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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * NTP state machine interfaces and logic.
4 *
5 * This code was mainly moved from kernel/timer.c and kernel/time.c
6 * Please see those files for relevant copyright info and historical
7 * changelogs.
8 */
9#include <linux/capability.h>
10#include <linux/clocksource.h>
11#include <linux/workqueue.h>
12#include <linux/hrtimer.h>
13#include <linux/jiffies.h>
14#include <linux/math64.h>
15#include <linux/timex.h>
16#include <linux/time.h>
17#include <linux/mm.h>
18#include <linux/module.h>
19#include <linux/rtc.h>
20#include <linux/audit.h>
21
22#include "ntp_internal.h"
23#include "timekeeping_internal.h"
24
25
26/*
27 * NTP timekeeping variables:
28 *
29 * Note: All of the NTP state is protected by the timekeeping locks.
30 */
31
32
33/* USER_HZ period (usecs): */
34unsigned long tick_usec = USER_TICK_USEC;
35
36/* SHIFTED_HZ period (nsecs): */
37unsigned long tick_nsec;
38
39static u64 tick_length;
40static u64 tick_length_base;
41
42#define SECS_PER_DAY 86400
43#define MAX_TICKADJ 500LL /* usecs */
44#define MAX_TICKADJ_SCALED \
45 (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
46#define MAX_TAI_OFFSET 100000
47
48/*
49 * phase-lock loop variables
50 */
51
52/*
53 * clock synchronization status
54 *
55 * (TIME_ERROR prevents overwriting the CMOS clock)
56 */
57static int time_state = TIME_OK;
58
59/* clock status bits: */
60static int time_status = STA_UNSYNC;
61
62/* time adjustment (nsecs): */
63static s64 time_offset;
64
65/* pll time constant: */
66static long time_constant = 2;
67
68/* maximum error (usecs): */
69static long time_maxerror = NTP_PHASE_LIMIT;
70
71/* estimated error (usecs): */
72static long time_esterror = NTP_PHASE_LIMIT;
73
74/* frequency offset (scaled nsecs/secs): */
75static s64 time_freq;
76
77/* time at last adjustment (secs): */
78static time64_t time_reftime;
79
80static long time_adjust;
81
82/* constant (boot-param configurable) NTP tick adjustment (upscaled) */
83static s64 ntp_tick_adj;
84
85/* second value of the next pending leapsecond, or TIME64_MAX if no leap */
86static time64_t ntp_next_leap_sec = TIME64_MAX;
87
88#ifdef CONFIG_NTP_PPS
89
90/*
91 * The following variables are used when a pulse-per-second (PPS) signal
92 * is available. They establish the engineering parameters of the clock
93 * discipline loop when controlled by the PPS signal.
94 */
95#define PPS_VALID 10 /* PPS signal watchdog max (s) */
96#define PPS_POPCORN 4 /* popcorn spike threshold (shift) */
97#define PPS_INTMIN 2 /* min freq interval (s) (shift) */
98#define PPS_INTMAX 8 /* max freq interval (s) (shift) */
99#define PPS_INTCOUNT 4 /* number of consecutive good intervals to
100 increase pps_shift or consecutive bad
101 intervals to decrease it */
102#define PPS_MAXWANDER 100000 /* max PPS freq wander (ns/s) */
103
104static int pps_valid; /* signal watchdog counter */
105static long pps_tf[3]; /* phase median filter */
106static long pps_jitter; /* current jitter (ns) */
107static struct timespec64 pps_fbase; /* beginning of the last freq interval */
108static int pps_shift; /* current interval duration (s) (shift) */
109static int pps_intcnt; /* interval counter */
110static s64 pps_freq; /* frequency offset (scaled ns/s) */
111static long pps_stabil; /* current stability (scaled ns/s) */
112
113/*
114 * PPS signal quality monitors
115 */
116static long pps_calcnt; /* calibration intervals */
117static long pps_jitcnt; /* jitter limit exceeded */
118static long pps_stbcnt; /* stability limit exceeded */
119static long pps_errcnt; /* calibration errors */
120
121
122/* PPS kernel consumer compensates the whole phase error immediately.
123 * Otherwise, reduce the offset by a fixed factor times the time constant.
