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/priv.h> 43 #include <sys/proc.h> 44 #include <sys/lock.h> 45 #include <sys/mutex.h> 46 #include <sys/time.h> 47 #include <sys/timex.h> 48 #include <sys/timetc.h> 49 #include <sys/timepps.h> 50 #include <sys/syscallsubr.h> 51 #include <sys/sysctl.h> 52 53 /* 54 * Single-precision macros for 64-bit machines 55 */ 56 typedef int64_t l_fp; 57 #define L_ADD(v, u) ((v) += (u)) 58 #define L_SUB(v, u) ((v) -= (u)) 59 #define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32) 60 #define L_NEG(v) ((v) = -(v)) 61 #define L_RSHIFT(v, n) \ 62 do { \ 63 if ((v) < 0) \ 64 (v) = -(-(v) >> (n)); \ 65 else \ 66 (v) = (v) >> (n); \ 67 } while (0) 68 #define L_MPY(v, a) ((v) *= (a)) 69 #define L_CLR(v) ((v) = 0) 70 #define L_ISNEG(v) ((v) < 0) 71 #define L_LINT(v, a) ((v) = (int64_t)(a) << 32) 72 #define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32) 73 74 /* 75 * Generic NTP kernel interface 76 * 77 * These routines constitute the Network Time Protocol (NTP) interfaces 78 * for user and daemon application programs. The ntp_gettime() routine 79 * provides the time, maximum error (synch distance) and estimated error 80 * (dispersion) to client user application programs. The ntp_adjtime() 81 * routine is used by the NTP daemon to adjust the system clock to an 82 * externally derived time. The time offset and related variables set by 83 * this routine are used by other routines in this module to adjust the 84 * phase and frequency of the clock discipline loop which controls the 85 * system clock. 86 * 87 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO 88 * defined), the time at each tick interrupt is derived directly from 89 * the kernel time variable. When the kernel time is reckoned in 90 * microseconds, (NTP_NANO undefined), the time is derived from the 91 * kernel time variable together with a variable representing the 92 * leftover nanoseconds at the last tick interrupt. In either case, the 93 * current nanosecond time is reckoned from these values plus an 94 * interpolated value derived by the clock routines in another 95 * architecture-specific module. The interpolation can use either a 96 * dedicated counter or a processor cycle counter (PCC) implemented in 97 * some architectures. 98 * 99 * Note that all routines must run at priority splclock or higher. 100 */ 101 /* 102 * Phase/frequency-lock loop (PLL/FLL) definitions 103 * 104 * The nanosecond clock discipline uses two variable types, time 105 * variables and frequency variables. Both types are represented as 64- 106 * bit fixed-point quantities with the decimal point between two 32-bit 107 * halves. On a 32-bit machine, each half is represented as a single 108 * word and mathematical operations are done using multiple-precision 109 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is 110 * used. 111 * 112 * A time variable is a signed 64-bit fixed-point number in ns and 113 * fraction. It represents the remaining time offset to be amortized 114 * over succeeding tick interrupts. The maximum time offset is about 115 * 0.5 s and the resolution is about 2.3e-10 ns. 116 * 117 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 118 * 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 1 119 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 120 * |s s s| ns | 121 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 122 * | fraction | 123 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 124 * 125 * A frequency variable is a signed 64-bit fixed-point number in ns/s 126 * and fraction. It represents the ns and fraction to be added to the 127 * kernel time variable at each second. The maximum frequency offset is 128 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s. 129 * 130 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 131 * 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 1 132 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 133 * |s s s s s s s s s s s s s| ns/s | 134 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 * | fraction | 136 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 137 */ 138 /* 139 * The following variables establish the state of the PLL/FLL and the 140 * residual time and frequency offset of the local clock. 