1 /*-
2 ***********************************************************************
3 * *
4 * Copyright (c) David L. Mills 1993-2001 *
5 * *
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 *
16 * warranty. *
17 * *
18 **********************************************************************/
19
20 /*
21 * Adapted from the original sources for FreeBSD and timecounters by:
22 * Poul-Henning Kamp <phk@FreeBSD.org>.
23 *
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
26 * in this file.
27 *
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.
31 */
32
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD: releng/11.0/sys/kern/kern_ntptime.c 302252 2016-06-28 16:43:23Z kib $");
35
36 #include "opt_ntp.h"
37
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>
43 #include <sys/priv.h>
44 #include <sys/proc.h>
45 #include <sys/lock.h>
46 #include <sys/mutex.h>
47 #include <sys/time.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>
53
54 #ifdef PPS_SYNC
55 FEATURE(pps_sync, "Support usage of external PPS signal by kernel PLL");
56 #endif
57
58 /*
59 * Single-precision macros for 64-bit machines
60 */
61 typedef int64_t l_fp;
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) \
67 do { \
68 if ((v) < 0) \
69 (v) = -(-(v) >> (n)); \
70 else \
71 (v) = (v) >> (n); \
72 } while (0)
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)
78
79 /*
80 * Generic NTP kernel interface
81 *
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
90 * system clock.
91 *
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.
103 *
104 * Note that all routines must run at priority splclock or higher.
105 */
106 /*
107 * Phase/frequency-lock loop (PLL/FLL) definitions
108 *
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
115 * used.
116 *
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.
121 *
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 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
125 * |s s s| ns |
126 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
127 * | fraction |
128 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
129 *
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.
134 *
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 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
140 * | fraction |
141 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
142 */
143 /*
144 * The following variables establish the state of the PLL/FLL and the
145 * residual time and frequency offset of the local clock.
146 */
147 #define SHIFT_PLL 4 /* PLL loop gain (shift) */
148 #define SHIFT_FLL 2 /* FLL loop gain (shift) */
149
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) */
162
163 static int64_t time_adjtime; /* correction from adjtime(2) (usec) */
164
165 static struct mtx ntpadj_lock;
166 MTX_SYSINIT(ntpadj, &ntpadj_lock, "ntpadj",
167 #ifdef PPS_SYNC
168 MTX_SPIN
169 #else
170 MTX_DEF
171 #endif
172 );
173
174 /*
175 * When PPS_SYNC is defined, hardpps() function is provided which can
176 * be legitimately called from interrupt filters. Due to this, use
177 * spinlock for ntptime state protection, otherwise sleepable mutex is
178 * adequate.
179 */
180 #ifdef PPS_SYNC
181 #define NTPADJ_LOCK() mtx_lock_spin(&ntpadj_lock)
182 #define NTPADJ_UNLOCK() mtx_unlock_spin(&ntpadj_lock)
183 #else
184 #define NTPADJ_LOCK() mtx_lock(&ntpadj_lock)
185 #define NTPADJ_UNLOCK() mtx_unlock(&ntpadj_lock)
186 #endif
187 #define NTPADJ_ASSERT_LOCKED() mtx_assert(&ntpadj_lock, MA_OWNED)
188
189 #ifdef PPS_SYNC
190 /*
191 * The following variables are used when a pulse-per-second (PPS) signal
192 * is available and connected via a modem control lead. They establish
193 * the engineering parameters of the clock discipline loop when
194 * controlled by the PPS signal.
195 */
196 #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */
197 #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */
198 #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */
199 #define PPS_PAVG 4 /* phase avg interval (s) (shift) */
200 #define PPS_VALID 120 /* PPS signal watchdog max (s) */
201 #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */
202 #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */
203
204 static struct timespec pps_tf[3]; /* phase median filter */
205 static l_fp pps_freq; /* scaled frequency offset (ns/s) */
206 static long pps_fcount; /* frequency accumulator */
207 static long pps_jitter; /* nominal jitter (ns) */
208 static long pps_stabil; /* nominal stability (scaled ns/s) */
209 static long pps_lastsec; /* time at last calibration (s) */
210 static int pps_valid; /* signal watchdog counter */
211 static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */
212 static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */
213 static int pps_intcnt; /* wander counter */
214
215 /*
216 * PPS signal quality monitors
217 */
218 static long pps_calcnt; /* calibration intervals */
219 static long pps_jitcnt; /* jitter limit exceeded */
220 static long pps_stbcnt; /* stability limit exceeded */
221 static long pps_errcnt; /* calibration errors */
222 #endif /* PPS_SYNC */
223 /*
224 * End of phase/frequency-lock loop (PLL/FLL) definitions
225 */
226
227 static void ntp_init(void);
228 static void hardupdate(long offset);
229 static void ntp_gettime1(struct ntptimeval *ntvp);
230 static bool ntp_is_time_error(int tsl);
231
232 static bool
233 ntp_is_time_error(int tsl)
234 {
235
236 /*
237 * Status word error decode. If any of these conditions occur,
238 * an error is returned, instead of the status word. Most
239 * applications will care only about the fact the system clock
240 * may not be trusted, not about the details.
