FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_tc.c
1 /*-
2 * ----------------------------------------------------------------------------
3 * "THE BEER-WARE LICENSE" (Revision 42):
4 * <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you
5 * can do whatever you want with this stuff. If we meet some day, and you think
6 * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp
7 * ----------------------------------------------------------------------------
8 */
9
10 #include <sys/cdefs.h>
11 __FBSDID("$FreeBSD: releng/6.4/sys/kern/kern_tc.c 144152 2005-03-26 20:04:28Z phk $");
12
13 #include "opt_ntp.h"
14
15 #include <sys/param.h>
16 #include <sys/kernel.h>
17 #include <sys/sysctl.h>
18 #include <sys/syslog.h>
19 #include <sys/systm.h>
20 #include <sys/timepps.h>
21 #include <sys/timetc.h>
22 #include <sys/timex.h>
23
24 /*
25 * A large step happens on boot. This constant detects such steps.
26 * It is relatively small so that ntp_update_second gets called enough
27 * in the typical 'missed a couple of seconds' case, but doesn't loop
28 * forever when the time step is large.
29 */
30 #define LARGE_STEP 200
31
32 /*
33 * Implement a dummy timecounter which we can use until we get a real one
34 * in the air. This allows the console and other early stuff to use
35 * time services.
36 */
37
38 static u_int
39 dummy_get_timecount(struct timecounter *tc)
40 {
41 static u_int now;
42
43 return (++now);
44 }
45
46 static struct timecounter dummy_timecounter = {
47 dummy_get_timecount, 0, ~0u, 1000000, "dummy", -1000000
48 };
49
50 struct timehands {
51 /* These fields must be initialized by the driver. */
52 struct timecounter *th_counter;
53 int64_t th_adjustment;
54 u_int64_t th_scale;
55 u_int th_offset_count;
56 struct bintime th_offset;
57 struct timeval th_microtime;
58 struct timespec th_nanotime;
59 /* Fields not to be copied in tc_windup start with th_generation. */
60 volatile u_int th_generation;
61 struct timehands *th_next;
62 };
63
64 extern struct timehands th0;
65 static struct timehands th9 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th0};
66 static struct timehands th8 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th9};
67 static struct timehands th7 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th8};
68 static struct timehands th6 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th7};
69 static struct timehands th5 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th6};
70 static struct timehands th4 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th5};
71 static struct timehands th3 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th4};
72 static struct timehands th2 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th3};
73 static struct timehands th1 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th2};
74 static struct timehands th0 = {
75 &dummy_timecounter,
76 0,
77 (uint64_t)-1 / 1000000,
78 0,
79 {1, 0},
80 {0, 0},
81 {0, 0},
82 1,
83 &th1
84 };
85
86 static struct timehands *volatile timehands = &th0;
87 struct timecounter *timecounter = &dummy_timecounter;
88 static struct timecounter *timecounters = &dummy_timecounter;
89
