Line data Source code
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): */
34 : unsigned long tick_usec = USER_TICK_USEC;
35 :
36 : /* SHIFTED_HZ period (nsecs): */
37 : unsigned long tick_nsec;
38 :
39 : static u64 tick_length;
40 : static 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 : */
57 : static int time_state = TIME_OK;
58 :
59 : /* clock status bits: */
60 : static int time_status = STA_UNSYNC;
61 :
62 : /* time adjustment (nsecs): */
63 : static s64 time_offset;
64 :
65 : /* pll time constant: */
66 : static long time_constant = 2;
67 :
68 : /* maximum error (usecs): */
69 : static long time_maxerror = NTP_PHASE_LIMIT;
70 :
71 : /* estimated error (usecs): */
72 : static long time_esterror = NTP_PHASE_LIMIT;
73 :
74 : /* frequency offset (scaled nsecs/secs): */
75 : static s64 time_freq;
76 :
77 : /* time at last adjustment (secs): */
78 : static time64_t time_reftime;
79 :
80 : static long time_adjust;
81 :
82 : /* constant (boot-param configurable) NTP tick adjustment (upscaled) */
83 : static s64 ntp_tick_adj;
84 :
85 : /* second value of the next pending leapsecond, or TIME64_MAX if no leap */
86 : static 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 :
104 : static int pps_valid; /* signal watchdog counter */
105 : static long pps_tf[3]; /* phase median filter */
106 : static long pps_jitter; /* current jitter (ns) */
107 : static struct timespec64 pps_fbase; /* beginning of the last freq interval */
108 : static int pps_shift; /* current interval duration (s) (shift) */
109 : static int pps_intcnt; /* interval counter */
110 : static s64 pps_freq; /* frequency offset (scaled ns/s) */
111 : static long pps_stabil; /* current stability (scaled ns/s) */
112 :
113 : /*
114 : * PPS signal quality monitors
115 : */
116 : static long pps_calcnt; /* calibration intervals */
117 : static long pps_jitcnt; /* jitter limit exceeded */
118 : static long pps_stbcnt; /* stability limit exceeded */
119 : static 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 : */
125 : static 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 :
133 : static 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 : */
144 : static 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 : */
158 : static 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 :
169 : static inline void pps_set_freq(s64 freq)
170 : {
171 : pps_freq = freq;
172 : }
173 :
174 : static 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 :
193 : static 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 :
210 : static inline s64 ntp_offset_chunk(s64 offset)
211 : {
212 0 : return shift_right(offset, SHIFT_PLL + time_constant);
213 : }
214 :
215 : static inline void pps_reset_freq_interval(void) {}
216 : static inline void pps_clear(void) {}
217 : static inline void pps_dec_valid(void) {}
218 : static inline void pps_set_freq(s64 freq) {}
219 :
220 : static inline int is_error_status(int status)
221 : {
222 0 : return status & (STA_UNSYNC|STA_CLOCKERR);
223 : }
224 :
225 : static inline void pps_fill_timex(struct __kernel_timex *txc)
226 : {
227 : /* PPS is not implemented, so these are zero */
228 0 : txc->ppsfreq = 0;
229 0 : txc->jitter = 0;
230 0 : txc->shift = 0;
231 0 : txc->stabil = 0;
232 0 : txc->jitcnt = 0;
233 0 : txc->calcnt = 0;
234 0 : txc->errcnt = 0;
235 0 : 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 : */
245 : static 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 : */
259 2 : static void ntp_update_frequency(void)
260 : {
261 : u64 second_length;
262 : u64 new_base;
263 :
264 2 : second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
265 : << NTP_SCALE_SHIFT;
266 :
267 2 : second_length += ntp_tick_adj;
268 2 : second_length += time_freq;
269 :
270 2 : tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT;
271 2 : 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 2 : tick_length += new_base - tick_length_base;
278 2 : tick_length_base = new_base;
279 2 : }
280 :
281 : static inline s64 ntp_update_offset_fll(s64 offset64, long secs)
282 : {
283 0 : time_status &= ~STA_MODE;
284 :
285 0 : if (secs < MINSEC)
286 : return 0;
287 :
288 0 : if (!(time_status & STA_FLL) && (secs <= MAXSEC))
289 : return 0;
290 :
291 0 : time_status |= STA_MODE;
292 :
293 0 : return div64_long(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
294 : }
295 :
296 0 : static void ntp_update_offset(long offset)
297 : {
298 : s64 freq_adj;
299 : s64 offset64;
300 : long secs;
301 :
302 0 : if (!(time_status & STA_PLL))
303 : return;
304 :
305 0 : if (!(time_status & STA_NANO)) {
306 : /* Make sure the multiplication below won't overflow */
307 0 : offset = clamp(offset, -USEC_PER_SEC, USEC_PER_SEC);
308 0 : offset *= NSEC_PER_USEC;
309 : }
310 :
311 : /*
312 : * Scale the phase adjustment and
313 : * clamp to the operating range.
