text: /*
   *  include/linux/hrtimer.h
   *
   *  hrtimers - High-resolution kernel timers
   *
   *   Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
   *   Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
   *
   *  data type definitions, declarations, prototypes
   *
   *  Started by: Thomas Gleixner and Ingo Molnar
   *
   *  For licencing details see kernel-base/COPYING
   */
  #ifndef _LINUX_HRTIMER_H
  #define _LINUX_HRTIMER_H
  
  #include <linux/rbtree.h>
  #include <linux/ktime.h>
  #include <linux/init.h>
  #include <linux/list.h>
  #include <linux/wait.h>
  #include <linux/percpu.h>
  #include <linux/timer.h>
  #include <linux/timerqueue.h>
  
  struct hrtimer_clock_base;
  struct hrtimer_cpu_base;
  
  /*
   * Mode arguments of xxx_hrtimer functions:
   */
  enum hrtimer_mode {
  	HRTIMER_MODE_ABS = 0x0,		/* Time value is absolute */
  	HRTIMER_MODE_REL = 0x1,		/* Time value is relative to now */
  	HRTIMER_MODE_PINNED = 0x02,	/* Timer is bound to CPU */
  	HRTIMER_MODE_ABS_PINNED = 0x02,
  	HRTIMER_MODE_REL_PINNED = 0x03,
  };
  
  /*
   * Return values for the callback function
   */
  enum hrtimer_restart {
  	HRTIMER_NORESTART,	/* Timer is not restarted */
  	HRTIMER_RESTART,	/* Timer must be restarted */
  };
  
  /*
   * Values to track state of the timer
   *
   * Possible states:
   *
   * 0x00		inactive
   * 0x01		enqueued into rbtree
   * 0x02		callback function running
   * 0x04		timer is migrated to another cpu
   *
   * Special cases:
   * 0x03		callback function running and enqueued
   *		(was requeued on another CPU)
   * 0x05		timer was migrated on CPU hotunplug
   *
   * The "callback function running and enqueued" status is only possible on
   * SMP. It happens for example when a posix timer expired and the callback
   * queued a signal. Between dropping the lock which protects the posix timer
   * and reacquiring the base lock of the hrtimer, another CPU can deliver the
   * signal and rearm the timer. We have to preserve the callback running state,
   * as otherwise the timer could be removed before the softirq code finishes the
   * the handling of the timer.
   *
   * The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state
   * to preserve the HRTIMER_STATE_CALLBACK in the above scenario. This
   * also affects HRTIMER_STATE_MIGRATE where the preservation is not
   * necessary. HRTIMER_STATE_MIGRATE is cleared after the timer is
   * enqueued on the new cpu.
   *
   * All state transitions are protected by cpu_base->lock.
   */
  #define HRTIMER_STATE_INACTIVE	0x00
  #define HRTIMER_STATE_ENQUEUED	0x01
  #define HRTIMER_STATE_CALLBACK	0x02
  #define HRTIMER_STATE_MIGRATE	0x04
  
  /**
   * struct hrtimer - the basic hrtimer structure
   * @node:	timerqueue node, which also manages node.expires,
   *		the absolute expiry time in the hrtimers internal
   *		representation. The time is related to the clock on
   *		which the timer is based. Is setup by adding
   *		slack to the _softexpires value. For non range timers
   *		identical to _softexpires.
   * @_softexpires: the absolute earliest expiry time of the hrtimer.
   *		The time which was given as expiry time when the timer
   *		was armed.
   * @function:	timer expiry callback function
   * @base:	pointer to the timer base (per cpu and per clock)
   * @state:	state information (See bit values above)
   * @start_site:	timer statistics field to store the site where the timer
   *		was started
   * @start_comm: timer statistics field to store the name of the process which
   *		started the timer
   * @start_pid: timer statistics field to store the pid of the task which
   *		started the timer
   *
   * The hrtimer structure must be initialized by hrtimer_init()
   */
  struct hrtimer {
  	struct timerqueue_node		node;
  	ktime_t				_softexpires;
  	enum hrtimer_restart		(*function)(struct hrtimer *);
  	struct hrtimer_clock_base	*base;
  	unsigned long			state;
  #ifdef CONFIG_TIMER_STATS
  	int				start_pid;
  	void				*start_site;
  	char				start_comm[16];
  #endif
  };
  
  /**
   * struct hrtimer_sleeper - simple sleeper structure
   * @timer:	embedded timer structure
   * @task:	task to wake up
   *
   * task is set to NULL, when the timer expires.
   */
  struct hrtimer_sleeper {
  	struct hrtimer timer;
  	struct task_struct *task;
  };
  
