blob: 70b33abcc7bb0e92762b05af6c6ceaa1be75cd38 [file] [log] [blame]
john stultz4c7ee8d2006-09-30 23:28:22 -07001/*
john stultz4c7ee8d2006-09-30 23:28:22 -07002 * 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 */
Alexey Dobriyanaa0ac362007-07-15 23:40:39 -07008#include <linux/capability.h>
Roman Zippel7dffa3c2008-05-01 04:34:41 -07009#include <linux/clocksource.h>
Maciej W. Rozyckieb3f9382008-09-22 14:42:40 -070010#include <linux/workqueue.h>
Ingo Molnar53bbfa92008-02-20 07:58:42 +010011#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>
Alexander Gordeev025b40a2011-01-12 17:00:56 -080017#include <linux/module.h>
john stultz4c7ee8d2006-09-30 23:28:22 -070018
Torben Hohne2830b52011-01-27 16:00:32 +010019#include "tick-internal.h"
20
Roman Zippelb0ee7552006-09-30 23:28:22 -070021/*
Ingo Molnar53bbfa92008-02-20 07:58:42 +010022 * NTP timekeeping variables:
Roman Zippelb0ee7552006-09-30 23:28:22 -070023 */
Roman Zippelb0ee7552006-09-30 23:28:22 -070024
John Stultzbd331262011-11-14 13:48:36 -080025DEFINE_SPINLOCK(ntp_lock);
26
27
Ingo Molnar53bbfa92008-02-20 07:58:42 +010028/* USER_HZ period (usecs): */
29unsigned long tick_usec = TICK_USEC;
Roman Zippel7dffa3c2008-05-01 04:34:41 -070030
Ingo Molnar53bbfa92008-02-20 07:58:42 +010031/* ACTHZ period (nsecs): */
32unsigned long tick_nsec;
33
John Stultzea7cf492011-11-14 13:18:07 -080034static u64 tick_length;
Ingo Molnar53bbfa92008-02-20 07:58:42 +010035static u64 tick_length_base;
36
Ingo Molnarbbd12672009-02-22 12:11:11 +010037#define MAX_TICKADJ 500LL /* usecs */
Ingo Molnar53bbfa92008-02-20 07:58:42 +010038#define MAX_TICKADJ_SCALED \
Ingo Molnarbbd12672009-02-22 12:11:11 +010039 (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
john stultz4c7ee8d2006-09-30 23:28:22 -070040
41/*
42 * phase-lock loop variables
43 */
Ingo Molnar53bbfa92008-02-20 07:58:42 +010044
45/*
46 * clock synchronization status
47 *
48 * (TIME_ERROR prevents overwriting the CMOS clock)
49 */
50static int time_state = TIME_OK;
51
52/* clock status bits: */
John Stultz83579292011-11-14 13:06:21 -080053static int time_status = STA_UNSYNC;
Ingo Molnar53bbfa92008-02-20 07:58:42 +010054
55/* TAI offset (secs): */
56static long time_tai;
57
58/* time adjustment (nsecs): */
59static s64 time_offset;
60
61/* pll time constant: */
62static long time_constant = 2;
63
64/* maximum error (usecs): */
john stultz1f5b8f82010-01-28 15:02:41 -080065static long time_maxerror = NTP_PHASE_LIMIT;
Ingo Molnar53bbfa92008-02-20 07:58:42 +010066
67/* estimated error (usecs): */
john stultz1f5b8f82010-01-28 15:02:41 -080068static long time_esterror = NTP_PHASE_LIMIT;
Ingo Molnar53bbfa92008-02-20 07:58:42 +010069
70/* frequency offset (scaled nsecs/secs): */
71static s64 time_freq;
72
73/* time at last adjustment (secs): */
74static long time_reftime;
75
John Stultze1292ba2010-03-18 20:19:27 -070076static long time_adjust;
Ingo Molnar53bbfa92008-02-20 07:58:42 +010077
Ingo Molnar069569e2009-02-22 16:03:37 +010078/* constant (boot-param configurable) NTP tick adjustment (upscaled) */
79static s64 ntp_tick_adj;
Ingo Molnar53bbfa92008-02-20 07:58:42 +010080
Alexander Gordeev025b40a2011-01-12 17:00:56 -080081#ifdef CONFIG_NTP_PPS
82
83/*
84 * The following variables are used when a pulse-per-second (PPS) signal
85 * is available. They establish the engineering parameters of the clock
86 * discipline loop when controlled by the PPS signal.
87 */
88#define PPS_VALID 10 /* PPS signal watchdog max (s) */
89#define PPS_POPCORN 4 /* popcorn spike threshold (shift) */
90#define PPS_INTMIN 2 /* min freq interval (s) (shift) */
91#define PPS_INTMAX 8 /* max freq interval (s) (shift) */
92#define PPS_INTCOUNT 4 /* number of consecutive good intervals to
93 increase pps_shift or consecutive bad
94 intervals to decrease it */
95#define PPS_MAXWANDER 100000 /* max PPS freq wander (ns/s) */
96
97static int pps_valid; /* signal watchdog counter */
98static long pps_tf[3]; /* phase median filter */
99static long pps_jitter; /* current jitter (ns) */
100static struct timespec pps_fbase; /* beginning of the last freq interval */
101static int pps_shift; /* current interval duration (s) (shift) */
102static int pps_intcnt; /* interval counter */
103static s64 pps_freq; /* frequency offset (scaled ns/s) */
104static long pps_stabil; /* current stability (scaled ns/s) */
105
106/*
107 * PPS signal quality monitors
108 */
109static long pps_calcnt; /* calibration intervals */
110static long pps_jitcnt; /* jitter limit exceeded */
111static long pps_stbcnt; /* stability limit exceeded */
112static long pps_errcnt; /* calibration errors */
113
114
115/* PPS kernel consumer compensates the whole phase error immediately.
