1 /*********************************************************************** 2 * * 3 * Copyright (c) David L. Mills 1993-2001 * 4 * * 5 * Permission to use, copy, modify, and distribute this software and * 6 * its documentation for any purpose and without fee is hereby * 7 * granted, provided that the above copyright notice appears in all * 8 * copies and that both the copyright notice and this permission * 9 * notice appear in supporting documentation, and that the name * 10 * University of Delaware not be used in advertising or publicity * 11 * pertaining to distribution of the software without specific, * 12 * written prior permission. The University of Delaware makes no * 13 * representations about the suitability this software for any * 14 * purpose. It is provided "as is" without express or implied * 15 * warranty. * 16 * * 17 **********************************************************************/ 18 19 /* 20 * Adapted from the original sources for FreeBSD and timecounters by: 21 * Poul-Henning Kamp <phk@FreeBSD.org>. 22 * 23 * The 32bit version of the "LP" macros seems a bit past its "sell by" 24 * date so I have retained only the 64bit version and included it directly 25 * in this file. 26 * 27 * Only minor changes done to interface with the timecounters over in 28 * sys/kern/kern_clock.c. Some of the comments below may be (even more) 29 * confusing and/or plain wrong in that context. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "opt_ntp.h" 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/sysproto.h> 40 #include <sys/kernel.h> 41 #include <sys/proc.h> 42 #include <sys/lock.h> 43 #include <sys/mutex.h> 44 #include <sys/time.h> 45 #include <sys/timex.h> 46 #include <sys/timetc.h> 47 #include <sys/timepps.h> 48 #include <sys/sysctl.h> 49 50 /* 51 * Single-precision macros for 64-bit machines 52 */ 53 typedef int64_t l_fp; 54 #define L_ADD(v, u) ((v) += (u)) 55 #define L_SUB(v, u) ((v) -= (u)) 56 #define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32) 57 #define L_NEG(v) ((v) = -(v)) 58 #define L_RSHIFT(v, n) \ 59 do { \ 60 if ((v) < 0) \ 61 (v) = -(-(v) >> (n)); \ 62 else \ 63 (v) = (v) >> (n); \ 64 } while (0) 65 #define L_MPY(v, a) ((v) *= (a)) 66 #define L_CLR(v) ((v) = 0) 67 #define L_ISNEG(v) ((v) < 0) 68 #define L_LINT(v, a) ((v) = (int64_t)(a) << 32) 69 #define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32) 70 71 /* 72 * Generic NTP kernel interface 73 * 74 * These routines constitute the Network Time Protocol (NTP) interfaces 75 * for user and daemon application programs. The ntp_gettime() routine 76 * provides the time, maximum error (synch distance) and estimated error 77 * (dispersion) to client user application programs. The ntp_adjtime() 78 * routine is used by the NTP daemon to adjust the system clock to an 79 * externally derived time. The time offset and related variables set by 80 * this routine are used by other routines in this module to adjust the 81 * phase and frequency of the clock discipline loop which controls the 82 * system clock. 83 * 84 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO 85 * defined), the time at each tick interrupt is derived directly from 86 * the kernel time variable. When the kernel time is reckoned in 87 * microseconds, (NTP_NANO undefined), the time is derived from the 88 * kernel time variable together with a variable representing the 89 * leftover nanoseconds at the last tick interrupt. In either case, the 90 * current nanosecond time is reckoned from these values plus an 91 * interpolated value derived by the clock routines in another 92 * architecture-specific module. The interpolation can use either a 93 * dedicated counter or a processor cycle counter (PCC) implemented in 94 * some architectures. 95 * 96 * Note that all routines must run at priority splclock or higher. 