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>
25 #include <linux/compiler.h>
27 #include "tick-internal.h"
28 #include "ntp_internal.h"
29 #include "timekeeping_internal.h"
31 #define TK_CLEAR_NTP (1 << 0)
32 #define TK_MIRROR (1 << 1)
33 #define TK_CLOCK_WAS_SET (1 << 2)
36 * The most important data for readout fits into a single 64 byte
41 struct timekeeper timekeeper
;
42 } tk_core ____cacheline_aligned
;
44 static DEFINE_RAW_SPINLOCK(timekeeper_lock
);
45 static struct timekeeper shadow_timekeeper
;
48 * struct tk_fast - NMI safe timekeeper
49 * @seq: Sequence counter for protecting updates. The lowest bit
50 * is the index for the tk_read_base array
51 * @base: tk_read_base array. Access is indexed by the lowest bit of
54 * See @update_fast_timekeeper() below.
58 struct tk_read_base base
[2];
61 static struct tk_fast tk_fast_mono ____cacheline_aligned
;
63 /* flag for if timekeeping is suspended */
64 int __read_mostly timekeeping_suspended
;
66 /* Flag for if there is a persistent clock on this platform */
67 bool __read_mostly persistent_clock_exist
= false;
69 static inline void tk_normalize_xtime(struct timekeeper
*tk
)
71 while (tk
->tkr
.xtime_nsec
>= ((u64
)NSEC_PER_SEC
<< tk
->tkr
.shift
)) {
72 tk
->tkr
.xtime_nsec
-= (u64
)NSEC_PER_SEC
<< tk
->tkr
.shift
;
77 static inline struct timespec64
tk_xtime(struct timekeeper
*tk
)
81 ts
.tv_sec
= tk
->xtime_sec
;
82 ts
.tv_nsec
= (long)(tk
->tkr
.xtime_nsec
>> tk
->tkr
.shift
);
86 static void tk_set_xtime(struct timekeeper
*tk
, const struct timespec64
*ts
)
88 tk
->xtime_sec
= ts
->tv_sec
;
89 tk
->tkr
.xtime_nsec
= (u64
)ts
->tv_nsec
<< tk
->tkr
.shift
;
92 static void tk_xtime_add(struct timekeeper
*tk
, const struct timespec64
*ts
)
94 tk
->xtime_sec
+= ts
->tv_sec
;
95 tk
->tkr
.xtime_nsec
+= (u64
)ts
->tv_nsec
<< tk
->tkr
.shift
;
96 tk_normalize_xtime(tk
);
99 static void tk_set_wall_to_mono(struct timekeeper
*tk
, struct timespec64 wtm
)
101 struct timespec64 tmp
;
104 * Verify consistency of: offset_real = -wall_to_monotonic
105 * before modifying anything
107 set_normalized_timespec64(&tmp
, -tk
->wall_to_monotonic
.tv_sec
,
108 -tk
->wall_to_monotonic
.tv_nsec
);
109 WARN_ON_ONCE(tk
->offs_real
.tv64
!= timespec64_to_ktime(tmp
).tv64
);
110 tk
->wall_to_monotonic
= wtm
;
111 set_normalized_timespec64(&tmp
, -wtm
.tv_sec
, -wtm
.tv_nsec
);
112 tk
->offs_real
= timespec64_to_ktime(tmp
);
113 tk
->offs_tai
= ktime_add(tk
->offs_real
, ktime_set(tk
->tai_offset
, 0));
116 static inline void tk_update_sleep_time(struct timekeeper
*tk
, ktime_t delta
)
118 tk
->offs_boot
= ktime_add(tk
->offs_boot
, delta
);
122 * tk_setup_internals - Set up internals to use clocksource clock.
124 * @tk: The target timekeeper to setup.
125 * @clock: Pointer to clocksource.
127 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
128 * pair and interval request.
130 * Unless you're the timekeeping code, you should not be using this!
132 static void tk_setup_internals(struct timekeeper
*tk
, struct clocksource
*clock
)
135 u64 tmp
, ntpinterval
;
136 struct clocksource
*old_clock
;
138 old_clock
= tk
->tkr
.clock
;
139 tk
->tkr
.clock
= clock
;
140 tk
->tkr
.read
= clock
->read
;
141 tk
->tkr
.mask
= clock
->mask
;
142 tk
->tkr
.cycle_last
= tk
->tkr
.read(clock
);
144 /* Do the ns -> cycle conversion first, using original mult */
145 tmp
= NTP_INTERVAL_LENGTH
;
146 tmp
<<= clock
->shift
;
148 tmp
+= clock
->mult
/2;
149 do_div(tmp
, clock
->mult
);
153 interval
= (cycle_t
) tmp
;
154 tk
->cycle_interval
= interval
;
156 /* Go back from cycles -> shifted ns */
157 tk
->xtime_interval
= (u64
) interval
* clock
->mult
;
158 tk
->xtime_remainder
= ntpinterval
- tk
->xtime_interval
;
160 ((u64
) interval
* clock
->mult
) >> clock
->shift
;
162 /* if changing clocks, convert xtime_nsec shift units */
164 int shift_change
= clock
->shift
- old_clock
->shift
;
165 if (shift_change
< 0)
166 tk
->tkr
.xtime_nsec
>>= -shift_change
;
168 tk
->tkr
.xtime_nsec
<<= shift_change
;
170 tk
->tkr
.shift
= clock
->shift
;
173 tk
->ntp_error_shift
= NTP_SCALE_SHIFT
- clock
->shift
;
174 tk
->ntp_tick
= ntpinterval
<< tk
->ntp_error_shift
;
177 * The timekeeper keeps its own mult values for the currently
178 * active clocksource. These value will be adjusted via NTP
179 * to counteract clock drifting.
181 tk
->tkr
.mult
= clock
->mult
;
182 tk
->ntp_err_mult
= 0;
185 /* Timekeeper helper functions. */
187 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
188 static u32
default_arch_gettimeoffset(void) { return 0; }
189 u32 (*arch_gettimeoffset
)(void) = default_arch_gettimeoffset
;
191 static inline u32
arch_gettimeoffset(void) { return 0; }
194 static inline s64
timekeeping_get_ns(struct tk_read_base
*tkr
)
196 cycle_t cycle_now
, delta
;
199 /* read clocksource: */
200 cycle_now
= tkr
->read(tkr
->clock
);
202 /* calculate the delta since the last update_wall_time: */
203 delta
= clocksource_delta(cycle_now
, tkr
->cycle_last
, tkr
->mask
);
205 nsec
= delta
* tkr
->mult
+ tkr
->xtime_nsec
;
208 /* If arch requires, add in get_arch_timeoffset() */
209 return nsec
+ arch_gettimeoffset();
212 static inline s64
timekeeping_get_ns_raw(struct timekeeper
*tk
)
214 struct clocksource
*clock
= tk
->tkr
.clock
;
215 cycle_t cycle_now
, delta
;
218 /* read clocksource: */
219 cycle_now
= tk
->tkr
.read(clock
);
221 /* calculate the delta since the last update_wall_time: */
222 delta
= clocksource_delta(cycle_now
, tk
->tkr
.cycle_last
, tk
->tkr
.mask
);
224 /* convert delta to nanoseconds. */
225 nsec
= clocksource_cyc2ns(delta
, clock
->mult
, clock
->shift
);
227 /* If arch requires, add in get_arch_timeoffset() */
228 return nsec
+ arch_gettimeoffset();
232 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
233 * @tk: The timekeeper from which we take the update
234 * @tkf: The fast timekeeper to update
235 * @tbase: The time base for the fast timekeeper (mono/raw)
237 * We want to use this from any context including NMI and tracing /
238 * instrumenting the timekeeping code itself.