116 * Otherwise, reduce the offset by a fixed factor times the time constant.
117 */
118static inline s64 ntp_offset_chunk(s64 offset)
119{
120 if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL)
121 return offset;
122 else
123 return shift_right(offset, SHIFT_PLL + time_constant);
124}
125
126static inline void pps_reset_freq_interval(void)
127{
128 /* the PPS calibration interval may end
129 surprisingly early */
130 pps_shift = PPS_INTMIN;
131 pps_intcnt = 0;
132}
133
134/**
135 * pps_clear - Clears the PPS state variables
136 *
John Stultzbd331262011-11-14 13:48:36 -0800137 * Must be called while holding a write on the ntp_lock
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800138 */
139static inline void pps_clear(void)
140{
141 pps_reset_freq_interval();
142 pps_tf[0] = 0;
143 pps_tf[1] = 0;
144 pps_tf[2] = 0;
145 pps_fbase.tv_sec = pps_fbase.tv_nsec = 0;
146 pps_freq = 0;
147}
148
149/* Decrease pps_valid to indicate that another second has passed since
150 * the last PPS signal. When it reaches 0, indicate that PPS signal is
151 * missing.
152 *
John Stultzbd331262011-11-14 13:48:36 -0800153 * Must be called while holding a write on the ntp_lock
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800154 */
155static inline void pps_dec_valid(void)
156{
157 if (pps_valid > 0)
158 pps_valid--;
159 else {
160 time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
161 STA_PPSWANDER | STA_PPSERROR);
162 pps_clear();
163 }
164}
165
166static inline void pps_set_freq(s64 freq)
167{
168 pps_freq = freq;
169}
170
171static inline int is_error_status(int status)
172{
173 return (time_status & (STA_UNSYNC|STA_CLOCKERR))
174 /* PPS signal lost when either PPS time or
175 * PPS frequency synchronization requested
176 */
177 || ((time_status & (STA_PPSFREQ|STA_PPSTIME))
178 && !(time_status & STA_PPSSIGNAL))
179 /* PPS jitter exceeded when
180 * PPS time synchronization requested */
181 || ((time_status & (STA_PPSTIME|STA_PPSJITTER))
182 == (STA_PPSTIME|STA_PPSJITTER))
183 /* PPS wander exceeded or calibration error when
184 * PPS frequency synchronization requested
185 */
186 || ((time_status & STA_PPSFREQ)
187 && (time_status & (STA_PPSWANDER|STA_PPSERROR)));
188}
189
190static inline void pps_fill_timex(struct timex *txc)
191{
192 txc->ppsfreq = shift_right((pps_freq >> PPM_SCALE_INV_SHIFT) *
193 PPM_SCALE_INV, NTP_SCALE_SHIFT);
194 txc->jitter = pps_jitter;
195 if (!(time_status & STA_NANO))
196 txc->jitter /= NSEC_PER_USEC;
197 txc->shift = pps_shift;
198 txc->stabil = pps_stabil;
199 txc->jitcnt = pps_jitcnt;
200 txc->calcnt = pps_calcnt;
201 txc->errcnt = pps_errcnt;
202 txc->stbcnt = pps_stbcnt;
203}
204
205#else /* !CONFIG_NTP_PPS */
206
207static inline s64 ntp_offset_chunk(s64 offset)
208{
209 return shift_right(offset, SHIFT_PLL + time_constant);
210}
211
212static inline void pps_reset_freq_interval(void) {}
213static inline void pps_clear(void) {}
214static inline void pps_dec_valid(void) {}
215static inline void pps_set_freq(s64 freq) {}
216
217static inline int is_error_status(int status)
218{
219 return status & (STA_UNSYNC|STA_CLOCKERR);
220}
221
222static inline void pps_fill_timex(struct timex *txc)
223{
224 /* PPS is not implemented, so these are zero */
225 txc->ppsfreq = 0;
226 txc->jitter = 0;
227 txc->shift = 0;
228 txc->stabil = 0;
229 txc->jitcnt = 0;
230 txc->calcnt = 0;
231 txc->errcnt = 0;
232 txc->stbcnt = 0;
233}
234
235#endif /* CONFIG_NTP_PPS */
236
John Stultz83579292011-11-14 13:06:21 -0800237
238/**
239 * ntp_synced - Returns 1 if the NTP status is not UNSYNC
240 *
241 */
242static inline int ntp_synced(void)
243{
244 return !(time_status & STA_UNSYNC);
245}
246
247
Ingo Molnar53bbfa92008-02-20 07:58:42 +0100248/*
249 * NTP methods:
250 */
john stultz4c7ee8d2006-09-30 23:28:22 -0700251
Ingo Molnar9ce616a2009-02-22 12:42:59 +0100252/*
253 * Update (tick_length, tick_length_base, tick_nsec), based
254 * on (tick_usec, ntp_tick_adj, time_freq):
255 */
Adrian Bunk70bc42f2006-09-30 23:28:29 -0700256static void ntp_update_frequency(void)
257{
Ingo Molnar9ce616a2009-02-22 12:42:59 +0100258 u64 second_length;
Ingo Molnarbc26c312009-02-22 12:17:36 +0100259 u64 new_base;
Adrian Bunk70bc42f2006-09-30 23:28:29 -0700260
Ingo Molnar9ce616a2009-02-22 12:42:59 +0100261 second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
262 << NTP_SCALE_SHIFT;
263
Ingo Molnar069569e2009-02-22 16:03:37 +0100264 second_length += ntp_tick_adj;
Ingo Molnar9ce616a2009-02-22 12:42:59 +0100265 second_length += time_freq;
266
Ingo Molnar9ce616a2009-02-22 12:42:59 +0100267 tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT;
Ingo Molnarbc26c312009-02-22 12:17:36 +0100268 new_base = div_u64(second_length, NTP_INTERVAL_FREQ);
john stultzfdcedf72009-02-18 16:02:22 -0800269
270 /*
271 * Don't wait for the next second_overflow, apply