97 */ 98 /* 99 * Phase/frequency-lock loop (PLL/FLL) definitions 100 * 101 * The nanosecond clock discipline uses two variable types, time 102 * variables and frequency variables. Both types are represented as 64- 103 * bit fixed-point quantities with the decimal point between two 32-bit 104 * halves. On a 32-bit machine, each half is represented as a single 105 * word and mathematical operations are done using multiple-precision 106 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is 107 * used. 108 * 109 * A time variable is a signed 64-bit fixed-point number in ns and 110 * fraction. It represents the remaining time offset to be amortized 111 * over succeeding tick interrupts. The maximum time offset is about 112 * 0.5 s and the resolution is about 2.3e-10 ns. 113 * 114 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 115 * 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 1 116 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 117 * |s s s| ns | 118 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 119 * | fraction | 120 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 121 * 122 * A frequency variable is a signed 64-bit fixed-point number in ns/s 123 * and fraction. It represents the ns and fraction to be added to the 124 * kernel time variable at each second. The maximum frequency offset is 125 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s. 126 * 127 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 128 * 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 1 129 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 130 * |s s s s s s s s s s s s s| ns/s | 131 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 132 * | fraction | 133 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 134 */ 135 /* 136 * The following variables establish the state of the PLL/FLL and the 137 * residual time and frequency offset of the local clock. 138 */ 139 #define SHIFT_PLL 4 /* PLL loop gain (shift) */ 140 #define SHIFT_FLL 2 /* FLL loop gain (shift) */ 141 142 static int time_state = TIME_OK; /* clock state */ 143 static int time_status = STA_UNSYNC; /* clock status bits */ 144 static long time_tai; /* TAI offset (s) */ 145 static long time_monitor; /* last time offset scaled (ns) */ 146 static long time_constant; /* poll interval (shift) (s) */ 147 static long time_precision = 1; /* clock precision (ns) */ 148 static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */ 149 static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */ 150 static long time_reftime; /* time at last adjustment (s) */ 151 static l_fp time_offset; /* time offset (ns) */ 152 static l_fp time_freq; /* frequency offset (ns/s) */ 153 static l_fp time_adj; /* tick adjust (ns/s) */ 154 155 static int64_t time_adjtime; /* correction from adjtime(2) (usec) */ 156 157 #ifdef PPS_SYNC 158 /* 159 * The following variables are used when a pulse-per-second (PPS) signal 160 * is available and connected via a modem control lead. They establish 161 * the engineering parameters of the clock discipline loop when 162 * controlled by the PPS signal. 163 */ 164 #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */ 165 #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */ 166 #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */ 167 #define PPS_PAVG 4 /* phase avg interval (s) (shift) */ 168 #define PPS_VALID 120 /* PPS signal watchdog max (s) */ 169 #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */ 170 #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */ 171 172 static struct timespec pps_tf[3]; /* phase median filter */ 173 static l_fp pps_freq; /* scaled frequency offset (ns/s) */ 174 static long pps_fcount; /* frequency accumulator */ 175 static long pps_jitter; /* nominal jitter (ns) */ 176 static long pps_stabil; /* nominal stability (scaled ns/s) */ 177 static long pps_lastsec; /* time at last calibration (s) */ 178 static int pps_valid; /* signal watchdog counter */ 179 static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */ 180 static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */ 181 static int pps_intcnt; /* wander counter */ 182 183 /* 184 * PPS signal quality monitors 185 */ 186 static long pps_calcnt; /* calibration