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1/*
2 * NTP state machine interfaces and logic.
3 *
4 * This code was mainly moved from kernel/timer.c and kernel/time.c
5 * Please see those files for relevant copyright info and historical
6 * changelogs.
7 */
8#include <linux/capability.h>
9#include <linux/clocksource.h>
10#include <linux/workqueue.h>
11#include <linux/hrtimer.h>
12#include <linux/jiffies.h>
13#include <linux/math64.h>
14#include <linux/timex.h>
15#include <linux/time.h>
16#include <linux/mm.h>
17#include <linux/module.h>
18#include <linux/rtc.h>
19#include <linux/math64.h>
20
21#include "ntp_internal.h"
22#include "timekeeping_internal.h"
23
24
25/*
26 * NTP timekeeping variables:
27 *
28 * Note: All of the NTP state is protected by the timekeeping locks.
29 */
30
31
32/* USER_HZ period (usecs): */
33unsigned long tick_usec = TICK_USEC;
34
35/* SHIFTED_HZ period (nsecs): */
36unsigned long tick_nsec;
37
38static u64 tick_length;
39static u64 tick_length_base;
40
41#define SECS_PER_DAY 86400
42#define MAX_TICKADJ 500LL /* usecs */
43#define MAX_TICKADJ_SCALED \
44 (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
45
46/*
47 * phase-lock loop variables
48 */
49
50/*
51 * clock synchronization status
52 *
53 * (TIME_ERROR prevents overwriting the CMOS clock)
54 */
55static int time_state = TIME_OK;
56
57/* clock status bits: */
58static int time_status = STA_UNSYNC;
59
60/* time adjustment (nsecs): */
61static s64 time_offset;
62
63/* pll time constant: */
64static long time_constant = 2;
65
66/* maximum error (usecs): */
67static long time_maxerror = NTP_PHASE_LIMIT;
68
69/* estimated error (usecs): */
70static long time_esterror = NTP_PHASE_LIMIT;
71
72/* frequency offset (scaled nsecs/secs): */
73static s64 time_freq;
74
75/* time at last adjustment (secs): */
76static time64_t time_reftime;
77
78static long time_adjust;
79
80/* constant (boot-param configurable) NTP tick adjustment (upscaled) */
81static s64 ntp_tick_adj;
82
83/* second value of the next pending leapsecond, or TIME64_MAX if no leap */
84static time64_t ntp_next_leap_sec = TIME64_MAX;
85
86#ifdef CONFIG_NTP_PPS
87
88/*
89 * The following variables are used when a pulse-per-second (PPS) signal
90 * is available. They establish the engineering parameters of the clock
91 * discipline loop when controlled by the PPS signal.
92 */
93#define PPS_VALID 10 /* PPS signal watchdog max (s) */
94#define PPS_POPCORN 4 /* popcorn spike threshold (shift) */
95#define PPS_INTMIN 2 /* min freq interval (s) (shift) */
96#define PPS_INTMAX 8 /* max freq interval (s) (shift) */
97#define PPS_INTCOUNT 4 /* number of consecutive good intervals to
98 increase pps_shift or consecutive bad
99 intervals to decrease it */
100#define PPS_MAXWANDER 100000 /* max PPS freq wander (ns/s) */
101
102static int pps_valid; /* signal watchdog counter */
103static long pps_tf[3]; /* phase median filter */
104static long pps_jitter; /* current jitter (ns) */
105static struct timespec64 pps_fbase; /* beginning of the last freq interval */
106static int pps_shift; /* current interval duration (s) (shift) */
107static int pps_intcnt; /* interval counter */
108static s64 pps_freq; /* frequency offset (scaled ns/s) */
109static long pps_stabil; /* current stability (scaled ns/s) */
110
111/*
112 * PPS signal quality monitors
113 */
114static long pps_calcnt; /* calibration intervals */
115static long pps_jitcnt; /* jitter limit exceeded */
116static long pps_stbcnt; /* stability limit exceeded */
117static long pps_errcnt; /* calibration errors */
118
119
120/* PPS kernel consumer compensates the whole phase error immediately.
121 * Otherwise, reduce the offset by a fixed factor times the time constant.
122 */
123static inline s64 ntp_offset_chunk(s64 offset)
124{
125 if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL)
126 return offset;
127 else
128 return shift_right(offset, SHIFT_PLL + time_constant);
129}
130
131static inline void pps_reset_freq_interval(void)
132{
133 /* the PPS calibration interval may end
134 surprisingly early */
135 pps_shift = PPS_INTMIN;
136 pps_intcnt = 0;
137}
138
139/**
140 * pps_clear - Clears the PPS state variables
141 */
142static inline void pps_clear(void)
143{
144 pps_reset_freq_interval();
145 pps_tf[0] = 0;
146 pps_tf[1] = 0;
147 pps_tf[2] = 0;
148 pps_fbase.tv_sec = pps_fbase.tv_nsec = 0;
149 pps_freq = 0;
150}
151
152/* Decrease pps_valid to indicate that another second has passed since
153 * the last PPS signal. When it reaches 0, indicate that PPS signal is
154 * missing.
155 */
156static inline void pps_dec_valid(void)
157{
158 if (pps_valid > 0)
159 pps_valid--;
160 else {
161 time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
162 STA_PPSWANDER | STA_PPSERROR);
163 pps_clear();
164 }
165}
166
167static inline void pps_set_freq(s64 freq)
168{
169 pps_freq = freq;
170}
171
172static inline int is_error_status(int status)
173{
174 return (status & (STA_UNSYNC|STA_CLOCKERR))
175 /* PPS signal lost when either PPS time or
176 * PPS frequency synchronization requested
177 */
178 || ((status & (STA_PPSFREQ|STA_PPSTIME))
179 && !(status & STA_PPSSIGNAL))
180 /* PPS jitter exceeded when
181 * PPS time synchronization requested */
182 || ((status & (STA_PPSTIME|STA_PPSJITTER))
183 == (STA_PPSTIME|STA_PPSJITTER))
184 /* PPS wander exceeded or calibration error when
185 * PPS frequency synchronization requested
186 */
187 || ((status & STA_PPSFREQ)
188 && (status & (STA_PPSWANDER|STA_PPSERROR)));
189}
190
191static inline void pps_fill_timex(struct timex *txc)
192{
193 txc->ppsfreq = shift_right((pps_freq >> PPM_SCALE_INV_SHIFT) *
194 PPM_SCALE_INV, NTP_SCALE_SHIFT);
195 txc->jitter = pps_jitter;
196 if (!(time_status & STA_NANO))
197 txc->jitter /= NSEC_PER_USEC;
198 txc->shift = pps_shift;
199 txc->stabil = pps_stabil;
200 txc->jitcnt = pps_jitcnt;
201 txc->calcnt = pps_calcnt;
202 txc->errcnt = pps_errcnt;
203 txc->stbcnt = pps_stbcnt;
204}
205
206#else /* !CONFIG_NTP_PPS */
207
208static inline s64 ntp_offset_chunk(s64 offset)
209{
210 return shift_right(offset, SHIFT_PLL + time_constant);
211}
212
213static inline void pps_reset_freq_interval(void) {}
214static inline void pps_clear(void) {}
215static inline void pps_dec_valid(void) {}
216static inline void pps_set_freq(s64 freq) {}
217
218static inline int is_error_status(int status)
219{
220 return status & (STA_UNSYNC|STA_CLOCKERR);
221}
222
223static inline void pps_fill_timex(struct timex *txc)
224{
225 /* PPS is not implemented, so these are zero */
226 txc->ppsfreq = 0;
227 txc->jitter = 0;
228 txc->shift = 0;
229 txc->stabil = 0;
230 txc->jitcnt = 0;
231 txc->calcnt = 0;
232 txc->errcnt = 0;
233 txc->stbcnt = 0;
234}
235
236#endif /* CONFIG_NTP_PPS */
237
238
239/**
240 * ntp_synced - Returns 1 if the NTP status is not UNSYNC
241 *
242 */
243static inline int ntp_synced(void)
244{
245 return !(time_status & STA_UNSYNC);
246}
247
248
249/*
250 * NTP methods:
251 */
252
253/*
254 * Update (tick_length, tick_length_base, tick_nsec), based
255 * on (tick_usec, ntp_tick_adj, time_freq):
256 */
257static void ntp_update_frequency(void)
258{
259 u64 second_length;
260 u64 new_base;
261
262 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
263 << NTP_SCALE_SHIFT;
264
265 second_length += ntp_tick_adj;
266 second_length += time_freq;
267
268 tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT;
269 new_base = div_u64(second_length, NTP_INTERVAL_FREQ);
270
271 /*
272 * Don't wait for the next second_overflow, apply
273 * the change to the tick length immediately:
274 */
275 tick_length += new_base - tick_length_base;
276 tick_length_base = new_base;
277}
278
279static inline s64 ntp_update_offset_fll(s64 offset64, long secs)
280{
281 time_status &= ~STA_MODE;
282
283 if (secs < MINSEC)
284 return 0;
285
286 if (!(time_status & STA_FLL) && (secs <= MAXSEC))
287 return 0;
288
289 time_status |= STA_MODE;
290
291 return div64_long(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
292}
293
294static void ntp_update_offset(long offset)
295{
296 s64 freq_adj;
297 s64 offset64;
298 long secs;
299
300 if (!(time_status & STA_PLL))
301 return;
302
303 if (!(time_status & STA_NANO)) {
304 /* Make sure the multiplication below won't overflow */
305 offset = clamp(offset, -USEC_PER_SEC, USEC_PER_SEC);
306 offset *= NSEC_PER_USEC;
307 }
308
309 /*
310 * Scale the phase adjustment and
311 * clamp to the operating range.
