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 ntpadj_lock; 166 MTX_SYSINIT(ntpadj, &ntpadj_lock, "ntpadj", 167 #ifdef PPS_SYNC 168 MTX_SPIN 169 #else 170 MTX_DEF 171 #endif 172 ); 173 174 /* 175 * When PPS_SYNC is defined, hardpps() function is provided which can 176 * be legitimately called from interrupt filters. Due to this, use 177 * spinlock for ntptime state protection, otherwise sleepable mutex is 178 * adequate. 179 */ 180 #ifdef PPS_SYNC 181 #define NTPADJ_LOCK() mtx_lock_spin(&ntpadj_lock) 182 #define NTPADJ_UNLOCK() mtx_unlock_spin(&ntpadj_lock) 183 #else 184 #define NTPADJ_LOCK() mtx_lock(&ntpadj_lock) 185 #define NTPADJ_UNLOCK() mtx_unlock(&ntpadj_lock) 186 #endif 187 #define NTPADJ_ASSERT_LOCKED() mtx_assert(&ntpadj_lock, MA_OWNED) 188 189 #ifdef PPS_SYNC 190 /* 191 * The following variables are used when a pulse-per-second (PPS) signal 192 * is available and connected via a modem control lead. They establish 193 * the engineering parameters of the clock discipline loop when 194 * controlled by the PPS signal. 195 */ 196 #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */ 197 #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */ 198 #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */ 199 #define PPS_PAVG 4 /* phase avg interval (s) (shift) */ 200 #define PPS_VALID 120 /* PPS signal watchdog max (s) */ 201 #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */ 202 #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */ 203 204 static struct timespec pps_tf[3]; /* phase median filter */ 205 static l_fp pps_freq; /* scaled frequency offset (ns/s) */ 206 static long pps_fcount; /* frequency accumulator */ 207 static long pps_jitter; /* nominal jitter (ns) */ 208 static long pps_stabil; /* nominal stability (scaled ns/s) */ 209 static long pps_lastsec; /* time at last calibration (s) */ 210 static int pps_valid; /* signal watchdog counter */ 211 static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */ 212 static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */ 213 static int pps_intcnt; /* wander counter */ 214 215 /* 216 * PPS signal quality monitors 217 */ 218 static long pps_calcnt; /* calibration intervals */ 219 static long pps_jitcnt; /* jitter limit exceeded */ 220 static long pps_stbcnt; /* stability limit exceeded */ 221 static long pps_errcnt; /* calibration errors */ 222 #endif /* PPS_SYNC */ 223 /* 224 * End of phase/frequency-lock loop (PLL/FLL) definitions 225 */ 226 227 static void ntp_init(void); 228 static void hardupdate(long offset); 229 static void ntp_gettime1(struct ntptimeval *ntvp); 230 static bool ntp_is_time_error(int tsl); 231 232 static bool 233 ntp_is_time_error(int tsl) 234 { 235 236 /* 237 * Status word error decode. If any of these conditions occur, 238 * an error is returned, instead of the status word. Most 239 * applications will care only about the fact the system clock 240 * may not be trusted, not about the details. 241 * 242 * Hardware or software error 243 */ 244 if ((tsl & (STA_UNSYNC | STA_CLOCKERR)) || 245 246 /* 247 * PPS signal lost when either time or frequency synchronization 248 * requested 249 */ 250 (tsl & (STA_PPSFREQ | STA_PPSTIME) && 251 !