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1/*
2 * linux/kernel/time/timekeeping.c
3 *
4 * Kernel timekeeping code and accessor functions
5 *
6 * This code was moved from linux/kernel/timer.c.
7 * Please see that file for copyright and history logs.
8 *
9 */
10
11#include <linux/module.h>
12#include <linux/interrupt.h>
13#include <linux/percpu.h>
14#include <linux/init.h>
15#include <linux/mm.h>
16#include <linux/sched.h>
17#include <linux/syscore_ops.h>
18#include <linux/clocksource.h>
19#include <linux/jiffies.h>
20#include <linux/time.h>
21#include <linux/tick.h>
22#include <linux/stop_machine.h>
23
24/* Structure holding internal timekeeping values. */
25struct timekeeper {
26 /* Current clocksource used for timekeeping. */
27 struct clocksource *clock;
28 /* The shift value of the current clocksource. */
29 int shift;
30
31 /* Number of clock cycles in one NTP interval. */
32 cycle_t cycle_interval;
33 /* Number of clock shifted nano seconds in one NTP interval. */
34 u64 xtime_interval;
35 /* shifted nano seconds left over when rounding cycle_interval */
36 s64 xtime_remainder;
37 /* Raw nano seconds accumulated per NTP interval. */
38 u32 raw_interval;
39
40 /* Clock shifted nano seconds remainder not stored in xtime.tv_nsec. */
41 u64 xtime_nsec;
42 /* Difference between accumulated time and NTP time in ntp
43 * shifted nano seconds. */
44 s64 ntp_error;
45 /* Shift conversion between clock shifted nano seconds and
46 * ntp shifted nano seconds. */
47 int ntp_error_shift;
48 /* NTP adjusted clock multiplier */
49 u32 mult;
50};
51
52static struct timekeeper timekeeper;
53
54/**
55 * timekeeper_setup_internals - Set up internals to use clocksource clock.
56 *
57 * @clock: Pointer to clocksource.
58 *
59 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
60 * pair and interval request.
61 *
62 * Unless you're the timekeeping code, you should not be using this!
63 */
64static void timekeeper_setup_internals(struct clocksource *clock)
65{
66 cycle_t interval;
67 u64 tmp, ntpinterval;
68
69 timekeeper.clock = clock;
70 clock->cycle_last = clock->read(clock);
71
72 /* Do the ns -> cycle conversion first, using original mult */
73 tmp = NTP_INTERVAL_LENGTH;
74 tmp <<= clock->shift;
75 ntpinterval = tmp;
76 tmp += clock->mult/2;
77 do_div(tmp, clock->mult);
78 if (tmp == 0)
79 tmp = 1;
80
81 interval = (cycle_t) tmp;
82 timekeeper.cycle_interval = interval;
83
84 /* Go back from cycles -> shifted ns */
85 timekeeper.xtime_interval = (u64) interval * clock->mult;
86 timekeeper.xtime_remainder = ntpinterval - timekeeper.xtime_interval;
87 timekeeper.raw_interval =
88 ((u64) interval * clock->mult) >> clock->shift;
89
90 timekeeper.xtime_nsec = 0;
91 timekeeper.shift = clock->shift;
92
93 timekeeper.ntp_error = 0;
94 timekeeper.ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
95
96 /*
97 * The timekeeper keeps its own mult values for the currently
98 * active clocksource. These value will be adjusted via NTP
99 * to counteract clock drifting.
100 */
101 timekeeper.mult = clock->mult;
102}
103
104/* Timekeeper helper functions. */
105static inline s64 timekeeping_get_ns(void)
106{
107 cycle_t cycle_now, cycle_delta;
108 struct clocksource *clock;
109
110 /* read clocksource: */
111 clock = timekeeper.clock;
112 cycle_now = clock->read(clock);
113
114 /* calculate the delta since the last update_wall_time: */
115 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
116
117 /* return delta convert to nanoseconds using ntp adjusted mult. */
118 return clocksource_cyc2ns(cycle_delta, timekeeper.mult,
119 timekeeper.shift);
120}
121
122static inline s64 timekeeping_get_ns_raw(void)
123{
124 cycle_t cycle_now, cycle_delta;
125 struct clocksource *clock;
126
127 /* read clocksource: */
128 clock = timekeeper.clock;
129 cycle_now = clock->read(clock);
130
131 /* calculate the delta since the last update_wall_time: */
132 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
133
134 /* return delta convert to nanoseconds using ntp adjusted mult. */
135 return clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
136}
137
138/*
139 * This read-write spinlock protects us from races in SMP while
140 * playing with xtime.
141 */
142__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
143
144
145/*
146 * The current time
147 * wall_to_monotonic is what we need to add to xtime (or xtime corrected
148 * for sub jiffie times) to get to monotonic time. Monotonic is pegged
149 * at zero at system boot time, so wall_to_monotonic will be negative,
150 * however, we will ALWAYS keep the tv_nsec part positive so we can use
151 * the usual normalization.
152 *
153 * wall_to_monotonic is moved after resume from suspend for the monotonic
154 * time not to jump. We need to add total_sleep_time to wall_to_monotonic
155 * to get the real boot based time offset.
156 *
157 * - wall_to_monotonic is no longer the boot time, getboottime must be
158 * used instead.
159 */
160static struct timespec xtime __attribute__ ((aligned (16)));
161static struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
162static struct timespec total_sleep_time;
163
164/*
165 * The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock.
166 */
167static struct timespec raw_time;
168
169/* flag for if timekeeping is suspended */
170int __read_mostly timekeeping_suspended;
171
172/* must hold xtime_lock */
173void timekeeping_leap_insert(int leapsecond)
174{
175 xtime.tv_sec += leapsecond;
176 wall_to_monotonic.tv_sec -= leapsecond;
177 update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
178 timekeeper.mult);
179}
180
181/**
182 * timekeeping_forward_now - update clock to the current time
183 *
184 * Forward the current clock to update its state since the last call to
185 * update_wall_time(). This is useful before significant clock changes,
186 * as it avoids having to deal with this time offset explicitly.
187 */
188static void timekeeping_forward_now(void)
189{
190 cycle_t cycle_now, cycle_delta;
191 struct clocksource *clock;
192 s64 nsec;
193
194 clock = timekeeper.clock;
195 cycle_now = clock->read(clock);
196 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
197 clock->cycle_last = cycle_now;
198
199 nsec = clocksource_cyc2ns(cycle_delta, timekeeper.mult,
200 timekeeper.shift);
201
202 /* If arch requires, add in gettimeoffset() */
203 nsec += arch_gettimeoffset();
204
205 timespec_add_ns(&xtime, nsec);
206
207 nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
208 timespec_add_ns(&raw_time, nsec);
209}
210
211/**
212 * getnstimeofday - Returns the time of day in a timespec
213 * @ts: pointer to the timespec to be set
214 *
215 * Returns the time of day in a timespec.
216 */
217void getnstimeofday(struct timespec *ts)
218{
219 unsigned long seq;
220 s64 nsecs;
221
222 WARN_ON(timekeeping_suspended);
223
224 do {
225 seq = read_seqbegin(&xtime_lock);
226
227 *ts = xtime;
228 nsecs = timekeeping_get_ns();
229
230 /* If arch requires, add in gettimeoffset() */
231 nsecs += arch_gettimeoffset();
232
233 } while (read_seqretry(&xtime_lock, seq));
234
235 timespec_add_ns(ts, nsecs);
236}
237
238EXPORT_SYMBOL(getnstimeofday);
239
240ktime_t ktime_get(void)
241{
242 unsigned int seq;
243 s64 secs, nsecs;
244
245 WARN_ON(timekeeping_suspended);
246
247 do {
248 seq = read_seqbegin(&xtime_lock);
249 secs = xtime.tv_sec + wall_to_monotonic.tv_sec;
250 nsecs = xtime.tv_nsec + wall_to_monotonic.tv_nsec;
251 nsecs += timekeeping_get_ns();
252
253 } while (read_seqretry(&xtime_lock, seq));
254 /*
255 * Use ktime_set/ktime_add_ns to create a proper ktime on
256 * 32-bit architectures without CONFIG_KTIME_SCALAR.
257 */
258 return ktime_add_ns(ktime_set(secs, 0), nsecs);
259}
260EXPORT_SYMBOL_GPL(ktime_get);
261
262/**
263 * ktime_get_ts - get the monotonic clock in timespec format
264 * @ts: pointer to timespec variable
265 *
266 * The function calculates the monotonic clock from the realtime
267 * clock and the wall_to_monotonic offset and stores the result
268 * in normalized timespec format in the variable pointed to by @ts.
269 */
270void ktime_get_ts(struct timespec *ts)
271{
272 struct timespec tomono;
273 unsigned int seq;
274 s64 nsecs;
275
276 WARN_ON(timekeeping_suspended);
277
278 do {
279 seq = read_seqbegin(&xtime_lock);
280 *ts = xtime;
281 tomono = wall_to_monotonic;
282 nsecs = timekeeping_get_ns();
283
284 } while (read_seqretry(&xtime_lock, seq));
285
286 set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec,
287 ts->tv_nsec + tomono.tv_nsec + nsecs);
288}
289EXPORT_SYMBOL_GPL(ktime_get_ts);
290
291#ifdef CONFIG_NTP_PPS
292
293/**
294 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
295 * @ts_raw: pointer to the timespec to be set to raw monotonic time
296 * @ts_real: pointer to the timespec to be set to the time of day
297 *
298 * This function reads both the time of day and raw monotonic time at the
299 * same time atomically and stores the resulting timestamps in timespec
300 * format.