241 *
242 * Hardware or software error
243 */
244 if ((tsl & (STA_UNSYNC | STA_CLOCKERR)) ||
245
246 /*
247 * PPS signal lost when either time or frequency synchronization
248 * requested
249 */
250 (tsl & (STA_PPSFREQ | STA_PPSTIME) &&
251 !(tsl & STA_PPSSIGNAL)) ||
252
253 /*
254 * PPS jitter exceeded when time synchronization requested
255 */
256 (tsl & STA_PPSTIME && tsl & STA_PPSJITTER) ||
257
258 /*
259 * PPS wander exceeded or calibration error when frequency
260 * synchronization requested
261 */
262 (tsl & STA_PPSFREQ &&
263 tsl & (STA_PPSWANDER | STA_PPSERROR)))
264 return (true);
265
266 return (false);
267 }
268
269 static void
270 ntp_gettime1(struct ntptimeval *ntvp)
271 {
272 struct timespec atv; /* nanosecond time */
273
274 NTPADJ_ASSERT_LOCKED();
275
276 nanotime(&atv);
277 ntvp->time.tv_sec = atv.tv_sec;
278 ntvp->time.tv_nsec = atv.tv_nsec;
279 ntvp->maxerror = time_maxerror;
280 ntvp->esterror = time_esterror;
281 ntvp->tai = time_tai;
282 ntvp->time_state = time_state;
283
284 if (ntp_is_time_error(time_status))
285 ntvp->time_state = TIME_ERROR;
286 }
287
288 /*
289 * ntp_gettime() - NTP user application interface
290 *
291 * See the timex.h header file for synopsis and API description. Note that
292 * the TAI offset is returned in the ntvtimeval.tai structure member.
293 */
294 #ifndef _SYS_SYSPROTO_H_
295 struct ntp_gettime_args {
296 struct ntptimeval *ntvp;
297 };
298 #endif
299 /* ARGSUSED */
300 int
301 sys_ntp_gettime(struct thread *td, struct ntp_gettime_args *uap)
302 {
303 struct ntptimeval ntv;
304
305 NTPADJ_LOCK();
306 ntp_gettime1(&ntv);
307 NTPADJ_UNLOCK();
308
309 td->td_retval[0] = ntv.time_state;
310 return (copyout(&ntv, uap->ntvp, sizeof(ntv)));
311 }
312
313 static int
314 ntp_sysctl(SYSCTL_HANDLER_ARGS)
315 {
316 struct ntptimeval ntv; /* temporary structure */
317
318 NTPADJ_LOCK();
319 ntp_gettime1(&ntv);
320 NTPADJ_UNLOCK();
321
322 return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req));
323 }
324
325 SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, "");
326 SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE | CTLFLAG_RD |
327 CTLFLAG_MPSAFE, 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval",
328 "");
329
330 #ifdef PPS_SYNC
331 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW,
332 &pps_shiftmax, 0, "Max interval duration (sec) (shift)");
333 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW,
334 &pps_shift, 0, "Interval duration (sec) (shift)");
335 SYSCTL_LONG(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD,
336 &time_monitor, 0, "Last time offset scaled (ns)");
337
338 SYSCTL_S64(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD | CTLFLAG_MPSAFE,
339 &pps_freq, 0,
340 "Scaled frequency offset (ns/sec)");
341 SYSCTL_S64(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD | CTLFLAG_MPSAFE,
342 &time_freq, 0,
343 "Frequency offset (ns/sec)");
344 #endif
345
346 /*
347 * ntp_adjtime() - NTP daemon application interface
348 *
349 * See the timex.h header file for synopsis and API description. Note that
350 * the timex.constant structure member has a dual purpose to set the time
351 * constant and to set the TAI offset.