240 * So we handle this differently than the other timekeeping accessor
241 * functions which retry when the sequence count has changed. The
244 * smp_wmb(); <- Ensure that the last base[1] update is visible
246 * smp_wmb(); <- Ensure that the seqcount update is visible
247 * update(tkf->base[0], tk);
248 * smp_wmb(); <- Ensure that the base[0] update is visible
250 * smp_wmb(); <- Ensure that the seqcount update is visible
251 * update(tkf->base[1], tk);
253 * The reader side does:
259 * now = now(tkf->base[idx]);
261 * } while (seq != tkf->seq)
263 * As long as we update base[0] readers are forced off to
264 * base[1]. Once base[0] is updated readers are redirected to base[0]
265 * and the base[1] update takes place.
267 * So if a NMI hits the update of base[0] then it will use base[1]
268 * which is still consistent. In the worst case this can result is a
269 * slightly wrong timestamp (a few nanoseconds). See
270 * @ktime_get_mono_fast_ns.
272 static void update_fast_timekeeper(struct timekeeper
*tk
)
274 struct tk_read_base
*base
= tk_fast_mono
.base
;
276 /* Force readers off to base[1] */
277 raw_write_seqcount_latch(&tk_fast_mono
.seq
);
280 memcpy(base
, &tk
->tkr
, sizeof(*base
));
282 /* Force readers back to base[0] */
283 raw_write_seqcount_latch(&tk_fast_mono
.seq
);
286 memcpy(base
+ 1, base
, sizeof(*base
));
290 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
292 * This timestamp is not guaranteed to be monotonic across an update.
293 * The timestamp is calculated by:
295 * now = base_mono + clock_delta * slope
297 * So if the update lowers the slope, readers who are forced to the
298 * not yet updated second array are still using the old steeper slope.
307 * |12345678---> reader order
313 * So reader 6 will observe time going backwards versus reader 5.
315 * While other CPUs are likely to be able observe that, the only way
316 * for a CPU local observation is when an NMI hits in the middle of
317 * the update. Timestamps taken from that NMI context might be ahead
318 * of the following timestamps. Callers need to be aware of that and
321 u64 notrace
ktime_get_mono_fast_ns(void)
323 struct tk_read_base
*tkr
;
328 seq
= raw_read_seqcount(&tk_fast_mono
.seq
);
329 tkr
= tk_fast_mono
.base
+ (seq
& 0x01);
330 now
= ktime_to_ns(tkr
->base_mono
) + timekeeping_get_ns(tkr
);
332 } while (read_seqcount_retry(&tk_fast_mono
.seq
, seq
));
335 EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns
);
337 #ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
339 static inline void update_vsyscall(struct timekeeper
*tk
)
341 struct timespec xt
, wm
;
343 xt
= timespec64_to_timespec(tk_xtime(tk
));
344 wm
= timespec64_to_timespec(tk
->wall_to_monotonic
);
345 update_vsyscall_old(&xt
, &wm
, tk
->tkr
.clock
, tk
->tkr
.mult
,
349 static inline void old_vsyscall_fixup(struct timekeeper
*tk
)
354 * Store only full nanoseconds into xtime_nsec after rounding
355 * it up and add the remainder to the error difference.
356 * XXX - This is necessary to avoid small 1ns inconsistnecies caused
357 * by truncating the remainder in vsyscalls. However, it causes
358 * additional work to be done in timekeeping_adjust(). Once
359 * the vsyscall implementations are converted to use xtime_nsec
360 * (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
361 * users are removed, this can be killed.
363 remainder
= tk
->tkr
.xtime_nsec
& ((1ULL << tk
->tkr
.shift
) - 1);
364 tk
->tkr
.xtime_nsec
-= remainder
;
365 tk
->tkr
.xtime_nsec
+= 1ULL << tk
->tkr
.shift
;
366 tk
->ntp_error
+= remainder
<< tk
->ntp_error_shift
;
367 tk
->ntp_error
-= (1ULL << tk
->tkr
.shift
) << tk
->ntp_error_shift
;
370 #define old_vsyscall_fixup(tk)
373 static RAW_NOTIFIER_HEAD(pvclock_gtod_chain
);
375 static void update_pvclock_gtod(struct timekeeper
*tk
, bool was_set
)
377 raw_notifier_call_chain(&pvclock_gtod_chain
, was_set
, tk
);
381 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
383 int pvclock_gtod_register_notifier(struct notifier_block
*nb
)
385 struct timekeeper
*tk
= &tk_core
.timekeeper
;
389 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
390 ret
= raw_notifier_chain_register(&pvclock_gtod_chain
, nb
);
391 update_pvclock_gtod(tk
, true);
392 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
396 EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier
);
399 * pvclock_gtod_unregister_notifier - unregister a pvclock
400 * timedata update listener
402 int pvclock_gtod_unregister_notifier(struct notifier_block
*nb
)
407 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
408 ret
= raw_notifier_chain_unregister(&pvclock_gtod_chain
, nb
);
409 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
413 EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier
);
416 * Update the ktime_t based scalar nsec members of the timekeeper
418 static inline void tk_update_ktime_data(struct timekeeper
*tk
)
423 * The xtime based monotonic readout is:
424 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
425 * The ktime based monotonic readout is:
426 * nsec = base_mono + now();
427 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
429 nsec
= (s64
)(tk
->xtime_sec
+ tk
->wall_to_monotonic
.tv_sec
);
430 nsec
*= NSEC_PER_SEC
;
431 nsec
+= tk
->wall_to_monotonic
.tv_nsec
;
432 tk
->tkr
.base_mono
= ns_to_ktime(nsec
);
434 /* Update the monotonic raw base */
435 tk
->base_raw
= timespec64_to_ktime(tk
->raw_time
);
438 /* must hold timekeeper_lock */
439 static void timekeeping_update(struct timekeeper
*tk
, unsigned int action
)
441 if (action
& TK_CLEAR_NTP
) {
446 tk_update_ktime_data(tk
);
449 update_pvclock_gtod(tk
, action
& TK_CLOCK_WAS_SET
);
451 if (action
& TK_MIRROR
)
452 memcpy(&shadow_timekeeper
, &tk_core
.timekeeper
,
453 sizeof(tk_core
.timekeeper
));
455 update_fast_timekeeper(tk
);
459 * timekeeping_forward_now - update clock to the current time
461 * Forward the current clock to update its state since the last call to
462 * update_wall_time(). This is useful before significant clock changes,
463 * as it avoids having to deal with this time offset explicitly.
