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 static 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 static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */ 158 static long time_reftime; /* time 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 #ifdef PPS_SYNC 166 /* 167 * The following variables are used when a pulse-per-second (PPS) signal 168 * is available and connected via a modem control lead. They establish 169 * the engineering parameters of the clock discipline loop when 170 * controlled by the PPS signal. 171 */ 172 #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */ 173 #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */ 174 #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */ 175 #define PPS_PAVG 4 /* phase avg interval (s) (shift) */ 176 #define PPS_VALID 120 /* PPS signal watchdog max (s) */ 177 #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */ 178 #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */ 179 180 static struct timespec pps_tf[3]; /* phase median filter */ 181 static l_fp pps_freq; /* scaled frequency offset (ns/s) */ 182 static long pps_fcount; /* frequency accumulator */ 183 static long pps_jitter; /* nominal jitter (ns) */ 184 static long pps_stabil; /* nominal stability (scaled ns/s) */ 185 static long pps_lastsec; /* time at last calibration (s) */ 186 static int pps_valid; /* signal watchdog counter */ 187 static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */ 188 static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */ 189 static int pps_intcnt; /* wander counter */ 190 191 /* 192 * PPS signal quality monitors 193 */ 194 static long pps_calcnt; /* calibration intervals */ 195 static long pps_jitcnt; /* jitter limit exceeded */ 196 static long pps_stbcnt; /* stability limit exceeded */ 197 static long pps_errcnt; /* calibration errors */ 198 #endif /* PPS_SYNC */ 199 /* 200 * End of phase/frequency-lock loop (PLL/FLL) definitions 201 */ 202 203 static void ntp_init(void); 204 static void hardupdate(long offset); 205 static void ntp_gettime1(struct ntptimeval *ntvp); 206 static int ntp_is_time_error(void); 207 208 static int 209 ntp_is_time_error(void) 210 { 211 /* 212 * Status word error decode. If any of these conditions occur, 213 * an error is returned, instead of the status word. Most 214 * applications will care only about the fact the system clock 215 * may not be trusted, not about the details. 216 * 217 * Hardware or software error 218 */ 219 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 220 221 /* 222 * PPS signal lost when either time or frequency synchronization 223 * requested 224 */ 225 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 226 !(time_status & STA_PPSSIGNAL)) || 227 228 /* 229 * PPS jitter exceeded when time synchronization requested 230 */ 231 (time_status & STA_PPSTIME && 232 time_status & STA_PPSJITTER) || 233 234 /* 235 * PPS wander exceeded or calibration error when frequency 236 * synchronization requested 237 */ 238 (time_status & STA_PPSFREQ && 239 time_status & (STA_PPSWANDER | STA_PPSERROR))) 240 return (1); 241 242 return (0); 243 } 244 245 static void 246 ntp_gettime1(struct ntptimeval *ntvp) 247 { 248 struct timespec atv; /* nanosecond time */ 249 250 GIANT_REQUIRED; 251 252 nanotime(&atv); 253 ntvp->time.tv_sec = atv.tv_sec; 254 ntvp->time.tv_nsec = atv.tv_nsec; 255 ntvp->maxerror = time_maxerror; 256 ntvp->esterror = time_esterror; 257 ntvp->tai = time_tai; 258 ntvp->time_state = time_state; 259 260 if (ntp_is_time_error()) 261 ntvp->time_state = TIME_ERROR; 262 } 263 264 /* 265 * ntp_gettime() - NTP user application interface 266 * 267 * See the timex.h header file for synopsis and API description. Note that 268 * the TAI offset is returned in the ntvtimeval.tai structure member. 