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>
34 __FBSDID("$FreeBSD$");
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/sysproto.h>
41 #include <sys/eventhandler.h>
42 #include <sys/kernel.h>
46 #include <sys/mutex.h>
48 #include <sys/timex.h>
49 #include <sys/timetc.h>
50 #include <sys/timepps.h>
51 #include <sys/syscallsubr.h>
52 #include <sys/sysctl.h>
55 FEATURE(pps_sync, "Support usage of external PPS signal by kernel PLL");
59 * Single-precision macros for 64-bit machines
62 #define L_ADD(v, u) ((v) += (u))
63 #define L_SUB(v, u) ((v) -= (u))
64 #define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32)
65 #define L_NEG(v) ((v) = -(v))
66 #define L_RSHIFT(v, n) \
69 (v) = -(-(v) >> (n)); \
73 #define L_MPY(v, a) ((v) *= (a))
74 #define L_CLR(v) ((v) = 0)
75 #define L_ISNEG(v) ((v) < 0)
76 #define L_LINT(v, a) ((v) = (int64_t)(a) << 32)
77 #define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32)
80 * Generic NTP kernel interface
82 * These routines constitute the Network Time Protocol (NTP) interfaces
83 * for user and daemon application programs. The ntp_gettime() routine
84 * provides the time, maximum error (synch distance) and estimated error
85 * (dispersion) to client user application programs. The ntp_adjtime()
86 * routine is used by the NTP daemon to adjust the system clock to an
87 * externally derived time. The time offset and related variables set by
88 * this routine are used by other routines in this module to adjust the
89 * phase and frequency of the clock discipline loop which controls the
92 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO
93 * defined), the time at each tick interrupt is derived directly from
94 * the kernel time variable. When the kernel time is reckoned in
95 * microseconds, (NTP_NANO undefined), the time is derived from the
96 * kernel time variable together with a variable representing the
97 * leftover nanoseconds at the last tick interrupt. In either case, the
98 * current nanosecond time is reckoned from these values plus an
99 * interpolated value derived by the clock routines in another
100 * architecture-specific module. The interpolation can use either a
101 * dedicated counter or a processor cycle counter (PCC) implemented in
102 * some architectures.
104 * Note that all routines must run at priority splclock or higher.
107 * Phase/frequency-lock loop (PLL/FLL) definitions
109 * The nanosecond clock discipline uses two variable types, time
110 * variables and frequency variables. Both types are represented as 64-
111 * bit fixed-point quantities with the decimal point between two 32-bit
112 * halves. On a 32-bit machine, each half is represented as a single
113 * word and mathematical operations are done using multiple-precision
114 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is
117 * A time variable is a signed 64-bit fixed-point number in ns and
118 * fraction. It represents the remaining time offset to be amortized
119 * over succeeding tick interrupts. The maximum time offset is about
120 * 0.5 s and the resolution is about 2.3e-10 ns.
122 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
123 * 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
124 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
126 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
128 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
130 * A frequency variable is a signed 64-bit fixed-point number in ns/s
131 * and fraction. It represents the ns and fraction to be added to the
132 * kernel time variable at each second. The maximum frequency offset is
133 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s.
135 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
136 * 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
137 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
138 * |s s s s s s s s s s s s s| ns/s |
139 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
141 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
144 * The following variables establish the state of the PLL/FLL and the
145 * residual time and frequency offset of the local clock.
147 #define SHIFT_PLL 4 /* PLL loop gain (shift) */
148 #define SHIFT_FLL 2 /* FLL loop gain (shift) */
150 static int time_state = TIME_OK; /* clock state */
151 int time_status = STA_UNSYNC; /* clock status bits */
152 static long time_tai; /* TAI offset (s) */
153 static long time_monitor; /* last time offset scaled (ns) */
154 static long time_constant; /* poll interval (shift) (s) */
155 static long time_precision = 1; /* clock precision (ns) */
156 static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */
157 long time_esterror = MAXPHASE / 1000; /* estimated error (us) */
158 static long time_reftime; /* uptime at last adjustment (s) */
159 static l_fp time_offset; /* time offset (ns) */
160 static l_fp time_freq; /* frequency offset (ns/s) */
161 static l_fp time_adj; /* tick adjust (ns/s) */
163 static int64_t time_adjtime; /* correction from adjtime(2) (usec) */
165 static struct mtx ntp_lock;
166 MTX_SYSINIT(ntp, &ntp_lock, "ntp", MTX_SPIN);
168 #define NTP_LOCK() mtx_lock_spin(&ntp_lock)
169 #define NTP_UNLOCK() mtx_unlock_spin(&ntp_lock)
170 #define NTP_ASSERT_LOCKED() mtx_assert(&ntp_lock, MA_OWNED)
174 * The following variables are used when a pulse-per-second (PPS) signal
175 * is available and connected via a modem control lead. They establish
176 * the engineering parameters of the clock discipline loop when
177 * controlled by the PPS signal.
