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
)
424 * The xtime based monotonic readout is:
425 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
426 * The ktime based monotonic readout is:
427 * nsec = base_mono + now();
428 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
430 seconds
= (u64
)(tk
->xtime_sec
+ tk
->wall_to_monotonic
.tv_sec
);
431 nsec
= (u32
) tk
->wall_to_monotonic
.tv_nsec
;
432 tk
->tkr
.base_mono
= ns_to_ktime(seconds
* NSEC_PER_SEC
+ nsec
);
434 /* Update the monotonic raw base */
435 tk
->base_raw
= timespec64_to_ktime(tk
->raw_time
);
438 * The sum of the nanoseconds portions of xtime and
439 * wall_to_monotonic can be greater/equal one second. Take
440 * this into account before updating tk->ktime_sec.
442 nsec
+= (u32
)(tk
->tkr
.xtime_nsec
>> tk
->tkr
.shift
);
443 if (nsec
>= NSEC_PER_SEC
)
445 tk
->ktime_sec
= seconds
;
448 /* must hold timekeeper_lock */
449 static void timekeeping_update(struct timekeeper
*tk
, unsigned int action
)
451 if (action
& TK_CLEAR_NTP
) {
456 tk_update_ktime_data(tk
);
459 update_pvclock_gtod(tk
, action
& TK_CLOCK_WAS_SET
);
461 if (action
& TK_MIRROR
)
462 memcpy(&shadow_timekeeper
, &tk_core
.timekeeper
,
463 sizeof(tk_core
.timekeeper
));
465 update_fast_timekeeper(tk
);
469 * timekeeping_forward_now - update clock to the current time
471 * Forward the current clock to update its state since the last call to
472 * update_wall_time(). This is useful before significant clock changes,
473 * as it avoids having to deal with this time offset explicitly.
475 static void timekeeping_forward_now(struct timekeeper
*tk
)
477 struct clocksource
*clock
= tk
->tkr
.clock
;
478 cycle_t cycle_now
, delta
;
481 cycle_now
= tk
->tkr
.read(clock
);
482 delta
= clocksource_delta(cycle_now
, tk
->tkr
.cycle_last
, tk
->tkr
.mask
);
483 tk
->tkr
.cycle_last
= cycle_now
;
485 tk
->tkr
.xtime_nsec
+= delta
* tk
->tkr
.mult
;
487 /* If arch requires, add in get_arch_timeoffset() */
488 tk
->tkr
.xtime_nsec
+= (u64
)arch_gettimeoffset() << tk
->tkr
.shift
;
490 tk_normalize_xtime(tk
);
492 nsec
= clocksource_cyc2ns(delta
, clock
->mult
, clock
->shift
);
493 timespec64_add_ns(&tk
->raw_time
, nsec
);
497 * __getnstimeofday64 - Returns the time of day in a timespec64.
498 * @ts: pointer to the timespec to be set
500 * Updates the time of day in the timespec.
501 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
503 int __getnstimeofday64(struct timespec64
*ts
)
505 struct timekeeper
*tk
= &tk_core
.timekeeper
;
510 seq
= read_seqcount_begin(&tk_core
.seq
);
512 ts
->tv_sec
= tk
->xtime_sec
;
513 nsecs
= timekeeping_get_ns(&tk
->tkr
);
515 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
518 timespec64_add_ns(ts
, nsecs
);
521 * Do not bail out early, in case there were callers still using
522 * the value, even in the face of the WARN_ON.
524 if (unlikely(timekeeping_suspended
))
528 EXPORT_SYMBOL(__getnstimeofday64
);
531 * getnstimeofday64 - Returns the time of day in a timespec64.
532 * @ts: pointer to the timespec64 to be set
534 * Returns the time of day in a timespec64 (WARN if suspended).
536 void getnstimeofday64(struct timespec64
*ts
)
538 WARN_ON(__getnstimeofday64(ts
));
540 EXPORT_SYMBOL(getnstimeofday64
);
542 ktime_t
ktime_get(void)
544 struct timekeeper
*tk
= &tk_core
.timekeeper
;
549 WARN_ON(timekeeping_suspended
);
552 seq
= read_seqcount_begin(&tk_core
.seq
);
553 base
= tk
->tkr
.base_mono
;
554 nsecs
= timekeeping_get_ns(&tk
->tkr
);
556 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
558 return ktime_add_ns(base
, nsecs
);
560 EXPORT_SYMBOL_GPL(ktime_get
);
562 static ktime_t
*offsets
[TK_OFFS_MAX
] = {
563 [TK_OFFS_REAL
] = &tk_core
.timekeeper
.offs_real
,
564 [TK_OFFS_BOOT
] = &tk_core
.timekeeper
.offs_boot
,
565 [TK_OFFS_TAI
] = &tk_core
.timekeeper
.offs_tai
,
568 ktime_t
ktime_get_with_offset(enum tk_offsets offs
)
570 struct timekeeper
*tk
= &tk_core
.timekeeper
;
572 ktime_t base
, *offset
= offsets
[offs
];
575 WARN_ON(timekeeping_suspended
);
578 seq
= read_seqcount_begin(&tk_core
.seq
);
579 base
= ktime_add(tk
->tkr
.base_mono
, *offset
);
580 nsecs
= timekeeping_get_ns(&tk
->tkr
);
582 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
584 return ktime_add_ns(base
, nsecs
);
587 EXPORT_SYMBOL_GPL(ktime_get_with_offset
);
590 * ktime_mono_to_any() - convert mononotic time to any other time
591 * @tmono: time to convert.
