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  * 0x04		timer is migrated to another cpu
58  *
59  * Special cases:
60  * 0x03		callback function running and enqueued
61  *		(was requeued on another CPU)
62  * 0x05		timer was migrated on CPU hotunplug
63  *
64  * The "callback function running and enqueued" status is only possible on
65  * SMP. It happens for example when a posix timer expired and the callback
66  * queued a signal. Between dropping the lock which protects the posix timer
67  * and reacquiring the base lock of the hrtimer, another CPU can deliver the
68  * signal and rearm the timer. We have to preserve the callback running state,
69  * as otherwise the timer could be removed before the softirq code finishes the
70  * the handling of the timer.
71  *
72  * The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state
73  * to preserve the HRTIMER_STATE_CALLBACK in the above scenario. This
74  * also affects HRTIMER_STATE_MIGRATE where the preservation is not
75  * necessary. HRTIMER_STATE_MIGRATE is cleared after the timer is
76  * enqueued on the new cpu.
77  *
78  * All state transitions are protected by cpu_base->lock.
79  */
80 #define HRTIMER_STATE_INACTIVE	0x00
81 #define HRTIMER_STATE_ENQUEUED	0x01
82 #define HRTIMER_STATE_CALLBACK	0x02
83 #define HRTIMER_STATE_MIGRATE	0x04
84 
85 /**
86  * struct hrtimer - the basic hrtimer structure
87  * @node:	timerqueue node, which also manages node.expires,
88  *		the absolute expiry time in the hrtimers internal
89  *		representation. The time is related to the clock on
90  *		which the timer is based. Is setup by adding
91  *		slack to the _softexpires value. For non range timers
92  *		identical to _softexpires.
93  * @_softexpires: the absolute earliest expiry time of the hrtimer.
94  *		The time which was given as expiry time when the timer
95  *		was armed.
96  * @function:	timer expiry callback function
97  * @base:	pointer to the timer base (per cpu and per clock)
98  * @state:	state information (See bit values above)
99  * @start_site:	timer statistics field to store the site where the timer
100  *		was started
101  * @start_comm: timer statistics field to store the name of the process which
102  *		started the timer
103  * @start_pid: timer statistics field to store the pid of the task which
104  *		started the timer
105  *
106  * The hrtimer structure must be initialized by hrtimer_init()
107  */
108 struct hrtimer {
109 	struct timerqueue_node		node;
110 	ktime_t				_softexpires;
111 	enum hrtimer_restart		(*function)(struct hrtimer *);
112 	struct hrtimer_clock_base	*base;
113 	unsigned long			state;
114 #ifdef CONFIG_TIMER_STATS
115 	int				start_pid;
116 	void				*start_site;
117 	char				start_comm[16];
118 #endif
119 };
120 
121 /**
122  * struct hrtimer_sleeper - simple sleeper structure
123  * @timer:	embedded timer structure
124  * @task:	task to wake up
125  *
126  * task is set to NULL, when the timer expires.
127  */
128 struct hrtimer_sleeper {
129 	struct hrtimer timer;
130 	struct task_struct *task;
131 };
132 
133 /**
134  * struct hrtimer_clock_base - the timer base for a specific clock
135  * @cpu_base:		per cpu clock base
136  * @index:		clock type index for per_cpu support when moving a
137  *			timer to a base on another cpu.
138  * @clockid:		clock id for per_cpu support
139  * @active:		red black tree root node for the active timers
140  * @resolution:		the resolution of the clock, in nanoseconds
141  * @get_time:		function to retrieve the current time of the clock
142  * @softirq_time:	the time when running the hrtimer queue in the softirq
143  * @offset:		offset of this clock to the monotonic base
144  */
145 struct hrtimer_clock_base {
146 	struct hrtimer_cpu_base	*cpu_base;
147 	int			index;
148 	clockid_t		clockid;
149 	struct timerqueue_head	active;
150 	ktime_t			resolution;
151 	ktime_t			(*get_time)(void);
152 	ktime_t			softirq_time;
153 	ktime_t			offset;
154 };
155 
156 enum  hrtimer_base_type {
157 	HRTIMER_BASE_MONOTONIC,
158 	HRTIMER_BASE_REALTIME,
159 	HRTIMER_BASE_BOOTTIME,
160 	HRTIMER_MAX_CLOCK_BASES,
161 };
162 
163 /*
164  * struct hrtimer_cpu_base - the per cpu clock bases
165  * @lock:		lock protecting the base and associated clock bases
166  *			and timers
167  * @active_bases:	Bitfield to mark bases with active timers
168  * @clock_was_set:	Indicates that clock was set from irq context.