124 */
125static inline s64 ntp_offset_chunk(s64 offset)
126{
127 if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL)
128 return offset;
129 else
130 return shift_right(offset, SHIFT_PLL + time_constant);
131}
132
133static inline void pps_reset_freq_interval(void)
134{
135 /* the PPS calibration interval may end
136 surprisingly early */
137 pps_shift = PPS_INTMIN;
138 pps_intcnt = 0;
139}
140
141/**
142 * pps_clear - Clears the PPS state variables
143 */
144static inline void pps_clear(void)
145{
146 pps_reset_freq_interval();
147 pps_tf[0] = 0;
148 pps_tf[1] = 0;
149 pps_tf[2] = 0;
150 pps_fbase.tv_sec = pps_fbase.tv_nsec = 0;
151 pps_freq = 0;
152}
153
154/* Decrease pps_valid to indicate that another second has passed since
155 * the last PPS signal. When it reaches 0, indicate that PPS signal is
156 * missing.
157 */
158static inline void pps_dec_valid(void)
159{
160 if (pps_valid > 0)
161 pps_valid--;
162 else {
163 time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
164 STA_PPSWANDER | STA_PPSERROR);
165 pps_clear();
166 }
167}
168
169static inline void pps_set_freq(s64 freq)
170{
171 pps_freq = freq;
172}
173
174static inline int is_error_status(int status)
175{
176 return (status & (STA_UNSYNC|STA_CLOCKERR))
177 /* PPS signal lost when either PPS time or
178 * PPS frequency synchronization requested
179 */
180 || ((status & (STA_PPSFREQ|STA_PPSTIME))
181 && !(status & STA_PPSSIGNAL))
182 /* PPS jitter exceeded when
183 * PPS time synchronization requested */
184 || ((status & (STA_PPSTIME|STA_PPSJITTER))
185 == (STA_PPSTIME|STA_PPSJITTER))
186 /* PPS wander exceeded or calibration error when
187 * PPS frequency synchronization requested
188 */
189 || ((status & STA_PPSFREQ)
190 && (status & (STA_PPSWANDER|STA_PPSERROR)));
191}
192
193static inline void pps_fill_timex(struct __kernel_timex *txc)
194{
195 txc->ppsfreq = shift_right((pps_freq >> PPM_SCALE_INV_SHIFT) *
196 PPM_SCALE_INV, NTP_SCALE_SHIFT);
197 txc->jitter = pps_jitter;
198 if (!(time_status & STA_NANO))
199 txc->jitter = pps_jitter / NSEC_PER_USEC;
200 txc->shift = pps_shift;
201 txc->stabil = pps_stabil;
202 txc->jitcnt = pps_jitcnt;
203 txc->calcnt = pps_calcnt;
204 txc->errcnt = pps_errcnt;
205 txc->stbcnt = pps_stbcnt;
206}
207
208#else /* !CONFIG_NTP_PPS */
209
210static inline s64 ntp_offset_chunk(s64 offset)
211{
212 return shift_right(offset, SHIFT_PLL + time_constant);
213}
214
215static inline void pps_reset_freq_interval(void) {}
216static inline void pps_clear(void) {}
217static inline void pps_dec_valid(void) {}
218static inline void pps_set_freq(s64 freq) {}
219
220static inline int is_error_status(int status)
221{
222 return status & (STA_UNSYNC|STA_CLOCKERR);
223}
224
225static inline void pps_fill_timex(struct __kernel_timex *txc)
226{
227 /* PPS is not implemented, so these are zero */
228 txc->ppsfreq = 0;
229 txc->jitter = 0;
230 txc->shift = 0;
231 txc->stabil = 0;
232 txc->jitcnt = 0;
233 txc->calcnt = 0;
234 txc->errcnt = 0;
235 txc->stbcnt = 0;
236}
237
238#endif /* CONFIG_NTP_PPS */
239
240
241/**
242 * ntp_synced - Returns 1 if the NTP status is not UNSYNC
243 *
244 */
245static inline int ntp_synced(void)
246{
247 return !(time_status & STA_UNSYNC);
248}
249
250
251/*
252 * NTP methods:
253 */
254
255/*
256 * Update (tick_length, tick_length_base, tick_nsec), based
257 * on (tick_usec, ntp_tick_adj, time_freq):
258 */
259static void ntp_update_frequency(void)
260{
261 u64 second_length;
262 u64 new_base;
263
264 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
265 << NTP_SCALE_SHIFT;
266
267 second_length += ntp_tick_adj;
268 second_length += time_freq;
269
270 tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT;
271 new_base = div_u64(second_length, NTP_INTERVAL_FREQ);
272
273 /*
274 * Don't wait for the next second_overflow, apply
275 * the change to the tick length immediately:
276 */
277 tick_length += new_base - tick_length_base;
278 tick_length_base = new_base;
279}
280
281static inline s64 ntp_update_offset_fll(s64 offset64, long secs)
282{
283 time_status &= ~STA_MODE;
284
285 if (secs < MINSEC)
286 return 0;
287
288 if (!(time_status & STA_FLL) && (secs <= MAXSEC))
289 return 0;
290
291 time_status |= STA_MODE;
292
293 return div64_long(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
294}
295
296static void ntp_update_offset(long offset)
297{
298 s64 freq_adj;
299 s64 offset64;
300 long secs;
301
302 if (!(time_status & STA_PLL))
303 return;
304
305 if (!(time_status & STA_NANO)) {
306 /* Make sure the multiplication below won't overflow */
307 offset = clamp(offset, -USEC_PER_SEC, USEC_PER_SEC);
308 offset *= NSEC_PER_USEC;
309 }
310
311 /*
312 * Scale the phase adjustment and
313 * clamp to the operating range.
