1 /* $NetBSD: kern_ntptime.c,v 1.63 2022/03/13 12:57:33 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /*- 30 *********************************************************************** 31 * * 32 * Copyright (c) David L. Mills 1993-2001 * 33 * * 34 * Permission to use, copy, modify, and distribute this software and * 35 * its documentation for any purpose and without fee is hereby * 36 * granted, provided that the above copyright notice appears in all * 37 * copies and that both the copyright notice and this permission * 38 * notice appear in supporting documentation, and that the name * 39 * University of Delaware not be used in advertising or publicity * 40 * pertaining to distribution of the software without specific, * 41 * written prior permission. The University of Delaware makes no * 42 * representations about the suitability this software for any * 43 * purpose. It is provided "as is" without express or implied * 44 * warranty. * 45 * * 46 **********************************************************************/ 47 48 /* 49 * Adapted from the original sources for FreeBSD and timecounters by: 50 * Poul-Henning Kamp <phk@FreeBSD.org>. 51 * 52 * The 32bit version of the "LP" macros seems a bit past its "sell by" 53 * date so I have retained only the 64bit version and included it directly 54 * in this file. 55 * 56 * Only minor changes done to interface with the timecounters over in 57 * sys/kern/kern_clock.c. Some of the comments below may be (even more) 58 * confusing and/or plain wrong in that context. 59 */ 60 61 #include <sys/cdefs.h> 62 /* __FBSDID("$FreeBSD: src/sys/kern/kern_ntptime.c,v 1.59 2005/05/28 14:34:41 rwatson Exp $"); */ 63 __KERNEL_RCSID(0, "$NetBSD: kern_ntptime.c,v 1.63 2022/03/13 12:57:33 riastradh Exp $"); 64 65 #ifdef _KERNEL_OPT 66 #include "opt_ntp.h" 67 #endif 68 69 #include <sys/param.h> 70 #include <sys/resourcevar.h> 71 #include <sys/systm.h> 72 #include <sys/kernel.h> 73 #include <sys/proc.h> 74 #include <sys/sysctl.h> 75 #include <sys/timex.h> 76 #include <sys/vnode.h> 77 #include <sys/kauth.h> 78 #include <sys/mount.h> 79 #include <sys/syscallargs.h> 80 #include <sys/cpu.h> 81 82 #include <compat/sys/timex.h> 83 84 /* 85 * Single-precision macros for 64-bit machines 86 */ 87 typedef int64_t l_fp; 88 #define L_ADD(v, u) ((v) += (u)) 89 #define L_SUB(v, u) ((v) -= (u)) 90 #define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32) 91 #define L_NEG(v) ((v) = -(v)) 92 #define L_RSHIFT(v, n) \ 93 do { \ 94 if ((v) < 0) \ 95 (v) = -(-(v) >> (n)); \ 96 else \ 97 (v) = (v) >> (n); \ 98 } while (0) 99 #define L_MPY(v, a) ((v) *= (a)) 100 #define L_CLR(v) ((v) = 0) 101 #define L_ISNEG(v) ((v) < 0) 102 #define L_LINT(v, a) ((v) = (int64_t)((uint64_t)(a) << 32)) 103 #define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32) 104 105 #ifdef NTP 106 /* 107 * Generic NTP kernel interface 108 * 109 * These routines constitute the Network Time Protocol (NTP) interfaces 110 * for user and daemon application programs. The ntp_gettime() routine 111 * provides the time, maximum error (synch distance) and estimated error 112 * (dispersion) to client user application programs. The ntp_adjtime() 113 * routine is used by the NTP daemon to adjust the system clock to an 114 * externally derived time. The time offset and related variables set by 115 * this routine are used by other routines in this module to adjust the 116 * phase and frequency of the clock discipline loop which controls the 117 * system clock. 118 * 119 * When the kernel time is reckoned directly in nanoseconds (NTP_NANO 120 * defined), the time at each tick interrupt is derived directly from 121 * the kernel time variable. When the kernel time is reckoned in 122 * microseconds, (NTP_NANO undefined), the time is derived from the 123 * kernel time variable together with a variable representing the 124 * leftover nanoseconds at the last tick interrupt. In either case, the 125 * current nanosecond time is reckoned from these values plus an 126 * interpolated value derived by the clock routines in another 127 * architecture-specific module. The interpolation can use either a 128 * dedicated counter or a processor cycle counter (PCC) implemented in 129 * some architectures. 