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 softirq 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 #ifdef CONFIG_HIGH_RES_TIMERS
119 enum hrtimer_cb_mode cb_mode;
120 struct list_head cb_entry;
125 * struct hrtimer_sleeper - simple sleeper structure
126 * @timer: embedded timer structure
127 * @task: task to wake up
129 * task is set to NULL, when the timer expires.
131 struct hrtimer_sleeper {
132 struct hrtimer timer;
133 struct task_struct *task;
137 * struct hrtimer_base - the timer base for a specific clock
138 * @index: clock type index for per_cpu support when moving a
139 * timer to a base on another cpu.
140 * @active: red black tree root node for the active timers
141 * @first: pointer to the timer node which expires first
142 * @resolution: the resolution of the clock, in nanoseconds
143 * @get_time: function to retrieve the current time of the clock
144 * @get_softirq_time: function to retrieve the current time from the softirq
145 * @softirq_time: the time when running the hrtimer queue in the softirq
146 * @cb_pending: list of timers where the callback is pending
147 * @offset: offset of this clock to the monotonic base
148 * @reprogram: function to reprogram the timer event
150 struct hrtimer_clock_base {
151 struct hrtimer_cpu_base *cpu_base;
153 struct rb_root active;
154 struct rb_node *first;
156 ktime_t (*get_time)(void);
157 ktime_t (*get_softirq_time)(void);
158 ktime_t softirq_time;
159 #ifdef CONFIG_HIGH_RES_TIMERS
161 int (*reprogram)(struct hrtimer *t,
162 struct hrtimer_clock_base *b,
167 #define HRTIMER_MAX_CLOCK_BASES 2
170 * struct hrtimer_cpu_base - the per cpu clock bases
171 * @lock: lock protecting the base and associated clock bases
173 * @lock_key: the lock_class_key for use with lockdep
174 * @clock_base: array of clock bases for this cpu
175 * @curr_timer: the timer which is executing a callback right now
176 * @expires_next: absolute time of the next event which was scheduled
177 * via clock_set_next_event()
178 * @hres_active: State of high resolution mode
179 * @check_clocks: Indictator, when set evaluate time source and clock
180 * event devices whether high resolution mode can be
182 * @cb_pending: Expired timers are moved from the rbtree to this
183 * list in the timer interrupt. The list is processed
185 * @nr_events: Total number of timer interrupt events
187 struct hrtimer_cpu_base {
189 struct lock_class_key lock_key;
190 struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
191 #ifdef CONFIG_HIGH_RES_TIMERS
192 ktime_t expires_next;
194 struct list_head cb_pending;
195 unsigned long nr_events;
199 #ifdef CONFIG_HIGH_RES_TIMERS
200 struct clock_event_device;
202 extern void clock_was_set(void);
203 extern void hrtimer_interrupt(struct clock_event_device *dev);
206 * In high resolution mode the time reference must be read accurate
208 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
210 return timer->base->get_time();
214 * The resolution of the clocks. The resolution value is returned in
215 * the clock_getres() system call to give application programmers an
216 * idea of the (in)accuracy of timers. Timer values are rounded up to
217 * this resolution values.
219 # define KTIME_HIGH_RES (ktime_t) { .tv64 = 1 }
220 # define KTIME_MONOTONIC_RES KTIME_HIGH_RES
224 # define KTIME_MONOTONIC_RES KTIME_LOW_RES
227 * clock_was_set() is a NOP for non- high-resolution systems. The
228 * time-sorted order guarantees that a timer does not expire early and
229 * is expired in the next softirq when the clock was advanced.
231 static inline void clock_was_set(void) { }
234 * In non high resolution mode the time reference is taken from
235 * the base softirq time variable.
237 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
239 return timer->base->softirq_time;
244 extern ktime_t ktime_get(void);
245 extern ktime_t ktime_get_real(void);
247 /* Exported timer functions: */
249 /* Initialize timers: */
250 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
251 enum hrtimer_mode mode);
253 /* Basic timer operations: */
254 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
255 const enum hrtimer_mode mode);
256 extern int hrtimer_cancel(struct hrtimer *timer);
257 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
259 static inline int hrtimer_restart(struct hrtimer *timer)
261 return hrtimer_start(timer, timer->expires, HRTIMER_MODE_ABS);
265 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
266 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
268 extern ktime_t hrtimer_get_next_event(void);
271 * A timer is active, when it is enqueued into the rbtree or the callback
272 * function is running.
274 static inline int hrtimer_active(const struct hrtimer *timer)
276 return timer->state != HRTIMER_STATE_INACTIVE;
280 * Helper function to check, whether the timer is on one of the queues
282 static inline int hrtimer_is_queued(struct hrtimer *timer)
284 return timer->state &
285 (HRTIMER_STATE_ENQUEUED | HRTIMER_STATE_PENDING);
288 /* Forward a hrtimer so it expires after now: */
290 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
293 extern long hrtimer_nanosleep(struct timespec *rqtp,
294 struct timespec __user *rmtp,
295 const enum hrtimer_mode mode,
296 const clockid_t clockid);
297 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
299 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
300 struct task_struct *tsk);
302 /* Soft interrupt function to run the hrtimer queues: */
303 extern void hrtimer_run_queues(void);
305 /* Bootup initialization: */
306 extern void __init hrtimers_init(void);
308 #if BITS_PER_LONG < 64
309 extern unsigned long ktime_divns(const ktime_t kt, s64 div);
310 #else /* BITS_PER_LONG < 64 */
311 # define ktime_divns(kt, div) (unsigned long)((kt).tv64 / (div))