465 static void timekeeping_forward_now(struct timekeeper
*tk
)
467 struct clocksource
*clock
= tk
->tkr
.clock
;
468 cycle_t cycle_now
, delta
;
471 cycle_now
= tk
->tkr
.read(clock
);
472 delta
= clocksource_delta(cycle_now
, tk
->tkr
.cycle_last
, tk
->tkr
.mask
);
473 tk
->tkr
.cycle_last
= cycle_now
;
475 tk
->tkr
.xtime_nsec
+= delta
* tk
->tkr
.mult
;
477 /* If arch requires, add in get_arch_timeoffset() */
478 tk
->tkr
.xtime_nsec
+= (u64
)arch_gettimeoffset() << tk
->tkr
.shift
;
480 tk_normalize_xtime(tk
);
482 nsec
= clocksource_cyc2ns(delta
, clock
->mult
, clock
->shift
);
483 timespec64_add_ns(&tk
->raw_time
, nsec
);
487 * __getnstimeofday64 - Returns the time of day in a timespec64.
488 * @ts: pointer to the timespec to be set
490 * Updates the time of day in the timespec.
491 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
493 int __getnstimeofday64(struct timespec64
*ts
)
495 struct timekeeper
*tk
= &tk_core
.timekeeper
;
500 seq
= read_seqcount_begin(&tk_core
.seq
);
502 ts
->tv_sec
= tk
->xtime_sec
;
503 nsecs
= timekeeping_get_ns(&tk
->tkr
);
505 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
508 timespec64_add_ns(ts
, nsecs
);
511 * Do not bail out early, in case there were callers still using
512 * the value, even in the face of the WARN_ON.
514 if (unlikely(timekeeping_suspended
))
518 EXPORT_SYMBOL(__getnstimeofday64
);
521 * getnstimeofday64 - Returns the time of day in a timespec64.
522 * @ts: pointer to the timespec to be set
524 * Returns the time of day in a timespec (WARN if suspended).
526 void getnstimeofday64(struct timespec64
*ts
)
528 WARN_ON(__getnstimeofday64(ts
));
530 EXPORT_SYMBOL(getnstimeofday64
);
532 ktime_t
ktime_get(void)
534 struct timekeeper
*tk
= &tk_core
.timekeeper
;
539 WARN_ON(timekeeping_suspended
);
542 seq
= read_seqcount_begin(&tk_core
.seq
);
543 base
= tk
->tkr
.base_mono
;
544 nsecs
= timekeeping_get_ns(&tk
->tkr
);
546 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
548 return ktime_add_ns(base
, nsecs
);
550 EXPORT_SYMBOL_GPL(ktime_get
);
552 static ktime_t
*offsets
[TK_OFFS_MAX
] = {
553 [TK_OFFS_REAL
] = &tk_core
.timekeeper
.offs_real
,
554 [TK_OFFS_BOOT
] = &tk_core
.timekeeper
.offs_boot
,
555 [TK_OFFS_TAI
] = &tk_core
.timekeeper
.offs_tai
,
558 ktime_t
ktime_get_with_offset(enum tk_offsets offs
)
560 struct timekeeper
*tk
= &tk_core
.timekeeper
;
562 ktime_t base
, *offset
= offsets
[offs
];
565 WARN_ON(timekeeping_suspended
);
568 seq
= read_seqcount_begin(&tk_core
.seq
);
569 base
= ktime_add(tk
->tkr
.base_mono
, *offset
);
570 nsecs
= timekeeping_get_ns(&tk
->tkr
);
572 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
574 return ktime_add_ns(base
, nsecs
);
577 EXPORT_SYMBOL_GPL(ktime_get_with_offset
);
580 * ktime_mono_to_any() - convert mononotic time to any other time
581 * @tmono: time to convert.
582 * @offs: which offset to use
584 ktime_t
ktime_mono_to_any(ktime_t tmono
, enum tk_offsets offs
)
586 ktime_t
*offset
= offsets
[offs
];
591 seq
= read_seqcount_begin(&tk_core
.seq
);
592 tconv
= ktime_add(tmono
, *offset
);
593 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
597 EXPORT_SYMBOL_GPL(ktime_mono_to_any
);
600 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
602 ktime_t
ktime_get_raw(void)
604 struct timekeeper
*tk
= &tk_core
.timekeeper
;
610 seq
= read_seqcount_begin(&tk_core
.seq
);
612 nsecs
= timekeeping_get_ns_raw(tk
);
614 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
616 return ktime_add_ns(base
, nsecs
);
618 EXPORT_SYMBOL_GPL(ktime_get_raw
);
621 * ktime_get_ts64 - get the monotonic clock in timespec64 format
622 * @ts: pointer to timespec variable
624 * The function calculates the monotonic clock from the realtime
625 * clock and the wall_to_monotonic offset and stores the result
626 * in normalized timespec format in the variable pointed to by @ts.