352 */
353 #ifndef _SYS_SYSPROTO_H_
354 struct ntp_adjtime_args {
355 struct timex *tp;
356 };
357 #endif
358
359 int
360 sys_ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap)
361 {
362 struct timex ntv; /* temporary structure */
363 long freq; /* frequency ns/s) */
364 int modes; /* mode bits from structure */
365 int error, retval;
366
367 error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv));
368 if (error)
369 return (error);
370
371 /*
372 * Update selected clock variables - only the superuser can
373 * change anything. Note that there is no error checking here on
374 * the assumption the superuser should know what it is doing.
375 * Note that either the time constant or TAI offset are loaded
376 * from the ntv.constant member, depending on the mode bits. If
377 * the STA_PLL bit in the status word is cleared, the state and
378 * status words are reset to the initial values at boot.
379 */
380 modes = ntv.modes;
381 if (modes)
382 error = priv_check(td, PRIV_NTP_ADJTIME);
383 if (error != 0)
384 return (error);
385 NTPADJ_LOCK();
386 if (modes & MOD_MAXERROR)
387 time_maxerror = ntv.maxerror;
388 if (modes & MOD_ESTERROR)
389 time_esterror = ntv.esterror;
390 if (modes & MOD_STATUS) {
391 if (time_status & STA_PLL && !(ntv.status & STA_PLL)) {
392 time_state = TIME_OK;
393 time_status = STA_UNSYNC;
394 #ifdef PPS_SYNC
395 pps_shift = PPS_FAVG;
396 #endif /* PPS_SYNC */
397 }
398 time_status &= STA_RONLY;
399 time_status |= ntv.status & ~STA_RONLY;
400 }
401 if (modes & MOD_TIMECONST) {
402 if (ntv.constant < 0)
403 time_constant = 0;
404 else if (ntv.constant > MAXTC)
405 time_constant = MAXTC;
406 else
407 time_constant = ntv.constant;
408 }
409 if (modes & MOD_TAI) {
410 if (ntv.constant > 0) /* XXX zero & negative numbers ? */
411 time_tai = ntv.constant;
412 }
413 #ifdef PPS_SYNC
414 if (modes & MOD_PPSMAX) {
415 if (ntv.shift < PPS_FAVG)
416 pps_shiftmax = PPS_FAVG;
417 else if (ntv.shift > PPS_FAVGMAX)
418 pps_shiftmax = PPS_FAVGMAX;
419 else
420 pps_shiftmax = ntv.shift;
421 }
422 #endif /* PPS_SYNC */
423 if (modes & MOD_NANO)
424 time_status |= STA_NANO;
425 if (modes & MOD_MICRO)
426 time_status &= ~STA_NANO;
427 if (modes & MOD_CLKB)
428 time_status |= STA_CLK;
429 if (modes & MOD_CLKA)
430 time_status &= ~STA_CLK;
431 if (modes & MOD_FREQUENCY) {
432 freq = (ntv.freq * 1000LL) >> 16;
433 if (freq > MAXFREQ)
434 L_LINT(time_freq, MAXFREQ);
435 else if (freq < -MAXFREQ)
436 L_LINT(time_freq, -MAXFREQ);
437 else {
438 /*
439 * ntv.freq is [PPM * 2^16] = [us/s * 2^16]
440 * time_freq is [ns/s * 2^32]
441 */
442 time_freq = ntv.freq * 1000LL * 65536LL;
443 }
444 #ifdef PPS_SYNC
445 pps_freq = time_freq;
446 #endif /* PPS_SYNC */
447 }
448 if (modes & MOD_OFFSET) {
449 if (time_status & STA_NANO)
450 hardupdate(ntv.offset);
451 else
452 hardupdate(ntv.offset * 1000);
453 }
454
455 /*
456 * Retrieve all clock variables. Note that the TAI offset is
457 * returned only by ntp_gettime();
458 */
459 if (time_status & STA_NANO)
460 ntv.offset = L_GINT(time_offset);
461 else
462 ntv.offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */
463 ntv.freq = L_GINT((time_freq / 1000LL) << 16);
464 ntv.maxerror = time_maxerror;
465 ntv.esterror = time_esterror;
466 ntv.status = time_status;
467 ntv.constant = time_constant;
468 if (time_status & STA_NANO)
469 ntv.precision = time_precision;
470 else
471 ntv.precision = time_precision / 1000;
472 ntv.tolerance = MAXFREQ * SCALE_PPM;
473 #ifdef PPS_SYNC
474 ntv.shift = pps_shift;
