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/8.4/sys/kern/kern_tc.c 247556 2013-03-01 17:10:52Z jhb $");
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 static 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 volatile time_t time_second = 1;
91 volatile time_t time_uptime = 1;
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 SYSCTL_NODE(_kern_timecounter, OID_AUTO, tc, CTLFLAG_RW, 0, "");
101
102 static int timestepwarnings;
103 SYSCTL_INT(_kern_timecounter, OID_AUTO, stepwarnings, CTLFLAG_RW,
104 ×tepwarnings, 0, "Log time steps");
105
106 static void tc_windup(void);
107 static void cpu_tick_calibrate(int);
108
109 static int
110 sysctl_kern_boottime(SYSCTL_HANDLER_ARGS)
111 {
112 #ifdef SCTL_MASK32
113 int tv[2];
114
115 if (req->flags & SCTL_MASK32) {
116 tv[0] = boottime.tv_sec;
117 tv[1] = boottime.tv_usec;
118 return SYSCTL_OUT(req, tv, sizeof(tv));
119 } else
120 #endif
121 return SYSCTL_OUT(req, &boottime, sizeof(boottime));
122 }
123
124 static int
125 sysctl_kern_timecounter_get(SYSCTL_HANDLER_ARGS)
126 {
127 u_int ncount;
128 struct timecounter *tc = arg1;
129
130 ncount = tc->tc_get_timecount(tc);
131 return sysctl_handle_int(oidp, &ncount, 0, req);
132 }
133
134 static int
135 sysctl_kern_timecounter_freq(SYSCTL_HANDLER_ARGS)
136 {
137 u_int64_t freq;
138 struct timecounter *tc = arg1;
139
140 freq = tc->tc_frequency;
141 return sysctl_handle_quad(oidp, &freq, 0, req);
142 }
143
144 /*
145 * Return the difference between the timehands' counter value now and what
146 * was when we copied it to the timehands' offset_count.
147 */
148 static __inline u_int
149 tc_delta(struct timehands *th)
150 {
151 struct timecounter *tc;
152
153 tc = th->th_counter;
154 return ((tc->tc_get_timecount(tc) - th->th_offset_count) &
155 tc->tc_counter_mask);
156 }
157
158 /*
159 * Functions for reading the time. We have to loop until we are sure that
160 * the timehands that we operated on was not updated under our feet. See
161 * the comment in <sys/time.h> for a description of these 12 functions.
162 */
163
164 void
165 binuptime(struct bintime *bt)
166 {
167 struct timehands *th;
168 u_int gen;
169
170 do {
171 th = timehands;
172 gen = th->th_generation;
173 *bt = th->th_offset;
174 bintime_addx(bt, th->th_scale * tc_delta(th));
175 } while (gen == 0 || gen != th->th_generation);
176 }
177
178 void
179 nanouptime(struct timespec *tsp)
180 {
181 struct bintime bt;
182
183 binuptime(&bt);
184 bintime2timespec(&bt, tsp);
185 }
186
187 void
188 microuptime(struct timeval *tvp)
189 {
190 struct bintime bt;
191
192 binuptime(&bt);
193 bintime2timeval(&bt, tvp);
194 }
195
196 void
197 bintime(struct bintime *bt)
198 {
199
200 binuptime(bt);
201 bintime_add(bt, &boottimebin);
202 }
203
204 void
205 nanotime(struct timespec *tsp)
206 {
207 struct bintime bt;
208
209 bintime(&bt);
210 bintime2timespec(&bt, tsp);
211 }
212
213 void
214 microtime(struct timeval *tvp)
215 {
216 struct bintime bt;
217
218 bintime(&bt);
219 bintime2timeval(&bt, tvp);
220 }
221
222 void
223 getbinuptime(struct bintime *bt)
224 {
225 struct timehands *th;
226 u_int gen;
227
228 do {
229 th = timehands;
230 gen = th->th_generation;
231 *bt = th->th_offset;
232 } while (gen == 0 || gen != th->th_generation);
233 }
234
235 void
236 getnanouptime(struct timespec *tsp)
237 {
238 struct timehands *th;
239 u_int gen;
240
241 do {
242 th = timehands;
243 gen = th->th_generation;
244 bintime2timespec(&th->th_offset, tsp);
245 } while (gen == 0 || gen != th->th_generation);
246 }
247
248 void
249 getmicrouptime(struct timeval *tvp)
250 {
251 struct timehands *th;
252 u_int gen;
253
254 do {
255 th = timehands;
256 gen = th->th_generation;
257 bintime2timeval(&th->th_offset, tvp);
258 } while (gen == 0 || gen != th->th_generation);
259 }
260
261 void
262 getbintime(struct bintime *bt)
263 {
264 struct timehands *th;
265 u_int gen;
266
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 do {
282 th = timehands;
283 gen = th->th_generation;
284 *tsp = th->th_nanotime;
285 } while (gen == 0 || gen != th->th_generation);
286 }
287
288 void
289 getmicrotime(struct timeval *tvp)
290 {
291 struct timehands *th;
292 u_int gen;
293
294 do {
295 th = timehands;
296 gen = th->th_generation;
297 *tvp = th->th_microtime;
298 } while (gen == 0 || gen != th->th_generation);
299 }
300
301 /*
302 * Initialize a new timecounter and possibly use it.