90 time_t time_second = 1;
91 time_t time_uptime = 0;
92
93 static struct bintime boottimebin;
94 struct timeval boottime;
95 static int sysctl_kern_boottime(SYSCTL_HANDLER_ARGS);
96 SYSCTL_PROC(_kern, KERN_BOOTTIME, boottime, CTLTYPE_STRUCT|CTLFLAG_RD,
97 NULL, 0, sysctl_kern_boottime, "S,timeval", "System boottime");
98
99 SYSCTL_NODE(_kern, OID_AUTO, timecounter, CTLFLAG_RW, 0, "");
100
101 static int timestepwarnings;
102 SYSCTL_INT(_kern_timecounter, OID_AUTO, stepwarnings, CTLFLAG_RW,
103 ×tepwarnings, 0, "");
104
105 #define TC_STATS(foo) \
106 static u_int foo; \
107 SYSCTL_UINT(_kern_timecounter, OID_AUTO, foo, CTLFLAG_RD, &foo, 0, "");\
108 struct __hack
109
110 TC_STATS(nbinuptime); TC_STATS(nnanouptime); TC_STATS(nmicrouptime);
111 TC_STATS(nbintime); TC_STATS(nnanotime); TC_STATS(nmicrotime);
112 TC_STATS(ngetbinuptime); TC_STATS(ngetnanouptime); TC_STATS(ngetmicrouptime);
113 TC_STATS(ngetbintime); TC_STATS(ngetnanotime); TC_STATS(ngetmicrotime);
114 TC_STATS(nsetclock);
115
116 #undef TC_STATS
117
118 static void tc_windup(void);
119
120 static int
121 sysctl_kern_boottime(SYSCTL_HANDLER_ARGS)
122 {
123 #ifdef SCTL_MASK32
124 int tv[2];
125
126 if (req->flags & SCTL_MASK32) {
127 tv[0] = boottime.tv_sec;
128 tv[1] = boottime.tv_usec;
129 return SYSCTL_OUT(req, tv, sizeof(tv));
130 } else
131 #endif
132 return SYSCTL_OUT(req, &boottime, sizeof(boottime));
133 }
134 /*
135 * Return the difference between the timehands' counter value now and what
136 * was when we copied it to the timehands' offset_count.
137 */
138 static __inline u_int
139 tc_delta(struct timehands *th)
140 {
141 struct timecounter *tc;
142
143 tc = th->th_counter;
144 return ((tc->tc_get_timecount(tc) - th->th_offset_count) &
145 tc->tc_counter_mask);
146 }
147
148 /*
149 * Functions for reading the time. We have to loop until we are sure that
150 * the timehands that we operated on was not updated under our feet. See
151 * the comment in <sys/time.h> for a description of these 12 functions.
152 */
153
154 void
155 binuptime(struct bintime *bt)
156 {
157 struct timehands *th;
158 u_int gen;
159
160 nbinuptime++;
161 do {
162 th = timehands;
163 gen = th->th_generation;
164 *bt = th->th_offset;
165 bintime_addx(bt, th->th_scale * tc_delta(th));
166 } while (gen == 0 || gen != th->th_generation);
167 }
168
169 void
170 nanouptime(struct timespec *tsp)
171 {
172 struct bintime bt;
173
174 nnanouptime++;
175 binuptime(&bt);
176 bintime2timespec(&bt, tsp);
177 }
178
179 void
180 microuptime(struct timeval *tvp)
181 {
182 struct bintime bt;
183
184 nmicrouptime++;
185 binuptime(&bt);
186 bintime2timeval(&bt, tvp);
187 }
188
189 void
190 bintime(struct bintime *bt)
191 {
192
193 nbintime++;
194 binuptime(bt);
195 bintime_add(bt, &boottimebin);
196 }
197
198 void
199 nanotime(struct timespec *tsp)
200 {
201 struct bintime bt;
202
203 nnanotime++;
204 bintime(&bt);
205 bintime2timespec(&bt, tsp);
206 }
207
208 void
209 microtime(struct timeval *tvp)
210 {
211 struct bintime bt;
212
213 nmicrotime++;
214 bintime(&bt);
215 bintime2timeval(&bt, tvp);
216 }
217
218 void
219 getbinuptime(struct bintime *bt)
220 {
221 struct timehands *th;
222 u_int gen;
