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