141 */ 142 #define SHIFT_PLL 4 /* PLL loop gain (shift) */ 143 #define SHIFT_FLL 2 /* FLL loop gain (shift) */ 144 145 static int time_state = TIME_OK; /* clock state */ 146 static int time_status = STA_UNSYNC; /* clock status bits */ 147 static long time_tai; /* TAI offset (s) */ 148 static long time_monitor; /* last time offset scaled (ns) */ 149 static long time_constant; /* poll interval (shift) (s) */ 150 static long time_precision = 1; /* clock precision (ns) */ 151 static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */ 152 static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */ 153 static long time_reftime; /* time at last adjustment (s) */ 154 static l_fp time_offset; /* time offset (ns) */ 155 static l_fp time_freq; /* frequency offset (ns/s) */ 156 static l_fp time_adj; /* tick adjust (ns/s) */ 157 158 static int64_t time_adjtime; /* correction from adjtime(2) (usec) */ 159 160 #ifdef PPS_SYNC 161 /* 162 * The following variables are used when a pulse-per-second (PPS) signal 163 * is available and connected via a modem control lead. They establish 164 * the engineering parameters of the clock discipline loop when 165 * controlled by the PPS signal. 166 */ 167 #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */ 168 #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */ 169 #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */ 170 #define PPS_PAVG 4 /* phase avg interval (s) (shift) */ 171 #define PPS_VALID 120 /* PPS signal watchdog max (s) */ 172 #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */ 173 #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */ 174 175 static struct timespec pps_tf[3]; /* phase median filter */ 176 static l_fp pps_freq; /* scaled frequency offset (ns/s) */ 177 static long pps_fcount; /* frequency accumulator */ 178 static long pps_jitter; /* nominal jitter (ns) */ 179 static long pps_stabil; /* nominal stability (scaled ns/s) */ 180 static long pps_lastsec; /* time at last calibration (s) */ 181 static int pps_valid; /* signal watchdog counter */ 182 static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */ 183 static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */ 184 static int pps_intcnt; /* wander counter */ 185 186 /* 187 * PPS signal quality monitors 188 */ 189 static long pps_calcnt; /* calibration intervals */ 190 static long pps_jitcnt; /* jitter limit exceeded */ 191 static long pps_stbcnt; /* stability limit exceeded */ 192 static long pps_errcnt; /* calibration errors */ 193 #endif /* PPS_SYNC */ 194 /* 195 * End of phase/frequency-lock loop (PLL/FLL) definitions 196 */ 197 198 static void ntp_init(void); 199 static void hardupdate(long offset); 200 static void ntp_gettime1(struct ntptimeval *ntvp); 201 202 static void 203 ntp_gettime1(struct ntptimeval *ntvp) 204 { 205 struct timespec atv; /* nanosecond time */ 206 207 GIANT_REQUIRED; 208 209 nanotime(&atv); 210 ntvp->time.tv_sec = atv.tv_sec; 211 ntvp->time.tv_nsec = atv.tv_nsec; 212 ntvp->maxerror = time_maxerror; 213 ntvp->esterror = time_esterror; 214 ntvp->tai = time_tai; 215 ntvp->time_state = time_state; 216 217 /* 218 * Status word error decode. If any of these conditions occur, 219 * an error is returned, instead of the status word. Most 220 * applications will care only about the fact the system clock 221 * may not be trusted, not about the details. 222 * 223 * Hardware or software error 224 */ 225 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 226 227 /* 228 * PPS signal lost when either time or frequency synchronization 229 * requested 230 */ 231 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 232 !