2 ***********************************************************************
4 * Copyright (c) David L. Mills 1993-2001 *
6 * Permission to use, copy, modify, and distribute this software and *
7 * its documentation for any purpose and without fee is hereby *
8 * granted, provided that the above copyright notice appears in all *
9 * copies and that both the copyright notice and this permission *
10 * notice appear in supporting documentation, and that the name *
11 * University of Delaware not be used in advertising or publicity *
12 * pertaining to distribution of the software without specific, *
13 * written prior permission. The University of Delaware makes no *
14 * representations about the suitability this software for any *
15 * purpose. It is provided "as is" without express or implied *
18 **********************************************************************/
21 * Adapted from the original sources for FreeBSD and timecounters by:
22 * Poul-Henning Kamp <phk@FreeBSD.org>.
24 * The 32bit version of the "LP" macros seems a bit past its "sell by"
25 * date so I have retained only the 64bit version and included it directly
28 * Only minor changes done to interface with the timecounters over in
29 * sys/kern/kern_clock.c. Some of the comments below may be (even more)
30 * confusing and/or plain wrong in that context.
33 #include <sys/cdefs.h>
36 #include <sys/param.h>
37 #include <sys/systm.h>
38 #include <sys/sysproto.h>
39 #include <sys/eventhandler.h>
40 #include <sys/kernel.h>
44 #include <sys/mutex.h>
46 #include <sys/timex.h>
47 #include <sys/timetc.h>
48 #include <sys/timepps.h>
49 #include <sys/syscallsubr.h>
50 #include <sys/sysctl.h>
53 FEATURE(pps_sync, "Support usage of external PPS signal by kernel PLL");
57 * Single-precision macros for 64-bit machines
60 #define L_ADD(v, u) ((v) += (u))
61 #define L_SUB(v, u) ((v) -= (u))
62 #define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32)
63 #define L_NEG(v) ((v) = -(v))
64 #define L_RSHIFT(v, n) \
67 (v) = -(-(v) >> (n)); \
71 #define L_MPY(v, a) ((v) *= (a))
72 #define L_CLR(v) ((v) = 0)
73 #define L_ISNEG(v) ((v) < 0)
74 #define L_LINT(v, a) \
77 ((v) = -((int64_t)(-(a)) << 32)); \
79 ((v) = (int64_t)(a) << 32); \
81 #define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32)
84 * Generic NTP kernel interface
86 * These routines constitute the Network Time Protocol (NTP) interfaces
87 * for user and daemon application programs. The ntp_gettime() routine
88 * provides the time, maximum error (synch distance) and estimated error
89 * (dispersion) to client user application programs. The ntp_adjtime()
90 * routine is used by the NTP daemon to adjust the system clock to an
91 * externally derived time. The time offset and related variables set by
92 * this routine are used by other routines in this module to adjust the
93 * phase and frequency of the clock discipline loop which controls the
96 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO
97 * defined), the time at each tick interrupt is derived directly from
98 * the kernel time variable. When the kernel time is reckoned in
99 * microseconds, (NTP_NANO undefined), the time is derived from the
100 * kernel time variable together with a variable representing the
101 * leftover nanoseconds at the last tick interrupt. In either case, the
102 * current nanosecond time is reckoned from these values plus an
103 * interpolated value derived by the clock routines in another
104 * architecture-specific module. The interpolation can use either a
105 * dedicated counter or a processor cycle counter (PCC) implemented in
106 * some architectures.
108 * Note that all routines must run at priority splclock or higher.
111 * Phase/frequency-lock loop (PLL/FLL) definitions
113 * The nanosecond clock discipline uses two variable types, time
114 * variables and frequency variables. Both types are represented as 64-
115 * bit fixed-point quantities with the decimal point between two 32-bit
116 * halves. On a 32-bit machine, each half is represented as a single
117 * word and mathematical operations are done using multiple-precision
118 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is
121 * A time variable is a signed 64-bit fixed-point number in ns and
122 * fraction. It represents the remaining time offset to be amortized
123 * over succeeding tick interrupts. The maximum time offset is about
124 * 0.5 s and the resolution is about 2.3e-10 ns.
