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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 #include <linux/timerqueue.h>
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: timerqueue node, which also manages node.expires,
83 * 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 timerqueue_node node;
105 ktime_t _softexpires;
106 enum hrtimer_restart (*function)(struct hrtimer *);
107 struct hrtimer_clock_base *base;
108 unsigned long state;
109 #ifdef CONFIG_TIMER_STATS
110 int start_pid;
111 void *start_site;
112 char start_comm[16];
113 #endif
114 };
115
116 /**
117 * struct hrtimer_sleeper - simple sleeper structure
118 * @timer: embedded timer structure
119 * @task: task to wake up
120 *
121 * task is set to NULL, when the timer expires.
122 */
123 struct hrtimer_sleeper {
124 struct hrtimer timer;
125 struct task_struct *task;
126 };
127
128 /**
129 * struct hrtimer_clock_base - the timer base for a specific clock
130 * @cpu_base: per cpu clock base
131 * @index: clock type index for per_cpu support when moving a
132 * timer to a base on another cpu.
133 * @active: red black tree root node for the active timers
134 * @resolution: the resolution of the clock, in nanoseconds
135 * @get_time: function to retrieve the current time of the clock
136 * @softirq_time: the time when running the hrtimer queue in the softirq
137 * @offset: offset of this clock to the monotonic base
138 */
139 struct hrtimer_clock_base {
140 struct hrtimer_cpu_base *cpu_base;
141 clockid_t index;
142 struct timerqueue_head active;
143 ktime_t resolution;
144 ktime_t (*get_time)(void);
145 ktime_t softirq_time;
146 #ifdef CONFIG_HIGH_RES_TIMERS
147 ktime_t offset;
148 #endif
149 };
150
151 #define HRTIMER_MAX_CLOCK_BASES 2
152
153 /*
154 * struct hrtimer_cpu_base - the per cpu clock bases
155 * @lock: lock protecting the base and associated clock bases
156 * and timers
157 * @clock_base: array of clock bases for this cpu
158 * @expires_next: absolute time of the next event which was scheduled
159 * via clock_set_next_event()
160 * @hres_active: State of high resolution mode
161 * @hang_detected: The last hrtimer interrupt detected a hang
162 * @nr_events: Total number of hrtimer interrupt events
163 * @nr_retries: Total number of hrtimer interrupt retries
164 * @nr_hangs: Total number of hrtimer interrupt hangs
165 * @max_hang_time: Maximum time spent in hrtimer_interrupt
166 */
167 struct hrtimer_cpu_base {
168 raw_spinlock_t lock;
169 struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
170 #ifdef CONFIG_HIGH_RES_TIMERS
171 ktime_t expires_next;
172 int hres_active;
173 int hang_detected;
174 unsigned long nr_events;
175 unsigned long nr_retries;
176 unsigned long nr_hangs;
177 ktime_t max_hang_time;
178 #endif
179 };
180
181 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
182 {
183 timer->node.expires = time;
184 timer->_softexpires = time;
185 }
186
187 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
188 {
189 timer->_softexpires = time;
190 timer->node.expires = ktime_add_safe(time, delta);
191 }
192
193 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
194 {
195 timer->_softexpires = time;
196 timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
197 }
198
199 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
200 {
201 timer->node.expires.tv64 = tv64;
202 timer->_softexpires.tv64 = tv64;
203 }
204
205 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
206 {
207 timer->node.expires = ktime_add_safe(timer->node.expires, time);
208 timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
209 }
210
211 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
212 {
213 timer->node.expires = ktime_add_ns(timer->node.expires, ns);
214 timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
215 }
216
217 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
218 {
219 return timer->node.expires;
220 }
221
222 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
223 {
224 return timer->_softexpires;
225 }
226
227 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
228 {
229 return timer->node.expires.tv64;
230 }
231 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
232 {
233 return timer->_softexpires.tv64;
234 }
235
236 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
237 {
238 return ktime_to_ns(timer->node.expires);
239 }
240
241 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
242 {
243 return ktime_sub(timer->node.expires, timer->base->get_time());
244 }
245
246 #ifdef CONFIG_HIGH_RES_TIMERS
247 struct clock_event_device;
248
249 extern void clock_was_set(void);
250 extern void hres_timers_resume(void);
251 extern void hrtimer_interrupt(struct clock_event_device *dev);
252
253 /*
254 * In high resolution mode the time reference must be read accurate
255 */
256 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
257 {
258 return timer->base->get_time();
259 }
260
261 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
262 {
263 return timer->base->cpu_base->hres_active;
264 }
265
266 extern void hrtimer_peek_ahead_timers(void);
267
268 /*
269 * The resolution of the clocks. The resolution value is returned in
270 * the clock_getres() system call to give application programmers an
271 * idea of the (in)accuracy of timers. Timer values are rounded up to
272 * this resolution values.