Ingo Molnarbc26c312009-02-22 12:17:36 +0100272 * the change to the tick length immediately:
john stultzfdcedf72009-02-18 16:02:22 -0800273 */
Ingo Molnarbc26c312009-02-22 12:17:36 +0100274 tick_length += new_base - tick_length_base;
275 tick_length_base = new_base;
Adrian Bunk70bc42f2006-09-30 23:28:29 -0700276}
277
Ingo Molnar478b7aa2009-02-22 13:22:23 +0100278static inline s64 ntp_update_offset_fll(s64 offset64, long secs)
Ingo Molnarf9398902009-02-22 12:57:49 +0100279{
280 time_status &= ~STA_MODE;
281
282 if (secs < MINSEC)
Ingo Molnar478b7aa2009-02-22 13:22:23 +0100283 return 0;
Ingo Molnarf9398902009-02-22 12:57:49 +0100284
285 if (!(time_status & STA_FLL) && (secs <= MAXSEC))
Ingo Molnar478b7aa2009-02-22 13:22:23 +0100286 return 0;
Ingo Molnarf9398902009-02-22 12:57:49 +0100287
Ingo Molnarf9398902009-02-22 12:57:49 +0100288 time_status |= STA_MODE;
289
Sasha Levina078c6d2012-03-15 12:36:14 -0400290 return div64_long(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
Ingo Molnarf9398902009-02-22 12:57:49 +0100291}
292
Roman Zippelee9851b2008-05-01 04:34:32 -0700293static void ntp_update_offset(long offset)
294{
Roman Zippelee9851b2008-05-01 04:34:32 -0700295 s64 freq_adj;
Ingo Molnarf9398902009-02-22 12:57:49 +0100296 s64 offset64;
297 long secs;
Roman Zippelee9851b2008-05-01 04:34:32 -0700298
299 if (!(time_status & STA_PLL))
300 return;
301
Roman Zippeleea83d82008-05-01 04:34:33 -0700302 if (!(time_status & STA_NANO))
Roman Zippel9f14f662008-05-01 04:34:36 -0700303 offset *= NSEC_PER_USEC;
Roman Zippelee9851b2008-05-01 04:34:32 -0700304
305 /*
306 * Scale the phase adjustment and
307 * clamp to the operating range.
308 */
Roman Zippel9f14f662008-05-01 04:34:36 -0700309 offset = min(offset, MAXPHASE);
310 offset = max(offset, -MAXPHASE);
Roman Zippelee9851b2008-05-01 04:34:32 -0700311
312 /*
313 * Select how the frequency is to be controlled
314 * and in which mode (PLL or FLL).
315 */
John Stultz7e1b5842010-01-28 20:20:44 -0800316 secs = get_seconds() - time_reftime;
Ingo Molnar10dd31a2009-02-22 13:38:40 +0100317 if (unlikely(time_status & STA_FREQHOLD))
Ingo Molnarc7986ac2009-02-22 13:29:09 +0100318 secs = 0;
319
John Stultz7e1b5842010-01-28 20:20:44 -0800320 time_reftime = get_seconds();
Roman Zippelee9851b2008-05-01 04:34:32 -0700321
Ingo Molnarf9398902009-02-22 12:57:49 +0100322 offset64 = offset;
Miroslav Lichvar8af3c152010-09-07 16:43:46 +0200323 freq_adj = ntp_update_offset_fll(offset64, secs);
Roman Zippel9f14f662008-05-01 04:34:36 -0700324
Miroslav Lichvar8af3c152010-09-07 16:43:46 +0200325 /*
326 * Clamp update interval to reduce PLL gain with low
327 * sampling rate (e.g. intermittent network connection)
328 * to avoid instability.
329 */
330 if (unlikely(secs > 1 << (SHIFT_PLL + 1 + time_constant)))
331 secs = 1 << (SHIFT_PLL + 1 + time_constant);
332
333 freq_adj += (offset64 * secs) <<
334 (NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant));
Ingo Molnarf9398902009-02-22 12:57:49 +0100335
336 freq_adj = min(freq_adj + time_freq, MAXFREQ_SCALED);
337
338 time_freq = max(freq_adj, -MAXFREQ_SCALED);
339
340 time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
Roman Zippelee9851b2008-05-01 04:34:32 -0700341}
342
Roman Zippelb0ee7552006-09-30 23:28:22 -0700343/**
344 * ntp_clear - Clears the NTP state variables
Roman Zippelb0ee7552006-09-30 23:28:22 -0700345 */
346void ntp_clear(void)
347{
John Stultzbd331262011-11-14 13:48:36 -0800348 unsigned long flags;
349
350 spin_lock_irqsave(&ntp_lock, flags);
351
Ingo Molnar53bbfa92008-02-20 07:58:42 +0100352 time_adjust = 0; /* stop active adjtime() */
353 time_status |= STA_UNSYNC;
354 time_maxerror = NTP_PHASE_LIMIT;
355 time_esterror = NTP_PHASE_LIMIT;
Roman Zippelb0ee7552006-09-30 23:28:22 -0700356
357 ntp_update_frequency();
358
Ingo Molnar53bbfa92008-02-20 07:58:42 +0100359 tick_length = tick_length_base;
360 time_offset = 0;
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800361
362 /* Clear PPS state variables */
363 pps_clear();
John Stultzbd331262011-11-14 13:48:36 -0800364 spin_unlock_irqrestore(&ntp_lock, flags);
365
Roman Zippelb0ee7552006-09-30 23:28:22 -0700366}
367
John Stultzea7cf492011-11-14 13:18:07 -0800368
369u64 ntp_tick_length(void)
370{
John Stultzbd331262011-11-14 13:48:36 -0800371 unsigned long flags;
372 s64 ret;
373
374 spin_lock_irqsave(&ntp_lock, flags);
375 ret = tick_length;
376 spin_unlock_irqrestore(&ntp_lock, flags);
377 return ret;
John Stultzea7cf492011-11-14 13:18:07 -0800378}
379
380
john stultz4c7ee8d2006-09-30 23:28:22 -0700381/*
382 * this routine handles the overflow of the microsecond field
383 *
384 * The tricky bits of code to handle the accurate clock support
385 * were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
386 * They were originally developed for SUN and DEC kernels.