intervals */ 187 static long pps_jitcnt; /* jitter limit exceeded */ 188 static long pps_stbcnt; /* stability limit exceeded */ 189 static long pps_errcnt; /* calibration errors */ 190 #endif /* PPS_SYNC */ 191 /* 192 * End of phase/frequency-lock loop (PLL/FLL) definitions 193 */ 194 195 static void ntp_init(void); 196 static void hardupdate(long offset); 197 static void ntp_gettime1(struct ntptimeval *ntvp); 198 199 static void 200 ntp_gettime1(struct ntptimeval *ntvp) 201 { 202 struct timespec atv; /* nanosecond time */ 203 204 nanotime(&atv); 205 ntvp->time.tv_sec = atv.tv_sec; 206 ntvp->time.tv_nsec = atv.tv_nsec; 207 ntvp->maxerror = time_maxerror; 208 ntvp->esterror = time_esterror; 209 ntvp->tai = time_tai; 210 ntvp->time_state = time_state; 211 212 /* 213 * Status word error decode. If any of these conditions occur, 214 * an error is returned, instead of the status word. Most 215 * applications will care only about the fact the system clock 216 * may not be trusted, not about the details. 217 * 218 * Hardware or software error 219 */ 220 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 221 222 /* 223 * PPS signal lost when either time or frequency synchronization 224 * requested 225 */ 226 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 227 !(time_status & STA_PPSSIGNAL)) || 228 229 /* 230 * PPS jitter exceeded when time synchronization requested 231 */ 232 (time_status & STA_PPSTIME && 233 time_status & STA_PPSJITTER) || 234 235 /* 236 * PPS wander exceeded or calibration error when frequency 237 * synchronization requested 238 */ 239 (time_status & STA_PPSFREQ && 240 time_status & (STA_PPSWANDER | STA_PPSERROR))) 241 ntvp->time_state = TIME_ERROR; 242 } 243 244 /* 245 * ntp_gettime() - NTP user application interface 246 * 247 * See the timex.h header file for synopsis and API description. Note 248 * that the TAI offset is returned in the ntvtimeval.tai structure 249 * member. 250 */ 251 #ifndef _SYS_SYSPROTO_H_ 252 struct ntp_gettime_args { 253 struct ntptimeval *ntvp; 254 }; 255 #endif 256 /* ARGSUSED */ 257 int 258 ntp_gettime(struct thread *td, struct ntp_gettime_args *uap) 259 { 260 struct ntptimeval ntv; 261 262 ntp_gettime1(&ntv); 263 264 return (copyout(&ntv, uap->ntvp, sizeof(ntv))); 265 } 266 267 static int 268 ntp_sysctl(SYSCTL_HANDLER_ARGS) 269 { 270 struct ntptimeval ntv; /* temporary structure */ 271 272 ntp_gettime1(&ntv); 273 274 return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req)); 275 } 276 277 SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, ""); 278 SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD, 279 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", ""); 280 281 #ifdef PPS_SYNC 282 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, &pps_shiftmax, 0, ""); 283 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, &pps_shift, 0, ""); 284 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, &time_monitor, 0, ""); 285 286 SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD, &pps_freq, sizeof(pps_freq), "I", ""); 287 SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD, &time_freq, sizeof(time_freq), "I", ""); 288 #endif 289 /* 290 * ntp_adjtime() - NTP daemon application interface 291 * 292 * See the timex.h header file for synopsis and API description. Note 293 * that the timex.constant structure member has a dual purpose to set 294 * the time constant and to set the TAI offset. 295 */ 296 #ifndef _SYS_SYSPROTO_H_ 297 struct ntp_adjtime_args { 298 struct timex *tp; 299 }; 300 #endif 301 302 /* 303 * MPSAFE 304 */ 305 int 306 ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap) 307 { 308 struct timex ntv; /* temporary structure */ 309 long freq; /* frequency ns/s) */ 310 int modes; /* mode bits from structure */ 311 int s; /* caller priority */ 312 int error; 313 314 error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv)); 315 if (error) 316 return(error); 317 318 /* 319 * Update selected clock variables - only the superuser can 320 * change anything. Note that there is no error checking here on 321 * the assumption the superuser should know what it is doing. 