126 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
127 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
128 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
130 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
132 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
134 * A frequency variable is a signed 64-bit fixed-point number in ns/s
135 * and fraction. It represents the ns and fraction to be added to the
136 * kernel time variable at each second. The maximum frequency offset is
137 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s.
139 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
140 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
141 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
142 * |s s s s s s s s s s s s s| ns/s |
143 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
145 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
148 * The following variables establish the state of the PLL/FLL and the
149 * residual time and frequency offset of the local clock.
151 #define SHIFT_PLL 4 /* PLL loop gain (shift) */
152 #define SHIFT_FLL 2 /* FLL loop gain (shift) */
154 static int time_state = TIME_OK; /* clock state */
155 int time_status = STA_UNSYNC; /* clock status bits */
156 static long time_tai; /* TAI offset (s) */
157 static long time_monitor; /* last time offset scaled (ns) */
158 static long time_constant; /* poll interval (shift) (s) */
159 static long time_precision = 1; /* clock precision (ns) */
160 static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */
161 long time_esterror = MAXPHASE / 1000; /* estimated error (us) */
162 static long time_reftime; /* uptime at last adjustment (s) */
163 static l_fp time_offset; /* time offset (ns) */
164 static l_fp time_freq; /* frequency offset (ns/s) */
165 static l_fp time_adj; /* tick adjust (ns/s) */
167 static int64_t time_adjtime; /* correction from adjtime(2) (usec) */
169 static struct mtx ntp_lock;
170 MTX_SYSINIT(ntp, &ntp_lock, "ntp", MTX_SPIN);
172 #define NTP_LOCK() mtx_lock_spin(&ntp_lock)
173 #define NTP_UNLOCK() mtx_unlock_spin(&ntp_lock)
174 #define NTP_ASSERT_LOCKED() mtx_assert(&ntp_lock, MA_OWNED)
178 * The following variables are used when a pulse-per-second (PPS) signal
179 * is available and connected via a modem control lead. They establish
180 * the engineering parameters of the clock discipline loop when
181 * controlled by the PPS signal.
183 #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */
184 #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */
185 #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */
186 #define PPS_PAVG 4 /* phase avg interval (s) (shift) */
187 #define PPS_VALID 120 /* PPS signal watchdog max (s) */
188 #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */
189 #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */
191 static struct timespec pps_tf[3]; /* phase median filter */
192 static l_fp pps_freq; /* scaled frequency offset (ns/s) */
193 static long pps_fcount; /* frequency accumulator */
194 static long pps_jitter; /* nominal jitter (ns) */
195 static long pps_stabil; /* nominal stability (scaled ns/s) */
196 static long pps_lastsec; /* time at last calibration (s) */
197 static int pps_valid; /* signal watchdog counter */
198 static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */
199 static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */
200 static int pps_intcnt; /* wander counter */
203 * PPS signal quality monitors
205 static long pps_calcnt; /* calibration intervals */
206 static long pps_jitcnt; /* jitter limit exceeded */
207 static long pps_stbcnt; /* stability limit exceeded */
208 static long pps_errcnt; /* calibration errors */
209 #endif /* PPS_SYNC */
211 * End of phase/frequency-lock loop (PLL/FLL) definitions
214 static void ntp_init(void);
215 static void hardupdate(long offset);
216 static void ntp_gettime1(struct ntptimeval *ntvp);
217 static bool ntp_is_time_error(int tsl);
220 ntp_is_time_error(int tsl)
224 * Status word error decode. If any of these conditions occur,
225 * an error is returned, instead of the status word. Most
226 * applications will care only about the fact the system clock
227 * may not be trusted, not about the details.
