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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// 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 * struct ntp_data - Structure holding all NTP related state
27 * @tick_usec: USER_HZ period in microseconds
28 * @tick_length: Adjusted tick length
29 * @tick_length_base: Base value for @tick_length
30 * @time_state: State of the clock synchronization
31 * @time_status: Clock status bits
32 * @time_offset: Time adjustment in nanoseconds
33 * @time_constant: PLL time constant
34 * @time_maxerror: Maximum error in microseconds holding the NTP sync distance
35 * (NTP dispersion + delay / 2)
36 * @time_esterror: Estimated error in microseconds holding NTP dispersion
37 * @time_freq: Frequency offset scaled nsecs/secs
38 * @time_reftime: Time at last adjustment in seconds
39 * @time_adjust: Adjustment value
40 * @ntp_tick_adj: Constant boot-param configurable NTP tick adjustment (upscaled)
41 * @ntp_next_leap_sec: Second value of the next pending leapsecond, or TIME64_MAX if no leap
42 *
43 * @pps_valid: PPS signal watchdog counter
44 * @pps_tf: PPS phase median filter
45 * @pps_jitter: PPS current jitter in nanoseconds
46 * @pps_fbase: PPS beginning of the last freq interval
47 * @pps_shift: PPS current interval duration in seconds (shift value)
48 * @pps_intcnt: PPS interval counter
49 * @pps_freq: PPS frequency offset in scaled ns/s
50 * @pps_stabil: PPS current stability in scaled ns/s
51 * @pps_calcnt: PPS monitor: calibration intervals
52 * @pps_jitcnt: PPS monitor: jitter limit exceeded
53 * @pps_stbcnt: PPS monitor: stability limit exceeded
54 * @pps_errcnt: PPS monitor: calibration errors
55 *
56 * Protected by the timekeeping locks.
57 */
58struct ntp_data {
59 unsigned long tick_usec;
60 u64 tick_length;
61 u64 tick_length_base;
62 int time_state;
63 int time_status;
64 s64 time_offset;
65 long time_constant;
66 long time_maxerror;
67 long time_esterror;
68 s64 time_freq;
69 time64_t time_reftime;
70 long time_adjust;
71 s64 ntp_tick_adj;
72 time64_t ntp_next_leap_sec;
73#ifdef CONFIG_NTP_PPS
74 int pps_valid;
75 long pps_tf[3];
76 long pps_jitter;
77 struct timespec64 pps_fbase;
78 int pps_shift;
79 int pps_intcnt;
80 s64 pps_freq;
81 long pps_stabil;
82 long pps_calcnt;
83 long pps_jitcnt;
84 long pps_stbcnt;
85 long pps_errcnt;
86#endif
87};
88
89static struct ntp_data tk_ntp_data = {
90 .tick_usec = USER_TICK_USEC,
91 .time_state = TIME_OK,
92 .time_status = STA_UNSYNC,
93 .time_constant = 2,
94 .time_maxerror = NTP_PHASE_LIMIT,
95 .time_esterror = NTP_PHASE_LIMIT,
96 .ntp_next_leap_sec = TIME64_MAX,
97};
98
99#define SECS_PER_DAY 86400
100#define MAX_TICKADJ 500LL /* usecs */
101#define MAX_TICKADJ_SCALED \
102 (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
103#define MAX_TAI_OFFSET 100000
104
105#ifdef CONFIG_NTP_PPS
106
107/*
108 * The following variables are used when a pulse-per-second (PPS) signal
109 * is available. They establish the engineering parameters of the clock
110 * discipline loop when controlled by the PPS signal.
111 */
112#define PPS_VALID 10 /* PPS signal watchdog max (s) */
113#define PPS_POPCORN 4 /* popcorn spike threshold (shift) */
114#define PPS_INTMIN 2 /* min freq interval (s) (shift) */
115#define PPS_INTMAX 8 /* max freq interval (s) (shift) */
116#define PPS_INTCOUNT 4 /* number of consecutive good intervals to
117 increase pps_shift or consecutive bad
118 intervals to decrease it */
119#define PPS_MAXWANDER 100000 /* max PPS freq wander (ns/s) */
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(struct ntp_data *ntpdata, s64 offset)
126{
127 if (ntpdata->time_status & STA_PPSTIME && ntpdata->time_status & STA_PPSSIGNAL)
128 return offset;
129 else
130 return shift_right(offset, SHIFT_PLL + ntpdata->time_constant);
131}
132
133static inline void pps_reset_freq_interval(struct ntp_data *ntpdata)
134{
135 /* The PPS calibration interval may end surprisingly early */
136 ntpdata->pps_shift = PPS_INTMIN;
137 ntpdata->pps_intcnt = 0;
138}
139
140/**
141 * pps_clear - Clears the PPS state variables
142 * @ntpdata: Pointer to ntp data
143 */
144static inline void pps_clear(struct ntp_data *ntpdata)
145{
146 pps_reset_freq_interval(ntpdata);
147 ntpdata->pps_tf[0] = 0;
148 ntpdata->pps_tf[1] = 0;
149 ntpdata->pps_tf[2] = 0;
150 ntpdata->pps_fbase.tv_sec = ntpdata->pps_fbase.tv_nsec = 0;
151 ntpdata->pps_freq = 0;
152}
153
154/*
155 * Decrease pps_valid to indicate that another second has passed since the
156 * last PPS signal. When it reaches 0, indicate that PPS signal is missing.