(time_status & STA_PPSSIGNAL)) || 233 234 /* 235 * PPS jitter exceeded when time synchronization requested 236 */ 237 (time_status & STA_PPSTIME && 238 time_status & STA_PPSJITTER) || 239 240 /* 241 * PPS wander exceeded or calibration error when frequency 242 * synchronization requested 243 */ 244 (time_status & STA_PPSFREQ && 245 time_status & (STA_PPSWANDER | STA_PPSERROR))) 246 ntvp->time_state = TIME_ERROR; 247 } 248 249 /* 250 * ntp_gettime() - NTP user application interface 251 * 252 * See the timex.h header file for synopsis and API description. Note 253 * that the TAI offset is returned in the ntvtimeval.tai structure 254 * member. 255 */ 256 #ifndef _SYS_SYSPROTO_H_ 257 struct ntp_gettime_args { 258 struct ntptimeval *ntvp; 259 }; 260 #endif 261 /* ARGSUSED */ 262 int 263 ntp_gettime(struct thread *td, struct ntp_gettime_args *uap) 264 { 265 struct ntptimeval ntv; 266 267 mtx_lock(&Giant); 268 ntp_gettime1(&ntv); 269 mtx_unlock(&Giant); 270 271 td->td_retval[0] = ntv.time_state; 272 return (copyout(&ntv, uap->ntvp, sizeof(ntv))); 273 } 274 275 static int 276 ntp_sysctl(SYSCTL_HANDLER_ARGS) 277 { 278 struct ntptimeval ntv; /* temporary structure */ 279 280 ntp_gettime1(&ntv); 281 282 return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req)); 283 } 284 285 SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, ""); 286 SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD, 287 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", ""); 288 289 #ifdef PPS_SYNC 290 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW, &pps_shiftmax, 0, ""); 291 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW, &pps_shift, 0, ""); 292 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD, &time_monitor, 0, ""); 293 294 SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD, &pps_freq, sizeof(pps_freq), "I", ""); 295 SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD, &time_freq, sizeof(time_freq), "I", ""); 296 #endif 297 /* 298 * ntp_adjtime() - NTP daemon application interface 299 * 300 * See the timex.h header file for synopsis and API description. Note 301 * that the timex.constant structure member has a dual purpose to set 302 * the time constant and to set the TAI offset. 303 */ 304 #ifndef _SYS_SYSPROTO_H_ 305 struct ntp_adjtime_args { 306 struct timex *tp; 307 }; 308 #endif 309 310 /* 311 * MPSAFE 312 */ 313 int 314 ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap) 315 { 316 struct timex ntv; /* temporary structure */ 317 long freq; /* frequency ns/s) */ 318 int modes; /* mode bits from structure */ 319 int s; /* caller priority */ 320 int error; 321 322 error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv)); 323 if (error) 324 return(error); 325 326 /* 327 * Update selected clock variables - only the superuser can 328 * change anything. Note that there is no error checking here on 329 * the assumption the superuser should know what it is doing. 330 * Note that either the time constant or TAI offset are loaded 331 * from the ntv.constant member, depending on the mode bits. If 332 * the STA_PLL bit in the status word is cleared, the state and 333 * status words are reset to the initial values at boot. 334 */ 335 mtx_lock(&Giant); 336 modes = ntv.modes; 337 if (modes) 338 error = priv_check(td, PRIV_NTP_ADJTIME); 339 if (error) 340 goto done2; 341 s = splclock(); 342 if (modes & MOD_MAXERROR) 343 time_maxerror = ntv.maxerror; 344 if (modes & MOD_ESTERROR) 345 time_esterror = ntv.esterror; 346 if (modes & MOD_STATUS) { 347 if (time_status & STA_PLL && !