1 /* $NetBSD: kern_ntptime.c,v 1.49 2008/04/28 20:24:03 martin Exp $ */
2
3 /*-
4 * Copyright (c) 2008 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 /*-
30 ***********************************************************************
31 * *
32 * Copyright (c) David L. Mills 1993-2001 *
33 * *
34 * Permission to use, copy, modify, and distribute this software and *
35 * its documentation for any purpose and without fee is hereby *
36 * granted, provided that the above copyright notice appears in all *
37 * copies and that both the copyright notice and this permission *
38 * notice appear in supporting documentation, and that the name *
39 * University of Delaware not be used in advertising or publicity *
40 * pertaining to distribution of the software without specific, *
41 * written prior permission. The University of Delaware makes no *
42 * representations about the suitability this software for any *
43 * purpose. It is provided "as is" without express or implied *
44 * warranty. *
45 * *
46 **********************************************************************/
47
48 /*
49 * Adapted from the original sources for FreeBSD and timecounters by:
50 * Poul-Henning Kamp <phk@FreeBSD.org>.
51 *
52 * The 32bit version of the "LP" macros seems a bit past its "sell by"
53 * date so I have retained only the 64bit version and included it directly
54 * in this file.
55 *
56 * Only minor changes done to interface with the timecounters over in
57 * sys/kern/kern_clock.c. Some of the comments below may be (even more)
58 * confusing and/or plain wrong in that context.
59 */
60
61 #include <sys/cdefs.h>
62 /* __FBSDID("$FreeBSD: src/sys/kern/kern_ntptime.c,v 1.59 2005/05/28 14:34:41 rwatson Exp $"); */
63 __KERNEL_RCSID(0, "$NetBSD: kern_ntptime.c,v 1.49 2008/04/28 20:24:03 martin Exp $");
64
65 #include "opt_ntp.h"
66 #include "opt_compat_netbsd.h"
67
68 #include <sys/param.h>
69 #include <sys/resourcevar.h>
70 #include <sys/systm.h>
71 #include <sys/kernel.h>
72 #include <sys/proc.h>
73 #include <sys/sysctl.h>
74 #include <sys/timex.h>
75 #include <sys/vnode.h>
76 #include <sys/kauth.h>
77 #include <sys/mount.h>
78 #include <sys/syscallargs.h>
79 #include <sys/cpu.h>
80
81 #ifdef COMPAT_30
82 #include <compat/sys/timex.h>
83 #endif
84
85 /*
86 * Single-precision macros for 64-bit machines
87 */
88 typedef int64_t l_fp;
89 #define L_ADD(v, u) ((v) += (u))
90 #define L_SUB(v, u) ((v) -= (u))
91 #define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32)
92 #define L_NEG(v) ((v) = -(v))
93 #define L_RSHIFT(v, n) \
94 do { \
95 if ((v) < 0) \
96 (v) = -(-(v) >> (n)); \
97 else \
98 (v) = (v) >> (n); \
99 } while (0)
100 #define L_MPY(v, a) ((v) *= (a))
101 #define L_CLR(v) ((v) = 0)
102 #define L_ISNEG(v) ((v) < 0)
103 #define L_LINT(v, a) ((v) = (int64_t)(a) << 32)
104 #define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32)
105
106 #ifdef NTP
107 /*
108 * Generic NTP kernel interface
109 *
110 * These routines constitute the Network Time Protocol (NTP) interfaces
111 * for user and daemon application programs. The ntp_gettime() routine
112 * provides the time, maximum error (synch distance) and estimated error
113 * (dispersion) to client user application programs. The ntp_adjtime()
114 * routine is used by the NTP daemon to adjust the system clock to an
115 * externally derived time. The time offset and related variables set by
116 * this routine are used by other routines in this module to adjust the
117 * phase and frequency of the clock discipline loop which controls the
118 * system clock.
119 *
120 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO
121 * defined), the time at each tick interrupt is derived directly from
122 * the kernel time variable. When the kernel time is reckoned in
123 * microseconds, (NTP_NANO undefined), the time is derived from the
124 * kernel time variable together with a variable representing the
125 * leftover nanoseconds at the last tick interrupt. In either case, the
126 * current nanosecond time is reckoned from these values plus an
127 * interpolated value derived by the clock routines in another
128 * architecture-specific module. The interpolation can use either a
129 * dedicated counter or a processor cycle counter (PCC) implemented in
130 * some architectures.
131 *
132 * Note that all routines must run at priority splclock or higher.
