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_MODE_ABS,       /* Time value is absolute */
  29         HRTIMER_MODE_REL,       /* Time value is relative to now */
  30 };
  31
  32 /*
  33  * Return values for the callback function
  34  */
  35 enum hrtimer_restart {
  36         HRTIMER_NORESTART,      /* Timer is not restarted */
  37         HRTIMER_RESTART,        /* Timer must be restarted */
  38 };
  39
  40 struct hrtimer_base;
  41
  42 /**
  43  * struct hrtimer - the basic hrtimer structure
  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         enum hrtimer_restart    (*function)(struct hrtimer *);
  57         struct hrtimer_base     *base;
  58 };
  59
  60 /**
  61  * struct hrtimer_sleeper - simple sleeper structure
  62  * @timer:      embedded timer structure
  63  * @task:       task to wake up
  64  *
  65  * task is set to NULL, when the timer expires.
  66  */
  67 struct hrtimer_sleeper {
  68         struct hrtimer timer;
  69         struct task_struct *task;
  70 };
  71
  72 /**
  73  * struct hrtimer_base - the timer base for a specific clock
  74  * @index:              clock type index for per_cpu support when moving a timer
  75  *                      to a base on another cpu.
  76  * @lock:               lock protecting the base and associated timers
  77  * @active:             red black tree root node for the active timers
  78  * @first:              pointer to the timer node which expires first
  79  * @resolution:         the resolution of the clock, in nanoseconds
  80  * @get_time:           function to retrieve the current time of the clock
  81  * @get_softirq_time:   function to retrieve the current time from the softirq
  82  * @curr_timer:         the timer which is executing a callback right now
  83  * @softirq_time:       the time when running the hrtimer queue in the softirq
  84  * @lock_key:           the lock_class_key for use with lockdep
  85  */
  86 struct hrtimer_base {
  87         clockid_t               index;
  88         spinlock_t              lock;
  89         struct rb_root          active;
  90         struct rb_node          *first;
  91         ktime_t                 resolution;
  92         ktime_t                 (*get_time)(void);
  93         ktime_t                 (*get_softirq_time)(void);
  94         struct hrtimer          *curr_timer;
  95         ktime_t                 softirq_time;
  96         struct lock_class_key lock_key;
  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 static inline int hrtimer_restart(struct hrtimer *timer)
 119 {
 120         return hrtimer_start(timer, timer->expires, HRTIMER_MODE_ABS);
 121 }
 122
 123 /* Query timers: */
 124 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
 125 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
 126
 127 #ifdef CONFIG_NO_IDLE_HZ
 128 extern ktime_t hrtimer_get_next_event(void);
 129 #endif
 130
 131 static inline int hrtimer_active(const struct hrtimer *timer)
 132 {
 133         return rb_parent(&timer->node) != &timer->node;
 134 }
 135
 136 /* Forward a hrtimer so it expires after now: */
 137 extern unsigned long
 138 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 139
 140 /* Precise sleep: */
 141 extern long hrtimer_nanosleep(struct timespec *rqtp,
 142                               struct timespec __user *rmtp,
 143                               const enum hrtimer_mode mode,
 144                               const clockid_t clockid);
 145 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
 146
 147 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
 148                                  struct task_struct *tsk);
 149
 150 /* Soft interrupt function to run the hrtimer queues: */
 151 extern void hrtimer_run_queues(void);
 152
 153 /* Resume notification */
 154 void hrtimer_notify_resume(void);
 155
 156 /* Bootup initialization: */
 157 extern void __init hrtimers_init(void);
 158
 159 #endif