229 * Hardware or software error
231 if ((tsl & (STA_UNSYNC | STA_CLOCKERR)) ||
234 * PPS signal lost when either time or frequency synchronization
237 (tsl & (STA_PPSFREQ | STA_PPSTIME) &&
238 !(tsl & STA_PPSSIGNAL)) ||
241 * PPS jitter exceeded when time synchronization requested
243 (tsl & STA_PPSTIME && tsl & STA_PPSJITTER) ||
246 * PPS wander exceeded or calibration error when frequency
247 * synchronization requested
249 (tsl & STA_PPSFREQ &&
250 tsl & (STA_PPSWANDER | STA_PPSERROR)))
257 ntp_gettime1(struct ntptimeval *ntvp)
259 struct timespec atv; /* nanosecond time */
264 ntvp->time.tv_sec = atv.tv_sec;
265 ntvp->time.tv_nsec = atv.tv_nsec;
266 ntvp->maxerror = time_maxerror;
267 ntvp->esterror = time_esterror;
268 ntvp->tai = time_tai;
269 ntvp->time_state = time_state;
271 if (ntp_is_time_error(time_status))
272 ntvp->time_state = TIME_ERROR;
276 * ntp_gettime() - NTP user application interface
278 * See the timex.h header file for synopsis and API description. Note that
279 * the TAI offset is returned in the ntvtimeval.tai structure member.
281 #ifndef _SYS_SYSPROTO_H_
282 struct ntp_gettime_args {
283 struct ntptimeval *ntvp;
288 sys_ntp_gettime(struct thread *td, struct ntp_gettime_args *uap)
290 struct ntptimeval ntv;
292 memset(&ntv, 0, sizeof(ntv));
298 td->td_retval[0] = ntv.time_state;
299 return (copyout(&ntv, uap->ntvp, sizeof(ntv)));
303 ntp_sysctl(SYSCTL_HANDLER_ARGS)
305 struct ntptimeval ntv; /* temporary structure */
307 memset(&ntv, 0, sizeof(ntv));
313 return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req));
316 SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
318 SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE | CTLFLAG_RD |
319 CTLFLAG_MPSAFE, 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval",
323 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW,
324 &pps_shiftmax, 0, "Max interval duration (sec) (shift)");
325 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW,
326 &pps_shift, 0, "Interval duration (sec) (shift)");
327 SYSCTL_LONG(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD,
328 &time_monitor, 0, "Last time offset scaled (ns)");
330 SYSCTL_S64(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD | CTLFLAG_MPSAFE,
332 "Scaled frequency offset (ns/sec)");
333 SYSCTL_S64(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD | CTLFLAG_MPSAFE,
335 "Frequency offset (ns/sec)");
339 * ntp_adjtime() - NTP daemon application interface
341 * See the timex.h header file for synopsis and API description. Note that
342 * the timex.constant structure member has a dual purpose to set the time
343 * constant and to set the TAI offset.
346 kern_ntp_adjtime(struct thread *td, struct timex *ntv, int *retvalp)
348 long freq; /* frequency ns/s) */
349 int modes; /* mode bits from structure */
353 * Update selected clock variables - only the superuser can
354 * change anything. Note that there is no error checking here on
355 * the assumption the superuser should know what it is doing.
356 * Note that either the time constant or TAI offset are loaded
357 * from the ntv.constant member, depending on the mode bits. If
358 * the STA_PLL bit in the status word is cleared, the state and
359 * status words are reset to the initial values at boot.
