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 /*
  38  * Timer states:
  39  */
  40 enum hrtimer_state {
  41         HRTIMER_INACTIVE,       /* Timer is inactive */
  42         HRTIMER_EXPIRED,                /* Timer is expired */
  43         HRTIMER_RUNNING,                /* Timer is running the callback function */
  44         HRTIMER_PENDING,                /* Timer is pending */
  45 };
  46
  47 struct hrtimer_base;
  48
  49 /**
  50  * struct hrtimer - the basic hrtimer structure
  51  *
  52  * @node:       red black tree node for time ordered insertion
  53  * @expires:    the absolute expiry time in the hrtimers internal
  54  *              representation. The time is related to the clock on
  55  *              which the timer is based.
  56  * @state:      state of the timer
  57  * @function:   timer expiry callback function
  58  * @data:       argument for the callback function
  59  * @base:       pointer to the timer base (per cpu and per clock)
  60  *
  61  * The hrtimer structure must be initialized by init_hrtimer_#CLOCKTYPE()
  62  */
  63 struct hrtimer {
  64         struct rb_node          node;
  65         ktime_t                 expires;
  66         enum hrtimer_state      state;
  67         int                     (*function)(void *);
  68         void                    *data;
  69         struct hrtimer_base     *base;
  70 };
  71
  72 /**
  73  * struct hrtimer_base - the timer base for a specific clock
  74  *
  75  * @index:      clock type index for per_cpu support when moving a timer
  76  *              to a base on another cpu.
  77  * @lock:       lock protecting the base and associated timers
  78  * @active:     red black tree root node for the active timers
  79  * @first:      pointer to the timer node which expires first
  80  * @resolution: the resolution of the clock, in nanoseconds
  81  * @get_time:   function to retrieve the current time of the clock
  82  * @curr_timer: the timer which is executing a callback right now
  83  */
  84 struct hrtimer_base {
  85         clockid_t               index;
  86         spinlock_t              lock;
  87         struct rb_root          active;
  88         struct rb_node          *first;
  89         ktime_t                 resolution;
  90         ktime_t                 (*get_time)(void);
  91         struct hrtimer          *curr_timer;
  92 };
  93
  94 /*
  95  * clock_was_set() is a NOP for non- high-resolution systems. The
  96  * time-sorted order guarantees that a timer does not expire early and
  97  * is expired in the next softirq when the clock was advanced.
  98  */
  99 #define clock_was_set()         do { } while (0)
 100
 101 /* Exported timer functions: */
 102
 103 /* Initialize timers: */
 104 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 105                          enum hrtimer_mode mode);
 106
 107 /* Basic timer operations: */
 108 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
 109                          const enum hrtimer_mode mode);
 110 extern int hrtimer_cancel(struct hrtimer *timer);
 111 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 112
 113 #define hrtimer_restart(timer) hrtimer_start((timer), (timer)->expires, HRTIMER_ABS)
 114
 115 /* Query timers: */
 116 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
 117 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
 118
 119 #ifdef CONFIG_NO_IDLE_HZ
 120 extern ktime_t hrtimer_get_next_event(void);
 121 #endif
 122
 123 static inline int hrtimer_active(const struct hrtimer *timer)
 124 {
 125         return timer->state == HRTIMER_PENDING;
 126 }
 127
 128 /* Forward a hrtimer so it expires after now: */
 129 extern unsigned long hrtimer_forward(struct hrtimer *timer, ktime_t interval);
 130
 131 /* Precise sleep: */
 132 extern long hrtimer_nanosleep(struct timespec *rqtp,
 133                               struct timespec __user *rmtp,
 134                               const enum hrtimer_mode mode,
 135                               const clockid_t clockid);
 136
 137 /* Soft interrupt function to run the hrtimer queues: */
 138 extern void hrtimer_run_queues(void);
 139
 140 /* Bootup initialization: */
 141 extern void __init hrtimers_init(void);
 142
 143 #endif