133 */
134 /*
135 * Phase/frequency-lock loop (PLL/FLL) definitions
136 *
137 * The nanosecond clock discipline uses two variable types, time
138 * variables and frequency variables. Both types are represented as 64-
139 * bit fixed-point quantities with the decimal point between two 32-bit
140 * halves. On a 32-bit machine, each half is represented as a single
141 * word and mathematical operations are done using multiple-precision
142 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is
143 * used.
144 *
145 * A time variable is a signed 64-bit fixed-point number in ns and
146 * fraction. It represents the remaining time offset to be amortized
147 * over succeeding tick interrupts. The maximum time offset is about
148 * 0.5 s and the resolution is about 2.3e-10 ns.
149 *
150 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
151 * 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
152 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
153 * |s s s| ns |
154 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
155 * | fraction |
156 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
157 *
158 * A frequency variable is a signed 64-bit fixed-point number in ns/s
159 * and fraction. It represents the ns and fraction to be added to the
160 * kernel time variable at each second. The maximum frequency offset is
161 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s.
162 *
163 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
164 * 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
165 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
166 * |s s s s s s s s s s s s s| ns/s |
167 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
168 * | fraction |
169 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
170 */
171 /*
172 * The following variables establish the state of the PLL/FLL and the
173 * residual time and frequency offset of the local clock.
174 */
175 #define SHIFT_PLL 4 /* PLL loop gain (shift) */
176 #define SHIFT_FLL 2 /* FLL loop gain (shift) */
177
178 static int time_state = TIME_OK; /* clock state */
179 static int time_status = STA_UNSYNC; /* clock status bits */
180 static long time_tai; /* TAI offset (s) */
181 static long time_monitor; /* last time offset scaled (ns) */
182 static long time_constant; /* poll interval (shift) (s) */
183 static long time_precision = 1; /* clock precision (ns) */
184 static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */
185 static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */
186 static long time_reftime; /* time at last adjustment (s) */
187 static l_fp time_offset; /* time offset (ns) */
188 static l_fp time_freq; /* frequency offset (ns/s) */
189 #endif /* NTP */
190
191 static l_fp time_adj; /* tick adjust (ns/s) */
192 int64_t time_adjtime; /* correction from adjtime(2) (usec) */
193
194 extern int time_adjusted; /* ntp might have changed the system time */
195
196 #ifdef NTP
197 #ifdef PPS_SYNC
198 /*
199 * The following variables are used when a pulse-per-second (PPS) signal
200 * is available and connected via a modem control lead. They establish
201 * the engineering parameters of the clock discipline loop when
202 * controlled by the PPS signal.
203 */
204 #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */
205 #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */
206 #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */
207 #define PPS_PAVG 4 /* phase avg interval (s) (shift) */
208 #define PPS_VALID 120 /* PPS signal watchdog max (s) */
209 #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */
210 #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */
211
212 static struct timespec pps_tf[3]; /* phase median filter */
213 static l_fp pps_freq; /* scaled frequency offset (ns/s) */
214 static long pps_fcount; /* frequency accumulator */
215 static long pps_jitter; /* nominal jitter (ns) */
216 static long pps_stabil; /* nominal stability (scaled ns/s) */
217 static long pps_lastsec; /* time at last calibration (s) */
218 static int pps_valid; /* signal watchdog counter */
219 static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */
220 static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */
221 static int pps_intcnt; /* wander counter */
222
223 /*
224 * PPS signal quality monitors
225 */
226 static long pps_calcnt; /* calibration intervals */
227 static long pps_jitcnt; /* jitter limit exceeded */
228 static long pps_stbcnt; /* stability limit exceeded */
229 static long pps_errcnt; /* calibration errors */
230 #endif /* PPS_SYNC */
231 /*
232 * End of phase/frequency-lock loop (PLL/FLL) definitions
233 */
234
235 static void hardupdate(long offset);
236
237 /*
238 * ntp_gettime() - NTP user application interface
239 */
240 void
241 ntp_gettime(struct ntptimeval *ntv)
242 {
243
244 mutex_spin_enter(&timecounter_lock);
245 nanotime(&ntv->time);
246 ntv->maxerror = time_maxerror;
247 ntv->esterror = time_esterror;
248 ntv->tai = time_tai;
249 ntv->time_state = time_state;
250 mutex_spin_exit(&timecounter_lock);
251 }
252
253 /* ARGSUSED */
254 /*
255 * ntp_adjtime() - NTP daemon application interface
256 */
257 int
258 sys_ntp_adjtime(struct lwp *l, const struct sys_ntp_adjtime_args *uap, register_t *retval)
259 {
260 /* {
261 syscallarg(struct timex *) tp;
262 } */
263 struct timex ntv;
264 int error = 0;
265
266 error = copyin((void *)SCARG(uap, tp), (void *)&ntv, sizeof(ntv));
267 if (error != 0)
268 return (error);
269
270 if (ntv.modes != 0 && (error = kauth_authorize_system(l->l_cred,
271 KAUTH_SYSTEM_TIME, KAUTH_REQ_SYSTEM_TIME_NTPADJTIME, NULL,
272 NULL, NULL)) != 0)
273 return (error);
274
275 ntp_adjtime1(&ntv);
276
277 error = copyout((void *)&ntv, (void *)SCARG(uap, tp), sizeof(ntv));
278 if (!error)
279 *retval = ntp_timestatus();
280
281 return error;
282 }
283
284 void
285 ntp_adjtime1(struct timex *ntv)
286 {
287 long freq;
288 int modes;
289
290 /*
291 * Update selected clock variables - only the superuser can
292 * change anything. Note that there is no error checking here on
293 * the assumption the superuser should know what it is doing.
