1 /* $NetBSD: kern_ntptime.c,v 1.64 2022/10/26 23:23:52 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 1.64 2022/10/26 23:23:52 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 #ifdef NTP 194 #ifdef PPS_SYNC 195 /* 196 * The following variables are used when a pulse-per-second (PPS) signal 197 * is available and connected via a modem control lead. They establish 198 * the engineering parameters of the clock discipline loop when 199 * controlled by the PPS signal. 200 */ 201 #define PPS_FAVG 2 /* min freq avg interval (s) (shift) */ 202 #define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */ 203 #define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */ 204 #define PPS_PAVG 4 /* phase avg interval (s) (shift) */ 205 #define PPS_VALID 120 /* PPS signal watchdog max (s) */ 206 #define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */ 207 #define PPS_POPCORN 2 /* popcorn spike threshold (shift) */ 208 209 static struct timespec pps_tf[3]; /* phase median filter */ 210 static l_fp pps_freq; /* scaled frequency offset (ns/s) */ 211 static long pps_fcount; /* frequency accumulator */ 212 static long pps_jitter; /* nominal jitter (ns) */ 213 static long pps_stabil; /* nominal stability (scaled ns/s) */ 214 static long pps_lastsec; /* time at last calibration (s) */ 215 static int pps_valid; /* signal watchdog counter */ 216 static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */ 217 static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */ 218 static int pps_intcnt; /* wander counter */ 219 220 /* 221 * PPS signal quality monitors 222 */ 223 static long pps_calcnt; /* calibration intervals */ 224 static long pps_jitcnt; /* jitter limit exceeded */ 225 static long pps_stbcnt; /* stability limit exceeded */ 226 static long pps_errcnt; /* calibration errors */ 227 #endif /* PPS_SYNC */ 228 /* 229 * End of phase/frequency-lock loop (PLL/FLL) definitions 230 */ 231 232 static void hardupdate(long offset); 233 234 /* 235 * ntp_gettime() - NTP user application interface 236 */ 237 void 238 ntp_gettime(struct ntptimeval *ntv) 239 { 240 memset(ntv, 0, sizeof(*ntv)); 241 242 mutex_spin_enter(&timecounter_lock); 243 nanotime(&ntv->time); 244 ntv->maxerror = time_maxerror; 245 ntv->esterror = time_esterror; 246 ntv->tai = time_tai; 247 ntv->time_state = time_state; 248 mutex_spin_exit(&timecounter_lock); 249 } 250 251 /* ARGSUSED */ 252 /* 253 * ntp_adjtime() - NTP daemon application interface 254 */ 255 int 256 sys_ntp_adjtime(struct lwp *l, const struct sys_ntp_adjtime_args *uap, register_t *retval) 257 { 258 /* { 259 syscallarg(struct timex *) tp; 260 } */ 261 struct timex ntv; 262 int error; 263 264 error = copyin((void *)SCARG(uap, tp), (void *)&ntv, sizeof(ntv)); 265 if (error != 0) 266 return (error); 267 268 if (ntv.modes != 0 && (error = kauth_authorize_system(l->l_cred, 269 KAUTH_SYSTEM_TIME, KAUTH_REQ_SYSTEM_TIME_NTPADJTIME, NULL, 270 NULL, NULL)) != 0) 271 return (error); 272 273 ntp_adjtime1(&ntv); 274 275 error = copyout((void *)&ntv, (void *)SCARG(uap, tp), sizeof(ntv)); 276 if (!error) 277 *retval = ntp_timestatus(); 278 279 return error; 280 } 281 282 void 283 ntp_adjtime1(struct timex *ntv) 284 { 285 long freq; 286 int modes; 287 288 /* 289 * Update selected clock variables - only the superuser can 290 * change anything. Note that there is no error checking here on 291 * the assumption the superuser should know what it is doing. 292 * Note that either the time constant or TAI offset are loaded 293 * from the ntv.constant member, depending on the mode bits. If 294 * the STA_PLL bit in the status word is cleared, the state and 295 * status words are reset to the initial values at boot. 296 */ 297 mutex_spin_enter(&timecounter_lock); 298 modes = ntv->modes; 299 if (modes != 0) 300 /* We need to save the system time during shutdown */ 301 time_adjusted |= 2; 302 if (modes & MOD_MAXERROR) 303 time_maxerror = ntv->maxerror; 304 if (modes & MOD_ESTERROR) 305 time_esterror = ntv->esterror; 306 if (modes & MOD_STATUS) { 307 if (time_status & STA_PLL && !