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
;
62 static struct tk_fast tk_fast_raw ____cacheline_aligned
;
64 /* flag for if timekeeping is suspended */
65 int __read_mostly timekeeping_suspended
;
67 /* Flag for if there is a persistent clock on this platform */
68 bool __read_mostly persistent_clock_exist
= false;
70 static inline void tk_normalize_xtime(struct timekeeper
*tk
)
72 while (tk
->tkr_mono
.xtime_nsec
>= ((u64
)NSEC_PER_SEC
<< tk
->tkr_mono
.shift
)) {
73 tk
->tkr_mono
.xtime_nsec
-= (u64
)NSEC_PER_SEC
<< tk
->tkr_mono
.shift
;
78 static inline struct timespec64
tk_xtime(struct timekeeper
*tk
)
82 ts
.tv_sec
= tk
->xtime_sec
;
83 ts
.tv_nsec
= (long)(tk
->tkr_mono
.xtime_nsec
>> tk
->tkr_mono
.shift
);
87 static void tk_set_xtime(struct timekeeper
*tk
, const struct timespec64
*ts
)
89 tk
->xtime_sec
= ts
->tv_sec
;
90 tk
->tkr_mono
.xtime_nsec
= (u64
)ts
->tv_nsec
<< tk
->tkr_mono
.shift
;
93 static void tk_xtime_add(struct timekeeper
*tk
, const struct timespec64
*ts
)
95 tk
->xtime_sec
+= ts
->tv_sec
;
96 tk
->tkr_mono
.xtime_nsec
+= (u64
)ts
->tv_nsec
<< tk
->tkr_mono
.shift
;
97 tk_normalize_xtime(tk
);
100 static void tk_set_wall_to_mono(struct timekeeper
*tk
, struct timespec64 wtm
)
102 struct timespec64 tmp
;
105 * Verify consistency of: offset_real = -wall_to_monotonic
106 * before modifying anything
108 set_normalized_timespec64(&tmp
, -tk
->wall_to_monotonic
.tv_sec
,
109 -tk
->wall_to_monotonic
.tv_nsec
);
110 WARN_ON_ONCE(tk
->offs_real
.tv64
!= timespec64_to_ktime(tmp
).tv64
);
111 tk
->wall_to_monotonic
= wtm
;
112 set_normalized_timespec64(&tmp
, -wtm
.tv_sec
, -wtm
.tv_nsec
);
113 tk
->offs_real
= timespec64_to_ktime(tmp
);
114 tk
->offs_tai
= ktime_add(tk
->offs_real
, ktime_set(tk
->tai_offset
, 0));
117 static inline void tk_update_sleep_time(struct timekeeper
*tk
, ktime_t delta
)
119 tk
->offs_boot
= ktime_add(tk
->offs_boot
, delta
);
122 #ifdef CONFIG_DEBUG_TIMEKEEPING
123 #define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
125 * These simple flag variables are managed
126 * without locks, which is racy, but ok since
127 * we don't really care about being super
128 * precise about how many events were seen,
129 * just that a problem was observed.
131 static int timekeeping_underflow_seen
;
132 static int timekeeping_overflow_seen
;
134 /* last_warning is only modified under the timekeeping lock */
135 static long timekeeping_last_warning
;
137 static void timekeeping_check_update(struct timekeeper
*tk
, cycle_t offset
)
140 cycle_t max_cycles
= tk
->tkr_mono
.clock
->max_cycles
;
141 const char *name
= tk
->tkr_mono
.clock
->name
;
143 if (offset
> max_cycles
) {
144 printk_deferred("WARNING: timekeeping: Cycle offset (%lld) is larger than allowed by the '%s' clock's max_cycles value (%lld): time overflow danger\n",
145 offset
, name
, max_cycles
);
146 printk_deferred(" timekeeping: Your kernel is sick, but tries to cope by capping time updates\n");
148 if (offset
> (max_cycles
>> 1)) {
149 printk_deferred("INFO: timekeeping: Cycle offset (%lld) is larger than the the '%s' clock's 50%% safety margin (%lld)\n",
150 offset
, name
, max_cycles
>> 1);
151 printk_deferred(" timekeeping: Your kernel is still fine, but is feeling a bit nervous\n");
155 if (timekeeping_underflow_seen
) {
156 if (jiffies
- timekeeping_last_warning
> WARNING_FREQ
) {
157 printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name
);
158 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
159 printk_deferred(" Your kernel is probably still fine.\n");
160 timekeeping_last_warning
= jiffies
;
162 timekeeping_underflow_seen
= 0;
165 if (timekeeping_overflow_seen
) {
166 if (jiffies
- timekeeping_last_warning
> WARNING_FREQ
) {
167 printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name
);
168 printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
169 printk_deferred(" Your kernel is probably still fine.\n");
170 timekeeping_last_warning
= jiffies
;
172 timekeeping_overflow_seen
= 0;
176 static inline cycle_t
timekeeping_get_delta(struct tk_read_base
*tkr
)
178 cycle_t now
, last
, mask
, max
, delta
;
182 * Since we're called holding a seqlock, the data may shift
183 * under us while we're doing the calculation. This can cause
184 * false positives, since we'd note a problem but throw the
185 * results away. So nest another seqlock here to atomically
186 * grab the points we are checking with.
189 seq
= read_seqcount_begin(&tk_core
.seq
);
190 now
= tkr
->read(tkr
->clock
);
191 last
= tkr
->cycle_last
;
193 max
= tkr
->clock
->max_cycles
;
194 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
196 delta
= clocksource_delta(now
, last
, mask
);
199 * Try to catch underflows by checking if we are seeing small
200 * mask-relative negative values.
202 if (unlikely((~delta
& mask
) < (mask
>> 3))) {
203 timekeeping_underflow_seen
= 1;
207 /* Cap delta value to the max_cycles values to avoid mult overflows */
208 if (unlikely(delta
> max
)) {
209 timekeeping_overflow_seen
= 1;
210 delta
= tkr
->clock
->max_cycles
;
216 static inline void timekeeping_check_update(struct timekeeper
*tk
, cycle_t offset
)
219 static inline cycle_t
timekeeping_get_delta(struct tk_read_base
*tkr
)
221 cycle_t cycle_now
, delta
;
223 /* read clocksource */
224 cycle_now
= tkr
->read(tkr
->clock
);
226 /* calculate the delta since the last update_wall_time */
227 delta
= clocksource_delta(cycle_now
, tkr
->cycle_last
, tkr
->mask
);
234 * tk_setup_internals - Set up internals to use clocksource clock.
236 * @tk: The target timekeeper to setup.
237 * @clock: Pointer to clocksource.
239 * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
240 * pair and interval request.
242 * Unless you're the timekeeping code, you should not be using this!