179 #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */
180 #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */
181 #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */
182 #define PPS_PAVG 4 /* phase avg interval (s) (shift) */
183 #define PPS_VALID 120 /* PPS signal watchdog max (s) */
184 #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */
185 #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */
187 static struct timespec pps_tf[3]; /* phase median filter */
188 static l_fp pps_freq; /* scaled frequency offset (ns/s) */
189 static long pps_fcount; /* frequency accumulator */
190 static long pps_jitter; /* nominal jitter (ns) */
191 static long pps_stabil; /* nominal stability (scaled ns/s) */
192 static long pps_lastsec; /* time at last calibration (s) */
193 static int pps_valid; /* signal watchdog counter */
194 static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */
195 static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */
196 static int pps_intcnt; /* wander counter */
199 * PPS signal quality monitors
201 static long pps_calcnt; /* calibration intervals */
202 static long pps_jitcnt; /* jitter limit exceeded */
203 static long pps_stbcnt; /* stability limit exceeded */
204 static long pps_errcnt; /* calibration errors */
205 #endif /* PPS_SYNC */
207 * End of phase/frequency-lock loop (PLL/FLL) definitions
210 static void ntp_init(void);
211 static void hardupdate(long offset);
212 static void ntp_gettime1(struct ntptimeval *ntvp);
213 static bool ntp_is_time_error(int tsl);
216 ntp_is_time_error(int tsl)
220 * Status word error decode. If any of these conditions occur,
221 * an error is returned, instead of the status word. Most
222 * applications will care only about the fact the system clock
223 * may not be trusted, not about the details.
225 * Hardware or software error
227 if ((tsl & (STA_UNSYNC | STA_CLOCKERR)) ||
230 * PPS signal lost when either time or frequency synchronization
233 (tsl & (STA_PPSFREQ | STA_PPSTIME) &&
234 !(tsl & STA_PPSSIGNAL)) ||
237 * PPS jitter exceeded when time synchronization requested
239 (tsl & STA_PPSTIME && tsl & STA_PPSJITTER) ||
242 * PPS wander exceeded or calibration error when frequency
243 * synchronization requested
245 (tsl & STA_PPSFREQ &&
246 tsl & (STA_PPSWANDER | STA_PPSERROR)))
253 ntp_gettime1(struct ntptimeval *ntvp)
255 struct timespec atv; /* nanosecond time */
260 ntvp->time.tv_sec = atv.tv_sec;
261 ntvp->time.tv_nsec = atv.tv_nsec;
262 ntvp->maxerror = time_maxerror;
263 ntvp->esterror = time_esterror;
264 ntvp->tai = time_tai;
265 ntvp->time_state = time_state;
267 if (ntp_is_time_error(time_status))
268 ntvp->time_state = TIME_ERROR;
272 * ntp_gettime() - NTP user application interface
274 * See the timex.h header file for synopsis and API description. Note that
275 * the TAI offset is returned in the ntvtimeval.tai structure member.