(tsl & STA_PPSSIGNAL)) || 252 253 /* 254 * PPS jitter exceeded when time synchronization requested 255 */ 256 (tsl & STA_PPSTIME && tsl & STA_PPSJITTER) || 257 258 /* 259 * PPS wander exceeded or calibration error when frequency 260 * synchronization requested 261 */ 262 (tsl & STA_PPSFREQ && 263 tsl & (STA_PPSWANDER | STA_PPSERROR))) 264 return (true); 265 266 return (false); 267 } 268 269 static void 270 ntp_gettime1(struct ntptimeval *ntvp) 271 { 272 struct timespec atv; /* nanosecond time */ 273 274 NTPADJ_ASSERT_LOCKED(); 275 276 nanotime(&atv); 277 ntvp->time.tv_sec = atv.tv_sec; 278 ntvp->time.tv_nsec = atv.tv_nsec; 279 ntvp->maxerror = time_maxerror; 280 ntvp->esterror = time_esterror; 281 ntvp->tai = time_tai; 282 ntvp->time_state = time_state; 283 284 if (ntp_is_time_error(time_status)) 285 ntvp->time_state = TIME_ERROR; 286 } 287 288 /* 289 * ntp_gettime() - NTP user application interface 290 * 291 * See the timex.h header file for synopsis and API description. Note that 292 * the TAI offset is returned in the ntvtimeval.tai structure member. 293 */ 294 #ifndef _SYS_SYSPROTO_H_ 295 struct ntp_gettime_args { 296 struct ntptimeval *ntvp; 297 }; 298 #endif 299 /* ARGSUSED */ 300 int 301 sys_ntp_gettime(struct thread *td, struct ntp_gettime_args *uap) 302 { 303 struct ntptimeval ntv; 304 305 NTPADJ_LOCK(); 306 ntp_gettime1(&ntv); 307 NTPADJ_UNLOCK(); 308 309 td->td_retval[0] = ntv.time_state; 310 return (copyout(&ntv, uap->ntvp, sizeof(ntv))); 311 } 312 313 static int 314 ntp_sysctl(SYSCTL_HANDLER_ARGS) 315 { 316 struct ntptimeval ntv; /* temporary structure */ 317 318 NTPADJ_LOCK(); 319 ntp_gettime1(&ntv); 320 NTPADJ_UNLOCK(); 321 322 return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req)); 323 } 324 325 SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, ""); 326 SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE | CTLFLAG_RD | 327 CTLFLAG_MPSAFE, 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", 328 ""); 329 330 #ifdef PPS_SYNC 331 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, 332 &pps_shiftmax, 0, "Max interval duration (sec) (shift)"); 333 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, 334 &pps_shift, 0, "Interval duration (sec) (shift)"); 335 SYSCTL_LONG(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, 336 &time_monitor, 0, "Last time offset scaled (ns)"); 337 338 SYSCTL_S64(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD | CTLFLAG_MPSAFE, 339 &pps_freq, 0, 340 "Scaled frequency offset (ns/sec)"); 341 SYSCTL_S64(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD | CTLFLAG_MPSAFE, 342 &time_freq, 0, 343 "Frequency offset (ns/sec)"); 344 #endif 345 346 /* 347 * ntp_adjtime() - NTP daemon application interface 348 * 349 * See the timex.h header file for synopsis and API description. Note that 350 * the timex.constant structure member has a dual purpose to set the time 351 * constant and to set the TAI offset. 352 */ 353 #ifndef _SYS_SYSPROTO_H_ 354 struct ntp_adjtime_args { 355 struct timex *tp; 356 }; 357 #endif 358 359 int 360 sys_ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap) 361 { 362 struct timex ntv; /* temporary structure */ 363 long freq; /* frequency ns/s) */ 364 int modes; /* mode bits from structure */ 365 int error, retval; 366 367 error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv)); 368 if (error) 369 return (error); 370 371 /* 372 * Update selected clock variables - only the superuser can 373 * change anything. Note that there is no error checking here on 374 * the assumption the superuser should know what it is doing. 375 * Note that either the time constant or TAI offset are loaded 376 * from the ntv.constant member, depending on the mode bits. If 377 * the STA_PLL bit in the status word is cleared, the state and 378 * status words are reset to the initial values at boot. 379 */ 380 modes = ntv.modes; 381 if (modes) 382 error = priv_check(td, PRIV_NTP_ADJTIME); 383 if (error != 0) 384 return (error); 385 NTPADJ_LOCK(); 386 if (modes & MOD_MAXERROR) 387 time_maxerror = ntv.maxerror; 388 if (modes & MOD_ESTERROR) 389 time_esterror = ntv.esterror; 390 if (modes & MOD_STATUS) { 391 if (time_status & STA_PLL && !