223
224 ngetbinuptime++;
225 do {
226 th = timehands;
227 gen = th->th_generation;
228 *bt = th->th_offset;
229 } while (gen == 0 || gen != th->th_generation);
230 }
231
232 void
233 getnanouptime(struct timespec *tsp)
234 {
235 struct timehands *th;
236 u_int gen;
237
238 ngetnanouptime++;
239 do {
240 th = timehands;
241 gen = th->th_generation;
242 bintime2timespec(&th->th_offset, tsp);
243 } while (gen == 0 || gen != th->th_generation);
244 }
245
246 void
247 getmicrouptime(struct timeval *tvp)
248 {
249 struct timehands *th;
250 u_int gen;
251
252 ngetmicrouptime++;
253 do {
254 th = timehands;
255 gen = th->th_generation;
256 bintime2timeval(&th->th_offset, tvp);
257 } while (gen == 0 || gen != th->th_generation);
258 }
259
260 void
261 getbintime(struct bintime *bt)
262 {
263 struct timehands *th;
264 u_int gen;
265
266 ngetbintime++;
267 do {
268 th = timehands;
269 gen = th->th_generation;
270 *bt = th->th_offset;
271 } while (gen == 0 || gen != th->th_generation);
272 bintime_add(bt, &boottimebin);
273 }
274
275 void
276 getnanotime(struct timespec *tsp)
277 {
278 struct timehands *th;
279 u_int gen;
280
281 ngetnanotime++;
282 do {
283 th = timehands;
284 gen = th->th_generation;
285 *tsp = th->th_nanotime;
286 } while (gen == 0 || gen != th->th_generation);
287 }
288
289 void
290 getmicrotime(struct timeval *tvp)
291 {
292 struct timehands *th;
293 u_int gen;
294
295 ngetmicrotime++;
296 do {
297 th = timehands;
298 gen = th->th_generation;
299 *tvp = th->th_microtime;
300 } while (gen == 0 || gen != th->th_generation);
301 }
302
303 /*
304 * Initialize a new timecounter and possibly use it.
305 */
306 void
307 tc_init(struct timecounter *tc)
308 {
309 u_int u;
310
311 u = tc->tc_frequency / tc->tc_counter_mask;
312 /* XXX: We need some margin here, 10% is a guess */
313 u *= 11;
314 u /= 10;
315 if (u > hz && tc->tc_quality >= 0) {
316 tc->tc_quality = -2000;
317 if (bootverbose) {
318 printf("Timecounter \"%s\" frequency %ju Hz",
319 tc->tc_name, (uintmax_t)tc->tc_frequency);
320 printf(" -- Insufficient hz, needs at least %u\n", u);
321 }
322 } else if (tc->tc_quality >= 0 || bootverbose) {
323 printf("Timecounter \"%s\" frequency %ju Hz quality %d\n",
324 tc->tc_name, (uintmax_t)tc->tc_frequency,
325 tc->tc_quality);
326 }
327
328 tc->tc_next = timecounters;
329 timecounters = tc;
330 /*
331 * Never automatically use a timecounter with negative quality.
332 * Even though we run on the dummy counter, switching here may be
333 * worse since this timecounter may not be monotonous.
334 */
335 if (tc->tc_quality < 0)
336 return;
337 if (tc->tc_quality < timecounter->tc_quality)
338 return;
339 if (tc->tc_quality == timecounter->tc_quality &&
340 tc->tc_frequency < timecounter->tc_frequency)
341 return;
342 (void)tc->tc_get_timecount(tc);
343 (void)tc->tc_get_timecount(tc);
344 timecounter = tc;
345 }
346
347 /* Report the frequency of the current timecounter. */
348 u_int64_t
349 tc_getfrequency(void)
350 {
351
352 return (timehands->th_counter->tc_frequency);
353 }
354
355 /*
356 * Step our concept of UTC. This is done by modifying our estimate of
357 * when we booted.
358 * XXX: not locked.
