priv: Narrow down privileges
[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 $
ba39e2e0 32 * $DragonFly: src/sys/kern/kern_ntptime.c,v 1.13 2007/04/30 07:18:53 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>
895c1f85 42#include <sys/priv.h>
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43#include <sys/time.h>
44#include <sys/timex.h>
45#include <sys/timepps.h>
46#include <sys/sysctl.h>
88c4d2f6 47#include <sys/thread2.h>
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48
49/*
50 * Single-precision macros for 64-bit machines
51 */
52typedef long long l_fp;
53#define L_ADD(v, u) ((v) += (u))
54#define L_SUB(v, u) ((v) -= (u))
55#define L_ADDHI(v, a) ((v) += (long long)(a) << 32)
56#define L_NEG(v) ((v) = -(v))
57#define L_RSHIFT(v, n) \
58 do { \
59 if ((v) < 0) \
60 (v) = -(-(v) >> (n)); \
61 else \
62 (v) = (v) >> (n); \
63 } while (0)
64#define L_MPY(v, a) ((v) *= (a))
65#define L_CLR(v) ((v) = 0)
66#define L_ISNEG(v) ((v) < 0)
67#define L_LINT(v, a) ((v) = (long long)(a) << 32)
68#define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32)
69
70/*
71 * Generic NTP kernel interface
72 *
73 * These routines constitute the Network Time Protocol (NTP) interfaces
74 * for user and daemon application programs. The ntp_gettime() routine
75 * provides the time, maximum error (synch distance) and estimated error
76 * (dispersion) to client user application programs. The ntp_adjtime()
77 * routine is used by the NTP daemon to adjust the system clock to an
78 * externally derived time. The time offset and related variables set by
79 * this routine are used by other routines in this module to adjust the
80 * phase and frequency of the clock discipline loop which controls the
81 * system clock.
82 *
83 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO
84 * defined), the time at each tick interrupt is derived directly from
85 * the kernel time variable. When the kernel time is reckoned in
86 * microseconds, (NTP_NANO undefined), the time is derived from the
87 * kernel time variable together with a variable representing the
88 * leftover nanoseconds at the last tick interrupt. In either case, the
89 * current nanosecond time is reckoned from these values plus an
90 * interpolated value derived by the clock routines in another
91 * architecture-specific module. The interpolation can use either a
92 * dedicated counter or a processor cycle counter (PCC) implemented in
93 * some architectures.
94 *
95 * Note that all routines must run at priority splclock or higher.
96 */
97/*
98 * Phase/frequency-lock loop (PLL/FLL) definitions
99 *
100 * The nanosecond clock discipline uses two variable types, time
101 * variables and frequency variables. Both types are represented as 64-
102 * bit fixed-point quantities with the decimal point between two 32-bit
103 * halves. On a 32-bit machine, each half is represented as a single
104 * word and mathematical operations are done using multiple-precision
105 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is
106 * used.
107 *
108 * A time variable is a signed 64-bit fixed-point number in ns and
109 * fraction. It represents the remaining time offset to be amortized
110 * over succeeding tick interrupts. The maximum time offset is about
111 * 0.5 s and the resolution is about 2.3e-10 ns.
112 *
113 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
114 * 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
115 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
116 * |s s s| ns |
117 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
118 * | fraction |
119 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
120 *
121 * A frequency variable is a signed 64-bit fixed-point number in ns/s
122 * and fraction. It represents the ns and fraction to be added to the
123 * kernel time variable at each second. The maximum frequency offset is
124 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s.
125 *
126 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
127 * 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
128 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
129 * |s s s s s s s s s s s s s| ns/s |
130 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
131 * | fraction |
132 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
133 */
134/*
135 * The following variables establish the state of the PLL/FLL and the
136 * residual time and frequency offset of the local clock.