(ntv.status & STA_PLL)) { 392 time_state = TIME_OK; 393 time_status = STA_UNSYNC; 394 #ifdef PPS_SYNC 395 pps_shift = PPS_FAVG; 396 #endif /* PPS_SYNC */ 397 } 398 time_status &= STA_RONLY; 399 time_status |= ntv.status & ~STA_RONLY; 400 } 401 if (modes & MOD_TIMECONST) { 402 if (ntv.constant < 0) 403 time_constant = 0; 404 else if (ntv.constant > MAXTC) 405 time_constant = MAXTC; 406 else 407 time_constant = ntv.constant; 408 } 409 if (modes & MOD_TAI) { 410 if (ntv.constant > 0) /* XXX zero & negative numbers ? */ 411 time_tai = ntv.constant; 412 } 413 #ifdef PPS_SYNC 414 if (modes & MOD_PPSMAX) { 415 if (ntv.shift < PPS_FAVG) 416 pps_shiftmax = PPS_FAVG; 417 else if (ntv.shift > PPS_FAVGMAX) 418 pps_shiftmax = PPS_FAVGMAX; 419 else 420 pps_shiftmax = ntv.shift; 421 } 422 #endif /* PPS_SYNC */ 423 if (modes & MOD_NANO) 424 time_status |= STA_NANO; 425 if (modes & MOD_MICRO) 426 time_status &= ~STA_NANO; 427 if (modes & MOD_CLKB) 428 time_status |= STA_CLK; 429 if (modes & MOD_CLKA) 430 time_status &= ~STA_CLK; 431 if (modes & MOD_FREQUENCY) { 432 freq = (ntv.freq * 1000LL) >> 16; 433 if (freq > MAXFREQ) 434 L_LINT(time_freq, MAXFREQ); 435 else if (freq < -MAXFREQ) 436 L_LINT(time_freq, -MAXFREQ); 437 else { 438 /* 439 * ntv.freq is [PPM * 2^16] = [us/s * 2^16] 440 * time_freq is [ns/s * 2^32] 441 */ 442 time_freq = ntv.freq * 1000LL * 65536LL; 443 } 444 #ifdef PPS_SYNC 445 pps_freq = time_freq; 446 #endif /* PPS_SYNC */ 447 } 448 if (modes & MOD_OFFSET) { 449 if (time_status & STA_NANO) 450 hardupdate(ntv.offset); 451 else 452 hardupdate(ntv.offset * 1000); 453 } 454 455 /* 456 * Retrieve all clock variables. Note that the TAI offset is 457 * returned only by ntp_gettime(); 458 */ 459 if (time_status & STA_NANO) 460 ntv.offset = L_GINT(time_offset); 461 else 462 ntv.offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */ 463 ntv.freq = L_GINT((time_freq / 1000LL) << 16); 464 ntv.maxerror = time_maxerror; 465 ntv.esterror = time_esterror; 466 ntv.status = time_status; 467 ntv.constant = time_constant; 468 if (time_status & STA_NANO) 469 ntv.precision = time_precision; 470 else 471 ntv.precision = time_precision / 1000; 472 ntv.tolerance = MAXFREQ * SCALE_PPM; 473 #ifdef PPS_SYNC 474 ntv.shift = pps_shift; 475 ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16); 476 if (time_status & STA_NANO) 477 ntv.jitter = pps_jitter; 478 else 479 ntv.jitter = pps_jitter / 1000; 480 ntv.stabil = pps_stabil; 481 ntv.calcnt = pps_calcnt; 482 ntv.errcnt = pps_errcnt; 483 ntv.jitcnt = pps_jitcnt; 484 ntv.stbcnt = pps_stbcnt; 485 #endif /* PPS_SYNC */ 486 retval = ntp_is_time_error(time_status) ? TIME_ERROR : time_state; 487 NTPADJ_UNLOCK(); 488 489 error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv)); 490 if (error == 0) 491 td->td_retval[0] = retval; 492 return (error); 493 } 494 495 /* 496 * second_overflow() - called after ntp_tick_adjust() 497 * 498 * This routine is ordinarily called immediately following the above 499 * routine ntp_tick_adjust(). While these two routines are normally 500 * combined, they are separated here only for the purposes of 501 * simulation. 502 */ 503 void 504 ntp_update_second(int64_t *adjustment, time_t *newsec) 505 { 506 int tickrate; 507 l_fp ftemp; /* 32/64-bit temporary */ 508 509 /* 510 * On rollover of the second both the nanosecond and microsecond 511 * clocks are updated and the state machine cranked as 512 * necessary. The phase adjustment to be used for the next 513 * second is calculated and the maximum error is increased by 514 * the tolerance. 