157 */
158static inline void pps_dec_valid(struct ntp_data *ntpdata)
159{
160 if (ntpdata->pps_valid > 0) {
161 ntpdata->pps_valid--;
162 } else {
163 ntpdata->time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
164 STA_PPSWANDER | STA_PPSERROR);
165 pps_clear(ntpdata);
166 }
167}
168
169static inline void pps_set_freq(struct ntp_data *ntpdata)
170{
171 ntpdata->pps_freq = ntpdata->time_freq;
172}
173
174static inline bool is_error_status(int status)
175{
176 return (status & (STA_UNSYNC|STA_CLOCKERR))
177 /*
178 * PPS signal lost when either PPS time or PPS frequency
179 * synchronization requested
180 */
181 || ((status & (STA_PPSFREQ|STA_PPSTIME))
182 && !(status & STA_PPSSIGNAL))
183 /*
184 * PPS jitter exceeded when PPS time synchronization
185 * requested
186 */
187 || ((status & (STA_PPSTIME|STA_PPSJITTER))
188 == (STA_PPSTIME|STA_PPSJITTER))
189 /*
190 * PPS wander exceeded or calibration error when PPS
191 * frequency synchronization requested
192 */
193 || ((status & STA_PPSFREQ)
194 && (status & (STA_PPSWANDER|STA_PPSERROR)));
195}
196
197static inline void pps_fill_timex(struct ntp_data *ntpdata, struct __kernel_timex *txc)
198{
199 txc->ppsfreq = shift_right((ntpdata->pps_freq >> PPM_SCALE_INV_SHIFT) *
200 PPM_SCALE_INV, NTP_SCALE_SHIFT);
201 txc->jitter = ntpdata->pps_jitter;
202 if (!(ntpdata->time_status & STA_NANO))
203 txc->jitter = ntpdata->pps_jitter / NSEC_PER_USEC;
204 txc->shift = ntpdata->pps_shift;
205 txc->stabil = ntpdata->pps_stabil;
206 txc->jitcnt = ntpdata->pps_jitcnt;
207 txc->calcnt = ntpdata->pps_calcnt;
208 txc->errcnt = ntpdata->pps_errcnt;
209 txc->stbcnt = ntpdata->pps_stbcnt;
210}
211
212#else /* !CONFIG_NTP_PPS */
213
214static inline s64 ntp_offset_chunk(struct ntp_data *ntpdata, s64 offset)
215{
216 return shift_right(offset, SHIFT_PLL + ntpdata->time_constant);
217}
218
219static inline void pps_reset_freq_interval(struct ntp_data *ntpdata) {}
220static inline void pps_clear(struct ntp_data *ntpdata) {}
221static inline void pps_dec_valid(struct ntp_data *ntpdata) {}
222static inline void pps_set_freq(struct ntp_data *ntpdata) {}
223
224static inline bool is_error_status(int status)
225{
226 return status & (STA_UNSYNC|STA_CLOCKERR);
227}
228
229static inline void pps_fill_timex(struct ntp_data *ntpdata, struct __kernel_timex *txc)
230{
231 /* PPS is not implemented, so these are zero */
232 txc->ppsfreq = 0;
233 txc->jitter = 0;
234 txc->shift = 0;
235 txc->stabil = 0;
236 txc->jitcnt = 0;
237 txc->calcnt = 0;
238 txc->errcnt = 0;
239 txc->stbcnt = 0;
240}
241
242#endif /* CONFIG_NTP_PPS */
243
244/*
245 * Update tick_length and tick_length_base, based on tick_usec, ntp_tick_adj and
246 * time_freq:
247 */
248static void ntp_update_frequency(struct ntp_data *ntpdata)
249{
250 u64 second_length, new_base, tick_usec = (u64)ntpdata->tick_usec;
251
252 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) << NTP_SCALE_SHIFT;
253
254 second_length += ntpdata->ntp_tick_adj;
255 second_length += ntpdata->time_freq;
256
257 new_base = div_u64(second_length, NTP_INTERVAL_FREQ);
258
259 /*
260 * Don't wait for the next second_overflow, apply the change to the
261 * tick length immediately:
262 */
263 ntpdata->tick_length += new_base - ntpdata->tick_length_base;
264 ntpdata->tick_length_base = new_base;
265}
266
267static inline s64 ntp_update_offset_fll(struct ntp_data *ntpdata, s64 offset64, long secs)
268{
269 ntpdata->time_status &= ~STA_MODE;
270
271 if (secs < MINSEC)
272 return 0;
273
274 if (!(ntpdata->time_status & STA_FLL) && (secs <= MAXSEC))
275 return 0;
276
277 ntpdata->time_status |= STA_MODE;
278
279 return div64_long(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
280}
281
282static void ntp_update_offset(struct ntp_data *ntpdata, long offset)
283{
284 s64 freq_adj, offset64;
285 long secs, real_secs;
286
287 if (!(ntpdata->time_status & STA_PLL))
288 return;
289
290 if (!(ntpdata->time_status & STA_NANO)) {
291 /* Make sure the multiplication below won't overflow */
292 offset = clamp(offset, -USEC_PER_SEC, USEC_PER_SEC);
293 offset *= NSEC_PER_USEC;
294 }
295
296 /* Scale the phase adjustment and clamp to the operating range. */
297 offset = clamp(offset, -MAXPHASE, MAXPHASE);
298
299 /*
300 * Select how the frequency is to be controlled
301 * and in which mode (PLL or FLL).