387 * All the kudos should go to Dave for this stuff.
John Stultz6b43ae82012-03-15 13:04:03 -0700388 *
389 * Also handles leap second processing, and returns leap offset
john stultz4c7ee8d2006-09-30 23:28:22 -0700390 */
John Stultz6b43ae82012-03-15 13:04:03 -0700391int second_overflow(unsigned long secs)
john stultz4c7ee8d2006-09-30 23:28:22 -0700392{
Ingo Molnar39854fe2009-02-22 16:06:58 +0100393 s64 delta;
John Stultz6b43ae82012-03-15 13:04:03 -0700394 int leap = 0;
John Stultzbd331262011-11-14 13:48:36 -0800395 unsigned long flags;
396
397 spin_lock_irqsave(&ntp_lock, flags);
john stultz4c7ee8d2006-09-30 23:28:22 -0700398
John Stultz6b43ae82012-03-15 13:04:03 -0700399 /*
400 * Leap second processing. If in leap-insert state at the end of the
401 * day, the system clock is set back one second; if in leap-delete
402 * state, the system clock is set ahead one second.
403 */
404 switch (time_state) {
405 case TIME_OK:
406 if (time_status & STA_INS)
407 time_state = TIME_INS;
408 else if (time_status & STA_DEL)
409 time_state = TIME_DEL;
410 break;
411 case TIME_INS:
412 if (secs % 86400 == 0) {
413 leap = -1;
414 time_state = TIME_OOP;
Richard Cochrandd48d702012-04-26 14:11:32 +0200415 time_tai++;
John Stultz6b43ae82012-03-15 13:04:03 -0700416 printk(KERN_NOTICE
417 "Clock: inserting leap second 23:59:60 UTC\n");
418 }
419 break;
420 case TIME_DEL:
421 if ((secs + 1) % 86400 == 0) {
422 leap = 1;
423 time_tai--;
424 time_state = TIME_WAIT;
425 printk(KERN_NOTICE
426 "Clock: deleting leap second 23:59:59 UTC\n");
427 }
428 break;
429 case TIME_OOP:
John Stultz6b43ae82012-03-15 13:04:03 -0700430 time_state = TIME_WAIT;
431 break;
432
433 case TIME_WAIT:
434 if (!(time_status & (STA_INS | STA_DEL)))
435 time_state = TIME_OK;
436 break;
437 }
438
439
john stultz4c7ee8d2006-09-30 23:28:22 -0700440 /* Bump the maxerror field */
Roman Zippel074b3b82008-05-01 04:34:34 -0700441 time_maxerror += MAXFREQ / NSEC_PER_USEC;
john stultz4c7ee8d2006-09-30 23:28:22 -0700442 if (time_maxerror > NTP_PHASE_LIMIT) {
443 time_maxerror = NTP_PHASE_LIMIT;
444 time_status |= STA_UNSYNC;
445 }
446
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800447 /* Compute the phase adjustment for the next second */
Ingo Molnar39854fe2009-02-22 16:06:58 +0100448 tick_length = tick_length_base;
449
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800450 delta = ntp_offset_chunk(time_offset);
Ingo Molnar39854fe2009-02-22 16:06:58 +0100451 time_offset -= delta;
452 tick_length += delta;
john stultz4c7ee8d2006-09-30 23:28:22 -0700453
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800454 /* Check PPS signal */
455 pps_dec_valid();
456
Ingo Molnar3c972c22009-02-22 12:06:57 +0100457 if (!time_adjust)
John Stultzbd331262011-11-14 13:48:36 -0800458 goto out;
Ingo Molnar3c972c22009-02-22 12:06:57 +0100459
460 if (time_adjust > MAX_TICKADJ) {
461 time_adjust -= MAX_TICKADJ;
462 tick_length += MAX_TICKADJ_SCALED;
John Stultzbd331262011-11-14 13:48:36 -0800463 goto out;
john stultz4c7ee8d2006-09-30 23:28:22 -0700464 }
Ingo Molnar3c972c22009-02-22 12:06:57 +0100465
466 if (time_adjust < -MAX_TICKADJ) {
467 time_adjust += MAX_TICKADJ;
468 tick_length -= MAX_TICKADJ_SCALED;
John Stultzbd331262011-11-14 13:48:36 -0800469 goto out;
Ingo Molnar3c972c22009-02-22 12:06:57 +0100470 }
471
472 tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)
473 << NTP_SCALE_SHIFT;
474 time_adjust = 0;
John Stultz6b43ae82012-03-15 13:04:03 -0700475
John Stultzbd331262011-11-14 13:48:36 -0800476out:
477 spin_unlock_irqrestore(&ntp_lock, flags);
John Stultz6b43ae82012-03-15 13:04:03 -0700478
479 return leap;
john stultz4c7ee8d2006-09-30 23:28:22 -0700480}
481
Thomas Gleixner82644452007-07-21 04:37:37 -0700482#ifdef CONFIG_GENERIC_CMOS_UPDATE
john stultz4c7ee8d2006-09-30 23:28:22 -0700483
Maciej W. Rozyckieb3f9382008-09-22 14:42:40 -0700484static void sync_cmos_clock(struct work_struct *work);
Thomas Gleixner82644452007-07-21 04:37:37 -0700485
Maciej W. Rozyckieb3f9382008-09-22 14:42:40 -0700486static DECLARE_DELAYED_WORK(sync_cmos_work, sync_cmos_clock);
Thomas Gleixner82644452007-07-21 04:37:37 -0700487
Maciej W. Rozyckieb3f9382008-09-22 14:42:40 -0700488static void sync_cmos_clock(struct work_struct *work)
john stultz4c7ee8d2006-09-30 23:28:22 -0700489{
Thomas Gleixner82644452007-07-21 04:37:37 -0700490 struct timespec now, next;
491 int fail = 1;
492
493 /*
494 * If we have an externally synchronized Linux clock, then update
495 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
496 * called as close as possible to 500 ms before the new second starts.