130 * 131 * Note that all routines must run at priority splclock or higher. 132 */ 133 /* 134 * Phase/frequency-lock loop (PLL/FLL) definitions 135 * 136 * The nanosecond clock discipline uses two variable types, time 137 * variables and frequency variables. Both types are represented as 64- 138 * bit fixed-point quantities with the decimal point between two 32-bit 139 * halves. On a 32-bit machine, each half is represented as a single 140 * word and mathematical operations are done using multiple-precision 141 * arithmetic. On a 64-bit machine, ordinary computer arithmetic is 142 * used. 143 * 144 * A time variable is a signed 64-bit fixed-point number in ns and 145 * fraction. It represents the remaining time offset to be amortized 146 * over succeeding tick interrupts. The maximum time offset is about 147 * 0.5 s and the resolution is about 2.3e-10 ns. 148 * 149 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 150 * 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 1 151 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 152 * |s s s| ns | 153 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 154 * | fraction | 155 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 156 * 157 * A frequency variable is a signed 64-bit fixed-point number in ns/s 158 * and fraction. It represents the ns and fraction to be added to the 159 * kernel time variable at each second. The maximum frequency offset is 160 * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s. 161 * 162 * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 163 * 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 1 164 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 165 * |s s s s s s s s s s s s s| ns/s | 166 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 167 * | fraction | 168 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 169 */ 170 /* 171 * The following variables establish the state of the PLL/FLL and the 172 * residual time and frequency offset of the local clock. 173 */ 174 #define SHIFT_PLL 4 /* PLL loop gain (shift) */ 175 #define SHIFT_FLL 2 /* FLL loop gain (shift) */ 176 177 static int time_state = TIME_OK; /* clock state */ 178 static int time_status = STA_UNSYNC; /* clock status bits */ 179 static long time_tai; /* TAI offset (s) */ 180 static long time_monitor; /* last time offset scaled (ns) */ 181 static long time_constant; /* poll interval (shift) (s) */ 182 static long time_precision = 1; /* clock precision (ns) */ 183 static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */ 184 static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */ 185 static time_t time_reftime; /* time at last adjustment (s) */ 186 static l_fp time_offset; /* time offset (ns) */ 187 static l_fp time_freq; /* frequency offset (ns/s) */ 188 #endif /* NTP */ 189 190 static l_fp time_adj; /* tick adjust (ns/s) */ 191 int64_t time_adjtime; /* correction from adjtime(2) (usec) */ 192 193 extern int time_adjusted; /* ntp might have changed the system time */ 194 195 #ifdef NTP 196 #ifdef PPS_SYNC 197 /* 198 * The following variables are used when a pulse-per-second (PPS) signal 199 * is available and connected via a modem control lead. They establish 200 * the engineering parameters of the clock discipline loop when 201 * controlled by the PPS signal. 