Supporting multiple CPU idle levels in kernel

				cpuidle drivers




cpuidle driver hooks into the cpuidle infrastructure and handles the
architecture/platform dependent part of CPU idle states. Driver
provides the platform idle state detection capability and also
has mechanisms in place to support actual entry-exit into CPU idle states.

cpuidle driver initializes the cpuidle_device structure for each CPU device
and registers with cpuidle using cpuidle_register_device.

If all the idle states are the same, the wrapper function cpuidle_register
could be used instead.

It can also support the dynamic changes (like battery <-> AC), by using
cpuidle_pause_and_lock, cpuidle_disable_device and cpuidle_enable_device,
cpuidle_resume_and_unlock.

Interfaces:
extern int cpuidle_register(struct cpuidle_driver *drv,
                            const struct cpumask *const coupled_cpus);
extern int cpuidle_unregister(struct cpuidle_driver *drv);
extern int cpuidle_register_driver(struct cpuidle_driver *drv);
extern void cpuidle_unregister_driver(struct cpuidle_driver *drv);
extern int cpuidle_register_device(struct cpuidle_device *dev);
extern void cpuidle_unregister_device(struct cpuidle_device *dev);

extern void cpuidle_pause_and_lock(void);
extern void cpuidle_resume_and_unlock(void);
extern int cpuidle_enable_device(struct cpuidle_device *dev);
extern void cpuidle_disable_device(struct cpuidle_device *dev);