497 * This code is run on a timer. If the clock is set, that timer
498 * may not expire at the correct time. Thus, we adjust...
499 */
Ingo Molnar53bbfa92008-02-20 07:58:42 +0100500 if (!ntp_synced()) {
Thomas Gleixner82644452007-07-21 04:37:37 -0700501 /*
502 * Not synced, exit, do not restart a timer (if one is
503 * running, let it run out).
504 */
505 return;
Ingo Molnar53bbfa92008-02-20 07:58:42 +0100506 }
Thomas Gleixner82644452007-07-21 04:37:37 -0700507
508 getnstimeofday(&now);
David P. Reedfa6a1a52007-11-14 17:49:21 -0500509 if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2)
Thomas Gleixner82644452007-07-21 04:37:37 -0700510 fail = update_persistent_clock(now);
511
Maciej W. Rozycki4ff4b9e2008-09-05 14:05:31 -0700512 next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec - (TICK_NSEC / 2);
Thomas Gleixner82644452007-07-21 04:37:37 -0700513 if (next.tv_nsec <= 0)
514 next.tv_nsec += NSEC_PER_SEC;
515
516 if (!fail)
517 next.tv_sec = 659;
518 else
519 next.tv_sec = 0;
520
521 if (next.tv_nsec >= NSEC_PER_SEC) {
522 next.tv_sec++;
523 next.tv_nsec -= NSEC_PER_SEC;
524 }
Maciej W. Rozyckieb3f9382008-09-22 14:42:40 -0700525 schedule_delayed_work(&sync_cmos_work, timespec_to_jiffies(&next));
john stultz4c7ee8d2006-09-30 23:28:22 -0700526}
527
Thomas Gleixner82644452007-07-21 04:37:37 -0700528static void notify_cmos_timer(void)
529{
Cesar Eduardo Barros335dd852012-02-11 17:54:59 -0200530 schedule_delayed_work(&sync_cmos_work, 0);
Thomas Gleixner82644452007-07-21 04:37:37 -0700531}
532
533#else
534static inline void notify_cmos_timer(void) { }
535#endif
536
Ingo Molnar80f22572009-02-22 15:15:32 +0100537
538/*
539 * Propagate a new txc->status value into the NTP state:
540 */
541static inline void process_adj_status(struct timex *txc, struct timespec *ts)
542{
Ingo Molnar80f22572009-02-22 15:15:32 +0100543 if ((time_status & STA_PLL) && !(txc->status & STA_PLL)) {
544 time_state = TIME_OK;
545 time_status = STA_UNSYNC;
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800546 /* restart PPS frequency calibration */
547 pps_reset_freq_interval();
Ingo Molnar80f22572009-02-22 15:15:32 +0100548 }
Ingo Molnar80f22572009-02-22 15:15:32 +0100549
550 /*
551 * If we turn on PLL adjustments then reset the
552 * reference time to current time.
553 */
554 if (!(time_status & STA_PLL) && (txc->status & STA_PLL))
John Stultz7e1b5842010-01-28 20:20:44 -0800555 time_reftime = get_seconds();
Ingo Molnar80f22572009-02-22 15:15:32 +0100556
John Stultza2a5ac82009-02-26 09:46:14 -0800557 /* only set allowed bits */
558 time_status &= STA_RONLY;
Ingo Molnar80f22572009-02-22 15:15:32 +0100559 time_status |= txc->status & ~STA_RONLY;
Ingo Molnar80f22572009-02-22 15:15:32 +0100560}
Richard Cochrancd5398b2012-04-27 10:12:41 +0200561
Ingo Molnar80f22572009-02-22 15:15:32 +0100562/*
Richard Cochrancd5398b2012-04-27 10:12:41 +0200563 * Called with ntp_lock held, so we can access and modify
Ingo Molnar80f22572009-02-22 15:15:32 +0100564 * all the global NTP state:
565 */
566static inline void process_adjtimex_modes(struct timex *txc, struct timespec *ts)
567{
568 if (txc->modes & ADJ_STATUS)
569 process_adj_status(txc, ts);
570
571 if (txc->modes & ADJ_NANO)
572 time_status |= STA_NANO;
Ingo Molnare9629162009-02-22 15:35:18 +0100573
Ingo Molnar80f22572009-02-22 15:15:32 +0100574 if (txc->modes & ADJ_MICRO)
575 time_status &= ~STA_NANO;
576
577 if (txc->modes & ADJ_FREQUENCY) {
Ingo Molnar2b9d1492009-02-22 15:48:43 +0100578 time_freq = txc->freq * PPM_SCALE;
Ingo Molnar80f22572009-02-22 15:15:32 +0100579 time_freq = min(time_freq, MAXFREQ_SCALED);
580 time_freq = max(time_freq, -MAXFREQ_SCALED);
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800581 /* update pps_freq */
582 pps_set_freq(time_freq);
Ingo Molnar80f22572009-02-22 15:15:32 +0100583 }
584
585 if (txc->modes & ADJ_MAXERROR)
586 time_maxerror = txc->maxerror;
Ingo Molnare9629162009-02-22 15:35:18 +0100587
Ingo Molnar80f22572009-02-22 15:15:32 +0100588 if (txc->modes & ADJ_ESTERROR)
589 time_esterror = txc->esterror;
590
591 if (txc->modes & ADJ_TIMECONST) {
592 time_constant = txc->constant;
593 if (!(time_status & STA_NANO))
594 time_constant += 4;
595 time_constant = min(time_constant, (long)MAXTC);
596 time_constant = max(time_constant, 0l);
597 }
598
599 if (txc->modes & ADJ_TAI && txc->constant > 0)
600 time_tai = txc->constant;
601
602 if (txc->modes & ADJ_OFFSET)
603 ntp_update_offset(txc->offset);
Ingo Molnare9629162009-02-22 15:35:18 +0100604
Ingo Molnar80f22572009-02-22 15:15:32 +0100605 if (txc->modes & ADJ_TICK)
606 tick_usec = txc->tick;
607
608 if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET))
609 ntp_update_frequency();
610}
611
Ingo Molnar53bbfa92008-02-20 07:58:42 +0100612/*
613 * adjtimex mainly allows reading (and writing, if superuser) of
john stultz4c7ee8d2006-09-30 23:28:22 -0700614 * kernel time-keeping variables. used by xntpd.
