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
27struct hrtimer_clock_base;
28struct hrtimer_cpu_base;
29
30/*
31 * Mode arguments of xxx_hrtimer functions:
32 */
33enum 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 */
44enum 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_pid: timer statistics field to store the pid of the task which
100 *		started the timer
101 * @start_site:	timer statistics field to store the site where the timer
102 *		was started
103 * @start_comm: timer statistics field to store the name of the process which
104 *		started the timer
105 *
106 * The hrtimer structure must be initialized by hrtimer_init()
107 */
108struct 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 */
128struct 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 */
145struct 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
156enum  hrtimer_base_type {
157	HRTIMER_BASE_MONOTONIC,
158	HRTIMER_BASE_REALTIME,
159	HRTIMER_BASE_BOOTTIME,
160	HRTIMER_BASE_TAI,
161	HRTIMER_MAX_CLOCK_BASES,
162};
163
164/*
165 * struct hrtimer_cpu_base - the per cpu clock bases
166 * @lock:		lock protecting the base and associated clock bases
167 *			and timers
168 * @cpu:		cpu number
169 * @active_bases:	Bitfield to mark bases with active timers
170 * @clock_was_set:	Indicates that clock was set from irq context.
171 * @expires_next:	absolute time of the next event which was scheduled
172 *			via clock_set_next_event()
173 * @in_hrtirq:		hrtimer_interrupt() is currently executing
174 * @hres_active:	State of high resolution mode
175 * @hang_detected:	The last hrtimer interrupt detected a hang
176 * @nr_events:		Total number of hrtimer interrupt events
177 * @nr_retries:		Total number of hrtimer interrupt retries
178 * @nr_hangs:		Total number of hrtimer interrupt hangs
179 * @max_hang_time:	Maximum time spent in hrtimer_interrupt
180 * @clock_base:		array of clock bases for this cpu
181 */
182struct hrtimer_cpu_base {
183	raw_spinlock_t			lock;
184	unsigned int			cpu;
185	unsigned int			active_bases;
186	unsigned int			clock_was_set;
187#ifdef CONFIG_HIGH_RES_TIMERS
188	ktime_t				expires_next;
189	int				in_hrtirq;
190	int				hres_active;
191	int				hang_detected;
192	unsigned long			nr_events;
193	unsigned long			nr_retries;
194	unsigned long			nr_hangs;
195	ktime_t				max_hang_time;
196#endif
197	struct hrtimer_clock_base	clock_base[HRTIMER_MAX_CLOCK_BASES];
198};
199
200static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
201{
202	timer->node.expires = time;
203	timer->_softexpires = time;
204}
205
206static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
207{
208	timer->_softexpires = time;
209	timer->node.expires = ktime_add_safe(time, delta);
210}
211
212static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
213{
214	timer->_softexpires = time;
215	timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
216}
217
218static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
219{
220	timer->node.expires.tv64 = tv64;
221	timer->_softexpires.tv64 = tv64;
222}
223
224static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
225{
226	timer->node.expires = ktime_add_safe(timer->node.expires, time);
227	timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
228}
229
230static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
231{
232	timer->node.expires = ktime_add_ns(timer->node.expires, ns);
233	timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
234}
235
236static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
237{
238	return timer->node.expires;
239}
240
241static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
242{
243	return timer->_softexpires;
244}
245
246static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
247{
248	return timer->node.expires.tv64;
249}
250static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
251{
252	return timer->_softexpires.tv64;
253}
254
255static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
256{
257	return ktime_to_ns(timer->node.expires);
258}
259
260static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
261{
262	return ktime_sub(timer->node.expires, timer->base->get_time());
263}
264
265#ifdef CONFIG_HIGH_RES_TIMERS
266struct clock_event_device;
267
268extern void hrtimer_interrupt(struct clock_event_device *dev);
269
270/*
271 * In high resolution mode the time reference must be read accurate
272 */
273static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
274{
275	return timer->base->get_time();
276}
277
278static inline int hrtimer_is_hres_active(struct hrtimer *timer)
279{
280	return timer->base->cpu_base->hres_active;
281}
282
283extern void hrtimer_peek_ahead_timers(void);
284
285/*
286 * The resolution of the clocks. The resolution value is returned in
287 * the clock_getres() system call to give application programmers an
288 * idea of the (in)accuracy of timers. Timer values are rounded up to
289 * this resolution values.
