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("$FreeBSD$");
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 time_t time_second = 1;
91 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, "");
105
106 #ifdef TC_COUNTERS
107 #define TC_STATS(foo) \
108 static u_int foo; \
109 SYSCTL_UINT(_kern_timecounter, OID_AUTO, foo, CTLFLAG_RD, &foo, 0, "");\
110 struct __hack
111
112 TC_STATS(nbinuptime); TC_STATS(nnanouptime); TC_STATS(nmicrouptime);
113 TC_STATS(nbintime); TC_STATS(nnanotime); TC_STATS(nmicrotime);
114 TC_STATS(ngetbinuptime); TC_STATS(ngetnanouptime); TC_STATS(ngetmicrouptime);
115 TC_STATS(ngetbintime); TC_STATS(ngetnanotime); TC_STATS(ngetmicrotime);
116 TC_STATS(nsetclock);
117
118 #define TC_COUNT(var) var++
119 #undef TC_STATS
120 #else
121 #define TC_COUNT(var) /* nothing */
122 #endif /* TC_COUNTERS */
123
124 static void tc_windup(void);
125 static void cpu_tick_calibrate(int);
126
127 static int
128 sysctl_kern_boottime(SYSCTL_HANDLER_ARGS)
129 {
130 #ifdef SCTL_MASK32
131 int tv[2];
132
133 if (req->flags & SCTL_MASK32) {
134 tv[0] = boottime.tv_sec;
135 tv[1] = boottime.tv_usec;
136 return SYSCTL_OUT(req, tv, sizeof(tv));
137 } else
138 #endif
139 return SYSCTL_OUT(req, &boottime, sizeof(boottime));
140 }
141
142 static int
143 sysctl_kern_timecounter_get(SYSCTL_HANDLER_ARGS)
144 {
145 u_int ncount;
146 struct timecounter *tc = arg1;
147
148 ncount = tc->tc_get_timecount(tc);
149 return sysctl_handle_int(oidp, &ncount, 0, req);
150 }
151
152 static int
153 sysctl_kern_timecounter_freq(SYSCTL_HANDLER_ARGS)
154 {
155 u_int64_t freq;
156 struct timecounter *tc = arg1;
157
158 freq = tc->tc_frequency;
159 return sysctl_handle_quad(oidp, &freq, 0, req);
160 }
161
162 /*
163 * Return the difference between the timehands' counter value now and what
164 * was when we copied it to the timehands' offset_count.
165 */
166 static __inline u_int
167 tc_delta(struct timehands *th)
168 {
169 struct timecounter *tc;
170
171 tc = th->th_counter;
172 return ((tc->tc_get_timecount(tc) - th->th_offset_count) &
173 tc->tc_counter_mask);
174 }
175
176 /*
177 * Functions for reading the time. We have to loop until we are sure that
178 * the timehands that we operated on was not updated under our feet. See
179 * the comment in <sys/time.h> for a description of these 12 functions.
