SMART_PREPARE: Take the driver ->prepare callback return value into account.
558  * See Documentation/driver-api/pm/devices.rst for details.
629  * struct dev_pm_domain - power management domain representation.
631  * @ops: Power management operations associated with this domain.
638  * Power domains provide callbacks that are executed during system suspend,
640  * subsystem-level and driver-level callbacks.
653  * suspend framework, based on the ->suspend() and ->resume() callbacks common
666  *		a power-off reset, or it may have maintained state from the
678  * SUSPEND	Quiesce, enter a low power device state appropriate for
682  * HIBERNATE	Enter a low power device state appropriate for the hibernation
686  *		but do NOT otherwise enter a low power device state, and do
695  * A minimally power-aware driver treats all messages as SUSPEND, fully
696  * reinitializes its device during resume() -- whether or not it was reset
697  * during the suspend/resume cycle -- and can't issue wakeup events.
699  * More power-aware drivers may also use low power states at runtime as
701  * be able to use wakeup events to exit from runtime low-power states,
702  * or from system low-power states such as standby or suspend-to-RAM.