592 * @offs: which offset to use
594 ktime_t
ktime_mono_to_any(ktime_t tmono
, enum tk_offsets offs
)
596 ktime_t
*offset
= offsets
[offs
];
601 seq
= read_seqcount_begin(&tk_core
.seq
);
602 tconv
= ktime_add(tmono
, *offset
);
603 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
607 EXPORT_SYMBOL_GPL(ktime_mono_to_any
);
610 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
612 ktime_t
ktime_get_raw(void)
614 struct timekeeper
*tk
= &tk_core
.timekeeper
;
620 seq
= read_seqcount_begin(&tk_core
.seq
);
622 nsecs
= timekeeping_get_ns_raw(tk
);
624 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
626 return ktime_add_ns(base
, nsecs
);
628 EXPORT_SYMBOL_GPL(ktime_get_raw
);
631 * ktime_get_ts64 - get the monotonic clock in timespec64 format
632 * @ts: pointer to timespec variable
634 * The function calculates the monotonic clock from the realtime
635 * clock and the wall_to_monotonic offset and stores the result
636 * in normalized timespec64 format in the variable pointed to by @ts.
638 void ktime_get_ts64(struct timespec64
*ts
)
640 struct timekeeper
*tk
= &tk_core
.timekeeper
;
641 struct timespec64 tomono
;
645 WARN_ON(timekeeping_suspended
);
648 seq
= read_seqcount_begin(&tk_core
.seq
);
649 ts
->tv_sec
= tk
->xtime_sec
;
650 nsec
= timekeeping_get_ns(&tk
->tkr
);
651 tomono
= tk
->wall_to_monotonic
;
653 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
655 ts
->tv_sec
+= tomono
.tv_sec
;
657 timespec64_add_ns(ts
, nsec
+ tomono
.tv_nsec
);
659 EXPORT_SYMBOL_GPL(ktime_get_ts64
);
662 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
664 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
665 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
666 * works on both 32 and 64 bit systems. On 32 bit systems the readout
667 * covers ~136 years of uptime which should be enough to prevent
668 * premature wrap arounds.
670 time64_t
ktime_get_seconds(void)
672 struct timekeeper
*tk
= &tk_core
.timekeeper
;
674 WARN_ON(timekeeping_suspended
);
675 return tk
->ktime_sec
;
677 EXPORT_SYMBOL_GPL(ktime_get_seconds
);
680 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
682 * Returns the wall clock seconds since 1970. This replaces the
683 * get_seconds() interface which is not y2038 safe on 32bit systems.
685 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
686 * 32bit systems the access must be protected with the sequence
687 * counter to provide "atomic" access to the 64bit tk->xtime_sec
690 time64_t
ktime_get_real_seconds(void)
692 struct timekeeper
*tk
= &tk_core
.timekeeper
;
696 if (IS_ENABLED(CONFIG_64BIT
))
697 return tk
->xtime_sec
;
700 seq
= read_seqcount_begin(&tk_core
.seq
);
701 seconds
= tk
->xtime_sec
;
703 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
707 EXPORT_SYMBOL_GPL(ktime_get_real_seconds
);
709 #ifdef CONFIG_NTP_PPS
712 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
713 * @ts_raw: pointer to the timespec to be set to raw monotonic time
714 * @ts_real: pointer to the timespec to be set to the time of day
716 * This function reads both the time of day and raw monotonic time at the
717 * same time atomically and stores the resulting timestamps in timespec
720 void getnstime_raw_and_real(struct timespec
*ts_raw
, struct timespec
*ts_real
)
722 struct timekeeper
*tk
= &tk_core
.timekeeper
;
724 s64 nsecs_raw
, nsecs_real
;
726 WARN_ON_ONCE(timekeeping_suspended
);
729 seq
= read_seqcount_begin(&tk_core
.seq
);
731 *ts_raw
= timespec64_to_timespec(tk
->raw_time
);
732 ts_real
->tv_sec
= tk
->xtime_sec
;
733 ts_real
->tv_nsec
= 0;
735 nsecs_raw
= timekeeping_get_ns_raw(tk
);
736 nsecs_real
= timekeeping_get_ns(&tk
->tkr
);
738 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
740 timespec_add_ns(ts_raw
, nsecs_raw
);
741 timespec_add_ns(ts_real
, nsecs_real
);
743 EXPORT_SYMBOL(getnstime_raw_and_real
);
745 #endif /* CONFIG_NTP_PPS */
748 * do_gettimeofday - Returns the time of day in a timeval
749 * @tv: pointer to the timeval to be set
751 * NOTE: Users should be converted to using getnstimeofday()
753 void do_gettimeofday(struct timeval
*tv
)
755 struct timespec64 now
;
757 getnstimeofday64(&now
);
758 tv
->tv_sec
= now
.tv_sec
;
759 tv
->tv_usec
= now
.tv_nsec
/1000;
761 EXPORT_SYMBOL(do_gettimeofday
);
764 * do_settimeofday64 - Sets the time of day.