302 */
303 real_secs = __ktime_get_real_seconds();
304 secs = (long)(real_secs - ntpdata->time_reftime);
305 if (unlikely(ntpdata->time_status & STA_FREQHOLD))
306 secs = 0;
307
308 ntpdata->time_reftime = real_secs;
309
310 offset64 = offset;
311 freq_adj = ntp_update_offset_fll(ntpdata, 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 + ntpdata->time_constant)))
319 secs = 1 << (SHIFT_PLL + 1 + ntpdata->time_constant);
320
321 freq_adj += (offset64 * secs) <<
322 (NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + ntpdata->time_constant));
323
324 freq_adj = min(freq_adj + ntpdata->time_freq, MAXFREQ_SCALED);
325
326 ntpdata->time_freq = max(freq_adj, -MAXFREQ_SCALED);
327
328 ntpdata->time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
329}
330
331static void __ntp_clear(struct ntp_data *ntpdata)
332{
333 /* Stop active adjtime() */
334 ntpdata->time_adjust = 0;
335 ntpdata->time_status |= STA_UNSYNC;
336 ntpdata->time_maxerror = NTP_PHASE_LIMIT;
337 ntpdata->time_esterror = NTP_PHASE_LIMIT;
338
339 ntp_update_frequency(ntpdata);
340
341 ntpdata->tick_length = ntpdata->tick_length_base;
342 ntpdata->time_offset = 0;
343
344 ntpdata->ntp_next_leap_sec = TIME64_MAX;
345 /* Clear PPS state variables */
346 pps_clear(ntpdata);
347}
348
349/**
350 * ntp_clear - Clears the NTP state variables
351 */
352void ntp_clear(void)
353{
354 __ntp_clear(&tk_ntp_data);
355}
356
357
358u64 ntp_tick_length(void)
359{
360 return tk_ntp_data.tick_length;
361}
362
363/**
364 * ntp_get_next_leap - Returns the next leapsecond in CLOCK_REALTIME ktime_t
365 *
366 * Provides the time of the next leapsecond against CLOCK_REALTIME in
367 * a ktime_t format. Returns KTIME_MAX if no leapsecond is pending.
368 */
369ktime_t ntp_get_next_leap(void)
370{
371 struct ntp_data *ntpdata = &tk_ntp_data;
372 ktime_t ret;
373
374 if ((ntpdata->time_state == TIME_INS) && (ntpdata->time_status & STA_INS))
375 return ktime_set(ntpdata->ntp_next_leap_sec, 0);
376 ret = KTIME_MAX;
377 return ret;
378}
379
380/*
381 * This routine handles the overflow of the microsecond field
382 *
383 * The tricky bits of code to handle the accurate clock support
384 * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
385 * They were originally developed for SUN and DEC kernels.
386 * All the kudos should go to Dave for this stuff.
387 *
388 * Also handles leap second processing, and returns leap offset
389 */
390int second_overflow(time64_t secs)
391{
392 struct ntp_data *ntpdata = &tk_ntp_data;
393 s64 delta;
394 int leap = 0;
395 s32 rem;
396
397 /*
398 * Leap second processing. If in leap-insert state at the end of the
399 * day, the system clock is set back one second; if in leap-delete
400 * state, the system clock is set ahead one second.
401 */
402 switch (ntpdata->time_state) {
403 case TIME_OK:
404 if (ntpdata->time_status & STA_INS) {
405 ntpdata->time_state = TIME_INS;
406 div_s64_rem(secs, SECS_PER_DAY, &rem);
407 ntpdata->ntp_next_leap_sec = secs + SECS_PER_DAY - rem;
408 } else if (ntpdata->time_status & STA_DEL) {
409 ntpdata->time_state = TIME_DEL;
410 div_s64_rem(secs + 1, SECS_PER_DAY, &rem);
411 ntpdata->ntp_next_leap_sec = secs + SECS_PER_DAY - rem;
412 }
413 break;
414 case TIME_INS:
415 if (!(ntpdata->time_status & STA_INS)) {
416 ntpdata->ntp_next_leap_sec = TIME64_MAX;
417 ntpdata->time_state = TIME_OK;
418 } else if (secs == ntpdata->ntp_next_leap_sec) {
419 leap = -1;
420 ntpdata->time_state = TIME_OOP;
421 pr_notice("Clock: inserting leap second 23:59:60 UTC\n");
422 }
423 break;
424 case TIME_DEL:
425 if (!(ntpdata->time_status & STA_DEL)) {
426 ntpdata->ntp_next_leap_sec = TIME64_MAX;
427 ntpdata->time_state = TIME_OK;
428 } else if (secs == ntpdata->ntp_next_leap_sec) {
429 leap = 1;
430 ntpdata->ntp_next_leap_sec = TIME64_MAX;
431 ntpdata->time_state = TIME_WAIT;
432 pr_notice("Clock: deleting leap second 23:59:59 UTC\n");
433 }
434 break;
435 case TIME_OOP:
436 ntpdata->ntp_next_leap_sec = TIME64_MAX;
437 ntpdata->time_state = TIME_WAIT;
438 break;
439 case TIME_WAIT:
440 if (!(ntpdata->time_status & (STA_INS | STA_DEL)))
441 ntpdata->time_state = TIME_OK;
442 break;
443 }
444
445 /* Bump the maxerror field */
446 ntpdata->time_maxerror += MAXFREQ / NSEC_PER_USEC;
447 if (ntpdata->time_maxerror > NTP_PHASE_LIMIT) {
448 ntpdata->time_maxerror = NTP_PHASE_LIMIT;
449 ntpdata->time_status |= STA_UNSYNC;
450 }
451
452 /* Compute the phase adjustment for the next second */
453 ntpdata->tick_length = ntpdata->tick_length_base;
454
455 delta = ntp_offset_chunk(ntpdata, ntpdata->time_offset);
456 ntpdata->time_offset -= delta;
457 ntpdata->tick_length += delta;
458
459 /* Check PPS signal */
460 pps_dec_valid(ntpdata);