(ntv.status & STA_PLL)) { 348 time_state = TIME_OK; 349 time_status = STA_UNSYNC; 350 #ifdef PPS_SYNC 351 pps_shift = PPS_FAVG; 352 #endif /* PPS_SYNC */ 353 } 354 time_status &= STA_RONLY; 355 time_status |= ntv.status & ~STA_RONLY; 356 } 357 if (modes & MOD_TIMECONST) { 358 if (ntv.constant < 0) 359 time_constant = 0; 360 else if (ntv.constant > MAXTC) 361 time_constant = MAXTC; 362 else 363 time_constant = ntv.constant; 364 } 365 if (modes & MOD_TAI) { 366 if (ntv.constant > 0) /* XXX zero & negative numbers ? */ 367 time_tai = ntv.constant; 368 } 369 #ifdef PPS_SYNC 370 if (modes & MOD_PPSMAX) { 371 if (ntv.shift < PPS_FAVG) 372 pps_shiftmax = PPS_FAVG; 373 else if (ntv.shift > PPS_FAVGMAX) 374 pps_shiftmax = PPS_FAVGMAX; 375 else 376 pps_shiftmax = ntv.shift; 377 } 378 #endif /* PPS_SYNC */ 379 if (modes & MOD_NANO) 380 time_status |= STA_NANO; 381 if (modes & MOD_MICRO) 382 time_status &= ~STA_NANO; 383 if (modes & MOD_CLKB) 384 time_status |= STA_CLK; 385 if (modes & MOD_CLKA) 386 time_status &= ~STA_CLK; 387 if (modes & MOD_FREQUENCY) { 388 freq = (ntv.freq * 1000LL) >> 16; 389 if (freq > MAXFREQ) 390 L_LINT(time_freq, MAXFREQ); 391 else if (freq < -MAXFREQ) 392 L_LINT(time_freq, -MAXFREQ); 393 else { 394 /* 395 * ntv.freq is [PPM * 2^16] = [us/s * 2^16] 396 * time_freq is [ns/s * 2^32] 397 */ 398 time_freq = ntv.freq * 1000LL * 65536LL; 399 } 400 #ifdef PPS_SYNC 401 pps_freq = time_freq; 402 #endif /* PPS_SYNC */ 403 } 404 if (modes & MOD_OFFSET) { 405 if (time_status & STA_NANO) 406 hardupdate(ntv.offset); 407 else 408 hardupdate(ntv.offset * 1000); 409 } 410 411 /* 412 * Retrieve all clock variables. Note that the TAI offset is 413 * returned only by ntp_gettime(); 414 */ 415 if (time_status & STA_NANO) 416 ntv.offset = L_GINT(time_offset); 417 else 418 ntv.offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */ 419 ntv.freq = L_GINT((time_freq / 1000LL) << 16); 420 ntv.maxerror = time_maxerror; 421 ntv.esterror = time_esterror; 422 ntv.status = time_status; 423 ntv.constant = time_constant; 424 if (time_status & STA_NANO) 425 ntv.precision = time_precision; 426 else 427 ntv.precision = time_precision / 1000; 428 ntv.tolerance = MAXFREQ * SCALE_PPM; 429 #ifdef PPS_SYNC 430 ntv.shift = pps_shift; 431 ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16); 432 if (time_status & STA_NANO) 433 ntv.jitter = pps_jitter; 434 else 435 ntv.jitter = pps_jitter / 1000; 436 ntv.stabil = pps_stabil; 437 ntv.calcnt = pps_calcnt; 438 ntv.errcnt = pps_errcnt; 439 ntv.jitcnt = pps_jitcnt; 440 ntv.stbcnt = pps_stbcnt; 441 #endif /* PPS_SYNC */ 442 splx(s); 443 444 error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv)); 445 if (error) 446 goto done2; 447 448 /* 449 * Status word error decode. See comments in 450 * ntp_gettime() routine. 451 */ 452 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 453 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 454 !(time_status & STA_PPSSIGNAL)) || 455 (time_status & STA_PPSTIME && 456 time_status & STA_PPSJITTER) || 457 (time_status & STA_PPSFREQ && 458 time_status & (STA_PPSWANDER | STA_PPSERROR))) { 459 td->td_retval[0] = TIME_ERROR; 460 } else { 461 td->td_retval[0] = time_state; 462 } 463 done2: 464 mtx_unlock(&Giant); 465 return (error); 466 } 467 468 /* 469 * second_overflow() - called after ntp_tick_adjust() 470 * 471 * This routine is ordinarily called immediately following the above 472 * routine ntp_tick_adjust(). While these two routines are normally 473 * combined, they are separated here only for the purposes of 474 * simulation. 475 */ 476 void 477 ntp_update_second(int64_t *adjustment, time_t *newsec) 478 { 479 int tickrate; 480 l_fp ftemp; /* 32/64-bit temporary */ 481 482 /* 483 * On rollover of the second both the nanosecond and microsecond 484 * clocks are updated and the state machine cranked as 485 * necessary. The phase adjustment to be used for the next 486 * second is calculated and the maximum error is increased by 487 * the tolerance. 488 */ 489 time_maxerror += MAXFREQ / 1000; 490 491 /* 492 * Leap second processing. If in leap-insert state at 493 * the end of the day, the system clock is set back one 494 * second; if in leap-delete state, the system clock is 495 * set ahead one second. The nano_time() routine or 496 * external clock driver will insure that reported time 497 * is always monotonic. 