303 */
304 void
305 tc_init(struct timecounter *tc)
306 {
307 u_int u;
308 struct sysctl_oid *tc_root;
309
310 u = tc->tc_frequency / tc->tc_counter_mask;
311 /* XXX: We need some margin here, 10% is a guess */
312 u *= 11;
313 u /= 10;
314 if (u > hz && tc->tc_quality >= 0) {
315 tc->tc_quality = -2000;
316 if (bootverbose) {
317 printf("Timecounter \"%s\" frequency %ju Hz",
318 tc->tc_name, (uintmax_t)tc->tc_frequency);
319 printf(" -- Insufficient hz, needs at least %u\n", u);
320 }
321 } else if (tc->tc_quality >= 0 || bootverbose) {
322 printf("Timecounter \"%s\" frequency %ju Hz quality %d\n",
323 tc->tc_name, (uintmax_t)tc->tc_frequency,
324 tc->tc_quality);
325 }
326
327 tc->tc_next = timecounters;
328 timecounters = tc;
329 /*
330 * Set up sysctl tree for this counter.
331 */
332 tc_root = SYSCTL_ADD_NODE(NULL,
333 SYSCTL_STATIC_CHILDREN(_kern_timecounter_tc), OID_AUTO, tc->tc_name,
334 CTLFLAG_RW, 0, "timecounter description");
335 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
336 "mask", CTLFLAG_RD, &(tc->tc_counter_mask), 0,
337 "mask for implemented bits");
338 SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
339 "counter", CTLTYPE_UINT | CTLFLAG_RD, tc, sizeof(*tc),
340 sysctl_kern_timecounter_get, "IU", "current timecounter value");
341 SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
342 "frequency", CTLTYPE_QUAD | CTLFLAG_RD, tc, sizeof(*tc),
343 sysctl_kern_timecounter_freq, "QU", "timecounter frequency");
344 SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
345 "quality", CTLFLAG_RD, &(tc->tc_quality), 0,
346 "goodness of time counter");
347 /*
348 * Never automatically use a timecounter with negative quality.
349 * Even though we run on the dummy counter, switching here may be
350 * worse since this timecounter may not be monotonous.
351 */
352 if (tc->tc_quality < 0)
353 return;
354 if (tc->tc_quality < timecounter->tc_quality)
355 return;
356 if (tc->tc_quality == timecounter->tc_quality &&
357 tc->tc_frequency < timecounter->tc_frequency)
358 return;
359 (void)tc->tc_get_timecount(tc);
360 (void)tc->tc_get_timecount(tc);
361 timecounter = tc;
362 }
363
364 /* Report the frequency of the current timecounter. */
365 u_int64_t
366 tc_getfrequency(void)
367 {
368
369 return (timehands->th_counter->tc_frequency);
370 }
371
372 /*
373 * Step our concept of UTC. This is done by modifying our estimate of
374 * when we booted.
375 * XXX: not locked.