628 void ktime_get_ts64(struct timespec64
*ts
)
630 struct timekeeper
*tk
= &tk_core
.timekeeper
;
631 struct timespec64 tomono
;
635 WARN_ON(timekeeping_suspended
);
638 seq
= read_seqcount_begin(&tk_core
.seq
);
639 ts
->tv_sec
= tk
->xtime_sec
;
640 nsec
= timekeeping_get_ns(&tk
->tkr
);
641 tomono
= tk
->wall_to_monotonic
;
643 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
645 ts
->tv_sec
+= tomono
.tv_sec
;
647 timespec64_add_ns(ts
, nsec
+ tomono
.tv_nsec
);
649 EXPORT_SYMBOL_GPL(ktime_get_ts64
);
651 #ifdef CONFIG_NTP_PPS
654 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
655 * @ts_raw: pointer to the timespec to be set to raw monotonic time
656 * @ts_real: pointer to the timespec to be set to the time of day
658 * This function reads both the time of day and raw monotonic time at the
659 * same time atomically and stores the resulting timestamps in timespec
662 void getnstime_raw_and_real(struct timespec
*ts_raw
, struct timespec
*ts_real
)
664 struct timekeeper
*tk
= &tk_core
.timekeeper
;
666 s64 nsecs_raw
, nsecs_real
;
668 WARN_ON_ONCE(timekeeping_suspended
);
671 seq
= read_seqcount_begin(&tk_core
.seq
);
673 *ts_raw
= timespec64_to_timespec(tk
->raw_time
);
674 ts_real
->tv_sec
= tk
->xtime_sec
;
675 ts_real
->tv_nsec
= 0;
677 nsecs_raw
= timekeeping_get_ns_raw(tk
);
678 nsecs_real
= timekeeping_get_ns(&tk
->tkr
);
680 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
682 timespec_add_ns(ts_raw
, nsecs_raw
);
683 timespec_add_ns(ts_real
, nsecs_real
);
685 EXPORT_SYMBOL(getnstime_raw_and_real
);
687 #endif /* CONFIG_NTP_PPS */
690 * do_gettimeofday - Returns the time of day in a timeval
691 * @tv: pointer to the timeval to be set
693 * NOTE: Users should be converted to using getnstimeofday()
695 void do_gettimeofday(struct timeval
*tv
)
697 struct timespec64 now
;
699 getnstimeofday64(&now
);
700 tv
->tv_sec
= now
.tv_sec
;
701 tv
->tv_usec
= now
.tv_nsec
/1000;
703 EXPORT_SYMBOL(do_gettimeofday
);
706 * do_settimeofday - Sets the time of day
707 * @tv: pointer to the timespec variable containing the new time
709 * Sets the time of day to the new time and update NTP and notify hrtimers
711 int do_settimeofday(const struct timespec
*tv
)
713 struct timekeeper
*tk
= &tk_core
.timekeeper
;
714 struct timespec64 ts_delta
, xt
, tmp
;
717 if (!timespec_valid_strict(tv
))
720 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
721 write_seqcount_begin(&tk_core
.seq
);
723 timekeeping_forward_now(tk
);
726 ts_delta
.tv_sec
= tv
->tv_sec
- xt
.tv_sec
;
727 ts_delta
.tv_nsec
= tv
->tv_nsec
- xt
.tv_nsec
;
729 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, ts_delta
));
731 tmp
= timespec_to_timespec64(*tv
);
732 tk_set_xtime(tk
, &tmp
);
734 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
736 write_seqcount_end(&tk_core
.seq
);
737 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
739 /* signal hrtimers about time change */
744 EXPORT_SYMBOL(do_settimeofday
);
747 * timekeeping_inject_offset - Adds or subtracts from the current time.
748 * @tv: pointer to the timespec variable containing the offset
750 * Adds or subtracts an offset value from the current time.
752 int timekeeping_inject_offset(struct timespec
*ts
)
754 struct timekeeper
*tk
= &tk_core
.timekeeper
;
756 struct timespec64 ts64
, tmp
;
759 if ((unsigned long)ts
->tv_nsec
>= NSEC_PER_SEC
)
762 ts64
= timespec_to_timespec64(*ts
);
764 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
765 write_seqcount_begin(&tk_core
.seq
);
767 timekeeping_forward_now(tk
);
769 /* Make sure the proposed value is valid */
770 tmp
= timespec64_add(tk_xtime(tk
), ts64
);
771 if (!timespec64_valid_strict(&tmp
)) {
776 tk_xtime_add(tk
, &ts64
);
777 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, ts64
));
779 error
: /* even if we error out, we forwarded the time, so call update */
780 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
782 write_seqcount_end(&tk_core
.seq
);
783 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
785 /* signal hrtimers about time change */
790 EXPORT_SYMBOL(timekeeping_inject_offset
);
794 * timekeeping_get_tai_offset - Returns current TAI offset from UTC
797 s32
timekeeping_get_tai_offset(void)
799 struct timekeeper
*tk
= &tk_core
.timekeeper
;
804 seq
= read_seqcount_begin(&tk_core
.seq
);
805 ret
= tk
->tai_offset
;
806 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
812 * __timekeeping_set_tai_offset - Lock free worker function
815 static void __timekeeping_set_tai_offset(struct timekeeper
*tk
, s32 tai_offset
)
817 tk
->tai_offset
= tai_offset
;
818 tk
->offs_tai
= ktime_add(tk
->offs_real
, ktime_set(tai_offset
, 0));
822 * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
825 void timekeeping_set_tai_offset(s32 tai_offset
)
827 struct timekeeper
*tk
= &tk_core
.timekeeper
;
830 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
831 write_seqcount_begin(&tk_core
.seq
);
832 __timekeeping_set_tai_offset(tk
, tai_offset
);
833 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
834 write_seqcount_end(&tk_core
.seq
);
835 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
840 * change_clocksource - Swaps clocksources if a new one is available
842 * Accumulates current time interval and initializes new clocksource
844 static int change_clocksource(void *data
)
846 struct timekeeper
*tk
= &tk_core
.timekeeper
;
847 struct clocksource
*new, *old
;
850 new = (struct clocksource
*) data
;
852 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
853 write_seqcount_begin(&tk_core
.seq
);
855 timekeeping_forward_now(tk
);
857 * If the cs is in module, get a module reference. Succeeds
858 * for built-in code (owner == NULL) as well.
860 if (try_module_get(new->owner
)) {
861 if (!new->enable
|| new->enable(new) == 0) {
863 tk_setup_internals(tk
, new);
866 module_put(old
->owner
);
868 module_put(new->owner
);
871 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
873 write_seqcount_end(&tk_core
.seq
);
874 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
880 * timekeeping_notify - Install a new clock source
881 * @clock: pointer to the clock source
883 * This function is called from clocksource.c after a new, better clock
884 * source has been registered. The caller holds the clocksource_mutex.
886 int timekeeping_notify(struct clocksource
*clock
)
888 struct timekeeper
*tk
= &tk_core
.timekeeper
;
890 if (tk
->tkr
.clock
== clock
)
892 stop_machine(change_clocksource
, clock
, NULL
);
894 return tk
->tkr
.clock
== clock
? 0 : -1;
898 * getrawmonotonic - Returns the raw monotonic time in a timespec
899 * @ts: pointer to the timespec to be set
901 * Returns the raw monotonic time (completely un-modified by ntp)
903 void getrawmonotonic(struct timespec
*ts
)
905 struct timekeeper
*tk
= &tk_core
.timekeeper
;
906 struct timespec64 ts64
;
911 seq
= read_seqcount_begin(&tk_core
.seq
);
912 nsecs
= timekeeping_get_ns_raw(tk
);
915 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
917 timespec64_add_ns(&ts64
, nsecs
);
918 *ts
= timespec64_to_timespec(ts64
);
920 EXPORT_SYMBOL(getrawmonotonic
);
923 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
925 int timekeeping_valid_for_hres(void)
927 struct timekeeper
*tk
= &tk_core
.timekeeper
;
932 seq
= read_seqcount_begin(&tk_core
.seq
);
934 ret
= tk
->tkr
.clock
->flags
& CLOCK_SOURCE_VALID_FOR_HRES
;
936 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
942 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
944 u64
timekeeping_max_deferment(void)
946 struct timekeeper
*tk
= &tk_core
.timekeeper
;
951 seq
= read_seqcount_begin(&tk_core
.seq
);
953 ret
= tk
->tkr
.clock
->max_idle_ns
;
955 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
961 * read_persistent_clock - Return time from the persistent clock.