202 */ 203 #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */ 204 #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */ 205 #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */ 206 #define PPS_PAVG 4 /* phase avg interval (s) (shift) */ 207 #define PPS_VALID 120 /* PPS signal watchdog max (s) */ 208 #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */ 209 #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */ 210 211 static struct timespec pps_tf[3]; /* phase median filter */ 212 static l_fp pps_freq; /* scaled frequency offset (ns/s) */ 213 static long pps_fcount; /* frequency accumulator */ 214 static long pps_jitter; /* nominal jitter (ns) */ 215 static long pps_stabil; /* nominal stability (scaled ns/s) */ 216 static long pps_lastsec; /* time at last calibration (s) */ 217 static int pps_valid; /* signal watchdog counter */ 218 static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */ 219 static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */ 220 static int pps_intcnt; /* wander counter */ 221 222 /* 223 * PPS signal quality monitors 224 */ 225 static long pps_calcnt; /* calibration intervals */ 226 static long pps_jitcnt; /* jitter limit exceeded */ 227 static long pps_stbcnt; /* stability limit exceeded */ 228 static long pps_errcnt; /* calibration errors */ 229 #endif /* PPS_SYNC */ 230 /* 231 * End of phase/frequency-lock loop (PLL/FLL) definitions 232 */ 233 234 static void hardupdate(long offset); 235 236 /* 237 * ntp_gettime() - NTP user application interface 238 */ 239 void 240 ntp_gettime(struct ntptimeval *ntv) 241 { 242 memset(ntv, 0, sizeof(*ntv)); 243 244 mutex_spin_enter(&timecounter_lock); 245 nanotime(&ntv->time); 246 ntv->maxerror = time_maxerror; 247 ntv->esterror = time_esterror; 248 ntv->tai = time_tai; 249 ntv->time_state = time_state; 250 mutex_spin_exit(&timecounter_lock); 251 } 252 253 /* ARGSUSED */ 254 /* 255 * ntp_adjtime() - NTP daemon application interface 256 */ 257 int 258 sys_ntp_adjtime(struct lwp *l, const struct sys_ntp_adjtime_args *uap, register_t *retval) 259 { 260 /* { 261 syscallarg(struct timex *) tp; 262 } */ 263 struct timex ntv; 264 int error; 265 266 error = copyin((void *)SCARG(uap, tp), (void *)&ntv, sizeof(ntv)); 267 if (error != 0) 268 return (error); 269 270 if (ntv.modes != 0 && (error = kauth_authorize_system(l->l_cred, 271 KAUTH_SYSTEM_TIME, KAUTH_REQ_SYSTEM_TIME_NTPADJTIME, NULL, 272 NULL, NULL)) != 0) 273 return (error); 274 275 ntp_adjtime1(&ntv); 276 277 error = copyout((void *)&ntv, (void *)SCARG(uap, tp), sizeof(ntv)); 278 if (!error) 279 *retval = ntp_timestatus(); 280 281 return error; 282 } 283 284 void 285 ntp_adjtime1(struct timex *ntv) 286 { 287 long freq; 288 int modes; 289 290 /* 291 * Update selected clock variables - only the superuser can 292 * change anything. Note that there is no error checking here on 293 * the assumption the superuser should know what it is doing. 294 * Note that either the time constant or TAI offset are loaded 295 * from the ntv.constant member, depending on the mode bits. If 296 * the STA_PLL bit in the status word is cleared, the state and 297 * status words are reset to the initial values at boot. 298 */ 299 mutex_spin_enter(&timecounter_lock); 300 modes = ntv->modes; 301 if (modes != 0) 302 /* We need to save the system time during shutdown */ 303 time_adjusted |= 2; 304 if (modes & MOD_MAXERROR) 305 time_maxerror = ntv->maxerror; 306 if (modes & MOD_ESTERROR) 307 time_esterror = ntv->esterror; 308 if (modes & MOD_STATUS) { 309 if (time_status & STA_PLL && !(ntv->status & STA_PLL)) { 310 time_state = TIME_OK; 311 time_status = STA_UNSYNC; 312 #ifdef PPS_SYNC 313 pps_shift = PPS_FAVG; 314 #endif /* PPS_SYNC */ 315 } 316 time_status &= STA_RONLY; 317 time_status |= ntv->status & ~STA_RONLY; 318 } 319 if (modes & MOD_TIMECONST) { 320 if (ntv->constant < 0) 321 time_constant = 0; 322 else if (ntv->constant > MAXTC) 323 time_constant = MAXTC; 324 else 325 time_constant = ntv->constant; 326 } 327 if (modes & MOD_TAI) { 328 if (ntv->constant > 0) /* XXX zero & negative numbers ? */ 329 time_tai = ntv->constant; 330 } 331 #ifdef PPS_SYNC 332 if (modes & MOD_PPSMAX) { 333 if (ntv->shift < PPS_FAVG) 334 pps_shiftmax = PPS_FAVG; 335 else if (ntv->shift > PPS_FAVGMAX) 336 pps_shiftmax = PPS_FAVGMAX; 337 else 338 pps_shiftmax = ntv->shift; 339 } 340 #endif /* PPS_SYNC */ 341 if (modes & MOD_NANO) 342 time_status |= STA_NANO; 343 if (modes & MOD_MICRO) 