137 */
138#define SHIFT_PLL 4 /* PLL loop gain (shift) */
139#define SHIFT_FLL 2 /* FLL loop gain (shift) */
140
141static int time_state = TIME_OK; /* clock state */
142static int time_status = STA_UNSYNC; /* clock status bits */
143static long time_tai; /* TAI offset (s) */
144static long time_monitor; /* last time offset scaled (ns) */
145static long time_constant; /* poll interval (shift) (s) */
146static long time_precision = 1; /* clock precision (ns) */
147static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */
148static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */
149static long time_reftime; /* time at last adjustment (s) */
150static long time_tick; /* nanoseconds per tick (ns) */
151static l_fp time_offset; /* time offset (ns) */
152static l_fp time_freq; /* frequency offset (ns/s) */
153static l_fp time_adj; /* tick adjust (ns/s) */
154
155#ifdef PPS_SYNC
156/*
157 * The following variables are used when a pulse-per-second (PPS) signal
158 * is available and connected via a modem control lead. They establish
159 * the engineering parameters of the clock discipline loop when
160 * controlled by the PPS signal.
161 */
162#define PPS_FAVG 2 /* min freq avg interval (s) (shift) */
163#define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */
164#define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */
165#define PPS_PAVG 4 /* phase avg interval (s) (shift) */
166#define PPS_VALID 120 /* PPS signal watchdog max (s) */
167#define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */
168#define PPS_POPCORN 2 /* popcorn spike threshold (shift) */
169
170static struct timespec pps_tf[3]; /* phase median filter */
171static l_fp pps_freq; /* scaled frequency offset (ns/s) */
172static long pps_fcount; /* frequency accumulator */
173static long pps_jitter; /* nominal jitter (ns) */
174static long pps_stabil; /* nominal stability (scaled ns/s) */
175static long pps_lastsec; /* time at last calibration (s) */
176static int pps_valid; /* signal watchdog counter */
177static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */
178static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */
179static int pps_intcnt; /* wander counter */
180
181/*
182 * PPS signal quality monitors
183 */
184static long pps_calcnt; /* calibration intervals */
185static long pps_jitcnt; /* jitter limit exceeded */
186static long pps_stbcnt; /* stability limit exceeded */
187static long pps_errcnt; /* calibration errors */
188#endif /* PPS_SYNC */
189/*
190 * End of phase/frequency-lock loop (PLL/FLL) definitions
191 */
192
193static void ntp_init(void);
194static void hardupdate(long offset);
195
196/*
197 * ntp_gettime() - NTP user application interface
198 *
199 * See the timex.h header file for synopsis and API description. Note
200 * that the TAI offset is returned in the ntvtimeval.tai structure
201 * member.
202 */
203static int
204ntp_sysctl(SYSCTL_HANDLER_ARGS)
205{
206 struct ntptimeval ntv; /* temporary structure */
207 struct timespec atv; /* nanosecond time */
208
209 nanotime(&atv);
210 ntv.time.tv_sec = atv.tv_sec;
211 ntv.time.tv_nsec = atv.tv_nsec;
212 ntv.maxerror = time_maxerror;
213 ntv.esterror = time_esterror;
214 ntv.tai = time_tai;
215 ntv.time_state = time_state;
216
217 /*
218 * Status word error decode. If any of these conditions occur,
219 * an error is returned, instead of the status word. Most
220 * applications will care only about the fact the system clock
221 * may not be trusted, not about the details.
222 *
223 * Hardware or software error
224 */
225 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||
226
227 /*
228 * PPS signal lost when either time or frequency synchronization
229 * requested
230 */
231 (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
232 !(time_status & STA_PPSSIGNAL)) ||
233
234 /*
235 * PPS jitter exceeded when time synchronization requested
236 */
237 (time_status & STA_PPSTIME &&
238 time_status & STA_PPSJITTER) ||
239
240 /*
241 * PPS wander exceeded or calibration error when frequency
242 * synchronization requested
243 */
244 (time_status & STA_PPSFREQ &&
245 time_status & (STA_PPSWANDER | STA_PPSERROR)))
246 ntv.time_state = TIME_ERROR;
247 return (sysctl_handle_opaque(oidp, &ntv, sizeof ntv, req));
248}
249
250SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, "");
251SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD,
252 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", "");
253
254#ifdef PPS_SYNC
255SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, &pps_shiftmax, 0, "");
256SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, &pps_shift, 0, "");
257SYSCTL_INT(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, &time_monitor, 0, "");
258
259SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD, &pps_freq, sizeof(pps_freq), "I", "");
260SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD, &time_freq, sizeof(time_freq), "I", "");
261#endif
262/*
263 * ntp_adjtime() - NTP daemon application interface
264 *
265 * See the timex.h header file for synopsis and API description. Note
266 * that the timex.constant structure member has a dual purpose to set
267 * the time constant and to set the TAI offset.
