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/syscallsubr.h> 50 #include <sys/sysctl.h> 51 52 /* 53 * Single-precision macros for 64-bit machines 54 */ 55 typedef int64_t l_fp; 56 #define L_ADD(v, u) ((v) += (u)) 57 #define L_SUB(v, u) ((v) -= (u)) 58 #define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32) 59 #define L_NEG(v) ((v) = -(v)) 60 #define L_RSHIFT(v, n) \ 61 do { \ 62 if ((v) < 0) \ 63 (v) = -(-(v) >> (n)); \ 64 else \ 65 (v) = (v) >> (n); \ 66 } while (0) 67 #define L_MPY(v, a) ((v) *= (a)) 68 #define L_CLR(v) ((v) = 0) 69 #define L_ISNEG(v) ((v) < 0) 70 #define L_LINT(v, a) ((v) = (int64_t)(a) << 32) 71 #define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32) 72 73 /* 74 * Generic NTP kernel interface 75 * 76 * These routines constitute the Network Time Protocol (NTP) interfaces 77 * for user and daemon application programs. The ntp_gettime() routine 78 * provides the time, maximum error (synch distance) and estimated error 79 * (dispersion) to client user application programs. The ntp_adjtime() 80 * routine is used by the NTP daemon to adjust the system clock to an 81 * externally derived time. The time offset and related variables set by 82 * this routine are used by other routines in this module to adjust the 83 * phase and frequency of the clock discipline loop which controls the 84 * system clock. 85 * 86 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO 87 * defined), the time at each tick interrupt is derived directly from 88 * the kernel time variable. When the kernel time is reckoned in 89 * microseconds, (NTP_NANO undefined), the time is derived from the 90 * kernel time variable together with a variable representing the 91 * leftover nanoseconds at the last tick interrupt. In either case, the 92 * current nanosecond time is reckoned from these values plus an 93 * interpolated value derived by the clock routines in another 94 * architecture-specific module. The interpolation can use either a 95 * dedicated counter or a processor cycle counter (PCC) implemented in 96 * some architectures. 97 * 98 * Note that all routines must run at priority splclock or higher. 99 */ 100 /* 101 * Phase/frequency-lock loop (PLL/FLL) definitions 102 * 103 * The nanosecond clock discipline uses two variable types, time 104 * variables and frequency variables. Both types are represented as 64- 105 * bit fixed-point quantities with the decimal point between two 32-bit 106 * halves. On a 32-bit machine, each half is represented as a single 107 * word and mathematical operations are done using multiple-precision 108 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is 109 * used. 110 * 111 * A time variable is a signed 64-bit fixed-point number in ns and 112 * fraction. It represents the remaining time offset to be amortized 113 * over succeeding tick interrupts. The maximum time offset is about 114 * 0.5 s and the resolution is about 2.3e-10 ns. 115 * 116 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 117 * 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 1 118 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 119 * |s s s| ns | 120 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 121 * | fraction | 122 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 123 * 124 * A frequency variable is a signed 64-bit fixed-point number in ns/s 125 * and fraction. It represents the ns and fraction to be added to the 126 * kernel time variable at each second. The maximum frequency offset is 127 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s. 128 * 129 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 130 * 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 1 131 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 132 * |s s s s s s s s s s s s s| ns/s | 133 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 134 * | fraction | 135 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 136 */ 137 /* 138 * The following variables establish the state of the PLL/FLL and the 139 * residual time and frequency offset of the local clock. 