461
462 if (!ntpdata->time_adjust)
463 goto out;
464
465 if (ntpdata->time_adjust > MAX_TICKADJ) {
466 ntpdata->time_adjust -= MAX_TICKADJ;
467 ntpdata->tick_length += MAX_TICKADJ_SCALED;
468 goto out;
469 }
470
471 if (ntpdata->time_adjust < -MAX_TICKADJ) {
472 ntpdata->time_adjust += MAX_TICKADJ;
473 ntpdata->tick_length -= MAX_TICKADJ_SCALED;
474 goto out;
475 }
476
477 ntpdata->tick_length += (s64)(ntpdata->time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)
478 << NTP_SCALE_SHIFT;
479 ntpdata->time_adjust = 0;
480
481out:
482 return leap;
483}
484
485#if defined(CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC)
486static void sync_hw_clock(struct work_struct *work);
487static DECLARE_WORK(sync_work, sync_hw_clock);
488static struct hrtimer sync_hrtimer;
489#define SYNC_PERIOD_NS (11ULL * 60 * NSEC_PER_SEC)
490
491static enum hrtimer_restart sync_timer_callback(struct hrtimer *timer)
492{
493 queue_work(system_freezable_power_efficient_wq, &sync_work);
494
495 return HRTIMER_NORESTART;
496}
497
498static void sched_sync_hw_clock(unsigned long offset_nsec, bool retry)
499{
500 ktime_t exp = ktime_set(ktime_get_real_seconds(), 0);
501
502 if (retry)
503 exp = ktime_add_ns(exp, 2ULL * NSEC_PER_SEC - offset_nsec);
504 else
505 exp = ktime_add_ns(exp, SYNC_PERIOD_NS - offset_nsec);
506
507 hrtimer_start(&sync_hrtimer, exp, HRTIMER_MODE_ABS);
508}
509
510/*
511 * Check whether @now is correct versus the required time to update the RTC
512 * and calculate the value which needs to be written to the RTC so that the
513 * next seconds increment of the RTC after the write is aligned with the next
514 * seconds increment of clock REALTIME.
515 *
516 * tsched t1 write(t2.tv_sec - 1sec)) t2 RTC increments seconds
517 *
518 * t2.tv_nsec == 0
519 * tsched = t2 - set_offset_nsec
520 * newval = t2 - NSEC_PER_SEC
521 *
522 * ==> neval = tsched + set_offset_nsec - NSEC_PER_SEC
523 *
524 * As the execution of this code is not guaranteed to happen exactly at
525 * tsched this allows it to happen within a fuzzy region:
526 *
527 * abs(now - tsched) < FUZZ
528 *
529 * If @now is not inside the allowed window the function returns false.
530 */
531static inline bool rtc_tv_nsec_ok(unsigned long set_offset_nsec,
532 struct timespec64 *to_set,
533 const struct timespec64 *now)
534{
535 /* Allowed error in tv_nsec, arbitrarily set to 5 jiffies in ns. */
536 const unsigned long TIME_SET_NSEC_FUZZ = TICK_NSEC * 5;
537 struct timespec64 delay = {.tv_sec = -1,
538 .tv_nsec = set_offset_nsec};
539
540 *to_set = timespec64_add(*now, delay);
541
542 if (to_set->tv_nsec < TIME_SET_NSEC_FUZZ) {
543 to_set->tv_nsec = 0;
544 return true;
545 }
546
547 if (to_set->tv_nsec > NSEC_PER_SEC - TIME_SET_NSEC_FUZZ) {
548 to_set->tv_sec++;
549 to_set->tv_nsec = 0;
550 return true;
551 }
552 return false;
553}
554
555#ifdef CONFIG_GENERIC_CMOS_UPDATE
556int __weak update_persistent_clock64(struct timespec64 now64)
557{
558 return -ENODEV;
559}
560#else
561static inline int update_persistent_clock64(struct timespec64 now64)
562{
563 return -ENODEV;
564}
565#endif
566
567#ifdef CONFIG_RTC_SYSTOHC
568/* Save NTP synchronized time to the RTC */
569static int update_rtc(struct timespec64 *to_set, unsigned long *offset_nsec)
570{
571 struct rtc_device *rtc;
572 struct rtc_time tm;
573 int err = -ENODEV;
574
575 rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE);
576 if (!rtc)
577 return -ENODEV;
578
579 if (!rtc->ops || !rtc->ops->set_time)
580 goto out_close;
581
582 /* First call might not have the correct offset */
583 if (*offset_nsec == rtc->set_offset_nsec) {
584 rtc_time64_to_tm(to_set->tv_sec, &tm);
585 err = rtc_set_time(rtc, &tm);
586 } else {
587 /* Store the update offset and let the caller try again */
588 *offset_nsec = rtc->set_offset_nsec;
589 err = -EAGAIN;
590 }
591out_close:
592 rtc_class_close(rtc);
593 return err;
594}
595#else
596static inline int update_rtc(struct timespec64 *to_set, unsigned long *offset_nsec)
597{
598 return -ENODEV;
599}
600#endif
601
602/**
603 * ntp_synced - Tells whether the NTP status is not UNSYNC
604 * Returns: true if not UNSYNC, false otherwise
605 */
606static inline bool ntp_synced(void)
607{
608 return !(tk_ntp_data.time_status & STA_UNSYNC);
609}
610
611/*
612 * If we have an externally synchronized Linux clock, then update RTC clock
613 * accordingly every ~11 minutes. Generally RTCs can only store second
614 * precision, but many RTCs will adjust the phase of their second tick to
615 * match the moment of update. This infrastructure arranges to call to the RTC
616 * set at the correct moment to phase synchronize the RTC second tick over
617 * with the kernel clock.