244 static void tk_setup_internals(struct timekeeper
*tk
, struct clocksource
*clock
)
247 u64 tmp
, ntpinterval
;
248 struct clocksource
*old_clock
;
250 old_clock
= tk
->tkr_mono
.clock
;
251 tk
->tkr_mono
.clock
= clock
;
252 tk
->tkr_mono
.read
= clock
->read
;
253 tk
->tkr_mono
.mask
= clock
->mask
;
254 tk
->tkr_mono
.cycle_last
= tk
->tkr_mono
.read(clock
);
256 tk
->tkr_raw
.clock
= clock
;
257 tk
->tkr_raw
.read
= clock
->read
;
258 tk
->tkr_raw
.mask
= clock
->mask
;
259 tk
->tkr_raw
.cycle_last
= tk
->tkr_mono
.cycle_last
;
261 /* Do the ns -> cycle conversion first, using original mult */
262 tmp
= NTP_INTERVAL_LENGTH
;
263 tmp
<<= clock
->shift
;
265 tmp
+= clock
->mult
/2;
266 do_div(tmp
, clock
->mult
);
270 interval
= (cycle_t
) tmp
;
271 tk
->cycle_interval
= interval
;
273 /* Go back from cycles -> shifted ns */
274 tk
->xtime_interval
= (u64
) interval
* clock
->mult
;
275 tk
->xtime_remainder
= ntpinterval
- tk
->xtime_interval
;
277 ((u64
) interval
* clock
->mult
) >> clock
->shift
;
279 /* if changing clocks, convert xtime_nsec shift units */
281 int shift_change
= clock
->shift
- old_clock
->shift
;
282 if (shift_change
< 0)
283 tk
->tkr_mono
.xtime_nsec
>>= -shift_change
;
285 tk
->tkr_mono
.xtime_nsec
<<= shift_change
;
287 tk
->tkr_raw
.xtime_nsec
= 0;
289 tk
->tkr_mono
.shift
= clock
->shift
;
290 tk
->tkr_raw
.shift
= clock
->shift
;
293 tk
->ntp_error_shift
= NTP_SCALE_SHIFT
- clock
->shift
;
294 tk
->ntp_tick
= ntpinterval
<< tk
->ntp_error_shift
;
297 * The timekeeper keeps its own mult values for the currently
298 * active clocksource. These value will be adjusted via NTP
299 * to counteract clock drifting.
301 tk
->tkr_mono
.mult
= clock
->mult
;
302 tk
->tkr_raw
.mult
= clock
->mult
;
303 tk
->ntp_err_mult
= 0;
306 /* Timekeeper helper functions. */
308 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
309 static u32
default_arch_gettimeoffset(void) { return 0; }
310 u32 (*arch_gettimeoffset
)(void) = default_arch_gettimeoffset
;
312 static inline u32
arch_gettimeoffset(void) { return 0; }
315 static inline s64
timekeeping_get_ns(struct tk_read_base
*tkr
)
320 delta
= timekeeping_get_delta(tkr
);
322 nsec
= delta
* tkr
->mult
+ tkr
->xtime_nsec
;
325 /* If arch requires, add in get_arch_timeoffset() */
326 return nsec
+ arch_gettimeoffset();
330 * update_fast_timekeeper - Update the fast and NMI safe monotonic timekeeper.
331 * @tkr: Timekeeping readout base from which we take the update
333 * We want to use this from any context including NMI and tracing /
334 * instrumenting the timekeeping code itself.
336 * So we handle this differently than the other timekeeping accessor
337 * functions which retry when the sequence count has changed. The
340 * smp_wmb(); <- Ensure that the last base[1] update is visible
342 * smp_wmb(); <- Ensure that the seqcount update is visible
343 * update(tkf->base[0], tkr);
344 * smp_wmb(); <- Ensure that the base[0] update is visible
346 * smp_wmb(); <- Ensure that the seqcount update is visible
347 * update(tkf->base[1], tkr);
349 * The reader side does:
355 * now = now(tkf->base[idx]);
357 * } while (seq != tkf->seq)
359 * As long as we update base[0] readers are forced off to
360 * base[1]. Once base[0] is updated readers are redirected to base[0]
361 * and the base[1] update takes place.
363 * So if a NMI hits the update of base[0] then it will use base[1]
364 * which is still consistent. In the worst case this can result is a
365 * slightly wrong timestamp (a few nanoseconds). See
366 * @ktime_get_mono_fast_ns.
368 static void update_fast_timekeeper(struct tk_read_base
*tkr
, struct tk_fast
*tkf
)
370 struct tk_read_base
*base
= tkf
->base
;
372 /* Force readers off to base[1] */
373 raw_write_seqcount_latch(&tkf
->seq
);
376 memcpy(base
, tkr
, sizeof(*base
));
378 /* Force readers back to base[0] */
379 raw_write_seqcount_latch(&tkf
->seq
);
382 memcpy(base
+ 1, base
, sizeof(*base
));
386 * ktime_get_mono_fast_ns - Fast NMI safe access to clock monotonic
388 * This timestamp is not guaranteed to be monotonic across an update.
389 * The timestamp is calculated by:
391 * now = base_mono + clock_delta * slope
393 * So if the update lowers the slope, readers who are forced to the
394 * not yet updated second array are still using the old steeper slope.
403 * |12345678---> reader order
409 * So reader 6 will observe time going backwards versus reader 5.
411 * While other CPUs are likely to be able observe that, the only way
412 * for a CPU local observation is when an NMI hits in the middle of
413 * the update. Timestamps taken from that NMI context might be ahead
414 * of the following timestamps. Callers need to be aware of that and
417 static __always_inline u64
__ktime_get_fast_ns(struct tk_fast
*tkf
)
419 struct tk_read_base
*tkr
;
424 seq
= raw_read_seqcount(&tkf
->seq
);
425 tkr
= tkf
->base
+ (seq
& 0x01);
426 now
= ktime_to_ns(tkr
->base
) + timekeeping_get_ns(tkr
);
427 } while (read_seqcount_retry(&tkf
->seq
, seq
));
432 u64
ktime_get_mono_fast_ns(void)
434 return __ktime_get_fast_ns(&tk_fast_mono
);
436 EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns
);
438 u64
ktime_get_raw_fast_ns(void)
440 return __ktime_get_fast_ns(&tk_fast_raw
);
442 EXPORT_SYMBOL_GPL(ktime_get_raw_fast_ns
);
444 /* Suspend-time cycles value for halted fast timekeeper. */
445 static cycle_t cycles_at_suspend
;
447 static cycle_t
dummy_clock_read(struct clocksource
*cs
)
449 return cycles_at_suspend
;
453 * halt_fast_timekeeper - Prevent fast timekeeper from accessing clocksource.
454 * @tk: Timekeeper to snapshot.
456 * It generally is unsafe to access the clocksource after timekeeping has been
457 * suspended, so take a snapshot of the readout base of @tk and use it as the
458 * fast timekeeper's readout base while suspended. It will return the same
459 * number of cycles every time until timekeeping is resumed at which time the
460 * proper readout base for the fast timekeeper will be restored automatically.
462 static void halt_fast_timekeeper(struct timekeeper
*tk
)
464 static struct tk_read_base tkr_dummy
;
465 struct tk_read_base
*tkr
= &tk
->tkr_mono
;
467 memcpy(&tkr_dummy
, tkr
, sizeof(tkr_dummy
));
468 cycles_at_suspend
= tkr
->read(tkr
->clock
);
469 tkr_dummy
.read
= dummy_clock_read
;
470 update_fast_timekeeper(&tkr_dummy
, &tk_fast_mono
);
473 memcpy(&tkr_dummy
, tkr
, sizeof(tkr_dummy
));
474 tkr_dummy
.read
= dummy_clock_read
;
475 update_fast_timekeeper(&tkr_dummy
, &tk_fast_raw
);
478 #ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
480 static inline void update_vsyscall(struct timekeeper
*tk
)
482 struct timespec xt
, wm
;
484 xt
= timespec64_to_timespec(tk_xtime(tk
));
485 wm
= timespec64_to_timespec(tk
->wall_to_monotonic
);
486 update_vsyscall_old(&xt
, &wm
, tk
->tkr_mono
.clock
, tk
->tkr_mono
.mult
,
487 tk
->tkr_mono
.cycle_last
);
490 static inline void old_vsyscall_fixup(struct timekeeper
*tk
)
495 * Store only full nanoseconds into xtime_nsec after rounding
496 * it up and add the remainder to the error difference.
497 * XXX - This is necessary to avoid small 1ns inconsistnecies caused
498 * by truncating the remainder in vsyscalls. However, it causes
499 * additional work to be done in timekeeping_adjust(). Once
500 * the vsyscall implementations are converted to use xtime_nsec
501 * (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
502 * users are removed, this can be killed.
