proc->thread stage 4: rework the VFS and DEVICE subsystems to take thread
[dragonfly.git] / sys / kern / kern_ntptime.c
CommitLineData
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1/***********************************************************************
2 * *
3 * Copyright (c) David L. Mills 1993-2001 *
4 * *
5 * Permission to use, copy, modify, and distribute this software and *
6 * its documentation for any purpose and without fee is hereby *
7 * granted, provided that the above copyright notice appears in all *
8 * copies and that both the copyright notice and this permission *
9 * notice appear in supporting documentation, and that the name *
10 * University of Delaware not be used in advertising or publicity *
11 * pertaining to distribution of the software without specific, *
12 * written prior permission. The University of Delaware makes no *
13 * representations about the suitability this software for any *
14 * purpose. It is provided "as is" without express or implied *
15 * warranty. *
16 * *
17 **********************************************************************/
18
19/*
20 * Adapted from the original sources for FreeBSD and timecounters by:
21 * Poul-Henning Kamp <phk@FreeBSD.org>.
22 *
23 * The 32bit version of the "LP" macros seems a bit past its "sell by"
24 * date so I have retained only the 64bit version and included it directly
25 * in this file.
26 *
27 * Only minor changes done to interface with the timecounters over in
28 * sys/kern/kern_clock.c. Some of the comments below may be (even more)
29 * confusing and/or plain wrong in that context.
30 *
31 * $FreeBSD: src/sys/kern/kern_ntptime.c,v 1.32.2.2 2001/04/22 11:19:46 jhay Exp $
dadab5e9 32 * $DragonFly: src/sys/kern/kern_ntptime.c,v 1.4 2003/06/25 03:55:57 dillon Exp $
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33 */
34
35#include "opt_ntp.h"
36
37#include <sys/param.h>
38#include <sys/systm.h>
39#include <sys/sysproto.h>
40#include <sys/kernel.h>
41#include <sys/proc.h>
42#include <sys/time.h>
43#include <sys/timex.h>
44#include <sys/timepps.h>
45#include <sys/sysctl.h>
46
47/*
48 * Single-precision macros for 64-bit machines
49 */
50typedef long long l_fp;
51#define L_ADD(v, u) ((v) += (u))
52#define L_SUB(v, u) ((v) -= (u))
53#define L_ADDHI(v, a) ((v) += (long long)(a) << 32)
54#define L_NEG(v) ((v) = -(v))
55#define L_RSHIFT(v, n) \
56 do { \
57 if ((v) < 0) \
58 (v) = -(-(v) >> (n)); \
59 else \
60 (v) = (v) >> (n); \
61 } while (0)
62#define L_MPY(v, a) ((v) *= (a))
63#define L_CLR(v) ((v) = 0)
64#define L_ISNEG(v) ((v) < 0)
65#define L_LINT(v, a) ((v) = (long long)(a) << 32)
66#define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32)
67
68/*
69 * Generic NTP kernel interface
70 *
71 * These routines constitute the Network Time Protocol (NTP) interfaces
72 * for user and daemon application programs. The ntp_gettime() routine
73 * provides the time, maximum error (synch distance) and estimated error
74 * (dispersion) to client user application programs. The ntp_adjtime()
75 * routine is used by the NTP daemon to adjust the system clock to an
76 * externally derived time. The time offset and related variables set by
77 * this routine are used by other routines in this module to adjust the
78 * phase and frequency of the clock discipline loop which controls the
79 * system clock.
80 *
81 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO
82 * defined), the time at each tick interrupt is derived directly from
83 * the kernel time variable. When the kernel time is reckoned in
84 * microseconds, (NTP_NANO undefined), the time is derived from the
85 * kernel time variable together with a variable representing the
86 * leftover nanoseconds at the last tick interrupt. In either case, the
87 * current nanosecond time is reckoned from these values plus an
88 * interpolated value derived by the clock routines in another
89 * architecture-specific module. The interpolation can use either a
90 * dedicated counter or a processor cycle counter (PCC) implemented in
91 * some architectures.
92 *
93 * Note that all routines must run at priority splclock or higher.