268 */
984263bc 269int
753fd850 270sys_ntp_adjtime(struct ntp_adjtime_args *uap)
984263bc 271{
dadab5e9 272 struct thread *td = curthread;
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273 struct timex ntv; /* temporary structure */
274 long freq; /* frequency ns/s) */
275 int modes; /* mode bits from structure */
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276 int error;
277
278 error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv));
279 if (error)
280 return(error);
281
282 /*
283 * Update selected clock variables - only the superuser can
284 * change anything. Note that there is no error checking here on
285 * the assumption the superuser should know what it is doing.
286 * Note that either the time constant or TAI offset are loaded
287 * from the ntv.constant member, depending on the mode bits. If
288 * the STA_PLL bit in the status word is cleared, the state and
289 * status words are reset to the initial values at boot.
290 */
291 modes = ntv.modes;
292 if (modes)
1dad22bb 293 error = priv_check(td, PRIV_NTP_ADJTIME);
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294 if (error)
295 return (error);
88c4d2f6 296 crit_enter();
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297 if (modes & MOD_MAXERROR)
298 time_maxerror = ntv.maxerror;
299 if (modes & MOD_ESTERROR)
300 time_esterror = ntv.esterror;
301 if (modes & MOD_STATUS) {
302 if (time_status & STA_PLL && !(ntv.status & STA_PLL)) {
303 time_state = TIME_OK;
304 time_status = STA_UNSYNC;
305#ifdef PPS_SYNC
306 pps_shift = PPS_FAVG;
307#endif /* PPS_SYNC */
308 }
309 time_status &= STA_RONLY;
310 time_status |= ntv.status & ~STA_RONLY;
311 }
312 if (modes & MOD_TIMECONST) {
313 if (ntv.constant < 0)
314 time_constant = 0;
315 else if (ntv.constant > MAXTC)
316 time_constant = MAXTC;
317 else
318 time_constant = ntv.constant;
319 }
320 if (modes & MOD_TAI) {
321 if (ntv.constant > 0) /* XXX zero & negative numbers ? */
322 time_tai = ntv.constant;
323 }
324#ifdef PPS_SYNC
325 if (modes & MOD_PPSMAX) {
326 if (ntv.shift < PPS_FAVG)
327 pps_shiftmax = PPS_FAVG;
328 else if (ntv.shift > PPS_FAVGMAX)
329 pps_shiftmax = PPS_FAVGMAX;
330 else
331 pps_shiftmax = ntv.shift;
332 }
333#endif /* PPS_SYNC */
334 if (modes & MOD_NANO)
335 time_status |= STA_NANO;
336 if (modes & MOD_MICRO)
337 time_status &= ~STA_NANO;
338 if (modes & MOD_CLKB)
339 time_status |= STA_CLK;
340 if (modes & MOD_CLKA)
341 time_status &= ~STA_CLK;
342 if (modes & MOD_OFFSET) {
343 if (time_status & STA_NANO)
344 hardupdate(ntv.offset);
345 else
346 hardupdate(ntv.offset * 1000);
347 }
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348 /*
349 * Note: the userland specified frequency is in seconds per second
350 * times 65536e+6. Multiply by a thousand and divide by 65336 to
351 * get nanoseconds.
