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("$FreeBSD$"); 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/eventhandler.h> 42 #include <sys/kernel.h> 43 #include <sys/priv.h> 44 #include <sys/proc.h> 45 #include <sys/lock.h> 46 #include <sys/mutex.h> 47 #include <sys/time.h> 48 #include <sys/timex.h> 49 #include <sys/timetc.h> 50 #include <sys/timepps.h> 51 #include <sys/syscallsubr.h> 52 #include <sys/sysctl.h> 53 54 #ifdef PPS_SYNC 55 FEATURE(pps_sync, "Support usage of external PPS signal by kernel PLL"); 56 #endif 57 58 /* 59 * Single-precision macros for 64-bit machines 60 */ 61 typedef int64_t l_fp; 62 #define L_ADD(v, u) ((v) += (u)) 63 #define L_SUB(v, u) ((v) -= (u)) 64 #define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32) 65 #define L_NEG(v) ((v) = -(v)) 66 #define L_RSHIFT(v, n) \ 67 do { \ 68 if ((v) < 0) \ 69 (v) = -(-(v) >> (n)); \ 70 else \ 71 (v) = (v) >> (n); \ 72 } while (0) 73 #define L_MPY(v, a) ((v) *= (a)) 74 #define L_CLR(v) ((v) = 0) 75 #define L_ISNEG(v) ((v) < 0) 76 #define L_LINT(v, a) ((v) = (int64_t)(a) << 32) 77 #define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32) 78 79 /* 80 * Generic NTP kernel interface 81 * 82 * These routines constitute the Network Time Protocol (NTP) interfaces 83 * for user and daemon application programs. The ntp_gettime() routine 84 * provides the time, maximum error (synch distance) and estimated error 85 * (dispersion) to client user application programs. The ntp_adjtime() 86 * routine is used by the NTP daemon to adjust the system clock to an 87 * externally derived time. The time offset and related variables set by 88 * this routine are used by other routines in this module to adjust the 89 * phase and frequency of the clock discipline loop which controls the 90 * system clock. 91 * 92 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO 93 * defined), the time at each tick interrupt is derived directly from 94 * the kernel time variable. When the kernel time is reckoned in 95 * microseconds, (NTP_NANO undefined), the time is derived from the 96 * kernel time variable together with a variable representing the 97 * leftover nanoseconds at the last tick interrupt. In either case, the 98 * current nanosecond time is reckoned from these values plus an 99 * interpolated value derived by the clock routines in another 100 * architecture-specific module. The interpolation can use either a 101 * dedicated counter or a processor cycle counter (PCC) implemented in 102 * some architectures. 103 * 104 * Note that all routines must run at priority splclock or higher. 105 */ 106 /* 107 * Phase/frequency-lock loop (PLL/FLL) definitions 108 * 109 * The nanosecond clock discipline uses two variable types, time 110 * variables and frequency variables. Both types are represented as 64- 111 * bit fixed-point quantities with the decimal point between two 32-bit 112 * halves. On a 32-bit machine, each half is represented as a single 113 * word and mathematical operations are done using multiple-precision 114 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is 115 * used. 116 * 117 * A time variable is a signed 64-bit fixed-point number in ns and 118 * fraction. It represents the remaining time offset to be amortized 119 * over succeeding tick interrupts. The maximum time offset is about 120 * 0.5 s and the resolution is about 2.3e-10 ns. 121 * 122 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 123 * 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 1 124 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 125 * |s s s| ns | 126 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 127 * | fraction | 128 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 129 * 130 * A frequency variable is a signed 64-bit fixed-point number in ns/s 131 * and fraction. It represents the ns and fraction to be added to the 132 * kernel time variable at each second. The maximum frequency offset is 133 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s. 134 * 135 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 136 * 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 1 137 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 138 * |s s s s s s s s s s s s s| ns/s | 139 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 140 * | fraction | 141 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 142 */ 143 /* 144 * The following variables establish the state of the PLL/FLL and the 145 * residual time and frequency offset of the local clock. 