kern_tc.c revision 156270
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: head/sys/kern/kern_tc.c 156270 2006-03-04 06:06:43Z 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 38static u_int 39dummy_get_timecount(struct timecounter *tc) 40{ 41 static u_int now; 42 43 return (++now); 44} 45 46static struct timecounter dummy_timecounter = { 47 dummy_get_timecount, 0, ~0u, 1000000, "dummy", -1000000 48}; 49 50struct 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 64static struct timehands th0; 65static struct timehands th9 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th0}; 66static struct timehands th8 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th9}; 67static struct timehands th7 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th8}; 68static struct timehands th6 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th7}; 69static struct timehands th5 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th6}; 70static struct timehands th4 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th5}; 71static struct timehands th3 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th4}; 72static struct timehands th2 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th3}; 73static struct timehands th1 = { NULL, 0, 0, 0, {0, 0}, {0, 0}, {0, 0}, 0, &th2}; 74static 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 86static struct timehands *volatile timehands = &th0; 87struct timecounter *timecounter = &dummy_timecounter; 88static struct timecounter *timecounters = &dummy_timecounter; 89 90time_t time_second = 1; 91time_t time_uptime = 1; 92 93static struct bintime boottimebin; 94struct timeval boottime; 95static int sysctl_kern_boottime(SYSCTL_HANDLER_ARGS); 96SYSCTL_PROC(_kern, KERN_BOOTTIME, boottime, CTLTYPE_STRUCT|CTLFLAG_RD, 97 NULL, 0, sysctl_kern_boottime, "S,timeval", "System boottime"); 98 99SYSCTL_NODE(_kern, OID_AUTO, timecounter, CTLFLAG_RW, 0, ""); 100 101static int timestepwarnings; 102SYSCTL_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 110TC_STATS(nbinuptime); TC_STATS(nnanouptime); TC_STATS(nmicrouptime); 111TC_STATS(nbintime); TC_STATS(nnanotime); TC_STATS(nmicrotime); 112TC_STATS(ngetbinuptime); TC_STATS(ngetnanouptime); TC_STATS(ngetmicrouptime); 113TC_STATS(ngetbintime); TC_STATS(ngetnanotime); TC_STATS(ngetmicrotime); 114TC_STATS(nsetclock); 115 116#undef TC_STATS 117 118static void tc_windup(void); 119static void cpu_tick_calibrate(int); 120 121static int 122sysctl_kern_boottime(SYSCTL_HANDLER_ARGS) 123{ 124#ifdef SCTL_MASK32 125 int tv[2]; 126 127 if (req->flags & SCTL_MASK32) { 128 tv[0] = boottime.tv_sec; 129 tv[1] = boottime.tv_usec; 130 return SYSCTL_OUT(req, tv, sizeof(tv)); 131 } else 132#endif 133 return SYSCTL_OUT(req, &boottime, sizeof(boottime)); 134} 135 136/* 137 * Return the difference between the timehands' counter value now and what 138 * was when we copied it to the timehands' offset_count. 139 */ 140static __inline u_int 141tc_delta(struct timehands *th) 142{ 143 struct timecounter *tc; 144 145 tc = th->th_counter; 146 return ((tc->tc_get_timecount(tc) - th->th_offset_count) & 147 tc->tc_counter_mask); 148} 149 150/* 151 * Functions for reading the time. We have to loop until we are sure that 152 * the timehands that we operated on was not updated under our feet. See 153 * the comment in <sys/time.h> for a description of these 12 functions. 