~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/kernel/time/timekeeping.c

Version: ~ [ linux-5.4.2 ] ~ [ linux-5.3.15 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.88 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.158 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.206 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.206 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.78 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /*
  2  *  linux/kernel/time/timekeeping.c
  3  *
  4  *  Kernel timekeeping code and accessor functions
  5  *
  6  *  This code was moved from linux/kernel/timer.c.
  7  *  Please see that file for copyright and history logs.
  8  *
  9  */
 10 
 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>
 16 #include <linux/mm.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 
 26 #include "tick-internal.h"
 27 #include "ntp_internal.h"
 28 #include "timekeeping_internal.h"
 29 
 30 #define TK_CLEAR_NTP            (1 << 0)
 31 #define TK_MIRROR               (1 << 1)
 32 #define TK_CLOCK_WAS_SET        (1 << 2)
 33 
 34 static struct timekeeper timekeeper;
 35 static DEFINE_RAW_SPINLOCK(timekeeper_lock);
 36 static seqcount_t timekeeper_seq;
 37 static struct timekeeper shadow_timekeeper;
 38 
 39 /* flag for if timekeeping is suspended */
 40 int __read_mostly timekeeping_suspended;
 41 
 42 /* Flag for if there is a persistent clock on this platform */
 43 bool __read_mostly persistent_clock_exist = false;
 44 
 45 static inline void tk_normalize_xtime(struct timekeeper *tk)
 46 {
 47         while (tk->xtime_nsec >= ((u64)NSEC_PER_SEC << tk->shift)) {
 48                 tk->xtime_nsec -= (u64)NSEC_PER_SEC << tk->shift;
 49                 tk->xtime_sec++;
 50         }
 51 }
 52 
 53 static void tk_set_xtime(struct timekeeper *tk, const struct timespec *ts)
 54 {
 55         tk->xtime_sec = ts->tv_sec;
 56         tk->xtime_nsec = (u64)ts->tv_nsec << tk->shift;
 57 }
 58 
 59 static void tk_xtime_add(struct timekeeper *tk, const struct timespec *ts)
 60 {
 61         tk->xtime_sec += ts->tv_sec;
 62         tk->xtime_nsec += (u64)ts->tv_nsec << tk->shift;
 63         tk_normalize_xtime(tk);
 64 }
 65 
 66 static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec wtm)
 67 {
 68         struct timespec tmp;
 69 
 70         /*
 71          * Verify consistency of: offset_real = -wall_to_monotonic
 72          * before modifying anything
 73          */
 74         set_normalized_timespec(&tmp, -tk->wall_to_monotonic.tv_sec,
 75                                         -tk->wall_to_monotonic.tv_nsec);
 76         WARN_ON_ONCE(tk->offs_real.tv64 != timespec_to_ktime(tmp).tv64);
 77         tk->wall_to_monotonic = wtm;
 78         set_normalized_timespec(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
 79         tk->offs_real = timespec_to_ktime(tmp);
 80         tk->offs_tai = ktime_sub(tk->offs_real, ktime_set(tk->tai_offset, 0));
 81 }
 82 
 83 static void tk_set_sleep_time(struct timekeeper *tk, struct timespec t)
 84 {
 85         /* Verify consistency before modifying */
 86         WARN_ON_ONCE(tk->offs_boot.tv64 != timespec_to_ktime(tk->total_sleep_time).tv64);
 87 
 88         tk->total_sleep_time    = t;
 89         tk->offs_boot           = timespec_to_ktime(t);
 90 }
 91 
 92 /**
 93  * timekeeper_setup_internals - Set up internals to use clocksource clock.
 94  *
 95  * @clock:              Pointer to clocksource.
 96  *
 97  * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
 98  * pair and interval request.
 99  *
100  * Unless you're the timekeeping code, you should not be using this!
101  */
102 static void tk_setup_internals(struct timekeeper *tk, struct clocksource *clock)
103 {
104         cycle_t interval;
105         u64 tmp, ntpinterval;
106         struct clocksource *old_clock;
107 
108         old_clock = tk->clock;
109         tk->clock = clock;
110         tk->cycle_last = clock->cycle_last = clock->read(clock);
111 
112         /* Do the ns -> cycle conversion first, using original mult */
113         tmp = NTP_INTERVAL_LENGTH;
114         tmp <<= clock->shift;
115         ntpinterval = tmp;
116         tmp += clock->mult/2;
117         do_div(tmp, clock->mult);
118         if (tmp == 0)
119                 tmp = 1;
120 
121         interval = (cycle_t) tmp;
122         tk->cycle_interval = interval;
123 
124         /* Go back from cycles -> shifted ns */
125         tk->xtime_interval = (u64) interval * clock->mult;
126         tk->xtime_remainder = ntpinterval - tk->xtime_interval;
127         tk->raw_interval =
128                 ((u64) interval * clock->mult) >> clock->shift;
129 
130          /* if changing clocks, convert xtime_nsec shift units */
131         if (old_clock) {
132                 int shift_change = clock->shift - old_clock->shift;
133                 if (shift_change < 0)
134                         tk->xtime_nsec >>= -shift_change;
135                 else
136                         tk->xtime_nsec <<= shift_change;
137         }
138         tk->shift = clock->shift;
139 
140         tk->ntp_error = 0;
141         tk->ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
142 
143         /*
144          * The timekeeper keeps its own mult values for the currently
145          * active clocksource. These value will be adjusted via NTP
146          * to counteract clock drifting.
147          */
148         tk->mult = clock->mult;
149 }
150 
151 /* Timekeeper helper functions. */
152 
153 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
154 u32 (*arch_gettimeoffset)(void);
155 
156 u32 get_arch_timeoffset(void)
157 {
158         if (likely(arch_gettimeoffset))
159                 return arch_gettimeoffset();
160         return 0;
161 }
162 #else
163 static inline u32 get_arch_timeoffset(void) { return 0; }
164 #endif
165 
166 static inline s64 timekeeping_get_ns(struct timekeeper *tk)
167 {
168         cycle_t cycle_now, cycle_delta;
169         struct clocksource *clock;
170         s64 nsec;
171 
172         /* read clocksource: */
173         clock = tk->clock;
174         cycle_now = clock->read(clock);
175 
176         /* calculate the delta since the last update_wall_time: */
177         cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
178 
179         nsec = cycle_delta * tk->mult + tk->xtime_nsec;
180         nsec >>= tk->shift;
181 
182         /* If arch requires, add in get_arch_timeoffset() */
183         return nsec + get_arch_timeoffset();
184 }
185 
186 static inline s64 timekeeping_get_ns_raw(struct timekeeper *tk)
187 {
188         cycle_t cycle_now, cycle_delta;
189         struct clocksource *clock;
190         s64 nsec;
191 
192         /* read clocksource: */
193         clock = tk->clock;
194         cycle_now = clock->read(clock);
195 
196         /* calculate the delta since the last update_wall_time: */
197         cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
198 
199         /* convert delta to nanoseconds. */
200         nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
201 
202         /* If arch requires, add in get_arch_timeoffset() */
203         return nsec + get_arch_timeoffset();
204 }
205 
206 static RAW_NOTIFIER_HEAD(pvclock_gtod_chain);
207 
208 static void update_pvclock_gtod(struct timekeeper *tk, bool was_set)
209 {
210         raw_notifier_call_chain(&pvclock_gtod_chain, was_set, tk);
211 }
212 
213 /**
214  * pvclock_gtod_register_notifier - register a pvclock timedata update listener
215  */
216 int pvclock_gtod_register_notifier(struct notifier_block *nb)
217 {
218         struct timekeeper *tk = &timekeeper;
219         unsigned long flags;
220         int ret;
221 
222         raw_spin_lock_irqsave(&timekeeper_lock, flags);
223         ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
224         update_pvclock_gtod(tk, true);
225         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
226 
227         return ret;
228 }
229 EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
230 
231 /**
232  * pvclock_gtod_unregister_notifier - unregister a pvclock
233  * timedata update listener
234  */
235 int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
236 {
237         unsigned long flags;
238         int ret;
239 
240         raw_spin_lock_irqsave(&timekeeper_lock, flags);
241         ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
242         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
243 
244         return ret;
245 }
246 EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
247 
248 /* must hold timekeeper_lock */
249 static void timekeeping_update(struct timekeeper *tk, unsigned int action)
250 {
251         if (action & TK_CLEAR_NTP) {
252                 tk->ntp_error = 0;
253                 ntp_clear();
254         }
255         update_vsyscall(tk);
256         update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
257 
258         if (action & TK_MIRROR)
259                 memcpy(&shadow_timekeeper, &timekeeper, sizeof(timekeeper));
260 }
261 
262 /**
263  * timekeeping_forward_now - update clock to the current time
264  *
265  * Forward the current clock to update its state since the last call to
266  * update_wall_time(). This is useful before significant clock changes,
267  * as it avoids having to deal with this time offset explicitly.