146 */ 147 #define SHIFT_PLL 4 /* PLL loop gain (shift) */ 148 #define SHIFT_FLL 2 /* FLL loop gain (shift) */ 149 150 static int time_state = TIME_OK; /* clock state */ 151 int time_status = STA_UNSYNC; /* clock status bits */ 152 static long time_tai; /* TAI offset (s) */ 153 static long time_monitor; /* last time offset scaled (ns) */ 154 static long time_constant; /* poll interval (shift) (s) */ 155 static long time_precision = 1; /* clock precision (ns) */ 156 static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */ 157 long time_esterror = MAXPHASE / 1000; /* estimated error (us) */ 158 static long time_reftime; /* uptime at last adjustment (s) */ 159 static l_fp time_offset; /* time offset (ns) */ 160 static l_fp time_freq; /* frequency offset (ns/s) */ 161 static l_fp time_adj; /* tick adjust (ns/s) */ 162 163 static int64_t time_adjtime; /* correction from adjtime(2) (usec) */ 164 165 static struct mtx ntp_lock; 166 MTX_SYSINIT(ntp, &ntp_lock, "ntp", MTX_SPIN); 167 168 #define NTP_LOCK() mtx_lock_spin(&ntp_lock) 169 #define NTP_UNLOCK() mtx_unlock_spin(&ntp_lock) 170 #define NTP_ASSERT_LOCKED() mtx_assert(&ntp_lock, MA_OWNED) 171 172 #ifdef PPS_SYNC 173 /* 174 * The following variables are used when a pulse-per-second (PPS) signal 175 * is available and connected via a modem control lead. They establish 176 * the engineering parameters of the clock discipline loop when 177 * controlled by the PPS signal. 178 */ 179 #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */ 180 #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */ 181 #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */ 182 #define PPS_PAVG 4 /* phase avg interval (s) (shift) */ 183 #define PPS_VALID 120 /* PPS signal watchdog max (s) */ 184 #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */ 185 #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */ 186 187 static struct timespec pps_tf[3]; /* phase median filter */ 188 static l_fp pps_freq; /* scaled frequency offset (ns/s) */ 189 static long pps_fcount; /* frequency accumulator */ 190 static long pps_jitter; /* nominal jitter (ns) */ 191 static long pps_stabil; /* nominal stability (scaled ns/s) */ 192 static long pps_lastsec; /* time at last calibration (s) */ 193 static int pps_valid; /* signal watchdog counter */ 194 static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */ 195 static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */ 196 static int pps_intcnt; /* wander counter */ 197 198 /* 199 * PPS signal quality monitors 200 */ 201 static long pps_calcnt; /* calibration intervals */ 202 static long pps_jitcnt; /* jitter limit exceeded */ 203 static long pps_stbcnt; /* stability limit exceeded */ 204 static long pps_errcnt; /* calibration errors */ 205 #endif /* PPS_SYNC */ 206 /* 207 * End of phase/frequency-lock loop (PLL/FLL) definitions 208 */ 209 210 static void ntp_init(void); 211 static void hardupdate(long offset); 212 static void ntp_gettime1(struct ntptimeval *ntvp); 213 static bool ntp_is_time_error(int tsl); 214 215 static bool 216 ntp_is_time_error(int tsl) 217 { 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 ((tsl & (STA_UNSYNC | STA_CLOCKERR)) || 228 229 /* 230 * PPS signal lost when either time or frequency synchronization 231 * requested 232 */ 233 (tsl & (STA_PPSFREQ | STA_PPSTIME) && 234 !(tsl & STA_PPSSIGNAL)) || 235 236 /* 237 * PPS jitter exceeded when time synchronization requested 238 */ 239 (tsl & STA_PPSTIME && tsl & STA_PPSJITTER) || 240 241 /* 242 * PPS wander exceeded or calibration error when frequency 243 * synchronization requested 244 */ 245 (tsl & STA_PPSFREQ && 246 tsl & (STA_PPSWANDER | STA_PPSERROR))) 247 return (true); 248 249 return (false); 250 } 251 252 static void 253 ntp_gettime1(struct ntptimeval *ntvp) 254 { 255 struct timespec atv; /* nanosecond time */ 256 257 NTP_ASSERT_LOCKED(); 258 259 nanotime(&atv); 260 ntvp->time.tv_sec = atv.tv_sec; 261 ntvp->time.tv_nsec = atv.tv_nsec; 262 ntvp->maxerror = time_maxerror; 263 ntvp->esterror = time_esterror; 264 ntvp->tai = time_tai; 265 ntvp->time_state = time_state; 266 267 if (ntp_is_time_error(time_status)) 268 ntvp->time_state = TIME_ERROR; 269 } 270 271 /* 272 * ntp_gettime() - NTP user application interface 273 * 274 * See the timex.h header file for synopsis and API description. Note that 275 * the TAI offset is returned in the ntvtimeval.tai structure member. 