963 * Weak dummy function for arches that do not yet support it.
964 * Reads the time from the battery backed persistent clock.
965 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
967 * XXX - Do be sure to remove it once all arches implement it.
969 void __weak
read_persistent_clock(struct timespec
*ts
)
976 * read_boot_clock - Return time of the system start.
978 * Weak dummy function for arches that do not yet support it.
979 * Function to read the exact time the system has been started.
980 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
982 * XXX - Do be sure to remove it once all arches implement it.
984 void __weak
read_boot_clock(struct timespec
*ts
)
991 * timekeeping_init - Initializes the clocksource and common timekeeping values
993 void __init
timekeeping_init(void)
995 struct timekeeper
*tk
= &tk_core
.timekeeper
;
996 struct clocksource
*clock
;
998 struct timespec64 now
, boot
, tmp
;
1001 read_persistent_clock(&ts
);
1002 now
= timespec_to_timespec64(ts
);
1003 if (!timespec64_valid_strict(&now
)) {
1004 pr_warn("WARNING: Persistent clock returned invalid value!\n"
1005 " Check your CMOS/BIOS settings.\n");
1008 } else if (now
.tv_sec
|| now
.tv_nsec
)
1009 persistent_clock_exist
= true;
1011 read_boot_clock(&ts
);
1012 boot
= timespec_to_timespec64(ts
);
1013 if (!timespec64_valid_strict(&boot
)) {
1014 pr_warn("WARNING: Boot clock returned invalid value!\n"
1015 " Check your CMOS/BIOS settings.\n");
1020 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1021 write_seqcount_begin(&tk_core
.seq
);
1024 clock
= clocksource_default_clock();
1026 clock
->enable(clock
);
1027 tk_setup_internals(tk
, clock
);
1029 tk_set_xtime(tk
, &now
);
1030 tk
->raw_time
.tv_sec
= 0;
1031 tk
->raw_time
.tv_nsec
= 0;
1032 tk
->base_raw
.tv64
= 0;
1033 if (boot
.tv_sec
== 0 && boot
.tv_nsec
== 0)
1034 boot
= tk_xtime(tk
);
1036 set_normalized_timespec64(&tmp
, -boot
.tv_sec
, -boot
.tv_nsec
);
1037 tk_set_wall_to_mono(tk
, tmp
);
1039 timekeeping_update(tk
, TK_MIRROR
);
1041 write_seqcount_end(&tk_core
.seq
);
1042 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1045 /* time in seconds when suspend began */
1046 static struct timespec64 timekeeping_suspend_time
;
1049 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1050 * @delta: pointer to a timespec delta value
1052 * Takes a timespec offset measuring a suspend interval and properly
1053 * adds the sleep offset to the timekeeping variables.
1055 static void __timekeeping_inject_sleeptime(struct timekeeper
*tk
,
1056 struct timespec64
*delta
)
1058 if (!timespec64_valid_strict(delta
)) {
1059 printk_deferred(KERN_WARNING
1060 "__timekeeping_inject_sleeptime: Invalid "
1061 "sleep delta value!\n");
1064 tk_xtime_add(tk
, delta
);
1065 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, *delta
));
1066 tk_update_sleep_time(tk
, timespec64_to_ktime(*delta
));
1067 tk_debug_account_sleep_time(delta
);
1071 * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
1072 * @delta: pointer to a timespec delta value
1074 * This hook is for architectures that cannot support read_persistent_clock
1075 * because their RTC/persistent clock is only accessible when irqs are enabled.
1077 * This function should only be called by rtc_resume(), and allows
1078 * a suspend offset to be injected into the timekeeping values.
1080 void timekeeping_inject_sleeptime(struct timespec
*delta
)
1082 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1083 struct timespec64 tmp
;
1084 unsigned long flags
;
1087 * Make sure we don't set the clock twice, as timekeeping_resume()
1090 if (has_persistent_clock())
1093 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1094 write_seqcount_begin(&tk_core
.seq
);
1096 timekeeping_forward_now(tk
);
1098 tmp
= timespec_to_timespec64(*delta
);
1099 __timekeeping_inject_sleeptime(tk
, &tmp
);
1101 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
1103 write_seqcount_end(&tk_core
.seq
);
1104 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1106 /* signal hrtimers about time change */
1111 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1113 * This is for the generic clocksource timekeeping.
1114 * xtime/wall_to_monotonic/jiffies/etc are
1115 * still managed by arch specific suspend/resume code.
1117 static void timekeeping_resume(void)
1119 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1120 struct clocksource
*clock
= tk
->tkr
.clock
;
1121 unsigned long flags
;
1122 struct timespec64 ts_new
, ts_delta
;
1123 struct timespec tmp
;
1124 cycle_t cycle_now
, cycle_delta
;
1125 bool suspendtime_found
= false;
1127 read_persistent_clock(&tmp
);
1128 ts_new
= timespec_to_timespec64(tmp
);
1130 clockevents_resume();
1131 clocksource_resume();
1133 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1134 write_seqcount_begin(&tk_core
.seq
);
1137 * After system resumes, we need to calculate the suspended time and
1138 * compensate it for the OS time. There are 3 sources that could be
1139 * used: Nonstop clocksource during suspend, persistent clock and rtc
1142 * One specific platform may have 1 or 2 or all of them, and the
1143 * preference will be:
1144 * suspend-nonstop clocksource -> persistent clock -> rtc
1145 * The less preferred source will only be tried if there is no better
1146 * usable source. The rtc part is handled separately in rtc core code.
1148 cycle_now
= tk
->tkr
.read(clock
);
1149 if ((clock
->flags
& CLOCK_SOURCE_SUSPEND_NONSTOP
) &&
1150 cycle_now
> tk
->tkr
.cycle_last
) {
1151 u64 num
, max
= ULLONG_MAX
;
1152 u32 mult
= clock
->mult
;
1153 u32 shift
= clock
->shift
;
1156 cycle_delta
= clocksource_delta(cycle_now
, tk
->tkr
.cycle_last
,
1160 * "cycle_delta * mutl" may cause 64 bits overflow, if the
1161 * suspended time is too long. In that case we need do the
1162 * 64 bits math carefully
1165 if (cycle_delta
> max
) {
1166 num
= div64_u64(cycle_delta
, max
);
1167 nsec
= (((u64
) max
* mult
) >> shift
) * num
;
1168 cycle_delta
-= num
* max
;
1170 nsec
+= ((u64
) cycle_delta
* mult
) >> shift
;
1172 ts_delta
= ns_to_timespec64(nsec
);
1173 suspendtime_found
= true;
1174 } else if (timespec64_compare(&ts_new
, &timekeeping_suspend_time
) > 0) {
1175 ts_delta
= timespec64_sub(ts_new
, timekeeping_suspend_time
);
1176 suspendtime_found
= true;
1179 if (suspendtime_found
)
1180 __timekeeping_inject_sleeptime(tk
, &ts_delta
);
1182 /* Re-base the last cycle value */
1183 tk
->tkr
.cycle_last
= cycle_now
;
1185 timekeeping_suspended
= 0;
1186 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
1187 write_seqcount_end(&tk_core
.seq
);
1188 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1190 touch_softlockup_watchdog();
1192 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME
, NULL
);
1194 /* Resume hrtimers */
1198 static int timekeeping_suspend(void)
1200 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1201 unsigned long flags
;
1202 struct timespec64 delta
, delta_delta
;
1203 static struct timespec64 old_delta
;
1204 struct timespec tmp
;
1206 read_persistent_clock(&tmp
);
1207 timekeeping_suspend_time
= timespec_to_timespec64(tmp
);
1210 * On some systems the persistent_clock can not be detected at
1211 * timekeeping_init by its return value, so if we see a valid
1212 * value returned, update the persistent_clock_exists flag.
