kern_ntptime.c revision 207359
1/*- 2 *********************************************************************** 3 * * 4 * Copyright (c) David L. Mills 1993-2001 * 5 * * 6 * Permission to use, copy, modify, and distribute this software and * 7 * its documentation for any purpose and without fee is hereby * 8 * granted, provided that the above copyright notice appears in all * 9 * copies and that both the copyright notice and this permission * 10 * notice appear in supporting documentation, and that the name * 11 * University of Delaware not be used in advertising or publicity * 12 * pertaining to distribution of the software without specific, * 13 * written prior permission. The University of Delaware makes no * 14 * representations about the suitability this software for any * 15 * purpose. It is provided "as is" without express or implied * 16 * warranty. * 17 * * 18 **********************************************************************/ 19 20/* 21 * Adapted from the original sources for FreeBSD and timecounters by: 22 * Poul-Henning Kamp <phk@FreeBSD.org>. 23 * 24 * The 32bit version of the "LP" macros seems a bit past its "sell by" 25 * date so I have retained only the 64bit version and included it directly 26 * in this file. 27 * 28 * Only minor changes done to interface with the timecounters over in 29 * sys/kern/kern_clock.c. Some of the comments below may be (even more) 30 * confusing and/or plain wrong in that context. 31 */ 32 33#include <sys/cdefs.h> 34__FBSDID("$FreeBSD: head/sys/kern/kern_ntptime.c 207359 2010-04-29 09:02:21Z avg $"); 35 36#include "opt_ntp.h" 37 38#include <sys/param.h> 39#include <sys/systm.h> 40#include <sys/sysproto.h> 41#include <sys/kernel.h> 42#include <sys/priv.h> 43#include <sys/proc.h> 44#include <sys/lock.h> 45#include <sys/mutex.h> 46#include <sys/time.h> 47#include <sys/timex.h> 48#include <sys/timetc.h> 49#include <sys/timepps.h> 50#include <sys/syscallsubr.h> 51#include <sys/sysctl.h> 52 53/* 54 * Single-precision macros for 64-bit machines 55 */ 56typedef int64_t l_fp; 57#define L_ADD(v, u) ((v) += (u)) 58#define L_SUB(v, u) ((v) -= (u)) 59#define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32) 60#define L_NEG(v) ((v) = -(v)) 61#define L_RSHIFT(v, n) \ 62 do { \ 63 if ((v) < 0) \ 64 (v) = -(-(v) >> (n)); \ 65 else \ 66 (v) = (v) >> (n); \ 67 } while (0) 68#define L_MPY(v, a) ((v) *= (a)) 69#define L_CLR(v) ((v) = 0) 70#define L_ISNEG(v) ((v) < 0) 71#define L_LINT(v, a) ((v) = (int64_t)(a) << 32) 72#define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32) 73 74/* 75 * Generic NTP kernel interface 76 * 77 * These routines constitute the Network Time Protocol (NTP) interfaces 78 * for user and daemon application programs. The ntp_gettime() routine 79 * provides the time, maximum error (synch distance) and estimated error 80 * (dispersion) to client user application programs. The ntp_adjtime() 81 * routine is used by the NTP daemon to adjust the system clock to an 82 * externally derived time. The time offset and related variables set by 83 * this routine are used by other routines in this module to adjust the 84 * phase and frequency of the clock discipline loop which controls the 85 * system clock. 86 * 87 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO 88 * defined), the time at each tick interrupt is derived directly from 89 * the kernel time variable. When the kernel time is reckoned in 90 * microseconds, (NTP_NANO undefined), the time is derived from the 91 * kernel time variable together with a variable representing the 92 * leftover nanoseconds at the last tick interrupt. In either case, the 93 * current nanosecond time is reckoned from these values plus an 94 * interpolated value derived by the clock routines in another 95 * architecture-specific module. The interpolation can use either a 96 * dedicated counter or a processor cycle counter (PCC) implemented in 97 * some architectures. 98 * 99 * Note that all routines must run at priority splclock or higher. 