344 time_status &= ~STA_NANO; 345 if (modes & MOD_CLKB) 346 time_status |= STA_CLK; 347 if (modes & MOD_CLKA) 348 time_status &= ~STA_CLK; 349 if (modes & MOD_FREQUENCY) { 350 freq = MIN(INT32_MAX, MAX(INT32_MIN, ntv->freq)); 351 freq = (freq * (int64_t)1000) >> 16; 352 if (freq > MAXFREQ) 353 L_LINT(time_freq, MAXFREQ); 354 else if (freq < -MAXFREQ) 355 L_LINT(time_freq, -MAXFREQ); 356 else { 357 /* 358 * ntv.freq is [PPM * 2^16] = [us/s * 2^16] 359 * time_freq is [ns/s * 2^32] 360 */ 361 time_freq = ntv->freq * 1000LL * 65536LL; 362 } 363 #ifdef PPS_SYNC 364 pps_freq = time_freq; 365 #endif /* PPS_SYNC */ 366 } 367 if (modes & MOD_OFFSET) { 368 if (time_status & STA_NANO) { 369 hardupdate(ntv->offset); 370 } else { 371 long offset = ntv->offset; 372 offset = MIN(offset, MAXPHASE/1000); 373 offset = MAX(offset, -MAXPHASE/1000); 374 hardupdate(offset * 1000); 375 } 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 if (time_freq < 0) 387 ntv->freq = L_GINT(-((-time_freq / 1000LL) << 16)); 388 else 389 ntv->freq = L_GINT((time_freq / 1000LL) << 16); 390 ntv->maxerror = time_maxerror; 391 ntv->esterror = time_esterror; 392 ntv->status = time_status; 393 ntv->constant = time_constant; 394 if (time_status & STA_NANO) 395 ntv->precision = time_precision; 396 else 397 ntv->precision = time_precision / 1000; 398 ntv->tolerance = MAXFREQ * SCALE_PPM; 399 #ifdef PPS_SYNC 400 ntv->shift = pps_shift; 401 ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16); 402 if (time_status & STA_NANO) 403 ntv->jitter = pps_jitter; 404 else 405 ntv->jitter = pps_jitter / 1000; 406 ntv->stabil = pps_stabil; 407 ntv->calcnt = pps_calcnt; 408 ntv->errcnt = pps_errcnt; 409 ntv->jitcnt = pps_jitcnt; 410 ntv->stbcnt = pps_stbcnt; 411 #endif /* PPS_SYNC */ 412 mutex_spin_exit(&timecounter_lock); 413 } 414 #endif /* NTP */ 415 416 /* 417 * second_overflow() - called after ntp_tick_adjust() 418 * 419 * This routine is ordinarily called immediately following the above 420 * routine ntp_tick_adjust(). While these two routines are normally 421 * combined, they are separated here only for the purposes of 422 * simulation. 423 */ 424 void 425 ntp_update_second(int64_t *adjustment, time_t *newsec) 426 { 427 int tickrate; 428 l_fp ftemp; /* 32/64-bit temporary */ 429 430 KASSERT(mutex_owned(&timecounter_lock)); 431 432 #ifdef NTP 433 434 /* 435 * On rollover of the second both the nanosecond and microsecond 436 * clocks are updated and the state machine cranked as 437 * necessary. The phase adjustment to be used for the next 438 * second is calculated and the maximum error is increased by 439 * the tolerance. 440 */ 441 time_maxerror += MAXFREQ / 1000; 442 443 /* 444 * Leap second processing. If in leap-insert state at 445 * the end of the day, the system clock is set back one 446 * second; if in leap-delete state, the system clock is 447 * set ahead one second. The nano_time() routine or 448 * external clock driver will insure that reported time 449 * is always monotonic. 450 */ 451 switch (time_state) { 452 453 /* 454 * No warning. 455 */ 456 case TIME_OK: 457 if (time_status & STA_INS) 458 time_state = TIME_INS; 459 else if (time_status & STA_DEL) 460 time_state = TIME_DEL; 461 break; 462 463 /* 464 * Insert second 23:59:60 following second 465 * 23:59:59. 466 */ 467 case TIME_INS: 468 if (!(time_status & STA_INS)) 469 time_state = TIME_OK; 470 else if ((*newsec) % 86400 == 0) { 471 (*newsec)--; 472 time_state = TIME_OOP; 473 time_tai++; 474 } 475 break; 476 477 /* 478 * Delete second 23:59:59. 479 */ 480 case TIME_DEL: 481 if (!(time_status & STA_DEL)) 482 time_state = TIME_OK; 483 else if (((*newsec) + 1) % 86400 == 0) { 484 (*newsec)++; 485 time_tai--; 486 time_state = TIME_WAIT; 487 } 488 break; 489 490 /* 491 * Insert second in progress. 492 */ 493 case TIME_OOP: 494 time_state = TIME_WAIT; 495 break; 496 497 /* 498 * Wait for status bits to clear. 499 */ 500 case TIME_WAIT: 501 if (!