include/linux/hrtimer.h

   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