(ntv->status & STA_PLL)) { 308 time_state = TIME_OK; 309 time_status = STA_UNSYNC; 310 #ifdef PPS_SYNC 311 pps_shift = PPS_FAVG; 312 #endif /* PPS_SYNC */ 313 } 314 time_status &= STA_RONLY; 315 time_status |= ntv->status & ~STA_RONLY; 316 } 317 if (modes & MOD_TIMECONST) { 318 if (ntv->constant < 0) 319 time_constant = 0; 320 else if (ntv->constant > MAXTC) 321 time_constant = MAXTC; 322 else 323 time_constant = ntv->constant; 324 } 325 if (modes & MOD_TAI) { 326 if (ntv->constant > 0) /* XXX zero & negative numbers ? */ 327 time_tai = ntv->constant; 328 } 329 #ifdef PPS_SYNC 330 if (modes & MOD_PPSMAX) { 331 if (ntv->shift < PPS_FAVG) 332 pps_shiftmax = PPS_FAVG; 333 else if (ntv->shift > PPS_FAVGMAX) 334 pps_shiftmax = PPS_FAVGMAX; 335 else 336 pps_shiftmax = ntv->shift; 337 } 338 #endif /* PPS_SYNC */ 339 if (modes & MOD_NANO) 340 time_status |= STA_NANO; 341 if (modes & MOD_MICRO) 342 time_status &= ~STA_NANO; 343 if (modes & MOD_CLKB) 344 time_status |= STA_CLK; 345 if (modes & MOD_CLKA) 346 time_status &= ~STA_CLK; 347 if (modes & MOD_FREQUENCY) { 348 freq = MIN(INT32_MAX, MAX(INT32_MIN, ntv->freq)); 349 freq = (freq * (int64_t)1000) >> 16; 350 if (freq > MAXFREQ) 351 L_LINT(time_freq, MAXFREQ); 352 else if (freq < -MAXFREQ) 353 L_LINT(time_freq, -MAXFREQ); 354 else { 355 /* 356 * ntv.freq is [PPM * 2^16] = [us/s * 2^16] 357 * time_freq is [ns/s * 2^32] 358 */ 359 time_freq = ntv->freq * 1000LL * 65536LL; 360 } 361 #ifdef PPS_SYNC 362 pps_freq = time_freq; 363 #endif /* PPS_SYNC */ 364 } 365 if (modes & MOD_OFFSET) { 366 if (time_status & STA_NANO) { 367 hardupdate(ntv->offset); 368 } else { 369 long offset = ntv->offset; 370 offset = MIN(offset, MAXPHASE/1000); 371 offset = MAX(offset, -MAXPHASE/1000); 372 hardupdate(offset * 1000); 373 } 374 } 375 376 /* 377 * Retrieve all clock variables. Note that the TAI offset is 378 * returned only by ntp_gettime(); 379 */ 380 if (time_status & STA_NANO) 381 ntv->offset = L_GINT(time_offset); 382 else 383 ntv->offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */ 384 if (time_freq < 0) 385 ntv->freq = L_GINT(-((-time_freq / 1000LL) << 16)); 386 else 387 ntv->freq = L_GINT((time_freq / 1000LL) << 16); 388 ntv->maxerror = time_maxerror; 389 ntv->esterror = time_esterror; 390 ntv->status = time_status; 391 ntv->constant = time_constant; 392 if (time_status & STA_NANO) 393 ntv->precision = time_precision; 394 else 395 ntv->precision = time_precision / 1000; 396 ntv->tolerance = MAXFREQ * SCALE_PPM; 397 #ifdef PPS_SYNC 398 ntv->shift = pps_shift; 399 ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16); 400 if (time_status & STA_NANO) 401 ntv->jitter = pps_jitter; 402 else 403 ntv->jitter = pps_jitter / 1000; 404 ntv->stabil = pps_stabil; 405 ntv->calcnt = pps_calcnt; 406 ntv->errcnt = pps_errcnt; 407 ntv->jitcnt = pps_jitcnt; 408 ntv->stbcnt = pps_stbcnt; 409 #endif /* PPS_SYNC */ 410 mutex_spin_exit(&timecounter_lock); 411 } 412 #endif /* NTP */ 413 414 /* 415 * second_overflow() - called after ntp_tick_adjust() 416 * 417 * This routine is ordinarily called immediately following the above 418 * routine ntp_tick_adjust(). While these two routines are normally 419 * combined, they are separated here only for the purposes of 420 * simulation. 421 */ 422 void 423 ntp_update_second(int64_t *adjustment, time_t *newsec) 424 { 425 int tickrate; 426 l_fp ftemp; /* 32/64-bit temporary */ 427 428 KASSERT(mutex_owned(&timecounter_lock)); 429 430 #ifdef NTP 431 432 /* 433 * On rollover of the second both the nanosecond and microsecond 434 * clocks are updated and the state machine cranked as 435 * necessary. The phase adjustment to be used for the next 436 * second is calculated and the maximum error is increased by 437 * the tolerance. 438 */ 439 time_maxerror += MAXFREQ / 1000; 440 441 /* 442 * Leap second processing. If in leap-insert state at 443 * the end of the day, the system clock is set back one 444 * second; if in leap-delete state, the system clock is 445 * set ahead one second. The nano_time() routine or 446 * external clock driver will insure that reported time 447 * is always monotonic. 448 */ 449 switch (time_state) { 450 451 /* 452 * No warning. 453 */ 454 case TIME_OK: 455 if (time_status & STA_INS) 456 time_state = TIME_INS; 457 else if (time_status & STA_DEL) 458 time_state = TIME_DEL; 459 break; 460 461 /* 462 * Insert second 23:59:60 following second 463 * 23:59:59. 