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_sleeper - simple sleeper structure
  62  *
  63  * @timer:      embedded timer structure
  64  * @task:       task to wake up
  65  *
  66  * task is set to NULL, when the timer expires.
  67  */
  68 struct hrtimer_sleeper {
  69         struct hrtimer timer;
  70         struct task_struct *task;
  71 };
  72
  73 /**
  74  * struct hrtimer_base - the timer base for a specific clock
  75  *
  76  * @index:              clock type index for per_cpu support when moving a timer
  77  *                      to a base on another cpu.
  78  * @lock:               lock protecting the base and associated timers
  79  * @active:             red black tree root node for the active timers
  80  * @first:              pointer to the timer node which expires first
  81  * @resolution:         the resolution of the clock, in nanoseconds
  82  * @get_time:           function to retrieve the current time of the clock
  83  * @get_softirq_time:   function to retrieve the current time from the softirq
  84  * @curr_timer:         the timer which is executing a callback right now
  85  * @softirq_time:       the time when running the hrtimer queue in the softirq
  86  */
  87 struct hrtimer_base {
  88         clockid_t               index;
  89         spinlock_t              lock;
  90         struct rb_root          active;
  91         struct rb_node          *first;
  92         ktime_t                 resolution;
  93         ktime_t                 (*get_time)(void);
  94         ktime_t                 (*get_softirq_time)(void);
  95         struct hrtimer          *curr_timer;
  96         ktime_t                 softirq_time;
  97 };
  98
  99 /*
 100  * clock_was_set() is a NOP for non- high-resolution systems. The
 101  * time-sorted order guarantees that a timer does not expire early and
 102  * is expired in the next softirq when the clock was advanced.
 103  */
 104 #define clock_was_set()         do { } while (0)
 105
 106 /* Exported timer functions: */
 107
 108 /* Initialize timers: */
 109 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 110                          enum hrtimer_mode mode);
 111
 112 /* Basic timer operations: */
 113 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
 114                          const enum hrtimer_mode mode);
 115 extern int hrtimer_cancel(struct hrtimer *timer);
 116 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 117
 118 #define hrtimer_restart(timer) hrtimer_start((timer), (timer)->expires, HRTIMER_ABS)
 119
 120 /* Query timers: */
 121 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
 122 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
 123
 124 #ifdef CONFIG_NO_IDLE_HZ
 125 extern ktime_t hrtimer_get_next_event(void);
 126 #endif
 127
 128 static inline int hrtimer_active(const struct hrtimer *timer)
 129 {
 130         return timer->node.rb_parent != HRTIMER_INACTIVE;
 131 }
 132
 133 /* Forward a hrtimer so it expires after now: */
 134 extern unsigned long
 135 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 136
 137 /* Precise sleep: */
 138 extern long hrtimer_nanosleep(struct timespec *rqtp,
 139                               struct timespec __user *rmtp,
 140                               const enum hrtimer_mode mode,
 141                               const clockid_t clockid);
 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