277 #ifndef _SYS_SYSPROTO_H_
278 struct ntp_gettime_args {
279 struct ntptimeval *ntvp;
284 sys_ntp_gettime(struct thread *td, struct ntp_gettime_args *uap)
286 struct ntptimeval ntv;
288 memset(&ntv, 0, sizeof(ntv));
294 td->td_retval[0] = ntv.time_state;
295 return (copyout(&ntv, uap->ntvp, sizeof(ntv)));
299 ntp_sysctl(SYSCTL_HANDLER_ARGS)
301 struct ntptimeval ntv; /* temporary structure */
303 memset(&ntv, 0, sizeof(ntv));
309 return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req));
312 SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
314 SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE | CTLFLAG_RD |
315 CTLFLAG_MPSAFE, 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval",
319 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW,
320 &pps_shiftmax, 0, "Max interval duration (sec) (shift)");
321 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW,
322 &pps_shift, 0, "Interval duration (sec) (shift)");
323 SYSCTL_LONG(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD,
324 &time_monitor, 0, "Last time offset scaled (ns)");
326 SYSCTL_S64(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD | CTLFLAG_MPSAFE,
328 "Scaled frequency offset (ns/sec)");
329 SYSCTL_S64(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD | CTLFLAG_MPSAFE,
331 "Frequency offset (ns/sec)");
335 * ntp_adjtime() - NTP daemon application interface
337 * See the timex.h header file for synopsis and API description. Note that
338 * the timex.constant structure member has a dual purpose to set the time
339 * constant and to set the TAI offset.
342 kern_ntp_adjtime(struct thread *td, struct timex *ntv, int *retvalp)
344 long freq; /* frequency ns/s) */
345 int modes; /* mode bits from structure */
349 * Update selected clock variables - only the superuser can
350 * change anything. Note that there is no error checking here on
351 * the assumption the superuser should know what it is doing.
352 * Note that either the time constant or TAI offset are loaded
353 * from the ntv.constant member, depending on the mode bits. If
354 * the STA_PLL bit in the status word is cleared, the state and
355 * status words are reset to the initial values at boot.
360 error = priv_check(td, PRIV_NTP_ADJTIME);
364 if (modes & MOD_MAXERROR)
365 time_maxerror = ntv->maxerror;
366 if (modes & MOD_ESTERROR)
367 time_esterror = ntv->esterror;
368 if (modes & MOD_STATUS) {
369 if (time_status & STA_PLL && !(ntv->status & STA_PLL)) {
370 time_state = TIME_OK;
371 time_status = STA_UNSYNC;
373 pps_shift = PPS_FAVG;
374 #endif /* PPS_SYNC */
376 time_status &= STA_RONLY;
377 time_status |= ntv->status & ~STA_RONLY;
379 if (modes & MOD_TIMECONST) {
380 if (ntv->constant < 0)
382 else if (ntv->constant > MAXTC)
383 time_constant = MAXTC;
385 time_constant = ntv->constant;
387 if (modes & MOD_TAI) {
388 if (ntv->constant > 0) /* XXX zero & negative numbers ? */
389 time_tai = ntv->constant;
392 if (modes & MOD_PPSMAX) {
393 if (ntv->shift < PPS_FAVG)
394 pps_shiftmax = PPS_FAVG;
395 else if (ntv->shift > PPS_FAVGMAX)
396 pps_shiftmax = PPS_FAVGMAX;
398 pps_shiftmax = ntv->shift;
400 #endif /* PPS_SYNC */
401 if (modes & MOD_NANO)
402 time_status |= STA_NANO;
403 if (modes & MOD_MICRO)
404 time_status &= ~STA_NANO;
405 if (modes & MOD_CLKB)
406 time_status |= STA_CLK;
407 if (modes & MOD_CLKA)
408 time_status &= ~STA_CLK;
409 if (modes & MOD_FREQUENCY) {
410 freq = (ntv->freq * 1000LL) >> 16;
412 L_LINT(time_freq, MAXFREQ);
413 else if (freq < -MAXFREQ)
414 L_LINT(time_freq, -MAXFREQ);
417 * ntv->freq is [PPM * 2^16] = [us/s * 2^16]
418 * time_freq is [ns/s * 2^32]
420 time_freq = ntv->freq * 1000LL * 65536LL;
423 pps_freq = time_freq;
424 #endif /* PPS_SYNC */
426 if (modes & MOD_OFFSET) {
427 if (time_status & STA_NANO)
428 hardupdate(ntv->offset);
430 hardupdate(ntv->offset * 1000);
434 * Retrieve all clock variables. Note that the TAI offset is
435 * returned only by ntp_gettime();
437 if (time_status & STA_NANO)
438 ntv->offset = L_GINT(time_offset);
440 ntv->offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */
441 ntv->freq = L_GINT((time_freq / 1000LL) << 16);
442 ntv->maxerror = time_maxerror;
443 ntv->esterror = time_esterror;
444 ntv->status = time_status;
