1/* $NetBSD: kern_ntptime.c,v 1.57 2015/11/23 23:45:44 joerg Exp $ */
2
3/*-
4 * Copyright (c) 2008 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/*-
30 ***********************************************************************
31 * *
32 * Copyright (c) David L. Mills 1993-2001 *
33 * *
34 * Permission to use, copy, modify, and distribute this software and *
35 * its documentation for any purpose and without fee is hereby *
36 * granted, provided that the above copyright notice appears in all *
37 * copies and that both the copyright notice and this permission *
38 * notice appear in supporting documentation, and that the name *
39 * University of Delaware not be used in advertising or publicity *
40 * pertaining to distribution of the software without specific, *
41 * written prior permission. The University of Delaware makes no *
42 * representations about the suitability this software for any *
43 * purpose. It is provided "as is" without express or implied *
44 * warranty. *
45 * *
46 **********************************************************************/
47
48/*
49 * Adapted from the original sources for FreeBSD and timecounters by:
50 * Poul-Henning Kamp <phk@FreeBSD.org>.
51 *
52 * The 32bit version of the "LP" macros seems a bit past its "sell by"
53 * date so I have retained only the 64bit version and included it directly
54 * in this file.
55 *
56 * Only minor changes done to interface with the timecounters over in
57 * sys/kern/kern_clock.c. Some of the comments below may be (even more)
58 * confusing and/or plain wrong in that context.
59 */
60
61#include <sys/cdefs.h>
62/* __FBSDID("$FreeBSD: src/sys/kern/kern_ntptime.c,v 1.59 2005/05/28 14:34:41 rwatson Exp $"); */
63__KERNEL_RCSID(0, "$NetBSD: kern_ntptime.c,v 1.57 2015/11/23 23:45:44 joerg Exp $");
64
65#ifdef _KERNEL_OPT
66#include "opt_ntp.h"
67#endif
68
69#include <sys/param.h>
70#include <sys/resourcevar.h>
71#include <sys/systm.h>
72#include <sys/kernel.h>
73#include <sys/proc.h>
74#include <sys/sysctl.h>
75#include <sys/timex.h>
76#include <sys/vnode.h>
77#include <sys/kauth.h>
78#include <sys/mount.h>
79#include <sys/syscallargs.h>
80#include <sys/cpu.h>
81
82#include <compat/sys/timex.h>
83
84/*
85 * Single-precision macros for 64-bit machines
86 */
87typedef int64_t l_fp;
88#define L_ADD(v, u) ((v) += (u))
89#define L_SUB(v, u) ((v) -= (u))
90#define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32)
91#define L_NEG(v) ((v) = -(v))
92#define L_RSHIFT(v, n) \
93 do { \
94 if ((v) < 0) \
95 (v) = -(-(v) >> (n)); \
96 else \
97 (v) = (v) >> (n); \
98 } while (0)
99#define L_MPY(v, a) ((v) *= (a))
100#define L_CLR(v) ((v) = 0)
101#define L_ISNEG(v) ((v) < 0)
102#define L_LINT(v, a) ((v) = (int64_t)((uint64_t)(a) << 32))
103#define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32)
104
105#ifdef NTP
106/*
107 * Generic NTP kernel interface
108 *
109 * These routines constitute the Network Time Protocol (NTP) interfaces
110 * for user and daemon application programs. The ntp_gettime() routine
111 * provides the time, maximum error (synch distance) and estimated error
112 * (dispersion) to client user application programs. The ntp_adjtime()
113 * routine is used by the NTP daemon to adjust the system clock to an
114 * externally derived time. The time offset and related variables set by
115 * this routine are used by other routines in this module to adjust the
116 * phase and frequency of the clock discipline loop which controls the
117 * system clock.
118 *
119 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO
120 * defined), the time at each tick interrupt is derived directly from
121 * the kernel time variable. When the kernel time is reckoned in
122 * microseconds, (NTP_NANO undefined), the time is derived from the
123 * kernel time variable together with a variable representing the
124 * leftover nanoseconds at the last tick interrupt. In either case, the
125 * current nanosecond time is reckoned from these values plus an
126 * interpolated value derived by the clock routines in another
127 * architecture-specific module. The interpolation can use either a
128 * dedicated counter or a processor cycle counter (PCC) implemented in
129 * some architectures.
