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. */
142 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
143 u32 (*arch_gettimeoffset
)(void);
145 u32
get_arch_timeoffset(void)
147 if (likely(arch_gettimeoffset
))
148 return arch_gettimeoffset();
152 static inline u32
get_arch_timeoffset(void) { return 0; }
155 static inline s64
timekeeping_get_ns(struct timekeeper
*tk
)
157 cycle_t cycle_now
, cycle_delta
;
158 struct clocksource
*clock
;
161 /* read clocksource: */
163 cycle_now
= clock
->read(clock
);
165 /* calculate the delta since the last update_wall_time: */
166 cycle_delta
= (cycle_now
- clock
->cycle_last
) & clock
->mask
;
168 nsec
= cycle_delta
* tk
->mult
+ tk
->xtime_nsec
;
171 /* If arch requires, add in get_arch_timeoffset() */
172 return nsec
+ get_arch_timeoffset();
175 static inline s64
timekeeping_get_ns_raw(struct timekeeper
*tk
)
177 cycle_t cycle_now
, cycle_delta
;
178 struct clocksource
*clock
;
181 /* read clocksource: */
183 cycle_now
= clock
->read(clock
);
185 /* calculate the delta since the last update_wall_time: */
186 cycle_delta
= (cycle_now
- clock
->cycle_last
) & clock
->mask
;
188 /* convert delta to nanoseconds. */
189 nsec
= clocksource_cyc2ns(cycle_delta
, clock
->mult
, clock
->shift
);
191 /* If arch requires, add in get_arch_timeoffset() */
192 return nsec
+ get_arch_timeoffset();
195 static RAW_NOTIFIER_HEAD(pvclock_gtod_chain
);
197 static void update_pvclock_gtod(struct timekeeper
*tk
)
199 raw_notifier_call_chain(&pvclock_gtod_chain
, 0, tk
);
203 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
205 * Must hold write on timekeeper.lock
207 int pvclock_gtod_register_notifier(struct notifier_block
*nb
)
209 struct timekeeper
*tk
= &timekeeper
;
213 write_seqlock_irqsave(&tk
->lock
, flags
);
214 ret
= raw_notifier_chain_register(&pvclock_gtod_chain
, nb
);
215 /* update timekeeping data */
216 update_pvclock_gtod(tk
);
217 write_sequnlock_irqrestore(&tk
->lock
, flags
);
221 EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier
);
224 * pvclock_gtod_unregister_notifier - unregister a pvclock
225 * timedata update listener
227 * Must hold write on timekeeper.lock
229 int pvclock_gtod_unregister_notifier(struct notifier_block
*nb
)
231 struct timekeeper
*tk
= &timekeeper
;
235 write_seqlock_irqsave(&tk
->lock
, flags
);
236 ret
= raw_notifier_chain_unregister(&pvclock_gtod_chain
, nb
);
237 write_sequnlock_irqrestore(&tk
->lock
, flags
);
241 EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier
);
243 /* must hold write on timekeeper.lock */
244 static void timekeeping_update(struct timekeeper
*tk
, bool clearntp
)
251 update_pvclock_gtod(tk
);
255 * timekeeping_forward_now - update clock to the current time
257 * Forward the current clock to update its state since the last call to
258 * update_wall_time(). This is useful before significant clock changes,
259 * as it avoids having to deal with this time offset explicitly.
261 static void timekeeping_forward_now(struct timekeeper
*tk
)
263 cycle_t cycle_now
, cycle_delta
;
264 struct clocksource
*clock
;
268 cycle_now
= clock
->read(clock
);
269 cycle_delta
= (cycle_now
- clock
->cycle_last
) & clock
->mask
;
270 clock
->cycle_last
= cycle_now
;
272 tk
->xtime_nsec
+= cycle_delta
* tk
->mult
;
274 /* If arch requires, add in get_arch_timeoffset() */
275 tk
->xtime_nsec
+= (u64
)get_arch_timeoffset() << tk
->shift
;
277 tk_normalize_xtime(tk
);
279 nsec
= clocksource_cyc2ns(cycle_delta
, clock
->mult
, clock
->shift
);
280 timespec_add_ns(&tk
->raw_time
, nsec
);
284 * __getnstimeofday - Returns the time of day in a timespec.
285 * @ts: pointer to the timespec to be set
287 * Updates the time of day in the timespec.
288 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
290 int __getnstimeofday(struct timespec
*ts
)
292 struct timekeeper
*tk
= &timekeeper
;
297 seq
= read_seqbegin(&tk
->lock
);
299 ts
->tv_sec
= tk
->xtime_sec
;
300 nsecs
= timekeeping_get_ns(tk
);
302 } while (read_seqretry(&tk
->lock
, seq
));
305 timespec_add_ns(ts
, nsecs
);
308 * Do not bail out early, in case there were callers still using
309 * the value, even in the face of the WARN_ON.
311 if (unlikely(timekeeping_suspended
))
315 EXPORT_SYMBOL(__getnstimeofday
);
318 * getnstimeofday - Returns the time of day in a timespec.
319 * @ts: pointer to the timespec to be set
321 * Returns the time of day in a timespec (WARN if suspended).