464 */ 465 case TIME_INS: 466 if (!(time_status & STA_INS)) 467 time_state = TIME_OK; 468 else if ((*newsec) % 86400 == 0) { 469 (*newsec)--; 470 time_state = TIME_OOP; 471 time_tai++; 472 } 473 break; 474 475 /* 476 * Delete second 23:59:59. 477 */ 478 case TIME_DEL: 479 if (!(time_status & STA_DEL)) 480 time_state = TIME_OK; 481 else if (((*newsec) + 1) % 86400 == 0) { 482 (*newsec)++; 483 time_tai--; 484 time_state = TIME_WAIT; 485 } 486 break; 487 488 /* 489 * Insert second in progress. 490 */ 491 case TIME_OOP: 492 time_state = TIME_WAIT; 493 break; 494 495 /* 496 * Wait for status bits to clear. 497 */ 498 case TIME_WAIT: 499 if (!(time_status & (STA_INS | STA_DEL))) 500 time_state = TIME_OK; 501 } 502 503 /* 504 * Compute the total time adjustment for the next second 505 * in ns. The offset is reduced by a factor depending on 506 * whether the PPS signal is operating. Note that the 507 * value is in effect scaled by the clock frequency, 508 * since the adjustment is added at each tick interrupt. 509 */ 510 ftemp = time_offset; 511 #ifdef PPS_SYNC 512 /* XXX even if PPS signal dies we should finish adjustment ? */ 513 if (time_status & STA_PPSTIME && time_status & 514 STA_PPSSIGNAL) 515 L_RSHIFT(ftemp, pps_shift); 516 else 517 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 518 #else 519 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 520 #endif /* PPS_SYNC */ 521 time_adj = ftemp; 522 L_SUB(time_offset, ftemp); 523 L_ADD(time_adj, time_freq); 524 525 #ifdef PPS_SYNC 526 if (pps_valid > 0) 527 pps_valid--; 528 else 529 time_status &= ~STA_PPSSIGNAL; 530 #endif /* PPS_SYNC */ 531 #else /* !NTP */ 532 L_CLR(time_adj); 533 #endif /* !NTP */ 534 535 /* 536 * Apply any correction from adjtime(2). If more than one second 537 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM) 538 * until the last second is slewed the final < 500 usecs. 539 */ 540 if (time_adjtime != 0) { 541 if (time_adjtime > 1000000) 542 tickrate = 5000; 543 else if (time_adjtime < -1000000) 544 tickrate = -5000; 545 else if (time_adjtime > 500) 546 tickrate = 500; 547 else if (time_adjtime < -500) 548 tickrate = -500; 549 else 550 tickrate = time_adjtime; 551 time_adjtime -= tickrate; 552 L_LINT(ftemp, tickrate * 1000); 553 L_ADD(time_adj, ftemp); 554 } 555 *adjustment = time_adj; 556 } 557 558 /* 559 * ntp_init() - initialize variables and structures 560 * 561 * This routine must be called after the kernel variables hz and tick 562 * are set or changed and before the next tick interrupt. In this 563 * particular implementation, these values are assumed set elsewhere in 564 * the kernel. The design allows the clock frequency and tick interval 565 * to be changed while the system is running. So, this routine should 566 * probably be integrated with the code that does that. 567 */ 568 void 569 ntp_init(void) 570 { 571 572 /* 573 * The following variables are initialized only at startup. Only 574 * those structures not cleared by the compiler need to be 575 * initialized, and these only in the simulator. In the actual 576 * kernel, any nonzero values here will quickly evaporate. 577 */ 578 L_CLR(time_adj); 579 #ifdef NTP 580 L_CLR(time_offset); 581 L_CLR(time_freq); 582 #ifdef PPS_SYNC 583 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0; 584 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0; 585 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0; 586 pps_fcount = 0; 587 L_CLR(pps_freq); 588 #endif /* PPS_SYNC */ 589 #endif 590 } 591 592 #ifdef NTP 593 /* 594 * hardupdate() - local clock update 595 * 596 * This routine is called by ntp_adjtime() to update the local clock 597 * phase and frequency. The implementation is of an adaptive-parameter, 598 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new 599 * time and frequency offset estimates for each call. If the kernel PPS 600 * discipline code is configured (PPS_SYNC), the PPS signal itself 601 * determines the new time offset, instead of the calling argument. 