2 * linux/kernel/time/timekeeping.c
4 * Kernel timekeeping code and accessor functions
6 * This code was moved from linux/kernel/timer.c.
7 * Please see that file for copyright and history logs.
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>
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>
27 static struct timekeeper timekeeper
;
29 /* flag for if timekeeping is suspended */
30 int __read_mostly timekeeping_suspended
;
32 /* Flag for if there is a persistent clock on this platform */
33 bool __read_mostly persistent_clock_exist
= false;
35 static inline void tk_normalize_xtime(struct timekeeper
*tk
)
37 while (tk
->xtime_nsec
>= ((u64
)NSEC_PER_SEC
<< tk
->shift
)) {
38 tk
->xtime_nsec
-= (u64
)NSEC_PER_SEC
<< tk
->shift
;
43 static void tk_set_xtime(struct timekeeper
*tk
, const struct timespec
*ts
)
45 tk
->xtime_sec
= ts
->tv_sec
;
46 tk
->xtime_nsec
= (u64
)ts
->tv_nsec
<< tk
->shift
;
49 static void tk_xtime_add(struct timekeeper
*tk
, const struct timespec
*ts
)
51 tk
->xtime_sec
+= ts
->tv_sec
;
52 tk
->xtime_nsec
+= (u64
)ts
->tv_nsec
<< tk
->shift
;
53 tk_normalize_xtime(tk
);
56 static void tk_set_wall_to_mono(struct timekeeper
*tk
, struct timespec wtm
)
61 * Verify consistency of: offset_real = -wall_to_monotonic
62 * before modifying anything
64 set_normalized_timespec(&tmp
, -tk
->wall_to_monotonic
.tv_sec
,
65 -tk
->wall_to_monotonic
.tv_nsec
);
66 WARN_ON_ONCE(tk
->offs_real
.tv64
!= timespec_to_ktime(tmp
).tv64
);
67 tk
->wall_to_monotonic
= wtm
;
68 set_normalized_timespec(&tmp
, -wtm
.tv_sec
, -wtm
.tv_nsec
);
69 tk
->offs_real
= timespec_to_ktime(tmp
);
72 static void tk_set_sleep_time(struct timekeeper
*tk
, struct timespec t
)
74 /* Verify consistency before modifying */
75 WARN_ON_ONCE(tk
->offs_boot
.tv64
!= timespec_to_ktime(tk
->total_sleep_time
).tv64
);
77 tk
->total_sleep_time
= t
;
78 tk
->offs_boot
= timespec_to_ktime(t
);
82 * timekeeper_setup_internals - Set up internals to use clocksource clock.
84 * @clock: Pointer to clocksource.
86 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
87 * pair and interval request.
89 * Unless you're the timekeeping code, you should not be using this!
91 static void tk_setup_internals(struct timekeeper
*tk
, struct clocksource
*clock
)
95 struct clocksource
*old_clock
;
97 old_clock
= tk
->clock
;
99 clock
->cycle_last
= clock
->read(clock
);
101 /* Do the ns -> cycle conversion first, using original mult */
102 tmp
= NTP_INTERVAL_LENGTH
;
103 tmp
<<= clock
->shift
;
105 tmp
+= clock
->mult
/2;
106 do_div(tmp
, clock
->mult
);
110 interval
= (cycle_t
) tmp
;
111 tk
->cycle_interval
= interval
;
113 /* Go back from cycles -> shifted ns */
114 tk
->xtime_interval
= (u64
) interval
* clock
->mult
;
115 tk
->xtime_remainder
= ntpinterval
- tk
->xtime_interval
;
117 ((u64
) interval
* clock
->mult
) >> clock
->shift
;
119 /* if changing clocks, convert xtime_nsec shift units */
121 int shift_change
= clock
->shift
- old_clock
->shift
;
122 if (shift_change
< 0)
123 tk
->xtime_nsec
>>= -shift_change
;
125 tk
->xtime_nsec
<<= shift_change
;
127 tk
->shift
= clock
->shift
;
130 tk
->ntp_error_shift
= NTP_SCALE_SHIFT
- clock
->shift
;
133 * The timekeeper keeps its own mult values for the currently
134 * active clocksource. These value will be adjusted via NTP
135 * to counteract clock drifting.