154 */ 155 156void 157binuptime(struct bintime *bt) 158{ 159 struct timehands *th; 160 u_int gen; 161 162 nbinuptime++; 163 do { 164 th = timehands; 165 gen = th->th_generation; 166 *bt = th->th_offset; 167 bintime_addx(bt, th->th_scale * tc_delta(th)); 168 } while (gen == 0 || gen != th->th_generation); 169} 170 171void 172nanouptime(struct timespec *tsp) 173{ 174 struct bintime bt; 175 176 nnanouptime++; 177 binuptime(&bt); 178 bintime2timespec(&bt, tsp); 179} 180 181void 182microuptime(struct timeval *tvp) 183{ 184 struct bintime bt; 185 186 nmicrouptime++; 187 binuptime(&bt); 188 bintime2timeval(&bt, tvp); 189} 190 191void 192bintime(struct bintime *bt) 193{ 194 195 nbintime++; 196 binuptime(bt); 197 bintime_add(bt, &boottimebin); 198} 199 200void 201nanotime(struct timespec *tsp) 202{ 203 struct bintime bt; 204 205 nnanotime++; 206 bintime(&bt); 207 bintime2timespec(&bt, tsp); 208} 209 210void 211microtime(struct timeval *tvp) 212{ 213 struct bintime bt; 214 215 nmicrotime++; 216 bintime(&bt); 217 bintime2timeval(&bt, tvp); 218} 219 220void 221getbinuptime(struct bintime *bt) 222{ 223 struct timehands *th; 224 u_int gen; 225 226 ngetbinuptime++; 227 do { 228 th = timehands; 229 gen = th->th_generation; 230 *bt = th->th_offset; 231 } while (gen == 0 || gen != th->th_generation); 232} 233 234void 235getnanouptime(struct timespec *tsp) 236{ 237 struct timehands *th; 238 u_int gen; 239 240 ngetnanouptime++; 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 248void 249getmicrouptime(struct timeval *tvp) 250{ 251 struct timehands *th; 252 u_int gen; 253 254 ngetmicrouptime++; 255 do { 256 th = timehands; 257 gen = th->th_generation; 258 bintime2timeval(&th->th_offset, tvp); 259 } while (gen == 0 || gen != th->th_generation); 260} 261 262void 263getbintime(struct bintime *bt) 264{ 265 struct timehands *th; 266 u_int gen; 267 268 ngetbintime++; 269 do { 270 th = timehands; 271 gen = th->th_generation; 272 *bt = th->th_offset; 273 } while (gen == 0 || gen != th->th_generation); 274 bintime_add(bt, &boottimebin); 275} 276 277void 278getnanotime(struct timespec *tsp) 279{ 280 struct timehands *th; 281 u_int gen; 282 283 ngetnanotime++; 284 do { 285 th = timehands; 286 gen = th->th_generation; 287 *tsp = th->th_nanotime; 288 } while (gen == 0 || gen != th->th_generation); 289} 290 291void 292getmicrotime(struct timeval *tvp) 293{ 294 struct timehands *th; 295 u_int gen; 296 297 ngetmicrotime++; 298 do { 299 th = timehands; 300 gen = th->th_generation; 301 *tvp = th->th_microtime; 302 } while (gen == 0 || gen != th->th_generation); 303} 304 305/* 306 * Initialize a new timecounter and possibly use it. 307 */ 308void 309tc_init(struct timecounter *tc) 310{ 311 u_int u; 312 313 u = tc->tc_frequency / tc->tc_counter_mask; 314 /* XXX: We need some margin here, 10% is a guess */ 315 u *= 11; 316 u /= 10; 317 if (u > hz && tc->tc_quality >= 0) { 318 tc->tc_quality = -2000; 319 if (bootverbose) { 320 printf("Timecounter \"%s\" frequency %ju Hz", 321 tc->tc_name, (uintmax_t)tc->tc_frequency); 322 printf(" -- Insufficient hz, needs at least %u\n", u); 323 } 324 } else if (tc->tc_quality >= 0 || bootverbose) { 325 printf("Timecounter \"%s\" frequency %ju Hz quality %d\n", 326 tc->tc_name, (uintmax_t)tc->tc_frequency, 327 tc->tc_quality); 328 } 329 330 tc->tc_next = timecounters; 331 timecounters = tc; 332 /* 333 * Never automatically use a timecounter with negative quality. 334 * Even though we run on the dummy counter, switching here may be 335 * worse since this timecounter may not be monotonous. 