294 * Note that either the time constant or TAI offset are loaded
295 * from the ntv.constant member, depending on the mode bits. If
296 * the STA_PLL bit in the status word is cleared, the state and
297 * status words are reset to the initial values at boot.
298 */
299 mutex_spin_enter(&timecounter_lock);
300 modes = ntv->modes;
301 if (modes != 0)
302 /* We need to save the system time during shutdown */
303 time_adjusted |= 2;
304 if (modes & MOD_MAXERROR)
305 time_maxerror = ntv->maxerror;
306 if (modes & MOD_ESTERROR)
307 time_esterror = ntv->esterror;
308 if (modes & MOD_STATUS) {
309 if (time_status & STA_PLL && !(ntv->status & STA_PLL)) {
310 time_state = TIME_OK;
311 time_status = STA_UNSYNC;
312 #ifdef PPS_SYNC
313 pps_shift = PPS_FAVG;
314 #endif /* PPS_SYNC */
315 }
316 time_status &= STA_RONLY;
317 time_status |= ntv->status & ~STA_RONLY;
318 }
319 if (modes & MOD_TIMECONST) {
320 if (ntv->constant < 0)
321 time_constant = 0;
322 else if (ntv->constant > MAXTC)
323 time_constant = MAXTC;
324 else
325 time_constant = ntv->constant;
326 }
327 if (modes & MOD_TAI) {
328 if (ntv->constant > 0) /* XXX zero & negative numbers ? */
329 time_tai = ntv->constant;
330 }
331 #ifdef PPS_SYNC
332 if (modes & MOD_PPSMAX) {
333 if (ntv->shift < PPS_FAVG)
334 pps_shiftmax = PPS_FAVG;
335 else if (ntv->shift > PPS_FAVGMAX)
336 pps_shiftmax = PPS_FAVGMAX;
337 else
338 pps_shiftmax = ntv->shift;
339 }
340 #endif /* PPS_SYNC */
341 if (modes & MOD_NANO)
342 time_status |= STA_NANO;
343 if (modes & MOD_MICRO)
344 time_status &= ~STA_NANO;
345 if (modes & MOD_CLKB)
346 time_status |= STA_CLK;
347 if (modes & MOD_CLKA)
348 time_status &= ~STA_CLK;
349 if (modes & MOD_FREQUENCY) {
350 freq = (ntv->freq * 1000LL) >> 16;
351 if (freq > MAXFREQ)
352 L_LINT(time_freq, MAXFREQ);
353 else if (freq < -MAXFREQ)
354 L_LINT(time_freq, -MAXFREQ);
355 else {
356 /*
357 * ntv.freq is [PPM * 2^16] = [us/s * 2^16]
358 * time_freq is [ns/s * 2^32]
359 */
360 time_freq = ntv->freq * 1000LL * 65536LL;
361 }
362 #ifdef PPS_SYNC
363 pps_freq = time_freq;
364 #endif /* PPS_SYNC */
365 }
366 if (modes & MOD_OFFSET) {
367 if (time_status & STA_NANO)
368 hardupdate(ntv->offset);
369 else
370 hardupdate(ntv->offset * 1000);
371 }
372
373 /*
374 * Retrieve all clock variables. Note that the TAI offset is
375 * returned only by ntp_gettime();
376 */
377 if (time_status & STA_NANO)
378 ntv->offset = L_GINT(time_offset);
379 else
380 ntv->offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */
381 ntv->freq = L_GINT((time_freq / 1000LL) << 16);
382 ntv->maxerror = time_maxerror;
383 ntv->esterror = time_esterror;
384 ntv->status = time_status;
385 ntv->constant = time_constant;
386 if (time_status & STA_NANO)
387 ntv->precision = time_precision;
388 else
389 ntv->precision = time_precision / 1000;
390 ntv->tolerance = MAXFREQ * SCALE_PPM;
391 #ifdef PPS_SYNC
392 ntv->shift = pps_shift;
393 ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16);
394 if (time_status & STA_NANO)
395 ntv->jitter = pps_jitter;
396 else
397 ntv->jitter = pps_jitter / 1000;
398 ntv->stabil = pps_stabil;
399 ntv->calcnt = pps_calcnt;
400 ntv->errcnt = pps_errcnt;
401 ntv->jitcnt = pps_jitcnt;
402 ntv->stbcnt = pps_stbcnt;
403 #endif /* PPS_SYNC */
404 mutex_spin_exit(&timecounter_lock);
405 }
406 #endif /* NTP */
407
408 /*