100 */ 101/* 102 * Phase/frequency-lock loop (PLL/FLL) definitions 103 * 104 * The nanosecond clock discipline uses two variable types, time 105 * variables and frequency variables. Both types are represented as 64- 106 * bit fixed-point quantities with the decimal point between two 32-bit 107 * halves. On a 32-bit machine, each half is represented as a single 108 * word and mathematical operations are done using multiple-precision 109 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is 110 * used. 111 * 112 * A time variable is a signed 64-bit fixed-point number in ns and 113 * fraction. It represents the remaining time offset to be amortized 114 * over succeeding tick interrupts. The maximum time offset is about 115 * 0.5 s and the resolution is about 2.3e-10 ns. 116 * 117 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 118 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 119 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 120 * |s s s| ns | 121 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 122 * | fraction | 123 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 124 * 125 * A frequency variable is a signed 64-bit fixed-point number in ns/s 126 * and fraction. It represents the ns and fraction to be added to the 127 * kernel time variable at each second. The maximum frequency offset is 128 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s. 129 * 130 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 131 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 132 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 133 * |s s s s s s s s s s s s s| ns/s | 134 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 * | fraction | 136 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 137 */ 138/* 139 * The following variables establish the state of the PLL/FLL and the 140 * residual time and frequency offset of the local clock. 141 */ 142#define SHIFT_PLL 4 /* PLL loop gain (shift) */ 143#define SHIFT_FLL 2 /* FLL loop gain (shift) */ 144 145static int time_state = TIME_OK; /* clock state */ 146static int time_status = STA_UNSYNC; /* clock status bits */ 147static long time_tai; /* TAI offset (s) */ 148static long time_monitor; /* last time offset scaled (ns) */ 149static long time_constant; /* poll interval (shift) (s) */ 150static long time_precision = 1; /* clock precision (ns) */ 151static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */ 152static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */ 153static long time_reftime; /* time at last adjustment (s) */ 154static l_fp time_offset; /* time offset (ns) */ 155static l_fp time_freq; /* frequency offset (ns/s) */ 156static l_fp time_adj; /* tick adjust (ns/s) */ 157 158static int64_t time_adjtime; /* correction from adjtime(2) (usec) */ 159 160#ifdef PPS_SYNC 161/* 162 * The following variables are used when a pulse-per-second (PPS) signal 163 * is available and connected via a modem control lead. They establish 164 * the engineering parameters of the clock discipline loop when 165 * controlled by the PPS signal. 166 */ 167#define PPS_FAVG 2 /* min freq avg interval (s) (shift) */ 168#define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */ 169#define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */ 170#define PPS_PAVG 4 /* phase avg interval (s) (shift) */ 171#define PPS_VALID 120 /* PPS signal watchdog max (s) */ 172#define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */ 173#define PPS_POPCORN 2 /* popcorn spike threshold (shift) */ 174 175static struct timespec pps_tf[3]; /* phase median filter */ 176static l_fp pps_freq; /* scaled frequency offset (ns/s) */ 177static long pps_fcount; /* frequency accumulator */ 178static long pps_jitter; /* nominal jitter (ns) */ 179static long pps_stabil; /* nominal stability (scaled ns/s) */ 180static long pps_lastsec; /* time at last calibration (s) */ 181static int pps_valid; /* signal watchdog counter */ 182static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */ 183static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */ 184static int pps_intcnt; /* wander counter */ 185 186/* 187 * PPS signal quality monitors 