276 */ 277 #ifndef _SYS_SYSPROTO_H_ 278 struct ntp_gettime_args { 279 struct ntptimeval *ntvp; 280 }; 281 #endif 282 /* ARGSUSED */ 283 int 284 sys_ntp_gettime(struct thread *td, struct ntp_gettime_args *uap) 285 { 286 struct ntptimeval ntv; 287 288 memset(&ntv, 0, sizeof(ntv)); 289 290 NTP_LOCK(); 291 ntp_gettime1(&ntv); 292 NTP_UNLOCK(); 293 294 td->td_retval[0] = ntv.time_state; 295 return (copyout(&ntv, uap->ntvp, sizeof(ntv))); 296 } 297 298 static int 299 ntp_sysctl(SYSCTL_HANDLER_ARGS) 300 { 301 struct ntptimeval ntv; /* temporary structure */ 302 303 memset(&ntv, 0, sizeof(ntv)); 304 305 NTP_LOCK(); 306 ntp_gettime1(&ntv); 307 NTP_UNLOCK(); 308 309 return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req)); 310 } 311 312 SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 313 ""); 314 SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE | CTLFLAG_RD | 315 CTLFLAG_MPSAFE, 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", 316 ""); 317 318 #ifdef PPS_SYNC 319 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, 320 &pps_shiftmax, 0, "Max interval duration (sec) (shift)"); 321 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, 322 &pps_shift, 0, "Interval duration (sec) (shift)"); 323 SYSCTL_LONG(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, 324 &time_monitor, 0, "Last time offset scaled (ns)"); 325 326 SYSCTL_S64(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD | CTLFLAG_MPSAFE, 327 &pps_freq, 0, 328 "Scaled frequency offset (ns/sec)"); 329 SYSCTL_S64(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD | CTLFLAG_MPSAFE, 330 &time_freq, 0, 331 "Frequency offset (ns/sec)"); 332 #endif 333 334 /* 335 * ntp_adjtime() - NTP daemon application interface 336 * 337 * See the timex.h header file for synopsis and API description. Note that 338 * the timex.constant structure member has a dual purpose to set the time 339 * constant and to set the TAI offset. 340 */ 341 #ifndef _SYS_SYSPROTO_H_ 342 struct ntp_adjtime_args { 343 struct timex *tp; 344 }; 345 #endif 346 347 int 348 sys_ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap) 349 { 350 struct timex ntv; /* temporary structure */ 351 long freq; /* frequency ns/s) */ 352 int modes; /* mode bits from structure */ 353 int error, retval; 354 355 error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv)); 356 if (error) 357 return (error); 358 359 /* 360 * Update selected clock variables - only the superuser can 361 * change anything. Note that there is no error checking here on 362 * the assumption the superuser should know what it is doing. 363 * Note that either the time constant or TAI offset are loaded 364 * from the ntv.constant member, depending on the mode bits. If 365 * the STA_PLL bit in the status word is cleared, the state and 366 * status words are reset to the initial values at boot. 367 */ 368 modes = ntv.modes; 369 if (modes) 370 error = priv_check(td, PRIV_NTP_ADJTIME); 371 if (error != 0) 372 return (error); 373 NTP_LOCK(); 374 if (modes & MOD_MAXERROR) 375 time_maxerror = ntv.maxerror; 376 if (modes & MOD_ESTERROR) 377 time_esterror = ntv.esterror; 378 if (modes & MOD_STATUS) { 379 if (time_status & STA_PLL && !(ntv.status & STA_PLL)) { 380 time_state = TIME_OK; 381 time_status = STA_UNSYNC; 382 #ifdef PPS_SYNC 383 pps_shift = PPS_FAVG; 384 #endif /* PPS_SYNC */ 385 } 386 time_status &= STA_RONLY; 387 time_status |= ntv.status & ~STA_RONLY; 388 } 389 if (modes & MOD_TIMECONST) { 390 if (ntv.constant < 0) 391 time_constant = 0; 392 else if (ntv.constant > MAXTC) 393 time_constant = MAXTC; 394 else 395 time_constant = ntv.constant; 396 } 397 if (modes & MOD_TAI) { 398 if (ntv.constant > 0) /* XXX zero & negative numbers ? */ 399 time_tai = ntv.constant; 400 } 401 #ifdef PPS_SYNC 402 if (modes & MOD_PPSMAX) { 403 if (ntv.shift < PPS_FAVG) 404 pps_shiftmax = PPS_FAVG; 405 else if (ntv.shift > PPS_FAVGMAX) 406 pps_shiftmax = PPS_FAVGMAX; 407 else 408 pps_shiftmax = ntv.shift; 409 } 410 #endif /* PPS_SYNC */ 411 if (modes & MOD_NANO) 412 time_status |= STA_NANO; 413 if (modes & MOD_MICRO) 414 time_status &= ~STA_NANO; 415 if (modes & MOD_CLKB) 416 time_status |= STA_CLK; 417 if (modes & MOD_CLKA) 418 time_status &= ~STA_CLK; 419 if (modes & MOD_FREQUENCY) { 420 freq = (ntv.freq * 1000LL) >> 16; 421 if (freq > MAXFREQ) 422 L_LINT(time_freq, MAXFREQ); 423 else if (freq < -MAXFREQ) 424 L_LINT(time_freq, -MAXFREQ); 425 else { 426 /* 427 * ntv.freq is [PPM * 2^16] = [us/s * 2^16] 428 * time_freq is [ns/s * 2^32] 429 */ 430 time_freq = ntv.freq * 1000LL * 65536LL; 431 } 432 #ifdef PPS_SYNC 433 pps_freq = time_freq; 434 #endif /* PPS_SYNC */ 435 } 436 if (modes & MOD_OFFSET) { 437 if (time_status & STA_NANO) 438 hardupdate(ntv.offset); 439 else 440 hardupdate(ntv.offset * 1000); 441 } 442 443 /* 444 * Retrieve all clock variables. Note that the TAI offset is 445 * returned only by ntp_gettime(); 446 */ 447 if (time_status & STA_NANO) 448 ntv.offset = L_GINT(time_offset); 449 else 450 ntv.offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */ 451 ntv.freq = L_GINT((time_freq / 1000LL) << 16); 452 ntv.maxerror = time_maxerror; 453 ntv.esterror = time_esterror; 454 ntv.status = time_status; 455 ntv.constant = time_constant; 456 if (time_status & STA_NANO) 457 ntv.precision = time_precision; 458 else 459 ntv.precision = time_precision / 1000; 460 ntv.tolerance = MAXFREQ * SCALE_PPM; 461 #ifdef PPS_SYNC 462 ntv.shift = pps_shift; 463 ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16); 464 if (time_status & STA_NANO) 465 ntv.jitter = pps_jitter; 466 else 467 ntv.jitter = pps_jitter / 1000; 468 ntv.stabil = pps_stabil; 469 ntv.calcnt = pps_calcnt; 470 ntv.errcnt = pps_errcnt; 471 ntv.jitcnt = pps_jitcnt; 472 ntv.stbcnt = pps_stbcnt; 473 #endif /* PPS_SYNC */ 474 retval = ntp_is_time_error(time_status) ? TIME_ERROR : time_state; 475 NTP_UNLOCK(); 476 477 error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv)); 478 if (error == 0) 479 td->td_retval[0] = retval; 480 return (error); 481 } 482 483 /* 484 * second_overflow() - called after ntp_tick_adjust() 485 * 486 * This routine is ordinarily called immediately following the above 487 * routine ntp_tick_adjust(). While these two routines are normally 488 * combined, they are separated here only for the purposes of 489 * simulation. 490 */ 491 void 492 ntp_update_second(int64_t *adjustment, time_t *newsec) 493 { 494 int tickrate; 495 l_fp ftemp; /* 32/64-bit temporary */ 496 497 NTP_LOCK(); 498 499 /* 500 * On rollover of the second both the nanosecond and microsecond 501 * clocks are updated and the state machine cranked as 502 * necessary. The phase adjustment to be used for the next 503 * second is calculated and the maximum error is increased by 504 * the tolerance. 505 */ 506 time_maxerror += MAXFREQ / 1000; 507 508 /* 509 * Leap second processing. If in leap-insert state at 510 * the end of the day, the system clock is set back one 511 * second; if in leap-delete state, the system clock is 512 * set ahead one second. The nano_time() routine or 513 * external clock driver will insure that reported time 514 * is always monotonic. 515 */ 516 switch (time_state) { 517 518 /* 519 * No warning. 520 */ 521 case TIME_OK: 522 if (time_status & STA_INS) 523 time_state = TIME_INS; 524 else if (time_status & STA_DEL) 525 time_state = TIME_DEL; 526 break; 527 528 /* 529 * Insert second 23:59:60 following second 530 * 23:59:59. 531 */ 532 case TIME_INS: 533 if (!(time_status & STA_INS)) 534 time_state = TIME_OK; 535 else if ((*newsec) % 86400 == 0) { 536 (*newsec)--; 537 time_state = TIME_OOP; 538 time_tai++; 539 } 540 break; 541 542 /* 543 * Delete second 23:59:59. 544 */ 545 case TIME_DEL: 546 if (!(time_status & STA_DEL)) 547 time_state = TIME_OK; 548 else if (((*newsec) + 1) % 86400 == 0) { 549 (*newsec)++; 550 time_tai--; 551 time_state = TIME_WAIT; 552 } 553 break; 554 555 /* 556 * Insert second in progress. 557 */ 558 case TIME_OOP: 559 time_state = TIME_WAIT; 560 break; 561 562 /* 563 * Wait for status bits to clear. 564 */ 565 case TIME_WAIT: 566 if (!