364 error = priv_check(td, PRIV_NTP_ADJTIME);
368 if (modes & MOD_MAXERROR)
369 time_maxerror = ntv->maxerror;
370 if (modes & MOD_ESTERROR)
371 time_esterror = ntv->esterror;
372 if (modes & MOD_STATUS) {
373 if (time_status & STA_PLL && !(ntv->status & STA_PLL)) {
374 time_state = TIME_OK;
375 time_status = STA_UNSYNC;
377 pps_shift = PPS_FAVG;
378 #endif /* PPS_SYNC */
380 time_status &= STA_RONLY;
381 time_status |= ntv->status & ~STA_RONLY;
383 if (modes & MOD_TIMECONST) {
384 if (ntv->constant < 0)
386 else if (ntv->constant > MAXTC)
387 time_constant = MAXTC;
389 time_constant = ntv->constant;
391 if (modes & MOD_TAI) {
392 if (ntv->constant > 0) /* XXX zero & negative numbers ? */
393 time_tai = ntv->constant;
396 if (modes & MOD_PPSMAX) {
397 if (ntv->shift < PPS_FAVG)
398 pps_shiftmax = PPS_FAVG;
399 else if (ntv->shift > PPS_FAVGMAX)
400 pps_shiftmax = PPS_FAVGMAX;
402 pps_shiftmax = ntv->shift;
404 #endif /* PPS_SYNC */
405 if (modes & MOD_NANO)
406 time_status |= STA_NANO;
407 if (modes & MOD_MICRO)
408 time_status &= ~STA_NANO;
409 if (modes & MOD_CLKB)
410 time_status |= STA_CLK;
411 if (modes & MOD_CLKA)
412 time_status &= ~STA_CLK;
413 if (modes & MOD_FREQUENCY) {
414 freq = (ntv->freq * 1000LL) >> 16;
416 L_LINT(time_freq, MAXFREQ);
417 else if (freq < -MAXFREQ)
418 L_LINT(time_freq, -MAXFREQ);
421 * ntv->freq is [PPM * 2^16] = [us/s * 2^16]
422 * time_freq is [ns/s * 2^32]
424 time_freq = ntv->freq * 1000LL * 65536LL;
427 pps_freq = time_freq;
428 #endif /* PPS_SYNC */
430 if (modes & MOD_OFFSET) {
431 if (time_status & STA_NANO)
432 hardupdate(ntv->offset);
434 hardupdate(ntv->offset * 1000);
438 * Retrieve all clock variables. Note that the TAI offset is
439 * returned only by ntp_gettime();
441 if (time_status & STA_NANO)
442 ntv->offset = L_GINT(time_offset);
444 ntv->offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */
445 ntv->freq = L_GINT((time_freq / 1000LL) << 16);
446 ntv->maxerror = time_maxerror;
447 ntv->esterror = time_esterror;
448 ntv->status = time_status;
449 ntv->constant = time_constant;
450 if (time_status & STA_NANO)
451 ntv->precision = time_precision;
453 ntv->precision = time_precision / 1000;
454 ntv->tolerance = MAXFREQ * SCALE_PPM;
456 ntv->shift = pps_shift;
457 ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16);
458 if (time_status & STA_NANO)
459 ntv->jitter = pps_jitter;
461 ntv->jitter = pps_jitter / 1000;
462 ntv->stabil = pps_stabil;
463 ntv->calcnt = pps_calcnt;
464 ntv->errcnt = pps_errcnt;
465 ntv->jitcnt = pps_jitcnt;
466 ntv->stbcnt = pps_stbcnt;
467 #endif /* PPS_SYNC */
468 retval = ntp_is_time_error(time_status) ? TIME_ERROR : time_state;
475 #ifndef _SYS_SYSPROTO_H_
476 struct ntp_adjtime_args {
482 sys_ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap)
487 error = copyin(uap->tp, &ntv, sizeof(ntv));
489 error = kern_ntp_adjtime(td, &ntv, &retval);
491 error = copyout(&ntv, uap->tp, sizeof(ntv));
493 td->td_retval[0] = retval;
500 * second_overflow() - called after ntp_tick_adjust()
502 * This routine is ordinarily called immediately following the above
503 * routine ntp_tick_adjust(). While these two routines are normally
504 * combined, they are separated here only for the purposes of
508 ntp_update_second(int64_t *adjustment, time_t *newsec)
511 l_fp ftemp; /* 32/64-bit temporary */
516 * On rollover of the second both the nanosecond and microsecond
517 * clocks are updated and the state machine cranked as
518 * necessary. The phase adjustment to be used for the next
519 * second is calculated and the maximum error is increased by
522 time_maxerror += MAXFREQ / 1000;
525 * Leap second processing. If in leap-insert state at
526 * the end of the day, the system clock is set back one
527 * second; if in leap-delete state, the system clock is
528 * set ahead one second. The nano_time() routine or
529 * external clock driver will insure that reported time
530 * is always monotonic.