504 remainder
= tk
->tkr_mono
.xtime_nsec
& ((1ULL << tk
->tkr_mono
.shift
) - 1);
505 tk
->tkr_mono
.xtime_nsec
-= remainder
;
506 tk
->tkr_mono
.xtime_nsec
+= 1ULL << tk
->tkr_mono
.shift
;
507 tk
->ntp_error
+= remainder
<< tk
->ntp_error_shift
;
508 tk
->ntp_error
-= (1ULL << tk
->tkr_mono
.shift
) << tk
->ntp_error_shift
;
511 #define old_vsyscall_fixup(tk)
514 static RAW_NOTIFIER_HEAD(pvclock_gtod_chain
);
516 static void update_pvclock_gtod(struct timekeeper
*tk
, bool was_set
)
518 raw_notifier_call_chain(&pvclock_gtod_chain
, was_set
, tk
);
522 * pvclock_gtod_register_notifier - register a pvclock timedata update listener
524 int pvclock_gtod_register_notifier(struct notifier_block
*nb
)
526 struct timekeeper
*tk
= &tk_core
.timekeeper
;
530 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
531 ret
= raw_notifier_chain_register(&pvclock_gtod_chain
, nb
);
532 update_pvclock_gtod(tk
, true);
533 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
537 EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier
);
540 * pvclock_gtod_unregister_notifier - unregister a pvclock
541 * timedata update listener
543 int pvclock_gtod_unregister_notifier(struct notifier_block
*nb
)
548 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
549 ret
= raw_notifier_chain_unregister(&pvclock_gtod_chain
, nb
);
550 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
554 EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier
);
557 * Update the ktime_t based scalar nsec members of the timekeeper
559 static inline void tk_update_ktime_data(struct timekeeper
*tk
)
565 * The xtime based monotonic readout is:
566 * nsec = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec + now();
567 * The ktime based monotonic readout is:
568 * nsec = base_mono + now();
569 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
571 seconds
= (u64
)(tk
->xtime_sec
+ tk
->wall_to_monotonic
.tv_sec
);
572 nsec
= (u32
) tk
->wall_to_monotonic
.tv_nsec
;
573 tk
->tkr_mono
.base
= ns_to_ktime(seconds
* NSEC_PER_SEC
+ nsec
);
575 /* Update the monotonic raw base */
576 tk
->tkr_raw
.base
= timespec64_to_ktime(tk
->raw_time
);
579 * The sum of the nanoseconds portions of xtime and
580 * wall_to_monotonic can be greater/equal one second. Take
581 * this into account before updating tk->ktime_sec.
583 nsec
+= (u32
)(tk
->tkr_mono
.xtime_nsec
>> tk
->tkr_mono
.shift
);
584 if (nsec
>= NSEC_PER_SEC
)
586 tk
->ktime_sec
= seconds
;
589 /* must hold timekeeper_lock */
590 static void timekeeping_update(struct timekeeper
*tk
, unsigned int action
)
592 if (action
& TK_CLEAR_NTP
) {
597 tk_update_ktime_data(tk
);
600 update_pvclock_gtod(tk
, action
& TK_CLOCK_WAS_SET
);
602 if (action
& TK_MIRROR
)
603 memcpy(&shadow_timekeeper
, &tk_core
.timekeeper
,
604 sizeof(tk_core
.timekeeper
));
606 update_fast_timekeeper(&tk
->tkr_mono
, &tk_fast_mono
);
607 update_fast_timekeeper(&tk
->tkr_raw
, &tk_fast_raw
);
611 * timekeeping_forward_now - update clock to the current time
613 * Forward the current clock to update its state since the last call to
614 * update_wall_time(). This is useful before significant clock changes,
615 * as it avoids having to deal with this time offset explicitly.
617 static void timekeeping_forward_now(struct timekeeper
*tk
)
619 struct clocksource
*clock
= tk
->tkr_mono
.clock
;
620 cycle_t cycle_now
, delta
;
623 cycle_now
= tk
->tkr_mono
.read(clock
);
624 delta
= clocksource_delta(cycle_now
, tk
->tkr_mono
.cycle_last
, tk
->tkr_mono
.mask
);
625 tk
->tkr_mono
.cycle_last
= cycle_now
;
626 tk
->tkr_raw
.cycle_last
= cycle_now
;
628 tk
->tkr_mono
.xtime_nsec
+= delta
* tk
->tkr_mono
.mult
;
630 /* If arch requires, add in get_arch_timeoffset() */
631 tk
->tkr_mono
.xtime_nsec
+= (u64
)arch_gettimeoffset() << tk
->tkr_mono
.shift
;
633 tk_normalize_xtime(tk
);
635 nsec
= clocksource_cyc2ns(delta
, tk
->tkr_raw
.mult
, tk
->tkr_raw
.shift
);
636 timespec64_add_ns(&tk
->raw_time
, nsec
);
640 * __getnstimeofday64 - Returns the time of day in a timespec64.
641 * @ts: pointer to the timespec to be set
643 * Updates the time of day in the timespec.
644 * Returns 0 on success, or -ve when suspended (timespec will be undefined).
646 int __getnstimeofday64(struct timespec64
*ts
)
648 struct timekeeper
*tk
= &tk_core
.timekeeper
;
653 seq
= read_seqcount_begin(&tk_core
.seq
);
655 ts
->tv_sec
= tk
->xtime_sec
;
656 nsecs
= timekeeping_get_ns(&tk
->tkr_mono
);
658 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
661 timespec64_add_ns(ts
, nsecs
);
664 * Do not bail out early, in case there were callers still using
665 * the value, even in the face of the WARN_ON.
667 if (unlikely(timekeeping_suspended
))
671 EXPORT_SYMBOL(__getnstimeofday64
);
674 * getnstimeofday64 - Returns the time of day in a timespec64.
675 * @ts: pointer to the timespec64 to be set
677 * Returns the time of day in a timespec64 (WARN if suspended).
679 void getnstimeofday64(struct timespec64
*ts
)
681 WARN_ON(__getnstimeofday64(ts
));
683 EXPORT_SYMBOL(getnstimeofday64
);
685 ktime_t
ktime_get(void)
687 struct timekeeper
*tk
= &tk_core
.timekeeper
;
692 WARN_ON(timekeeping_suspended
);
695 seq
= read_seqcount_begin(&tk_core
.seq
);
696 base
= tk
->tkr_mono
.base
;
697 nsecs
= timekeeping_get_ns(&tk
->tkr_mono
);
699 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
701 return ktime_add_ns(base
, nsecs
);
703 EXPORT_SYMBOL_GPL(ktime_get
);
705 static ktime_t
*offsets
[TK_OFFS_MAX
] = {
706 [TK_OFFS_REAL
] = &tk_core
.timekeeper
.offs_real
,
707 [TK_OFFS_BOOT
] = &tk_core
.timekeeper
.offs_boot
,
708 [TK_OFFS_TAI
] = &tk_core
.timekeeper
.offs_tai
,
711 ktime_t
ktime_get_with_offset(enum tk_offsets offs
)
713 struct timekeeper
*tk
= &tk_core
.timekeeper
;
715 ktime_t base
, *offset
= offsets
[offs
];
718 WARN_ON(timekeeping_suspended
);
721 seq
= read_seqcount_begin(&tk_core
.seq
);
722 base
= ktime_add(tk
->tkr_mono
.base
, *offset
);
723 nsecs
= timekeeping_get_ns(&tk
->tkr_mono
);
725 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
727 return ktime_add_ns(base
, nsecs
);
730 EXPORT_SYMBOL_GPL(ktime_get_with_offset
);
733 * ktime_mono_to_any() - convert mononotic time to any other time
734 * @tmono: time to convert.