94 */
95/*
96 * Phase/frequency-lock loop (PLL/FLL) definitions
97 *
98 * The nanosecond clock discipline uses two variable types, time
99 * variables and frequency variables. Both types are represented as 64-
100 * bit fixed-point quantities with the decimal point between two 32-bit
101 * halves. On a 32-bit machine, each half is represented as a single
102 * word and mathematical operations are done using multiple-precision
103 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is
104 * used.
105 *
106 * A time variable is a signed 64-bit fixed-point number in ns and
107 * fraction. It represents the remaining time offset to be amortized
108 * over succeeding tick interrupts. The maximum time offset is about
109 * 0.5 s and the resolution is about 2.3e-10 ns.
110 *
111 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
112 * 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
113 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
114 * |s s s| ns |
115 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
116 * | fraction |
117 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
118 *
119 * A frequency variable is a signed 64-bit fixed-point number in ns/s
120 * and fraction. It represents the ns and fraction to be added to the
121 * kernel time variable at each second. The maximum frequency offset is
122 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s.
123 *
124 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
125 * 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
126 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
127 * |s s s s s s s s s s s s s| ns/s |
128 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
129 * | fraction |
130 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
131 */
132/*
133 * The following variables establish the state of the PLL/FLL and the
134 * residual time and frequency offset of the local clock.
135 */
136#define SHIFT_PLL 4 /* PLL loop gain (shift) */
137#define SHIFT_FLL 2 /* FLL loop gain (shift) */
138
139static int time_state = TIME_OK; /* clock state */
140static int time_status = STA_UNSYNC; /* clock status bits */
141static long time_tai; /* TAI offset (s) */
142static long time_monitor; /* last time offset scaled (ns) */
143static long time_constant; /* poll interval (shift) (s) */
144static long time_precision = 1; /* clock precision (ns) */
145static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */
146static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */
147static long time_reftime; /* time at last adjustment (s) */
148static long time_tick; /* nanoseconds per tick (ns) */
149static l_fp time_offset; /* time offset (ns) */
150static l_fp time_freq; /* frequency offset (ns/s) */
151static l_fp time_adj; /* tick adjust (ns/s) */
152
153#ifdef PPS_SYNC
154/*
155 * The following variables are used when a pulse-per-second (PPS) signal
156 * is available and connected via a modem control lead. They establish
157 * the engineering parameters of the clock discipline loop when
158 * controlled by the PPS signal.
159 */
160#define PPS_FAVG 2 /* min freq avg interval (s) (shift) */
161#define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */
162#define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */
163#define PPS_PAVG 4 /* phase avg interval (s) (shift) */
164#define PPS_VALID 120 /* PPS signal watchdog max (s) */
165#define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */
166#define PPS_POPCORN 2 /* popcorn spike threshold (shift) */
167
168static struct timespec pps_tf[3]; /* phase median filter */
169static l_fp pps_freq; /* scaled frequency offset (ns/s) */
170static long pps_fcount; /* frequency accumulator */
171static long pps_jitter; /* nominal jitter (ns) */
172static long pps_stabil; /* nominal stability (scaled ns/s) */
173static long pps_lastsec; /* time at last calibration (s) */
174static int pps_valid; /* signal watchdog counter */
175static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */
176static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */
177static int pps_intcnt; /* wander counter */
178
179/*
180 * PPS signal quality monitors
181 */
182static long pps_calcnt; /* calibration intervals */
183static long pps_jitcnt; /* jitter limit exceeded */
184static long pps_stbcnt; /* stability limit exceeded */
185static long pps_errcnt; /* calibration errors */
186#endif /* PPS_SYNC */
187/*
188 * End of phase/frequency-lock loop (PLL/FLL) definitions
189 */
190
191static void ntp_init(void);
192static void hardupdate(long offset);
193
194/*
195 * ntp_gettime() - NTP user application interface
196 *
197 * See the timex.h header file for synopsis and API description. Note
198 * that the TAI offset is returned in the ntvtimeval.tai structure
199 * member.