312 */
313 offset = clamp(offset, -MAXPHASE, MAXPHASE);
314
315 /*
316 * Select how the frequency is to be controlled
317 * and in which mode (PLL or FLL).
318 */
319 secs = (long)(__ktime_get_real_seconds() - time_reftime);
320 if (unlikely(time_status & STA_FREQHOLD))
321 secs = 0;
322
323 time_reftime = __ktime_get_real_seconds();
324
325 offset64 = offset;
326 freq_adj = ntp_update_offset_fll(offset64, secs);
327
328 /*
329 * Clamp update interval to reduce PLL gain with low
330 * sampling rate (e.g. intermittent network connection)
331 * to avoid instability.
332 */
333 if (unlikely(secs > 1 << (SHIFT_PLL + 1 + time_constant)))
334 secs = 1 << (SHIFT_PLL + 1 + time_constant);
335
336 freq_adj += (offset64 * secs) <<
337 (NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant));
338
339 freq_adj = min(freq_adj + time_freq, MAXFREQ_SCALED);
340
341 time_freq = max(freq_adj, -MAXFREQ_SCALED);
342
343 time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
344}
345
346/**
347 * ntp_clear - Clears the NTP state variables
348 */
349void ntp_clear(void)
350{
351 time_adjust = 0; /* stop active adjtime() */
352 time_status |= STA_UNSYNC;
353 time_maxerror = NTP_PHASE_LIMIT;
354 time_esterror = NTP_PHASE_LIMIT;
355
356 ntp_update_frequency();
357
358 tick_length = tick_length_base;
359 time_offset = 0;
360
361 ntp_next_leap_sec = TIME64_MAX;
362 /* Clear PPS state variables */
363 pps_clear();
364}
365
366
367u64 ntp_tick_length(void)
368{
369 return tick_length;
370}
371
372/**
373 * ntp_get_next_leap - Returns the next leapsecond in CLOCK_REALTIME ktime_t
374 *
375 * Provides the time of the next leapsecond against CLOCK_REALTIME in
376 * a ktime_t format. Returns KTIME_MAX if no leapsecond is pending.
377 */
378ktime_t ntp_get_next_leap(void)
379{
380 ktime_t ret;
381
382 if ((time_state == TIME_INS) && (time_status & STA_INS))
383 return ktime_set(ntp_next_leap_sec, 0);
384 ret.tv64 = KTIME_MAX;
385 return ret;
386}
387
388/*
389 * this routine handles the overflow of the microsecond field
390 *
391 * The tricky bits of code to handle the accurate clock support
392 * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
393 * They were originally developed for SUN and DEC kernels.
394 * All the kudos should go to Dave for this stuff.
395 *
396 * Also handles leap second processing, and returns leap offset
397 */
398int second_overflow(time64_t secs)
399{
400 s64 delta;
401 int leap = 0;
402 s32 rem;
403
404 /*
405 * Leap second processing. If in leap-insert state at the end of the
406 * day, the system clock is set back one second; if in leap-delete
407 * state, the system clock is set ahead one second.
408 */
409 switch (time_state) {
410 case TIME_OK:
411 if (time_status & STA_INS) {
412 time_state = TIME_INS;
413 div_s64_rem(secs, SECS_PER_DAY, &rem);
414 ntp_next_leap_sec = secs + SECS_PER_DAY - rem;
415 } else if (time_status & STA_DEL) {
416 time_state = TIME_DEL;
417 div_s64_rem(secs + 1, SECS_PER_DAY, &rem);
418 ntp_next_leap_sec = secs + SECS_PER_DAY - rem;
419 }
420 break;
421 case TIME_INS:
422 if (!(time_status & STA_INS)) {
423 ntp_next_leap_sec = TIME64_MAX;
424 time_state = TIME_OK;
425 } else if (secs == ntp_next_leap_sec) {
426 leap = -1;
427 time_state = TIME_OOP;
428 printk(KERN_NOTICE
429 "Clock: inserting leap second 23:59:60 UTC\n");
430 }
431 break;
432 case TIME_DEL:
433 if (!(time_status & STA_DEL)) {
434 ntp_next_leap_sec = TIME64_MAX;
435 time_state = TIME_OK;
436 } else if (secs == ntp_next_leap_sec) {
437 leap = 1;
438 ntp_next_leap_sec = TIME64_MAX;
439 time_state = TIME_WAIT;
440 printk(KERN_NOTICE
441 "Clock: deleting leap second 23:59:59 UTC\n");
442 }
443 break;
444 case TIME_OOP:
445 ntp_next_leap_sec = TIME64_MAX;
446 time_state = TIME_WAIT;
447 break;
448 case TIME_WAIT:
449 if (!(time_status & (STA_INS | STA_DEL)))
450 time_state = TIME_OK;
451 break;
452 }
453
454
455 /* Bump the maxerror field */
456 time_maxerror += MAXFREQ / NSEC_PER_USEC;
457 if (time_maxerror > NTP_PHASE_LIMIT) {
458 time_maxerror = NTP_PHASE_LIMIT;
459 time_status |= STA_UNSYNC;
460 }
461
462 /* Compute the phase adjustment for the next second */
463 tick_length = tick_length_base;
464
465 delta = ntp_offset_chunk(time_offset);
466 time_offset -= delta;
467 tick_length += delta;
468
469 /* Check PPS signal */
470 pps_dec_valid();
471
472 if (!time_adjust)
473 goto out;
474
475 if (time_adjust > MAX_TICKADJ) {
476 time_adjust -= MAX_TICKADJ;
477 tick_length += MAX_TICKADJ_SCALED;
478 goto out;
479 }
480
481 if (time_adjust < -MAX_TICKADJ) {
482 time_adjust += MAX_TICKADJ;
483 tick_length -= MAX_TICKADJ_SCALED;
484 goto out;
485 }
486
487 tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)
488 << NTP_SCALE_SHIFT;
489 time_adjust = 0;
490
491out:
492 return leap;
493}
494
495#ifdef CONFIG_GENERIC_CMOS_UPDATE
496int __weak update_persistent_clock(struct timespec now)
497{
498 return -ENODEV;
499}
500
501int __weak update_persistent_clock64(struct timespec64 now64)
502{
503 struct timespec now;
504
505 now = timespec64_to_timespec(now64);
506 return update_persistent_clock(now);
507}
508#endif
509
510#if defined(CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC)
511static void sync_cmos_clock(struct work_struct *work);
512
513static DECLARE_DELAYED_WORK(sync_cmos_work, sync_cmos_clock);
514
515static void sync_cmos_clock(struct work_struct *work)
516{
517 struct timespec64 now;
518 struct timespec64 next;
519 int fail = 1;
520
521 /*
522 * If we have an externally synchronized Linux clock, then update
523 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
524 * called as close as possible to 500 ms before the new second starts.