532 switch (time_state) {
537 if (time_status & STA_INS)
538 time_state = TIME_INS;
539 else if (time_status & STA_DEL)
540 time_state = TIME_DEL;
544 * Insert second 23:59:60 following second
548 if (!(time_status & STA_INS))
549 time_state = TIME_OK;
550 else if ((*newsec) % 86400 == 0) {
552 time_state = TIME_OOP;
558 * Delete second 23:59:59.
561 if (!(time_status & STA_DEL))
562 time_state = TIME_OK;
563 else if (((*newsec) + 1) % 86400 == 0) {
566 time_state = TIME_WAIT;
571 * Insert second in progress.
574 time_state = TIME_WAIT;
578 * Wait for status bits to clear.
581 if (!(time_status & (STA_INS | STA_DEL)))
582 time_state = TIME_OK;
586 * Compute the total time adjustment for the next second
587 * in ns. The offset is reduced by a factor depending on
588 * whether the PPS signal is operating. Note that the
589 * value is in effect scaled by the clock frequency,
590 * since the adjustment is added at each tick interrupt.
594 /* XXX even if PPS signal dies we should finish adjustment ? */
595 if (time_status & STA_PPSTIME && time_status &
597 L_RSHIFT(ftemp, pps_shift);
599 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
601 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
602 #endif /* PPS_SYNC */
604 L_SUB(time_offset, ftemp);
605 L_ADD(time_adj, time_freq);
608 * Apply any correction from adjtime(2). If more than one second
609 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500 PPM)
610 * until the last second is slewed the final < 500 usecs.
612 if (time_adjtime != 0) {
613 if (time_adjtime > 1000000)
615 else if (time_adjtime < -1000000)
617 else if (time_adjtime > 500)
619 else if (time_adjtime < -500)
622 tickrate = time_adjtime;
623 time_adjtime -= tickrate;
624 L_LINT(ftemp, tickrate * 1000);
625 L_ADD(time_adj, ftemp);
627 *adjustment = time_adj;
633 time_status &= ~STA_PPSSIGNAL;
634 #endif /* PPS_SYNC */
640 * ntp_init() - initialize variables and structures
642 * This routine must be called after the kernel variables hz and tick
643 * are set or changed and before the next tick interrupt. In this
644 * particular implementation, these values are assumed set elsewhere in
645 * the kernel. The design allows the clock frequency and tick interval
646 * to be changed while the system is running. So, this routine should
647 * probably be integrated with the code that does that.
654 * The following variables are initialized only at startup. Only
655 * those structures not cleared by the compiler need to be
656 * initialized, and these only in the simulator. In the actual
657 * kernel, any nonzero values here will quickly evaporate.
662 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;
663 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;
664 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;
667 #endif /* PPS_SYNC */
670 SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL);
673 * hardupdate() - local clock update
675 * This routine is called by ntp_adjtime() to update the local clock
676 * phase and frequency. The implementation is of an adaptive-parameter,
677 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
678 * time and frequency offset estimates for each call. If the kernel PPS
679 * discipline code is configured (PPS_SYNC), the PPS signal itself
680 * determines the new time offset, instead of the calling argument.
681 * Presumably, calls to ntp_adjtime() occur only when the caller
682 * believes the local clock is valid within some bound (+-128 ms with
683 * NTP). If the caller's time is far different than the PPS time, an
684 * argument will ensue, and it's not clear who will lose.