269 */ 270 #ifndef _SYS_SYSPROTO_H_ 271 struct ntp_gettime_args { 272 struct ntptimeval *ntvp; 273 }; 274 #endif 275 /* ARGSUSED */ 276 int 277 ntp_gettime(struct thread *td, struct ntp_gettime_args *uap) 278 { 279 struct ntptimeval ntv; 280 281 mtx_lock(&Giant); 282 ntp_gettime1(&ntv); 283 mtx_unlock(&Giant); 284 285 td->td_retval[0] = ntv.time_state; 286 return (copyout(&ntv, uap->ntvp, sizeof(ntv))); 287 } 288 289 static int 290 ntp_sysctl(SYSCTL_HANDLER_ARGS) 291 { 292 struct ntptimeval ntv; /* temporary structure */ 293 294 ntp_gettime1(&ntv); 295 296 return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req)); 297 } 298 299 SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, ""); 300 SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD, 301 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", ""); 302 303 #ifdef PPS_SYNC 304 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, &pps_shiftmax, 0, ""); 305 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, &pps_shift, 0, ""); 306 SYSCTL_LONG(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, 307 &time_monitor, 0, ""); 308 309 SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD, &pps_freq, sizeof(pps_freq), "I", ""); 310 SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD, &time_freq, sizeof(time_freq), "I", ""); 311 #endif 312 313 /* 314 * ntp_adjtime() - NTP daemon application interface 315 * 316 * See the timex.h header file for synopsis and API description. Note that 317 * the timex.constant structure member has a dual purpose to set the time 318 * constant and to set the TAI offset. 319 */ 320 #ifndef _SYS_SYSPROTO_H_ 321 struct ntp_adjtime_args { 322 struct timex *tp; 323 }; 324 #endif 325 326 int 327 ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap) 328 { 329 struct timex ntv; /* temporary structure */ 330 long freq; /* frequency ns/s) */ 331 int modes; /* mode bits from structure */ 332 int s; /* caller priority */ 333 int error; 334 335 error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv)); 336 if (error) 337 return(error); 338 339 /* 340 * Update selected clock variables - only the superuser can 341 * change anything. Note that there is no error checking here on 342 * the assumption the superuser should know what it is doing. 343 * Note that either the time constant or TAI offset are loaded 344 * from the ntv.constant member, depending on the mode bits. If 345 * the STA_PLL bit in the status word is cleared, the state and 346 * status words are reset to the initial values at boot. 347 */ 348 mtx_lock(&Giant); 349 modes = ntv.modes; 350 if (modes) 351 error = priv_check(td, PRIV_NTP_ADJTIME); 352 if (error) 353 goto done2; 354 s = splclock(); 355 if (modes & MOD_MAXERROR) 356 time_maxerror = ntv.maxerror; 357 if (modes & MOD_ESTERROR) 358 time_esterror = ntv.esterror; 359 if (modes & MOD_STATUS) { 360 if (time_status & STA_PLL && !(ntv.status & STA_PLL)) { 361 time_state = TIME_OK; 362 time_status = STA_UNSYNC; 363 #ifdef PPS_SYNC 364 pps_shift = PPS_FAVG; 365 #endif /* PPS_SYNC */ 366 } 367 time_status &= STA_RONLY; 368 time_status |= ntv.status & ~STA_RONLY; 369 } 370 if (modes & MOD_TIMECONST) { 371 if (ntv.constant < 0) 372 time_constant = 0; 373 else if (ntv.constant > MAXTC) 374 time_constant = MAXTC; 375 else 376 time_constant = ntv.constant; 377 } 378 if (modes & MOD_TAI) { 379 if (ntv.constant > 0) /* XXX zero & negative numbers ? */ 380 time_tai = ntv.constant; 381 } 382 #ifdef PPS_SYNC 383 if (modes & MOD_PPSMAX) { 384 if (ntv.shift < PPS_FAVG) 385 pps_shiftmax = PPS_FAVG; 386 else if (ntv.shift > PPS_FAVGMAX) 387 pps_shiftmax = PPS_FAVGMAX; 388 else 389 pps_shiftmax = ntv.shift; 390 } 391 #endif /* PPS_SYNC */ 392 if (modes & MOD_NANO) 393 time_status |= STA_NANO; 394 if (modes & MOD_MICRO) 395 time_status &= ~STA_NANO; 396 if (modes & MOD_CLKB) 397 time_status |= STA_CLK; 398 if (modes & MOD_CLKA) 399 time_status &= ~STA_CLK; 400 if (modes & MOD_FREQUENCY) { 401 freq = (ntv.freq * 1000LL) >> 16; 402 if (freq > MAXFREQ) 403 L_LINT(time_freq, MAXFREQ); 404 else if (freq < -MAXFREQ) 405 L_LINT(time_freq, -MAXFREQ); 406 else { 407 /* 408 * ntv.freq is [PPM * 2^16] = [us/s * 2^16] 409 * time_freq