137 tk
->mult
= clock
->mult
;
140 /* Timekeeper helper functions. */
141 static inline s64
timekeeping_get_ns(struct timekeeper
*tk
)
143 cycle_t cycle_now
, cycle_delta
;
144 struct clocksource
*clock
;
147 /* read clocksource: */
149 cycle_now
= clock
->read(clock
);
151 /* calculate the delta since the last update_wall_time: */
152 cycle_delta
= (cycle_now
- clock
->cycle_last
) & clock
->mask
;
154 nsec
= cycle_delta
* tk
->mult
+ tk
->xtime_nsec
;
157 /* If arch requires, add in gettimeoffset() */
158 return nsec
+ arch_gettimeoffset();
161 static inline s64
timekeeping_get_ns_raw(struct timekeeper
*tk
)
163 cycle_t cycle_now
, cycle_delta
;
164 struct clocksource
*clock
;
167 /* read clocksource: */
169 cycle_now
= clock
->read(clock
);
171 /* calculate the delta since the last update_wall_time: */
172 cycle_delta
= (cycle_now
- clock
->cycle_last
) & clock
->mask
;
174 /* convert delta to nanoseconds. */
175 nsec
= clocksource_cyc2ns(cycle_delta
, clock
->mult
, clock
->shift
);
177 /* If arch requires, add in gettimeoffset() */
178 return nsec
+ arch_gettimeoffset();
181 static RAW_NOTIFIER_HEAD(pvclock_gtod_chain
);
183 static void update_pvclock_gtod(struct timekeeper
*tk
)
185 raw_notifier_call_chain(&pvclock_gtod_chain
, 0, tk
);
189 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
191 * Must hold write on timekeeper.lock
193 int pvclock_gtod_register_notifier(struct notifier_block
*nb
)
195 struct timekeeper
*tk
= &timekeeper
;
199 write_seqlock_irqsave(&tk
->lock
, flags
);
200 ret
= raw_notifier_chain_register(&pvclock_gtod_chain
, nb
);
201 /* update timekeeping data */
202 update_pvclock_gtod(tk
);
203 write_sequnlock_irqrestore(&tk
->lock
, flags
);
207 EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier
);
210 * pvclock_gtod_unregister_notifier - unregister a pvclock
211 * timedata update listener
213 * Must hold write on timekeeper.lock
215 int pvclock_gtod_unregister_notifier(struct notifier_block
*nb
)
217 struct timekeeper
*tk
= &timekeeper
;
221 write_seqlock_irqsave(&tk
->lock
, flags
);
222 ret
= raw_notifier_chain_unregister(&pvclock_gtod_chain
, nb
);
223 write_sequnlock_irqrestore(&tk
->lock
, flags
);
227 EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier
);
229 /* must hold write on timekeeper.lock */
230 static void timekeeping_update(struct timekeeper
*tk
, bool clearntp
)
237 update_pvclock_gtod(tk
);
241 * timekeeping_forward_now - update clock to the current time
243 * Forward the current clock to update its state since the last call to
244 * update_wall_time(). This is useful before significant clock changes,
245 * as it avoids having to deal with this time offset explicitly.
247 static void timekeeping_forward_now(struct timekeeper
*tk
)
249 cycle_t cycle_now
, cycle_delta
;
250 struct clocksource
*clock
;
254 cycle_now
= clock
->read(clock
);
255 cycle_delta
= (cycle_now
- clock
->cycle_last
) & clock
->mask
;
256 clock
->cycle_last
= cycle_now
;
258 tk
->xtime_nsec
+= cycle_delta
* tk
->mult
;
260 /* If arch requires, add in gettimeoffset() */
261 tk
->xtime_nsec
+= (u64
)arch_gettimeoffset() << tk
->shift
;
263 tk_normalize_xtime(tk
);
265 nsec
= clocksource_cyc2ns(cycle_delta
, clock
->mult
, clock
->shift
);
266 timespec_add_ns(&tk
->raw_time
, nsec
);
270 * __getnstimeofday - Returns the time of day in a timespec.
271 * @ts: pointer to the timespec to be set
273 * Updates the time of day in the timespec.
274 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
276 int __getnstimeofday(struct timespec
*ts
)
278 struct timekeeper
*tk
= &timekeeper
;
283 seq
= read_seqbegin(&tk
->lock
);
285 ts
->tv_sec
= tk
->xtime_sec
;
286 nsecs
= timekeeping_get_ns(tk
);
288 } while (read_seqretry(&tk
->lock
, seq
));
291 timespec_add_ns(ts
, nsecs
);
294 * Do not bail out early, in case there were callers still using
295 * the value, even in the face of the WARN_ON.
297 if (unlikely(timekeeping_suspended
))
301 EXPORT_SYMBOL(__getnstimeofday
);
304 * getnstimeofday - Returns the time of day in a timespec.
305 * @ts: pointer to the timespec to be set
307 * Returns the time of day in a timespec (WARN if suspended).
309 void getnstimeofday(struct timespec
*ts
)
311 WARN_ON(__getnstimeofday(ts
));
313 EXPORT_SYMBOL(getnstimeofday
);
315 ktime_t
ktime_get(void)
317 struct timekeeper
*tk
= &timekeeper
;
321 WARN_ON(timekeeping_suspended
);
324 seq
= read_seqbegin(&tk
->lock
);
325 secs
= tk
->xtime_sec
+ tk
->wall_to_monotonic
.tv_sec
;
326 nsecs
= timekeeping_get_ns(tk
) + tk
->wall_to_monotonic
.tv_nsec
;
328 } while (read_seqretry(&tk
->lock
, seq
));
330 * Use ktime_set/ktime_add_ns to create a proper ktime on
331 * 32-bit architectures without CONFIG_KTIME_SCALAR.
333 return ktime_add_ns(ktime_set(secs
, 0), nsecs
);
335 EXPORT_SYMBOL_GPL(ktime_get
);
338 * ktime_get_ts - get the monotonic clock in timespec format
339 * @ts: pointer to timespec variable
341 * The function calculates the monotonic clock from the realtime
342 * clock and the wall_to_monotonic offset and stores the result
343 * in normalized timespec format in the variable pointed to by @ts.