140 */ 141 #define SHIFT_PLL 4 /* PLL loop gain (shift) */ 142 #define SHIFT_FLL 2 /* FLL loop gain (shift) */ 143 144 static int time_state = TIME_OK; /* clock state */ 145 static int time_status = STA_UNSYNC; /* clock status bits */ 146 static long time_tai; /* TAI offset (s) */ 147 static long time_monitor; /* last time offset scaled (ns) */ 148 static long time_constant; /* poll interval (shift) (s) */ 149 static long time_precision = 1; /* clock precision (ns) */ 150 static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */ 151 static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */ 152 static long time_reftime; /* time at last adjustment (s) */ 153 static l_fp time_offset; /* time offset (ns) */ 154 static l_fp time_freq; /* frequency offset (ns/s) */ 155 static l_fp time_adj; /* tick adjust (ns/s) */ 156 157 static int64_t time_adjtime; /* correction from adjtime(2) (usec) */ 158 159 #ifdef PPS_SYNC 160 /* 161 * The following variables are used when a pulse-per-second (PPS) signal 162 * is available and connected via a modem control lead. They establish 163 * the engineering parameters of the clock discipline loop when 164 * controlled by the PPS signal. 165 */ 166 #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */ 167 #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */ 168 #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */ 169 #define PPS_PAVG 4 /* phase avg interval (s) (shift) */ 170 #define PPS_VALID 120 /* PPS signal watchdog max (s) */ 171 #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */ 172 #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */ 173 174 static struct timespec pps_tf[3]; /* phase median filter */ 175 static l_fp pps_freq; /* scaled frequency offset (ns/s) */ 176 static long pps_fcount; /* frequency accumulator */ 177 static long pps_jitter; /* nominal jitter (ns) */ 178 static long pps_stabil; /* nominal stability (scaled ns/s) */ 179 static long pps_lastsec; /* time at last calibration (s) */ 180 static int pps_valid; /* signal watchdog counter */ 181 static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */ 182 static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */ 183 static int pps_intcnt; /* wander counter */ 184 185 /* 186 * PPS signal quality monitors 187 */ 188 static long pps_calcnt; /* calibration intervals */ 189 static long pps_jitcnt; /* jitter limit exceeded */ 190 static long pps_stbcnt; /* stability limit exceeded */ 191 static long pps_errcnt; /* calibration errors */ 192 #endif /* PPS_SYNC */ 193 /* 194 * End of phase/frequency-lock loop (PLL/FLL) definitions 195 */ 196 197 static void ntp_init(void); 198 static void hardupdate(long offset); 199 static void ntp_gettime1(struct ntptimeval *ntvp); 200 201 static void 202 ntp_gettime1(struct ntptimeval *ntvp) 203 { 204 struct timespec atv; /* nanosecond time */ 205 206 nanotime(&atv); 207 ntvp->time.tv_sec = atv.tv_sec; 208 ntvp->time.tv_nsec = atv.tv_nsec; 209 ntvp->maxerror = time_maxerror; 210 ntvp->esterror = time_esterror; 211 ntvp->tai = time_tai; 212 ntvp->time_state = time_state; 213 214 /* 215 * Status word error decode. If any of these conditions occur, 216 * an error is returned, instead of the status word. Most 217 * applications will care only about the fact the system clock 218 * may not be trusted, not about the details. 219 * 220 * Hardware or software error 221 */ 222 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 223 224 /* 225 * PPS signal lost when either time or frequency synchronization 226 * requested 227 */ 228 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 229 !