314 */
315 offset = clamp(offset, -MAXPHASE, MAXPHASE);
316
317 /*
318 * Select how the frequency is to be controlled
319 * and in which mode (PLL or FLL).
320 */
321 secs = (long)(__ktime_get_real_seconds() - time_reftime);
322 if (unlikely(time_status & STA_FREQHOLD))
323 secs = 0;
324
325 time_reftime = __ktime_get_real_seconds();
326
327 offset64 = offset;
328 freq_adj = ntp_update_offset_fll(offset64, secs);
329
330 /*
331 * Clamp update interval to reduce PLL gain with low
332 * sampling rate (e.g. intermittent network connection)
333 * to avoid instability.
334 */
335 if (unlikely(secs > 1 << (SHIFT_PLL + 1 + time_constant)))
336 secs = 1 << (SHIFT_PLL + 1 + time_constant);
337
338 freq_adj += (offset64 * secs) <<
339 (NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant));
340
341 freq_adj = min(freq_adj + time_freq, MAXFREQ_SCALED);
342
343 time_freq = max(freq_adj, -MAXFREQ_SCALED);
344
345 time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
346}
347
348/**
349 * ntp_clear - Clears the NTP state variables
350 */
351void ntp_clear(void)
352{
353 time_adjust = 0; /* stop active adjtime() */
354 time_status |= STA_UNSYNC;
355 time_maxerror = NTP_PHASE_LIMIT;
356 time_esterror = NTP_PHASE_LIMIT;
357
358 ntp_update_frequency();
359
360 tick_length = tick_length_base;
361 time_offset = 0;
362
363 ntp_next_leap_sec = TIME64_MAX;
364 /* Clear PPS state variables */
365 pps_clear();
366}
367
368
369u64 ntp_tick_length(void)
370{
371 return tick_length;
372}
373
374/**
375 * ntp_get_next_leap - Returns the next leapsecond in CLOCK_REALTIME ktime_t
376 *
377 * Provides the time of the next leapsecond against CLOCK_REALTIME in
378 * a ktime_t format. Returns KTIME_MAX if no leapsecond is pending.
379 */
380ktime_t ntp_get_next_leap(void)
381{
382 ktime_t ret;
383
384 if ((time_state == TIME_INS) && (time_status & STA_INS))
385 return ktime_set(ntp_next_leap_sec, 0);
386 ret = KTIME_MAX;
387 return ret;
388}
389
390/*
391 * this routine handles the overflow of the microsecond field
392 *
393 * The tricky bits of code to handle the accurate clock support
394 * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
395 * They were originally developed for SUN and DEC kernels.
396 * All the kudos should go to Dave for this stuff.
397 *
398 * Also handles leap second processing, and returns leap offset
399 */
400int second_overflow(time64_t secs)
401{
402 s64 delta;
403 int leap = 0;
404 s32 rem;
405
406 /*
407 * Leap second processing. If in leap-insert state at the end of the
408 * day, the system clock is set back one second; if in leap-delete
409 * state, the system clock is set ahead one second.