301 */
302void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
303{
304 unsigned long seq;
305 s64 nsecs_raw, nsecs_real;
306
307 WARN_ON_ONCE(timekeeping_suspended);
308
309 do {
310 u32 arch_offset;
311
312 seq = read_seqbegin(&xtime_lock);
313
314 *ts_raw = raw_time;
315 *ts_real = xtime;
316
317 nsecs_raw = timekeeping_get_ns_raw();
318 nsecs_real = timekeeping_get_ns();
319
320 /* If arch requires, add in gettimeoffset() */
321 arch_offset = arch_gettimeoffset();
322 nsecs_raw += arch_offset;
323 nsecs_real += arch_offset;
324
325 } while (read_seqretry(&xtime_lock, seq));
326
327 timespec_add_ns(ts_raw, nsecs_raw);
328 timespec_add_ns(ts_real, nsecs_real);
329}
330EXPORT_SYMBOL(getnstime_raw_and_real);
331
332#endif /* CONFIG_NTP_PPS */
333
334/**
335 * do_gettimeofday - Returns the time of day in a timeval
336 * @tv: pointer to the timeval to be set
337 *
338 * NOTE: Users should be converted to using getnstimeofday()
339 */
340void do_gettimeofday(struct timeval *tv)
341{
342 struct timespec now;
343
344 getnstimeofday(&now);
345 tv->tv_sec = now.tv_sec;
346 tv->tv_usec = now.tv_nsec/1000;
347}
348
349EXPORT_SYMBOL(do_gettimeofday);
350/**
351 * do_settimeofday - Sets the time of day
352 * @tv: pointer to the timespec variable containing the new time
353 *
354 * Sets the time of day to the new time and update NTP and notify hrtimers
355 */
356int do_settimeofday(const struct timespec *tv)
357{
358 struct timespec ts_delta;
359 unsigned long flags;
360
361 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
362 return -EINVAL;
363
364 write_seqlock_irqsave(&xtime_lock, flags);
365
366 timekeeping_forward_now();
367
368 ts_delta.tv_sec = tv->tv_sec - xtime.tv_sec;
369 ts_delta.tv_nsec = tv->tv_nsec - xtime.tv_nsec;
370 wall_to_monotonic = timespec_sub(wall_to_monotonic, ts_delta);
371
372 xtime = *tv;
373
374 timekeeper.ntp_error = 0;
375 ntp_clear();
376
377 update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
378 timekeeper.mult);
379
380 write_sequnlock_irqrestore(&xtime_lock, flags);
381
382 /* signal hrtimers about time change */
383 clock_was_set();
384
385 return 0;
386}
387
388EXPORT_SYMBOL(do_settimeofday);
389
390
391/**
392 * timekeeping_inject_offset - Adds or subtracts from the current time.
393 * @tv: pointer to the timespec variable containing the offset
394 *
395 * Adds or subtracts an offset value from the current time.
396 */
397int timekeeping_inject_offset(struct timespec *ts)
398{
399 unsigned long flags;
400
401 if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
402 return -EINVAL;
403
404 write_seqlock_irqsave(&xtime_lock, flags);
405
406 timekeeping_forward_now();
407
408 xtime = timespec_add(xtime, *ts);
409 wall_to_monotonic = timespec_sub(wall_to_monotonic, *ts);
410
411 timekeeper.ntp_error = 0;
412 ntp_clear();
413
414 update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
415 timekeeper.mult);
416
417 write_sequnlock_irqrestore(&xtime_lock, flags);
418
419 /* signal hrtimers about time change */
420 clock_was_set();
421
422 return 0;
423}
424EXPORT_SYMBOL(timekeeping_inject_offset);
425
426/**
427 * change_clocksource - Swaps clocksources if a new one is available
428 *
429 * Accumulates current time interval and initializes new clocksource
430 */
431static int change_clocksource(void *data)
432{
433 struct clocksource *new, *old;
434
435 new = (struct clocksource *) data;
436
437 timekeeping_forward_now();
438 if (!new->enable || new->enable(new) == 0) {
439 old = timekeeper.clock;
440 timekeeper_setup_internals(new);
441 if (old->disable)
442 old->disable(old);
443 }
444 return 0;
445}
446
447/**
448 * timekeeping_notify - Install a new clock source
449 * @clock: pointer to the clock source
450 *
451 * This function is called from clocksource.c after a new, better clock
452 * source has been registered. The caller holds the clocksource_mutex.
453 */
454void timekeeping_notify(struct clocksource *clock)
455{
456 if (timekeeper.clock == clock)
457 return;
458 stop_machine(change_clocksource, clock, NULL);
459 tick_clock_notify();
460}
461
462/**
463 * ktime_get_real - get the real (wall-) time in ktime_t format
464 *
465 * returns the time in ktime_t format
466 */
467ktime_t ktime_get_real(void)
468{
469 struct timespec now;
470
471 getnstimeofday(&now);
472
473 return timespec_to_ktime(now);
474}
475EXPORT_SYMBOL_GPL(ktime_get_real);
476
477/**
478 * getrawmonotonic - Returns the raw monotonic time in a timespec
479 * @ts: pointer to the timespec to be set
480 *
481 * Returns the raw monotonic time (completely un-modified by ntp)
482 */
483void getrawmonotonic(struct timespec *ts)
484{
485 unsigned long seq;
486 s64 nsecs;
487
488 do {
489 seq = read_seqbegin(&xtime_lock);
490 nsecs = timekeeping_get_ns_raw();
491 *ts = raw_time;
492
493 } while (read_seqretry(&xtime_lock, seq));
494
495 timespec_add_ns(ts, nsecs);
496}
497EXPORT_SYMBOL(getrawmonotonic);
498
499
500/**
501 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
502 */
503int timekeeping_valid_for_hres(void)
504{
505 unsigned long seq;
506 int ret;
507
508 do {
509 seq = read_seqbegin(&xtime_lock);
510
511 ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
512
513 } while (read_seqretry(&xtime_lock, seq));
514
515 return ret;
516}
517
518/**
519 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
520 *
521 * Caller must observe xtime_lock via read_seqbegin/read_seqretry to
522 * ensure that the clocksource does not change!
523 */
524u64 timekeeping_max_deferment(void)
525{
526 return timekeeper.clock->max_idle_ns;
527}
528
529/**
530 * read_persistent_clock - Return time from the persistent clock.
531 *
532 * Weak dummy function for arches that do not yet support it.
533 * Reads the time from the battery backed persistent clock.
534 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
535 *
536 * XXX - Do be sure to remove it once all arches implement it.
537 */
538void __attribute__((weak)) read_persistent_clock(struct timespec *ts)
539{
540 ts->tv_sec = 0;
541 ts->tv_nsec = 0;
542}
543
544/**
545 * read_boot_clock - Return time of the system start.
546 *
547 * Weak dummy function for arches that do not yet support it.
548 * Function to read the exact time the system has been started.
549 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
550 *
551 * XXX - Do be sure to remove it once all arches implement it.
552 */
553void __attribute__((weak)) read_boot_clock(struct timespec *ts)
554{
555 ts->tv_sec = 0;
556 ts->tv_nsec = 0;
557}
558
559/*
560 * timekeeping_init - Initializes the clocksource and common timekeeping values
561 */
562void __init timekeeping_init(void)
563{
564 struct clocksource *clock;
565 unsigned long flags;
566 struct timespec now, boot;
567
568 read_persistent_clock(&now);
569 read_boot_clock(&boot);
570
571 write_seqlock_irqsave(&xtime_lock, flags);
572
573 ntp_init();
574
575 clock = clocksource_default_clock();
576 if (clock->enable)
577 clock->enable(clock);
578 timekeeper_setup_internals(clock);
579
580 xtime.tv_sec = now.tv_sec;
581 xtime.tv_nsec = now.tv_nsec;
582 raw_time.tv_sec = 0;
583 raw_time.tv_nsec = 0;
584 if (boot.tv_sec == 0 && boot.tv_nsec == 0) {
585 boot.tv_sec = xtime.tv_sec;
586 boot.tv_nsec = xtime.tv_nsec;
587 }
588 set_normalized_timespec(&wall_to_monotonic,
589 -boot.tv_sec, -boot.tv_nsec);
590 total_sleep_time.tv_sec = 0;
591 total_sleep_time.tv_nsec = 0;
592 write_sequnlock_irqrestore(&xtime_lock, flags);
593}
594
595/* time in seconds when suspend began */
596static struct timespec timekeeping_suspend_time;
597
598/**
599 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
600 * @delta: pointer to a timespec delta value
601 *
602 * Takes a timespec offset measuring a suspend interval and properly
603 * adds the sleep offset to the timekeeping variables.
604 */
605static void __timekeeping_inject_sleeptime(struct timespec *delta)
606{
607 if (!timespec_valid(delta)) {
608 printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
609 "sleep delta value!\n");
610 return;
611 }
612
613 xtime = timespec_add(xtime, *delta);
614 wall_to_monotonic = timespec_sub(wall_to_monotonic, *delta);
615 total_sleep_time = timespec_add(total_sleep_time, *delta);
616}
617
618
619/**
620 * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
621 * @delta: pointer to a timespec delta value
622 *
623 * This hook is for architectures that cannot support read_persistent_clock
624 * because their RTC/persistent clock is only accessible when irqs are enabled.
625 *
626 * This function should only be called by rtc_resume(), and allows
627 * a suspend offset to be injected into the timekeeping values.
628 */
629void timekeeping_inject_sleeptime(struct timespec *delta)
630{
631 unsigned long flags;
632 struct timespec ts;
633
634 /* Make sure we don't set the clock twice */
635 read_persistent_clock(&ts);
636 if (!(ts.tv_sec == 0 && ts.tv_nsec == 0))
637 return;
638
639 write_seqlock_irqsave(&xtime_lock, flags);
640 timekeeping_forward_now();
641
642 __timekeeping_inject_sleeptime(delta);
643
644 timekeeper.ntp_error = 0;
645 ntp_clear();
646 update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
647 timekeeper.mult);
648
649 write_sequnlock_irqrestore(&xtime_lock, flags);
650
651 /* signal hrtimers about time change */
652 clock_was_set();
653}
654
655
656/**
657 * timekeeping_resume - Resumes the generic timekeeping subsystem.
658 *
659 * This is for the generic clocksource timekeeping.
660 * xtime/wall_to_monotonic/jiffies/etc are
661 * still managed by arch specific suspend/resume code.