515 */ 516 time_maxerror += MAXFREQ / 1000; 517 518 /* 519 * Leap second processing. If in leap-insert state at 520 * the end of the day, the system clock is set back one 521 * second; if in leap-delete state, the system clock is 522 * set ahead one second. The nano_time() routine or 523 * external clock driver will insure that reported time 524 * is always monotonic. 525 */ 526 switch (time_state) { 527 528 /* 529 * No warning. 530 */ 531 case TIME_OK: 532 if (time_status & STA_INS) 533 time_state = TIME_INS; 534 else if (time_status & STA_DEL) 535 time_state = TIME_DEL; 536 break; 537 538 /* 539 * Insert second 23:59:60 following second 540 * 23:59:59. 541 */ 542 case TIME_INS: 543 if (!(time_status & STA_INS)) 544 time_state = TIME_OK; 545 else if ((*newsec) % 86400 == 0) { 546 (*newsec)--; 547 time_state = TIME_OOP; 548 time_tai++; 549 } 550 break; 551 552 /* 553 * Delete second 23:59:59. 554 */ 555 case TIME_DEL: 556 if (!(time_status & STA_DEL)) 557 time_state = TIME_OK; 558 else if (((*newsec) + 1) % 86400 == 0) { 559 (*newsec)++; 560 time_tai--; 561 time_state = TIME_WAIT; 562 } 563 break; 564 565 /* 566 * Insert second in progress. 567 */ 568 case TIME_OOP: 569 time_state = TIME_WAIT; 570 break; 571 572 /* 573 * Wait for status bits to clear. 574 */ 575 case TIME_WAIT: 576 if (!(time_status & (STA_INS | STA_DEL))) 577 time_state = TIME_OK; 578 } 579 580 /* 581 * Compute the total time adjustment for the next second 582 * in ns. The offset is reduced by a factor depending on 583 * whether the PPS signal is operating. Note that the 584 * value is in effect scaled by the clock frequency, 585 * since the adjustment is added at each tick interrupt. 586 */ 587 ftemp = time_offset; 588 #ifdef PPS_SYNC 589 /* XXX even if PPS signal dies we should finish adjustment ? */ 590 if (time_status & STA_PPSTIME && time_status & 591 STA_PPSSIGNAL) 592 L_RSHIFT(ftemp, pps_shift); 593 else 594 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 595 #else 596 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 597 #endif /* PPS_SYNC */ 598 time_adj = ftemp; 599 L_SUB(time_offset, ftemp); 600 L_ADD(time_adj, time_freq); 601 602 /* 603 * Apply any correction from adjtime(2). If more than one second 604 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM) 605 * until the last second is slewed the final < 500 usecs. 606 */ 607 if (time_adjtime != 0) { 608 if (time_adjtime > 1000000) 609 tickrate = 5000; 610 else if (time_adjtime < -1000000) 611 tickrate = -5000; 612 else if (time_adjtime > 500) 613 tickrate = 500; 614 else if (time_adjtime < -500) 615 tickrate = -500; 616 else 617 tickrate = time_adjtime; 618 time_adjtime -= tickrate; 619 L_LINT(ftemp, tickrate * 1000); 620 L_ADD(time_adj, ftemp); 621 } 622 *adjustment = time_adj; 623 624 #ifdef PPS_SYNC 625 if (pps_valid > 0) 626 pps_valid--; 627 else 628 time_status &= ~STA_PPSSIGNAL; 629 #endif /* PPS_SYNC */ 630 } 631 632 /* 633 * ntp_init() - initialize variables and structures 634 * 635 * This routine must be called after the kernel variables hz and tick 636 * are set or changed and before the next tick interrupt. In this 637 * particular implementation, these values are assumed set elsewhere in 638 * the kernel. The design allows the clock frequency and tick interval 639 * to be changed while the system is running. So, this routine should 640 * probably be integrated with the code that does that. 641 */ 642 static void 643 ntp_init(void) 644 { 645 646 /* 647 * The following variables are initialized only at startup. Only 648 * those structures not cleared by the compiler need to be 649 * initialized, and these only in the simulator. In the actual 650 * kernel, any nonzero values here will quickly evaporate. 