169  * @expires_next:	absolute time of the next event which was scheduled
170  *			via clock_set_next_event()
171  * @hres_active:	State of high resolution mode
172  * @hang_detected:	The last hrtimer interrupt detected a hang
173  * @nr_events:		Total number of hrtimer interrupt events
174  * @nr_retries:		Total number of hrtimer interrupt retries
175  * @nr_hangs:		Total number of hrtimer interrupt hangs
176  * @max_hang_time:	Maximum time spent in hrtimer_interrupt
177  * @clock_base:		array of clock bases for this cpu
178  */
179 struct hrtimer_cpu_base {
180 	raw_spinlock_t			lock;
181 	unsigned int			active_bases;
182 	unsigned int			clock_was_set;
183 #ifdef CONFIG_HIGH_RES_TIMERS
184 	ktime_t				expires_next;
185 	int				hres_active;
186 	int				hang_detected;
187 	unsigned long			nr_events;
188 	unsigned long			nr_retries;
189 	unsigned long			nr_hangs;
190 	ktime_t				max_hang_time;
191 #endif
192 	struct hrtimer_clock_base	clock_base[HRTIMER_MAX_CLOCK_BASES];
193 };
194 
hrtimer_set_expires(struct hrtimer * timer,ktime_t time)195 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
196 {
197 	timer->node.expires = time;
198 	timer->_softexpires = time;
199 }
200 
hrtimer_set_expires_range(struct hrtimer * timer,ktime_t time,ktime_t delta)201 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
202 {
203 	timer->_softexpires = time;
204 	timer->node.expires = ktime_add_safe(time, delta);
205 }
206 
hrtimer_set_expires_range_ns(struct hrtimer * timer,ktime_t time,unsigned long delta)207 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
208 {
209 	timer->_softexpires = time;
210 	timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
211 }
212 
hrtimer_set_expires_tv64(struct hrtimer * timer,s64 tv64)213 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
214 {
215 	timer->node.expires.tv64 = tv64;
216 	timer->_softexpires.tv64 = tv64;
217 }
218 
hrtimer_add_expires(struct hrtimer * timer,ktime_t time)219 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
220 {
221 	timer->node.expires = ktime_add_safe(timer->node.expires, time);
222 	timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
223 }
224 
hrtimer_add_expires_ns(struct hrtimer * timer,u64 ns)225 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
226 {
227 	timer->node.expires = ktime_add_ns(timer->node.expires, ns);
228 	timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
229 }
230 
hrtimer_get_expires(const struct hrtimer * timer)231 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
232 {
233 	return timer->node.expires;
234 }
235 
hrtimer_get_softexpires(const struct hrtimer * timer)236 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
237 {
238 	return timer->_softexpires;
239 }
240 
hrtimer_get_expires_tv64(const struct hrtimer * timer)241 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
242 {
243 	return timer->node.expires.tv64;
244 }
hrtimer_get_softexpires_tv64(const struct hrtimer * timer)245 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
246 {
247 	return timer->_softexpires.tv64;
248 }
249 
hrtimer_get_expires_ns(const struct hrtimer * timer)250 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
251 {
252 	return ktime_to_ns(timer->node.expires);
253 }
254 
hrtimer_expires_remaining(const struct hrtimer * timer)255 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
256 {
257 	return ktime_sub(timer->node.expires, timer->base->get_time());
258 }
259 
260 #ifdef CONFIG_HIGH_RES_TIMERS
261 struct clock_event_device;
262 
263 extern void hrtimer_interrupt(struct clock_event_device *dev);
264 
265 /*
266  * In high resolution mode the time reference must be read accurate
267  */
hrtimer_cb_get_time(struct hrtimer * timer)268 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
269 {
270 	return timer->base->get_time();
271 }
272 
hrtimer_is_hres_active(struct hrtimer * timer)273 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
274 {
275 	return timer->base->cpu_base->hres_active;
276 }
277 
278 extern void hrtimer_peek_ahead_timers(void);
279 
280 /*
281  * The resolution of the clocks. The resolution value is returned in
282  * the clock_getres() system call to give application programmers an
283  * idea of the (in)accuracy of timers. Timer values are rounded up to
284  * this resolution values.
285  */
286 # define HIGH_RES_NSEC		1
287 # define KTIME_HIGH_RES		(ktime_t) { .tv64 = HIGH_RES_NSEC }
288 # define MONOTONIC_RES_NSEC	HIGH_RES_NSEC
289 # define KTIME_MONOTONIC_RES	KTIME_HIGH_RES
290 
291 extern void clock_was_set_delayed(void);
292 
293 #else
294 
295 # define MONOTONIC_RES_NSEC	LOW_RES_NSEC
296 # define KTIME_MONOTONIC_RES	KTIME_LOW_RES
297 
hrtimer_peek_ahead_timers(void)298 static inline void hrtimer_peek_ahead_timers(void) { }
299 
300 /*
301  * In non high resolution mode the time reference is taken from
302  * the base softirq time variable.