130 *
131 * Note that all routines must run at priority splclock or higher.
132 */
133/*
134 * Phase/frequency-lock loop (PLL/FLL) definitions
135 *
136 * The nanosecond clock discipline uses two variable types, time
137 * variables and frequency variables. Both types are represented as 64-
138 * bit fixed-point quantities with the decimal point between two 32-bit
139 * halves. On a 32-bit machine, each half is represented as a single
140 * word and mathematical operations are done using multiple-precision
141 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is
142 * used.
143 *
144 * A time variable is a signed 64-bit fixed-point number in ns and
145 * fraction. It represents the remaining time offset to be amortized
146 * over succeeding tick interrupts. The maximum time offset is about
147 * 0.5 s and the resolution is about 2.3e-10 ns.
148 *
149 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
150 * 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
151 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
152 * |s s s| ns |
153 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
154 * | fraction |
155 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
156 *
157 * A frequency variable is a signed 64-bit fixed-point number in ns/s
158 * and fraction. It represents the ns and fraction to be added to the
159 * kernel time variable at each second. The maximum frequency offset is
160 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s.
161 *
162 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
163 * 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
164 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
165 * |s s s s s s s s s s s s s| ns/s |
166 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
167 * | fraction |
168 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
169 */
170/*
171 * The following variables establish the state of the PLL/FLL and the
172 * residual time and frequency offset of the local clock.
173 */
174#define SHIFT_PLL 4 /* PLL loop gain (shift) */
175#define SHIFT_FLL 2 /* FLL loop gain (shift) */
176
177static int time_state = TIME_OK; /* clock state */
178static int time_status = STA_UNSYNC; /* clock status bits */
179static long time_tai; /* TAI offset (s) */
180static long time_monitor; /* last time offset scaled (ns) */
181static long time_constant; /* poll interval (shift) (s) */
182static long time_precision = 1; /* clock precision (ns) */
183static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */
184static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */
185static time_t time_reftime; /* time at last adjustment (s) */
186static l_fp time_offset; /* time offset (ns) */
187static l_fp time_freq; /* frequency offset (ns/s) */
188#endif /* NTP */
189
190static l_fp time_adj; /* tick adjust (ns/s) */
191int64_t time_adjtime; /* correction from adjtime(2) (usec) */
192
193extern int time_adjusted; /* ntp might have changed the system time */
194
195#ifdef NTP
196#ifdef PPS_SYNC
197/*
198 * The following variables are used when a pulse-per-second (PPS) signal
199 * is available and connected via a modem control lead. They establish
200 * the engineering parameters of the clock discipline loop when
201 * controlled by the PPS signal.
202 */
203#define PPS_FAVG 2 /* min freq avg interval (s) (shift) */
204#define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */
205#define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */
206#define PPS_PAVG 4 /* phase avg interval (s) (shift) */
207#define PPS_VALID 120 /* PPS signal watchdog max (s) */
208#define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */
209#define PPS_POPCORN 2 /* popcorn spike threshold (shift) */
210
211static struct timespec pps_tf[3]; /* phase median filter */
212static l_fp pps_freq; /* scaled frequency offset (ns/s) */