200 */
201static int
202ntp_sysctl(SYSCTL_HANDLER_ARGS)
203{
204 struct ntptimeval ntv; /* temporary structure */
205 struct timespec atv; /* nanosecond time */
206
207 nanotime(&atv);
208 ntv.time.tv_sec = atv.tv_sec;
209 ntv.time.tv_nsec = atv.tv_nsec;
210 ntv.maxerror = time_maxerror;
211 ntv.esterror = time_esterror;
212 ntv.tai = time_tai;
213 ntv.time_state = time_state;
214
215 /*
216 * Status word error decode. If any of these conditions occur,
217 * an error is returned, instead of the status word. Most
218 * applications will care only about the fact the system clock
219 * may not be trusted, not about the details.
220 *
221 * Hardware or software error
222 */
223 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||
224
225 /*
226 * PPS signal lost when either time or frequency synchronization
227 * requested
228 */
229 (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
230 !(time_status & STA_PPSSIGNAL)) ||
231
232 /*
233 * PPS jitter exceeded when time synchronization requested
234 */
235 (time_status & STA_PPSTIME &&
236 time_status & STA_PPSJITTER) ||
237
238 /*
239 * PPS wander exceeded or calibration error when frequency
240 * synchronization requested
241 */
242 (time_status & STA_PPSFREQ &&
243 time_status & (STA_PPSWANDER | STA_PPSERROR)))
244 ntv.time_state = TIME_ERROR;
245 return (sysctl_handle_opaque(oidp, &ntv, sizeof ntv, req));
246}
247
248SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, "");
249SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD,
250 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", "");
251
252#ifdef PPS_SYNC
253SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, &pps_shiftmax, 0, "");
254SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, &pps_shift, 0, "");
255SYSCTL_INT(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, &time_monitor, 0, "");
256
257SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD, &pps_freq, sizeof(pps_freq), "I", "");
258SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD, &time_freq, sizeof(time_freq), "I", "");
259#endif
260/*
261 * ntp_adjtime() - NTP daemon application interface
262 *
263 * See the timex.h header file for synopsis and API description. Note
264 * that the timex.constant structure member has a dual purpose to set
265 * the time constant and to set the TAI offset.
266 */
267#ifndef _SYS_SYSPROTO_H_
268struct ntp_adjtime_args {
269 struct timex *tp;
270};
271#endif
272
273int
41c20dac 274ntp_adjtime(struct ntp_adjtime_args *uap)
984263bc 275{
dadab5e9 276 struct thread *td = curthread;
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277 struct timex ntv; /* temporary structure */
278 long freq; /* frequency ns/s) */
279 int modes; /* mode bits from structure */
280 int s; /* caller priority */
281 int error;
282
283 error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv));
284 if (error)
285 return(error);
286
287 /*
288 * Update selected clock variables - only the superuser can
289 * change anything. Note that there is no error checking here on
290 * the assumption the superuser should know what it is doing.
291 * Note that either the time constant or TAI offset are loaded
292 * from the ntv.constant member, depending on the mode bits. If
293 * the STA_PLL bit in the status word is cleared, the state and
294 * status words are reset to the initial values at boot.
295 */
296 modes = ntv.modes;
297 if (modes)
dadab5e9 298 error = suser(td);
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299 if (error)
300 return (error);
301 s = splclock();
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_OFFSET) {
348 if (time_status & STA_NANO)
349 hardupdate(ntv.offset);
350 else
351 hardupdate(ntv.offset * 1000);
352 }
353 if (modes & MOD_FREQUENCY) {
354 freq = (ntv.freq * 1000LL) >> 16;
355 if (freq > MAXFREQ)
356 L_LINT(time_freq, MAXFREQ);
357 else if (freq < -MAXFREQ)
358 L_LINT(time_freq, -MAXFREQ);
359 else
360 L_LINT(time_freq, freq);
361#ifdef PPS_SYNC
362 pps_freq = time_freq;
363#endif /* PPS_SYNC */
364 }
365
366 /*
367 * Retrieve all clock variables. Note that the TAI offset is
368 * returned only by ntp_gettime();
369 */
370 if (time_status & STA_NANO)
371 ntv.offset = time_monitor;
372 else
373 ntv.offset = time_monitor / 1000; /* XXX rounding ? */
374 ntv.freq = L_GINT((time_freq / 1000LL) << 16);
375 ntv.maxerror = time_maxerror;
376 ntv.esterror = time_esterror;
377 ntv.status = time_status;
378 ntv.constant = time_constant;
379 if (time_status & STA_NANO)
380 ntv.precision = time_precision;
381 else
382 ntv.precision = time_precision / 1000;
383 ntv.tolerance = MAXFREQ * SCALE_PPM;
384#ifdef PPS_SYNC
385 ntv.shift = pps_shift;
386 ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16);
387 if (time_status & STA_NANO)
388 ntv.jitter = pps_jitter;
389 else
390 ntv.jitter = pps_jitter / 1000;
391 ntv.stabil = pps_stabil;
392 ntv.calcnt = pps_calcnt;
393 ntv.errcnt = pps_errcnt;
394 ntv.jitcnt = pps_jitcnt;
395 ntv.stbcnt = pps_stbcnt;
396#endif /* PPS_SYNC */
397 splx(s);
398
399 error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv));
400 if (error)
401 return (error);
402
403 /*
404 * Status word error decode. See comments in
405 * ntp_gettime() routine.
