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/module.h>
12 #include <linux/interrupt.h>
13 #include <linux/percpu.h>
14 #include <linux/init.h>
16 #include <linux/sched.h>
17 #include <linux/sysdev.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>
24 /* Structure holding internal timekeeping values. */
26 /* Current clocksource used for timekeeping. */
27 struct clocksource
*clock
;
28 /* The shift value of the current clocksource. */
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. */
35 /* shifted nano seconds left over when rounding cycle_interval */
37 /* Raw nano seconds accumulated per NTP interval. */
40 /* Clock shifted nano seconds remainder not stored in xtime.tv_nsec. */
42 /* Difference between accumulated time and NTP time in ntp
43 * shifted nano seconds. */
45 /* Shift conversion between clock shifted nano seconds and
46 * ntp shifted nano seconds. */
48 /* NTP adjusted clock multiplier */
52 struct timekeeper timekeeper
;
55 * timekeeper_setup_internals - Set up internals to use clocksource clock.
57 * @clock: Pointer to clocksource.
59 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
60 * pair and interval request.
62 * Unless you're the timekeeping code, you should not be using this!
64 static void timekeeper_setup_internals(struct clocksource
*clock
)
69 timekeeper
.clock
= clock
;
70 clock
->cycle_last
= clock
->read(clock
);
72 /* Do the ns -> cycle conversion first, using original mult */
73 tmp
= NTP_INTERVAL_LENGTH
;
77 do_div(tmp
, clock
->mult
);
81 interval
= (cycle_t
) tmp
;
82 timekeeper
.cycle_interval
= interval
;
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
;
90 timekeeper
.xtime_nsec
= 0;
91 timekeeper
.shift
= clock
->shift
;
93 timekeeper
.ntp_error
= 0;
94 timekeeper
.ntp_error_shift
= NTP_SCALE_SHIFT
- clock
->shift
;
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.
101 timekeeper
.mult
= clock
->mult
;
104 /* Timekeeper helper functions. */
105 static inline s64
timekeeping_get_ns(void)
107 cycle_t cycle_now
, cycle_delta
;
108 struct clocksource
*clock
;
110 /* read clocksource: */
111 clock
= timekeeper
.clock
;
112 cycle_now
= clock
->read(clock
);
114 /* calculate the delta since the last update_wall_time: */
115 cycle_delta
= (cycle_now
- clock
->cycle_last
) & clock
->mask
;
117 /* return delta convert to nanoseconds using ntp adjusted mult. */
118 return clocksource_cyc2ns(cycle_delta
, timekeeper
.mult
,
122 static inline s64
timekeeping_get_ns_raw(void)
124 cycle_t cycle_now
, cycle_delta
;
125 struct clocksource
*clock
;
127 /* read clocksource: */
128 clock
= timekeeper
.clock
;
129 cycle_now
= clock
->read(clock
);
131 /* calculate the delta since the last update_wall_time: */
132 cycle_delta
= (cycle_now
- clock
->cycle_last
) & clock
->mask
;
134 /* return delta convert to nanoseconds using ntp adjusted mult. */
135 return clocksource_cyc2ns(cycle_delta
, clock
->mult
, clock
->shift
);
139 * This read-write spinlock protects us from races in SMP while
140 * playing with xtime.
142 __cacheline_aligned_in_smp
DEFINE_SEQLOCK(xtime_lock
);
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.
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.
157 * - wall_to_monotonic is no longer the boot time, getboottime must be
160 struct timespec xtime
__attribute__ ((aligned (16)));
161 struct timespec wall_to_monotonic
__attribute__ ((aligned (16)));
162 static struct timespec total_sleep_time
;
165 * The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock.
167 struct timespec raw_time
;
169 /* flag for if timekeeping is suspended */
170 int __read_mostly timekeeping_suspended
;
172 static struct timespec xtime_cache
__attribute__ ((aligned (16)));
173 void update_xtime_cache(u64 nsec
)
176 * Use temporary variable so get_seconds() cannot catch
177 * an intermediate xtime_cache.tv_sec value.
178 * The ACCESS_ONCE() keeps the compiler from optimizing
179 * out the intermediate value.
