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