(time_status & (STA_INS | STA_DEL))) 502 time_state = TIME_OK; 503 } 504 505 /* 506 * Compute the total time adjustment for the next second 507 * in ns. The offset is reduced by a factor depending on 508 * whether the PPS signal is operating. Note that the 509 * value is in effect scaled by the clock frequency, 510 * since the adjustment is added at each tick interrupt. 511 */ 512 ftemp = time_offset; 513 #ifdef PPS_SYNC 514 /* XXX even if PPS signal dies we should finish adjustment ? */ 515 if (time_status & STA_PPSTIME && time_status & 516 STA_PPSSIGNAL) 517 L_RSHIFT(ftemp, pps_shift); 518 else 519 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 520 #else 521 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 522 #endif /* PPS_SYNC */ 523 time_adj = ftemp; 524 L_SUB(time_offset, ftemp); 525 L_ADD(time_adj, time_freq); 526 527 #ifdef PPS_SYNC 528 if (pps_valid > 0) 529 pps_valid--; 530 else 531 time_status &= ~STA_PPSSIGNAL; 532 #endif /* PPS_SYNC */ 533 #else /* !NTP */ 534 L_CLR(time_adj); 535 #endif /* !NTP */ 536 537 /* 538 * Apply any correction from adjtime(2). If more than one second 539 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM) 540 * until the last second is slewed the final < 500 usecs. 541 */ 542 if (time_adjtime != 0) { 543 if (time_adjtime > 1000000) 544 tickrate = 5000; 545 else if (time_adjtime < -1000000) 546 tickrate = -5000; 547 else if (time_adjtime > 500) 548 tickrate = 500; 549 else if (time_adjtime < -500) 550 tickrate = -500; 551 else 552 tickrate = time_adjtime; 553 time_adjtime -= tickrate; 554 L_LINT(ftemp, tickrate * 1000); 555 L_ADD(time_adj, ftemp); 556 } 557 *adjustment = time_adj; 558 } 559 560 /* 561 * ntp_init() - initialize variables and structures 562 * 563 * This routine must be called after the kernel variables hz and tick 564 * are set or changed and before the next tick interrupt. In this 565 * particular implementation, these values are assumed set elsewhere in 566 * the kernel. The design allows the clock frequency and tick interval 567 * to be changed while the system is running. So, this routine should 568 * probably be integrated with the code that does that. 569 */ 570 void 571 ntp_init(void) 572 { 573 574 /* 575 * The following variables are initialized only at startup. Only 576 * those structures not cleared by the compiler need to be 577 * initialized, and these only in the simulator. In the actual 578 * kernel, any nonzero values here will quickly evaporate. 579 */ 580 L_CLR(time_adj); 581 #ifdef NTP 582 L_CLR(time_offset); 583 L_CLR(time_freq); 584 #ifdef PPS_SYNC 585 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0; 586 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0; 587 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0; 588 pps_fcount = 0; 589 L_CLR(pps_freq); 590 #endif /* PPS_SYNC */ 591 #endif 592 } 593 594 #ifdef NTP 595 /* 596 * hardupdate() - local clock update 597 * 598 * This routine is called by ntp_adjtime() to update the local clock 599 * phase and frequency. The implementation is of an adaptive-parameter, 600 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new 601 * time and frequency offset estimates for each call. If the kernel PPS 602 * discipline code is configured (PPS_SYNC), the PPS signal itself 603 * determines the new time offset, instead of the calling argument. 604 * Presumably, calls to ntp_adjtime() occur only when the caller 605 * believes the local clock is valid within some bound (+-128 ms with 606 * NTP). If the caller's time is far different than the PPS time, an 607 * argument will ensue, and it's not clear who will lose. 608 * 609 * For uncompensated quartz crystal oscillators and nominal update 610 * intervals less than 256 s, operation should be in phase-lock mode, 611 * where the loop is disciplined to phase. For update intervals greater 612 * than 1024 s, operation should be in frequency-lock mode, where the 613 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode 614 * is selected by the STA_MODE status bit. 615 * 616 * Note: splclock() is in effect. 