181 struct timespec ts
= xtime
;
182 timespec_add_ns(&ts
, nsec
);
183 ACCESS_ONCE(xtime_cache
) = ts
;
186 /* must hold xtime_lock */
187 void timekeeping_leap_insert(int leapsecond
)
189 xtime
.tv_sec
+= leapsecond
;
190 wall_to_monotonic
.tv_sec
-= leapsecond
;
191 update_vsyscall(&xtime
, timekeeper
.clock
, timekeeper
.mult
);
194 #ifdef CONFIG_GENERIC_TIME
197 * timekeeping_forward_now - update clock to the current time
199 * Forward the current clock to update its state since the last call to
200 * update_wall_time(). This is useful before significant clock changes,
201 * as it avoids having to deal with this time offset explicitly.
203 static void timekeeping_forward_now(void)
205 cycle_t cycle_now
, cycle_delta
;
206 struct clocksource
*clock
;
209 clock
= timekeeper
.clock
;
210 cycle_now
= clock
->read(clock
);
211 cycle_delta
= (cycle_now
- clock
->cycle_last
) & clock
->mask
;
212 clock
->cycle_last
= cycle_now
;
214 nsec
= clocksource_cyc2ns(cycle_delta
, timekeeper
.mult
,
217 /* If arch requires, add in gettimeoffset() */
218 nsec
+= arch_gettimeoffset();
220 timespec_add_ns(&xtime
, nsec
);
222 nsec
= clocksource_cyc2ns(cycle_delta
, clock
->mult
, clock
->shift
);
223 timespec_add_ns(&raw_time
, nsec
);
227 * getnstimeofday - Returns the time of day in a timespec
228 * @ts: pointer to the timespec to be set
230 * Returns the time of day in a timespec.
232 void getnstimeofday(struct timespec
*ts
)
237 WARN_ON(timekeeping_suspended
);
240 seq
= read_seqbegin(&xtime_lock
);
243 nsecs
= timekeeping_get_ns();
245 /* If arch requires, add in gettimeoffset() */
246 nsecs
+= arch_gettimeoffset();
248 } while (read_seqretry(&xtime_lock
, seq
));
250 timespec_add_ns(ts
, nsecs
);
253 EXPORT_SYMBOL(getnstimeofday
);
255 ktime_t
ktime_get(void)
260 WARN_ON(timekeeping_suspended
);
263 seq
= read_seqbegin(&xtime_lock
);
264 secs
= xtime
.tv_sec
+ wall_to_monotonic
.tv_sec
;
265 nsecs
= xtime
.tv_nsec
+ wall_to_monotonic
.tv_nsec
;
266 nsecs
+= timekeeping_get_ns();
267 /* If arch requires, add in gettimeoffset() */
268 nsecs
+= arch_gettimeoffset();
270 } while (read_seqretry(&xtime_lock
, seq
));
272 * Use ktime_set/ktime_add_ns to create a proper ktime on
273 * 32-bit architectures without CONFIG_KTIME_SCALAR.
275 return ktime_add_ns(ktime_set(secs
, 0), nsecs
);
277 EXPORT_SYMBOL_GPL(ktime_get
);
280 * ktime_get_ts - get the monotonic clock in timespec format
281 * @ts: pointer to timespec variable
283 * The function calculates the monotonic clock from the realtime
284 * clock and the wall_to_monotonic offset and stores the result
285 * in normalized timespec format in the variable pointed to by @ts.