735 * @offs: which offset to use
737 ktime_t
ktime_mono_to_any(ktime_t tmono
, enum tk_offsets offs
)
739 ktime_t
*offset
= offsets
[offs
];
744 seq
= read_seqcount_begin(&tk_core
.seq
);
745 tconv
= ktime_add(tmono
, *offset
);
746 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
750 EXPORT_SYMBOL_GPL(ktime_mono_to_any
);
753 * ktime_get_raw - Returns the raw monotonic time in ktime_t format
755 ktime_t
ktime_get_raw(void)
757 struct timekeeper
*tk
= &tk_core
.timekeeper
;
763 seq
= read_seqcount_begin(&tk_core
.seq
);
764 base
= tk
->tkr_raw
.base
;
765 nsecs
= timekeeping_get_ns(&tk
->tkr_raw
);
767 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
769 return ktime_add_ns(base
, nsecs
);
771 EXPORT_SYMBOL_GPL(ktime_get_raw
);
774 * ktime_get_ts64 - get the monotonic clock in timespec64 format
775 * @ts: pointer to timespec variable
777 * The function calculates the monotonic clock from the realtime
778 * clock and the wall_to_monotonic offset and stores the result
779 * in normalized timespec64 format in the variable pointed to by @ts.
781 void ktime_get_ts64(struct timespec64
*ts
)
783 struct timekeeper
*tk
= &tk_core
.timekeeper
;
784 struct timespec64 tomono
;
788 WARN_ON(timekeeping_suspended
);
791 seq
= read_seqcount_begin(&tk_core
.seq
);
792 ts
->tv_sec
= tk
->xtime_sec
;
793 nsec
= timekeeping_get_ns(&tk
->tkr_mono
);
794 tomono
= tk
->wall_to_monotonic
;
796 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
798 ts
->tv_sec
+= tomono
.tv_sec
;
800 timespec64_add_ns(ts
, nsec
+ tomono
.tv_nsec
);
802 EXPORT_SYMBOL_GPL(ktime_get_ts64
);
805 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
807 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
808 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
809 * works on both 32 and 64 bit systems. On 32 bit systems the readout
810 * covers ~136 years of uptime which should be enough to prevent
811 * premature wrap arounds.
813 time64_t
ktime_get_seconds(void)
815 struct timekeeper
*tk
= &tk_core
.timekeeper
;
817 WARN_ON(timekeeping_suspended
);
818 return tk
->ktime_sec
;
820 EXPORT_SYMBOL_GPL(ktime_get_seconds
);
823 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
825 * Returns the wall clock seconds since 1970. This replaces the
826 * get_seconds() interface which is not y2038 safe on 32bit systems.
828 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
829 * 32bit systems the access must be protected with the sequence
830 * counter to provide "atomic" access to the 64bit tk->xtime_sec
833 time64_t
ktime_get_real_seconds(void)
835 struct timekeeper
*tk
= &tk_core
.timekeeper
;
839 if (IS_ENABLED(CONFIG_64BIT
))
840 return tk
->xtime_sec
;
843 seq
= read_seqcount_begin(&tk_core
.seq
);
844 seconds
= tk
->xtime_sec
;
846 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
850 EXPORT_SYMBOL_GPL(ktime_get_real_seconds
);
852 #ifdef CONFIG_NTP_PPS
855 * getnstime_raw_and_real - get day and raw monotonic time in timespec format
856 * @ts_raw: pointer to the timespec to be set to raw monotonic time
857 * @ts_real: pointer to the timespec to be set to the time of day
859 * This function reads both the time of day and raw monotonic time at the
860 * same time atomically and stores the resulting timestamps in timespec
863 void getnstime_raw_and_real(struct timespec
*ts_raw
, struct timespec
*ts_real
)
865 struct timekeeper
*tk
= &tk_core
.timekeeper
;
867 s64 nsecs_raw
, nsecs_real
;
869 WARN_ON_ONCE(timekeeping_suspended
);
872 seq
= read_seqcount_begin(&tk_core
.seq
);
874 *ts_raw
= timespec64_to_timespec(tk
->raw_time
);
875 ts_real
->tv_sec
= tk
->xtime_sec
;
876 ts_real
->tv_nsec
= 0;
878 nsecs_raw
= timekeeping_get_ns(&tk
->tkr_raw
);
879 nsecs_real
= timekeeping_get_ns(&tk
->tkr_mono
);
881 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
883 timespec_add_ns(ts_raw
, nsecs_raw
);
884 timespec_add_ns(ts_real
, nsecs_real
);
886 EXPORT_SYMBOL(getnstime_raw_and_real
);
888 #endif /* CONFIG_NTP_PPS */
891 * do_gettimeofday - Returns the time of day in a timeval
892 * @tv: pointer to the timeval to be set
894 * NOTE: Users should be converted to using getnstimeofday()
896 void do_gettimeofday(struct timeval
*tv
)
898 struct timespec64 now
;
900 getnstimeofday64(&now
);
901 tv
->tv_sec
= now
.tv_sec
;
902 tv
->tv_usec
= now
.tv_nsec
/1000;
904 EXPORT_SYMBOL(do_gettimeofday
);
907 * do_settimeofday64 - Sets the time of day.
908 * @ts: pointer to the timespec64 variable containing the new time
910 * Sets the time of day to the new time and update NTP and notify hrtimers
912 int do_settimeofday64(const struct timespec64
*ts
)
914 struct timekeeper
*tk
= &tk_core
.timekeeper
;
915 struct timespec64 ts_delta
, xt
;
918 if (!timespec64_valid_strict(ts
))
921 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
922 write_seqcount_begin(&tk_core
.seq
);
924 timekeeping_forward_now(tk
);
927 ts_delta
.tv_sec
= ts
->tv_sec
- xt
.tv_sec
;
928 ts_delta
.tv_nsec
= ts
->tv_nsec
- xt
.tv_nsec
;
930 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, ts_delta
));
932 tk_set_xtime(tk
, ts
);
934 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
936 write_seqcount_end(&tk_core
.seq
);
937 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
939 /* signal hrtimers about time change */
944 EXPORT_SYMBOL(do_settimeofday64
);
947 * timekeeping_inject_offset - Adds or subtracts from the current time.
948 * @tv: pointer to the timespec variable containing the offset
950 * Adds or subtracts an offset value from the current time.
952 int timekeeping_inject_offset(struct timespec
*ts
)
954 struct timekeeper
*tk
= &tk_core
.timekeeper
;
956 struct timespec64 ts64
, tmp
;
959 if ((unsigned long)ts
->tv_nsec
>= NSEC_PER_SEC
)
962 ts64
= timespec_to_timespec64(*ts
);
964 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
965 write_seqcount_begin(&tk_core
.seq
);
967 timekeeping_forward_now(tk
);
969 /* Make sure the proposed value is valid */
970 tmp
= timespec64_add(tk_xtime(tk
), ts64
);
971 if (!timespec64_valid_strict(&tmp
)) {
976 tk_xtime_add(tk
, &ts64
);
977 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, ts64
));
979 error
: /* even if we error out, we forwarded the time, so call update */
980 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
982 write_seqcount_end(&tk_core
.seq
);
983 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
985 /* signal hrtimers about time change */
990 EXPORT_SYMBOL(timekeeping_inject_offset
);
994 * timekeeping_get_tai_offset - Returns current TAI offset from UTC
997 s32
timekeeping_get_tai_offset(void)
999 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1004 seq
= read_seqcount_begin(&tk_core
.seq
);
1005 ret
= tk
->tai_offset
;
1006 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1012 * __timekeeping_set_tai_offset - Lock free worker function
1015 static void __timekeeping_set_tai_offset(struct timekeeper
*tk
, s32 tai_offset
)
1017 tk
->tai_offset
= tai_offset
;
1018 tk
->offs_tai
= ktime_add(tk
->offs_real
, ktime_set(tai_offset
, 0));
1022 * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
1025 void timekeeping_set_tai_offset(s32 tai_offset
)
1027 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1028 unsigned long flags
;
1030 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1031 write_seqcount_begin(&tk_core
.seq
);
1032 __timekeeping_set_tai_offset(tk
, tai_offset
);
1033 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
1034 write_seqcount_end(&tk_core
.seq
);
1035 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1040 * change_clocksource - Swaps clocksources if a new one is available
1042 * Accumulates current time interval and initializes new clocksource
1044 static int change_clocksource(void *data
)
1046 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1047 struct clocksource
*new, *old
;
1048 unsigned long flags
;
1050 new = (struct clocksource
*) data
;
1052 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1053 write_seqcount_begin(&tk_core
.seq
);
1055 timekeeping_forward_now(tk
);
1057 * If the cs is in module, get a module reference. Succeeds
1058 * for built-in code (owner == NULL) as well.