322 * Note that either the time constant or TAI offset are loaded 323 * from the ntv.constant member, depending on the mode bits. If 324 * the STA_PLL bit in the status word is cleared, the state and 325 * status words are reset to the initial values at boot. 326 */ 327 mtx_lock(&Giant); 328 modes = ntv.modes; 329 if (modes) 330 error = suser(td); 331 if (error) 332 goto done2; 333 s = splclock(); 334 if (modes & MOD_MAXERROR) 335 time_maxerror = ntv.maxerror; 336 if (modes & MOD_ESTERROR) 337 time_esterror = ntv.esterror; 338 if (modes & MOD_STATUS) { 339 if (time_status & STA_PLL && !(ntv.status & STA_PLL)) { 340 time_state = TIME_OK; 341 time_status = STA_UNSYNC; 342 #ifdef PPS_SYNC 343 pps_shift = PPS_FAVG; 344 #endif /* PPS_SYNC */ 345 } 346 time_status &= STA_RONLY; 347 time_status |= ntv.status & ~STA_RONLY; 348 } 349 if (modes & MOD_TIMECONST) { 350 if (ntv.constant < 0) 351 time_constant = 0; 352 else if (ntv.constant > MAXTC) 353 time_constant = MAXTC; 354 else 355 time_constant = ntv.constant; 356 } 357 if (modes & MOD_TAI) { 358 if (ntv.constant > 0) /* XXX zero & negative numbers ? */ 359 time_tai = ntv.constant; 360 } 361 #ifdef PPS_SYNC 362 if (modes & MOD_PPSMAX) { 363 if (ntv.shift < PPS_FAVG) 364 pps_shiftmax = PPS_FAVG; 365 else if (ntv.shift > PPS_FAVGMAX) 366 pps_shiftmax = PPS_FAVGMAX; 367 else 368 pps_shiftmax = ntv.shift; 369 } 370 #endif /* PPS_SYNC */ 371 if (modes & MOD_NANO) 372 time_status |= STA_NANO; 373 if (modes & MOD_MICRO) 374 time_status &= ~STA_NANO; 375 if (modes & MOD_CLKB) 376 time_status |= STA_CLK; 377 if (modes & MOD_CLKA) 378 time_status &= ~STA_CLK; 379 if (modes & MOD_FREQUENCY) { 380 freq = (ntv.freq * 1000LL) >> 16; 381 if (freq > MAXFREQ) 382 L_LINT(time_freq, MAXFREQ); 383 else if (freq < -MAXFREQ) 384 L_LINT(time_freq, -MAXFREQ); 385 else { 386 /* 387 * ntv.freq is [PPM * 2^16] = [us/s * 2^16] 388 * time_freq is [ns/s * 2^32] 389 */ 390 time_freq = ntv.freq * 1000LL * 65536LL; 391 } 392 #ifdef PPS_SYNC 393 pps_freq = time_freq; 394 #endif /* PPS_SYNC */ 395 } 396 if (modes & MOD_OFFSET) { 397 if (time_status & STA_NANO) 398 hardupdate(ntv.offset); 399 else 400 hardupdate(ntv.offset * 1000); 401 } 402 403 /* 404 * Retrieve all clock variables. Note that the TAI offset is 405 * returned only by ntp_gettime(); 406 */ 407 if (time_status & STA_NANO) 408 ntv.offset = L_GINT(time_offset); 409 else 410 ntv.offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */ 411 ntv.freq = L_GINT((time_freq / 1000LL) << 16); 412 ntv.maxerror = time_maxerror; 413 ntv.esterror = time_esterror; 414 ntv.status = time_status; 415 ntv.constant = time_constant; 416 if (time_status & STA_NANO) 417 ntv.precision = time_precision; 418 else 419 ntv.precision = time_precision / 1000; 420 ntv.tolerance = MAXFREQ * SCALE_PPM; 421 #ifdef PPS_SYNC 422 ntv.shift = pps_shift; 423 ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16); 424 if (time_status & STA_NANO) 425 ntv.jitter = pps_jitter; 426 else 427 ntv.jitter = pps_jitter / 1000; 428 ntv.stabil = pps_stabil; 429 ntv.calcnt = pps_calcnt; 430 ntv.errcnt = pps_errcnt; 431 ntv.jitcnt = pps_jitcnt; 432 ntv.stbcnt = pps_stbcnt; 433 #endif /* PPS_SYNC */ 434 splx(s); 435 436 error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv)); 437 if (error) 438 goto done2; 439 440 /* 441 * Status word error decode. See comments in 442 * ntp_gettime() routine. 443 */ 444 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 445 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 446 !(time_status & STA_PPSSIGNAL)) || 447 (time_status & STA_PPSTIME && 448 time_status & STA_PPSJITTER) || 449 (time_status & STA_PPSFREQ && 450 time_status & (STA_PPSWANDER | STA_PPSERROR))) { 451 td->td_retval[0] = TIME_ERROR; 452 } else { 453 td->td_retval[0] = time_state; 454 } 455 done2: 456 mtx_unlock(&Giant); 457 return (error); 458 } 459 460 /* 461 * second_overflow() - called after ntp_tick_adjust() 462 * 463 * This routine is ordinarily called immediately following the above 464 * routine ntp_tick_adjust(). While these two routines are normally 465 * combined, they are separated here only for the purposes of 466 * simulation. 