213static long pps_fcount; /* frequency accumulator */
214static long pps_jitter; /* nominal jitter (ns) */
215static long pps_stabil; /* nominal stability (scaled ns/s) */
216static long pps_lastsec; /* time at last calibration (s) */
217static int pps_valid; /* signal watchdog counter */
218static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */
219static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */
220static int pps_intcnt; /* wander counter */
221
222/*
223 * PPS signal quality monitors
224 */
225static long pps_calcnt; /* calibration intervals */
226static long pps_jitcnt; /* jitter limit exceeded */
227static long pps_stbcnt; /* stability limit exceeded */
228static long pps_errcnt; /* calibration errors */
229#endif /* PPS_SYNC */
230/*
231 * End of phase/frequency-lock loop (PLL/FLL) definitions
232 */
233
234static void hardupdate(long offset);
235
236/*
237 * ntp_gettime() - NTP user application interface
238 */
239void
240ntp_gettime(struct ntptimeval *ntv)
241{
242
243 mutex_spin_enter(&timecounter_lock);
244 nanotime(&ntv->time);
245 ntv->maxerror = time_maxerror;
246 ntv->esterror = time_esterror;
247 ntv->tai = time_tai;
248 ntv->time_state = time_state;
249 mutex_spin_exit(&timecounter_lock);
250}
251
252/* ARGSUSED */
253/*
254 * ntp_adjtime() - NTP daemon application interface
255 */
256int
257sys_ntp_adjtime(struct lwp *l, const struct sys_ntp_adjtime_args *uap, register_t *retval)
258{
259 /* {
260 syscallarg(struct timex *) tp;
261 } */
262 struct timex ntv;
263 int error;
264
265 error = copyin((void *)SCARG(uap, tp), (void *)&ntv, sizeof(ntv));
266 if (error != 0)
267 return (error);
268
269 if (ntv.modes != 0 && (error = kauth_authorize_system(l->l_cred,
270 KAUTH_SYSTEM_TIME, KAUTH_REQ_SYSTEM_TIME_NTPADJTIME, NULL,
271 NULL, NULL)) != 0)
272 return (error);
273
274 ntp_adjtime1(&ntv);
275
276 error = copyout((void *)&ntv, (void *)SCARG(uap, tp), sizeof(ntv));
277 if (!error)
278 *retval = ntp_timestatus();
279
280 return error;
281}
282
283void
284ntp_adjtime1(struct timex *ntv)
285{
286 long freq;
287 int modes;
288
289 /*
290 * Update selected clock variables - only the superuser can
291 * change anything. Note that there is no error checking here on
292 * the assumption the superuser should know what it is doing.
293 * Note that either the time constant or TAI offset are loaded
294 * from the ntv.constant member, depending on the mode bits. If
295 * the STA_PLL bit in the status word is cleared, the state and
296 * status words are reset to the initial values at boot.
297 */
298 mutex_spin_enter(&timecounter_lock);
299 modes = ntv->modes;
300 if (modes != 0)
301 /* We need to save the system time during shutdown */
302 time_adjusted |= 2;
303 if (modes & MOD_MAXERROR)
304 time_maxerror = ntv->maxerror;
305 if (modes & MOD_ESTERROR)
306 time_esterror = ntv->esterror;
307 if (modes & MOD_STATUS) {
308 if (time_status & STA_PLL && !(ntv->status & STA_PLL)) {
309 time_state = TIME_OK;
310 time_status = STA_UNSYNC;
311#ifdef PPS_SYNC
312 pps_shift = PPS_FAVG;
313#endif /* PPS_SYNC */
314 }
315 time_status &= STA_RONLY;
316 time_status |= ntv->status & ~STA_RONLY;
317 }
318 if (modes & MOD_TIMECONST) {
319 if (ntv->constant < 0)
320 time_constant = 0;
321 else if (ntv->constant > MAXTC)
322 time_constant = MAXTC;
323 else
324 time_constant = ntv->constant;
325 }
326 if (modes & MOD_TAI) {
327 if (ntv->constant > 0) /* XXX zero & negative numbers ? */
328 time_tai = ntv->constant;
329 }
330#ifdef PPS_SYNC
331 if (modes & MOD_PPSMAX) {
332 if (ntv->shift < PPS_FAVG)
333 pps_shiftmax = PPS_FAVG;
334 else if (ntv->shift > PPS_FAVGMAX)
335 pps_shiftmax = PPS_FAVGMAX;
336 else
337 pps_shiftmax = ntv->shift;
338 }
339#endif /* PPS_SYNC */
340 if (modes & MOD_NANO)
341 time_status |= STA_NANO;
342 if (modes & MOD_MICRO)