323 void getnstimeofday(struct timespec
*ts
)
325 WARN_ON(__getnstimeofday(ts
));
327 EXPORT_SYMBOL(getnstimeofday
);
329 ktime_t
ktime_get(void)
331 struct timekeeper
*tk
= &timekeeper
;
335 WARN_ON(timekeeping_suspended
);
338 seq
= read_seqbegin(&tk
->lock
);
339 secs
= tk
->xtime_sec
+ tk
->wall_to_monotonic
.tv_sec
;
340 nsecs
= timekeeping_get_ns(tk
) + tk
->wall_to_monotonic
.tv_nsec
;
342 } while (read_seqretry(&tk
->lock
, seq
));
344 * Use ktime_set/ktime_add_ns to create a proper ktime on
345 * 32-bit architectures without CONFIG_KTIME_SCALAR.
347 return ktime_add_ns(ktime_set(secs
, 0), nsecs
);
349 EXPORT_SYMBOL_GPL(ktime_get
);
352 * ktime_get_ts - get the monotonic clock in timespec format
353 * @ts: pointer to timespec variable
355 * The function calculates the monotonic clock from the realtime
356 * clock and the wall_to_monotonic offset and stores the result
357 * in normalized timespec format in the variable pointed to by @ts.
359 void ktime_get_ts(struct timespec
*ts
)
361 struct timekeeper
*tk
= &timekeeper
;
362 struct timespec tomono
;
366 WARN_ON(timekeeping_suspended
);
369 seq
= read_seqbegin(&tk
->lock
);
370 ts
->tv_sec
= tk
->xtime_sec
;
371 nsec
= timekeeping_get_ns(tk
);
372 tomono
= tk
->wall_to_monotonic
;
374 } while (read_seqretry(&tk
->lock
, seq
));
376 ts
->tv_sec
+= tomono
.tv_sec
;
378 timespec_add_ns(ts
, nsec
+ tomono
.tv_nsec
);
380 EXPORT_SYMBOL_GPL(ktime_get_ts
);
382 #ifdef CONFIG_NTP_PPS
385 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
386 * @ts_raw: pointer to the timespec to be set to raw monotonic time
387 * @ts_real: pointer to the timespec to be set to the time of day
389 * This function reads both the time of day and raw monotonic time at the
390 * same time atomically and stores the resulting timestamps in timespec
393 void getnstime_raw_and_real(struct timespec
*ts_raw
, struct timespec
*ts_real
)
395 struct timekeeper
*tk
= &timekeeper
;
397 s64 nsecs_raw
, nsecs_real
;
399 WARN_ON_ONCE(timekeeping_suspended
);
402 seq
= read_seqbegin(&tk
->lock
);
404 *ts_raw
= tk
->raw_time
;
405 ts_real
->tv_sec
= tk
->xtime_sec
;
406 ts_real
->tv_nsec
= 0;
408 nsecs_raw
= timekeeping_get_ns_raw(tk
);
409 nsecs_real
= timekeeping_get_ns(tk
);
411 } while (read_seqretry(&tk
->lock
, seq
));
413 timespec_add_ns(ts_raw
, nsecs_raw
);
414 timespec_add_ns(ts_real
, nsecs_real
);
416 EXPORT_SYMBOL(getnstime_raw_and_real
);
418 #endif /* CONFIG_NTP_PPS */
421 * do_gettimeofday - Returns the time of day in a timeval
422 * @tv: pointer to the timeval to be set
424 * NOTE: Users should be converted to using getnstimeofday()
426 void do_gettimeofday(struct timeval
*tv
)
430 getnstimeofday(&now
);
431 tv
->tv_sec
= now
.tv_sec
;
432 tv
->tv_usec
= now
.tv_nsec
/1000;
434 EXPORT_SYMBOL(do_gettimeofday
);
437 * do_settimeofday - Sets the time of day
438 * @tv: pointer to the timespec variable containing the new time
440 * Sets the time of day to the new time and update NTP and notify hrtimers
442 int do_settimeofday(const struct timespec
*tv
)
444 struct timekeeper
*tk
= &timekeeper
;
445 struct timespec ts_delta
, xt
;
448 if (!timespec_valid_strict(tv
))
451 write_seqlock_irqsave(&tk
->lock
, flags
);
453 timekeeping_forward_now(tk
);
456 ts_delta
.tv_sec
= tv
->tv_sec
- xt
.tv_sec
;
457 ts_delta
.tv_nsec
= tv
->tv_nsec
- xt
.tv_nsec
;
459 tk_set_wall_to_mono(tk
, timespec_sub(tk
->wall_to_monotonic
, ts_delta
));
461 tk_set_xtime(tk
, tv
);
463 timekeeping_update(tk
, true);
465 write_sequnlock_irqrestore(&tk
->lock
, flags
);
467 /* signal hrtimers about time change */
472 EXPORT_SYMBOL(do_settimeofday
);
475 * timekeeping_inject_offset - Adds or subtracts from the current time.
476 * @tv: pointer to the timespec variable containing the offset
478 * Adds or subtracts an offset value from the current time.