445 ntv->constant = time_constant;
446 if (time_status & STA_NANO)
447 ntv->precision = time_precision;
449 ntv->precision = time_precision / 1000;
450 ntv->tolerance = MAXFREQ * SCALE_PPM;
452 ntv->shift = pps_shift;
453 ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16);
454 if (time_status & STA_NANO)
455 ntv->jitter = pps_jitter;
457 ntv->jitter = pps_jitter / 1000;
458 ntv->stabil = pps_stabil;
459 ntv->calcnt = pps_calcnt;
460 ntv->errcnt = pps_errcnt;
461 ntv->jitcnt = pps_jitcnt;
462 ntv->stbcnt = pps_stbcnt;
463 #endif /* PPS_SYNC */
464 retval = ntp_is_time_error(time_status) ? TIME_ERROR : time_state;
471 #ifndef _SYS_SYSPROTO_H_
472 struct ntp_adjtime_args {
478 sys_ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap)
483 error = copyin(uap->tp, &ntv, sizeof(ntv));
485 error = kern_ntp_adjtime(td, &ntv, &retval);
487 error = copyout(&ntv, uap->tp, sizeof(ntv));
489 td->td_retval[0] = retval;
496 * second_overflow() - called after ntp_tick_adjust()
498 * This routine is ordinarily called immediately following the above
499 * routine ntp_tick_adjust(). While these two routines are normally
500 * combined, they are separated here only for the purposes of
504 ntp_update_second(int64_t *adjustment, time_t *newsec)
507 l_fp ftemp; /* 32/64-bit temporary */
512 * On rollover of the second both the nanosecond and microsecond
513 * clocks are updated and the state machine cranked as
514 * necessary. The phase adjustment to be used for the next
515 * second is calculated and the maximum error is increased by
518 time_maxerror += MAXFREQ / 1000;
521 * Leap second processing. If in leap-insert state at
522 * the end of the day, the system clock is set back one
523 * second; if in leap-delete state, the system clock is
524 * set ahead one second. The nano_time() routine or
525 * external clock driver will insure that reported time
526 * is always monotonic.
528 switch (time_state) {
533 if (time_status & STA_INS)
534 time_state = TIME_INS;
535 else if (time_status & STA_DEL)
536 time_state = TIME_DEL;
540 * Insert second 23:59:60 following second
544 if (!(time_status & STA_INS))
545 time_state = TIME_OK;
546 else if ((*newsec) % 86400 == 0) {
548 time_state = TIME_OOP;
554 * Delete second 23:59:59.
557 if (!(time_status & STA_DEL))
558 time_state = TIME_OK;
559 else if (((*newsec) + 1) % 86400 == 0) {
562 time_state = TIME_WAIT;
567 * Insert second in progress.
570 time_state = TIME_WAIT;
574 * Wait for status bits to clear.
577 if (!(time_status & (STA_INS | STA_DEL)))
578 time_state = TIME_OK;
582 * Compute the total time adjustment for the next second
583 * in ns. The offset is reduced by a factor depending on
584 * whether the PPS signal is operating. Note that the
585 * value is in effect scaled by the clock frequency,
586 * since the adjustment is added at each tick interrupt.
590 /* XXX even if PPS signal dies we should finish adjustment ? */
591 if (time_status & STA_PPSTIME && time_status &
593 L_RSHIFT(ftemp, pps_shift);
595 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
597 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
598 #endif /* PPS_SYNC */
600 L_SUB(time_offset, ftemp);
601 L_ADD(time_adj, time_freq);
604 * Apply any correction from adjtime(2). If more than one second
605 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500 PPM)
606 * until the last second is slewed the final < 500 usecs.
608 if (time_adjtime != 0) {
609 if (time_adjtime > 1000000)
611 else if (time_adjtime < -1000000)
613 else if (time_adjtime > 500)
615 else if (time_adjtime < -500)
618 tickrate = time_adjtime;
619 time_adjtime -= tickrate;
620 L_LINT(ftemp, tickrate * 1000);
621 L_ADD(time_adj, ftemp);
623 *adjustment = time_adj;
629 time_status &= ~STA_PPSSIGNAL;
630 #endif /* PPS_SYNC */
636 * ntp_init() - initialize variables and structures
638 * This routine must be called after the kernel variables hz and tick
639 * are set or changed and before the next tick interrupt. In this
640 * particular implementation, these values are assumed set elsewhere in
641 * the kernel. The design allows the clock frequency and tick interval
642 * to be changed while the system is running. So, this routine should
643 * probably be integrated with the code that does that.