336 */ 337 if (tc->tc_quality < 0) 338 return; 339 if (tc->tc_quality < timecounter->tc_quality) 340 return; 341 if (tc->tc_quality == timecounter->tc_quality && 342 tc->tc_frequency < timecounter->tc_frequency) 343 return; 344 (void)tc->tc_get_timecount(tc); 345 (void)tc->tc_get_timecount(tc); 346 timecounter = tc; 347} 348 349/* Report the frequency of the current timecounter. */ 350u_int64_t 351tc_getfrequency(void) 352{ 353 354 return (timehands->th_counter->tc_frequency); 355} 356 357/* 358 * Step our concept of UTC. This is done by modifying our estimate of 359 * when we booted. 360 * XXX: not locked. 361 */ 362void 363tc_setclock(struct timespec *ts) 364{ 365 struct timespec tbef, taft; 366 struct bintime bt, bt2; 367 368 cpu_tick_calibrate(1); 369 nsetclock++; 370 nanotime(&tbef); 371 timespec2bintime(ts, &bt); 372 binuptime(&bt2); 373 bintime_sub(&bt, &bt2); 374 bintime_add(&bt2, &boottimebin); 375 boottimebin = bt; 376 bintime2timeval(&bt, &boottime); 377 378 /* XXX fiddle all the little crinkly bits around the fiords... */ 379 tc_windup(); 380 nanotime(&taft); 381 if (timestepwarnings) { 382 log(LOG_INFO, 383 "Time stepped from %jd.%09ld to %jd.%09ld (%jd.%09ld)\n", 384 (intmax_t)tbef.tv_sec, tbef.tv_nsec, 385 (intmax_t)taft.tv_sec, taft.tv_nsec, 386 (intmax_t)ts->tv_sec, ts->tv_nsec); 387 } 388 cpu_tick_calibrate(1); 389} 390 391/* 392 * Initialize the next struct timehands in the ring and make 393 * it the active timehands. Along the way we might switch to a different 394 * timecounter and/or do seconds processing in NTP. Slightly magic. 395 */ 396static void 397tc_windup(void) 398{ 399 struct bintime bt; 400 struct timehands *th, *tho; 401 u_int64_t scale; 402 u_int delta, ncount, ogen; 403 int i; 404 time_t t; 405 406 /* 407 * Make the next timehands a copy of the current one, but do not 408 * overwrite the generation or next pointer. While we update 409 * the contents, the generation must be zero. 410 */ 411 tho = timehands; 412 th = tho->th_next; 413 ogen = th->th_generation; 414 th->th_generation = 0; 415 bcopy(tho, th, offsetof(struct timehands, th_generation)); 416 417 /* 418 * Capture a timecounter delta on the current timecounter and if 419 * changing timecounters, a counter value from the new timecounter. 420 * Update the offset fields accordingly. 421 */ 422 delta = tc_delta(th); 423 if (th->th_counter != timecounter) 424 ncount = timecounter->tc_get_timecount(timecounter); 425 else 426 ncount = 0; 427 th->th_offset_count += delta; 428 th->th_offset_count &= th->th_counter->tc_counter_mask; 429 bintime_addx(&th->th_offset, th->th_scale * delta); 430 431 /* 432 * Hardware latching timecounters may not generate interrupts on 433 * PPS events, so instead we poll them. There is a finite risk that 434 * the hardware might capture a count which is later than the one we 435 * got above, and therefore possibly in the next NTP second which might 436 * have a different rate than the current NTP second. It doesn't 437 * matter in practice. 438 */ 439 if (tho->th_counter->tc_poll_pps) 440 tho->th_counter->tc_poll_pps(tho->th_counter); 441 442 /* 443 * Deal with NTP second processing. The for loop normally 444 * iterates at most once, but in extreme situations it might 445 * keep NTP sane if timeouts are not run for several seconds. 446 * At boot, the time step can be large when the TOD hardware 447 * has been read, so on really large steps, we call 448 * ntp_update_second only twice. We need to call it twice in 449 * case we missed a leap second. 