475 ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16);
476 if (time_status & STA_NANO)
477 ntv.jitter = pps_jitter;
478 else
479 ntv.jitter = pps_jitter / 1000;
480 ntv.stabil = pps_stabil;
481 ntv.calcnt = pps_calcnt;
482 ntv.errcnt = pps_errcnt;
483 ntv.jitcnt = pps_jitcnt;
484 ntv.stbcnt = pps_stbcnt;
485 #endif /* PPS_SYNC */
486 retval = ntp_is_time_error(time_status) ? TIME_ERROR : time_state;
487 NTPADJ_UNLOCK();
488
489 error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv));
490 if (error == 0)
491 td->td_retval[0] = retval;
492 return (error);
493 }
494
495 /*
496 * second_overflow() - called after ntp_tick_adjust()
497 *
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
501 * simulation.
502 */
503 void
504 ntp_update_second(int64_t *adjustment, time_t *newsec)
505 {
506 int tickrate;
507 l_fp ftemp; /* 32/64-bit temporary */
508
509 /*
510 * On rollover of the second both the nanosecond and microsecond
511 * clocks are updated and the state machine cranked as
512 * necessary. The phase adjustment to be used for the next
513 * second is calculated and the maximum error is increased by
514 * the tolerance.
515 */
516 time_maxerror += MAXFREQ / 1000;
517
518 /*
519 * Leap second processing. If in leap-insert state at
520 * the end of the day, the system clock is set back one
521 * second; if in leap-delete state, the system clock is
522 * set ahead one second. The nano_time() routine or
523 * external clock driver will insure that reported time
524 * is always monotonic.
525 */
526 switch (time_state) {
527
528 /*
529 * No warning.
530 */
531 case TIME_OK:
532 if (time_status & STA_INS)
533 time_state = TIME_INS;
534 else if (time_status & STA_DEL)
535 time_state = TIME_DEL;
536 break;
537
538 /*
539 * Insert second 23:59:60 following second
540 * 23:59:59.
541 */
542 case TIME_INS:
543 if (!(time_status & STA_INS))
544 time_state = TIME_OK;
545 else if ((*newsec) % 86400 == 0) {
546 (*newsec)--;
547 time_state = TIME_OOP;
548 time_tai++;
549 }
550 break;
551
552 /*
553 * Delete second 23:59:59.
554 */
555 case TIME_DEL:
556 if (!(time_status & STA_DEL))
557 time_state = TIME_OK;
558 else if (((*newsec) + 1) % 86400 == 0) {
559 (*newsec)++;
560 time_tai--;
561 time_state = TIME_WAIT;
562 }
563 break;
564
565 /*
566 * Insert second in progress.
567 */
568 case TIME_OOP:
569 time_state = TIME_WAIT;
570 break;
571
572 /*
573 * Wait for status bits to clear.
574 */
575 case TIME_WAIT:
576 if (!(time_status & (STA_INS | STA_DEL)))
577 time_state = TIME_OK;
578 }
579
580 /*
581 * Compute the total time adjustment for the next second
582 * in ns. The offset is reduced by a factor depending on
583 * whether the PPS signal is operating. Note that the
584 * value is in effect scaled by the clock frequency,
585 * since the adjustment is added at each tick interrupt.
586 */
587 ftemp = time_offset;
588 #ifdef PPS_SYNC
589 /* XXX even if PPS signal dies we should finish adjustment ? */
590 if (time_status & STA_PPSTIME && time_status &
591 STA_PPSSIGNAL)
592 L_RSHIFT(ftemp, pps_shift);
593 else
594 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
595 #else
596 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
597 #endif /* PPS_SYNC */
598 time_adj = ftemp;
599 L_SUB(time_offset, ftemp);
600 L_ADD(time_adj, time_freq);
601
602 /*
603 * Apply any correction from adjtime(2). If more than one second
604 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM)
605 * until the last second is slewed the final < 500 usecs.