290 */
291# define HIGH_RES_NSEC		1
292# define KTIME_HIGH_RES		(ktime_t) { .tv64 = HIGH_RES_NSEC }
293# define MONOTONIC_RES_NSEC	HIGH_RES_NSEC
294# define KTIME_MONOTONIC_RES	KTIME_HIGH_RES
295
296extern void clock_was_set_delayed(void);
297
298#else
299
300# define MONOTONIC_RES_NSEC	LOW_RES_NSEC
301# define KTIME_MONOTONIC_RES	KTIME_LOW_RES
302
303static inline void hrtimer_peek_ahead_timers(void) { }
304
305/*
306 * In non high resolution mode the time reference is taken from
307 * the base softirq time variable.
308 */
309static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
310{
311	return timer->base->softirq_time;
312}
313
314static inline int hrtimer_is_hres_active(struct hrtimer *timer)
315{
316	return 0;
317}
318
319static inline void clock_was_set_delayed(void) { }
320
321#endif
322
323extern void clock_was_set(void);
324#ifdef CONFIG_TIMERFD
325extern void timerfd_clock_was_set(void);
326#else
327static inline void timerfd_clock_was_set(void) { }
328#endif
329extern void hrtimers_resume(void);
330
331DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
332
333
334/* Exported timer functions: */
335
336/* Initialize timers: */
337extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
338			 enum hrtimer_mode mode);
339
340#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
341extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
342				  enum hrtimer_mode mode);
343
344extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
345#else
346static inline void hrtimer_init_on_stack(struct hrtimer *timer,
347					 clockid_t which_clock,
348					 enum hrtimer_mode mode)
349{
350	hrtimer_init(timer, which_clock, mode);
351}
352static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
353#endif
354
355/* Basic timer operations: */
356extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
357			 const enum hrtimer_mode mode);
358extern int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
359			unsigned long range_ns, const enum hrtimer_mode mode);
360extern int
361__hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
362			 unsigned long delta_ns,
363			 const enum hrtimer_mode mode, int wakeup);
364
365extern int hrtimer_cancel(struct hrtimer *timer);
366extern int hrtimer_try_to_cancel(struct hrtimer *timer);
367
368static inline int hrtimer_start_expires(struct hrtimer *timer,
369						enum hrtimer_mode mode)
370{
371	unsigned long delta;
372	ktime_t soft, hard;
373	soft = hrtimer_get_softexpires(timer);
374	hard = hrtimer_get_expires(timer);
375	delta = ktime_to_ns(ktime_sub(hard, soft));
376	return hrtimer_start_range_ns(timer, soft, delta, mode);
377}
378
379static inline int hrtimer_restart(struct hrtimer *timer)
380{
381	return hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
382}
383
384/* Query timers: */
385extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
386extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
387
388extern ktime_t hrtimer_get_next_event(void);
389
390/*
391 * A timer is active, when it is enqueued into the rbtree or the
392 * callback function is running or it's in the state of being migrated
393 * to another cpu.
394 */
395static inline int hrtimer_active(const struct hrtimer *timer)
396{
397	return timer->state != HRTIMER_STATE_INACTIVE;
398}
399
400/*
401 * Helper function to check, whether the timer is on one of the queues
402 */
403static inline int hrtimer_is_queued(struct hrtimer *timer)
404{
405	return timer->state & HRTIMER_STATE_ENQUEUED;
406}
407
408/*
409 * Helper function to check, whether the timer is running the callback
410 * function
411 */
412static inline int hrtimer_callback_running(struct hrtimer *timer)
413{
414	return timer->state & HRTIMER_STATE_CALLBACK;
415}
416
417/* Forward a hrtimer so it expires after now: */
418extern u64
419hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
420
421/* Forward a hrtimer so it expires after the hrtimer's current now */
422static inline u64 hrtimer_forward_now(struct hrtimer *timer,
423				      ktime_t interval)
424{
425	return hrtimer_forward(timer, timer->base->get_time(), interval);
426}
427
428/* Precise sleep: */
429extern long hrtimer_nanosleep(struct timespec *rqtp,
430			      struct timespec __user *rmtp,
431			      const enum hrtimer_mode mode,
432			      const clockid_t clockid);
433extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
434
435extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
436				 struct task_struct *tsk);
437
438extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
439						const enum hrtimer_mode mode);
440extern int schedule_hrtimeout_range_clock(ktime_t *expires,
441		unsigned long delta, const enum hrtimer_mode mode, int clock);
442extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
443
444/* Soft interrupt function to run the hrtimer queues: */
445extern void hrtimer_run_queues(void);
446extern void hrtimer_run_pending(void);
447
448/* Bootup initialization: */
449extern void __init hrtimers_init(void);
450
451/* Show pending timers: */
452extern void sysrq_timer_list_show(void);
453
454#endif
455