268  */
269 static void timekeeping_forward_now(struct timekeeper *tk)
270 {
271         cycle_t cycle_now, cycle_delta;
272         struct clocksource *clock;
273         s64 nsec;
274 
275         clock = tk->clock;
276         cycle_now = clock->read(clock);
277         cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
278         tk->cycle_last = clock->cycle_last = cycle_now;
279 
280         tk->xtime_nsec += cycle_delta * tk->mult;
281 
282         /* If arch requires, add in get_arch_timeoffset() */
283         tk->xtime_nsec += (u64)get_arch_timeoffset() << tk->shift;
284 
285         tk_normalize_xtime(tk);
286 
287         nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
288         timespec_add_ns(&tk->raw_time, nsec);
289 }
290 
291 /**
292  * __getnstimeofday - Returns the time of day in a timespec.
293  * @ts:         pointer to the timespec to be set
294  *
295  * Updates the time of day in the timespec.
296  * Returns 0 on success, or -ve when suspended (timespec will be undefined).
297  */
298 int __getnstimeofday(struct timespec *ts)
299 {
300         struct timekeeper *tk = &timekeeper;
301         unsigned long seq;
302         s64 nsecs = 0;
303 
304         do {
305                 seq = read_seqcount_begin(&timekeeper_seq);
306 
307                 ts->tv_sec = tk->xtime_sec;
308                 nsecs = timekeeping_get_ns(tk);
309 
310         } while (read_seqcount_retry(&timekeeper_seq, seq));
311 
312         ts->tv_nsec = 0;
313         timespec_add_ns(ts, nsecs);
314 
315         /*
316          * Do not bail out early, in case there were callers still using
317          * the value, even in the face of the WARN_ON.
318          */
319         if (unlikely(timekeeping_suspended))
320                 return -EAGAIN;
321         return 0;
322 }
323 EXPORT_SYMBOL(__getnstimeofday);
324 
325 /**
326  * getnstimeofday - Returns the time of day in a timespec.
327  * @ts:         pointer to the timespec to be set
328  *
329  * Returns the time of day in a timespec (WARN if suspended).
330  */
331 void getnstimeofday(struct timespec *ts)
332 {
333         WARN_ON(__getnstimeofday(ts));
334 }
335 EXPORT_SYMBOL(getnstimeofday);
336 
337 ktime_t ktime_get(void)
338 {
339         struct timekeeper *tk = &timekeeper;
340         unsigned int seq;
341         s64 secs, nsecs;
342 
343         WARN_ON(timekeeping_suspended);
344 
345         do {
346                 seq = read_seqcount_begin(&timekeeper_seq);
347                 secs = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
348                 nsecs = timekeeping_get_ns(tk) + tk->wall_to_monotonic.tv_nsec;
349 
350         } while (read_seqcount_retry(&timekeeper_seq, seq));
351         /*
352          * Use ktime_set/ktime_add_ns to create a proper ktime on
353          * 32-bit architectures without CONFIG_KTIME_SCALAR.
354          */
355         return ktime_add_ns(ktime_set(secs, 0), nsecs);
356 }
357 EXPORT_SYMBOL_GPL(ktime_get);
358 
359 /**
360  * ktime_get_ts - get the monotonic clock in timespec format
361  * @ts:         pointer to timespec variable
362  *
363  * The function calculates the monotonic clock from the realtime
364  * clock and the wall_to_monotonic offset and stores the result
365  * in normalized timespec format in the variable pointed to by @ts.
366  */
367 void ktime_get_ts(struct timespec *ts)
368 {
369         struct timekeeper *tk = &timekeeper;
370         struct timespec tomono;
371         s64 nsec;
372         unsigned int seq;
373 
374         WARN_ON(timekeeping_suspended);
375 
376         do {
377                 seq = read_seqcount_begin(&timekeeper_seq);
378                 ts->tv_sec = tk->xtime_sec;
379                 nsec = timekeeping_get_ns(tk);
380                 tomono = tk->wall_to_monotonic;
381 
382         } while (read_seqcount_retry(&timekeeper_seq, seq));
383 
384         ts->tv_sec += tomono.tv_sec;
385         ts->tv_nsec = 0;
386         timespec_add_ns(ts, nsec + tomono.tv_nsec);
387 }
388 EXPORT_SYMBOL_GPL(ktime_get_ts);
389 
390 
391 /**
392  * timekeeping_clocktai - Returns the TAI time of day in a timespec
393  * @ts:         pointer to the timespec to be set
394  *
395  * Returns the time of day in a timespec.
396  */
397 void timekeeping_clocktai(struct timespec *ts)
398 {
399         struct timekeeper *tk = &timekeeper;
400         unsigned long seq;
401         u64 nsecs;
402 
403         WARN_ON(timekeeping_suspended);
404 
405         do {
406                 seq = read_seqcount_begin(&timekeeper_seq);
407 
408                 ts->tv_sec = tk->xtime_sec + tk->tai_offset;
409                 nsecs = timekeeping_get_ns(tk);
410 
411         } while (read_seqcount_retry(&timekeeper_seq, seq));
412 
413         ts->tv_nsec = 0;
414         timespec_add_ns(ts, nsecs);
415 
416 }
417 EXPORT_SYMBOL(timekeeping_clocktai);
418 
419 
420 /**
421  * ktime_get_clocktai - Returns the TAI time of day in a ktime
422  *
423  * Returns the time of day in a ktime.
424  */
425 ktime_t ktime_get_clocktai(void)
426 {
427         struct timespec ts;
428 
429         timekeeping_clocktai(&ts);
430         return timespec_to_ktime(ts);
431 }
432 EXPORT_SYMBOL(ktime_get_clocktai);
433 
434 #ifdef CONFIG_NTP_PPS
435 
436 /**
437  * getnstime_raw_and_real - get day and raw monotonic time in timespec format
438  * @ts_raw:     pointer to the timespec to be set to raw monotonic time
439  * @ts_real:    pointer to the timespec to be set to the time of day
440  *
441  * This function reads both the time of day and raw monotonic time at the
442  * same time atomically and stores the resulting timestamps in timespec
443  * format.