450 */ 451 bt = th->th_offset; 452 bintime_add(&bt, &boottimebin); 453 i = bt.sec - tho->th_microtime.tv_sec; 454 if (i > LARGE_STEP) 455 i = 2; 456 for (; i > 0; i--) { 457 t = bt.sec; 458 ntp_update_second(&th->th_adjustment, &bt.sec); 459 if (bt.sec != t) 460 boottimebin.sec += bt.sec - t; 461 } 462 /* Update the UTC timestamps used by the get*() functions. */ 463 /* XXX shouldn't do this here. Should force non-`get' versions. */ 464 bintime2timeval(&bt, &th->th_microtime); 465 bintime2timespec(&bt, &th->th_nanotime); 466 467 /* Now is a good time to change timecounters. */ 468 if (th->th_counter != timecounter) { 469 th->th_counter = timecounter; 470 th->th_offset_count = ncount; 471 } 472 473 /*- 474 * Recalculate the scaling factor. We want the number of 1/2^64 475 * fractions of a second per period of the hardware counter, taking 476 * into account the th_adjustment factor which the NTP PLL/adjtime(2) 477 * processing provides us with. 478 * 479 * The th_adjustment is nanoseconds per second with 32 bit binary 480 * fraction and we want 64 bit binary fraction of second: 481 * 482 * x = a * 2^32 / 10^9 = a * 4.294967296 483 * 484 * The range of th_adjustment is +/- 5000PPM so inside a 64bit int 485 * we can only multiply by about 850 without overflowing, that 486 * leaves no suitably precise fractions for multiply before divide. 487 * 488 * Divide before multiply with a fraction of 2199/512 results in a 489 * systematic undercompensation of 10PPM of th_adjustment. On a 490 * 5000PPM adjustment this is a 0.05PPM error. This is acceptable. 491 * 492 * We happily sacrifice the lowest of the 64 bits of our result 493 * to the goddess of code clarity. 494 * 495 */ 496 scale = (u_int64_t)1 << 63; 497 scale += (th->th_adjustment / 1024) * 2199; 498 scale /= th->th_counter->tc_frequency; 499 th->th_scale = scale * 2; 500 501 /* 502 * Now that the struct timehands is again consistent, set the new 503 * generation number, making sure to not make it zero. 504 */ 505 if (++ogen == 0) 506 ogen = 1; 507 th->th_generation = ogen; 508 509 /* Go live with the new struct timehands. */ 510 time_second = th->th_microtime.tv_sec; 511 time_uptime = th->th_offset.sec; 512 timehands = th; 513} 514 515/* Report or change the active timecounter hardware. */ 516static int 517sysctl_kern_timecounter_hardware(SYSCTL_HANDLER_ARGS) 518{ 519 char newname[32]; 520 struct timecounter *newtc, *tc; 521 int error; 522 523 tc = timecounter; 524 strlcpy(newname, tc->tc_name, sizeof(newname)); 525 526 error = sysctl_handle_string(oidp, &newname[0], sizeof(newname), req); 527 if (error != 0 || req->newptr == NULL || 528 strcmp(newname, tc->tc_name) == 0) 529 return (error); 530 for (newtc = timecounters; newtc != NULL; newtc = newtc->tc_next) { 531 if (strcmp(newname, newtc->tc_name) != 0) 532 continue; 533 534 /* Warm up new timecounter. */ 535 (void)newtc->tc_get_timecount(newtc); 536 (void)newtc->tc_get_timecount(newtc); 537 538 timecounter = newtc; 539 return (0); 540 } 541 return (EINVAL); 542} 543 544SYSCTL_PROC(_kern_timecounter, OID_AUTO, hardware, CTLTYPE_STRING | CTLFLAG_RW, 545 0, 0, sysctl_kern_timecounter_hardware, "A", ""); 546 547 548/* Report or change the active timecounter hardware. */ 549static int 550sysctl_kern_timecounter_choice(SYSCTL_HANDLER_ARGS) 551{ 552 char buf[32], *spc; 553 struct timecounter *tc; 554 int error; 555 556 spc = ""; 557 error = 0; 558 for (tc = timecounters; error == 0 && tc != NULL; tc = tc->tc_next) { 559 sprintf(buf, "%s%s(%d)", 560 spc, tc->tc_name, tc->tc_quality); 561 error = SYSCTL_OUT(req, buf, strlen(buf)); 562 spc = " "; 563 } 564 return (error); 565} 566 567SYSCTL_PROC(_kern_timecounter, OID_AUTO, choice, CTLTYPE_STRING | CTLFLAG_RD, 568 0, 0, sysctl_kern_timecounter_choice, "A", ""); 569 570/* 571 * RFC 2783 PPS-API implementation. 