180 */
181
182 void
183 binuptime(struct bintime *bt)
184 {
185 struct timehands *th;
186 u_int gen;
187
188 TC_COUNT(nbinuptime);
189 do {
190 th = timehands;
191 gen = th->th_generation;
192 *bt = th->th_offset;
193 bintime_addx(bt, th->th_scale * tc_delta(th));
194 } while (gen == 0 || gen != th->th_generation);
195 }
196
197 void
198 nanouptime(struct timespec *tsp)
199 {
200 struct bintime bt;
201
202 TC_COUNT(nnanouptime);
203 binuptime(&bt);
204 bintime2timespec(&bt, tsp);
205 }
206
207 void
208 microuptime(struct timeval *tvp)
209 {
210 struct bintime bt;
211
212 TC_COUNT(nmicrouptime);
213 binuptime(&bt);
214 bintime2timeval(&bt, tvp);
215 }
216
217 void
218 bintime(struct bintime *bt)
219 {
220
221 TC_COUNT(nbintime);
222 binuptime(bt);
223 bintime_add(bt, &boottimebin);
224 }
225
226 void
227 nanotime(struct timespec *tsp)
228 {
229 struct bintime bt;
230
231 TC_COUNT(nnanotime);
232 bintime(&bt);
233 bintime2timespec(&bt, tsp);
234 }
235
236 void
237 microtime(struct timeval *tvp)
238 {
239 struct bintime bt;
240
241 TC_COUNT(nmicrotime);
242 bintime(&bt);
243 bintime2timeval(&bt, tvp);
244 }
245
246 void
247 getbinuptime(struct bintime *bt)
248 {
249 struct timehands *th;
250 u_int gen;
251
252 TC_COUNT(ngetbinuptime);
253 do {
254 th = timehands;
255 gen = th->th_generation;
256 *bt = th->th_offset;
257 } while (gen == 0 || gen != th->th_generation);
258 }
259
260 void
261 getnanouptime(struct timespec *tsp)
262 {
263 struct timehands *th;
264 u_int gen;
265
266 TC_COUNT(ngetnanouptime);
267 do {
268 th = timehands;
269 gen = th->th_generation;
270 bintime2timespec(&th->th_offset, tsp);
271 } while (gen == 0 || gen != th->th_generation);
272 }
273
274 void
275 getmicrouptime(struct timeval *tvp)
276 {
277 struct timehands *th;
278 u_int gen;
279
280 TC_COUNT(ngetmicrouptime);
281 do {
282 th = timehands;
283 gen = th->th_generation;
284 bintime2timeval(&th->th_offset, tvp);
285 } while (gen == 0 || gen != th->th_generation);
286 }
287
288 void
289 getbintime(struct bintime *bt)
290 {
291 struct timehands *th;
292 u_int gen;
293
294 TC_COUNT(ngetbintime);
295 do {
296 th = timehands;
297 gen = th->th_generation;
298 *bt = th->th_offset;
299 } while (gen == 0 || gen != th->th_generation);
300 bintime_add(bt, &boottimebin);
301 }
302
303 void
304 getnanotime(struct timespec *tsp)
305 {
306 struct timehands *th;
307 u_int gen;
308
309 TC_COUNT(ngetnanotime);
310 do {
311 th = timehands;
312 gen = th->th_generation;
313 *tsp = th->th_nanotime;
314 } while (gen == 0 || gen != th->th_generation);
315 }
316
317 void
318 getmicrotime(struct timeval *tvp)
319 {
320 struct timehands *th;
321 u_int gen;
322
323 TC_COUNT(ngetmicrotime);
324 do {
325 th = timehands;
326 gen = th->th_generation;
327 *tvp = th->th_microtime;
328 } while (gen == 0 || gen != th->th_generation);
329 }
330
331 /*
332 * Initialize a new timecounter and possibly use it.
333 */
334 void
335 tc_init(struct timecounter *tc)
336 {
337 u_int u;
338 struct sysctl_oid *tc_root;
339
340 u = tc->tc_frequency / tc->tc_counter_mask;
341 /* XXX: We need some margin here, 10% is a guess */
342 u *= 11;
343 u /= 10;
344 if (u > hz && tc->tc_quality >= 0) {
345 tc->tc_quality = -2000;
346 if (bootverbose) {
347 printf("Timecounter \"%s\" frequency %ju Hz",
348 tc->tc_name, (uintmax_t)tc->tc_frequency);
349 printf(" -- Insufficient hz, needs at least %u\n", u);
350 }
351 } else if (tc->tc_quality >= 0 || bootverbose) {
352 printf("Timecounter \"%s\" frequency %ju Hz quality %d\n",
353 tc->tc_name, (uintmax_t)tc->tc_frequency,
354 tc->tc_quality);
355 }
356
357 tc->tc_next = timecounters;
358 timecounters = tc;
359 /*
360 * Set up sysctl tree for this counter.