406 */
407 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||
408 (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
409 !(time_status & STA_PPSSIGNAL)) ||
410 (time_status & STA_PPSTIME &&
411 time_status & STA_PPSJITTER) ||
412 (time_status & STA_PPSFREQ &&
413 time_status & (STA_PPSWANDER | STA_PPSERROR)))
41c20dac 414 curproc->p_retval[0] = TIME_ERROR;
984263bc 415 else
41c20dac 416 curproc->p_retval[0] = time_state;
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417 return (error);
418}
419
420/*
421 * second_overflow() - called after ntp_tick_adjust()
422 *
423 * This routine is ordinarily called immediately following the above
424 * routine ntp_tick_adjust(). While these two routines are normally
425 * combined, they are separated here only for the purposes of
426 * simulation.
427 */
428void
429ntp_update_second(struct timecounter *tcp)
430{
431 u_int32_t *newsec;
432 l_fp ftemp; /* 32/64-bit temporary */
433
434 newsec = &tcp->tc_offset_sec;
435 /*
436 * On rollover of the second both the nanosecond and microsecond
437 * clocks are updated and the state machine cranked as
438 * necessary. The phase adjustment to be used for the next
439 * second is calculated and the maximum error is increased by
440 * the tolerance.
441 */
442 time_maxerror += MAXFREQ / 1000;
443
444 /*
445 * Leap second processing. If in leap-insert state at
446 * the end of the day, the system clock is set back one
447 * second; if in leap-delete state, the system clock is
448 * set ahead one second. The nano_time() routine or
449 * external clock driver will insure that reported time
450 * is always monotonic.
451 */
452 switch (time_state) {
453
454 /*
455 * No warning.
456 */
457 case TIME_OK:
458 if (time_status & STA_INS)
459 time_state = TIME_INS;
460 else if (time_status & STA_DEL)
461 time_state = TIME_DEL;
462 break;
463
464 /*
465 * Insert second 23:59:60 following second
466 * 23:59:59.
467 */
468 case TIME_INS:
469 if (!(time_status & STA_INS))
470 time_state = TIME_OK;
471 else if ((*newsec) % 86400 == 0) {
472 (*newsec)--;
473 time_state = TIME_OOP;
474 }
475 break;
476
477 /*
478 * Delete second 23:59:59.
479 */
480 case TIME_DEL:
481 if (!(time_status & STA_DEL))
482 time_state = TIME_OK;
483 else if (((*newsec) + 1) % 86400 == 0) {
484 (*newsec)++;
485 time_tai--;
486 time_state = TIME_WAIT;
487 }
488 break;
489
490 /*
491 * Insert second in progress.
492 */
493 case TIME_OOP:
494 time_tai++;
495 time_state = TIME_WAIT;
496 break;
497
498 /*
499 * Wait for status bits to clear.
500 */
501 case TIME_WAIT:
502 if (!(time_status & (STA_INS | STA_DEL)))
503 time_state = TIME_OK;
504 }
505
506 /*
507 * Compute the total time adjustment for the next second
508 * in ns. The offset is reduced by a factor depending on
509 * whether the PPS signal is operating. Note that the
510 * value is in effect scaled by the clock frequency,
511 * since the adjustment is added at each tick interrupt.
