Annotation of src/sys/kern/kern_ntptime.c, Revision 1.64
1.64 ! riastrad 1: /* $NetBSD: kern_ntptime.c,v 1.63 2022/03/13 12:57:33 riastradh Exp $ */
1.48 ad 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: */
1.33 kardel 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: **********************************************************************/
1.1 jonathan 47:
1.33 kardel 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 $"); */
1.64 ! riastrad 63: __KERNEL_RCSID(0, "$NetBSD: kern_ntptime.c,v 1.63 2022/03/13 12:57:33 riastradh Exp $");
1.33 kardel 64:
1.54 pooka 65: #ifdef _KERNEL_OPT
1.33 kardel 66: #include "opt_ntp.h"
1.54 pooka 67: #endif
1.33 kardel 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>
1.48 ad 80: #include <sys/cpu.h>
1.33 kardel 81:
1.48 ad 82: #include <compat/sys/timex.h>
1.33 kardel 83:
84: /*
85: * Single-precision macros for 64-bit machines
86: */
87: typedef 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)
1.57 joerg 102: #define L_LINT(v, a) ((v) = (int64_t)((uint64_t)(a) << 32))
1.33 kardel 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:
177: static int time_state = TIME_OK; /* clock state */
178: static int time_status = STA_UNSYNC; /* clock status bits */
179: static long time_tai; /* TAI offset (s) */
180: static long time_monitor; /* last time offset scaled (ns) */
181: static long time_constant; /* poll interval (shift) (s) */
182: static long time_precision = 1; /* clock precision (ns) */
183: static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */
184: static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */
1.53 tsutsui 185: static time_t time_reftime; /* time at last adjustment (s) */
1.33 kardel 186: static l_fp time_offset; /* time offset (ns) */
187: static l_fp time_freq; /* frequency offset (ns/s) */
188: #endif /* NTP */
189:
190: static l_fp time_adj; /* tick adjust (ns/s) */
191: int64_t time_adjtime; /* correction from adjtime(2) (usec) */
192:
193: #ifdef NTP
194: #ifdef PPS_SYNC
195: /*
196: * The following variables are used when a pulse-per-second (PPS) signal
197: * is available and connected via a modem control lead. They establish
198: * the engineering parameters of the clock discipline loop when
199: * controlled by the PPS signal.
200: */
201: #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */
202: #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */
203: #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */
204: #define PPS_PAVG 4 /* phase avg interval (s) (shift) */
205: #define PPS_VALID 120 /* PPS signal watchdog max (s) */
206: #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */
207: #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */
208:
209: static struct timespec pps_tf[3]; /* phase median filter */
210: static l_fp pps_freq; /* scaled frequency offset (ns/s) */
211: static long pps_fcount; /* frequency accumulator */
212: static long pps_jitter; /* nominal jitter (ns) */
213: static long pps_stabil; /* nominal stability (scaled ns/s) */
214: static long pps_lastsec; /* time at last calibration (s) */
215: static int pps_valid; /* signal watchdog counter */
216: static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */
217: static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */
218: static int pps_intcnt; /* wander counter */
219:
220: /*
221: * PPS signal quality monitors
222: */
223: static long pps_calcnt; /* calibration intervals */