361 */
362 tc_root = SYSCTL_ADD_NODE(NULL,
363 SYSCTL_STATIC_CHILDREN(_kern_timecounter_tc), OID_AUTO, tc->tc_name,
364 CTLFLAG_RW, 0, "timecounter description");
365 SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
366 "mask", CTLFLAG_RD, &(tc->tc_counter_mask), 0,
367 "mask for implemented bits");
368 SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
369 "counter", CTLTYPE_UINT | CTLFLAG_RD, tc, sizeof(*tc),
370 sysctl_kern_timecounter_get, "IU", "current timecounter value");
371 SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
372 "frequency", CTLTYPE_QUAD | CTLFLAG_RD, tc, sizeof(*tc),
373 sysctl_kern_timecounter_freq, "QU", "timecounter frequency");
374 SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
375 "quality", CTLFLAG_RD, &(tc->tc_quality), 0,
376 "goodness of time counter");
377 /*
378 * Never automatically use a timecounter with negative quality.
379 * Even though we run on the dummy counter, switching here may be
380 * worse since this timecounter may not be monotonous.
381 */
382 if (tc->tc_quality < 0)
383 return;
384 if (tc->tc_quality < timecounter->tc_quality)
385 return;
386 if (tc->tc_quality == timecounter->tc_quality &&
387 tc->tc_frequency < timecounter->tc_frequency)
388 return;
389 (void)tc->tc_get_timecount(tc);
390 (void)tc->tc_get_timecount(tc);
391 timecounter = tc;
392 }
393
394 /* Report the frequency of the current timecounter. */
395 u_int64_t
396 tc_getfrequency(void)
397 {
398
399 return (timehands->th_counter->tc_frequency);
400 }
401
402 /*
403 * Step our concept of UTC. This is done by modifying our estimate of
404 * when we booted.
405 * XXX: not locked.
406 */
407 void
408 tc_setclock(struct timespec *ts)
409 {
410 struct timespec tbef, taft;
411 struct bintime bt, bt2;
412
413 cpu_tick_calibrate(1);
414 TC_COUNT(nsetclock);
415 nanotime(&tbef);
416 timespec2bintime(ts, &bt);
417 binuptime(&bt2);
418 bintime_sub(&bt, &bt2);
419 bintime_add(&bt2, &boottimebin);
420 boottimebin = bt;
421 bintime2timeval(&bt, &boottime);
422
423 /* XXX fiddle all the little crinkly bits around the fiords... */
424 tc_windup();
425 nanotime(&taft);
426 if (timestepwarnings) {
427 log(LOG_INFO,
428 "Time stepped from %jd.%09ld to %jd.%09ld (%jd.%09ld)\n",
429 (intmax_t)tbef.tv_sec, tbef.tv_nsec,
430 (intmax_t)taft.tv_sec, taft.tv_nsec,
431 (intmax_t)ts->tv_sec, ts->tv_nsec);
432 }
433 cpu_tick_calibrate(1);
434 }
435
436 /*
437 * Initialize the next struct timehands in the ring and make
438 * it the active timehands. Along the way we might switch to a different
439 * timecounter and/or do seconds processing in NTP. Slightly magic.
440 */
441 static void
442 tc_windup(void)
443 {
444 struct bintime bt;
445 struct timehands *th, *tho;
446 u_int64_t scale;
447 u_int delta, ncount, ogen;
448 int i;
449 time_t t;
450
451 /*
452 * Make the next timehands a copy of the current one, but do not
453 * overwrite the generation or next pointer. While we update
454 * the contents, the generation must be zero.
455 */
456 tho = timehands;
457 th = tho->th_next;
458 ogen = th->th_generation;
459 th->th_generation = 0;
460 bcopy(tho, th, offsetof(struct timehands, th_generation));
461
462 /*
463 * Capture a timecounter delta on the current timecounter and if
464 * changing timecounters, a counter value from the new timecounter.