606 */
607 if (time_adjtime != 0) {
608 if (time_adjtime > 1000000)
609 tickrate = 5000;
610 else if (time_adjtime < -1000000)
611 tickrate = -5000;
612 else if (time_adjtime > 500)
613 tickrate = 500;
614 else if (time_adjtime < -500)
615 tickrate = -500;
616 else
617 tickrate = time_adjtime;
618 time_adjtime -= tickrate;
619 L_LINT(ftemp, tickrate * 1000);
620 L_ADD(time_adj, ftemp);
621 }
622 *adjustment = time_adj;
623
624 #ifdef PPS_SYNC
625 if (pps_valid > 0)
626 pps_valid--;
627 else
628 time_status &= ~STA_PPSSIGNAL;
629 #endif /* PPS_SYNC */
630 }
631
632 /*
633 * ntp_init() - initialize variables and structures
634 *
635 * This routine must be called after the kernel variables hz and tick
636 * are set or changed and before the next tick interrupt. In this
637 * particular implementation, these values are assumed set elsewhere in
638 * the kernel. The design allows the clock frequency and tick interval
639 * to be changed while the system is running. So, this routine should
640 * probably be integrated with the code that does that.
641 */
642 static void
643 ntp_init(void)
644 {
645
646 /*
647 * The following variables are initialized only at startup. Only
648 * those structures not cleared by the compiler need to be
649 * initialized, and these only in the simulator. In the actual
650 * kernel, any nonzero values here will quickly evaporate.
651 */
652 L_CLR(time_offset);
653 L_CLR(time_freq);
654 #ifdef PPS_SYNC
655 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;
656 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;
657 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;
658 pps_fcount = 0;
659 L_CLR(pps_freq);
660 #endif /* PPS_SYNC */
661 }
662
663 SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL);
664
665 /*
666 * hardupdate() - local clock update
667 *
668 * This routine is called by ntp_adjtime() to update the local clock
669 * phase and frequency. The implementation is of an adaptive-parameter,
670 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
671 * time and frequency offset estimates for each call. If the kernel PPS
672 * discipline code is configured (PPS_SYNC), the PPS signal itself
673 * determines the new time offset, instead of the calling argument.
674 * Presumably, calls to ntp_adjtime() occur only when the caller
675 * believes the local clock is valid within some bound (+-128 ms with
676 * NTP). If the caller's time is far different than the PPS time, an
677 * argument will ensue, and it's not clear who will lose.
678 *
679 * For uncompensated quartz crystal oscillators and nominal update
680 * intervals less than 256 s, operation should be in phase-lock mode,
681 * where the loop is disciplined to phase. For update intervals greater
682 * than 1024 s, operation should be in frequency-lock mode, where the
683 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
684 * is selected by the STA_MODE status bit.
685 */
686 static void
687 hardupdate(offset)
688 long offset; /* clock offset (ns) */
689 {
690 long mtemp;
691 l_fp ftemp;
692
693 NTPADJ_ASSERT_LOCKED();
694
695 /*
696 * Select how the phase is to be controlled and from which
697 * source. If the PPS signal is present and enabled to
698 * discipline the time, the PPS offset is used; otherwise, the
699 * argument offset is used.
700 */
701 if (!(time_status & STA_PLL))
702 return;
703 if (!(time_status & STA_PPSTIME && time_status &
704 STA_PPSSIGNAL)) {
705 if (offset > MAXPHASE)
706 time_monitor = MAXPHASE;
707 else if (offset < -MAXPHASE)
708 time_monitor = -MAXPHASE;
709 else
710 time_monitor = offset;
711 L_LINT(time_offset, time_monitor);
712 }
713
714 /*
715 * Select how the frequency is to be controlled and in which
716 * mode (PLL or FLL). If the PPS signal is present and enabled
717 * to discipline the frequency, the PPS frequency is used;
718 * otherwise, the argument offset is used to compute it.