314 : */
315 0 : 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 0 : secs = (long)(__ktime_get_real_seconds() - time_reftime);
322 0 : if (unlikely(time_status & STA_FREQHOLD))
323 0 : secs = 0;
324 :
325 0 : time_reftime = __ktime_get_real_seconds();
326 :
327 0 : offset64 = offset;
328 0 : 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 0 : if (unlikely(secs > 1 << (SHIFT_PLL + 1 + time_constant)))
336 0 : secs = 1 << (SHIFT_PLL + 1 + time_constant);
337 :
338 0 : freq_adj += (offset64 * secs) <<
339 0 : (NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant));
340 :
341 0 : freq_adj = min(freq_adj + time_freq, MAXFREQ_SCALED);
342 :
343 0 : time_freq = max(freq_adj, -MAXFREQ_SCALED);
344 :
345 0 : time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
346 : }
347 :
348 : /**
349 : * ntp_clear - Clears the NTP state variables
350 : */
351 2 : void ntp_clear(void)
352 : {
353 2 : time_adjust = 0; /* stop active adjtime() */
354 2 : time_status |= STA_UNSYNC;
355 2 : time_maxerror = NTP_PHASE_LIMIT;
356 2 : time_esterror = NTP_PHASE_LIMIT;
357 :
358 2 : ntp_update_frequency();
359 :
360 2 : tick_length = tick_length_base;
361 2 : time_offset = 0;
362 :
363 2 : ntp_next_leap_sec = TIME64_MAX;
364 : /* Clear PPS state variables */
365 : pps_clear();
366 2 : }
367 :
368 :
369 8 : u64 ntp_tick_length(void)
370 : {
371 8 : 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 : */
380 6 : ktime_t ntp_get_next_leap(void)
381 : {
382 : ktime_t ret;
383 :
384 6 : if ((time_state == TIME_INS) && (time_status & STA_INS))
385 0 : 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 : */
400 0 : int second_overflow(time64_t secs)
401 : {
402 : s64 delta;
403 0 : 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 0 : switch (time_state) {
412 : case TIME_OK:
413 0 : if (time_status & STA_INS) {
414 0 : time_state = TIME_INS;
415 0 : div_s64_rem(secs, SECS_PER_DAY, &rem);
416 0 : ntp_next_leap_sec = secs + SECS_PER_DAY - rem;
417 0 : } else if (time_status & STA_DEL) {
418 0 : time_state = TIME_DEL;
419 0 : div_s64_rem(secs + 1, SECS_PER_DAY, &rem);
420 0 : ntp_next_leap_sec = secs + SECS_PER_DAY - rem;
421 : }
422 : break;
423 : case TIME_INS:
424 0 : if (!(time_status & STA_INS)) {
425 0 : ntp_next_leap_sec = TIME64_MAX;
426 0 : time_state = TIME_OK;
427 0 : } else if (secs == ntp_next_leap_sec) {
428 0 : leap = -1;
429 0 : time_state = TIME_OOP;
430 0 : printk(KERN_NOTICE
431 : "Clock: inserting leap second 23:59:60 UTC\n");
432 : }
433 : break;
434 : case TIME_DEL:
435 0 : if (!(time_status & STA_DEL)) {
436 0 : ntp_next_leap_sec = TIME64_MAX;
437 0 : time_state = TIME_OK;
438 0 : } else if (secs == ntp_next_leap_sec) {
439 0 : leap = 1;
440 0 : ntp_next_leap_sec = TIME64_MAX;
441 0 : time_state = TIME_WAIT;
442 0 : printk(KERN_NOTICE
443 : "Clock: deleting leap second 23:59:59 UTC\n");
444 : }
445 : break;
446 : case TIME_OOP:
447 0 : ntp_next_leap_sec = TIME64_MAX;