359 */
360 void
361 tc_setclock(struct timespec *ts)
362 {
363 struct timespec ts2;
364 struct bintime bt, bt2;
365
366 nsetclock++;
367 binuptime(&bt2);
368 timespec2bintime(ts, &bt);
369 bintime_sub(&bt, &bt2);
370 bintime_add(&bt2, &boottimebin);
371 boottimebin = bt;
372 bintime2timeval(&bt, &boottime);
373
374 /* XXX fiddle all the little crinkly bits around the fiords... */
375 tc_windup();
376 if (timestepwarnings) {
377 bintime2timespec(&bt2, &ts2);
378 log(LOG_INFO, "Time stepped from %jd.%09ld to %jd.%09ld\n",
379 (intmax_t)ts2.tv_sec, ts2.tv_nsec,
380 (intmax_t)ts->tv_sec, ts->tv_nsec);
381 }
382 }
383
384 /*
385 * Initialize the next struct timehands in the ring and make
386 * it the active timehands. Along the way we might switch to a different
387 * timecounter and/or do seconds processing in NTP. Slightly magic.
388 */
389 static void
390 tc_windup(void)
391 {
392 struct bintime bt;
393 struct timehands *th, *tho;
394 u_int64_t scale;
395 u_int delta, ncount, ogen;
396 int i;
397 time_t t;
398
399 /*
400 * Make the next timehands a copy of the current one, but do not
401 * overwrite the generation or next pointer. While we update
402 * the contents, the generation must be zero.
403 */
404 tho = timehands;
405 th = tho->th_next;
406 ogen = th->th_generation;
407 th->th_generation = 0;
408 bcopy(tho, th, offsetof(struct timehands, th_generation));
409
410 /*
411 * Capture a timecounter delta on the current timecounter and if
412 * changing timecounters, a counter value from the new timecounter.
413 * Update the offset fields accordingly.
414 */
415 delta = tc_delta(th);
416 if (th->th_counter != timecounter)
417 ncount = timecounter->tc_get_timecount(timecounter);
418 else
419 ncount = 0;
420 th->th_offset_count += delta;
421 th->th_offset_count &= th->th_counter->tc_counter_mask;
422 bintime_addx(&th->th_offset, th->th_scale * delta);
423
424 /*
425 * Hardware latching timecounters may not generate interrupts on
426 * PPS events, so instead we poll them. There is a finite risk that
427 * the hardware might capture a count which is later than the one we
428 * got above, and therefore possibly in the next NTP second which might
429 * have a different rate than the current NTP second. It doesn't
430 * matter in practice.
431 */
432 if (tho->th_counter->tc_poll_pps)
433 tho->th_counter->tc_poll_pps(tho->th_counter);
434
435 /*
436 * Deal with NTP second processing. The for loop normally
437 * iterates at most once, but in extreme situations it might
438 * keep NTP sane if timeouts are not run for several seconds.
439 * At boot, the time step can be large when the TOD hardware
440 * has been read, so on really large steps, we call
441 * ntp_update_second only twice. We need to call it twice in
442 * case we missed a leap second.
443 */
444 bt = th->th_offset;
445 bintime_add(&bt, &boottimebin);
446 i = bt.sec - tho->th_microtime.tv_sec;
447 if (i > LARGE_STEP)
448 i = 2;
449 for (; i > 0; i--) {
450 t = bt.sec;
451 ntp_update_second(&th->th_adjustment, &bt.sec);
452 if (bt.sec != t)
453 boottimebin.sec += bt.sec - t;
454 }
455 /* Update the UTC timestamps used by the get*() functions. */
456 /* XXX shouldn't do this here. Should force non-`get' versions. */
457 bintime2timeval(&bt, &th->th_microtime);
458 bintime2timespec(&bt, &th->th_nanotime);
459
460 /* Now is a good time to change timecounters. */
461 if (th->th_counter != timecounter) {
462 th->th_counter = timecounter;
463 th->th_offset_count = ncount;
464 }
465
466 /*-
467 * Recalculate the scaling factor. We want the number of 1/2^64
468 * fractions of a second per period of the hardware counter, taking
469 * into account the th_adjustment factor which the NTP PLL/adjtime(2)
470 * processing provides us with.
471 *
472 * The th_adjustment is nanoseconds per second with 32 bit binary
473 * fraction and we want 64 bit binary fraction of second:
474 *
475 * x = a * 2^32 / 10^9 = a * 4.294967296
476 *
477 * The range of th_adjustment is +/- 5000PPM so inside a 64bit int
478 * we can only multiply by about 850 without overflowing, but that
479 * leaves suitably precise fractions for multiply before divide.