is [ns/s * 2^32] 410 */ 411 time_freq = ntv.freq * 1000LL * 65536LL; 412 } 413 #ifdef PPS_SYNC 414 pps_freq = time_freq; 415 #endif /* PPS_SYNC */ 416 } 417 if (modes & MOD_OFFSET) { 418 if (time_status & STA_NANO) 419 hardupdate(ntv.offset); 420 else 421 hardupdate(ntv.offset * 1000); 422 } 423 424 /* 425 * Retrieve all clock variables. Note that the TAI offset is 426 * returned only by ntp_gettime(); 427 */ 428 if (time_status & STA_NANO) 429 ntv.offset = L_GINT(time_offset); 430 else 431 ntv.offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */ 432 ntv.freq = L_GINT((time_freq / 1000LL) << 16); 433 ntv.maxerror = time_maxerror; 434 ntv.esterror = time_esterror; 435 ntv.status = time_status; 436 ntv.constant = time_constant; 437 if (time_status & STA_NANO) 438 ntv.precision = time_precision; 439 else 440 ntv.precision = time_precision / 1000; 441 ntv.tolerance = MAXFREQ * SCALE_PPM; 442 #ifdef PPS_SYNC 443 ntv.shift = pps_shift; 444 ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16); 445 if (time_status & STA_NANO) 446 ntv.jitter = pps_jitter; 447 else 448 ntv.jitter = pps_jitter / 1000; 449 ntv.stabil = pps_stabil; 450 ntv.calcnt = pps_calcnt; 451 ntv.errcnt = pps_errcnt; 452 ntv.jitcnt = pps_jitcnt; 453 ntv.stbcnt = pps_stbcnt; 454 #endif /* PPS_SYNC */ 455 splx(s); 456 457 error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv)); 458 if (error) 459 goto done2; 460 461 if (ntp_is_time_error()) 462 td->td_retval[0] = TIME_ERROR; 463 else 464 td->td_retval[0] = time_state; 465 466 done2: 467 mtx_unlock(&Giant); 468 return (error); 469 } 470 471 /* 472 * second_overflow() - called after ntp_tick_adjust() 473 * 474 * This routine is ordinarily called immediately following the above 475 * routine ntp_tick_adjust(). While these two routines are normally 476 * combined, they are separated here only for the purposes of 477 * simulation. 478 */ 479 void 480 ntp_update_second(int64_t *adjustment, time_t *newsec) 481 { 482 int tickrate; 483 l_fp ftemp; /* 32/64-bit temporary */ 484 485 /* 486 * On rollover of the second both the nanosecond and microsecond 487 * clocks are updated and the state machine cranked as 488 * necessary. The phase adjustment to be used for the next 489 * second is calculated and the maximum error is increased by 490 * the tolerance. 491 */ 492 time_maxerror += MAXFREQ / 1000; 493 494 /* 495 * Leap second processing. If in leap-insert state at 496 * the end of the day, the system clock is set back one 497 * second; if in leap-delete state, the system clock is 498 * set ahead one second. The nano_time() routine or 499 * external clock driver will insure that reported time 500 * is always monotonic. 501 */ 502 switch (time_state) { 503 504 /* 505 * No warning. 506 */ 507 case TIME_OK: 508 if (time_status & STA_INS) 509 time_state = TIME_INS; 510 else if (time_status & STA_DEL) 511 time_state = TIME_DEL; 512 break; 513 514 /* 515 * Insert second 23:59:60 following second 516 * 23:59:59. 517 */ 518 case TIME_INS: 519 if (!(time_status & STA_INS)) 520 time_state = TIME_OK; 521 else if ((*newsec) % 86400 == 0) { 522 (*newsec)--; 523 time_state = TIME_OOP; 524 time_tai++; 525 } 526 break; 527 528 /* 529 * Delete second 23:59:59. 530 */ 531 case TIME_DEL: 532 if (!(time_status & STA_DEL)) 533 time_state = TIME_OK; 534 else if (((*newsec) + 1) % 86400 == 0) { 535 (*newsec)++; 536 time_tai--; 537 time_state = TIME_WAIT; 538 } 539 break; 540 541 /* 542 * Insert second in progress. 543 */ 544 case TIME_OOP: 545 time_state = TIME_WAIT; 546 break; 547 548 /* 549 * Wait for status bits to clear. 550 */ 551 case TIME_WAIT: 552 if (!(time_status & (STA_INS | STA_DEL))) 553 time_state = TIME_OK; 554 } 555 556 /* 557 * Compute the total time adjustment for the next second 558 * in ns. The offset is reduced by a factor depending on 559 * whether the PPS signal is operating. Note that the 560 * value is in effect scaled by the clock frequency, 561 * since the adjustment is added at each tick interrupt. 