448 0 : time_state = TIME_WAIT;
449 0 : break;
450 : case TIME_WAIT:
451 0 : if (!(time_status & (STA_INS | STA_DEL)))
452 0 : time_state = TIME_OK;
453 : break;
454 : }
455 :
456 :
457 : /* Bump the maxerror field */
458 0 : time_maxerror += MAXFREQ / NSEC_PER_USEC;
459 0 : if (time_maxerror > NTP_PHASE_LIMIT) {
460 0 : time_maxerror = NTP_PHASE_LIMIT;
461 0 : time_status |= STA_UNSYNC;
462 : }
463 :
464 : /* Compute the phase adjustment for the next second */
465 0 : tick_length = tick_length_base;
466 :
467 0 : delta = ntp_offset_chunk(time_offset);
468 0 : time_offset -= delta;
469 0 : tick_length += delta;
470 :
471 : /* Check PPS signal */
472 : pps_dec_valid();
473 :
474 0 : if (!time_adjust)
475 : goto out;
476 :
477 0 : if (time_adjust > MAX_TICKADJ) {
478 0 : time_adjust -= MAX_TICKADJ;
479 0 : tick_length += MAX_TICKADJ_SCALED;
480 0 : goto out;
481 : }
482 :
483 0 : if (time_adjust < -MAX_TICKADJ) {
484 0 : time_adjust += MAX_TICKADJ;
485 0 : tick_length -= MAX_TICKADJ_SCALED;
486 0 : goto out;
487 : }
488 :
489 0 : tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)
490 0 : << NTP_SCALE_SHIFT;
491 0 : time_adjust = 0;
492 :
493 : out:
494 0 : return leap;
495 : }
496 :
497 : #if defined(CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC)
498 : static void sync_hw_clock(struct work_struct *work);
499 : static DECLARE_WORK(sync_work, sync_hw_clock);
500 : static struct hrtimer sync_hrtimer;
501 : #define SYNC_PERIOD_NS (11ULL * 60 * NSEC_PER_SEC)
502 :
503 : static enum hrtimer_restart sync_timer_callback(struct hrtimer *timer)
504 : {
505 : queue_work(system_freezable_power_efficient_wq, &sync_work);
506 :
507 : return HRTIMER_NORESTART;
508 : }
509 :
510 : static void sched_sync_hw_clock(unsigned long offset_nsec, bool retry)
511 : {
512 : ktime_t exp = ktime_set(ktime_get_real_seconds(), 0);
513 :
514 : if (retry)
515 : exp = ktime_add_ns(exp, 2ULL * NSEC_PER_SEC - offset_nsec);
516 : else
517 : exp = ktime_add_ns(exp, SYNC_PERIOD_NS - offset_nsec);
518 :
519 : hrtimer_start(&sync_hrtimer, exp, HRTIMER_MODE_ABS);
520 : }
521 :
522 : /*
523 : * Check whether @now is correct versus the required time to update the RTC
524 : * and calculate the value which needs to be written to the RTC so that the
525 : * next seconds increment of the RTC after the write is aligned with the next
526 : * seconds increment of clock REALTIME.
527 : *
528 : * tsched t1 write(t2.tv_sec - 1sec)) t2 RTC increments seconds
529 : *
530 : * t2.tv_nsec == 0
531 : * tsched = t2 - set_offset_nsec
532 : * newval = t2 - NSEC_PER_SEC
533 : *
534 : * ==> neval = tsched + set_offset_nsec - NSEC_PER_SEC
535 : *
536 : * As the execution of this code is not guaranteed to happen exactly at
537 : * tsched this allows it to happen within a fuzzy region:
538 : *
539 : * abs(now - tsched) < FUZZ
540 : *
541 : * If @now is not inside the allowed window the function returns false.