224: static long pps_jitcnt; /* jitter limit exceeded */
225: static long pps_stbcnt; /* stability limit exceeded */
226: static long pps_errcnt; /* calibration errors */
227: #endif /* PPS_SYNC */
228: /*
229: * End of phase/frequency-lock loop (PLL/FLL) definitions
230: */
231:
232: static void hardupdate(long offset);
233:
234: /*
235: * ntp_gettime() - NTP user application interface
236: */
237: void
1.45 dsl 238: ntp_gettime(struct ntptimeval *ntv)
1.33 kardel 239: {
1.60 christos 240: memset(ntv, 0, sizeof(*ntv));
1.48 ad 241:
242: mutex_spin_enter(&timecounter_lock);
1.33 kardel 243: nanotime(&ntv->time);
244: ntv->maxerror = time_maxerror;
245: ntv->esterror = time_esterror;
246: ntv->tai = time_tai;
247: ntv->time_state = time_state;
1.48 ad 248: mutex_spin_exit(&timecounter_lock);
1.33 kardel 249: }
250:
251: /* ARGSUSED */
252: /*
253: * ntp_adjtime() - NTP daemon application interface
254: */
255: int
1.45 dsl 256: sys_ntp_adjtime(struct lwp *l, const struct sys_ntp_adjtime_args *uap, register_t *retval)
1.33 kardel 257: {
1.45 dsl 258: /* {
1.33 kardel 259: syscallarg(struct timex *) tp;
1.45 dsl 260: } */
1.33 kardel 261: struct timex ntv;
1.56 maxv 262: int error;
1.33 kardel 263:
1.43 christos 264: error = copyin((void *)SCARG(uap, tp), (void *)&ntv, sizeof(ntv));
1.35 ad 265: if (error != 0)
1.33 kardel 266: return (error);
267:
1.37 elad 268: if (ntv.modes != 0 && (error = kauth_authorize_system(l->l_cred,
269: KAUTH_SYSTEM_TIME, KAUTH_REQ_SYSTEM_TIME_NTPADJTIME, NULL,
1.36 elad 270: NULL, NULL)) != 0)
1.33 kardel 271: return (error);
272:
273: ntp_adjtime1(&ntv);
274:
1.43 christos 275: error = copyout((void *)&ntv, (void *)SCARG(uap, tp), sizeof(ntv));
1.35 ad 276: if (!error)
1.33 kardel 277: *retval = ntp_timestatus();
1.35 ad 278:
1.33 kardel 279: return error;
280: }
281:
282: void
1.45 dsl 283: ntp_adjtime1(struct timex *ntv)
1.33 kardel 284: {
285: long freq;
286: int modes;
287:
288: /*
289: * Update selected clock variables - only the superuser can
290: * change anything. Note that there is no error checking here on
291: * the assumption the superuser should know what it is doing.
292: * Note that either the time constant or TAI offset are loaded
293: * from the ntv.constant member, depending on the mode bits. If
294: * the STA_PLL bit in the status word is cleared, the state and
295: * status words are reset to the initial values at boot.
296: */
1.48 ad 297: mutex_spin_enter(&timecounter_lock);
1.33 kardel 298: modes = ntv->modes;
299: if (modes != 0)
300: /* We need to save the system time during shutdown */
301: time_adjusted |= 2;
302: if (modes & MOD_MAXERROR)
303: time_maxerror = ntv->maxerror;
304: if (modes & MOD_ESTERROR)
305: time_esterror = ntv->esterror;
306: if (modes & MOD_STATUS) {
307: if (time_status & STA_PLL && !(ntv->status & STA_PLL)) {
308: time_state = TIME_OK;
309: time_status = STA_UNSYNC;
310: #ifdef PPS_SYNC
311: pps_shift = PPS_FAVG;
312: #endif /* PPS_SYNC */
313: }
314: time_status &= STA_RONLY;
315: time_status |= ntv->status & ~STA_RONLY;
316: }
317: if (modes & MOD_TIMECONST) {
318: if (ntv->constant < 0)
319: time_constant = 0;
320: else if (ntv->constant > MAXTC)
321: time_constant = MAXTC;
322: else
323: time_constant = ntv->constant;
324: }
325: if (modes & MOD_TAI) {
326: if (ntv->constant > 0) /* XXX zero & negative numbers ? */
327: time_tai = ntv->constant;
328: }
329: #ifdef PPS_SYNC
330: if (modes & MOD_PPSMAX) {