  /**
   * struct hrtimer_clock_base - the timer base for a specific clock
   * @cpu_base:		per cpu clock base
   * @index:		clock type index for per_cpu support when moving a
   *			timer to a base on another cpu.
   * @clockid:		clock id for per_cpu support
   * @active:		red black tree root node for the active timers
   * @resolution:		the resolution of the clock, in nanoseconds
   * @get_time:		function to retrieve the current time of the clock
   * @softirq_time:	the time when running the hrtimer queue in the softirq
   * @offset:		offset of this clock to the monotonic base
   */
  struct hrtimer_clock_base {
  	struct hrtimer_cpu_base	*cpu_base;
  	int			index;
  	clockid_t		clockid;
  	struct timerqueue_head	active;
  	ktime_t			resolution;
  	ktime_t			(*get_time)(void);
  	ktime_t			softirq_time;
  	ktime_t			offset;
  };
  
  enum  hrtimer_base_type {
  	HRTIMER_BASE_MONOTONIC,
  	HRTIMER_BASE_REALTIME,
  	HRTIMER_BASE_BOOTTIME,
  	HRTIMER_BASE_TAI,
  	HRTIMER_MAX_CLOCK_BASES,
  };
  
  /*
   * struct hrtimer_cpu_base - the per cpu clock bases
   * @lock:		lock protecting the base and associated clock bases
   *			and timers
   * @active_bases:	Bitfield to mark bases with active timers
   * @clock_was_set:	Indicates that clock was set from irq context.
   * @expires_next:	absolute time of the next event which was scheduled
   *			via clock_set_next_event()
   * @hres_active:	State of high resolution mode
   * @hang_detected:	The last hrtimer interrupt detected a hang
   * @nr_events:		Total number of hrtimer interrupt events
   * @nr_retries:		Total number of hrtimer interrupt retries
   * @nr_hangs:		Total number of hrtimer interrupt hangs
   * @max_hang_time:	Maximum time spent in hrtimer_interrupt
   * @clock_base:		array of clock bases for this cpu
   */
  struct hrtimer_cpu_base {
  	raw_spinlock_t			lock;
  	unsigned int			active_bases;
  	unsigned int			clock_was_set;
  #ifdef CONFIG_HIGH_RES_TIMERS
  	ktime_t				expires_next;
  	int				hres_active;
  	int				hang_detected;
  	unsigned long			nr_events;
  	unsigned long			nr_retries;
  	unsigned long			nr_hangs;
  	ktime_t				max_hang_time;
  #endif
  	struct hrtimer_clock_base	clock_base[HRTIMER_MAX_CLOCK_BASES];
  };
  
  static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
  {
  	timer->node.expires = time;
  	timer->_softexpires = time;
  }
  
  static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
  {
  	timer->_softexpires = time;
  	timer->node.expires = ktime_add_safe(time, delta);
  }
  
  static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
  {
  	timer->_softexpires = time;
  	timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
  }
  
  static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
  {
  	timer->node.expires.tv64 = tv64;
  	timer->_softexpires.tv64 = tv64;
  }
  
  static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
  {
  	timer->node.expires = ktime_add_safe(timer->node.expires, time);
  	timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
  }
  
  static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
  {
  	timer->node.expires = ktime_add_ns(timer->node.expires, ns);
  	timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
  }
  
  static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
  {
  	return timer->node.expires;
  }
  
  static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
  {
  	return timer->_softexpires;
  }
  
  static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
  {
  	return timer->node.expires.tv64;
  }
  static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
  {
  	return timer->_softexpires.tv64;
  }
  
  static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
  {
  	return ktime_to_ns(timer->node.expires);
  }
  
  static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
  {
  	return ktime_sub(timer->node.expires, timer->base->get_time());
  }
  
  #ifdef CONFIG_HIGH_RES_TIMERS
  struct clock_event_device;
  
  extern void hrtimer_interrupt(struct clock_event_device *dev);
  
  /*
   * In high resolution mode the time reference must be read accurate
   */
  static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
  {
  	return timer->base->get_time();
  }
  
  static inline int hrtimer_is_hres_active(struct hrtimer *timer)
  {
  	return timer->base->cpu_base->hres_active;
  }
  
  extern void hrtimer_peek_ahead_timers(void);
  
  /*
   * The resolution of the clocks. The resolution value is returned in
   * the clock_getres() system call to give application programmers an
   * idea of the (in)accuracy of timers. Timer values are rounded up to
   * this resolution values.
   */
  # define HIGH_RES_NSEC		1
  # define KTIME_HIGH_RES		(ktime_t) { .tv64 = HIGH_RES_NSEC }
  # define MONOTONIC_RES_NSEC	HIGH_RES_NSEC
  # define KTIME_MONOTONIC_RES	KTIME_HIGH_RES
  
  extern void clock_was_set_delayed(void);
  