525 * This code is run on a timer. If the clock is set, that timer
526 * may not expire at the correct time. Thus, we adjust...
527 * We want the clock to be within a couple of ticks from the target.
528 */
529 if (!ntp_synced()) {
530 /*
531 * Not synced, exit, do not restart a timer (if one is
532 * running, let it run out).
533 */
534 return;
535 }
536
537 getnstimeofday64(&now);
538 if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec * 5) {
539 struct timespec64 adjust = now;
540
541 fail = -ENODEV;
542 if (persistent_clock_is_local)
543 adjust.tv_sec -= (sys_tz.tz_minuteswest * 60);
544#ifdef CONFIG_GENERIC_CMOS_UPDATE
545 fail = update_persistent_clock64(adjust);
546#endif
547
548#ifdef CONFIG_RTC_SYSTOHC
549 if (fail == -ENODEV)
550 fail = rtc_set_ntp_time(adjust);
551#endif
552 }
553
554 next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec - (TICK_NSEC / 2);
555 if (next.tv_nsec <= 0)
556 next.tv_nsec += NSEC_PER_SEC;
557
558 if (!fail || fail == -ENODEV)
559 next.tv_sec = 659;
560 else
561 next.tv_sec = 0;
562
563 if (next.tv_nsec >= NSEC_PER_SEC) {
564 next.tv_sec++;
565 next.tv_nsec -= NSEC_PER_SEC;
566 }
567 queue_delayed_work(system_power_efficient_wq,
568 &sync_cmos_work, timespec64_to_jiffies(&next));
569}
570
571void ntp_notify_cmos_timer(void)
572{
573 queue_delayed_work(system_power_efficient_wq, &sync_cmos_work, 0);
574}
575
576#else
577void ntp_notify_cmos_timer(void) { }
578#endif
579
580
581/*
582 * Propagate a new txc->status value into the NTP state:
583 */
584static inline void process_adj_status(struct timex *txc, struct timespec64 *ts)
585{
586 if ((time_status & STA_PLL) && !(txc->status & STA_PLL)) {
587 time_state = TIME_OK;
588 time_status = STA_UNSYNC;
589 ntp_next_leap_sec = TIME64_MAX;
590 /* restart PPS frequency calibration */
591 pps_reset_freq_interval();
592 }
593
594 /*
595 * If we turn on PLL adjustments then reset the
596 * reference time to current time.
597 */
598 if (!(time_status & STA_PLL) && (txc->status & STA_PLL))
599 time_reftime = __ktime_get_real_seconds();
600
601 /* only set allowed bits */
602 time_status &= STA_RONLY;
603 time_status |= txc->status & ~STA_RONLY;
604}
605
606
607static inline void process_adjtimex_modes(struct timex *txc,
608 struct timespec64 *ts,
609 s32 *time_tai)
610{
611 if (txc->modes & ADJ_STATUS)
612 process_adj_status(txc, ts);
613
614 if (txc->modes & ADJ_NANO)
615 time_status |= STA_NANO;
616
617 if (txc->modes & ADJ_MICRO)
618 time_status &= ~STA_NANO;
619
620 if (txc->modes & ADJ_FREQUENCY) {
621 time_freq = txc->freq * PPM_SCALE;
622 time_freq = min(time_freq, MAXFREQ_SCALED);
623 time_freq = max(time_freq, -MAXFREQ_SCALED);
624 /* update pps_freq */
625 pps_set_freq(time_freq);
626 }
627
628 if (txc->modes & ADJ_MAXERROR)
629 time_maxerror = txc->maxerror;
630
631 if (txc->modes & ADJ_ESTERROR)
632 time_esterror = txc->esterror;
633
634 if (txc->modes & ADJ_TIMECONST) {
635 time_constant = txc->constant;
636 if (!(time_status & STA_NANO))
637 time_constant += 4;
638 time_constant = min(time_constant, (long)MAXTC);
639 time_constant = max(time_constant, 0l);
640 }
641
642 if (txc->modes & ADJ_TAI && txc->constant > 0)
643 *time_tai = txc->constant;
644
645 if (txc->modes & ADJ_OFFSET)
646 ntp_update_offset(txc->offset);
647
648 if (txc->modes & ADJ_TICK)
649 tick_usec = txc->tick;
650
651 if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET))
652 ntp_update_frequency();
653}
654
655
656
657/**
658 * ntp_validate_timex - Ensures the timex is ok for use in do_adjtimex
659 */
660int ntp_validate_timex(struct timex *txc)
661{
662 if (txc->modes & ADJ_ADJTIME) {
663 /* singleshot must not be used with any other mode bits */
664 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
665 return -EINVAL;
666 if (!(txc->modes & ADJ_OFFSET_READONLY) &&
667 !capable(CAP_SYS_TIME))
668 return -EPERM;
669 } else {
670 /* In order to modify anything, you gotta be super-user! */
671 if (txc->modes && !capable(CAP_SYS_TIME))
672 return -EPERM;
673 /*
674 * if the quartz is off by more than 10% then
675 * something is VERY wrong!
676 */
677 if (txc->modes & ADJ_TICK &&
678 (txc->tick < 900000/USER_HZ ||
679 txc->tick > 1100000/USER_HZ))
680 return -EINVAL;
681 }
682
683 if (txc->modes & ADJ_SETOFFSET) {
684 /* In order to inject time, you gotta be super-user! */
685 if (!capable(CAP_SYS_TIME))
686 return -EPERM;
687
688 if (txc->modes & ADJ_NANO) {
689 struct timespec ts;
690
691 ts.tv_sec = txc->time.tv_sec;
692 ts.tv_nsec = txc->time.tv_usec;
693 if (!timespec_inject_offset_valid(&ts))
694 return -EINVAL;
695
696 } else {
697 if (!timeval_inject_offset_valid(&txc->time))
698 return -EINVAL;
699 }
700 }
701
702 /*
703 * Check for potential multiplication overflows that can
704 * only happen on 64-bit systems:
705 */
706 if ((txc->modes & ADJ_FREQUENCY) && (BITS_PER_LONG == 64)) {
707 if (LLONG_MIN / PPM_SCALE > txc->freq)
708 return -EINVAL;
709 if (LLONG_MAX / PPM_SCALE < txc->freq)
710 return -EINVAL;
711 }
712
713 return 0;
714}
715
716
717/*
718 * adjtimex mainly allows reading (and writing, if superuser) of
719 * kernel time-keeping variables. used by xntpd.
