kern_ntptime.c revision 94754
1/*********************************************************************** 2 * * 3 * Copyright (c) David L. Mills 1993-2001 * 4 * * 5 * Permission to use, copy, modify, and distribute this software and * 6 * its documentation for any purpose and without fee is hereby * 7 * granted, provided that the above copyright notice appears in all * 8 * copies and that both the copyright notice and this permission * 9 * notice appear in supporting documentation, and that the name * 10 * University of Delaware not be used in advertising or publicity * 11 * pertaining to distribution of the software without specific, * 12 * written prior permission. The University of Delaware makes no * 13 * representations about the suitability this software for any * 14 * purpose. It is provided "as is" without express or implied * 15 * warranty. * 16 * * 17 **********************************************************************/ 18 19/* 20 * Adapted from the original sources for FreeBSD and timecounters by: 21 * Poul-Henning Kamp <phk@FreeBSD.org>. 22 * 23 * The 32bit version of the "LP" macros seems a bit past its "sell by" 24 * date so I have retained only the 64bit version and included it directly 25 * in this file. 26 * 27 * Only minor changes done to interface with the timecounters over in 28 * sys/kern/kern_clock.c. Some of the comments below may be (even more) 29 * confusing and/or plain wrong in that context. 30 * 31 * $FreeBSD: head/sys/kern/kern_ntptime.c 94754 2002-04-15 12:23:11Z phk $ 32 */ 33 34#include "opt_ntp.h" 35 36#include <sys/param.h> 37#include <sys/systm.h> 38#include <sys/sysproto.h> 39#include <sys/kernel.h> 40#include <sys/proc.h> 41#include <sys/lock.h> 42#include <sys/mutex.h> 43#include <sys/time.h> 44#include <sys/timex.h> 45#include <sys/timetc.h> 46#include <sys/timepps.h> 47#include <sys/sysctl.h> 48 49/* 50 * Single-precision macros for 64-bit machines 51 */ 52typedef long long l_fp; 53#define L_ADD(v, u) ((v) += (u)) 54#define L_SUB(v, u) ((v) -= (u)) 55#define L_ADDHI(v, a) ((v) += (long long)(a) << 32) 56#define L_NEG(v) ((v) = -(v)) 57#define L_RSHIFT(v, n) \ 58 do { \ 59 if ((v) < 0) \ 60 (v) = -(-(v) >> (n)); \ 61 else \ 62 (v) = (v) >> (n); \ 63 } while (0) 64#define L_MPY(v, a) ((v) *= (a)) 65#define L_CLR(v) ((v) = 0) 66#define L_ISNEG(v) ((v) < 0) 67#define L_LINT(v, a) ((v) = (long long)(a) << 32) 68#define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32) 69 70/* 71 * Generic NTP kernel interface 72 * 73 * These routines constitute the Network Time Protocol (NTP) interfaces 74 * for user and daemon application programs. The ntp_gettime() routine 75 * provides the time, maximum error (synch distance) and estimated error 76 * (dispersion) to client user application programs. The ntp_adjtime() 77 * routine is used by the NTP daemon to adjust the system clock to an 78 * externally derived time. The time offset and related variables set by 79 * this routine are used by other routines in this module to adjust the 80 * phase and frequency of the clock discipline loop which controls the 81 * system clock. 82 * 83 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO 84 * defined), the time at each tick interrupt is derived directly from 85 * the kernel time variable. When the kernel time is reckoned in 86 * microseconds, (NTP_NANO undefined), the time is derived from the 87 * kernel time variable together with a variable representing the 88 * leftover nanoseconds at the last tick interrupt. In either case, the 89 * current nanosecond time is reckoned from these values plus an 90 * interpolated value derived by the clock routines in another 91 * architecture-specific module. The interpolation can use either a 92 * dedicated counter or a processor cycle counter (PCC) implemented in 93 * some architectures. 94 * 95 * Note that all routines must run at priority splclock or higher. 