410 */
411 switch (time_state) {
412 case TIME_OK:
413 if (time_status & STA_INS) {
414 time_state = TIME_INS;
415 div_s64_rem(secs, SECS_PER_DAY, &rem);
416 ntp_next_leap_sec = secs + SECS_PER_DAY - rem;
417 } else if (time_status & STA_DEL) {
418 time_state = TIME_DEL;
419 div_s64_rem(secs + 1, SECS_PER_DAY, &rem);
420 ntp_next_leap_sec = secs + SECS_PER_DAY - rem;
421 }
422 break;
423 case TIME_INS:
424 if (!(time_status & STA_INS)) {
425 ntp_next_leap_sec = TIME64_MAX;
426 time_state = TIME_OK;
427 } else if (secs == ntp_next_leap_sec) {
428 leap = -1;
429 time_state = TIME_OOP;
430 printk(KERN_NOTICE
431 "Clock: inserting leap second 23:59:60 UTC\n");
432 }
433 break;
434 case TIME_DEL:
435 if (!(time_status & STA_DEL)) {
436 ntp_next_leap_sec = TIME64_MAX;
437 time_state = TIME_OK;
438 } else if (secs == ntp_next_leap_sec) {
439 leap = 1;
440 ntp_next_leap_sec = TIME64_MAX;
441 time_state = TIME_WAIT;
442 printk(KERN_NOTICE
443 "Clock: deleting leap second 23:59:59 UTC\n");
444 }
445 break;
446 case TIME_OOP:
447 ntp_next_leap_sec = TIME64_MAX;
448 time_state = TIME_WAIT;
449 break;
450 case TIME_WAIT:
451 if (!(time_status & (STA_INS | STA_DEL)))
452 time_state = TIME_OK;
453 break;
454 }
455
456
457 /* Bump the maxerror field */
458 time_maxerror += MAXFREQ / NSEC_PER_USEC;
459 if (time_maxerror > NTP_PHASE_LIMIT) {
460 time_maxerror = NTP_PHASE_LIMIT;
461 time_status |= STA_UNSYNC;
462 }
463
464 /* Compute the phase adjustment for the next second */
465 tick_length = tick_length_base;
466
467 delta = ntp_offset_chunk(time_offset);
468 time_offset -= delta;
469 tick_length += delta;
470
471 /* Check PPS signal */
472 pps_dec_valid();
473
474 if (!time_adjust)
475 goto out;
476
477 if (time_adjust > MAX_TICKADJ) {
478 time_adjust -= MAX_TICKADJ;
479 tick_length += MAX_TICKADJ_SCALED;
480 goto out;
481 }
482
483 if (time_adjust < -MAX_TICKADJ) {
484 time_adjust += MAX_TICKADJ;
485 tick_length -= MAX_TICKADJ_SCALED;
486 goto out;
487 }
488
489 tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)
490 << NTP_SCALE_SHIFT;
491 time_adjust = 0;
492
493out:
494 return leap;
495}
496
497static void sync_hw_clock(struct work_struct *work);
498static DECLARE_DELAYED_WORK(sync_work, sync_hw_clock);
499
500static void sched_sync_hw_clock(struct timespec64 now,
501 unsigned long target_nsec, bool fail)
502
503{
504 struct timespec64 next;
505
506 ktime_get_real_ts64(&next);
507 if (!fail)
508 next.tv_sec = 659;
509 else {
510 /*
511 * Try again as soon as possible. Delaying long periods
512 * decreases the accuracy of the work queue timer. Due to this
513 * the algorithm is very likely to require a short-sleep retry
514 * after the above long sleep to synchronize ts_nsec.
515 */
516 next.tv_sec = 0;
517 }
518
519 /* Compute the needed delay that will get to tv_nsec == target_nsec */
520 next.tv_nsec = target_nsec - next.tv_nsec;
521 if (next.tv_nsec <= 0)
522 next.tv_nsec += NSEC_PER_SEC;
523 if (next.tv_nsec >= NSEC_PER_SEC) {
524 next.tv_sec++;
525 next.tv_nsec -= NSEC_PER_SEC;
526 }
527
528 queue_delayed_work(system_power_efficient_wq, &sync_work,
529 timespec64_to_jiffies(&next));
530}
531
532static void sync_rtc_clock(void)
533{
534 unsigned long target_nsec;
535 struct timespec64 adjust, now;
536 int rc;
537
538 if (!IS_ENABLED(CONFIG_RTC_SYSTOHC))
539 return;
540
541 ktime_get_real_ts64(&now);
542
543 adjust = now;
544 if (persistent_clock_is_local)
545 adjust.tv_sec -= (sys_tz.tz_minuteswest * 60);
546
547 /*
548 * The current RTC in use will provide the target_nsec it wants to be
549 * called at, and does rtc_tv_nsec_ok internally.