720 */
721int __do_adjtimex(struct timex *txc, struct timespec64 *ts, s32 *time_tai)
722{
723 int result;
724
725 if (txc->modes & ADJ_ADJTIME) {
726 long save_adjust = time_adjust;
727
728 if (!(txc->modes & ADJ_OFFSET_READONLY)) {
729 /* adjtime() is independent from ntp_adjtime() */
730 time_adjust = txc->offset;
731 ntp_update_frequency();
732 }
733 txc->offset = save_adjust;
734 } else {
735
736 /* If there are input parameters, then process them: */
737 if (txc->modes)
738 process_adjtimex_modes(txc, ts, time_tai);
739
740 txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
741 NTP_SCALE_SHIFT);
742 if (!(time_status & STA_NANO))
743 txc->offset /= NSEC_PER_USEC;
744 }
745
746 result = time_state; /* mostly `TIME_OK' */
747 /* check for errors */
748 if (is_error_status(time_status))
749 result = TIME_ERROR;
750
751 txc->freq = shift_right((time_freq >> PPM_SCALE_INV_SHIFT) *
752 PPM_SCALE_INV, NTP_SCALE_SHIFT);
753 txc->maxerror = time_maxerror;
754 txc->esterror = time_esterror;
755 txc->status = time_status;
756 txc->constant = time_constant;
757 txc->precision = 1;
758 txc->tolerance = MAXFREQ_SCALED / PPM_SCALE;
759 txc->tick = tick_usec;
760 txc->tai = *time_tai;
761
762 /* fill PPS status fields */
763 pps_fill_timex(txc);
764
765 txc->time.tv_sec = (time_t)ts->tv_sec;
766 txc->time.tv_usec = ts->tv_nsec;
767 if (!(time_status & STA_NANO))
768 txc->time.tv_usec /= NSEC_PER_USEC;
769
770 /* Handle leapsec adjustments */
771 if (unlikely(ts->tv_sec >= ntp_next_leap_sec)) {
772 if ((time_state == TIME_INS) && (time_status & STA_INS)) {
773 result = TIME_OOP;
774 txc->tai++;
775 txc->time.tv_sec--;
776 }
777 if ((time_state == TIME_DEL) && (time_status & STA_DEL)) {
778 result = TIME_WAIT;
779 txc->tai--;
780 txc->time.tv_sec++;
781 }
782 if ((time_state == TIME_OOP) &&
783 (ts->tv_sec == ntp_next_leap_sec)) {
784 result = TIME_WAIT;
785 }
786 }
787
788 return result;
789}
790
791#ifdef CONFIG_NTP_PPS
792
793/* actually struct pps_normtime is good old struct timespec, but it is
794 * semantically different (and it is the reason why it was invented):
795 * pps_normtime.nsec has a range of ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ]
796 * while timespec.tv_nsec has a range of [0, NSEC_PER_SEC) */
797struct pps_normtime {
798 s64 sec; /* seconds */
799 long nsec; /* nanoseconds */
800};
801
802/* normalize the timestamp so that nsec is in the
803 ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ] interval */
804static inline struct pps_normtime pps_normalize_ts(struct timespec64 ts)
805{
806 struct pps_normtime norm = {
807 .sec = ts.tv_sec,
808 .nsec = ts.tv_nsec
809 };
810
811 if (norm.nsec > (NSEC_PER_SEC >> 1)) {
812 norm.nsec -= NSEC_PER_SEC;
813 norm.sec++;
814 }
815
816 return norm;
817}
818
819/* get current phase correction and jitter */
820static inline long pps_phase_filter_get(long *jitter)
821{
822 *jitter = pps_tf[0] - pps_tf[1];
823 if (*jitter < 0)
824 *jitter = -*jitter;
825
826 /* TODO: test various filters */
827 return pps_tf[0];
828}
829
830/* add the sample to the phase filter */
831static inline void pps_phase_filter_add(long err)
832{
833 pps_tf[2] = pps_tf[1];
834 pps_tf[1] = pps_tf[0];
835 pps_tf[0] = err;
836}
837
838/* decrease frequency calibration interval length.
839 * It is halved after four consecutive unstable intervals.
840 */
841static inline void pps_dec_freq_interval(void)
842{
843 if (--pps_intcnt <= -PPS_INTCOUNT) {
844 pps_intcnt = -PPS_INTCOUNT;
845 if (pps_shift > PPS_INTMIN) {
846 pps_shift--;
847 pps_intcnt = 0;
848 }
849 }
850}
851
852/* increase frequency calibration interval length.
853 * It is doubled after four consecutive stable intervals.
854 */
855static inline void pps_inc_freq_interval(void)
856{
857 if (++pps_intcnt >= PPS_INTCOUNT) {
858 pps_intcnt = PPS_INTCOUNT;
859 if (pps_shift < PPS_INTMAX) {
860 pps_shift++;
861 pps_intcnt = 0;
862 }
863 }
864}
865
866/* update clock frequency based on MONOTONIC_RAW clock PPS signal
867 * timestamps
868 *
869 * At the end of the calibration interval the difference between the
870 * first and last MONOTONIC_RAW clock timestamps divided by the length
871 * of the interval becomes the frequency update. If the interval was
872 * too long, the data are discarded.
873 * Returns the difference between old and new frequency values.
874 */
875static long hardpps_update_freq(struct pps_normtime freq_norm)
876{
877 long delta, delta_mod;
878 s64 ftemp;
879
880 /* check if the frequency interval was too long */
881 if (freq_norm.sec > (2 << pps_shift)) {
882 time_status |= STA_PPSERROR;
883 pps_errcnt++;
884 pps_dec_freq_interval();
885 printk_deferred(KERN_ERR
886 "hardpps: PPSERROR: interval too long - %lld s\n",
887 freq_norm.sec);
888 return 0;
889 }
890
891 /* here the raw frequency offset and wander (stability) is
892 * calculated. If the wander is less than the wander threshold
893 * the interval is increased; otherwise it is decreased.
894 */
895 ftemp = div_s64(((s64)(-freq_norm.nsec)) << NTP_SCALE_SHIFT,
896 freq_norm.sec);
897 delta = shift_right(ftemp - pps_freq, NTP_SCALE_SHIFT);
898 pps_freq = ftemp;
899 if (delta > PPS_MAXWANDER || delta < -PPS_MAXWANDER) {
900 printk_deferred(KERN_WARNING
901 "hardpps: PPSWANDER: change=%ld\n", delta);
902 time_status |= STA_PPSWANDER;
903 pps_stbcnt++;
904 pps_dec_freq_interval();
905 } else { /* good sample */
906 pps_inc_freq_interval();
907 }
908
909 /* the stability metric is calculated as the average of recent
910 * frequency changes, but is used only for performance
911 * monitoring
912 */
913 delta_mod = delta;
914 if (delta_mod < 0)
915 delta_mod = -delta_mod;
916 pps_stabil += (div_s64(((s64)delta_mod) <<
917 (NTP_SCALE_SHIFT - SHIFT_USEC),
918 NSEC_PER_USEC) - pps_stabil) >> PPS_INTMIN;
919
920 /* if enabled, the system clock frequency is updated */
921 if ((time_status & STA_PPSFREQ) != 0 &&
922 (time_status & STA_FREQHOLD) == 0) {
923 time_freq = pps_freq;
924 ntp_update_frequency();
925 }
926
927 return delta;
928}
929
930/* correct REALTIME clock phase error against PPS signal */
931static void hardpps_update_phase(long error)
932{
933 long correction = -error;
934 long jitter;
935
936 /* add the sample to the median filter */
937 pps_phase_filter_add(correction);
938 correction = pps_phase_filter_get(&jitter);
939
940 /* Nominal jitter is due to PPS signal noise. If it exceeds the
941 * threshold, the sample is discarded; otherwise, if so enabled,
942 * the time offset is updated.
943 */
944 if (jitter > (pps_jitter << PPS_POPCORN)) {
945 printk_deferred(KERN_WARNING
946 "hardpps: PPSJITTER: jitter=%ld, limit=%ld\n",
947 jitter, (pps_jitter << PPS_POPCORN));
948 time_status |= STA_PPSJITTER;
949 pps_jitcnt++;
950 } else if (time_status & STA_PPSTIME) {
951 /* correct the time using the phase offset */
952 time_offset = div_s64(((s64)correction) << NTP_SCALE_SHIFT,
953 NTP_INTERVAL_FREQ);
954 /* cancel running adjtime() */
955 time_adjust = 0;
956 }
957 /* update jitter */
958 pps_jitter += (jitter - pps_jitter) >> PPS_INTMIN;
959}
960
961/*
962 * __hardpps() - discipline CPU clock oscillator to external PPS signal
963 *
964 * This routine is called at each PPS signal arrival in order to
965 * discipline the CPU clock oscillator to the PPS signal. It takes two
966 * parameters: REALTIME and MONOTONIC_RAW clock timestamps. The former
967 * is used to correct clock phase error and the latter is used to
968 * correct the frequency.
969 *
970 * This code is based on David Mills's reference nanokernel
971 * implementation. It was mostly rewritten but keeps the same idea.