615 */
616int do_adjtimex(struct timex *txc)
617{
Roman Zippeleea83d82008-05-01 04:34:33 -0700618 struct timespec ts;
john stultz4c7ee8d2006-09-30 23:28:22 -0700619 int result;
620
Roman Zippel916c7a82008-08-20 16:46:08 -0700621 /* Validate the data before disabling interrupts */
622 if (txc->modes & ADJ_ADJTIME) {
Roman Zippeleea83d82008-05-01 04:34:33 -0700623 /* singleshot must not be used with any other mode bits */
Roman Zippel916c7a82008-08-20 16:46:08 -0700624 if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
john stultz4c7ee8d2006-09-30 23:28:22 -0700625 return -EINVAL;
Roman Zippel916c7a82008-08-20 16:46:08 -0700626 if (!(txc->modes & ADJ_OFFSET_READONLY) &&
627 !capable(CAP_SYS_TIME))
628 return -EPERM;
629 } else {
630 /* In order to modify anything, you gotta be super-user! */
631 if (txc->modes && !capable(CAP_SYS_TIME))
632 return -EPERM;
633
Ingo Molnar53bbfa92008-02-20 07:58:42 +0100634 /*
635 * if the quartz is off by more than 10% then
636 * something is VERY wrong!
637 */
Roman Zippel916c7a82008-08-20 16:46:08 -0700638 if (txc->modes & ADJ_TICK &&
639 (txc->tick < 900000/USER_HZ ||
640 txc->tick > 1100000/USER_HZ))
Ingo Molnare9629162009-02-22 15:35:18 +0100641 return -EINVAL;
John Stultz52bfb362007-11-26 20:42:19 +0100642 }
john stultz4c7ee8d2006-09-30 23:28:22 -0700643
Richard Cochran094aa182011-02-01 13:52:20 +0000644 if (txc->modes & ADJ_SETOFFSET) {
645 struct timespec delta;
Richard Cochran094aa182011-02-01 13:52:20 +0000646 delta.tv_sec = txc->time.tv_sec;
647 delta.tv_nsec = txc->time.tv_usec;
Richard Cochran4352d9d2011-04-04 08:31:23 -0700648 if (!capable(CAP_SYS_TIME))
649 return -EPERM;
Richard Cochran094aa182011-02-01 13:52:20 +0000650 if (!(txc->modes & ADJ_NANO))
651 delta.tv_nsec *= 1000;
Richard Cochrandb1c1cc2011-02-18 10:07:25 +0100652 result = timekeeping_inject_offset(&delta);
653 if (result)
654 return result;
Richard Cochran094aa182011-02-01 13:52:20 +0000655 }
656
Roman Zippel7dffa3c2008-05-01 04:34:41 -0700657 getnstimeofday(&ts);
658
John Stultzbd331262011-11-14 13:48:36 -0800659 spin_lock_irq(&ntp_lock);
john stultz4c7ee8d2006-09-30 23:28:22 -0700660
Roman Zippel916c7a82008-08-20 16:46:08 -0700661 if (txc->modes & ADJ_ADJTIME) {
662 long save_adjust = time_adjust;
663
664 if (!(txc->modes & ADJ_OFFSET_READONLY)) {
665 /* adjtime() is independent from ntp_adjtime() */
666 time_adjust = txc->offset;
667 ntp_update_frequency();
668 }
669 txc->offset = save_adjust;
Ingo Molnare9629162009-02-22 15:35:18 +0100670 } else {
671
672 /* If there are input parameters, then process them: */
673 if (txc->modes)
674 process_adjtimex_modes(txc, &ts);
675
676 txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
677 NTP_SCALE_SHIFT);
678 if (!(time_status & STA_NANO))
679 txc->offset /= NSEC_PER_USEC;
Roman Zippel916c7a82008-08-20 16:46:08 -0700680 }
Roman Zippel916c7a82008-08-20 16:46:08 -0700681
Roman Zippeleea83d82008-05-01 04:34:33 -0700682 result = time_state; /* mostly `TIME_OK' */
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800683 /* check for errors */
684 if (is_error_status(time_status))
john stultz4c7ee8d2006-09-30 23:28:22 -0700685 result = TIME_ERROR;
686
Roman Zippeld40e9442008-09-22 14:42:44 -0700687 txc->freq = shift_right((time_freq >> PPM_SCALE_INV_SHIFT) *
Ingo Molnar2b9d1492009-02-22 15:48:43 +0100688 PPM_SCALE_INV, NTP_SCALE_SHIFT);
john stultz4c7ee8d2006-09-30 23:28:22 -0700689 txc->maxerror = time_maxerror;
690 txc->esterror = time_esterror;
691 txc->status = time_status;
692 txc->constant = time_constant;
Adrian Bunk70bc42f2006-09-30 23:28:29 -0700693 txc->precision = 1;
Roman Zippel074b3b82008-05-01 04:34:34 -0700694 txc->tolerance = MAXFREQ_SCALED / PPM_SCALE;
john stultz4c7ee8d2006-09-30 23:28:22 -0700695 txc->tick = tick_usec;
Roman Zippel153b5d02008-05-01 04:34:37 -0700696 txc->tai = time_tai;