572 */ 573 574int 575pps_ioctl(u_long cmd, caddr_t data, struct pps_state *pps) 576{ 577 pps_params_t *app; 578 struct pps_fetch_args *fapi; 579#ifdef PPS_SYNC 580 struct pps_kcbind_args *kapi; 581#endif 582 583 KASSERT(pps != NULL, ("NULL pps pointer in pps_ioctl")); 584 switch (cmd) { 585 case PPS_IOC_CREATE: 586 return (0); 587 case PPS_IOC_DESTROY: 588 return (0); 589 case PPS_IOC_SETPARAMS: 590 app = (pps_params_t *)data; 591 if (app->mode & ~pps->ppscap) 592 return (EINVAL); 593 pps->ppsparam = *app; 594 return (0); 595 case PPS_IOC_GETPARAMS: 596 app = (pps_params_t *)data; 597 *app = pps->ppsparam; 598 app->api_version = PPS_API_VERS_1; 599 return (0); 600 case PPS_IOC_GETCAP: 601 *(int*)data = pps->ppscap; 602 return (0); 603 case PPS_IOC_FETCH: 604 fapi = (struct pps_fetch_args *)data; 605 if (fapi->tsformat && fapi->tsformat != PPS_TSFMT_TSPEC) 606 return (EINVAL); 607 if (fapi->timeout.tv_sec || fapi->timeout.tv_nsec) 608 return (EOPNOTSUPP); 609 pps->ppsinfo.current_mode = pps->ppsparam.mode; 610 fapi->pps_info_buf = pps->ppsinfo; 611 return (0); 612 case PPS_IOC_KCBIND: 613#ifdef PPS_SYNC 614 kapi = (struct pps_kcbind_args *)data; 615 /* XXX Only root should be able to do this */ 616 if (kapi->tsformat && kapi->tsformat != PPS_TSFMT_TSPEC) 617 return (EINVAL); 618 if (kapi->kernel_consumer != PPS_KC_HARDPPS) 619 return (EINVAL); 620 if (kapi->edge & ~pps->ppscap) 621 return (EINVAL); 622 pps->kcmode = kapi->edge; 623 return (0); 624#else 625 return (EOPNOTSUPP); 626#endif 627 default: 628 return (ENOIOCTL); 629 } 630} 631 632void 633pps_init(struct pps_state *pps) 634{ 635 pps->ppscap |= PPS_TSFMT_TSPEC; 636 if (pps->ppscap & PPS_CAPTUREASSERT) 637 pps->ppscap |= PPS_OFFSETASSERT; 638 if (pps->ppscap & PPS_CAPTURECLEAR) 639 pps->ppscap |= PPS_OFFSETCLEAR; 640} 641 642void 643pps_capture(struct pps_state *pps) 644{ 645 struct timehands *th; 646 647 KASSERT(pps != NULL, ("NULL pps pointer in pps_capture")); 648 th = timehands; 649 pps->capgen = th->th_generation; 650 pps->capth = th; 651 pps->capcount = th->th_counter->tc_get_timecount(th->th_counter); 652 if (pps->capgen != th->th_generation) 653 pps->capgen = 0; 654} 655 656void 657pps_event(struct pps_state *pps, int event) 658{ 659 struct bintime bt; 660 struct timespec ts, *tsp, *osp; 661 u_int tcount, *pcount; 662 int foff, fhard; 663 pps_seq_t *pseq; 664 665 KASSERT(pps != NULL, ("NULL pps pointer in pps_event")); 666 /* If the timecounter was wound up underneath us, bail out. */ 667 if (pps->capgen == 0 || pps->capgen != pps->capth->th_generation) 668 return; 669 670 /* Things would be easier with arrays. */ 671 if (event == PPS_CAPTUREASSERT) { 672 tsp = &pps->ppsinfo.assert_timestamp; 673 osp = &pps->ppsparam.assert_offset; 674 foff = pps->ppsparam.mode & PPS_OFFSETASSERT; 675 fhard = pps->kcmode & PPS_CAPTUREASSERT; 676 pcount = &pps->ppscount[0]; 677 pseq = &pps->ppsinfo.assert_sequence; 678 } else { 679 tsp = &pps->ppsinfo.clear_timestamp; 680 osp = &pps->ppsparam.clear_offset; 681 foff = pps->ppsparam.mode & PPS_OFFSETCLEAR; 682 fhard = pps->kcmode & PPS_CAPTURECLEAR; 683 pcount = &pps->ppscount[1]; 684 pseq = &pps->ppsinfo.clear_sequence; 685 } 686 687 /* 688 * If the timecounter changed, we cannot compare the count values, so 689 * we have to drop the rest of the PPS-stuff until the next event. 