1060 if (try_module_get(new->owner
)) {
1061 if (!new->enable
|| new->enable(new) == 0) {
1062 old
= tk
->tkr_mono
.clock
;
1063 tk_setup_internals(tk
, new);
1066 module_put(old
->owner
);
1068 module_put(new->owner
);
1071 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
1073 write_seqcount_end(&tk_core
.seq
);
1074 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1080 * timekeeping_notify - Install a new clock source
1081 * @clock: pointer to the clock source
1083 * This function is called from clocksource.c after a new, better clock
1084 * source has been registered. The caller holds the clocksource_mutex.
1086 int timekeeping_notify(struct clocksource
*clock
)
1088 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1090 if (tk
->tkr_mono
.clock
== clock
)
1092 stop_machine(change_clocksource
, clock
, NULL
);
1093 tick_clock_notify();
1094 return tk
->tkr_mono
.clock
== clock
? 0 : -1;
1098 * getrawmonotonic64 - Returns the raw monotonic time in a timespec
1099 * @ts: pointer to the timespec64 to be set
1101 * Returns the raw monotonic time (completely un-modified by ntp)
1103 void getrawmonotonic64(struct timespec64
*ts
)
1105 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1106 struct timespec64 ts64
;
1111 seq
= read_seqcount_begin(&tk_core
.seq
);
1112 nsecs
= timekeeping_get_ns(&tk
->tkr_raw
);
1113 ts64
= tk
->raw_time
;
1115 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1117 timespec64_add_ns(&ts64
, nsecs
);
1120 EXPORT_SYMBOL(getrawmonotonic64
);
1124 * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
1126 int timekeeping_valid_for_hres(void)
1128 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1133 seq
= read_seqcount_begin(&tk_core
.seq
);
1135 ret
= tk
->tkr_mono
.clock
->flags
& CLOCK_SOURCE_VALID_FOR_HRES
;
1137 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1143 * timekeeping_max_deferment - Returns max time the clocksource can be deferred
1145 u64
timekeeping_max_deferment(void)
1147 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1152 seq
= read_seqcount_begin(&tk_core
.seq
);
1154 ret
= tk
->tkr_mono
.clock
->max_idle_ns
;
1156 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1162 * read_persistent_clock - Return time from the persistent clock.
1164 * Weak dummy function for arches that do not yet support it.
1165 * Reads the time from the battery backed persistent clock.
1166 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1168 * XXX - Do be sure to remove it once all arches implement it.
1170 void __weak
read_persistent_clock(struct timespec
*ts
)
1177 * read_boot_clock - Return time of the system start.
1179 * Weak dummy function for arches that do not yet support it.
1180 * Function to read the exact time the system has been started.
1181 * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
1183 * XXX - Do be sure to remove it once all arches implement it.
1185 void __weak
read_boot_clock(struct timespec
*ts
)
1192 * timekeeping_init - Initializes the clocksource and common timekeeping values
1194 void __init
timekeeping_init(void)
1196 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1197 struct clocksource
*clock
;
1198 unsigned long flags
;
1199 struct timespec64 now
, boot
, tmp
;
1202 read_persistent_clock(&ts
);
1203 now
= timespec_to_timespec64(ts
);
1204 if (!timespec64_valid_strict(&now
)) {
1205 pr_warn("WARNING: Persistent clock returned invalid value!\n"
1206 " Check your CMOS/BIOS settings.\n");
1209 } else if (now
.tv_sec
|| now
.tv_nsec
)
1210 persistent_clock_exist
= true;
1212 read_boot_clock(&ts
);
1213 boot
= timespec_to_timespec64(ts
);
1214 if (!timespec64_valid_strict(&boot
)) {
1215 pr_warn("WARNING: Boot clock returned invalid value!\n"
1216 " Check your CMOS/BIOS settings.\n");
1221 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1222 write_seqcount_begin(&tk_core
.seq
);
1225 clock
= clocksource_default_clock();
1227 clock
->enable(clock
);
1228 tk_setup_internals(tk
, clock
);
1230 tk_set_xtime(tk
, &now
);
1231 tk
->raw_time
.tv_sec
= 0;
1232 tk
->raw_time
.tv_nsec
= 0;
1233 if (boot
.tv_sec
== 0 && boot
.tv_nsec
== 0)
1234 boot
= tk_xtime(tk
);
1236 set_normalized_timespec64(&tmp
, -boot
.tv_sec
, -boot
.tv_nsec
);
1237 tk_set_wall_to_mono(tk
, tmp
);
1239 timekeeping_update(tk
, TK_MIRROR
);
1241 write_seqcount_end(&tk_core
.seq
);
1242 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1245 /* time in seconds when suspend began */
1246 static struct timespec64 timekeeping_suspend_time
;
1249 * __timekeeping_inject_sleeptime - Internal function to add sleep interval
1250 * @delta: pointer to a timespec delta value
1252 * Takes a timespec offset measuring a suspend interval and properly
1253 * adds the sleep offset to the timekeeping variables.
1255 static void __timekeeping_inject_sleeptime(struct timekeeper
*tk
,
1256 struct timespec64
*delta
)
1258 if (!timespec64_valid_strict(delta
)) {
1259 printk_deferred(KERN_WARNING
1260 "__timekeeping_inject_sleeptime: Invalid "
1261 "sleep delta value!\n");
1264 tk_xtime_add(tk
, delta
);
1265 tk_set_wall_to_mono(tk
, timespec64_sub(tk
->wall_to_monotonic
, *delta
));
1266 tk_update_sleep_time(tk
, timespec64_to_ktime(*delta
));
1267 tk_debug_account_sleep_time(delta
);
1271 * timekeeping_inject_sleeptime64 - Adds suspend interval to timeekeeping values
1272 * @delta: pointer to a timespec64 delta value
1274 * This hook is for architectures that cannot support read_persistent_clock
1275 * because their RTC/persistent clock is only accessible when irqs are enabled.
1277 * This function should only be called by rtc_resume(), and allows
1278 * a suspend offset to be injected into the timekeeping values.
1280 void timekeeping_inject_sleeptime64(struct timespec64
*delta
)
1282 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1283 unsigned long flags
;
1286 * Make sure we don't set the clock twice, as timekeeping_resume()
1289 if (has_persistent_clock())
1292 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1293 write_seqcount_begin(&tk_core
.seq
);
1295 timekeeping_forward_now(tk
);
1297 __timekeeping_inject_sleeptime(tk
, delta
);
1299 timekeeping_update(tk
, TK_CLEAR_NTP
| TK_MIRROR
| TK_CLOCK_WAS_SET
);
1301 write_seqcount_end(&tk_core
.seq
);
1302 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1304 /* signal hrtimers about time change */
1309 * timekeeping_resume - Resumes the generic timekeeping subsystem.
1311 * This is for the generic clocksource timekeeping.
1312 * xtime/wall_to_monotonic/jiffies/etc are
1313 * still managed by arch specific suspend/resume code.