444  */
445 void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
446 {
447         struct timekeeper *tk = &timekeeper;
448         unsigned long seq;
449         s64 nsecs_raw, nsecs_real;
450 
451         WARN_ON_ONCE(timekeeping_suspended);
452 
453         do {
454                 seq = read_seqcount_begin(&timekeeper_seq);
455 
456                 *ts_raw = tk->raw_time;
457                 ts_real->tv_sec = tk->xtime_sec;
458                 ts_real->tv_nsec = 0;
459 
460                 nsecs_raw = timekeeping_get_ns_raw(tk);
461                 nsecs_real = timekeeping_get_ns(tk);
462 
463         } while (read_seqcount_retry(&timekeeper_seq, seq));
464 
465         timespec_add_ns(ts_raw, nsecs_raw);
466         timespec_add_ns(ts_real, nsecs_real);
467 }
468 EXPORT_SYMBOL(getnstime_raw_and_real);
469 
470 #endif /* CONFIG_NTP_PPS */
471 
472 /**
473  * do_gettimeofday - Returns the time of day in a timeval
474  * @tv:         pointer to the timeval to be set
475  *
476  * NOTE: Users should be converted to using getnstimeofday()
477  */
478 void do_gettimeofday(struct timeval *tv)
479 {
480         struct timespec now;
481 
482         getnstimeofday(&now);
483         tv->tv_sec = now.tv_sec;
484         tv->tv_usec = now.tv_nsec/1000;
485 }
486 EXPORT_SYMBOL(do_gettimeofday);
487 
488 /**
489  * do_settimeofday - Sets the time of day
490  * @tv:         pointer to the timespec variable containing the new time
491  *
492  * Sets the time of day to the new time and update NTP and notify hrtimers
493  */
494 int do_settimeofday(const struct timespec *tv)
495 {
496         struct timekeeper *tk = &timekeeper;
497         struct timespec ts_delta, xt;
498         unsigned long flags;
499 
500         if (!timespec_valid_strict(tv))
501                 return -EINVAL;
502 
503         raw_spin_lock_irqsave(&timekeeper_lock, flags);
504         write_seqcount_begin(&timekeeper_seq);
505 
506         timekeeping_forward_now(tk);
507 
508         xt = tk_xtime(tk);
509         ts_delta.tv_sec = tv->tv_sec - xt.tv_sec;
510         ts_delta.tv_nsec = tv->tv_nsec - xt.tv_nsec;
511 
512         tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, ts_delta));
513 
514         tk_set_xtime(tk, tv);
515 
516         timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
517 
518         write_seqcount_end(&timekeeper_seq);
519         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
520 
521         /* signal hrtimers about time change */
522         clock_was_set();
523 
524         return 0;
525 }
526 EXPORT_SYMBOL(do_settimeofday);
527 
528 /**
529  * timekeeping_inject_offset - Adds or subtracts from the current time.
530  * @tv:         pointer to the timespec variable containing the offset
531  *
532  * Adds or subtracts an offset value from the current time.
533  */
534 int timekeeping_inject_offset(struct timespec *ts)
535 {
536         struct timekeeper *tk = &timekeeper;
537         unsigned long flags;
538         struct timespec tmp;
539         int ret = 0;
540 
541         if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
542                 return -EINVAL;
543 
544         raw_spin_lock_irqsave(&timekeeper_lock, flags);
545         write_seqcount_begin(&timekeeper_seq);
546 
547         timekeeping_forward_now(tk);
548 
549         /* Make sure the proposed value is valid */
550         tmp = timespec_add(tk_xtime(tk),  *ts);
551         if (!timespec_valid_strict(&tmp)) {
552                 ret = -EINVAL;
553                 goto error;
554         }
555 
556         tk_xtime_add(tk, ts);
557         tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *ts));
558 
559 error: /* even if we error out, we forwarded the time, so call update */
560         timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
561 
562         write_seqcount_end(&timekeeper_seq);
563         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
564 
565         /* signal hrtimers about time change */
566         clock_was_set();
567 
568         return ret;
569 }
570 EXPORT_SYMBOL(timekeeping_inject_offset);
571 
572 
573 /**
574  * timekeeping_get_tai_offset - Returns current TAI offset from UTC
575  *
576  */
577 s32 timekeeping_get_tai_offset(void)
578 {
579         struct timekeeper *tk = &timekeeper;
580         unsigned int seq;
581         s32 ret;
582 
583         do {
584                 seq = read_seqcount_begin(&timekeeper_seq);
585                 ret = tk->tai_offset;
586         } while (read_seqcount_retry(&timekeeper_seq, seq));
587 
588         return ret;
589 }
590 
591 /**
592  * __timekeeping_set_tai_offset - Lock free worker function
593  *
594  */
595 static void __timekeeping_set_tai_offset(struct timekeeper *tk, s32 tai_offset)
596 {
597         tk->tai_offset = tai_offset;
598         tk->offs_tai = ktime_sub(tk->offs_real, ktime_set(tai_offset, 0));
599 }
600 
601 /**
602  * timekeeping_set_tai_offset - Sets the current TAI offset from UTC
603  *
604  */
605 void timekeeping_set_tai_offset(s32 tai_offset)
606 {
607         struct timekeeper *tk = &timekeeper;
608         unsigned long flags;
609 
610         raw_spin_lock_irqsave(&timekeeper_lock, flags);
611         write_seqcount_begin(&timekeeper_seq);
612         __timekeeping_set_tai_offset(tk, tai_offset);
613         write_seqcount_end(&timekeeper_seq);
614         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
615         clock_was_set();
616 }
617 
618 /**
619  * change_clocksource - Swaps clocksources if a new one is available
620  *
621  * Accumulates current time interval and initializes new clocksource
622  */
623 static int change_clocksource(void *data)
624 {
625         struct timekeeper *tk = &timekeeper;
626         struct clocksource *new, *old;
627         unsigned long flags;
628 
629         new = (struct clocksource *) data;
630 
631         raw_spin_lock_irqsave(&timekeeper_lock, flags);
632         write_seqcount_begin(&timekeeper_seq);
633 
634         timekeeping_forward_now(tk);
635         /*
636          * If the cs is in module, get a module reference. Succeeds
637          * for built-in code (owner == NULL) as well.
638          */
639         if (try_module_get(new->owner)) {
640                 if (!new->enable || new->enable(new) == 0) {
641                         old = tk->clock;
642                         tk_setup_internals(tk, new);
643                         if (old->disable)
644                                 old->disable(old);
645                         module_put(old->owner);
646                 } else {
647                         module_put(new->owner);
648                 }
649         }
650         timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
651 
652         write_seqcount_end(&timekeeper_seq);
653         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
654 
655         return 0;
656 }
657 
658 /**
659  * timekeeping_notify - Install a new clock source
660  * @clock:              pointer to the clock source
661  *
662  * This function is called from clocksource.c after a new, better clock
663  * source has been registered. The caller holds the clocksource_mutex.