618 */
619static void sync_hw_clock(struct work_struct *work)
620{
621 /*
622 * The default synchronization offset is 500ms for the deprecated
623 * update_persistent_clock64() under the assumption that it uses
624 * the infamous CMOS clock (MC146818).
625 */
626 static unsigned long offset_nsec = NSEC_PER_SEC / 2;
627 struct timespec64 now, to_set;
628 int res = -EAGAIN;
629
630 /*
631 * Don't update if STA_UNSYNC is set and if ntp_notify_cmos_timer()
632 * managed to schedule the work between the timer firing and the
633 * work being able to rearm the timer. Wait for the timer to expire.
634 */
635 if (!ntp_synced() || hrtimer_is_queued(&sync_hrtimer))
636 return;
637
638 ktime_get_real_ts64(&now);
639 /* If @now is not in the allowed window, try again */
640 if (!rtc_tv_nsec_ok(offset_nsec, &to_set, &now))
641 goto rearm;
642
643 /* Take timezone adjusted RTCs into account */
644 if (persistent_clock_is_local)
645 to_set.tv_sec -= (sys_tz.tz_minuteswest * 60);
646
647 /* Try the legacy RTC first. */
648 res = update_persistent_clock64(to_set);
649 if (res != -ENODEV)
650 goto rearm;
651
652 /* Try the RTC class */
653 res = update_rtc(&to_set, &offset_nsec);
654 if (res == -ENODEV)
655 return;
656rearm:
657 sched_sync_hw_clock(offset_nsec, res != 0);
658}
659
660void ntp_notify_cmos_timer(bool offset_set)
661{
662 /*
663 * If the time jumped (using ADJ_SETOFFSET) cancels sync timer,
664 * which may have been running if the time was synchronized
665 * prior to the ADJ_SETOFFSET call.
666 */
667 if (offset_set)
668 hrtimer_cancel(&sync_hrtimer);
669
670 /*
671 * When the work is currently executed but has not yet the timer
672 * rearmed this queues the work immediately again. No big issue,
673 * just a pointless work scheduled.
674 */
675 if (ntp_synced() && !hrtimer_is_queued(&sync_hrtimer))
676 queue_work(system_freezable_power_efficient_wq, &sync_work);
677}
678
679static void __init ntp_init_cmos_sync(void)
680{
681 hrtimer_init(&sync_hrtimer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
682 sync_hrtimer.function = sync_timer_callback;
683}
684#else /* CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC) */
685static inline void __init ntp_init_cmos_sync(void) { }
686#endif /* !CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC) */
687
688/*
689 * Propagate a new txc->status value into the NTP state:
690 */
691static inline void process_adj_status(struct ntp_data *ntpdata, const struct __kernel_timex *txc)
692{
693 if ((ntpdata->time_status & STA_PLL) && !(txc->status & STA_PLL)) {
694 ntpdata->time_state = TIME_OK;
695 ntpdata->time_status = STA_UNSYNC;
696 ntpdata->ntp_next_leap_sec = TIME64_MAX;
697 /* Restart PPS frequency calibration */
698 pps_reset_freq_interval(ntpdata);
699 }
700
701 /*
702 * If we turn on PLL adjustments then reset the
703 * reference time to current time.
