Supporting multiple CPU idle levels in kernel

				cpuidle governors




cpuidle governor is policy routine that decides what idle state to enter at
any given time. cpuidle core uses different callbacks to the governor.

* enable() to enable governor for a particular device
* disable() to disable governor for a particular device
* select() to select an idle state to enter
* reflect() called after returning from the idle state, which can be used
  by the governor for some record keeping.

More than one governor can be registered at the same time and
users can switch between drivers using /sysfs interface (when enabled).
More than one governor part is supported for developers to easily experiment
with different governors. By default, most optimal governor based on your
kernel configuration and platform will be selected by cpuidle.

Interfaces:
extern int cpuidle_register_governor(struct cpuidle_governor *gov);
extern void cpuidle_unregister_governor(struct cpuidle_governor *gov);
struct cpuidle_governor