376 */
377 void
378 tc_setclock(struct timespec *ts)
379 {
380 struct timespec tbef, taft;
381 struct bintime bt, bt2;
382
383 cpu_tick_calibrate(1);
384 nanotime(&tbef);
385 timespec2bintime(ts, &bt);
386 binuptime(&bt2);
387 bintime_sub(&bt, &bt2);
388 bintime_add(&bt2, &boottimebin);
389 boottimebin = bt;
390 bintime2timeval(&bt, &boottime);
391
392 /* XXX fiddle all the little crinkly bits around the fiords... */
393 tc_windup();
394 nanotime(&taft);
395 if (timestepwarnings) {
396 log(LOG_INFO,
397 "Time stepped from %jd.%09ld to %jd.%09ld (%jd.%09ld)\n",
398 (intmax_t)tbef.tv_sec, tbef.tv_nsec,
399 (intmax_t)taft.tv_sec, taft.tv_nsec,
400 (intmax_t)ts->tv_sec, ts->tv_nsec);
401 }
402 cpu_tick_calibrate(1);
403 }
404
405 /*
406 * Initialize the next struct timehands in the ring and make
407 * it the active timehands. Along the way we might switch to a different
408 * timecounter and/or do seconds processing in NTP. Slightly magic.
409 */
410 static void
411 tc_windup(void)
412 {
413 struct bintime bt;
414 struct timehands *th, *tho;
415 u_int64_t scale;
416 u_int delta, ncount, ogen;
417 int i;
418 time_t t;
419
420 /*
421 * Make the next timehands a copy of the current one, but do not
422 * overwrite the generation or next pointer. While we update
423 * the contents, the generation must be zero.
424 */
425 tho = timehands;
426 th = tho->th_next;
427 ogen = th->th_generation;
428 th->th_generation = 0;
429 bcopy(tho, th, offsetof(struct timehands, th_generation));
430
431 /*
432 * Capture a timecounter delta on the current timecounter and if
433 * changing timecounters, a counter value from the new timecounter.
434 * Update the offset fields accordingly.
435 */
436 delta = tc_delta(th);
437 if (th->th_counter != timecounter)
438 ncount = timecounter->tc_get_timecount(timecounter);
439 else
440 ncount = 0;
441 th->th_offset_count += delta;
442 th->th_offset_count &= th->th_counter->tc_counter_mask;
443 while (delta > th->th_counter->tc_frequency) {
444 /* Eat complete unadjusted seconds. */
445 delta -= th->th_counter->tc_frequency;
446 th->th_offset.sec++;
447 }
448 if ((delta > th->th_counter->tc_frequency / 2) &&
449 (th->th_scale * delta < ((uint64_t)1 << 63))) {
450 /* The product th_scale * delta just barely overflows. */
451 th->th_offset.sec++;
452 }
453 bintime_addx(&th->th_offset, th->th_scale * delta);
454
455 /*
456 * Hardware latching timecounters may not generate interrupts on
457 * PPS events, so instead we poll them. There is a finite risk that
458 * the hardware might capture a count which is later than the one we
459 * got above, and therefore possibly in the next NTP second which might
460 * have a different rate than the current NTP second. It doesn't
461 * matter in practice.
462 */
463 if (tho->th_counter->tc_poll_pps)
464 tho->th_counter->tc_poll_pps(tho->th_counter);
465
466 /*
467 * Deal with NTP second processing. The for loop normally
468 * iterates at most once, but in extreme situations it might
469 * keep NTP sane if timeouts are not run for several seconds.
470 * At boot, the time step can be large when the TOD hardware
471 * has been read, so on really large steps, we call
472 * ntp_update_second only twice. We need to call it twice in
473 * case we missed a leap second.
474 */
475 bt = th->th_offset;
476 bintime_add(&bt, &boottimebin);
477 i = bt.sec - tho->th_microtime.tv_sec;
478 if (i > LARGE_STEP)
479 i = 2;
480 for (; i > 0; i--) {
481 t = bt.sec;
482 ntp_update_second(&th->th_adjustment, &bt.sec);
483 if (bt.sec != t)
484 boottimebin.sec += bt.sec - t;
485 }
486 /* Update the UTC timestamps used by the get*() functions. */
487 /* XXX shouldn't do this here. Should force non-`get' versions. */
488 bintime2timeval(&bt, &th->th_microtime);
489 bintime2timespec(&bt, &th->th_nanotime);
490
491 /* Now is a good time to change timecounters. */
492 if (th->th_counter != timecounter) {
493 th->th_counter = timecounter;
494 th->th_offset_count = ncount;
495 }
496
497 /*-
498 * Recalculate the scaling factor. We want the number of 1/2^64
499 * fractions of a second per period of the hardware counter, taking
500 * into account the th_adjustment factor which the NTP PLL/adjtime(2)
501 * processing provides us with.