287 void ktime_get_ts(struct timespec
*ts
)
289 struct timespec tomono
;
293 WARN_ON(timekeeping_suspended
);
296 seq
= read_seqbegin(&xtime_lock
);
298 tomono
= wall_to_monotonic
;
299 nsecs
= timekeeping_get_ns();
300 /* If arch requires, add in gettimeoffset() */
301 nsecs
+= arch_gettimeoffset();
303 } while (read_seqretry(&xtime_lock
, seq
));
305 set_normalized_timespec(ts
, ts
->tv_sec
+ tomono
.tv_sec
,
306 ts
->tv_nsec
+ tomono
.tv_nsec
+ nsecs
);
308 EXPORT_SYMBOL_GPL(ktime_get_ts
);
311 * do_gettimeofday - Returns the time of day in a timeval
312 * @tv: pointer to the timeval to be set
314 * NOTE: Users should be converted to using getnstimeofday()
316 void do_gettimeofday(struct timeval
*tv
)
320 getnstimeofday(&now
);
321 tv
->tv_sec
= now
.tv_sec
;
322 tv
->tv_usec
= now
.tv_nsec
/1000;
325 EXPORT_SYMBOL(do_gettimeofday
);
327 * do_settimeofday - Sets the time of day
328 * @tv: pointer to the timespec variable containing the new time
330 * Sets the time of day to the new time and update NTP and notify hrtimers
332 int do_settimeofday(struct timespec
*tv
)
334 struct timespec ts_delta
;
337 if ((unsigned long)tv
->tv_nsec
>= NSEC_PER_SEC
)
340 write_seqlock_irqsave(&xtime_lock
, flags
);
342 timekeeping_forward_now();
344 ts_delta
.tv_sec
= tv
->tv_sec
- xtime
.tv_sec
;
345 ts_delta
.tv_nsec
= tv
->tv_nsec
- xtime
.tv_nsec
;
346 wall_to_monotonic
= timespec_sub(wall_to_monotonic
, ts_delta
);
350 update_xtime_cache(0);
352 timekeeper
.ntp_error
= 0;
355 update_vsyscall(&xtime
, timekeeper
.clock
, timekeeper
.mult
);
357 write_sequnlock_irqrestore(&xtime_lock
, flags
);
359 /* signal hrtimers about time change */
365 EXPORT_SYMBOL(do_settimeofday
);
368 * change_clocksource - Swaps clocksources if a new one is available
370 * Accumulates current time interval and initializes new clocksource
372 static int change_clocksource(void *data
)
374 struct clocksource
*new, *old
;
376 new = (struct clocksource
*) data
;
378 timekeeping_forward_now();
379 if (!new->enable
|| new->enable(new) == 0) {
380 old
= timekeeper
.clock
;
381 timekeeper_setup_internals(new);
389 * timekeeping_notify - Install a new clock source
390 * @clock: pointer to the clock source
392 * This function is called from clocksource.c after a new, better clock
393 * source has been registered. The caller holds the clocksource_mutex.
395 void timekeeping_notify(struct clocksource
*clock
)
397 if (timekeeper
.clock
== clock
)
399 stop_machine(change_clocksource
, clock
, NULL
);
403 #else /* GENERIC_TIME */
405 static inline void timekeeping_forward_now(void) { }
408 * ktime_get - get the monotonic time in ktime_t format
410 * returns the time in ktime_t format
412 ktime_t
ktime_get(void)
418 return timespec_to_ktime(now
);
420 EXPORT_SYMBOL_GPL(ktime_get
);
423 * ktime_get_ts - get the monotonic clock in timespec format
424 * @ts: pointer to timespec variable
426 * The function calculates the monotonic clock from the realtime
427 * clock and the wall_to_monotonic offset and stores the result
428 * in normalized timespec format in the variable pointed to by @ts.
430 void ktime_get_ts(struct timespec
*ts
)
432 struct timespec tomono
;
436 seq
= read_seqbegin(&xtime_lock
);
438 tomono
= wall_to_monotonic
;
440 } while (read_seqretry(&xtime_lock
, seq
));
442 set_normalized_timespec(ts
, ts
->tv_sec
+ tomono
.tv_sec
,
443 ts
->tv_nsec
+ tomono
.tv_nsec
);
445 EXPORT_SYMBOL_GPL(ktime_get_ts
);
447 #endif /* !GENERIC_TIME */
450 * ktime_get_real - get the real (wall-) time in ktime_t format
452 * returns the time in ktime_t format
454 ktime_t
ktime_get_real(void)
458 getnstimeofday(&now
);
460 return timespec_to_ktime(now
);
462 EXPORT_SYMBOL_GPL(ktime_get_real
);
465 * getrawmonotonic - Returns the raw monotonic time in a timespec
466 * @ts: pointer to the timespec to be set
468 * Returns the raw monotonic time (completely un-modified by ntp)
470 void getrawmonotonic(struct timespec
*ts
)
476 seq
= read_seqbegin(&xtime_lock
);
477 nsecs
= timekeeping_get_ns_raw();
480 } while (read_seqretry(&xtime_lock
, seq
));
482 timespec_add_ns(ts
, nsecs
);
484 EXPORT_SYMBOL(getrawmonotonic
);
488 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
490 int timekeeping_valid_for_hres(void)
496 seq
= read_seqbegin(&xtime_lock
);
498 ret
= timekeeper
.clock
->flags
& CLOCK_SOURCE_VALID_FOR_HRES
;
500 } while (read_seqretry(&xtime_lock
, seq
));
506 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
508 * Caller must observe xtime_lock via read_seqbegin/read_seqretry to
509 * ensure that the clocksource does not change!
