Line data Source code
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 : #include <linux/percpu.h>
24 : #include <linux/timer.h>
25 :
26 :
27 : struct hrtimer_clock_base;
28 : struct hrtimer_cpu_base;
29 :
30 : /*
31 : * Mode arguments of xxx_hrtimer functions:
32 : */
33 : enum hrtimer_mode {
34 : HRTIMER_MODE_ABS = 0x0, /* Time value is absolute */
35 : HRTIMER_MODE_REL = 0x1, /* Time value is relative to now */
36 : HRTIMER_MODE_PINNED = 0x02, /* Timer is bound to CPU */
37 : HRTIMER_MODE_ABS_PINNED = 0x02,
38 : HRTIMER_MODE_REL_PINNED = 0x03,
39 : };
40 :
41 : /*
42 : * Return values for the callback function
43 : */
44 : enum hrtimer_restart {
45 : HRTIMER_NORESTART, /* Timer is not restarted */
46 : HRTIMER_RESTART, /* Timer must be restarted */
47 : };
48 :
49 : /*
50 : * Values to track state of the timer
51 : *
52 : * Possible states:
53 : *
54 : * 0x00 inactive
55 : * 0x01 enqueued into rbtree
56 : * 0x02 callback function running
57 : *
58 : * Special cases:
59 : * 0x03 callback function running and enqueued
60 : * (was requeued on another CPU)
61 : * 0x09 timer was migrated on CPU hotunplug
62 : * The "callback function running and enqueued" status is only possible on
63 : * SMP. It happens for example when a posix timer expired and the callback
64 : * queued a signal. Between dropping the lock which protects the posix timer
65 : * and reacquiring the base lock of the hrtimer, another CPU can deliver the
66 : * signal and rearm the timer. We have to preserve the callback running state,
67 : * as otherwise the timer could be removed before the softirq code finishes the
68 : * the handling of the timer.
69 : *
70 : * The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state to
71 : * preserve the HRTIMER_STATE_CALLBACK bit in the above scenario.
72 : *
73 : * All state transitions are protected by cpu_base->lock.
74 : */
75 : #define HRTIMER_STATE_INACTIVE 0x00
76 : #define HRTIMER_STATE_ENQUEUED 0x01
77 : #define HRTIMER_STATE_CALLBACK 0x02
78 : #define HRTIMER_STATE_MIGRATE 0x04
79 :
80 : /**
81 : * struct hrtimer - the basic hrtimer structure
82 : * @node: red black tree node for time ordered insertion
83 : * @_expires: the absolute expiry time in the hrtimers internal
84 : * representation. The time is related to the clock on
85 : * which the timer is based. Is setup by adding
86 : * slack to the _softexpires value. For non range timers
87 : * identical to _softexpires.
88 : * @_softexpires: the absolute earliest expiry time of the hrtimer.
89 : * The time which was given as expiry time when the timer
90 : * was armed.
91 : * @function: timer expiry callback function
92 : * @base: pointer to the timer base (per cpu and per clock)
93 : * @state: state information (See bit values above)
94 : * @start_site: timer statistics field to store the site where the timer
95 : * was started
96 : * @start_comm: timer statistics field to store the name of the process which
97 : * started the timer
98 : * @start_pid: timer statistics field to store the pid of the task which
99 : * started the timer
100 : *
101 : * The hrtimer structure must be initialized by hrtimer_init()
102 : */
103 : struct hrtimer {
104 : struct rb_node node;
105 : ktime_t _expires;
106 : ktime_t _softexpires;
107 : enum hrtimer_restart (*function)(struct hrtimer *);
108 : struct hrtimer_clock_base *base;
109 : unsigned long state;
110 : #ifdef CONFIG_TIMER_STATS
111 : int start_pid;
112 : void *start_site;
113 : char start_comm[16];
114 : #endif
115 : };
116 :
117 : /**
118 : * struct hrtimer_sleeper - simple sleeper structure
119 : * @timer: embedded timer structure
120 : * @task: task to wake up
121 : *
122 : * task is set to NULL, when the timer expires.
123 : */
124 : struct hrtimer_sleeper {
125 : struct hrtimer timer;
126 : struct task_struct *task;
127 : };
128 1 :
129 : /**
130 : * struct hrtimer_clock_base - the timer base for a specific clock
131 : * @cpu_base: per cpu clock base
132 : * @index: clock type index for per_cpu support when moving a
133 : * timer to a base on another cpu.