480 int timekeeping_inject_offset(struct timespec
*ts
)
482 struct timekeeper
*tk
= &timekeeper
;
487 if ((unsigned long)ts
->tv_nsec
>= NSEC_PER_SEC
)
490 write_seqlock_irqsave(&tk
->lock
, flags
);
492 timekeeping_forward_now(tk
);
494 /* Make sure the proposed value is valid */
495 tmp
= timespec_add(tk_xtime(tk
), *ts
);
496 if (!timespec_valid_strict(&tmp
)) {
501 tk_xtime_add(tk
, ts
);
502 tk_set_wall_to_mono(tk
, timespec_sub(tk
->wall_to_monotonic
, *ts
));
504 error
: /* even if we error out, we forwarded the time, so call update */
505 timekeeping_update(tk
, true);
507 write_sequnlock_irqrestore(&tk
->lock
, flags
);
509 /* signal hrtimers about time change */
514 EXPORT_SYMBOL(timekeeping_inject_offset
);
518 * timekeeping_get_tai_offset - Returns current TAI offset from UTC
521 s32
timekeeping_get_tai_offset(void)
523 struct timekeeper
*tk
= &timekeeper
;
528 seq
= read_seqbegin(&tk
->lock
);
529 ret
= tk
->tai_offset
;
530 } while (read_seqretry(&tk
->lock
, seq
));
536 * __timekeeping_set_tai_offset - Lock free worker function
539 void __timekeeping_set_tai_offset(struct timekeeper
*tk
, s32 tai_offset
)
541 tk
->tai_offset
= tai_offset
;
545 * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
548 void timekeeping_set_tai_offset(s32 tai_offset
)
550 struct timekeeper
*tk
= &timekeeper
;
553 write_seqlock_irqsave(&tk
->lock
, flags
);
554 __timekeeping_set_tai_offset(tk
, tai_offset
);
555 write_sequnlock_irqrestore(&tk
->lock
, flags
);
559 * change_clocksource - Swaps clocksources if a new one is available
561 * Accumulates current time interval and initializes new clocksource
563 static int change_clocksource(void *data
)
565 struct timekeeper
*tk
= &timekeeper
;
566 struct clocksource
*new, *old
;
569 new = (struct clocksource
*) data
;
571 write_seqlock_irqsave(&tk
->lock
, flags
);
573 timekeeping_forward_now(tk
);
574 if (!new->enable
|| new->enable(new) == 0) {
576 tk_setup_internals(tk
, new);
580 timekeeping_update(tk
, true);
582 write_sequnlock_irqrestore(&tk
->lock
, flags
);
588 * timekeeping_notify - Install a new clock source
589 * @clock: pointer to the clock source
591 * This function is called from clocksource.c after a new, better clock
592 * source has been registered. The caller holds the clocksource_mutex.
594 void timekeeping_notify(struct clocksource
*clock
)
596 struct timekeeper
*tk
= &timekeeper
;
598 if (tk
->clock
== clock
)
600 stop_machine(change_clocksource
, clock
, NULL
);
605 * ktime_get_real - get the real (wall-) time in ktime_t format
607 * returns the time in ktime_t format
609 ktime_t
ktime_get_real(void)
613 getnstimeofday(&now
);
615 return timespec_to_ktime(now
);
617 EXPORT_SYMBOL_GPL(ktime_get_real
);
620 * getrawmonotonic - Returns the raw monotonic time in a timespec
621 * @ts: pointer to the timespec to be set
623 * Returns the raw monotonic time (completely un-modified by ntp)
625 void getrawmonotonic(struct timespec
*ts
)
627 struct timekeeper
*tk
= &timekeeper
;
632 seq
= read_seqbegin(&tk
->lock
);
633 nsecs
= timekeeping_get_ns_raw(tk
);
636 } while (read_seqretry(&tk
->lock
, seq
));
638 timespec_add_ns(ts
, nsecs
);
640 EXPORT_SYMBOL(getrawmonotonic
);
643 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
645 int timekeeping_valid_for_hres(void)
647 struct timekeeper
*tk
= &timekeeper
;
652 seq
= read_seqbegin(&tk
->lock
);
654 ret
= tk
->clock
->flags
& CLOCK_SOURCE_VALID_FOR_HRES
;
656 } while (read_seqretry(&tk
->lock
, seq
));
662 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
664 u64
timekeeping_max_deferment(void)
666 struct timekeeper
*tk
= &timekeeper
;
671 seq
= read_seqbegin(&tk
->lock
);
673 ret
= tk
->clock
->max_idle_ns
;
675 } while (read_seqretry(&tk
->lock
, seq
));
681 * read_persistent_clock - Return time from the persistent clock.
683 * Weak dummy function for arches that do not yet support it.
684 * Reads the time from the battery backed persistent clock.
685 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
687 * XXX - Do be sure to remove it once all arches implement it.
689 void __attribute__((weak
)) read_persistent_clock(struct timespec
*ts
)
696 * read_boot_clock - Return time of the system start.
698 * Weak dummy function for arches that do not yet support it.
699 * Function to read the exact time the system has been started.
700 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
702 * XXX - Do be sure to remove it once all arches implement it.