686 * For uncompensated quartz crystal oscillators and nominal update
687 * intervals less than 256 s, operation should be in phase-lock mode,
688 * where the loop is disciplined to phase. For update intervals greater
689 * than 1024 s, operation should be in frequency-lock mode, where the
690 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
691 * is selected by the STA_MODE status bit.
695 long offset; /* clock offset (ns) */
703 * Select how the phase is to be controlled and from which
704 * source. If the PPS signal is present and enabled to
705 * discipline the time, the PPS offset is used; otherwise, the
706 * argument offset is used.
708 if (!(time_status & STA_PLL))
710 if (!(time_status & STA_PPSTIME && time_status &
712 if (offset > MAXPHASE)
713 time_monitor = MAXPHASE;
714 else if (offset < -MAXPHASE)
715 time_monitor = -MAXPHASE;
717 time_monitor = offset;
718 L_LINT(time_offset, time_monitor);
722 * Select how the frequency is to be controlled and in which
723 * mode (PLL or FLL). If the PPS signal is present and enabled
724 * to discipline the frequency, the PPS frequency is used;
725 * otherwise, the argument offset is used to compute it.
727 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {
728 time_reftime = time_uptime;
731 if (time_status & STA_FREQHOLD || time_reftime == 0)
732 time_reftime = time_uptime;
733 mtemp = time_uptime - time_reftime;
734 L_LINT(ftemp, time_monitor);
735 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
737 L_ADD(time_freq, ftemp);
738 time_status &= ~STA_MODE;
739 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
741 L_LINT(ftemp, (time_monitor << 4) / mtemp);
742 L_RSHIFT(ftemp, SHIFT_FLL + 4);
743 L_ADD(time_freq, ftemp);
744 time_status |= STA_MODE;
746 time_reftime = time_uptime;
747 if (L_GINT(time_freq) > MAXFREQ)
748 L_LINT(time_freq, MAXFREQ);
749 else if (L_GINT(time_freq) < -MAXFREQ)
750 L_LINT(time_freq, -MAXFREQ);
755 * hardpps() - discipline CPU clock oscillator to external PPS signal
757 * This routine is called at each PPS interrupt in order to discipline
758 * the CPU clock oscillator to the PPS signal. There are two independent
759 * first-order feedback loops, one for the phase, the other for the
760 * frequency. The phase loop measures and grooms the PPS phase offset
761 * and leaves it in a handy spot for the seconds overflow routine. The
762 * frequency loop averages successive PPS phase differences and
763 * calculates the PPS frequency offset, which is also processed by the
764 * seconds overflow routine. The code requires the caller to capture the
765 * time and architecture-dependent hardware counter values in
766 * nanoseconds at the on-time PPS signal transition.
768 * Note that, on some Unix systems this routine runs at an interrupt
769 * priority level higher than the timer interrupt routine hardclock().
770 * Therefore, the variables used are distinct from the hardclock()
771 * variables, except for the actual time and frequency variables, which
772 * are determined by this routine and updated atomically.