550 */
551 rc = rtc_set_ntp_time(adjust, &target_nsec);
552 if (rc == -ENODEV)
553 return;
554
555 sched_sync_hw_clock(now, target_nsec, rc);
556}
557
558#ifdef CONFIG_GENERIC_CMOS_UPDATE
559int __weak update_persistent_clock64(struct timespec64 now64)
560{
561 return -ENODEV;
562}
563#endif
564
565static bool sync_cmos_clock(void)
566{
567 static bool no_cmos;
568 struct timespec64 now;
569 struct timespec64 adjust;
570 int rc = -EPROTO;
571 long target_nsec = NSEC_PER_SEC / 2;
572
573 if (!IS_ENABLED(CONFIG_GENERIC_CMOS_UPDATE))
574 return false;
575
576 if (no_cmos)
577 return false;
578
579 /*
580 * Historically update_persistent_clock64() has followed x86
581 * semantics, which match the MC146818A/etc RTC. This RTC will store
582 * 'adjust' and then in .5s it will advance once second.
583 *
584 * Architectures are strongly encouraged to use rtclib and not
585 * implement this legacy API.
586 */
587 ktime_get_real_ts64(&now);
588 if (rtc_tv_nsec_ok(-1 * target_nsec, &adjust, &now)) {
589 if (persistent_clock_is_local)
590 adjust.tv_sec -= (sys_tz.tz_minuteswest * 60);
591 rc = update_persistent_clock64(adjust);
592 /*
593 * The machine does not support update_persistent_clock64 even
594 * though it defines CONFIG_GENERIC_CMOS_UPDATE.
595 */
596 if (rc == -ENODEV) {
597 no_cmos = true;
598 return false;
599 }
600 }
601
602 sched_sync_hw_clock(now, target_nsec, rc);
603 return true;
604}
605
606/*
607 * If we have an externally synchronized Linux clock, then update RTC clock
608 * accordingly every ~11 minutes. Generally RTCs can only store second
609 * precision, but many RTCs will adjust the phase of their second tick to
610 * match the moment of update. This infrastructure arranges to call to the RTC
611 * set at the correct moment to phase synchronize the RTC second tick over
612 * with the kernel clock.
613 */
614static void sync_hw_clock(struct work_struct *work)
615{
616 if (!ntp_synced())
617 return;
618
619 if (sync_cmos_clock())
620 return;
621
622 sync_rtc_clock();
623}
624
625void ntp_notify_cmos_timer(void)
626{
627 if (!ntp_synced())
628 return;
629
630 if (IS_ENABLED(CONFIG_GENERIC_CMOS_UPDATE) ||
631 IS_ENABLED(CONFIG_RTC_SYSTOHC))
632 queue_delayed_work(system_power_efficient_wq, &sync_work, 0);
633}
634
635/*
636 * Propagate a new txc->status value into the NTP state:
637 */
638static inline void process_adj_status(const struct __kernel_timex *txc)
639{
640 if ((time_status & STA_PLL) && !(txc->status & STA_PLL)) {
641 time_state = TIME_OK;
642 time_status = STA_UNSYNC;
643 ntp_next_leap_sec = TIME64_MAX;
644 /* restart PPS frequency calibration */
645 pps_reset_freq_interval();
646 }
647
648 /*
649 * If we turn on PLL adjustments then reset the
650 * reference time to current time.
651 */
652 if (!(time_status & STA_PLL) && (txc->status & STA_PLL))
653 time_reftime = __ktime_get_real_seconds();
654
655 /* only set allowed bits */
656 time_status &= STA_RONLY;
657 time_status |= txc->status & ~STA_RONLY;
658}
659
660
661static inline void process_adjtimex_modes(const struct __kernel_timex *txc,
662 s32 *time_tai)
663{
664 if (txc->modes & ADJ_STATUS)
665 process_adj_status(txc);
666
667 if (txc->modes & ADJ_NANO)
668 time_status |= STA_NANO;
669
670 if (txc->modes & ADJ_MICRO)
671 time_status &= ~STA_NANO;
672
673 if (txc->modes & ADJ_FREQUENCY) {
674 time_freq = txc->freq * PPM_SCALE;
675 time_freq = min(time_freq, MAXFREQ_SCALED);
676 time_freq = max(time_freq, -MAXFREQ_SCALED);
677 /* update pps_freq */
678 pps_set_freq(time_freq);
679 }
680
681 if (txc->modes & ADJ_MAXERROR)
682 time_maxerror = txc->maxerror;
683
684 if (txc->modes & ADJ_ESTERROR)
685 time_esterror = txc->esterror;
686
687 if (txc->modes & ADJ_TIMECONST) {
688 time_constant = txc->constant;
689 if (!(time_status & STA_NANO))
690 time_constant += 4;
691 time_constant = min(time_constant, (long)MAXTC);
692 time_constant = max(time_constant, 0l);
693 }
694
695 if (txc->modes & ADJ_TAI &&
696 txc->constant >= 0 && txc->constant <= MAX_TAI_OFFSET)
697 *time_tai = txc->constant;
698
699 if (txc->modes & ADJ_OFFSET)
700 ntp_update_offset(txc->offset);
701
702 if (txc->modes & ADJ_TICK)
703 tick_usec = txc->tick;
704
705 if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET))
706 ntp_update_frequency();
707}
708
709
710/*
711 * adjtimex mainly allows reading (and writing, if superuser) of
712 * kernel time-keeping variables. used by xntpd.