331: if (ntv->shift < PPS_FAVG)
332: pps_shiftmax = PPS_FAVG;
333: else if (ntv->shift > PPS_FAVGMAX)
334: pps_shiftmax = PPS_FAVGMAX;
335: else
336: pps_shiftmax = ntv->shift;
337: }
338: #endif /* PPS_SYNC */
339: if (modes & MOD_NANO)
340: time_status |= STA_NANO;
341: if (modes & MOD_MICRO)
342: time_status &= ~STA_NANO;
343: if (modes & MOD_CLKB)
344: time_status |= STA_CLK;
345: if (modes & MOD_CLKA)
346: time_status &= ~STA_CLK;
347: if (modes & MOD_FREQUENCY) {
1.61 riastrad 348: freq = MIN(INT32_MAX, MAX(INT32_MIN, ntv->freq));
349: freq = (freq * (int64_t)1000) >> 16;
1.33 kardel 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) {
1.62 riastrad 366: if (time_status & STA_NANO) {
1.33 kardel 367: hardupdate(ntv->offset);
1.62 riastrad 368: } else {
369: long offset = ntv->offset;
370: offset = MIN(offset, MAXPHASE/1000);
371: offset = MAX(offset, -MAXPHASE/1000);
372: hardupdate(offset * 1000);
373: }
1.33 kardel 374: }
375:
376: /*
377: * Retrieve all clock variables. Note that the TAI offset is
378: * returned only by ntp_gettime();
379: */
380: if (time_status & STA_NANO)
381: ntv->offset = L_GINT(time_offset);
382: else
383: ntv->offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */
1.63 riastrad 384: if (time_freq < 0)
385: ntv->freq = L_GINT(-((-time_freq / 1000LL) << 16));
386: else
387: ntv->freq = L_GINT((time_freq / 1000LL) << 16);
1.33 kardel 388: ntv->maxerror = time_maxerror;
389: ntv->esterror = time_esterror;
390: ntv->status = time_status;
391: ntv->constant = time_constant;
392: if (time_status & STA_NANO)
393: ntv->precision = time_precision;
394: else
395: ntv->precision = time_precision / 1000;
396: ntv->tolerance = MAXFREQ * SCALE_PPM;
397: #ifdef PPS_SYNC
398: ntv->shift = pps_shift;
399: ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16);
400: if (time_status & STA_NANO)
401: ntv->jitter = pps_jitter;
402: else
403: ntv->jitter = pps_jitter / 1000;
404: ntv->stabil = pps_stabil;
405: ntv->calcnt = pps_calcnt;
406: ntv->errcnt = pps_errcnt;
407: ntv->jitcnt = pps_jitcnt;
408: ntv->stbcnt = pps_stbcnt;
409: #endif /* PPS_SYNC */
1.48 ad 410: mutex_spin_exit(&timecounter_lock);
1.33 kardel 411: }
412: #endif /* NTP */
413:
414: /*
415: * second_overflow() - called after ntp_tick_adjust()
416: *
417: * This routine is ordinarily called immediately following the above
418: * routine ntp_tick_adjust(). While these two routines are normally
419: * combined, they are separated here only for the purposes of
420: * simulation.
421: */
422: void
423: ntp_update_second(int64_t *adjustment, time_t *newsec)
424: {
425: int tickrate;
426: l_fp ftemp; /* 32/64-bit temporary */
427:
1.59 riastrad 428: KASSERT(mutex_owned(&timecounter_lock));
1.48 ad 429:
1.33 kardel 430: #ifdef NTP
431:
432: /*
433: * On rollover of the second both the nanosecond and microsecond
434: * clocks are updated and the state machine cranked as
435: * necessary. The phase adjustment to be used for the next
436: * second is calculated and the maximum error is increased by
437: * the tolerance.
438: */
439: time_maxerror += MAXFREQ / 1000;
440:
441: /*
442: * Leap second processing. If in leap-insert state at
443: * the end of the day, the system clock is set back one
444: * second; if in leap-delete state, the system clock is
445: * set ahead one second. The nano_time() routine or
446: * external clock driver will insure that reported time
447: * is always monotonic.