662 */
663static void timekeeping_resume(void)
664{
665 unsigned long flags;
666 struct timespec ts;
667
668 read_persistent_clock(&ts);
669
670 clocksource_resume();
671
672 write_seqlock_irqsave(&xtime_lock, flags);
673
674 if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {
675 ts = timespec_sub(ts, timekeeping_suspend_time);
676 __timekeeping_inject_sleeptime(&ts);
677 }
678 /* re-base the last cycle value */
679 timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
680 timekeeper.ntp_error = 0;
681 timekeeping_suspended = 0;
682 write_sequnlock_irqrestore(&xtime_lock, flags);
683
684 touch_softlockup_watchdog();
685
686 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
687
688 /* Resume hrtimers */
689 hrtimers_resume();
690}
691
692static int timekeeping_suspend(void)
693{
694 unsigned long flags;
695 struct timespec delta, delta_delta;
696 static struct timespec old_delta;
697
698 read_persistent_clock(&timekeeping_suspend_time);
699
700 write_seqlock_irqsave(&xtime_lock, flags);
701 timekeeping_forward_now();
702 timekeeping_suspended = 1;
703
704 /*
705 * To avoid drift caused by repeated suspend/resumes,
706 * which each can add ~1 second drift error,
707 * try to compensate so the difference in system time
708 * and persistent_clock time stays close to constant.
709 */
710 delta = timespec_sub(xtime, timekeeping_suspend_time);
711 delta_delta = timespec_sub(delta, old_delta);
712 if (abs(delta_delta.tv_sec) >= 2) {
713 /*
714 * if delta_delta is too large, assume time correction
715 * has occured and set old_delta to the current delta.
716 */
717 old_delta = delta;
718 } else {
719 /* Otherwise try to adjust old_system to compensate */
720 timekeeping_suspend_time =
721 timespec_add(timekeeping_suspend_time, delta_delta);
722 }
723 write_sequnlock_irqrestore(&xtime_lock, flags);
724
725 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
726 clocksource_suspend();
727
728 return 0;
729}
730
731/* sysfs resume/suspend bits for timekeeping */
732static struct syscore_ops timekeeping_syscore_ops = {
733 .resume = timekeeping_resume,
734 .suspend = timekeeping_suspend,
735};
736
737static int __init timekeeping_init_ops(void)
738{
739 register_syscore_ops(&timekeeping_syscore_ops);
740 return 0;
741}
742
743device_initcall(timekeeping_init_ops);
744
745/*
746 * If the error is already larger, we look ahead even further
747 * to compensate for late or lost adjustments.
748 */
749static __always_inline int timekeeping_bigadjust(s64 error, s64 *interval,
750 s64 *offset)
751{
752 s64 tick_error, i;
753 u32 look_ahead, adj;
754 s32 error2, mult;
755
756 /*
757 * Use the current error value to determine how much to look ahead.
758 * The larger the error the slower we adjust for it to avoid problems
759 * with losing too many ticks, otherwise we would overadjust and
760 * produce an even larger error. The smaller the adjustment the
761 * faster we try to adjust for it, as lost ticks can do less harm
762 * here. This is tuned so that an error of about 1 msec is adjusted
763 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
764 */
765 error2 = timekeeper.ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
766 error2 = abs(error2);
767 for (look_ahead = 0; error2 > 0; look_ahead++)
768 error2 >>= 2;
769
770 /*
771 * Now calculate the error in (1 << look_ahead) ticks, but first
772 * remove the single look ahead already included in the error.
773 */
774 tick_error = tick_length >> (timekeeper.ntp_error_shift + 1);
775 tick_error -= timekeeper.xtime_interval >> 1;
776 error = ((error - tick_error) >> look_ahead) + tick_error;
777
778 /* Finally calculate the adjustment shift value. */
779 i = *interval;
780 mult = 1;
781 if (error < 0) {
782 error = -error;
783 *interval = -*interval;
784 *offset = -*offset;
785 mult = -1;
786 }
787 for (adj = 0; error > i; adj++)
788 error >>= 1;
789
790 *interval <<= adj;
791 *offset <<= adj;
792 return mult << adj;
793}
794
795/*
796 * Adjust the multiplier to reduce the error value,
797 * this is optimized for the most common adjustments of -1,0,1,
798 * for other values we can do a bit more work.
799 */
800static void timekeeping_adjust(s64 offset)
801{
802 s64 error, interval = timekeeper.cycle_interval;
803 int adj;
804
805 error = timekeeper.ntp_error >> (timekeeper.ntp_error_shift - 1);
806 if (error > interval) {
807 error >>= 2;
808 if (likely(error <= interval))
809 adj = 1;
810 else
811 adj = timekeeping_bigadjust(error, &interval, &offset);
812 } else if (error < -interval) {
813 error >>= 2;
814 if (likely(error >= -interval)) {
815 adj = -1;
816 interval = -interval;
817 offset = -offset;
818 } else
819 adj = timekeeping_bigadjust(error, &interval, &offset);
820 } else
821 return;
822
823 timekeeper.mult += adj;
824 timekeeper.xtime_interval += interval;
825 timekeeper.xtime_nsec -= offset;
826 timekeeper.ntp_error -= (interval - offset) <<
827 timekeeper.ntp_error_shift;
828}
829
830
831/**
832 * logarithmic_accumulation - shifted accumulation of cycles
833 *
834 * This functions accumulates a shifted interval of cycles into
835 * into a shifted interval nanoseconds. Allows for O(log) accumulation
836 * loop.
837 *
838 * Returns the unconsumed cycles.
839 */
840static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
841{
842 u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift;
843 u64 raw_nsecs;
844
845 /* If the offset is smaller then a shifted interval, do nothing */
846 if (offset < timekeeper.cycle_interval<<shift)
847 return offset;
848
849 /* Accumulate one shifted interval */
850 offset -= timekeeper.cycle_interval << shift;
851 timekeeper.clock->cycle_last += timekeeper.cycle_interval << shift;
852
853 timekeeper.xtime_nsec += timekeeper.xtime_interval << shift;
854 while (timekeeper.xtime_nsec >= nsecps) {
855 timekeeper.xtime_nsec -= nsecps;
856 xtime.tv_sec++;
857 second_overflow();
858 }
859
860 /* Accumulate raw time */
861 raw_nsecs = timekeeper.raw_interval << shift;
862 raw_nsecs += raw_time.tv_nsec;
863 if (raw_nsecs >= NSEC_PER_SEC) {
864 u64 raw_secs = raw_nsecs;
865 raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
866 raw_time.tv_sec += raw_secs;
867 }
868 raw_time.tv_nsec = raw_nsecs;
869
870 /* Accumulate error between NTP and clock interval */
871 timekeeper.ntp_error += tick_length << shift;
872 timekeeper.ntp_error -=
873 (timekeeper.xtime_interval + timekeeper.xtime_remainder) <<
874 (timekeeper.ntp_error_shift + shift);
875
876 return offset;
877}
878
879
880/**
881 * update_wall_time - Uses the current clocksource to increment the wall time
882 *
883 * Called from the timer interrupt, must hold a write on xtime_lock.
884 */
885static void update_wall_time(void)
886{
887 struct clocksource *clock;
888 cycle_t offset;
889 int shift = 0, maxshift;
890
891 /* Make sure we're fully resumed: */
892 if (unlikely(timekeeping_suspended))
893 return;
894
895 clock = timekeeper.clock;
896
897#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
898 offset = timekeeper.cycle_interval;
899#else
900 offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
901#endif
902 timekeeper.xtime_nsec = (s64)xtime.tv_nsec << timekeeper.shift;
903
904 /*
905 * With NO_HZ we may have to accumulate many cycle_intervals
906 * (think "ticks") worth of time at once. To do this efficiently,
907 * we calculate the largest doubling multiple of cycle_intervals
908 * that is smaller then the offset. We then accumulate that
909 * chunk in one go, and then try to consume the next smaller
910 * doubled multiple.
911 */
912 shift = ilog2(offset) - ilog2(timekeeper.cycle_interval);
913 shift = max(0, shift);
914 /* Bound shift to one less then what overflows tick_length */
915 maxshift = (8*sizeof(tick_length) - (ilog2(tick_length)+1)) - 1;
916 shift = min(shift, maxshift);
917 while (offset >= timekeeper.cycle_interval) {
918 offset = logarithmic_accumulation(offset, shift);
919 if(offset < timekeeper.cycle_interval<<shift)
920 shift--;
921 }
922
923 /* correct the clock when NTP error is too big */
924 timekeeping_adjust(offset);
925
926 /*
927 * Since in the loop above, we accumulate any amount of time
928 * in xtime_nsec over a second into xtime.tv_sec, its possible for
929 * xtime_nsec to be fairly small after the loop. Further, if we're
930 * slightly speeding the clocksource up in timekeeping_adjust(),
931 * its possible the required corrective factor to xtime_nsec could
932 * cause it to underflow.
933 *
934 * Now, we cannot simply roll the accumulated second back, since
935 * the NTP subsystem has been notified via second_overflow. So
936 * instead we push xtime_nsec forward by the amount we underflowed,
937 * and add that amount into the error.
938 *
939 * We'll correct this error next time through this function, when
940 * xtime_nsec is not as small.
941 */
942 if (unlikely((s64)timekeeper.xtime_nsec < 0)) {
943 s64 neg = -(s64)timekeeper.xtime_nsec;
944 timekeeper.xtime_nsec = 0;
945 timekeeper.ntp_error += neg << timekeeper.ntp_error_shift;
946 }
947
948
949 /*
950 * Store full nanoseconds into xtime after rounding it up and
951 * add the remainder to the error difference.
952 */
953 xtime.tv_nsec = ((s64) timekeeper.xtime_nsec >> timekeeper.shift) + 1;
954 timekeeper.xtime_nsec -= (s64) xtime.tv_nsec << timekeeper.shift;
955 timekeeper.ntp_error += timekeeper.xtime_nsec <<
956 timekeeper.ntp_error_shift;
957
958 /*
959 * Finally, make sure that after the rounding
960 * xtime.tv_nsec isn't larger then NSEC_PER_SEC
961 */
962 if (unlikely(xtime.tv_nsec >= NSEC_PER_SEC)) {
963 xtime.tv_nsec -= NSEC_PER_SEC;
964 xtime.tv_sec++;
965 second_overflow();
966 }
967
968 /* check to see if there is a new clocksource to use */
969 update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
970 timekeeper.mult);
971}
972
973/**
974 * getboottime - Return the real time of system boot.
975 * @ts: pointer to the timespec to be set
976 *
977 * Returns the wall-time of boot in a timespec.