704 */
705 if (!(ntpdata->time_status & STA_PLL) && (txc->status & STA_PLL))
706 ntpdata->time_reftime = __ktime_get_real_seconds();
707
708 /* only set allowed bits */
709 ntpdata->time_status &= STA_RONLY;
710 ntpdata->time_status |= txc->status & ~STA_RONLY;
711}
712
713static inline void process_adjtimex_modes(struct ntp_data *ntpdata, const struct __kernel_timex *txc,
714 s32 *time_tai)
715{
716 if (txc->modes & ADJ_STATUS)
717 process_adj_status(ntpdata, txc);
718
719 if (txc->modes & ADJ_NANO)
720 ntpdata->time_status |= STA_NANO;
721
722 if (txc->modes & ADJ_MICRO)
723 ntpdata->time_status &= ~STA_NANO;
724
725 if (txc->modes & ADJ_FREQUENCY) {
726 ntpdata->time_freq = txc->freq * PPM_SCALE;
727 ntpdata->time_freq = min(ntpdata->time_freq, MAXFREQ_SCALED);
728 ntpdata->time_freq = max(ntpdata->time_freq, -MAXFREQ_SCALED);
729 /* Update pps_freq */
730 pps_set_freq(ntpdata);
731 }
732
733 if (txc->modes & ADJ_MAXERROR)
734 ntpdata->time_maxerror = clamp(txc->maxerror, 0, NTP_PHASE_LIMIT);
735
736 if (txc->modes & ADJ_ESTERROR)
737 ntpdata->time_esterror = clamp(txc->esterror, 0, NTP_PHASE_LIMIT);
738
739 if (txc->modes & ADJ_TIMECONST) {
740 ntpdata->time_constant = clamp(txc->constant, 0, MAXTC);
741 if (!(ntpdata->time_status & STA_NANO))
742 ntpdata->time_constant += 4;
743 ntpdata->time_constant = clamp(ntpdata->time_constant, 0, MAXTC);
744 }
745
746 if (txc->modes & ADJ_TAI && txc->constant >= 0 && txc->constant <= MAX_TAI_OFFSET)
747 *time_tai = txc->constant;
748
749 if (txc->modes & ADJ_OFFSET)
750 ntp_update_offset(ntpdata, txc->offset);
751
752 if (txc->modes & ADJ_TICK)
753 ntpdata->tick_usec = txc->tick;
754
755 if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET))
756 ntp_update_frequency(ntpdata);
757}
758
759/*
760 * adjtimex() mainly allows reading (and writing, if superuser) of
761 * kernel time-keeping variables. used by xntpd.
762 */
763int __do_adjtimex(struct __kernel_timex *txc, const struct timespec64 *ts,
764 s32 *time_tai, struct audit_ntp_data *ad)
765{
766 struct ntp_data *ntpdata = &tk_ntp_data;
767 int result;
768
769 if (txc->modes & ADJ_ADJTIME) {
770 long save_adjust = ntpdata->time_adjust;
771
772 if (!(txc->modes & ADJ_OFFSET_READONLY)) {
773 /* adjtime() is independent from ntp_adjtime() */
774 ntpdata->time_adjust = txc->offset;
775 ntp_update_frequency(ntpdata);
776
777 audit_ntp_set_old(ad, AUDIT_NTP_ADJUST, save_adjust);
778 audit_ntp_set_new(ad, AUDIT_NTP_ADJUST, ntpdata->time_adjust);
779 }
780 txc->offset = save_adjust;
781 } else {
782 /* If there are input parameters, then process them: */
783 if (txc->modes) {
784 audit_ntp_set_old(ad, AUDIT_NTP_OFFSET, ntpdata->time_offset);
785 audit_ntp_set_old(ad, AUDIT_NTP_FREQ, ntpdata->time_freq);
786 audit_ntp_set_old(ad, AUDIT_NTP_STATUS, ntpdata->time_status);
787 audit_ntp_set_old(ad, AUDIT_NTP_TAI, *time_tai);
788 audit_ntp_set_old(ad, AUDIT_NTP_TICK, ntpdata->tick_usec);
789
790 process_adjtimex_modes(ntpdata, txc, time_tai);
791
792 audit_ntp_set_new(ad, AUDIT_NTP_OFFSET, ntpdata->time_offset);
793 audit_ntp_set_new(ad, AUDIT_NTP_FREQ, ntpdata->time_freq);
794 audit_ntp_set_new(ad, AUDIT_NTP_STATUS, ntpdata->time_status);
795 audit_ntp_set_new(ad, AUDIT_NTP_TAI, *time_tai);
796 audit_ntp_set_new(ad, AUDIT_NTP_TICK, ntpdata->tick_usec);
797 }
798
799 txc->offset = shift_right(ntpdata->time_offset * NTP_INTERVAL_FREQ, NTP_SCALE_SHIFT);
800 if (!(ntpdata->time_status & STA_NANO))
801 txc->offset = div_s64(txc->offset, NSEC_PER_USEC);
802 }
803
804 result = ntpdata->time_state;
805 if (is_error_status(ntpdata->time_status))
806 result = TIME_ERROR;
807
808 txc->freq = shift_right((ntpdata->time_freq >> PPM_SCALE_INV_SHIFT) *
809 PPM_SCALE_INV, NTP_SCALE_SHIFT);
810 txc->maxerror = ntpdata->time_maxerror;
811 txc->esterror = ntpdata->time_esterror;
812 txc->status = ntpdata->time_status;
813 txc->constant = ntpdata->time_constant;
814 txc->precision = 1;
815 txc->tolerance = MAXFREQ_SCALED / PPM_SCALE;
816 txc->tick = ntpdata->tick_usec;
817 txc->tai = *time_tai;
818
819 /* Fill PPS status fields */
820 pps_fill_timex(ntpdata, txc);