542 : */
543 : static inline bool rtc_tv_nsec_ok(unsigned long set_offset_nsec,
544 : struct timespec64 *to_set,
545 : const struct timespec64 *now)
546 : {
547 : /* Allowed error in tv_nsec, arbitrarily set to 5 jiffies in ns. */
548 : const unsigned long TIME_SET_NSEC_FUZZ = TICK_NSEC * 5;
549 : struct timespec64 delay = {.tv_sec = -1,
550 : .tv_nsec = set_offset_nsec};
551 :
552 : *to_set = timespec64_add(*now, delay);
553 :
554 : if (to_set->tv_nsec < TIME_SET_NSEC_FUZZ) {
555 : to_set->tv_nsec = 0;
556 : return true;
557 : }
558 :
559 : if (to_set->tv_nsec > NSEC_PER_SEC - TIME_SET_NSEC_FUZZ) {
560 : to_set->tv_sec++;
561 : to_set->tv_nsec = 0;
562 : return true;
563 : }
564 : return false;
565 : }
566 :
567 : #ifdef CONFIG_GENERIC_CMOS_UPDATE
568 : int __weak update_persistent_clock64(struct timespec64 now64)
569 : {
570 : return -ENODEV;
571 : }
572 : #else
573 : static inline int update_persistent_clock64(struct timespec64 now64)
574 : {
575 : return -ENODEV;
576 : }
577 : #endif
578 :
579 : #ifdef CONFIG_RTC_SYSTOHC
580 : /* Save NTP synchronized time to the RTC */
581 : static int update_rtc(struct timespec64 *to_set, unsigned long *offset_nsec)
582 : {
583 : struct rtc_device *rtc;
584 : struct rtc_time tm;
585 : int err = -ENODEV;
586 :
587 : rtc = rtc_class_open(CONFIG_RTC_SYSTOHC_DEVICE);
588 : if (!rtc)
589 : return -ENODEV;
590 :
591 : if (!rtc->ops || !rtc->ops->set_time)
592 : goto out_close;
593 :
594 : /* First call might not have the correct offset */
595 : if (*offset_nsec == rtc->set_offset_nsec) {
596 : rtc_time64_to_tm(to_set->tv_sec, &tm);
597 : err = rtc_set_time(rtc, &tm);
598 : } else {
599 : /* Store the update offset and let the caller try again */
600 : *offset_nsec = rtc->set_offset_nsec;
601 : err = -EAGAIN;
602 : }
603 : out_close:
604 : rtc_class_close(rtc);
605 : return err;
606 : }
607 : #else
608 : static inline int update_rtc(struct timespec64 *to_set, unsigned long *offset_nsec)
609 : {
610 : return -ENODEV;
611 : }
612 : #endif
613 :
614 : /*
615 : * If we have an externally synchronized Linux clock, then update RTC clock
616 : * accordingly every ~11 minutes. Generally RTCs can only store second
617 : * precision, but many RTCs will adjust the phase of their second tick to
618 : * match the moment of update. This infrastructure arranges to call to the RTC
619 : * set at the correct moment to phase synchronize the RTC second tick over
620 : * with the kernel clock.
621 : */
622 : static void sync_hw_clock(struct work_struct *work)
623 : {
624 : /*
625 : * The default synchronization offset is 500ms for the deprecated
626 : * update_persistent_clock64() under the assumption that it uses
627 : * the infamous CMOS clock (MC146818).
628 : */
629 : static unsigned long offset_nsec = NSEC_PER_SEC / 2;
630 : struct timespec64 now, to_set;
631 : int res = -EAGAIN;
632 :
633 : /*
634 : * Don't update if STA_UNSYNC is set and if ntp_notify_cmos_timer()
635 : * managed to schedule the work between the timer firing and the
636 : * work being able to rearm the timer. Wait for the timer to expire.
637 : */
638 : if (!ntp_synced() || hrtimer_is_queued(&sync_hrtimer))
639 : return;
640 :
641 : ktime_get_real_ts64(&now);
642 : /* If @now is not in the allowed window, try again */
643 : if (!rtc_tv_nsec_ok(offset_nsec, &to_set, &now))
644 : goto rearm;
645 :
646 : /* Take timezone adjusted RTCs into account */
647 : if (persistent_clock_is_local)
648 : to_set.tv_sec -= (sys_tz.tz_minuteswest * 60);
649 :
650 : /* Try the legacy RTC first. */
651 : res = update_persistent_clock64(to_set);
652 : if (res != -ENODEV)
653 : goto rearm;
654 :
655 : /* Try the RTC class */
656 : res = update_rtc(&to_set, &offset_nsec);
657 : if (res == -ENODEV)
658 : return;
659 : rearm:
660 : sched_sync_hw_clock(offset_nsec, res != 0);
661 : }
662 :
663 : void ntp_notify_cmos_timer(void)
664 : {
665 : /*
666 : * When the work is currently executed but has not yet the timer
667 : * rearmed this queues the work immediately again. No big issue,
668 : * just a pointless work scheduled.