448: */
449: switch (time_state) {
450:
451: /*
452: * No warning.
453: */
454: case TIME_OK:
455: if (time_status & STA_INS)
456: time_state = TIME_INS;
457: else if (time_status & STA_DEL)
458: time_state = TIME_DEL;
459: break;
460:
461: /*
462: * Insert second 23:59:60 following second
463: * 23:59:59.
464: */
465: case TIME_INS:
466: if (!(time_status & STA_INS))
467: time_state = TIME_OK;
468: else if ((*newsec) % 86400 == 0) {
469: (*newsec)--;
470: time_state = TIME_OOP;
471: time_tai++;
472: }
473: break;
474:
475: /*
476: * Delete second 23:59:59.
477: */
478: case TIME_DEL:
479: if (!(time_status & STA_DEL))
480: time_state = TIME_OK;
481: else if (((*newsec) + 1) % 86400 == 0) {
482: (*newsec)++;
483: time_tai--;
484: time_state = TIME_WAIT;
485: }
486: break;
487:
488: /*
489: * Insert second in progress.
490: */
491: case TIME_OOP:
492: time_state = TIME_WAIT;
493: break;
494:
495: /*
496: * Wait for status bits to clear.
497: */
498: case TIME_WAIT:
499: if (!(time_status & (STA_INS | STA_DEL)))
500: time_state = TIME_OK;
501: }
502:
503: /*
504: * Compute the total time adjustment for the next second
505: * in ns. The offset is reduced by a factor depending on
506: * whether the PPS signal is operating. Note that the
507: * value is in effect scaled by the clock frequency,
508: * since the adjustment is added at each tick interrupt.
509: */
510: ftemp = time_offset;
511: #ifdef PPS_SYNC
512: /* XXX even if PPS signal dies we should finish adjustment ? */
513: if (time_status & STA_PPSTIME && time_status &
514: STA_PPSSIGNAL)
515: L_RSHIFT(ftemp, pps_shift);
516: else
517: L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
518: #else
519: L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
520: #endif /* PPS_SYNC */
521: time_adj = ftemp;
522: L_SUB(time_offset, ftemp);
523: L_ADD(time_adj, time_freq);
524:
525: #ifdef PPS_SYNC
526: if (pps_valid > 0)
527: pps_valid--;
528: else
529: time_status &= ~STA_PPSSIGNAL;
530: #endif /* PPS_SYNC */
1.34 kardel 531: #else /* !NTP */
532: L_CLR(time_adj);
533: #endif /* !NTP */
1.33 kardel 534:
535: /*
536: * Apply any correction from adjtime(2). If more than one second
537: * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM)
538: * until the last second is slewed the final < 500 usecs.
539: */
540: if (time_adjtime != 0) {
541: if (time_adjtime > 1000000)
542: tickrate = 5000;
543: else if (time_adjtime < -1000000)
544: tickrate = -5000;
545: else if (time_adjtime > 500)
546: tickrate = 500;
547: else if (time_adjtime < -500)
548: tickrate = -500;
549: else
550: tickrate = time_adjtime;
551: time_adjtime -= tickrate;
552: L_LINT(ftemp, tickrate * 1000);
553: L_ADD(time_adj, ftemp);
554: }
555: *adjustment = time_adj;
556: }
557:
558: /*
559: * ntp_init() - initialize variables and structures
560: *
561: * This routine must be called after the kernel variables hz and tick
562: * are set or changed and before the next tick interrupt. In this
563: * particular implementation, these values are assumed set elsewhere in
564: * the kernel. The design allows the clock frequency and tick interval
565: * to be changed while the system is running. So, this routine should
566: * probably be integrated with the code that does that.
567: */
568: void
569: ntp_init(void)
570: {
571:
572: /*
573: * The following variables are initialized only at startup. Only
574: * those structures not cleared by the compiler need to be
575: * initialized, and these only in the simulator. In the actual
576: * kernel, any nonzero values here will quickly evaporate.