409 * second_overflow() - called after ntp_tick_adjust()
410 *
411 * This routine is ordinarily called immediately following the above
412 * routine ntp_tick_adjust(). While these two routines are normally
413 * combined, they are separated here only for the purposes of
414 * simulation.
415 */
416 void
417 ntp_update_second(int64_t *adjustment, time_t *newsec)
418 {
419 int tickrate;
420 l_fp ftemp; /* 32/64-bit temporary */
421
422 KASSERT(mutex_owned(&timecounter_lock));
423
424 #ifdef NTP
425
426 /*
427 * On rollover of the second both the nanosecond and microsecond
428 * clocks are updated and the state machine cranked as
429 * necessary. The phase adjustment to be used for the next
430 * second is calculated and the maximum error is increased by
431 * the tolerance.
432 */
433 time_maxerror += MAXFREQ / 1000;
434
435 /*
436 * Leap second processing. If in leap-insert state at
437 * the end of the day, the system clock is set back one
438 * second; if in leap-delete state, the system clock is
439 * set ahead one second. The nano_time() routine or
440 * external clock driver will insure that reported time
441 * is always monotonic.
442 */
443 switch (time_state) {
444
445 /*
446 * No warning.
447 */
448 case TIME_OK:
449 if (time_status & STA_INS)
450 time_state = TIME_INS;
451 else if (time_status & STA_DEL)
452 time_state = TIME_DEL;
453 break;
454
455 /*
456 * Insert second 23:59:60 following second
457 * 23:59:59.
458 */
459 case TIME_INS:
460 if (!(time_status & STA_INS))
461 time_state = TIME_OK;
462 else if ((*newsec) % 86400 == 0) {
463 (*newsec)--;
464 time_state = TIME_OOP;
465 time_tai++;
466 }
467 break;
468
469 /*
470 * Delete second 23:59:59.
471 */
472 case TIME_DEL:
473 if (!(time_status & STA_DEL))
474 time_state = TIME_OK;
475 else if (((*newsec) + 1) % 86400 == 0) {
476 (*newsec)++;
477 time_tai--;
478 time_state = TIME_WAIT;
479 }
480 break;
481
482 /*
483 * Insert second in progress.
484 */
485 case TIME_OOP:
486 time_state = TIME_WAIT;
487 break;
488
489 /*
490 * Wait for status bits to clear.
491 */
492 case TIME_WAIT:
493 if (!(time_status & (STA_INS | STA_DEL)))
494 time_state = TIME_OK;
495 }
496
497 /*
498 * Compute the total time adjustment for the next second
499 * in ns. The offset is reduced by a factor depending on
500 * whether the PPS signal is operating. Note that the
501 * value is in effect scaled by the clock frequency,
502 * since the adjustment is added at each tick interrupt.
503 */
504 ftemp = time_offset;
505 #ifdef PPS_SYNC
506 /* XXX even if PPS signal dies we should finish adjustment ? */
507 if (time_status & STA_PPSTIME && time_status &
508 STA_PPSSIGNAL)
509 L_RSHIFT(ftemp, pps_shift);
510 else
511 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
512 #else
513 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
514 #endif /* PPS_SYNC */
515 time_adj = ftemp;
516 L_SUB(time_offset, ftemp);
517 L_ADD(time_adj, time_freq);
518
519 #ifdef PPS_SYNC
520 if (pps_valid > 0)
521 pps_valid--;
522 else
523 time_status &= ~STA_PPSSIGNAL;
524 #endif /* PPS_SYNC */
525 #else /* !NTP */
526 L_CLR(time_adj);
527 #endif /* !NTP */
528
529 /*
530 * Apply any correction from adjtime(2). If more than one second
531 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM)
532 * until the last second is slewed the final < 500 usecs.