617 */ 618 void 619 hardupdate(long offset) 620 { 621 long mtemp; 622 l_fp ftemp; 623 624 KASSERT(mutex_owned(&timecounter_lock)); 625 626 /* 627 * Select how the phase is to be controlled and from which 628 * source. If the PPS signal is present and enabled to 629 * discipline the time, the PPS offset is used; otherwise, the 630 * argument offset is used. 631 */ 632 if (!(time_status & STA_PLL)) 633 return; 634 if (!(time_status & STA_PPSTIME && time_status & 635 STA_PPSSIGNAL)) { 636 if (offset > MAXPHASE) 637 time_monitor = MAXPHASE; 638 else if (offset < -MAXPHASE) 639 time_monitor = -MAXPHASE; 640 else 641 time_monitor = offset; 642 L_LINT(time_offset, time_monitor); 643 } 644 645 /* 646 * Select how the frequency is to be controlled and in which 647 * mode (PLL or FLL). If the PPS signal is present and enabled 648 * to discipline the frequency, the PPS frequency is used; 649 * otherwise, the argument offset is used to compute it. 650 */ 651 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) { 652 time_reftime = time_second; 653 return; 654 } 655 if (time_status & STA_FREQHOLD || time_reftime == 0) 656 time_reftime = time_second; 657 mtemp = time_second - time_reftime; 658 L_LINT(ftemp, time_monitor); 659 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); 660 L_MPY(ftemp, mtemp); 661 L_ADD(time_freq, ftemp); 662 time_status &= ~STA_MODE; 663 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > 664 MAXSEC)) { 665 L_LINT(ftemp, (time_monitor << 4) / mtemp); 666 L_RSHIFT(ftemp, SHIFT_FLL + 4); 667 L_ADD(time_freq, ftemp); 668 time_status |= STA_MODE; 669 } 670 time_reftime = time_second; 671 if (L_GINT(time_freq) > MAXFREQ) 672 L_LINT(time_freq, MAXFREQ); 673 else if (L_GINT(time_freq) < -MAXFREQ) 674 L_LINT(time_freq, -MAXFREQ); 675 } 676 677 #ifdef PPS_SYNC 678 /* 679 * hardpps() - discipline CPU clock oscillator to external PPS signal 680 * 681 * This routine is called at each PPS interrupt in order to discipline 682 * the CPU clock oscillator to the PPS signal. It measures the PPS phase 683 * and leaves it in a handy spot for the hardclock() routine. It 684 * integrates successive PPS phase differences and calculates the 685 * frequency offset. This is used in hardclock() to discipline the CPU 686 * clock oscillator so that intrinsic frequency error is cancelled out. 687 * The code requires the caller to capture the time and hardware counter 688 * value at the on-time PPS signal transition. 689 * 690 * Note that, on some Unix systems, this routine runs at an interrupt 691 * priority level higher than the timer interrupt routine hardclock(). 692 * Therefore, the variables used are distinct from the hardclock() 693 * variables, except for certain exceptions: The PPS frequency pps_freq 694 * and phase pps_offset variables are determined by this routine and 695 * updated atomically. The time_tolerance variable can be considered a 696 * constant, since it is infrequently changed, and then only when the 697 * PPS signal is disabled. The watchdog counter pps_valid is updated 698 * once per second by hardclock() and is atomically cleared in this 699 * routine. 700 */ 701 void 702 hardpps(struct timespec *tsp, /* time at PPS */ 703 long nsec /* hardware counter at PPS */) 704 { 705 long u_sec, u_nsec, v_nsec; /* temps */ 706 l_fp ftemp; 707 708 KASSERT(mutex_owned(&timecounter_lock)); 709 710 /* 711 * The signal is first processed by a range gate and frequency 712 * discriminator. The range gate rejects noise spikes outside 713 * the range +-500 us. The frequency discriminator rejects input 714 * signals with apparent frequency outside the range 1 +-500 715 * PPM. If two hits occur in the same second, we ignore the 716 * later hit; if not and a hit occurs outside the range gate, 717 * keep the later hit for later comparison, but do not process 718 * it. 719 */ 720 time_status |= STA_PPSSIGNAL | STA_PPSJITTER; 721 time_status &= ~(STA_PPSWANDER | STA_PPSERROR); 722 pps_valid = PPS_VALID; 723 u_sec = tsp->tv_sec; 