502 *
503 * The th_adjustment is nanoseconds per second with 32 bit binary
504 * fraction and we want 64 bit binary fraction of second:
505 *
506 * x = a * 2^32 / 10^9 = a * 4.294967296
507 *
508 * The range of th_adjustment is +/- 5000PPM so inside a 64bit int
509 * we can only multiply by about 850 without overflowing, that
510 * leaves no suitably precise fractions for multiply before divide.
511 *
512 * Divide before multiply with a fraction of 2199/512 results in a
513 * systematic undercompensation of 10PPM of th_adjustment. On a
514 * 5000PPM adjustment this is a 0.05PPM error. This is acceptable.
515 *
516 * We happily sacrifice the lowest of the 64 bits of our result
517 * to the goddess of code clarity.
518 *
519 */
520 scale = (u_int64_t)1 << 63;
521 scale += (th->th_adjustment / 1024) * 2199;
522 scale /= th->th_counter->tc_frequency;
523 th->th_scale = scale * 2;
524
525 /*
526 * Now that the struct timehands is again consistent, set the new
527 * generation number, making sure to not make it zero.
528 */
529 if (++ogen == 0)
530 ogen = 1;
531 th->th_generation = ogen;
532
533 /* Go live with the new struct timehands. */
534 time_second = th->th_microtime.tv_sec;
535 time_uptime = th->th_offset.sec;
536 timehands = th;
537 }
538
539 /* Report or change the active timecounter hardware. */
540 static int
541 sysctl_kern_timecounter_hardware(SYSCTL_HANDLER_ARGS)
542 {
543 char newname[32];
544 struct timecounter *newtc, *tc;
545 int error;
546
547 tc = timecounter;
548 strlcpy(newname, tc->tc_name, sizeof(newname));
549
550 error = sysctl_handle_string(oidp, &newname[0], sizeof(newname), req);
551 if (error != 0 || req->newptr == NULL ||
552 strcmp(newname, tc->tc_name) == 0)
553 return (error);
554 for (newtc = timecounters; newtc != NULL; newtc = newtc->tc_next) {
555 if (strcmp(newname, newtc->tc_name) != 0)
556 continue;
557
558 /* Warm up new timecounter. */
559 (void)newtc->tc_get_timecount(newtc);
560 (void)newtc->tc_get_timecount(newtc);
561
562 timecounter = newtc;
563 return (0);
564 }
565 return (EINVAL);
566 }
567
568 SYSCTL_PROC(_kern_timecounter, OID_AUTO, hardware, CTLTYPE_STRING | CTLFLAG_RW,
569 0, 0, sysctl_kern_timecounter_hardware, "A",
570 "Timecounter hardware selected");
571
572
573 /* Report or change the active timecounter hardware. */
574 static int
575 sysctl_kern_timecounter_choice(SYSCTL_HANDLER_ARGS)
576 {
577 char buf[32], *spc;
578 struct timecounter *tc;
579 int error;
580
581 spc = "";
582 error = 0;
583 for (tc = timecounters; error == 0 && tc != NULL; tc = tc->tc_next) {
584 sprintf(buf, "%s%s(%d)",
585 spc, tc->tc_name, tc->tc_quality);
586 error = SYSCTL_OUT(req, buf, strlen(buf));
587 spc = " ";
588 }
589 return (error);
590 }
591
592 SYSCTL_PROC(_kern_timecounter, OID_AUTO, choice, CTLTYPE_STRING | CTLFLAG_RD,
593 0, 0, sysctl_kern_timecounter_choice, "A", "Timecounter hardware detected");
594
595 /*
596 * RFC 2783 PPS-API implementation.