533 */
534 if (time_adjtime != 0) {
535 if (time_adjtime > 1000000)
536 tickrate = 5000;
537 else if (time_adjtime < -1000000)
538 tickrate = -5000;
539 else if (time_adjtime > 500)
540 tickrate = 500;
541 else if (time_adjtime < -500)
542 tickrate = -500;
543 else
544 tickrate = time_adjtime;
545 time_adjtime -= tickrate;
546 L_LINT(ftemp, tickrate * 1000);
547 L_ADD(time_adj, ftemp);
548 }
549 *adjustment = time_adj;
550 }
551
552 /*
553 * ntp_init() - initialize variables and structures
554 *
555 * This routine must be called after the kernel variables hz and tick
556 * are set or changed and before the next tick interrupt. In this
557 * particular implementation, these values are assumed set elsewhere in
558 * the kernel. The design allows the clock frequency and tick interval
559 * to be changed while the system is running. So, this routine should
560 * probably be integrated with the code that does that.
561 */
562 void
563 ntp_init(void)
564 {
565
566 /*
567 * The following variables are initialized only at startup. Only
568 * those structures not cleared by the compiler need to be
569 * initialized, and these only in the simulator. In the actual
570 * kernel, any nonzero values here will quickly evaporate.
571 */
572 L_CLR(time_adj);
573 #ifdef NTP
574 L_CLR(time_offset);
575 L_CLR(time_freq);
576 #ifdef PPS_SYNC
577 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;
578 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;
579 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;
580 pps_fcount = 0;
581 L_CLR(pps_freq);
582 #endif /* PPS_SYNC */
583 #endif
584 }
585
586 #ifdef NTP
587 /*
588 * hardupdate() - local clock update
589 *
590 * This routine is called by ntp_adjtime() to update the local clock
591 * phase and frequency. The implementation is of an adaptive-parameter,
592 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
593 * time and frequency offset estimates for each call. If the kernel PPS
594 * discipline code is configured (PPS_SYNC), the PPS signal itself
595 * determines the new time offset, instead of the calling argument.
596 * Presumably, calls to ntp_adjtime() occur only when the caller
597 * believes the local clock is valid within some bound (+-128 ms with
598 * NTP). If the caller's time is far different than the PPS time, an
599 * argument will ensue, and it's not clear who will lose.
600 *
601 * For uncompensated quartz crystal oscillators and nominal update
602 * intervals less than 256 s, operation should be in phase-lock mode,
603 * where the loop is disciplined to phase. For update intervals greater
604 * than 1024 s, operation should be in frequency-lock mode, where the
605 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
606 * is selected by the STA_MODE status bit.
607 *
608 * Note: splclock() is in effect.
609 */
610 void
611 hardupdate(long offset)
612 {
613 long mtemp;
614 l_fp ftemp;
615
616 KASSERT(mutex_owned(&timecounter_lock));
617
618 /*
619 * Select how the phase is to be controlled and from which
620 * source. If the PPS signal is present and enabled to
621 * discipline the time, the PPS offset is used; otherwise, the
622 * argument offset is used.
623 */
624 if (!(time_status & STA_PLL))
625 return;
626 if (!(time_status & STA_PPSTIME && time_status &
627 STA_PPSSIGNAL)) {
628 if (offset > MAXPHASE)
629 time_monitor = MAXPHASE;
630 else if (offset < -MAXPHASE)
631 time_monitor = -MAXPHASE;
632 else
633 time_monitor = offset;
634 L_LINT(time_offset, time_monitor);
635 }
636
637 /*
638 * Select how the frequency is to be controlled and in which
639 * mode (PLL or FLL). If the PPS signal is present and enabled
640 * to discipline the frequency, the PPS frequency is used;
641 * otherwise, the argument offset is used to compute it.