972 */
973void __hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
974{
975 struct pps_normtime pts_norm, freq_norm;
976
977 pts_norm = pps_normalize_ts(*phase_ts);
978
979 /* clear the error bits, they will be set again if needed */
980 time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
981
982 /* indicate signal presence */
983 time_status |= STA_PPSSIGNAL;
984 pps_valid = PPS_VALID;
985
986 /* when called for the first time,
987 * just start the frequency interval */
988 if (unlikely(pps_fbase.tv_sec == 0)) {
989 pps_fbase = *raw_ts;
990 return;
991 }
992
993 /* ok, now we have a base for frequency calculation */
994 freq_norm = pps_normalize_ts(timespec64_sub(*raw_ts, pps_fbase));
995
996 /* check that the signal is in the range
997 * [1s - MAXFREQ us, 1s + MAXFREQ us], otherwise reject it */
998 if ((freq_norm.sec == 0) ||
999 (freq_norm.nsec > MAXFREQ * freq_norm.sec) ||
1000 (freq_norm.nsec < -MAXFREQ * freq_norm.sec)) {
1001 time_status |= STA_PPSJITTER;
1002 /* restart the frequency calibration interval */
1003 pps_fbase = *raw_ts;
1004 printk_deferred(KERN_ERR "hardpps: PPSJITTER: bad pulse\n");
1005 return;
1006 }
1007
1008 /* signal is ok */
1009
1010 /* check if the current frequency interval is finished */
1011 if (freq_norm.sec >= (1 << pps_shift)) {
1012 pps_calcnt++;
1013 /* restart the frequency calibration interval */
1014 pps_fbase = *raw_ts;
1015 hardpps_update_freq(freq_norm);
1016 }
1017
1018 hardpps_update_phase(pts_norm.nsec);
1019
1020}
1021#endif /* CONFIG_NTP_PPS */
1022
1023static int __init ntp_tick_adj_setup(char *str)
1024{
1025 int rc = kstrtol(str, 0, (long *)&ntp_tick_adj);
1026
1027 if (rc)
1028 return rc;
1029 ntp_tick_adj <<= NTP_SCALE_SHIFT;
1030
1031 return 1;
1032}
1033
1034__setup("ntp_tick_adj=", ntp_tick_adj_setup);
1035
1036void __init ntp_init(void)
1037{
1038 ntp_clear();
1039}
1/*
2 * NTP state machine interfaces and logic.
3 *
4 * This code was mainly moved from kernel/timer.c and kernel/time.c
5 * Please see those files for relevant copyright info and historical
6 * changelogs.
7 */
8#include <linux/capability.h>
9#include <linux/clocksource.h>
10#include <linux/workqueue.h>
11#include <linux/hrtimer.h>
12#include <linux/jiffies.h>
13#include <linux/math64.h>
14#include <linux/timex.h>
15#include <linux/time.h>
16#include <linux/mm.h>
17#include <linux/module.h>
18
19#include "tick-internal.h"
20
21/*
22 * NTP timekeeping variables:
23 */
24
25/* USER_HZ period (usecs): */
26unsigned long tick_usec = TICK_USEC;
27
28/* ACTHZ period (nsecs): */
29unsigned long tick_nsec;
30
31u64 tick_length;
32static u64 tick_length_base;
33
34static struct hrtimer leap_timer;
35
36#define MAX_TICKADJ 500LL /* usecs */
37#define MAX_TICKADJ_SCALED \
38 (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
39
40/*
41 * phase-lock loop variables
42 */
43
44/*
45 * clock synchronization status
46 *
47 * (TIME_ERROR prevents overwriting the CMOS clock)
48 */
49static int time_state = TIME_OK;
50
51/* clock status bits: */
52int time_status = STA_UNSYNC;
53
54/* TAI offset (secs): */
55static long time_tai;
56
57/* time adjustment (nsecs): */
58static s64 time_offset;
59
60/* pll time constant: */
61static long time_constant = 2;
62
63/* maximum error (usecs): */
64static long time_maxerror = NTP_PHASE_LIMIT;
65
66/* estimated error (usecs): */
67static long time_esterror = NTP_PHASE_LIMIT;
68
69/* frequency offset (scaled nsecs/secs): */
70static s64 time_freq;
71
72/* time at last adjustment (secs): */
73static long time_reftime;
74
75static long time_adjust;
76
77/* constant (boot-param configurable) NTP tick adjustment (upscaled) */
78static s64 ntp_tick_adj;
79
80#ifdef CONFIG_NTP_PPS
81
82/*
83 * The following variables are used when a pulse-per-second (PPS) signal
84 * is available. They establish the engineering parameters of the clock
85 * discipline loop when controlled by the PPS signal.
86 */
87#define PPS_VALID 10 /* PPS signal watchdog max (s) */
88#define PPS_POPCORN 4 /* popcorn spike threshold (shift) */
89#define PPS_INTMIN 2 /* min freq interval (s) (shift) */
90#define PPS_INTMAX 8 /* max freq interval (s) (shift) */
91#define PPS_INTCOUNT 4 /* number of consecutive good intervals to
92 increase pps_shift or consecutive bad
93 intervals to decrease it */
94#define PPS_MAXWANDER 100000 /* max PPS freq wander (ns/s) */
95
96static int pps_valid; /* signal watchdog counter */
97static long pps_tf[3]; /* phase median filter */
98static long pps_jitter; /* current jitter (ns) */
99static struct timespec pps_fbase; /* beginning of the last freq interval */
100static int pps_shift; /* current interval duration (s) (shift) */
101static int pps_intcnt; /* interval counter */
102static s64 pps_freq; /* frequency offset (scaled ns/s) */
103static long pps_stabil; /* current stability (scaled ns/s) */
104
105/*
106 * PPS signal quality monitors
107 */
108static long pps_calcnt; /* calibration intervals */
109static long pps_jitcnt; /* jitter limit exceeded */
110static long pps_stbcnt; /* stability limit exceeded */
111static long pps_errcnt; /* calibration errors */
112
113
114/* PPS kernel consumer compensates the whole phase error immediately.
115 * Otherwise, reduce the offset by a fixed factor times the time constant.
116 */
117static inline s64 ntp_offset_chunk(s64 offset)
118{
119 if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL)
120 return offset;
121 else
122 return shift_right(offset, SHIFT_PLL + time_constant);
123}
124
125static inline void pps_reset_freq_interval(void)
126{
127 /* the PPS calibration interval may end
128 surprisingly early */
129 pps_shift = PPS_INTMIN;
130 pps_intcnt = 0;
131}
132
133/**
134 * pps_clear - Clears the PPS state variables
135 *
136 * Must be called while holding a write on the xtime_lock
137 */
138static inline void pps_clear(void)
139{
140 pps_reset_freq_interval();
141 pps_tf[0] = 0;
142 pps_tf[1] = 0;
143 pps_tf[2] = 0;
144 pps_fbase.tv_sec = pps_fbase.tv_nsec = 0;
145 pps_freq = 0;
146}
147
148/* Decrease pps_valid to indicate that another second has passed since
149 * the last PPS signal. When it reaches 0, indicate that PPS signal is
150 * missing.