562 */ 563 ftemp = time_offset; 564 #ifdef PPS_SYNC 565 /* XXX even if PPS signal dies we should finish adjustment ? */ 566 if (time_status & STA_PPSTIME && time_status & 567 STA_PPSSIGNAL) 568 L_RSHIFT(ftemp, pps_shift); 569 else 570 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 571 #else 572 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 573 #endif /* PPS_SYNC */ 574 time_adj = ftemp; 575 L_SUB(time_offset, ftemp); 576 L_ADD(time_adj, time_freq); 577 578 /* 579 * Apply any correction from adjtime(2). If more than one second 580 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM) 581 * until the last second is slewed the final < 500 usecs. 582 */ 583 if (time_adjtime != 0) { 584 if (time_adjtime > 1000000) 585 tickrate = 5000; 586 else if (time_adjtime < -1000000) 587 tickrate = -5000; 588 else if (time_adjtime > 500) 589 tickrate = 500; 590 else if (time_adjtime < -500) 591 tickrate = -500; 592 else 593 tickrate = time_adjtime; 594 time_adjtime -= tickrate; 595 L_LINT(ftemp, tickrate * 1000); 596 L_ADD(time_adj, ftemp); 597 } 598 *adjustment = time_adj; 599 600 #ifdef PPS_SYNC 601 if (pps_valid > 0) 602 pps_valid--; 603 else 604 time_status &= ~STA_PPSSIGNAL; 605 #endif /* PPS_SYNC */ 606 } 607 608 /* 609 * ntp_init() - initialize variables and structures 610 * 611 * This routine must be called after the kernel variables hz and tick 612 * are set or changed and before the next tick interrupt. In this 613 * particular implementation, these values are assumed set elsewhere in 614 * the kernel. The design allows the clock frequency and tick interval 615 * to be changed while the system is running. So, this routine should 616 * probably be integrated with the code that does that. 617 */ 618 static void 619 ntp_init() 620 { 621 622 /* 623 * The following variables are initialized only at startup. Only 624 * those structures not cleared by the compiler need to be 625 * initialized, and these only in the simulator. In the actual 626 * kernel, any nonzero values here will quickly evaporate. 627 */ 628 L_CLR(time_offset); 629 L_CLR(time_freq); 630 #ifdef PPS_SYNC 631 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0; 632 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0; 633 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0; 634 pps_fcount = 0; 635 L_CLR(pps_freq); 636 #endif /* PPS_SYNC */ 637 } 638 639 SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL); 640 641 /* 642 * hardupdate() - local clock update 643 * 644 * This routine is called by ntp_adjtime() to update the local clock 645 * phase and frequency. The implementation is of an adaptive-parameter, 646 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new 647 * time and frequency offset estimates for each call. If the kernel PPS 648 * discipline code is configured (PPS_SYNC), the PPS signal itself 649 * determines the new time offset, instead of the calling argument. 650 * Presumably, calls to ntp_adjtime() occur only when the caller 651 * believes the local clock is valid within some bound (+-128 ms with 652 * NTP). If the caller's time is far different than the PPS time, an 653 * argument will ensue, and it's not clear who will lose. 654 * 655 * For uncompensated quartz crystal oscillators and nominal update 656 * intervals less than 256 s, operation should be in phase-lock mode, 657 * where the loop is disciplined to phase. For update intervals greater 658 * than 1024 s, operation should be in frequency-lock mode, where the 659 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode 660 * is selected by the STA_MODE status bit. 661 */ 662 static void 663 hardupdate(offset) 664 long offset; /* clock offset (ns) */ 665 { 666 long mtemp; 667 l_fp ftemp; 668 669 /* 670 * Select how the phase is to be controlled and from which 671 * source. If the PPS signal is present and enabled to 672 * discipline the time, the PPS offset is used; otherwise, the 673 * argument offset is used. 674 */ 675 if (!(time_status & STA_PLL)) 676 return; 677 if (!