465 * Update the offset fields accordingly.
466 */
467 delta = tc_delta(th);
468 if (th->th_counter != timecounter)
469 ncount = timecounter->tc_get_timecount(timecounter);
470 else
471 ncount = 0;
472 th->th_offset_count += delta;
473 th->th_offset_count &= th->th_counter->tc_counter_mask;
474 bintime_addx(&th->th_offset, th->th_scale * delta);
475
476 /*
477 * Hardware latching timecounters may not generate interrupts on
478 * PPS events, so instead we poll them. There is a finite risk that
479 * the hardware might capture a count which is later than the one we
480 * got above, and therefore possibly in the next NTP second which might
481 * have a different rate than the current NTP second. It doesn't
482 * matter in practice.
483 */
484 if (tho->th_counter->tc_poll_pps)
485 tho->th_counter->tc_poll_pps(tho->th_counter);
486
487 /*
488 * Deal with NTP second processing. The for loop normally
489 * iterates at most once, but in extreme situations it might
490 * keep NTP sane if timeouts are not run for several seconds.
491 * At boot, the time step can be large when the TOD hardware
492 * has been read, so on really large steps, we call
493 * ntp_update_second only twice. We need to call it twice in
494 * case we missed a leap second.
495 */
496 bt = th->th_offset;
497 bintime_add(&bt, &boottimebin);
498 i = bt.sec - tho->th_microtime.tv_sec;
499 if (i > LARGE_STEP)
500 i = 2;
501 for (; i > 0; i--) {
502 t = bt.sec;
503 ntp_update_second(&th->th_adjustment, &bt.sec);
504 if (bt.sec != t)
505 boottimebin.sec += bt.sec - t;
506 }
507 /* Update the UTC timestamps used by the get*() functions. */
508 /* XXX shouldn't do this here. Should force non-`get' versions. */
509 bintime2timeval(&bt, &th->th_microtime);
510 bintime2timespec(&bt, &th->th_nanotime);
511
512 /* Now is a good time to change timecounters. */
513 if (th->th_counter != timecounter) {
514 th->th_counter = timecounter;
515 th->th_offset_count = ncount;
516 }
517
518 /*-
519 * Recalculate the scaling factor. We want the number of 1/2^64
520 * fractions of a second per period of the hardware counter, taking
521 * into account the th_adjustment factor which the NTP PLL/adjtime(2)
522 * processing provides us with.
523 *
524 * The th_adjustment is nanoseconds per second with 32 bit binary
525 * fraction and we want 64 bit binary fraction of second:
526 *
527 * x = a * 2^32 / 10^9 = a * 4.294967296
528 *
529 * The range of th_adjustment is +/- 5000PPM so inside a 64bit int
530 * we can only multiply by about 850 without overflowing, that
531 * leaves no suitably precise fractions for multiply before divide.
532 *
533 * Divide before multiply with a fraction of 2199/512 results in a
534 * systematic undercompensation of 10PPM of th_adjustment. On a
535 * 5000PPM adjustment this is a 0.05PPM error. This is acceptable.
536 *
537 * We happily sacrifice the lowest of the 64 bits of our result
538 * to the goddess of code clarity.
539 *
540 */
541 scale = (u_int64_t)1 << 63;
542 scale += (th->th_adjustment / 1024) * 2199;
543 scale /= th->th_counter->tc_frequency;
544 th->th_scale = scale * 2;
545
546 /*
547 * Now that the struct timehands is again consistent, set the new
548 * generation number, making sure to not make it zero.