1214 if (timekeeping_suspend_time
.tv_sec
|| timekeeping_suspend_time
.tv_nsec
)
1215 persistent_clock_exist
= true;
1217 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1218 write_seqcount_begin(&tk_core
.seq
);
1219 timekeeping_forward_now(tk
);
1220 timekeeping_suspended
= 1;
1223 * To avoid drift caused by repeated suspend/resumes,
1224 * which each can add ~1 second drift error,
1225 * try to compensate so the difference in system time
1226 * and persistent_clock time stays close to constant.
1228 delta
= timespec64_sub(tk_xtime(tk
), timekeeping_suspend_time
);
1229 delta_delta
= timespec64_sub(delta
, old_delta
);
1230 if (abs(delta_delta
.tv_sec
) >= 2) {
1232 * if delta_delta is too large, assume time correction
1233 * has occured and set old_delta to the current delta.
1237 /* Otherwise try to adjust old_system to compensate */
1238 timekeeping_suspend_time
=
1239 timespec64_add(timekeeping_suspend_time
, delta_delta
);
1242 timekeeping_update(tk
, TK_MIRROR
);
1243 write_seqcount_end(&tk_core
.seq
);
1244 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1246 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND
, NULL
);
1247 clocksource_suspend();
1248 clockevents_suspend();
1253 /* sysfs resume/suspend bits for timekeeping */
1254 static struct syscore_ops timekeeping_syscore_ops
= {
1255 .resume
= timekeeping_resume
,
1256 .suspend
= timekeeping_suspend
,
1259 static int __init
timekeeping_init_ops(void)
1261 register_syscore_ops(&timekeeping_syscore_ops
);
1264 device_initcall(timekeeping_init_ops
);
1267 * Apply a multiplier adjustment to the timekeeper
1269 static __always_inline
void timekeeping_apply_adjustment(struct timekeeper
*tk
,
1274 s64 interval
= tk
->cycle_interval
;
1278 mult_adj
= -mult_adj
;
1279 interval
= -interval
;
1282 mult_adj
<<= adj_scale
;
1283 interval
<<= adj_scale
;
1284 offset
<<= adj_scale
;
1287 * So the following can be confusing.
1289 * To keep things simple, lets assume mult_adj == 1 for now.
1291 * When mult_adj != 1, remember that the interval and offset values
1292 * have been appropriately scaled so the math is the same.
1294 * The basic idea here is that we're increasing the multiplier
1295 * by one, this causes the xtime_interval to be incremented by
1296 * one cycle_interval. This is because:
1297 * xtime_interval = cycle_interval * mult
1298 * So if mult is being incremented by one:
1299 * xtime_interval = cycle_interval * (mult + 1)
1301 * xtime_interval = (cycle_interval * mult) + cycle_interval
1302 * Which can be shortened to:
1303 * xtime_interval += cycle_interval
1305 * So offset stores the non-accumulated cycles. Thus the current
1306 * time (in shifted nanoseconds) is:
1307 * now = (offset * adj) + xtime_nsec
1308 * Now, even though we're adjusting the clock frequency, we have
1309 * to keep time consistent. In other words, we can't jump back
1310 * in time, and we also want to avoid jumping forward in time.
1312 * So given the same offset value, we need the time to be the same
1313 * both before and after the freq adjustment.
1314 * now = (offset * adj_1) + xtime_nsec_1
1315 * now = (offset * adj_2) + xtime_nsec_2
1317 * (offset * adj_1) + xtime_nsec_1 =
1318 * (offset * adj_2) + xtime_nsec_2
1322 * (offset * adj_1) + xtime_nsec_1 =
1323 * (offset * (adj_1+1)) + xtime_nsec_2
1324 * (offset * adj_1) + xtime_nsec_1 =
1325 * (offset * adj_1) + offset + xtime_nsec_2
1326 * Canceling the sides:
1327 * xtime_nsec_1 = offset + xtime_nsec_2
1329 * xtime_nsec_2 = xtime_nsec_1 - offset
1330 * Which simplfies to:
1331 * xtime_nsec -= offset
1333 * XXX - TODO: Doc ntp_error calculation.
1335 tk
->tkr
.mult
+= mult_adj
;
1336 tk
->xtime_interval
+= interval
;
1337 tk
->tkr
.xtime_nsec
-= offset
;
1338 tk
->ntp_error
-= (interval
- offset
) << tk
->ntp_error_shift
;
1342 * Calculate the multiplier adjustment needed to match the frequency
1345 static __always_inline
void timekeeping_freqadjust(struct timekeeper
*tk
,
1348 s64 interval
= tk
->cycle_interval
;
1349 s64 xinterval
= tk
->xtime_interval
;
1354 /* Remove any current error adj from freq calculation */
1355 if (tk
->ntp_err_mult
)
1356 xinterval
-= tk
->cycle_interval
;
1358 tk
->ntp_tick
= ntp_tick_length();
1360 /* Calculate current error per tick */
1361 tick_error
= ntp_tick_length() >> tk
->ntp_error_shift
;
1362 tick_error
-= (xinterval
+ tk
->xtime_remainder
);
1364 /* Don't worry about correcting it if its small */
1365 if (likely((tick_error
>= 0) && (tick_error
<= interval
)))
1368 /* preserve the direction of correction */
1369 negative
= (tick_error
< 0);
1371 /* Sort out the magnitude of the correction */
1372 tick_error
= abs(tick_error
);
1373 for (adj
= 0; tick_error
> interval
; adj
++)
1376 /* scale the corrections */
1377 timekeeping_apply_adjustment(tk
, offset
, negative
, adj
);
1381 * Adjust the timekeeper's multiplier to the correct frequency
1382 * and also to reduce the accumulated error value.