713 */
714int __do_adjtimex(struct __kernel_timex *txc, const struct timespec64 *ts,
715 s32 *time_tai, struct audit_ntp_data *ad)
716{
717 int result;
718
719 if (txc->modes & ADJ_ADJTIME) {
720 long save_adjust = time_adjust;
721
722 if (!(txc->modes & ADJ_OFFSET_READONLY)) {
723 /* adjtime() is independent from ntp_adjtime() */
724 time_adjust = txc->offset;
725 ntp_update_frequency();
726
727 audit_ntp_set_old(ad, AUDIT_NTP_ADJUST, save_adjust);
728 audit_ntp_set_new(ad, AUDIT_NTP_ADJUST, time_adjust);
729 }
730 txc->offset = save_adjust;
731 } else {
732 /* If there are input parameters, then process them: */
733 if (txc->modes) {
734 audit_ntp_set_old(ad, AUDIT_NTP_OFFSET, time_offset);
735 audit_ntp_set_old(ad, AUDIT_NTP_FREQ, time_freq);
736 audit_ntp_set_old(ad, AUDIT_NTP_STATUS, time_status);
737 audit_ntp_set_old(ad, AUDIT_NTP_TAI, *time_tai);
738 audit_ntp_set_old(ad, AUDIT_NTP_TICK, tick_usec);
739
740 process_adjtimex_modes(txc, time_tai);
741
742 audit_ntp_set_new(ad, AUDIT_NTP_OFFSET, time_offset);
743 audit_ntp_set_new(ad, AUDIT_NTP_FREQ, time_freq);
744 audit_ntp_set_new(ad, AUDIT_NTP_STATUS, time_status);
745 audit_ntp_set_new(ad, AUDIT_NTP_TAI, *time_tai);
746 audit_ntp_set_new(ad, AUDIT_NTP_TICK, tick_usec);
747 }
748
749 txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
750 NTP_SCALE_SHIFT);
751 if (!(time_status & STA_NANO))
752 txc->offset = (u32)txc->offset / NSEC_PER_USEC;
753 }
754
755 result = time_state; /* mostly `TIME_OK' */
756 /* check for errors */
757 if (is_error_status(time_status))
758 result = TIME_ERROR;
759
760 txc->freq = shift_right((time_freq >> PPM_SCALE_INV_SHIFT) *
761 PPM_SCALE_INV, NTP_SCALE_SHIFT);
762 txc->maxerror = time_maxerror;
763 txc->esterror = time_esterror;
764 txc->status = time_status;
765 txc->constant = time_constant;
766 txc->precision = 1;
767 txc->tolerance = MAXFREQ_SCALED / PPM_SCALE;
768 txc->tick = tick_usec;
769 txc->tai = *time_tai;
770
771 /* fill PPS status fields */
772 pps_fill_timex(txc);
773
774 txc->time.tv_sec = ts->tv_sec;
775 txc->time.tv_usec = ts->tv_nsec;
776 if (!(time_status & STA_NANO))
777 txc->time.tv_usec = ts->tv_nsec / NSEC_PER_USEC;
778
779 /* Handle leapsec adjustments */
780 if (unlikely(ts->tv_sec >= ntp_next_leap_sec)) {
781 if ((time_state == TIME_INS) && (time_status & STA_INS)) {
782 result = TIME_OOP;
783 txc->tai++;
784 txc->time.tv_sec--;
785 }
786 if ((time_state == TIME_DEL) && (time_status & STA_DEL)) {
787 result = TIME_WAIT;
788 txc->tai--;
789 txc->time.tv_sec++;
790 }
791 if ((time_state == TIME_OOP) &&
792 (ts->tv_sec == ntp_next_leap_sec)) {
793 result = TIME_WAIT;
794 }
795 }
796
797 return result;
798}
799
800#ifdef CONFIG_NTP_PPS
801
802/* actually struct pps_normtime is good old struct timespec, but it is
803 * semantically different (and it is the reason why it was invented):
804 * pps_normtime.nsec has a range of ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ]
805 * while timespec.tv_nsec has a range of [0, NSEC_PER_SEC) */
806struct pps_normtime {
807 s64 sec; /* seconds */
808 long nsec; /* nanoseconds */
809};
810
811/* normalize the timestamp so that nsec is in the
812 ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ] interval */
813static inline struct pps_normtime pps_normalize_ts(struct timespec64 ts)
814{
815 struct pps_normtime norm = {
816 .sec = ts.tv_sec,
817 .nsec = ts.tv_nsec
818 };
819
820 if (norm.nsec > (NSEC_PER_SEC >> 1)) {
821 norm.nsec -= NSEC_PER_SEC;
822 norm.sec++;
823 }
824
825 return norm;
826}
827
828/* get current phase correction and jitter */
829static inline long pps_phase_filter_get(long *jitter)