96 */ 97/* 98 * Phase/frequency-lock loop (PLL/FLL) definitions 99 * 100 * The nanosecond clock discipline uses two variable types, time 101 * variables and frequency variables. Both types are represented as 64- 102 * bit fixed-point quantities with the decimal point between two 32-bit 103 * halves. On a 32-bit machine, each half is represented as a single 104 * word and mathematical operations are done using multiple-precision 105 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is 106 * used. 107 * 108 * A time variable is a signed 64-bit fixed-point number in ns and 109 * fraction. It represents the remaining time offset to be amortized 110 * over succeeding tick interrupts. The maximum time offset is about 111 * 0.5 s and the resolution is about 2.3e-10 ns. 112 * 113 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 114 * 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 1 115 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 116 * |s s s| ns | 117 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 118 * | fraction | 119 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 120 * 121 * A frequency variable is a signed 64-bit fixed-point number in ns/s 122 * and fraction. It represents the ns and fraction to be added to the 123 * kernel time variable at each second. The maximum frequency offset is 124 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s. 125 * 126 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 127 * 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 1 128 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 129 * |s s s s s s s s s s s s s| ns/s | 130 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 131 * | fraction | 132 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 133 */ 134/* 135 * The following variables establish the state of the PLL/FLL and the 136 * residual time and frequency offset of the local clock. 137 */ 138#define SHIFT_PLL 4 /* PLL loop gain (shift) */ 139#define SHIFT_FLL 2 /* FLL loop gain (shift) */ 140 141static int time_state = TIME_OK; /* clock state */ 142static int time_status = STA_UNSYNC; /* clock status bits */ 143static long time_tai; /* TAI offset (s) */ 144static long time_monitor; /* last time offset scaled (ns) */ 145static long time_constant; /* poll interval (shift) (s) */ 146static long time_precision = 1; /* clock precision (ns) */ 147static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */ 148static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */ 149static long time_reftime; /* time at last adjustment (s) */ 150static long time_tick; /* nanoseconds per tick (ns) */ 151static l_fp time_offset; /* time offset (ns) */ 152static l_fp time_freq; /* frequency offset (ns/s) */ 153static l_fp time_adj; /* tick adjust (ns/s) */ 154 155static int64_t time_adjtime; /* correction from adjtime(2) (usec) */ 156 157#ifdef PPS_SYNC 158/* 159 * The following variables are used when a pulse-per-second (PPS) signal 160 * is available and connected via a modem control lead. They establish 161 * the engineering parameters of the clock discipline loop when 162 * controlled by the PPS signal. 163 */ 164#define PPS_FAVG 2 /* min freq avg interval (s) (shift) */ 165#define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */ 166#define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */ 167#define PPS_PAVG 4 /* phase avg interval (s) (shift) */ 168#define PPS_VALID 120 /* PPS signal watchdog max (s) */ 169#define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */ 170#define PPS_POPCORN 2 /* popcorn spike threshold (shift) */ 171 172static struct timespec pps_tf[3]; /* phase median filter */ 173static l_fp pps_freq; /* scaled frequency offset (ns/s) */ 174static long pps_fcount; /* frequency accumulator */ 175static long pps_jitter; /* nominal jitter (ns) */ 176static long pps_stabil; /* nominal stability (scaled ns/s) */ 177static long pps_lastsec; /* time at last calibration (s) */ 178static int pps_valid; /* signal watchdog counter */ 179static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */ 180static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */ 181static