765 * @ts: pointer to the timespec64 variable containing the new time
767 * Sets the time of day to the new time and update NTP and notify hrtimers
769 int do_settimeofday64(const struct timespec64
*ts
)
771 struct timekeeper
*tk
= &tk_core
.timekeeper
;
772 struct timespec64 ts_delta
, xt
;
775 if (!timespec64_valid_strict(ts
))
778 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
779 write_seqcount_begin(&tk_core
.seq
);
781 timekeeping_forward_now(tk
);
784 ts_delta
.tv_sec
= ts
->tv_sec
- xt
.tv_sec
;
785 ts_delta
.tv_nsec
= ts
->tv_nsec
- xt
.tv_nsec
;
787 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, ts_delta
));
789 tk_set_xtime(tk
, ts
);
791 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
793 write_seqcount_end(&tk_core
.seq
);
794 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
796 /* signal hrtimers about time change */
801 EXPORT_SYMBOL(do_settimeofday64
);
804 * timekeeping_inject_offset - Adds or subtracts from the current time.
805 * @tv: pointer to the timespec variable containing the offset
807 * Adds or subtracts an offset value from the current time.
809 int timekeeping_inject_offset(struct timespec
*ts
)
811 struct timekeeper
*tk
= &tk_core
.timekeeper
;
813 struct timespec64 ts64
, tmp
;
816 if ((unsigned long)ts
->tv_nsec
>= NSEC_PER_SEC
)
819 ts64
= timespec_to_timespec64(*ts
);
821 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
822 write_seqcount_begin(&tk_core
.seq
);
824 timekeeping_forward_now(tk
);
826 /* Make sure the proposed value is valid */
827 tmp
= timespec64_add(tk_xtime(tk
), ts64
);
828 if (!timespec64_valid_strict(&tmp
)) {
833 tk_xtime_add(tk
, &ts64
);
834 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, ts64
));
836 error
: /* even if we error out, we forwarded the time, so call update */
837 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
839 write_seqcount_end(&tk_core
.seq
);
840 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
842 /* signal hrtimers about time change */
847 EXPORT_SYMBOL(timekeeping_inject_offset
);
851 * timekeeping_get_tai_offset - Returns current TAI offset from UTC
854 s32
timekeeping_get_tai_offset(void)
856 struct timekeeper
*tk
= &tk_core
.timekeeper
;
861 seq
= read_seqcount_begin(&tk_core
.seq
);
862 ret
= tk
->tai_offset
;
863 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
869 * __timekeeping_set_tai_offset - Lock free worker function
872 static void __timekeeping_set_tai_offset(struct timekeeper
*tk
, s32 tai_offset
)
874 tk
->tai_offset
= tai_offset
;
875 tk
->offs_tai
= ktime_add(tk
->offs_real
, ktime_set(tai_offset
, 0));
879 * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
882 void timekeeping_set_tai_offset(s32 tai_offset
)
884 struct timekeeper
*tk
= &tk_core
.timekeeper
;
887 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
888 write_seqcount_begin(&tk_core
.seq
);
889 __timekeeping_set_tai_offset(tk
, tai_offset
);
890 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
891 write_seqcount_end(&tk_core
.seq
);
892 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
897 * change_clocksource - Swaps clocksources if a new one is available
899 * Accumulates current time interval and initializes new clocksource
901 static int change_clocksource(void *data
)
903 struct timekeeper
*tk
= &tk_core
.timekeeper
;
904 struct clocksource
*new, *old
;
907 new = (struct clocksource
*) data
;
909 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
910 write_seqcount_begin(&tk_core
.seq
);
912 timekeeping_forward_now(tk
);
914 * If the cs is in module, get a module reference. Succeeds
915 * for built-in code (owner == NULL) as well.
917 if (try_module_get(new->owner
)) {
918 if (!new->enable
|| new->enable(new) == 0) {
920 tk_setup_internals(tk
, new);
923 module_put(old
->owner
);
925 module_put(new->owner
);
928 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
930 write_seqcount_end(&tk_core
.seq
);
931 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
937 * timekeeping_notify - Install a new clock source
938 * @clock: pointer to the clock source
940 * This function is called from clocksource.c after a new, better clock
941 * source has been registered. The caller holds the clocksource_mutex.
943 int timekeeping_notify(struct clocksource
*clock
)
945 struct timekeeper
*tk
= &tk_core
.timekeeper
;
947 if (tk
->tkr
.clock
== clock
)
949 stop_machine(change_clocksource
, clock
, NULL
);
951 return tk
->tkr
.clock
== clock
? 0 : -1;
955 * getrawmonotonic64 - Returns the raw monotonic time in a timespec
956 * @ts: pointer to the timespec64 to be set
958 * Returns the raw monotonic time (completely un-modified by ntp)
960 void getrawmonotonic64(struct timespec64
*ts
)
962 struct timekeeper
*tk
= &tk_core
.timekeeper
;
963 struct timespec64 ts64
;
968 seq
= read_seqcount_begin(&tk_core
.seq
);
969 nsecs
= timekeeping_get_ns_raw(tk
);
972 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
974 timespec64_add_ns(&ts64
, nsecs
);
977 EXPORT_SYMBOL(getrawmonotonic64
);
981 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
983 int timekeeping_valid_for_hres(void)
985 struct timekeeper
*tk
= &tk_core
.timekeeper
;
990 seq
= read_seqcount_begin(&tk_core
.seq
);
992 ret
= tk
->tkr
.clock
->flags
& CLOCK_SOURCE_VALID_FOR_HRES
;
994 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1000 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1002 u64
timekeeping_max_deferment(void)
1004 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1009 seq
= read_seqcount_begin(&tk_core
.seq
);
1011 ret
= tk
->tkr
.clock
->max_idle_ns
;
1013 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1019 * read_persistent_clock - Return time from the persistent clock.
1021 * Weak dummy function for arches that do not yet support it.
1022 * Reads the time from the battery backed persistent clock.