704 void __attribute__((weak
)) read_boot_clock(struct timespec
*ts
)
711 * timekeeping_init - Initializes the clocksource and common timekeeping values
713 void __init
timekeeping_init(void)
715 struct timekeeper
*tk
= &timekeeper
;
716 struct clocksource
*clock
;
718 struct timespec now
, boot
, tmp
;
720 read_persistent_clock(&now
);
722 if (!timespec_valid_strict(&now
)) {
723 pr_warn("WARNING: Persistent clock returned invalid value!\n"
724 " Check your CMOS/BIOS settings.\n");
727 } else if (now
.tv_sec
|| now
.tv_nsec
)
728 persistent_clock_exist
= true;
730 read_boot_clock(&boot
);
731 if (!timespec_valid_strict(&boot
)) {
732 pr_warn("WARNING: Boot clock returned invalid value!\n"
733 " Check your CMOS/BIOS settings.\n");
738 seqlock_init(&tk
->lock
);
742 write_seqlock_irqsave(&tk
->lock
, flags
);
743 clock
= clocksource_default_clock();
745 clock
->enable(clock
);
746 tk_setup_internals(tk
, clock
);
748 tk_set_xtime(tk
, &now
);
749 tk
->raw_time
.tv_sec
= 0;
750 tk
->raw_time
.tv_nsec
= 0;
751 if (boot
.tv_sec
== 0 && boot
.tv_nsec
== 0)
754 set_normalized_timespec(&tmp
, -boot
.tv_sec
, -boot
.tv_nsec
);
755 tk_set_wall_to_mono(tk
, tmp
);
759 tk_set_sleep_time(tk
, tmp
);
761 write_sequnlock_irqrestore(&tk
->lock
, flags
);
764 /* time in seconds when suspend began */
765 static struct timespec timekeeping_suspend_time
;
768 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
769 * @delta: pointer to a timespec delta value
771 * Takes a timespec offset measuring a suspend interval and properly
772 * adds the sleep offset to the timekeeping variables.
774 static void __timekeeping_inject_sleeptime(struct timekeeper
*tk
,
775 struct timespec
*delta
)
777 if (!timespec_valid_strict(delta
)) {
778 printk(KERN_WARNING
"__timekeeping_inject_sleeptime: Invalid "
779 "sleep delta value!\n");
782 tk_xtime_add(tk
, delta
);
783 tk_set_wall_to_mono(tk
, timespec_sub(tk
->wall_to_monotonic
, *delta
));
784 tk_set_sleep_time(tk
, timespec_add(tk
->total_sleep_time
, *delta
));
788 * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
789 * @delta: pointer to a timespec delta value
791 * This hook is for architectures that cannot support read_persistent_clock
792 * because their RTC/persistent clock is only accessible when irqs are enabled.
794 * This function should only be called by rtc_resume(), and allows
795 * a suspend offset to be injected into the timekeeping values.
797 void timekeeping_inject_sleeptime(struct timespec
*delta
)
799 struct timekeeper
*tk
= &timekeeper
;
803 * Make sure we don't set the clock twice, as timekeeping_resume()
806 if (has_persistent_clock())
809 write_seqlock_irqsave(&tk
->lock
, flags
);
811 timekeeping_forward_now(tk
);
813 __timekeeping_inject_sleeptime(tk
, delta
);
815 timekeeping_update(tk
, true);
817 write_sequnlock_irqrestore(&tk
->lock
, flags
);
819 /* signal hrtimers about time change */
824 * timekeeping_resume - Resumes the generic timekeeping subsystem.
826 * This is for the generic clocksource timekeeping.
827 * xtime/wall_to_monotonic/jiffies/etc are
828 * still managed by arch specific suspend/resume code.
830 static void timekeeping_resume(void)
832 struct timekeeper
*tk
= &timekeeper
;
833 struct clocksource
*clock
= tk
->clock
;
835 struct timespec ts_new
, ts_delta
;
836 cycle_t cycle_now
, cycle_delta
;
837 bool suspendtime_found
= false;
839 read_persistent_clock(&ts_new
);
841 clockevents_resume();
842 clocksource_resume();
844 write_seqlock_irqsave(&tk
->lock
, flags
);
847 * After system resumes, we need to calculate the suspended time and
848 * compensate it for the OS time. There are 3 sources that could be
849 * used: Nonstop clocksource during suspend, persistent clock and rtc
852 * One specific platform may have 1 or 2 or all of them, and the
853 * preference will be:
854 * suspend-nonstop clocksource -> persistent clock -> rtc
855 * The less preferred source will only be tried if there is no better
856 * usable source. The rtc part is handled separately in rtc core code.
858 cycle_now
= clock
->read(clock
);
859 if ((clock
->flags
& CLOCK_SOURCE_SUSPEND_NONSTOP
) &&
860 cycle_now
> clock
->cycle_last
) {
861 u64 num
, max
= ULLONG_MAX
;
862 u32 mult
= clock
->mult
;
863 u32 shift
= clock
->shift
;
866 cycle_delta
= (cycle_now
- clock
->cycle_last
) & clock
->mask
;
869 * "cycle_delta * mutl" may cause 64 bits overflow, if the
870 * suspended time is too long. In that case we need do the
871 * 64 bits math carefully
874 if (cycle_delta
> max
) {
875 num
= div64_u64(cycle_delta
, max
);
876 nsec
= (((u64
) max
* mult
) >> shift
) * num
;
877 cycle_delta
-= num
* max
;
879 nsec
+= ((u64
) cycle_delta
* mult
) >> shift
;
881 ts_delta
= ns_to_timespec(nsec
);
882 suspendtime_found
= true;
883 } else if (timespec_compare(&ts_new
, &timekeeping_suspend_time
) > 0) {
884 ts_delta
= timespec_sub(ts_new
, timekeeping_suspend_time
);
885 suspendtime_found
= true;
888 if (suspendtime_found
)
889 __timekeeping_inject_sleeptime(tk
, &ts_delta
);
891 /* Re-base the last cycle value */
892 clock
->cycle_last
= cycle_now
;
894 timekeeping_suspended
= 0;
895 timekeeping_update(tk
, false);
896 write_sequnlock_irqrestore(&tk
->lock
, flags
);
898 touch_softlockup_watchdog();
900 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME
, NULL
);
902 /* Resume hrtimers */
906 static int timekeeping_suspend(void)
908 struct timekeeper
*tk
= &timekeeper
;
910 struct timespec delta
, delta_delta
;
911 static struct timespec old_delta
;
913 read_persistent_clock(&timekeeping_suspend_time
);
915 write_seqlock_irqsave(&tk
->lock
, flags
);
916 timekeeping_forward_now(tk
);
917 timekeeping_suspended
= 1;
920 * To avoid drift caused by repeated suspend/resumes,
921 * which each can add ~1 second drift error,
922 * try to compensate so the difference in system time
923 * and persistent_clock time stays close to constant.