int pps_intcnt; /* wander counter */ 182 183/* 184 * PPS signal quality monitors 185 */ 186static long pps_calcnt; /* calibration intervals */ 187static long pps_jitcnt; /* jitter limit exceeded */ 188static long pps_stbcnt; /* stability limit exceeded */ 189static long pps_errcnt; /* calibration errors */ 190#endif /* PPS_SYNC */ 191/* 192 * End of phase/frequency-lock loop (PLL/FLL) definitions 193 */ 194 195static void ntp_init(void); 196static void hardupdate(long offset); 197 198/* 199 * ntp_gettime() - NTP user application interface 200 * 201 * See the timex.h header file for synopsis and API description. Note 202 * that the TAI offset is returned in the ntvtimeval.tai structure 203 * member. 204 */ 205static int 206ntp_sysctl(SYSCTL_HANDLER_ARGS) 207{ 208 struct ntptimeval ntv; /* temporary structure */ 209 struct timespec atv; /* nanosecond time */ 210 211 nanotime(&atv); 212 ntv.time.tv_sec = atv.tv_sec; 213 ntv.time.tv_nsec = atv.tv_nsec; 214 ntv.maxerror = time_maxerror; 215 ntv.esterror = time_esterror; 216 ntv.tai = time_tai; 217 ntv.time_state = time_state; 218 219 /* 220 * Status word error decode. If any of these conditions occur, 221 * an error is returned, instead of the status word. Most 222 * applications will care only about the fact the system clock 223 * may not be trusted, not about the details. 224 * 225 * Hardware or software error 226 */ 227 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 228 229 /* 230 * PPS signal lost when either time or frequency synchronization 231 * requested 232 */ 233 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 234 !(time_status & STA_PPSSIGNAL)) || 235 236 /* 237 * PPS jitter exceeded when time synchronization requested 238 */ 239 (time_status & STA_PPSTIME && 240 time_status & STA_PPSJITTER) || 241 242 /* 243 * PPS wander exceeded or calibration error when frequency 244 * synchronization requested 245 */ 246 (time_status & STA_PPSFREQ && 247 time_status & (STA_PPSWANDER | STA_PPSERROR))) 248 ntv.time_state = TIME_ERROR; 249 return (sysctl_handle_opaque(oidp, &ntv, sizeof ntv, req)); 250} 251 252SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, ""); 253SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD, 254 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", ""); 255 256#ifdef PPS_SYNC 257SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, &pps_shiftmax, 0, ""); 258SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, &pps_shift, 0, ""); 259SYSCTL_INT(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, &time_monitor, 0, ""); 260 261SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD, &pps_freq, sizeof(pps_freq), "I", ""); 262SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD, &time_freq, sizeof(time_freq), "I", ""); 263#endif 264/* 265 * ntp_adjtime() - NTP daemon application interface 266 * 267 * See the timex.h header file for synopsis and API description. Note 268 * that the timex.constant structure member has a dual purpose to set 269 * the time constant and to set the TAI offset. 270 */ 271#ifndef _SYS_SYSPROTO_H_ 272struct ntp_adjtime_args { 273 struct timex *tp; 274}; 275#endif 276 277/* 278 * MPSAFE 279 */ 280int 281ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap) 282{ 283 struct timex ntv; /* temporary structure */ 284 long freq; /* frequency ns/s) */ 285 int modes; /* mode bits from structure */ 286 int s; /* caller priority */ 287 int error; 288 289 error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv)); 290 if (error) 291 return(error); 292 293 /* 294 * Update selected clock variables - only the superuser can 295 * change anything. Note that there is no error checking here on 296 * the assumption the superuser should know what it is doing. 