1023 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1025 * XXX - Do be sure to remove it once all arches implement it.
1027 void __weak
read_persistent_clock(struct timespec
*ts
)
1034 * read_boot_clock - Return time of the system start.
1036 * Weak dummy function for arches that do not yet support it.
1037 * Function to read the exact time the system has been started.
1038 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1040 * XXX - Do be sure to remove it once all arches implement it.
1042 void __weak
read_boot_clock(struct timespec
*ts
)
1049 * timekeeping_init - Initializes the clocksource and common timekeeping values
1051 void __init
timekeeping_init(void)
1053 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1054 struct clocksource
*clock
;
1055 unsigned long flags
;
1056 struct timespec64 now
, boot
, tmp
;
1059 read_persistent_clock(&ts
);
1060 now
= timespec_to_timespec64(ts
);
1061 if (!timespec64_valid_strict(&now
)) {
1062 pr_warn("WARNING: Persistent clock returned invalid value!\n"
1063 " Check your CMOS/BIOS settings.\n");
1066 } else if (now
.tv_sec
|| now
.tv_nsec
)
1067 persistent_clock_exist
= true;
1069 read_boot_clock(&ts
);
1070 boot
= timespec_to_timespec64(ts
);
1071 if (!timespec64_valid_strict(&boot
)) {
1072 pr_warn("WARNING: Boot clock returned invalid value!\n"
1073 " Check your CMOS/BIOS settings.\n");
1078 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1079 write_seqcount_begin(&tk_core
.seq
);
1082 clock
= clocksource_default_clock();
1084 clock
->enable(clock
);
1085 tk_setup_internals(tk
, clock
);
1087 tk_set_xtime(tk
, &now
);
1088 tk
->raw_time
.tv_sec
= 0;
1089 tk
->raw_time
.tv_nsec
= 0;
1090 tk
->base_raw
.tv64
= 0;
1091 if (boot
.tv_sec
== 0 && boot
.tv_nsec
== 0)
1092 boot
= tk_xtime(tk
);
1094 set_normalized_timespec64(&tmp
, -boot
.tv_sec
, -boot
.tv_nsec
);
1095 tk_set_wall_to_mono(tk
, tmp
);
1097 timekeeping_update(tk
, TK_MIRROR
);
1099 write_seqcount_end(&tk_core
.seq
);
1100 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1103 /* time in seconds when suspend began */
1104 static struct timespec64 timekeeping_suspend_time
;
1107 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1108 * @delta: pointer to a timespec delta value
1110 * Takes a timespec offset measuring a suspend interval and properly
1111 * adds the sleep offset to the timekeeping variables.
1113 static void __timekeeping_inject_sleeptime(struct timekeeper
*tk
,
1114 struct timespec64
*delta
)
1116 if (!timespec64_valid_strict(delta
)) {
1117 printk_deferred(KERN_WARNING
1118 "__timekeeping_inject_sleeptime: Invalid "
1119 "sleep delta value!\n");
1122 tk_xtime_add(tk
, delta
);
1123 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, *delta
));
1124 tk_update_sleep_time(tk
, timespec64_to_ktime(*delta
));
1125 tk_debug_account_sleep_time(delta
);
1129 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1130 * @delta: pointer to a timespec64 delta value
1132 * This hook is for architectures that cannot support read_persistent_clock
1133 * because their RTC/persistent clock is only accessible when irqs are enabled.
1135 * This function should only be called by rtc_resume(), and allows
1136 * a suspend offset to be injected into the timekeeping values.
1138 void timekeeping_inject_sleeptime64(struct timespec64
*delta
)
1140 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1141 unsigned long flags
;
1144 * Make sure we don't set the clock twice, as timekeeping_resume()
1147 if (has_persistent_clock())
1150 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1151 write_seqcount_begin(&tk_core
.seq
);
1153 timekeeping_forward_now(tk
);
1155 __timekeeping_inject_sleeptime(tk
, delta
);
1157 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
1159 write_seqcount_end(&tk_core
.seq
);
1160 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1162 /* signal hrtimers about time change */
1167 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1169 * This is for the generic clocksource timekeeping.
1170 * xtime/wall_to_monotonic/jiffies/etc are
1171 * still managed by arch specific suspend/resume code.
1173 static void timekeeping_resume(void)
1175 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1176 struct clocksource
*clock
= tk
->tkr
.clock
;
1177 unsigned long flags
;
1178 struct timespec64 ts_new
, ts_delta
;
1179 struct timespec tmp
;
1180 cycle_t cycle_now
, cycle_delta
;
1181 bool suspendtime_found
= false;
1183 read_persistent_clock(&tmp
);
1184 ts_new
= timespec_to_timespec64(tmp
);
1186 clockevents_resume();
1187 clocksource_resume();
1189 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1190 write_seqcount_begin(&tk_core
.seq
);
1193 * After system resumes, we need to calculate the suspended time and
1194 * compensate it for the OS time. There are 3 sources that could be
1195 * used: Nonstop clocksource during suspend, persistent clock and rtc
1198 * One specific platform may have 1 or 2 or all of them, and the
1199 * preference will be:
1200 * suspend-nonstop clocksource -> persistent clock -> rtc
1201 * The less preferred source will only be tried if there is no better
1202 * usable source. The rtc part is handled separately in rtc core code.