512 */
513 ftemp = time_offset;
514#ifdef PPS_SYNC
515 /* XXX even if PPS signal dies we should finish adjustment ? */
516 if (time_status & STA_PPSTIME && time_status &
517 STA_PPSSIGNAL)
518 L_RSHIFT(ftemp, pps_shift);
519 else
520 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
521#else
522 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
523#endif /* PPS_SYNC */
524 time_adj = ftemp;
525 L_SUB(time_offset, ftemp);
526 L_ADD(time_adj, time_freq);
527 tcp->tc_adjustment = time_adj;
528#ifdef PPS_SYNC
529 if (pps_valid > 0)
530 pps_valid--;
531 else
532 time_status &= ~STA_PPSSIGNAL;
533#endif /* PPS_SYNC */
534}
535
536/*
537 * ntp_init() - initialize variables and structures
538 *
539 * This routine must be called after the kernel variables hz and tick
540 * are set or changed and before the next tick interrupt. In this
541 * particular implementation, these values are assumed set elsewhere in
542 * the kernel. The design allows the clock frequency and tick interval
543 * to be changed while the system is running. So, this routine should
544 * probably be integrated with the code that does that.
545 */
546static void
547ntp_init()
548{
549
550 /*
551 * The following variable must be initialized any time the
552 * kernel variable hz is changed.
553 */
554 time_tick = NANOSECOND / hz;
555
556 /*
557 * The following variables are initialized only at startup. Only
558 * those structures not cleared by the compiler need to be
559 * initialized, and these only in the simulator. In the actual
560 * kernel, any nonzero values here will quickly evaporate.
561 */
562 L_CLR(time_offset);
563 L_CLR(time_freq);
564#ifdef PPS_SYNC
565 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;
566 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;
567 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;
568 pps_fcount = 0;
569 L_CLR(pps_freq);
570#endif /* PPS_SYNC */
571}
572
573SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, ntp_init, NULL)
574
575/*
576 * hardupdate() - local clock update
577 *
578 * This routine is called by ntp_adjtime() to update the local clock
579 * phase and frequency. The implementation is of an adaptive-parameter,
580 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
581 * time and frequency offset estimates for each call. If the kernel PPS
582 * discipline code is configured (PPS_SYNC), the PPS signal itself
583 * determines the new time offset, instead of the calling argument.
584 * Presumably, calls to ntp_adjtime() occur only when the caller
585 * believes the local clock is valid within some bound (+-128 ms with
586 * NTP). If the caller's time is far different than the PPS time, an
587 * argument will ensue, and it's not clear who will lose.
588 *
589 * For uncompensated quartz crystal oscillators and nominal update
590 * intervals less than 256 s, operation should be in phase-lock mode,
591 * where the loop is disciplined to phase. For update intervals greater
592 * than 1024 s, operation should be in frequency-lock mode, where the
593 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
594 * is selected by the STA_MODE status bit.
595 */
596static void
597hardupdate(offset)
598 long offset; /* clock offset (ns) */
599{
600 long mtemp;
601 l_fp ftemp;
602
603 /*
604 * Select how the phase is to be controlled and from which
605 * source. If the PPS signal is present and enabled to
606 * discipline the time, the PPS offset is used; otherwise, the
607 * argument offset is used.
608 */
609 if (!(time_status & STA_PLL))
610 return;
611 if (!(time_status & STA_PPSTIME && time_status &
612 STA_PPSSIGNAL)) {
613 if (offset > MAXPHASE)
614 time_monitor = MAXPHASE;
615 else if (offset < -MAXPHASE)
616 time_monitor = -MAXPHASE;
617 else
618 time_monitor = offset;
619 L_LINT(time_offset, time_monitor);
620 }
621
622 /*
623 * Select how the frequency is to be controlled and in which
624 * mode (PLL or FLL). If the PPS signal is present and enabled
625 * to discipline the frequency, the PPS frequency is used;
626 * otherwise, the argument offset is used to compute it.