664  */
665 int timekeeping_notify(struct clocksource *clock)
666 {
667         struct timekeeper *tk = &timekeeper;
668 
669         if (tk->clock == clock)
670                 return 0;
671         stop_machine(change_clocksource, clock, NULL);
672         tick_clock_notify();
673         return tk->clock == clock ? 0 : -1;
674 }
675 
676 /**
677  * ktime_get_real - get the real (wall-) time in ktime_t format
678  *
679  * returns the time in ktime_t format
680  */
681 ktime_t ktime_get_real(void)
682 {
683         struct timespec now;
684 
685         getnstimeofday(&now);
686 
687         return timespec_to_ktime(now);
688 }
689 EXPORT_SYMBOL_GPL(ktime_get_real);
690 
691 /**
692  * getrawmonotonic - Returns the raw monotonic time in a timespec
693  * @ts:         pointer to the timespec to be set
694  *
695  * Returns the raw monotonic time (completely un-modified by ntp)
696  */
697 void getrawmonotonic(struct timespec *ts)
698 {
699         struct timekeeper *tk = &timekeeper;
700         unsigned long seq;
701         s64 nsecs;
702 
703         do {
704                 seq = read_seqcount_begin(&timekeeper_seq);
705                 nsecs = timekeeping_get_ns_raw(tk);
706                 *ts = tk->raw_time;
707 
708         } while (read_seqcount_retry(&timekeeper_seq, seq));
709 
710         timespec_add_ns(ts, nsecs);
711 }
712 EXPORT_SYMBOL(getrawmonotonic);
713 
714 /**
715  * timekeeping_valid_for_hres - Check if timekeeping is suitable for hres
716  */
717 int timekeeping_valid_for_hres(void)
718 {
719         struct timekeeper *tk = &timekeeper;
720         unsigned long seq;
721         int ret;
722 
723         do {
724                 seq = read_seqcount_begin(&timekeeper_seq);
725 
726                 ret = tk->clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
727 
728         } while (read_seqcount_retry(&timekeeper_seq, seq));
729 
730         return ret;
731 }
732 
733 /**
734  * timekeeping_max_deferment - Returns max time the clocksource can be deferred
735  */
736 u64 timekeeping_max_deferment(void)
737 {
738         struct timekeeper *tk = &timekeeper;
739         unsigned long seq;
740         u64 ret;
741 
742         do {
743                 seq = read_seqcount_begin(&timekeeper_seq);
744 
745                 ret = tk->clock->max_idle_ns;
746 
747         } while (read_seqcount_retry(&timekeeper_seq, seq));
748 
749         return ret;
750 }
751 
752 /**
753  * read_persistent_clock -  Return time from the persistent clock.
754  *
755  * Weak dummy function for arches that do not yet support it.
756  * Reads the time from the battery backed persistent clock.
757  * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
758  *
759  *  XXX - Do be sure to remove it once all arches implement it.
760  */
761 void __attribute__((weak)) read_persistent_clock(struct timespec *ts)
762 {
763         ts->tv_sec = 0;
764         ts->tv_nsec = 0;
765 }
766 
767 /**
768  * read_boot_clock -  Return time of the system start.
769  *
770  * Weak dummy function for arches that do not yet support it.
771  * Function to read the exact time the system has been started.
772  * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
773  *
774  *  XXX - Do be sure to remove it once all arches implement it.
775  */
776 void __attribute__((weak)) read_boot_clock(struct timespec *ts)
777 {
778         ts->tv_sec = 0;
779         ts->tv_nsec = 0;
780 }
781 
782 /*
783  * timekeeping_init - Initializes the clocksource and common timekeeping values
784  */
785 void __init timekeeping_init(void)
786 {
787         struct timekeeper *tk = &timekeeper;
788         struct clocksource *clock;
789         unsigned long flags;
790         struct timespec now, boot, tmp;
791 
792         read_persistent_clock(&now);
793 
794         if (!timespec_valid_strict(&now)) {
795                 pr_warn("WARNING: Persistent clock returned invalid value!\n"
796                         "         Check your CMOS/BIOS settings.\n");
797                 now.tv_sec = 0;
798                 now.tv_nsec = 0;
799         } else if (now.tv_sec || now.tv_nsec)
800                 persistent_clock_exist = true;
801 
802         read_boot_clock(&boot);
803         if (!timespec_valid_strict(&boot)) {
804                 pr_warn("WARNING: Boot clock returned invalid value!\n"
805                         "         Check your CMOS/BIOS settings.\n");
806                 boot.tv_sec = 0;
807                 boot.tv_nsec = 0;
808         }
809 
810         raw_spin_lock_irqsave(&timekeeper_lock, flags);
811         write_seqcount_begin(&timekeeper_seq);
812         ntp_init();
813 
814         clock = clocksource_default_clock();
815         if (clock->enable)
816                 clock->enable(clock);
817         tk_setup_internals(tk, clock);
818 
819         tk_set_xtime(tk, &now);
820         tk->raw_time.tv_sec = 0;
821         tk->raw_time.tv_nsec = 0;
822         if (boot.tv_sec == 0 && boot.tv_nsec == 0)
823                 boot = tk_xtime(tk);
824 
825         set_normalized_timespec(&tmp, -boot.tv_sec, -boot.tv_nsec);
826         tk_set_wall_to_mono(tk, tmp);
827 
828         tmp.tv_sec = 0;
829         tmp.tv_nsec = 0;
830         tk_set_sleep_time(tk, tmp);
831 
832         memcpy(&shadow_timekeeper, &timekeeper, sizeof(timekeeper));
833 
834         write_seqcount_end(&timekeeper_seq);
835         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
836 }
837 
838 /* time in seconds when suspend began */
839 static struct timespec timekeeping_suspend_time;
840 
841 /**
842  * __timekeeping_inject_sleeptime - Internal function to add sleep interval
843  * @delta: pointer to a timespec delta value
844  *
845  * Takes a timespec offset measuring a suspend interval and properly
846  * adds the sleep offset to the timekeeping variables.
847  */
848 static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
849                                                         struct timespec *delta)
850 {
851         if (!timespec_valid_strict(delta)) {
852                 printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
853                                         "sleep delta value!\n");
854                 return;
855         }
856         tk_xtime_add(tk, delta);
857         tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *delta));
858         tk_set_sleep_time(tk, timespec_add(tk->total_sleep_time, *delta));
859         tk_debug_account_sleep_time(delta);
860 }
861 
862 /**
863  * timekeeping_inject_sleeptime - Adds suspend interval to timeekeeping values
864  * @delta: pointer to a timespec delta value
865  *
866  * This hook is for architectures that cannot support read_persistent_clock
867  * because their RTC/persistent clock is only accessible when irqs are enabled.
868  *
869  * This function should only be called by rtc_resume(), and allows
870  * a suspend offset to be injected into the timekeeping values.
871  */
872 void timekeeping_inject_sleeptime(struct timespec *delta)
873 {
874         struct timekeeper *tk = &timekeeper;
875         unsigned long flags;
876 
877         /*
878          * Make sure we don't set the clock twice, as timekeeping_resume()
879          * already did it
880          */
881         if (has_persistent_clock())
882                 return;
883 
884         raw_spin_lock_irqsave(&timekeeper_lock, flags);
885         write_seqcount_begin(&timekeeper_seq);
886 
887         timekeeping_forward_now(tk);
888 
889         __timekeeping_inject_sleeptime(tk, delta);
890 
891         timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
892 
893         write_seqcount_end(&timekeeper_seq);
894         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
895 
896         /* signal hrtimers about time change */
897         clock_was_set();
898 }
899 
900 /**
901  * timekeeping_resume - Resumes the generic timekeeping subsystem.
902  *
903  * This is for the generic clocksource timekeeping.
904  * xtime/wall_to_monotonic/jiffies/etc are
905  * still managed by arch specific suspend/resume code.
906  */
907 static void timekeeping_resume(void)
908 {
909         struct timekeeper *tk = &timekeeper;
910         struct clocksource *clock = tk->clock;
911         unsigned long flags;
912         struct timespec ts_new, ts_delta;
913         cycle_t cycle_now, cycle_delta;
914         bool suspendtime_found = false;
915 
916         read_persistent_clock(&ts_new);
917 
918         clockevents_resume();
919         clocksource_resume();
920 
921         raw_spin_lock_irqsave(&timekeeper_lock, flags);
922         write_seqcount_begin(&timekeeper_seq);
923 
924         /*
925          * After system resumes, we need to calculate the suspended time and
926          * compensate it for the OS time. There are 3 sources that could be
927          * used: Nonstop clocksource during suspend, persistent clock and rtc
928          * device.