188 */ 189static long pps_calcnt; /* calibration intervals */ 190static long pps_jitcnt; /* jitter limit exceeded */ 191static long pps_stbcnt; /* stability limit exceeded */ 192static long pps_errcnt; /* calibration errors */ 193#endif /* PPS_SYNC */ 194/* 195 * End of phase/frequency-lock loop (PLL/FLL) definitions 196 */ 197 198static void ntp_init(void); 199static void hardupdate(long offset); 200static void ntp_gettime1(struct ntptimeval *ntvp); 201static int ntp_is_time_error(void); 202 203static int 204ntp_is_time_error(void) 205{ 206 /* 207 * Status word error decode. If any of these conditions occur, 208 * an error is returned, instead of the status word. Most 209 * applications will care only about the fact the system clock 210 * may not be trusted, not about the details. 211 * 212 * Hardware or software error 213 */ 214 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 215 216 /* 217 * PPS signal lost when either time or frequency synchronization 218 * requested 219 */ 220 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 221 !(time_status & STA_PPSSIGNAL)) || 222 223 /* 224 * PPS jitter exceeded when time synchronization requested 225 */ 226 (time_status & STA_PPSTIME && 227 time_status & STA_PPSJITTER) || 228 229 /* 230 * PPS wander exceeded or calibration error when frequency 231 * synchronization requested 232 */ 233 (time_status & STA_PPSFREQ && 234 time_status & (STA_PPSWANDER | STA_PPSERROR))) 235 return (1); 236 237 return (0); 238} 239 240static void 241ntp_gettime1(struct ntptimeval *ntvp) 242{ 243 struct timespec atv; /* nanosecond time */ 244 245 GIANT_REQUIRED; 246 247 nanotime(&atv); 248 ntvp->time.tv_sec = atv.tv_sec; 249 ntvp->time.tv_nsec = atv.tv_nsec; 250 ntvp->maxerror = time_maxerror; 251 ntvp->esterror = time_esterror; 252 ntvp->tai = time_tai; 253 ntvp->time_state = time_state; 254 255 if (ntp_is_time_error()) 256 ntvp->time_state = TIME_ERROR; 257} 258 259/* 260 * ntp_gettime() - NTP user application interface 261 * 262 * See the timex.h header file for synopsis and API description. Note that 263 * the TAI offset is returned in the ntvtimeval.tai structure member. 264 */ 265#ifndef _SYS_SYSPROTO_H_ 266struct ntp_gettime_args { 267 struct ntptimeval *ntvp; 268}; 269#endif 270/* ARGSUSED */ 271int 272ntp_gettime(struct thread *td, struct ntp_gettime_args *uap) 273{ 274 struct ntptimeval ntv; 275 276 mtx_lock(&Giant); 277 ntp_gettime1(&ntv); 278 mtx_unlock(&Giant); 279 280 td->td_retval[0] = ntv.time_state; 281 return (copyout(&ntv, uap->ntvp, sizeof(ntv))); 282} 283 284static int 285ntp_sysctl(SYSCTL_HANDLER_ARGS) 286{ 287 struct ntptimeval ntv; /* temporary structure */ 288 289 ntp_gettime1(&ntv); 290 291 return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req)); 292} 293 294SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, ""); 295SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD, 296 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", ""); 297 298#ifdef PPS_SYNC 299SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, &pps_shiftmax, 0, ""); 300SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, &pps_shift, 0, ""); 301SYSCTL_INT(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, &time_monitor, 0, ""); 302 303SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD, &pps_freq, sizeof(pps_freq), "I", ""); 304SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD, &time_freq, sizeof(time_freq), "I", ""); 305#endif 306 307/* 308 * ntp_adjtime() - NTP daemon application interface 309 * 310 * See the timex.h header file for synopsis and API description. Note that 311 * the timex.constant structure member has a dual purpose to set the time 312 * constant and to set the TAI offset. 313 */ 314#ifndef _SYS_SYSPROTO_H_ 315struct ntp_adjtime_args { 316 struct timex *tp; 317}; 318#endif 319 320int 321ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap) 322{ 323 struct timex ntv; /* temporary structure */ 324 long freq; /* frequency ns/s) */ 325 int modes; /* mode bits from structure */ 326 int s; /* caller priority */ 327 int error; 328 329 error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv)); 330 if (error) 331 return(error); 332 333 /* 334 * Update selected clock variables - only the superuser can 335 * change anything. Note that there is no error checking here on 336 * the assumption the superuser should know what it is doing. 