151 *
152 * Must be called while holding a write on the xtime_lock
153 */
154static inline void pps_dec_valid(void)
155{
156 if (pps_valid > 0)
157 pps_valid--;
158 else {
159 time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
160 STA_PPSWANDER | STA_PPSERROR);
161 pps_clear();
162 }
163}
164
165static inline void pps_set_freq(s64 freq)
166{
167 pps_freq = freq;
168}
169
170static inline int is_error_status(int status)
171{
172 return (time_status & (STA_UNSYNC|STA_CLOCKERR))
173 /* PPS signal lost when either PPS time or
174 * PPS frequency synchronization requested
175 */
176 || ((time_status & (STA_PPSFREQ|STA_PPSTIME))
177 && !(time_status & STA_PPSSIGNAL))
178 /* PPS jitter exceeded when
179 * PPS time synchronization requested */
180 || ((time_status & (STA_PPSTIME|STA_PPSJITTER))
181 == (STA_PPSTIME|STA_PPSJITTER))
182 /* PPS wander exceeded or calibration error when
183 * PPS frequency synchronization requested
184 */
185 || ((time_status & STA_PPSFREQ)
186 && (time_status & (STA_PPSWANDER|STA_PPSERROR)));
187}
188
189static inline void pps_fill_timex(struct timex *txc)
190{
191 txc->ppsfreq = shift_right((pps_freq >> PPM_SCALE_INV_SHIFT) *
192 PPM_SCALE_INV, NTP_SCALE_SHIFT);
193 txc->jitter = pps_jitter;
194 if (!(time_status & STA_NANO))
195 txc->jitter /= NSEC_PER_USEC;
196 txc->shift = pps_shift;
197 txc->stabil = pps_stabil;
198 txc->jitcnt = pps_jitcnt;
199 txc->calcnt = pps_calcnt;
200 txc->errcnt = pps_errcnt;
201 txc->stbcnt = pps_stbcnt;
202}
203
204#else /* !CONFIG_NTP_PPS */
205
206static inline s64 ntp_offset_chunk(s64 offset)
207{
208 return shift_right(offset, SHIFT_PLL + time_constant);
209}
210
211static inline void pps_reset_freq_interval(void) {}
212static inline void pps_clear(void) {}
213static inline void pps_dec_valid(void) {}
214static inline void pps_set_freq(s64 freq) {}
215
216static inline int is_error_status(int status)
217{
218 return status & (STA_UNSYNC|STA_CLOCKERR);
219}
220
221static inline void pps_fill_timex(struct timex *txc)
222{
223 /* PPS is not implemented, so these are zero */
224 txc->ppsfreq = 0;
225 txc->jitter = 0;
226 txc->shift = 0;
227 txc->stabil = 0;
228 txc->jitcnt = 0;
229 txc->calcnt = 0;
230 txc->errcnt = 0;
231 txc->stbcnt = 0;
232}
233
234#endif /* CONFIG_NTP_PPS */
235
236/*
237 * NTP methods:
238 */
239
240/*
241 * Update (tick_length, tick_length_base, tick_nsec), based
242 * on (tick_usec, ntp_tick_adj, time_freq):
243 */
244static void ntp_update_frequency(void)
245{
246 u64 second_length;
247 u64 new_base;
248
249 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
250 << NTP_SCALE_SHIFT;
251
252 second_length += ntp_tick_adj;
253 second_length += time_freq;
254
255 tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT;
256 new_base = div_u64(second_length, NTP_INTERVAL_FREQ);
257
258 /*
259 * Don't wait for the next second_overflow, apply
260 * the change to the tick length immediately:
261 */
262 tick_length += new_base - tick_length_base;
263 tick_length_base = new_base;
264}
265
266static inline s64 ntp_update_offset_fll(s64 offset64, long secs)
267{
268 time_status &= ~STA_MODE;
269
270 if (secs < MINSEC)
271 return 0;
272
273 if (!(time_status & STA_FLL) && (secs <= MAXSEC))
274 return 0;
275
276 time_status |= STA_MODE;
277
278 return div_s64(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
279}
280
281static void ntp_update_offset(long offset)
282{
283 s64 freq_adj;
284 s64 offset64;
285 long secs;
286
287 if (!(time_status & STA_PLL))
288 return;
289
290 if (!(time_status & STA_NANO))
291 offset *= NSEC_PER_USEC;
292
293 /*
294 * Scale the phase adjustment and
295 * clamp to the operating range.
296 */
297 offset = min(offset, MAXPHASE);
298 offset = max(offset, -MAXPHASE);
299
300 /*
301 * Select how the frequency is to be controlled
302 * and in which mode (PLL or FLL).
303 */
304 secs = get_seconds() - time_reftime;
305 if (unlikely(time_status & STA_FREQHOLD))
306 secs = 0;
307
308 time_reftime = get_seconds();
309
310 offset64 = offset;
311 freq_adj = ntp_update_offset_fll(offset64, secs);
312
313 /*
314 * Clamp update interval to reduce PLL gain with low
315 * sampling rate (e.g. intermittent network connection)
316 * to avoid instability.
317 */
318 if (unlikely(secs > 1 << (SHIFT_PLL + 1 + time_constant)))
319 secs = 1 << (SHIFT_PLL + 1 + time_constant);
320
321 freq_adj += (offset64 * secs) <<
322 (NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant));
323
324 freq_adj = min(freq_adj + time_freq, MAXFREQ_SCALED);
325
326 time_freq = max(freq_adj, -MAXFREQ_SCALED);
327
328 time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
329}
330
331/**
332 * ntp_clear - Clears the NTP state variables
333 *
334 * Must be called while holding a write on the xtime_lock
335 */
336void ntp_clear(void)
337{
338 time_adjust = 0; /* stop active adjtime() */
339 time_status |= STA_UNSYNC;
340 time_maxerror = NTP_PHASE_LIMIT;
341 time_esterror = NTP_PHASE_LIMIT;
342
343 ntp_update_frequency();
344
345 tick_length = tick_length_base;
346 time_offset = 0;
347
348 /* Clear PPS state variables */
349 pps_clear();
350}
351
352/*
353 * Leap second processing. If in leap-insert state at the end of the
354 * day, the system clock is set back one second; if in leap-delete
355 * state, the system clock is set ahead one second.
356 */
357static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)
358{
359 enum hrtimer_restart res = HRTIMER_NORESTART;
360
361 write_seqlock(&xtime_lock);
362
363 switch (time_state) {
364 case TIME_OK:
365 break;
366 case TIME_INS:
367 timekeeping_leap_insert(-1);
368 time_state = TIME_OOP;
369 printk(KERN_NOTICE
370 "Clock: inserting leap second 23:59:60 UTC\n");
371 hrtimer_add_expires_ns(&leap_timer, NSEC_PER_SEC);
372 res = HRTIMER_RESTART;
373 break;
374 case TIME_DEL:
375 timekeeping_leap_insert(1);
376 time_tai--;
377 time_state = TIME_WAIT;
378 printk(KERN_NOTICE
379 "Clock: deleting leap second 23:59:59 UTC\n");
380 break;
381 case TIME_OOP:
382 time_tai++;
383 time_state = TIME_WAIT;
384 /* fall through */
385 case TIME_WAIT:
386 if (!(time_status & (STA_INS | STA_DEL)))
387 time_state = TIME_OK;
388 break;
389 }
390
391 write_sequnlock(&xtime_lock);
392
393 return res;
394}
395
396/*
397 * this routine handles the overflow of the microsecond field
398 *
399 * The tricky bits of code to handle the accurate clock support
400 * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
401 * They were originally developed for SUN and DEC kernels.
402 * All the kudos should go to Dave for this stuff.
403 */
404void second_overflow(void)
405{
406 s64 delta;
407
408 /* Bump the maxerror field */
409 time_maxerror += MAXFREQ / NSEC_PER_USEC;
410 if (time_maxerror > NTP_PHASE_LIMIT) {
411 time_maxerror = NTP_PHASE_LIMIT;
412 time_status |= STA_UNSYNC;
413 }
414
415 /* Compute the phase adjustment for the next second */
416 tick_length = tick_length_base;
417
418 delta = ntp_offset_chunk(time_offset);
419 time_offset -= delta;
420 tick_length += delta;
421
422 /* Check PPS signal */
423 pps_dec_valid();
424
425 if (!time_adjust)
426 return;
427
428 if (time_adjust > MAX_TICKADJ) {
429 time_adjust -= MAX_TICKADJ;
430 tick_length += MAX_TICKADJ_SCALED;
431 return;
432 }
433
434 if (time_adjust < -MAX_TICKADJ) {
435 time_adjust += MAX_TICKADJ;
436 tick_length -= MAX_TICKADJ_SCALED;
437 return;
438 }
439
440 tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)
441 << NTP_SCALE_SHIFT;
442 time_adjust = 0;
443}
444
445#ifdef CONFIG_GENERIC_CMOS_UPDATE
446
447/* Disable the cmos update - used by virtualization and embedded */
448int no_sync_cmos_clock __read_mostly;
449
450static void sync_cmos_clock(struct work_struct *work);
451
452static DECLARE_DELAYED_WORK(sync_cmos_work, sync_cmos_clock);
453
454static void sync_cmos_clock(struct work_struct *work)
455{
456 struct timespec now, next;
457 int fail = 1;
458
459 /*
460 * If we have an externally synchronized Linux clock, then update
461 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
462 * called as close as possible to 500 ms before the new second starts.
463 * This code is run on a timer. If the clock is set, that timer
464 * may not expire at the correct time. Thus, we adjust...
465 */
466 if (!ntp_synced()) {
467 /*
468 * Not synced, exit, do not restart a timer (if one is
469 * running, let it run out).
