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);