1315 void timekeeping_resume(void)
1317 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1318 struct clocksource
*clock
= tk
->tkr_mono
.clock
;
1319 unsigned long flags
;
1320 struct timespec64 ts_new
, ts_delta
;
1321 struct timespec tmp
;
1322 cycle_t cycle_now
, cycle_delta
;
1323 bool suspendtime_found
= false;
1325 read_persistent_clock(&tmp
);
1326 ts_new
= timespec_to_timespec64(tmp
);
1328 clockevents_resume();
1329 clocksource_resume();
1331 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1332 write_seqcount_begin(&tk_core
.seq
);
1335 * After system resumes, we need to calculate the suspended time and
1336 * compensate it for the OS time. There are 3 sources that could be
1337 * used: Nonstop clocksource during suspend, persistent clock and rtc
1340 * One specific platform may have 1 or 2 or all of them, and the
1341 * preference will be:
1342 * suspend-nonstop clocksource -> persistent clock -> rtc
1343 * The less preferred source will only be tried if there is no better
1344 * usable source. The rtc part is handled separately in rtc core code.
1346 cycle_now
= tk
->tkr_mono
.read(clock
);
1347 if ((clock
->flags
& CLOCK_SOURCE_SUSPEND_NONSTOP
) &&
1348 cycle_now
> tk
->tkr_mono
.cycle_last
) {
1349 u64 num
, max
= ULLONG_MAX
;
1350 u32 mult
= clock
->mult
;
1351 u32 shift
= clock
->shift
;
1354 cycle_delta
= clocksource_delta(cycle_now
, tk
->tkr_mono
.cycle_last
,
1358 * "cycle_delta * mutl" may cause 64 bits overflow, if the
1359 * suspended time is too long. In that case we need do the
1360 * 64 bits math carefully
1363 if (cycle_delta
> max
) {
1364 num
= div64_u64(cycle_delta
, max
);
1365 nsec
= (((u64
) max
* mult
) >> shift
) * num
;
1366 cycle_delta
-= num
* max
;
1368 nsec
+= ((u64
) cycle_delta
* mult
) >> shift
;
1370 ts_delta
= ns_to_timespec64(nsec
);
1371 suspendtime_found
= true;
1372 } else if (timespec64_compare(&ts_new
, &timekeeping_suspend_time
) > 0) {
1373 ts_delta
= timespec64_sub(ts_new
, timekeeping_suspend_time
);
1374 suspendtime_found
= true;
1377 if (suspendtime_found
)
1378 __timekeeping_inject_sleeptime(tk
, &ts_delta
);
1380 /* Re-base the last cycle value */
1381 tk
->tkr_mono
.cycle_last
= cycle_now
;
1382 tk
->tkr_raw
.cycle_last
= cycle_now
;
1385 timekeeping_suspended
= 0;
1386 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
1387 write_seqcount_end(&tk_core
.seq
);
1388 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1390 touch_softlockup_watchdog();
1396 int timekeeping_suspend(void)
1398 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1399 unsigned long flags
;
1400 struct timespec64 delta
, delta_delta
;
1401 static struct timespec64 old_delta
;
1402 struct timespec tmp
;
1404 read_persistent_clock(&tmp
);
1405 timekeeping_suspend_time
= timespec_to_timespec64(tmp
);
1408 * On some systems the persistent_clock can not be detected at
1409 * timekeeping_init by its return value, so if we see a valid
1410 * value returned, update the persistent_clock_exists flag.
1412 if (timekeeping_suspend_time
.tv_sec
|| timekeeping_suspend_time
.tv_nsec
)
1413 persistent_clock_exist
= true;
1415 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1416 write_seqcount_begin(&tk_core
.seq
);
1417 timekeeping_forward_now(tk
);
1418 timekeeping_suspended
= 1;
1421 * To avoid drift caused by repeated suspend/resumes,
1422 * which each can add ~1 second drift error,
1423 * try to compensate so the difference in system time
1424 * and persistent_clock time stays close to constant.
1426 delta
= timespec64_sub(tk_xtime(tk
), timekeeping_suspend_time
);
1427 delta_delta
= timespec64_sub(delta
, old_delta
);
1428 if (abs(delta_delta
.tv_sec
) >= 2) {
1430 * if delta_delta is too large, assume time correction
1431 * has occured and set old_delta to the current delta.
1435 /* Otherwise try to adjust old_system to compensate */
1436 timekeeping_suspend_time
=
1437 timespec64_add(timekeeping_suspend_time
, delta_delta
);
1440 timekeeping_update(tk
, TK_MIRROR
);
1441 halt_fast_timekeeper(tk
);
1442 write_seqcount_end(&tk_core
.seq
);
1443 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1446 clocksource_suspend();
1447 clockevents_suspend();
1452 /* sysfs resume/suspend bits for timekeeping */
1453 static struct syscore_ops timekeeping_syscore_ops
= {
1454 .resume
= timekeeping_resume
,
1455 .suspend
= timekeeping_suspend
,
1458 static int __init
timekeeping_init_ops(void)
1460 register_syscore_ops(&timekeeping_syscore_ops
);
1463 device_initcall(timekeeping_init_ops
);
1466 * Apply a multiplier adjustment to the timekeeper
1468 static __always_inline
void timekeeping_apply_adjustment(struct timekeeper
*tk
,
1473 s64 interval
= tk
->cycle_interval
;
1477 mult_adj
= -mult_adj
;
1478 interval
= -interval
;
1481 mult_adj
<<= adj_scale
;
1482 interval
<<= adj_scale
;
1483 offset
<<= adj_scale
;
1486 * So the following can be confusing.
1488 * To keep things simple, lets assume mult_adj == 1 for now.
1490 * When mult_adj != 1, remember that the interval and offset values
1491 * have been appropriately scaled so the math is the same.
1493 * The basic idea here is that we're increasing the multiplier
1494 * by one, this causes the xtime_interval to be incremented by
1495 * one cycle_interval. This is because:
1496 * xtime_interval = cycle_interval * mult
1497 * So if mult is being incremented by one:
1498 * xtime_interval = cycle_interval * (mult + 1)
1500 * xtime_interval = (cycle_interval * mult) + cycle_interval
1501 * Which can be shortened to:
1502 * xtime_interval += cycle_interval
1504 * So offset stores the non-accumulated cycles. Thus the current
1505 * time (in shifted nanoseconds) is:
1506 * now = (offset * adj) + xtime_nsec
1507 * Now, even though we're adjusting the clock frequency, we have
1508 * to keep time consistent. In other words, we can't jump back
1509 * in time, and we also want to avoid jumping forward in time.
1511 * So given the same offset value, we need the time to be the same
1512 * both before and after the freq adjustment.
1513 * now = (offset * adj_1) + xtime_nsec_1
1514 * now = (offset * adj_2) + xtime_nsec_2
1516 * (offset * adj_1) + xtime_nsec_1 =
1517 * (offset * adj_2) + xtime_nsec_2
1521 * (offset * adj_1) + xtime_nsec_1 =
1522 * (offset * (adj_1+1)) + xtime_nsec_2
1523 * (offset * adj_1) + xtime_nsec_1 =
1524 * (offset * adj_1) + offset + xtime_nsec_2
1525 * Canceling the sides:
1526 * xtime_nsec_1 = offset + xtime_nsec_2
1528 * xtime_nsec_2 = xtime_nsec_1 - offset
1529 * Which simplfies to:
1530 * xtime_nsec -= offset
1532 * XXX - TODO: Doc ntp_error calculation.