343 time_status &= ~STA_NANO;
344 if (modes & MOD_CLKB)
345 time_status |= STA_CLK;
346 if (modes & MOD_CLKA)
347 time_status &= ~STA_CLK;
348 if (modes & MOD_FREQUENCY) {
349 freq = (ntv->freq * 1000LL) >> 16;
350 if (freq > MAXFREQ)
351 L_LINT(time_freq, MAXFREQ);
352 else if (freq < -MAXFREQ)
353 L_LINT(time_freq, -MAXFREQ);
354 else {
355 /*
356 * ntv.freq is [PPM * 2^16] = [us/s * 2^16]
357 * time_freq is [ns/s * 2^32]
358 */
359 time_freq = ntv->freq * 1000LL * 65536LL;
360 }
361#ifdef PPS_SYNC
362 pps_freq = time_freq;
363#endif /* PPS_SYNC */
364 }
365 if (modes & MOD_OFFSET) {
366 if (time_status & STA_NANO)
367 hardupdate(ntv->offset);
368 else
369 hardupdate(ntv->offset * 1000);
370 }
371
372 /*
373 * Retrieve all clock variables. Note that the TAI offset is
374 * returned only by ntp_gettime();
375 */
376 if (time_status & STA_NANO)
377 ntv->offset = L_GINT(time_offset);
378 else
379 ntv->offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */
380 ntv->freq = L_GINT((time_freq / 1000LL) << 16);
381 ntv->maxerror = time_maxerror;
382 ntv->esterror = time_esterror;
383 ntv->status = time_status;
384 ntv->constant = time_constant;
385 if (time_status & STA_NANO)
386 ntv->precision = time_precision;
387 else
388 ntv->precision = time_precision / 1000;
389 ntv->tolerance = MAXFREQ * SCALE_PPM;
390#ifdef PPS_SYNC
391 ntv->shift = pps_shift;
392 ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16);
393 if (time_status & STA_NANO)
394 ntv->jitter = pps_jitter;
395 else
396 ntv->jitter = pps_jitter / 1000;
397 ntv->stabil = pps_stabil;
398 ntv->calcnt = pps_calcnt;
399 ntv->errcnt = pps_errcnt;
400 ntv->jitcnt = pps_jitcnt;
401 ntv->stbcnt = pps_stbcnt;
402#endif /* PPS_SYNC */
403 mutex_spin_exit(&timecounter_lock);
404}
405#endif /* NTP */
406
407/*
408 * second_overflow() - called after ntp_tick_adjust()
409 *
410 * This routine is ordinarily called immediately following the above
411 * routine ntp_tick_adjust(). While these two routines are normally
412 * combined, they are separated here only for the purposes of
413 * simulation.
414 */
415void
416ntp_update_second(int64_t *adjustment, time_t *newsec)
417{
418 int tickrate;
419 l_fp ftemp; /* 32/64-bit temporary */
420
421 KASSERT(mutex_owned(&timecounter_lock));
422
423#ifdef NTP
424
425 /*
426 * On rollover of the second both the nanosecond and microsecond
427 * clocks are updated and the state machine cranked as
428 * necessary. The phase adjustment to be used for the next
429 * second is calculated and the maximum error is increased by
430 * the tolerance.
431 */
432 time_maxerror += MAXFREQ / 1000;
433
434 /*
435 * Leap second processing. If in leap-insert state at
436 * the end of the day, the system clock is set back one
437 * second; if in leap-delete state, the system clock is
438 * set ahead one second. The nano_time() routine or
439 * external clock driver will insure that reported time
440 * is always monotonic.
441 */
442 switch (time_state) {
443
444 /*
445 * No warning.
446 */
447 case TIME_OK:
448 if (time_status & STA_INS)
449 time_state = TIME_INS;
450 else if (time_status & STA_DEL)
451 time_state = TIME_DEL;
452 break;
453
454 /*
455 * Insert second 23:59:60 following second
456 * 23:59:59.
457 */
458 case TIME_INS:
459 if (!(time_status & STA_INS))
460 time_state = TIME_OK;
461 else if ((*newsec) % 86400 == 0) {
462 (*newsec)--;
463 time_state = TIME_OOP;
464 time_tai++;
465 }
466 break;
467
468 /*
469 * Delete second 23:59:59.
470 */
471 case TIME_DEL:
472 if (!(time_status & STA_DEL))
473 time_state = TIME_OK;
474 else if (((*newsec) + 1) % 86400 == 0) {
475 (*newsec)++;
476 time_tai--;
477 time_state = TIME_WAIT;
478 }
479 break;
480
481 /*
482 * Insert second in progress.
483 */
484 case TIME_OOP:
485 time_state = TIME_WAIT;
486 break;
487
488 /*
489 * Wait for status bits to clear.