651 */ 652 L_CLR(time_offset); 653 L_CLR(time_freq); 654 #ifdef PPS_SYNC 655 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0; 656 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0; 657 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0; 658 pps_fcount = 0; 659 L_CLR(pps_freq); 660 #endif /* PPS_SYNC */ 661 } 662 663 SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL); 664 665 /* 666 * hardupdate() - local clock update 667 * 668 * This routine is called by ntp_adjtime() to update the local clock 669 * phase and frequency. The implementation is of an adaptive-parameter, 670 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new 671 * time and frequency offset estimates for each call. If the kernel PPS 672 * discipline code is configured (PPS_SYNC), the PPS signal itself 673 * determines the new time offset, instead of the calling argument. 674 * Presumably, calls to ntp_adjtime() occur only when the caller 675 * believes the local clock is valid within some bound (+-128 ms with 676 * NTP). If the caller's time is far different than the PPS time, an 677 * argument will ensue, and it's not clear who will lose. 678 * 679 * For uncompensated quartz crystal oscillators and nominal update 680 * intervals less than 256 s, operation should be in phase-lock mode, 681 * where the loop is disciplined to phase. For update intervals greater 682 * than 1024 s, operation should be in frequency-lock mode, where the 683 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode 684 * is selected by the STA_MODE status bit. 685 */ 686 static void 687 hardupdate(offset) 688 long offset; /* clock offset (ns) */ 689 { 690 long mtemp; 691 l_fp ftemp; 692 693 NTPADJ_ASSERT_LOCKED(); 694 695 /* 696 * Select how the phase is to be controlled and from which 697 * source. If the PPS signal is present and enabled to 698 * discipline the time, the PPS offset is used; otherwise, the 699 * argument offset is used. 700 */ 701 if (!(time_status & STA_PLL)) 702 return; 703 if (!(time_status & STA_PPSTIME && time_status & 704 STA_PPSSIGNAL)) { 705 if (offset > MAXPHASE) 706 time_monitor = MAXPHASE; 707 else if (offset < -MAXPHASE) 708 time_monitor = -MAXPHASE; 709 else 710 time_monitor = offset; 711 L_LINT(time_offset, time_monitor); 712 } 713 714 /* 715 * Select how the frequency is to be controlled and in which 716 * mode (PLL or FLL). If the PPS signal is present and enabled 717 * to discipline the frequency, the PPS frequency is used; 718 * otherwise, the argument offset is used to compute it. 719 */ 720 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) { 721 time_reftime = time_uptime; 722 return; 723 } 724 if (time_status & STA_FREQHOLD || time_reftime == 0) 725 time_reftime = time_uptime; 726 mtemp = time_uptime - time_reftime; 727 L_LINT(ftemp, time_monitor); 728 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); 729 L_MPY(ftemp, mtemp); 730 L_ADD(time_freq, ftemp); 731 time_status &= ~STA_MODE; 732 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > 733 MAXSEC)) { 734 L_LINT(ftemp, (time_monitor << 4) / mtemp); 735 L_RSHIFT(ftemp, SHIFT_FLL + 4); 736 L_ADD(time_freq, ftemp); 737 time_status |= STA_MODE; 738 } 739 time_reftime = time_uptime; 740 if (L_GINT(time_freq) > MAXFREQ) 741 L_LINT(time_freq, MAXFREQ); 742 else if (L_GINT(time_freq) < -MAXFREQ) 743 L_LINT(time_freq, -MAXFREQ); 744 } 745 746 #ifdef PPS_SYNC 747 /* 748 * hardpps() - discipline CPU clock oscillator to external PPS signal 749 * 750 * This routine is called at each PPS interrupt in order to discipline 751 * the CPU clock oscillator to the PPS signal. There are two independent 752 * first-order feedback loops, one for the phase, the other for the 753 * frequency. The phase loop measures and grooms the PPS phase offset 754 * and leaves it in a handy spot for the seconds overflow routine. The 755 * frequency loop averages successive PPS phase differences and 756 * calculates the PPS frequency offset, which is also processed by the 757 * seconds overflow routine. The code requires the caller to capture the 758 * time and architecture-dependent hardware counter values in 759 * nanoseconds at the on-time PPS signal transition. 