821
822 txc->time.tv_sec = ts->tv_sec;
823 txc->time.tv_usec = ts->tv_nsec;
824 if (!(ntpdata->time_status & STA_NANO))
825 txc->time.tv_usec = ts->tv_nsec / NSEC_PER_USEC;
826
827 /* Handle leapsec adjustments */
828 if (unlikely(ts->tv_sec >= ntpdata->ntp_next_leap_sec)) {
829 if ((ntpdata->time_state == TIME_INS) && (ntpdata->time_status & STA_INS)) {
830 result = TIME_OOP;
831 txc->tai++;
832 txc->time.tv_sec--;
833 }
834 if ((ntpdata->time_state == TIME_DEL) && (ntpdata->time_status & STA_DEL)) {
835 result = TIME_WAIT;
836 txc->tai--;
837 txc->time.tv_sec++;
838 }
839 if ((ntpdata->time_state == TIME_OOP) && (ts->tv_sec == ntpdata->ntp_next_leap_sec))
840 result = TIME_WAIT;
841 }
842
843 return result;
844}
845
846#ifdef CONFIG_NTP_PPS
847
848/*
849 * struct pps_normtime is basically a struct timespec, but it is
850 * semantically different (and it is the reason why it was invented):
851 * pps_normtime.nsec has a range of ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ]
852 * while timespec.tv_nsec has a range of [0, NSEC_PER_SEC)
853 */
854struct pps_normtime {
855 s64 sec; /* seconds */
856 long nsec; /* nanoseconds */
857};
858
859/*
860 * Normalize the timestamp so that nsec is in the
861 * [ -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ] interval
862 */
863static inline struct pps_normtime pps_normalize_ts(struct timespec64 ts)
864{
865 struct pps_normtime norm = {
866 .sec = ts.tv_sec,
867 .nsec = ts.tv_nsec
868 };
869
870 if (norm.nsec > (NSEC_PER_SEC >> 1)) {
871 norm.nsec -= NSEC_PER_SEC;
872 norm.sec++;
873 }
874
875 return norm;
876}
877
878/* Get current phase correction and jitter */
879static inline long pps_phase_filter_get(struct ntp_data *ntpdata, long *jitter)
880{
881 *jitter = ntpdata->pps_tf[0] - ntpdata->pps_tf[1];
882 if (*jitter < 0)
883 *jitter = -*jitter;
884
885 /* TODO: test various filters */
886 return ntpdata->pps_tf[0];
887}
888
889/* Add the sample to the phase filter */
890static inline void pps_phase_filter_add(struct ntp_data *ntpdata, long err)
891{
892 ntpdata->pps_tf[2] = ntpdata->pps_tf[1];
893 ntpdata->pps_tf[1] = ntpdata->pps_tf[0];
894 ntpdata->pps_tf[0] = err;
895}
896
897/*
898 * Decrease frequency calibration interval length. It is halved after four
899 * consecutive unstable intervals.
900 */
901static inline void pps_dec_freq_interval(struct ntp_data *ntpdata)
902{
903 if (--ntpdata->pps_intcnt <= -PPS_INTCOUNT) {
904 ntpdata->pps_intcnt = -PPS_INTCOUNT;
905 if (ntpdata->pps_shift > PPS_INTMIN) {
906 ntpdata->pps_shift--;
907 ntpdata->pps_intcnt = 0;
908 }
909 }
910}
911
912/*
913 * Increase frequency calibration interval length. It is doubled after
914 * four consecutive stable intervals.
915 */
916static inline void pps_inc_freq_interval(struct ntp_data *ntpdata)
917{
918 if (++ntpdata->pps_intcnt >= PPS_INTCOUNT) {
919 ntpdata->pps_intcnt = PPS_INTCOUNT;
920 if (ntpdata->pps_shift < PPS_INTMAX) {
921 ntpdata->pps_shift++;
922 ntpdata->pps_intcnt = 0;
923 }
924 }
925}
926
927/*
928 * Update clock frequency based on MONOTONIC_RAW clock PPS signal
929 * timestamps
930 *
931 * At the end of the calibration interval the difference between the
932 * first and last MONOTONIC_RAW clock timestamps divided by the length
933 * of the interval becomes the frequency update. If the interval was
934 * too long, the data are discarded.
935 * Returns the difference between old and new frequency values.
936 */
937static long hardpps_update_freq(struct ntp_data *ntpdata, struct pps_normtime freq_norm)
938{
939 long delta, delta_mod;
940 s64 ftemp;
941
942 /* Check if the frequency interval was too long */
943 if (freq_norm.sec > (2 << ntpdata->pps_shift)) {
944 ntpdata->time_status |= STA_PPSERROR;
945 ntpdata->pps_errcnt++;
946 pps_dec_freq_interval(ntpdata);
947 printk_deferred(KERN_ERR "hardpps: PPSERROR: interval too long - %lld s\n",
948 freq_norm.sec);
949 return 0;
950 }
951
952 /*
953 * Here the raw frequency offset and wander (stability) is
954 * calculated. If the wander is less than the wander threshold the
955 * interval is increased; otherwise it is decreased.
