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_PENDING,                /* Timer is pending */
  44 };
  45
  46 struct hrtimer_base;
  47
  48 /**
  49  * struct hrtimer - the basic hrtimer structure
  50  *
  51  * @node:       red black tree node for time ordered insertion
  52  * @list:       list head for easier access to the time ordered list,
  53  *              without walking the red black tree.
  54  * @expires:    the absolute expiry time in the hrtimers internal
  55  *              representation. The time is related to the clock on
  56  *              which the timer is based.
  57  * @state:      state of the timer
  58  * @function:   timer expiry callback function
  59  * @data:       argument for the callback function
  60  * @base:       pointer to the timer base (per cpu and per clock)
  61  *
  62  * The hrtimer structure must be initialized by init_hrtimer_#CLOCKTYPE()
  63  */
  64 struct hrtimer {
  65         struct rb_node          node;
  66         struct list_head        list;
  67         ktime_t                 expires;
  68         enum hrtimer_state      state;
  69         int                     (*function)(void *);
  70         void                    *data;
  71         struct hrtimer_base     *base;
  72 };
  73
  74 /**
  75  * struct hrtimer_base - the timer base for a specific clock
  76  *
  77  * @index:      clock type index for per_cpu support when moving a timer
  78  *              to a base on another cpu.
  79  * @lock:       lock protecting the base and associated timers
  80  * @active:     red black tree root node for the active timers
  81  * @pending:    list of pending timers for simple time ordered access
  82  * @resolution: the resolution of the clock, in nanoseconds
  83  * @get_time:   function to retrieve the current time of the clock
  84  * @curr_timer: the timer which is executing a callback right now
  85  */
  86 struct hrtimer_base {
  87         clockid_t               index;
  88         spinlock_t              lock;
  89         struct rb_root          active;
  90         struct list_head        pending;
  91         unsigned long           resolution;
  92         ktime_t                 (*get_time)(void);
  93         struct hrtimer          *curr_timer;
  94 };
  95
  96 /* Exported timer functions: */
  97
  98 /* Initialize timers: */
  99 extern void hrtimer_init(struct hrtimer *timer, const clockid_t which_clock);
 100 extern void hrtimer_rebase(struct hrtimer *timer, const clockid_t which_clock);
 101
 102
 103 /* Basic timer operations: */
 104 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
 105                          const enum hrtimer_mode mode);
 106 extern int hrtimer_cancel(struct hrtimer *timer);
 107 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 108
 109 #define hrtimer_restart(timer) hrtimer_start((timer), (timer)->expires, HRTIMER_ABS)
 110
 111 /* Query timers: */
 112 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
 113 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
 114
 115 static inline int hrtimer_active(const struct hrtimer *timer)
 116 {
 117         return timer->state == HRTIMER_PENDING;
 118 }
 119
 120 /* Forward a hrtimer so it expires after now: */
 121 extern unsigned long hrtimer_forward(struct hrtimer *timer,
 122                                      const ktime_t interval);
 123
 124 /* Soft interrupt function to run the hrtimer queues: */
 125 extern void hrtimer_run_queues(void);
 126
 127 /* Bootup initialization: */
 128 extern void __init hrtimers_init(void);
 129
 130 #endif