480 *
481 * Divide before multiply with a fraction of 2199/512 results in a
482 * systematic undercompensation of 10PPM of th_adjustment. On a
483 * 5000PPM adjustment this is a 0.05PPM error. This is acceptable.
484 *
485 * We happily sacrifice the lowest of the 64 bits of our result
486 * to the goddess of code clarity.
487 *
488 */
489 scale = (u_int64_t)1 << 63;
490 scale += (th->th_adjustment / 1024) * 2199;
491 scale /= th->th_counter->tc_frequency;
492 th->th_scale = scale * 2;
493
494 /*
495 * Now that the struct timehands is again consistent, set the new
496 * generation number, making sure to not make it zero.
497 */
498 if (++ogen == 0)
499 ogen = 1;
500 th->th_generation = ogen;
501
502 /* Go live with the new struct timehands. */
503 time_second = th->th_microtime.tv_sec;
504 time_uptime = th->th_offset.sec;
505 timehands = th;
506 }
507
508 /* Report or change the active timecounter hardware. */
509 static int
510 sysctl_kern_timecounter_hardware(SYSCTL_HANDLER_ARGS)
511 {
512 char newname[32];
513 struct timecounter *newtc, *tc;
514 int error;
515
516 tc = timecounter;
517 strlcpy(newname, tc->tc_name, sizeof(newname));
518
519 error = sysctl_handle_string(oidp, &newname[0], sizeof(newname), req);
520 if (error != 0 || req->newptr == NULL ||
521 strcmp(newname, tc->tc_name) == 0)
522 return (error);
523 for (newtc = timecounters; newtc != NULL; newtc = newtc->tc_next) {
524 if (strcmp(newname, newtc->tc_name) != 0)
525 continue;
526
527 /* Warm up new timecounter. */
528 (void)newtc->tc_get_timecount(newtc);
529 (void)newtc->tc_get_timecount(newtc);
530
531 timecounter = newtc;
532 return (0);
533 }
534 return (EINVAL);
535 }
536
537 SYSCTL_PROC(_kern_timecounter, OID_AUTO, hardware, CTLTYPE_STRING | CTLFLAG_RW,
538 0, 0, sysctl_kern_timecounter_hardware, "A", "");
539
540
541 /* Report or change the active timecounter hardware. */
542 static int
543 sysctl_kern_timecounter_choice(SYSCTL_HANDLER_ARGS)
544 {
545 char buf[32], *spc;
546 struct timecounter *tc;
547 int error;
548
549 spc = "";
550 error = 0;
551 for (tc = timecounters; error == 0 && tc != NULL; tc = tc->tc_next) {
552 sprintf(buf, "%s%s(%d)",
553 spc, tc->tc_name, tc->tc_quality);
554 error = SYSCTL_OUT(req, buf, strlen(buf));
555 spc = " ";
556 }
557 return (error);
558 }
559
560 SYSCTL_PROC(_kern_timecounter, OID_AUTO, choice, CTLTYPE_STRING | CTLFLAG_RD,
561 0, 0, sysctl_kern_timecounter_choice, "A", "");
562
563 /*
564 * RFC 2783 PPS-API implementation.