john stultz4c7ee8d2006-09-30 23:28:22 -0700697
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800698 /* fill PPS status fields */
699 pps_fill_timex(txc);
Ingo Molnare9629162009-02-22 15:35:18 +0100700
John Stultzbd331262011-11-14 13:48:36 -0800701 spin_unlock_irq(&ntp_lock);
Roman Zippelee9851b2008-05-01 04:34:32 -0700702
Roman Zippeleea83d82008-05-01 04:34:33 -0700703 txc->time.tv_sec = ts.tv_sec;
704 txc->time.tv_usec = ts.tv_nsec;
705 if (!(time_status & STA_NANO))
706 txc->time.tv_usec /= NSEC_PER_USEC;
Roman Zippelee9851b2008-05-01 04:34:32 -0700707
Thomas Gleixner82644452007-07-21 04:37:37 -0700708 notify_cmos_timer();
Roman Zippelee9851b2008-05-01 04:34:32 -0700709
710 return result;
john stultz4c7ee8d2006-09-30 23:28:22 -0700711}
Roman Zippel10a398d2008-03-04 15:14:26 -0800712
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800713#ifdef CONFIG_NTP_PPS
714
715/* actually struct pps_normtime is good old struct timespec, but it is
716 * semantically different (and it is the reason why it was invented):
717 * pps_normtime.nsec has a range of ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ]
718 * while timespec.tv_nsec has a range of [0, NSEC_PER_SEC) */
719struct pps_normtime {
720 __kernel_time_t sec; /* seconds */
721 long nsec; /* nanoseconds */
722};
723
724/* normalize the timestamp so that nsec is in the
725 ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ] interval */
726static inline struct pps_normtime pps_normalize_ts(struct timespec ts)
727{
728 struct pps_normtime norm = {
729 .sec = ts.tv_sec,
730 .nsec = ts.tv_nsec
731 };
732
733 if (norm.nsec > (NSEC_PER_SEC >> 1)) {
734 norm.nsec -= NSEC_PER_SEC;
735 norm.sec++;
736 }
737
738 return norm;
739}
740
741/* get current phase correction and jitter */
742static inline long pps_phase_filter_get(long *jitter)
743{
744 *jitter = pps_tf[0] - pps_tf[1];
745 if (*jitter < 0)
746 *jitter = -*jitter;
747
748 /* TODO: test various filters */
749 return pps_tf[0];
750}
751
752/* add the sample to the phase filter */
753static inline void pps_phase_filter_add(long err)
754{
755 pps_tf[2] = pps_tf[1];
756 pps_tf[1] = pps_tf[0];
757 pps_tf[0] = err;
758}
759
760/* decrease frequency calibration interval length.
761 * It is halved after four consecutive unstable intervals.
762 */
763static inline void pps_dec_freq_interval(void)
764{
765 if (--pps_intcnt <= -PPS_INTCOUNT) {
766 pps_intcnt = -PPS_INTCOUNT;
767 if (pps_shift > PPS_INTMIN) {
768 pps_shift--;
769 pps_intcnt = 0;
770 }
771 }
772}
773
774/* increase frequency calibration interval length.
775 * It is doubled after four consecutive stable intervals.
776 */
777static inline void pps_inc_freq_interval(void)
778{
779 if (++pps_intcnt >= PPS_INTCOUNT) {
780 pps_intcnt = PPS_INTCOUNT;
781 if (pps_shift < PPS_INTMAX) {
782 pps_shift++;
783 pps_intcnt = 0;
784 }
785 }
786}
787
788/* update clock frequency based on MONOTONIC_RAW clock PPS signal
789 * timestamps
790 *
791 * At the end of the calibration interval the difference between the
792 * first and last MONOTONIC_RAW clock timestamps divided by the length
793 * of the interval becomes the frequency update. If the interval was
794 * too long, the data are discarded.
795 * Returns the difference between old and new frequency values.
796 */
797static long hardpps_update_freq(struct pps_normtime freq_norm)
798{
799 long delta, delta_mod;
800 s64 ftemp;
801
802 /* check if the frequency interval was too long */
803 if (freq_norm.sec > (2 << pps_shift)) {
804 time_status |= STA_PPSERROR;
805 pps_errcnt++;
806 pps_dec_freq_interval();
807 pr_err("hardpps: PPSERROR: interval too long - %ld s\n",
808 freq_norm.sec);
809 return 0;
810 }
811
812 /* here the raw frequency offset and wander (stability) is
813 * calculated. If the wander is less than the wander threshold
814 * the interval is increased; otherwise it is decreased.