642 */
643 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {
644 time_reftime = time_second;
645 return;
646 }
647 if (time_status & STA_FREQHOLD || time_reftime == 0)
648 time_reftime = time_second;
649 mtemp = time_second - time_reftime;
650 L_LINT(ftemp, time_monitor);
651 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
652 L_MPY(ftemp, mtemp);
653 L_ADD(time_freq, ftemp);
654 time_status &= ~STA_MODE;
655 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
656 MAXSEC)) {
657 L_LINT(ftemp, (time_monitor << 4) / mtemp);
658 L_RSHIFT(ftemp, SHIFT_FLL + 4);
659 L_ADD(time_freq, ftemp);
660 time_status |= STA_MODE;
661 }
662 time_reftime = time_second;
663 if (L_GINT(time_freq) > MAXFREQ)
664 L_LINT(time_freq, MAXFREQ);
665 else if (L_GINT(time_freq) < -MAXFREQ)
666 L_LINT(time_freq, -MAXFREQ);
667 }
668
669 #ifdef PPS_SYNC
670 /*
671 * hardpps() - discipline CPU clock oscillator to external PPS signal
672 *
673 * This routine is called at each PPS interrupt in order to discipline
674 * the CPU clock oscillator to the PPS signal. It measures the PPS phase
675 * and leaves it in a handy spot for the hardclock() routine. It
676 * integrates successive PPS phase differences and calculates the
677 * frequency offset. This is used in hardclock() to discipline the CPU
678 * clock oscillator so that intrinsic frequency error is cancelled out.
679 * The code requires the caller to capture the time and hardware counter
680 * value at the on-time PPS signal transition.
681 *
682 * Note that, on some Unix systems, this routine runs at an interrupt
683 * priority level higher than the timer interrupt routine hardclock().
684 * Therefore, the variables used are distinct from the hardclock()
685 * variables, except for certain exceptions: The PPS frequency pps_freq
686 * and phase pps_offset variables are determined by this routine and
687 * updated atomically. The time_tolerance variable can be considered a
688 * constant, since it is infrequently changed, and then only when the
689 * PPS signal is disabled. The watchdog counter pps_valid is updated
690 * once per second by hardclock() and is atomically cleared in this
691 * routine.
692 */
693 void
694 hardpps(struct timespec *tsp, /* time at PPS */
695 long nsec /* hardware counter at PPS */)
696 {
697 long u_sec, u_nsec, v_nsec; /* temps */
698 l_fp ftemp;
699
700 KASSERT(mutex_owned(&timecounter_lock));
701
702 /*
703 * The signal is first processed by a range gate and frequency
704 * discriminator. The range gate rejects noise spikes outside
705 * the range +-500 us. The frequency discriminator rejects input
706 * signals with apparent frequency outside the range 1 +-500
707 * PPM. If two hits occur in the same second, we ignore the
708 * later hit; if not and a hit occurs outside the range gate,
709 * keep the later hit for later comparison, but do not process
710 * it.
711 */
712 time_status |= STA_PPSSIGNAL | STA_PPSJITTER;
713 time_status &= ~(STA_PPSWANDER | STA_PPSERROR);
714 pps_valid = PPS_VALID;
715 u_sec = tsp->tv_sec;
716 u_nsec = tsp->tv_nsec;
717 if (u_nsec >= (NANOSECOND >> 1)) {
718 u_nsec -= NANOSECOND;
719 u_sec++;
720 }
721 v_nsec = u_nsec - pps_tf[0].tv_nsec;
722 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND -
723 MAXFREQ)
724 return;
725 pps_tf[2] = pps_tf[1];
726 pps_tf[1] = pps_tf[0];
727 pps_tf[0].tv_sec = u_sec;
728 pps_tf[0].tv_nsec = u_nsec;
729
730 /*
731 * Compute the difference between the current and previous
732 * counter values. If the difference exceeds 0.5 s, assume it
733 * has wrapped around, so correct 1.0 s. If the result exceeds
734 * the tick interval, the sample point has crossed a tick
735 * boundary during the last second, so correct the tick. Very
736 * intricate.
737 */
738 u_nsec = nsec;
739 if (u_nsec > (NANOSECOND >> 1))
740 u_nsec -= NANOSECOND;
741 else if (u_nsec < -(NANOSECOND >> 1))
742 u_nsec += NANOSECOND;
743 pps_fcount += u_nsec;
744 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
745 return;
746 time_status &= ~STA_PPSJITTER;
747
748 /*
749 * A three-stage median filter is used to help denoise the PPS
750 * time. The median sample becomes the time offset estimate; the
751 * difference between the other two samples becomes the time
752 * dispersion (jitter) estimate.