1204 cycle_now
= tk
->tkr
.read(clock
);
1205 if ((clock
->flags
& CLOCK_SOURCE_SUSPEND_NONSTOP
) &&
1206 cycle_now
> tk
->tkr
.cycle_last
) {
1207 u64 num
, max
= ULLONG_MAX
;
1208 u32 mult
= clock
->mult
;
1209 u32 shift
= clock
->shift
;
1212 cycle_delta
= clocksource_delta(cycle_now
, tk
->tkr
.cycle_last
,
1216 * "cycle_delta * mutl" may cause 64 bits overflow, if the
1217 * suspended time is too long. In that case we need do the
1218 * 64 bits math carefully
1221 if (cycle_delta
> max
) {
1222 num
= div64_u64(cycle_delta
, max
);
1223 nsec
= (((u64
) max
* mult
) >> shift
) * num
;
1224 cycle_delta
-= num
* max
;
1226 nsec
+= ((u64
) cycle_delta
* mult
) >> shift
;
1228 ts_delta
= ns_to_timespec64(nsec
);
1229 suspendtime_found
= true;
1230 } else if (timespec64_compare(&ts_new
, &timekeeping_suspend_time
) > 0) {
1231 ts_delta
= timespec64_sub(ts_new
, timekeeping_suspend_time
);
1232 suspendtime_found
= true;
1235 if (suspendtime_found
)
1236 __timekeeping_inject_sleeptime(tk
, &ts_delta
);
1238 /* Re-base the last cycle value */
1239 tk
->tkr
.cycle_last
= cycle_now
;
1241 timekeeping_suspended
= 0;
1242 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
1243 write_seqcount_end(&tk_core
.seq
);
1244 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1246 touch_softlockup_watchdog();
1248 clockevents_notify(CLOCK_EVT_NOTIFY_RESUME
, NULL
);
1250 /* Resume hrtimers */
1254 static int timekeeping_suspend(void)
1256 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1257 unsigned long flags
;
1258 struct timespec64 delta
, delta_delta
;
1259 static struct timespec64 old_delta
;
1260 struct timespec tmp
;
1262 read_persistent_clock(&tmp
);
1263 timekeeping_suspend_time
= timespec_to_timespec64(tmp
);
1266 * On some systems the persistent_clock can not be detected at
1267 * timekeeping_init by its return value, so if we see a valid
1268 * value returned, update the persistent_clock_exists flag.
1270 if (timekeeping_suspend_time
.tv_sec
|| timekeeping_suspend_time
.tv_nsec
)
1271 persistent_clock_exist
= true;
1273 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1274 write_seqcount_begin(&tk_core
.seq
);
1275 timekeeping_forward_now(tk
);
1276 timekeeping_suspended
= 1;
1279 * To avoid drift caused by repeated suspend/resumes,
1280 * which each can add ~1 second drift error,
1281 * try to compensate so the difference in system time
1282 * and persistent_clock time stays close to constant.
1284 delta
= timespec64_sub(tk_xtime(tk
), timekeeping_suspend_time
);
1285 delta_delta
= timespec64_sub(delta
, old_delta
);
1286 if (abs(delta_delta
.tv_sec
) >= 2) {
1288 * if delta_delta is too large, assume time correction
1289 * has occured and set old_delta to the current delta.
1293 /* Otherwise try to adjust old_system to compensate */
1294 timekeeping_suspend_time
=
1295 timespec64_add(timekeeping_suspend_time
, delta_delta
);
1298 timekeeping_update(tk
, TK_MIRROR
);
1299 write_seqcount_end(&tk_core
.seq
);
1300 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1302 clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND
, NULL
);
1303 clocksource_suspend();
1304 clockevents_suspend();
1309 /* sysfs resume/suspend bits for timekeeping */
1310 static struct syscore_ops timekeeping_syscore_ops
= {
1311 .resume
= timekeeping_resume
,
1312 .suspend
= timekeeping_suspend
,
1315 static int __init
timekeeping_init_ops(void)
1317 register_syscore_ops(&timekeeping_syscore_ops
);
1320 device_initcall(timekeeping_init_ops
);
1323 * Apply a multiplier adjustment to the timekeeper
1325 static __always_inline
void timekeeping_apply_adjustment(struct timekeeper
*tk
,
1330 s64 interval
= tk
->cycle_interval
;
1334 mult_adj
= -mult_adj
;
1335 interval
= -interval
;
1338 mult_adj
<<= adj_scale
;
1339 interval
<<= adj_scale
;
1340 offset
<<= adj_scale
;
1343 * So the following can be confusing.
1345 * To keep things simple, lets assume mult_adj == 1 for now.
1347 * When mult_adj != 1, remember that the interval and offset values
1348 * have been appropriately scaled so the math is the same.
1350 * The basic idea here is that we're increasing the multiplier
1351 * by one, this causes the xtime_interval to be incremented by
1352 * one cycle_interval. This is because:
1353 * xtime_interval = cycle_interval * mult
1354 * So if mult is being incremented by one:
1355 * xtime_interval = cycle_interval * (mult + 1)
1357 * xtime_interval = (cycle_interval * mult) + cycle_interval
1358 * Which can be shortened to:
1359 * xtime_interval += cycle_interval
1361 * So offset stores the non-accumulated cycles. Thus the current
1362 * time (in shifted nanoseconds) is:
1363 * now = (offset * adj) + xtime_nsec
1364 * Now, even though we're adjusting the clock frequency, we have
1365 * to keep time consistent. In other words, we can't jump back
1366 * in time, and we also want to avoid jumping forward in time.
1368 * So given the same offset value, we need the time to be the same
1369 * both before and after the freq adjustment.