577: */
578: L_CLR(time_adj);
579: #ifdef NTP
580: L_CLR(time_offset);
581: L_CLR(time_freq);
582: #ifdef PPS_SYNC
583: pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;
584: pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;
585: pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;
586: pps_fcount = 0;
587: L_CLR(pps_freq);
588: #endif /* PPS_SYNC */
589: #endif
590: }
591:
592: #ifdef NTP
593: /*
594: * hardupdate() - local clock update
595: *
596: * This routine is called by ntp_adjtime() to update the local clock
597: * phase and frequency. The implementation is of an adaptive-parameter,
598: * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
599: * time and frequency offset estimates for each call. If the kernel PPS
600: * discipline code is configured (PPS_SYNC), the PPS signal itself
601: * determines the new time offset, instead of the calling argument.
602: * Presumably, calls to ntp_adjtime() occur only when the caller
603: * believes the local clock is valid within some bound (+-128 ms with
604: * NTP). If the caller's time is far different than the PPS time, an
605: * argument will ensue, and it's not clear who will lose.
606: *
607: * For uncompensated quartz crystal oscillators and nominal update
608: * intervals less than 256 s, operation should be in phase-lock mode,
609: * where the loop is disciplined to phase. For update intervals greater
610: * than 1024 s, operation should be in frequency-lock mode, where the
611: * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
612: * is selected by the STA_MODE status bit.
613: *
614: * Note: splclock() is in effect.
615: */
616: void
617: hardupdate(long offset)
618: {
619: long mtemp;
620: l_fp ftemp;
621:
1.48 ad 622: KASSERT(mutex_owned(&timecounter_lock));
623:
1.33 kardel 624: /*
625: * Select how the phase is to be controlled and from which
626: * source. If the PPS signal is present and enabled to
627: * discipline the time, the PPS offset is used; otherwise, the
628: * argument offset is used.
629: */
630: if (!(time_status & STA_PLL))
631: return;
632: if (!(time_status & STA_PPSTIME && time_status &
633: STA_PPSSIGNAL)) {
634: if (offset > MAXPHASE)
635: time_monitor = MAXPHASE;
636: else if (offset < -MAXPHASE)
637: time_monitor = -MAXPHASE;
638: else
639: time_monitor = offset;
640: L_LINT(time_offset, time_monitor);
641: }
642:
643: /*
644: * Select how the frequency is to be controlled and in which
645: * mode (PLL or FLL). If the PPS signal is present and enabled
646: * to discipline the frequency, the PPS frequency is used;
647: * otherwise, the argument offset is used to compute it.
648: */
649: if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {
650: time_reftime = time_second;
651: return;
652: }
653: if (time_status & STA_FREQHOLD || time_reftime == 0)
654: time_reftime = time_second;
655: mtemp = time_second - time_reftime;
656: L_LINT(ftemp, time_monitor);
657: L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
658: L_MPY(ftemp, mtemp);
659: L_ADD(time_freq, ftemp);
660: time_status &= ~STA_MODE;
661: if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
662: MAXSEC)) {
663: L_LINT(ftemp, (time_monitor << 4) / mtemp);
664: L_RSHIFT(ftemp, SHIFT_FLL + 4);
665: L_ADD(time_freq, ftemp);
666: time_status |= STA_MODE;
667: }
668: time_reftime = time_second;
669: if (L_GINT(time_freq) > MAXFREQ)
670: L_LINT(time_freq, MAXFREQ);
671: else if (L_GINT(time_freq) < -MAXFREQ)
672: L_LINT(time_freq, -MAXFREQ);
673: }
674:
675: #ifdef PPS_SYNC
676: /*
677: * hardpps() - discipline CPU clock oscillator to external PPS signal
678: *
679: * This routine is called at each PPS interrupt in order to discipline
680: * the CPU clock oscillator to the PPS signal. It measures the PPS phase
681: * and leaves it in a handy spot for the hardclock() routine. It
682: * integrates successive PPS phase differences and calculates the
683: * frequency offset. This is used in hardclock() to discipline the CPU
684: * clock oscillator so that intrinsic frequency error is cancelled out.