929          *
930          * One specific platform may have 1 or 2 or all of them, and the
931          * preference will be:
932          *      suspend-nonstop clocksource -> persistent clock -> rtc
933          * The less preferred source will only be tried if there is no better
934          * usable source. The rtc part is handled separately in rtc core code.
935          */
936         cycle_now = clock->read(clock);
937         if ((clock->flags & CLOCK_SOURCE_SUSPEND_NONSTOP) &&
938                 cycle_now > clock->cycle_last) {
939                 u64 num, max = ULLONG_MAX;
940                 u32 mult = clock->mult;
941                 u32 shift = clock->shift;
942                 s64 nsec = 0;
943 
944                 cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
945 
946                 /*
947                  * "cycle_delta * mutl" may cause 64 bits overflow, if the
948                  * suspended time is too long. In that case we need do the
949                  * 64 bits math carefully
950                  */
951                 do_div(max, mult);
952                 if (cycle_delta > max) {
953                         num = div64_u64(cycle_delta, max);
954                         nsec = (((u64) max * mult) >> shift) * num;
955                         cycle_delta -= num * max;
956                 }
957                 nsec += ((u64) cycle_delta * mult) >> shift;
958 
959                 ts_delta = ns_to_timespec(nsec);
960                 suspendtime_found = true;
961         } else if (timespec_compare(&ts_new, &timekeeping_suspend_time) > 0) {
962                 ts_delta = timespec_sub(ts_new, timekeeping_suspend_time);
963                 suspendtime_found = true;
964         }
965 
966         if (suspendtime_found)
967                 __timekeeping_inject_sleeptime(tk, &ts_delta);
968 
969         /* Re-base the last cycle value */
970         tk->cycle_last = clock->cycle_last = cycle_now;
971         tk->ntp_error = 0;
972         timekeeping_suspended = 0;
973         timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
974         write_seqcount_end(&timekeeper_seq);
975         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
976 
977         touch_softlockup_watchdog();
978 
979         clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
980 
981         /* Resume hrtimers */
982         hrtimers_resume();
983 }
984 
985 static int timekeeping_suspend(void)
986 {
987         struct timekeeper *tk = &timekeeper;
988         unsigned long flags;
989         struct timespec         delta, delta_delta;
990         static struct timespec  old_delta;
991 
992         read_persistent_clock(&timekeeping_suspend_time);
993 
994         /*
995          * On some systems the persistent_clock can not be detected at
996          * timekeeping_init by its return value, so if we see a valid
997          * value returned, update the persistent_clock_exists flag.
998          */
999         if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec)
1000                 persistent_clock_exist = true;
1001 
1002         raw_spin_lock_irqsave(&timekeeper_lock, flags);
1003         write_seqcount_begin(&timekeeper_seq);
1004         timekeeping_forward_now(tk);
1005         timekeeping_suspended = 1;
1006 
1007         /*
1008          * To avoid drift caused by repeated suspend/resumes,
1009          * which each can add ~1 second drift error,
1010          * try to compensate so the difference in system time
1011          * and persistent_clock time stays close to constant.
1012          */
1013         delta = timespec_sub(tk_xtime(tk), timekeeping_suspend_time);
1014         delta_delta = timespec_sub(delta, old_delta);
1015         if (abs(delta_delta.tv_sec)  >= 2) {
1016                 /*
1017                  * if delta_delta is too large, assume time correction
1018                  * has occured and set old_delta to the current delta.
1019                  */
1020                 old_delta = delta;
1021         } else {
1022                 /* Otherwise try to adjust old_system to compensate */
1023                 timekeeping_suspend_time =
1024                         timespec_add(timekeeping_suspend_time, delta_delta);
1025         }
1026         write_seqcount_end(&timekeeper_seq);
1027         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1028 
1029         clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
1030         clocksource_suspend();
1031         clockevents_suspend();
1032 
1033         return 0;
1034 }
1035 
1036 /* sysfs resume/suspend bits for timekeeping */
1037 static struct syscore_ops timekeeping_syscore_ops = {
1038         .resume         = timekeeping_resume,
1039         .suspend        = timekeeping_suspend,
1040 };
1041 
1042 static int __init timekeeping_init_ops(void)
1043 {
1044         register_syscore_ops(&timekeeping_syscore_ops);
1045         return 0;
1046 }
1047 
1048 device_initcall(timekeeping_init_ops);
1049 
1050 /*
1051  * If the error is already larger, we look ahead even further
1052  * to compensate for late or lost adjustments.
1053  */
1054 static __always_inline int timekeeping_bigadjust(struct timekeeper *tk,
1055                                                  s64 error, s64 *interval,
1056                                                  s64 *offset)
1057 {
1058         s64 tick_error, i;
1059         u32 look_ahead, adj;
1060         s32 error2, mult;
1061 
1062         /*
1063          * Use the current error value to determine how much to look ahead.
1064          * The larger the error the slower we adjust for it to avoid problems
1065          * with losing too many ticks, otherwise we would overadjust and
1066          * produce an even larger error.  The smaller the adjustment the
1067          * faster we try to adjust for it, as lost ticks can do less harm
1068          * here.  This is tuned so that an error of about 1 msec is adjusted
1069          * within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
1070          */
1071         error2 = tk->ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
1072         error2 = abs(error2);
1073         for (look_ahead = 0; error2 > 0; look_ahead++)
1074                 error2 >>= 2;
1075 
1076         /*
1077          * Now calculate the error in (1 << look_ahead) ticks, but first
1078          * remove the single look ahead already included in the error.
1079          */
1080         tick_error = ntp_tick_length() >> (tk->ntp_error_shift + 1);
1081         tick_error -= tk->xtime_interval >> 1;
1082         error = ((error - tick_error) >> look_ahead) + tick_error;
1083 
1084         /* Finally calculate the adjustment shift value.  */
1085         i = *interval;
1086         mult = 1;
1087         if (error < 0) {
1088                 error = -error;
1089                 *interval = -*interval;
1090                 *offset = -*offset;
1091                 mult = -1;
1092         }
1093         for (adj = 0; error > i; adj++)
1094                 error >>= 1;
1095 
1096         *interval <<= adj;
1097         *offset <<= adj;
1098         return mult << adj;
1099 }
1100 
1101 /*
1102  * Adjust the multiplier to reduce the error value,
1103  * this is optimized for the most common adjustments of -1,0,1,
1104  * for other values we can do a bit more work.
1105  */
1106 static void timekeeping_adjust(struct timekeeper *tk, s64 offset)
1107 {
1108         s64 error, interval = tk->cycle_interval;
1109         int adj;
1110 
1111         /*
1112          * The point of this is to check if the error is greater than half
1113          * an interval.
1114          *
1115          * First we shift it down from NTP_SHIFT to clocksource->shifted nsecs.
1116          *
1117          * Note we subtract one in the shift, so that error is really error*2.
1118          * This "saves" dividing(shifting) interval twice, but keeps the
1119          * (error > interval) comparison as still measuring if error is
1120          * larger than half an interval.
1121          *
1122          * Note: It does not "save" on aggravation when reading the code.
1123          */
1124         error = tk->ntp_error >> (tk->ntp_error_shift - 1);
1125         if (error > interval) {
1126                 /*
1127                  * We now divide error by 4(via shift), which checks if
1128                  * the error is greater than twice the interval.
1129                  * If it is greater, we need a bigadjust, if its smaller,
1130                  * we can adjust by 1.
1131                  */
1132                 error >>= 2;
1133                 /*
1134                  * XXX - In update_wall_time, we round up to the next
1135                  * nanosecond, and store the amount rounded up into
1136                  * the error. This causes the likely below to be unlikely.
1137                  *
1138                  * The proper fix is to avoid rounding up by using
1139                  * the high precision tk->xtime_nsec instead of
1140                  * xtime.tv_nsec everywhere. Fixing this will take some
1141                  * time.