490 */
491 case TIME_WAIT:
492 if (!(time_status & (STA_INS | STA_DEL)))
493 time_state = TIME_OK;
494 }
495
496 /*
497 * Compute the total time adjustment for the next second
498 * in ns. The offset is reduced by a factor depending on
499 * whether the PPS signal is operating. Note that the
500 * value is in effect scaled by the clock frequency,
501 * since the adjustment is added at each tick interrupt.
502 */
503 ftemp = time_offset;
504#ifdef PPS_SYNC
505 /* XXX even if PPS signal dies we should finish adjustment ? */
506 if (time_status & STA_PPSTIME && time_status &
507 STA_PPSSIGNAL)
508 L_RSHIFT(ftemp, pps_shift);
509 else
510 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
511#else
512 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
513#endif /* PPS_SYNC */
514 time_adj = ftemp;
515 L_SUB(time_offset, ftemp);
516 L_ADD(time_adj, time_freq);
517
518#ifdef PPS_SYNC
519 if (pps_valid > 0)
520 pps_valid--;
521 else
522 time_status &= ~STA_PPSSIGNAL;
523#endif /* PPS_SYNC */
524#else /* !NTP */
525 L_CLR(time_adj);
526#endif /* !NTP */
527
528 /*
529 * Apply any correction from adjtime(2). If more than one second
530 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM)
531 * until the last second is slewed the final < 500 usecs.
532 */
533 if (time_adjtime != 0) {
534 if (time_adjtime > 1000000)
535 tickrate = 5000;
536 else if (time_adjtime < -1000000)
537 tickrate = -5000;
538 else if (time_adjtime > 500)
539 tickrate = 500;
540 else if (time_adjtime < -500)
541 tickrate = -500;
542 else
543 tickrate = time_adjtime;
544 time_adjtime -= tickrate;
545 L_LINT(ftemp, tickrate * 1000);
546 L_ADD(time_adj, ftemp);
547 }
548 *adjustment = time_adj;
549}
550
551/*
552 * ntp_init() - initialize variables and structures
553 *
554 * This routine must be called after the kernel variables hz and tick
555 * are set or changed and before the next tick interrupt. In this
556 * particular implementation, these values are assumed set elsewhere in
557 * the kernel. The design allows the clock frequency and tick interval
558 * to be changed while the system is running. So, this routine should
559 * probably be integrated with the code that does that.
560 */
561void
562ntp_init(void)
563{
564
565 /*
566 * The following variables are initialized only at startup. Only
567 * those structures not cleared by the compiler need to be
568 * initialized, and these only in the simulator. In the actual
569 * kernel, any nonzero values here will quickly evaporate.
570 */
571 L_CLR(time_adj);
572#ifdef NTP
573 L_CLR(time_offset);
574 L_CLR(time_freq);
575#ifdef PPS_SYNC
576 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;
577 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;
578 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;
579 pps_fcount = 0;
580 L_CLR(pps_freq);
581#endif /* PPS_SYNC */
582#endif
583}
584
585#ifdef NTP
586/*
587 * hardupdate() - local clock update
588 *
589 * This routine is called by ntp_adjtime() to update the local clock
590 * phase and frequency. The implementation is of an adaptive-parameter,
591 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
592 * time and frequency offset estimates for each call. If the kernel PPS
593 * discipline code is configured (PPS_SYNC), the PPS signal itself
594 * determines the new time offset, instead of the calling argument.
595 * Presumably, calls to ntp_adjtime() occur only when the caller
596 * believes the local clock is valid within some bound (+-128 ms with
597 * NTP). If the caller's time is far different than the PPS time, an
598 * argument will ensue, and it's not clear who will lose.
599 *
600 * For uncompensated quartz crystal oscillators and nominal update
601 * intervals less than 256 s, operation should be in phase-lock mode,
602 * where the loop is disciplined to phase. For update intervals greater
603 * than 1024 s, operation should be in frequency-lock mode, where the
604 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
605 * is selected by the STA_MODE status bit.
606 *
607 * Note: splclock() is in effect.
608 */
609void
610hardupdate(long offset)
611{
612 long mtemp;
613 l_fp ftemp;
614
615 KASSERT(mutex_owned(&timecounter_lock));
616
617 /*
618 * Select how the phase is to be controlled and from which
619 * source. If the PPS signal is present and enabled to
620 * discipline the time, the PPS offset is used; otherwise, the
621 * argument offset is used.