669 : */
670 : if (ntp_synced() && !hrtimer_is_queued(&sync_hrtimer))
671 : queue_work(system_freezable_power_efficient_wq, &sync_work);
672 : }
673 :
674 : static void __init ntp_init_cmos_sync(void)
675 : {
676 : hrtimer_init(&sync_hrtimer, CLOCK_REALTIME, HRTIMER_MODE_ABS);
677 : sync_hrtimer.function = sync_timer_callback;
678 : }
679 : #else /* CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC) */
680 : static inline void __init ntp_init_cmos_sync(void) { }
681 : #endif /* !CONFIG_GENERIC_CMOS_UPDATE) || defined(CONFIG_RTC_SYSTOHC) */
682 :
683 : /*
684 : * Propagate a new txc->status value into the NTP state:
685 : */
686 0 : static inline void process_adj_status(const struct __kernel_timex *txc)
687 : {
688 0 : if ((time_status & STA_PLL) && !(txc->status & STA_PLL)) {
689 0 : time_state = TIME_OK;
690 0 : time_status = STA_UNSYNC;
691 0 : ntp_next_leap_sec = TIME64_MAX;
692 : /* restart PPS frequency calibration */
693 : pps_reset_freq_interval();
694 : }
695 :
696 : /*
697 : * If we turn on PLL adjustments then reset the
698 : * reference time to current time.
699 : */
700 0 : if (!(time_status & STA_PLL) && (txc->status & STA_PLL))
701 0 : time_reftime = __ktime_get_real_seconds();
702 :
703 : /* only set allowed bits */
704 0 : time_status &= STA_RONLY;
705 0 : time_status |= txc->status & ~STA_RONLY;
706 0 : }
707 :
708 :
709 0 : static inline void process_adjtimex_modes(const struct __kernel_timex *txc,
710 : s32 *time_tai)
711 : {
712 0 : if (txc->modes & ADJ_STATUS)
713 0 : process_adj_status(txc);
714 :
715 0 : if (txc->modes & ADJ_NANO)
716 0 : time_status |= STA_NANO;
717 :
718 0 : if (txc->modes & ADJ_MICRO)
719 0 : time_status &= ~STA_NANO;
720 :
721 0 : if (txc->modes & ADJ_FREQUENCY) {
722 0 : time_freq = txc->freq * PPM_SCALE;
723 0 : time_freq = min(time_freq, MAXFREQ_SCALED);
724 0 : time_freq = max(time_freq, -MAXFREQ_SCALED);
725 : /* update pps_freq */
726 0 : pps_set_freq(time_freq);
727 : }
728 :
729 0 : if (txc->modes & ADJ_MAXERROR)
730 0 : time_maxerror = txc->maxerror;
731 :
732 0 : if (txc->modes & ADJ_ESTERROR)
733 0 : time_esterror = txc->esterror;
734 :
735 0 : if (txc->modes & ADJ_TIMECONST) {
736 0 : time_constant = txc->constant;
737 0 : if (!(time_status & STA_NANO))
738 0 : time_constant += 4;
739 0 : time_constant = min(time_constant, (long)MAXTC);
740 0 : time_constant = max(time_constant, 0l);
741 : }
742 :
743 0 : if (txc->modes & ADJ_TAI &&
744 0 : txc->constant >= 0 && txc->constant <= MAX_TAI_OFFSET)
745 0 : *time_tai = txc->constant;
746 :
747 0 : if (txc->modes & ADJ_OFFSET)
748 0 : ntp_update_offset(txc->offset);
749 :
750 0 : if (txc->modes & ADJ_TICK)
751 0 : tick_usec = txc->tick;
752 :
753 0 : if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET))
754 0 : ntp_update_frequency();
755 0 : }
756 :
757 :
758 : /*
759 : * adjtimex mainly allows reading (and writing, if superuser) of
760 : * kernel time-keeping variables. used by xntpd.
