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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
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24struct hrtimer_clock_base;
25struct hrtimer_cpu_base;
26
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27/*
28 * Mode arguments of xxx_hrtimer functions:
29 */
30enum hrtimer_mode {
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31 HRTIMER_MODE_ABS, /* Time value is absolute */
32 HRTIMER_MODE_REL, /* Time value is relative to now */
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33};
34
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35/*
36 * Return values for the callback function
37 */
c0a31329 38enum hrtimer_restart {
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39 HRTIMER_NORESTART, /* Timer is not restarted */
40 HRTIMER_RESTART, /* Timer must be restarted */
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41};
42
303e967f 43/*
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44 * hrtimer callback modes:
45 *
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
52 */
53enum hrtimer_cb_mode {
54 HRTIMER_CB_SOFTIRQ,
55 HRTIMER_CB_IRQSAFE,
56 HRTIMER_CB_IRQSAFE_NO_RESTART,
57 HRTIMER_CB_IRQSAFE_NO_SOFTIRQ,
58};
59
60/*
61 * Values to track state of the timer
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62 *
63 * Possible states:
64 *
65 * 0x00 inactive
66 * 0x01 enqueued into rbtree
67 * 0x02 callback function running
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68 * 0x04 callback pending (high resolution mode)
69 *
70 * Special case:
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71 * 0x03 callback function running and enqueued
72 * (was requeued on another CPU)
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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.
80 *
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.
83 *
84 * All state transitions are protected by cpu_base->lock.
85 */
86#define HRTIMER_STATE_INACTIVE 0x00
87#define HRTIMER_STATE_ENQUEUED 0x01
88#define HRTIMER_STATE_CALLBACK 0x02
54cdfdb4 89#define HRTIMER_STATE_PENDING 0x04
303e967f 90
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91/**
92 * struct hrtimer - the basic hrtimer structure
c0a31329 93 * @node: red black tree node for time ordered insertion
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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.
c0a31329 97 * @function: timer expiry callback function
c0a31329 98 * @base: pointer to the timer base (per cpu and per clock)
303e967f 99 * @state: state information (See bit values above)
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100 * @cb_mode: high resolution timer feature to select the callback execution
101 * mode
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
104 * was started
105 * @start_comm: timer statistics field to store the name of the process which
106 * started the timer
107 * @start_pid: timer statistics field to store the pid of the task which
108 * started the timer
c0a31329 109 *
54cdfdb4 110 * The hrtimer structure must be initialized by hrtimer_init()
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111 */
112struct hrtimer {
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113 struct rb_node node;
114 ktime_t expires;
115 enum hrtimer_restart (*function)(struct hrtimer *);
116 struct hrtimer_clock_base *base;
303e967f 117 unsigned long state;
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118#ifdef CONFIG_HIGH_RES_TIMERS
119 enum hrtimer_cb_mode cb_mode;
120 struct list_head cb_entry;
121#endif
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122};
123
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124/**
125 * struct hrtimer_sleeper - simple sleeper structure
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126 * @timer: embedded timer structure
127 * @task: task to wake up
128 *
129 * task is set to NULL, when the timer expires.
130 */
131struct hrtimer_sleeper {
132 struct hrtimer timer;
133 struct task_struct *task;
134};
135
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136/**
137 * struct hrtimer_base - the timer base for a specific clock
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138 * @index: clock type index for per_cpu support when moving a
139 * timer to a base on another cpu.
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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
a580290c 144 * @get_softirq_time: function to retrieve the current time from the softirq
92127c7a 145 * @softirq_time: the time when running the hrtimer queue in the softirq
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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
c0a31329 149 */
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150struct hrtimer_clock_base {
151 struct hrtimer_cpu_base *cpu_base;
c0a31329 152 clockid_t index;
c0a31329 153 struct rb_root active;
288867ec 154 struct rb_node *first;
e2787630 155 ktime_t resolution;
c0a31329 156 ktime_t (*get_time)(void);
92127c7a 157 ktime_t (*get_softirq_time)(void);
92127c7a 158 ktime_t softirq_time;
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159#ifdef CONFIG_HIGH_RES_TIMERS
160 ktime_t offset;
161 int (*reprogram)(struct hrtimer *t,
162 struct hrtimer_clock_base *b,
163 ktime_t n);
164#endif
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165};
166
167#define HRTIMER_MAX_CLOCK_BASES 2
168
169/*
170 * struct hrtimer_cpu_base - the per cpu clock bases
171 * @lock: lock protecting the base and associated clock bases
172 * and timers
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
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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
181 * activated.