337 * Note that either the time constant or TAI offset are loaded 338 * from the ntv.constant member, depending on the mode bits. If 339 * the STA_PLL bit in the status word is cleared, the state and 340 * status words are reset to the initial values at boot. 341 */ 342 mtx_lock(&Giant); 343 modes = ntv.modes; 344 if (modes) 345 error = priv_check(td, PRIV_NTP_ADJTIME); 346 if (error) 347 goto done2; 348 s = splclock(); 349 if (modes & MOD_MAXERROR) 350 time_maxerror = ntv.maxerror; 351 if (modes & MOD_ESTERROR) 352 time_esterror = ntv.esterror; 353 if (modes & MOD_STATUS) { 354 if (time_status & STA_PLL && !(ntv.status & STA_PLL)) { 355 time_state = TIME_OK; 356 time_status = STA_UNSYNC; 357#ifdef PPS_SYNC 358 pps_shift = PPS_FAVG; 359#endif /* PPS_SYNC */ 360 } 361 time_status &= STA_RONLY; 362 time_status |= ntv.status & ~STA_RONLY; 363 } 364 if (modes & MOD_TIMECONST) { 365 if (ntv.constant < 0) 366 time_constant = 0; 367 else if (ntv.constant > MAXTC) 368 time_constant = MAXTC; 369 else 370 time_constant = ntv.constant; 371 } 372 if (modes & MOD_TAI) { 373 if (ntv.constant > 0) /* XXX zero & negative numbers ? */ 374 time_tai = ntv.constant; 375 } 376#ifdef PPS_SYNC 377 if (modes & MOD_PPSMAX) { 378 if (ntv.shift < PPS_FAVG) 379 pps_shiftmax = PPS_FAVG; 380 else if (ntv.shift > PPS_FAVGMAX) 381 pps_shiftmax = PPS_FAVGMAX; 382 else 383 pps_shiftmax = ntv.shift; 384 } 385#endif /* PPS_SYNC */ 386 if (modes & MOD_NANO) 387 time_status |= STA_NANO; 388 if (modes & MOD_MICRO) 389 time_status &= ~STA_NANO; 390 if (modes & MOD_CLKB) 391 time_status |= STA_CLK; 392 if (modes & MOD_CLKA) 393 time_status &= ~STA_CLK; 394 if (modes & MOD_FREQUENCY) { 395 freq = (ntv.freq * 1000LL) >> 16; 396 if (freq > MAXFREQ) 397 L_LINT(time_freq, MAXFREQ); 398 else if (freq < -MAXFREQ) 399 L_LINT(time_freq, -MAXFREQ); 400 else { 401 /* 402 * ntv.freq is [PPM * 2^16] = [us/s * 2^16] 403 * time_freq is [ns/s * 2^32] 404 */ 405 time_freq = ntv.freq * 1000LL * 65536LL; 406 } 407#ifdef PPS_SYNC 408 pps_freq = time_freq; 409#endif /* PPS_SYNC */ 410 } 411 if (modes & MOD_OFFSET) { 412 if (time_status & STA_NANO) 413 hardupdate(ntv.offset); 414 else 415 hardupdate(ntv.offset * 1000); 416 } 417 418 /* 419 * Retrieve all clock variables. Note that the TAI offset is 420 * returned only by ntp_gettime(); 421 */ 422 if (time_status & STA_NANO) 423 ntv.offset = L_GINT(time_offset); 424 else 425 ntv.offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */ 426 ntv.freq = L_GINT((time_freq / 1000LL) << 16); 427 ntv.maxerror = time_maxerror; 428 ntv.esterror = time_esterror; 429 ntv.status = time_status; 430 ntv.constant = time_constant; 431 if (time_status & STA_NANO) 432 ntv.precision = time_precision; 433 else 434 ntv.precision = time_precision / 1000; 435 ntv.tolerance = MAXFREQ * SCALE_PPM; 436#ifdef PPS_SYNC 437 ntv.shift = pps_shift; 438 ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16); 439 if (time_status & STA_NANO) 440 ntv.jitter = pps_jitter; 441 else 442 ntv.jitter = pps_jitter / 1000; 443 ntv.stabil = pps_stabil; 444 ntv.calcnt = pps_calcnt; 445 ntv.errcnt = pps_errcnt; 446 ntv.jitcnt = pps_jitcnt; 447 ntv.stbcnt = pps_stbcnt; 448#endif /* PPS_SYNC */ 449 splx(s); 450 451 error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv)); 452 if (error) 453 goto done2; 454 455 /* 456 * Status word error decode. See comments in 457 * ntp_gettime() routine. 458 */ 459 if (ntp_is_time_error()) 460 td->td_retval[0] = TIME_ERROR; 461 else 462 td->td_retval[0] = time_state; 463 464done2: 465 mtx_unlock(&Giant); 466 return (error); 467} 468 469/* 470 * second_overflow() - called after ntp_tick_adjust() 471 * 472 * This routine is ordinarily called immediately following the above 473 * routine ntp_tick_adjust(). While these two routines are normally 474 * combined, they are separated here only for the purposes of 475 * simulation. 