761 : */
762 0 : int __do_adjtimex(struct __kernel_timex *txc, const struct timespec64 *ts,
763 : s32 *time_tai, struct audit_ntp_data *ad)
764 : {
765 : int result;
766 :
767 0 : if (txc->modes & ADJ_ADJTIME) {
768 0 : long save_adjust = time_adjust;
769 :
770 0 : if (!(txc->modes & ADJ_OFFSET_READONLY)) {
771 : /* adjtime() is independent from ntp_adjtime() */
772 0 : time_adjust = txc->offset;
773 0 : ntp_update_frequency();
774 :
775 0 : audit_ntp_set_old(ad, AUDIT_NTP_ADJUST, save_adjust);
776 0 : audit_ntp_set_new(ad, AUDIT_NTP_ADJUST, time_adjust);
777 : }
778 0 : txc->offset = save_adjust;
779 : } else {
780 : /* If there are input parameters, then process them: */
781 0 : if (txc->modes) {
782 0 : audit_ntp_set_old(ad, AUDIT_NTP_OFFSET, time_offset);
783 0 : audit_ntp_set_old(ad, AUDIT_NTP_FREQ, time_freq);
784 0 : audit_ntp_set_old(ad, AUDIT_NTP_STATUS, time_status);
785 0 : audit_ntp_set_old(ad, AUDIT_NTP_TAI, *time_tai);
786 0 : audit_ntp_set_old(ad, AUDIT_NTP_TICK, tick_usec);
787 :
788 0 : process_adjtimex_modes(txc, time_tai);
789 :
790 0 : audit_ntp_set_new(ad, AUDIT_NTP_OFFSET, time_offset);
791 0 : audit_ntp_set_new(ad, AUDIT_NTP_FREQ, time_freq);
792 0 : audit_ntp_set_new(ad, AUDIT_NTP_STATUS, time_status);
793 0 : audit_ntp_set_new(ad, AUDIT_NTP_TAI, *time_tai);
794 0 : audit_ntp_set_new(ad, AUDIT_NTP_TICK, tick_usec);
795 : }
796 :
797 0 : txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
798 : NTP_SCALE_SHIFT);
799 0 : if (!(time_status & STA_NANO))
800 0 : txc->offset = (u32)txc->offset / NSEC_PER_USEC;
801 : }
802 :
803 0 : result = time_state; /* mostly `TIME_OK' */
804 : /* check for errors */
805 0 : if (is_error_status(time_status))
806 0 : result = TIME_ERROR;
807 :
808 0 : txc->freq = shift_right((time_freq >> PPM_SCALE_INV_SHIFT) *
809 : PPM_SCALE_INV, NTP_SCALE_SHIFT);
810 0 : txc->maxerror = time_maxerror;
811 0 : txc->esterror = time_esterror;
812 0 : txc->status = time_status;
813 0 : txc->constant = time_constant;
814 0 : txc->precision = 1;
815 0 : txc->tolerance = MAXFREQ_SCALED / PPM_SCALE;
816 0 : txc->tick = tick_usec;
817 0 : txc->tai = *time_tai;
818 :
819 : /* fill PPS status fields */
820 0 : pps_fill_timex(txc);
821 :
822 0 : txc->time.tv_sec = ts->tv_sec;
823 0 : txc->time.tv_usec = ts->tv_nsec;
824 0 : if (!(time_status & STA_NANO))
825 0 : txc->time.tv_usec = ts->tv_nsec / NSEC_PER_USEC;
826 :
827 : /* Handle leapsec adjustments */
828 0 : if (unlikely(ts->tv_sec >= ntp_next_leap_sec)) {
829 0 : if ((time_state == TIME_INS) && (time_status & STA_INS)) {
830 0 : result = TIME_OOP;
831 0 : txc->tai++;
832 0 : txc->time.tv_sec--;
833 : }
834 0 : if ((time_state == TIME_DEL) && (time_status & STA_DEL)) {
835 0 : result = TIME_WAIT;
836 0 : txc->tai--;
837 0 : txc->time.tv_sec++;
838 : }
839 0 : if ((time_state == TIME_OOP) &&
840 0 : (ts->tv_sec == ntp_next_leap_sec)) {
841 0 : result = TIME_WAIT;
842 : }
843 : }
844 :
845 0 : return result;
846 : }
847 :
848 : #ifdef CONFIG_NTP_PPS
849 :
850 : /* actually struct pps_normtime is good old struct timespec, but it is
851 : * semantically different (and it is the reason why it was invented):
852 : * pps_normtime.nsec has a range of ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ]
853 : * while timespec.tv_nsec has a range of [0, NSEC_PER_SEC) */
854 : struct pps_normtime {
855 : s64 sec; /* seconds */
856 : long nsec; /* nanoseconds */
857 : };
858 :
859 : /* normalize the timestamp so that nsec is in the
860 : ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ] interval */
861 : static inline struct pps_normtime pps_normalize_ts(struct timespec64 ts)
862 : {
863 : struct pps_normtime norm = {
864 : .sec = ts.tv_sec,
865 : .nsec = ts.tv_nsec
866 : };
867 :
868 : if (norm.nsec > (NSEC_PER_SEC >> 1)) {
869 : norm.nsec -= NSEC_PER_SEC;
870 : norm.sec++;
871 : }
872 :
873 : return norm;
874 : }
875 :
876 : /* get current phase correction and jitter */
877 : static inline long pps_phase_filter_get(long *jitter)
878 : {
879 : *jitter = pps_tf[0] - pps_tf[1];
880 : if (*jitter < 0)
881 : *jitter = -*jitter;
882 :
883 : /* TODO: test various filters */
884 : return pps_tf[0];
885 : }
886 :
887 : /* add the sample to the phase filter */
888 : static inline void pps_phase_filter_add(long err)
889 : {
890 : pps_tf[2] = pps_tf[1];
891 : pps_tf[1] = pps_tf[0];
892 : pps_tf[0] = err;
893 : }
894 :
895 : /* decrease frequency calibration interval length.