690 */ 691 if (pps->ppstc != pps->capth->th_counter) { 692 pps->ppstc = pps->capth->th_counter; 693 *pcount = pps->capcount; 694 pps->ppscount[2] = pps->capcount; 695 return; 696 } 697 698 /* Convert the count to a timespec. */ 699 tcount = pps->capcount - pps->capth->th_offset_count; 700 tcount &= pps->capth->th_counter->tc_counter_mask; 701 bt = pps->capth->th_offset; 702 bintime_addx(&bt, pps->capth->th_scale * tcount); 703 bintime_add(&bt, &boottimebin); 704 bintime2timespec(&bt, &ts); 705 706 /* If the timecounter was wound up underneath us, bail out. */ 707 if (pps->capgen != pps->capth->th_generation) 708 return; 709 710 *pcount = pps->capcount; 711 (*pseq)++; 712 *tsp = ts; 713 714 if (foff) { 715 timespecadd(tsp, osp); 716 if (tsp->tv_nsec < 0) { 717 tsp->tv_nsec += 1000000000; 718 tsp->tv_sec -= 1; 719 } 720 } 721#ifdef PPS_SYNC 722 if (fhard) { 723 u_int64_t scale; 724 725 /* 726 * Feed the NTP PLL/FLL. 727 * The FLL wants to know how many (hardware) nanoseconds 728 * elapsed since the previous event. 729 */ 730 tcount = pps->capcount - pps->ppscount[2]; 731 pps->ppscount[2] = pps->capcount; 732 tcount &= pps->capth->th_counter->tc_counter_mask; 733 scale = (u_int64_t)1 << 63; 734 scale /= pps->capth->th_counter->tc_frequency; 735 scale *= 2; 736 bt.sec = 0; 737 bt.frac = 0; 738 bintime_addx(&bt, scale * tcount); 739 bintime2timespec(&bt, &ts); 740 hardpps(tsp, ts.tv_nsec + 1000000000 * ts.tv_sec); 741 } 742#endif 743} 744 745/* 746 * Timecounters need to be updated every so often to prevent the hardware 747 * counter from overflowing. Updating also recalculates the cached values 748 * used by the get*() family of functions, so their precision depends on 749 * the update frequency. 750 */ 751 752static int tc_tick; 753SYSCTL_INT(_kern_timecounter, OID_AUTO, tick, CTLFLAG_RD, &tc_tick, 0, ""); 754 755void 756tc_ticktock(void) 757{ 758 static int count; 759 static time_t last_calib; 760 761 if (++count < tc_tick) 762 return; 763 count = 0; 764 tc_windup(); 765 if (time_uptime != last_calib && !(time_uptime & 0xf)) { 766 cpu_tick_calibrate(0); 767 last_calib = time_uptime; 768 } 769} 770 771static void 772inittimecounter(void *dummy) 773{ 774 u_int p; 775 776 /* 777 * Set the initial timeout to 778 * max(1, <approx. number of hardclock ticks in a millisecond>). 779 * People should probably not use the sysctl to set the timeout 780 * to smaller than its inital value, since that value is the 781 * smallest reasonable one. If they want better timestamps they 782 * should use the non-"get"* functions. 783 */ 784 if (hz > 1000) 785 tc_tick = (hz + 500) / 1000; 786 else 787 tc_tick = 1; 788 p = (tc_tick * 1000000) / hz; 789 printf("Timecounters tick every %d.%03u msec\n", p / 1000, p % 1000); 790 791 /* warm up new timecounter (again) and get rolling. */ 792 (void)timecounter->tc_get_timecount(timecounter); 793 (void)timecounter->tc_get_timecount(timecounter); 794} 795 796SYSINIT(timecounter, SI_SUB_CLOCKS, SI_ORDER_SECOND, inittimecounter, NULL) 797 798/* Cpu tick handling -------------------------------------------------*/ 799 800static int cpu_tick_variable; 801static uint64_t cpu_tick_frequency; 802 803static 804uint64_t 805tc_cpu_ticks(void) 806{ 807 static uint64_t base; 808 static unsigned last; 809 unsigned u; 810 struct timecounter *tc; 811 812 tc = timehands->th_counter; 813 u = tc->tc_get_timecount(tc) & tc->tc_counter_mask; 814 if (u < last) 815 base += tc->tc_counter_mask + 1; 816 last = u; 817 return (u + base); 818} 819 820/* 821 * This function gets called ever 16 seconds on only one designated 822 * CPU in the system from hardclock() via tc_ticktock(). 