549 */
550 if (++ogen == 0)
551 ogen = 1;
552 th->th_generation = ogen;
553
554 /* Go live with the new struct timehands. */
555 time_second = th->th_microtime.tv_sec;
556 time_uptime = th->th_offset.sec;
557 timehands = th;
558 }
559
560 /* Report or change the active timecounter hardware. */
561 static int
562 sysctl_kern_timecounter_hardware(SYSCTL_HANDLER_ARGS)
563 {
564 char newname[32];
565 struct timecounter *newtc, *tc;
566 int error;
567
568 tc = timecounter;
569 strlcpy(newname, tc->tc_name, sizeof(newname));
570
571 error = sysctl_handle_string(oidp, &newname[0], sizeof(newname), req);
572 if (error != 0 || req->newptr == NULL ||
573 strcmp(newname, tc->tc_name) == 0)
574 return (error);
575 for (newtc = timecounters; newtc != NULL; newtc = newtc->tc_next) {
576 if (strcmp(newname, newtc->tc_name) != 0)
577 continue;
578
579 /* Warm up new timecounter. */
580 (void)newtc->tc_get_timecount(newtc);
581 (void)newtc->tc_get_timecount(newtc);
582
583 timecounter = newtc;
584 return (0);
585 }
586 return (EINVAL);
587 }
588
589 SYSCTL_PROC(_kern_timecounter, OID_AUTO, hardware, CTLTYPE_STRING | CTLFLAG_RW,
590 0, 0, sysctl_kern_timecounter_hardware, "A", "");
591
592
593 /* Report or change the active timecounter hardware. */
594 static int
595 sysctl_kern_timecounter_choice(SYSCTL_HANDLER_ARGS)
596 {
597 char buf[32], *spc;
598 struct timecounter *tc;
599 int error;
600
601 spc = "";
602 error = 0;
603 for (tc = timecounters; error == 0 && tc != NULL; tc = tc->tc_next) {
604 sprintf(buf, "%s%s(%d)",
605 spc, tc->tc_name, tc->tc_quality);
606 error = SYSCTL_OUT(req, buf, strlen(buf));
607 spc = " ";
608 }
609 return (error);
610 }
611
612 SYSCTL_PROC(_kern_timecounter, OID_AUTO, choice, CTLTYPE_STRING | CTLFLAG_RD,
613 0, 0, sysctl_kern_timecounter_choice, "A", "");
614
615 /*
616 * RFC 2783 PPS-API implementation.
617 */
618
619 int
620 pps_ioctl(u_long cmd, caddr_t data, struct pps_state *pps)
621 {
622 pps_params_t *app;
623 struct pps_fetch_args *fapi;
624 #ifdef PPS_SYNC
625 struct pps_kcbind_args *kapi;
626 #endif
627
628 KASSERT(pps != NULL, ("NULL pps pointer in pps_ioctl"));
629 switch (cmd) {
630 case PPS_IOC_CREATE:
631 return (0);
632 case PPS_IOC_DESTROY:
633 return (0);
634 case PPS_IOC_SETPARAMS:
635 app = (pps_params_t *)data;
636 if (app->mode & ~pps->ppscap)
637 return (EINVAL);
638 pps->ppsparam = *app;
639 return (0);
640 case PPS_IOC_GETPARAMS:
641 app = (pps_params_t *)data;
642 *app = pps->ppsparam;
643 app->api_version = PPS_API_VERS_1;
644 return (0);
645 case PPS_IOC_GETCAP:
646 *(int*)data = pps->ppscap;
647 return (0);
648 case PPS_IOC_FETCH:
649 fapi = (struct pps_fetch_args *)data;
650 if (fapi->tsformat && fapi->tsformat != PPS_TSFMT_TSPEC)
651 return (EINVAL);
652 if (fapi->timeout.tv_sec || fapi->timeout.tv_nsec)
653 return (EOPNOTSUPP);
654 pps->ppsinfo.current_mode = pps->ppsparam.mode;
655 fapi->pps_info_buf = pps->ppsinfo;
656 return (0);
657 case PPS_IOC_KCBIND:
658 #ifdef PPS_SYNC
659 kapi = (struct pps_kcbind_args *)data;
660 /* XXX Only root should be able to do this */