134 : * @active: red black tree root node for the active timers
135 : * @first: pointer to the timer node which expires first
136 : * @resolution: the resolution of the clock, in nanoseconds
137 : * @get_time: function to retrieve the current time of the clock
138 : * @softirq_time: the time when running the hrtimer queue in the softirq
139 : * @offset: offset of this clock to the monotonic base
140 : */
141 : struct hrtimer_clock_base {
142 : struct hrtimer_cpu_base *cpu_base;
143 : clockid_t index;
144 : struct rb_root active;
145 : struct rb_node *first;
146 : ktime_t resolution;
147 : ktime_t (*get_time)(void);
148 : ktime_t softirq_time;
149 : #ifdef CONFIG_HIGH_RES_TIMERS
150 : ktime_t offset;
151 : #endif
152 1 : };
153 :
154 : #define HRTIMER_MAX_CLOCK_BASES 2
155 :
156 : /*
157 : * struct hrtimer_cpu_base - the per cpu clock bases
158 : * @lock: lock protecting the base and associated clock bases
159 : * and timers
160 : * @clock_base: array of clock bases for this cpu
161 : * @curr_timer: the timer which is executing a callback right now
162 : * @expires_next: absolute time of the next event which was scheduled
163 : * via clock_set_next_event()
164 : * @hres_active: State of high resolution mode
165 : * @hang_detected: The last hrtimer interrupt detected a hang
166 : * @nr_events: Total number of hrtimer interrupt events
167 : * @nr_retries: Total number of hrtimer interrupt retries
168 : * @nr_hangs: Total number of hrtimer interrupt hangs
169 : * @max_hang_time: Maximum time spent in hrtimer_interrupt
170 : */
171 : struct hrtimer_cpu_base {
172 : raw_spinlock_t lock;
173 : struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
174 : #ifdef CONFIG_HIGH_RES_TIMERS
175 : ktime_t expires_next;
176 : int hres_active;
177 : int hang_detected;
178 : unsigned long nr_events;
179 : unsigned long nr_retries;
180 : unsigned long nr_hangs;
181 : ktime_t max_hang_time;
182 : #endif
183 : };
184 :
185 : static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
186 : {
187 : timer->_expires = time;
188 : timer->_softexpires = time;
189 : }
190 :
191 : static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
192 : {
193 : timer->_softexpires = time;
194 : timer->_expires = ktime_add_safe(time, delta);
195 : }
196 :
197 : static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
198 : {
199 : timer->_softexpires = time;
200 : timer->_expires = ktime_add_safe(time, ns_to_ktime(delta));
201 : }
202 :
203 : static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
204 : {
205 : timer->_expires.tv64 = tv64;
206 : timer->_softexpires.tv64 = tv64;
207 : }
208 :
209 : static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
210 : {
211 : timer->_expires = ktime_add_safe(timer->_expires, time);
212 : timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
213 : }
214 :
215 : static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
216 : {
217 : timer->_expires = ktime_add_ns(timer->_expires, ns);
218 : timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
219 : }
220 :
221 : static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
222 : {
223 : return timer->_expires;
224 : }
225 :
226 : static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
227 : {
228 : return timer->_softexpires;
229 : }
230 :
231 : static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
232 : {
233 : return timer->_expires.tv64;
234 : }
235 : static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
236 : {
237 : return timer->_softexpires.tv64;
238 : }
239 :
240 : static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
241 : {
242 : return ktime_to_ns(timer->_expires);
243 : }
244 :
245 : static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
246 : {
247 : return ktime_sub(timer->_expires, timer->base->get_time());
248 : }
249 :
250 : #ifdef CONFIG_HIGH_RES_TIMERS
251 : struct clock_event_device;
252 :
253 : extern void clock_was_set(void);
254 : extern void hres_timers_resume(void);
255 : extern void hrtimer_interrupt(struct clock_event_device *dev);
256 :
257 : /*
258 : * In high resolution mode the time reference must be read accurate
259 : */
260 : static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
261 : {
262 : return timer->base->get_time();
263 : }
264 :
265 : static inline int hrtimer_is_hres_active(struct hrtimer *timer)
266 : {
267 : return timer->base->cpu_base->hres_active;
268 : }
269 :
270 : extern void hrtimer_peek_ahead_timers(void);
271 :
272 : /*
273 : * The resolution of the clocks. The resolution value is returned in
274 : * the clock_getres() system call to give application programmers an
275 : * idea of the (in)accuracy of timers. Timer values are rounded up to
276 : * this resolution values.
277 : */
278 : # define HIGH_RES_NSEC 1
279 : # define KTIME_HIGH_RES (ktime_t) { .tv64 = HIGH_RES_NSEC }
280 : # define MONOTONIC_RES_NSEC HIGH_RES_NSEC
281 : # define KTIME_MONOTONIC_RES KTIME_HIGH_RES
282 :
283 : #else
284 :
285 : # define MONOTONIC_RES_NSEC LOW_RES_NSEC
286 : # define KTIME_MONOTONIC_RES KTIME_LOW_RES
287 :
288 : /*
289 : * clock_was_set() is a NOP for non- high-resolution systems. The
290 : * time-sorted order guarantees that a timer does not expire early and
291 : * is expired in the next softirq when the clock was advanced.