622 */
623 if (!(time_status & STA_PLL))
624 return;
625 if (!(time_status & STA_PPSTIME && time_status &
626 STA_PPSSIGNAL)) {
627 if (offset > MAXPHASE)
628 time_monitor = MAXPHASE;
629 else if (offset < -MAXPHASE)
630 time_monitor = -MAXPHASE;
631 else
632 time_monitor = offset;
633 L_LINT(time_offset, time_monitor);
634 }
635
636 /*
637 * Select how the frequency is to be controlled and in which
638 * mode (PLL or FLL). If the PPS signal is present and enabled
639 * to discipline the frequency, the PPS frequency is used;
640 * otherwise, the argument offset is used to compute it.
641 */
642 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {
643 time_reftime = time_second;
644 return;
645 }
646 if (time_status & STA_FREQHOLD || time_reftime == 0)
647 time_reftime = time_second;
648 mtemp = time_second - time_reftime;
649 L_LINT(ftemp, time_monitor);
650 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
651 L_MPY(ftemp, mtemp);
652 L_ADD(time_freq, ftemp);
653 time_status &= ~STA_MODE;
654 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
655 MAXSEC)) {
656 L_LINT(ftemp, (time_monitor << 4) / mtemp);
657 L_RSHIFT(ftemp, SHIFT_FLL + 4);
658 L_ADD(time_freq, ftemp);
659 time_status |= STA_MODE;
660 }
661 time_reftime = time_second;
662 if (L_GINT(time_freq) > MAXFREQ)
663 L_LINT(time_freq, MAXFREQ);
664 else if (L_GINT(time_freq) < -MAXFREQ)
665 L_LINT(time_freq, -MAXFREQ);
666}
667
668#ifdef PPS_SYNC
669/*
670 * hardpps() - discipline CPU clock oscillator to external PPS signal
671 *
672 * This routine is called at each PPS interrupt in order to discipline
673 * the CPU clock oscillator to the PPS signal. It measures the PPS phase
674 * and leaves it in a handy spot for the hardclock() routine. It
675 * integrates successive PPS phase differences and calculates the
676 * frequency offset. This is used in hardclock() to discipline the CPU
677 * clock oscillator so that intrinsic frequency error is cancelled out.
678 * The code requires the caller to capture the time and hardware counter
679 * value at the on-time PPS signal transition.
680 *
681 * Note that, on some Unix systems, this routine runs at an interrupt
682 * priority level higher than the timer interrupt routine hardclock().
683 * Therefore, the variables used are distinct from the hardclock()
684 * variables, except for certain exceptions: The PPS frequency pps_freq
685 * and phase pps_offset variables are determined by this routine and
686 * updated atomically. The time_tolerance variable can be considered a
687 * constant, since it is infrequently changed, and then only when the
688 * PPS signal is disabled. The watchdog counter pps_valid is updated
689 * once per second by hardclock() and is atomically cleared in this
690 * routine.
691 */
692void
693hardpps(struct timespec *tsp, /* time at PPS */
694 long nsec /* hardware counter at PPS */)
695{
696 long u_sec, u_nsec, v_nsec; /* temps */
697 l_fp ftemp;
698
699 KASSERT(mutex_owned(&timecounter_lock));
700
701 /*
702 * The signal is first processed by a range gate and frequency
703 * discriminator. The range gate rejects noise spikes outside
704 * the range +-500 us. The frequency discriminator rejects input
705 * signals with apparent frequency outside the range 1 +-500
706 * PPM. If two hits occur in the same second, we ignore the
707 * later hit; if not and a hit occurs outside the range gate,
708 * keep the later hit for later comparison, but do not process
709 * it.