775 * nsec - hardware counter at PPS
778 hardpps(struct timespec *tsp, long nsec)
780 long u_sec, u_nsec, v_nsec; /* temps */
786 * The signal is first processed by a range gate and frequency
787 * discriminator. The range gate rejects noise spikes outside
788 * the range +-500 us. The frequency discriminator rejects input
789 * signals with apparent frequency outside the range 1 +-500
790 * PPM. If two hits occur in the same second, we ignore the
791 * later hit; if not and a hit occurs outside the range gate,
792 * keep the later hit for later comparison, but do not process
795 time_status |= STA_PPSSIGNAL | STA_PPSJITTER;
796 time_status &= ~(STA_PPSWANDER | STA_PPSERROR);
797 pps_valid = PPS_VALID;
799 u_nsec = tsp->tv_nsec;
800 if (u_nsec >= (NANOSECOND >> 1)) {
801 u_nsec -= NANOSECOND;
804 v_nsec = u_nsec - pps_tf[0].tv_nsec;
805 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - MAXFREQ)
807 pps_tf[2] = pps_tf[1];
808 pps_tf[1] = pps_tf[0];
809 pps_tf[0].tv_sec = u_sec;
810 pps_tf[0].tv_nsec = u_nsec;
813 * Compute the difference between the current and previous
814 * counter values. If the difference exceeds 0.5 s, assume it
815 * has wrapped around, so correct 1.0 s. If the result exceeds
816 * the tick interval, the sample point has crossed a tick
817 * boundary during the last second, so correct the tick. Very
821 if (u_nsec > (NANOSECOND >> 1))
822 u_nsec -= NANOSECOND;
823 else if (u_nsec < -(NANOSECOND >> 1))
824 u_nsec += NANOSECOND;
825 pps_fcount += u_nsec;
826 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
828 time_status &= ~STA_PPSJITTER;
831 * A three-stage median filter is used to help denoise the PPS
832 * time. The median sample becomes the time offset estimate; the
833 * difference between the other two samples becomes the time
834 * dispersion (jitter) estimate.
836 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {
837 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {
838 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */
839 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;
840 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {
841 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */
842 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;
844 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */
845 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;
848 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {
849 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */
850 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;
851 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {
852 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */
853 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;
855 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */
856 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;
861 * Nominal jitter is due to PPS signal noise and interrupt
862 * latency. If it exceeds the popcorn threshold, the sample is
863 * discarded. otherwise, if so enabled, the time offset is
864 * updated. We can tolerate a modest loss of data here without
865 * much degrading time accuracy.
867 * The measurements being checked here were made with the system
868 * timecounter, so the popcorn threshold is not allowed to fall below
869 * the number of nanoseconds in two ticks of the timecounter. For a
870 * timecounter running faster than 1 GHz the lower bound is 2ns, just
871 * to avoid a nonsensical threshold of zero.
873 if (u_nsec > lmax(pps_jitter << PPS_POPCORN,
874 2 * (NANOSECOND / (long)qmin(NANOSECOND, tc_getfrequency())))) {
875 time_status |= STA_PPSJITTER;
877 } else if (time_status & STA_PPSTIME) {
878 time_monitor = -v_nsec;
879 L_LINT(time_offset, time_monitor);
881 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;
882 u_sec = pps_tf[0].tv_sec - pps_lastsec;
883 if (u_sec < (1 << pps_shift))
887 * At the end of the calibration interval the difference between
888 * the first and last counter values becomes the scaled
889 * frequency. It will later be divided by the length of the
890 * interval to determine the frequency update. If the frequency
891 * exceeds a sanity threshold, or if the actual calibration
892 * interval is not equal to the expected length, the data are
893 * discarded. We can tolerate a modest loss of data here without
894 * much degrading frequency accuracy.