719 */
720 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {
721 time_reftime = time_uptime;
722 return;
723 }
724 if (time_status & STA_FREQHOLD || time_reftime == 0)
725 time_reftime = time_uptime;
726 mtemp = time_uptime - time_reftime;
727 L_LINT(ftemp, time_monitor);
728 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
729 L_MPY(ftemp, mtemp);
730 L_ADD(time_freq, ftemp);
731 time_status &= ~STA_MODE;
732 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
733 MAXSEC)) {
734 L_LINT(ftemp, (time_monitor << 4) / mtemp);
735 L_RSHIFT(ftemp, SHIFT_FLL + 4);
736 L_ADD(time_freq, ftemp);
737 time_status |= STA_MODE;
738 }
739 time_reftime = time_uptime;
740 if (L_GINT(time_freq) > MAXFREQ)
741 L_LINT(time_freq, MAXFREQ);
742 else if (L_GINT(time_freq) < -MAXFREQ)
743 L_LINT(time_freq, -MAXFREQ);
744 }
745
746 #ifdef PPS_SYNC
747 /*
748 * hardpps() - discipline CPU clock oscillator to external PPS signal
749 *
750 * This routine is called at each PPS interrupt in order to discipline
751 * the CPU clock oscillator to the PPS signal. There are two independent
752 * first-order feedback loops, one for the phase, the other for the
753 * frequency. The phase loop measures and grooms the PPS phase offset
754 * and leaves it in a handy spot for the seconds overflow routine. The
755 * frequency loop averages successive PPS phase differences and
756 * calculates the PPS frequency offset, which is also processed by the
757 * seconds overflow routine. The code requires the caller to capture the
758 * time and architecture-dependent hardware counter values in
759 * nanoseconds at the on-time PPS signal transition.
760 *
761 * Note that, on some Unix systems this routine runs at an interrupt
762 * priority level higher than the timer interrupt routine hardclock().
763 * Therefore, the variables used are distinct from the hardclock()
764 * variables, except for the actual time and frequency variables, which
765 * are determined by this routine and updated atomically.
766 */
767 void
768 hardpps(tsp, nsec)
769 struct timespec *tsp; /* time at PPS */
770 long nsec; /* hardware counter at PPS */
771 {
772 long u_sec, u_nsec, v_nsec; /* temps */
773 l_fp ftemp;
774
775 NTPADJ_LOCK();
776
777 /*
778 * The signal is first processed by a range gate and frequency
779 * discriminator. The range gate rejects noise spikes outside
780 * the range +-500 us. The frequency discriminator rejects input
781 * signals with apparent frequency outside the range 1 +-500
782 * PPM. If two hits occur in the same second, we ignore the
783 * later hit; if not and a hit occurs outside the range gate,
784 * keep the later hit for later comparison, but do not process
785 * it.
786 */
787 time_status |= STA_PPSSIGNAL | STA_PPSJITTER;
788 time_status &= ~(STA_PPSWANDER | STA_PPSERROR);
789 pps_valid = PPS_VALID;
790 u_sec = tsp->tv_sec;
791 u_nsec = tsp->tv_nsec;
792 if (u_nsec >= (NANOSECOND >> 1)) {
793 u_nsec -= NANOSECOND;
794 u_sec++;
795 }
796 v_nsec = u_nsec - pps_tf[0].tv_nsec;
797 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - MAXFREQ)
798 goto out;
799 pps_tf[2] = pps_tf[1];
800 pps_tf[1] = pps_tf[0];
801 pps_tf[0].tv_sec = u_sec;
802 pps_tf[0].tv_nsec = u_nsec;
803
804 /*
805 * Compute the difference between the current and previous
806 * counter values. If the difference exceeds 0.5 s, assume it
807 * has wrapped around, so correct 1.0 s. If the result exceeds
808 * the tick interval, the sample point has crossed a tick
809 * boundary during the last second, so correct the tick. Very
810 * intricate.
811 */
812 u_nsec = nsec;
813 if (u_nsec > (NANOSECOND >> 1))
814 u_nsec -= NANOSECOND;
815 else if (u_nsec < -(NANOSECOND >> 1))
816 u_nsec += NANOSECOND;
817 pps_fcount += u_nsec;
818 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
819 goto out;
820 time_status &= ~STA_PPSJITTER;
821
822 /*
823 * A three-stage median filter is used to help denoise the PPS
824 * time. The median sample becomes the time offset estimate; the
825 * difference between the other two samples becomes the time
826 * dispersion (jitter) estimate.