345 void ktime_get_ts(struct timespec
*ts
)
347 struct timekeeper
*tk
= &timekeeper
;
348 struct timespec tomono
;
352 WARN_ON(timekeeping_suspended
);
355 seq
= read_seqbegin(&tk
->lock
);
356 ts
->tv_sec
= tk
->xtime_sec
;
357 nsec
= timekeeping_get_ns(tk
);
358 tomono
= tk
->wall_to_monotonic
;
360 } while (read_seqretry(&tk
->lock
, seq
));
362 ts
->tv_sec
+= tomono
.tv_sec
;
364 timespec_add_ns(ts
, nsec
+ tomono
.tv_nsec
);
366 EXPORT_SYMBOL_GPL(ktime_get_ts
);
368 #ifdef CONFIG_NTP_PPS
371 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
372 * @ts_raw: pointer to the timespec to be set to raw monotonic time
373 * @ts_real: pointer to the timespec to be set to the time of day
375 * This function reads both the time of day and raw monotonic time at the
376 * same time atomically and stores the resulting timestamps in timespec
379 void getnstime_raw_and_real(struct timespec
*ts_raw
, struct timespec
*ts_real
)
381 struct timekeeper
*tk
= &timekeeper
;
383 s64 nsecs_raw
, nsecs_real
;
385 WARN_ON_ONCE(timekeeping_suspended
);
388 seq
= read_seqbegin(&tk
->lock
);
390 *ts_raw
= tk
->raw_time
;
391 ts_real
->tv_sec
= tk
->xtime_sec
;
392 ts_real
->tv_nsec
= 0;
394 nsecs_raw
= timekeeping_get_ns_raw(tk
);
395 nsecs_real
= timekeeping_get_ns(tk
);
397 } while (read_seqretry(&tk
->lock
, seq
));
399 timespec_add_ns(ts_raw
, nsecs_raw
);
400 timespec_add_ns(ts_real
, nsecs_real
);
402 EXPORT_SYMBOL(getnstime_raw_and_real
);
404 #endif /* CONFIG_NTP_PPS */
407 * do_gettimeofday - Returns the time of day in a timeval
408 * @tv: pointer to the timeval to be set
410 * NOTE: Users should be converted to using getnstimeofday()
412 void do_gettimeofday(struct timeval
*tv
)
416 getnstimeofday(&now
);
417 tv
->tv_sec
= now
.tv_sec
;
418 tv
->tv_usec
= now
.tv_nsec
/1000;
420 EXPORT_SYMBOL(do_gettimeofday
);
423 * do_settimeofday - Sets the time of day
424 * @tv: pointer to the timespec variable containing the new time
426 * Sets the time of day to the new time and update NTP and notify hrtimers
428 int do_settimeofday(const struct timespec
*tv
)
430 struct timekeeper
*tk
= &timekeeper
;
431 struct timespec ts_delta
, xt
;
434 if (!timespec_valid_strict(tv
))
437 write_seqlock_irqsave(&tk
->lock
, flags
);
439 timekeeping_forward_now(tk
);
442 ts_delta
.tv_sec
= tv
->tv_sec
- xt
.tv_sec
;
443 ts_delta
.tv_nsec
= tv
->tv_nsec
- xt
.tv_nsec
;
445 tk_set_wall_to_mono(tk
, timespec_sub(tk
->wall_to_monotonic
, ts_delta
));
447 tk_set_xtime(tk
, tv
);
449 timekeeping_update(tk
, true);
451 write_sequnlock_irqrestore(&tk
->lock
, flags
);
453 /* signal hrtimers about time change */
458 EXPORT_SYMBOL(do_settimeofday
);
461 * timekeeping_inject_offset - Adds or subtracts from the current time.
462 * @tv: pointer to the timespec variable containing the offset
464 * Adds or subtracts an offset value from the current time.
466 int timekeeping_inject_offset(struct timespec
*ts
)
468 struct timekeeper
*tk
= &timekeeper
;
473 if ((unsigned long)ts
->tv_nsec
>= NSEC_PER_SEC
)
476 write_seqlock_irqsave(&tk
->lock
, flags
);
478 timekeeping_forward_now(tk
);
480 /* Make sure the proposed value is valid */
481 tmp
= timespec_add(tk_xtime(tk
), *ts
);
482 if (!timespec_valid_strict(&tmp
)) {
487 tk_xtime_add(tk
, ts
);
488 tk_set_wall_to_mono(tk
, timespec_sub(tk
->wall_to_monotonic
, *ts
));
490 error
: /* even if we error out, we forwarded the time, so call update */
491 timekeeping_update(tk
, true);
493 write_sequnlock_irqrestore(&tk
->lock
, flags
);
495 /* signal hrtimers about time change */
500 EXPORT_SYMBOL(timekeeping_inject_offset
);
503 * change_clocksource - Swaps clocksources if a new one is available
505 * Accumulates current time interval and initializes new clocksource
507 static int change_clocksource(void *data
)
509 struct timekeeper
*tk
= &timekeeper
;
510 struct clocksource
*new, *old
;
513 new = (struct clocksource
*) data
;
515 write_seqlock_irqsave(&tk
->lock
, flags
);
517 timekeeping_forward_now(tk
);
518 if (!new->enable
|| new->enable(new) == 0) {
520 tk_setup_internals(tk
, new);
524 timekeeping_update(tk
, true);
526 write_sequnlock_irqrestore(&tk
->lock
, flags
);
532 * timekeeping_notify - Install a new clock source
533 * @clock: pointer to the clock source
535 * This function is called from clocksource.c after a new, better clock
536 * source has been registered. The caller holds the clocksource_mutex.