470 */
471 return;
472 }
473
474 getnstimeofday(&now);
475 if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2)
476 fail = update_persistent_clock(now);
477
478 next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec - (TICK_NSEC / 2);
479 if (next.tv_nsec <= 0)
480 next.tv_nsec += NSEC_PER_SEC;
481
482 if (!fail)
483 next.tv_sec = 659;
484 else
485 next.tv_sec = 0;
486
487 if (next.tv_nsec >= NSEC_PER_SEC) {
488 next.tv_sec++;
489 next.tv_nsec -= NSEC_PER_SEC;
490 }
491 schedule_delayed_work(&sync_cmos_work, timespec_to_jiffies(&next));
492}
493
494static void notify_cmos_timer(void)
495{
496 if (!no_sync_cmos_clock)
497 schedule_delayed_work(&sync_cmos_work, 0);
498}
499
500#else
501static inline void notify_cmos_timer(void) { }
502#endif
503
504/*
505 * Start the leap seconds timer:
506 */
507static inline void ntp_start_leap_timer(struct timespec *ts)
508{
509 long now = ts->tv_sec;
510
511 if (time_status & STA_INS) {
512 time_state = TIME_INS;
513 now += 86400 - now % 86400;
514 hrtimer_start(&leap_timer, ktime_set(now, 0), HRTIMER_MODE_ABS);
515
516 return;
517 }
518
519 if (time_status & STA_DEL) {
520 time_state = TIME_DEL;
521 now += 86400 - (now + 1) % 86400;
522 hrtimer_start(&leap_timer, ktime_set(now, 0), HRTIMER_MODE_ABS);
523 }
524}
525
526/*
527 * Propagate a new txc->status value into the NTP state:
528 */
529static inline void process_adj_status(struct timex *txc, struct timespec *ts)
530{
531 if ((time_status & STA_PLL) && !(txc->status & STA_PLL)) {
532 time_state = TIME_OK;
533 time_status = STA_UNSYNC;
534 /* restart PPS frequency calibration */
535 pps_reset_freq_interval();
536 }
537
538 /*
539 * If we turn on PLL adjustments then reset the
540 * reference time to current time.
541 */
542 if (!(time_status & STA_PLL) && (txc->status & STA_PLL))
543 time_reftime = get_seconds();
544
545 /* only set allowed bits */
546 time_status &= STA_RONLY;
547 time_status |= txc->status & ~STA_RONLY;
548
549 switch (time_state) {
550 case TIME_OK:
551 ntp_start_leap_timer(ts);
552 break;
553 case TIME_INS:
554 case TIME_DEL:
555 time_state = TIME_OK;
556 ntp_start_leap_timer(ts);
557 case TIME_WAIT:
558 if (!(time_status & (STA_INS | STA_DEL)))
559 time_state = TIME_OK;
560 break;
561 case TIME_OOP:
562 hrtimer_restart(&leap_timer);
563 break;
564 }
565}
566/*
567 * Called with the xtime lock held, so we can access and modify
568 * all the global NTP state:
569 */
570static inline void process_adjtimex_modes(struct timex *txc, struct timespec *ts)
571{
572 if (txc->modes & ADJ_STATUS)
573 process_adj_status(txc, ts);
574
575 if (txc->modes & ADJ_NANO)
576 time_status |= STA_NANO;
577
578 if (txc->modes & ADJ_MICRO)
579 time_status &= ~STA_NANO;
580
581 if (txc->modes & ADJ_FREQUENCY) {
582 time_freq = txc->freq * PPM_SCALE;
583 time_freq = min(time_freq, MAXFREQ_SCALED);
584 time_freq = max(time_freq, -MAXFREQ_SCALED);
585 /* update pps_freq */
586 pps_set_freq(time_freq);
587 }
588
589 if (txc->modes & ADJ_MAXERROR)
590 time_maxerror = txc->maxerror;
591
592 if (txc->modes & ADJ_ESTERROR)
593 time_esterror = txc->esterror;
594
595 if (txc->modes & ADJ_TIMECONST) {
596 time_constant = txc->constant;
597 if (!(time_status & STA_NANO))
598 time_constant += 4;
599 time_constant = min(time_constant, (long)MAXTC);
600 time_constant = max(time_constant, 0l);
601 }
602
603 if (txc->modes & ADJ_TAI && txc->constant > 0)
604 time_tai = txc->constant;
605
606 if (txc->modes & ADJ_OFFSET)
607 ntp_update_offset(txc->offset);
608
609 if (txc->modes & ADJ_TICK)
610 tick_usec = txc->tick;
611
612 if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET))
613 ntp_update_frequency();
614}
615
616/*
617 * adjtimex mainly allows reading (and writing, if superuser) of
618 * kernel time-keeping variables. used by xntpd.
619 */
620int do_adjtimex(struct timex *txc)
621{
622 struct timespec ts;
623 int result;
624
625 /* Validate the data before disabling interrupts */
626 if (txc->modes & ADJ_ADJTIME) {
627 /* singleshot must not be used with any other mode bits */
628 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
629 return -EINVAL;
630 if (!(txc->modes & ADJ_OFFSET_READONLY) &&
631 !capable(CAP_SYS_TIME))
632 return -EPERM;
633 } else {
634 /* In order to modify anything, you gotta be super-user! */
635 if (txc->modes && !capable(CAP_SYS_TIME))
636 return -EPERM;
637
638 /*
639 * if the quartz is off by more than 10% then
640 * something is VERY wrong!
641 */
642 if (txc->modes & ADJ_TICK &&
643 (txc->tick < 900000/USER_HZ ||
644 txc->tick > 1100000/USER_HZ))
645 return -EINVAL;
646
647 if (txc->modes & ADJ_STATUS && time_state != TIME_OK)
648 hrtimer_cancel(&leap_timer);
649 }
650
651 if (txc->modes & ADJ_SETOFFSET) {
652 struct timespec delta;
653 delta.tv_sec = txc->time.tv_sec;
654 delta.tv_nsec = txc->time.tv_usec;
655 if (!capable(CAP_SYS_TIME))
656 return -EPERM;
657 if (!(txc->modes & ADJ_NANO))
658 delta.tv_nsec *= 1000;
659 result = timekeeping_inject_offset(&delta);
660 if (result)
661 return result;
662 }
663
664 getnstimeofday(&ts);
665
666 write_seqlock_irq(&xtime_lock);
667
668 if (txc->modes & ADJ_ADJTIME) {
669 long save_adjust = time_adjust;
670
671 if (!(txc->modes & ADJ_OFFSET_READONLY)) {
672 /* adjtime() is independent from ntp_adjtime() */
673 time_adjust = txc->offset;
674 ntp_update_frequency();
675 }
676 txc->offset = save_adjust;
677 } else {
678
679 /* If there are input parameters, then process them: */
680 if (txc->modes)
681 process_adjtimex_modes(txc, &ts);
682
683 txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
684 NTP_SCALE_SHIFT);
685 if (!(time_status & STA_NANO))
686 txc->offset /= NSEC_PER_USEC;
687 }
688
689 result = time_state; /* mostly `TIME_OK' */
690 /* check for errors */
691 if (is_error_status(time_status))
692 result = TIME_ERROR;
693
694 txc->freq = shift_right((time_freq >> PPM_SCALE_INV_SHIFT) *
695 PPM_SCALE_INV, NTP_SCALE_SHIFT);
696 txc->maxerror = time_maxerror;
697 txc->esterror = time_esterror;
698 txc->status = time_status;
699 txc->constant = time_constant;
700 txc->precision = 1;
701 txc->tolerance = MAXFREQ_SCALED / PPM_SCALE;
702 txc->tick = tick_usec;
703 txc->tai = time_tai;
704
705 /* fill PPS status fields */
706 pps_fill_timex(txc);
707
708 write_sequnlock_irq(&xtime_lock);
709
710 txc->time.tv_sec = ts.tv_sec;
711 txc->time.tv_usec = ts.tv_nsec;
712 if (!(time_status & STA_NANO))
713 txc->time.tv_usec /= NSEC_PER_USEC;
714
715 notify_cmos_timer();
716
717 return result;
718}
719
720#ifdef CONFIG_NTP_PPS
721
722/* actually struct pps_normtime is good old struct timespec, but it is
723 * semantically different (and it is the reason why it was invented):
724 * pps_normtime.nsec has a range of ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ]
725 * while timespec.tv_nsec has a range of [0, NSEC_PER_SEC) */
726struct pps_normtime {
727 __kernel_time_t sec; /* seconds */
728 long nsec; /* nanoseconds */
729};
730
731/* normalize the timestamp so that nsec is in the
732 ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ] interval */
733static inline struct pps_normtime pps_normalize_ts(struct timespec ts)
734{
735 struct pps_normtime norm = {
736 .sec = ts.tv_sec,
737 .nsec = ts.tv_nsec
738 };
739
740 if (norm.nsec > (NSEC_PER_SEC >> 1)) {
741 norm.nsec -= NSEC_PER_SEC;
742 norm.sec++;
743 }
744
745 return norm;
746}
747
748/* get current phase correction and jitter */
749static inline long pps_phase_filter_get(long *jitter)
750{
751 *jitter = pps_tf[0] - pps_tf[1];
752 if (*jitter < 0)
753 *jitter = -*jitter;
754
755 /* TODO: test various filters */
756 return pps_tf[0];
757}
758
759/* add the sample to the phase filter */
760static inline void pps_phase_filter_add(long err)
761{
762 pps_tf[2] = pps_tf[1];
763 pps_tf[1] = pps_tf[0];
764 pps_tf[0] = err;
765}
766
767/* decrease frequency calibration interval length.