925 delta
= timespec_sub(tk_xtime(tk
), timekeeping_suspend_time
);
926 delta_delta
= timespec_sub(delta
, old_delta
);
927 if (abs(delta_delta
.tv_sec
) >= 2) {
929 * if delta_delta is too large, assume time correction
930 * has occured and set old_delta to the current delta.
934 /* Otherwise try to adjust old_system to compensate */
935 timekeeping_suspend_time
=
936 timespec_add(timekeeping_suspend_time
, delta_delta
);
938 write_sequnlock_irqrestore(&tk
->lock
, flags
);
940 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND
, NULL
);
941 clocksource_suspend();
942 clockevents_suspend();
947 /* sysfs resume/suspend bits for timekeeping */
948 static struct syscore_ops timekeeping_syscore_ops
= {
949 .resume
= timekeeping_resume
,
950 .suspend
= timekeeping_suspend
,
953 static int __init
timekeeping_init_ops(void)
955 register_syscore_ops(&timekeeping_syscore_ops
);
959 device_initcall(timekeeping_init_ops
);
962 * If the error is already larger, we look ahead even further
963 * to compensate for late or lost adjustments.
965 static __always_inline
int timekeeping_bigadjust(struct timekeeper
*tk
,
966 s64 error
, s64
*interval
,
974 * Use the current error value to determine how much to look ahead.
975 * The larger the error the slower we adjust for it to avoid problems
976 * with losing too many ticks, otherwise we would overadjust and
977 * produce an even larger error. The smaller the adjustment the
978 * faster we try to adjust for it, as lost ticks can do less harm
979 * here. This is tuned so that an error of about 1 msec is adjusted
980 * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
982 error2
= tk
->ntp_error
>> (NTP_SCALE_SHIFT
+ 22 - 2 * SHIFT_HZ
);
983 error2
= abs(error2
);
984 for (look_ahead
= 0; error2
> 0; look_ahead
++)
988 * Now calculate the error in (1 << look_ahead) ticks, but first
989 * remove the single look ahead already included in the error.
991 tick_error
= ntp_tick_length() >> (tk
->ntp_error_shift
+ 1);
992 tick_error
-= tk
->xtime_interval
>> 1;
993 error
= ((error
- tick_error
) >> look_ahead
) + tick_error
;
995 /* Finally calculate the adjustment shift value. */
1000 *interval
= -*interval
;
1004 for (adj
= 0; error
> i
; adj
++)
1013 * Adjust the multiplier to reduce the error value,
1014 * this is optimized for the most common adjustments of -1,0,1,
1015 * for other values we can do a bit more work.
1017 static void timekeeping_adjust(struct timekeeper
*tk
, s64 offset
)
1019 s64 error
, interval
= tk
->cycle_interval
;
1023 * The point of this is to check if the error is greater than half
1026 * First we shift it down from NTP_SHIFT to clocksource->shifted nsecs.
1028 * Note we subtract one in the shift, so that error is really error*2.
1029 * This "saves" dividing(shifting) interval twice, but keeps the
1030 * (error > interval) comparison as still measuring if error is
1031 * larger than half an interval.
1033 * Note: It does not "save" on aggravation when reading the code.
1035 error
= tk
->ntp_error
>> (tk
->ntp_error_shift
- 1);
1036 if (error
> interval
) {
1038 * We now divide error by 4(via shift), which checks if
1039 * the error is greater than twice the interval.
1040 * If it is greater, we need a bigadjust, if its smaller,
1041 * we can adjust by 1.
1045 * XXX - In update_wall_time, we round up to the next
1046 * nanosecond, and store the amount rounded up into
1047 * the error. This causes the likely below to be unlikely.
1049 * The proper fix is to avoid rounding up by using
1050 * the high precision tk->xtime_nsec instead of
1051 * xtime.tv_nsec everywhere. Fixing this will take some
1054 if (likely(error
<= interval
))
1057 adj
= timekeeping_bigadjust(tk
, error
, &interval
, &offset
);
1059 if (error
< -interval
) {
1060 /* See comment above, this is just switched for the negative */
1062 if (likely(error
>= -interval
)) {
1064 interval
= -interval
;
1067 adj
= timekeeping_bigadjust(tk
, error
, &interval
, &offset
);
1074 if (unlikely(tk
->clock
->maxadj
&&
1075 (tk
->mult
+ adj
> tk
->clock
->mult
+ tk
->clock
->maxadj
))) {
1076 printk_once(KERN_WARNING
1077 "Adjusting %s more than 11%% (%ld vs %ld)\n",
1078 tk
->clock
->name
, (long)tk
->mult
+ adj
,
1079 (long)tk
->clock
->mult
+ tk
->clock
->maxadj
);
1082 * So the following can be confusing.