297 * Note that either the time constant or TAI offset are loaded 298 * from the ntv.constant member, depending on the mode bits. If 299 * the STA_PLL bit in the status word is cleared, the state and 300 * status words are reset to the initial values at boot. 301 */ 302 mtx_lock(&Giant); 303 modes = ntv.modes; 304 if (modes) 305 error = suser(td); 306 if (error) 307 goto done2; 308 s = splclock(); 309 if (modes & MOD_MAXERROR) 310 time_maxerror = ntv.maxerror; 311 if (modes & MOD_ESTERROR) 312 time_esterror = ntv.esterror; 313 if (modes & MOD_STATUS) { 314 if (time_status & STA_PLL && !(ntv.status & STA_PLL)) { 315 time_state = TIME_OK; 316 time_status = STA_UNSYNC; 317#ifdef PPS_SYNC 318 pps_shift = PPS_FAVG; 319#endif /* PPS_SYNC */ 320 } 321 time_status &= STA_RONLY; 322 time_status |= ntv.status & ~STA_RONLY; 323 } 324 if (modes & MOD_TIMECONST) { 325 if (ntv.constant < 0) 326 time_constant = 0; 327 else if (ntv.constant > MAXTC) 328 time_constant = MAXTC; 329 else 330 time_constant = ntv.constant; 331 } 332 if (modes & MOD_TAI) { 333 if (ntv.constant > 0) /* XXX zero & negative numbers ? */ 334 time_tai = ntv.constant; 335 } 336#ifdef PPS_SYNC 337 if (modes & MOD_PPSMAX) { 338 if (ntv.shift < PPS_FAVG) 339 pps_shiftmax = PPS_FAVG; 340 else if (ntv.shift > PPS_FAVGMAX) 341 pps_shiftmax = PPS_FAVGMAX; 342 else 343 pps_shiftmax = ntv.shift; 344 } 345#endif /* PPS_SYNC */ 346 if (modes & MOD_NANO) 347 time_status |= STA_NANO; 348 if (modes & MOD_MICRO) 349 time_status &= ~STA_NANO; 350 if (modes & MOD_CLKB) 351 time_status |= STA_CLK; 352 if (modes & MOD_CLKA) 353 time_status &= ~STA_CLK; 354 if (modes & MOD_OFFSET) { 355 if (time_status & STA_NANO) 356 hardupdate(ntv.offset); 357 else 358 hardupdate(ntv.offset * 1000); 359 } 360 if (modes & MOD_FREQUENCY) { 361 freq = (ntv.freq * 1000LL) >> 16; 362 if (freq > MAXFREQ) 363 L_LINT(time_freq, MAXFREQ); 364 else if (freq < -MAXFREQ) 365 L_LINT(time_freq, -MAXFREQ); 366 else 367 L_LINT(time_freq, freq); 368#ifdef PPS_SYNC 369 pps_freq = time_freq; 370#endif /* PPS_SYNC */ 371 } 372 373 /* 374 * Retrieve all clock variables. Note that the TAI offset is 375 * returned only by ntp_gettime(); 376 */ 377 if (time_status & STA_NANO) 378 ntv.offset = L_GINT(time_offset); 379 else 380 ntv.offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */ 381 ntv.freq = L_GINT((time_freq / 1000LL) << 16); 382 ntv.maxerror = time_maxerror; 383 ntv.esterror = time_esterror; 384 ntv.status = time_status; 385 ntv.constant = time_constant; 386 if (time_status & STA_NANO) 387 ntv.precision = time_precision; 388 else 389 ntv.precision = time_precision / 1000; 390 ntv.tolerance = MAXFREQ * SCALE_PPM; 391#ifdef PPS_SYNC 392 ntv.shift = pps_shift; 393 ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16); 394 if (time_status & STA_NANO) 395 ntv.jitter = pps_jitter; 396 else 397 ntv.jitter = pps_jitter / 1000; 398 ntv.stabil = pps_stabil; 399 ntv.calcnt = pps_calcnt; 400 ntv.errcnt = pps_errcnt; 401 ntv.jitcnt = pps_jitcnt; 402 ntv.stbcnt = pps_stbcnt; 403#endif /* PPS_SYNC */ 404 splx(s); 405 406 error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv)); 407 if (error) 408 goto done2; 409 410 /* 411 * Status word error decode. See comments in 412 * ntp_gettime() routine. 413 */ 414 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 415 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 416 !(time_status & STA_PPSSIGNAL)) || 417 (time_status & STA_PPSTIME && 418 time_status & STA_PPSJITTER) || 419 (time_status & STA_PPSFREQ && 420 time_status & (STA_PPSWANDER | STA_PPSERROR))) { 421 td->td_retval[0] = TIME_ERROR; 422 } else { 423 td->td_retval[0] = time_state; 424 } 425done2: 426 mtx_unlock(&Giant); 427 return (error); 428} 429 430/* 431 * second_overflow() - called after ntp_tick_adjust() 432 * 433 * This routine is ordinarily called immediately following the above 434 * routine ntp_tick_adjust(). While these two routines are normally 435 * combined, they are separated here only for the purposes of 436 * simulation. 437 */ 438void 439ntp_update_second(struct timecounter *tcp) 440{ 441 u_int32_t *newsec; 442 int tickrate; 443 l_fp ftemp; /* 32/64-bit temporary */ 444 445 newsec = &tcp->tc_offset.sec; 446 /* 447 * On rollover of the second both the nanosecond and microsecond 448 * clocks are updated and the state machine cranked as 449 * necessary. The phase adjustment to be used for the next 450 * second is calculated and the maximum error is increased by 451 * the tolerance. 