597 */
598
599 int
600 pps_ioctl(u_long cmd, caddr_t data, struct pps_state *pps)
601 {
602 pps_params_t *app;
603 struct pps_fetch_args *fapi;
604 #ifdef PPS_SYNC
605 struct pps_kcbind_args *kapi;
606 #endif
607
608 KASSERT(pps != NULL, ("NULL pps pointer in pps_ioctl"));
609 switch (cmd) {
610 case PPS_IOC_CREATE:
611 return (0);
612 case PPS_IOC_DESTROY:
613 return (0);
614 case PPS_IOC_SETPARAMS:
615 app = (pps_params_t *)data;
616 if (app->mode & ~pps->ppscap)
617 return (EINVAL);
618 pps->ppsparam = *app;
619 return (0);
620 case PPS_IOC_GETPARAMS:
621 app = (pps_params_t *)data;
622 *app = pps->ppsparam;
623 app->api_version = PPS_API_VERS_1;
624 return (0);
625 case PPS_IOC_GETCAP:
626 *(int*)data = pps->ppscap;
627 return (0);
628 case PPS_IOC_FETCH:
629 fapi = (struct pps_fetch_args *)data;
630 if (fapi->tsformat && fapi->tsformat != PPS_TSFMT_TSPEC)
631 return (EINVAL);
632 if (fapi->timeout.tv_sec || fapi->timeout.tv_nsec)
633 return (EOPNOTSUPP);
634 pps->ppsinfo.current_mode = pps->ppsparam.mode;
635 fapi->pps_info_buf = pps->ppsinfo;
636 return (0);
637 case PPS_IOC_KCBIND:
638 #ifdef PPS_SYNC
639 kapi = (struct pps_kcbind_args *)data;
640 /* XXX Only root should be able to do this */
641 if (kapi->tsformat && kapi->tsformat != PPS_TSFMT_TSPEC)
642 return (EINVAL);
643 if (kapi->kernel_consumer != PPS_KC_HARDPPS)
644 return (EINVAL);
645 if (kapi->edge & ~pps->ppscap)
646 return (EINVAL);
647 pps->kcmode = kapi->edge;
648 return (0);
649 #else
650 return (EOPNOTSUPP);
651 #endif
652 default:
653 return (ENOIOCTL);
654 }
655 }
656
657 void
658 pps_init(struct pps_state *pps)
659 {
660 pps->ppscap |= PPS_TSFMT_TSPEC;
661 if (pps->ppscap & PPS_CAPTUREASSERT)
662 pps->ppscap |= PPS_OFFSETASSERT;
663 if (pps->ppscap & PPS_CAPTURECLEAR)
664 pps->ppscap |= PPS_OFFSETCLEAR;
665 }
666
667 void
668 pps_capture(struct pps_state *pps)
669 {
670 struct timehands *th;
671
672 KASSERT(pps != NULL, ("NULL pps pointer in pps_capture"));
673 th = timehands;
674 pps->capgen = th->th_generation;
675 pps->capth = th;
676 pps->capcount = th->th_counter->tc_get_timecount(th->th_counter);
677 if (pps->capgen != th->th_generation)
678 pps->capgen = 0;
679 }
680
681 void
682 pps_event(struct pps_state *pps, int event)
683 {
684 struct bintime bt;
685 struct timespec ts, *tsp, *osp;
686 u_int tcount, *pcount;
687 int foff, fhard;
688 pps_seq_t *pseq;
689
690 KASSERT(pps != NULL, ("NULL pps pointer in pps_event"));
691 /* If the timecounter was wound up underneath us, bail out. */
692 if (pps->capgen == 0 || pps->capgen != pps->capth->th_generation)
693 return;
694
695 /* Things would be easier with arrays. */
696 if (event == PPS_CAPTUREASSERT) {
697 tsp = &pps->ppsinfo.assert_timestamp;
698 osp = &pps->ppsparam.assert_offset;
699 foff = pps->ppsparam.mode & PPS_OFFSETASSERT;
700 fhard = pps->kcmode & PPS_CAPTUREASSERT;
701 pcount = &pps->ppscount[0];
702 pseq = &pps->ppsinfo.assert_sequence;
703 } else {
704 tsp = &pps->ppsinfo.clear_timestamp;
705 osp = &pps->ppsparam.clear_offset;
706 foff = pps->ppsparam.mode & PPS_OFFSETCLEAR;
707 fhard = pps->kcmode & PPS_CAPTURECLEAR;
708 pcount = &pps->ppscount[1];
709 pseq = &pps->ppsinfo.clear_sequence;
710 }
711
712 /*
713 * If the timecounter changed, we cannot compare the count values, so
714 * we have to drop the rest of the PPS-stuff until the next event.