896 : * It is halved after four consecutive unstable intervals.
897 : */
898 : static inline void pps_dec_freq_interval(void)
899 : {
900 : if (--pps_intcnt <= -PPS_INTCOUNT) {
901 : pps_intcnt = -PPS_INTCOUNT;
902 : if (pps_shift > PPS_INTMIN) {
903 : pps_shift--;
904 : pps_intcnt = 0;
905 : }
906 : }
907 : }
908 :
909 : /* increase frequency calibration interval length.
910 : * It is doubled after four consecutive stable intervals.
911 : */
912 : static inline void pps_inc_freq_interval(void)
913 : {
914 : if (++pps_intcnt >= PPS_INTCOUNT) {
915 : pps_intcnt = PPS_INTCOUNT;
916 : if (pps_shift < PPS_INTMAX) {
917 : pps_shift++;
918 : pps_intcnt = 0;
919 : }
920 : }
921 : }
922 :
923 : /* update clock frequency based on MONOTONIC_RAW clock PPS signal
924 : * timestamps
925 : *
926 : * At the end of the calibration interval the difference between the
927 : * first and last MONOTONIC_RAW clock timestamps divided by the length
928 : * of the interval becomes the frequency update. If the interval was
929 : * too long, the data are discarded.
930 : * Returns the difference between old and new frequency values.
931 : */
932 : static long hardpps_update_freq(struct pps_normtime freq_norm)
933 : {
934 : long delta, delta_mod;
935 : s64 ftemp;
936 :
937 : /* check if the frequency interval was too long */
938 : if (freq_norm.sec > (2 << pps_shift)) {
939 : time_status |= STA_PPSERROR;
940 : pps_errcnt++;
941 : pps_dec_freq_interval();
942 : printk_deferred(KERN_ERR
943 : "hardpps: PPSERROR: interval too long - %lld s\n",
944 : freq_norm.sec);
945 : return 0;
946 : }
947 :
948 : /* here the raw frequency offset and wander (stability) is
949 : * calculated. If the wander is less than the wander threshold
950 : * the interval is increased; otherwise it is decreased.
951 : */
952 : ftemp = div_s64(((s64)(-freq_norm.nsec)) << NTP_SCALE_SHIFT,
953 : freq_norm.sec);
954 : delta = shift_right(ftemp - pps_freq, NTP_SCALE_SHIFT);
955 : pps_freq = ftemp;
956 : if (delta > PPS_MAXWANDER || delta < -PPS_MAXWANDER) {
957 : printk_deferred(KERN_WARNING
958 : "hardpps: PPSWANDER: change=%ld\n", delta);
959 : time_status |= STA_PPSWANDER;
960 : pps_stbcnt++;
961 : pps_dec_freq_interval();
962 : } else { /* good sample */
963 : pps_inc_freq_interval();
964 : }
965 :
966 : /* the stability metric is calculated as the average of recent
967 : * frequency changes, but is used only for performance
968 : * monitoring
969 : */
970 : delta_mod = delta;
971 : if (delta_mod < 0)
972 : delta_mod = -delta_mod;
973 : pps_stabil += (div_s64(((s64)delta_mod) <<
974 : (NTP_SCALE_SHIFT - SHIFT_USEC),
975 : NSEC_PER_USEC) - pps_stabil) >> PPS_INTMIN;
976 :
977 : /* if enabled, the system clock frequency is updated */
978 : if ((time_status & STA_PPSFREQ) != 0 &&
979 : (time_status & STA_FREQHOLD) == 0) {
980 : time_freq = pps_freq;
981 : ntp_update_frequency();
982 : }
983 :
984 : return delta;
985 : }
986 :
987 : /* correct REALTIME clock phase error against PPS signal */
988 : static void hardpps_update_phase(long error)
989 : {
990 : long correction = -error;
991 : long jitter;
992 :
993 : /* add the sample to the median filter */
994 : pps_phase_filter_add(correction);
995 : correction = pps_phase_filter_get(&jitter);
996 :
997 : /* Nominal jitter is due to PPS signal noise. If it exceeds the
998 : * threshold, the sample is discarded; otherwise, if so enabled,
999 : * the time offset is updated.