830{
831 *jitter = pps_tf[0] - pps_tf[1];
832 if (*jitter < 0)
833 *jitter = -*jitter;
834
835 /* TODO: test various filters */
836 return pps_tf[0];
837}
838
839/* add the sample to the phase filter */
840static inline void pps_phase_filter_add(long err)
841{
842 pps_tf[2] = pps_tf[1];
843 pps_tf[1] = pps_tf[0];
844 pps_tf[0] = err;
845}
846
847/* decrease frequency calibration interval length.
848 * It is halved after four consecutive unstable intervals.
849 */
850static inline void pps_dec_freq_interval(void)
851{
852 if (--pps_intcnt <= -PPS_INTCOUNT) {
853 pps_intcnt = -PPS_INTCOUNT;
854 if (pps_shift > PPS_INTMIN) {
855 pps_shift--;
856 pps_intcnt = 0;
857 }
858 }
859}
860
861/* increase frequency calibration interval length.
862 * It is doubled after four consecutive stable intervals.
863 */
864static inline void pps_inc_freq_interval(void)
865{
866 if (++pps_intcnt >= PPS_INTCOUNT) {
867 pps_intcnt = PPS_INTCOUNT;
868 if (pps_shift < PPS_INTMAX) {
869 pps_shift++;
870 pps_intcnt = 0;
871 }
872 }
873}
874
875/* update clock frequency based on MONOTONIC_RAW clock PPS signal
876 * timestamps
877 *
878 * At the end of the calibration interval the difference between the
879 * first and last MONOTONIC_RAW clock timestamps divided by the length
880 * of the interval becomes the frequency update. If the interval was
881 * too long, the data are discarded.
882 * Returns the difference between old and new frequency values.
883 */
884static long hardpps_update_freq(struct pps_normtime freq_norm)
885{
886 long delta, delta_mod;
887 s64 ftemp;
888
889 /* check if the frequency interval was too long */
890 if (freq_norm.sec > (2 << pps_shift)) {
891 time_status |= STA_PPSERROR;
892 pps_errcnt++;
893 pps_dec_freq_interval();
894 printk_deferred(KERN_ERR
895 "hardpps: PPSERROR: interval too long - %lld s\n",
896 freq_norm.sec);
897 return 0;
898 }
899
900 /* here the raw frequency offset and wander (stability) is
901 * calculated. If the wander is less than the wander threshold
902 * the interval is increased; otherwise it is decreased.
903 */
904 ftemp = div_s64(((s64)(-freq_norm.nsec)) << NTP_SCALE_SHIFT,
905 freq_norm.sec);
906 delta = shift_right(ftemp - pps_freq, NTP_SCALE_SHIFT);
907 pps_freq = ftemp;
908 if (delta > PPS_MAXWANDER || delta < -PPS_MAXWANDER) {
909 printk_deferred(KERN_WARNING
910 "hardpps: PPSWANDER: change=%ld\n", delta);
911 time_status |= STA_PPSWANDER;
912 pps_stbcnt++;
913 pps_dec_freq_interval();
914 } else { /* good sample */
915 pps_inc_freq_interval();
916 }
917
918 /* the stability metric is calculated as the average of recent
919 * frequency changes, but is used only for performance
920 * monitoring
921 */
922 delta_mod = delta;
923 if (delta_mod < 0)
924 delta_mod = -delta_mod;
925 pps_stabil += (div_s64(((s64)delta_mod) <<
926 (NTP_SCALE_SHIFT - SHIFT_USEC),
927 NSEC_PER_USEC) - pps_stabil) >> PPS_INTMIN;
928
929 /* if enabled, the system clock frequency is updated */
930 if ((time_status & STA_PPSFREQ) != 0 &&
931 (time_status & STA_FREQHOLD) == 0) {
932 time_freq = pps_freq;
933 ntp_update_frequency();
934 }
935
936 return delta;
937}
938
939/* correct REALTIME clock phase error against PPS signal */
940static void hardpps_update_phase(long error)
941{
942 long correction = -error;
943 long jitter;
944
945 /* add the sample to the median filter */
946 pps_phase_filter_add(correction);
947 correction = pps_phase_filter_get(&jitter);
948
949 /* Nominal jitter is due to PPS signal noise. If it exceeds the
950 * threshold, the sample is discarded; otherwise, if so enabled,
951 * the time offset is updated.