511 u64
timekeeping_max_deferment(void)
513 return timekeeper
.clock
->max_idle_ns
;
517 * read_persistent_clock - Return time from the persistent clock.
519 * Weak dummy function for arches that do not yet support it.
520 * Reads the time from the battery backed persistent clock.
521 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
523 * XXX - Do be sure to remove it once all arches implement it.
525 void __attribute__((weak
)) read_persistent_clock(struct timespec
*ts
)
532 * read_boot_clock - Return time of the system start.
534 * Weak dummy function for arches that do not yet support it.
535 * Function to read the exact time the system has been started.
536 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
538 * XXX - Do be sure to remove it once all arches implement it.
540 void __attribute__((weak
)) read_boot_clock(struct timespec
*ts
)
547 * timekeeping_init - Initializes the clocksource and common timekeeping values
549 void __init
timekeeping_init(void)
551 struct clocksource
*clock
;
553 struct timespec now
, boot
;
555 read_persistent_clock(&now
);
556 read_boot_clock(&boot
);
558 write_seqlock_irqsave(&xtime_lock
, flags
);
562 clock
= clocksource_default_clock();
564 clock
->enable(clock
);
565 timekeeper_setup_internals(clock
);
567 xtime
.tv_sec
= now
.tv_sec
;
568 xtime
.tv_nsec
= now
.tv_nsec
;
570 raw_time
.tv_nsec
= 0;
571 if (boot
.tv_sec
== 0 && boot
.tv_nsec
== 0) {
572 boot
.tv_sec
= xtime
.tv_sec
;
573 boot
.tv_nsec
= xtime
.tv_nsec
;
575 set_normalized_timespec(&wall_to_monotonic
,
576 -boot
.tv_sec
, -boot
.tv_nsec
);
577 update_xtime_cache(0);
578 total_sleep_time
.tv_sec
= 0;
579 total_sleep_time
.tv_nsec
= 0;
580 write_sequnlock_irqrestore(&xtime_lock
, flags
);
583 /* time in seconds when suspend began */
584 static struct timespec timekeeping_suspend_time
;
587 * timekeeping_resume - Resumes the generic timekeeping subsystem.
590 * This is for the generic clocksource timekeeping.
591 * xtime/wall_to_monotonic/jiffies/etc are
592 * still managed by arch specific suspend/resume code.
594 static int timekeeping_resume(struct sys_device
*dev
)
599 read_persistent_clock(&ts
);
601 clocksource_resume();
603 write_seqlock_irqsave(&xtime_lock
, flags
);
605 if (timespec_compare(&ts
, &timekeeping_suspend_time
) > 0) {
606 ts
= timespec_sub(ts
, timekeeping_suspend_time
);
607 xtime
= timespec_add_safe(xtime
, ts
);
608 wall_to_monotonic
= timespec_sub(wall_to_monotonic
, ts
);
609 total_sleep_time
= timespec_add_safe(total_sleep_time
, ts
);
611 update_xtime_cache(0);
612 /* re-base the last cycle value */
613 timekeeper
.clock
->cycle_last
= timekeeper
.clock
->read(timekeeper
.clock
);
614 timekeeper
.ntp_error
= 0;
615 timekeeping_suspended
= 0;
616 write_sequnlock_irqrestore(&xtime_lock
, flags
);
618 touch_softlockup_watchdog();
620 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME
, NULL
);
622 /* Resume hrtimers */
623 hres_timers_resume();
628 static int timekeeping_suspend(struct sys_device
*dev
, pm_message_t state
)
632 read_persistent_clock(&timekeeping_suspend_time
);
634 write_seqlock_irqsave(&xtime_lock
, flags
);
635 timekeeping_forward_now();
636 timekeeping_suspended
= 1;
637 write_sequnlock_irqrestore(&xtime_lock
, flags
);
639 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND
, NULL
);
644 /* sysfs resume/suspend bits for timekeeping */
645 static struct sysdev_class timekeeping_sysclass
= {
646 .name
= "timekeeping",
647 .resume
= timekeeping_resume
,
648 .suspend
= timekeeping_suspend
,
651 static struct sys_device device_timer
= {
653 .cls
= &timekeeping_sysclass
,
656 static int __init
timekeeping_init_device(void)
658 int error
= sysdev_class_register(&timekeeping_sysclass
);
660 error
= sysdev_register(&device_timer
);
664 device_initcall(timekeeping_init_device
);
667 * If the error is already larger, we look ahead even further
668 * to compensate for late or lost adjustments.