1084 * To keep things simple, lets assume adj == 1 for now.
1086 * When adj != 1, remember that the interval and offset values
1087 * have been appropriately scaled so the math is the same.
1089 * The basic idea here is that we're increasing the multiplier
1090 * by one, this causes the xtime_interval to be incremented by
1091 * one cycle_interval. This is because:
1092 * xtime_interval = cycle_interval * mult
1093 * So if mult is being incremented by one:
1094 * xtime_interval = cycle_interval * (mult + 1)
1096 * xtime_interval = (cycle_interval * mult) + cycle_interval
1097 * Which can be shortened to:
1098 * xtime_interval += cycle_interval
1100 * So offset stores the non-accumulated cycles. Thus the current
1101 * time (in shifted nanoseconds) is:
1102 * now = (offset * adj) + xtime_nsec
1103 * Now, even though we're adjusting the clock frequency, we have
1104 * to keep time consistent. In other words, we can't jump back
1105 * in time, and we also want to avoid jumping forward in time.
1107 * So given the same offset value, we need the time to be the same
1108 * both before and after the freq adjustment.
1109 * now = (offset * adj_1) + xtime_nsec_1
1110 * now = (offset * adj_2) + xtime_nsec_2
1112 * (offset * adj_1) + xtime_nsec_1 =
1113 * (offset * adj_2) + xtime_nsec_2
1117 * (offset * adj_1) + xtime_nsec_1 =
1118 * (offset * (adj_1+1)) + xtime_nsec_2
1119 * (offset * adj_1) + xtime_nsec_1 =
1120 * (offset * adj_1) + offset + xtime_nsec_2
1121 * Canceling the sides:
1122 * xtime_nsec_1 = offset + xtime_nsec_2
1124 * xtime_nsec_2 = xtime_nsec_1 - offset
1125 * Which simplfies to:
1126 * xtime_nsec -= offset
1128 * XXX - TODO: Doc ntp_error calculation.
1131 tk
->xtime_interval
+= interval
;
1132 tk
->xtime_nsec
-= offset
;
1133 tk
->ntp_error
-= (interval
- offset
) << tk
->ntp_error_shift
;
1137 * It may be possible that when we entered this function, xtime_nsec
1138 * was very small. Further, if we're slightly speeding the clocksource
1139 * in the code above, its possible the required corrective factor to
1140 * xtime_nsec could cause it to underflow.
1142 * Now, since we already accumulated the second, cannot simply roll
1143 * the accumulated second back, since the NTP subsystem has been
1144 * notified via second_overflow. So instead we push xtime_nsec forward
1145 * by the amount we underflowed, and add that amount into the error.
1147 * We'll correct this error next time through this function, when
1148 * xtime_nsec is not as small.
1150 if (unlikely((s64
)tk
->xtime_nsec
< 0)) {
1151 s64 neg
= -(s64
)tk
->xtime_nsec
;
1153 tk
->ntp_error
+= neg
<< tk
->ntp_error_shift
;
1159 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1161 * Helper function that accumulates a the nsecs greater then a second
1162 * from the xtime_nsec field to the xtime_secs field.
1163 * It also calls into the NTP code to handle leapsecond processing.
1166 static inline void accumulate_nsecs_to_secs(struct timekeeper
*tk
)
1168 u64 nsecps
= (u64
)NSEC_PER_SEC
<< tk
->shift
;
1170 while (tk
->xtime_nsec
>= nsecps
) {
1173 tk
->xtime_nsec
-= nsecps
;
1176 /* Figure out if its a leap sec and apply if needed */
1177 leap
= second_overflow(tk
->xtime_sec
);
1178 if (unlikely(leap
)) {
1181 tk
->xtime_sec
+= leap
;
1185 tk_set_wall_to_mono(tk
,
1186 timespec_sub(tk
->wall_to_monotonic
, ts
));
1188 __timekeeping_set_tai_offset(tk
, tk
->tai_offset
- leap
);
1190 clock_was_set_delayed();
1196 * logarithmic_accumulation - shifted accumulation of cycles
1198 * This functions accumulates a shifted interval of cycles into
1199 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1202 * Returns the unconsumed cycles.
1204 static cycle_t
logarithmic_accumulation(struct timekeeper
*tk
, cycle_t offset
,
1209 /* If the offset is smaller then a shifted interval, do nothing */
1210 if (offset
< tk
->cycle_interval
<<shift
)
1213 /* Accumulate one shifted interval */
1214 offset
-= tk
->cycle_interval
<< shift
;
1215 tk
->clock
->cycle_last
+= tk
->cycle_interval
<< shift
;
1217 tk
->xtime_nsec
+= tk
->xtime_interval
<< shift
;
1218 accumulate_nsecs_to_secs(tk
);
1220 /* Accumulate raw time */
1221 raw_nsecs
= (u64
)tk
->raw_interval
<< shift
;
1222 raw_nsecs
+= tk
->raw_time
.tv_nsec
;
1223 if (raw_nsecs
>= NSEC_PER_SEC
) {
1224 u64 raw_secs
= raw_nsecs
;
1225 raw_nsecs
= do_div(raw_secs
, NSEC_PER_SEC
);
1226 tk
->raw_time
.tv_sec
+= raw_secs
;
1228 tk
->raw_time
.tv_nsec
= raw_nsecs
;
1230 /* Accumulate error between NTP and clock interval */
1231 tk
->ntp_error
+= ntp_tick_length() << shift
;
1232 tk
->ntp_error
-= (tk
->xtime_interval
+ tk
->xtime_remainder
) <<
1233 (tk
->ntp_error_shift
+ shift
);
1238 #ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
1239 static inline void old_vsyscall_fixup(struct timekeeper
*tk
)
1244 * Store only full nanoseconds into xtime_nsec after rounding
1245 * it up and add the remainder to the error difference.