715 */
716 if (pps->ppstc != pps->capth->th_counter) {
717 pps->ppstc = pps->capth->th_counter;
718 *pcount = pps->capcount;
719 pps->ppscount[2] = pps->capcount;
720 return;
721 }
722
723 /* Convert the count to a timespec. */
724 tcount = pps->capcount - pps->capth->th_offset_count;
725 tcount &= pps->capth->th_counter->tc_counter_mask;
726 bt = pps->capth->th_offset;
727 bintime_addx(&bt, pps->capth->th_scale * tcount);
728 bintime_add(&bt, &boottimebin);
729 bintime2timespec(&bt, &ts);
730
731 /* If the timecounter was wound up underneath us, bail out. */
732 if (pps->capgen != pps->capth->th_generation)
733 return;
734
735 *pcount = pps->capcount;
736 (*pseq)++;
737 *tsp = ts;
738
739 if (foff) {
740 timespecadd(tsp, osp);
741 if (tsp->tv_nsec < 0) {
742 tsp->tv_nsec += 1000000000;
743 tsp->tv_sec -= 1;
744 }
745 }
746 #ifdef PPS_SYNC
747 if (fhard) {
748 u_int64_t scale;
749
750 /*
751 * Feed the NTP PLL/FLL.
752 * The FLL wants to know how many (hardware) nanoseconds
753 * elapsed since the previous event.
754 */
755 tcount = pps->capcount - pps->ppscount[2];
756 pps->ppscount[2] = pps->capcount;
757 tcount &= pps->capth->th_counter->tc_counter_mask;
758 scale = (u_int64_t)1 << 63;
759 scale /= pps->capth->th_counter->tc_frequency;
760 scale *= 2;
761 bt.sec = 0;
762 bt.frac = 0;
763 bintime_addx(&bt, scale * tcount);
764 bintime2timespec(&bt, &ts);
765 hardpps(tsp, ts.tv_nsec + 1000000000 * ts.tv_sec);
766 }
767 #endif
768 }
769
770 /*
771 * Timecounters need to be updated every so often to prevent the hardware
772 * counter from overflowing. Updating also recalculates the cached values
773 * used by the get*() family of functions, so their precision depends on
774 * the update frequency.
775 */
776
777 static int tc_tick;
778 SYSCTL_INT(_kern_timecounter, OID_AUTO, tick, CTLFLAG_RD, &tc_tick, 0,
779 "Approximate number of hardclock ticks in a millisecond");
780
781 void
782 tc_ticktock(void)
783 {
784 static int count;
785 static time_t last_calib;
786
787 if (++count < tc_tick)
788 return;
789 count = 0;
790 tc_windup();
791 if (time_uptime != last_calib && !(time_uptime & 0xf)) {
792 cpu_tick_calibrate(0);
793 last_calib = time_uptime;
794 }
795 }
796
797 static void
798 inittimecounter(void *dummy)
799 {
800 u_int p;
801
802 /*
803 * Set the initial timeout to
804 * max(1, <approx. number of hardclock ticks in a millisecond>).
805 * People should probably not use the sysctl to set the timeout
806 * to smaller than its inital value, since that value is the
807 * smallest reasonable one. If they want better timestamps they
808 * should use the non-"get"* functions.
809 */
810 if (hz > 1000)
811 tc_tick = (hz + 500) / 1000;
812 else
813 tc_tick = 1;
814 p = (tc_tick * 1000000) / hz;
815 printf("Timecounters tick every %d.%03u msec\n", p / 1000, p % 1000);
816
817 /* warm up new timecounter (again) and get rolling. */
818 (void)timecounter->tc_get_timecount(timecounter);
819 (void)timecounter->tc_get_timecount(timecounter);
820 }
821
822 SYSINIT(timecounter, SI_SUB_CLOCKS, SI_ORDER_SECOND, inittimecounter, NULL);
823
824 /* Cpu tick handling -------------------------------------------------*/
825
826 static int cpu_tick_variable;
827 static uint64_t cpu_tick_frequency;
828
829 static uint64_t
830 tc_cpu_ticks(void)
831 {
832 static uint64_t base;
833 static unsigned last;
834 unsigned u;
835 struct timecounter *tc;
836
837 tc = timehands->th_counter;
838 u = tc->tc_get_timecount(tc) & tc->tc_counter_mask;
839 if (u < last)
840 base += (uint64_t)tc->tc_counter_mask + 1;
841 last = u;
842 return (u + base);
843 }
844
845 /*
846 * This function gets called every 16 seconds on only one designated
847 * CPU in the system from hardclock() via tc_ticktock().