827 */
828 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {
829 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {
830 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */
831 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;
832 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {
833 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */
834 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;
835 } else {
836 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */
837 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;
838 }
839 } else {
840 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {
841 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */
842 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;
843 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {
844 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */
845 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;
846 } else {
847 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */
848 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;
849 }
850 }
851
852 /*
853 * Nominal jitter is due to PPS signal noise and interrupt
854 * latency. If it exceeds the popcorn threshold, the sample is
855 * discarded. otherwise, if so enabled, the time offset is
856 * updated. We can tolerate a modest loss of data here without
857 * much degrading time accuracy.
858 *
859 * The measurements being checked here were made with the system
860 * timecounter, so the popcorn threshold is not allowed to fall below
861 * the number of nanoseconds in two ticks of the timecounter. For a
862 * timecounter running faster than 1 GHz the lower bound is 2ns, just
863 * to avoid a nonsensical threshold of zero.
864 */
865 if (u_nsec > lmax(pps_jitter << PPS_POPCORN,
866 2 * (NANOSECOND / (long)qmin(NANOSECOND, tc_getfrequency())))) {
867 time_status |= STA_PPSJITTER;
868 pps_jitcnt++;
869 } else if (time_status & STA_PPSTIME) {
870 time_monitor = -v_nsec;
871 L_LINT(time_offset, time_monitor);
872 }
873 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;
874 u_sec = pps_tf[0].tv_sec - pps_lastsec;
875 if (u_sec < (1 << pps_shift))
876 goto out;
877
878 /*
879 * At the end of the calibration interval the difference between
880 * the first and last counter values becomes the scaled
881 * frequency. It will later be divided by the length of the
882 * interval to determine the frequency update. If the frequency
883 * exceeds a sanity threshold, or if the actual calibration
884 * interval is not equal to the expected length, the data are
885 * discarded. We can tolerate a modest loss of data here without
886 * much degrading frequency accuracy.
887 */
888 pps_calcnt++;
889 v_nsec = -pps_fcount;
890 pps_lastsec = pps_tf[0].tv_sec;
891 pps_fcount = 0;
892 u_nsec = MAXFREQ << pps_shift;
893 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << pps_shift)) {
894 time_status |= STA_PPSERROR;
895 pps_errcnt++;
896 goto out;
897 }
898
899 /*
900 * Here the raw frequency offset and wander (stability) is
901 * calculated. If the wander is less than the wander threshold
902 * for four consecutive averaging intervals, the interval is
903 * doubled; if it is greater than the threshold for four
904 * consecutive intervals, the interval is halved. The scaled
905 * frequency offset is converted to frequency offset. The
906 * stability metric is calculated as the average of recent
907 * frequency changes, but is used only for performance
908 * monitoring.
909 */
910 L_LINT(ftemp, v_nsec);
911 L_RSHIFT(ftemp, pps_shift);
912 L_SUB(ftemp, pps_freq);
913 u_nsec = L_GINT(ftemp);
914 if (u_nsec > PPS_MAXWANDER) {
915 L_LINT(ftemp, PPS_MAXWANDER);
916 pps_intcnt--;
917 time_status |= STA_PPSWANDER;
918 pps_stbcnt++;
919 } else if (u_nsec < -PPS_MAXWANDER) {
920 L_LINT(ftemp, -PPS_MAXWANDER);
921 pps_intcnt--;
922 time_status |= STA_PPSWANDER;
923 pps_stbcnt++;
924 } else {
925 pps_intcnt++;
926 }
927 if (pps_intcnt >= 4) {
928 pps_intcnt = 4;
929 if (pps_shift < pps_shiftmax) {
930 pps_shift++;
931 pps_intcnt = 0;
932 }
933 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {
934 pps_intcnt = -4;
935 if (pps_shift > PPS_FAVG) {
936 pps_shift--;
937 pps_intcnt = 0;
938 }
939 }
940 if (u_nsec < 0)
941 u_nsec = -u_nsec;
942 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;
943
944 /*
945 * The PPS frequency is recalculated and clamped to the maximum
946 * MAXFREQ. If enabled, the system clock frequency is updated as
947 * well.