661 if (kapi->tsformat && kapi->tsformat != PPS_TSFMT_TSPEC)
662 return (EINVAL);
663 if (kapi->kernel_consumer != PPS_KC_HARDPPS)
664 return (EINVAL);
665 if (kapi->edge & ~pps->ppscap)
666 return (EINVAL);
667 pps->kcmode = kapi->edge;
668 return (0);
669 #else
670 return (EOPNOTSUPP);
671 #endif
672 default:
673 return (ENOIOCTL);
674 }
675 }
676
677 void
678 pps_init(struct pps_state *pps)
679 {
680 pps->ppscap |= PPS_TSFMT_TSPEC;
681 if (pps->ppscap & PPS_CAPTUREASSERT)
682 pps->ppscap |= PPS_OFFSETASSERT;
683 if (pps->ppscap & PPS_CAPTURECLEAR)
684 pps->ppscap |= PPS_OFFSETCLEAR;
685 }
686
687 void
688 pps_capture(struct pps_state *pps)
689 {
690 struct timehands *th;
691
692 KASSERT(pps != NULL, ("NULL pps pointer in pps_capture"));
693 th = timehands;
694 pps->capgen = th->th_generation;
695 pps->capth = th;
696 pps->capcount = th->th_counter->tc_get_timecount(th->th_counter);
697 if (pps->capgen != th->th_generation)
698 pps->capgen = 0;
699 }
700
701 void
702 pps_event(struct pps_state *pps, int event)
703 {
704 struct bintime bt;
705 struct timespec ts, *tsp, *osp;
706 u_int tcount, *pcount;
707 int foff, fhard;
708 pps_seq_t *pseq;
709
710 KASSERT(pps != NULL, ("NULL pps pointer in pps_event"));
711 /* If the timecounter was wound up underneath us, bail out. */
712 if (pps->capgen == 0 || pps->capgen != pps->capth->th_generation)
713 return;
714
715 /* Things would be easier with arrays. */
716 if (event == PPS_CAPTUREASSERT) {
717 tsp = &pps->ppsinfo.assert_timestamp;
718 osp = &pps->ppsparam.assert_offset;
719 foff = pps->ppsparam.mode & PPS_OFFSETASSERT;
720 fhard = pps->kcmode & PPS_CAPTUREASSERT;
721 pcount = &pps->ppscount[0];
722 pseq = &pps->ppsinfo.assert_sequence;
723 } else {
724 tsp = &pps->ppsinfo.clear_timestamp;
725 osp = &pps->ppsparam.clear_offset;
726 foff = pps->ppsparam.mode & PPS_OFFSETCLEAR;
727 fhard = pps->kcmode & PPS_CAPTURECLEAR;
728 pcount = &pps->ppscount[1];
729 pseq = &pps->ppsinfo.clear_sequence;
730 }
731
732 /*
733 * If the timecounter changed, we cannot compare the count values, so
734 * we have to drop the rest of the PPS-stuff until the next event.
735 */
736 if (pps->ppstc != pps->capth->th_counter) {
737 pps->ppstc = pps->capth->th_counter;
738 *pcount = pps->capcount;
739 pps->ppscount[2] = pps->capcount;
740 return;
741 }
742
743 /* Convert the count to a timespec. */
744 tcount = pps->capcount - pps->capth->th_offset_count;
745 tcount &= pps->capth->th_counter->tc_counter_mask;
746 bt = pps->capth->th_offset;
747 bintime_addx(&bt, pps->capth->th_scale * tcount);
748 bintime_add(&bt, &boottimebin);
749 bintime2timespec(&bt, &ts);
750
751 /* If the timecounter was wound up underneath us, bail out. */
752 if (pps->capgen != pps->capth->th_generation)
753 return;
754
755 *pcount = pps->capcount;
756 (*pseq)++;
757 *tsp = ts;
758
759 if (foff) {
760 timespecadd(tsp, osp);
761 if (tsp->tv_nsec < 0) {
762 tsp->tv_nsec += 1000000000;
763 tsp->tv_sec -= 1;
764 }
765 }
766 #ifdef PPS_SYNC
767 if (fhard) {
768 u_int64_t scale;
769
770 /*
771 * Feed the NTP PLL/FLL.