476 */ 477void 478ntp_update_second(int64_t *adjustment, time_t *newsec) 479{ 480 int tickrate; 481 l_fp ftemp; /* 32/64-bit temporary */ 482 483 /* 484 * On rollover of the second both the nanosecond and microsecond 485 * clocks are updated and the state machine cranked as 486 * necessary. The phase adjustment to be used for the next 487 * second is calculated and the maximum error is increased by 488 * the tolerance. 489 */ 490 time_maxerror += MAXFREQ / 1000; 491 492 /* 493 * Leap second processing. If in leap-insert state at 494 * the end of the day, the system clock is set back one 495 * second; if in leap-delete state, the system clock is 496 * set ahead one second. The nano_time() routine or 497 * external clock driver will insure that reported time 498 * is always monotonic. 499 */ 500 switch (time_state) { 501 502 /* 503 * No warning. 504 */ 505 case TIME_OK: 506 if (time_status & STA_INS) 507 time_state = TIME_INS; 508 else if (time_status & STA_DEL) 509 time_state = TIME_DEL; 510 break; 511 512 /* 513 * Insert second 23:59:60 following second 514 * 23:59:59. 515 */ 516 case TIME_INS: 517 if (!(time_status & STA_INS)) 518 time_state = TIME_OK; 519 else if ((*newsec) % 86400 == 0) { 520 (*newsec)--; 521 time_state = TIME_OOP; 522 time_tai++; 523 } 524 break; 525 526 /* 527 * Delete second 23:59:59. 528 */ 529 case TIME_DEL: 530 if (!(time_status & STA_DEL)) 531 time_state = TIME_OK; 532 else if (((*newsec) + 1) % 86400 == 0) { 533 (*newsec)++; 534 time_tai--; 535 time_state = TIME_WAIT; 536 } 537 break; 538 539 /* 540 * Insert second in progress. 541 */ 542 case TIME_OOP: 543 time_state = TIME_WAIT; 544 break; 545 546 /* 547 * Wait for status bits to clear. 548 */ 549 case TIME_WAIT: 550 if (!(time_status & (STA_INS | STA_DEL))) 551 time_state = TIME_OK; 552 } 553 554 /* 555 * Compute the total time adjustment for the next second 556 * in ns. The offset is reduced by a factor depending on 557 * whether the PPS signal is operating. Note that the 558 * value is in effect scaled by the clock frequency, 559 * since the adjustment is added at each tick interrupt. 560 */ 561 ftemp = time_offset; 562#ifdef PPS_SYNC 563 /* XXX even if PPS signal dies we should finish adjustment ? */ 564 if (time_status & STA_PPSTIME && time_status & 565 STA_PPSSIGNAL) 566 L_RSHIFT(ftemp, pps_shift); 567 else 568 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 569#else 570 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 571#endif /* PPS_SYNC */ 572 time_adj = ftemp; 573 L_SUB(time_offset, ftemp); 574 L_ADD(time_adj, time_freq); 575 576 /* 577 * Apply any correction from adjtime(2). If more than one second 578 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM) 579 * until the last second is slewed the final < 500 usecs. 580 */ 581 if (time_adjtime != 0) { 582 if (time_adjtime > 1000000) 583 tickrate = 5000; 584 else if (time_adjtime < -1000000) 585 tickrate = -5000; 586 else if (time_adjtime > 500) 587 tickrate = 500; 588 else if (time_adjtime < -500) 589 tickrate = -500; 590 else 591 tickrate = time_adjtime; 592 time_adjtime -= tickrate; 593 L_LINT(ftemp, tickrate * 1000); 594 L_ADD(time_adj, ftemp); 595 } 596 *adjustment = time_adj; 597 598#ifdef PPS_SYNC 599 if (pps_valid > 0) 600 pps_valid--; 601 else 602 time_status &= ~STA_PPSSIGNAL; 603#endif /* PPS_SYNC */ 604} 605 606/* 607 * ntp_init() - initialize variables and structures 608 * 609 * This routine must be called after the kernel variables hz and tick 610 * are set or changed and before the next tick interrupt. In this 611 * particular implementation, these values are assumed set elsewhere in 612 * the kernel. The design allows the clock frequency and tick interval 613 * to be changed while the system is running. So, this routine should 614 * probably be integrated with the code that does that. 615 */ 616static void 617ntp_init() 618{ 619 620 /* 621 * The following variables are initialized only at startup. Only 622 * those structures not cleared by the compiler need to be 623 * initialized, and these only in the simulator. In the actual 624 * kernel, any nonzero values here will quickly evaporate. 