948 */
949 L_ADD(pps_freq, ftemp);
950 u_nsec = L_GINT(pps_freq);
951 if (u_nsec > MAXFREQ)
952 L_LINT(pps_freq, MAXFREQ);
953 else if (u_nsec < -MAXFREQ)
954 L_LINT(pps_freq, -MAXFREQ);
955 if (time_status & STA_PPSFREQ)
956 time_freq = pps_freq;
957
958 out:
959 NTPADJ_UNLOCK();
960 }
961 #endif /* PPS_SYNC */
962
963 #ifndef _SYS_SYSPROTO_H_
964 struct adjtime_args {
965 struct timeval *delta;
966 struct timeval *olddelta;
967 };
968 #endif
969 /* ARGSUSED */
970 int
971 sys_adjtime(struct thread *td, struct adjtime_args *uap)
972 {
973 struct timeval delta, olddelta, *deltap;
974 int error;
975
976 if (uap->delta) {
977 error = copyin(uap->delta, &delta, sizeof(delta));
978 if (error)
979 return (error);
980 deltap = δ
981 } else
982 deltap = NULL;
983 error = kern_adjtime(td, deltap, &olddelta);
984 if (uap->olddelta && error == 0)
985 error = copyout(&olddelta, uap->olddelta, sizeof(olddelta));
986 return (error);
987 }
988
989 int
990 kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta)
991 {
992 struct timeval atv;
993 int64_t ltr, ltw;
994 int error;
995
996 if (delta != NULL) {
997 error = priv_check(td, PRIV_ADJTIME);
998 if (error != 0)
999 return (error);
1000 ltw = (int64_t)delta->tv_sec * 1000000 + delta->tv_usec;
1001 }
1002 NTPADJ_LOCK();
1003 ltr = time_adjtime;
1004 if (delta != NULL)
1005 time_adjtime = ltw;
1006 NTPADJ_UNLOCK();
1007 if (olddelta != NULL) {
1008 atv.tv_sec = ltr / 1000000;
1009 atv.tv_usec = ltr % 1000000;
1010 if (atv.tv_usec < 0) {
1011 atv.tv_usec += 1000000;
1012 atv.tv_sec--;
1013 }
1014 *olddelta = atv;
1015 }
1016 return (0);
1017 }
1018
1019 static struct callout resettodr_callout;
1020 static int resettodr_period = 1800;
1021
1022 static void
1023 periodic_resettodr(void *arg __unused)
1024 {
1025
1026 /*
1027 * Read of time_status is lock-less, which is fine since
1028 * ntp_is_time_error() operates on the consistent read value.
1029 */
1030 if (!ntp_is_time_error(time_status))
1031 resettodr();
1032 if (resettodr_period > 0)
1033 callout_schedule(&resettodr_callout, resettodr_period * hz);
1034 }
1035
1036 static void
1037 shutdown_resettodr(void *arg __unused, int howto __unused)
1038 {
1039
1040 callout_drain(&resettodr_callout);
1041 /* Another unlocked read of time_status */
1042 if (resettodr_period > 0 && !ntp_is_time_error(time_status))
1043 resettodr();
1044 }
1045
1046 static int
1047 sysctl_resettodr_period(SYSCTL_HANDLER_ARGS)
1048 {
1049 int error;
1050
1051 error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
1052 if (error || !req->newptr)
1053 return (error);
1054 if (cold)
1055 goto done;
1056 if (resettodr_period == 0)
1057 callout_stop(&resettodr_callout);
1058 else
1059 callout_reset(&resettodr_callout, resettodr_period * hz,
1060 periodic_resettodr, NULL);
1061 done:
1062 return (0);
1063 }
1064
1065 SYSCTL_PROC(_machdep, OID_AUTO, rtc_save_period, CTLTYPE_INT | CTLFLAG_RWTUN |
1066 CTLFLAG_MPSAFE, &resettodr_period, 1800, sysctl_resettodr_period, "I",
1067 "Save system time to RTC with this period (in seconds)");
1068
1069 static void
1070 start_periodic_resettodr(void *arg __unused)
1071 {
1072
1073 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_resettodr, NULL,
1074 SHUTDOWN_PRI_FIRST);
1075 callout_init(&resettodr_callout, 1);
1076 if (resettodr_period == 0)
1077 return;
1078 callout_reset(&resettodr_callout, resettodr_period * hz,
1079 periodic_resettodr, NULL);
1080 }
1081
1082 SYSINIT(periodic_resettodr, SI_SUB_LAST, SI_ORDER_MIDDLE,
1083 start_periodic_resettodr, NULL);
Cache object: 195f9f9d410408d87411284df81244ed
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