768 * It is halved after four consecutive unstable intervals.
769 */
770static inline void pps_dec_freq_interval(void)
771{
772 if (--pps_intcnt <= -PPS_INTCOUNT) {
773 pps_intcnt = -PPS_INTCOUNT;
774 if (pps_shift > PPS_INTMIN) {
775 pps_shift--;
776 pps_intcnt = 0;
777 }
778 }
779}
780
781/* increase frequency calibration interval length.
782 * It is doubled after four consecutive stable intervals.
783 */
784static inline void pps_inc_freq_interval(void)
785{
786 if (++pps_intcnt >= PPS_INTCOUNT) {
787 pps_intcnt = PPS_INTCOUNT;
788 if (pps_shift < PPS_INTMAX) {
789 pps_shift++;
790 pps_intcnt = 0;
791 }
792 }
793}
794
795/* update clock frequency based on MONOTONIC_RAW clock PPS signal
796 * timestamps
797 *
798 * At the end of the calibration interval the difference between the
799 * first and last MONOTONIC_RAW clock timestamps divided by the length
800 * of the interval becomes the frequency update. If the interval was
801 * too long, the data are discarded.
802 * Returns the difference between old and new frequency values.
803 */
804static long hardpps_update_freq(struct pps_normtime freq_norm)
805{
806 long delta, delta_mod;
807 s64 ftemp;
808
809 /* check if the frequency interval was too long */
810 if (freq_norm.sec > (2 << pps_shift)) {
811 time_status |= STA_PPSERROR;
812 pps_errcnt++;
813 pps_dec_freq_interval();
814 pr_err("hardpps: PPSERROR: interval too long - %ld s\n",
815 freq_norm.sec);
816 return 0;
817 }
818
819 /* here the raw frequency offset and wander (stability) is
820 * calculated. If the wander is less than the wander threshold
821 * the interval is increased; otherwise it is decreased.
822 */
823 ftemp = div_s64(((s64)(-freq_norm.nsec)) << NTP_SCALE_SHIFT,
824 freq_norm.sec);
825 delta = shift_right(ftemp - pps_freq, NTP_SCALE_SHIFT);
826 pps_freq = ftemp;
827 if (delta > PPS_MAXWANDER || delta < -PPS_MAXWANDER) {
828 pr_warning("hardpps: PPSWANDER: change=%ld\n", delta);
829 time_status |= STA_PPSWANDER;
830 pps_stbcnt++;
831 pps_dec_freq_interval();
832 } else { /* good sample */
833 pps_inc_freq_interval();
834 }
835
836 /* the stability metric is calculated as the average of recent
837 * frequency changes, but is used only for performance
838 * monitoring
839 */
840 delta_mod = delta;
841 if (delta_mod < 0)
842 delta_mod = -delta_mod;
843 pps_stabil += (div_s64(((s64)delta_mod) <<
844 (NTP_SCALE_SHIFT - SHIFT_USEC),
845 NSEC_PER_USEC) - pps_stabil) >> PPS_INTMIN;
846
847 /* if enabled, the system clock frequency is updated */
848 if ((time_status & STA_PPSFREQ) != 0 &&
849 (time_status & STA_FREQHOLD) == 0) {
850 time_freq = pps_freq;
851 ntp_update_frequency();
852 }
853
854 return delta;
855}
856
857/* correct REALTIME clock phase error against PPS signal */
858static void hardpps_update_phase(long error)
859{
860 long correction = -error;
861 long jitter;
862
863 /* add the sample to the median filter */
864 pps_phase_filter_add(correction);
865 correction = pps_phase_filter_get(&jitter);
866
867 /* Nominal jitter is due to PPS signal noise. If it exceeds the
868 * threshold, the sample is discarded; otherwise, if so enabled,
869 * the time offset is updated.
870 */
871 if (jitter > (pps_jitter << PPS_POPCORN)) {
872 pr_warning("hardpps: PPSJITTER: jitter=%ld, limit=%ld\n",
873 jitter, (pps_jitter << PPS_POPCORN));
874 time_status |= STA_PPSJITTER;
875 pps_jitcnt++;
876 } else if (time_status & STA_PPSTIME) {
877 /* correct the time using the phase offset */
878 time_offset = div_s64(((s64)correction) << NTP_SCALE_SHIFT,
879 NTP_INTERVAL_FREQ);
880 /* cancel running adjtime() */
881 time_adjust = 0;
882 }
883 /* update jitter */
884 pps_jitter += (jitter - pps_jitter) >> PPS_INTMIN;
885}
886
887/*
888 * hardpps() - discipline CPU clock oscillator to external PPS signal
889 *
890 * This routine is called at each PPS signal arrival in order to
891 * discipline the CPU clock oscillator to the PPS signal. It takes two
892 * parameters: REALTIME and MONOTONIC_RAW clock timestamps. The former
893 * is used to correct clock phase error and the latter is used to
894 * correct the frequency.
895 *
896 * This code is based on David Mills's reference nanokernel
897 * implementation. It was mostly rewritten but keeps the same idea.
898 */
899void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts)
900{
901 struct pps_normtime pts_norm, freq_norm;
902 unsigned long flags;
903
904 pts_norm = pps_normalize_ts(*phase_ts);
905
906 write_seqlock_irqsave(&xtime_lock, flags);
907
908 /* clear the error bits, they will be set again if needed */
909 time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
910
911 /* indicate signal presence */
912 time_status |= STA_PPSSIGNAL;
913 pps_valid = PPS_VALID;
914
915 /* when called for the first time,
916 * just start the frequency interval */
917 if (unlikely(pps_fbase.tv_sec == 0)) {
918 pps_fbase = *raw_ts;
919 write_sequnlock_irqrestore(&xtime_lock, flags);
920 return;
921 }
922
923 /* ok, now we have a base for frequency calculation */
924 freq_norm = pps_normalize_ts(timespec_sub(*raw_ts, pps_fbase));
925
926 /* check that the signal is in the range
927 * [1s - MAXFREQ us, 1s + MAXFREQ us], otherwise reject it */
928 if ((freq_norm.sec == 0) ||
929 (freq_norm.nsec > MAXFREQ * freq_norm.sec) ||
930 (freq_norm.nsec < -MAXFREQ * freq_norm.sec)) {
931 time_status |= STA_PPSJITTER;
932 /* restart the frequency calibration interval */
933 pps_fbase = *raw_ts;
934 write_sequnlock_irqrestore(&xtime_lock, flags);
935 pr_err("hardpps: PPSJITTER: bad pulse\n");
936 return;
937 }
938
939 /* signal is ok */
940
941 /* check if the current frequency interval is finished */
942 if (freq_norm.sec >= (1 << pps_shift)) {
943 pps_calcnt++;
944 /* restart the frequency calibration interval */
945 pps_fbase = *raw_ts;
946 hardpps_update_freq(freq_norm);
947 }
948
949 hardpps_update_phase(pts_norm.nsec);
950
951 write_sequnlock_irqrestore(&xtime_lock, flags);
952}
953EXPORT_SYMBOL(hardpps);
954
955#endif /* CONFIG_NTP_PPS */
956
957static int __init ntp_tick_adj_setup(char *str)
958{
959 ntp_tick_adj = simple_strtol(str, NULL, 0);
960 ntp_tick_adj <<= NTP_SCALE_SHIFT;
961
962 return 1;
963}
964
965__setup("ntp_tick_adj=", ntp_tick_adj_setup);
966
967void __init ntp_init(void)
968{
969 ntp_clear();
970 hrtimer_init(&leap_timer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
971 leap_timer.function = ntp_leap_second;
972}