538 void timekeeping_notify(struct clocksource
*clock
)
540 struct timekeeper
*tk
= &timekeeper
;
542 if (tk
->clock
== clock
)
544 stop_machine(change_clocksource
, clock
, NULL
);
549 * ktime_get_real - get the real (wall-) time in ktime_t format
551 * returns the time in ktime_t format
553 ktime_t
ktime_get_real(void)
557 getnstimeofday(&now
);
559 return timespec_to_ktime(now
);
561 EXPORT_SYMBOL_GPL(ktime_get_real
);
564 * getrawmonotonic - Returns the raw monotonic time in a timespec
565 * @ts: pointer to the timespec to be set
567 * Returns the raw monotonic time (completely un-modified by ntp)
569 void getrawmonotonic(struct timespec
*ts
)
571 struct timekeeper
*tk
= &timekeeper
;
576 seq
= read_seqbegin(&tk
->lock
);
577 nsecs
= timekeeping_get_ns_raw(tk
);
580 } while (read_seqretry(&tk
->lock
, seq
));
582 timespec_add_ns(ts
, nsecs
);
584 EXPORT_SYMBOL(getrawmonotonic
);
587 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
589 int timekeeping_valid_for_hres(void)
591 struct timekeeper
*tk
= &timekeeper
;
596 seq
= read_seqbegin(&tk
->lock
);
598 ret
= tk
->clock
->flags
& CLOCK_SOURCE_VALID_FOR_HRES
;
600 } while (read_seqretry(&tk
->lock
, seq
));
606 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
608 u64
timekeeping_max_deferment(void)
610 struct timekeeper
*tk
= &timekeeper
;
615 seq
= read_seqbegin(&tk
->lock
);
617 ret
= tk
->clock
->max_idle_ns
;
619 } while (read_seqretry(&tk
->lock
, seq
));
625 * read_persistent_clock - Return time from the persistent clock.
627 * Weak dummy function for arches that do not yet support it.
628 * Reads the time from the battery backed persistent clock.
629 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
631 * XXX - Do be sure to remove it once all arches implement it.
633 void __attribute__((weak
)) read_persistent_clock(struct timespec
*ts
)
640 * read_boot_clock - Return time of the system start.
642 * Weak dummy function for arches that do not yet support it.
643 * Function to read the exact time the system has been started.
644 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
646 * XXX - Do be sure to remove it once all arches implement it.
648 void __attribute__((weak
)) read_boot_clock(struct timespec
*ts
)
655 * timekeeping_init - Initializes the clocksource and common timekeeping values
657 void __init
timekeeping_init(void)
659 struct timekeeper
*tk
= &timekeeper
;
660 struct clocksource
*clock
;
662 struct timespec now
, boot
, tmp
;
664 read_persistent_clock(&now
);
666 if (!timespec_valid_strict(&now
)) {
667 pr_warn("WARNING: Persistent clock returned invalid value!\n"
668 " Check your CMOS/BIOS settings.\n");
671 } else if (now
.tv_sec
|| now
.tv_nsec
)
672 persistent_clock_exist
= true;
674 read_boot_clock(&boot
);
675 if (!timespec_valid_strict(&boot
)) {
676 pr_warn("WARNING: Boot clock returned invalid value!\n"
677 " Check your CMOS/BIOS settings.\n");
682 seqlock_init(&tk
->lock
);
686 write_seqlock_irqsave(&tk
->lock
, flags
);
687 clock
= clocksource_default_clock();
689 clock
->enable(clock
);
690 tk_setup_internals(tk
, clock
);
692 tk_set_xtime(tk
, &now
);
693 tk
->raw_time
.tv_sec
= 0;
694 tk
->raw_time
.tv_nsec
= 0;
695 if (boot
.tv_sec
== 0 && boot
.tv_nsec
== 0)
698 set_normalized_timespec(&tmp
, -boot
.tv_sec
, -boot
.tv_nsec
);
699 tk_set_wall_to_mono(tk
, tmp
);
703 tk_set_sleep_time(tk
, tmp
);
705 write_sequnlock_irqrestore(&tk
->lock
, flags
);
708 /* time in seconds when suspend began */
709 static struct timespec timekeeping_suspend_time
;
712 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
713 * @delta: pointer to a timespec delta value
715 * Takes a timespec offset measuring a suspend interval and properly
716 * adds the sleep offset to the timekeeping variables.
718 static void __timekeeping_inject_sleeptime(struct timekeeper
*tk
,
719 struct timespec
*delta
)
721 if (!timespec_valid_strict(delta
)) {
722 printk(KERN_WARNING
"__timekeeping_inject_sleeptime: Invalid "
723 "sleep delta value!\n");
726 tk_xtime_add(tk
, delta
);
727 tk_set_wall_to_mono(tk
, timespec_sub(tk
->wall_to_monotonic
, *delta
));
728 tk_set_sleep_time(tk
, timespec_add(tk
->total_sleep_time
, *delta
));
732 * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
733 * @delta: pointer to a timespec delta value
735 * This hook is for architectures that cannot support read_persistent_clock
736 * because their RTC/persistent clock is only accessible when irqs are enabled.
738 * This function should only be called by rtc_resume(), and allows
739 * a suspend offset to be injected into the timekeeping values.
741 void timekeeping_inject_sleeptime(struct timespec
*delta
)
743 struct timekeeper
*tk
= &timekeeper
;
747 * Make sure we don't set the clock twice, as timekeeping_resume()
750 if (has_persistent_clock())
753 write_seqlock_irqsave(&tk
->lock
, flags
);
755 timekeeping_forward_now(tk
);
757 __timekeeping_inject_sleeptime(tk
, delta
);
759 timekeeping_update(tk
, true);
761 write_sequnlock_irqrestore(&tk
->lock
, flags
);
763 /* signal hrtimers about time change */
768 * timekeeping_resume - Resumes the generic timekeeping subsystem.