1534 if ((mult_adj
> 0) && (tk
->tkr_mono
.mult
+ mult_adj
< mult_adj
)) {
1535 /* NTP adjustment caused clocksource mult overflow */
1540 tk
->tkr_mono
.mult
+= mult_adj
;
1541 tk
->xtime_interval
+= interval
;
1542 tk
->tkr_mono
.xtime_nsec
-= offset
;
1543 tk
->ntp_error
-= (interval
- offset
) << tk
->ntp_error_shift
;
1547 * Calculate the multiplier adjustment needed to match the frequency
1550 static __always_inline
void timekeeping_freqadjust(struct timekeeper
*tk
,
1553 s64 interval
= tk
->cycle_interval
;
1554 s64 xinterval
= tk
->xtime_interval
;
1559 /* Remove any current error adj from freq calculation */
1560 if (tk
->ntp_err_mult
)
1561 xinterval
-= tk
->cycle_interval
;
1563 tk
->ntp_tick
= ntp_tick_length();
1565 /* Calculate current error per tick */
1566 tick_error
= ntp_tick_length() >> tk
->ntp_error_shift
;
1567 tick_error
-= (xinterval
+ tk
->xtime_remainder
);
1569 /* Don't worry about correcting it if its small */
1570 if (likely((tick_error
>= 0) && (tick_error
<= interval
)))
1573 /* preserve the direction of correction */
1574 negative
= (tick_error
< 0);
1576 /* Sort out the magnitude of the correction */
1577 tick_error
= abs(tick_error
);
1578 for (adj
= 0; tick_error
> interval
; adj
++)
1581 /* scale the corrections */
1582 timekeeping_apply_adjustment(tk
, offset
, negative
, adj
);
1586 * Adjust the timekeeper's multiplier to the correct frequency
1587 * and also to reduce the accumulated error value.
1589 static void timekeeping_adjust(struct timekeeper
*tk
, s64 offset
)
1591 /* Correct for the current frequency error */
1592 timekeeping_freqadjust(tk
, offset
);
1594 /* Next make a small adjustment to fix any cumulative error */
1595 if (!tk
->ntp_err_mult
&& (tk
->ntp_error
> 0)) {
1596 tk
->ntp_err_mult
= 1;
1597 timekeeping_apply_adjustment(tk
, offset
, 0, 0);
1598 } else if (tk
->ntp_err_mult
&& (tk
->ntp_error
<= 0)) {
1599 /* Undo any existing error adjustment */
1600 timekeeping_apply_adjustment(tk
, offset
, 1, 0);
1601 tk
->ntp_err_mult
= 0;
1604 if (unlikely(tk
->tkr_mono
.clock
->maxadj
&&
1605 (abs(tk
->tkr_mono
.mult
- tk
->tkr_mono
.clock
->mult
)
1606 > tk
->tkr_mono
.clock
->maxadj
))) {
1607 printk_once(KERN_WARNING
1608 "Adjusting %s more than 11%% (%ld vs %ld)\n",
1609 tk
->tkr_mono
.clock
->name
, (long)tk
->tkr_mono
.mult
,
1610 (long)tk
->tkr_mono
.clock
->mult
+ tk
->tkr_mono
.clock
->maxadj
);
1614 * It may be possible that when we entered this function, xtime_nsec
1615 * was very small. Further, if we're slightly speeding the clocksource
1616 * in the code above, its possible the required corrective factor to
1617 * xtime_nsec could cause it to underflow.
1619 * Now, since we already accumulated the second, cannot simply roll
1620 * the accumulated second back, since the NTP subsystem has been
1621 * notified via second_overflow. So instead we push xtime_nsec forward
1622 * by the amount we underflowed, and add that amount into the error.
1624 * We'll correct this error next time through this function, when
1625 * xtime_nsec is not as small.
1627 if (unlikely((s64
)tk
->tkr_mono
.xtime_nsec
< 0)) {
1628 s64 neg
= -(s64
)tk
->tkr_mono
.xtime_nsec
;
1629 tk
->tkr_mono
.xtime_nsec
= 0;
1630 tk
->ntp_error
+= neg
<< tk
->ntp_error_shift
;
1635 * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1637 * Helper function that accumulates a the nsecs greater then a second
1638 * from the xtime_nsec field to the xtime_secs field.
1639 * It also calls into the NTP code to handle leapsecond processing.
1642 static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper
*tk
)
1644 u64 nsecps
= (u64
)NSEC_PER_SEC
<< tk
->tkr_mono
.shift
;
1645 unsigned int clock_set
= 0;
1647 while (tk
->tkr_mono
.xtime_nsec
>= nsecps
) {
1650 tk
->tkr_mono
.xtime_nsec
-= nsecps
;
1653 /* Figure out if its a leap sec and apply if needed */
1654 leap
= second_overflow(tk
->xtime_sec
);
1655 if (unlikely(leap
)) {
1656 struct timespec64 ts
;
1658 tk
->xtime_sec
+= leap
;
1662 tk_set_wall_to_mono(tk
,
1663 timespec64_sub(tk
->wall_to_monotonic
, ts
));
1665 __timekeeping_set_tai_offset(tk
, tk
->tai_offset
- leap
);
1667 clock_set
= TK_CLOCK_WAS_SET
;
1674 * logarithmic_accumulation - shifted accumulation of cycles
1676 * This functions accumulates a shifted interval of cycles into
1677 * into a shifted interval nanoseconds. Allows for O(log) accumulation
1680 * Returns the unconsumed cycles.
1682 static cycle_t
logarithmic_accumulation(struct timekeeper
*tk
, cycle_t offset
,
1684 unsigned int *clock_set
)
1686 cycle_t interval
= tk
->cycle_interval
<< shift
;
1689 /* If the offset is smaller then a shifted interval, do nothing */
1690 if (offset
< interval
)
1693 /* Accumulate one shifted interval */
1695 tk
->tkr_mono
.cycle_last
+= interval
;
1696 tk
->tkr_raw
.cycle_last
+= interval
;
1698 tk
->tkr_mono
.xtime_nsec
+= tk
->xtime_interval
<< shift
;
1699 *clock_set
|= accumulate_nsecs_to_secs(tk
);
1701 /* Accumulate raw time */
1702 raw_nsecs
= (u64
)tk
->raw_interval
<< shift
;
1703 raw_nsecs
+= tk
->raw_time
.tv_nsec
;
1704 if (raw_nsecs
>= NSEC_PER_SEC
) {
1705 u64 raw_secs
= raw_nsecs
;
1706 raw_nsecs
= do_div(raw_secs
, NSEC_PER_SEC
);
1707 tk
->raw_time
.tv_sec
+= raw_secs
;
1709 tk
->raw_time
.tv_nsec
= raw_nsecs
;
1711 /* Accumulate error between NTP and clock interval */
1712 tk
->ntp_error
+= tk
->ntp_tick
<< shift
;
1713 tk
->ntp_error
-= (tk
->xtime_interval
+ tk
->xtime_remainder
) <<
1714 (tk
->ntp_error_shift
+ shift
);
1720 * update_wall_time - Uses the current clocksource to increment the wall time
1723 void update_wall_time(void)
1725 struct timekeeper
*real_tk
= &tk_core
.timekeeper
;
1726 struct timekeeper
*tk
= &shadow_timekeeper
;
1728 int shift
= 0, maxshift
;
1729 unsigned int clock_set
= 0;
1730 unsigned long flags
;
1732 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1734 /* Make sure we're fully resumed: */
1735 if (unlikely(timekeeping_suspended
))
1738 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1739 offset
= real_tk
->cycle_interval
;
1741 offset
= clocksource_delta(tk
->tkr_mono
.read(tk
->tkr_mono
.clock
),
1742 tk
->tkr_mono
.cycle_last
, tk
->tkr_mono
.mask
);
1745 /* Check if there's really nothing to do */
1746 if (offset
< real_tk
->cycle_interval
)
1749 /* Do some additional sanity checking */
1750 timekeeping_check_update(real_tk
, offset
);
1753 * With NO_HZ we may have to accumulate many cycle_intervals
1754 * (think "ticks") worth of time at once. To do this efficiently,
1755 * we calculate the largest doubling multiple of cycle_intervals
1756 * that is smaller than the offset. We then accumulate that
1757 * chunk in one go, and then try to consume the next smaller
1760 shift
= ilog2(offset
) - ilog2(tk
->cycle_interval
);
1761 shift
= max(0, shift
);
1762 /* Bound shift to one less than what overflows tick_length */
1763 maxshift
= (64 - (ilog2(ntp_tick_length())+1)) - 1;
1764 shift
= min(shift
, maxshift
);
1765 while (offset
>= tk
->cycle_interval
) {
1766 offset
= logarithmic_accumulation(tk
, offset
, shift
,
1768 if (offset
< tk
->cycle_interval
<<shift
)
1772 /* correct the clock when NTP error is too big */
1773 timekeeping_adjust(tk
, offset
);
1776 * XXX This can be killed once everyone converts
1777 * to the new update_vsyscall.