1370 * now = (offset * adj_1) + xtime_nsec_1
1371 * now = (offset * adj_2) + xtime_nsec_2
1373 * (offset * adj_1) + xtime_nsec_1 =
1374 * (offset * adj_2) + xtime_nsec_2
1378 * (offset * adj_1) + xtime_nsec_1 =
1379 * (offset * (adj_1+1)) + xtime_nsec_2
1380 * (offset * adj_1) + xtime_nsec_1 =
1381 * (offset * adj_1) + offset + xtime_nsec_2
1382 * Canceling the sides:
1383 * xtime_nsec_1 = offset + xtime_nsec_2
1385 * xtime_nsec_2 = xtime_nsec_1 - offset
1386 * Which simplfies to:
1387 * xtime_nsec -= offset
1389 * XXX - TODO: Doc ntp_error calculation.
1391 if ((mult_adj
> 0) && (tk
->tkr
.mult
+ mult_adj
< mult_adj
)) {
1392 /* NTP adjustment caused clocksource mult overflow */
1397 tk
->tkr
.mult
+= mult_adj
;
1398 tk
->xtime_interval
+= interval
;
1399 tk
->tkr
.xtime_nsec
-= offset
;
1400 tk
->ntp_error
-= (interval
- offset
) << tk
->ntp_error_shift
;
1404 * Calculate the multiplier adjustment needed to match the frequency
1407 static __always_inline
void timekeeping_freqadjust(struct timekeeper
*tk
,
1410 s64 interval
= tk
->cycle_interval
;
1411 s64 xinterval
= tk
->xtime_interval
;
1416 /* Remove any current error adj from freq calculation */
1417 if (tk
->ntp_err_mult
)
1418 xinterval
-= tk
->cycle_interval
;
1420 tk
->ntp_tick
= ntp_tick_length();
1422 /* Calculate current error per tick */
1423 tick_error
= ntp_tick_length() >> tk
->ntp_error_shift
;
1424 tick_error
-= (xinterval
+ tk
->xtime_remainder
);
1426 /* Don't worry about correcting it if its small */
1427 if (likely((tick_error
>= 0) && (tick_error
<= interval
)))
1430 /* preserve the direction of correction */
1431 negative
= (tick_error
< 0);
1433 /* Sort out the magnitude of the correction */
1434 tick_error
= abs(tick_error
);
1435 for (adj
= 0; tick_error
> interval
; adj
++)
1438 /* scale the corrections */
1439 timekeeping_apply_adjustment(tk
, offset
, negative
, adj
);
1443 * Adjust the timekeeper's multiplier to the correct frequency
1444 * and also to reduce the accumulated error value.
1446 static void timekeeping_adjust(struct timekeeper
*tk
, s64 offset
)
1448 /* Correct for the current frequency error */
1449 timekeeping_freqadjust(tk
, offset
);
1451 /* Next make a small adjustment to fix any cumulative error */
1452 if (!tk
->ntp_err_mult
&& (tk
->ntp_error
> 0)) {
1453 tk
->ntp_err_mult
= 1;
1454 timekeeping_apply_adjustment(tk
, offset
, 0, 0);
1455 } else if (tk
->ntp_err_mult
&& (tk
->ntp_error
<= 0)) {
1456 /* Undo any existing error adjustment */
1457 timekeeping_apply_adjustment(tk
, offset
, 1, 0);
1458 tk
->ntp_err_mult
= 0;
1461 if (unlikely(tk
->tkr
.clock
->maxadj
&&
1462 (abs(tk
->tkr
.mult
- tk
->tkr
.clock
->mult
)
1463 > tk
->tkr
.clock
->maxadj
))) {
1464 printk_once(KERN_WARNING
1465 "Adjusting %s more than 11%% (%ld vs %ld)\n",
1466 tk
->tkr
.clock
->name
, (long)tk
->tkr
.mult
,
1467 (long)tk
->tkr
.clock
->mult
+ tk
->tkr
.clock
->maxadj
);
1471 * It may be possible that when we entered this function, xtime_nsec
1472 * was very small. Further, if we're slightly speeding the clocksource
1473 * in the code above, its possible the required corrective factor to
1474 * xtime_nsec could cause it to underflow.
1476 * Now, since we already accumulated the second, cannot simply roll
1477 * the accumulated second back, since the NTP subsystem has been
1478 * notified via second_overflow. So instead we push xtime_nsec forward
1479 * by the amount we underflowed, and add that amount into the error.
1481 * We'll correct this error next time through this function, when
1482 * xtime_nsec is not as small.
1484 if (unlikely((s64
)tk
->tkr
.xtime_nsec
< 0)) {
1485 s64 neg
= -(s64
)tk
->tkr
.xtime_nsec
;
1486 tk
->tkr
.xtime_nsec
= 0;
1487 tk
->ntp_error
+= neg
<< tk
->ntp_error_shift
;
1492 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1494 * Helper function that accumulates a the nsecs greater then a second
1495 * from the xtime_nsec field to the xtime_secs field.
1496 * It also calls into the NTP code to handle leapsecond processing.