770 * This is for the generic clocksource timekeeping.
771 * xtime/wall_to_monotonic/jiffies/etc are
772 * still managed by arch specific suspend/resume code.
774 static void timekeeping_resume(void)
776 struct timekeeper
*tk
= &timekeeper
;
780 read_persistent_clock(&ts
);
782 clockevents_resume();
783 clocksource_resume();
785 write_seqlock_irqsave(&tk
->lock
, flags
);
787 if (timespec_compare(&ts
, &timekeeping_suspend_time
) > 0) {
788 ts
= timespec_sub(ts
, timekeeping_suspend_time
);
789 __timekeeping_inject_sleeptime(tk
, &ts
);
791 /* re-base the last cycle value */
792 tk
->clock
->cycle_last
= tk
->clock
->read(tk
->clock
);
794 timekeeping_suspended
= 0;
795 timekeeping_update(tk
, false);
796 write_sequnlock_irqrestore(&tk
->lock
, flags
);
798 touch_softlockup_watchdog();
800 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME
, NULL
);
802 /* Resume hrtimers */
806 static int timekeeping_suspend(void)
808 struct timekeeper
*tk
= &timekeeper
;
810 struct timespec delta
, delta_delta
;
811 static struct timespec old_delta
;
813 read_persistent_clock(&timekeeping_suspend_time
);
815 write_seqlock_irqsave(&tk
->lock
, flags
);
816 timekeeping_forward_now(tk
);
817 timekeeping_suspended
= 1;
820 * To avoid drift caused by repeated suspend/resumes,
821 * which each can add ~1 second drift error,
822 * try to compensate so the difference in system time
823 * and persistent_clock time stays close to constant.
825 delta
= timespec_sub(tk_xtime(tk
), timekeeping_suspend_time
);
826 delta_delta
= timespec_sub(delta
, old_delta
);
827 if (abs(delta_delta
.tv_sec
) >= 2) {
829 * if delta_delta is too large, assume time correction
830 * has occured and set old_delta to the current delta.
834 /* Otherwise try to adjust old_system to compensate */
835 timekeeping_suspend_time
=
836 timespec_add(timekeeping_suspend_time
, delta_delta
);
838 write_sequnlock_irqrestore(&tk
->lock
, flags
);
840 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND
, NULL
);
841 clocksource_suspend();
842 clockevents_suspend();
847 /* sysfs resume/suspend bits for timekeeping */
848 static struct syscore_ops timekeeping_syscore_ops
= {
849 .resume
= timekeeping_resume
,
850 .suspend
= timekeeping_suspend
,
853 static int __init
timekeeping_init_ops(void)
855 register_syscore_ops(&timekeeping_syscore_ops
);
859 device_initcall(timekeeping_init_ops
);
862 * If the error is already larger, we look ahead even further
863 * to compensate for late or lost adjustments.
865 static __always_inline
int timekeeping_bigadjust(struct timekeeper
*tk
,
866 s64 error
, s64
*interval
,
874 * Use the current error value to determine how much to look ahead.
875 * The larger the error the slower we adjust for it to avoid problems
876 * with losing too many ticks, otherwise we would overadjust and
877 * produce an even larger error. The smaller the adjustment the
878 * faster we try to adjust for it, as lost ticks can do less harm
879 * here. This is tuned so that an error of about 1 msec is adjusted
880 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
882 error2
= tk
->ntp_error
>> (NTP_SCALE_SHIFT
+ 22 - 2 * SHIFT_HZ
);
883 error2
= abs(error2
);
884 for (look_ahead
= 0; error2
> 0; look_ahead
++)
888 * Now calculate the error in (1 << look_ahead) ticks, but first
889 * remove the single look ahead already included in the error.
891 tick_error
= ntp_tick_length() >> (tk
->ntp_error_shift
+ 1);
892 tick_error
-= tk
->xtime_interval
>> 1;
893 error
= ((error
- tick_error
) >> look_ahead
) + tick_error
;
895 /* Finally calculate the adjustment shift value. */
900 *interval
= -*interval
;
904 for (adj
= 0; error
> i
; adj
++)
913 * Adjust the multiplier to reduce the error value,
914 * this is optimized for the most common adjustments of -1,0,1,
915 * for other values we can do a bit more work.
917 static void timekeeping_adjust(struct timekeeper
*tk
, s64 offset
)
919 s64 error
, interval
= tk
->cycle_interval
;
923 * The point of this is to check if the error is greater than half
926 * First we shift it down from NTP_SHIFT to clocksource->shifted nsecs.
928 * Note we subtract one in the shift, so that error is really error*2.
929 * This "saves" dividing(shifting) interval twice, but keeps the
930 * (error > interval) comparison as still measuring if error is
931 * larger than half an interval.
933 * Note: It does not "save" on aggravation when reading the code.
935 error
= tk
->ntp_error
>> (tk
->ntp_error_shift
- 1);
936 if (error
> interval
) {
938 * We now divide error by 4(via shift), which checks if
939 * the error is greater than twice the interval.
940 * If it is greater, we need a bigadjust, if its smaller,
941 * we can adjust by 1.
945 * XXX - In update_wall_time, we round up to the next
946 * nanosecond, and store the amount rounded up into
947 * the error. This causes the likely below to be unlikely.
949 * The proper fix is to avoid rounding up by using
950 * the high precision tk->xtime_nsec instead of
951 * xtime.tv_nsec everywhere. Fixing this will take some
954 if (likely(error
<= interval
))
957 adj
= timekeeping_bigadjust(tk
, error
, &interval
, &offset
);
959 if (error
< -interval
) {
960 /* See comment above, this is just switched for the negative */
962 if (likely(error
>= -interval
)) {
964 interval
= -interval
;
967 adj
= timekeeping_bigadjust(tk
, error
, &interval
, &offset
);
974 if (unlikely(tk
->clock
->maxadj
&&
975 (tk
->mult
+ adj
> tk
->clock
->mult
+ tk
->clock
->maxadj
))) {
976 printk_once(KERN_WARNING
977 "Adjusting %s more than 11%% (%ld vs %ld)\n",
978 tk
->clock
->name
, (long)tk
->mult
+ adj
,
979 (long)tk
->clock
->mult
+ tk
->clock
->maxadj
);
982 * So the following can be confusing.
984 * To keep things simple, lets assume adj == 1 for now.
986 * When adj != 1, remember that the interval and offset values
987 * have been appropriately scaled so the math is the same.
989 * The basic idea here is that we're increasing the multiplier
990 * by one, this causes the xtime_interval to be incremented by
991 * one cycle_interval. This is because:
992 * xtime_interval = cycle_interval * mult
993 * So if mult is being incremented by one:
994 * xtime_interval = cycle_interval * (mult + 1)
996 * xtime_interval = (cycle_interval * mult) + cycle_interval
997 * Which can be shortened to:
998 * xtime_interval += cycle_interval
1000 * So offset stores the non-accumulated cycles. Thus the current
1001 * time (in shifted nanoseconds) is:
1002 * now = (offset * adj) + xtime_nsec
1003 * Now, even though we're adjusting the clock frequency, we have
1004 * to keep time consistent. In other words, we can't jump back
1005 * in time, and we also want to avoid jumping forward in time.
1007 * So given the same offset value, we need the time to be the same
1008 * both before and after the freq adjustment.
1009 * now = (offset * adj_1) + xtime_nsec_1
1010 * now = (offset * adj_2) + xtime_nsec_2
1012 * (offset * adj_1) + xtime_nsec_1 =
1013 * (offset * adj_2) + xtime_nsec_2
1017 * (offset * adj_1) + xtime_nsec_1 =
1018 * (offset * (adj_1+1)) + xtime_nsec_2
1019 * (offset * adj_1) + xtime_nsec_1 =
1020 * (offset * adj_1) + offset + xtime_nsec_2
1021 * Canceling the sides:
1022 * xtime_nsec_1 = offset + xtime_nsec_2
1024 * xtime_nsec_2 = xtime_nsec_1 - offset
1025 * Which simplfies to:
1026 * xtime_nsec -= offset
1028 * XXX - TODO: Doc ntp_error calculation.
1031 tk
->xtime_interval
+= interval
;
1032 tk
->xtime_nsec
-= offset
;
1033 tk
->ntp_error
-= (interval
- offset
) << tk
->ntp_error_shift
;
1037 * It may be possible that when we entered this function, xtime_nsec
1038 * was very small. Further, if we're slightly speeding the clocksource
1039 * in the code above, its possible the required corrective factor to
1040 * xtime_nsec could cause it to underflow.
1042 * Now, since we already accumulated the second, cannot simply roll
1043 * the accumulated second back, since the NTP subsystem has been
1044 * notified via second_overflow. So instead we push xtime_nsec forward
1045 * by the amount we underflowed, and add that amount into the error.
1047 * We'll correct this error next time through this function, when
1048 * xtime_nsec is not as small.
1050 if (unlikely((s64
)tk
->xtime_nsec
< 0)) {
1051 s64 neg
= -(s64
)tk
->xtime_nsec
;
1053 tk
->ntp_error
+= neg
<< tk
->ntp_error_shift
;
1059 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1061 * Helper function that accumulates a the nsecs greater then a second
1062 * from the xtime_nsec field to the xtime_secs field.
1063 * It also calls into the NTP code to handle leapsecond processing.
1066 static inline void accumulate_nsecs_to_secs(struct timekeeper
*tk
)
1068 u64 nsecps
= (u64
)NSEC_PER_SEC
<< tk
->shift
;
1070 while (tk
->xtime_nsec
>= nsecps
) {
1073 tk
->xtime_nsec
-= nsecps
;
1076 /* Figure out if its a leap sec and apply if needed */
1077 leap
= second_overflow(tk
->xtime_sec
);
1078 if (unlikely(leap
)) {
1081 tk
->xtime_sec
+= leap
;
1085 tk_set_wall_to_mono(tk
,
1086 timespec_sub(tk
->wall_to_monotonic
, ts
));
1088 clock_was_set_delayed();
1094 * logarithmic_accumulation - shifted accumulation of cycles
1096 * This functions accumulates a shifted interval of cycles into
1097 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1100 * Returns the unconsumed cycles.