498 */ 499 switch (time_state) { 500 501 /* 502 * No warning. 503 */ 504 case TIME_OK: 505 if (time_status & STA_INS) 506 time_state = TIME_INS; 507 else if (time_status & STA_DEL) 508 time_state = TIME_DEL; 509 break; 510 511 /* 512 * Insert second 23:59:60 following second 513 * 23:59:59. 514 */ 515 case TIME_INS: 516 if (!(time_status & STA_INS)) 517 time_state = TIME_OK; 518 else if ((*newsec) % 86400 == 0) { 519 (*newsec)--; 520 time_state = TIME_OOP; 521 time_tai++; 522 } 523 break; 524 525 /* 526 * Delete second 23:59:59. 527 */ 528 case TIME_DEL: 529 if (!(time_status & STA_DEL)) 530 time_state = TIME_OK; 531 else if (((*newsec) + 1) % 86400 == 0) { 532 (*newsec)++; 533 time_tai--; 534 time_state = TIME_WAIT; 535 } 536 break; 537 538 /* 539 * Insert second in progress. 540 */ 541 case TIME_OOP: 542 time_state = TIME_WAIT; 543 break; 544 545 /* 546 * Wait for status bits to clear. 547 */ 548 case TIME_WAIT: 549 if (!(time_status & (STA_INS | STA_DEL))) 550 time_state = TIME_OK; 551 } 552 553 /* 554 * Compute the total time adjustment for the next second 555 * in ns. The offset is reduced by a factor depending on 556 * whether the PPS signal is operating. Note that the 557 * value is in effect scaled by the clock frequency, 558 * since the adjustment is added at each tick interrupt. 559 */ 560 ftemp = time_offset; 561 #ifdef PPS_SYNC 562 /* XXX even if PPS signal dies we should finish adjustment ? */ 563 if (time_status & STA_PPSTIME && time_status & 564 STA_PPSSIGNAL) 565 L_RSHIFT(ftemp, pps_shift); 566 else 567 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 568 #else 569 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 570 #endif /* PPS_SYNC */ 571 time_adj = ftemp; 572 L_SUB(time_offset, ftemp); 573 L_ADD(time_adj, time_freq); 574 575 /* 576 * Apply any correction from adjtime(2). If more than one second 577 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM) 578 * until the last second is slewed the final < 500 usecs. 579 */ 580 if (time_adjtime != 0) { 581 if (time_adjtime > 1000000) 582 tickrate = 5000; 583 else if (time_adjtime < -1000000) 584 tickrate = -5000; 585 else if (time_adjtime > 500) 586 tickrate = 500; 587 else if (time_adjtime < -500) 588 tickrate = -500; 589 else 590 tickrate = time_adjtime; 591 time_adjtime -= tickrate; 592 L_LINT(ftemp, tickrate * 1000); 593 L_ADD(time_adj, ftemp); 594 } 595 *adjustment = time_adj; 596 597 #ifdef PPS_SYNC 598 if (pps_valid > 0) 599 pps_valid--; 600 else 601 time_status &= ~STA_PPSSIGNAL; 602 #endif /* PPS_SYNC */ 603 } 604 605 /* 606 * ntp_init() - initialize variables and structures 607 * 608 * This routine must be called after the kernel variables hz and tick 609 * are set or changed and before the next tick interrupt. In this 610 * particular implementation, these values are assumed set elsewhere in 611 * the kernel. The design allows the clock frequency and tick interval 612 * to be changed while the system is running. So, this routine should 613 * probably be integrated with the code that does that. 614 */ 615 static void 616 ntp_init() 617 { 618 619 /* 620 * The following variables are initialized only at startup. Only 621 * those structures not cleared by the compiler need to be 622 * initialized, and these only in the simulator. In the actual 623 * kernel, any nonzero values here will quickly evaporate. 