452 */ 453 time_maxerror += MAXFREQ / 1000; 454 455 /* 456 * Leap second processing. If in leap-insert state at 457 * the end of the day, the system clock is set back one 458 * second; if in leap-delete state, the system clock is 459 * set ahead one second. The nano_time() routine or 460 * external clock driver will insure that reported time 461 * is always monotonic. 462 */ 463 switch (time_state) { 464 465 /* 466 * No warning. 467 */ 468 case TIME_OK: 469 if (time_status & STA_INS) 470 time_state = TIME_INS; 471 else if (time_status & STA_DEL) 472 time_state = TIME_DEL; 473 break; 474 475 /* 476 * Insert second 23:59:60 following second 477 * 23:59:59. 478 */ 479 case TIME_INS: 480 if (!(time_status & STA_INS)) 481 time_state = TIME_OK; 482 else if ((*newsec) % 86400 == 0) { 483 (*newsec)--; 484 time_state = TIME_OOP; 485 } 486 break; 487 488 /* 489 * Delete second 23:59:59. 490 */ 491 case TIME_DEL: 492 if (!(time_status & STA_DEL)) 493 time_state = TIME_OK; 494 else if (((*newsec) + 1) % 86400 == 0) { 495 (*newsec)++; 496 time_tai--; 497 time_state = TIME_WAIT; 498 } 499 break; 500 501 /* 502 * Insert second in progress. 503 */ 504 case TIME_OOP: 505 time_tai++; 506 time_state = TIME_WAIT; 507 break; 508 509 /* 510 * Wait for status bits to clear. 511 */ 512 case TIME_WAIT: 513 if (!(time_status & (STA_INS | STA_DEL))) 514 time_state = TIME_OK; 515 } 516 517 /* 518 * Compute the total time adjustment for the next second 519 * in ns. The offset is reduced by a factor depending on 520 * whether the PPS signal is operating. Note that the 521 * value is in effect scaled by the clock frequency, 522 * since the adjustment is added at each tick interrupt. 523 */ 524 ftemp = time_offset; 525#ifdef PPS_SYNC 526 /* XXX even if PPS signal dies we should finish adjustment ? */ 527 if (time_status & STA_PPSTIME && time_status & 528 STA_PPSSIGNAL) 529 L_RSHIFT(ftemp, pps_shift); 530 else 531 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 532#else 533 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 534#endif /* PPS_SYNC */ 535 time_adj = ftemp; 536 L_SUB(time_offset, ftemp); 537 L_ADD(time_adj, time_freq); 538 539 /* 540 * Apply any correction from adjtime(2). If more than one second 541 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM) 542 * until the last second is slewed the final < 500 usecs. 543 */ 544 if (time_adjtime != 0) { 545 if (time_adjtime > 1000000) 546 tickrate = 5000; 547 else if (time_adjtime < -1000000) 548 tickrate = -5000; 549 else if (time_adjtime > 500) 550 tickrate = 500; 551 else if (time_adjtime < -500) 552 tickrate = -500; 553 else if (time_adjtime != 0) 554 tickrate = time_adjtime; 555 else 556 tickrate = 0; /* GCC sucks! */ 557 time_adjtime -= tickrate; 558 L_LINT(ftemp, tickrate * 1000); 559 L_ADD(time_adj, ftemp); 560 } 561 tcp->tc_adjustment = time_adj; 562 563#ifdef PPS_SYNC 564 if (pps_valid > 0) 565 pps_valid--; 566 else 567 time_status &= ~STA_PPSSIGNAL; 568#endif /* PPS_SYNC */ 569} 570 571/* 572 * ntp_init() - initialize variables and structures 573 * 574 * This routine must be called after the kernel variables hz and tick 575 * are set or changed and before the next tick interrupt. In this 576 * particular implementation, these values are assumed set elsewhere in 577 * the kernel. The design allows the clock frequency and tick interval 578 * to be changed while the system is running. So, this routine should 579 * probably be integrated with the code that does that. 580 */ 581static void 582ntp_init() 583{ 584 585 /* 586 * The following variable must be initialized any time the 587 * kernel variable hz is changed. 588 */ 589 time_tick = NANOSECOND / hz; 590 591 /* 592 * The following variables are initialized only at startup. Only 593 * those structures not cleared by the compiler need to be 594 * initialized, and these only in the simulator. In the actual 595 * kernel, any nonzero values here will quickly evaporate. 