(time_status & (STA_INS | STA_DEL))) 567 time_state = TIME_OK; 568 } 569 570 /* 571 * Compute the total time adjustment for the next second 572 * in ns. The offset is reduced by a factor depending on 573 * whether the PPS signal is operating. Note that the 574 * value is in effect scaled by the clock frequency, 575 * since the adjustment is added at each tick interrupt. 576 */ 577 ftemp = time_offset; 578 #ifdef PPS_SYNC 579 /* XXX even if PPS signal dies we should finish adjustment ? */ 580 if (time_status & STA_PPSTIME && time_status & 581 STA_PPSSIGNAL) 582 L_RSHIFT(ftemp, pps_shift); 583 else 584 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 585 #else 586 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 587 #endif /* PPS_SYNC */ 588 time_adj = ftemp; 589 L_SUB(time_offset, ftemp); 590 L_ADD(time_adj, time_freq); 591 592 /* 593 * Apply any correction from adjtime(2). If more than one second 594 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM) 595 * until the last second is slewed the final < 500 usecs. 596 */ 597 if (time_adjtime != 0) { 598 if (time_adjtime > 1000000) 599 tickrate = 5000; 600 else if (time_adjtime < -1000000) 601 tickrate = -5000; 602 else if (time_adjtime > 500) 603 tickrate = 500; 604 else if (time_adjtime < -500) 605 tickrate = -500; 606 else 607 tickrate = time_adjtime; 608 time_adjtime -= tickrate; 609 L_LINT(ftemp, tickrate * 1000); 610 L_ADD(time_adj, ftemp); 611 } 612 *adjustment = time_adj; 613 614 #ifdef PPS_SYNC 615 if (pps_valid > 0) 616 pps_valid--; 617 else 618 time_status &= ~STA_PPSSIGNAL; 619 #endif /* PPS_SYNC */ 620 621 NTP_UNLOCK(); 622 } 623 624 /* 625 * ntp_init() - initialize variables and structures 626 * 627 * This routine must be called after the kernel variables hz and tick 628 * are set or changed and before the next tick interrupt. In this 629 * particular implementation, these values are assumed set elsewhere in 630 * the kernel. The design allows the clock frequency and tick interval 631 * to be changed while the system is running. So, this routine should 632 * probably be integrated with the code that does that. 633 */ 634 static void 635 ntp_init(void) 636 { 637 638 /* 639 * The following variables are initialized only at startup. Only 640 * those structures not cleared by the compiler need to be 641 * initialized, and these only in the simulator. In the actual 642 * kernel, any nonzero values here will quickly evaporate. 643 */ 644 L_CLR(time_offset); 645 L_CLR(time_freq); 646 #ifdef PPS_SYNC 647 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0; 648 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0; 649 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0; 650 pps_fcount = 0; 651 L_CLR(pps_freq); 652 #endif /* PPS_SYNC */ 653 } 654 655 SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL); 656 657 /* 658 * hardupdate() - local clock update 659 * 660 * This routine is called by ntp_adjtime() to update the local clock 661 * phase and frequency. The implementation is of an adaptive-parameter, 662 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new 663 * time and frequency offset estimates for each call. If the kernel PPS 664 * discipline code is configured (PPS_SYNC), the PPS signal itself 665 * determines the new time offset, instead of the calling argument. 666 * Presumably, calls to ntp_adjtime() occur only when the caller 667 * believes the local clock is valid within some bound (+-128 ms with 668 * NTP). If the caller's time is far different than the PPS time, an 669 * argument will ensue, and it's not clear who will lose. 670 * 671 * For uncompensated quartz crystal oscillators and nominal update 672 * intervals less than 256 s, operation should be in phase-lock mode, 673 * where the loop is disciplined to phase. For update intervals greater 674 * than 1024 s, operation should be in frequency-lock mode, where the 675 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode 676 * is selected by the STA_MODE status bit. 677 */ 678 static void 679 hardupdate(offset) 680 long offset; /* clock offset (ns) */ 681 { 682 long mtemp; 683 l_fp ftemp; 684 685 NTP_ASSERT_LOCKED(); 686 687 /* 688 * Select how the phase is to be controlled and from which 689 * source. If the PPS signal is present and enabled to 690 * discipline the time, the PPS offset is used; otherwise, the 691 * argument offset is used. 692 */ 693 if (!