760 * 761 * Note that, on some Unix systems this routine runs at an interrupt 762 * priority level higher than the timer interrupt routine hardclock(). 763 * Therefore, the variables used are distinct from the hardclock() 764 * variables, except for the actual time and frequency variables, which 765 * are determined by this routine and updated atomically. 766 */ 767 void 768 hardpps(tsp, nsec) 769 struct timespec *tsp; /* time at PPS */ 770 long nsec; /* hardware counter at PPS */ 771 { 772 long u_sec, u_nsec, v_nsec; /* temps */ 773 l_fp ftemp; 774 775 NTPADJ_LOCK(); 776 777 /* 778 * The signal is first processed by a range gate and frequency 779 * discriminator. The range gate rejects noise spikes outside 780 * the range +-500 us. The frequency discriminator rejects input 781 * signals with apparent frequency outside the range 1 +-500 782 * PPM. If two hits occur in the same second, we ignore the 783 * later hit; if not and a hit occurs outside the range gate, 784 * keep the later hit for later comparison, but do not process 785 * it. 786 */ 787 time_status |= STA_PPSSIGNAL | STA_PPSJITTER; 788 time_status &= ~(STA_PPSWANDER | STA_PPSERROR); 789 pps_valid = PPS_VALID; 790 u_sec = tsp->tv_sec; 791 u_nsec = tsp->tv_nsec; 792 if (u_nsec >= (NANOSECOND >> 1)) { 793 u_nsec -= NANOSECOND; 794 u_sec++; 795 } 796 v_nsec = u_nsec - pps_tf[0].tv_nsec; 797 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - MAXFREQ) 798 goto out; 799 pps_tf[2] = pps_tf[1]; 800 pps_tf[1] = pps_tf[0]; 801 pps_tf[0].tv_sec = u_sec; 802 pps_tf[0].tv_nsec = u_nsec; 803 804 /* 805 * Compute the difference between the current and previous 806 * counter values. If the difference exceeds 0.5 s, assume it 807 * has wrapped around, so correct 1.0 s. If the result exceeds 808 * the tick interval, the sample point has crossed a tick 809 * boundary during the last second, so correct the tick. Very 810 * intricate. 811 */ 812 u_nsec = nsec; 813 if (u_nsec > (NANOSECOND >> 1)) 814 u_nsec -= NANOSECOND; 815 else if (u_nsec < -(NANOSECOND >> 1)) 816 u_nsec += NANOSECOND; 817 pps_fcount += u_nsec; 818 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) 819 goto out; 820 time_status &= ~STA_PPSJITTER; 821 822 /* 823 * A three-stage median filter is used to help denoise the PPS 824 * time. The median sample becomes the time offset estimate; the 825 * difference between the other two samples becomes the time 826 * dispersion (jitter) estimate. 827 */ 828 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { 829 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { 830 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ 831 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; 832 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { 833 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ 834 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; 835 } else { 836 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ 837 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; 838 } 839 } else { 840 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { 841 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ 842 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; 843 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { 844 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ 845 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; 846 } else { 847 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ 848 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; 849 } 850 } 851 852 /* 853 * Nominal jitter is due to PPS signal noise and interrupt 854 * latency. If it exceeds the popcorn threshold, the sample is 855 * discarded. otherwise, if so enabled, the time offset is 856 * updated. We can tolerate a modest loss of data here without 857 * much degrading time accuracy. 858 * 859 * The measurements being checked here were made with the system 860 * timecounter, so the popcorn threshold is not allowed to fall below 861 * the number of nanoseconds in two ticks of the timecounter. For a 862 * timecounter running faster than 1 GHz the lower bound is 2ns, just 863 * to avoid a nonsensical threshold of zero. 864 */ 865 if (u_nsec > lmax(pps_jitter << PPS_POPCORN, 866 2 * (NANOSECOND / (long)qmin(NANOSECOND, tc_getfrequency())))) { 867 time_status |= STA_PPSJITTER; 868 pps_jitcnt++; 869 } else if (time_status & STA_PPSTIME) { 870 time_monitor = -v_nsec; 871 L_LINT(time_offset, time_monitor); 872 } 873 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; 874 u_sec = pps_tf[0].tv_sec - pps_lastsec; 875 if (u_sec < (1 << pps_shift)) 876 goto out; 877 878 /* 879 * At the end of the calibration interval the difference between 880 * the first and last counter values becomes the scaled 881 * frequency. It will later be divided by the length of the 882 * interval to determine the frequency update. If the frequency 883 * exceeds a sanity threshold, or if the actual calibration 884 * interval is not equal to the expected length, the data are 885 * discarded. We can tolerate a modest loss of data here without 886 * much degrading frequency accuracy. 887 */ 888 pps_calcnt++; 889 v_nsec = -pps_fcount; 890 pps_lastsec = pps_tf[0].tv_sec; 891 pps_fcount = 0; 892 u_nsec = MAXFREQ << pps_shift; 893 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << pps_shift)) { 894 time_status |= STA_PPSERROR; 895 pps_errcnt++; 896 goto out; 897 } 898 899 /* 900 * Here the raw frequency offset and wander (stability) is 901 * calculated. If the wander is less than the wander threshold 902 * for four consecutive averaging intervals, the interval is 903 * doubled; if it is greater than the threshold for four 904 * consecutive intervals, the interval is halved. The scaled 905 * frequency offset is converted to frequency offset. The 906 * stability metric is calculated as the average of recent 907 * frequency changes, but is used only for performance 908 * monitoring. 909 */ 910 L_LINT(ftemp, v_nsec); 911 L_RSHIFT(ftemp, pps_shift); 912 L_SUB(ftemp, pps_freq); 913 u_nsec = L_GINT(ftemp); 914 if (u_nsec > PPS_MAXWANDER) { 915 L_LINT(ftemp, PPS_MAXWANDER); 916 pps_intcnt--; 917 time_status |= STA_PPSWANDER; 918 pps_stbcnt++; 919 } else if (u_nsec < -PPS_MAXWANDER) { 920 L_LINT(ftemp, -PPS_MAXWANDER); 921 pps_intcnt--; 922 time_status |= STA_PPSWANDER; 923 pps_stbcnt++; 924 } else { 925 pps_intcnt++; 926 } 927 if (pps_intcnt >= 4) { 928 pps_intcnt = 4; 929 if (pps_shift < pps_shiftmax) { 930 pps_shift++; 931 pps_intcnt = 0; 932 } 933 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { 934 pps_intcnt = -4; 935 if (pps_shift > PPS_FAVG) { 936 pps_shift--; 937 pps_intcnt = 0; 938 } 939 } 940 if (u_nsec < 0) 941 u_nsec = -u_nsec; 942 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; 943 944 /* 945 * The PPS frequency