625 */ 626 L_CLR(time_offset); 627 L_CLR(time_freq); 628#ifdef PPS_SYNC 629 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0; 630 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0; 631 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0; 632 pps_fcount = 0; 633 L_CLR(pps_freq); 634#endif /* PPS_SYNC */ 635} 636 637SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL); 638 639/* 640 * hardupdate() - local clock update 641 * 642 * This routine is called by ntp_adjtime() to update the local clock 643 * phase and frequency. The implementation is of an adaptive-parameter, 644 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new 645 * time and frequency offset estimates for each call. If the kernel PPS 646 * discipline code is configured (PPS_SYNC), the PPS signal itself 647 * determines the new time offset, instead of the calling argument. 648 * Presumably, calls to ntp_adjtime() occur only when the caller 649 * believes the local clock is valid within some bound (+-128 ms with 650 * NTP). If the caller's time is far different than the PPS time, an 651 * argument will ensue, and it's not clear who will lose. 652 * 653 * For uncompensated quartz crystal oscillators and nominal update 654 * intervals less than 256 s, operation should be in phase-lock mode, 655 * where the loop is disciplined to phase. For update intervals greater 656 * than 1024 s, operation should be in frequency-lock mode, where the 657 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode 658 * is selected by the STA_MODE status bit. 659 */ 660static void 661hardupdate(offset) 662 long offset; /* clock offset (ns) */ 663{ 664 long mtemp; 665 l_fp ftemp; 666 667 /* 668 * Select how the phase is to be controlled and from which 669 * source. If the PPS signal is present and enabled to 670 * discipline the time, the PPS offset is used; otherwise, the 671 * argument offset is used. 672 */ 673 if (!(time_status & STA_PLL)) 674 return; 675 if (!(time_status & STA_PPSTIME && time_status & 676 STA_PPSSIGNAL)) { 677 if (offset > MAXPHASE) 678 time_monitor = MAXPHASE; 679 else if (offset < -MAXPHASE) 680 time_monitor = -MAXPHASE; 681 else 682 time_monitor = offset; 683 L_LINT(time_offset, time_monitor); 684 } 685 686 /* 687 * Select how the frequency is to be controlled and in which 688 * mode (PLL or FLL). If the PPS signal is present and enabled 689 * to discipline the frequency, the PPS frequency is used; 690 * otherwise, the argument offset is used to compute it. 691 */ 692 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) { 693 time_reftime = time_second; 694 return; 695 } 696 if (time_status & STA_FREQHOLD || time_reftime == 0) 697 time_reftime = time_second; 698 mtemp = time_second - time_reftime; 699 L_LINT(ftemp, time_monitor); 700 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); 701 L_MPY(ftemp, mtemp); 702 L_ADD(time_freq, ftemp); 703 time_status &= ~STA_MODE; 704 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > 705 MAXSEC)) { 706 L_LINT(ftemp, (time_monitor << 4) / mtemp); 707 L_RSHIFT(ftemp, SHIFT_FLL + 4); 708 L_ADD(time_freq, ftemp); 709 time_status |= STA_MODE; 710 } 711 time_reftime = time_second; 712 if (L_GINT(time_freq) > MAXFREQ) 713 L_LINT(time_freq, MAXFREQ); 714 else if (L_GINT(time_freq) < -MAXFREQ) 715 L_LINT(time_freq, -MAXFREQ); 716} 717 718#ifdef PPS_SYNC 719/* 720 * hardpps() - discipline CPU clock oscillator to external PPS signal 721 * 722 * This routine is called at each PPS interrupt in order to discipline 723 * the CPU clock oscillator to the PPS signal. There are two independent 724 * first-order feedback loops, one for the phase, the other for the 725 * frequency. The phase loop measures and grooms the PPS phase offset 726 * and leaves it in a handy spot for the seconds overflow routine. The 727 * frequency loop averages successive PPS phase differences and 728 * calculates the PPS frequency offset, which is also processed by the 729 * seconds overflow routine. The code requires the caller to capture the 730 * time and architecture-dependent hardware counter values in 731 * nanoseconds at the on-time PPS signal transition. 