627 */
628 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {
629 time_reftime = time_second;
630 return;
631 }
632 if (time_status & STA_FREQHOLD || time_reftime == 0)
633 time_reftime = time_second;
634 mtemp = time_second - time_reftime;
635 L_LINT(ftemp, time_monitor);
636 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
637 L_MPY(ftemp, mtemp);
638 L_ADD(time_freq, ftemp);
639 time_status &= ~STA_MODE;
640 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
641 MAXSEC)) {
642 L_LINT(ftemp, (time_monitor << 4) / mtemp);
643 L_RSHIFT(ftemp, SHIFT_FLL + 4);
644 L_ADD(time_freq, ftemp);
645 time_status |= STA_MODE;
646 }
647 time_reftime = time_second;
648 if (L_GINT(time_freq) > MAXFREQ)
649 L_LINT(time_freq, MAXFREQ);
650 else if (L_GINT(time_freq) < -MAXFREQ)
651 L_LINT(time_freq, -MAXFREQ);
652}
653
654#ifdef PPS_SYNC
655/*
656 * hardpps() - discipline CPU clock oscillator to external PPS signal
657 *
658 * This routine is called at each PPS interrupt in order to discipline
659 * the CPU clock oscillator to the PPS signal. There are two independent
660 * first-order feedback loops, one for the phase, the other for the
661 * frequency. The phase loop measures and grooms the PPS phase offset
662 * and leaves it in a handy spot for the seconds overflow routine. The
663 * frequency loop averages successive PPS phase differences and
664 * calculates the PPS frequency offset, which is also processed by the
665 * seconds overflow routine. The code requires the caller to capture the
666 * time and architecture-dependent hardware counter values in
667 * nanoseconds at the on-time PPS signal transition.
668 *
669 * Note that, on some Unix systems this routine runs at an interrupt
670 * priority level higher than the timer interrupt routine hardclock().
671 * Therefore, the variables used are distinct from the hardclock()
672 * variables, except for the actual time and frequency variables, which
673 * are determined by this routine and updated atomically.
674 */
675void
676hardpps(tsp, nsec)
677 struct timespec *tsp; /* time at PPS */
678 long nsec; /* hardware counter at PPS */
679{
680 long u_sec, u_nsec, v_nsec; /* temps */
681 l_fp ftemp;
682
683 /*
684 * The signal is first processed by a range gate and frequency
685 * discriminator. The range gate rejects noise spikes outside
686 * the range +-500 us. The frequency discriminator rejects input
687 * signals with apparent frequency outside the range 1 +-500
688 * PPM. If two hits occur in the same second, we ignore the
689 * later hit; if not and a hit occurs outside the range gate,
690 * keep the later hit for later comparison, but do not process
691 * it.
692 */
693 time_status |= STA_PPSSIGNAL | STA_PPSJITTER;
694 time_status &= ~(STA_PPSWANDER | STA_PPSERROR);
695 pps_valid = PPS_VALID;
696 u_sec = tsp->tv_sec;
697 u_nsec = tsp->tv_nsec;
698 if (u_nsec >= (NANOSECOND >> 1)) {
699 u_nsec -= NANOSECOND;
700 u_sec++;
701 }
702 v_nsec = u_nsec - pps_tf[0].tv_nsec;
703 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND -
704 MAXFREQ)
705 return;
706 pps_tf[2] = pps_tf[1];
707 pps_tf[1] = pps_tf[0];
708 pps_tf[0].tv_sec = u_sec;
709 pps_tf[0].tv_nsec = u_nsec;
710
711 /*
712 * Compute the difference between the current and previous
713 * counter values. If the difference exceeds 0.5 s, assume it
714 * has wrapped around, so correct 1.0 s. If the result exceeds
715 * the tick interval, the sample point has crossed a tick
716 * boundary during the last second, so correct the tick. Very
717 * intricate.
718 */
719 u_nsec = nsec;
720 if (u_nsec > (NANOSECOND >> 1))
721 u_nsec -= NANOSECOND;
722 else if (u_nsec < -(NANOSECOND >> 1))
723 u_nsec += NANOSECOND;
724 pps_fcount += u_nsec;
725 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
726 return;
727 time_status &= ~STA_PPSJITTER;
728
729 /*
730 * A three-stage median filter is used to help denoise the PPS
731 * time. The median sample becomes the time offset estimate; the
732 * difference between the other two samples becomes the time
733 * dispersion (jitter) estimate.