1384 static void timekeeping_adjust(struct timekeeper
*tk
, s64 offset
)
1386 /* Correct for the current frequency error */
1387 timekeeping_freqadjust(tk
, offset
);
1389 /* Next make a small adjustment to fix any cumulative error */
1390 if (!tk
->ntp_err_mult
&& (tk
->ntp_error
> 0)) {
1391 tk
->ntp_err_mult
= 1;
1392 timekeeping_apply_adjustment(tk
, offset
, 0, 0);
1393 } else if (tk
->ntp_err_mult
&& (tk
->ntp_error
<= 0)) {
1394 /* Undo any existing error adjustment */
1395 timekeeping_apply_adjustment(tk
, offset
, 1, 0);
1396 tk
->ntp_err_mult
= 0;
1399 if (unlikely(tk
->tkr
.clock
->maxadj
&&
1400 (tk
->tkr
.mult
> tk
->tkr
.clock
->mult
+ tk
->tkr
.clock
->maxadj
))) {
1401 printk_once(KERN_WARNING
1402 "Adjusting %s more than 11%% (%ld vs %ld)\n",
1403 tk
->tkr
.clock
->name
, (long)tk
->tkr
.mult
,
1404 (long)tk
->tkr
.clock
->mult
+ tk
->tkr
.clock
->maxadj
);
1408 * It may be possible that when we entered this function, xtime_nsec
1409 * was very small. Further, if we're slightly speeding the clocksource
1410 * in the code above, its possible the required corrective factor to
1411 * xtime_nsec could cause it to underflow.
1413 * Now, since we already accumulated the second, cannot simply roll
1414 * the accumulated second back, since the NTP subsystem has been
1415 * notified via second_overflow. So instead we push xtime_nsec forward
1416 * by the amount we underflowed, and add that amount into the error.
1418 * We'll correct this error next time through this function, when
1419 * xtime_nsec is not as small.
1421 if (unlikely((s64
)tk
->tkr
.xtime_nsec
< 0)) {
1422 s64 neg
= -(s64
)tk
->tkr
.xtime_nsec
;
1423 tk
->tkr
.xtime_nsec
= 0;
1424 tk
->ntp_error
+= neg
<< tk
->ntp_error_shift
;
1429 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1431 * Helper function that accumulates a the nsecs greater then a second
1432 * from the xtime_nsec field to the xtime_secs field.
1433 * It also calls into the NTP code to handle leapsecond processing.
1436 static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper
*tk
)
1438 u64 nsecps
= (u64
)NSEC_PER_SEC
<< tk
->tkr
.shift
;
1439 unsigned int clock_set
= 0;
1441 while (tk
->tkr
.xtime_nsec
>= nsecps
) {
1444 tk
->tkr
.xtime_nsec
-= nsecps
;
1447 /* Figure out if its a leap sec and apply if needed */
1448 leap
= second_overflow(tk
->xtime_sec
);
1449 if (unlikely(leap
)) {
1450 struct timespec64 ts
;
1452 tk
->xtime_sec
+= leap
;
1456 tk_set_wall_to_mono(tk
,
1457 timespec64_sub(tk
->wall_to_monotonic
, ts
));
1459 __timekeeping_set_tai_offset(tk
, tk
->tai_offset
- leap
);
1461 clock_set
= TK_CLOCK_WAS_SET
;
1468 * logarithmic_accumulation - shifted accumulation of cycles
1470 * This functions accumulates a shifted interval of cycles into
1471 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1474 * Returns the unconsumed cycles.
1476 static cycle_t
logarithmic_accumulation(struct timekeeper
*tk
, cycle_t offset
,
1478 unsigned int *clock_set
)
1480 cycle_t interval
= tk
->cycle_interval
<< shift
;
1483 /* If the offset is smaller then a shifted interval, do nothing */
1484 if (offset
< interval
)
1487 /* Accumulate one shifted interval */
1489 tk
->tkr
.cycle_last
+= interval
;
1491 tk
->tkr
.xtime_nsec
+= tk
->xtime_interval
<< shift
;
1492 *clock_set
|= accumulate_nsecs_to_secs(tk
);
1494 /* Accumulate raw time */
1495 raw_nsecs
= (u64
)tk
->raw_interval
<< shift
;
1496 raw_nsecs
+= tk
->raw_time
.tv_nsec
;
1497 if (raw_nsecs
>= NSEC_PER_SEC
) {
1498 u64 raw_secs
= raw_nsecs
;
1499 raw_nsecs
= do_div(raw_secs
, NSEC_PER_SEC
);
1500 tk
->raw_time
.tv_sec
+= raw_secs
;
1502 tk
->raw_time
.tv_nsec
= raw_nsecs
;
1504 /* Accumulate error between NTP and clock interval */
1505 tk
->ntp_error
+= tk
->ntp_tick
<< shift
;
1506 tk
->ntp_error
-= (tk
->xtime_interval
+ tk
->xtime_remainder
) <<
1507 (tk
->ntp_error_shift
+ shift
);
1513 * update_wall_time - Uses the current clocksource to increment the wall time
1516 void update_wall_time(void)
1518 struct timekeeper
*real_tk
= &tk_core
.timekeeper
;
1519 struct timekeeper
*tk
= &shadow_timekeeper
;
1521 int shift
= 0, maxshift
;
1522 unsigned int clock_set
= 0;
1523 unsigned long flags
;
1525 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1527 /* Make sure we're fully resumed: */
1528 if (unlikely(timekeeping_suspended
))
1531 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1532 offset
= real_tk
->cycle_interval
;
1534 offset
= clocksource_delta(tk
->tkr
.read(tk
->tkr
.clock
),
1535 tk
->tkr
.cycle_last
, tk
->tkr
.mask
);
1538 /* Check if there's really nothing to do */
1539 if (offset
< real_tk
->cycle_interval
)
1543 * With NO_HZ we may have to accumulate many cycle_intervals
1544 * (think "ticks") worth of time at once. To do this efficiently,
1545 * we calculate the largest doubling multiple of cycle_intervals
1546 * that is smaller than the offset. We then accumulate that
1547 * chunk in one go, and then try to consume the next smaller
1550 shift
= ilog2(offset
) - ilog2(tk
->cycle_interval
);
1551 shift
= max(0, shift
);
1552 /* Bound shift to one less than what overflows tick_length */
1553 maxshift
= (64 - (ilog2(ntp_tick_length())+1)) - 1;
1554 shift
= min(shift
, maxshift
);
1555 while (offset
>= tk
->cycle_interval
) {
1556 offset
= logarithmic_accumulation(tk
, offset
, shift
,
1558 if (offset
< tk
->cycle_interval
<<shift
)
1562 /* correct the clock when NTP error is too big */
1563 timekeeping_adjust(tk
, offset
);
1566 * XXX This can be killed once everyone converts
1567 * to the new update_vsyscall.
