include/linux/hrtimer.h

   1 /*
   2  *  include/linux/hrtimer.h
   3  *
   4  *  hrtimers - High-resolution kernel timers
   5  *
   6  *   Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
   7  *   Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
   8  *
   9  *  data type definitions, declarations, prototypes
  10  *
  11  *  Started by: Thomas Gleixner and Ingo Molnar
  12  *
  13  *  For licencing details see kernel-base/COPYING
  14  */
  15 #ifndef _LINUX_HRTIMER_H
  16 #define _LINUX_HRTIMER_H
  17
  18 #include <linux/rbtree.h>
  19 #include <linux/ktime.h>
  20 #include <linux/init.h>
  21 #include <linux/list.h>
  22 #include <linux/wait.h>
  23
  24 /*
  25  * Mode arguments of xxx_hrtimer functions:
  26  */
  27 enum hrtimer_mode {
  28         HRTIMER_ABS,    /* Time value is absolute */
  29         HRTIMER_REL,    /* Time value is relative to now */
  30 };
  31
  32 enum hrtimer_restart {
  33         HRTIMER_NORESTART,
  34         HRTIMER_RESTART,
  35 };
  36
  37 #define HRTIMER_INACTIVE        ((void *)1UL)
  38
  39 struct hrtimer_base;
  40
  41 /**
  42  * struct hrtimer - the basic hrtimer structure
  43  * @node:       red black tree node for time ordered insertion
  44  * @expires:    the absolute expiry time in the hrtimers internal
  45  *              representation. The time is related to the clock on
  46  *              which the timer is based.
  47  * @function:   timer expiry callback function
  48  * @base:       pointer to the timer base (per cpu and per clock)
  49  *
  50  * The hrtimer structure must be initialized by init_hrtimer_#CLOCKTYPE()
  51  */
  52 struct hrtimer {
  53         struct rb_node          node;
  54         ktime_t                 expires;
  55         int                     (*function)(struct hrtimer *);
  56         struct hrtimer_base     *base;
  57 };
  58
  59 /**
  60  * struct hrtimer_sleeper - simple sleeper structure
  61  * @timer:      embedded timer structure
  62  * @task:       task to wake up
  63  *
  64  * task is set to NULL, when the timer expires.
  65  */
  66 struct hrtimer_sleeper {
  67         struct hrtimer timer;
  68         struct task_struct *task;
  69 };
  70
  71 /**
  72  * struct hrtimer_base - the timer base for a specific clock
  73  * @index:              clock type index for per_cpu support when moving a timer
  74  *                      to a base on another cpu.
  75  * @lock:               lock protecting the base and associated timers
  76  * @active:             red black tree root node for the active timers
  77  * @first:              pointer to the timer node which expires first
  78  * @resolution:         the resolution of the clock, in nanoseconds
  79  * @get_time:           function to retrieve the current time of the clock
  80  * @get_softirq_time:   function to retrieve the current time from the softirq
  81  * @curr_timer:         the timer which is executing a callback right now
  82  * @softirq_time:       the time when running the hrtimer queue in the softirq
  83  * @lock_key:           the lock_class_key for use with lockdep
  84  */
  85 struct hrtimer_base {
  86         clockid_t               index;
  87         spinlock_t              lock;
  88         struct rb_root          active;
  89         struct rb_node          *first;
  90         ktime_t                 resolution;
  91         ktime_t                 (*get_time)(void);
  92         ktime_t                 (*get_softirq_time)(void);
  93         struct hrtimer          *curr_timer;
  94         ktime_t                 softirq_time;
  95         struct lock_class_key lock_key;
  96 };
  97
  98 /*
  99  * clock_was_set() is a NOP for non- high-resolution systems. The
 100  * time-sorted order guarantees that a timer does not expire early and
 101  * is expired in the next softirq when the clock was advanced.
 102  */
 103 #define clock_was_set()         do { } while (0)
 104
 105 /* Exported timer functions: */
 106
 107 /* Initialize timers: */
 108 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 109                          enum hrtimer_mode mode);
 110
 111 /* Basic timer operations: */
 112 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
 113                          const enum hrtimer_mode mode);
 114 extern int hrtimer_cancel(struct hrtimer *timer);
 115 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 116
 117 #define hrtimer_restart(timer) hrtimer_start((timer), (timer)->expires, HRTIMER_ABS)
 118
 119 /* Query timers: */
 120 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
 121 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
 122
 123 #ifdef CONFIG_NO_IDLE_HZ
 124 extern ktime_t hrtimer_get_next_event(void);
 125 #endif
 126
 127 static inline int hrtimer_active(const struct hrtimer *timer)
 128 {
 129         return rb_parent(&timer->node) != &timer->node;
 130 }
 131
 132 /* Forward a hrtimer so it expires after now: */
 133 extern unsigned long
 134 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 135
 136 /* Precise sleep: */
 137 extern long hrtimer_nanosleep(struct timespec *rqtp,
 138                               struct timespec __user *rmtp,
 139                               const enum hrtimer_mode mode,
 140                               const clockid_t clockid);
 141 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
 142
 143 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
 144                                  struct task_struct *tsk);
 145
 146 /* Soft interrupt function to run the hrtimer queues: */
 147 extern void hrtimer_run_queues(void);
 148
 149 /* Bootup initialization: */
 150 extern void __init hrtimers_init(void);
 151
 152 #endif