(time_status & STA_PPSSIGNAL)) || 230 231 /* 232 * PPS jitter exceeded when time synchronization requested 233 */ 234 (time_status & STA_PPSTIME && 235 time_status & STA_PPSJITTER) || 236 237 /* 238 * PPS wander exceeded or calibration error when frequency 239 * synchronization requested 240 */ 241 (time_status & STA_PPSFREQ && 242 time_status & (STA_PPSWANDER | STA_PPSERROR))) 243 ntvp->time_state = TIME_ERROR; 244 } 245 246 /* 247 * ntp_gettime() - NTP user application interface 248 * 249 * See the timex.h header file for synopsis and API description. Note 250 * that the TAI offset is returned in the ntvtimeval.tai structure 251 * member. 252 */ 253 #ifndef _SYS_SYSPROTO_H_ 254 struct ntp_gettime_args { 255 struct ntptimeval *ntvp; 256 }; 257 #endif 258 /* ARGSUSED */ 259 int 260 ntp_gettime(struct thread *td, struct ntp_gettime_args *uap) 261 { 262 struct ntptimeval ntv; 263 264 ntp_gettime1(&ntv); 265 266 return (copyout(&ntv, uap->ntvp, sizeof(ntv))); 267 } 268 269 static int 270 ntp_sysctl(SYSCTL_HANDLER_ARGS) 271 { 272 struct ntptimeval ntv; /* temporary structure */ 273 274 ntp_gettime1(&ntv); 275 276 return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req)); 277 } 278 279 SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, ""); 280 SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD, 281 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", ""); 282 283 #ifdef PPS_SYNC 284 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, &pps_shiftmax, 0, ""); 285 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, &pps_shift, 0, ""); 286 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, &time_monitor, 0, ""); 287 288 SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD, &pps_freq, sizeof(pps_freq), "I", ""); 289 SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD, &time_freq, sizeof(time_freq), "I", ""); 290 #endif 291 /* 292 * ntp_adjtime() - NTP daemon application interface 293 * 294 * See the timex.h header file for synopsis and API description. Note 295 * that the timex.constant structure member has a dual purpose to set 296 * the time constant and to set the TAI offset. 297 */ 298 #ifndef _SYS_SYSPROTO_H_ 299 struct ntp_adjtime_args { 300 struct timex *tp; 301 }; 302 #endif 303 304 /* 305 * MPSAFE 306 */ 307 int 308 ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap) 309 { 310 struct timex ntv; /* temporary structure */ 311 long freq; /* frequency ns/s) */ 312 int modes; /* mode bits from structure */ 313 int s; /* caller priority */ 314 int error; 315 316 error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv)); 317 if (error) 318 return(error); 319 320 /* 321 * Update selected clock variables - only the superuser can 322 * change anything. Note that there is no error checking here on 323 * the assumption the superuser should know what it is doing. 324 * Note that either the time constant or TAI offset are loaded 325 * from the ntv.constant member, depending on the mode bits. If 326 * the STA_PLL bit in the status word is cleared, the state and 327 * status words are reset to the initial values at boot. 328 */ 329 mtx_lock(&Giant); 330 modes = ntv.modes; 331 if (modes) 332 error = suser(td); 333 if (error) 334 goto done2; 335 s = splclock(); 336 if (modes & MOD_MAXERROR) 337 time_maxerror = ntv.maxerror; 338 if (modes & MOD_ESTERROR) 339 time_esterror = ntv.esterror; 340 if (modes & MOD_STATUS) { 341 if (time_status & STA_PLL && !(ntv.status & STA_PLL)) { 342 time_state = TIME_OK; 343 time_status = STA_UNSYNC; 344 #ifdef PPS_SYNC 345 pps_shift = PPS_FAVG; 346 #endif /* PPS_SYNC */ 347 } 348 time_status &= STA_RONLY; 349 time_status |= ntv.status & ~STA_RONLY; 350 } 351 if (modes & MOD_TIMECONST) { 352 if (ntv.constant < 0) 353 time_constant = 0; 354 else if (ntv.constant > MAXTC) 355 time_constant = MAXTC; 356 else 357 time_constant = ntv.constant; 358 } 359 if (modes & MOD_TAI) { 360 if (ntv.constant > 0) /* XXX zero & negative numbers ? */ 361 time_tai = ntv.constant; 362 } 363 #ifdef PPS_SYNC 364 if (modes & MOD_PPSMAX) { 365 if (ntv.shift < PPS_FAVG) 366 pps_shiftmax = PPS_FAVG; 367 else if (ntv.shift > PPS_FAVGMAX) 368 pps_shiftmax = PPS_FAVGMAX; 369 else 370 pps_shiftmax = ntv.shift; 371 } 372 #endif /* PPS_SYNC */ 373 if (modes & MOD_NANO) 374 time_status |= STA_NANO; 375 if (modes & MOD_MICRO) 376 time_status &= ~STA_NANO; 377 if (modes & MOD_CLKB) 378 time_status |= STA_CLK; 379 if (modes & MOD_CLKA) 380 time_status &= ~STA_CLK; 381 if (modes & MOD_FREQUENCY) { 382 freq = (ntv.freq * 1000LL) >> 16; 383 if (freq > MAXFREQ) 384 L_LINT(time_freq, MAXFREQ); 385 else if (freq < -MAXFREQ) 386 L_LINT(time_freq, -MAXFREQ); 387 else { 388 /* 389 * ntv.freq is [PPM * 2^16] = [us/s * 2^16] 390 * time_freq is [ns/s * 2^32] 391 */ 392 time_freq = ntv.freq * 1000LL * 65536LL; 393 } 394 #ifdef PPS_SYNC 395 pps_freq = time_freq; 396 #endif /* PPS_SYNC */ 397 } 398 if (modes & MOD_OFFSET) { 399 if (time_status & STA_NANO) 400 hardupdate(ntv.offset); 401 else 402 hardupdate(ntv.offset * 1000); 403 } 404 405 /* 406 * Retrieve all clock variables. Note that the TAI offset is 407 * returned only by ntp_gettime(); 408 */ 409 if (time_status & STA_NANO) 410 ntv.offset = L_GINT(time_offset); 411 else 412 ntv.offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */ 413 ntv.freq = L_GINT((time_freq / 1000LL) << 16); 414 ntv.maxerror = time_maxerror; 415 ntv.esterror = time_esterror; 416 ntv.status = time_status; 417 ntv.constant = time_constant; 418 if (time_status & STA_NANO) 419 ntv.precision = time_precision; 420 else 421 ntv.precision = time_precision / 1000; 422 ntv.tolerance = MAXFREQ * SCALE_PPM; 423 #ifdef PPS_SYNC 424 ntv.shift = pps_shift; 425 ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16); 426 if (time_status & STA_NANO) 427 ntv.jitter = pps_jitter; 428 else 429 ntv.jitter = pps_jitter / 1000; 430 ntv.stabil = pps_stabil; 431 ntv.calcnt = pps_calcnt; 432 ntv.errcnt = pps_errcnt; 433 ntv.jitcnt = pps_jitcnt; 434 ntv.stbcnt = pps_stbcnt; 435 #endif /* PPS_SYNC */ 436 splx(s); 437 438 error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv)); 439 if (error) 440 goto done2; 441 442 /* 443 * Status word error decode. See comments in 444 * ntp_gettime() routine. 445 */ 446 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 447 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 448 !(time_status & STA_PPSSIGNAL)) || 449 (time_status & STA_PPSTIME && 450 time_status & STA_PPSJITTER) || 451 (time_status & STA_PPSFREQ && 452 time_status & (STA_PPSWANDER | STA_PPSERROR))) { 453 td->td_retval[0] = TIME_ERROR; 454 } else { 455 td->td_retval[0] = time_state; 456 } 457 done2: 458 mtx_unlock(&Giant); 459 return (error); 460 } 461 462 /* 463 * second_overflow() - called after ntp_tick_adjust() 464 * 465 * This routine is ordinarily called immediately following the above 466 * routine ntp_tick_adjust(). While these two routines are normally 467 * combined, they are separated here only for the purposes of 468 * simulation. 469 */ 470 void 471 ntp_update_second(int64_t *adjustment, time_t *newsec) 472 { 473 int tickrate; 474 l_fp ftemp; /* 32/64-bit temporary */ 475 476 /* 477 * On rollover of the second both the nanosecond and microsecond 478 * clocks are updated and the state machine cranked as 479 * necessary. The phase adjustment to be used for the next 480 * second is calculated and the maximum error is increased by 481 * the tolerance. 482 */ 483 time_maxerror += MAXFREQ / 1000; 484 485 /* 486 * Leap second processing. If in leap-insert state at 487 * the end of the day, the system clock is set back one 488 * second; if in leap-delete state, the system clock is 489 * set ahead one second. The nano_time() routine or 490 * external clock driver will insure that reported time 491 * is always monotonic. 492 */ 493 switch (time_state) { 494 495 /* 496 * No warning. 497 */ 498 case TIME_OK: 499 if (time_status & STA_INS) 500 time_state = TIME_INS; 501 else if (time_status & STA_DEL) 502 time_state = TIME_DEL; 503 break; 504 505 /* 506 * Insert second 23:59:60 following second 507 * 23:59:59. 508 */ 509 case TIME_INS: 510 if (!(time_status & STA_INS)) 511 time_state = TIME_OK; 512 else if ((*newsec) % 86400 == 0) { 513 (*newsec)--; 514 time_state = TIME_OOP; 515 time_tai++; 516 } 517 break; 518 519 /* 520 * Delete second 23:59:59. 521 */ 522 case TIME_DEL: 523 if (!(time_status & STA_DEL)) 524 time_state = TIME_OK; 525 else if (((*newsec) + 1) % 86400 == 0) { 526 (*newsec)++; 527 time_tai--; 528 time_state = TIME_WAIT; 529 } 530 break; 531 532 /* 533 * Insert second in progress. 534 */ 535 case TIME_OOP: 536 time_state = TIME_WAIT; 537 break; 538 539 /* 540 * Wait for status bits to clear. 541 */ 542 case TIME_WAIT: 543 if (!(time_status & (STA_INS | STA_DEL))) 544 time_state = TIME_OK; 545 } 546 547 /* 548 * Compute the total time adjustment for the next second 549 * in ns. The offset is reduced by a factor depending on 550 * whether the PPS signal is operating. Note that the 551 * value is in effect scaled by the clock frequency, 552 * since the adjustment is added at each tick interrupt. 553 */ 554 ftemp = time_offset; 555 #ifdef PPS_SYNC 556 /* XXX even if PPS signal dies we should finish adjustment ? */ 557 if (time_status & STA_PPSTIME && time_status & 558 STA_PPSSIGNAL) 559 L_RSHIFT(ftemp, pps_shift); 560 else 561 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 562 #else 563 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 564 #endif /* PPS_SYNC */ 565 time_adj = ftemp; 566 L_SUB(time_offset, ftemp); 567 L_ADD(time_adj, time_freq); 568 569 /* 570 * Apply any correction from adjtime(2). If more than one second 571 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM) 572 * until the last second is slewed the final < 500 usecs. 573 */ 574 if (time_adjtime != 0) { 575 if (time_adjtime > 1000000) 576 tickrate = 5000; 577 else if (time_adjtime < -1000000) 578 tickrate = -5000; 579 else if (time_adjtime > 500) 580 tickrate = 500; 581 else if (time_adjtime < -500) 582 tickrate = -500; 583 else 584 tickrate = time_adjtime; 585 time_adjtime -= tickrate; 586 L_LINT(ftemp, tickrate * 1000); 587 L_ADD(time_adj, ftemp); 588 } 589 *adjustment = time_adj; 590 591 #ifdef PPS_SYNC 592 if (pps_valid > 0) 593 pps_valid--; 594 else 595 time_status &= ~STA_PPSSIGNAL; 596 #endif /* PPS_SYNC */ 597 } 598 599 /* 600 * ntp_init() - initialize variables and structures 601 * 602 * This routine must be called after the kernel variables hz and tick 603 * are set or changed and before the next tick interrupt. In this 604 * particular implementation, these values are assumed set elsewhere in 605 * the kernel. The design allows the clock frequency and tick interval 606 * to be changed while the system is running. So, this routine should 607 * probably be integrated with the code that does that. 608 */ 609 static void 610 ntp_init() 611 { 612 613 /* 614 * The following variables are initialized only at startup. Only 615 * those structures not cleared by the compiler need to be 616 * initialized, and these only in the simulator. In the actual 617 * kernel, any nonzero values here will quickly evaporate. 618 */ 619 L_CLR(time_offset); 620 L_CLR(time_freq); 621 #ifdef PPS_SYNC 622 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0; 623 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0; 624 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0; 625 pps_fcount = 0; 626 L_CLR(pps_freq); 627 #endif /* PPS_SYNC */ 628 } 629 630 SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL) 631 632 /* 633 * hardupdate() - local clock update 634 * 635 * This routine is called by ntp_adjtime() to update the local clock 636 * phase and frequency. The implementation is of an adaptive-parameter, 637 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new 638 * time and frequency offset estimates for each call. If the kernel PPS 639 * discipline code is configured (PPS_SYNC), the PPS signal itself 640 * determines the new time offset, instead of the calling argument. 641 * Presumably, calls to ntp_adjtime() occur only when the caller 642 * believes the local clock is valid within some bound (+-128 ms with 643 * NTP). If the caller's time is far different than the PPS time, an 644 * argument will ensue, and it's not clear who will lose. 645 * 646 * For uncompensated quartz crystal oscillators and nominal update 647 * intervals less than 256 s, operation should be in phase-lock mode, 648 * where the loop is disciplined to phase. For update intervals greater 649 * than 1024 s, operation should be in frequency-lock mode, where the 650 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode 651 * is selected by the STA_MODE status bit. 652 */ 653 static void 654 hardupdate(offset) 655 long offset; /* clock offset (ns) */ 656 { 657 long mtemp; 658 l_fp ftemp; 659 660 /* 661 * Select how the phase is to be controlled and from which 662 * source. If the PPS signal is present and enabled to 663 * discipline the time, the PPS offset is used; otherwise, the 664 * argument offset is used. 665 */ 666 if (!(time_status & STA_PLL)) 667 return; 668 if (!(time_status & STA_PPSTIME && time_status & 669 STA_PPSSIGNAL)) { 670 if (offset > MAXPHASE) 671 time_monitor = MAXPHASE; 672 else if (offset < -MAXPHASE) 673 time_monitor = -MAXPHASE; 674 else 675 time_monitor = offset; 676 L_LINT(time_offset, time_monitor); 677 } 678 679 /* 680 * Select how the frequency is to be controlled and in which 681 * mode (PLL or FLL). If the PPS signal is present and enabled 682 * to discipline the frequency, the PPS frequency is used; 683 * otherwise, the argument offset is used to compute it. 684 */ 685 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) { 686 time_reftime = time_second; 687 return; 688 } 689 if (time_status & STA_FREQHOLD || time_reftime == 0) 690 time_reftime = time_second; 691 mtemp = time_second - time_reftime; 692 L_LINT(ftemp, time_monitor); 693 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); 694 L_MPY(ftemp, mtemp); 695 L_ADD(time_freq, ftemp); 696 time_status &= ~STA_MODE; 697 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > 698 MAXSEC)) { 699 L_LINT(ftemp, (time_monitor << 4) / mtemp); 700 L_RSHIFT(ftemp, SHIFT_FLL + 4); 701 L_ADD(time_freq, ftemp); 702 time_status |= STA_MODE; 703 } 704 time_reftime = time_second; 705 if (L_GINT(time_freq) > MAXFREQ) 706 L_LINT(time_freq, MAXFREQ); 707 else if (L_GINT(time_freq) < -MAXFREQ) 708 L_LINT(time_freq, -MAXFREQ); 709 } 710 711 #ifdef PPS_SYNC 712 /* 713 * hardpps() - discipline CPU clock oscillator to external PPS signal 714 * 715 * This routine is called at each PPS interrupt in order to discipline 716 * the CPU clock oscillator to the PPS signal. There are two independent 717 * first-order feedback loops, one for the phase, the other for the 718 * frequency. The phase loop measures and grooms the PPS phase offset 719 * and leaves it in a handy spot for the seconds overflow routine. The 720 * frequency loop averages successive PPS phase differences and 721 * calculates the PPS frequency offset, which is also processed by the 722 * seconds overflow routine. The code requires the caller to capture the 723 * time and architecture-dependent hardware counter values in 724 * nanoseconds at the on-time PPS signal transition. 725 * 726 * Note that, on some Unix systems this routine runs at an interrupt 727 * priority level higher than the timer interrupt routine hardclock(). 728 * Therefore, the variables used are distinct from the hardclock() 729 * variables, except for the actual time and frequency variables, which 730 * are determined by this routine and updated atomically. 731 */ 732 void 733 hardpps(tsp, nsec) 734 struct timespec *tsp; /* time at PPS */ 735 long nsec; /* hardware counter at PPS */ 736 { 737 long u_sec, u_nsec, v_nsec; /* temps */ 738 l_fp ftemp; 739 740 /* 741 * The signal is first processed by a range gate and frequency 742 * discriminator. The range gate rejects noise spikes outside 743 * the range +-500 us. The frequency discriminator rejects input 744 * signals with apparent frequency outside the range 1 +-500 745 * PPM. If two hits occur in the same second, we ignore the 746 * later hit; if not and a hit occurs outside the range gate, 747 * keep the later hit for later comparison, but do not process 748 * it. 749 */ 750 time_status |= STA_PPSSIGNAL | STA_PPSJITTER; 751 time_status &= ~(STA_PPSWANDER | STA_PPSERROR); 752 pps_valid = PPS_VALID; 753 u_sec = tsp->tv_sec; 754 u_nsec = tsp->tv_nsec; 755 if (u_nsec >= (NANOSECOND >> 1)) { 756 u_nsec -= NANOSECOND; 757 u_sec++; 758 } 759 v_nsec = u_nsec - pps_tf[0].tv_nsec; 760 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - 761 MAXFREQ) 762 return; 763 pps_tf[2] = pps_tf[1]; 764 pps_tf[1] = pps_tf[0]; 765 pps_tf[0].tv_sec = u_sec; 766 pps_tf[0].tv_nsec = u_nsec; 767 768 /* 769 * Compute the difference between the current and previous 770 * counter values. If the difference exceeds 0.5 s, assume it 771 * has wrapped around, so correct 1.0 s. If the result exceeds 772 * the tick interval, the sample point has crossed a tick 773 * boundary during the last second, so correct the tick. Very 774 * intricate. 775 */ 776 u_nsec = nsec; 777 if (u_nsec > (NANOSECOND >> 1)) 778 u_nsec -= NANOSECOND; 779 else if (u_nsec < -(NANOSECOND >> 1)) 780 u_nsec += NANOSECOND; 781 pps_fcount += u_nsec; 782 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) 783 return; 784 time_status &= ~STA_PPSJITTER; 785 786 /* 787 * A three-stage median filter is used to help denoise the PPS 788 * time. The median sample becomes the time offset estimate; the 789 * difference between the other two samples becomes the time 790 * dispersion (jitter) estimate. 791 */ 792 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { 793 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { 794 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ 795 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; 796 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { 797 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ 798 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; 799 } else { 800 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ 801 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; 802 } 803 } else { 804 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { 805 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ 806 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; 807 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { 808 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ 809 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; 810 } else { 811 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ 812 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; 813 } 814 } 815 816 /* 817 * Nominal jitter is due to PPS signal noise and interrupt 818 * latency. If it exceeds the popcorn threshold, the sample is 819 * discarded. otherwise, if so enabled, the time offset is 820 * updated. We can tolerate a modest loss of data here without 821 * much degrading time accuracy. 822 */ 823 if (u_nsec > (pps_jitter << PPS_POPCORN)) { 824 time_status |= STA_PPSJITTER; 825 pps_jitcnt++; 826 } else if (time_status & STA_PPSTIME) { 827 time_monitor = -v_nsec; 828 L_LINT(time_offset, time_monitor); 829 } 830 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; 831 u_sec = pps_tf[0].tv_sec - pps_lastsec; 832 if (u_sec < (1 << pps_shift)) 833 return; 834 835 /* 836 * At the end of the calibration interval the difference between 837 * the first and last counter values becomes the scaled 838 * frequency. It will later be divided by the length of the 839 * interval to determine the frequency update. If the frequency 840 * exceeds a sanity threshold, or if the actual calibration 841 * interval is not equal to the expected length, the data are 842 * discarded. We can tolerate a modest loss of data here without 843 * much degrading frequency accuracy. 844 */ 845 pps_calcnt++; 846 v_nsec = -pps_fcount; 847 pps_lastsec = pps_tf[0].tv_sec; 848 pps_fcount = 0; 849 u_nsec = MAXFREQ << pps_shift; 850 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << 851 pps_shift)) { 852 time_status |= STA_PPSERROR; 853 pps_errcnt++; 854 return; 855 } 856 857 /* 858 * Here the raw frequency offset and wander (stability) is 859 * calculated. If the wander is less than the wander threshold 860 * for four consecutive averaging intervals, the interval is 861 * doubled; if it is greater than the threshold for four 862 * consecutive intervals, the interval is halved. The scaled 863 * frequency offset is converted to frequency offset. The 864 * stability metric is calculated as the average of recent 865 * frequency changes, but is used only for performance 866 * monitoring. 867 */ 868 L_LINT(ftemp, v_nsec); 869 L_RSHIFT(ftemp, pps_shift); 870 L_SUB(ftemp, pps_freq); 871 u_nsec = L_GINT(ftemp); 872 if (u_nsec > PPS_MAXWANDER) { 873 L_LINT(ftemp, PPS_MAXWANDER); 874 pps_intcnt--; 875 time_status |= STA_PPSWANDER; 876 pps_stbcnt++; 877 } else if (u_nsec < -PPS_MAXWANDER) { 878 L_LINT(ftemp, -PPS_MAXWANDER); 879 pps_intcnt--; 880 time_status |= STA_PPSWANDER; 881 pps_stbcnt++; 882 } else { 883 pps_intcnt++; 884 } 885 if (pps_intcnt >= 4) { 886 pps_intcnt = 4; 887 if (pps_shift < pps_shiftmax) { 888 pps_shift++; 889 pps_intcnt = 0; 890 } 891 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { 892 pps_intcnt = -4; 893 if (pps_shift > PPS_FAVG) { 894 pps_shift--; 895 pps_intcnt = 0; 896 } 897 } 898 if (u_nsec < 0) 899 u_nsec = -u_nsec; 900 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; 901 902 /* 903 * The PPS frequency is recalculated and clamped to the maximum 904 * MAXFREQ. If enabled, the system clock frequency is updated as 905 * well. 906 */ 907 L_ADD(pps_freq, ftemp); 908 u_nsec = L_GINT(pps_freq); 909 if (u_nsec > MAXFREQ) 910 L_LINT(pps_freq, MAXFREQ); 911 else if (u_nsec < -MAXFREQ) 912 L_LINT(pps_freq, -MAXFREQ); 913 if (time_status & STA_PPSFREQ) 914 time_freq = pps_freq; 915 } 916 #endif /* PPS_SYNC */ 917 918 #ifndef _SYS_SYSPROTO_H_ 919 struct adjtime_args { 920 struct timeval *delta; 921 struct timeval *olddelta; 922 }; 923 #endif 924 /* 925 * MPSAFE 926 */ 927 /* ARGSUSED */ 928 int 929 adjtime(struct thread *td, struct adjtime_args *uap) 930 { 931 struct timeval delta, olddelta, *deltap; 932 int error; 933 934 if (uap->delta) { 935 error = copyin(uap->delta, &delta, sizeof(delta)); 936 if (error) 937 return (error); 938 deltap = δ 939 } else 940 deltap = NULL; 941 error = kern_adjtime(td, deltap, &olddelta); 942 if (uap->olddelta && error == 0) 943 error = copyout(&olddelta, uap->olddelta, sizeof(olddelta)); 944 return (error); 945 } 946 947 int 948 kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta) 949 { 950 struct timeval atv; 951 int error; 952 953 if ((error = suser(td))) 954 return (error); 955 956 mtx_lock(&Giant); 957 if (olddelta) { 958 atv.tv_sec = time_adjtime / 1000000; 959 atv.tv_usec = time_adjtime % 1000000; 960 if (atv.tv_usec < 0) { 961 atv.tv_usec += 1000000; 962 atv.tv_sec--; 963 } 964 *olddelta = atv; 965 } 966 if (delta) 967 time_adjtime = (int64_t)delta->tv_sec * 1000000 + 968 delta->tv_usec; 969 mtx_unlock(&Giant); 970 return (error); 971 } 972 973