1102 static cycle_t
logarithmic_accumulation(struct timekeeper
*tk
, cycle_t offset
,
1107 /* If the offset is smaller then a shifted interval, do nothing */
1108 if (offset
< tk
->cycle_interval
<<shift
)
1111 /* Accumulate one shifted interval */
1112 offset
-= tk
->cycle_interval
<< shift
;
1113 tk
->clock
->cycle_last
+= tk
->cycle_interval
<< shift
;
1115 tk
->xtime_nsec
+= tk
->xtime_interval
<< shift
;
1116 accumulate_nsecs_to_secs(tk
);
1118 /* Accumulate raw time */
1119 raw_nsecs
= (u64
)tk
->raw_interval
<< shift
;
1120 raw_nsecs
+= tk
->raw_time
.tv_nsec
;
1121 if (raw_nsecs
>= NSEC_PER_SEC
) {
1122 u64 raw_secs
= raw_nsecs
;
1123 raw_nsecs
= do_div(raw_secs
, NSEC_PER_SEC
);
1124 tk
->raw_time
.tv_sec
+= raw_secs
;
1126 tk
->raw_time
.tv_nsec
= raw_nsecs
;
1128 /* Accumulate error between NTP and clock interval */
1129 tk
->ntp_error
+= ntp_tick_length() << shift
;
1130 tk
->ntp_error
-= (tk
->xtime_interval
+ tk
->xtime_remainder
) <<
1131 (tk
->ntp_error_shift
+ shift
);
1136 #ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
1137 static inline void old_vsyscall_fixup(struct timekeeper
*tk
)
1142 * Store only full nanoseconds into xtime_nsec after rounding
1143 * it up and add the remainder to the error difference.
1144 * XXX - This is necessary to avoid small 1ns inconsistnecies caused
1145 * by truncating the remainder in vsyscalls. However, it causes
1146 * additional work to be done in timekeeping_adjust(). Once
1147 * the vsyscall implementations are converted to use xtime_nsec
1148 * (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
1149 * users are removed, this can be killed.
1151 remainder
= tk
->xtime_nsec
& ((1ULL << tk
->shift
) - 1);
1152 tk
->xtime_nsec
-= remainder
;
1153 tk
->xtime_nsec
+= 1ULL << tk
->shift
;
1154 tk
->ntp_error
+= remainder
<< tk
->ntp_error_shift
;
1158 #define old_vsyscall_fixup(tk)
1164 * update_wall_time - Uses the current clocksource to increment the wall time
1167 static void update_wall_time(void)
1169 struct clocksource
*clock
;
1170 struct timekeeper
*tk
= &timekeeper
;
1172 int shift
= 0, maxshift
;
1173 unsigned long flags
;
1175 write_seqlock_irqsave(&tk
->lock
, flags
);
1177 /* Make sure we're fully resumed: */
1178 if (unlikely(timekeeping_suspended
))
1183 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1184 offset
= tk
->cycle_interval
;
1186 offset
= (clock
->read(clock
) - clock
->cycle_last
) & clock
->mask
;
1189 /* Check if there's really nothing to do */
1190 if (offset
< tk
->cycle_interval
)
1194 * With NO_HZ we may have to accumulate many cycle_intervals
1195 * (think "ticks") worth of time at once. To do this efficiently,
1196 * we calculate the largest doubling multiple of cycle_intervals
1197 * that is smaller than the offset. We then accumulate that
1198 * chunk in one go, and then try to consume the next smaller
1201 shift
= ilog2(offset
) - ilog2(tk
->cycle_interval
);
1202 shift
= max(0, shift
);
1203 /* Bound shift to one less than what overflows tick_length */
1204 maxshift
= (64 - (ilog2(ntp_tick_length())+1)) - 1;
1205 shift
= min(shift
, maxshift
);
1206 while (offset
>= tk
->cycle_interval
) {
1207 offset
= logarithmic_accumulation(tk
, offset
, shift
);
1208 if (offset
< tk
->cycle_interval
<<shift
)
1212 /* correct the clock when NTP error is too big */
1213 timekeeping_adjust(tk
, offset
);
1216 * XXX This can be killed once everyone converts
1217 * to the new update_vsyscall.
1219 old_vsyscall_fixup(tk
);
1222 * Finally, make sure that after the rounding
1223 * xtime_nsec isn't larger than NSEC_PER_SEC
1225 accumulate_nsecs_to_secs(tk
);
1227 timekeeping_update(tk
, false);
1230 write_sequnlock_irqrestore(&tk
->lock
, flags
);
1235 * getboottime - Return the real time of system boot.
1236 * @ts: pointer to the timespec to be set
1238 * Returns the wall-time of boot in a timespec.
1240 * This is based on the wall_to_monotonic offset and the total suspend
1241 * time. Calls to settimeofday will affect the value returned (which
1242 * basically means that however wrong your real time clock is at boot time,
1243 * you get the right time here).
1245 void getboottime(struct timespec
*ts
)
1247 struct timekeeper
*tk
= &timekeeper
;
1248 struct timespec boottime
= {
1249 .tv_sec
= tk
->wall_to_monotonic
.tv_sec
+
1250 tk
->total_sleep_time
.tv_sec
,
1251 .tv_nsec
= tk
->wall_to_monotonic
.tv_nsec
+
1252 tk
->total_sleep_time
.tv_nsec
1255 set_normalized_timespec(ts
, -boottime
.tv_sec
, -boottime
.tv_nsec
);
1257 EXPORT_SYMBOL_GPL(getboottime
);
1260 * get_monotonic_boottime - Returns monotonic time since boot
1261 * @ts: pointer to the timespec to be set
1263 * Returns the monotonic time since boot in a timespec.
1265 * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
1266 * includes the time spent in suspend.