732 * 733 * Note that, on some Unix systems this routine runs at an interrupt 734 * priority level higher than the timer interrupt routine hardclock(). 735 * Therefore, the variables used are distinct from the hardclock() 736 * variables, except for the actual time and frequency variables, which 737 * are determined by this routine and updated atomically. 738 */ 739void 740hardpps(tsp, nsec) 741 struct timespec *tsp; /* time at PPS */ 742 long nsec; /* hardware counter at PPS */ 743{ 744 long u_sec, u_nsec, v_nsec; /* temps */ 745 l_fp ftemp; 746 747 /* 748 * The signal is first processed by a range gate and frequency 749 * discriminator. The range gate rejects noise spikes outside 750 * the range +-500 us. The frequency discriminator rejects input 751 * signals with apparent frequency outside the range 1 +-500 752 * PPM. If two hits occur in the same second, we ignore the 753 * later hit; if not and a hit occurs outside the range gate, 754 * keep the later hit for later comparison, but do not process 755 * it. 756 */ 757 time_status |= STA_PPSSIGNAL | STA_PPSJITTER; 758 time_status &= ~(STA_PPSWANDER | STA_PPSERROR); 759 pps_valid = PPS_VALID; 760 u_sec = tsp->tv_sec; 761 u_nsec = tsp->tv_nsec; 762 if (u_nsec >= (NANOSECOND >> 1)) { 763 u_nsec -= NANOSECOND; 764 u_sec++; 765 } 766 v_nsec = u_nsec - pps_tf[0].tv_nsec; 767 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - 768 MAXFREQ) 769 return; 770 pps_tf[2] = pps_tf[1]; 771 pps_tf[1] = pps_tf[0]; 772 pps_tf[0].tv_sec = u_sec; 773 pps_tf[0].tv_nsec = u_nsec; 774 775 /* 776 * Compute the difference between the current and previous 777 * counter values. If the difference exceeds 0.5 s, assume it 778 * has wrapped around, so correct 1.0 s. If the result exceeds 779 * the tick interval, the sample point has crossed a tick 780 * boundary during the last second, so correct the tick. Very 781 * intricate. 782 */ 783 u_nsec = nsec; 784 if (u_nsec > (NANOSECOND >> 1)) 785 u_nsec -= NANOSECOND; 786 else if (u_nsec < -(NANOSECOND >> 1)) 787 u_nsec += NANOSECOND; 788 pps_fcount += u_nsec; 789 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) 790 return; 791 time_status &= ~STA_PPSJITTER; 792 793 /* 794 * A three-stage median filter is used to help denoise the PPS 795 * time. The median sample becomes the time offset estimate; the 796 * difference between the other two samples becomes the time 797 * dispersion (jitter) estimate. 798 */ 799 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { 800 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { 801 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ 802 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; 803 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { 804 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ 805 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; 806 } else { 807 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ 808 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; 809 } 810 } else { 811 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { 812 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ 813 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; 814 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { 815 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ 816 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; 817 } else { 818 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ 819 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; 820 } 821 } 822 823 /* 824 * Nominal jitter is due to PPS signal noise and interrupt 825 * latency. If it exceeds the popcorn threshold, the sample is 826 * discarded. otherwise, if so enabled, the time offset is 827 * updated. We can tolerate a modest loss of data here without 828 * much degrading time accuracy. 