724 u_nsec = tsp->tv_nsec; 725 if (u_nsec >= (NANOSECOND >> 1)) { 726 u_nsec -= NANOSECOND; 727 u_sec++; 728 } 729 v_nsec = u_nsec - pps_tf[0].tv_nsec; 730 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - 731 MAXFREQ) 732 return; 733 pps_tf[2] = pps_tf[1]; 734 pps_tf[1] = pps_tf[0]; 735 pps_tf[0].tv_sec = u_sec; 736 pps_tf[0].tv_nsec = u_nsec; 737 738 /* 739 * Compute the difference between the current and previous 740 * counter values. If the difference exceeds 0.5 s, assume it 741 * has wrapped around, so correct 1.0 s. If the result exceeds 742 * the tick interval, the sample point has crossed a tick 743 * boundary during the last second, so correct the tick. Very 744 * intricate. 745 */ 746 u_nsec = nsec; 747 if (u_nsec > (NANOSECOND >> 1)) 748 u_nsec -= NANOSECOND; 749 else if (u_nsec < -(NANOSECOND >> 1)) 750 u_nsec += NANOSECOND; 751 pps_fcount += u_nsec; 752 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) 753 return; 754 time_status &= ~STA_PPSJITTER; 755 756 /* 757 * A three-stage median filter is used to help denoise the PPS 758 * time. The median sample becomes the time offset estimate; the 759 * difference between the other two samples becomes the time 760 * dispersion (jitter) estimate. 761 */ 762 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { 763 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { 764 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ 765 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; 766 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { 767 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ 768 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; 769 } else { 770 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ 771 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; 772 } 773 } else { 774 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { 775 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ 776 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; 777 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { 778 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ 779 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; 780 } else { 781 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ 782 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; 783 } 784 } 785 786 /* 787 * Nominal jitter is due to PPS signal noise and interrupt 788 * latency. If it exceeds the popcorn threshold, the sample is 789 * discarded. otherwise, if so enabled, the time offset is 790 * updated. We can tolerate a modest loss of data here without 791 * much degrading time accuracy. 792 */ 793 if (u_nsec > (pps_jitter << PPS_POPCORN)) { 794 time_status |= STA_PPSJITTER; 795 pps_jitcnt++; 796 } else if (time_status & STA_PPSTIME) { 797 time_monitor = -v_nsec; 798 L_LINT(time_offset, time_monitor); 799 } 800 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; 801 u_sec = pps_tf[0].tv_sec - pps_lastsec; 802 if (u_sec < (1 << pps_shift)) 803 return; 804 805 /* 806 * At the end of the calibration interval the difference between 807 * the first and last counter values becomes the scaled 808 * frequency. It will later be divided by the length of the 809 * interval to determine the frequency update. If the frequency 810 * exceeds a sanity threshold, or if the actual calibration 811 * interval is not equal to the expected length, the data are 812 * discarded. We can tolerate a modest loss of data here without 813 * much degrading frequency accuracy. 814 */ 815 pps_calcnt++; 816 v_nsec = -pps_fcount; 817 pps_lastsec = pps_tf[0].tv_sec; 818 pps_fcount = 0; 819 u_nsec = MAXFREQ << pps_shift; 820 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << 821 pps_shift)) { 822 time_status |= STA_PPSERROR; 823 pps_errcnt++; 824 return; 825 } 826 827 /* 828 * Here the raw frequency offset and wander (stability) is 829 * calculated. If the wander is less than the wander threshold 830 * for four consecutive averaging intervals, the interval is 831 * doubled; if it is greater than the threshold for four 832 * consecutive intervals, the interval is halved. The scaled 833 * frequency offset is converted to frequency offset. The 834 * stability metric is calculated as the average of recent 835 * frequency changes, but is used only for performance 836 * monitoring. 