772 * The FLL wants to know how many (hardware) nanoseconds
773 * elapsed since the previous event.
774 */
775 tcount = pps->capcount - pps->ppscount[2];
776 pps->ppscount[2] = pps->capcount;
777 tcount &= pps->capth->th_counter->tc_counter_mask;
778 scale = (u_int64_t)1 << 63;
779 scale /= pps->capth->th_counter->tc_frequency;
780 scale *= 2;
781 bt.sec = 0;
782 bt.frac = 0;
783 bintime_addx(&bt, scale * tcount);
784 bintime2timespec(&bt, &ts);
785 hardpps(tsp, ts.tv_nsec + 1000000000 * ts.tv_sec);
786 }
787 #endif
788 }
789
790 /*
791 * Timecounters need to be updated every so often to prevent the hardware
792 * counter from overflowing. Updating also recalculates the cached values
793 * used by the get*() family of functions, so their precision depends on
794 * the update frequency.
795 */
796
797 static int tc_tick;
798 SYSCTL_INT(_kern_timecounter, OID_AUTO, tick, CTLFLAG_RD, &tc_tick, 0, "");
799
800 void
801 tc_ticktock(void)
802 {
803 static int count;
804 static time_t last_calib;
805
806 if (++count < tc_tick)
807 return;
808 count = 0;
809 tc_windup();
810 if (time_uptime != last_calib && !(time_uptime & 0xf)) {
811 cpu_tick_calibrate(0);
812 last_calib = time_uptime;
813 }
814 }
815
816 static void
817 inittimecounter(void *dummy)
818 {
819 u_int p;
820
821 /*
822 * Set the initial timeout to
823 * max(1, <approx. number of hardclock ticks in a millisecond>).
824 * People should probably not use the sysctl to set the timeout
825 * to smaller than its inital value, since that value is the
826 * smallest reasonable one. If they want better timestamps they
827 * should use the non-"get"* functions.
828 */
829 if (hz > 1000)
830 tc_tick = (hz + 500) / 1000;
831 else
832 tc_tick = 1;
833 p = (tc_tick * 1000000) / hz;
834 printf("Timecounters tick every %d.%03u msec\n", p / 1000, p % 1000);
835
836 /* warm up new timecounter (again) and get rolling. */
837 (void)timecounter->tc_get_timecount(timecounter);
838 (void)timecounter->tc_get_timecount(timecounter);
839 }
840
841 SYSINIT(timecounter, SI_SUB_CLOCKS, SI_ORDER_SECOND, inittimecounter, NULL);
842
843 /* Cpu tick handling -------------------------------------------------*/
844
845 static int cpu_tick_variable;
846 static uint64_t cpu_tick_frequency;
847
848 static uint64_t
849 tc_cpu_ticks(void)
850 {
851 static uint64_t base;
852 static unsigned last;
853 unsigned u;
854 struct timecounter *tc;
855
856 tc = timehands->th_counter;
857 u = tc->tc_get_timecount(tc) & tc->tc_counter_mask;
858 if (u < last)
859 base += (uint64_t)tc->tc_counter_mask + 1;
860 last = u;
861 return (u + base);
862 }
863
864 /*
865 * This function gets called ever 16 seconds on only one designated
866 * CPU in the system from hardclock() via tc_ticktock().
867 *
868 * Whenever the real time clock is stepped we get called with reset=1
869 * to make sure we handle suspend/resume and similar events correctly.