734 */
735 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {
736 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {
737 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */
738 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;
739 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {
740 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */
741 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;
742 } else {
743 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */
744 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;
745 }
746 } else {
747 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {
748 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */
749 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;
750 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {
751 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */
752 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;
753 } else {
754 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */
755 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;
756 }
757 }
758
759 /*
760 * Nominal jitter is due to PPS signal noise and interrupt
761 * latency. If it exceeds the popcorn threshold, the sample is
762 * discarded. otherwise, if so enabled, the time offset is
763 * updated. We can tolerate a modest loss of data here without
764 * much degrading time accuracy.
765 */
766 if (u_nsec > (pps_jitter << PPS_POPCORN)) {
767 time_status |= STA_PPSJITTER;
768 pps_jitcnt++;
769 } else if (time_status & STA_PPSTIME) {
770 time_monitor = -v_nsec;
771 L_LINT(time_offset, time_monitor);
772 }
773 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;
774 u_sec = pps_tf[0].tv_sec - pps_lastsec;
775 if (u_sec < (1 << pps_shift))
776 return;
777
778 /*
779 * At the end of the calibration interval the difference between
780 * the first and last counter values becomes the scaled
781 * frequency. It will later be divided by the length of the
782 * interval to determine the frequency update. If the frequency
783 * exceeds a sanity threshold, or if the actual calibration
784 * interval is not equal to the expected length, the data are
785 * discarded. We can tolerate a modest loss of data here without
786 * much degrading frequency accuracy.
787 */
788 pps_calcnt++;
789 v_nsec = -pps_fcount;
790 pps_lastsec = pps_tf[0].tv_sec;
791 pps_fcount = 0;
792 u_nsec = MAXFREQ << pps_shift;
793 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 <<
794 pps_shift)) {
795 time_status |= STA_PPSERROR;
796 pps_errcnt++;
797 return;
798 }
799
800 /*
801 * Here the raw frequency offset and wander (stability) is
802 * calculated. If the wander is less than the wander threshold
803 * for four consecutive averaging intervals, the interval is
804 * doubled; if it is greater than the threshold for four
805 * consecutive intervals, the interval is halved. The scaled
806 * frequency offset is converted to frequency offset. The
807 * stability metric is calculated as the average of recent
808 * frequency changes, but is used only for performance
809 * monitoring.
810 */
811 L_LINT(ftemp, v_nsec);
812 L_RSHIFT(ftemp, pps_shift);
813 L_SUB(ftemp, pps_freq);
814 u_nsec = L_GINT(ftemp);
815 if (u_nsec > PPS_MAXWANDER) {
816 L_LINT(ftemp, PPS_MAXWANDER);
817 pps_intcnt--;
818 time_status |= STA_PPSWANDER;
819 pps_stbcnt++;
820 } else if (u_nsec < -PPS_MAXWANDER) {
821 L_LINT(ftemp, -PPS_MAXWANDER);
822 pps_intcnt--;
823 time_status |= STA_PPSWANDER;
824 pps_stbcnt++;
825 } else {
826 pps_intcnt++;
827 }
828 if (pps_intcnt >= 4) {
829 pps_intcnt = 4;
830 if (pps_shift < pps_shiftmax) {
831 pps_shift++;
832 pps_intcnt = 0;
833 }
834 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {
835 pps_intcnt = -4;
836 if (pps_shift > PPS_FAVG) {
837 pps_shift--;
838 pps_intcnt = 0;
839 }
840 }
841 if (u_nsec < 0)
842 u_nsec = -u_nsec;
843 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;
844
845 /*
846 * The PPS frequency is recalculated and clamped to the maximum
847 * MAXFREQ. If enabled, the system clock frequency is updated as
848 * well.
849 */
850 L_ADD(pps_freq, ftemp);
851 u_nsec = L_GINT(pps_freq);
852 if (u_nsec > MAXFREQ)
853 L_LINT(pps_freq, MAXFREQ);
854 else if (u_nsec < -MAXFREQ)
855 L_LINT(pps_freq, -MAXFREQ);
856 if (time_status & STA_PPSFREQ)
857 time_freq = pps_freq;
858}
859#endif /* PPS_SYNC */