815 */
816 ftemp = div_s64(((s64)(-freq_norm.nsec)) << NTP_SCALE_SHIFT,
817 freq_norm.sec);
818 delta = shift_right(ftemp - pps_freq, NTP_SCALE_SHIFT);
819 pps_freq = ftemp;
820 if (delta > PPS_MAXWANDER || delta < -PPS_MAXWANDER) {
821 pr_warning("hardpps: PPSWANDER: change=%ld\n", delta);
822 time_status |= STA_PPSWANDER;
823 pps_stbcnt++;
824 pps_dec_freq_interval();
825 } else { /* good sample */
826 pps_inc_freq_interval();
827 }
828
829 /* the stability metric is calculated as the average of recent
830 * frequency changes, but is used only for performance
831 * monitoring
832 */
833 delta_mod = delta;
834 if (delta_mod < 0)
835 delta_mod = -delta_mod;
836 pps_stabil += (div_s64(((s64)delta_mod) <<
837 (NTP_SCALE_SHIFT - SHIFT_USEC),
838 NSEC_PER_USEC) - pps_stabil) >> PPS_INTMIN;
839
840 /* if enabled, the system clock frequency is updated */
841 if ((time_status & STA_PPSFREQ) != 0 &&
842 (time_status & STA_FREQHOLD) == 0) {
843 time_freq = pps_freq;
844 ntp_update_frequency();
845 }
846
847 return delta;
848}
849
850/* correct REALTIME clock phase error against PPS signal */
851static void hardpps_update_phase(long error)
852{
853 long correction = -error;
854 long jitter;
855
856 /* add the sample to the median filter */
857 pps_phase_filter_add(correction);
858 correction = pps_phase_filter_get(&jitter);
859
860 /* Nominal jitter is due to PPS signal noise. If it exceeds the
861 * threshold, the sample is discarded; otherwise, if so enabled,
862 * the time offset is updated.
863 */
864 if (jitter > (pps_jitter << PPS_POPCORN)) {
865 pr_warning("hardpps: PPSJITTER: jitter=%ld, limit=%ld\n",
866 jitter, (pps_jitter << PPS_POPCORN));
867 time_status |= STA_PPSJITTER;
868 pps_jitcnt++;
869 } else if (time_status & STA_PPSTIME) {
870 /* correct the time using the phase offset */
871 time_offset = div_s64(((s64)correction) << NTP_SCALE_SHIFT,
872 NTP_INTERVAL_FREQ);
873 /* cancel running adjtime() */
874 time_adjust = 0;
875 }
876 /* update jitter */
877 pps_jitter += (jitter - pps_jitter) >> PPS_INTMIN;
878}
879
880/*
881 * hardpps() - discipline CPU clock oscillator to external PPS signal
882 *
883 * This routine is called at each PPS signal arrival in order to
884 * discipline the CPU clock oscillator to the PPS signal. It takes two
885 * parameters: REALTIME and MONOTONIC_RAW clock timestamps. The former
886 * is used to correct clock phase error and the latter is used to
887 * correct the frequency.
888 *
889 * This code is based on David Mills's reference nanokernel
890 * implementation. It was mostly rewritten but keeps the same idea.
891 */
892void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts)
893{
894 struct pps_normtime pts_norm, freq_norm;
895 unsigned long flags;
896
897 pts_norm = pps_normalize_ts(*phase_ts);
898
John Stultzbd331262011-11-14 13:48:36 -0800899 spin_lock_irqsave(&ntp_lock, flags);
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800900
901 /* clear the error bits, they will be set again if needed */
902 time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
903
904 /* indicate signal presence */
905 time_status |= STA_PPSSIGNAL;
906 pps_valid = PPS_VALID;
907
908 /* when called for the first time,
909 * just start the frequency interval */
910 if (unlikely(pps_fbase.tv_sec == 0)) {
911 pps_fbase = *raw_ts;
John Stultzbd331262011-11-14 13:48:36 -0800912 spin_unlock_irqrestore(&ntp_lock, flags);
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800913 return;
914 }
915
916 /* ok, now we have a base for frequency calculation */
917 freq_norm = pps_normalize_ts(timespec_sub(*raw_ts, pps_fbase));
918
919 /* check that the signal is in the range
920 * [1s - MAXFREQ us, 1s + MAXFREQ us], otherwise reject it */
921 if ((freq_norm.sec == 0) ||
922 (freq_norm.nsec > MAXFREQ * freq_norm.sec) ||
923 (freq_norm.nsec < -MAXFREQ * freq_norm.sec)) {
924 time_status |= STA_PPSJITTER;
925 /* restart the frequency calibration interval */
926 pps_fbase = *raw_ts;
John Stultzbd331262011-11-14 13:48:36 -0800927 spin_unlock_irqrestore(&ntp_lock, flags);
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800928 pr_err("hardpps: PPSJITTER: bad pulse\n");
929 return;
930 }
931
932 /* signal is ok */
933
934 /* check if the current frequency interval is finished */
935 if (freq_norm.sec >= (1 << pps_shift)) {
936 pps_calcnt++;
937 /* restart the frequency calibration interval */
938 pps_fbase = *raw_ts;
939 hardpps_update_freq(freq_norm);
940 }
941
942 hardpps_update_phase(pts_norm.nsec);
943
John Stultzbd331262011-11-14 13:48:36 -0800944 spin_unlock_irqrestore(&ntp_lock, flags);
Alexander Gordeev025b40a2011-01-12 17:00:56 -0800945}
946EXPORT_SYMBOL(hardpps);
947
948#endif /* CONFIG_NTP_PPS */
949
Roman Zippel10a398d2008-03-04 15:14:26 -0800950static int __init ntp_tick_adj_setup(char *str)
951{
952 ntp_tick_adj = simple_strtol(str, NULL, 0);
Ingo Molnar069569e2009-02-22 16:03:37 +0100953 ntp_tick_adj <<= NTP_SCALE_SHIFT;
954
Roman Zippel10a398d2008-03-04 15:14:26 -0800955 return 1;
956}
957
958__setup("ntp_tick_adj=", ntp_tick_adj_setup);
Roman Zippel7dffa3c2008-05-01 04:34:41 -0700959
960void __init ntp_init(void)
961{
962 ntp_clear();
Roman Zippel7dffa3c2008-05-01 04:34:41 -0700963}