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 * hrtimer callback modes:
46 * HRTIMER_CB_SOFTIRQ: Callback must run in softirq context
47 * HRTIMER_CB_IRQSAFE: Callback may run in hardirq context
48 * HRTIMER_CB_IRQSAFE_NO_RESTART: Callback may run in hardirq context and
49 * does not restart the timer
50 * HRTIMER_CB_IRQSAFE_NO_SOFTIRQ: Callback must run in hardirq context
51 * Special mode for tick emultation
53 enum hrtimer_cb_mode {
56 HRTIMER_CB_IRQSAFE_NO_RESTART,
57 HRTIMER_CB_IRQSAFE_NO_SOFTIRQ,
61 * Values to track state of the timer
66 * 0x01 enqueued into rbtree
67 * 0x02 callback function running
68 * 0x04 callback pending (high resolution mode)
71 * 0x03 callback function running and enqueued
72 * (was requeued on another CPU)
73 * The "callback function running and enqueued" status is only possible on
74 * SMP. It happens for example when a posix timer expired and the callback
75 * queued a signal. Between dropping the lock which protects the posix timer
76 * and reacquiring the base lock of the hrtimer, another CPU can deliver the
77 * signal and rearm the timer. We have to preserve the callback running state,
78 * as otherwise the timer could be removed before the softirq code finishes the
79 * the handling of the timer.
81 * The HRTIMER_STATE_ENQUEUE bit is always or'ed to the current state to
82 * preserve the HRTIMER_STATE_CALLBACK bit in the above scenario.
84 * All state transitions are protected by cpu_base->lock.
86 #define HRTIMER_STATE_INACTIVE 0x00
87 #define HRTIMER_STATE_ENQUEUED 0x01
88 #define HRTIMER_STATE_CALLBACK 0x02
89 #define HRTIMER_STATE_PENDING 0x04
92 * struct hrtimer - the basic hrtimer structure
93 * @node: red black tree node for time ordered insertion
94 * @expires: the absolute expiry time in the hrtimers internal
95 * representation. The time is related to the clock on
96 * which the timer is based.
97 * @function: timer expiry callback function
98 * @base: pointer to the timer base (per cpu and per clock)
99 * @state: state information (See bit values above)
100 * @cb_mode: high resolution timer feature to select the callback execution
102 * @cb_entry: list head to enqueue an expired timer into the callback list
103 * @start_site: timer statistics field to store the site where the timer
105 * @start_comm: timer statistics field to store the name of the process which
107 * @start_pid: timer statistics field to store the pid of the task which
110 * The hrtimer structure must be initialized by hrtimer_init()
115 enum hrtimer_restart (*function)(struct hrtimer *);
116 struct hrtimer_clock_base *base;
118 enum hrtimer_cb_mode cb_mode;
119 struct list_head cb_entry;
120 #ifdef CONFIG_TIMER_STATS
128 * struct hrtimer_sleeper - simple sleeper structure
129 * @timer: embedded timer structure
130 * @task: task to wake up
132 * task is set to NULL, when the timer expires.
134 struct hrtimer_sleeper {
135 struct hrtimer timer;
136 struct task_struct *task;
140 * struct hrtimer_clock_base - the timer base for a specific clock
141 * @cpu_base: per cpu clock base
142 * @index: clock type index for per_cpu support when moving a
143 * timer to a base on another cpu.