1142                  */
1143                 if (likely(error <= interval))
1144                         adj = 1;
1145                 else
1146                         adj = timekeeping_bigadjust(tk, error, &interval, &offset);
1147         } else {
1148                 if (error < -interval) {
1149                         /* See comment above, this is just switched for the negative */
1150                         error >>= 2;
1151                         if (likely(error >= -interval)) {
1152                                 adj = -1;
1153                                 interval = -interval;
1154                                 offset = -offset;
1155                         } else {
1156                                 adj = timekeeping_bigadjust(tk, error, &interval, &offset);
1157                         }
1158                 } else {
1159                         goto out_adjust;
1160                 }
1161         }
1162 
1163         if (unlikely(tk->clock->maxadj &&
1164                 (tk->mult + adj > tk->clock->mult + tk->clock->maxadj))) {
1165                 printk_once(KERN_WARNING
1166                         "Adjusting %s more than 11%% (%ld vs %ld)\n",
1167                         tk->clock->name, (long)tk->mult + adj,
1168                         (long)tk->clock->mult + tk->clock->maxadj);
1169         }
1170         /*
1171          * So the following can be confusing.
1172          *
1173          * To keep things simple, lets assume adj == 1 for now.
1174          *
1175          * When adj != 1, remember that the interval and offset values
1176          * have been appropriately scaled so the math is the same.
1177          *
1178          * The basic idea here is that we're increasing the multiplier
1179          * by one, this causes the xtime_interval to be incremented by
1180          * one cycle_interval. This is because:
1181          *      xtime_interval = cycle_interval * mult
1182          * So if mult is being incremented by one:
1183          *      xtime_interval = cycle_interval * (mult + 1)
1184          * Its the same as:
1185          *      xtime_interval = (cycle_interval * mult) + cycle_interval
1186          * Which can be shortened to:
1187          *      xtime_interval += cycle_interval
1188          *
1189          * So offset stores the non-accumulated cycles. Thus the current
1190          * time (in shifted nanoseconds) is:
1191          *      now = (offset * adj) + xtime_nsec
1192          * Now, even though we're adjusting the clock frequency, we have
1193          * to keep time consistent. In other words, we can't jump back
1194          * in time, and we also want to avoid jumping forward in time.
1195          *
1196          * So given the same offset value, we need the time to be the same
1197          * both before and after the freq adjustment.
1198          *      now = (offset * adj_1) + xtime_nsec_1
1199          *      now = (offset * adj_2) + xtime_nsec_2
1200          * So:
1201          *      (offset * adj_1) + xtime_nsec_1 =
1202          *              (offset * adj_2) + xtime_nsec_2
1203          * And we know:
1204          *      adj_2 = adj_1 + 1
1205          * So:
1206          *      (offset * adj_1) + xtime_nsec_1 =
1207          *              (offset * (adj_1+1)) + xtime_nsec_2
1208          *      (offset * adj_1) + xtime_nsec_1 =
1209          *              (offset * adj_1) + offset + xtime_nsec_2
1210          * Canceling the sides:
1211          *      xtime_nsec_1 = offset + xtime_nsec_2
1212          * Which gives us:
1213          *      xtime_nsec_2 = xtime_nsec_1 - offset
1214          * Which simplfies to:
1215          *      xtime_nsec -= offset
1216          *
1217          * XXX - TODO: Doc ntp_error calculation.
1218          */
1219         tk->mult += adj;
1220         tk->xtime_interval += interval;
1221         tk->xtime_nsec -= offset;
1222         tk->ntp_error -= (interval - offset) << tk->ntp_error_shift;
1223 
1224 out_adjust:
1225         /*
1226          * It may be possible that when we entered this function, xtime_nsec
1227          * was very small.  Further, if we're slightly speeding the clocksource
1228          * in the code above, its possible the required corrective factor to
1229          * xtime_nsec could cause it to underflow.
1230          *
1231          * Now, since we already accumulated the second, cannot simply roll
1232          * the accumulated second back, since the NTP subsystem has been
1233          * notified via second_overflow. So instead we push xtime_nsec forward
1234          * by the amount we underflowed, and add that amount into the error.
1235          *
1236          * We'll correct this error next time through this function, when
1237          * xtime_nsec is not as small.
1238          */
1239         if (unlikely((s64)tk->xtime_nsec < 0)) {
1240                 s64 neg = -(s64)tk->xtime_nsec;
1241                 tk->xtime_nsec = 0;
1242                 tk->ntp_error += neg << tk->ntp_error_shift;
1243         }
1244 
1245 }
1246 
1247 /**
1248  * accumulate_nsecs_to_secs - Accumulates nsecs into secs
1249  *
1250  * Helper function that accumulates a the nsecs greater then a second
1251  * from the xtime_nsec field to the xtime_secs field.
1252  * It also calls into the NTP code to handle leapsecond processing.
1253  *
1254  */
1255 static inline unsigned int accumulate_nsecs_to_secs(struct timekeeper *tk)
1256 {
1257         u64 nsecps = (u64)NSEC_PER_SEC << tk->shift;
1258         unsigned int action = 0;
1259 
1260         while (tk->xtime_nsec >= nsecps) {
1261                 int leap;
1262 
1263                 tk->xtime_nsec -= nsecps;
1264                 tk->xtime_sec++;
1265 
1266                 /* Figure out if its a leap sec and apply if needed */
1267                 leap = second_overflow(tk->xtime_sec);
1268                 if (unlikely(leap)) {
1269                         struct timespec ts;
1270 
1271                         tk->xtime_sec += leap;
1272 
1273                         ts.tv_sec = leap;
1274                         ts.tv_nsec = 0;
1275                         tk_set_wall_to_mono(tk,
1276                                 timespec_sub(tk->wall_to_monotonic, ts));
1277 
1278                         __timekeeping_set_tai_offset(tk, tk->tai_offset - leap);
1279 
1280                         clock_was_set_delayed();
1281                         action = TK_CLOCK_WAS_SET;
1282                 }
1283         }
1284         return action;
1285 }
1286 
1287 /**
1288  * logarithmic_accumulation - shifted accumulation of cycles
1289  *
1290  * This functions accumulates a shifted interval of cycles into
1291  * into a shifted interval nanoseconds. Allows for O(log) accumulation
1292  * loop.
1293  *
1294  * Returns the unconsumed cycles.
1295  */
1296 static cycle_t logarithmic_accumulation(struct timekeeper *tk, cycle_t offset,
1297                                                 u32 shift)
1298 {
1299         cycle_t interval = tk->cycle_interval << shift;
1300         u64 raw_nsecs;
1301 
1302         /* If the offset is smaller then a shifted interval, do nothing */
1303         if (offset < interval)
1304                 return offset;
1305 
1306         /* Accumulate one shifted interval */
1307         offset -= interval;
1308         tk->cycle_last += interval;
1309 
1310         tk->xtime_nsec += tk->xtime_interval << shift;
1311         accumulate_nsecs_to_secs(tk);
1312 
1313         /* Accumulate raw time */
1314         raw_nsecs = (u64)tk->raw_interval << shift;
1315         raw_nsecs += tk->raw_time.tv_nsec;
1316         if (raw_nsecs >= NSEC_PER_SEC) {
1317                 u64 raw_secs = raw_nsecs;
1318                 raw_nsecs = do_div(raw_secs, NSEC_PER_SEC);
1319                 tk->raw_time.tv_sec += raw_secs;
1320         }
1321         tk->raw_time.tv_nsec = raw_nsecs;
1322 
1323         /* Accumulate error between NTP and clock interval */
1324         tk->ntp_error += ntp_tick_length() << shift;
1325         tk->ntp_error -= (tk->xtime_interval + tk->xtime_remainder) <<
1326                                                 (tk->ntp_error_shift + shift);
1327 
1328         return offset;
1329 }
1330 
1331 #ifdef CONFIG_GENERIC_TIME_VSYSCALL_OLD
1332 static inline void old_vsyscall_fixup(struct timekeeper *tk)
1333 {
1334         s64 remainder;
1335 
1336         /*
1337         * Store only full nanoseconds into xtime_nsec after rounding
1338         * it up and add the remainder to the error difference.