1779 old_vsyscall_fixup(tk
);
1782 * Finally, make sure that after the rounding
1783 * xtime_nsec isn't larger than NSEC_PER_SEC
1785 clock_set
|= accumulate_nsecs_to_secs(tk
);
1787 write_seqcount_begin(&tk_core
.seq
);
1789 * Update the real timekeeper.
1791 * We could avoid this memcpy by switching pointers, but that
1792 * requires changes to all other timekeeper usage sites as
1793 * well, i.e. move the timekeeper pointer getter into the
1794 * spinlocked/seqcount protected sections. And we trade this
1795 * memcpy under the tk_core.seq against one before we start
1798 memcpy(real_tk
, tk
, sizeof(*tk
));
1799 timekeeping_update(real_tk
, clock_set
);
1800 write_seqcount_end(&tk_core
.seq
);
1802 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1804 /* Have to call _delayed version, since in irq context*/
1805 clock_was_set_delayed();
1809 * getboottime64 - Return the real time of system boot.
1810 * @ts: pointer to the timespec64 to be set
1812 * Returns the wall-time of boot in a timespec64.
1814 * This is based on the wall_to_monotonic offset and the total suspend
1815 * time. Calls to settimeofday will affect the value returned (which
1816 * basically means that however wrong your real time clock is at boot time,
1817 * you get the right time here).
1819 void getboottime64(struct timespec64
*ts
)
1821 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1822 ktime_t t
= ktime_sub(tk
->offs_real
, tk
->offs_boot
);
1824 *ts
= ktime_to_timespec64(t
);
1826 EXPORT_SYMBOL_GPL(getboottime64
);
1828 unsigned long get_seconds(void)
1830 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1832 return tk
->xtime_sec
;
1834 EXPORT_SYMBOL(get_seconds
);
1836 struct timespec
__current_kernel_time(void)
1838 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1840 return timespec64_to_timespec(tk_xtime(tk
));
1843 struct timespec
current_kernel_time(void)
1845 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1846 struct timespec64 now
;
1850 seq
= read_seqcount_begin(&tk_core
.seq
);
1853 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1855 return timespec64_to_timespec(now
);
1857 EXPORT_SYMBOL(current_kernel_time
);
1859 struct timespec64
get_monotonic_coarse64(void)
1861 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1862 struct timespec64 now
, mono
;
1866 seq
= read_seqcount_begin(&tk_core
.seq
);
1869 mono
= tk
->wall_to_monotonic
;
1870 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1872 set_normalized_timespec64(&now
, now
.tv_sec
+ mono
.tv_sec
,
1873 now
.tv_nsec
+ mono
.tv_nsec
);
1879 * Must hold jiffies_lock
1881 void do_timer(unsigned long ticks
)
1883 jiffies_64
+= ticks
;
1884 calc_global_load(ticks
);
1888 * ktime_get_update_offsets_tick - hrtimer helper
1889 * @offs_real: pointer to storage for monotonic -> realtime offset
1890 * @offs_boot: pointer to storage for monotonic -> boottime offset
1891 * @offs_tai: pointer to storage for monotonic -> clock tai offset
1893 * Returns monotonic time at last tick and various offsets
1895 ktime_t
ktime_get_update_offsets_tick(ktime_t
*offs_real
, ktime_t
*offs_boot
,
1898 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1904 seq
= read_seqcount_begin(&tk_core
.seq
);
1906 base
= tk
->tkr_mono
.base
;
1907 nsecs
= tk
->tkr_mono
.xtime_nsec
>> tk
->tkr_mono
.shift
;
1909 *offs_real
= tk
->offs_real
;
1910 *offs_boot
= tk
->offs_boot
;
1911 *offs_tai
= tk
->offs_tai
;
1912 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1914 return ktime_add_ns(base
, nsecs
);
1917 #ifdef CONFIG_HIGH_RES_TIMERS
1919 * ktime_get_update_offsets_now - hrtimer helper
1920 * @offs_real: pointer to storage for monotonic -> realtime offset
1921 * @offs_boot: pointer to storage for monotonic -> boottime offset
1922 * @offs_tai: pointer to storage for monotonic -> clock tai offset
1924 * Returns current monotonic time and updates the offsets
1925 * Called from hrtimer_interrupt() or retrigger_next_event()
1927 ktime_t
ktime_get_update_offsets_now(ktime_t
*offs_real
, ktime_t
*offs_boot
,
1930 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1936 seq
= read_seqcount_begin(&tk_core
.seq
);
1938 base
= tk
->tkr_mono
.base
;
1939 nsecs
= timekeeping_get_ns(&tk
->tkr_mono
);
1941 *offs_real
= tk
->offs_real
;
1942 *offs_boot
= tk
->offs_boot
;
1943 *offs_tai
= tk
->offs_tai
;
1944 } while (read_seqcount_retry(&tk_core
.seq
, seq
));
1946 return ktime_add_ns(base
, nsecs
);
1951 * do_adjtimex() - Accessor function to NTP __do_adjtimex function
1953 int do_adjtimex(struct timex
*txc
)
1955 struct timekeeper
*tk
= &tk_core
.timekeeper
;
1956 unsigned long flags
;
1957 struct timespec64 ts
;
1961 /* Validate the data before disabling interrupts */
1962 ret
= ntp_validate_timex(txc
);
1966 if (txc
->modes
& ADJ_SETOFFSET
) {
1967 struct timespec delta
;
1968 delta
.tv_sec
= txc
->time
.tv_sec
;
1969 delta
.tv_nsec
= txc
->time
.tv_usec
;
1970 if (!(txc
->modes
& ADJ_NANO
))
1971 delta
.tv_nsec
*= 1000;
1972 ret
= timekeeping_inject_offset(&delta
);
1977 getnstimeofday64(&ts
);
1979 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
1980 write_seqcount_begin(&tk_core
.seq
);
1982 orig_tai
= tai
= tk
->tai_offset
;
1983 ret
= __do_adjtimex(txc
, &ts
, &tai
);
1985 if (tai
!= orig_tai
) {
1986 __timekeeping_set_tai_offset(tk
, tai
);
1987 timekeeping_update(tk
, TK_MIRROR
| TK_CLOCK_WAS_SET
);
1989 write_seqcount_end(&tk_core
.seq
);
1990 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
1992 if (tai
!= orig_tai
)
1995 ntp_notify_cmos_timer();
2000 #ifdef CONFIG_NTP_PPS
2002 * hardpps() - Accessor function to NTP __hardpps function
2004 void hardpps(const struct timespec
*phase_ts
, const struct timespec
*raw_ts
)
2006 unsigned long flags
;
2008 raw_spin_lock_irqsave(&timekeeper_lock
, flags
);
2009 write_seqcount_begin(&tk_core
.seq
);
2011 __hardpps(phase_ts
, raw_ts
);
2013 write_seqcount_end(&tk_core
.seq
);
2014 raw_spin_unlock_irqrestore(&timekeeper_lock
, flags
);
2016 EXPORT_SYMBOL(hardpps
);
2020 * xtime_update() - advances the timekeeping infrastructure
2021 * @ticks: number of ticks, that have elapsed since the last call.
2023 * Must be called with interrupts disabled.
2025 void xtime_update(unsigned long ticks
)
2027 write_seqlock(&jiffies_lock
);
2029 write_sequnlock(&jiffies_lock
);