753 */
754 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {
755 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {
756 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */
757 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;
758 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {
759 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */
760 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;
761 } else {
762 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */
763 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;
764 }
765 } else {
766 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {
767 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */
768 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;
769 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {
770 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */
771 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;
772 } else {
773 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */
774 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;
775 }
776 }
777
778 /*
779 * Nominal jitter is due to PPS signal noise and interrupt
780 * latency. If it exceeds the popcorn threshold, the sample is
781 * discarded. otherwise, if so enabled, the time offset is
782 * updated. We can tolerate a modest loss of data here without
783 * much degrading time accuracy.
784 */
785 if (u_nsec > (pps_jitter << PPS_POPCORN)) {
786 time_status |= STA_PPSJITTER;
787 pps_jitcnt++;
788 } else if (time_status & STA_PPSTIME) {
789 time_monitor = -v_nsec;
790 L_LINT(time_offset, time_monitor);
791 }
792 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;
793 u_sec = pps_tf[0].tv_sec - pps_lastsec;
794 if (u_sec < (1 << pps_shift))
795 return;
796
797 /*
798 * At the end of the calibration interval the difference between
799 * the first and last counter values becomes the scaled
800 * frequency. It will later be divided by the length of the
801 * interval to determine the frequency update. If the frequency
802 * exceeds a sanity threshold, or if the actual calibration
803 * interval is not equal to the expected length, the data are
804 * discarded. We can tolerate a modest loss of data here without
805 * much degrading frequency accuracy.
806 */
807 pps_calcnt++;
808 v_nsec = -pps_fcount;
809 pps_lastsec = pps_tf[0].tv_sec;
810 pps_fcount = 0;
811 u_nsec = MAXFREQ << pps_shift;
812 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 <<
813 pps_shift)) {
814 time_status |= STA_PPSERROR;
815 pps_errcnt++;
816 return;
817 }
818
819 /*
820 * Here the raw frequency offset and wander (stability) is
821 * calculated. If the wander is less than the wander threshold
822 * for four consecutive averaging intervals, the interval is
823 * doubled; if it is greater than the threshold for four
824 * consecutive intervals, the interval is halved. The scaled
825 * frequency offset is converted to frequency offset. The
826 * stability metric is calculated as the average of recent
827 * frequency changes, but is used only for performance
828 * monitoring.
829 */
830 L_LINT(ftemp, v_nsec);
831 L_RSHIFT(ftemp, pps_shift);
832 L_SUB(ftemp, pps_freq);
833 u_nsec = L_GINT(ftemp);
834 if (u_nsec > PPS_MAXWANDER) {
835 L_LINT(ftemp, PPS_MAXWANDER);
836 pps_intcnt--;
837 time_status |= STA_PPSWANDER;
838 pps_stbcnt++;
839 } else if (u_nsec < -PPS_MAXWANDER) {
840 L_LINT(ftemp, -PPS_MAXWANDER);
841 pps_intcnt--;
842 time_status |= STA_PPSWANDER;
843 pps_stbcnt++;
844 } else {
845 pps_intcnt++;
846 }
847 if (pps_intcnt >= 4) {
848 pps_intcnt = 4;
849 if (pps_shift < pps_shiftmax) {
850 pps_shift++;
851 pps_intcnt = 0;
852 }
853 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {
854 pps_intcnt = -4;
855 if (pps_shift > PPS_FAVG) {
856 pps_shift--;
857 pps_intcnt = 0;
858 }
859 }
860 if (u_nsec < 0)
861 u_nsec = -u_nsec;
862 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;
863
864 /*
865 * The PPS frequency is recalculated and clamped to the maximum
866 * MAXFREQ. If enabled, the system clock frequency is updated as
867 * well.
868 */
869 L_ADD(pps_freq, ftemp);
870 u_nsec = L_GINT(pps_freq);
871 if (u_nsec > MAXFREQ)
872 L_LINT(pps_freq, MAXFREQ);
873 else if (u_nsec < -MAXFREQ)
874 L_LINT(pps_freq, -MAXFREQ);
875 if (time_status & STA_PPSFREQ)
876 time_freq = pps_freq;
877 }
878 #endif /* PPS_SYNC */
879 #endif /* NTP */
880
881 #ifdef NTP
882 int
883 ntp_timestatus(void)
884 {
885 int rv;
886
887 /*
888 * Status word error decode. If any of these conditions
889 * occur, an error is returned, instead of the status
890 * word. Most applications will care only about the fact
891 * the system clock may not be trusted, not about the
892 * details.