685: * The code requires the caller to capture the time and hardware counter
686: * value at the on-time PPS signal transition.
687: *
688: * Note that, on some Unix systems, this routine runs at an interrupt
689: * priority level higher than the timer interrupt routine hardclock().
690: * Therefore, the variables used are distinct from the hardclock()
691: * variables, except for certain exceptions: The PPS frequency pps_freq
692: * and phase pps_offset variables are determined by this routine and
693: * updated atomically. The time_tolerance variable can be considered a
694: * constant, since it is infrequently changed, and then only when the
695: * PPS signal is disabled. The watchdog counter pps_valid is updated
696: * once per second by hardclock() and is atomically cleared in this
697: * routine.
698: */
699: void
700: hardpps(struct timespec *tsp, /* time at PPS */
701: long nsec /* hardware counter at PPS */)
702: {
703: long u_sec, u_nsec, v_nsec; /* temps */
704: l_fp ftemp;
705:
1.48 ad 706: KASSERT(mutex_owned(&timecounter_lock));
707:
1.33 kardel 708: /*
709: * The signal is first processed by a range gate and frequency
710: * discriminator. The range gate rejects noise spikes outside
711: * the range +-500 us. The frequency discriminator rejects input
712: * signals with apparent frequency outside the range 1 +-500
713: * PPM. If two hits occur in the same second, we ignore the
714: * later hit; if not and a hit occurs outside the range gate,
715: * keep the later hit for later comparison, but do not process
716: * it.
717: */
718: time_status |= STA_PPSSIGNAL | STA_PPSJITTER;
719: time_status &= ~(STA_PPSWANDER | STA_PPSERROR);
720: pps_valid = PPS_VALID;
721: u_sec = tsp->tv_sec;
722: u_nsec = tsp->tv_nsec;
723: if (u_nsec >= (NANOSECOND >> 1)) {
724: u_nsec -= NANOSECOND;
725: u_sec++;
726: }
727: v_nsec = u_nsec - pps_tf[0].tv_nsec;
728: if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND -
729: MAXFREQ)
730: return;
731: pps_tf[2] = pps_tf[1];
732: pps_tf[1] = pps_tf[0];
733: pps_tf[0].tv_sec = u_sec;
734: pps_tf[0].tv_nsec = u_nsec;
735:
736: /*
737: * Compute the difference between the current and previous
738: * counter values. If the difference exceeds 0.5 s, assume it
739: * has wrapped around, so correct 1.0 s. If the result exceeds
740: * the tick interval, the sample point has crossed a tick
741: * boundary during the last second, so correct the tick. Very
742: * intricate.
743: */
744: u_nsec = nsec;
745: if (u_nsec > (NANOSECOND >> 1))
746: u_nsec -= NANOSECOND;
747: else if (u_nsec < -(NANOSECOND >> 1))
748: u_nsec += NANOSECOND;
749: pps_fcount += u_nsec;
750: if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
751: return;
752: time_status &= ~STA_PPSJITTER;
753:
754: /*
755: * A three-stage median filter is used to help denoise the PPS
756: * time. The median sample becomes the time offset estimate; the
757: * difference between the other two samples becomes the time
758: * dispersion (jitter) estimate.
759: */
760: if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {
761: if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {
762: v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */
763: u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;
764: } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {
765: v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */
766: u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;
767: } else {
768: v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */
769: u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;
770: }
771: } else {
772: if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {
773: v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */
774: u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;
775: } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {
776: v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */
777: u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;
778: } else {
779: v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */
780: u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;
781: }
782: }
783:
784: /*
785: * Nominal jitter is due to PPS signal noise and interrupt
786: * latency. If it exceeds the popcorn threshold, the sample is
787: * discarded. otherwise, if so enabled, the time offset is
788: * updated. We can tolerate a modest loss of data here without
789: * much degrading time accuracy.