565 */
566
567 int
568 pps_ioctl(u_long cmd, caddr_t data, struct pps_state *pps)
569 {
570 pps_params_t *app;
571 struct pps_fetch_args *fapi;
572 #ifdef PPS_SYNC
573 struct pps_kcbind_args *kapi;
574 #endif
575
576 KASSERT(pps != NULL, ("NULL pps pointer in pps_ioctl"));
577 switch (cmd) {
578 case PPS_IOC_CREATE:
579 return (0);
580 case PPS_IOC_DESTROY:
581 return (0);
582 case PPS_IOC_SETPARAMS:
583 app = (pps_params_t *)data;
584 if (app->mode & ~pps->ppscap)
585 return (EINVAL);
586 pps->ppsparam = *app;
587 return (0);
588 case PPS_IOC_GETPARAMS:
589 app = (pps_params_t *)data;
590 *app = pps->ppsparam;
591 app->api_version = PPS_API_VERS_1;
592 return (0);
593 case PPS_IOC_GETCAP:
594 *(int*)data = pps->ppscap;
595 return (0);
596 case PPS_IOC_FETCH:
597 fapi = (struct pps_fetch_args *)data;
598 if (fapi->tsformat && fapi->tsformat != PPS_TSFMT_TSPEC)
599 return (EINVAL);
600 if (fapi->timeout.tv_sec || fapi->timeout.tv_nsec)
601 return (EOPNOTSUPP);
602 pps->ppsinfo.current_mode = pps->ppsparam.mode;
603 fapi->pps_info_buf = pps->ppsinfo;
604 return (0);
605 case PPS_IOC_KCBIND:
606 #ifdef PPS_SYNC
607 kapi = (struct pps_kcbind_args *)data;
608 /* XXX Only root should be able to do this */
609 if (kapi->tsformat && kapi->tsformat != PPS_TSFMT_TSPEC)
610 return (EINVAL);
611 if (kapi->kernel_consumer != PPS_KC_HARDPPS)
612 return (EINVAL);
613 if (kapi->edge & ~pps->ppscap)
614 return (EINVAL);
615 pps->kcmode = kapi->edge;
616 return (0);
617 #else
618 return (EOPNOTSUPP);
619 #endif
620 default:
621 return (ENOIOCTL);
622 }
623 }
624
625 void
626 pps_init(struct pps_state *pps)
627 {
628 pps->ppscap |= PPS_TSFMT_TSPEC;
629 if (pps->ppscap & PPS_CAPTUREASSERT)
630 pps->ppscap |= PPS_OFFSETASSERT;
631 if (pps->ppscap & PPS_CAPTURECLEAR)
632 pps->ppscap |= PPS_OFFSETCLEAR;
633 }
634
635 void
636 pps_capture(struct pps_state *pps)
637 {
638 struct timehands *th;
639
640 KASSERT(pps != NULL, ("NULL pps pointer in pps_capture"));
641 th = timehands;
642 pps->capgen = th->th_generation;
643 pps->capth = th;
644 pps->capcount = th->th_counter->tc_get_timecount(th->th_counter);
645 if (pps->capgen != th->th_generation)
646 pps->capgen = 0;
647 }
648
649 void
650 pps_event(struct pps_state *pps, int event)
651 {
652 struct bintime bt;
653 struct timespec ts, *tsp, *osp;
654 u_int tcount, *pcount;
655 int foff, fhard;
656 pps_seq_t *pseq;
657
658 KASSERT(pps != NULL, ("NULL pps pointer in pps_event"));
659 /* If the timecounter was wound up underneath us, bail out. */
660 if (pps->capgen == 0 || pps->capgen != pps->capth->th_generation)
661 return;
662
663 /* Things would be easier with arrays. */
664 if (event == PPS_CAPTUREASSERT) {
665 tsp = &pps->ppsinfo.assert_timestamp;
666 osp = &pps->ppsparam.assert_offset;
667 foff = pps->ppsparam.mode & PPS_OFFSETASSERT;
668 fhard = pps->kcmode & PPS_CAPTUREASSERT;
669 pcount = &pps->ppscount[0];
670 pseq = &pps->ppsinfo.assert_sequence;
671 } else {
672 tsp = &pps->ppsinfo.clear_timestamp;
673 osp = &pps->ppsparam.clear_offset;
674 foff = pps->ppsparam.mode & PPS_OFFSETCLEAR;
675 fhard = pps->kcmode & PPS_CAPTURECLEAR;
676 pcount = &pps->ppscount[1];
677 pseq = &pps->ppsinfo.clear_sequence;
678 }
679
680 /*
681 * If the timecounter changed, we cannot compare the count values, so
682 * we have to drop the rest of the PPS-stuff until the next event.