837 */ 838 L_LINT(ftemp, v_nsec); 839 L_RSHIFT(ftemp, pps_shift); 840 L_SUB(ftemp, pps_freq); 841 u_nsec = L_GINT(ftemp); 842 if (u_nsec > PPS_MAXWANDER) { 843 L_LINT(ftemp, PPS_MAXWANDER); 844 pps_intcnt--; 845 time_status |= STA_PPSWANDER; 846 pps_stbcnt++; 847 } else if (u_nsec < -PPS_MAXWANDER) { 848 L_LINT(ftemp, -PPS_MAXWANDER); 849 pps_intcnt--; 850 time_status |= STA_PPSWANDER; 851 pps_stbcnt++; 852 } else { 853 pps_intcnt++; 854 } 855 if (pps_intcnt >= 4) { 856 pps_intcnt = 4; 857 if (pps_shift < pps_shiftmax) { 858 pps_shift++; 859 pps_intcnt = 0; 860 } 861 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { 862 pps_intcnt = -4; 863 if (pps_shift > PPS_FAVG) { 864 pps_shift--; 865 pps_intcnt = 0; 866 } 867 } 868 if (u_nsec < 0) 869 u_nsec = -u_nsec; 870 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; 871 872 /* 873 * The PPS frequency is recalculated and clamped to the maximum 874 * MAXFREQ. If enabled, the system clock frequency is updated as 875 * well. 876 */ 877 L_ADD(pps_freq, ftemp); 878 u_nsec = L_GINT(pps_freq); 879 if (u_nsec > MAXFREQ) 880 L_LINT(pps_freq, MAXFREQ); 881 else if (u_nsec < -MAXFREQ) 882 L_LINT(pps_freq, -MAXFREQ); 883 if (time_status & STA_PPSFREQ) 884 time_freq = pps_freq; 885 } 886 #endif /* PPS_SYNC */ 887 #endif /* NTP */ 888 889 #ifdef NTP 890 int 891 ntp_timestatus(void) 892 { 893 int rv; 894 895 /* 896 * Status word error decode. If any of these conditions 897 * occur, an error is returned, instead of the status 898 * word. Most applications will care only about the fact 899 * the system clock may not be trusted, not about the 900 * details. 901 * 902 * Hardware or software error 903 */ 904 mutex_spin_enter(&timecounter_lock); 905 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 906 907 /* 908 * PPS signal lost when either time or frequency 909 * synchronization requested 910 */ 911 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 912 !(time_status & STA_PPSSIGNAL)) || 913 914 /* 915 * PPS jitter exceeded when time synchronization 916 * requested 917 */ 918 (time_status & STA_PPSTIME && 919 time_status & STA_PPSJITTER) || 920 921 /* 922 * PPS wander exceeded or calibration error when 923 * frequency synchronization requested 924 */ 925 (time_status & STA_PPSFREQ && 926 time_status & (STA_PPSWANDER | STA_PPSERROR))) 927 rv = TIME_ERROR; 928 else 929 rv = time_state; 930 mutex_spin_exit(&timecounter_lock); 931 932 return rv; 933 } 934 935 /*ARGSUSED*/ 936 /* 937 * ntp_gettime() - NTP user application interface 938 */ 939 int 940 sys___ntp_gettime50(struct lwp *l, const struct sys___ntp_gettime50_args *uap, register_t *retval) 941 { 942 /* { 943 syscallarg(struct ntptimeval *) ntvp; 944 } */ 945 struct ntptimeval ntv; 946 int error = 0; 947 948 if (SCARG(uap, ntvp)) { 949 ntp_gettime(&ntv); 950 951 error = copyout((void *)&ntv, (void *)SCARG(uap, ntvp), 952 sizeof(ntv)); 953 } 954 if (!error) { 955 *retval = ntp_timestatus(); 956 } 957 return(error); 958 } 959 960 /* 961 * return information about kernel precision timekeeping 962 */ 963 static int 964 sysctl_kern_ntptime(SYSCTLFN_ARGS) 965 { 966 struct sysctlnode node; 967 struct ntptimeval ntv; 968 969 ntp_gettime(&ntv); 970 971 node = *rnode; 972 node.sysctl_data = &ntv; 973 node.sysctl_size = sizeof(ntv); 974 return (sysctl_lookup(SYSCTLFN_CALL(&node))); 975 } 976 977 SYSCTL_SETUP(sysctl_kern_ntptime_setup, "sysctl kern.ntptime node setup") 978 { 979 980 sysctl_createv(clog, 0, NULL, NULL, 981 CTLFLAG_PERMANENT, 982 CTLTYPE_STRUCT, "ntptime", 983 SYSCTL_DESCR("Kernel clock values for NTP"), 984 sysctl_kern_ntptime, 0, NULL, 985 sizeof(struct ntptimeval), 986 CTL_KERN, KERN_NTPTIME, CTL_EOL); 987 } 988 #endif /* !NTP */ 989