303  */
hrtimer_cb_get_time(struct hrtimer * timer)304 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
305 {
306 	return timer->base->softirq_time;
307 }
308 
hrtimer_is_hres_active(struct hrtimer * timer)309 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
310 {
311 	return 0;
312 }
313 
clock_was_set_delayed(void)314 static inline void clock_was_set_delayed(void) { }
315 
316 #endif
317 
318 extern void clock_was_set(void);
319 #ifdef CONFIG_TIMERFD
320 extern void timerfd_clock_was_set(void);
321 #else
timerfd_clock_was_set(void)322 static inline void timerfd_clock_was_set(void) { }
323 #endif
324 extern void hrtimers_resume(void);
325 
326 extern ktime_t ktime_get(void);
327 extern ktime_t ktime_get_real(void);
328 extern ktime_t ktime_get_boottime(void);
329 extern ktime_t ktime_get_monotonic_offset(void);
330 extern ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot);
331 
332 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
333 
334 
335 /* Exported timer functions: */
336 
337 /* Initialize timers: */
338 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
339 			 enum hrtimer_mode mode);
340 
341 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
342 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
343 				  enum hrtimer_mode mode);
344 
345 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
346 #else
hrtimer_init_on_stack(struct hrtimer * timer,clockid_t which_clock,enum hrtimer_mode mode)347 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
348 					 clockid_t which_clock,
349 					 enum hrtimer_mode mode)
350 {
351 	hrtimer_init(timer, which_clock, mode);
352 }
destroy_hrtimer_on_stack(struct hrtimer * timer)353 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
354 #endif
355 
356 /* Basic timer operations: */
357 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
358 			 const enum hrtimer_mode mode);
359 extern int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
360 			unsigned long range_ns, const enum hrtimer_mode mode);
361 extern int
362 __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
363 			 unsigned long delta_ns,
364 			 const enum hrtimer_mode mode, int wakeup);
365 
366 extern int hrtimer_cancel(struct hrtimer *timer);
367 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
368 
hrtimer_start_expires(struct hrtimer * timer,enum hrtimer_mode mode)369 static inline int hrtimer_start_expires(struct hrtimer *timer,
370 						enum hrtimer_mode mode)
371 {
372 	unsigned long delta;
373 	ktime_t soft, hard;
374 	soft = hrtimer_get_softexpires(timer);
375 	hard = hrtimer_get_expires(timer);
376 	delta = ktime_to_ns(ktime_sub(hard, soft));
377 	return hrtimer_start_range_ns(timer, soft, delta, mode);
378 }
379 
hrtimer_restart(struct hrtimer * timer)380 static inline int hrtimer_restart(struct hrtimer *timer)
381 {
382 	return hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
383 }
384 
385 /* Query timers: */
386 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
387 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
388 
389 extern ktime_t hrtimer_get_next_event(void);
390 
391 /*
392  * A timer is active, when it is enqueued into the rbtree or the
393  * callback function is running or it's in the state of being migrated
394  * to another cpu.
395  */
hrtimer_active(const struct hrtimer * timer)396 static inline int hrtimer_active(const struct hrtimer *timer)
397 {
398 	return timer->state != HRTIMER_STATE_INACTIVE;
399 }
400 
401 /*
402  * Helper function to check, whether the timer is on one of the queues
403  */
hrtimer_is_queued(struct hrtimer * timer)404 static inline int hrtimer_is_queued(struct hrtimer *timer)
405 {
406 	return timer->state & HRTIMER_STATE_ENQUEUED;
407 }
408 
409 /*
410  * Helper function to check, whether the timer is running the callback
411  * function
412  */
hrtimer_callback_running(struct hrtimer * timer)413 static inline int hrtimer_callback_running(struct hrtimer *timer)
414 {
415 	return timer->state & HRTIMER_STATE_CALLBACK;
416 }
417 
418 /* Forward a hrtimer so it expires after now: */
419 extern u64
420 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
421 
422 /* Forward a hrtimer so it expires after the hrtimer's current now */
hrtimer_forward_now(struct hrtimer * timer,ktime_t interval)423 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
424 				      ktime_t interval)
425 {
426 	return hrtimer_forward(timer, timer->base->get_time(), interval);
427 }
428 
429 /* Precise sleep: */
430 extern long hrtimer_nanosleep(struct timespec *rqtp,
431 			      struct timespec __user *rmtp,
432 			      const enum hrtimer_mode mode,
433 			      const clockid_t clockid);
434 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
435 
436 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
437 				 struct task_struct *tsk);
438 
439 extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
440 						const enum hrtimer_mode mode);
441 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
442 		unsigned long delta, const enum hrtimer_mode mode, int clock);
443 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
444 
445 /* Soft interrupt function to run the hrtimer queues: */
446 extern void hrtimer_run_queues(void);
447 extern void hrtimer_run_pending(void);
448 
449 /* Bootup initialization: */
450 extern void __init hrtimers_init(void);
451 
452 #if BITS_PER_LONG < 64
453 extern u64 ktime_divns(const ktime_t kt, s64 div);
454 #else /* BITS_PER_LONG < 64 */
455 # define ktime_divns(kt, div)		(u64)((kt).tv64 / (div))
456 #endif
457 
458 /* Show pending timers: */
459 extern void sysrq_timer_list_show(void);
460 
461 #endif
462