273 */
274 # define HIGH_RES_NSEC 1
275 # define KTIME_HIGH_RES (ktime_t) { .tv64 = HIGH_RES_NSEC }
276 # define MONOTONIC_RES_NSEC HIGH_RES_NSEC
277 # define KTIME_MONOTONIC_RES KTIME_HIGH_RES
278
279 #else
280
281 # define MONOTONIC_RES_NSEC LOW_RES_NSEC
282 # define KTIME_MONOTONIC_RES KTIME_LOW_RES
283
284 /*
285 * clock_was_set() is a NOP for non- high-resolution systems. The
286 * time-sorted order guarantees that a timer does not expire early and
287 * is expired in the next softirq when the clock was advanced.
288 */
289 static inline void clock_was_set(void) { }
290 static inline void hrtimer_peek_ahead_timers(void) { }
291
292 static inline void hres_timers_resume(void) { }
293
294 /*
295 * In non high resolution mode the time reference is taken from
296 * the base softirq time variable.
297 */
298 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
299 {
300 return timer->base->softirq_time;
301 }
302
303 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
304 {
305 return 0;
306 }
307 #endif
308
309 extern ktime_t ktime_get(void);
310 extern ktime_t ktime_get_real(void);
311
312
313 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
314
315
316 /* Exported timer functions: */
317
318 /* Initialize timers: */
319 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
320 enum hrtimer_mode mode);
321
322 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
323 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
324 enum hrtimer_mode mode);
325
326 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
327 #else
328 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
329 clockid_t which_clock,
330 enum hrtimer_mode mode)
331 {
332 hrtimer_init(timer, which_clock, mode);
333 }
334 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
335 #endif
336
337 /* Basic timer operations: */
338 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
339 const enum hrtimer_mode mode);
340 extern int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
341 unsigned long range_ns, const enum hrtimer_mode mode);
342 extern int
343 __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
344 unsigned long delta_ns,
345 const enum hrtimer_mode mode, int wakeup);
346
347 extern int hrtimer_cancel(struct hrtimer *timer);
348 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
349
350 static inline int hrtimer_start_expires(struct hrtimer *timer,
351 enum hrtimer_mode mode)
352 {
353 unsigned long delta;
354 ktime_t soft, hard;
355 soft = hrtimer_get_softexpires(timer);
356 hard = hrtimer_get_expires(timer);
357 delta = ktime_to_ns(ktime_sub(hard, soft));
358 return hrtimer_start_range_ns(timer, soft, delta, mode);
359 }
360
361 static inline int hrtimer_restart(struct hrtimer *timer)
362 {
363 return hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
364 }
365
366 /* Query timers: */
367 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
368 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
369
370 extern ktime_t hrtimer_get_next_event(void);
371
372 /*
373 * A timer is active, when it is enqueued into the rbtree or the callback
374 * function is running.
375 */
376 static inline int hrtimer_active(const struct hrtimer *timer)
377 {
378 return timer->state != HRTIMER_STATE_INACTIVE;
379 }
380
381 /*
382 * Helper function to check, whether the timer is on one of the queues
383 */
384 static inline int hrtimer_is_queued(struct hrtimer *timer)
385 {
386 return timer->state & HRTIMER_STATE_ENQUEUED;
387 }
388
389 /*
390 * Helper function to check, whether the timer is running the callback
391 * function
392 */
393 static inline int hrtimer_callback_running(struct hrtimer *timer)
394 {
395 return timer->state & HRTIMER_STATE_CALLBACK;
396 }
397
398 /* Forward a hrtimer so it expires after now: */
399 extern u64
400 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
401
402 /* Forward a hrtimer so it expires after the hrtimer's current now */
403 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
404 ktime_t interval)
405 {
406 return hrtimer_forward(timer, timer->base->get_time(), interval);
407 }
408
409 /* Precise sleep: */
410 extern long hrtimer_nanosleep(struct timespec *rqtp,
411 struct timespec __user *rmtp,
412 const enum hrtimer_mode mode,
413 const clockid_t clockid);
414 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
415
416 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
417 struct task_struct *tsk);
418
419 extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
420 const enum hrtimer_mode mode);
421 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
422 unsigned long delta, const enum hrtimer_mode mode, int clock);
423 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
424
425 /* Soft interrupt function to run the hrtimer queues: */
426 extern void hrtimer_run_queues(void);
427 extern void hrtimer_run_pending(void);
428
429 /* Bootup initialization: */
430 extern void __init hrtimers_init(void);
431
432 #if BITS_PER_LONG < 64
433 extern u64 ktime_divns(const ktime_t kt, s64 div);
434 #else /* BITS_PER_LONG < 64 */
435 # define ktime_divns(kt, div) (u64)((kt).tv64 / (div))
436 #endif
437
438 /* Show pending timers: */
439 extern void sysrq_timer_list_show(void);
440
441 #endif