352 */
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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 */
88c4d2f6 397 crit_exit();
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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 &&
90b9818c 413 time_status & (STA_PPSWANDER | STA_PPSERROR))) {
c7114eea 414 uap->sysmsg_result = TIME_ERROR;
90b9818c 415 } else {
c7114eea 416 uap->sysmsg_result = time_state;
90b9818c 417 }
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418 return (error);
419}
420
421/*
422 * second_overflow() - called after ntp_tick_adjust()
423 *
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424 * This routine is ordinarily called from hardclock() whenever the seconds
425 * hand rolls over. It returns leap seconds to add or drop, and sets nsec_adj
426 * to the total adjustment to make over the next second in (ns << 32).
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427 *
428 * This routine is only called by cpu #0.
984263bc 429 */
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430int
431ntp_update_second(time_t newsec, int64_t *nsec_adj)
984263bc 432{
984263bc 433 l_fp ftemp; /* 32/64-bit temporary */
88c4d2f6 434 int adjsec = 0;
984263bc 435
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436 /*
437 * On rollover of the second both the nanosecond and microsecond
438 * clocks are updated and the state machine cranked as
439 * necessary. The phase adjustment to be used for the next
440 * second is calculated and the maximum error is increased by
441 * the tolerance.
442 */
443 time_maxerror += MAXFREQ / 1000;
444
445 /*
446 * Leap second processing. If in leap-insert state at
447 * the end of the day, the system clock is set back one
448 * second; if in leap-delete state, the system clock is
449 * set ahead one second. The nano_time() routine or
450 * external clock driver will insure that reported time
451 * is always monotonic.
452 */
453 switch (time_state) {
454
455 /*
456 * No warning.
457 */
458 case TIME_OK:
459 if (time_status & STA_INS)
460 time_state = TIME_INS;
461 else if (time_status & STA_DEL)
462 time_state = TIME_DEL;
463 break;
464
465 /*
466 * Insert second 23:59:60 following second
467 * 23:59:59.
468 */
469 case TIME_INS:
470 if (!(time_status & STA_INS))
471 time_state = TIME_OK;
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472 else if ((newsec) % 86400 == 0) {
473 --adjsec;
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474 time_state = TIME_OOP;
475 }
476 break;
477
478 /*
479 * Delete second 23:59:59.
480 */
481 case TIME_DEL:
482 if (!(time_status & STA_DEL))
483 time_state = TIME_OK;
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484 else if (((newsec) + 1) % 86400 == 0) {
485 ++adjsec;
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486 time_tai--;
487 time_state = TIME_WAIT;
488 }
489 break;
490
491 /*
492 * Insert second in progress.
493 */
494 case TIME_OOP:
495 time_tai++;
496 time_state = TIME_WAIT;
497 break;
498
499 /*
500 * Wait for status bits to clear.
501 */
502 case TIME_WAIT:
503 if (!(time_status & (STA_INS | STA_DEL)))
504 time_state = TIME_OK;
505 }
506
507 /*
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508 * time_offset represents the total time adjustment we wish to
509 * make (over no particular period of time). time_freq represents
510 * the frequency compensation we wish to apply.
511 *
512 * time_adj represents the total adjustment we wish to make over
513 * one full second. hardclock usually applies this adjustment in
514 * time_adj / hz jumps, hz times a second.
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515 */
516 ftemp = time_offset;
517#ifdef PPS_SYNC
518 /* XXX even if PPS signal dies we should finish adjustment ? */
581a9d18 519 if ((time_status & STA_PPSTIME) && (time_status & STA_PPSSIGNAL))
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520 L_RSHIFT(ftemp, pps_shift);
521 else
522 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
523#else
524 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
525#endif /* PPS_SYNC */
88c4d2f6 526 time_adj = ftemp; /* adjustment for part of the offset */
984263bc 527 L_SUB(time_offset, ftemp);
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528 L_ADD(time_adj, time_freq); /* add frequency correction */
529 *nsec_adj = time_adj;
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530#ifdef PPS_SYNC
531 if (pps_valid > 0)
532 pps_valid--;
533 else
534 time_status &= ~STA_PPSSIGNAL;
535#endif /* PPS_SYNC */
88c4d2f6 536 return(adjsec);
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537}
538
539/*
540 * ntp_init() - initialize variables and structures
541 *
542 * This routine must be called after the kernel variables hz and tick
543 * are set or changed and before the next tick interrupt. In this
544 * particular implementation, these values are assumed set elsewhere in
545 * the kernel. The design allows the clock frequency and tick interval
546 * to be changed while the system is running. So, this routine should
547 * probably be integrated with the code that does that.