978 *
979 * This is based on the wall_to_monotonic offset and the total suspend
980 * time. Calls to settimeofday will affect the value returned (which
981 * basically means that however wrong your real time clock is at boot time,
982 * you get the right time here).
983 */
984void getboottime(struct timespec *ts)
985{
986 struct timespec boottime = {
987 .tv_sec = wall_to_monotonic.tv_sec + total_sleep_time.tv_sec,
988 .tv_nsec = wall_to_monotonic.tv_nsec + total_sleep_time.tv_nsec
989 };
990
991 set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
992}
993EXPORT_SYMBOL_GPL(getboottime);
994
995
996/**
997 * get_monotonic_boottime - Returns monotonic time since boot
998 * @ts: pointer to the timespec to be set
999 *
1000 * Returns the monotonic time since boot in a timespec.
1001 *
1002 * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
1003 * includes the time spent in suspend.
1004 */
1005void get_monotonic_boottime(struct timespec *ts)
1006{
1007 struct timespec tomono, sleep;
1008 unsigned int seq;
1009 s64 nsecs;
1010
1011 WARN_ON(timekeeping_suspended);
1012
1013 do {
1014 seq = read_seqbegin(&xtime_lock);
1015 *ts = xtime;
1016 tomono = wall_to_monotonic;
1017 sleep = total_sleep_time;
1018 nsecs = timekeeping_get_ns();
1019
1020 } while (read_seqretry(&xtime_lock, seq));
1021
1022 set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec + sleep.tv_sec,
1023 ts->tv_nsec + tomono.tv_nsec + sleep.tv_nsec + nsecs);
1024}
1025EXPORT_SYMBOL_GPL(get_monotonic_boottime);
1026
1027/**
1028 * ktime_get_boottime - Returns monotonic time since boot in a ktime
1029 *
1030 * Returns the monotonic time since boot in a ktime
1031 *
1032 * This is similar to CLOCK_MONTONIC/ktime_get, but also
1033 * includes the time spent in suspend.
1034 */
1035ktime_t ktime_get_boottime(void)
1036{
1037 struct timespec ts;
1038
1039 get_monotonic_boottime(&ts);
1040 return timespec_to_ktime(ts);
1041}
1042EXPORT_SYMBOL_GPL(ktime_get_boottime);
1043
1044/**
1045 * monotonic_to_bootbased - Convert the monotonic time to boot based.
1046 * @ts: pointer to the timespec to be converted
1047 */
1048void monotonic_to_bootbased(struct timespec *ts)
1049{
1050 *ts = timespec_add(*ts, total_sleep_time);
1051}
1052EXPORT_SYMBOL_GPL(monotonic_to_bootbased);
1053
1054unsigned long get_seconds(void)
1055{
1056 return xtime.tv_sec;
1057}
1058EXPORT_SYMBOL(get_seconds);
1059
1060struct timespec __current_kernel_time(void)
1061{
1062 return xtime;
1063}
1064
1065struct timespec current_kernel_time(void)
1066{
1067 struct timespec now;
1068 unsigned long seq;
1069
1070 do {
1071 seq = read_seqbegin(&xtime_lock);
1072
1073 now = xtime;
1074 } while (read_seqretry(&xtime_lock, seq));
1075
1076 return now;
1077}
1078EXPORT_SYMBOL(current_kernel_time);
1079
1080struct timespec get_monotonic_coarse(void)
1081{
1082 struct timespec now, mono;
1083 unsigned long seq;
1084
1085 do {
1086 seq = read_seqbegin(&xtime_lock);
1087
1088 now = xtime;
1089 mono = wall_to_monotonic;
1090 } while (read_seqretry(&xtime_lock, seq));
1091
1092 set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
1093 now.tv_nsec + mono.tv_nsec);
1094 return now;
1095}
1096
1097/*
1098 * The 64-bit jiffies value is not atomic - you MUST NOT read it
1099 * without sampling the sequence number in xtime_lock.
1100 * jiffies is defined in the linker script...
1101 */
1102void do_timer(unsigned long ticks)
1103{
1104 jiffies_64 += ticks;
1105 update_wall_time();
1106 calc_global_load(ticks);
1107}
1108
1109/**
1110 * get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic,
1111 * and sleep offsets.
1112 * @xtim: pointer to timespec to be set with xtime
1113 * @wtom: pointer to timespec to be set with wall_to_monotonic
1114 * @sleep: pointer to timespec to be set with time in suspend
1115 */
1116void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
1117 struct timespec *wtom, struct timespec *sleep)
1118{
1119 unsigned long seq;
1120
1121 do {
1122 seq = read_seqbegin(&xtime_lock);
1123 *xtim = xtime;
1124 *wtom = wall_to_monotonic;
1125 *sleep = total_sleep_time;
1126 } while (read_seqretry(&xtime_lock, seq));
1127}
1128
1129/**
1130 * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
1131 */
1132ktime_t ktime_get_monotonic_offset(void)
1133{
1134 unsigned long seq;
1135 struct timespec wtom;
1136
1137 do {
1138 seq = read_seqbegin(&xtime_lock);
1139 wtom = wall_to_monotonic;
1140 } while (read_seqretry(&xtime_lock, seq));
1141 return timespec_to_ktime(wtom);
1142}
1143
1144/**
1145 * xtime_update() - advances the timekeeping infrastructure
1146 * @ticks: number of ticks, that have elapsed since the last call.
1147 *
1148 * Must be called with interrupts disabled.
1149 */
1150void xtime_update(unsigned long ticks)
1151{
1152 write_seqlock(&xtime_lock);
1153 do_timer(ticks);
1154 write_sequnlock(&xtime_lock);
1155}
1/*
2 * linux/kernel/time/timekeeping.c
3 *
4 * Kernel timekeeping code and accessor functions
5 *
6 * This code was moved from linux/kernel/timer.c.
7 * Please see that file for copyright and history logs.
8 *
9 */
10
11#include <linux/module.h>
12#include <linux/interrupt.h>
13#include <linux/percpu.h>
14#include <linux/init.h>
15#include <linux/mm.h>
16#include <linux/sched.h>
17#include <linux/syscore_ops.h>
18#include <linux/clocksource.h>
19#include <linux/jiffies.h>
20#include <linux/time.h>
21#include <linux/tick.h>
22#include <linux/stop_machine.h>
23
24/* Structure holding internal timekeeping values. */
25struct timekeeper {
26 /* Current clocksource used for timekeeping. */
27 struct clocksource *clock;
28 /* NTP adjusted clock multiplier */
29 u32 mult;
30 /* The shift value of the current clocksource. */
31 int shift;
32
33 /* Number of clock cycles in one NTP interval. */
34 cycle_t cycle_interval;
35 /* Number of clock shifted nano seconds in one NTP interval. */
36 u64 xtime_interval;
37 /* shifted nano seconds left over when rounding cycle_interval */
38 s64 xtime_remainder;
39 /* Raw nano seconds accumulated per NTP interval. */
40 u32 raw_interval;
41
42 /* Clock shifted nano seconds remainder not stored in xtime.tv_nsec. */
43 u64 xtime_nsec;
44 /* Difference between accumulated time and NTP time in ntp
45 * shifted nano seconds. */
46 s64 ntp_error;
47 /* Shift conversion between clock shifted nano seconds and
48 * ntp shifted nano seconds. */
49 int ntp_error_shift;
50
51 /* The current time */
52 struct timespec xtime;
53 /*
54 * wall_to_monotonic is what we need to add to xtime (or xtime corrected
55 * for sub jiffie times) to get to monotonic time. Monotonic is pegged
56 * at zero at system boot time, so wall_to_monotonic will be negative,
57 * however, we will ALWAYS keep the tv_nsec part positive so we can use
58 * the usual normalization.
59 *
60 * wall_to_monotonic is moved after resume from suspend for the
61 * monotonic time not to jump. We need to add total_sleep_time to
62 * wall_to_monotonic to get the real boot based time offset.
63 *
64 * - wall_to_monotonic is no longer the boot time, getboottime must be
65 * used instead.
66 */
67 struct timespec wall_to_monotonic;
68 /* time spent in suspend */
69 struct timespec total_sleep_time;
70 /* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */
71 struct timespec raw_time;
72
73 /* Offset clock monotonic -> clock realtime */
74 ktime_t offs_real;
75
76 /* Offset clock monotonic -> clock boottime */
77 ktime_t offs_boot;
78
79 /* Seqlock for all timekeeper values */
80 seqlock_t lock;
81};
82
83static struct timekeeper timekeeper;
84
85/*
86 * This read-write spinlock protects us from races in SMP while
87 * playing with xtime.
88 */
89__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
90
91
92/* flag for if timekeeping is suspended */
93int __read_mostly timekeeping_suspended;
94
95
96
97/**
98 * timekeeper_setup_internals - Set up internals to use clocksource clock.
99 *
100 * @clock: Pointer to clocksource.
101 *
102 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
103 * pair and interval request.
104 *
105 * Unless you're the timekeeping code, you should not be using this!
106 */
107static void timekeeper_setup_internals(struct clocksource *clock)
108{
109 cycle_t interval;
110 u64 tmp, ntpinterval;
111
112 timekeeper.clock = clock;
113 clock->cycle_last = clock->read(clock);
114
115 /* Do the ns -> cycle conversion first, using original mult */
116 tmp = NTP_INTERVAL_LENGTH;
117 tmp <<= clock->shift;
118 ntpinterval = tmp;
119 tmp += clock->mult/2;
120 do_div(tmp, clock->mult);
121 if (tmp == 0)
122 tmp = 1;
123
124 interval = (cycle_t) tmp;
125 timekeeper.cycle_interval = interval;
126
127 /* Go back from cycles -> shifted ns */
128 timekeeper.xtime_interval = (u64) interval * clock->mult;
129 timekeeper.xtime_remainder = ntpinterval - timekeeper.xtime_interval;
130 timekeeper.raw_interval =
131 ((u64) interval * clock->mult) >> clock->shift;
132
133 timekeeper.xtime_nsec = 0;
134 timekeeper.shift = clock->shift;
135
136 timekeeper.ntp_error = 0;
137 timekeeper.ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
138
139 /*
140 * The timekeeper keeps its own mult values for the currently
141 * active clocksource. These value will be adjusted via NTP
142 * to counteract clock drifting.