1339         * XXX - This is necessary to avoid small 1ns inconsistnecies caused
1340         * by truncating the remainder in vsyscalls. However, it causes
1341         * additional work to be done in timekeeping_adjust(). Once
1342         * the vsyscall implementations are converted to use xtime_nsec
1343         * (shifted nanoseconds), and CONFIG_GENERIC_TIME_VSYSCALL_OLD
1344         * users are removed, this can be killed.
1345         */
1346         remainder = tk->xtime_nsec & ((1ULL << tk->shift) - 1);
1347         tk->xtime_nsec -= remainder;
1348         tk->xtime_nsec += 1ULL << tk->shift;
1349         tk->ntp_error += remainder << tk->ntp_error_shift;
1350 
1351 }
1352 #else
1353 #define old_vsyscall_fixup(tk)
1354 #endif
1355 
1356 
1357 
1358 /**
1359  * update_wall_time - Uses the current clocksource to increment the wall time
1360  *
1361  */
1362 static void update_wall_time(void)
1363 {
1364         struct clocksource *clock;
1365         struct timekeeper *real_tk = &timekeeper;
1366         struct timekeeper *tk = &shadow_timekeeper;
1367         cycle_t offset;
1368         int shift = 0, maxshift;
1369         unsigned int action;
1370         unsigned long flags;
1371 
1372         raw_spin_lock_irqsave(&timekeeper_lock, flags);
1373 
1374         /* Make sure we're fully resumed: */
1375         if (unlikely(timekeeping_suspended))
1376                 goto out;
1377 
1378         clock = real_tk->clock;
1379 
1380 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
1381         offset = real_tk->cycle_interval;
1382 #else
1383         offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
1384 #endif
1385 
1386         /* Check if there's really nothing to do */
1387         if (offset < real_tk->cycle_interval)
1388                 goto out;
1389 
1390         /*
1391          * With NO_HZ we may have to accumulate many cycle_intervals
1392          * (think "ticks") worth of time at once. To do this efficiently,
1393          * we calculate the largest doubling multiple of cycle_intervals
1394          * that is smaller than the offset.  We then accumulate that
1395          * chunk in one go, and then try to consume the next smaller
1396          * doubled multiple.
1397          */
1398         shift = ilog2(offset) - ilog2(tk->cycle_interval);
1399         shift = max(0, shift);
1400         /* Bound shift to one less than what overflows tick_length */
1401         maxshift = (64 - (ilog2(ntp_tick_length())+1)) - 1;
1402         shift = min(shift, maxshift);
1403         while (offset >= tk->cycle_interval) {
1404                 offset = logarithmic_accumulation(tk, offset, shift);
1405                 if (offset < tk->cycle_interval<<shift)
1406                         shift--;
1407         }
1408 
1409         /* correct the clock when NTP error is too big */
1410         timekeeping_adjust(tk, offset);
1411 
1412         /*
1413          * XXX This can be killed once everyone converts
1414          * to the new update_vsyscall.
1415          */
1416         old_vsyscall_fixup(tk);
1417 
1418         /*
1419          * Finally, make sure that after the rounding
1420          * xtime_nsec isn't larger than NSEC_PER_SEC
1421          */
1422         action = accumulate_nsecs_to_secs(tk);
1423 
1424         write_seqcount_begin(&timekeeper_seq);
1425         /* Update clock->cycle_last with the new value */
1426         clock->cycle_last = tk->cycle_last;
1427         /*
1428          * Update the real timekeeper.
1429          *
1430          * We could avoid this memcpy by switching pointers, but that
1431          * requires changes to all other timekeeper usage sites as
1432          * well, i.e. move the timekeeper pointer getter into the
1433          * spinlocked/seqcount protected sections. And we trade this
1434          * memcpy under the timekeeper_seq against one before we start
1435          * updating.
1436          */
1437         memcpy(real_tk, tk, sizeof(*tk));
1438         timekeeping_update(real_tk, action);
1439         write_seqcount_end(&timekeeper_seq);
1440 out:
1441         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1442 }
1443 
1444 /**
1445  * getboottime - Return the real time of system boot.
1446  * @ts:         pointer to the timespec to be set
1447  *
1448  * Returns the wall-time of boot in a timespec.
1449  *
1450  * This is based on the wall_to_monotonic offset and the total suspend
1451  * time. Calls to settimeofday will affect the value returned (which
1452  * basically means that however wrong your real time clock is at boot time,
1453  * you get the right time here).
1454  */
1455 void getboottime(struct timespec *ts)
1456 {
1457         struct timekeeper *tk = &timekeeper;
1458         struct timespec boottime = {
1459                 .tv_sec = tk->wall_to_monotonic.tv_sec +
1460                                 tk->total_sleep_time.tv_sec,
1461                 .tv_nsec = tk->wall_to_monotonic.tv_nsec +
1462                                 tk->total_sleep_time.tv_nsec
1463         };
1464 
1465         set_normalized_timespec(ts, -boottime.tv_sec, -boottime.tv_nsec);
1466 }
1467 EXPORT_SYMBOL_GPL(getboottime);
1468 
1469 /**
1470  * get_monotonic_boottime - Returns monotonic time since boot
1471  * @ts:         pointer to the timespec to be set
1472  *
1473  * Returns the monotonic time since boot in a timespec.
1474  *
1475  * This is similar to CLOCK_MONTONIC/ktime_get_ts, but also
1476  * includes the time spent in suspend.
1477  */
1478 void get_monotonic_boottime(struct timespec *ts)
1479 {
1480         struct timekeeper *tk = &timekeeper;
1481         struct timespec tomono, sleep;
1482         s64 nsec;
1483         unsigned int seq;
1484 
1485         WARN_ON(timekeeping_suspended);
1486 
1487         do {
1488                 seq = read_seqcount_begin(&timekeeper_seq);
1489                 ts->tv_sec = tk->xtime_sec;
1490                 nsec = timekeeping_get_ns(tk);
1491                 tomono = tk->wall_to_monotonic;
1492                 sleep = tk->total_sleep_time;
1493 
1494         } while (read_seqcount_retry(&timekeeper_seq, seq));
1495 
1496         ts->tv_sec += tomono.tv_sec + sleep.tv_sec;
1497         ts->tv_nsec = 0;
1498         timespec_add_ns(ts, nsec + tomono.tv_nsec + sleep.tv_nsec);
1499 }
1500 EXPORT_SYMBOL_GPL(get_monotonic_boottime);
1501 
1502 /**
1503  * ktime_get_boottime - Returns monotonic time since boot in a ktime
1504  *
1505  * Returns the monotonic time since boot in a ktime
1506  *
1507  * This is similar to CLOCK_MONTONIC/ktime_get, but also
1508  * includes the time spent in suspend.
1509  */
1510 ktime_t ktime_get_boottime(void)
1511 {
1512         struct timespec ts;
1513 
1514         get_monotonic_boottime(&ts);
1515         return timespec_to_ktime(ts);
1516 }
1517 EXPORT_SYMBOL_GPL(ktime_get_boottime);
1518 
1519 /**
1520  * monotonic_to_bootbased - Convert the monotonic time to boot based.