848 *
849 * Whenever the real time clock is stepped we get called with reset=1
850 * to make sure we handle suspend/resume and similar events correctly.
851 */
852
853 static void
854 cpu_tick_calibrate(int reset)
855 {
856 static uint64_t c_last;
857 uint64_t c_this, c_delta;
858 static struct bintime t_last;
859 struct bintime t_this, t_delta;
860 uint32_t divi;
861
862 if (reset) {
863 /* The clock was stepped, abort & reset */
864 t_last.sec = 0;
865 return;
866 }
867
868 /* we don't calibrate fixed rate cputicks */
869 if (!cpu_tick_variable)
870 return;
871
872 getbinuptime(&t_this);
873 c_this = cpu_ticks();
874 if (t_last.sec != 0) {
875 c_delta = c_this - c_last;
876 t_delta = t_this;
877 bintime_sub(&t_delta, &t_last);
878 /*
879 * Validate that 16 +/- 1/256 seconds passed.
880 * After division by 16 this gives us a precision of
881 * roughly 250PPM which is sufficient
882 */
883 if (t_delta.sec > 16 || (
884 t_delta.sec == 16 && t_delta.frac >= (0x01LL << 56))) {
885 /* too long */
886 if (bootverbose)
887 printf("t_delta %ju.%016jx too long\n",
888 (uintmax_t)t_delta.sec,
889 (uintmax_t)t_delta.frac);
890 } else if (t_delta.sec < 15 ||
891 (t_delta.sec == 15 && t_delta.frac <= (0xffLL << 56))) {
892 /* too short */
893 if (bootverbose)
894 printf("t_delta %ju.%016jx too short\n",
895 (uintmax_t)t_delta.sec,
896 (uintmax_t)t_delta.frac);
897 } else {
898 /* just right */
899 /*
900 * Headroom:
901 * 2^(64-20) / 16[s] =
902 * 2^(44) / 16[s] =
903 * 17.592.186.044.416 / 16 =
904 * 1.099.511.627.776 [Hz]
905 */
906 divi = t_delta.sec << 20;
907 divi |= t_delta.frac >> (64 - 20);
908 c_delta <<= 20;
909 c_delta /= divi;
910 if (c_delta > cpu_tick_frequency) {
911 if (0 && bootverbose)
912 printf("cpu_tick increased to %ju Hz\n",
913 c_delta);
914 cpu_tick_frequency = c_delta;
915 }
916 }
917 }
918 c_last = c_this;
919 t_last = t_this;
920 }
921
922 void
923 set_cputicker(cpu_tick_f *func, uint64_t freq, unsigned var)
924 {
925
926 if (func == NULL) {
927 cpu_ticks = tc_cpu_ticks;
928 } else {
929 cpu_tick_frequency = freq;
930 cpu_tick_variable = var;
931 cpu_ticks = func;
932 }
933 }
934
935 uint64_t
936 cpu_tickrate(void)
937 {
938
939 if (cpu_ticks == tc_cpu_ticks)
940 return (tc_getfrequency());
941 return (cpu_tick_frequency);
942 }
943
944 /*
945 * We need to be slightly careful converting cputicks to microseconds.
946 * There is plenty of margin in 64 bits of microseconds (half a million
947 * years) and in 64 bits at 4 GHz (146 years), but if we do a multiply
948 * before divide conversion (to retain precision) we find that the
949 * margin shrinks to 1.5 hours (one millionth of 146y).
950 * With a three prong approach we never lose significant bits, no
951 * matter what the cputick rate and length of timeinterval is.
952 */
953
954 uint64_t
955 cputick2usec(uint64_t tick)
956 {
957
958 if (tick > 18446744073709551LL) /* floor(2^64 / 1000) */
959 return (tick / (cpu_tickrate() / 1000000LL));
960 else if (tick > 18446744073709LL) /* floor(2^64 / 1000000) */
961 return ((tick * 1000LL) / (cpu_tickrate() / 1000LL));
962 else
963 return ((tick * 1000000LL) / cpu_tickrate());
964 }
965
966 cpu_tick_f *cpu_ticks = tc_cpu_ticks;
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