1569 old_vsyscall_fixup(tk
);
1572 * Finally, make sure that after the rounding
1573 * xtime_nsec isn't larger than NSEC_PER_SEC
1575 clock_set
|= accumulate_nsecs_to_secs(tk
);
1577 write_seqcount_begin(&tk_core
.seq
);
1579 * Update the real timekeeper.
1581 * We could avoid this memcpy by switching pointers, but that
1582 * requires changes to all other timekeeper usage sites as
1583 * well, i.e. move the timekeeper pointer getter into the
1584 * spinlocked/seqcount protected sections. And we trade this
1585 * memcpy under the tk_core.seq against one before we start
1588 memcpy(real_tk
, tk
, sizeof(*tk
));
1589 timekeeping_update(real_tk
, clock_set
);
1590 write_seqcount_end(&tk_core
.seq
);
1592 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1594 /* Have to call _delayed version, since in irq context*/
1595 clock_was_set_delayed();
1599 * getboottime - Return the real time of system boot.
1600 * @ts: pointer to the timespec to be set
1602 * Returns the wall-time of boot in a timespec.
1604 * This is based on the wall_to_monotonic offset and the total suspend
1605 * time. Calls to settimeofday will affect the value returned (which
1606 * basically means that however wrong your real time clock is at boot time,
1607 * you get the right time here).
1609 void getboottime(struct timespec
*ts
)
1611 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1612 ktime_t t
= ktime_sub(tk
->offs_real
, tk
->offs_boot
);
1614 *ts
= ktime_to_timespec(t
);
1616 EXPORT_SYMBOL_GPL(getboottime
);
1618 unsigned long get_seconds(void)
1620 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1622 return tk
->xtime_sec
;
1624 EXPORT_SYMBOL(get_seconds
);
1626 struct timespec
__current_kernel_time(void)
1628 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1630 return timespec64_to_timespec(tk_xtime(tk
));
1633 struct timespec
current_kernel_time(void)
1635 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1636 struct timespec64 now
;
1640 seq
= read_seqcount_begin(&tk_core
.seq
);
1643 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1645 return timespec64_to_timespec(now
);
1647 EXPORT_SYMBOL(current_kernel_time
);
1649 struct timespec
get_monotonic_coarse(void)
1651 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1652 struct timespec64 now
, mono
;
1656 seq
= read_seqcount_begin(&tk_core
.seq
);
1659 mono
= tk
->wall_to_monotonic
;
1660 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1662 set_normalized_timespec64(&now
, now
.tv_sec
+ mono
.tv_sec
,
1663 now
.tv_nsec
+ mono
.tv_nsec
);
1665 return timespec64_to_timespec(now
);
1669 * Must hold jiffies_lock
1671 void do_timer(unsigned long ticks
)
1673 jiffies_64
+= ticks
;
1674 calc_global_load(ticks
);
1678 * ktime_get_update_offsets_tick - hrtimer helper
1679 * @offs_real: pointer to storage for monotonic -> realtime offset
1680 * @offs_boot: pointer to storage for monotonic -> boottime offset
1681 * @offs_tai: pointer to storage for monotonic -> clock tai offset
1683 * Returns monotonic time at last tick and various offsets
1685 ktime_t
ktime_get_update_offsets_tick(ktime_t
*offs_real
, ktime_t
*offs_boot
,
1688 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1694 seq
= read_seqcount_begin(&tk_core
.seq
);
1696 base
= tk
->tkr
.base_mono
;
1697 nsecs
= tk
->tkr
.xtime_nsec
>> tk
->tkr
.shift
;
1699 *offs_real
= tk
->offs_real
;
1700 *offs_boot
= tk
->offs_boot
;
1701 *offs_tai
= tk
->offs_tai
;
1702 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1704 return ktime_add_ns(base
, nsecs
);
1707 #ifdef CONFIG_HIGH_RES_TIMERS
1709 * ktime_get_update_offsets_now - hrtimer helper
1710 * @offs_real: pointer to storage for monotonic -> realtime offset
1711 * @offs_boot: pointer to storage for monotonic -> boottime offset
1712 * @offs_tai: pointer to storage for monotonic -> clock tai offset
1714 * Returns current monotonic time and updates the offsets
1715 * Called from hrtimer_interrupt() or retrigger_next_event()
1717 ktime_t
ktime_get_update_offsets_now(ktime_t
*offs_real
, ktime_t
*offs_boot
,
1720 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1726 seq
= read_seqcount_begin(&tk_core
.seq
);
1728 base
= tk
->tkr
.base_mono
;
1729 nsecs
= timekeeping_get_ns(&tk
->tkr
);
1731 *offs_real
= tk
->offs_real
;
1732 *offs_boot
= tk
->offs_boot
;
1733 *offs_tai
= tk
->offs_tai
;
1734 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1736 return ktime_add_ns(base
, nsecs
);
1741 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
1743 int do_adjtimex(struct timex
*txc
)
1745 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1746 unsigned long flags
;
1747 struct timespec64 ts
;
1751 /* Validate the data before disabling interrupts */
1752 ret
= ntp_validate_timex(txc
);
1756 if (txc
->modes
& ADJ_SETOFFSET
) {
1757 struct timespec delta
;
1758 delta
.tv_sec
= txc
->time
.tv_sec
;
1759 delta
.tv_nsec
= txc
->time
.tv_usec
;
1760 if (!(txc
->modes
& ADJ_NANO
))
1761 delta
.tv_nsec
*= 1000;
1762 ret
= timekeeping_inject_offset(&delta
);
1767 getnstimeofday64(&ts
);
1769 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1770 write_seqcount_begin(&tk_core
.seq
);
1772 orig_tai
= tai
= tk
->tai_offset
;
1773 ret
= __do_adjtimex(txc
, &ts
, &tai
);
1775 if (tai
!= orig_tai
) {
1776 __timekeeping_set_tai_offset(tk
, tai
);
1777 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
1779 write_seqcount_end(&tk_core
.seq
);
1780 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1782 if (tai
!= orig_tai
)
1785 ntp_notify_cmos_timer();
1790 #ifdef CONFIG_NTP_PPS
1792 * hardpps() - Accessor function to NTP __hardpps function
1794 void hardpps(const struct timespec
*phase_ts
, const struct timespec
*raw_ts
)
1796 unsigned long flags
;
1798 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1799 write_seqcount_begin(&tk_core
.seq
);
1801 __hardpps(phase_ts
, raw_ts
);
1803 write_seqcount_end(&tk_core
.seq
);
1804 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1806 EXPORT_SYMBOL(hardpps
);
1810 * xtime_update() - advances the timekeeping infrastructure
1811 * @ticks: number of ticks, that have elapsed since the last call.
1813 * Must be called with interrupts disabled.
1815 void xtime_update(unsigned long ticks
)
1817 write_seqlock(&jiffies_lock
);
1819 write_sequnlock(&jiffies_lock
);