624 */ 625 L_CLR(time_offset); 626 L_CLR(time_freq); 627 #ifdef PPS_SYNC 628 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0; 629 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0; 630 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0; 631 pps_fcount = 0; 632 L_CLR(pps_freq); 633 #endif /* PPS_SYNC */ 634 } 635 636 SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL) 637 638 /* 639 * hardupdate() - local clock update 640 * 641 * This routine is called by ntp_adjtime() to update the local clock 642 * phase and frequency. The implementation is of an adaptive-parameter, 643 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new 644 * time and frequency offset estimates for each call. If the kernel PPS 645 * discipline code is configured (PPS_SYNC), the PPS signal itself 646 * determines the new time offset, instead of the calling argument. 647 * Presumably, calls to ntp_adjtime() occur only when the caller 648 * believes the local clock is valid within some bound (+-128 ms with 649 * NTP). If the caller's time is far different than the PPS time, an 650 * argument will ensue, and it's not clear who will lose. 651 * 652 * For uncompensated quartz crystal oscillators and nominal update 653 * intervals less than 256 s, operation should be in phase-lock mode, 654 * where the loop is disciplined to phase. For update intervals greater 655 * than 1024 s, operation should be in frequency-lock mode, where the 656 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode 657 * is selected by the STA_MODE status bit. 658 */ 659 static void 660 hardupdate(offset) 661 long offset; /* clock offset (ns) */ 662 { 663 long mtemp; 664 l_fp ftemp; 665 666 /* 667 * Select how the phase is to be controlled and from which 668 * source. If the PPS signal is present and enabled to 669 * discipline the time, the PPS offset is used; otherwise, the 670 * argument offset is used. 671 */ 672 if (!(time_status & STA_PLL)) 673 return; 674 if (!(time_status & STA_PPSTIME && time_status & 675 STA_PPSSIGNAL)) { 676 if (offset > MAXPHASE) 677 time_monitor = MAXPHASE; 678 else if (offset < -MAXPHASE) 679 time_monitor = -MAXPHASE; 680 else 681 time_monitor = offset; 682 L_LINT(time_offset, time_monitor); 683 } 684 685 /* 686 * Select how the frequency is to be controlled and in which 687 * mode (PLL or FLL). If the PPS signal is present and enabled 688 * to discipline the frequency, the PPS frequency is used; 689 * otherwise, the argument offset is used to compute it. 690 */ 691 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) { 692 time_reftime = time_second; 693 return; 694 } 695 if (time_status & STA_FREQHOLD || time_reftime == 0) 696 time_reftime = time_second; 697 mtemp = time_second - time_reftime; 698 L_LINT(ftemp, time_monitor); 699 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); 700 L_MPY(ftemp, mtemp); 701 L_ADD(time_freq, ftemp); 702 time_status &= ~STA_MODE; 703 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > 704 MAXSEC)) { 705 L_LINT(ftemp, (time_monitor << 4) / mtemp); 706 L_RSHIFT(ftemp, SHIFT_FLL + 4); 707 L_ADD(time_freq, ftemp); 708 time_status |= STA_MODE; 709 } 710 time_reftime = time_second; 711 if (L_GINT(time_freq) > MAXFREQ) 712 L_LINT(time_freq, MAXFREQ); 713 else if (L_GINT(time_freq) < -MAXFREQ) 714 L_LINT(time_freq, -MAXFREQ); 715 } 716 717 #ifdef PPS_SYNC 718 /* 719 * hardpps() - discipline CPU clock oscillator to external PPS signal 720 * 721 * This routine is called at each PPS interrupt in order to discipline 722 * the CPU clock oscillator to the PPS signal. There are two independent 723 * first-order feedback loops, one for the phase, the other for the 724 * frequency. The phase loop measures and grooms the PPS phase offset 725 * and leaves it in a handy spot for the seconds overflow routine. The 726 * frequency loop averages successive PPS phase differences and 727 * calculates the PPS frequency offset, which is also processed by the 728 * seconds overflow routine. The code requires the caller to capture the 729 * time and architecture-dependent hardware counter values in 730 * nanoseconds at the on-time PPS signal transition. 731 * 732 * Note that, on some Unix systems this routine runs at an interrupt 733 * priority level higher than the timer interrupt routine hardclock(). 