1000 : */
1001 : if (jitter > (pps_jitter << PPS_POPCORN)) {
1002 : printk_deferred(KERN_WARNING
1003 : "hardpps: PPSJITTER: jitter=%ld, limit=%ld\n",
1004 : jitter, (pps_jitter << PPS_POPCORN));
1005 : time_status |= STA_PPSJITTER;
1006 : pps_jitcnt++;
1007 : } else if (time_status & STA_PPSTIME) {
1008 : /* correct the time using the phase offset */
1009 : time_offset = div_s64(((s64)correction) << NTP_SCALE_SHIFT,
1010 : NTP_INTERVAL_FREQ);
1011 : /* cancel running adjtime() */
1012 : time_adjust = 0;
1013 : }
1014 : /* update jitter */
1015 : pps_jitter += (jitter - pps_jitter) >> PPS_INTMIN;
1016 : }
1017 :
1018 : /*
1019 : * __hardpps() - discipline CPU clock oscillator to external PPS signal
1020 : *
1021 : * This routine is called at each PPS signal arrival in order to
1022 : * discipline the CPU clock oscillator to the PPS signal. It takes two
1023 : * parameters: REALTIME and MONOTONIC_RAW clock timestamps. The former
1024 : * is used to correct clock phase error and the latter is used to
1025 : * correct the frequency.
1026 : *
1027 : * This code is based on David Mills's reference nanokernel
1028 : * implementation. It was mostly rewritten but keeps the same idea.
1029 : */
1030 : void __hardpps(const struct timespec64 *phase_ts, const struct timespec64 *raw_ts)
1031 : {
1032 : struct pps_normtime pts_norm, freq_norm;
1033 :
1034 : pts_norm = pps_normalize_ts(*phase_ts);
1035 :
1036 : /* clear the error bits, they will be set again if needed */
1037 : time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
1038 :
1039 : /* indicate signal presence */
1040 : time_status |= STA_PPSSIGNAL;
1041 : pps_valid = PPS_VALID;
1042 :
1043 : /* when called for the first time,
1044 : * just start the frequency interval */
1045 : if (unlikely(pps_fbase.tv_sec == 0)) {
1046 : pps_fbase = *raw_ts;
1047 : return;
1048 : }
1049 :
1050 : /* ok, now we have a base for frequency calculation */
1051 : freq_norm = pps_normalize_ts(timespec64_sub(*raw_ts, pps_fbase));
1052 :
1053 : /* check that the signal is in the range
1054 : * [1s - MAXFREQ us, 1s + MAXFREQ us], otherwise reject it */
1055 : if ((freq_norm.sec == 0) ||
1056 : (freq_norm.nsec > MAXFREQ * freq_norm.sec) ||
1057 : (freq_norm.nsec < -MAXFREQ * freq_norm.sec)) {
1058 : time_status |= STA_PPSJITTER;
1059 : /* restart the frequency calibration interval */
1060 : pps_fbase = *raw_ts;
1061 : printk_deferred(KERN_ERR "hardpps: PPSJITTER: bad pulse\n");
1062 : return;
1063 : }
1064 :
1065 : /* signal is ok */
1066 :
1067 : /* check if the current frequency interval is finished */
1068 : if (freq_norm.sec >= (1 << pps_shift)) {
1069 : pps_calcnt++;
1070 : /* restart the frequency calibration interval */
1071 : pps_fbase = *raw_ts;
1072 : hardpps_update_freq(freq_norm);
1073 : }
1074 :
1075 : hardpps_update_phase(pts_norm.nsec);
1076 :
1077 : }
1078 : #endif /* CONFIG_NTP_PPS */
1079 :
1080 0 : static int __init ntp_tick_adj_setup(char *str)
1081 : {
1082 0 : int rc = kstrtos64(str, 0, &ntp_tick_adj);
1083 0 : if (rc)
1084 : return rc;
1085 :
1086 0 : ntp_tick_adj <<= NTP_SCALE_SHIFT;
1087 0 : return 1;
1088 : }
1089 :
1090 : __setup("ntp_tick_adj=", ntp_tick_adj_setup);
1091 :
1092 1 : void __init ntp_init(void)
1093 : {
1094 1 : ntp_clear();
1095 : ntp_init_cmos_sync();
1096 1 : }
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