467 */ 468 void 469 ntp_update_second(int64_t *adjustment, time_t *newsec) 470 { 471 int tickrate; 472 l_fp ftemp; /* 32/64-bit temporary */ 473 474 /* 475 * On rollover of the second both the nanosecond and microsecond 476 * clocks are updated and the state machine cranked as 477 * necessary. The phase adjustment to be used for the next 478 * second is calculated and the maximum error is increased by 479 * the tolerance. 480 */ 481 time_maxerror += MAXFREQ / 1000; 482 483 /* 484 * Leap second processing. If in leap-insert state at 485 * the end of the day, the system clock is set back one 486 * second; if in leap-delete state, the system clock is 487 * set ahead one second. The nano_time() routine or 488 * external clock driver will insure that reported time 489 * is always monotonic. 490 */ 491 switch (time_state) { 492 493 /* 494 * No warning. 495 */ 496 case TIME_OK: 497 if (time_status & STA_INS) 498 time_state = TIME_INS; 499 else if (time_status & STA_DEL) 500 time_state = TIME_DEL; 501 break; 502 503 /* 504 * Insert second 23:59:60 following second 505 * 23:59:59. 506 */ 507 case TIME_INS: 508 if (!(time_status & STA_INS)) 509 time_state = TIME_OK; 510 else if ((*newsec) % 86400 == 0) { 511 (*newsec)--; 512 time_state = TIME_OOP; 513 time_tai++; 514 } 515 break; 516 517 /* 518 * Delete second 23:59:59. 519 */ 520 case TIME_DEL: 521 if (!(time_status & STA_DEL)) 522 time_state = TIME_OK; 523 else if (((*newsec) + 1) % 86400 == 0) { 524 (*newsec)++; 525 time_tai--; 526 time_state = TIME_WAIT; 527 } 528 break; 529 530 /* 531 * Insert second in progress. 532 */ 533 case TIME_OOP: 534 time_state = TIME_WAIT; 535 break; 536 537 /* 538 * Wait for status bits to clear. 539 */ 540 case TIME_WAIT: 541 if (!(time_status & (STA_INS | STA_DEL))) 542 time_state = TIME_OK; 543 } 544 545 /* 546 * Compute the total time adjustment for the next second 547 * in ns. The offset is reduced by a factor depending on 548 * whether the PPS signal is operating. Note that the 549 * value is in effect scaled by the clock frequency, 550 * since the adjustment is added at each tick interrupt. 551 */ 552 ftemp = time_offset; 553 #ifdef PPS_SYNC 554 /* XXX even if PPS signal dies we should finish adjustment ? */ 555 if (time_status & STA_PPSTIME && time_status & 556 STA_PPSSIGNAL) 557 L_RSHIFT(ftemp, pps_shift); 558 else 559 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 560 #else 561 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 562 #endif /* PPS_SYNC */ 563 time_adj = ftemp; 564 L_SUB(time_offset, ftemp); 565 L_ADD(time_adj, time_freq); 566 567 /* 568 * Apply any correction from adjtime(2). If more than one second 569 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM) 570 * until the last second is slewed the final < 500 usecs. 571 */ 572 if (time_adjtime != 0) { 573 if (time_adjtime > 1000000) 574 tickrate = 5000; 575 else if (time_adjtime < -1000000) 576 tickrate = -5000; 577 else if (time_adjtime > 500) 578 tickrate = 500; 579 else if (time_adjtime < -500) 580 tickrate = -500; 581 else 582 tickrate = time_adjtime; 583 time_adjtime -= tickrate; 584 L_LINT(ftemp, tickrate * 1000); 585 L_ADD(time_adj, ftemp); 586 } 587 *adjustment = time_adj; 588 589 #ifdef PPS_SYNC 590 if (pps_valid > 0) 591 pps_valid--; 592 else 593 time_status &= ~STA_PPSSIGNAL; 594 #endif /* PPS_SYNC */ 595 } 596 597 /* 598 * ntp_init() - initialize variables and structures 599 * 600 * This routine must be called after the kernel variables hz and tick 601 * are set or changed and before the next tick interrupt. In this 602 * particular implementation, these values are assumed set elsewhere in 603 * the kernel. The design allows the clock frequency and tick interval 604 * to be changed while the system is running. So, this routine should 605 * probably be integrated with the code that does that. 606 */ 607 static void 608 ntp_init() 609 { 610 611 /* 612 * The following variables are initialized only at startup. Only 613 * those structures not cleared by the compiler need to be 614 * initialized, and these only in the simulator. In the actual 615 * kernel, any nonzero values here will quickly evaporate. 