829 */ 830 if (u_nsec > (pps_jitter << PPS_POPCORN)) { 831 time_status |= STA_PPSJITTER; 832 pps_jitcnt++; 833 } else if (time_status & STA_PPSTIME) { 834 time_monitor = -v_nsec; 835 L_LINT(time_offset, time_monitor); 836 } 837 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; 838 u_sec = pps_tf[0].tv_sec - pps_lastsec; 839 if (u_sec < (1 << pps_shift)) 840 return; 841 842 /* 843 * At the end of the calibration interval the difference between 844 * the first and last counter values becomes the scaled 845 * frequency. It will later be divided by the length of the 846 * interval to determine the frequency update. If the frequency 847 * exceeds a sanity threshold, or if the actual calibration 848 * interval is not equal to the expected length, the data are 849 * discarded. We can tolerate a modest loss of data here without 850 * much degrading frequency accuracy. 851 */ 852 pps_calcnt++; 853 v_nsec = -pps_fcount; 854 pps_lastsec = pps_tf[0].tv_sec; 855 pps_fcount = 0; 856 u_nsec = MAXFREQ << pps_shift; 857 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << 858 pps_shift)) { 859 time_status |= STA_PPSERROR; 860 pps_errcnt++; 861 return; 862 } 863 864 /* 865 * Here the raw frequency offset and wander (stability) is 866 * calculated. If the wander is less than the wander threshold 867 * for four consecutive averaging intervals, the interval is 868 * doubled; if it is greater than the threshold for four 869 * consecutive intervals, the interval is halved. The scaled 870 * frequency offset is converted to frequency offset. The 871 * stability metric is calculated as the average of recent 872 * frequency changes, but is used only for performance 873 * monitoring. 874 */ 875 L_LINT(ftemp, v_nsec); 876 L_RSHIFT(ftemp, pps_shift); 877 L_SUB(ftemp, pps_freq); 878 u_nsec = L_GINT(ftemp); 879 if (u_nsec > PPS_MAXWANDER) { 880 L_LINT(ftemp, PPS_MAXWANDER); 881 pps_intcnt--; 882 time_status |= STA_PPSWANDER; 883 pps_stbcnt++; 884 } else if (u_nsec < -PPS_MAXWANDER) { 885 L_LINT(ftemp, -PPS_MAXWANDER); 886 pps_intcnt--; 887 time_status |= STA_PPSWANDER; 888 pps_stbcnt++; 889 } else { 890 pps_intcnt++; 891 } 892 if (pps_intcnt >= 4) { 893 pps_intcnt = 4; 894 if (pps_shift < pps_shiftmax) { 895 pps_shift++; 896 pps_intcnt = 0; 897 } 898 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { 899 pps_intcnt = -4; 900 if (pps_shift > PPS_FAVG) { 901 pps_shift--; 902 pps_intcnt = 0; 903 } 904 } 905 if (u_nsec < 0) 906 u_nsec = -u_nsec; 907 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; 908 909 /* 910 * The PPS frequency is recalculated and clamped to the maximum 911 * MAXFREQ. If enabled, the system clock frequency is updated as 912 * well. 913 */ 914 L_ADD(pps_freq, ftemp); 915 u_nsec = L_GINT(pps_freq); 916 if (u_nsec > MAXFREQ) 917 L_LINT(pps_freq, MAXFREQ); 918 else if (u_nsec < -MAXFREQ) 919 L_LINT(pps_freq, -MAXFREQ); 920 if (time_status & STA_PPSFREQ) 921 time_freq = pps_freq; 922} 923#endif /* PPS_SYNC */ 924 925#ifndef _SYS_SYSPROTO_H_ 926struct adjtime_args { 927 struct timeval *delta; 928 struct timeval *olddelta; 929}; 930#endif 931/* ARGSUSED */ 932int 933adjtime(struct thread *td, struct adjtime_args *uap) 934{ 935 struct timeval delta, olddelta, *deltap; 936 int error; 937 938 if (uap->delta) { 939 error = copyin(uap->delta, &delta, sizeof(delta)); 940 if (error) 941 return (error); 942 deltap = δ 943 } else 944 deltap = NULL; 945 error = kern_adjtime(td, deltap, &olddelta); 946 if (uap->olddelta && error == 0) 947 error = copyout(&olddelta, uap->olddelta, sizeof(olddelta)); 948 return (error); 949} 950 951int 952kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta) 953{ 954 struct timeval atv; 955 int error; 956 957 mtx_lock(&Giant); 958 if (olddelta) { 959 atv.tv_sec = time_adjtime / 1000000; 960 atv.tv_usec = time_adjtime % 1000000; 961 if (atv.tv_usec < 0) { 962 atv.tv_usec += 1000000; 963 atv.tv_sec--; 964 } 965 *olddelta = atv; 966 } 967 if (delta) { 968 if ((error = priv_check(td, PRIV_ADJTIME))) { 969 mtx_unlock(&Giant); 970 return (error); 971 } 972 time_adjtime = (int64_t)delta->tv_sec * 1000000 + 973 delta->tv_usec; 974 } 975 mtx_unlock(&Giant); 976 return (0); 977} 978 979