548 */
549static void
77153250 550ntp_init(void)
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551{
552
553 /*
554 * The following variable must be initialized any time the
555 * kernel variable hz is changed.
556 */
557 time_tick = NANOSECOND / hz;
558
559 /*
560 * The following variables are initialized only at startup. Only
561 * those structures not cleared by the compiler need to be
562 * initialized, and these only in the simulator. In the actual
563 * kernel, any nonzero values here will quickly evaporate.
564 */
565 L_CLR(time_offset);
566 L_CLR(time_freq);
567#ifdef PPS_SYNC
568 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;
569 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;
570 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;
571 pps_fcount = 0;
572 L_CLR(pps_freq);
573#endif /* PPS_SYNC */
574}
575
ba39e2e0 576SYSINIT(ntpclocks, SI_BOOT2_CLOCKS, SI_ORDER_FIRST, ntp_init, NULL)
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577
578/*
579 * hardupdate() - local clock update
580 *
581 * This routine is called by ntp_adjtime() to update the local clock
582 * phase and frequency. The implementation is of an adaptive-parameter,
583 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
584 * time and frequency offset estimates for each call. If the kernel PPS
585 * discipline code is configured (PPS_SYNC), the PPS signal itself
586 * determines the new time offset, instead of the calling argument.
587 * Presumably, calls to ntp_adjtime() occur only when the caller
588 * believes the local clock is valid within some bound (+-128 ms with
589 * NTP). If the caller's time is far different than the PPS time, an
590 * argument will ensue, and it's not clear who will lose.
591 *
592 * For uncompensated quartz crystal oscillators and nominal update
593 * intervals less than 256 s, operation should be in phase-lock mode,
594 * where the loop is disciplined to phase. For update intervals greater
595 * than 1024 s, operation should be in frequency-lock mode, where the
596 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
597 * is selected by the STA_MODE status bit.
598 */
599static void
77153250 600hardupdate(long offset)
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601{
602 long mtemp;
603 l_fp ftemp;
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604 globaldata_t gd;
605
606 gd = mycpu;
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607
608 /*
609 * Select how the phase is to be controlled and from which
610 * source. If the PPS signal is present and enabled to
611 * discipline the time, the PPS offset is used; otherwise, the
612 * argument offset is used.
613 */
614 if (!(time_status & STA_PLL))
615 return;
88c4d2f6 616 if (!((time_status & STA_PPSTIME) && (time_status & STA_PPSSIGNAL))) {
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617 if (offset > MAXPHASE)
618 time_monitor = MAXPHASE;
619 else if (offset < -MAXPHASE)
620 time_monitor = -MAXPHASE;
621 else
622 time_monitor = offset;
623 L_LINT(time_offset, time_monitor);
624 }
625
626 /*
627 * Select how the frequency is to be controlled and in which
628 * mode (PLL or FLL). If the PPS signal is present and enabled
629 * to discipline the frequency, the PPS frequency is used;
630 * otherwise, the argument offset is used to compute it.
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631 *
632 * gd_time_seconds is basically an uncompensated uptime. We use
633 * this for consistency.