  #else
  
  # define MONOTONIC_RES_NSEC	LOW_RES_NSEC
  # define KTIME_MONOTONIC_RES	KTIME_LOW_RES
  
  static inline void hrtimer_peek_ahead_timers(void) { }
  
  /*
   * In non high resolution mode the time reference is taken from
   * the base softirq time variable.
   */
  static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
  {
  	return timer->base->softirq_time;
  }
  
  static inline int hrtimer_is_hres_active(struct hrtimer *timer)
  {
  	return 0;
  }
  
  static inline void clock_was_set_delayed(void) { }
  
  #endif
  
  extern void clock_was_set(void);
  #ifdef CONFIG_TIMERFD
  extern void timerfd_clock_was_set(void);
  #else
  static inline void timerfd_clock_was_set(void) { }
  #endif
  extern void hrtimers_resume(void);
  
  extern ktime_t ktime_get(void);
  extern ktime_t ktime_get_real(void);
  extern ktime_t ktime_get_boottime(void);
  extern ktime_t ktime_get_monotonic_offset(void);
  extern ktime_t ktime_get_clocktai(void);
  extern ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot,
  					 ktime_t *offs_tai);
  
  DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
  
  
  /* Exported timer functions: */
  
  /* Initialize timers: */
  extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
  			 enum hrtimer_mode mode);
  
  #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
  extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
  				  enum hrtimer_mode mode);
  
  extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
  #else
  static inline void hrtimer_init_on_stack(struct hrtimer *timer,
  					 clockid_t which_clock,
  					 enum hrtimer_mode mode)
  {
  	hrtimer_init(timer, which_clock, mode);
  }
  static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
  #endif
  
  /* Basic timer operations: */
  extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
  			 const enum hrtimer_mode mode);
  extern int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
  			unsigned long range_ns, const enum hrtimer_mode mode);
  extern int
  __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
  			 unsigned long delta_ns,
  			 const enum hrtimer_mode mode, int wakeup);
  
  extern int hrtimer_cancel(struct hrtimer *timer);
  extern int hrtimer_try_to_cancel(struct hrtimer *timer);
  
  static inline int hrtimer_start_expires(struct hrtimer *timer,
  						enum hrtimer_mode mode)
  {
  	unsigned long delta;
  	ktime_t soft, hard;
  	soft = hrtimer_get_softexpires(timer);
  	hard = hrtimer_get_expires(timer);
  	delta = ktime_to_ns(ktime_sub(hard, soft));
  	return hrtimer_start_range_ns(timer, soft, delta, mode);
  }
  
  static inline int hrtimer_restart(struct hrtimer *timer)
  {
  	return hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
  }
  
  /* Query timers: */
  extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
  extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
  
  extern ktime_t hrtimer_get_next_event(void);
  
  /*
   * A timer is active, when it is enqueued into the rbtree or the
   * callback function is running or it's in the state of being migrated
   * to another cpu.
   */
  static inline int hrtimer_active(const struct hrtimer *timer)
  {
  	return timer->state != HRTIMER_STATE_INACTIVE;
  }
  
  /*
   * Helper function to check, whether the timer is on one of the queues
   */
  static inline int hrtimer_is_queued(struct hrtimer *timer)
  {
  	return timer->state & HRTIMER_STATE_ENQUEUED;
  }
  
  /*
   * Helper function to check, whether the timer is running the callback
   * function
   */
  static inline int hrtimer_callback_running(struct hrtimer *timer)
  {
  	return timer->state & HRTIMER_STATE_CALLBACK;
  }
  
  /* Forward a hrtimer so it expires after now: */
  extern u64
  hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
  
  /* Forward a hrtimer so it expires after the hrtimer's current now */
  static inline u64 hrtimer_forward_now(struct hrtimer *timer,
  				      ktime_t interval)
  {
  	return hrtimer_forward(timer, timer->base->get_time(), interval);
  }
  
  /* Precise sleep: */
  extern long hrtimer_nanosleep(struct timespec *rqtp,
  			      struct timespec __user *rmtp,
  			      const enum hrtimer_mode mode,
  			      const clockid_t clockid);
  extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
  
  extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
  				 struct task_struct *tsk);
  
  extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
  						const enum hrtimer_mode mode);
  extern int schedule_hrtimeout_range_clock(ktime_t *expires,
  		unsigned long delta, const enum hrtimer_mode mode, int clock);
  extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
  
  /* Soft interrupt function to run the hrtimer queues: */
  extern void hrtimer_run_queues(void);
  extern void hrtimer_run_pending(void);
  
  /* Bootup initialization: */
  extern void __init hrtimers_init(void);
  
  #if BITS_PER_LONG < 64
  extern u64 ktime_divns(const ktime_t kt, s64 div);
  #else /* BITS_PER_LONG < 64 */
  # define ktime_divns(kt, div)		(u64)((kt).tv64 / (div))
  #endif
  
  /* Show pending timers: */
  extern void sysrq_timer_list_show(void);
  
  #endif
  