1246 * XXX - This is necessary to avoid small 1ns inconsistnecies caused
1247 * by truncating the remainder in vsyscalls. However, it causes
1248 * additional work to be done in timekeeping_adjust(). Once
1249 * the vsyscall implementations are converted to use xtime_nsec
1250 * (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
1251 * users are removed, this can be killed.
1253 remainder
= tk
->xtime_nsec
& ((1ULL << tk
->shift
) - 1);
1254 tk
->xtime_nsec
-= remainder
;
1255 tk
->xtime_nsec
+= 1ULL << tk
->shift
;
1256 tk
->ntp_error
+= remainder
<< tk
->ntp_error_shift
;
1260 #define old_vsyscall_fixup(tk)
1266 * update_wall_time - Uses the current clocksource to increment the wall time
1269 static void update_wall_time(void)
1271 struct clocksource
*clock
;
1272 struct timekeeper
*tk
= &timekeeper
;
1274 int shift
= 0, maxshift
;
1275 unsigned long flags
;
1277 write_seqlock_irqsave(&tk
->lock
, flags
);
1279 /* Make sure we're fully resumed: */
1280 if (unlikely(timekeeping_suspended
))
1285 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1286 offset
= tk
->cycle_interval
;
1288 offset
= (clock
->read(clock
) - clock
->cycle_last
) & clock
->mask
;
1291 /* Check if there's really nothing to do */
1292 if (offset
< tk
->cycle_interval
)
1296 * With NO_HZ we may have to accumulate many cycle_intervals
1297 * (think "ticks") worth of time at once. To do this efficiently,
1298 * we calculate the largest doubling multiple of cycle_intervals
1299 * that is smaller than the offset. We then accumulate that
1300 * chunk in one go, and then try to consume the next smaller
1303 shift
= ilog2(offset
) - ilog2(tk
->cycle_interval
);
1304 shift
= max(0, shift
);
1305 /* Bound shift to one less than what overflows tick_length */
1306 maxshift
= (64 - (ilog2(ntp_tick_length())+1)) - 1;
1307 shift
= min(shift
, maxshift
);
1308 while (offset
>= tk
->cycle_interval
) {
1309 offset
= logarithmic_accumulation(tk
, offset
, shift
);
1310 if (offset
< tk
->cycle_interval
<<shift
)
1314 /* correct the clock when NTP error is too big */
1315 timekeeping_adjust(tk
, offset
);
1318 * XXX This can be killed once everyone converts
1319 * to the new update_vsyscall.
1321 old_vsyscall_fixup(tk
);
1324 * Finally, make sure that after the rounding
1325 * xtime_nsec isn't larger than NSEC_PER_SEC
1327 accumulate_nsecs_to_secs(tk
);
1329 timekeeping_update(tk
, false);
1332 write_sequnlock_irqrestore(&tk
->lock
, flags
);
1337 * getboottime - Return the real time of system boot.
1338 * @ts: pointer to the timespec to be set
1340 * Returns the wall-time of boot in a timespec.
1342 * This is based on the wall_to_monotonic offset and the total suspend
1343 * time. Calls to settimeofday will affect the value returned (which
1344 * basically means that however wrong your real time clock is at boot time,
1345 * you get the right time here).
1347 void getboottime(struct timespec
*ts
)
1349 struct timekeeper
*tk
= &timekeeper
;
1350 struct timespec boottime
= {
1351 .tv_sec
= tk
->wall_to_monotonic
.tv_sec
+
1352 tk
->total_sleep_time
.tv_sec
,
1353 .tv_nsec
= tk
->wall_to_monotonic
.tv_nsec
+
1354 tk
->total_sleep_time
.tv_nsec
1357 set_normalized_timespec(ts
, -boottime
.tv_sec
, -boottime
.tv_nsec
);
1359 EXPORT_SYMBOL_GPL(getboottime
);
1362 * get_monotonic_boottime - Returns monotonic time since boot
1363 * @ts: pointer to the timespec to be set
1365 * Returns the monotonic time since boot in a timespec.
1367 * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
1368 * includes the time spent in suspend.