(time_status & STA_PPSTIME && time_status & 678 STA_PPSSIGNAL)) { 679 if (offset > MAXPHASE) 680 time_monitor = MAXPHASE; 681 else if (offset < -MAXPHASE) 682 time_monitor = -MAXPHASE; 683 else 684 time_monitor = offset; 685 L_LINT(time_offset, time_monitor); 686 } 687 688 /* 689 * Select how the frequency is to be controlled and in which 690 * mode (PLL or FLL). If the PPS signal is present and enabled 691 * to discipline the frequency, the PPS frequency is used; 692 * otherwise, the argument offset is used to compute it. 693 */ 694 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) { 695 time_reftime = time_second; 696 return; 697 } 698 if (time_status & STA_FREQHOLD || time_reftime == 0) 699 time_reftime = time_second; 700 mtemp = time_second - time_reftime; 701 L_LINT(ftemp, time_monitor); 702 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); 703 L_MPY(ftemp, mtemp); 704 L_ADD(time_freq, ftemp); 705 time_status &= ~STA_MODE; 706 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > 707 MAXSEC)) { 708 L_LINT(ftemp, (time_monitor << 4) / mtemp); 709 L_RSHIFT(ftemp, SHIFT_FLL + 4); 710 L_ADD(time_freq, ftemp); 711 time_status |= STA_MODE; 712 } 713 time_reftime = time_second; 714 if (L_GINT(time_freq) > MAXFREQ) 715 L_LINT(time_freq, MAXFREQ); 716 else if (L_GINT(time_freq) < -MAXFREQ) 717 L_LINT(time_freq, -MAXFREQ); 718 } 719 720 #ifdef PPS_SYNC 721 /* 722 * hardpps() - discipline CPU clock oscillator to external PPS signal 723 * 724 * This routine is called at each PPS interrupt in order to discipline 725 * the CPU clock oscillator to the PPS signal. There are two independent 726 * first-order feedback loops, one for the phase, the other for the 727 * frequency. The phase loop measures and grooms the PPS phase offset 728 * and leaves it in a handy spot for the seconds overflow routine. The 729 * frequency loop averages successive PPS phase differences and 730 * calculates the PPS frequency offset, which is also processed by the 731 * seconds overflow routine. The code requires the caller to capture the 732 * time and architecture-dependent hardware counter values in 733 * nanoseconds at the on-time PPS signal transition. 734 * 735 * Note that, on some Unix systems this routine runs at an interrupt 736 * priority level higher than the timer interrupt routine hardclock(). 737 * Therefore, the variables used are distinct from the hardclock() 738 * variables, except for the actual time and frequency variables, which 739 * are determined by this routine and updated atomically. 740 */ 741 void 742 hardpps(tsp, nsec) 743 struct timespec *tsp; /* time at PPS */ 744 long nsec; /* hardware counter at PPS */ 745 { 746 long u_sec, u_nsec, v_nsec; /* temps */ 747 l_fp ftemp; 748 749 /* 750 * The signal is first processed by a range gate and frequency 751 * discriminator. The range gate rejects noise spikes outside 752 * the range +-500 us. The frequency discriminator rejects input 753 * signals with apparent frequency outside the range 1 +-500 754 * PPM. If two hits occur in the same second, we ignore the 755 * later hit; if not and a hit occurs outside the range gate, 756 * keep the later hit for later comparison, but do not process 757 * it. 758 */ 759 time_status |= STA_PPSSIGNAL | STA_PPSJITTER; 760 time_status &= ~(STA_PPSWANDER | STA_PPSERROR); 761 pps_valid = PPS_VALID; 762 u_sec = tsp->tv_sec; 763 u_nsec = tsp->tv_nsec; 764 if (u_nsec >= (NANOSECOND >> 1)) { 765 u_nsec -= NANOSECOND; 766 u_sec++; 767 } 768 v_nsec = u_nsec - pps_tf[0].tv_nsec; 769 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - 770 MAXFREQ) 771 return; 772 pps_tf[2] = pps_tf[1]; 773 pps_tf[1] = pps_tf[0]; 774 pps_tf[0].tv_sec = u_sec; 775 pps_tf[0].tv_nsec = u_nsec; 776 777 /* 778 * Compute the difference between the current and previous 779 * counter values. If the difference exceeds 0.5 s, assume it 780 * has wrapped around, so correct 1.0 s. If the result exceeds 781 * the tick interval, the sample point has crossed a tick 782 * boundary during the last second, so correct the tick. Very 783 * intricate. 