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