#ifndef _linux_POSIX_TIMERS_H
  #define _linux_POSIX_TIMERS_H
  
  #include <linux/spinlock.h>
  #include <linux/list.h>
  #include <linux/sched.h>

  #include <linux/timex.h>

  #include <linux/alarmtimer.h>

  
  static inline unsigned long long cputime_to_expires(cputime_t expires)
  {
  	return (__force unsigned long long)expires;
  }
  
  static inline cputime_t expires_to_cputime(unsigned long long expires)
  {
  	return (__force cputime_t)expires;
  }

  
  struct cpu_timer_list {
  	struct list_head entry;

  	unsigned long long expires, incr;

  	struct task_struct *task;
  	int firing;
  };

  /*
   * Bit fields within a clockid:
   *
   * The most significant 29 bits hold either a pid or a file descriptor.
   *
   * Bit 2 indicates whether a cpu clock refers to a thread or a process.
   *
   * Bits 1 and 0 give the type: PROF=0, VIRT=1, SCHED=2, or FD=3.
   *
   * A clockid is invalid if bits 2, 1, and 0 are all set.
   */

  #define CPUCLOCK_PID(clock)		((pid_t) ~((clock) >> 3))
  #define CPUCLOCK_PERTHREAD(clock) \
  	(((clock) & (clockid_t) CPUCLOCK_PERTHREAD_MASK) != 0)

  #define CPUCLOCK_PERTHREAD_MASK	4
  #define CPUCLOCK_WHICH(clock)	((clock) & (clockid_t) CPUCLOCK_CLOCK_MASK)
  #define CPUCLOCK_CLOCK_MASK	3
  #define CPUCLOCK_PROF		0
  #define CPUCLOCK_VIRT		1
  #define CPUCLOCK_SCHED		2
  #define CPUCLOCK_MAX		3

  #define CLOCKFD			CPUCLOCK_MAX
  #define CLOCKFD_MASK		(CPUCLOCK_PERTHREAD_MASK|CPUCLOCK_CLOCK_MASK)

  
  #define MAKE_PROCESS_CPUCLOCK(pid, clock) \
  	((~(clockid_t) (pid) << 3) | (clockid_t) (clock))
  #define MAKE_THREAD_CPUCLOCK(tid, clock) \
  	MAKE_PROCESS_CPUCLOCK((tid), (clock) | CPUCLOCK_PERTHREAD_MASK)

  #define FD_TO_CLOCKID(fd)	((~(clockid_t) (fd) << 3) | CLOCKFD)
  #define CLOCKID_TO_FD(clk)	((unsigned int) ~((clk) >> 3))

  /* POSIX.1b interval timer structure. */
  struct k_itimer {
  	struct list_head list;		/* free/ allocate list */

  	struct hlist_node t_hash;

  	spinlock_t it_lock;
  	clockid_t it_clock;		/* which timer type */
  	timer_t it_id;			/* timer id */
  	int it_overrun;			/* overrun on pending signal  */
  	int it_overrun_last;		/* overrun on last delivered signal */

  	int it_requeue_pending;		/* waiting to requeue this timer */

  #define REQUEUE_PENDING 1
  	int it_sigev_notify;		/* notify word of sigevent struct */

  	struct signal_struct *it_signal;
  	union {
  		struct pid *it_pid;	/* pid of process to send signal to */
  		struct task_struct *it_process;	/* for clock_nanosleep */
  	};

  	struct sigqueue *sigq;		/* signal queue entry. */
  	union {
  		struct {

  			struct hrtimer timer;
  			ktime_t interval;

  		} real;
  		struct cpu_timer_list cpu;
  		struct {
  			unsigned int clock;
  			unsigned int node;
  			unsigned long incr;
  			unsigned long expires;
  		} mmtimer;

  		struct {
  			struct alarm alarmtimer;
  			ktime_t interval;
  		} alarm;

  		struct rcu_head rcu;

  	} it;
  };

  struct k_clock {

  	int (*clock_getres) (const clockid_t which_clock, struct timespec *tp);

  	int (*clock_set) (const clockid_t which_clock,
  			  const struct timespec *tp);

  	int (*clock_get) (const clockid_t which_clock, struct timespec * tp);

  	int (*clock_adj) (const clockid_t which_clock, struct timex *tx);

  	int (*timer_create) (struct k_itimer *timer);

  	int (*nsleep) (const clockid_t which_clock, int flags,

  		       struct timespec *, struct timespec __user *);

  	long (*nsleep_restart) (struct restart_block *restart_block);

  	int (*timer_set) (struct k_itimer * timr, int flags,
  			  struct itimerspec * new_setting,
  			  struct itimerspec * old_setting);
  	int (*timer_del) (struct k_itimer * timr);
  #define TIMER_RETRY 1
  	void (*timer_get) (struct k_itimer * timr,
  			   struct itimerspec * cur_setting);
  };

  extern struct k_clock clock_posix_cpu;

  extern struct k_clock clock_posix_dynamic;

  void posix_timers_register_clock(const clockid_t clock_id, struct k_clock *new_clock);

  /* function to call to trigger timer event */
  int posix_timer_event(struct k_itimer *timr, int si_private);

  void posix_cpu_timer_schedule(struct k_itimer *timer);
  
  void run_posix_cpu_timers(struct task_struct *task);
  void posix_cpu_timers_exit(struct task_struct *task);
  void posix_cpu_timers_exit_group(struct task_struct *task);

  bool posix_cpu_timers_can_stop_tick(struct task_struct *tsk);

  void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx,
  			   cputime_t *newval, cputime_t *oldval);

  long clock_nanosleep_restart(struct restart_block *restart_block);

  void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new);

  #endif