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634 */
635 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {
636 time_reftime = time_second;
637 return;
638 }
639 if (time_status & STA_FREQHOLD || time_reftime == 0)
640 time_reftime = time_second;
641 mtemp = time_second - time_reftime;
642 L_LINT(ftemp, time_monitor);
643 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
644 L_MPY(ftemp, mtemp);
645 L_ADD(time_freq, ftemp);
646 time_status &= ~STA_MODE;
88c4d2f6 647 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
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648 L_LINT(ftemp, (time_monitor << 4) / mtemp);
649 L_RSHIFT(ftemp, SHIFT_FLL + 4);
650 L_ADD(time_freq, ftemp);
651 time_status |= STA_MODE;
652 }
653 time_reftime = time_second;
654 if (L_GINT(time_freq) > MAXFREQ)
655 L_LINT(time_freq, MAXFREQ);
656 else if (L_GINT(time_freq) < -MAXFREQ)
657 L_LINT(time_freq, -MAXFREQ);
658}
659
660#ifdef PPS_SYNC
661/*
662 * hardpps() - discipline CPU clock oscillator to external PPS signal
663 *
664 * This routine is called at each PPS interrupt in order to discipline
665 * the CPU clock oscillator to the PPS signal. There are two independent
666 * first-order feedback loops, one for the phase, the other for the
667 * frequency. The phase loop measures and grooms the PPS phase offset
668 * and leaves it in a handy spot for the seconds overflow routine. The
669 * frequency loop averages successive PPS phase differences and
670 * calculates the PPS frequency offset, which is also processed by the
671 * seconds overflow routine. The code requires the caller to capture the
672 * time and architecture-dependent hardware counter values in
673 * nanoseconds at the on-time PPS signal transition.
674 *
675 * Note that, on some Unix systems this routine runs at an interrupt
676 * priority level higher than the timer interrupt routine hardclock().
677 * Therefore, the variables used are distinct from the hardclock()
678 * variables, except for the actual time and frequency variables, which
679 * are determined by this routine and updated atomically.
680 */
681void
77153250 682hardpps(struct timespec *tsp, long nsec)
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683{
684 long u_sec, u_nsec, v_nsec; /* temps */
685 l_fp ftemp;
686
687 /*
688 * The signal is first processed by a range gate and frequency
689 * discriminator. The range gate rejects noise spikes outside
690 * the range +-500 us. The frequency discriminator rejects input
691 * signals with apparent frequency outside the range 1 +-500
692 * PPM. If two hits occur in the same second, we ignore the
693 * later hit; if not and a hit occurs outside the range gate,
694 * keep the later hit for later comparison, but do not process
695 * it.
696 */
697 time_status |= STA_PPSSIGNAL | STA_PPSJITTER;
698 time_status &= ~(STA_PPSWANDER | STA_PPSERROR);
699 pps_valid = PPS_VALID;
700 u_sec = tsp->tv_sec;
701 u_nsec = tsp->tv_nsec;
702 if (u_nsec >= (NANOSECOND >> 1)) {
703 u_nsec -= NANOSECOND;
704 u_sec++;
705 }
706 v_nsec = u_nsec - pps_tf[0].tv_nsec;
707 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND -
708 MAXFREQ)
709 return;
710 pps_tf[2] = pps_tf[1];
711 pps_tf[1] = pps_tf[0];
712 pps_tf[0].tv_sec = u_sec;
713 pps_tf[0].tv_nsec = u_nsec;
714
715 /*
716 * Compute the difference between the current and previous
717 * counter values. If the difference exceeds 0.5 s, assume it
718 * has wrapped around, so correct 1.0 s. If the result exceeds
719 * the tick interval, the sample point has crossed a tick
720 * boundary during the last second, so correct the tick. Very
721 * intricate.
722 */
723 u_nsec = nsec;
724 if (u_nsec > (NANOSECOND >> 1))
725 u_nsec -= NANOSECOND;
726 else if (u_nsec < -(NANOSECOND >> 1))
727 u_nsec += NANOSECOND;
728 pps_fcount += u_nsec;
729 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
730 return;
731 time_status &= ~STA_PPSJITTER;
732
733 /*
734 * A three-stage median filter is used to help denoise the PPS
735 * time. The median sample becomes the time offset estimate; the
736 * difference between the other two samples becomes the time
737 * dispersion (jitter) estimate.