734 * Therefore, the variables used are distinct from the hardclock() 735 * variables, except for the actual time and frequency variables, which 736 * are determined by this routine and updated atomically. 737 */ 738 void 739 hardpps(tsp, nsec) 740 struct timespec *tsp; /* time at PPS */ 741 long nsec; /* hardware counter at PPS */ 742 { 743 long u_sec, u_nsec, v_nsec; /* temps */ 744 l_fp ftemp; 745 746 /* 747 * The signal is first processed by a range gate and frequency 748 * discriminator. The range gate rejects noise spikes outside 749 * the range +-500 us. The frequency discriminator rejects input 750 * signals with apparent frequency outside the range 1 +-500 751 * PPM. If two hits occur in the same second, we ignore the 752 * later hit; if not and a hit occurs outside the range gate, 753 * keep the later hit for later comparison, but do not process 754 * it. 755 */ 756 time_status |= STA_PPSSIGNAL | STA_PPSJITTER; 757 time_status &= ~(STA_PPSWANDER | STA_PPSERROR); 758 pps_valid = PPS_VALID; 759 u_sec = tsp->tv_sec; 760 u_nsec = tsp->tv_nsec; 761 if (u_nsec >= (NANOSECOND >> 1)) { 762 u_nsec -= NANOSECOND; 763 u_sec++; 764 } 765 v_nsec = u_nsec - pps_tf[0].tv_nsec; 766 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - 767 MAXFREQ) 768 return; 769 pps_tf[2] = pps_tf[1]; 770 pps_tf[1] = pps_tf[0]; 771 pps_tf[0].tv_sec = u_sec; 772 pps_tf[0].tv_nsec = u_nsec; 773 774 /* 775 * Compute the difference between the current and previous 776 * counter values. If the difference exceeds 0.5 s, assume it 777 * has wrapped around, so correct 1.0 s. If the result exceeds 778 * the tick interval, the sample point has crossed a tick 779 * boundary during the last second, so correct the tick. Very 780 * intricate. 781 */ 782 u_nsec = nsec; 783 if (u_nsec > (NANOSECOND >> 1)) 784 u_nsec -= NANOSECOND; 785 else if (u_nsec < -(NANOSECOND >> 1)) 786 u_nsec += NANOSECOND; 787 pps_fcount += u_nsec; 788 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) 789 return; 790 time_status &= ~STA_PPSJITTER; 791 792 /* 793 * A three-stage median filter is used to help denoise the PPS 794 * time. The median sample becomes the time offset estimate; the 795 * difference between the other two samples becomes the time 796 * dispersion (jitter) estimate. 797 */ 798 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { 799 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { 800 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ 801 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; 802 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { 803 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ 804 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; 805 } else { 806 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ 807 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; 808 } 809 } else { 810 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { 811 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ 812 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; 813 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { 814 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ 815 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; 816 } else { 817 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ 818 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; 819 } 820 } 821 822 /* 823 * Nominal jitter is due to PPS signal noise and interrupt 824 * latency. If it exceeds the popcorn threshold, the sample is 825 * discarded. otherwise, if so enabled, the time offset is 826 * updated. We can tolerate a modest loss of data here without 827 * much degrading time accuracy. 