143 */
144 timekeeper.mult = clock->mult;
145}
146
147/* Timekeeper helper functions. */
148static inline s64 timekeeping_get_ns(void)
149{
150 cycle_t cycle_now, cycle_delta;
151 struct clocksource *clock;
152
153 /* read clocksource: */
154 clock = timekeeper.clock;
155 cycle_now = clock->read(clock);
156
157 /* calculate the delta since the last update_wall_time: */
158 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
159
160 /* return delta convert to nanoseconds using ntp adjusted mult. */
161 return clocksource_cyc2ns(cycle_delta, timekeeper.mult,
162 timekeeper.shift);
163}
164
165static inline s64 timekeeping_get_ns_raw(void)
166{
167 cycle_t cycle_now, cycle_delta;
168 struct clocksource *clock;
169
170 /* read clocksource: */
171 clock = timekeeper.clock;
172 cycle_now = clock->read(clock);
173
174 /* calculate the delta since the last update_wall_time: */
175 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
176
177 /* return delta convert to nanoseconds. */
178 return clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
179}
180
181static void update_rt_offset(void)
182{
183 struct timespec tmp, *wtm = &timekeeper.wall_to_monotonic;
184
185 set_normalized_timespec(&tmp, -wtm->tv_sec, -wtm->tv_nsec);
186 timekeeper.offs_real = timespec_to_ktime(tmp);
187}
188
189/* must hold write on timekeeper.lock */
190static void timekeeping_update(bool clearntp)
191{
192 if (clearntp) {
193 timekeeper.ntp_error = 0;
194 ntp_clear();
195 }
196 update_rt_offset();
197 update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,
198 timekeeper.clock, timekeeper.mult);
199}
200
201
202/**
203 * timekeeping_forward_now - update clock to the current time
204 *
205 * Forward the current clock to update its state since the last call to
206 * update_wall_time(). This is useful before significant clock changes,
207 * as it avoids having to deal with this time offset explicitly.
208 */
209static void timekeeping_forward_now(void)
210{
211 cycle_t cycle_now, cycle_delta;
212 struct clocksource *clock;
213 s64 nsec;
214
215 clock = timekeeper.clock;
216 cycle_now = clock->read(clock);
217 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
218 clock->cycle_last = cycle_now;
219
220 nsec = clocksource_cyc2ns(cycle_delta, timekeeper.mult,
221 timekeeper.shift);
222
223 /* If arch requires, add in gettimeoffset() */
224 nsec += arch_gettimeoffset();
225
226 timespec_add_ns(&timekeeper.xtime, nsec);
227
228 nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
229 timespec_add_ns(&timekeeper.raw_time, nsec);
230}
231
232/**
233 * getnstimeofday - Returns the time of day in a timespec
234 * @ts: pointer to the timespec to be set
235 *
236 * Returns the time of day in a timespec.
237 */
238void getnstimeofday(struct timespec *ts)
239{
240 unsigned long seq;
241 s64 nsecs;
242
243 WARN_ON(timekeeping_suspended);
244
245 do {
246 seq = read_seqbegin(&timekeeper.lock);
247
248 *ts = timekeeper.xtime;
249 nsecs = timekeeping_get_ns();
250
251 /* If arch requires, add in gettimeoffset() */
252 nsecs += arch_gettimeoffset();
253
254 } while (read_seqretry(&timekeeper.lock, seq));
255
256 timespec_add_ns(ts, nsecs);
257}
258EXPORT_SYMBOL(getnstimeofday);
259
260ktime_t ktime_get(void)
261{
262 unsigned int seq;
263 s64 secs, nsecs;
264
265 WARN_ON(timekeeping_suspended);
266
267 do {
268 seq = read_seqbegin(&timekeeper.lock);
269 secs = timekeeper.xtime.tv_sec +
270 timekeeper.wall_to_monotonic.tv_sec;
271 nsecs = timekeeper.xtime.tv_nsec +
272 timekeeper.wall_to_monotonic.tv_nsec;
273 nsecs += timekeeping_get_ns();
274 /* If arch requires, add in gettimeoffset() */
275 nsecs += arch_gettimeoffset();
276
277 } while (read_seqretry(&timekeeper.lock, seq));
278 /*
279 * Use ktime_set/ktime_add_ns to create a proper ktime on
280 * 32-bit architectures without CONFIG_KTIME_SCALAR.
281 */
282 return ktime_add_ns(ktime_set(secs, 0), nsecs);
283}
284EXPORT_SYMBOL_GPL(ktime_get);
285
286/**
287 * ktime_get_ts - get the monotonic clock in timespec format
288 * @ts: pointer to timespec variable
289 *
290 * The function calculates the monotonic clock from the realtime
291 * clock and the wall_to_monotonic offset and stores the result
292 * in normalized timespec format in the variable pointed to by @ts.
293 */
294void ktime_get_ts(struct timespec *ts)
295{
296 struct timespec tomono;
297 unsigned int seq;
298 s64 nsecs;
299
300 WARN_ON(timekeeping_suspended);
301
302 do {
303 seq = read_seqbegin(&timekeeper.lock);
304 *ts = timekeeper.xtime;
305 tomono = timekeeper.wall_to_monotonic;
306 nsecs = timekeeping_get_ns();
307 /* If arch requires, add in gettimeoffset() */
308 nsecs += arch_gettimeoffset();
309
310 } while (read_seqretry(&timekeeper.lock, seq));
311
312 set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec,
313 ts->tv_nsec + tomono.tv_nsec + nsecs);
314}
315EXPORT_SYMBOL_GPL(ktime_get_ts);
316
317#ifdef CONFIG_NTP_PPS
318
319/**
320 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
321 * @ts_raw: pointer to the timespec to be set to raw monotonic time
322 * @ts_real: pointer to the timespec to be set to the time of day
323 *
324 * This function reads both the time of day and raw monotonic time at the
325 * same time atomically and stores the resulting timestamps in timespec
326 * format.
327 */
328void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
329{
330 unsigned long seq;
331 s64 nsecs_raw, nsecs_real;
332
333 WARN_ON_ONCE(timekeeping_suspended);
334
335 do {
336 u32 arch_offset;
337
338 seq = read_seqbegin(&timekeeper.lock);
339
340 *ts_raw = timekeeper.raw_time;
341 *ts_real = timekeeper.xtime;
342
343 nsecs_raw = timekeeping_get_ns_raw();
344 nsecs_real = timekeeping_get_ns();
345
346 /* If arch requires, add in gettimeoffset() */
347 arch_offset = arch_gettimeoffset();
348 nsecs_raw += arch_offset;
349 nsecs_real += arch_offset;
350
351 } while (read_seqretry(&timekeeper.lock, seq));
352
353 timespec_add_ns(ts_raw, nsecs_raw);
354 timespec_add_ns(ts_real, nsecs_real);
355}
356EXPORT_SYMBOL(getnstime_raw_and_real);
357
358#endif /* CONFIG_NTP_PPS */
359
360/**
361 * do_gettimeofday - Returns the time of day in a timeval
362 * @tv: pointer to the timeval to be set
363 *
364 * NOTE: Users should be converted to using getnstimeofday()
365 */
366void do_gettimeofday(struct timeval *tv)
367{
368 struct timespec now;
369
370 getnstimeofday(&now);
371 tv->tv_sec = now.tv_sec;
372 tv->tv_usec = now.tv_nsec/1000;
373}
374EXPORT_SYMBOL(do_gettimeofday);
375
376/**
377 * do_settimeofday - Sets the time of day
378 * @tv: pointer to the timespec variable containing the new time
379 *
380 * Sets the time of day to the new time and update NTP and notify hrtimers
381 */
382int do_settimeofday(const struct timespec *tv)
383{
384 struct timespec ts_delta;
385 unsigned long flags;
386
387 if (!timespec_valid_strict(tv))
388 return -EINVAL;
389
390 write_seqlock_irqsave(&timekeeper.lock, flags);
391
392 timekeeping_forward_now();
393
394 ts_delta.tv_sec = tv->tv_sec - timekeeper.xtime.tv_sec;
395 ts_delta.tv_nsec = tv->tv_nsec - timekeeper.xtime.tv_nsec;
396 timekeeper.wall_to_monotonic =
397 timespec_sub(timekeeper.wall_to_monotonic, ts_delta);
398
399 timekeeper.xtime = *tv;
400 timekeeping_update(true);
401
402 write_sequnlock_irqrestore(&timekeeper.lock, flags);
403
404 /* signal hrtimers about time change */
405 clock_was_set();
406
407 return 0;
408}
409EXPORT_SYMBOL(do_settimeofday);
410
411
412/**
413 * timekeeping_inject_offset - Adds or subtracts from the current time.
414 * @tv: pointer to the timespec variable containing the offset
415 *
416 * Adds or subtracts an offset value from the current time.
417 */
418int timekeeping_inject_offset(struct timespec *ts)
419{
420 unsigned long flags;
421 struct timespec tmp;
422 int ret = 0;
423
424 if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
425 return -EINVAL;
426
427 write_seqlock_irqsave(&timekeeper.lock, flags);
428
429 timekeeping_forward_now();
430
431 tmp = timespec_add(timekeeper.xtime, *ts);
432 if (!timespec_valid_strict(&tmp)) {
433 ret = -EINVAL;
434 goto error;
435 }
436
437 timekeeper.xtime = timespec_add(timekeeper.xtime, *ts);
438 timekeeper.wall_to_monotonic =
439 timespec_sub(timekeeper.wall_to_monotonic, *ts);
440
441error: /* even if we error out, we forwarded the time, so call update */
442 timekeeping_update(true);
443
444 write_sequnlock_irqrestore(&timekeeper.lock, flags);
445
446 /* signal hrtimers about time change */
447 clock_was_set();
448
449 return ret;
450}
451EXPORT_SYMBOL(timekeeping_inject_offset);
452
453/**
454 * change_clocksource - Swaps clocksources if a new one is available
455 *
456 * Accumulates current time interval and initializes new clocksource
457 */
458static int change_clocksource(void *data)
459{
460 struct clocksource *new, *old;
461 unsigned long flags;
462
463 new = (struct clocksource *) data;
464
465 write_seqlock_irqsave(&timekeeper.lock, flags);
466
467 timekeeping_forward_now();
468 if (!new->enable || new->enable(new) == 0) {
469 old = timekeeper.clock;
470 timekeeper_setup_internals(new);
471 if (old->disable)
472 old->disable(old);
473 }
474 timekeeping_update(true);
475
476 write_sequnlock_irqrestore(&timekeeper.lock, flags);
477
478 return 0;
479}
480
481/**
482 * timekeeping_notify - Install a new clock source
483 * @clock: pointer to the clock source
484 *
485 * This function is called from clocksource.c after a new, better clock
486 * source has been registered. The caller holds the clocksource_mutex.
487 */
488void timekeeping_notify(struct clocksource *clock)
489{
490 if (timekeeper.clock == clock)
491 return;
492 stop_machine(change_clocksource, clock, NULL);
493 tick_clock_notify();
494}
495
496/**
497 * ktime_get_real - get the real (wall-) time in ktime_t format
498 *
499 * returns the time in ktime_t format
500 */
501ktime_t ktime_get_real(void)
502{
503 struct timespec now;
504
505 getnstimeofday(&now);
506
507 return timespec_to_ktime(now);
508}
509EXPORT_SYMBOL_GPL(ktime_get_real);
510
511/**
512 * getrawmonotonic - Returns the raw monotonic time in a timespec
513 * @ts: pointer to the timespec to be set
514 *
515 * Returns the raw monotonic time (completely un-modified by ntp)
516 */
517void getrawmonotonic(struct timespec *ts)
518{
519 unsigned long seq;
520 s64 nsecs;
521
522 do {
523 seq = read_seqbegin(&timekeeper.lock);
524 nsecs = timekeeping_get_ns_raw();
525 *ts = timekeeper.raw_time;
526
527 } while (read_seqretry(&timekeeper.lock, seq));
528
529 timespec_add_ns(ts, nsecs);
530}
531EXPORT_SYMBOL(getrawmonotonic);
532
533
534/**
535 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
536 */
537int timekeeping_valid_for_hres(void)
538{
539 unsigned long seq;
540 int ret;
541
542 do {
543 seq = read_seqbegin(&timekeeper.lock);
544
545 ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
546
547 } while (read_seqretry(&timekeeper.lock, seq));
548
549 return ret;
550}
551
552/**
553 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
554 */
555u64 timekeeping_max_deferment(void)
556{
557 unsigned long seq;
558 u64 ret;
559 do {
560 seq = read_seqbegin(&timekeeper.lock);
561
562 ret = timekeeper.clock->max_idle_ns;
563
564 } while (read_seqretry(&timekeeper.lock, seq));
565
566 return ret;
567}
568
569/**
570 * read_persistent_clock - Return time from the persistent clock.
571 *
572 * Weak dummy function for arches that do not yet support it.
573 * Reads the time from the battery backed persistent clock.
574 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
575 *
576 * XXX - Do be sure to remove it once all arches implement it.
577 */
578void __attribute__((weak)) read_persistent_clock(struct timespec *ts)
579{
580 ts->tv_sec = 0;
581 ts->tv_nsec = 0;
582}
583
584/**
585 * read_boot_clock - Return time of the system start.
586 *
587 * Weak dummy function for arches that do not yet support it.
588 * Function to read the exact time the system has been started.
589 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
590 *
591 * XXX - Do be sure to remove it once all arches implement it.
592 */
593void __attribute__((weak)) read_boot_clock(struct timespec *ts)
594{
595 ts->tv_sec = 0;
596 ts->tv_nsec = 0;
597}
598
599/*
600 * timekeeping_init - Initializes the clocksource and common timekeeping values
601 */
602void __init timekeeping_init(void)
603{
604 struct clocksource *clock;
605 unsigned long flags;
606 struct timespec now, boot;
607
608 read_persistent_clock(&now);
609 if (!timespec_valid_strict(&now)) {
610 pr_warn("WARNING: Persistent clock returned invalid value!\n"
611 " Check your CMOS/BIOS settings.\n");
612 now.tv_sec = 0;
613 now.tv_nsec = 0;
614 }
615
616 read_boot_clock(&boot);
617 if (!timespec_valid_strict(&boot)) {
618 pr_warn("WARNING: Boot clock returned invalid value!\n"
619 " Check your CMOS/BIOS settings.\n");
620 boot.tv_sec = 0;
621 boot.tv_nsec = 0;
622 }
623
624 seqlock_init(&timekeeper.lock);
625
626 ntp_init();
627
628 write_seqlock_irqsave(&timekeeper.lock, flags);
629 clock = clocksource_default_clock();
630 if (clock->enable)
631 clock->enable(clock);
632 timekeeper_setup_internals(clock);
633
634 timekeeper.xtime.tv_sec = now.tv_sec;
635 timekeeper.xtime.tv_nsec = now.tv_nsec;
636 timekeeper.raw_time.tv_sec = 0;
637 timekeeper.raw_time.tv_nsec = 0;
638 if (boot.tv_sec == 0 && boot.tv_nsec == 0) {
639 boot.tv_sec = timekeeper.xtime.tv_sec;
640 boot.tv_nsec = timekeeper.xtime.tv_nsec;
641 }
642 set_normalized_timespec(&timekeeper.wall_to_monotonic,
643 -boot.tv_sec, -boot.tv_nsec);
644 update_rt_offset();
645 timekeeper.total_sleep_time.tv_sec = 0;
646 timekeeper.total_sleep_time.tv_nsec = 0;
647 write_sequnlock_irqrestore(&timekeeper.lock, flags);
648}
649
650/* time in seconds when suspend began */
651static struct timespec timekeeping_suspend_time;
652
653static void update_sleep_time(struct timespec t)
654{
655 timekeeper.total_sleep_time = t;
656 timekeeper.offs_boot = timespec_to_ktime(t);
657}
658
659/**
660 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
661 * @delta: pointer to a timespec delta value
662 *
663 * Takes a timespec offset measuring a suspend interval and properly
664 * adds the sleep offset to the timekeeping variables.
665 */
666static void __timekeeping_inject_sleeptime(struct timespec *delta)
667{
668 if (!timespec_valid_strict(delta)) {
669 printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
670 "sleep delta value!\n");
671 return;
672 }
673
674 timekeeper.xtime = timespec_add(timekeeper.xtime, *delta);
675 timekeeper.wall_to_monotonic =
676 timespec_sub(timekeeper.wall_to_monotonic, *delta);
677 update_sleep_time(timespec_add(timekeeper.total_sleep_time, *delta));
678}
679
680
681/**
682 * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
683 * @delta: pointer to a timespec delta value
684 *
685 * This hook is for architectures that cannot support read_persistent_clock
686 * because their RTC/persistent clock is only accessible when irqs are enabled.
687 *
688 * This function should only be called by rtc_resume(), and allows
689 * a suspend offset to be injected into the timekeeping values.
690 */
691void timekeeping_inject_sleeptime(struct timespec *delta)
692{
693 unsigned long flags;
694 struct timespec ts;
695
696 /* Make sure we don't set the clock twice */
697 read_persistent_clock(&ts);
698 if (!(ts.tv_sec == 0 && ts.tv_nsec == 0))
699 return;
700
701 write_seqlock_irqsave(&timekeeper.lock, flags);
702
703 timekeeping_forward_now();
704
705 __timekeeping_inject_sleeptime(delta);
706
707 timekeeping_update(true);
708
709 write_sequnlock_irqrestore(&timekeeper.lock, flags);
710
711 /* signal hrtimers about time change */
712 clock_was_set();
713}
714
715
716/**
717 * timekeeping_resume - Resumes the generic timekeeping subsystem.
718 *
719 * This is for the generic clocksource timekeeping.
720 * xtime/wall_to_monotonic/jiffies/etc are
721 * still managed by arch specific suspend/resume code.
722 */
723static void timekeeping_resume(void)
724{
725 unsigned long flags;
726 struct timespec ts;
727
728 read_persistent_clock(&ts);
729
730 clocksource_resume();
731
732 write_seqlock_irqsave(&timekeeper.lock, flags);
733
734 if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {
735 ts = timespec_sub(ts, timekeeping_suspend_time);
736 __timekeeping_inject_sleeptime(&ts);
737 }
738 /* re-base the last cycle value */
739 timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
740 timekeeper.ntp_error = 0;
741 timekeeping_suspended = 0;
742 timekeeping_update(false);
743 write_sequnlock_irqrestore(&timekeeper.lock, flags);
744
745 touch_softlockup_watchdog();
746
747 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
748
749 /* Resume hrtimers */
750 hrtimers_resume();
751}
752
753static int timekeeping_suspend(void)
754{
755 unsigned long flags;
756 struct timespec delta, delta_delta;
757 static struct timespec old_delta;
758
759 read_persistent_clock(&timekeeping_suspend_time);
760
761 write_seqlock_irqsave(&timekeeper.lock, flags);
762 timekeeping_forward_now();
763 timekeeping_suspended = 1;
764
765 /*
766 * To avoid drift caused by repeated suspend/resumes,
767 * which each can add ~1 second drift error,
768 * try to compensate so the difference in system time
769 * and persistent_clock time stays close to constant.
770 */
771 delta = timespec_sub(timekeeper.xtime, timekeeping_suspend_time);
772 delta_delta = timespec_sub(delta, old_delta);
773 if (abs(delta_delta.tv_sec) >= 2) {
774 /*
775 * if delta_delta is too large, assume time correction
776 * has occured and set old_delta to the current delta.
777 */
778 old_delta = delta;
779 } else {
780 /* Otherwise try to adjust old_system to compensate */
781 timekeeping_suspend_time =
782 timespec_add(timekeeping_suspend_time, delta_delta);
783 }
784 write_sequnlock_irqrestore(&timekeeper.lock, flags);
785
786 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
787 clocksource_suspend();
788
789 return 0;
790}
791
792/* sysfs resume/suspend bits for timekeeping */
793static struct syscore_ops timekeeping_syscore_ops = {
794 .resume = timekeeping_resume,
795 .suspend = timekeeping_suspend,
796};
797
798static int __init timekeeping_init_ops(void)
799{
800 register_syscore_ops(&timekeeping_syscore_ops);
801 return 0;
802}
803
804device_initcall(timekeeping_init_ops);
805
806/*
807 * If the error is already larger, we look ahead even further
808 * to compensate for late or lost adjustments.
809 */
810static __always_inline int timekeeping_bigadjust(s64 error, s64 *interval,
811 s64 *offset)
812{
813 s64 tick_error, i;
814 u32 look_ahead, adj;
815 s32 error2, mult;
816
817 /*
818 * Use the current error value to determine how much to look ahead.
819 * The larger the error the slower we adjust for it to avoid problems
820 * with losing too many ticks, otherwise we would overadjust and
821 * produce an even larger error. The smaller the adjustment the
822 * faster we try to adjust for it, as lost ticks can do less harm
823 * here. This is tuned so that an error of about 1 msec is adjusted
824 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
825 */
826 error2 = timekeeper.ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
827 error2 = abs(error2);
828 for (look_ahead = 0; error2 > 0; look_ahead++)
829 error2 >>= 2;
830
831 /*
832 * Now calculate the error in (1 << look_ahead) ticks, but first
833 * remove the single look ahead already included in the error.
834 */
835 tick_error = ntp_tick_length() >> (timekeeper.ntp_error_shift + 1);
836 tick_error -= timekeeper.xtime_interval >> 1;
837 error = ((error - tick_error) >> look_ahead) + tick_error;
838
839 /* Finally calculate the adjustment shift value. */
840 i = *interval;
841 mult = 1;
842 if (error < 0) {
843 error = -error;
844 *interval = -*interval;
845 *offset = -*offset;
846 mult = -1;
847 }
848 for (adj = 0; error > i; adj++)
849 error >>= 1;
850
851 *interval <<= adj;
852 *offset <<= adj;
853 return mult << adj;
854}
855
856/*
857 * Adjust the multiplier to reduce the error value,
858 * this is optimized for the most common adjustments of -1,0,1,
859 * for other values we can do a bit more work.
860 */
861static void timekeeping_adjust(s64 offset)
862{
863 s64 error, interval = timekeeper.cycle_interval;
864 int adj;
865
866 /*
867 * The point of this is to check if the error is greater than half
868 * an interval.
869 *
870 * First we shift it down from NTP_SHIFT to clocksource->shifted nsecs.
871 *
872 * Note we subtract one in the shift, so that error is really error*2.
873 * This "saves" dividing(shifting) interval twice, but keeps the
874 * (error > interval) comparison as still measuring if error is
875 * larger than half an interval.
876 *
877 * Note: It does not "save" on aggravation when reading the code.
878 */
879 error = timekeeper.ntp_error >> (timekeeper.ntp_error_shift - 1);
880 if (error > interval) {
881 /*
882 * We now divide error by 4(via shift), which checks if
883 * the error is greater than twice the interval.
884 * If it is greater, we need a bigadjust, if its smaller,
885 * we can adjust by 1.
886 */
887 error >>= 2;
888 /*
889 * XXX - In update_wall_time, we round up to the next
890 * nanosecond, and store the amount rounded up into
891 * the error. This causes the likely below to be unlikely.
892 *
893 * The proper fix is to avoid rounding up by using
894 * the high precision timekeeper.xtime_nsec instead of
895 * xtime.tv_nsec everywhere. Fixing this will take some
896 * time.
897 */
898 if (likely(error <= interval))
899 adj = 1;
900 else
901 adj = timekeeping_bigadjust(error, &interval, &offset);
902 } else if (error < -interval) {
903 /* See comment above, this is just switched for the negative */
904 error >>= 2;
905 if (likely(error >= -interval)) {
906 adj = -1;
907 interval = -interval;
908 offset = -offset;
909 } else
910 adj = timekeeping_bigadjust(error, &interval, &offset);
911 } else /* No adjustment needed */
912 return;
913
914 if (unlikely(timekeeper.clock->maxadj &&
915 (timekeeper.mult + adj >
916 timekeeper.clock->mult + timekeeper.clock->maxadj))) {
917 printk_once(KERN_WARNING
918 "Adjusting %s more than 11%% (%ld vs %ld)\n",
919 timekeeper.clock->name, (long)timekeeper.mult + adj,
920 (long)timekeeper.clock->mult +
921 timekeeper.clock->maxadj);
922 }
923 /*
924 * So the following can be confusing.
925 *
926 * To keep things simple, lets assume adj == 1 for now.
927 *
928 * When adj != 1, remember that the interval and offset values
929 * have been appropriately scaled so the math is the same.
930 *
931 * The basic idea here is that we're increasing the multiplier
932 * by one, this causes the xtime_interval to be incremented by
933 * one cycle_interval. This is because:
934 * xtime_interval = cycle_interval * mult
935 * So if mult is being incremented by one:
936 * xtime_interval = cycle_interval * (mult + 1)
937 * Its the same as:
938 * xtime_interval = (cycle_interval * mult) + cycle_interval
939 * Which can be shortened to:
940 * xtime_interval += cycle_interval
941 *
942 * So offset stores the non-accumulated cycles. Thus the current
943 * time (in shifted nanoseconds) is:
944 * now = (offset * adj) + xtime_nsec
945 * Now, even though we're adjusting the clock frequency, we have
946 * to keep time consistent. In other words, we can't jump back
947 * in time, and we also want to avoid jumping forward in time.
948 *
949 * So given the same offset value, we need the time to be the same
950 * both before and after the freq adjustment.
951 * now = (offset * adj_1) + xtime_nsec_1
952 * now = (offset * adj_2) + xtime_nsec_2
953 * So:
954 * (offset * adj_1) + xtime_nsec_1 =
955 * (offset * adj_2) + xtime_nsec_2
956 * And we know:
957 * adj_2 = adj_1 + 1
958 * So:
959 * (offset * adj_1) + xtime_nsec_1 =
960 * (offset * (adj_1+1)) + xtime_nsec_2
961 * (offset * adj_1) + xtime_nsec_1 =
962 * (offset * adj_1) + offset + xtime_nsec_2
963 * Canceling the sides:
964 * xtime_nsec_1 = offset + xtime_nsec_2
965 * Which gives us:
966 * xtime_nsec_2 = xtime_nsec_1 - offset
967 * Which simplfies to:
968 * xtime_nsec -= offset
969 *
970 * XXX - TODO: Doc ntp_error calculation.
971 */
972 timekeeper.mult += adj;
973 timekeeper.xtime_interval += interval;
974 timekeeper.xtime_nsec -= offset;
975 timekeeper.ntp_error -= (interval - offset) <<
976 timekeeper.ntp_error_shift;
977}
978
979
980/**
981 * logarithmic_accumulation - shifted accumulation of cycles
982 *
983 * This functions accumulates a shifted interval of cycles into
984 * into a shifted interval nanoseconds. Allows for O(log) accumulation
985 * loop.
986 *
987 * Returns the unconsumed cycles.
988 */
989static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
990{
991 u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift;
992 u64 raw_nsecs;
993
994 /* If the offset is smaller than a shifted interval, do nothing */
995 if (offset < timekeeper.cycle_interval<<shift)
996 return offset;
997
998 /* Accumulate one shifted interval */
999 offset -= timekeeper.cycle_interval << shift;
1000 timekeeper.clock->cycle_last += timekeeper.cycle_interval << shift;
1001
1002 timekeeper.xtime_nsec += timekeeper.xtime_interval << shift;
1003 while (timekeeper.xtime_nsec >= nsecps) {
1004 int leap;
1005 timekeeper.xtime_nsec -= nsecps;
1006 timekeeper.xtime.tv_sec++;
1007 leap = second_overflow(timekeeper.xtime.tv_sec);
1008 timekeeper.xtime.tv_sec += leap;
1009 timekeeper.wall_to_monotonic.tv_sec -= leap;
1010 if (leap)
1011 clock_was_set_delayed();
1012 }
1013
1014 /* Accumulate raw time */
1015 raw_nsecs = timekeeper.raw_interval << shift;
1016 raw_nsecs += timekeeper.raw_time.tv_nsec;
1017 if (raw_nsecs >= NSEC_PER_SEC) {
1018 u64 raw_secs = raw_nsecs;
1019 raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
1020 timekeeper.raw_time.tv_sec += raw_secs;
1021 }
1022 timekeeper.raw_time.tv_nsec = raw_nsecs;
1023
1024 /* Accumulate error between NTP and clock interval */
1025 timekeeper.ntp_error += ntp_tick_length() << shift;
1026 timekeeper.ntp_error -=
1027 (timekeeper.xtime_interval + timekeeper.xtime_remainder) <<
1028 (timekeeper.ntp_error_shift + shift);
1029
1030 return offset;
1031}
1032
1033
1034/**
1035 * update_wall_time - Uses the current clocksource to increment the wall time
1036 *
1037 */
1038static void update_wall_time(void)
1039{
1040 struct clocksource *clock;
1041 cycle_t offset;
1042 int shift = 0, maxshift;
1043 unsigned long flags;
1044
1045 write_seqlock_irqsave(&timekeeper.lock, flags);
1046
1047 /* Make sure we're fully resumed: */
1048 if (unlikely(timekeeping_suspended))
1049 goto out;
1050
1051 clock = timekeeper.clock;
1052
1053#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1054 offset = timekeeper.cycle_interval;
1055#else
1056 offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
1057#endif
1058 /* Check if there's really nothing to do */
1059 if (offset < timekeeper.cycle_interval)
1060 goto out;
1061
1062 timekeeper.xtime_nsec = (s64)timekeeper.xtime.tv_nsec <<
1063 timekeeper.shift;
1064
1065 /*
1066 * With NO_HZ we may have to accumulate many cycle_intervals
1067 * (think "ticks") worth of time at once. To do this efficiently,
1068 * we calculate the largest doubling multiple of cycle_intervals
1069 * that is smaller than the offset. We then accumulate that
1070 * chunk in one go, and then try to consume the next smaller
1071 * doubled multiple.
1072 */
1073 shift = ilog2(offset) - ilog2(timekeeper.cycle_interval);
1074 shift = max(0, shift);
1075 /* Bound shift to one less than what overflows tick_length */
1076 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
1077 shift = min(shift, maxshift);
1078 while (offset >= timekeeper.cycle_interval) {
1079 offset = logarithmic_accumulation(offset, shift);
1080 if(offset < timekeeper.cycle_interval<<shift)
1081 shift--;
1082 }
1083
1084 /* correct the clock when NTP error is too big */
1085 timekeeping_adjust(offset);
1086
1087 /*
1088 * Since in the loop above, we accumulate any amount of time
1089 * in xtime_nsec over a second into xtime.tv_sec, its possible for
1090 * xtime_nsec to be fairly small after the loop. Further, if we're
1091 * slightly speeding the clocksource up in timekeeping_adjust(),
1092 * its possible the required corrective factor to xtime_nsec could
1093 * cause it to underflow.
1094 *
1095 * Now, we cannot simply roll the accumulated second back, since
1096 * the NTP subsystem has been notified via second_overflow. So
1097 * instead we push xtime_nsec forward by the amount we underflowed,
1098 * and add that amount into the error.
1099 *
1100 * We'll correct this error next time through this function, when
1101 * xtime_nsec is not as small.
1102 */
1103 if (unlikely((s64)timekeeper.xtime_nsec < 0)) {
1104 s64 neg = -(s64)timekeeper.xtime_nsec;
1105 timekeeper.xtime_nsec = 0;
1106 timekeeper.ntp_error += neg << timekeeper.ntp_error_shift;
1107 }
1108
1109
1110 /*
1111 * Store full nanoseconds into xtime after rounding it up and
1112 * add the remainder to the error difference.
1113 */
1114 timekeeper.xtime.tv_nsec = ((s64)timekeeper.xtime_nsec >>
1115 timekeeper.shift) + 1;
1116 timekeeper.xtime_nsec -= (s64)timekeeper.xtime.tv_nsec <<
1117 timekeeper.shift;
1118 timekeeper.ntp_error += timekeeper.xtime_nsec <<
1119 timekeeper.ntp_error_shift;
1120
1121 /*
1122 * Finally, make sure that after the rounding
1123 * xtime.tv_nsec isn't larger than NSEC_PER_SEC
1124 */
1125 if (unlikely(timekeeper.xtime.tv_nsec >= NSEC_PER_SEC)) {
1126 int leap;
1127 timekeeper.xtime.tv_nsec -= NSEC_PER_SEC;
1128 timekeeper.xtime.tv_sec++;
1129 leap = second_overflow(timekeeper.xtime.tv_sec);
1130 timekeeper.xtime.tv_sec += leap;
1131 timekeeper.wall_to_monotonic.tv_sec -= leap;
1132 if (leap)
1133 clock_was_set_delayed();
1134 }
1135
1136 timekeeping_update(false);
1137
1138out:
1139 write_sequnlock_irqrestore(&timekeeper.lock, flags);
1140
1141}
1142
1143/**
1144 * getboottime - Return the real time of system boot.
1145 * @ts: pointer to the timespec to be set
1146 *
1147 * Returns the wall-time of boot in a timespec.
1148 *
1149 * This is based on the wall_to_monotonic offset and the total suspend
1150 * time. Calls to settimeofday will affect the value returned (which
1151 * basically means that however wrong your real time clock is at boot time,
1152 * you get the right time here).
1153 */
1154void getboottime(struct timespec *ts)
1155{
1156 struct timespec boottime = {
1157 .tv_sec = timekeeper.wall_to_monotonic.tv_sec +
1158 timekeeper.total_sleep_time.tv_sec,
1159 .tv_nsec = timekeeper.wall_to_monotonic.tv_nsec +
1160 timekeeper.total_sleep_time.tv_nsec
1161 };
1162
1163 set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
1164}
1165EXPORT_SYMBOL_GPL(getboottime);
1166
1167
1168/**
1169 * get_monotonic_boottime - Returns monotonic time since boot
1170 * @ts: pointer to the timespec to be set
1171 *
1172 * Returns the monotonic time since boot in a timespec.
1173 *
1174 * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
1175 * includes the time spent in suspend.
1176 */
1177void get_monotonic_boottime(struct timespec *ts)
1178{
1179 struct timespec tomono, sleep;
1180 unsigned int seq;
1181 s64 nsecs;
1182
1183 WARN_ON(timekeeping_suspended);
1184
1185 do {
1186 seq = read_seqbegin(&timekeeper.lock);
1187 *ts = timekeeper.xtime;
1188 tomono = timekeeper.wall_to_monotonic;
1189 sleep = timekeeper.total_sleep_time;
1190 nsecs = timekeeping_get_ns();
1191
1192 } while (read_seqretry(&timekeeper.lock, seq));
1193
1194 set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec + sleep.tv_sec,
1195 ts->tv_nsec + tomono.tv_nsec + sleep.tv_nsec + nsecs);
1196}
1197EXPORT_SYMBOL_GPL(get_monotonic_boottime);
1198
1199/**
1200 * ktime_get_boottime - Returns monotonic time since boot in a ktime
1201 *
1202 * Returns the monotonic time since boot in a ktime
1203 *
1204 * This is similar to CLOCK_MONTONIC/ktime_get, but also
1205 * includes the time spent in suspend.
1206 */
1207ktime_t ktime_get_boottime(void)
1208{
1209 struct timespec ts;
1210
1211 get_monotonic_boottime(&ts);
1212 return timespec_to_ktime(ts);
1213}
1214EXPORT_SYMBOL_GPL(ktime_get_boottime);
1215
1216/**
1217 * monotonic_to_bootbased - Convert the monotonic time to boot based.
1218 * @ts: pointer to the timespec to be converted
1219 */
1220void monotonic_to_bootbased(struct timespec *ts)
1221{
1222 *ts = timespec_add(*ts, timekeeper.total_sleep_time);
1223}
1224EXPORT_SYMBOL_GPL(monotonic_to_bootbased);
1225
1226unsigned long get_seconds(void)
1227{
1228 return timekeeper.xtime.tv_sec;
1229}
1230EXPORT_SYMBOL(get_seconds);
1231
1232struct timespec __current_kernel_time(void)
1233{
1234 return timekeeper.xtime;
1235}
1236
1237struct timespec current_kernel_time(void)
1238{
1239 struct timespec now;
1240 unsigned long seq;
1241
1242 do {
1243 seq = read_seqbegin(&timekeeper.lock);
1244
1245 now = timekeeper.xtime;
1246 } while (read_seqretry(&timekeeper.lock, seq));
1247
1248 return now;
1249}
1250EXPORT_SYMBOL(current_kernel_time);
1251
1252struct timespec get_monotonic_coarse(void)
1253{
1254 struct timespec now, mono;
1255 unsigned long seq;
1256
1257 do {
1258 seq = read_seqbegin(&timekeeper.lock);
1259
1260 now = timekeeper.xtime;
1261 mono = timekeeper.wall_to_monotonic;
1262 } while (read_seqretry(&timekeeper.lock, seq));
1263
1264 set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
1265 now.tv_nsec + mono.tv_nsec);
1266 return now;
1267}
1268
1269/*
1270 * The 64-bit jiffies value is not atomic - you MUST NOT read it
1271 * without sampling the sequence number in xtime_lock.
1272 * jiffies is defined in the linker script...
1273 */
1274void do_timer(unsigned long ticks)
1275{
1276 jiffies_64 += ticks;
1277 update_wall_time();
1278 calc_global_load(ticks);
1279}
1280
1281/**
1282 * get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic,
1283 * and sleep offsets.
1284 * @xtim: pointer to timespec to be set with xtime
1285 * @wtom: pointer to timespec to be set with wall_to_monotonic
1286 * @sleep: pointer to timespec to be set with time in suspend
1287 */
1288void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
1289 struct timespec *wtom, struct timespec *sleep)
1290{
1291 unsigned long seq;
1292
1293 do {
1294 seq = read_seqbegin(&timekeeper.lock);
1295 *xtim = timekeeper.xtime;
1296 *wtom = timekeeper.wall_to_monotonic;
1297 *sleep = timekeeper.total_sleep_time;
1298 } while (read_seqretry(&timekeeper.lock, seq));
1299}
1300
1301#ifdef CONFIG_HIGH_RES_TIMERS
1302/**
1303 * ktime_get_update_offsets - hrtimer helper
1304 * @offs_real: pointer to storage for monotonic -> realtime offset
1305 * @offs_boot: pointer to storage for monotonic -> boottime offset
1306 *
1307 * Returns current monotonic time and updates the offsets
1308 * Called from hrtimer_interupt() or retrigger_next_event()
1309 */
1310ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot)
1311{
1312 ktime_t now;
1313 unsigned int seq;
1314 u64 secs, nsecs;
1315
1316 do {
1317 seq = read_seqbegin(&timekeeper.lock);
1318
1319 secs = timekeeper.xtime.tv_sec;
1320 nsecs = timekeeper.xtime.tv_nsec;
1321 nsecs += timekeeping_get_ns();
1322 /* If arch requires, add in gettimeoffset() */
1323 nsecs += arch_gettimeoffset();
1324
1325 *offs_real = timekeeper.offs_real;
1326 *offs_boot = timekeeper.offs_boot;
1327 } while (read_seqretry(&timekeeper.lock, seq));
1328
1329 now = ktime_add_ns(ktime_set(secs, 0), nsecs);
1330 now = ktime_sub(now, *offs_real);
1331 return now;
1332}
1333#endif
1334
1335/**
1336 * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
1337 */
1338ktime_t ktime_get_monotonic_offset(void)
1339{
1340 unsigned long seq;
1341 struct timespec wtom;
1342
1343 do {
1344 seq = read_seqbegin(&timekeeper.lock);
1345 wtom = timekeeper.wall_to_monotonic;
1346 } while (read_seqretry(&timekeeper.lock, seq));
1347
1348 return timespec_to_ktime(wtom);
1349}
1350EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset);
1351
1352
1353/**
1354 * xtime_update() - advances the timekeeping infrastructure
1355 * @ticks: number of ticks, that have elapsed since the last call.
1356 *
1357 * Must be called with interrupts disabled.
1358 */
1359void xtime_update(unsigned long ticks)
1360{
1361 write_seqlock(&xtime_lock);
1362 do_timer(ticks);
1363 write_sequnlock(&xtime_lock);
1364}