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