670 static __always_inline
int timekeeping_bigadjust(s64 error
, s64
*interval
,
678 * Use the current error value to determine how much to look ahead.
679 * The larger the error the slower we adjust for it to avoid problems
680 * with losing too many ticks, otherwise we would overadjust and
681 * produce an even larger error. The smaller the adjustment the
682 * faster we try to adjust for it, as lost ticks can do less harm
683 * here. This is tuned so that an error of about 1 msec is adjusted
684 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
686 error2
= timekeeper
.ntp_error
>> (NTP_SCALE_SHIFT
+ 22 - 2 * SHIFT_HZ
);
687 error2
= abs(error2
);
688 for (look_ahead
= 0; error2
> 0; look_ahead
++)
692 * Now calculate the error in (1 << look_ahead) ticks, but first
693 * remove the single look ahead already included in the error.
695 tick_error
= tick_length
>> (timekeeper
.ntp_error_shift
+ 1);
696 tick_error
-= timekeeper
.xtime_interval
>> 1;
697 error
= ((error
- tick_error
) >> look_ahead
) + tick_error
;
699 /* Finally calculate the adjustment shift value. */
704 *interval
= -*interval
;
708 for (adj
= 0; error
> i
; adj
++)
717 * Adjust the multiplier to reduce the error value,
718 * this is optimized for the most common adjustments of -1,0,1,
719 * for other values we can do a bit more work.
721 static void timekeeping_adjust(s64 offset
)
723 s64 error
, interval
= timekeeper
.cycle_interval
;
726 error
= timekeeper
.ntp_error
>> (timekeeper
.ntp_error_shift
- 1);
727 if (error
> interval
) {
729 if (likely(error
<= interval
))
732 adj
= timekeeping_bigadjust(error
, &interval
, &offset
);
733 } else if (error
< -interval
) {
735 if (likely(error
>= -interval
)) {
737 interval
= -interval
;
740 adj
= timekeeping_bigadjust(error
, &interval
, &offset
);
744 timekeeper
.mult
+= adj
;
745 timekeeper
.xtime_interval
+= interval
;
746 timekeeper
.xtime_nsec
-= offset
;
747 timekeeper
.ntp_error
-= (interval
- offset
) <<
748 timekeeper
.ntp_error_shift
;
752 * update_wall_time - Uses the current clocksource to increment the wall time
754 * Called from the timer interrupt, must hold a write on xtime_lock.
756 void update_wall_time(void)
758 struct clocksource
*clock
;
762 /* Make sure we're fully resumed: */
763 if (unlikely(timekeeping_suspended
))
766 clock
= timekeeper
.clock
;
767 #ifdef CONFIG_GENERIC_TIME
768 offset
= (clock
->read(clock
) - clock
->cycle_last
) & clock
->mask
;
770 offset
= timekeeper
.cycle_interval
;
772 timekeeper
.xtime_nsec
= (s64
)xtime
.tv_nsec
<< timekeeper
.shift
;
774 /* normally this loop will run just once, however in the
775 * case of lost or late ticks, it will accumulate correctly.