650 * The following variables are initialized only at startup. Only
651 * those structures not cleared by the compiler need to be
652 * initialized, and these only in the simulator. In the actual
653 * kernel, any nonzero values here will quickly evaporate.
658 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;
659 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;
660 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;
663 #endif /* PPS_SYNC */
666 SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL);
669 * hardupdate() - local clock update
671 * This routine is called by ntp_adjtime() to update the local clock
672 * phase and frequency. The implementation is of an adaptive-parameter,
673 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
674 * time and frequency offset estimates for each call. If the kernel PPS
675 * discipline code is configured (PPS_SYNC), the PPS signal itself
676 * determines the new time offset, instead of the calling argument.
677 * Presumably, calls to ntp_adjtime() occur only when the caller
678 * believes the local clock is valid within some bound (+-128 ms with
679 * NTP). If the caller's time is far different than the PPS time, an
680 * argument will ensue, and it's not clear who will lose.
682 * For uncompensated quartz crystal oscillators and nominal update
683 * intervals less than 256 s, operation should be in phase-lock mode,
684 * where the loop is disciplined to phase. For update intervals greater
685 * than 1024 s, operation should be in frequency-lock mode, where the
686 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
687 * is selected by the STA_MODE status bit.
691 long offset; /* clock offset (ns) */
699 * Select how the phase is to be controlled and from which
700 * source. If the PPS signal is present and enabled to
701 * discipline the time, the PPS offset is used; otherwise, the
702 * argument offset is used.
704 if (!(time_status & STA_PLL))
706 if (!(time_status & STA_PPSTIME && time_status &
708 if (offset > MAXPHASE)
709 time_monitor = MAXPHASE;
710 else if (offset < -MAXPHASE)
711 time_monitor = -MAXPHASE;
713 time_monitor = offset;
714 L_LINT(time_offset, time_monitor);
718 * Select how the frequency is to be controlled and in which
719 * mode (PLL or FLL). If the PPS signal is present and enabled
720 * to discipline the frequency, the PPS frequency is used;
721 * otherwise, the argument offset is used to compute it.
723 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {
724 time_reftime = time_uptime;
727 if (time_status & STA_FREQHOLD || time_reftime == 0)
728 time_reftime = time_uptime;
729 mtemp = time_uptime - time_reftime;
730 L_LINT(ftemp, time_monitor);
731 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
733 L_ADD(time_freq, ftemp);
734 time_status &= ~STA_MODE;
735 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
737 L_LINT(ftemp, (time_monitor << 4) / mtemp);
738 L_RSHIFT(ftemp, SHIFT_FLL + 4);
739 L_ADD(time_freq, ftemp);
740 time_status |= STA_MODE;
742 time_reftime = time_uptime;
743 if (L_GINT(time_freq) > MAXFREQ)
744 L_LINT(time_freq, MAXFREQ);
745 else if (L_GINT(time_freq) < -MAXFREQ)
746 L_LINT(time_freq, -MAXFREQ);
751 * hardpps() - discipline CPU clock oscillator to external PPS signal
753 * This routine is called at each PPS interrupt in order to discipline
754 * the CPU clock oscillator to the PPS signal. There are two independent
755 * first-order feedback loops, one for the phase, the other for the
756 * frequency. The phase loop measures and grooms the PPS phase offset
757 * and leaves it in a handy spot for the seconds overflow routine. The
758 * frequency loop averages successive PPS phase differences and
759 * calculates the PPS frequency offset, which is also processed by the
760 * seconds overflow routine. The code requires the caller to capture the
761 * time and architecture-dependent hardware counter values in
762 * nanoseconds at the on-time PPS signal transition.
764 * Note that, on some Unix systems this routine runs at an interrupt
765 * priority level higher than the timer interrupt routine hardclock().
766 * Therefore, the variables used are distinct from the hardclock()
767 * variables, except for the actual time and frequency variables, which
768 * are determined by this routine and updated atomically.