292 : */
293 : static inline void clock_was_set(void) { }
294 : static inline void hrtimer_peek_ahead_timers(void) { }
295 :
296 : static inline void hres_timers_resume(void) { }
297 :
298 : /*
299 : * In non high resolution mode the time reference is taken from
300 : * the base softirq time variable.
301 : */
302 : static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
303 : {
304 : return timer->base->softirq_time;
305 : }
306 :
307 : static inline int hrtimer_is_hres_active(struct hrtimer *timer)
308 : {
309 : return 0;
310 : }
311 : #endif
312 :
313 : extern ktime_t ktime_get(void);
314 : extern ktime_t ktime_get_real(void);
315 :
316 :
317 : DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
318 :
319 :
320 : /* Exported timer functions: */
321 :
322 : /* Initialize timers: */
323 : extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
324 : enum hrtimer_mode mode);
325 :
326 : #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
327 : extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
328 : enum hrtimer_mode mode);
329 :
330 : extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
331 : #else
332 : static inline void hrtimer_init_on_stack(struct hrtimer *timer,
333 : clockid_t which_clock,
334 : enum hrtimer_mode mode)
335 : {
336 : hrtimer_init(timer, which_clock, mode);
337 : }
338 : static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
339 : #endif
340 :
341 : /* Basic timer operations: */
342 : extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
343 : const enum hrtimer_mode mode);
344 : extern int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
345 : unsigned long range_ns, const enum hrtimer_mode mode);
346 : extern int
347 : __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
348 : unsigned long delta_ns,
349 : const enum hrtimer_mode mode, int wakeup);
350 :
351 : extern int hrtimer_cancel(struct hrtimer *timer);
352 : extern int hrtimer_try_to_cancel(struct hrtimer *timer);
353 :
354 : static inline int hrtimer_start_expires(struct hrtimer *timer,
355 : enum hrtimer_mode mode)
356 : {
357 : unsigned long delta;
358 : ktime_t soft, hard;
359 : soft = hrtimer_get_softexpires(timer);
360 : hard = hrtimer_get_expires(timer);
361 : delta = ktime_to_ns(ktime_sub(hard, soft));
362 : return hrtimer_start_range_ns(timer, soft, delta, mode);
363 : }
364 :
365 : static inline int hrtimer_restart(struct hrtimer *timer)
366 : {
367 : return hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
368 : }
369 :
370 : /* Query timers: */
371 : extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
372 : extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
373 :
374 : extern ktime_t hrtimer_get_next_event(void);
375 :
376 : /*
377 : * A timer is active, when it is enqueued into the rbtree or the callback
378 : * function is running.
379 : */
380 : static inline int hrtimer_active(const struct hrtimer *timer)
381 : {
382 : return timer->state != HRTIMER_STATE_INACTIVE;
383 : }
384 :
385 : /*
386 : * Helper function to check, whether the timer is on one of the queues
387 : */
388 : static inline int hrtimer_is_queued(struct hrtimer *timer)
389 : {
390 : return timer->state & HRTIMER_STATE_ENQUEUED;
391 : }
392 :
393 : /*
394 : * Helper function to check, whether the timer is running the callback
395 : * function
396 : */
397 : static inline int hrtimer_callback_running(struct hrtimer *timer)
398 : {
399 : return timer->state & HRTIMER_STATE_CALLBACK;
400 : }
401 :
402 : /* Forward a hrtimer so it expires after now: */
403 : extern u64
404 : hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
405 :
406 : /* Forward a hrtimer so it expires after the hrtimer's current now */
407 : static inline u64 hrtimer_forward_now(struct hrtimer *timer,
408 : ktime_t interval)
409 : {
410 : return hrtimer_forward(timer, timer->base->get_time(), interval);
411 : }
412 :
413 : /* Precise sleep: */
414 : extern long hrtimer_nanosleep(struct timespec *rqtp,
415 : struct timespec __user *rmtp,
416 : const enum hrtimer_mode mode,
417 : const clockid_t clockid);
418 : extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
419 :
420 : extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
421 : struct task_struct *tsk);
422 :
423 : extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
424 : const enum hrtimer_mode mode);
425 : extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
426 :
427 : /* Soft interrupt function to run the hrtimer queues: */
428 : extern void hrtimer_run_queues(void);
429 : extern void hrtimer_run_pending(void);
430 :
431 : /* Bootup initialization: */
432 : extern void __init hrtimers_init(void);
433 :
434 : #if BITS_PER_LONG < 64
435 : extern u64 ktime_divns(const ktime_t kt, s64 div);
436 : #else /* BITS_PER_LONG < 64 */
437 : # define ktime_divns(kt, div) (u64)((kt).tv64 / (div))
438 : #endif
439 :
440 : /* Show pending timers: */
441 : extern void sysrq_timer_list_show(void);
442 1 :
443 : #endif
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