616 */ 617 L_CLR(time_offset); 618 L_CLR(time_freq); 619 #ifdef PPS_SYNC 620 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0; 621 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0; 622 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0; 623 pps_fcount = 0; 624 L_CLR(pps_freq); 625 #endif /* PPS_SYNC */ 626 } 627 628 SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL) 629 630 /* 631 * hardupdate() - local clock update 632 * 633 * This routine is called by ntp_adjtime() to update the local clock 634 * phase and frequency. The implementation is of an adaptive-parameter, 635 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new 636 * time and frequency offset estimates for each call. If the kernel PPS 637 * discipline code is configured (PPS_SYNC), the PPS signal itself 638 * determines the new time offset, instead of the calling argument. 639 * Presumably, calls to ntp_adjtime() occur only when the caller 640 * believes the local clock is valid within some bound (+-128 ms with 641 * NTP). If the caller's time is far different than the PPS time, an 642 * argument will ensue, and it's not clear who will lose. 643 * 644 * For uncompensated quartz crystal oscillators and nominal update 645 * intervals less than 256 s, operation should be in phase-lock mode, 646 * where the loop is disciplined to phase. For update intervals greater 647 * than 1024 s, operation should be in frequency-lock mode, where the 648 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode 649 * is selected by the STA_MODE status bit. 650 */ 651 static void 652 hardupdate(offset) 653 long offset; /* clock offset (ns) */ 654 { 655 long mtemp; 656 l_fp ftemp; 657 658 /* 659 * Select how the phase is to be controlled and from which 660 * source. If the PPS signal is present and enabled to 661 * discipline the time, the PPS offset is used; otherwise, the 662 * argument offset is used. 663 */ 664 if (!(time_status & STA_PLL)) 665 return; 666 if (!(time_status & STA_PPSTIME && time_status & 667 STA_PPSSIGNAL)) { 668 if (offset > MAXPHASE) 669 time_monitor = MAXPHASE; 670 else if (offset < -MAXPHASE) 671 time_monitor = -MAXPHASE; 672 else 673 time_monitor = offset; 674 L_LINT(time_offset, time_monitor); 675 } 676 677 /* 678 * Select how the frequency is to be controlled and in which 679 * mode (PLL or FLL). If the PPS signal is present and enabled 680 * to discipline the frequency, the PPS frequency is used; 681 * otherwise, the argument offset is used to compute it. 682 */ 683 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) { 684 time_reftime = time_second; 685 return; 686 } 687 if (time_status & STA_FREQHOLD || time_reftime == 0) 688 time_reftime = time_second; 689 mtemp = time_second - time_reftime; 690 L_LINT(ftemp, time_monitor); 691 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); 692 L_MPY(ftemp, mtemp); 693 L_ADD(time_freq, ftemp); 694 time_status &= ~STA_MODE; 695 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > 696 MAXSEC)) { 697 L_LINT(ftemp, (time_monitor << 4) / mtemp); 698 L_RSHIFT(ftemp, SHIFT_FLL + 4); 699 L_ADD(time_freq, ftemp); 700 time_status |= STA_MODE; 701 } 702 time_reftime = time_second; 703 if (L_GINT(time_freq) > MAXFREQ) 704 L_LINT(time_freq, MAXFREQ); 705 else if (L_GINT(time_freq) < -MAXFREQ) 706 L_LINT(time_freq, -MAXFREQ); 707 } 708 709 #ifdef PPS_SYNC 710 /* 711 * hardpps() - discipline CPU clock oscillator to external PPS signal 712 * 713 * This routine is called at each PPS interrupt in order to discipline 714 * the CPU clock oscillator to the PPS signal. There are two independent 715 * first-order feedback loops, one for the phase, the other for the 716 * frequency. The phase loop measures and grooms the PPS phase offset 717 * and leaves it in a handy spot for the seconds overflow routine. The 718 * frequency loop averages successive PPS phase differences and 719 * calculates the PPS frequency offset, which is also processed by the 720 * seconds overflow routine. The code requires the caller to capture the 721 * time and architecture-dependent hardware counter values in 722 * nanoseconds at the on-time PPS signal transition. 