1499 static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper
*tk
)
1501 u64 nsecps
= (u64
)NSEC_PER_SEC
<< tk
->tkr
.shift
;
1502 unsigned int clock_set
= 0;
1504 while (tk
->tkr
.xtime_nsec
>= nsecps
) {
1507 tk
->tkr
.xtime_nsec
-= nsecps
;
1510 /* Figure out if its a leap sec and apply if needed */
1511 leap
= second_overflow(tk
->xtime_sec
);
1512 if (unlikely(leap
)) {
1513 struct timespec64 ts
;
1515 tk
->xtime_sec
+= leap
;
1519 tk_set_wall_to_mono(tk
,
1520 timespec64_sub(tk
->wall_to_monotonic
, ts
));
1522 __timekeeping_set_tai_offset(tk
, tk
->tai_offset
- leap
);
1524 clock_set
= TK_CLOCK_WAS_SET
;
1531 * logarithmic_accumulation - shifted accumulation of cycles
1533 * This functions accumulates a shifted interval of cycles into
1534 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1537 * Returns the unconsumed cycles.
1539 static cycle_t
logarithmic_accumulation(struct timekeeper
*tk
, cycle_t offset
,
1541 unsigned int *clock_set
)
1543 cycle_t interval
= tk
->cycle_interval
<< shift
;
1546 /* If the offset is smaller then a shifted interval, do nothing */
1547 if (offset
< interval
)
1550 /* Accumulate one shifted interval */
1552 tk
->tkr
.cycle_last
+= interval
;
1554 tk
->tkr
.xtime_nsec
+= tk
->xtime_interval
<< shift
;
1555 *clock_set
|= accumulate_nsecs_to_secs(tk
);
1557 /* Accumulate raw time */
1558 raw_nsecs
= (u64
)tk
->raw_interval
<< shift
;
1559 raw_nsecs
+= tk
->raw_time
.tv_nsec
;
1560 if (raw_nsecs
>= NSEC_PER_SEC
) {
1561 u64 raw_secs
= raw_nsecs
;
1562 raw_nsecs
= do_div(raw_secs
, NSEC_PER_SEC
);
1563 tk
->raw_time
.tv_sec
+= raw_secs
;
1565 tk
->raw_time
.tv_nsec
= raw_nsecs
;
1567 /* Accumulate error between NTP and clock interval */
1568 tk
->ntp_error
+= tk
->ntp_tick
<< shift
;
1569 tk
->ntp_error
-= (tk
->xtime_interval
+ tk
->xtime_remainder
) <<
1570 (tk
->ntp_error_shift
+ shift
);
1576 * update_wall_time - Uses the current clocksource to increment the wall time
1579 void update_wall_time(void)
1581 struct timekeeper
*real_tk
= &tk_core
.timekeeper
;
1582 struct timekeeper
*tk
= &shadow_timekeeper
;
1584 int shift
= 0, maxshift
;
1585 unsigned int clock_set
= 0;
1586 unsigned long flags
;
1588 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1590 /* Make sure we're fully resumed: */
1591 if (unlikely(timekeeping_suspended
))
1594 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1595 offset
= real_tk
->cycle_interval
;
1597 offset
= clocksource_delta(tk
->tkr
.read(tk
->tkr
.clock
),
1598 tk
->tkr
.cycle_last
, tk
->tkr
.mask
);
1601 /* Check if there's really nothing to do */
1602 if (offset
< real_tk
->cycle_interval
)
1606 * With NO_HZ we may have to accumulate many cycle_intervals
1607 * (think "ticks") worth of time at once. To do this efficiently,
1608 * we calculate the largest doubling multiple of cycle_intervals
1609 * that is smaller than the offset. We then accumulate that
1610 * chunk in one go, and then try to consume the next smaller
1613 shift
= ilog2(offset
) - ilog2(tk
->cycle_interval
);
1614 shift
= max(0, shift
);
1615 /* Bound shift to one less than what overflows tick_length */
1616 maxshift
= (64 - (ilog2(ntp_tick_length())+1)) - 1;
1617 shift
= min(shift
, maxshift
);
1618 while (offset
>= tk
->cycle_interval
) {
1619 offset
= logarithmic_accumulation(tk
, offset
, shift
,
1621 if (offset
< tk
->cycle_interval
<<shift
)
1625 /* correct the clock when NTP error is too big */
1626 timekeeping_adjust(tk
, offset
);
1629 * XXX This can be killed once everyone converts
1630 * to the new update_vsyscall.
1632 old_vsyscall_fixup(tk
);
1635 * Finally, make sure that after the rounding
1636 * xtime_nsec isn't larger than NSEC_PER_SEC
1638 clock_set
|= accumulate_nsecs_to_secs(tk
);
1640 write_seqcount_begin(&tk_core
.seq
);
1642 * Update the real timekeeper.
1644 * We could avoid this memcpy by switching pointers, but that
1645 * requires changes to all other timekeeper usage sites as
1646 * well, i.e. move the timekeeper pointer getter into the
1647 * spinlocked/seqcount protected sections. And we trade this
1648 * memcpy under the tk_core.seq against one before we start
1651 memcpy(real_tk
, tk
, sizeof(*tk
));
1652 timekeeping_update(real_tk
, clock_set
);
1653 write_seqcount_end(&tk_core
.seq
);
1655 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1657 /* Have to call _delayed version, since in irq context*/
1658 clock_was_set_delayed();
1662 * getboottime64 - Return the real time of system boot.
1663 * @ts: pointer to the timespec64 to be set
1665 * Returns the wall-time of boot in a timespec64.
1667 * This is based on the wall_to_monotonic offset and the total suspend
1668 * time. Calls to settimeofday will affect the value returned (which
1669 * basically means that however wrong your real time clock is at boot time,
1670 * you get the right time here).