710 */
711 time_status |= STA_PPSSIGNAL | STA_PPSJITTER;
712 time_status &= ~(STA_PPSWANDER | STA_PPSERROR);
713 pps_valid = PPS_VALID;
714 u_sec = tsp->tv_sec;
715 u_nsec = tsp->tv_nsec;
716 if (u_nsec >= (NANOSECOND >> 1)) {
717 u_nsec -= NANOSECOND;
718 u_sec++;
719 }
720 v_nsec = u_nsec - pps_tf[0].tv_nsec;
721 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND -
722 MAXFREQ)
723 return;
724 pps_tf[2] = pps_tf[1];
725 pps_tf[1] = pps_tf[0];
726 pps_tf[0].tv_sec = u_sec;
727 pps_tf[0].tv_nsec = u_nsec;
728
729 /*
730 * Compute the difference between the current and previous
731 * counter values. If the difference exceeds 0.5 s, assume it
732 * has wrapped around, so correct 1.0 s. If the result exceeds
733 * the tick interval, the sample point has crossed a tick
734 * boundary during the last second, so correct the tick. Very
735 * intricate.
736 */
737 u_nsec = nsec;
738 if (u_nsec > (NANOSECOND >> 1))
739 u_nsec -= NANOSECOND;
740 else if (u_nsec < -(NANOSECOND >> 1))
741 u_nsec += NANOSECOND;
742 pps_fcount += u_nsec;
743 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
744 return;
745 time_status &= ~STA_PPSJITTER;
746
747 /*
748 * A three-stage median filter is used to help denoise the PPS
749 * time. The median sample becomes the time offset estimate; the
750 * difference between the other two samples becomes the time
751 * dispersion (jitter) estimate.
752 */
753 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {
754 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {
755 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */
756 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;
757 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {
758 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */
759 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;
760 } else {
761 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */
762 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;
763 }
764 } else {
765 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {
766 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */
767 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;
768 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {
769 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */
770 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;
771 } else {
772 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */
773 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;
774 }
775 }
776
777 /*
778 * Nominal jitter is due to PPS signal noise and interrupt
779 * latency. If it exceeds the popcorn threshold, the sample is
780 * discarded. otherwise, if so enabled, the time offset is
781 * updated. We can tolerate a modest loss of data here without
782 * much degrading time accuracy.
783 */
784 if (u_nsec > (pps_jitter << PPS_POPCORN)) {
785 time_status |= STA_PPSJITTER;
786 pps_jitcnt++;
787 } else if (time_status & STA_PPSTIME) {
788 time_monitor = -v_nsec;
789 L_LINT(time_offset, time_monitor);
790 }
791 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;
792 u_sec = pps_tf[0].tv_sec - pps_lastsec;
793 if (u_sec < (1 << pps_shift))
794 return;
795
796 /*
797 * At the end of the calibration interval the difference between
798 * the first and last counter values becomes the scaled
799 * frequency. It will later be divided by the length of the
800 * interval to determine the frequency update. If the frequency
801 * exceeds a sanity threshold, or if the actual calibration
802 * interval is not equal to the expected length, the data are
803 * discarded. We can tolerate a modest loss of data here without
804 * much degrading frequency accuracy.
805 */
806 pps_calcnt++;
807 v_nsec = -pps_fcount;
808 pps_lastsec = pps_tf[0].tv_sec;
809 pps_fcount = 0;
810 u_nsec = MAXFREQ << pps_shift;
811 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 <<
812 pps_shift)) {
813 time_status |= STA_PPSERROR;
814 pps_errcnt++;
815 return;
816 }
817
818 /*
819 * Here the raw frequency offset and wander (stability) is
820 * calculated. If the wander is less than the wander threshold
821 * for four consecutive averaging intervals, the interval is
822 * doubled; if it is greater than the threshold for four
823 * consecutive intervals, the interval is halved. The scaled
824 * frequency offset is converted to frequency offset. The
825 * stability metric is calculated as the average of recent
826 * frequency changes, but is used only for performance
827 * monitoring.