723 * 724 * Note that, on some Unix systems this routine runs at an interrupt 725 * priority level higher than the timer interrupt routine hardclock(). 726 * Therefore, the variables used are distinct from the hardclock() 727 * variables, except for the actual time and frequency variables, which 728 * are determined by this routine and updated atomically. 729 */ 730 void 731 hardpps(tsp, nsec) 732 struct timespec *tsp; /* time at PPS */ 733 long nsec; /* hardware counter at PPS */ 734 { 735 long u_sec, u_nsec, v_nsec; /* temps */ 736 l_fp ftemp; 737 738 /* 739 * The signal is first processed by a range gate and frequency 740 * discriminator. The range gate rejects noise spikes outside 741 * the range +-500 us. The frequency discriminator rejects input 742 * signals with apparent frequency outside the range 1 +-500 743 * PPM. If two hits occur in the same second, we ignore the 744 * later hit; if not and a hit occurs outside the range gate, 745 * keep the later hit for later comparison, but do not process 746 * it. 747 */ 748 time_status |= STA_PPSSIGNAL | STA_PPSJITTER; 749 time_status &= ~(STA_PPSWANDER | STA_PPSERROR); 750 pps_valid = PPS_VALID; 751 u_sec = tsp->tv_sec; 752 u_nsec = tsp->tv_nsec; 753 if (u_nsec >= (NANOSECOND >> 1)) { 754 u_nsec -= NANOSECOND; 755 u_sec++; 756 } 757 v_nsec = u_nsec - pps_tf[0].tv_nsec; 758 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - 759 MAXFREQ) 760 return; 761 pps_tf[2] = pps_tf[1]; 762 pps_tf[1] = pps_tf[0]; 763 pps_tf[0].tv_sec = u_sec; 764 pps_tf[0].tv_nsec = u_nsec; 765 766 /* 767 * Compute the difference between the current and previous 768 * counter values. If the difference exceeds 0.5 s, assume it 769 * has wrapped around, so correct 1.0 s. If the result exceeds 770 * the tick interval, the sample point has crossed a tick 771 * boundary during the last second, so correct the tick. Very 772 * intricate. 773 */ 774 u_nsec = nsec; 775 if (u_nsec > (NANOSECOND >> 1)) 776 u_nsec -= NANOSECOND; 777 else if (u_nsec < -(NANOSECOND >> 1)) 778 u_nsec += NANOSECOND; 779 pps_fcount += u_nsec; 780 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) 781 return; 782 time_status &= ~STA_PPSJITTER; 783 784 /* 785 * A three-stage median filter is used to help denoise the PPS 786 * time. The median sample becomes the time offset estimate; the 787 * difference between the other two samples becomes the time 788 * dispersion (jitter) estimate. 789 */ 790 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { 791 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { 792 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ 793 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; 794 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { 795 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ 796 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; 797 } else { 798 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ 799 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; 800 } 801 } else { 802 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { 803 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ 804 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; 805 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { 806 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ 807 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; 808 } else { 809 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ 810 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; 811 } 812 } 813 814 /* 815 * Nominal jitter is due to PPS signal noise and interrupt 816 * latency. If it exceeds the popcorn threshold, the sample is 817 * discarded. otherwise, if so enabled, the time offset is 818 * updated. We can tolerate a modest loss of data here without 819 * much degrading time accuracy. 