596 */ 597 L_CLR(time_offset); 598 L_CLR(time_freq); 599#ifdef PPS_SYNC 600 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0; 601 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0; 602 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0; 603 pps_fcount = 0; 604 L_CLR(pps_freq); 605#endif /* PPS_SYNC */ 606} 607 608SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, ntp_init, NULL) 609 610/* 611 * hardupdate() - local clock update 612 * 613 * This routine is called by ntp_adjtime() to update the local clock 614 * phase and frequency. The implementation is of an adaptive-parameter, 615 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new 616 * time and frequency offset estimates for each call. If the kernel PPS 617 * discipline code is configured (PPS_SYNC), the PPS signal itself 618 * determines the new time offset, instead of the calling argument. 619 * Presumably, calls to ntp_adjtime() occur only when the caller 620 * believes the local clock is valid within some bound (+-128 ms with 621 * NTP). If the caller's time is far different than the PPS time, an 622 * argument will ensue, and it's not clear who will lose. 623 * 624 * For uncompensated quartz crystal oscillators and nominal update 625 * intervals less than 256 s, operation should be in phase-lock mode, 626 * where the loop is disciplined to phase. For update intervals greater 627 * than 1024 s, operation should be in frequency-lock mode, where the 628 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode 629 * is selected by the STA_MODE status bit. 630 */ 631static void 632hardupdate(offset) 633 long offset; /* clock offset (ns) */ 634{ 635 long mtemp; 636 l_fp ftemp; 637 638 /* 639 * Select how the phase is to be controlled and from which 640 * source. If the PPS signal is present and enabled to 641 * discipline the time, the PPS offset is used; otherwise, the 642 * argument offset is used. 643 */ 644 if (!(time_status & STA_PLL)) 645 return; 646 if (!(time_status & STA_PPSTIME && time_status & 647 STA_PPSSIGNAL)) { 648 if (offset > MAXPHASE) 649 time_monitor = MAXPHASE; 650 else if (offset < -MAXPHASE) 651 time_monitor = -MAXPHASE; 652 else 653 time_monitor = offset; 654 L_LINT(time_offset, time_monitor); 655 } 656 657 /* 658 * Select how the frequency is to be controlled and in which 659 * mode (PLL or FLL). If the PPS signal is present and enabled 660 * to discipline the frequency, the PPS frequency is used; 661 * otherwise, the argument offset is used to compute it. 662 */ 663 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) { 664 time_reftime = time_second; 665 return; 666 } 667 if (time_status & STA_FREQHOLD || time_reftime == 0) 668 time_reftime = time_second; 669 mtemp = time_second - time_reftime; 670 L_LINT(ftemp, time_monitor); 671 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); 672 L_MPY(ftemp, mtemp); 673 L_ADD(time_freq, ftemp); 674 time_status &= ~STA_MODE; 675 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > 676 MAXSEC)) { 677 L_LINT(ftemp, (time_monitor << 4) / mtemp); 678 L_RSHIFT(ftemp, SHIFT_FLL + 4); 679 L_ADD(time_freq, ftemp); 680 time_status |= STA_MODE; 681 } 682 time_reftime = time_second; 683 if (L_GINT(time_freq) > MAXFREQ) 684 L_LINT(time_freq, MAXFREQ); 685 else if (L_GINT(time_freq) < -MAXFREQ) 686 L_LINT(time_freq, -MAXFREQ); 687} 688 689#ifdef PPS_SYNC 690/* 691 * hardpps() - discipline CPU clock oscillator to external PPS signal 692 * 693 * This routine is called at each PPS interrupt in order to discipline 694 * the CPU clock oscillator to the PPS signal. There are two independent 695 * first-order feedback loops, one for the phase, the other for the 696 * frequency. The phase loop measures and grooms the PPS phase offset 697 * and leaves it in a handy spot for the seconds overflow routine. The 698 * frequency loop averages successive PPS phase differences and 699 * calculates the PPS frequency offset, which is also processed by the 700 * seconds overflow routine. The code requires the caller to capture the 701 * time and architecture-dependent hardware counter values in 702 * nanoseconds at the on-time PPS signal transition. 