956 */
957 ftemp = div_s64(((s64)(-freq_norm.nsec)) << NTP_SCALE_SHIFT,
958 freq_norm.sec);
959 delta = shift_right(ftemp - ntpdata->pps_freq, NTP_SCALE_SHIFT);
960 ntpdata->pps_freq = ftemp;
961 if (delta > PPS_MAXWANDER || delta < -PPS_MAXWANDER) {
962 printk_deferred(KERN_WARNING "hardpps: PPSWANDER: change=%ld\n", delta);
963 ntpdata->time_status |= STA_PPSWANDER;
964 ntpdata->pps_stbcnt++;
965 pps_dec_freq_interval(ntpdata);
966 } else {
967 /* Good sample */
968 pps_inc_freq_interval(ntpdata);
969 }
970
971 /*
972 * The stability metric is calculated as the average of recent
973 * frequency changes, but is used only for performance monitoring
974 */
975 delta_mod = delta;
976 if (delta_mod < 0)
977 delta_mod = -delta_mod;
978 ntpdata->pps_stabil += (div_s64(((s64)delta_mod) << (NTP_SCALE_SHIFT - SHIFT_USEC),
979 NSEC_PER_USEC) - ntpdata->pps_stabil) >> PPS_INTMIN;
980
981 /* If enabled, the system clock frequency is updated */
982 if ((ntpdata->time_status & STA_PPSFREQ) && !(ntpdata->time_status & STA_FREQHOLD)) {
983 ntpdata->time_freq = ntpdata->pps_freq;
984 ntp_update_frequency(ntpdata);
985 }
986
987 return delta;
988}
989
990/* Correct REALTIME clock phase error against PPS signal */
991static void hardpps_update_phase(struct ntp_data *ntpdata, long error)
992{
993 long correction = -error;
994 long jitter;
995
996 /* Add the sample to the median filter */
997 pps_phase_filter_add(ntpdata, correction);
998 correction = pps_phase_filter_get(ntpdata, &jitter);
999
1000 /*
1001 * Nominal jitter is due to PPS signal noise. If it exceeds the
1002 * threshold, the sample is discarded; otherwise, if so enabled,
1003 * the time offset is updated.
1004 */
1005 if (jitter > (ntpdata->pps_jitter << PPS_POPCORN)) {
1006 printk_deferred(KERN_WARNING "hardpps: PPSJITTER: jitter=%ld, limit=%ld\n",
1007 jitter, (ntpdata->pps_jitter << PPS_POPCORN));
1008 ntpdata->time_status |= STA_PPSJITTER;
1009 ntpdata->pps_jitcnt++;
1010 } else if (ntpdata->time_status & STA_PPSTIME) {
1011 /* Correct the time using the phase offset */
1012 ntpdata->time_offset = div_s64(((s64)correction) << NTP_SCALE_SHIFT,
1013 NTP_INTERVAL_FREQ);
1014 /* Cancel running adjtime() */
1015 ntpdata->time_adjust = 0;
1016 }
1017 /* Update jitter */
1018 ntpdata->pps_jitter += (jitter - ntpdata->pps_jitter) >> PPS_INTMIN;
1019}
1020
1021/*
1022 * __hardpps() - discipline CPU clock oscillator to external PPS signal
1023 *
1024 * This routine is called at each PPS signal arrival in order to
1025 * discipline the CPU clock oscillator to the PPS signal. It takes two
1026 * parameters: REALTIME and MONOTONIC_RAW clock timestamps. The former
1027 * is used to correct clock phase error and the latter is used to
1028 * correct the frequency.
1029 *
1030 * This code is based on David Mills's reference nanokernel
1031 * implementation. It was mostly rewritten but keeps the same idea.
1032 */
1033void __hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
1034{
1035 struct pps_normtime pts_norm, freq_norm;
1036 struct ntp_data *ntpdata = &tk_ntp_data;
1037
1038 pts_norm = pps_normalize_ts(*phase_ts);
1039
1040 /* Clear the error bits, they will be set again if needed */
1041 ntpdata->time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
1042
1043 /* indicate signal presence */
1044 ntpdata->time_status |= STA_PPSSIGNAL;
1045 ntpdata->pps_valid = PPS_VALID;
1046
1047 /*
1048 * When called for the first time, just start the frequency
1049 * interval
1050 */
1051 if (unlikely(ntpdata->pps_fbase.tv_sec == 0)) {
1052 ntpdata->pps_fbase = *raw_ts;
1053 return;
1054 }
1055
1056 /* Ok, now we have a base for frequency calculation */
1057 freq_norm = pps_normalize_ts(timespec64_sub(*raw_ts, ntpdata->pps_fbase));
1058
1059 /*
1060 * Check that the signal is in the range
1061 * [1s - MAXFREQ us, 1s + MAXFREQ us], otherwise reject it
1062 */
1063 if ((freq_norm.sec == 0) || (freq_norm.nsec > MAXFREQ * freq_norm.sec) ||
1064 (freq_norm.nsec < -MAXFREQ * freq_norm.sec)) {
1065 ntpdata->time_status |= STA_PPSJITTER;
1066 /* Restart the frequency calibration interval */
1067 ntpdata->pps_fbase = *raw_ts;
1068 printk_deferred(KERN_ERR "hardpps: PPSJITTER: bad pulse\n");
1069 return;
1070 }
1071
1072 /* Signal is ok. Check if the current frequency interval is finished */
1073 if (freq_norm.sec >= (1 << ntpdata->pps_shift)) {
1074 ntpdata->pps_calcnt++;
1075 /* Restart the frequency calibration interval */
1076 ntpdata->pps_fbase = *raw_ts;
1077 hardpps_update_freq(ntpdata, freq_norm);
1078 }
1079
1080 hardpps_update_phase(ntpdata, pts_norm.nsec);
1081
1082}
1083#endif /* CONFIG_NTP_PPS */
1084
1085static int __init ntp_tick_adj_setup(char *str)
1086{
1087 int rc = kstrtos64(str, 0, &tk_ntp_data.ntp_tick_adj);
1088 if (rc)
1089 return rc;
1090
1091 tk_ntp_data.ntp_tick_adj <<= NTP_SCALE_SHIFT;
1092 return 1;
1093}
1094
1095__setup("ntp_tick_adj=", ntp_tick_adj_setup);
1096
1097void __init ntp_init(void)
1098{
1099 ntp_clear();
1100 ntp_init_cmos_sync();
1101}