1268 void get_monotonic_boottime(struct timespec
*ts
)
1270 struct timekeeper
*tk
= &timekeeper
;
1271 struct timespec tomono
, sleep
;
1275 WARN_ON(timekeeping_suspended
);
1278 seq
= read_seqbegin(&tk
->lock
);
1279 ts
->tv_sec
= tk
->xtime_sec
;
1280 nsec
= timekeeping_get_ns(tk
);
1281 tomono
= tk
->wall_to_monotonic
;
1282 sleep
= tk
->total_sleep_time
;
1284 } while (read_seqretry(&tk
->lock
, seq
));
1286 ts
->tv_sec
+= tomono
.tv_sec
+ sleep
.tv_sec
;
1288 timespec_add_ns(ts
, nsec
+ tomono
.tv_nsec
+ sleep
.tv_nsec
);
1290 EXPORT_SYMBOL_GPL(get_monotonic_boottime
);
1293 * ktime_get_boottime - Returns monotonic time since boot in a ktime
1295 * Returns the monotonic time since boot in a ktime
1297 * This is similar to CLOCK_MONTONIC/ktime_get, but also
1298 * includes the time spent in suspend.
1300 ktime_t
ktime_get_boottime(void)
1304 get_monotonic_boottime(&ts
);
1305 return timespec_to_ktime(ts
);
1307 EXPORT_SYMBOL_GPL(ktime_get_boottime
);
1310 * monotonic_to_bootbased - Convert the monotonic time to boot based.
1311 * @ts: pointer to the timespec to be converted
1313 void monotonic_to_bootbased(struct timespec
*ts
)
1315 struct timekeeper
*tk
= &timekeeper
;
1317 *ts
= timespec_add(*ts
, tk
->total_sleep_time
);
1319 EXPORT_SYMBOL_GPL(monotonic_to_bootbased
);
1321 unsigned long get_seconds(void)
1323 struct timekeeper
*tk
= &timekeeper
;
1325 return tk
->xtime_sec
;
1327 EXPORT_SYMBOL(get_seconds
);
1329 struct timespec
__current_kernel_time(void)
1331 struct timekeeper
*tk
= &timekeeper
;
1333 return tk_xtime(tk
);
1336 struct timespec
current_kernel_time(void)
1338 struct timekeeper
*tk
= &timekeeper
;
1339 struct timespec now
;
1343 seq
= read_seqbegin(&tk
->lock
);
1346 } while (read_seqretry(&tk
->lock
, seq
));
1350 EXPORT_SYMBOL(current_kernel_time
);
1352 struct timespec
get_monotonic_coarse(void)
1354 struct timekeeper
*tk
= &timekeeper
;
1355 struct timespec now
, mono
;
1359 seq
= read_seqbegin(&tk
->lock
);
1362 mono
= tk
->wall_to_monotonic
;
1363 } while (read_seqretry(&tk
->lock
, seq
));
1365 set_normalized_timespec(&now
, now
.tv_sec
+ mono
.tv_sec
,
1366 now
.tv_nsec
+ mono
.tv_nsec
);
1371 * Must hold jiffies_lock
1373 void do_timer(unsigned long ticks
)
1375 jiffies_64
+= ticks
;
1377 calc_global_load(ticks
);
1381 * get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic,
1382 * and sleep offsets.
1383 * @xtim: pointer to timespec to be set with xtime
1384 * @wtom: pointer to timespec to be set with wall_to_monotonic
1385 * @sleep: pointer to timespec to be set with time in suspend
1387 void get_xtime_and_monotonic_and_sleep_offset(struct timespec
*xtim
,
1388 struct timespec
*wtom
, struct timespec
*sleep
)
1390 struct timekeeper
*tk
= &timekeeper
;
1394 seq
= read_seqbegin(&tk
->lock
);
1395 *xtim
= tk_xtime(tk
);
1396 *wtom
= tk
->wall_to_monotonic
;
1397 *sleep
= tk
->total_sleep_time
;
1398 } while (read_seqretry(&tk
->lock
, seq
));
1401 #ifdef CONFIG_HIGH_RES_TIMERS
1403 * ktime_get_update_offsets - hrtimer helper
1404 * @offs_real: pointer to storage for monotonic -> realtime offset
1405 * @offs_boot: pointer to storage for monotonic -> boottime offset
1407 * Returns current monotonic time and updates the offsets
1408 * Called from hrtimer_interupt() or retrigger_next_event()
1410 ktime_t
ktime_get_update_offsets(ktime_t
*offs_real
, ktime_t
*offs_boot
)
1412 struct timekeeper
*tk
= &timekeeper
;
1418 seq
= read_seqbegin(&tk
->lock
);
1420 secs
= tk
->xtime_sec
;
1421 nsecs
= timekeeping_get_ns(tk
);
1423 *offs_real
= tk
->offs_real
;
1424 *offs_boot
= tk
->offs_boot
;
1425 } while (read_seqretry(&tk
->lock
, seq
));
1427 now
= ktime_add_ns(ktime_set(secs
, 0), nsecs
);
1428 now
= ktime_sub(now
, *offs_real
);
1434 * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
1436 ktime_t
ktime_get_monotonic_offset(void)
1438 struct timekeeper
*tk
= &timekeeper
;
1440 struct timespec wtom
;
1443 seq
= read_seqbegin(&tk
->lock
);
1444 wtom
= tk
->wall_to_monotonic
;
1445 } while (read_seqretry(&tk
->lock
, seq
));
1447 return timespec_to_ktime(wtom
);
1449 EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset
);
1452 * xtime_update() - advances the timekeeping infrastructure
1453 * @ticks: number of ticks, that have elapsed since the last call.
1455 * Must be called with interrupts disabled.
1457 void xtime_update(unsigned long ticks
)
1459 write_seqlock(&jiffies_lock
);
1461 write_sequnlock(&jiffies_lock
);