870 */
871
872 static void
873 cpu_tick_calibrate(int reset)
874 {
875 static uint64_t c_last;
876 uint64_t c_this, c_delta;
877 static struct bintime t_last;
878 struct bintime t_this, t_delta;
879 uint32_t divi;
880
881 if (reset) {
882 /* The clock was stepped, abort & reset */
883 t_last.sec = 0;
884 return;
885 }
886
887 /* we don't calibrate fixed rate cputicks */
888 if (!cpu_tick_variable)
889 return;
890
891 getbinuptime(&t_this);
892 c_this = cpu_ticks();
893 if (t_last.sec != 0) {
894 c_delta = c_this - c_last;
895 t_delta = t_this;
896 bintime_sub(&t_delta, &t_last);
897 /*
898 * Validate that 16 +/- 1/256 seconds passed.
899 * After division by 16 this gives us a precision of
900 * roughly 250PPM which is sufficient
901 */
902 if (t_delta.sec > 16 || (
903 t_delta.sec == 16 && t_delta.frac >= (0x01LL << 56))) {
904 /* too long */
905 if (bootverbose)
906 printf("t_delta %ju.%016jx too long\n",
907 (uintmax_t)t_delta.sec,
908 (uintmax_t)t_delta.frac);
909 } else if (t_delta.sec < 15 ||
910 (t_delta.sec == 15 && t_delta.frac <= (0xffLL << 56))) {
911 /* too short */
912 if (bootverbose)
913 printf("t_delta %ju.%016jx too short\n",
914 (uintmax_t)t_delta.sec,
915 (uintmax_t)t_delta.frac);
916 } else {
917 /* just right */
918 /*
919 * Headroom:
920 * 2^(64-20) / 16[s] =
921 * 2^(44) / 16[s] =
922 * 17.592.186.044.416 / 16 =
923 * 1.099.511.627.776 [Hz]
924 */
925 divi = t_delta.sec << 20;
926 divi |= t_delta.frac >> (64 - 20);
927 c_delta <<= 20;
928 c_delta /= divi;
929 if (c_delta > cpu_tick_frequency) {
930 if (0 && bootverbose)
931 printf("cpu_tick increased to %ju Hz\n",
932 c_delta);
933 cpu_tick_frequency = c_delta;
934 }
935 }
936 }
937 c_last = c_this;
938 t_last = t_this;
939 }
940
941 void
942 set_cputicker(cpu_tick_f *func, uint64_t freq, unsigned var)
943 {
944
945 if (func == NULL) {
946 cpu_ticks = tc_cpu_ticks;
947 } else {
948 cpu_tick_frequency = freq;
949 cpu_tick_variable = var;
950 cpu_ticks = func;
951 }
952 }
953
954 uint64_t
955 cpu_tickrate(void)
956 {
957
958 if (cpu_ticks == tc_cpu_ticks)
959 return (tc_getfrequency());
960 return (cpu_tick_frequency);
961 }
962
963 /*
964 * We need to be slightly careful converting cputicks to microseconds.
965 * There is plenty of margin in 64 bits of microseconds (half a million
966 * years) and in 64 bits at 4 GHz (146 years), but if we do a multiply
967 * before divide conversion (to retain precision) we find that the
968 * margin shrinks to 1.5 hours (one millionth of 146y).
969 * With a three prong approach we never lose significant bits, no
970 * matter what the cputick rate and length of timeinterval is.
971 */
972
973 uint64_t
974 cputick2usec(uint64_t tick)
975 {
976
977 if (tick > 18446744073709551LL) /* floor(2^64 / 1000) */
978 return (tick / (cpu_tickrate() / 1000000LL));
979 else if (tick > 18446744073709LL) /* floor(2^64 / 1000000) */
980 return ((tick * 1000LL) / (cpu_tickrate() / 1000LL));
981 else
982 return ((tick * 1000000LL) / cpu_tickrate());
983 }
984
985 cpu_tick_f *cpu_ticks = tc_cpu_ticks;
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