703 * 704 * Note that, on some Unix systems this routine runs at an interrupt 705 * priority level higher than the timer interrupt routine hardclock(). 706 * Therefore, the variables used are distinct from the hardclock() 707 * variables, except for the actual time and frequency variables, which 708 * are determined by this routine and updated atomically. 709 */ 710void 711hardpps(tsp, nsec) 712 struct timespec *tsp; /* time at PPS */ 713 long nsec; /* hardware counter at PPS */ 714{ 715 long u_sec, u_nsec, v_nsec; /* temps */ 716 l_fp ftemp; 717 718 /* 719 * The signal is first processed by a range gate and frequency 720 * discriminator. The range gate rejects noise spikes outside 721 * the range +-500 us. The frequency discriminator rejects input 722 * signals with apparent frequency outside the range 1 +-500 723 * PPM. If two hits occur in the same second, we ignore the 724 * later hit; if not and a hit occurs outside the range gate, 725 * keep the later hit for later comparison, but do not process 726 * it. 727 */ 728 time_status |= STA_PPSSIGNAL | STA_PPSJITTER; 729 time_status &= ~(STA_PPSWANDER | STA_PPSERROR); 730 pps_valid = PPS_VALID; 731 u_sec = tsp->tv_sec; 732 u_nsec = tsp->tv_nsec; 733 if (u_nsec >= (NANOSECOND >> 1)) { 734 u_nsec -= NANOSECOND; 735 u_sec++; 736 } 737 v_nsec = u_nsec - pps_tf[0].tv_nsec; 738 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - 739 MAXFREQ) 740 return; 741 pps_tf[2] = pps_tf[1]; 742 pps_tf[1] = pps_tf[0]; 743 pps_tf[0].tv_sec = u_sec; 744 pps_tf[0].tv_nsec = u_nsec; 745 746 /* 747 * Compute the difference between the current and previous 748 * counter values. If the difference exceeds 0.5 s, assume it 749 * has wrapped around, so correct 1.0 s. If the result exceeds 750 * the tick interval, the sample point has crossed a tick 751 * boundary during the last second, so correct the tick. Very 752 * intricate. 753 */ 754 u_nsec = nsec; 755 if (u_nsec > (NANOSECOND >> 1)) 756 u_nsec -= NANOSECOND; 757 else if (u_nsec < -(NANOSECOND >> 1)) 758 u_nsec += NANOSECOND; 759 pps_fcount += u_nsec; 760 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) 761 return; 762 time_status &= ~STA_PPSJITTER; 763 764 /* 765 * A three-stage median filter is used to help denoise the PPS 766 * time. The median sample becomes the time offset estimate; the 767 * difference between the other two samples becomes the time 768 * dispersion (jitter) estimate. 769 */ 770 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { 771 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { 772 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ 773 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; 774 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { 775 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ 776 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; 777 } else { 778 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ 779 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; 780 } 781 } else { 782 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { 783 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ 784 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; 785 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { 786 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ 787 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; 788 } else { 789 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ 790 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; 791 } 792 } 793 794 /* 795 * Nominal jitter is due to PPS signal noise and interrupt 796 * latency. If it exceeds the popcorn threshold, the sample is 797 * discarded. otherwise, if so enabled, the time offset is 798 * updated. We can tolerate a modest loss of data here without 799 * much degrading time accuracy. 