182 * @cb_pending: Expired timers are moved from the rbtree to this
183 * list in the timer interrupt. The list is processed
184 * in the softirq.
185 * @nr_events: Total number of timer interrupt events
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186 */
187struct hrtimer_cpu_base {
188 spinlock_t lock;
189 struct lock_class_key lock_key;
190 struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
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191#ifdef CONFIG_HIGH_RES_TIMERS
192 ktime_t expires_next;
193 int hres_active;
194 struct list_head cb_pending;
195 unsigned long nr_events;
196#endif
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197};
198
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199#ifdef CONFIG_HIGH_RES_TIMERS
200struct clock_event_device;
201
202extern void clock_was_set(void);
203extern void hrtimer_interrupt(struct clock_event_device *dev);
204
205/*
206 * In high resolution mode the time reference must be read accurate
207 */
208static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
209{
210 return timer->base->get_time();
211}
212
213/*
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.
218 */
219# define KTIME_HIGH_RES (ktime_t) { .tv64 = 1 }
220# define KTIME_MONOTONIC_RES KTIME_HIGH_RES
221
222#else
223
224# define KTIME_MONOTONIC_RES KTIME_LOW_RES
225
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226/*
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.
230 */
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231static inline void clock_was_set(void) { }
232
233/*
234 * In non high resolution mode the time reference is taken from
235 * the base softirq time variable.
236 */
237static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
238{
239 return timer->base->softirq_time;
240}
241
242#endif
243
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244extern ktime_t ktime_get(void);
245extern ktime_t ktime_get_real(void);
becf8b5d 246
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247/* Exported timer functions: */
248
249/* Initialize timers: */
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250extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
251 enum hrtimer_mode mode);
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252
253/* Basic timer operations: */
254extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
255 const enum hrtimer_mode mode);
256extern int hrtimer_cancel(struct hrtimer *timer);
257extern int hrtimer_try_to_cancel(struct hrtimer *timer);
258
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259static inline int hrtimer_restart(struct hrtimer *timer)
260{
261 return hrtimer_start(timer, timer->expires, HRTIMER_MODE_ABS);
262}
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263
264/* Query timers: */
265extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
266extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
267
69239749 268extern ktime_t hrtimer_get_next_event(void);
69239749 269
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270/*
271 * A timer is active, when it is enqueued into the rbtree or the callback
272 * function is running.
273 */
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274static inline int hrtimer_active(const struct hrtimer *timer)
275{
303e967f 276 return timer->state != HRTIMER_STATE_INACTIVE;
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277}
278
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279/*
280 * Helper function to check, whether the timer is on one of the queues
281 */
282static inline int hrtimer_is_queued(struct hrtimer *timer)
283{
284 return timer->state &
285 (HRTIMER_STATE_ENQUEUED | HRTIMER_STATE_PENDING);
286}
287
c0a31329 288/* Forward a hrtimer so it expires after now: */
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289extern unsigned long
290hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
c0a31329 291
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292/* Precise sleep: */
293extern long hrtimer_nanosleep(struct timespec *rqtp,
294 struct timespec __user *rmtp,
295 const enum hrtimer_mode mode,
296 const clockid_t clockid);
1711ef38 297extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
10c94ec1 298
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299extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
300 struct task_struct *tsk);
301
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302/* Soft interrupt function to run the hrtimer queues: */
303extern void hrtimer_run_queues(void);
304
305/* Bootup initialization: */
306extern void __init hrtimers_init(void);
307
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308#if BITS_PER_LONG < 64
309extern 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))
312#endif
313
c0a31329 314#endif