(time_status & STA_PLL)) 694 return; 695 if (!(time_status & STA_PPSTIME && time_status & 696 STA_PPSSIGNAL)) { 697 if (offset > MAXPHASE) 698 time_monitor = MAXPHASE; 699 else if (offset < -MAXPHASE) 700 time_monitor = -MAXPHASE; 701 else 702 time_monitor = offset; 703 L_LINT(time_offset, time_monitor); 704 } 705 706 /* 707 * Select how the frequency is to be controlled and in which 708 * mode (PLL or FLL). If the PPS signal is present and enabled 709 * to discipline the frequency, the PPS frequency is used; 710 * otherwise, the argument offset is used to compute it. 711 */ 712 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) { 713 time_reftime = time_uptime; 714 return; 715 } 716 if (time_status & STA_FREQHOLD || time_reftime == 0) 717 time_reftime = time_uptime; 718 mtemp = time_uptime - time_reftime; 719 L_LINT(ftemp, time_monitor); 720 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); 721 L_MPY(ftemp, mtemp); 722 L_ADD(time_freq, ftemp); 723 time_status &= ~STA_MODE; 724 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > 725 MAXSEC)) { 726 L_LINT(ftemp, (time_monitor << 4) / mtemp); 727 L_RSHIFT(ftemp, SHIFT_FLL + 4); 728 L_ADD(time_freq, ftemp); 729 time_status |= STA_MODE; 730 } 731 time_reftime = time_uptime; 732 if (L_GINT(time_freq) > MAXFREQ) 733 L_LINT(time_freq, MAXFREQ); 734 else if (L_GINT(time_freq) < -MAXFREQ) 735 L_LINT(time_freq, -MAXFREQ); 736 } 737 738 #ifdef PPS_SYNC 739 /* 740 * hardpps() - discipline CPU clock oscillator to external PPS signal 741 * 742 * This routine is called at each PPS interrupt in order to discipline 743 * the CPU clock oscillator to the PPS signal. There are two independent 744 * first-order feedback loops, one for the phase, the other for the 745 * frequency. The phase loop measures and grooms the PPS phase offset 746 * and leaves it in a handy spot for the seconds overflow routine. The 747 * frequency loop averages successive PPS phase differences and 748 * calculates the PPS frequency offset, which is also processed by the 749 * seconds overflow routine. The code requires the caller to capture the 750 * time and architecture-dependent hardware counter values in 751 * nanoseconds at the on-time PPS signal transition. 752 * 753 * Note that, on some Unix systems this routine runs at an interrupt 754 * priority level higher than the timer interrupt routine hardclock(). 755 * Therefore, the variables used are distinct from the hardclock() 756 * variables, except for the actual time and frequency variables, which 757 * are determined by this routine and updated atomically. 758 * 759 * tsp - time at PPS 760 * nsec - hardware counter at PPS 761 */ 762 void 763 hardpps(struct timespec *tsp, long nsec) 764 { 765 long u_sec, u_nsec, v_nsec; /* temps */ 766 l_fp ftemp; 767 768 NTP_LOCK(); 769 770 /* 771 * The signal is first processed by a range gate and frequency 772 * discriminator. The range gate rejects noise spikes outside 773 * the range +-500 us. The frequency discriminator rejects input 774 * signals with apparent frequency outside the range 1 +-500 775 * PPM. If two hits occur in the same second, we ignore the 776 * later hit; if not and a hit occurs outside the range gate, 777 * keep the later hit for later comparison, but do not process 778 * it. 779 */ 780 time_status |= STA_PPSSIGNAL | STA_PPSJITTER; 781 time_status &= ~(STA_PPSWANDER | STA_PPSERROR); 782 pps_valid = PPS_VALID; 783 u_sec = tsp->tv_sec; 784 u_nsec = tsp->tv_nsec; 785 if (u_nsec >= (NANOSECOND >> 1)) { 786 u_nsec -= NANOSECOND; 787 u_sec++; 788 } 789 v_nsec = u_nsec - pps_tf[0].tv_nsec; 790 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - MAXFREQ) 791 goto out; 792 pps_tf[2] = pps_tf[1]; 793 pps_tf[1] = pps_tf[0]; 794 pps_tf[0].tv_sec = u_sec; 795 pps_tf[0].tv_nsec = u_nsec; 796 797 /* 798 * Compute the difference between the current and previous 799 * counter values. If the difference exceeds 0.5 s, assume it 800 * has wrapped around, so correct 1.0 s. If the result exceeds 801 * the tick interval, the sample point has crossed a tick 802 * boundary during the last second, so correct the tick. Very 803 * intricate. 