is recalculated and clamped to the maximum 946 * MAXFREQ. If enabled, the system clock frequency is updated as 947 * well. 948 */ 949 L_ADD(pps_freq, ftemp); 950 u_nsec = L_GINT(pps_freq); 951 if (u_nsec > MAXFREQ) 952 L_LINT(pps_freq, MAXFREQ); 953 else if (u_nsec < -MAXFREQ) 954 L_LINT(pps_freq, -MAXFREQ); 955 if (time_status & STA_PPSFREQ) 956 time_freq = pps_freq; 957 958 out: 959 NTPADJ_UNLOCK(); 960 } 961 #endif /* PPS_SYNC */ 962 963 #ifndef _SYS_SYSPROTO_H_ 964 struct adjtime_args { 965 struct timeval *delta; 966 struct timeval *olddelta; 967 }; 968 #endif 969 /* ARGSUSED */ 970 int 971 sys_adjtime(struct thread *td, struct adjtime_args *uap) 972 { 973 struct timeval delta, olddelta, *deltap; 974 int error; 975 976 if (uap->delta) { 977 error = copyin(uap->delta, &delta, sizeof(delta)); 978 if (error) 979 return (error); 980 deltap = δ 981 } else 982 deltap = NULL; 983 error = kern_adjtime(td, deltap, &olddelta); 984 if (uap->olddelta && error == 0) 985 error = copyout(&olddelta, uap->olddelta, sizeof(olddelta)); 986 return (error); 987 } 988 989 int 990 kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta) 991 { 992 struct timeval atv; 993 int64_t ltr, ltw; 994 int error; 995 996 if (delta != NULL) { 997 error = priv_check(td, PRIV_ADJTIME); 998 if (error != 0) 999 return (error); 1000 ltw = (int64_t)delta->tv_sec * 1000000 + delta->tv_usec; 1001 } 1002 NTPADJ_LOCK(); 1003 ltr = time_adjtime; 1004 if (delta != NULL) 1005 time_adjtime = ltw; 1006 NTPADJ_UNLOCK(); 1007 if (olddelta != NULL) { 1008 atv.tv_sec = ltr / 1000000; 1009 atv.tv_usec = ltr % 1000000; 1010 if (atv.tv_usec < 0) { 1011 atv.tv_usec += 1000000; 1012 atv.tv_sec--; 1013 } 1014 *olddelta = atv; 1015 } 1016 return (0); 1017 } 1018 1019 static struct callout resettodr_callout; 1020 static int resettodr_period = 1800; 1021 1022 static void 1023 periodic_resettodr(void *arg __unused) 1024 { 1025 1026 /* 1027 * Read of time_status is lock-less, which is fine since 1028 * ntp_is_time_error() operates on the consistent read value. 1029 */ 1030 if (!ntp_is_time_error(time_status)) 1031 resettodr(); 1032 if (resettodr_period > 0) 1033 callout_schedule(&resettodr_callout, resettodr_period * hz); 1034 } 1035 1036 static void 1037 shutdown_resettodr(void *arg __unused, int howto __unused) 1038 { 1039 1040 callout_drain(&resettodr_callout); 1041 /* Another unlocked read of time_status */ 1042 if (resettodr_period > 0 && !ntp_is_time_error(time_status)) 1043 resettodr(); 1044 } 1045 1046 static int 1047 sysctl_resettodr_period(SYSCTL_HANDLER_ARGS) 1048 { 1049 int error; 1050 1051 error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req); 1052 if (error || !req->newptr) 1053 return (error); 1054 if (cold) 1055 goto done; 1056 if (resettodr_period == 0) 1057 callout_stop(&resettodr_callout); 1058 else 1059 callout_reset(&resettodr_callout, resettodr_period * hz, 1060 periodic_resettodr, NULL); 1061 done: 1062 return (0); 1063 } 1064 1065 SYSCTL_PROC(_machdep, OID_AUTO, rtc_save_period, CTLTYPE_INT | CTLFLAG_RWTUN | 1066 CTLFLAG_MPSAFE, &resettodr_period, 1800, sysctl_resettodr_period, "I", 1067 "Save system time to RTC with this period (in seconds)"); 1068 1069 static void 1070 start_periodic_resettodr(void *arg __unused) 1071 { 1072 1073 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_resettodr, NULL, 1074 SHUTDOWN_PRI_FIRST); 1075 callout_init(&resettodr_callout, 1); 1076 if (resettodr_period == 0) 1077 return; 1078 callout_reset(&resettodr_callout, resettodr_period * hz, 1079 periodic_resettodr, NULL); 1080 } 1081 1082 SYSINIT(periodic_resettodr, SI_SUB_LAST, SI_ORDER_MIDDLE, 1083 start_periodic_resettodr, NULL); 1084