777 while (offset
>= timekeeper
.cycle_interval
) {
778 u64 nsecps
= (u64
)NSEC_PER_SEC
<< timekeeper
.shift
;
780 /* accumulate one interval */
781 offset
-= timekeeper
.cycle_interval
;
782 clock
->cycle_last
+= timekeeper
.cycle_interval
;
784 timekeeper
.xtime_nsec
+= timekeeper
.xtime_interval
;
785 if (timekeeper
.xtime_nsec
>= nsecps
) {
786 timekeeper
.xtime_nsec
-= nsecps
;
791 raw_time
.tv_nsec
+= timekeeper
.raw_interval
;
792 if (raw_time
.tv_nsec
>= NSEC_PER_SEC
) {
793 raw_time
.tv_nsec
-= NSEC_PER_SEC
;
797 /* accumulate error between NTP and clock interval */
798 timekeeper
.ntp_error
+= tick_length
;
799 timekeeper
.ntp_error
-=
800 (timekeeper
.xtime_interval
+ timekeeper
.xtime_remainder
) <<
801 timekeeper
.ntp_error_shift
;
804 /* correct the clock when NTP error is too big */
805 timekeeping_adjust(offset
);
808 * Since in the loop above, we accumulate any amount of time
809 * in xtime_nsec over a second into xtime.tv_sec, its possible for
810 * xtime_nsec to be fairly small after the loop. Further, if we're
811 * slightly speeding the clocksource up in timekeeping_adjust(),
812 * its possible the required corrective factor to xtime_nsec could
813 * cause it to underflow.
815 * Now, we cannot simply roll the accumulated second back, since
816 * the NTP subsystem has been notified via second_overflow. So
817 * instead we push xtime_nsec forward by the amount we underflowed,
818 * and add that amount into the error.
820 * We'll correct this error next time through this function, when
821 * xtime_nsec is not as small.
823 if (unlikely((s64
)timekeeper
.xtime_nsec
< 0)) {
824 s64 neg
= -(s64
)timekeeper
.xtime_nsec
;
825 timekeeper
.xtime_nsec
= 0;
826 timekeeper
.ntp_error
+= neg
<< timekeeper
.ntp_error_shift
;
829 /* store full nanoseconds into xtime after rounding it up and
830 * add the remainder to the error difference.
832 xtime
.tv_nsec
= ((s64
) timekeeper
.xtime_nsec
>> timekeeper
.shift
) + 1;
833 timekeeper
.xtime_nsec
-= (s64
) xtime
.tv_nsec
<< timekeeper
.shift
;
834 timekeeper
.ntp_error
+= timekeeper
.xtime_nsec
<<
835 timekeeper
.ntp_error_shift
;
837 nsecs
= clocksource_cyc2ns(offset
, timekeeper
.mult
, timekeeper
.shift
);
838 update_xtime_cache(nsecs
);
840 /* check to see if there is a new clocksource to use */
841 update_vsyscall(&xtime
, timekeeper
.clock
, timekeeper
.mult
);
845 * getboottime - Return the real time of system boot.
846 * @ts: pointer to the timespec to be set
848 * Returns the time of day in a timespec.
850 * This is based on the wall_to_monotonic offset and the total suspend
851 * time. Calls to settimeofday will affect the value returned (which
852 * basically means that however wrong your real time clock is at boot time,
853 * you get the right time here).
855 void getboottime(struct timespec
*ts
)
857 struct timespec boottime
= {
858 .tv_sec
= wall_to_monotonic
.tv_sec
+ total_sleep_time
.tv_sec
,
859 .tv_nsec
= wall_to_monotonic
.tv_nsec
+ total_sleep_time
.tv_nsec
862 set_normalized_timespec(ts
, -boottime
.tv_sec
, -boottime
.tv_nsec
);
864 EXPORT_SYMBOL_GPL(getboottime
);
867 * monotonic_to_bootbased - Convert the monotonic time to boot based.
868 * @ts: pointer to the timespec to be converted
870 void monotonic_to_bootbased(struct timespec
*ts
)
872 *ts
= timespec_add_safe(*ts
, total_sleep_time
);
874 EXPORT_SYMBOL_GPL(monotonic_to_bootbased
);
876 unsigned long get_seconds(void)
878 return xtime_cache
.tv_sec
;
880 EXPORT_SYMBOL(get_seconds
);
882 struct timespec
__current_kernel_time(void)
887 struct timespec
current_kernel_time(void)
893 seq
= read_seqbegin(&xtime_lock
);
896 } while (read_seqretry(&xtime_lock
, seq
));
900 EXPORT_SYMBOL(current_kernel_time
);
902 struct timespec
get_monotonic_coarse(void)
904 struct timespec now
, mono
;
908 seq
= read_seqbegin(&xtime_lock
);
911 mono
= wall_to_monotonic
;
912 } while (read_seqretry(&xtime_lock
, seq
));
914 set_normalized_timespec(&now
, now
.tv_sec
+ mono
.tv_sec
,
915 now
.tv_nsec
+ mono
.tv_nsec
);