800 */ 801 if (u_nsec > (pps_jitter << PPS_POPCORN)) { 802 time_status |= STA_PPSJITTER; 803 pps_jitcnt++; 804 } else if (time_status & STA_PPSTIME) { 805 time_monitor = -v_nsec; 806 L_LINT(time_offset, time_monitor); 807 } 808 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; 809 u_sec = pps_tf[0].tv_sec - pps_lastsec; 810 if (u_sec < (1 << pps_shift)) 811 return; 812 813 /* 814 * At the end of the calibration interval the difference between 815 * the first and last counter values becomes the scaled 816 * frequency. It will later be divided by the length of the 817 * interval to determine the frequency update. If the frequency 818 * exceeds a sanity threshold, or if the actual calibration 819 * interval is not equal to the expected length, the data are 820 * discarded. We can tolerate a modest loss of data here without 821 * much degrading frequency accuracy. 822 */ 823 pps_calcnt++; 824 v_nsec = -pps_fcount; 825 pps_lastsec = pps_tf[0].tv_sec; 826 pps_fcount = 0; 827 u_nsec = MAXFREQ << pps_shift; 828 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << 829 pps_shift)) { 830 time_status |= STA_PPSERROR; 831 pps_errcnt++; 832 return; 833 } 834 835 /* 836 * Here the raw frequency offset and wander (stability) is 837 * calculated. If the wander is less than the wander threshold 838 * for four consecutive averaging intervals, the interval is 839 * doubled; if it is greater than the threshold for four 840 * consecutive intervals, the interval is halved. The scaled 841 * frequency offset is converted to frequency offset. The 842 * stability metric is calculated as the average of recent 843 * frequency changes, but is used only for performance 844 * monitoring. 845 */ 846 L_LINT(ftemp, v_nsec); 847 L_RSHIFT(ftemp, pps_shift); 848 L_SUB(ftemp, pps_freq); 849 u_nsec = L_GINT(ftemp); 850 if (u_nsec > PPS_MAXWANDER) { 851 L_LINT(ftemp, PPS_MAXWANDER); 852 pps_intcnt--; 853 time_status |= STA_PPSWANDER; 854 pps_stbcnt++; 855 } else if (u_nsec < -PPS_MAXWANDER) { 856 L_LINT(ftemp, -PPS_MAXWANDER); 857 pps_intcnt--; 858 time_status |= STA_PPSWANDER; 859 pps_stbcnt++; 860 } else { 861 pps_intcnt++; 862 } 863 if (pps_intcnt >= 4) { 864 pps_intcnt = 4; 865 if (pps_shift < pps_shiftmax) { 866 pps_shift++; 867 pps_intcnt = 0; 868 } 869 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { 870 pps_intcnt = -4; 871 if (pps_shift > PPS_FAVG) { 872 pps_shift--; 873 pps_intcnt = 0; 874 } 875 } 876 if (u_nsec < 0) 877 u_nsec = -u_nsec; 878 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; 879 880 /* 881 * The PPS frequency is recalculated and clamped to the maximum 882 * MAXFREQ. If enabled, the system clock frequency is updated as 883 * well. 884 */ 885 L_ADD(pps_freq, ftemp); 886 u_nsec = L_GINT(pps_freq); 887 if (u_nsec > MAXFREQ) 888 L_LINT(pps_freq, MAXFREQ); 889 else if (u_nsec < -MAXFREQ) 890 L_LINT(pps_freq, -MAXFREQ); 891 if (time_status & STA_PPSFREQ) 892 time_freq = pps_freq; 893} 894#endif /* PPS_SYNC */ 895 896#ifndef _SYS_SYSPROTO_H_ 897struct adjtime_args { 898 struct timeval *delta; 899 struct timeval *olddelta; 900}; 901#endif 902/* 903 * MPSAFE 904 */ 905/* ARGSUSED */ 906int 907adjtime(struct thread *td, struct adjtime_args *uap) 908{ 909 struct timeval atv; 910 int error; 911 912 mtx_lock(&Giant); 913 914 if ((error = suser(td))) 915 goto done2; 916 if (uap->olddelta) { 917 atv.tv_sec = time_adjtime / 1000000; 918 atv.tv_usec = time_adjtime % 1000000; 919 if (atv.tv_usec < 0) { 920 atv.tv_usec += 1000000; 921 atv.tv_sec--; 922 } 923 printf("Old: time_adjtime = %ld.%06ld %lld\n", 924 atv.tv_sec, atv.tv_usec, time_adjtime); 925 error = copyout(&atv, uap->olddelta, sizeof(atv)); 926 if (error) 927 goto done2; 928 } 929 if (uap->delta) { 930 error = copyin(uap->delta, &atv, sizeof(atv)); 931 if (error) 932 goto done2; 933 time_adjtime = (int64_t)atv.tv_sec * 1000000 + atv.tv_usec; 934 printf("New: time_adjtime = %ld.%06ld %lld\n", 935 atv.tv_sec, atv.tv_usec, time_adjtime); 936 } 937done2: 938 mtx_unlock(&Giant); 939 return (error); 940} 941 942