828 */
829 L_LINT(ftemp, v_nsec);
830 L_RSHIFT(ftemp, pps_shift);
831 L_SUB(ftemp, pps_freq);
832 u_nsec = L_GINT(ftemp);
833 if (u_nsec > PPS_MAXWANDER) {
834 L_LINT(ftemp, PPS_MAXWANDER);
835 pps_intcnt--;
836 time_status |= STA_PPSWANDER;
837 pps_stbcnt++;
838 } else if (u_nsec < -PPS_MAXWANDER) {
839 L_LINT(ftemp, -PPS_MAXWANDER);
840 pps_intcnt--;
841 time_status |= STA_PPSWANDER;
842 pps_stbcnt++;
843 } else {
844 pps_intcnt++;
845 }
846 if (pps_intcnt >= 4) {
847 pps_intcnt = 4;
848 if (pps_shift < pps_shiftmax) {
849 pps_shift++;
850 pps_intcnt = 0;
851 }
852 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {
853 pps_intcnt = -4;
854 if (pps_shift > PPS_FAVG) {
855 pps_shift--;
856 pps_intcnt = 0;
857 }
858 }
859 if (u_nsec < 0)
860 u_nsec = -u_nsec;
861 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;
862
863 /*
864 * The PPS frequency is recalculated and clamped to the maximum
865 * MAXFREQ. If enabled, the system clock frequency is updated as
866 * well.
867 */
868 L_ADD(pps_freq, ftemp);
869 u_nsec = L_GINT(pps_freq);
870 if (u_nsec > MAXFREQ)
871 L_LINT(pps_freq, MAXFREQ);
872 else if (u_nsec < -MAXFREQ)
873 L_LINT(pps_freq, -MAXFREQ);
874 if (time_status & STA_PPSFREQ)
875 time_freq = pps_freq;
876}
877#endif /* PPS_SYNC */
878#endif /* NTP */
879
880#ifdef NTP
881int
882ntp_timestatus(void)
883{
884 int rv;
885
886 /*
887 * Status word error decode. If any of these conditions
888 * occur, an error is returned, instead of the status
889 * word. Most applications will care only about the fact
890 * the system clock may not be trusted, not about the
891 * details.
892 *
893 * Hardware or software error
894 */
895 mutex_spin_enter(&timecounter_lock);
896 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||
897
898 /*
899 * PPS signal lost when either time or frequency
900 * synchronization requested
901 */
902 (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
903 !(time_status & STA_PPSSIGNAL)) ||
904
905 /*
906 * PPS jitter exceeded when time synchronization
907 * requested
908 */
909 (time_status & STA_PPSTIME &&
910 time_status & STA_PPSJITTER) ||
911
912 /*
913 * PPS wander exceeded or calibration error when
914 * frequency synchronization requested
915 */
916 (time_status & STA_PPSFREQ &&
917 time_status & (STA_PPSWANDER | STA_PPSERROR)))
918 rv = TIME_ERROR;
919 else
920 rv = time_state;
921 mutex_spin_exit(&timecounter_lock);
922
923 return rv;
924}
925
926/*ARGSUSED*/
927/*
928 * ntp_gettime() - NTP user application interface
929 */
930int
931sys___ntp_gettime50(struct lwp *l, const struct sys___ntp_gettime50_args *uap, register_t *retval)
932{
933 /* {
934 syscallarg(struct ntptimeval *) ntvp;
935 } */
936 struct ntptimeval ntv;
937 int error = 0;
938
939 if (SCARG(uap, ntvp)) {
940 ntp_gettime(&ntv);
941
942 error = copyout((void *)&ntv, (void *)SCARG(uap, ntvp),
943 sizeof(ntv));
944 }
945 if (!error) {
946 *retval = ntp_timestatus();
947 }
948 return(error);
949}
950
951/*
952 * return information about kernel precision timekeeping
953 */
954static int
955sysctl_kern_ntptime(SYSCTLFN_ARGS)
956{
957 struct sysctlnode node;
958 struct ntptimeval ntv;
959
960 ntp_gettime(&ntv);
961
962 node = *rnode;
963 node.sysctl_data = &ntv;
964 node.sysctl_size = sizeof(ntv);
965 return (sysctl_lookup(SYSCTLFN_CALL(&node)));
966}
967
968SYSCTL_SETUP(sysctl_kern_ntptime_setup, "sysctl kern.ntptime node setup")
969{
970
971 sysctl_createv(clog, 0, NULL, NULL,
972 CTLFLAG_PERMANENT,
973 CTLTYPE_STRUCT, "ntptime",
974 SYSCTL_DESCR("Kernel clock values for NTP"),
975 sysctl_kern_ntptime, 0, NULL,
976 sizeof(struct ntptimeval),
977 CTL_KERN, KERN_NTPTIME, CTL_EOL);
978}
979#endif /* !NTP */
980