738 */
739 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {
740 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {
741 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */
742 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;
743 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {
744 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */
745 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;
746 } else {
747 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */
748 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;
749 }
750 } else {
751 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {
752 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */
753 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;
754 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {
755 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */
756 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;
757 } else {
758 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */
759 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;
760 }
761 }
762
763 /*
764 * Nominal jitter is due to PPS signal noise and interrupt
765 * latency. If it exceeds the popcorn threshold, the sample is
766 * discarded. otherwise, if so enabled, the time offset is
767 * updated. We can tolerate a modest loss of data here without
768 * much degrading time accuracy.
769 */
770 if (u_nsec > (pps_jitter << PPS_POPCORN)) {
771 time_status |= STA_PPSJITTER;
772 pps_jitcnt++;
773 } else if (time_status & STA_PPSTIME) {
774 time_monitor = -v_nsec;
775 L_LINT(time_offset, time_monitor);
776 }
777 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;
778 u_sec = pps_tf[0].tv_sec - pps_lastsec;
779 if (u_sec < (1 << pps_shift))
780 return;
781
782 /*
783 * At the end of the calibration interval the difference between
784 * the first and last counter values becomes the scaled
785 * frequency. It will later be divided by the length of the
786 * interval to determine the frequency update. If the frequency
787 * exceeds a sanity threshold, or if the actual calibration
788 * interval is not equal to the expected length, the data are
789 * discarded. We can tolerate a modest loss of data here without
790 * much degrading frequency accuracy.
791 */
792 pps_calcnt++;
793 v_nsec = -pps_fcount;
794 pps_lastsec = pps_tf[0].tv_sec;
795 pps_fcount = 0;
796 u_nsec = MAXFREQ << pps_shift;
797 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 <<
798 pps_shift)) {
799 time_status |= STA_PPSERROR;
800 pps_errcnt++;
801 return;
802 }
803
804 /*
805 * Here the raw frequency offset and wander (stability) is
806 * calculated. If the wander is less than the wander threshold
807 * for four consecutive averaging intervals, the interval is
808 * doubled; if it is greater than the threshold for four
809 * consecutive intervals, the interval is halved. The scaled
810 * frequency offset is converted to frequency offset. The
811 * stability metric is calculated as the average of recent
812 * frequency changes, but is used only for performance
813 * monitoring.
814 */
815 L_LINT(ftemp, v_nsec);
816 L_RSHIFT(ftemp, pps_shift);
817 L_SUB(ftemp, pps_freq);
818 u_nsec = L_GINT(ftemp);
819 if (u_nsec > PPS_MAXWANDER) {
820 L_LINT(ftemp, PPS_MAXWANDER);
821 pps_intcnt--;
822 time_status |= STA_PPSWANDER;
823 pps_stbcnt++;
824 } else if (u_nsec < -PPS_MAXWANDER) {
825 L_LINT(ftemp, -PPS_MAXWANDER);
826 pps_intcnt--;
827 time_status |= STA_PPSWANDER;
828 pps_stbcnt++;
829 } else {
830 pps_intcnt++;
831 }
832 if (pps_intcnt >= 4) {
833 pps_intcnt = 4;
834 if (pps_shift < pps_shiftmax) {
835 pps_shift++;
836 pps_intcnt = 0;
837 }
838 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {
839 pps_intcnt = -4;
840 if (pps_shift > PPS_FAVG) {
841 pps_shift--;
842 pps_intcnt = 0;
843 }
844 }
845 if (u_nsec < 0)
846 u_nsec = -u_nsec;
847 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;
848
849 /*
850 * The PPS frequency is recalculated and clamped to the maximum
851 * MAXFREQ. If enabled, the system clock frequency is updated as
852 * well.
853 */
854 L_ADD(pps_freq, ftemp);
855 u_nsec = L_GINT(pps_freq);
856 if (u_nsec > MAXFREQ)
857 L_LINT(pps_freq, MAXFREQ);
858 else if (u_nsec < -MAXFREQ)
859 L_LINT(pps_freq, -MAXFREQ);
860 if (time_status & STA_PPSFREQ)
861 time_freq = pps_freq;
862}
863#endif /* PPS_SYNC */