784 */ 785 u_nsec = nsec; 786 if (u_nsec > (NANOSECOND >> 1)) 787 u_nsec -= NANOSECOND; 788 else if (u_nsec < -(NANOSECOND >> 1)) 789 u_nsec += NANOSECOND; 790 pps_fcount += u_nsec; 791 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) 792 return; 793 time_status &= ~STA_PPSJITTER; 794 795 /* 796 * A three-stage median filter is used to help denoise the PPS 797 * time. The median sample becomes the time offset estimate; the 798 * difference between the other two samples becomes the time 799 * dispersion (jitter) estimate. 800 */ 801 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { 802 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { 803 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ 804 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; 805 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { 806 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ 807 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; 808 } else { 809 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ 810 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; 811 } 812 } else { 813 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { 814 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ 815 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; 816 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { 817 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ 818 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; 819 } else { 820 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ 821 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; 822 } 823 } 824 825 /* 826 * Nominal jitter is due to PPS signal noise and interrupt 827 * latency. If it exceeds the popcorn threshold, the sample is 828 * discarded. otherwise, if so enabled, the time offset is 829 * updated. We can tolerate a modest loss of data here without 830 * much degrading time accuracy. 831 */ 832 if (u_nsec > (pps_jitter << PPS_POPCORN)) { 833 time_status |= STA_PPSJITTER; 834 pps_jitcnt++; 835 } else if (time_status & STA_PPSTIME) { 836 time_monitor = -v_nsec; 837 L_LINT(time_offset, time_monitor); 838 } 839 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; 840 u_sec = pps_tf[0].tv_sec - pps_lastsec; 841 if (u_sec < (1 << pps_shift)) 842 return; 843 844 /* 845 * At the end of the calibration interval the difference between 846 * the first and last counter values becomes the scaled 847 * frequency. It will later be divided by the length of the 848 * interval to determine the frequency update. If the frequency 849 * exceeds a sanity threshold, or if the actual calibration 850 * interval is not equal to the expected length, the data are 851 * discarded. We can tolerate a modest loss of data here without 852 * much degrading frequency accuracy. 853 */ 854 pps_calcnt++; 855 v_nsec = -pps_fcount; 856 pps_lastsec = pps_tf[0].tv_sec; 857 pps_fcount = 0; 858 u_nsec = MAXFREQ << pps_shift; 859 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << 860 pps_shift)) { 861 time_status |= STA_PPSERROR; 862 pps_errcnt++; 863 return; 864 } 865 866 /* 867 * Here the raw frequency offset and wander (stability) is 868 * calculated. If the wander is less than the wander threshold 869 * for four consecutive averaging intervals, the interval is 870 * doubled; if it is greater than the threshold for four 871 * consecutive intervals, the interval is halved. The scaled 872 * frequency offset is converted to frequency offset. The 873 * stability metric is calculated as the average of recent 874 * frequency changes, but is used only for performance 875 * monitoring. 