144 * @active: red black tree root node for the active timers
145 * @first: pointer to the timer node which expires first
146 * @resolution: the resolution of the clock, in nanoseconds
147 * @get_time: function to retrieve the current time of the clock
148 * @get_softirq_time: function to retrieve the current time from the softirq
149 * @softirq_time: the time when running the hrtimer queue in the softirq
150 * @offset: offset of this clock to the monotonic base
151 * @reprogram: function to reprogram the timer event
153 struct hrtimer_clock_base {
154 struct hrtimer_cpu_base *cpu_base;
156 struct rb_root active;
157 struct rb_node *first;
159 ktime_t (*get_time)(void);
160 ktime_t (*get_softirq_time)(void);
161 ktime_t softirq_time;
162 #ifdef CONFIG_HIGH_RES_TIMERS
164 int (*reprogram)(struct hrtimer *t,
165 struct hrtimer_clock_base *b,
170 #define HRTIMER_MAX_CLOCK_BASES 2
173 * struct hrtimer_cpu_base - the per cpu clock bases
174 * @lock: lock protecting the base and associated clock bases
176 * @lock_key: the lock_class_key for use with lockdep
177 * @clock_base: array of clock bases for this cpu
178 * @curr_timer: the timer which is executing a callback right now
179 * @expires_next: absolute time of the next event which was scheduled
180 * via clock_set_next_event()
181 * @hres_active: State of high resolution mode
182 * @check_clocks: Indictator, when set evaluate time source and clock
183 * event devices whether high resolution mode can be
185 * @cb_pending: Expired timers are moved from the rbtree to this
186 * list in the timer interrupt. The list is processed
188 * @nr_events: Total number of timer interrupt events
190 struct hrtimer_cpu_base {
192 struct lock_class_key lock_key;
193 struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
194 struct list_head cb_pending;
195 #ifdef CONFIG_HIGH_RES_TIMERS
196 ktime_t expires_next;
198 unsigned long nr_events;
202 #ifdef CONFIG_HIGH_RES_TIMERS
203 struct clock_event_device;
205 extern void clock_was_set(void);
206 extern void hres_timers_resume(void);
207 extern void hrtimer_interrupt(struct clock_event_device *dev);
210 * In high resolution mode the time reference must be read accurate
212 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
214 return timer->base->get_time();
217 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
219 return timer->base->cpu_base->hres_active;
223 * The resolution of the clocks. The resolution value is returned in
224 * the clock_getres() system call to give application programmers an
225 * idea of the (in)accuracy of timers. Timer values are rounded up to
226 * this resolution values.
228 # define KTIME_HIGH_RES (ktime_t) { .tv64 = 1 }
229 # define KTIME_MONOTONIC_RES KTIME_HIGH_RES
233 # define KTIME_MONOTONIC_RES KTIME_LOW_RES
236 * clock_was_set() is a NOP for non- high-resolution systems. The
237 * time-sorted order guarantees that a timer does not expire early and
238 * is expired in the next softirq when the clock was advanced.
240 static inline void clock_was_set(void) { }
242 static inline void hres_timers_resume(void) { }
245 * In non high resolution mode the time reference is taken from
246 * the base softirq time variable.
248 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
250 return timer->base->softirq_time;
253 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
259 extern ktime_t ktime_get(void);
260 extern ktime_t ktime_get_real(void);
262 /* Exported timer functions: */
264 /* Initialize timers: */
265 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
266 enum hrtimer_mode mode);
268 /* Basic timer operations: */
269 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
270 const enum hrtimer_mode mode);
271 extern int hrtimer_cancel(struct hrtimer *timer);
272 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
274 static inline int hrtimer_restart(struct hrtimer *timer)
276 return hrtimer_start(timer, timer->expires, HRTIMER_MODE_ABS);
280 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
281 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
283 extern ktime_t hrtimer_get_next_event(void);
286 * A timer is active, when it is enqueued into the rbtree or the callback
287 * function is running.
289 static inline int hrtimer_active(const struct hrtimer *timer)
291 return timer->state != HRTIMER_STATE_INACTIVE;
295 * Helper function to check, whether the timer is on one of the queues
297 static inline int hrtimer_is_queued(struct hrtimer *timer)
299 return timer->state &
300 (HRTIMER_STATE_ENQUEUED | HRTIMER_STATE_PENDING);
303 /* Forward a hrtimer so it expires after now: */
305 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
307 /* Forward a hrtimer so it expires after the hrtimer's current now */
308 static inline unsigned long hrtimer_forward_now(struct hrtimer *timer,
311 return hrtimer_forward(timer, timer->base->get_time(), interval);
315 extern long hrtimer_nanosleep(struct timespec *rqtp,
316 struct timespec *rmtp,
317 const enum hrtimer_mode mode,
318 const clockid_t clockid);
319 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
321 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
322 struct task_struct *tsk);
324 /* Soft interrupt function to run the hrtimer queues: */
325 extern void hrtimer_run_queues(void);
326 extern void hrtimer_run_pending(void);
328 /* Bootup initialization: */
329 extern void __init hrtimers_init(void);
331 #if BITS_PER_LONG < 64
332 extern unsigned long ktime_divns(const ktime_t kt, s64 div);
333 #else /* BITS_PER_LONG < 64 */
334 # define ktime_divns(kt, div) (unsigned long)((kt).tv64 / (div))
337 /* Show pending timers: */
338 extern void sysrq_timer_list_show(void);
341 * Timer-statistics info:
343 #ifdef CONFIG_TIMER_STATS
345 extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
346 void *timerf, char *comm,
347 unsigned int timer_flag);
349 static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
351 timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
352 timer->function, timer->start_comm, 0);
355 extern void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer,
358 static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
360 __timer_stats_hrtimer_set_start_info(timer, __builtin_return_address(0));
363 static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
365 timer->start_site = NULL;
368 static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
372 static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
376 static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)