804 */ 805 u_nsec = nsec; 806 if (u_nsec > (NANOSECOND >> 1)) 807 u_nsec -= NANOSECOND; 808 else if (u_nsec < -(NANOSECOND >> 1)) 809 u_nsec += NANOSECOND; 810 pps_fcount += u_nsec; 811 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) 812 goto out; 813 time_status &= ~STA_PPSJITTER; 814 815 /* 816 * A three-stage median filter is used to help denoise the PPS 817 * time. The median sample becomes the time offset estimate; the 818 * difference between the other two samples becomes the time 819 * dispersion (jitter) estimate. 820 */ 821 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { 822 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { 823 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ 824 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; 825 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { 826 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ 827 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; 828 } else { 829 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ 830 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; 831 } 832 } else { 833 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { 834 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ 835 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; 836 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { 837 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ 838 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; 839 } else { 840 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ 841 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; 842 } 843 } 844 845 /* 846 * Nominal jitter is due to PPS signal noise and interrupt 847 * latency. If it exceeds the popcorn threshold, the sample is 848 * discarded. otherwise, if so enabled, the time offset is 849 * updated. We can tolerate a modest loss of data here without 850 * much degrading time accuracy. 851 * 852 * The measurements being checked here were made with the system 853 * timecounter, so the popcorn threshold is not allowed to fall below 854 * the number of nanoseconds in two ticks of the timecounter. For a 855 * timecounter running faster than 1 GHz the lower bound is 2ns, just 856 * to avoid a nonsensical threshold of zero. 857 */ 858 if (u_nsec > lmax(pps_jitter << PPS_POPCORN, 859 2 * (NANOSECOND / (long)qmin(NANOSECOND, tc_getfrequency())))) { 860 time_status |= STA_PPSJITTER; 861 pps_jitcnt++; 862 } else if (time_status & STA_PPSTIME) { 863 time_monitor = -v_nsec; 864 L_LINT(time_offset, time_monitor); 865 } 866 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; 867 u_sec = pps_tf[0].tv_sec - pps_lastsec; 868 if (u_sec < (1 << pps_shift)) 869 goto out; 870 871 /* 872 * At the end of the calibration interval the difference between 873 * the first and last counter values becomes the scaled 874 * frequency. It will later be divided by the length of the 875 * interval to determine the frequency update. If the frequency 876 * exceeds a sanity threshold, or if the actual calibration 877 * interval is not equal to the expected length, the data are 878 * discarded. We can tolerate a modest loss of data here without 879 * much degrading frequency accuracy. 880 */ 881 pps_calcnt++; 882 v_nsec = -pps_fcount; 883 pps_lastsec = pps_tf[0].tv_sec; 884 pps_fcount = 0; 885 u_nsec = MAXFREQ << pps_shift; 886 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << pps_shift)) { 887 time_status |= STA_PPSERROR; 888 pps_errcnt++; 889 goto out; 890 } 891 892 /* 893 * Here the raw frequency offset and wander (stability) is 894 * calculated. If the wander is less than the wander threshold 895 * for four consecutive averaging intervals, the interval is 896 * doubled; if it is greater than the threshold for four 897 * consecutive intervals, the interval is halved. The scaled 898 * frequency offset is converted to frequency offset. The 899 * stability metric is calculated as the average of recent 900 * frequency changes, but is used only for performance 901 * monitoring. 