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  *
  44  * @node:       red black tree node for time ordered insertion
  45  * @expires:    the absolute expiry time in the hrtimers internal
  46  *              representation. The time is related to the clock on
  47  *              which the timer is based.
  48  * @function:   timer expiry callback function
  49  * @base:       pointer to the timer base (per cpu and per clock)
  50  *
  51  * The hrtimer structure must be initialized by init_hrtimer_#CLOCKTYPE()
  52  */
  53 struct hrtimer {
  54         struct rb_node          node;
  55         ktime_t                 expires;
  56         int                     (*function)(struct hrtimer *);
  57         struct hrtimer_base     *base;
  58 };
  59
  60 /**
  61  * struct hrtimer_base - the timer base for a specific clock
  62  *
  63  * @index:              clock type index for per_cpu support when moving a timer
  64  *                      to a base on another cpu.
  65  * @lock:               lock protecting the base and associated timers
  66  * @active:             red black tree root node for the active timers
  67  * @first:              pointer to the timer node which expires first
  68  * @resolution:         the resolution of the clock, in nanoseconds
  69  * @get_time:           function to retrieve the current time of the clock
  70  * @get_sofirq_time:    function to retrieve the current time from the softirq
  71  * @curr_timer:         the timer which is executing a callback right now
  72  * @softirq_time:       the time when running the hrtimer queue in the softirq
  73  */
  74 struct hrtimer_base {
  75         clockid_t               index;
  76         spinlock_t              lock;
  77         struct rb_root          active;
  78         struct rb_node          *first;
  79         ktime_t                 resolution;
  80         ktime_t                 (*get_time)(void);
  81         ktime_t                 (*get_softirq_time)(void);
  82         struct hrtimer          *curr_timer;
  83         ktime_t                 softirq_time;
  84 };
  85
  86 /*
  87  * clock_was_set() is a NOP for non- high-resolution systems. The
  88  * time-sorted order guarantees that a timer does not expire early and
  89  * is expired in the next softirq when the clock was advanced.
  90  */
  91 #define clock_was_set()         do { } while (0)
  92
  93 /* Exported timer functions: */
  94
  95 /* Initialize timers: */
  96 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
  97                          enum hrtimer_mode mode);
  98
  99 /* Basic timer operations: */
 100 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
 101                          const enum hrtimer_mode mode);
 102 extern int hrtimer_cancel(struct hrtimer *timer);
 103 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 104
 105 #define hrtimer_restart(timer) hrtimer_start((timer), (timer)->expires, HRTIMER_ABS)
 106
 107 /* Query timers: */
 108 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
 109 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
 110
 111 #ifdef CONFIG_NO_IDLE_HZ
 112 extern ktime_t hrtimer_get_next_event(void);
 113 #endif
 114
 115 static inline int hrtimer_active(const struct hrtimer *timer)
 116 {
 117         return timer->node.rb_parent != HRTIMER_INACTIVE;
 118 }
 119
 120 /* Forward a hrtimer so it expires after now: */
 121 extern unsigned long
 122 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 123
 124 /* Precise sleep: */
 125 extern long hrtimer_nanosleep(struct timespec *rqtp,
 126                               struct timespec __user *rmtp,
 127                               const enum hrtimer_mode mode,
 128                               const clockid_t clockid);
 129
 130 /* Soft interrupt function to run the hrtimer queues: */
 131 extern void hrtimer_run_queues(void);
 132
 133 /* Bootup initialization: */
 134 extern void __init hrtimers_init(void);
 135
 136 #endif