2 * include/linux/hrtimer.h
4 * hrtimers - High-resolution kernel timers
6 * Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
7 * Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
9 * data type definitions, declarations, prototypes
11 * Started by: Thomas Gleixner and Ingo Molnar
13 * For licencing details see kernel-base/COPYING
15 #ifndef _LINUX_HRTIMER_H
16 #define _LINUX_HRTIMER_H
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>
24 struct hrtimer_clock_base;
25 struct hrtimer_cpu_base;
28 * Mode arguments of xxx_hrtimer functions:
31 HRTIMER_MODE_ABS, /* Time value is absolute */
32 HRTIMER_MODE_REL, /* Time value is relative to now */
36 * Return values for the callback function
38 enum hrtimer_restart {
39 HRTIMER_NORESTART, /* Timer is not restarted */
40 HRTIMER_RESTART, /* Timer must be restarted */
44 * Bit values to track state of the timer
49 * 0x01 enqueued into rbtree
50 * 0x02 callback function running
51 * 0x03 callback function running and enqueued
52 * (was requeued on another CPU)
54 * The "callback function running and enqueued" status is only possible on
55 * SMP. It happens for example when a posix timer expired and the callback
56 * queued a signal. Between dropping the lock which protects the posix timer
57 * and reacquiring the base lock of the hrtimer, another CPU can deliver the
58 * signal and rearm the timer. We have to preserve the callback running state,
59 * as otherwise the timer could be removed before the softirq code finishes the
60 * the handling of the timer.
62 * The HRTIMER_STATE_ENQUEUE bit is always or'ed to the current state to
63 * preserve the HRTIMER_STATE_CALLBACK bit in the above scenario.
65 * All state transitions are protected by cpu_base->lock.
67 #define HRTIMER_STATE_INACTIVE 0x00
68 #define HRTIMER_STATE_ENQUEUED 0x01
69 #define HRTIMER_STATE_CALLBACK 0x02
72 * struct hrtimer - the basic hrtimer structure
73 * @node: red black tree node for time ordered insertion
74 * @expires: the absolute expiry time in the hrtimers internal
75 * representation. The time is related to the clock on
76 * which the timer is based.
77 * @function: timer expiry callback function
78 * @base: pointer to the timer base (per cpu and per clock)
79 * @state: state information (See bit values above)
81 * The hrtimer structure must be initialized by init_hrtimer_#CLOCKTYPE()
86 enum hrtimer_restart (*function)(struct hrtimer *);
87 struct hrtimer_clock_base *base;
92 * struct hrtimer_sleeper - simple sleeper structure
93 * @timer: embedded timer structure
94 * @task: task to wake up
96 * task is set to NULL, when the timer expires.
98 struct hrtimer_sleeper {
100 struct task_struct *task;
104 * struct hrtimer_base - the timer base for a specific clock
105 * @index: clock type index for per_cpu support when moving a
106 * timer to a base on another cpu.
107 * @active: red black tree root node for the active timers
108 * @first: pointer to the timer node which expires first
109 * @resolution: the resolution of the clock, in nanoseconds
110 * @get_time: function to retrieve the current time of the clock
111 * @get_softirq_time: function to retrieve the current time from the softirq
112 * @softirq_time: the time when running the hrtimer queue in the softirq
114 struct hrtimer_clock_base {
115 struct hrtimer_cpu_base *cpu_base;
117 struct rb_root active;
118 struct rb_node *first;
120 ktime_t (*get_time)(void);
121 ktime_t (*get_softirq_time)(void);
122 ktime_t softirq_time;
125 #define HRTIMER_MAX_CLOCK_BASES 2
128 * struct hrtimer_cpu_base - the per cpu clock bases
129 * @lock: lock protecting the base and associated clock bases
131 * @lock_key: the lock_class_key for use with lockdep
132 * @clock_base: array of clock bases for this cpu
133 * @curr_timer: the timer which is executing a callback right now
135 struct hrtimer_cpu_base {
137 struct lock_class_key lock_key;
138 struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
142 * clock_was_set() is a NOP for non- high-resolution systems. The
143 * time-sorted order guarantees that a timer does not expire early and
144 * is expired in the next softirq when the clock was advanced.
146 #define clock_was_set() do { } while (0)
147 extern ktime_t ktime_get(void);
148 extern ktime_t ktime_get_real(void);
150 /* Exported timer functions: */
152 /* Initialize timers: */
153 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
154 enum hrtimer_mode mode);
156 /* Basic timer operations: */
157 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
158 const enum hrtimer_mode mode);
159 extern int hrtimer_cancel(struct hrtimer *timer);
160 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
162 static inline int hrtimer_restart(struct hrtimer *timer)
164 return hrtimer_start(timer, timer->expires, HRTIMER_MODE_ABS);
168 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
169 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
171 #ifdef CONFIG_NO_IDLE_HZ
172 extern ktime_t hrtimer_get_next_event(void);
176 * A timer is active, when it is enqueued into the rbtree or the callback
177 * function is running.
179 static inline int hrtimer_active(const struct hrtimer *timer)
181 return timer->state != HRTIMER_STATE_INACTIVE;
184 /* Forward a hrtimer so it expires after now: */
186 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
189 extern long hrtimer_nanosleep(struct timespec *rqtp,
190 struct timespec __user *rmtp,
191 const enum hrtimer_mode mode,
192 const clockid_t clockid);
193 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
195 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
196 struct task_struct *tsk);
198 /* Soft interrupt function to run the hrtimer queues: */
199 extern void hrtimer_run_queues(void);
201 /* Bootup initialization: */
202 extern void __init hrtimers_init(void);
204 #if BITS_PER_LONG < 64
205 extern unsigned long ktime_divns(const ktime_t kt, s64 div);
206 #else /* BITS_PER_LONG < 64 */
207 # define ktime_divns(kt, div) (unsigned long)((kt).tv64 / (div))