Supporting multiple CPU idle levels in kernel cpuidle driverscpuidle driver hooks into the cpuidle infrastructure and handles thearchitecture/platform dependent part of CPU idle states. Driverprovides the platform idle state detection capability and alsohas mechanisms in place to support actual entry-exit into CPU idle states.cpuidle driver initializes the cpuidle_device structure for each CPU deviceand registers with cpuidle using cpuidle_register_device.It can also support the dynamic changes (like battery <-> AC), by usingcpuidle_pause_and_lock, cpuidle_disable_device and cpuidle_enable_device,cpuidle_resume_and_unlock.Interfaces: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);