820 */ 821 if (u_nsec > (pps_jitter << PPS_POPCORN)) { 822 time_status |= STA_PPSJITTER; 823 pps_jitcnt++; 824 } else if (time_status & STA_PPSTIME) { 825 time_monitor = -v_nsec; 826 L_LINT(time_offset, time_monitor); 827 } 828 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; 829 u_sec = pps_tf[0].tv_sec - pps_lastsec; 830 if (u_sec < (1 << pps_shift)) 831 return; 832 833 /* 834 * At the end of the calibration interval the difference between 835 * the first and last counter values becomes the scaled 836 * frequency. It will later be divided by the length of the 837 * interval to determine the frequency update. If the frequency 838 * exceeds a sanity threshold, or if the actual calibration 839 * interval is not equal to the expected length, the data are 840 * discarded. We can tolerate a modest loss of data here without 841 * much degrading frequency accuracy. 842 */ 843 pps_calcnt++; 844 v_nsec = -pps_fcount; 845 pps_lastsec = pps_tf[0].tv_sec; 846 pps_fcount = 0; 847 u_nsec = MAXFREQ << pps_shift; 848 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << 849 pps_shift)) { 850 time_status |= STA_PPSERROR; 851 pps_errcnt++; 852 return; 853 } 854 855 /* 856 * Here the raw frequency offset and wander (stability) is 857 * calculated. If the wander is less than the wander threshold 858 * for four consecutive averaging intervals, the interval is 859 * doubled; if it is greater than the threshold for four 860 * consecutive intervals, the interval is halved. The scaled 861 * frequency offset is converted to frequency offset. The 862 * stability metric is calculated as the average of recent 863 * frequency changes, but is used only for performance 864 * monitoring. 865 */ 866 L_LINT(ftemp, v_nsec); 867 L_RSHIFT(ftemp, pps_shift); 868 L_SUB(ftemp, pps_freq); 869 u_nsec = L_GINT(ftemp); 870 if (u_nsec > PPS_MAXWANDER) { 871 L_LINT(ftemp, PPS_MAXWANDER); 872 pps_intcnt--; 873 time_status |= STA_PPSWANDER; 874 pps_stbcnt++; 875 } else if (u_nsec < -PPS_MAXWANDER) { 876 L_LINT(ftemp, -PPS_MAXWANDER); 877 pps_intcnt--; 878 time_status |= STA_PPSWANDER; 879 pps_stbcnt++; 880 } else { 881 pps_intcnt++; 882 } 883 if (pps_intcnt >= 4) { 884 pps_intcnt = 4; 885 if (pps_shift < pps_shiftmax) { 886 pps_shift++; 887 pps_intcnt = 0; 888 } 889 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { 890 pps_intcnt = -4; 891 if (pps_shift > PPS_FAVG) { 892 pps_shift--; 893 pps_intcnt = 0; 894 } 895 } 896 if (u_nsec < 0) 897 u_nsec = -u_nsec; 898 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; 899 900 /* 901 * The PPS frequency is recalculated and clamped to the maximum 902 * MAXFREQ. If enabled, the system clock frequency is updated as 903 * well. 904 */ 905 L_ADD(pps_freq, ftemp); 906 u_nsec = L_GINT(pps_freq); 907 if (u_nsec > MAXFREQ) 908 L_LINT(pps_freq, MAXFREQ); 909 else if (u_nsec < -MAXFREQ) 910 L_LINT(pps_freq, -MAXFREQ); 911 if (time_status & STA_PPSFREQ) 912 time_freq = pps_freq; 913 } 914 #endif /* PPS_SYNC */ 915 916 #ifndef _SYS_SYSPROTO_H_ 917 struct adjtime_args { 918 struct timeval *delta; 919 struct timeval *olddelta; 920 }; 921 #endif 922 /* 923 * MPSAFE 924 */ 925 /* ARGSUSED */ 926 int 927 adjtime(struct thread *td, struct adjtime_args *uap) 928 { 929 struct timeval atv; 930 int error; 931 932 if ((error = suser(td))) 933 return (error); 934 935 mtx_lock(&Giant); 936 if (uap->olddelta) { 937 atv.tv_sec = time_adjtime / 1000000; 938 atv.tv_usec = time_adjtime % 1000000; 939 if (atv.tv_usec < 0) { 940 atv.tv_usec += 1000000; 941 atv.tv_sec--; 942 } 943 error = copyout(&atv, uap->olddelta, sizeof(atv)); 944 if (error) 945 goto done2; 946 } 947 if (uap->delta) { 948 error = copyin(uap->delta, &atv, sizeof(atv)); 949 if (error) 950 goto done2; 951 time_adjtime = (int64_t)atv.tv_sec * 1000000 + atv.tv_usec; 952 } 953 done2: 954 mtx_unlock(&Giant); 955 return (error); 956 } 957 958