1521  * @ts:         pointer to the timespec to be converted
1522  */
1523 void monotonic_to_bootbased(struct timespec *ts)
1524 {
1525         struct timekeeper *tk = &timekeeper;
1526 
1527         *ts = timespec_add(*ts, tk->total_sleep_time);
1528 }
1529 EXPORT_SYMBOL_GPL(monotonic_to_bootbased);
1530 
1531 unsigned long get_seconds(void)
1532 {
1533         struct timekeeper *tk = &timekeeper;
1534 
1535         return tk->xtime_sec;
1536 }
1537 EXPORT_SYMBOL(get_seconds);
1538 
1539 struct timespec __current_kernel_time(void)
1540 {
1541         struct timekeeper *tk = &timekeeper;
1542 
1543         return tk_xtime(tk);
1544 }
1545 
1546 struct timespec current_kernel_time(void)
1547 {
1548         struct timekeeper *tk = &timekeeper;
1549         struct timespec now;
1550         unsigned long seq;
1551 
1552         do {
1553                 seq = read_seqcount_begin(&timekeeper_seq);
1554 
1555                 now = tk_xtime(tk);
1556         } while (read_seqcount_retry(&timekeeper_seq, seq));
1557 
1558         return now;
1559 }
1560 EXPORT_SYMBOL(current_kernel_time);
1561 
1562 struct timespec get_monotonic_coarse(void)
1563 {
1564         struct timekeeper *tk = &timekeeper;
1565         struct timespec now, mono;
1566         unsigned long seq;
1567 
1568         do {
1569                 seq = read_seqcount_begin(&timekeeper_seq);
1570 
1571                 now = tk_xtime(tk);
1572                 mono = tk->wall_to_monotonic;
1573         } while (read_seqcount_retry(&timekeeper_seq, seq));
1574 
1575         set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
1576                                 now.tv_nsec + mono.tv_nsec);
1577         return now;
1578 }
1579 
1580 /*
1581  * Must hold jiffies_lock
1582  */
1583 void do_timer(unsigned long ticks)
1584 {
1585         jiffies_64 += ticks;
1586         update_wall_time();
1587         calc_global_load(ticks);
1588 }
1589 
1590 /**
1591  * get_xtime_and_monotonic_and_sleep_offset() - get xtime, wall_to_monotonic,
1592  *    and sleep offsets.
1593  * @xtim:       pointer to timespec to be set with xtime
1594  * @wtom:       pointer to timespec to be set with wall_to_monotonic
1595  * @sleep:      pointer to timespec to be set with time in suspend
1596  */
1597 void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
1598                                 struct timespec *wtom, struct timespec *sleep)
1599 {
1600         struct timekeeper *tk = &timekeeper;
1601         unsigned long seq;
1602 
1603         do {
1604                 seq = read_seqcount_begin(&timekeeper_seq);
1605                 *xtim = tk_xtime(tk);
1606                 *wtom = tk->wall_to_monotonic;
1607                 *sleep = tk->total_sleep_time;
1608         } while (read_seqcount_retry(&timekeeper_seq, seq));
1609 }
1610 
1611 #ifdef CONFIG_HIGH_RES_TIMERS
1612 /**
1613  * ktime_get_update_offsets - hrtimer helper
1614  * @offs_real:  pointer to storage for monotonic -> realtime offset
1615  * @offs_boot:  pointer to storage for monotonic -> boottime offset
1616  *
1617  * Returns current monotonic time and updates the offsets
1618  * Called from hrtimer_interupt() or retrigger_next_event()
1619  */
1620 ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot,
1621                                                         ktime_t *offs_tai)
1622 {
1623         struct timekeeper *tk = &timekeeper;
1624         ktime_t now;
1625         unsigned int seq;
1626         u64 secs, nsecs;
1627 
1628         do {
1629                 seq = read_seqcount_begin(&timekeeper_seq);
1630 
1631                 secs = tk->xtime_sec;
1632                 nsecs = timekeeping_get_ns(tk);
1633 
1634                 *offs_real = tk->offs_real;
1635                 *offs_boot = tk->offs_boot;
1636                 *offs_tai = tk->offs_tai;
1637         } while (read_seqcount_retry(&timekeeper_seq, seq));
1638 
1639         now = ktime_add_ns(ktime_set(secs, 0), nsecs);
1640         now = ktime_sub(now, *offs_real);
1641         return now;
1642 }
1643 #endif
1644 
1645 /**
1646  * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
1647  */
1648 ktime_t ktime_get_monotonic_offset(void)
1649 {
1650         struct timekeeper *tk = &timekeeper;
1651         unsigned long seq;
1652         struct timespec wtom;
1653 
1654         do {
1655                 seq = read_seqcount_begin(&timekeeper_seq);
1656                 wtom = tk->wall_to_monotonic;
1657         } while (read_seqcount_retry(&timekeeper_seq, seq));
1658 
1659         return timespec_to_ktime(wtom);
1660 }
1661 EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset);
1662 
1663 /**
1664  * do_adjtimex() - Accessor function to NTP __do_adjtimex function
1665  */
1666 int do_adjtimex(struct timex *txc)
1667 {
1668         struct timekeeper *tk = &timekeeper;
1669         unsigned long flags;
1670         struct timespec ts;
1671         s32 orig_tai, tai;
1672         int ret;
1673 
1674         /* Validate the data before disabling interrupts */
1675         ret = ntp_validate_timex(txc);
1676         if (ret)
1677                 return ret;
1678 
1679         if (txc->modes & ADJ_SETOFFSET) {
1680                 struct timespec delta;
1681                 delta.tv_sec  = txc->time.tv_sec;
1682                 delta.tv_nsec = txc->time.tv_usec;
1683                 if (!(txc->modes & ADJ_NANO))
1684                         delta.tv_nsec *= 1000;
1685                 ret = timekeeping_inject_offset(&delta);
1686                 if (ret)
1687                         return ret;
1688         }
1689 
1690         getnstimeofday(&ts);
1691 
1692         raw_spin_lock_irqsave(&timekeeper_lock, flags);
1693         write_seqcount_begin(&timekeeper_seq);
1694 
1695         orig_tai = tai = tk->tai_offset;
1696         ret = __do_adjtimex(txc, &ts, &tai);
1697 
1698         if (tai != orig_tai) {
1699                 __timekeeping_set_tai_offset(tk, tai);
1700                 update_pvclock_gtod(tk, true);
1701                 clock_was_set_delayed();
1702         }
1703         write_seqcount_end(&timekeeper_seq);
1704         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1705 
1706         ntp_notify_cmos_timer();
1707 
1708         return ret;
1709 }
1710 
1711 #ifdef CONFIG_NTP_PPS
1712 /**
1713  * hardpps() - Accessor function to NTP __hardpps function
1714  */
1715 void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts)
1716 {
1717         unsigned long flags;
1718 
1719         raw_spin_lock_irqsave(&timekeeper_lock, flags);
1720         write_seqcount_begin(&timekeeper_seq);
1721 
1722         __hardpps(phase_ts, raw_ts);
1723 
1724         write_seqcount_end(&timekeeper_seq);
1725         raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
1726 }
1727 EXPORT_SYMBOL(hardpps);
1728 #endif
1729 
1730 /**
1731  * xtime_update() - advances the timekeeping infrastructure
1732  * @ticks:      number of ticks, that have elapsed since the last call.
1733  *
1734  * Must be called with interrupts disabled.
1735  */
1736 void xtime_update(unsigned long ticks)
1737 {
1738         write_seqlock(&jiffies_lock);
1739         do_timer(ticks);
1740         write_sequnlock(&jiffies_lock);
1741 }
1742 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp