projects/linux·blob v3.13 · refs

1742 lines · 45.4 KiB

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/timekeeper_internal.h>
12#include <linux/module.h>
13#include <linux/interrupt.h>
14#include <linux/percpu.h>
15#include <linux/init.h>
16#include <linux/mm.h>
17#include <linux/sched.h>
18#include <linux/syscore_ops.h>
19#include <linux/clocksource.h>
20#include <linux/jiffies.h>
21#include <linux/time.h>
22#include <linux/tick.h>
23#include <linux/stop_machine.h>
24#include <linux/pvclock_gtod.h>
25
26#include "tick-internal.h"
27#include "ntp_internal.h"
28#include "timekeeping_internal.h"
29
30#define TK_CLEAR_NTP (1 << 0)
31#define TK_MIRROR (1 << 1)
32#define TK_CLOCK_WAS_SET (1 << 2)
33
34static struct timekeeper timekeeper;
35static DEFINE_RAW_SPINLOCK(timekeeper_lock);
36static seqcount_t timekeeper_seq;
37static struct timekeeper shadow_timekeeper;
38
39/* flag for if timekeeping is suspended */
40int __read_mostly timekeeping_suspended;
41
42/* Flag for if there is a persistent clock on this platform */
43bool __read_mostly persistent_clock_exist = false;
44
45static inline void tk_normalize_xtime(struct timekeeper *tk)
46{
47 while (tk->xtime_nsec >= ((u64)NSEC_PER_SEC << tk->shift)) {
48 tk->xtime_nsec -= (u64)NSEC_PER_SEC << tk->shift;
49 tk->xtime_sec++;
50 }
51}
52
53static void tk_set_xtime(struct timekeeper *tk, const struct timespec *ts)
54{
55 tk->xtime_sec = ts->tv_sec;
56 tk->xtime_nsec = (u64)ts->tv_nsec << tk->shift;
57}
58
59static void tk_xtime_add(struct timekeeper *tk, const struct timespec *ts)
60{
61 tk->xtime_sec += ts->tv_sec;
62 tk->xtime_nsec += (u64)ts->tv_nsec << tk->shift;
63 tk_normalize_xtime(tk);
64}
65
66static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec wtm)
67{
68 struct timespec tmp;
69
70 /*
71 * Verify consistency of: offset_real = -wall_to_monotonic
72 * before modifying anything
73 */
74 set_normalized_timespec(&tmp, -tk->wall_to_monotonic.tv_sec,
75 -tk->wall_to_monotonic.tv_nsec);
76 WARN_ON_ONCE(tk->offs_real.tv64 != timespec_to_ktime(tmp).tv64);
77 tk->wall_to_monotonic = wtm;
78 set_normalized_timespec(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
79 tk->offs_real = timespec_to_ktime(tmp);
80 tk->offs_tai = ktime_sub(tk->offs_real, ktime_set(tk->tai_offset, 0));
81}
82
83static void tk_set_sleep_time(struct timekeeper *tk, struct timespec t)
84{
85 /* Verify consistency before modifying */
86 WARN_ON_ONCE(tk->offs_boot.tv64 != timespec_to_ktime(tk->total_sleep_time).tv64);
87
88 tk->total_sleep_time = t;
89 tk->offs_boot = timespec_to_ktime(t);
90}
91
92/**
93 * timekeeper_setup_internals - Set up internals to use clocksource clock.
94 *
95 * @clock: Pointer to clocksource.
96 *
97 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
98 * pair and interval request.
99 *
100 * Unless you're the timekeeping code, you should not be using this!
101 */
102static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
103{
104 cycle_t interval;
105 u64 tmp, ntpinterval;
106 struct clocksource *old_clock;
107
108 old_clock = tk->clock;
109 tk->clock = clock;
110 tk->cycle_last = clock->cycle_last = clock->read(clock);
111
112 /* Do the ns -> cycle conversion first, using original mult */
113 tmp = NTP_INTERVAL_LENGTH;
114 tmp <<= clock->shift;
115 ntpinterval = tmp;
116 tmp += clock->mult/2;
117 do_div(tmp, clock->mult);
118 if (tmp == 0)
119 tmp = 1;
120
121 interval = (cycle_t) tmp;
122 tk->cycle_interval = interval;
123
124 /* Go back from cycles -> shifted ns */
125 tk->xtime_interval = (u64) interval * clock->mult;
126 tk->xtime_remainder = ntpinterval - tk->xtime_interval;
127 tk->raw_interval =
128 ((u64) interval * clock->mult) >> clock->shift;
129
130 /* if changing clocks, convert xtime_nsec shift units */
131 if (old_clock) {
132 int shift_change = clock->shift - old_clock->shift;
133 if (shift_change < 0)
134 tk->xtime_nsec >>= -shift_change;
135 else
136 tk->xtime_nsec <<= shift_change;
137 }
138 tk->shift = clock->shift;
139
140 tk->ntp_error = 0;
141 tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
142
143 /*
144 * The timekeeper keeps its own mult values for the currently
145 * active clocksource. These value will be adjusted via NTP
146 * to counteract clock drifting.
147 */
148 tk->mult = clock->mult;
149}
150
151/* Timekeeper helper functions. */
152
153#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
154u32 (*arch_gettimeoffset)(void);
155
156u32 get_arch_timeoffset(void)
157{
158 if (likely(arch_gettimeoffset))
159 return arch_gettimeoffset();
160 return 0;
161}
162#else
163static inline u32 get_arch_timeoffset(void) { return 0; }
164#endif
165
166static inline s64 timekeeping_get_ns(struct timekeeper *tk)
167{
168 cycle_t cycle_now, cycle_delta;
169 struct clocksource *clock;
170 s64 nsec;
171
172 /* read clocksource: */
173 clock = tk->clock;
174 cycle_now = clock->read(clock);
175
176 /* calculate the delta since the last update_wall_time: */
177 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
178
179 nsec = cycle_delta * tk->mult + tk->xtime_nsec;
180 nsec >>= tk->shift;
181
182 /* If arch requires, add in get_arch_timeoffset() */
183 return nsec + get_arch_timeoffset();
184}
185
186static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk)
187{
188 cycle_t cycle_now, cycle_delta;
189 struct clocksource *clock;
190 s64 nsec;
191
192 /* read clocksource: */
193 clock = tk->clock;
194 cycle_now = clock->read(clock);
195
196 /* calculate the delta since the last update_wall_time: */
197 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
198
199 /* convert delta to nanoseconds. */
200 nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
201
202 /* If arch requires, add in get_arch_timeoffset() */
203 return nsec + get_arch_timeoffset();
204}
205
206static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
207
208static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
209{
210 raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
211}
212
213/**
214 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
215 */
216int pvclock_gtod_register_notifier(struct notifier_block *nb)
217{
218 struct timekeeper *tk = &timekeeper;
219 unsigned long flags;
220 int ret;
221
222 raw_spin_lock_irqsave(&timekeeper_lock, flags);
223 ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
224 update_pvclock_gtod(tk, true);
225 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
226
227 return ret;
228}
229EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
230
231/**
232 * pvclock_gtod_unregister_notifier - unregister a pvclock
233 * timedata update listener
234 */
235int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
236{
237 unsigned long flags;
238 int ret;
239
240 raw_spin_lock_irqsave(&timekeeper_lock, flags);
241 ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
242 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
243
244 return ret;
245}
246EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
247
248/* must hold timekeeper_lock */
249static void timekeeping_update(struct timekeeper *tk, unsigned int action)
250{
251 if (action & TK_CLEAR_NTP) {
252 tk->ntp_error = 0;
253 ntp_clear();
254 }
255 update_vsyscall(tk);
256 update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
257
258 if (action & TK_MIRROR)
259 memcpy(&shadow_timekeeper, &timekeeper, sizeof(timekeeper));
260}
261
262/**
263 * timekeeping_forward_now - update clock to the current time
264 *
265 * Forward the current clock to update its state since the last call to
266 * update_wall_time(). This is useful before significant clock changes,
267 * as it avoids having to deal with this time offset explicitly.
268 */
269static void timekeeping_forward_now(struct timekeeper *tk)
270{
271 cycle_t cycle_now, cycle_delta;
272 struct clocksource *clock;
273 s64 nsec;
274
275 clock = tk->clock;
276 cycle_now = clock->read(clock);
277 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
278 tk->cycle_last = clock->cycle_last = cycle_now;
279
280 tk->xtime_nsec += cycle_delta * tk->mult;
281
282 /* If arch requires, add in get_arch_timeoffset() */
283 tk->xtime_nsec += (u64)get_arch_timeoffset() << tk->shift;
284
285 tk_normalize_xtime(tk);
286
287 nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
288 timespec_add_ns(&tk->raw_time, nsec);
289}
290
291/**
292 * __getnstimeofday - Returns the time of day in a timespec.
293 * @ts: pointer to the timespec to be set
294 *
295 * Updates the time of day in the timespec.
296 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
297 */
298int __getnstimeofday(struct timespec *ts)
299{
300 struct timekeeper *tk = &timekeeper;
301 unsigned long seq;
302 s64 nsecs = 0;
303
304 do {
305 seq = read_seqcount_begin(&timekeeper_seq);
306
307 ts->tv_sec = tk->xtime_sec;
308 nsecs = timekeeping_get_ns(tk);
309
310 } while (read_seqcount_retry(&timekeeper_seq, seq));
311
312 ts->tv_nsec = 0;
313 timespec_add_ns(ts, nsecs);
314
315 /*
316 * Do not bail out early, in case there were callers still using
317 * the value, even in the face of the WARN_ON.
318 */
319 if (unlikely(timekeeping_suspended))
320 return -EAGAIN;
321 return 0;
322}
323EXPORT_SYMBOL(__getnstimeofday);
324
325/**
326 * getnstimeofday - Returns the time of day in a timespec.
327 * @ts: pointer to the timespec to be set
328 *
329 * Returns the time of day in a timespec (WARN if suspended).
330 */
331void getnstimeofday(struct timespec *ts)
332{
333 WARN_ON(__getnstimeofday(ts));
334}
335EXPORT_SYMBOL(getnstimeofday);
336
337ktime_t ktime_get(void)
338{
339 struct timekeeper *tk = &timekeeper;
340 unsigned int seq;
341 s64 secs, nsecs;
342
343 WARN_ON(timekeeping_suspended);
344
345 do {
346 seq = read_seqcount_begin(&timekeeper_seq);
347 secs = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
348 nsecs = timekeeping_get_ns(tk) + tk->wall_to_monotonic.tv_nsec;
349
350 } while (read_seqcount_retry(&timekeeper_seq, seq));
351 /*
352 * Use ktime_set/ktime_add_ns to create a proper ktime on
353 * 32-bit architectures without CONFIG_KTIME_SCALAR.
354 */
355 return ktime_add_ns(ktime_set(secs, 0), nsecs);
356}
357EXPORT_SYMBOL_GPL(ktime_get);
358
359/**
360 * ktime_get_ts - get the monotonic clock in timespec format
361 * @ts: pointer to timespec variable
362 *
363 * The function calculates the monotonic clock from the realtime
364 * clock and the wall_to_monotonic offset and stores the result
365 * in normalized timespec format in the variable pointed to by @ts.
366 */
367void ktime_get_ts(struct timespec *ts)
368{
369 struct timekeeper *tk = &timekeeper;
370 struct timespec tomono;
371 s64 nsec;
372 unsigned int seq;
373
374 WARN_ON(timekeeping_suspended);
375
376 do {
377 seq = read_seqcount_begin(&timekeeper_seq);
378 ts->tv_sec = tk->xtime_sec;
379 nsec = timekeeping_get_ns(tk);
380 tomono = tk->wall_to_monotonic;
381
382 } while (read_seqcount_retry(&timekeeper_seq, seq));
383
384 ts->tv_sec += tomono.tv_sec;
385 ts->tv_nsec = 0;
386 timespec_add_ns(ts, nsec + tomono.tv_nsec);
387}
388EXPORT_SYMBOL_GPL(ktime_get_ts);
389
390
391/**
392 * timekeeping_clocktai - Returns the TAI time of day in a timespec
393 * @ts: pointer to the timespec to be set
394 *
395 * Returns the time of day in a timespec.
396 */
397void timekeeping_clocktai(struct timespec *ts)
398{
399 struct timekeeper *tk = &timekeeper;
400 unsigned long seq;
401 u64 nsecs;
402
403 WARN_ON(timekeeping_suspended);
404
405 do {
406 seq = read_seqcount_begin(&timekeeper_seq);
407
408 ts->tv_sec = tk->xtime_sec + tk->tai_offset;
409 nsecs = timekeeping_get_ns(tk);
410
411 } while (read_seqcount_retry(&timekeeper_seq, seq));
412
413 ts->tv_nsec = 0;
414 timespec_add_ns(ts, nsecs);
415
416}
417EXPORT_SYMBOL(timekeeping_clocktai);
418
419
420/**
421 * ktime_get_clocktai - Returns the TAI time of day in a ktime
422 *
423 * Returns the time of day in a ktime.
424 */
425ktime_t ktime_get_clocktai(void)
426{
427 struct timespec ts;
428
429 timekeeping_clocktai(&ts);
430 return timespec_to_ktime(ts);
431}
432EXPORT_SYMBOL(ktime_get_clocktai);
433
434#ifdef CONFIG_NTP_PPS
435
436/**
437 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
438 * @ts_raw: pointer to the timespec to be set to raw monotonic time
439 * @ts_real: pointer to the timespec to be set to the time of day
440 *
441 * This function reads both the time of day and raw monotonic time at the
442 * same time atomically and stores the resulting timestamps in timespec
443 * format.
444 */
445void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
446{
447 struct timekeeper *tk = &timekeeper;
448 unsigned long seq;
449 s64 nsecs_raw, nsecs_real;
450
451 WARN_ON_ONCE(timekeeping_suspended);
452
453 do {
454 seq = read_seqcount_begin(&timekeeper_seq);
455
456 *ts_raw = tk->raw_time;
457 ts_real->tv_sec = tk->xtime_sec;
458 ts_real->tv_nsec = 0;
459
460 nsecs_raw = timekeeping_get_ns_raw(tk);
461 nsecs_real = timekeeping_get_ns(tk);
462
463 } while (read_seqcount_retry(&timekeeper_seq, seq));
464
465 timespec_add_ns(ts_raw, nsecs_raw);
466 timespec_add_ns(ts_real, nsecs_real);
467}
468EXPORT_SYMBOL(getnstime_raw_and_real);
469
470#endif /* CONFIG_NTP_PPS */
471
472/**
473 * do_gettimeofday - Returns the time of day in a timeval
474 * @tv: pointer to the timeval to be set
475 *
476 * NOTE: Users should be converted to using getnstimeofday()
477 */
478void do_gettimeofday(struct timeval *tv)
479{
480 struct timespec now;
481
482 getnstimeofday(&now);
483 tv->tv_sec = now.tv_sec;
484 tv->tv_usec = now.tv_nsec/1000;
485}
486EXPORT_SYMBOL(do_gettimeofday);
487
488/**
489 * do_settimeofday - Sets the time of day
490 * @tv: pointer to the timespec variable containing the new time
491 *
492 * Sets the time of day to the new time and update NTP and notify hrtimers
493 */
494int do_settimeofday(const struct timespec *tv)
495{
496 struct timekeeper *tk = &timekeeper;
497 struct timespec ts_delta, xt;
498 unsigned long flags;
499
500 if (!timespec_valid_strict(tv))
501 return -EINVAL;
502
503 raw_spin_lock_irqsave(&timekeeper_lock, flags);
504 write_seqcount_begin(&timekeeper_seq);
505
506 timekeeping_forward_now(tk);
507
508 xt = tk_xtime(tk);
509 ts_delta.tv_sec = tv->tv_sec - xt.tv_sec;
510 ts_delta.tv_nsec = tv->tv_nsec - xt.tv_nsec;
511
512 tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, ts_delta));
513
514 tk_set_xtime(tk, tv);
515
516 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
517
518 write_seqcount_end(&timekeeper_seq);
519 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
520
521 /* signal hrtimers about time change */
522 clock_was_set();
523
524 return 0;
525}
526EXPORT_SYMBOL(do_settimeofday);
527
528/**
529 * timekeeping_inject_offset - Adds or subtracts from the current time.
530 * @tv: pointer to the timespec variable containing the offset
531 *
532 * Adds or subtracts an offset value from the current time.
533 */
534int timekeeping_inject_offset(struct timespec *ts)
535{
536 struct timekeeper *tk = &timekeeper;
537 unsigned long flags;
538 struct timespec tmp;
539 int ret = 0;
540
541 if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
542 return -EINVAL;
543
544 raw_spin_lock_irqsave(&timekeeper_lock, flags);
545 write_seqcount_begin(&timekeeper_seq);
546
547 timekeeping_forward_now(tk);
548
549 /* Make sure the proposed value is valid */
550 tmp = timespec_add(tk_xtime(tk), *ts);
551 if (!timespec_valid_strict(&tmp)) {
552 ret = -EINVAL;
553 goto error;
554 }
555
556 tk_xtime_add(tk, ts);
557 tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *ts));
558
559error: /* even if we error out, we forwarded the time, so call update */
560 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
561
562 write_seqcount_end(&timekeeper_seq);
563 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
564
565 /* signal hrtimers about time change */
566 clock_was_set();
567
568 return ret;
569}
570EXPORT_SYMBOL(timekeeping_inject_offset);
571
572
573/**
574 * timekeeping_get_tai_offset - Returns current TAI offset from UTC
575 *
576 */
577s32 timekeeping_get_tai_offset(void)
578{
579 struct timekeeper *tk = &timekeeper;
580 unsigned int seq;
581 s32 ret;
582
583 do {
584 seq = read_seqcount_begin(&timekeeper_seq);
585 ret = tk->tai_offset;
586 } while (read_seqcount_retry(&timekeeper_seq, seq));
587
588 return ret;
589}
590
591/**
592 * __timekeeping_set_tai_offset - Lock free worker function
593 *
594 */
595static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
596{
597 tk->tai_offset = tai_offset;
598 tk->offs_tai = ktime_sub(tk->offs_real, ktime_set(tai_offset, 0));
599}
600
601/**
602 * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
603 *
604 */
605void timekeeping_set_tai_offset(s32 tai_offset)
606{
607 struct timekeeper *tk = &timekeeper;
608 unsigned long flags;
609
610 raw_spin_lock_irqsave(&timekeeper_lock, flags);
611 write_seqcount_begin(&timekeeper_seq);
612 __timekeeping_set_tai_offset(tk, tai_offset);
613 write_seqcount_end(&timekeeper_seq);
614 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
615 clock_was_set();
616}
617
618/**
619 * change_clocksource - Swaps clocksources if a new one is available
620 *
621 * Accumulates current time interval and initializes new clocksource
622 */
623static int change_clocksource(void *data)
624{
625 struct timekeeper *tk = &timekeeper;
626 struct clocksource *new, *old;
627 unsigned long flags;
628
629 new = (struct clocksource *) data;
630
631 raw_spin_lock_irqsave(&timekeeper_lock, flags);
632 write_seqcount_begin(&timekeeper_seq);
633
634 timekeeping_forward_now(tk);
635 /*
636 * If the cs is in module, get a module reference. Succeeds
637 * for built-in code (owner == NULL) as well.
638 */
639 if (try_module_get(new->owner)) {
640 if (!new->enable || new->enable(new) == 0) {
641 old = tk->clock;
642 tk_setup_internals(tk, new);
643 if (old->disable)
644 old->disable(old);
645 module_put(old->owner);
646 } else {
647 module_put(new->owner);
648 }
649 }
650 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
651
652 write_seqcount_end(&timekeeper_seq);
653 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
654
655 return 0;
656}
657
658/**
659 * timekeeping_notify - Install a new clock source
660 * @clock: pointer to the clock source
661 *
662 * This function is called from clocksource.c after a new, better clock
663 * source has been registered. The caller holds the clocksource_mutex.
664 */
665int timekeeping_notify(struct clocksource *clock)
666{
667 struct timekeeper *tk = &timekeeper;
668
669 if (tk->clock == clock)
670 return 0;
671 stop_machine(change_clocksource, clock, NULL);
672 tick_clock_notify();
673 return tk->clock == clock ? 0 : -1;
674}
675
676/**
677 * ktime_get_real - get the real (wall-) time in ktime_t format
678 *
679 * returns the time in ktime_t format
680 */
681ktime_t ktime_get_real(void)
682{
683 struct timespec now;
684
685 getnstimeofday(&now);
686
687 return timespec_to_ktime(now);
688}
689EXPORT_SYMBOL_GPL(ktime_get_real);
690
691/**
692 * getrawmonotonic - Returns the raw monotonic time in a timespec
693 * @ts: pointer to the timespec to be set
694 *
695 * Returns the raw monotonic time (completely un-modified by ntp)
696 */
697void getrawmonotonic(struct timespec *ts)
698{
699 struct timekeeper *tk = &timekeeper;
700 unsigned long seq;
701 s64 nsecs;
702
703 do {
704 seq = read_seqcount_begin(&timekeeper_seq);
705 nsecs = timekeeping_get_ns_raw(tk);
706 *ts = tk->raw_time;
707
708 } while (read_seqcount_retry(&timekeeper_seq, seq));
709
710 timespec_add_ns(ts, nsecs);
711}
712EXPORT_SYMBOL(getrawmonotonic);
713
714/**
715 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
716 */
717int timekeeping_valid_for_hres(void)
718{
719 struct timekeeper *tk = &timekeeper;
720 unsigned long seq;
721 int ret;
722
723 do {
724 seq = read_seqcount_begin(&timekeeper_seq);
725
726 ret = tk->clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
727
728 } while (read_seqcount_retry(&timekeeper_seq, seq));
729
730 return ret;
731}
732
733/**
734 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
735 */
736u64 timekeeping_max_deferment(void)
737{
738 struct timekeeper *tk = &timekeeper;
739 unsigned long seq;
740 u64 ret;
741
742 do {
743 seq = read_seqcount_begin(&timekeeper_seq);
744
745 ret = tk->clock->max_idle_ns;
746
747 } while (read_seqcount_retry(&timekeeper_seq, seq));
748
749 return ret;
750}
751
752/**
753 * read_persistent_clock - Return time from the persistent clock.
754 *
755 * Weak dummy function for arches that do not yet support it.
756 * Reads the time from the battery backed persistent clock.
757 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
758 *
759 * XXX - Do be sure to remove it once all arches implement it.
760 */
761void __attribute__((weak)) read_persistent_clock(struct timespec *ts)
762{
763 ts->tv_sec = 0;
764 ts->tv_nsec = 0;
765}
766
767/**
768 * read_boot_clock - Return time of the system start.
769 *
770 * Weak dummy function for arches that do not yet support it.
771 * Function to read the exact time the system has been started.
772 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
773 *
774 * XXX - Do be sure to remove it once all arches implement it.
775 */
776void __attribute__((weak)) read_boot_clock(struct timespec *ts)
777{
778 ts->tv_sec = 0;
779 ts->tv_nsec = 0;
780}
781
782/*
783 * timekeeping_init - Initializes the clocksource and common timekeeping values
784 */
785void __init timekeeping_init(void)
786{
787 struct timekeeper *tk = &timekeeper;
788 struct clocksource *clock;
789 unsigned long flags;
790 struct timespec now, boot, tmp;
791
792 read_persistent_clock(&now);
793
794 if (!timespec_valid_strict(&now)) {
795 pr_warn("WARNING: Persistent clock returned invalid value!\n"
796 " Check your CMOS/BIOS settings.\n");
797 now.tv_sec = 0;
798 now.tv_nsec = 0;
799 } else if (now.tv_sec || now.tv_nsec)
800 persistent_clock_exist = true;
801
802 read_boot_clock(&boot);
803 if (!timespec_valid_strict(&boot)) {
804 pr_warn("WARNING: Boot clock returned invalid value!\n"
805 " Check your CMOS/BIOS settings.\n");
806 boot.tv_sec = 0;
807 boot.tv_nsec = 0;
808 }
809
810 raw_spin_lock_irqsave(&timekeeper_lock, flags);
811 write_seqcount_begin(&timekeeper_seq);
812 ntp_init();
813
814 clock = clocksource_default_clock();
815 if (clock->enable)
816 clock->enable(clock);
817 tk_setup_internals(tk, clock);
818
819 tk_set_xtime(tk, &now);
820 tk->raw_time.tv_sec = 0;
821 tk->raw_time.tv_nsec = 0;
822 if (boot.tv_sec == 0 && boot.tv_nsec == 0)
823 boot = tk_xtime(tk);
824
825 set_normalized_timespec(&tmp, -boot.tv_sec, -boot.tv_nsec);
826 tk_set_wall_to_mono(tk, tmp);
827
828 tmp.tv_sec = 0;
829 tmp.tv_nsec = 0;
830 tk_set_sleep_time(tk, tmp);
831
832 memcpy(&shadow_timekeeper, &timekeeper, sizeof(timekeeper));
833
834 write_seqcount_end(&timekeeper_seq);
835 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
836}
837
838/* time in seconds when suspend began */
839static struct timespec timekeeping_suspend_time;
840
841/**
842 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
843 * @delta: pointer to a timespec delta value
844 *
845 * Takes a timespec offset measuring a suspend interval and properly
846 * adds the sleep offset to the timekeeping variables.
847 */
848static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
849 struct timespec *delta)
850{
851 if (!timespec_valid_strict(delta)) {
852 printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
853 "sleep delta value!\n");
854 return;
855 }
856 tk_xtime_add(tk, delta);
857 tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *delta));
858 tk_set_sleep_time(tk, timespec_add(tk->total_sleep_time, *delta));
859 tk_debug_account_sleep_time(delta);
860}
861
862/**
863 * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
864 * @delta: pointer to a timespec delta value
865 *
866 * This hook is for architectures that cannot support read_persistent_clock
867 * because their RTC/persistent clock is only accessible when irqs are enabled.
868 *
869 * This function should only be called by rtc_resume(), and allows
870 * a suspend offset to be injected into the timekeeping values.
871 */
872void timekeeping_inject_sleeptime(struct timespec *delta)
873{
874 struct timekeeper *tk = &timekeeper;
875 unsigned long flags;
876
877 /*
878 * Make sure we don't set the clock twice, as timekeeping_resume()
879 * already did it
880 */
881 if (has_persistent_clock())
882 return;
883
884 raw_spin_lock_irqsave(&timekeeper_lock, flags);
885 write_seqcount_begin(&timekeeper_seq);
886
887 timekeeping_forward_now(tk);
888
889 __timekeeping_inject_sleeptime(tk, delta);
890
891 timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
892
893 write_seqcount_end(&timekeeper_seq);
894 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
895
896 /* signal hrtimers about time change */
897 clock_was_set();
898}
899
900/**
901 * timekeeping_resume - Resumes the generic timekeeping subsystem.
902 *
903 * This is for the generic clocksource timekeeping.
904 * xtime/wall_to_monotonic/jiffies/etc are
905 * still managed by arch specific suspend/resume code.
906 */
907static void timekeeping_resume(void)
908{
909 struct timekeeper *tk = &timekeeper;
910 struct clocksource *clock = tk->clock;
911 unsigned long flags;
912 struct timespec ts_new, ts_delta;
913 cycle_t cycle_now, cycle_delta;
914 bool suspendtime_found = false;
915
916 read_persistent_clock(&ts_new);
917
918 clockevents_resume();
919 clocksource_resume();
920
921 raw_spin_lock_irqsave(&timekeeper_lock, flags);
922 write_seqcount_begin(&timekeeper_seq);
923
924 /*
925 * After system resumes, we need to calculate the suspended time and
926 * compensate it for the OS time. There are 3 sources that could be
927 * used: Nonstop clocksource during suspend, persistent clock and rtc
928 * device.
929 *
930 * One specific platform may have 1 or 2 or all of them, and the
931 * preference will be:
932 * suspend-nonstop clocksource -> persistent clock -> rtc
933 * The less preferred source will only be tried if there is no better
934 * usable source. The rtc part is handled separately in rtc core code.
935 */
936 cycle_now = clock->read(clock);
937 if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) &&
938 cycle_now > clock->cycle_last) {
939 u64 num, max = ULLONG_MAX;
940 u32 mult = clock->mult;
941 u32 shift = clock->shift;
942 s64 nsec = 0;
943
944 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
945
946 /*
947 * "cycle_delta * mutl" may cause 64 bits overflow, if the
948 * suspended time is too long. In that case we need do the
949 * 64 bits math carefully
950 */
951 do_div(max, mult);
952 if (cycle_delta > max) {
953 num = div64_u64(cycle_delta, max);
954 nsec = (((u64) max * mult) >> shift) * num;
955 cycle_delta -= num * max;
956 }
957 nsec += ((u64) cycle_delta * mult) >> shift;
958
959 ts_delta = ns_to_timespec(nsec);
960 suspendtime_found = true;
961 } else if (timespec_compare(&ts_new, &timekeeping_suspend_time) > 0) {
962 ts_delta = timespec_sub(ts_new, timekeeping_suspend_time);
963 suspendtime_found = true;
964 }
965
966 if (suspendtime_found)
967 __timekeeping_inject_sleeptime(tk, &ts_delta);
968
969 /* Re-base the last cycle value */
970 tk->cycle_last = clock->cycle_last = cycle_now;
971 tk->ntp_error = 0;
972 timekeeping_suspended = 0;
973 timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
974 write_seqcount_end(&timekeeper_seq);
975 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
976
977 touch_softlockup_watchdog();
978
979 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
980
981 /* Resume hrtimers */
982 hrtimers_resume();
983}
984
985static int timekeeping_suspend(void)
986{
987 struct timekeeper *tk = &timekeeper;
988 unsigned long flags;
989 struct timespec delta, delta_delta;
990 static struct timespec old_delta;
991
992 read_persistent_clock(&timekeeping_suspend_time);
993
994 /*
995 * On some systems the persistent_clock can not be detected at
996 * timekeeping_init by its return value, so if we see a valid
997 * value returned, update the persistent_clock_exists flag.
998 */
999 if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1000 persistent_clock_exist = true;
1001
1002 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1003 write_seqcount_begin(&timekeeper_seq);
1004 timekeeping_forward_now(tk);
1005 timekeeping_suspended = 1;
1006
1007 /*
1008 * To avoid drift caused by repeated suspend/resumes,
1009 * which each can add ~1 second drift error,
1010 * try to compensate so the difference in system time
1011 * and persistent_clock time stays close to constant.
1012 */
1013 delta = timespec_sub(tk_xtime(tk), timekeeping_suspend_time);
1014 delta_delta = timespec_sub(delta, old_delta);
1015 if (abs(delta_delta.tv_sec) >= 2) {
1016 /*
1017 * if delta_delta is too large, assume time correction
1018 * has occured and set old_delta to the current delta.
1019 */
1020 old_delta = delta;
1021 } else {
1022 /* Otherwise try to adjust old_system to compensate */
1023 timekeeping_suspend_time =
1024 timespec_add(timekeeping_suspend_time, delta_delta);
1025 }
1026 write_seqcount_end(&timekeeper_seq);
1027 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1028
1029 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
1030 clocksource_suspend();
1031 clockevents_suspend();
1032
1033 return 0;
1034}
1035
1036/* sysfs resume/suspend bits for timekeeping */
1037static struct syscore_ops timekeeping_syscore_ops = {
1038 .resume = timekeeping_resume,
1039 .suspend = timekeeping_suspend,
1040};
1041
1042static int __init timekeeping_init_ops(void)
1043{
1044 register_syscore_ops(&timekeeping_syscore_ops);
1045 return 0;
1046}
1047
1048device_initcall(timekeeping_init_ops);
1049
1050/*
1051 * If the error is already larger, we look ahead even further
1052 * to compensate for late or lost adjustments.
1053 */
1054static __always_inline int timekeeping_bigadjust(struct timekeeper *tk,
1055 s64 error, s64 *interval,
1056 s64 *offset)
1057{
1058 s64 tick_error, i;
1059 u32 look_ahead, adj;
1060 s32 error2, mult;
1061
1062 /*
1063 * Use the current error value to determine how much to look ahead.
1064 * The larger the error the slower we adjust for it to avoid problems
1065 * with losing too many ticks, otherwise we would overadjust and
1066 * produce an even larger error. The smaller the adjustment the
1067 * faster we try to adjust for it, as lost ticks can do less harm
1068 * here. This is tuned so that an error of about 1 msec is adjusted
1069 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
1070 */
1071 error2 = tk->ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
1072 error2 = abs(error2);
1073 for (look_ahead = 0; error2 > 0; look_ahead++)
1074 error2 >>= 2;
1075
1076 /*
1077 * Now calculate the error in (1 << look_ahead) ticks, but first
1078 * remove the single look ahead already included in the error.
1079 */
1080 tick_error = ntp_tick_length() >> (tk->ntp_error_shift + 1);
1081 tick_error -= tk->xtime_interval >> 1;
1082 error = ((error - tick_error) >> look_ahead) + tick_error;
1083
1084 /* Finally calculate the adjustment shift value. */
1085 i = *interval;
1086 mult = 1;
1087 if (error < 0) {
1088 error = -error;
1089 *interval = -*interval;
1090 *offset = -*offset;
1091 mult = -1;
1092 }
1093 for (adj = 0; error > i; adj++)
1094 error >>= 1;
1095
1096 *interval <<= adj;
1097 *offset <<= adj;
1098 return mult << adj;
1099}
1100
1101/*
1102 * Adjust the multiplier to reduce the error value,
1103 * this is optimized for the most common adjustments of -1,0,1,
1104 * for other values we can do a bit more work.
1105 */
1106static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1107{
1108 s64 error, interval = tk->cycle_interval;
1109 int adj;
1110
1111 /*
1112 * The point of this is to check if the error is greater than half
1113 * an interval.
1114 *
1115 * First we shift it down from NTP_SHIFT to clocksource->shifted nsecs.
1116 *
1117 * Note we subtract one in the shift, so that error is really error*2.
1118 * This "saves" dividing(shifting) interval twice, but keeps the
1119 * (error > interval) comparison as still measuring if error is
1120 * larger than half an interval.
1121 *
1122 * Note: It does not "save" on aggravation when reading the code.
1123 */
1124 error = tk->ntp_error >> (tk->ntp_error_shift - 1);
1125 if (error > interval) {
1126 /*
1127 * We now divide error by 4(via shift), which checks if
1128 * the error is greater than twice the interval.
1129 * If it is greater, we need a bigadjust, if its smaller,
1130 * we can adjust by 1.
1131 */
1132 error >>= 2;
1133 /*
1134 * XXX - In update_wall_time, we round up to the next
1135 * nanosecond, and store the amount rounded up into
1136 * the error. This causes the likely below to be unlikely.
1137 *
1138 * The proper fix is to avoid rounding up by using
1139 * the high precision tk->xtime_nsec instead of
1140 * xtime.tv_nsec everywhere. Fixing this will take some
1141 * time.
1142 */
1143 if (likely(error <= interval))
1144 adj = 1;
1145 else
1146 adj = timekeeping_bigadjust(tk, error, &interval, &offset);
1147 } else {
1148 if (error < -interval) {
1149 /* See comment above, this is just switched for the negative */
1150 error >>= 2;
1151 if (likely(error >= -interval)) {
1152 adj = -1;
1153 interval = -interval;
1154 offset = -offset;
1155 } else {
1156 adj = timekeeping_bigadjust(tk, error, &interval, &offset);
1157 }
1158 } else {
1159 goto out_adjust;
1160 }
1161 }
1162
1163 if (unlikely(tk->clock->maxadj &&
1164 (tk->mult + adj > tk->clock->mult + tk->clock->maxadj))) {
1165 printk_once(KERN_WARNING
1166 "Adjusting %s more than 11%% (%ld vs %ld)\n",
1167 tk->clock->name, (long)tk->mult + adj,
1168 (long)tk->clock->mult + tk->clock->maxadj);
1169 }
1170 /*
1171 * So the following can be confusing.
1172 *
1173 * To keep things simple, lets assume adj == 1 for now.
1174 *
1175 * When adj != 1, remember that the interval and offset values
1176 * have been appropriately scaled so the math is the same.
1177 *
1178 * The basic idea here is that we're increasing the multiplier
1179 * by one, this causes the xtime_interval to be incremented by
1180 * one cycle_interval. This is because:
1181 * xtime_interval = cycle_interval * mult
1182 * So if mult is being incremented by one:
1183 * xtime_interval = cycle_interval * (mult + 1)
1184 * Its the same as:
1185 * xtime_interval = (cycle_interval * mult) + cycle_interval
1186 * Which can be shortened to:
1187 * xtime_interval += cycle_interval
1188 *
1189 * So offset stores the non-accumulated cycles. Thus the current
1190 * time (in shifted nanoseconds) is:
1191 * now = (offset * adj) + xtime_nsec
1192 * Now, even though we're adjusting the clock frequency, we have
1193 * to keep time consistent. In other words, we can't jump back
1194 * in time, and we also want to avoid jumping forward in time.
1195 *
1196 * So given the same offset value, we need the time to be the same
1197 * both before and after the freq adjustment.
1198 * now = (offset * adj_1) + xtime_nsec_1
1199 * now = (offset * adj_2) + xtime_nsec_2
1200 * So:
1201 * (offset * adj_1) + xtime_nsec_1 =
1202 * (offset * adj_2) + xtime_nsec_2
1203 * And we know:
1204 * adj_2 = adj_1 + 1
1205 * So:
1206 * (offset * adj_1) + xtime_nsec_1 =
1207 * (offset * (adj_1+1)) + xtime_nsec_2
1208 * (offset * adj_1) + xtime_nsec_1 =
1209 * (offset * adj_1) + offset + xtime_nsec_2
1210 * Canceling the sides:
1211 * xtime_nsec_1 = offset + xtime_nsec_2
1212 * Which gives us:
1213 * xtime_nsec_2 = xtime_nsec_1 - offset
1214 * Which simplfies to:
1215 * xtime_nsec -= offset
1216 *
1217 * XXX - TODO: Doc ntp_error calculation.
1218 */
1219 tk->mult += adj;
1220 tk->xtime_interval += interval;
1221 tk->xtime_nsec -= offset;
1222 tk->ntp_error -= (interval - offset) << tk->ntp_error_shift;
1223
1224out_adjust:
1225 /*
1226 * It may be possible that when we entered this function, xtime_nsec
1227 * was very small. Further, if we're slightly speeding the clocksource
1228 * in the code above, its possible the required corrective factor to
1229 * xtime_nsec could cause it to underflow.
1230 *
1231 * Now, since we already accumulated the second, cannot simply roll
1232 * the accumulated second back, since the NTP subsystem has been
1233 * notified via second_overflow. So instead we push xtime_nsec forward
1234 * by the amount we underflowed, and add that amount into the error.
1235 *
1236 * We'll correct this error next time through this function, when
1237 * xtime_nsec is not as small.
1238 */
1239 if (unlikely((s64)tk->xtime_nsec < 0)) {
1240 s64 neg = -(s64)tk->xtime_nsec;
1241 tk->xtime_nsec = 0;
1242 tk->ntp_error += neg << tk->ntp_error_shift;
1243 }
1244
1245}
1246
1247/**
1248 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1249 *
1250 * Helper function that accumulates a the nsecs greater then a second
1251 * from the xtime_nsec field to the xtime_secs field.
1252 * It also calls into the NTP code to handle leapsecond processing.
1253 *
1254 */
1255static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
1256{
1257 u64 nsecps = (u64)NSEC_PER_SEC << tk->shift;
1258 unsigned int action = 0;
1259
1260 while (tk->xtime_nsec >= nsecps) {
1261 int leap;
1262
1263 tk->xtime_nsec -= nsecps;
1264 tk->xtime_sec++;
1265
1266 /* Figure out if its a leap sec and apply if needed */
1267 leap = second_overflow(tk->xtime_sec);
1268 if (unlikely(leap)) {
1269 struct timespec ts;
1270
1271 tk->xtime_sec += leap;
1272
1273 ts.tv_sec = leap;
1274 ts.tv_nsec = 0;
1275 tk_set_wall_to_mono(tk,
1276 timespec_sub(tk->wall_to_monotonic, ts));
1277
1278 __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
1279
1280 clock_was_set_delayed();
1281 action = TK_CLOCK_WAS_SET;
1282 }
1283 }
1284 return action;
1285}
1286
1287/**
1288 * logarithmic_accumulation - shifted accumulation of cycles
1289 *
1290 * This functions accumulates a shifted interval of cycles into
1291 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1292 * loop.
1293 *
1294 * Returns the unconsumed cycles.
1295 */
1296static cycle_t logarithmic_accumulation(struct timekeeper *tk, cycle_t offset,
1297 u32 shift)
1298{
1299 cycle_t interval = tk->cycle_interval << shift;
1300 u64 raw_nsecs;
1301
1302 /* If the offset is smaller then a shifted interval, do nothing */
1303 if (offset < interval)
1304 return offset;
1305
1306 /* Accumulate one shifted interval */
1307 offset -= interval;
1308 tk->cycle_last += interval;
1309
1310 tk->xtime_nsec += tk->xtime_interval << shift;
1311 accumulate_nsecs_to_secs(tk);
1312
1313 /* Accumulate raw time */
1314 raw_nsecs = (u64)tk->raw_interval << shift;
1315 raw_nsecs += tk->raw_time.tv_nsec;
1316 if (raw_nsecs >= NSEC_PER_SEC) {
1317 u64 raw_secs = raw_nsecs;
1318 raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
1319 tk->raw_time.tv_sec += raw_secs;
1320 }
1321 tk->raw_time.tv_nsec = raw_nsecs;
1322
1323 /* Accumulate error between NTP and clock interval */
1324 tk->ntp_error += ntp_tick_length() << shift;
1325 tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
1326 (tk->ntp_error_shift + shift);
1327
1328 return offset;
1329}
1330
1331#ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
1332static inline void old_vsyscall_fixup(struct timekeeper *tk)
1333{
1334 s64 remainder;
1335
1336 /*
1337 * Store only full nanoseconds into xtime_nsec after rounding
1338 * it up and add the remainder to the error difference.
1339 * XXX - This is necessary to avoid small 1ns inconsistnecies caused
1340 * by truncating the remainder in vsyscalls. However, it causes
1341 * additional work to be done in timekeeping_adjust(). Once
1342 * the vsyscall implementations are converted to use xtime_nsec
1343 * (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
1344 * users are removed, this can be killed.
1345 */
1346 remainder = tk->xtime_nsec & ((1ULL << tk->shift) - 1);
1347 tk->xtime_nsec -= remainder;
1348 tk->xtime_nsec += 1ULL << tk->shift;
1349 tk->ntp_error += remainder << tk->ntp_error_shift;
1350 tk->ntp_error -= (1ULL << tk->shift) << tk->ntp_error_shift;
1351}
1352#else
1353#define old_vsyscall_fixup(tk)
1354#endif
1355
1356
1357
1358/**
1359 * update_wall_time - Uses the current clocksource to increment the wall time
1360 *
1361 */
1362static void update_wall_time(void)
1363{
1364 struct clocksource *clock;
1365 struct timekeeper *real_tk = &timekeeper;
1366 struct timekeeper *tk = &shadow_timekeeper;
1367 cycle_t offset;
1368 int shift = 0, maxshift;
1369 unsigned int action;
1370 unsigned long flags;
1371
1372 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1373
1374 /* Make sure we're fully resumed: */
1375 if (unlikely(timekeeping_suspended))
1376 goto out;
1377
1378 clock = real_tk->clock;
1379
1380#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1381 offset = real_tk->cycle_interval;
1382#else
1383 offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
1384#endif
1385
1386 /* Check if there's really nothing to do */
1387 if (offset < real_tk->cycle_interval)
1388 goto out;
1389
1390 /*
1391 * With NO_HZ we may have to accumulate many cycle_intervals
1392 * (think "ticks") worth of time at once. To do this efficiently,
1393 * we calculate the largest doubling multiple of cycle_intervals
1394 * that is smaller than the offset. We then accumulate that
1395 * chunk in one go, and then try to consume the next smaller
1396 * doubled multiple.
1397 */
1398 shift = ilog2(offset) - ilog2(tk->cycle_interval);
1399 shift = max(0, shift);
1400 /* Bound shift to one less than what overflows tick_length */
1401 maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
1402 shift = min(shift, maxshift);
1403 while (offset >= tk->cycle_interval) {
1404 offset = logarithmic_accumulation(tk, offset, shift);
1405 if (offset < tk->cycle_interval<<shift)
1406 shift--;
1407 }
1408
1409 /* correct the clock when NTP error is too big */
1410 timekeeping_adjust(tk, offset);
1411
1412 /*
1413 * XXX This can be killed once everyone converts
1414 * to the new update_vsyscall.
1415 */
1416 old_vsyscall_fixup(tk);
1417
1418 /*
1419 * Finally, make sure that after the rounding
1420 * xtime_nsec isn't larger than NSEC_PER_SEC
1421 */
1422 action = accumulate_nsecs_to_secs(tk);
1423
1424 write_seqcount_begin(&timekeeper_seq);
1425 /* Update clock->cycle_last with the new value */
1426 clock->cycle_last = tk->cycle_last;
1427 /*
1428 * Update the real timekeeper.
1429 *
1430 * We could avoid this memcpy by switching pointers, but that
1431 * requires changes to all other timekeeper usage sites as
1432 * well, i.e. move the timekeeper pointer getter into the
1433 * spinlocked/seqcount protected sections. And we trade this
1434 * memcpy under the timekeeper_seq against one before we start
1435 * updating.
1436 */
1437 memcpy(real_tk, tk, sizeof(*tk));
1438 timekeeping_update(real_tk, action);
1439 write_seqcount_end(&timekeeper_seq);
1440out:
1441 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1442}
1443
1444/**
1445 * getboottime - Return the real time of system boot.
1446 * @ts: pointer to the timespec to be set
1447 *
1448 * Returns the wall-time of boot in a timespec.
1449 *
1450 * This is based on the wall_to_monotonic offset and the total suspend
1451 * time. Calls to settimeofday will affect the value returned (which
1452 * basically means that however wrong your real time clock is at boot time,
1453 * you get the right time here).
1454 */
1455void getboottime(struct timespec *ts)
1456{
1457 struct timekeeper *tk = &timekeeper;
1458 struct timespec boottime = {
1459 .tv_sec = tk->wall_to_monotonic.tv_sec +
1460 tk->total_sleep_time.tv_sec,
1461 .tv_nsec = tk->wall_to_monotonic.tv_nsec +
1462 tk->total_sleep_time.tv_nsec
1463 };
1464
1465 set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
1466}
1467EXPORT_SYMBOL_GPL(getboottime);
1468
1469/**
1470 * get_monotonic_boottime - Returns monotonic time since boot
1471 * @ts: pointer to the timespec to be set
1472 *
1473 * Returns the monotonic time since boot in a timespec.
1474 *
1475 * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
1476 * includes the time spent in suspend.
1477 */
1478void get_monotonic_boottime(struct timespec *ts)
1479{
1480 struct timekeeper *tk = &timekeeper;
1481 struct timespec tomono, sleep;
1482 s64 nsec;
1483 unsigned int seq;
1484
1485 WARN_ON(timekeeping_suspended);
1486
1487 do {
1488 seq = read_seqcount_begin(&timekeeper_seq);
1489 ts->tv_sec = tk->xtime_sec;
1490 nsec = timekeeping_get_ns(tk);
1491 tomono = tk->wall_to_monotonic;
1492 sleep = tk->total_sleep_time;
1493
1494 } while (read_seqcount_retry(&timekeeper_seq, seq));
1495
1496 ts->tv_sec += tomono.tv_sec + sleep.tv_sec;
1497 ts->tv_nsec = 0;
1498 timespec_add_ns(ts, nsec + tomono.tv_nsec + sleep.tv_nsec);
1499}
1500EXPORT_SYMBOL_GPL(get_monotonic_boottime);
1501
1502/**
1503 * ktime_get_boottime - Returns monotonic time since boot in a ktime
1504 *
1505 * Returns the monotonic time since boot in a ktime
1506 *
1507 * This is similar to CLOCK_MONTONIC/ktime_get, but also
1508 * includes the time spent in suspend.
1509 */
1510ktime_t ktime_get_boottime(void)
1511{
1512 struct timespec ts;
1513
1514 get_monotonic_boottime(&ts);
1515 return timespec_to_ktime(ts);
1516}
1517EXPORT_SYMBOL_GPL(ktime_get_boottime);
1518
1519/**
1520 * monotonic_to_bootbased - Convert the monotonic time to boot based.
1521 * @ts: pointer to the timespec to be converted
1522 */
1523void monotonic_to_bootbased(struct timespec *ts)
1524{
1525 struct timekeeper *tk = &timekeeper;
1526
1527 *ts = timespec_add(*ts, tk->total_sleep_time);
1528}
1529EXPORT_SYMBOL_GPL(monotonic_to_bootbased);
1530
1531unsigned long get_seconds(void)
1532{
1533 struct timekeeper *tk = &timekeeper;
1534
1535 return tk->xtime_sec;
1536}
1537EXPORT_SYMBOL(get_seconds);
1538
1539struct timespec __current_kernel_time(void)
1540{
1541 struct timekeeper *tk = &timekeeper;
1542
1543 return tk_xtime(tk);
1544}
1545
1546struct timespec current_kernel_time(void)
1547{
1548 struct timekeeper *tk = &timekeeper;
1549 struct timespec now;
1550 unsigned long seq;
1551
1552 do {
1553 seq = read_seqcount_begin(&timekeeper_seq);
1554
1555 now = tk_xtime(tk);
1556 } while (read_seqcount_retry(&timekeeper_seq, seq));
1557
1558 return now;
1559}
1560EXPORT_SYMBOL(current_kernel_time);
1561
1562struct timespec get_monotonic_coarse(void)
1563{
1564 struct timekeeper *tk = &timekeeper;
1565 struct timespec now, mono;
1566 unsigned long seq;
1567
1568 do {
1569 seq = read_seqcount_begin(&timekeeper_seq);
1570
1571 now = tk_xtime(tk);
1572 mono = tk->wall_to_monotonic;
1573 } while (read_seqcount_retry(&timekeeper_seq, seq));
1574
1575 set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
1576 now.tv_nsec + mono.tv_nsec);
1577 return now;
1578}
1579
1580/*
1581 * Must hold jiffies_lock
1582 */
1583void do_timer(unsigned long ticks)
1584{
1585 jiffies_64 += ticks;
1586 update_wall_time();
1587 calc_global_load(ticks);
1588}
1589
1590/**
1591 * get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic,
1592 * and sleep offsets.
1593 * @xtim: pointer to timespec to be set with xtime
1594 * @wtom: pointer to timespec to be set with wall_to_monotonic
1595 * @sleep: pointer to timespec to be set with time in suspend
1596 */
1597void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
1598 struct timespec *wtom, struct timespec *sleep)
1599{
1600 struct timekeeper *tk = &timekeeper;
1601 unsigned long seq;
1602
1603 do {
1604 seq = read_seqcount_begin(&timekeeper_seq);
1605 *xtim = tk_xtime(tk);
1606 *wtom = tk->wall_to_monotonic;
1607 *sleep = tk->total_sleep_time;
1608 } while (read_seqcount_retry(&timekeeper_seq, seq));
1609}
1610
1611#ifdef CONFIG_HIGH_RES_TIMERS
1612/**
1613 * ktime_get_update_offsets - hrtimer helper
1614 * @offs_real: pointer to storage for monotonic -> realtime offset
1615 * @offs_boot: pointer to storage for monotonic -> boottime offset
1616 * @offs_tai: pointer to storage for monotonic -> clock tai offset
1617 *
1618 * Returns current monotonic time and updates the offsets
1619 * Called from hrtimer_interrupt() or retrigger_next_event()
1620 */
1621ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot,
1622 ktime_t *offs_tai)
1623{
1624 struct timekeeper *tk = &timekeeper;
1625 ktime_t now;
1626 unsigned int seq;
1627 u64 secs, nsecs;
1628
1629 do {
1630 seq = read_seqcount_begin(&timekeeper_seq);
1631
1632 secs = tk->xtime_sec;
1633 nsecs = timekeeping_get_ns(tk);
1634
1635 *offs_real = tk->offs_real;
1636 *offs_boot = tk->offs_boot;
1637 *offs_tai = tk->offs_tai;
1638 } while (read_seqcount_retry(&timekeeper_seq, seq));
1639
1640 now = ktime_add_ns(ktime_set(secs, 0), nsecs);
1641 now = ktime_sub(now, *offs_real);
1642 return now;
1643}
1644#endif
1645
1646/**
1647 * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
1648 */
1649ktime_t ktime_get_monotonic_offset(void)
1650{
1651 struct timekeeper *tk = &timekeeper;
1652 unsigned long seq;
1653 struct timespec wtom;
1654
1655 do {
1656 seq = read_seqcount_begin(&timekeeper_seq);
1657 wtom = tk->wall_to_monotonic;
1658 } while (read_seqcount_retry(&timekeeper_seq, seq));
1659
1660 return timespec_to_ktime(wtom);
1661}
1662EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset);
1663
1664/**
1665 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
1666 */
1667int do_adjtimex(struct timex *txc)
1668{
1669 struct timekeeper *tk = &timekeeper;
1670 unsigned long flags;
1671 struct timespec ts;
1672 s32 orig_tai, tai;
1673 int ret;
1674
1675 /* Validate the data before disabling interrupts */
1676 ret = ntp_validate_timex(txc);
1677 if (ret)
1678 return ret;
1679
1680 if (txc->modes & ADJ_SETOFFSET) {
1681 struct timespec delta;
1682 delta.tv_sec = txc->time.tv_sec;
1683 delta.tv_nsec = txc->time.tv_usec;
1684 if (!(txc->modes & ADJ_NANO))
1685 delta.tv_nsec *= 1000;
1686 ret = timekeeping_inject_offset(&delta);
1687 if (ret)
1688 return ret;
1689 }
1690
1691 getnstimeofday(&ts);
1692
1693 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1694 write_seqcount_begin(&timekeeper_seq);
1695
1696 orig_tai = tai = tk->tai_offset;
1697 ret = __do_adjtimex(txc, &ts, &tai);
1698
1699 if (tai != orig_tai) {
1700 __timekeeping_set_tai_offset(tk, tai);
1701 update_pvclock_gtod(tk, true);
1702 clock_was_set_delayed();
1703 }
1704 write_seqcount_end(&timekeeper_seq);
1705 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1706
1707 ntp_notify_cmos_timer();
1708
1709 return ret;
1710}
1711
1712#ifdef CONFIG_NTP_PPS
1713/**
1714 * hardpps() - Accessor function to NTP __hardpps function
1715 */
1716void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts)
1717{
1718 unsigned long flags;
1719
1720 raw_spin_lock_irqsave(&timekeeper_lock, flags);
1721 write_seqcount_begin(&timekeeper_seq);
1722
1723 __hardpps(phase_ts, raw_ts);
1724
1725 write_seqcount_end(&timekeeper_seq);
1726 raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1727}
1728EXPORT_SYMBOL(hardpps);
1729#endif
1730
1731/**
1732 * xtime_update() - advances the timekeeping infrastructure
1733 * @ticks: number of ticks, that have elapsed since the last call.
1734 *
1735 * Must be called with interrupts disabled.
1736 */
1737void xtime_update(unsigned long ticks)
1738{
1739 write_seqlock(&jiffies_lock);
1740 do_timer(ticks);
1741 write_sequnlock(&jiffies_lock);
1742}