876 */ 877 L_LINT(ftemp, v_nsec); 878 L_RSHIFT(ftemp, pps_shift); 879 L_SUB(ftemp, pps_freq); 880 u_nsec = L_GINT(ftemp); 881 if (u_nsec > PPS_MAXWANDER) { 882 L_LINT(ftemp, PPS_MAXWANDER); 883 pps_intcnt--; 884 time_status |= STA_PPSWANDER; 885 pps_stbcnt++; 886 } else if (u_nsec < -PPS_MAXWANDER) { 887 L_LINT(ftemp, -PPS_MAXWANDER); 888 pps_intcnt--; 889 time_status |= STA_PPSWANDER; 890 pps_stbcnt++; 891 } else { 892 pps_intcnt++; 893 } 894 if (pps_intcnt >= 4) { 895 pps_intcnt = 4; 896 if (pps_shift < pps_shiftmax) { 897 pps_shift++; 898 pps_intcnt = 0; 899 } 900 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { 901 pps_intcnt = -4; 902 if (pps_shift > PPS_FAVG) { 903 pps_shift--; 904 pps_intcnt = 0; 905 } 906 } 907 if (u_nsec < 0) 908 u_nsec = -u_nsec; 909 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; 910 911 /* 912 * The PPS frequency is recalculated and clamped to the maximum 913 * MAXFREQ. If enabled, the system clock frequency is updated as 914 * well. 915 */ 916 L_ADD(pps_freq, ftemp); 917 u_nsec = L_GINT(pps_freq); 918 if (u_nsec > MAXFREQ) 919 L_LINT(pps_freq, MAXFREQ); 920 else if (u_nsec < -MAXFREQ) 921 L_LINT(pps_freq, -MAXFREQ); 922 if (time_status & STA_PPSFREQ) 923 time_freq = pps_freq; 924 } 925 #endif /* PPS_SYNC */ 926 927 #ifndef _SYS_SYSPROTO_H_ 928 struct adjtime_args { 929 struct timeval *delta; 930 struct timeval *olddelta; 931 }; 932 #endif 933 /* ARGSUSED */ 934 int 935 adjtime(struct thread *td, struct adjtime_args *uap) 936 { 937 struct timeval delta, olddelta, *deltap; 938 int error; 939 940 if (uap->delta) { 941 error = copyin(uap->delta, &delta, sizeof(delta)); 942 if (error) 943 return (error); 944 deltap = δ 945 } else 946 deltap = NULL; 947 error = kern_adjtime(td, deltap, &olddelta); 948 if (uap->olddelta && error == 0) 949 error = copyout(&olddelta, uap->olddelta, sizeof(olddelta)); 950 return (error); 951 } 952 953 int 954 kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta) 955 { 956 struct timeval atv; 957 int error; 958 959 mtx_lock(&Giant); 960 if (olddelta) { 961 atv.tv_sec = time_adjtime / 1000000; 962 atv.tv_usec = time_adjtime % 1000000; 963 if (atv.tv_usec < 0) { 964 atv.tv_usec += 1000000; 965 atv.tv_sec--; 966 } 967 *olddelta = atv; 968 } 969 if (delta) { 970 if ((error = priv_check(td, PRIV_ADJTIME))) { 971 mtx_unlock(&Giant); 972 return (error); 973 } 974 time_adjtime = (int64_t)delta->tv_sec * 1000000 + 975 delta->tv_usec; 976 } 977 mtx_unlock(&Giant); 978 return (0); 979 } 980 981 static struct callout resettodr_callout; 982 static int resettodr_period = 1800; 983 984 static void 985 periodic_resettodr(void *arg __unused) 986 { 987 988 if (!ntp_is_time_error()) { 989 mtx_lock(&Giant); 990 resettodr(); 991 mtx_unlock(&Giant); 992 } 993 if (resettodr_period > 0) 994 callout_schedule(&resettodr_callout, resettodr_period * hz); 995 } 996 997 static void 998 shutdown_resettodr(void *arg __unused, int howto __unused) 999 { 1000 1001 callout_drain(&resettodr_callout); 1002 if (resettodr_period > 0 && !ntp_is_time_error()) { 1003 mtx_lock(&Giant); 1004 resettodr(); 1005 mtx_unlock(&Giant); 1006 } 1007 } 1008 1009 static int 1010 sysctl_resettodr_period(SYSCTL_HANDLER_ARGS) 1011 { 1012 int error; 1013 1014 error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req); 1015 if (error || !req->newptr) 1016 return (error); 1017 if (resettodr_period == 0) 1018 callout_stop(&resettodr_callout); 1019 else 1020 callout_reset(&resettodr_callout, resettodr_period * hz, 1021 periodic_resettodr, NULL); 1022 return (0); 1023 } 1024 1025 SYSCTL_PROC(_machdep, OID_AUTO, rtc_save_period, CTLTYPE_INT|CTLFLAG_RW, 1026 &resettodr_period, 1800, sysctl_resettodr_period, "I", 1027 "Save system time to RTC with this period (in seconds)"); 1028 TUNABLE_INT("machdep.rtc_save_period", &resettodr_period); 1029 1030 static void 1031 start_periodic_resettodr(void *arg __unused) 1032 { 1033 1034 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_resettodr, NULL, 1035 SHUTDOWN_PRI_FIRST); 1036 callout_init(&resettodr_callout, 1); 1037 if (resettodr_period == 0) 1038 return; 1039 callout_reset(&resettodr_callout, resettodr_period * hz, 1040 periodic_resettodr, NULL); 1041 } 1042 1043 SYSINIT(periodic_resettodr, SI_SUB_RUN_SCHEDULER, SI_ORDER_MIDDLE, 1044 start_periodic_resettodr, NULL); 1045