790: */
791: if (u_nsec > (pps_jitter << PPS_POPCORN)) {
792: time_status |= STA_PPSJITTER;
793: pps_jitcnt++;
794: } else if (time_status & STA_PPSTIME) {
795: time_monitor = -v_nsec;
796: L_LINT(time_offset, time_monitor);
797: }
798: pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;
799: u_sec = pps_tf[0].tv_sec - pps_lastsec;
800: if (u_sec < (1 << pps_shift))
801: return;
802:
803: /*
804: * At the end of the calibration interval the difference between
805: * the first and last counter values becomes the scaled
806: * frequency. It will later be divided by the length of the
807: * interval to determine the frequency update. If the frequency
808: * exceeds a sanity threshold, or if the actual calibration
809: * interval is not equal to the expected length, the data are
810: * discarded. We can tolerate a modest loss of data here without
811: * much degrading frequency accuracy.
812: */
813: pps_calcnt++;
814: v_nsec = -pps_fcount;
815: pps_lastsec = pps_tf[0].tv_sec;
816: pps_fcount = 0;
817: u_nsec = MAXFREQ << pps_shift;
818: if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 <<
819: pps_shift)) {
820: time_status |= STA_PPSERROR;
821: pps_errcnt++;
822: return;
823: }
824:
825: /*
826: * Here the raw frequency offset and wander (stability) is
827: * calculated. If the wander is less than the wander threshold
828: * for four consecutive averaging intervals, the interval is
829: * doubled; if it is greater than the threshold for four
830: * consecutive intervals, the interval is halved. The scaled
831: * frequency offset is converted to frequency offset. The
832: * stability metric is calculated as the average of recent
833: * frequency changes, but is used only for performance
834: * monitoring.
835: */
836: L_LINT(ftemp, v_nsec);
837: L_RSHIFT(ftemp, pps_shift);
838: L_SUB(ftemp, pps_freq);
839: u_nsec = L_GINT(ftemp);
840: if (u_nsec > PPS_MAXWANDER) {
841: L_LINT(ftemp, PPS_MAXWANDER);
842: pps_intcnt--;
843: time_status |= STA_PPSWANDER;
844: pps_stbcnt++;
845: } else if (u_nsec < -PPS_MAXWANDER) {
846: L_LINT(ftemp, -PPS_MAXWANDER);
847: pps_intcnt--;
848: time_status |= STA_PPSWANDER;
849: pps_stbcnt++;
850: } else {
851: pps_intcnt++;
852: }
853: if (pps_intcnt >= 4) {
854: pps_intcnt = 4;
855: if (pps_shift < pps_shiftmax) {
856: pps_shift++;
857: pps_intcnt = 0;
858: }
859: } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {
860: pps_intcnt = -4;
861: if (pps_shift > PPS_FAVG) {
862: pps_shift--;
863: pps_intcnt = 0;
864: }
865: }
866: if (u_nsec < 0)
867: u_nsec = -u_nsec;
868: pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;
869:
870: /*
871: * The PPS frequency is recalculated and clamped to the maximum
872: * MAXFREQ. If enabled, the system clock frequency is updated as
873: * well.
874: */
875: L_ADD(pps_freq, ftemp);
876: u_nsec = L_GINT(pps_freq);
877: if (u_nsec > MAXFREQ)
878: L_LINT(pps_freq, MAXFREQ);
879: else if (u_nsec < -MAXFREQ)
880: L_LINT(pps_freq, -MAXFREQ);
881: if (time_status & STA_PPSFREQ)
882: time_freq = pps_freq;
883: }
884: #endif /* PPS_SYNC */
885: #endif /* NTP */
886:
887: #ifdef NTP
888: int
1.47 matt 889: ntp_timestatus(void)
1.33 kardel 890: {
1.48 ad 891: int rv;
892:
1.33 kardel 893: /*
894: * Status word error decode. If any of these conditions
895: * occur, an error is returned, instead of the status
896: * word. Most applications will care only about the fact
897: * the system clock may not be trusted, not about the
898: * details.