771 * nsec - hardware counter at PPS
774 hardpps(struct timespec *tsp, long nsec)
776 long u_sec, u_nsec, v_nsec; /* temps */
782 * The signal is first processed by a range gate and frequency
783 * discriminator. The range gate rejects noise spikes outside
784 * the range +-500 us. The frequency discriminator rejects input
785 * signals with apparent frequency outside the range 1 +-500
786 * PPM. If two hits occur in the same second, we ignore the
787 * later hit; if not and a hit occurs outside the range gate,
788 * keep the later hit for later comparison, but do not process
791 time_status |= STA_PPSSIGNAL | STA_PPSJITTER;
792 time_status &= ~(STA_PPSWANDER | STA_PPSERROR);
793 pps_valid = PPS_VALID;
795 u_nsec = tsp->tv_nsec;
796 if (u_nsec >= (NANOSECOND >> 1)) {
797 u_nsec -= NANOSECOND;
800 v_nsec = u_nsec - pps_tf[0].tv_nsec;
801 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - MAXFREQ)
803 pps_tf[2] = pps_tf[1];
804 pps_tf[1] = pps_tf[0];
805 pps_tf[0].tv_sec = u_sec;
806 pps_tf[0].tv_nsec = u_nsec;
809 * Compute the difference between the current and previous
810 * counter values. If the difference exceeds 0.5 s, assume it
811 * has wrapped around, so correct 1.0 s. If the result exceeds
812 * the tick interval, the sample point has crossed a tick
813 * boundary during the last second, so correct the tick. Very
817 if (u_nsec > (NANOSECOND >> 1))
818 u_nsec -= NANOSECOND;
819 else if (u_nsec < -(NANOSECOND >> 1))
820 u_nsec += NANOSECOND;
821 pps_fcount += u_nsec;
822 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
824 time_status &= ~STA_PPSJITTER;
827 * A three-stage median filter is used to help denoise the PPS
828 * time. The median sample becomes the time offset estimate; the
829 * difference between the other two samples becomes the time
830 * dispersion (jitter) estimate.
832 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {
833 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {
834 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */
835 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;
836 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {
837 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */
838 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;
840 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */
841 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;
844 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {
845 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */
846 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;
847 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {
848 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */
849 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;
851 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */
852 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;
857 * Nominal jitter is due to PPS signal noise and interrupt
858 * latency. If it exceeds the popcorn threshold, the sample is
859 * discarded. otherwise, if so enabled, the time offset is
860 * updated. We can tolerate a modest loss of data here without
861 * much degrading time accuracy.
863 * The measurements being checked here were made with the system
864 * timecounter, so the popcorn threshold is not allowed to fall below
865 * the number of nanoseconds in two ticks of the timecounter. For a
866 * timecounter running faster than 1 GHz the lower bound is 2ns, just
867 * to avoid a nonsensical threshold of zero.
869 if (u_nsec > lmax(pps_jitter << PPS_POPCORN,
870 2 * (NANOSECOND / (long)qmin(NANOSECOND, tc_getfrequency())))) {
871 time_status |= STA_PPSJITTER;
873 } else if (time_status & STA_PPSTIME) {
874 time_monitor = -v_nsec;
875 L_LINT(time_offset, time_monitor);
877 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;
878 u_sec = pps_tf[0].tv_sec - pps_lastsec;
879 if (u_sec < (1 << pps_shift))
883 * At the end of the calibration interval the difference between
884 * the first and last counter values becomes the scaled
885 * frequency. It will later be divided by the length of the
886 * interval to determine the frequency update. If the frequency
887 * exceeds a sanity threshold, or if the actual calibration
888 * interval is not equal to the expected length, the data are
889 * discarded. We can tolerate a modest loss of data here without
890 * much degrading frequency accuracy.