893 *
894 * Hardware or software error
895 */
896 mutex_spin_enter(&timecounter_lock);
897 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||
898
899 /*
900 * PPS signal lost when either time or frequency
901 * synchronization requested
902 */
903 (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
904 !(time_status & STA_PPSSIGNAL)) ||
905
906 /*
907 * PPS jitter exceeded when time synchronization
908 * requested
909 */
910 (time_status & STA_PPSTIME &&
911 time_status & STA_PPSJITTER) ||
912
913 /*
914 * PPS wander exceeded or calibration error when
915 * frequency synchronization requested
916 */
917 (time_status & STA_PPSFREQ &&
918 time_status & (STA_PPSWANDER | STA_PPSERROR)))
919 rv = TIME_ERROR;
920 else
921 rv = time_state;
922 mutex_spin_exit(&timecounter_lock);
923
924 return rv;
925 }
926
927 /*ARGSUSED*/
928 /*
929 * ntp_gettime() - NTP user application interface
930 */
931 int
932 sys___ntp_gettime30(struct lwp *l, const struct sys___ntp_gettime30_args *uap, register_t *retval)
933 {
934 /* {
935 syscallarg(struct ntptimeval *) ntvp;
936 } */
937 struct ntptimeval ntv;
938 int error = 0;
939
940 if (SCARG(uap, ntvp)) {
941 ntp_gettime(&ntv);
942
943 error = copyout((void *)&ntv, (void *)SCARG(uap, ntvp),
944 sizeof(ntv));
945 }
946 if (!error) {
947 *retval = ntp_timestatus();
948 }
949 return(error);
950 }
951
952 #ifdef COMPAT_30
953 int
954 compat_30_sys_ntp_gettime(struct lwp *l, const struct compat_30_sys_ntp_gettime_args *uap, register_t *retval)
955 {
956 /* {
957 syscallarg(struct ntptimeval30 *) ontvp;
958 } */
959 struct ntptimeval ntv;
960 struct ntptimeval30 ontv;
961 int error = 0;
962
963 if (SCARG(uap, ntvp)) {
964 ntp_gettime(&ntv);
965 TIMESPEC_TO_TIMEVAL(&ontv.time, &ntv.time);
966 ontv.maxerror = ntv.maxerror;
967 ontv.esterror = ntv.esterror;
968
969 error = copyout((void *)&ontv, (void *)SCARG(uap, ntvp),
970 sizeof(ontv));
971 }
972 if (!error)
973 *retval = ntp_timestatus();
974
975 return (error);
976 }
977 #endif
978
979 /*
980 * return information about kernel precision timekeeping
981 */
982 static int
983 sysctl_kern_ntptime(SYSCTLFN_ARGS)
984 {
985 struct sysctlnode node;
986 struct ntptimeval ntv;
987
988 ntp_gettime(&ntv);
989
990 node = *rnode;
991 node.sysctl_data = &ntv;
992 node.sysctl_size = sizeof(ntv);
993 return (sysctl_lookup(SYSCTLFN_CALL(&node)));
994 }
995
996 SYSCTL_SETUP(sysctl_kern_ntptime_setup, "sysctl kern.ntptime node setup")
997 {
998
999 sysctl_createv(clog, 0, NULL, NULL,
1000 CTLFLAG_PERMANENT,
1001 CTLTYPE_NODE, "kern", NULL,
1002 NULL, 0, NULL, 0,
1003 CTL_KERN, CTL_EOL);
1004
1005 sysctl_createv(clog, 0, NULL, NULL,
1006 CTLFLAG_PERMANENT,
1007 CTLTYPE_STRUCT, "ntptime",
1008 SYSCTL_DESCR("Kernel clock values for NTP"),
1009 sysctl_kern_ntptime, 0, NULL,
1010 sizeof(struct ntptimeval),
1011 CTL_KERN, KERN_NTPTIME, CTL_EOL);
1012 }
1013 #else /* !NTP */
1014 /* For some reason, raising SIGSYS (as sys_nosys would) is problematic. */
1015
1016 int
1017 sys___ntp_gettime30(struct lwp *l, const struct sys___ntp_gettime30_args *uap, register_t *retval)
1018 {
1019
1020 return(ENOSYS);
1021 }
1022
1023 #ifdef COMPAT_30
1024 int
1025 compat_30_sys_ntp_gettime(struct lwp *l, const struct compat_30_sys_ntp_gettime_args *uap, register_t *retval)
1026 {
1027
1028 return(ENOSYS);
1029 }
1030 #endif
1031 #endif /* !NTP */
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