952 */
953 if (jitter > (pps_jitter << PPS_POPCORN)) {
954 printk_deferred(KERN_WARNING
955 "hardpps: PPSJITTER: jitter=%ld, limit=%ld\n",
956 jitter, (pps_jitter << PPS_POPCORN));
957 time_status |= STA_PPSJITTER;
958 pps_jitcnt++;
959 } else if (time_status & STA_PPSTIME) {
960 /* correct the time using the phase offset */
961 time_offset = div_s64(((s64)correction) << NTP_SCALE_SHIFT,
962 NTP_INTERVAL_FREQ);
963 /* cancel running adjtime() */
964 time_adjust = 0;
965 }
966 /* update jitter */
967 pps_jitter += (jitter - pps_jitter) >> PPS_INTMIN;
968}
969
970/*
971 * __hardpps() - discipline CPU clock oscillator to external PPS signal
972 *
973 * This routine is called at each PPS signal arrival in order to
974 * discipline the CPU clock oscillator to the PPS signal. It takes two
975 * parameters: REALTIME and MONOTONIC_RAW clock timestamps. The former
976 * is used to correct clock phase error and the latter is used to
977 * correct the frequency.
978 *
979 * This code is based on David Mills's reference nanokernel
980 * implementation. It was mostly rewritten but keeps the same idea.
981 */
982void __hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
983{
984 struct pps_normtime pts_norm, freq_norm;
985
986 pts_norm = pps_normalize_ts(*phase_ts);
987
988 /* clear the error bits, they will be set again if needed */
989 time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
990
991 /* indicate signal presence */
992 time_status |= STA_PPSSIGNAL;
993 pps_valid = PPS_VALID;
994
995 /* when called for the first time,
996 * just start the frequency interval */
997 if (unlikely(pps_fbase.tv_sec == 0)) {
998 pps_fbase = *raw_ts;
999 return;
1000 }
1001
1002 /* ok, now we have a base for frequency calculation */
1003 freq_norm = pps_normalize_ts(timespec64_sub(*raw_ts, pps_fbase));
1004
1005 /* check that the signal is in the range
1006 * [1s - MAXFREQ us, 1s + MAXFREQ us], otherwise reject it */
1007 if ((freq_norm.sec == 0) ||
1008 (freq_norm.nsec > MAXFREQ * freq_norm.sec) ||
1009 (freq_norm.nsec < -MAXFREQ * freq_norm.sec)) {
1010 time_status |= STA_PPSJITTER;
1011 /* restart the frequency calibration interval */
1012 pps_fbase = *raw_ts;
1013 printk_deferred(KERN_ERR "hardpps: PPSJITTER: bad pulse\n");
1014 return;
1015 }
1016
1017 /* signal is ok */
1018
1019 /* check if the current frequency interval is finished */
1020 if (freq_norm.sec >= (1 << pps_shift)) {
1021 pps_calcnt++;
1022 /* restart the frequency calibration interval */
1023 pps_fbase = *raw_ts;
1024 hardpps_update_freq(freq_norm);
1025 }
1026
1027 hardpps_update_phase(pts_norm.nsec);
1028
1029}
1030#endif /* CONFIG_NTP_PPS */
1031
1032static int __init ntp_tick_adj_setup(char *str)
1033{
1034 int rc = kstrtos64(str, 0, &ntp_tick_adj);
1035 if (rc)
1036 return rc;
1037
1038 ntp_tick_adj <<= NTP_SCALE_SHIFT;
1039 return 1;
1040}
1041
1042__setup("ntp_tick_adj=", ntp_tick_adj_setup);
1043
1044void __init ntp_init(void)
1045{
1046 ntp_clear();
1047}
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}