899: *
900: * Hardware or software error
901: */
1.48 ad 902: mutex_spin_enter(&timecounter_lock);
1.33 kardel 903: if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||
904:
905: /*
906: * PPS signal lost when either time or frequency
907: * synchronization requested
908: */
909: (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
910: !(time_status & STA_PPSSIGNAL)) ||
911:
912: /*
913: * PPS jitter exceeded when time synchronization
914: * requested
915: */
916: (time_status & STA_PPSTIME &&
917: time_status & STA_PPSJITTER) ||
918:
919: /*
920: * PPS wander exceeded or calibration error when
921: * frequency synchronization requested
922: */
923: (time_status & STA_PPSFREQ &&
924: time_status & (STA_PPSWANDER | STA_PPSERROR)))
1.48 ad 925: rv = TIME_ERROR;
1.33 kardel 926: else
1.48 ad 927: rv = time_state;
928: mutex_spin_exit(&timecounter_lock);
929:
930: return rv;
1.33 kardel 931: }
1.1 jonathan 932:
1.33 kardel 933: /*ARGSUSED*/
934: /*
935: * ntp_gettime() - NTP user application interface
936: */
937: int
1.51 christos 938: sys___ntp_gettime50(struct lwp *l, const struct sys___ntp_gettime50_args *uap, register_t *retval)
1.33 kardel 939: {
1.45 dsl 940: /* {
1.33 kardel 941: syscallarg(struct ntptimeval *) ntvp;
1.45 dsl 942: } */
1.33 kardel 943: struct ntptimeval ntv;
944: int error = 0;
945:
946: if (SCARG(uap, ntvp)) {
947: ntp_gettime(&ntv);
948:
1.43 christos 949: error = copyout((void *)&ntv, (void *)SCARG(uap, ntvp),
1.33 kardel 950: sizeof(ntv));
951: }
1.1 jonathan 952: if (!error) {
1.33 kardel 953: *retval = ntp_timestatus();
954: }
955: return(error);
956: }
1.1 jonathan 957:
958: /*
959: * return information about kernel precision timekeeping
960: */
1.25 atatat 961: static int
962: sysctl_kern_ntptime(SYSCTLFN_ARGS)
1.1 jonathan 963: {
1.25 atatat 964: struct sysctlnode node;
1.1 jonathan 965: struct ntptimeval ntv;
966:
1.31 drochner 967: ntp_gettime(&ntv);
1.25 atatat 968:
969: node = *rnode;
970: node.sysctl_data = &ntv;
971: node.sysctl_size = sizeof(ntv);
972: return (sysctl_lookup(SYSCTLFN_CALL(&node)));
973: }
974:
975: SYSCTL_SETUP(sysctl_kern_ntptime_setup, "sysctl kern.ntptime node setup")
976: {
977:
1.26 atatat 978: sysctl_createv(clog, 0, NULL, NULL,
979: CTLFLAG_PERMANENT,
1.27 atatat 980: CTLTYPE_STRUCT, "ntptime",
981: SYSCTL_DESCR("Kernel clock values for NTP"),
1.25 atatat 982: sysctl_kern_ntptime, 0, NULL,
983: sizeof(struct ntptimeval),
984: CTL_KERN, KERN_NTPTIME, CTL_EOL);
1.1 jonathan 985: }
1.13 bjh21 986: #endif /* !NTP */
CVSweb <webmaster@jp.NetBSD.org>
![[BACK]](/icons/back.gif){kind=icon}
Return to kern_ntptime.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [cvs.NetBSD.org] / src / sys / kern