#ifndef _LINUX_ALARMTIMER_H
  #define _LINUX_ALARMTIMER_H
  
  #include <linux/time.h>
  #include <linux/hrtimer.h>
  #include <linux/timerqueue.h>
  #include <linux/rtc.h>
  
  enum alarmtimer_type {
  	ALARM_REALTIME,
  	ALARM_BOOTTIME,
  
  	ALARM_NUMTYPE,
  };

  enum alarmtimer_restart {
  	ALARMTIMER_NORESTART,
  	ALARMTIMER_RESTART,
  };

  
  #define ALARMTIMER_STATE_INACTIVE	0x00
  #define ALARMTIMER_STATE_ENQUEUED	0x01
  #define ALARMTIMER_STATE_CALLBACK	0x02

  /**
   * struct alarm - Alarm timer structure
   * @node:	timerqueue node for adding to the event list this value
   *		also includes the expiration time.
   * @period:	Period for recuring alarms
   * @function:	Function pointer to be executed when the timer fires.
   * @type:	Alarm type (BOOTTIME/REALTIME)
   * @enabled:	Flag that represents if the alarm is set to fire or not
   * @data:	Internal data value.
   */

  struct alarm {
  	struct timerqueue_node	node;

  	enum alarmtimer_restart	(*function)(struct alarm *, ktime_t now);

  	enum alarmtimer_type	type;

  	int			state;

  	void			*data;
  };
  
  void alarm_init(struct alarm *alarm, enum alarmtimer_type type,

  		enum alarmtimer_restart (*function)(struct alarm *, ktime_t));

  void alarm_start(struct alarm *alarm, ktime_t start);

  int alarm_try_to_cancel(struct alarm *alarm);
  int alarm_cancel(struct alarm *alarm);

  u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval);

  /*
   * A alarmtimer is active, when it is enqueued into timerqueue or the
   * callback function is running.
   */
  static inline int alarmtimer_active(const struct alarm *timer)
  {
  	return timer->state != ALARMTIMER_STATE_INACTIVE;
  }
  
  /*
   * Helper function to check, whether the timer is on one of the queues
   */
  static inline int alarmtimer_is_queued(struct alarm *timer)
  {
  	return timer->state & ALARMTIMER_STATE_ENQUEUED;
  }
  
  /*
   * Helper function to check, whether the timer is running the callback
   * function
   */
  static inline int alarmtimer_callback_running(struct alarm *timer)
  {
  	return timer->state & ALARMTIMER_STATE_CALLBACK;
  }

  #endif