683 */
684 if (pps->ppstc != pps->capth->th_counter) {
685 pps->ppstc = pps->capth->th_counter;
686 *pcount = pps->capcount;
687 pps->ppscount[2] = pps->capcount;
688 return;
689 }
690
691 /* Convert the count to a timespec. */
692 tcount = pps->capcount - pps->capth->th_offset_count;
693 tcount &= pps->capth->th_counter->tc_counter_mask;
694 bt = pps->capth->th_offset;
695 bintime_addx(&bt, pps->capth->th_scale * tcount);
696 bintime_add(&bt, &boottimebin);
697 bintime2timespec(&bt, &ts);
698
699 /* If the timecounter was wound up underneath us, bail out. */
700 if (pps->capgen != pps->capth->th_generation)
701 return;
702
703 *pcount = pps->capcount;
704 (*pseq)++;
705 *tsp = ts;
706
707 if (foff) {
708 timespecadd(tsp, osp);
709 if (tsp->tv_nsec < 0) {
710 tsp->tv_nsec += 1000000000;
711 tsp->tv_sec -= 1;
712 }
713 }
714 #ifdef PPS_SYNC
715 if (fhard) {
716 u_int64_t scale;
717
718 /*
719 * Feed the NTP PLL/FLL.
720 * The FLL wants to know how many (hardware) nanoseconds
721 * elapsed since the previous event.
722 */
723 tcount = pps->capcount - pps->ppscount[2];
724 pps->ppscount[2] = pps->capcount;
725 tcount &= pps->capth->th_counter->tc_counter_mask;
726 scale = (u_int64_t)1 << 63;
727 scale /= pps->capth->th_counter->tc_frequency;
728 scale *= 2;
729 bt.sec = 0;
730 bt.frac = 0;
731 bintime_addx(&bt, scale * tcount);
732 bintime2timespec(&bt, &ts);
733 hardpps(tsp, ts.tv_nsec + 1000000000 * ts.tv_sec);
734 }
735 #endif
736 }
737
738 /*
739 * Timecounters need to be updated every so often to prevent the hardware
740 * counter from overflowing. Updating also recalculates the cached values
741 * used by the get*() family of functions, so their precision depends on
742 * the update frequency.
743 */
744
745 static int tc_tick;
746 SYSCTL_INT(_kern_timecounter, OID_AUTO, tick, CTLFLAG_RD, &tc_tick, 0, "");
747
748 void
749 tc_ticktock(void)
750 {
751 static int count;
752
753 if (++count < tc_tick)
754 return;
755 count = 0;
756 tc_windup();
757 }
758
759 static void
760 inittimecounter(void *dummy)
761 {
762 u_int p;
763
764 /*
765 * Set the initial timeout to
766 * max(1, <approx. number of hardclock ticks in a millisecond>).
767 * People should probably not use the sysctl to set the timeout
768 * to smaller than its inital value, since that value is the
769 * smallest reasonable one. If they want better timestamps they
770 * should use the non-"get"* functions.
771 */
772 if (hz > 1000)
773 tc_tick = (hz + 500) / 1000;
774 else
775 tc_tick = 1;
776 p = (tc_tick * 1000000) / hz;
777 printf("Timecounters tick every %d.%03u msec\n", p / 1000, p % 1000);
778
779 /* warm up new timecounter (again) and get rolling. */
780 (void)timecounter->tc_get_timecount(timecounter);
781 (void)timecounter->tc_get_timecount(timecounter);
782 }
783
784 SYSINIT(timecounter, SI_SUB_CLOCKS, SI_ORDER_SECOND, inittimecounter, NULL)
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