893 v_nsec = -pps_fcount;
894 pps_lastsec = pps_tf[0].tv_sec;
896 u_nsec = MAXFREQ << pps_shift;
897 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << pps_shift)) {
898 time_status |= STA_PPSERROR;
904 * Here the raw frequency offset and wander (stability) is
905 * calculated. If the wander is less than the wander threshold
906 * for four consecutive averaging intervals, the interval is
907 * doubled; if it is greater than the threshold for four
908 * consecutive intervals, the interval is halved. The scaled
909 * frequency offset is converted to frequency offset. The
910 * stability metric is calculated as the average of recent
911 * frequency changes, but is used only for performance
914 L_LINT(ftemp, v_nsec);
915 L_RSHIFT(ftemp, pps_shift);
916 L_SUB(ftemp, pps_freq);
917 u_nsec = L_GINT(ftemp);
918 if (u_nsec > PPS_MAXWANDER) {
919 L_LINT(ftemp, PPS_MAXWANDER);
921 time_status |= STA_PPSWANDER;
923 } else if (u_nsec < -PPS_MAXWANDER) {
924 L_LINT(ftemp, -PPS_MAXWANDER);
926 time_status |= STA_PPSWANDER;
931 if (pps_intcnt >= 4) {
933 if (pps_shift < pps_shiftmax) {
937 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {
939 if (pps_shift > PPS_FAVG) {
946 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;
949 * The PPS frequency is recalculated and clamped to the maximum
950 * MAXFREQ. If enabled, the system clock frequency is updated as
953 L_ADD(pps_freq, ftemp);
954 u_nsec = L_GINT(pps_freq);
955 if (u_nsec > MAXFREQ)
956 L_LINT(pps_freq, MAXFREQ);
957 else if (u_nsec < -MAXFREQ)
958 L_LINT(pps_freq, -MAXFREQ);
959 if (time_status & STA_PPSFREQ)
960 time_freq = pps_freq;
965 #endif /* PPS_SYNC */
967 #ifndef _SYS_SYSPROTO_H_
968 struct adjtime_args {
969 struct timeval *delta;
970 struct timeval *olddelta;
975 sys_adjtime(struct thread *td, struct adjtime_args *uap)
977 struct timeval delta, olddelta, *deltap;
981 error = copyin(uap->delta, &delta, sizeof(delta));
987 error = kern_adjtime(td, deltap, &olddelta);
988 if (uap->olddelta && error == 0)
989 error = copyout(&olddelta, uap->olddelta, sizeof(olddelta));
994 kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta)
1000 if (delta != NULL) {
1001 error = priv_check(td, PRIV_ADJTIME);
1004 ltw = (int64_t)delta->tv_sec * 1000000 + delta->tv_usec;
1011 if (olddelta != NULL) {
1012 atv.tv_sec = ltr / 1000000;
1013 atv.tv_usec = ltr % 1000000;
1014 if (atv.tv_usec < 0) {
1015 atv.tv_usec += 1000000;
1023 static struct callout resettodr_callout;
1024 static int resettodr_period = 1800;
1027 periodic_resettodr(void *arg __unused)
1031 * Read of time_status is lock-less, which is fine since
1032 * ntp_is_time_error() operates on the consistent read value.
1034 if (!ntp_is_time_error(time_status))
1036 if (resettodr_period > 0)
1037 callout_schedule(&resettodr_callout, resettodr_period * hz);
1041 shutdown_resettodr(void *arg __unused, int howto __unused)
1044 callout_drain(&resettodr_callout);
1045 /* Another unlocked read of time_status */
1046 if (resettodr_period > 0 && !ntp_is_time_error(time_status))
1051 sysctl_resettodr_period(SYSCTL_HANDLER_ARGS)
1055 error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
1056 if (error || !req->newptr)
1060 if (resettodr_period == 0)
1061 callout_stop(&resettodr_callout);
1063 callout_reset(&resettodr_callout, resettodr_period * hz,
1064 periodic_resettodr, NULL);
1069 SYSCTL_PROC(_machdep, OID_AUTO, rtc_save_period, CTLTYPE_INT | CTLFLAG_RWTUN |
1070 CTLFLAG_MPSAFE, &resettodr_period, 1800, sysctl_resettodr_period, "I",
1071 "Save system time to RTC with this period (in seconds)");
1074 start_periodic_resettodr(void *arg __unused)
1077 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_resettodr, NULL,
1078 SHUTDOWN_PRI_FIRST);
1079 callout_init(&resettodr_callout, 1);
1080 if (resettodr_period == 0)
1082 callout_reset(&resettodr_callout, resettodr_period * hz,
1083 periodic_resettodr, NULL);
1086 SYSINIT(periodic_resettodr, SI_SUB_LAST, SI_ORDER_MIDDLE,
1087 start_periodic_resettodr, NULL);