1672 void getboottime64(struct timespec64
*ts
)
1674 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1675 ktime_t t
= ktime_sub(tk
->offs_real
, tk
->offs_boot
);
1677 *ts
= ktime_to_timespec64(t
);
1679 EXPORT_SYMBOL_GPL(getboottime64
);
1681 unsigned long get_seconds(void)
1683 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1685 return tk
->xtime_sec
;
1687 EXPORT_SYMBOL(get_seconds
);
1689 struct timespec
__current_kernel_time(void)
1691 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1693 return timespec64_to_timespec(tk_xtime(tk
));
1696 struct timespec
current_kernel_time(void)
1698 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1699 struct timespec64 now
;
1703 seq
= read_seqcount_begin(&tk_core
.seq
);
1706 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1708 return timespec64_to_timespec(now
);
1710 EXPORT_SYMBOL(current_kernel_time
);
1712 struct timespec64
get_monotonic_coarse64(void)
1714 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1715 struct timespec64 now
, mono
;
1719 seq
= read_seqcount_begin(&tk_core
.seq
);
1722 mono
= tk
->wall_to_monotonic
;
1723 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1725 set_normalized_timespec64(&now
, now
.tv_sec
+ mono
.tv_sec
,
1726 now
.tv_nsec
+ mono
.tv_nsec
);
1732 * Must hold jiffies_lock
1734 void do_timer(unsigned long ticks
)
1736 jiffies_64
+= ticks
;
1737 calc_global_load(ticks
);
1741 * ktime_get_update_offsets_tick - hrtimer helper
1742 * @offs_real: pointer to storage for monotonic -> realtime offset
1743 * @offs_boot: pointer to storage for monotonic -> boottime offset
1744 * @offs_tai: pointer to storage for monotonic -> clock tai offset
1746 * Returns monotonic time at last tick and various offsets
1748 ktime_t
ktime_get_update_offsets_tick(ktime_t
*offs_real
, ktime_t
*offs_boot
,
1751 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1757 seq
= read_seqcount_begin(&tk_core
.seq
);
1759 base
= tk
->tkr
.base_mono
;
1760 nsecs
= tk
->tkr
.xtime_nsec
>> tk
->tkr
.shift
;
1762 *offs_real
= tk
->offs_real
;
1763 *offs_boot
= tk
->offs_boot
;
1764 *offs_tai
= tk
->offs_tai
;
1765 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1767 return ktime_add_ns(base
, nsecs
);
1770 #ifdef CONFIG_HIGH_RES_TIMERS
1772 * ktime_get_update_offsets_now - hrtimer helper
1773 * @offs_real: pointer to storage for monotonic -> realtime offset
1774 * @offs_boot: pointer to storage for monotonic -> boottime offset
1775 * @offs_tai: pointer to storage for monotonic -> clock tai offset
1777 * Returns current monotonic time and updates the offsets
1778 * Called from hrtimer_interrupt() or retrigger_next_event()
1780 ktime_t
ktime_get_update_offsets_now(ktime_t
*offs_real
, ktime_t
*offs_boot
,
1783 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1789 seq
= read_seqcount_begin(&tk_core
.seq
);
1791 base
= tk
->tkr
.base_mono
;
1792 nsecs
= timekeeping_get_ns(&tk
->tkr
);
1794 *offs_real
= tk
->offs_real
;
1795 *offs_boot
= tk
->offs_boot
;
1796 *offs_tai
= tk
->offs_tai
;
1797 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1799 return ktime_add_ns(base
, nsecs
);
1804 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
1806 int do_adjtimex(struct timex
*txc
)
1808 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1809 unsigned long flags
;
1810 struct timespec64 ts
;
1814 /* Validate the data before disabling interrupts */
1815 ret
= ntp_validate_timex(txc
);
1819 if (txc
->modes
& ADJ_SETOFFSET
) {
1820 struct timespec delta
;
1821 delta
.tv_sec
= txc
->time
.tv_sec
;
1822 delta
.tv_nsec
= txc
->time
.tv_usec
;
1823 if (!(txc
->modes
& ADJ_NANO
))
1824 delta
.tv_nsec
*= 1000;
1825 ret
= timekeeping_inject_offset(&delta
);
1830 getnstimeofday64(&ts
);
1832 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1833 write_seqcount_begin(&tk_core
.seq
);
1835 orig_tai
= tai
= tk
->tai_offset
;
1836 ret
= __do_adjtimex(txc
, &ts
, &tai
);
1838 if (tai
!= orig_tai
) {
1839 __timekeeping_set_tai_offset(tk
, tai
);
1840 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
1842 write_seqcount_end(&tk_core
.seq
);
1843 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1845 if (tai
!= orig_tai
)
1848 ntp_notify_cmos_timer();
1853 #ifdef CONFIG_NTP_PPS
1855 * hardpps() - Accessor function to NTP __hardpps function
1857 void hardpps(const struct timespec
*phase_ts
, const struct timespec
*raw_ts
)
1859 unsigned long flags
;
1861 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1862 write_seqcount_begin(&tk_core
.seq
);
1864 __hardpps(phase_ts
, raw_ts
);
1866 write_seqcount_end(&tk_core
.seq
);
1867 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1869 EXPORT_SYMBOL(hardpps
);
1873 * xtime_update() - advances the timekeeping infrastructure
1874 * @ticks: number of ticks, that have elapsed since the last call.
1876 * Must be called with interrupts disabled.
1878 void xtime_update(unsigned long ticks
)
1880 write_seqlock(&jiffies_lock
);
1882 write_sequnlock(&jiffies_lock
);