1370 void get_monotonic_boottime(struct timespec
*ts
)
1372 struct timekeeper
*tk
= &timekeeper
;
1373 struct timespec tomono
, sleep
;
1377 WARN_ON(timekeeping_suspended
);
1380 seq
= read_seqbegin(&tk
->lock
);
1381 ts
->tv_sec
= tk
->xtime_sec
;
1382 nsec
= timekeeping_get_ns(tk
);
1383 tomono
= tk
->wall_to_monotonic
;
1384 sleep
= tk
->total_sleep_time
;
1386 } while (read_seqretry(&tk
->lock
, seq
));
1388 ts
->tv_sec
+= tomono
.tv_sec
+ sleep
.tv_sec
;
1390 timespec_add_ns(ts
, nsec
+ tomono
.tv_nsec
+ sleep
.tv_nsec
);
1392 EXPORT_SYMBOL_GPL(get_monotonic_boottime
);
1395 * ktime_get_boottime - Returns monotonic time since boot in a ktime
1397 * Returns the monotonic time since boot in a ktime
1399 * This is similar to CLOCK_MONTONIC/ktime_get, but also
1400 * includes the time spent in suspend.
1402 ktime_t
ktime_get_boottime(void)
1406 get_monotonic_boottime(&ts
);
1407 return timespec_to_ktime(ts
);
1409 EXPORT_SYMBOL_GPL(ktime_get_boottime
);
1412 * monotonic_to_bootbased - Convert the monotonic time to boot based.
1413 * @ts: pointer to the timespec to be converted
1415 void monotonic_to_bootbased(struct timespec
*ts
)
1417 struct timekeeper
*tk
= &timekeeper
;
1419 *ts
= timespec_add(*ts
, tk
->total_sleep_time
);
1421 EXPORT_SYMBOL_GPL(monotonic_to_bootbased
);
1423 unsigned long get_seconds(void)
1425 struct timekeeper
*tk
= &timekeeper
;
1427 return tk
->xtime_sec
;
1429 EXPORT_SYMBOL(get_seconds
);
1431 struct timespec
__current_kernel_time(void)
1433 struct timekeeper
*tk
= &timekeeper
;
1435 return tk_xtime(tk
);
1438 struct timespec
current_kernel_time(void)
1440 struct timekeeper
*tk
= &timekeeper
;
1441 struct timespec now
;
1445 seq
= read_seqbegin(&tk
->lock
);
1448 } while (read_seqretry(&tk
->lock
, seq
));
1452 EXPORT_SYMBOL(current_kernel_time
);
1454 struct timespec
get_monotonic_coarse(void)
1456 struct timekeeper
*tk
= &timekeeper
;
1457 struct timespec now
, mono
;
1461 seq
= read_seqbegin(&tk
->lock
);
1464 mono
= tk
->wall_to_monotonic
;
1465 } while (read_seqretry(&tk
->lock
, seq
));
1467 set_normalized_timespec(&now
, now
.tv_sec
+ mono
.tv_sec
,
1468 now
.tv_nsec
+ mono
.tv_nsec
);
1473 * Must hold jiffies_lock
1475 void do_timer(unsigned long ticks
)
1477 jiffies_64
+= ticks
;
1479 calc_global_load(ticks
);
1483 * get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic,
1484 * and sleep offsets.
1485 * @xtim: pointer to timespec to be set with xtime
1486 * @wtom: pointer to timespec to be set with wall_to_monotonic
1487 * @sleep: pointer to timespec to be set with time in suspend
1489 void get_xtime_and_monotonic_and_sleep_offset(struct timespec
*xtim
,
1490 struct timespec
*wtom
, struct timespec
*sleep
)
1492 struct timekeeper
*tk
= &timekeeper
;
1496 seq
= read_seqbegin(&tk
->lock
);
1497 *xtim
= tk_xtime(tk
);
1498 *wtom
= tk
->wall_to_monotonic
;
1499 *sleep
= tk
->total_sleep_time
;
1500 } while (read_seqretry(&tk
->lock
, seq
));
1503 #ifdef CONFIG_HIGH_RES_TIMERS
1505 * ktime_get_update_offsets - hrtimer helper
1506 * @offs_real: pointer to storage for monotonic -> realtime offset
1507 * @offs_boot: pointer to storage for monotonic -> boottime offset
1509 * Returns current monotonic time and updates the offsets
1510 * Called from hrtimer_interupt() or retrigger_next_event()
1512 ktime_t
ktime_get_update_offsets(ktime_t
*offs_real
, ktime_t
*offs_boot
)
1514 struct timekeeper
*tk
= &timekeeper
;
1520 seq
= read_seqbegin(&tk
->lock
);
1522 secs
= tk
->xtime_sec
;
1523 nsecs
= timekeeping_get_ns(tk
);
1525 *offs_real
= tk
->offs_real
;
1526 *offs_boot
= tk
->offs_boot
;
1527 } while (read_seqretry(&tk
->lock
, seq
));
1529 now
= ktime_add_ns(ktime_set(secs
, 0), nsecs
);
1530 now
= ktime_sub(now
, *offs_real
);
1536 * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
1538 ktime_t
ktime_get_monotonic_offset(void)
1540 struct timekeeper
*tk
= &timekeeper
;
1542 struct timespec wtom
;
1545 seq
= read_seqbegin(&tk
->lock
);
1546 wtom
= tk
->wall_to_monotonic
;
1547 } while (read_seqretry(&tk
->lock
, seq
));
1549 return timespec_to_ktime(wtom
);
1551 EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset
);
1554 * xtime_update() - advances the timekeeping infrastructure
1555 * @ticks: number of ticks, that have elapsed since the last call.
1557 * Must be called with interrupts disabled.
1559 void xtime_update(unsigned long ticks
)
1561 write_seqlock(&jiffies_lock
);
1563 write_sequnlock(&jiffies_lock
);