897 v_nsec = -pps_fcount;
898 pps_lastsec = pps_tf[0].tv_sec;
900 u_nsec = MAXFREQ << pps_shift;
901 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << pps_shift)) {
902 time_status |= STA_PPSERROR;
908 * Here the raw frequency offset and wander (stability) is
909 * calculated. If the wander is less than the wander threshold
910 * for four consecutive averaging intervals, the interval is
911 * doubled; if it is greater than the threshold for four
912 * consecutive intervals, the interval is halved. The scaled
913 * frequency offset is converted to frequency offset. The
914 * stability metric is calculated as the average of recent
915 * frequency changes, but is used only for performance
918 L_LINT(ftemp, v_nsec);
919 L_RSHIFT(ftemp, pps_shift);
920 L_SUB(ftemp, pps_freq);
921 u_nsec = L_GINT(ftemp);
922 if (u_nsec > PPS_MAXWANDER) {
923 L_LINT(ftemp, PPS_MAXWANDER);
925 time_status |= STA_PPSWANDER;
927 } else if (u_nsec < -PPS_MAXWANDER) {
928 L_LINT(ftemp, -PPS_MAXWANDER);
930 time_status |= STA_PPSWANDER;
935 if (pps_intcnt >= 4) {
937 if (pps_shift < pps_shiftmax) {
941 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {
943 if (pps_shift > PPS_FAVG) {
950 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;
953 * The PPS frequency is recalculated and clamped to the maximum
954 * MAXFREQ. If enabled, the system clock frequency is updated as
957 L_ADD(pps_freq, ftemp);
958 u_nsec = L_GINT(pps_freq);
959 if (u_nsec > MAXFREQ)
960 L_LINT(pps_freq, MAXFREQ);
961 else if (u_nsec < -MAXFREQ)
962 L_LINT(pps_freq, -MAXFREQ);
963 if (time_status & STA_PPSFREQ)
964 time_freq = pps_freq;
969 #endif /* PPS_SYNC */
971 #ifndef _SYS_SYSPROTO_H_
972 struct adjtime_args {
973 struct timeval *delta;
974 struct timeval *olddelta;
979 sys_adjtime(struct thread *td, struct adjtime_args *uap)
981 struct timeval delta, olddelta, *deltap;
985 error = copyin(uap->delta, &delta, sizeof(delta));
991 error = kern_adjtime(td, deltap, &olddelta);
992 if (uap->olddelta && error == 0)
993 error = copyout(&olddelta, uap->olddelta, sizeof(olddelta));
998 kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta)
1004 if (delta != NULL) {
1005 error = priv_check(td, PRIV_ADJTIME);
1008 ltw = (int64_t)delta->tv_sec * 1000000 + delta->tv_usec;
1015 if (olddelta != NULL) {
1016 atv.tv_sec = ltr / 1000000;
1017 atv.tv_usec = ltr % 1000000;
1018 if (atv.tv_usec < 0) {
1019 atv.tv_usec += 1000000;
1027 static struct callout resettodr_callout;
1028 static int resettodr_period = 1800;
1031 periodic_resettodr(void *arg __unused)
1035 * Read of time_status is lock-less, which is fine since
1036 * ntp_is_time_error() operates on the consistent read value.
1038 if (!ntp_is_time_error(time_status))
1040 if (resettodr_period > 0)
1041 callout_schedule(&resettodr_callout, resettodr_period * hz);
1045 shutdown_resettodr(void *arg __unused, int howto __unused)
1048 callout_drain(&resettodr_callout);
1049 /* Another unlocked read of time_status */
1050 if (resettodr_period > 0 && !ntp_is_time_error(time_status))
1055 sysctl_resettodr_period(SYSCTL_HANDLER_ARGS)
1059 error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
1060 if (error || !req->newptr)
1064 if (resettodr_period == 0)
1065 callout_stop(&resettodr_callout);
1067 callout_reset(&resettodr_callout, resettodr_period * hz,
1068 periodic_resettodr, NULL);
1073 SYSCTL_PROC(_machdep, OID_AUTO, rtc_save_period, CTLTYPE_INT | CTLFLAG_RWTUN |
1074 CTLFLAG_MPSAFE, &resettodr_period, 1800, sysctl_resettodr_period, "I",
1075 "Save system time to RTC with this period (in seconds)");
1078 start_periodic_resettodr(void *arg __unused)
1081 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_resettodr, NULL,
1082 SHUTDOWN_PRI_FIRST);
1083 callout_init(&resettodr_callout, 1);
1084 if (resettodr_period == 0)
1086 callout_reset(&resettodr_callout, resettodr_period * hz,
1087 periodic_resettodr, NULL);
1090 SYSINIT(periodic_resettodr, SI_SUB_LAST, SI_ORDER_MIDDLE,
1091 start_periodic_resettodr, NULL);