+
+7. Generic subsystem callbacks
+
+Subsystems may wish to conserve code space by using the set of generic power
+management callbacks provided by the PM core, defined in
+driver/base/power/generic_ops.c:
+
+ int pm_generic_runtime_idle(struct device *dev);
+ - invoke the ->runtime_idle() callback provided by the driver of this
+ device, if defined, and call pm_runtime_suspend() for this device if the
+ return value is 0 or the callback is not defined
+
+ int pm_generic_runtime_suspend(struct device *dev);
+ - invoke the ->runtime_suspend() callback provided by the driver of this
+ device and return its result, or return -EINVAL if not defined
+
+ int pm_generic_runtime_resume(struct device *dev);
+ - invoke the ->runtime_resume() callback provided by the driver of this
+ device and return its result, or return -EINVAL if not defined
+
+ int pm_generic_suspend(struct device *dev);
+ - if the device has not been suspended at run time, invoke the ->suspend()
+ callback provided by its driver and return its result, or return 0 if not
+ defined
+
+ int pm_generic_resume(struct device *dev);
+ - invoke the ->resume() callback provided by the driver of this device and,
+ if successful, change the device's runtime PM status to 'active'
+
+ int pm_generic_freeze(struct device *dev);
+ - if the device has not been suspended at run time, invoke the ->freeze()
+ callback provided by its driver and return its result, or return 0 if not
+ defined
+
+ int pm_generic_thaw(struct device *dev);
+ - if the device has not been suspended at run time, invoke the ->thaw()
+ callback provided by its driver and return its result, or return 0 if not
+ defined
+
+ int pm_generic_poweroff(struct device *dev);
+ - if the device has not been suspended at run time, invoke the ->poweroff()
+ callback provided by its driver and return its result, or return 0 if not
+ defined
+
+ int pm_generic_restore(struct device *dev);
+ - invoke the ->restore() callback provided by the driver of this device and,
+ if successful, change the device's runtime PM status to 'active'
+
+These functions can be assigned to the ->runtime_idle(), ->runtime_suspend(),
+->runtime_resume(), ->suspend(), ->resume(), ->freeze(), ->thaw(), ->poweroff(),
+or ->restore() callback pointers in the subsystem-level dev_pm_ops structures.
+
+If a subsystem wishes to use all of them at the same time, it can simply assign
+the GENERIC_SUBSYS_PM_OPS macro, defined in include/linux/pm.h, to its
+dev_pm_ops structure pointer.
+
+Device drivers that wish to use the same function as a system suspend, freeze,
+poweroff and run-time suspend callback, and similarly for system resume, thaw,
+restore, and run-time resume, can achieve this with the help of the
+UNIVERSAL_DEV_PM_OPS macro defined in include/linux/pm.h (possibly setting its
+last argument to NULL).