902 */ 903 L_LINT(ftemp, v_nsec); 904 L_RSHIFT(ftemp, pps_shift); 905 L_SUB(ftemp, pps_freq); 906 u_nsec = L_GINT(ftemp); 907 if (u_nsec > PPS_MAXWANDER) { 908 L_LINT(ftemp, PPS_MAXWANDER); 909 pps_intcnt--; 910 time_status |= STA_PPSWANDER; 911 pps_stbcnt++; 912 } else if (u_nsec < -PPS_MAXWANDER) { 913 L_LINT(ftemp, -PPS_MAXWANDER); 914 pps_intcnt--; 915 time_status |= STA_PPSWANDER; 916 pps_stbcnt++; 917 } else { 918 pps_intcnt++; 919 } 920 if (pps_intcnt >= 4) { 921 pps_intcnt = 4; 922 if (pps_shift < pps_shiftmax) { 923 pps_shift++; 924 pps_intcnt = 0; 925 } 926 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { 927 pps_intcnt = -4; 928 if (pps_shift > PPS_FAVG) { 929 pps_shift--; 930 pps_intcnt = 0; 931 } 932 } 933 if (u_nsec < 0) 934 u_nsec = -u_nsec; 935 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; 936 937 /* 938 * The PPS frequency is recalculated and clamped to the maximum 939 * MAXFREQ. If enabled, the system clock frequency is updated as 940 * well. 941 */ 942 L_ADD(pps_freq, ftemp); 943 u_nsec = L_GINT(pps_freq); 944 if (u_nsec > MAXFREQ) 945 L_LINT(pps_freq, MAXFREQ); 946 else if (u_nsec < -MAXFREQ) 947 L_LINT(pps_freq, -MAXFREQ); 948 if (time_status & STA_PPSFREQ) 949 time_freq = pps_freq; 950 951 out: 952 NTP_UNLOCK(); 953 } 954 #endif /* PPS_SYNC */ 955 956 #ifndef _SYS_SYSPROTO_H_ 957 struct adjtime_args { 958 struct timeval *delta; 959 struct timeval *olddelta; 960 }; 961 #endif 962 /* ARGSUSED */ 963 int 964 sys_adjtime(struct thread *td, struct adjtime_args *uap) 965 { 966 struct timeval delta, olddelta, *deltap; 967 int error; 968 969 if (uap->delta) { 970 error = copyin(uap->delta, &delta, sizeof(delta)); 971 if (error) 972 return (error); 973 deltap = δ 974 } else 975 deltap = NULL; 976 error = kern_adjtime(td, deltap, &olddelta); 977 if (uap->olddelta && error == 0) 978 error = copyout(&olddelta, uap->olddelta, sizeof(olddelta)); 979 return (error); 980 } 981 982 int 983 kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta) 984 { 985 struct timeval atv; 986 int64_t ltr, ltw; 987 int error; 988 989 if (delta != NULL) { 990 error = priv_check(td, PRIV_ADJTIME); 991 if (error != 0) 992 return (error); 993 ltw = (int64_t)delta->tv_sec * 1000000 + delta->tv_usec; 994 } 995 NTP_LOCK(); 996 ltr = time_adjtime; 997 if (delta != NULL) 998 time_adjtime = ltw; 999 NTP_UNLOCK(); 1000 if (olddelta != NULL) { 1001 atv.tv_sec = ltr / 1000000; 1002 atv.tv_usec = ltr % 1000000; 1003 if (atv.tv_usec < 0) { 1004 atv.tv_usec += 1000000; 1005 atv.tv_sec--; 1006 } 1007 *olddelta = atv; 1008 } 1009 return (0); 1010 } 1011 1012 static struct callout resettodr_callout; 1013 static int resettodr_period = 1800; 1014 1015 static void 1016 periodic_resettodr(void *arg __unused) 1017 { 1018 1019 /* 1020 * Read of time_status is lock-less, which is fine since 1021 * ntp_is_time_error() operates on the consistent read value. 1022 */ 1023 if (!ntp_is_time_error(time_status)) 1024 resettodr(); 1025 if (resettodr_period > 0) 1026 callout_schedule(&resettodr_callout, resettodr_period * hz); 1027 } 1028 1029 static void 1030 shutdown_resettodr(void *arg __unused, int howto __unused) 1031 { 1032 1033 callout_drain(&resettodr_callout); 1034 /* Another unlocked read of time_status */ 1035 if (resettodr_period > 0 && !ntp_is_time_error(time_status)) 1036 resettodr(); 1037 } 1038 1039 static int 1040 sysctl_resettodr_period(SYSCTL_HANDLER_ARGS) 1041 { 1042 int error; 1043 1044 error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req); 1045 if (error || !req->newptr) 1046 return (error); 1047 if (cold) 1048 goto done; 1049 if (resettodr_period == 0) 1050 callout_stop(&resettodr_callout); 1051 else 1052 callout_reset(&resettodr_callout, resettodr_period * hz, 1053 periodic_resettodr, NULL); 1054 done: 1055 return (0); 1056 } 1057 1058 SYSCTL_PROC(_machdep, OID_AUTO, rtc_save_period, CTLTYPE_INT | CTLFLAG_RWTUN | 1059 CTLFLAG_MPSAFE, &resettodr_period, 1800, sysctl_resettodr_period, "I", 1060 "Save system time to RTC with this period (in seconds)"); 1061 1062 static void 1063 start_periodic_resettodr(void *arg __unused) 1064 { 1065 1066 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_resettodr, NULL, 1067 SHUTDOWN_PRI_FIRST); 1068 callout_init(&resettodr_callout, 1); 1069 if (resettodr_period == 0) 1070 return; 1071 callout_reset(&resettodr_callout, resettodr_period * hz, 1072 periodic_resettodr, NULL); 1073 } 1074 1075 SYSINIT(periodic_resettodr, SI_SUB_LAST, SI_ORDER_MIDDLE, 1076 start_periodic_resettodr, NULL); 1077