828 */ 829 if (u_nsec > (pps_jitter << PPS_POPCORN)) { 830 time_status |= STA_PPSJITTER; 831 pps_jitcnt++; 832 } else if (time_status & STA_PPSTIME) { 833 time_monitor = -v_nsec; 834 L_LINT(time_offset, time_monitor); 835 } 836 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; 837 u_sec = pps_tf[0].tv_sec - pps_lastsec; 838 if (u_sec < (1 << pps_shift)) 839 return; 840 841 /* 842 * At the end of the calibration interval the difference between 843 * the first and last counter values becomes the scaled 844 * frequency. It will later be divided by the length of the 845 * interval to determine the frequency update. If the frequency 846 * exceeds a sanity threshold, or if the actual calibration 847 * interval is not equal to the expected length, the data are 848 * discarded. We can tolerate a modest loss of data here without 849 * much degrading frequency accuracy. 850 */ 851 pps_calcnt++; 852 v_nsec = -pps_fcount; 853 pps_lastsec = pps_tf[0].tv_sec; 854 pps_fcount = 0; 855 u_nsec = MAXFREQ << pps_shift; 856 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << 857 pps_shift)) { 858 time_status |= STA_PPSERROR; 859 pps_errcnt++; 860 return; 861 } 862 863 /* 864 * Here the raw frequency offset and wander (stability) is 865 * calculated. If the wander is less than the wander threshold 866 * for four consecutive averaging intervals, the interval is 867 * doubled; if it is greater than the threshold for four 868 * consecutive intervals, the interval is halved. The scaled 869 * frequency offset is converted to frequency offset. The 870 * stability metric is calculated as the average of recent 871 * frequency changes, but is used only for performance 872 * monitoring. 873 */ 874 L_LINT(ftemp, v_nsec); 875 L_RSHIFT(ftemp, pps_shift); 876 L_SUB(ftemp, pps_freq); 877 u_nsec = L_GINT(ftemp); 878 if (u_nsec > PPS_MAXWANDER) { 879 L_LINT(ftemp, PPS_MAXWANDER); 880 pps_intcnt--; 881 time_status |= STA_PPSWANDER; 882 pps_stbcnt++; 883 } else if (u_nsec < -PPS_MAXWANDER) { 884 L_LINT(ftemp, -PPS_MAXWANDER); 885 pps_intcnt--; 886 time_status |= STA_PPSWANDER; 887 pps_stbcnt++; 888 } else { 889 pps_intcnt++; 890 } 891 if (pps_intcnt >= 4) { 892 pps_intcnt = 4; 893 if (pps_shift < pps_shiftmax) { 894 pps_shift++; 895 pps_intcnt = 0; 896 } 897 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { 898 pps_intcnt = -4; 899 if (pps_shift > PPS_FAVG) { 900 pps_shift--; 901 pps_intcnt = 0; 902 } 903 } 904 if (u_nsec < 0) 905 u_nsec = -u_nsec; 906 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; 907 908 /* 909 * The PPS frequency is recalculated and clamped to the maximum 910 * MAXFREQ. If enabled, the system clock frequency is updated as 911 * well. 912 */ 913 L_ADD(pps_freq, ftemp); 914 u_nsec = L_GINT(pps_freq); 915 if (u_nsec > MAXFREQ) 916 L_LINT(pps_freq, MAXFREQ); 917 else if (u_nsec < -MAXFREQ) 918 L_LINT(pps_freq, -MAXFREQ); 919 if (time_status & STA_PPSFREQ) 920 time_freq = pps_freq; 921 } 922 #endif /* PPS_SYNC */ 923 924 #ifndef _SYS_SYSPROTO_H_ 925 struct adjtime_args { 926 struct timeval *delta; 927 struct timeval *olddelta; 928 }; 929 #endif 930 /* 931 * MPSAFE 932 */ 933 /* ARGSUSED */ 934 int 935 adjtime(struct thread *td, struct adjtime_args *uap) 936 { 937 struct timeval delta, olddelta, *deltap; 938 int error; 939 940 if (uap->delta) { 941 error = copyin(uap->delta, &delta, sizeof(delta)); 942 if (error) 943 return (error); 944 deltap = δ 945 } else 946 deltap = NULL; 947 error = kern_adjtime(td, deltap, &olddelta); 948 if (uap->olddelta && error == 0) 949 error = copyout(&olddelta, uap->olddelta, sizeof(olddelta)); 950 return (error); 951 } 952 953 int 954 kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta) 955 { 956 struct timeval atv; 957 int error; 958 959 if ((error = priv_check(td, PRIV_ADJTIME))) 960 return (error); 961 962 mtx_lock(&Giant); 963 if (olddelta) { 964 atv.tv_sec = time_adjtime / 1000000; 965 atv.tv_usec = time_adjtime % 1000000; 966 if (atv.tv_usec < 0) { 967 atv.tv_usec += 1000000; 968 atv.tv_sec--; 969 } 970 *olddelta = atv; 971 } 972 if (delta) 973 time_adjtime = (int64_t)delta->tv_sec * 1000000 + 974 delta->tv_usec; 975 mtx_unlock(&Giant); 976 return (error); 977 } 978 979