823 * 824 * Whenever the real time clock is stepped we get called with reset=1 825 * to make sure we handle suspend/resume and similar events correctly. 826 */ 827 828static void 829cpu_tick_calibrate(int reset) 830{ 831 static uint64_t c_last; 832 uint64_t c_this, c_delta; 833 static struct bintime t_last; 834 struct bintime t_this, t_delta; 835 uint32_t divi; 836 837 if (reset) { 838 /* The clock was stepped, abort & reset */ 839 t_last.sec = 0; 840 return; 841 } 842 843 /* we don't calibrate fixed rate cputicks */ 844 if (!cpu_tick_variable) 845 return; 846 847 getbinuptime(&t_this); 848 c_this = cpu_ticks(); 849 if (t_last.sec != 0) { 850 c_delta = c_this - c_last; 851 t_delta = t_this; 852 bintime_sub(&t_delta, &t_last); 853 if (bootverbose) { 854 printf("%ju.%016jx ", 855 (uintmax_t)t_delta.sec, (uintmax_t)t_delta.frac); 856 } 857 /* 858 * Validate that 16 +/- 1/256 seconds passed. 859 * After division by 16 this gives us a precision of 860 * roughly 250PPM which is sufficient 861 */ 862 if (t_delta.sec > 16 || ( 863 t_delta.sec == 16 && t_delta.frac >= (0x01LL << 56))) { 864 /* too long */ 865 if (bootverbose) 866 printf("\ttoo long\n"); 867 } else if (t_delta.sec < 15 || 868 (t_delta.sec == 15 && t_delta.frac <= (0xffLL << 56))) { 869 /* too short */ 870 if (bootverbose) 871 printf("\ttoo short\n"); 872 } else { 873 /* just right */ 874 /* 875 * Headroom: 876 * 2^(64-20) / 16[s] = 877 * 2^(44) / 16[s] = 878 * 17.592.186.044.416 / 16 = 879 * 1.099.511.627.776 [Hz] 880 */ 881 divi = t_delta.sec << 20; 882 divi |= t_delta.frac >> (64 - 20); 883 c_delta <<= 20; 884 if (bootverbose) 885 printf(" %ju / %ju", 886 (uintmax_t)c_delta, (uintmax_t)divi); 887 c_delta /= divi; 888 if (bootverbose) 889 printf(" = %ju", c_delta); 890 if (c_delta > cpu_tick_frequency) { 891 if (bootverbose) 892 printf("\thigher\n"); 893 cpu_tick_frequency = c_delta; 894 } else { 895 if (bootverbose) 896 printf("\tlower\n"); 897 } 898 } 899 } 900 c_last = c_this; 901 t_last = t_this; 902} 903 904void 905set_cputicker(cpu_tick_f *func, uint64_t freq, unsigned var) 906{ 907 908 if (func == NULL) { 909 cpu_ticks = tc_cpu_ticks; 910 } else { 911 cpu_tick_frequency = freq; 912 cpu_tick_variable = var; 913 cpu_ticks = func; 914 } 915} 916 917uint64_t 918cpu_tickrate(void) 919{ 920 921 if (cpu_ticks == tc_cpu_ticks) 922 return (tc_getfrequency()); 923 return (cpu_tick_frequency); 924} 925 926/* 927 * We need to be slightly careful converting cputicks to microseconds. 928 * There is plenty of margin in 64 bits of microseconds (half a million 929 * years) and in 64 bits at 4 GHz (146 years), but if we do a multiply 930 * before divide conversion (to retain precision) we find that the 931 * margin shrinks to 1.5 hours (one millionth of 146y). 932 * With a three prong approach we never loose significant bits, no 933 * matter what the cputick rate and length of timeinterval is. 934 */ 935 936uint64_t 937cputick2usec(uint64_t tick) 938{ 939 940 if (tick > 18446744073709551LL) /* floor(2^64 / 1000) */ 941 return (tick / (cpu_tickrate() / 1000000LL)); 942 else if (tick > 18446744073709LL) /* floor(2^64 / 1000000) */ 943 return ((tick * 1000LL) / (cpu_tickrate() / 1000LL)); 944 else 945 return ((tick * 1000000LL) / cpu_tickrate()); 946} 947 948cpu_tick_f *cpu_ticks = tc_cpu_ticks; 949