602 * Presumably, calls to ntp_adjtime() occur only when the caller 603 * believes the local clock is valid within some bound (+-128 ms with 604 * NTP). If the caller's time is far different than the PPS time, an 605 * argument will ensue, and it's not clear who will lose. 606 * 607 * For uncompensated quartz crystal oscillators and nominal update 608 * intervals less than 256 s, operation should be in phase-lock mode, 609 * where the loop is disciplined to phase. For update intervals greater 610 * than 1024 s, operation should be in frequency-lock mode, where the 611 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode 612 * is selected by the STA_MODE status bit. 613 * 614 * Note: splclock() is in effect. 615 */ 616 void 617 hardupdate(long offset) 618 { 619 long mtemp; 620 l_fp ftemp; 621 622 KASSERT(mutex_owned(&timecounter_lock)); 623 624 /* 625 * Select how the phase is to be controlled and from which 626 * source. If the PPS signal is present and enabled to 627 * discipline the time, the PPS offset is used; otherwise, the 628 * argument offset is used. 629 */ 630 if (!(time_status & STA_PLL)) 631 return; 632 if (!(time_status & STA_PPSTIME && time_status & 633 STA_PPSSIGNAL)) { 634 if (offset > MAXPHASE) 635 time_monitor = MAXPHASE; 636 else if (offset < -MAXPHASE) 637 time_monitor = -MAXPHASE; 638 else 639 time_monitor = offset; 640 L_LINT(time_offset, time_monitor); 641 } 642 643 /* 644 * Select how the frequency is to be controlled and in which 645 * mode (PLL or FLL). If the PPS signal is present and enabled 646 * to discipline the frequency, the PPS frequency is used; 647 * otherwise, the argument offset is used to compute it. 648 */ 649 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) { 650 time_reftime = time_second; 651 return; 652 } 653 if (time_status & STA_FREQHOLD || time_reftime == 0) 654 time_reftime = time_second; 655 mtemp = time_second - time_reftime; 656 L_LINT(ftemp, time_monitor); 657 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); 658 L_MPY(ftemp, mtemp); 659 L_ADD(time_freq, ftemp); 660 time_status &= ~STA_MODE; 661 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > 662 MAXSEC)) { 663 L_LINT(ftemp, (time_monitor << 4) / mtemp); 664 L_RSHIFT(ftemp, SHIFT_FLL + 4); 665 L_ADD(time_freq, ftemp); 666 time_status |= STA_MODE; 667 } 668 time_reftime = time_second; 669 if (L_GINT(time_freq) > MAXFREQ) 670 L_LINT(time_freq, MAXFREQ); 671 else if (L_GINT(time_freq) < -MAXFREQ) 672 L_LINT(time_freq, -MAXFREQ); 673 } 674 675 #ifdef PPS_SYNC 676 /* 677 * hardpps() - discipline CPU clock oscillator to external PPS signal 678 * 679 * This routine is called at each PPS interrupt in order to discipline 680 * the CPU clock oscillator to the PPS signal. It measures the PPS phase 681 * and leaves it in a handy spot for the hardclock() routine. It 682 * integrates successive PPS phase differences and calculates the 683 * frequency offset. This is used in hardclock() to discipline the CPU 684 * clock oscillator so that intrinsic frequency error is cancelled out. 685 * The code requires the caller to capture the time and hardware counter 686 * value at the on-time PPS signal transition. 687 * 688 * Note that, on some Unix systems, this routine runs at an interrupt 689 * priority level higher than the timer interrupt routine hardclock(). 690 * Therefore, the variables used are distinct from the hardclock() 691 * variables, except for certain exceptions: The PPS frequency pps_freq 692 * and phase pps_offset variables are determined by this routine and 693 * updated atomically. The time_tolerance variable can be considered a 694 * constant, since it is infrequently changed, and then only when the 695 * PPS signal is disabled. The watchdog counter pps_valid is updated 696 * once per second by hardclock() and is atomically cleared in this 697 * routine. 698 */ 699 void 700 hardpps(struct timespec *tsp, /* time at PPS */ 701 long nsec /* hardware counter at PPS */) 702 { 703 long u_sec, u_nsec, v_nsec; /* temps */ 704 l_fp ftemp; 705 706 KASSERT(mutex_owned(&timecounter_lock)); 707 708 /* 709 * The signal is first processed by a range gate and frequency 710 * discriminator. The range gate rejects noise spikes outside 711 * the range +-500 us. The frequency discriminator rejects input 712 * signals with apparent frequency outside the range 1 +-500 713 * PPM. If two hits occur in the same second, we ignore the 714 * later hit; if not and a hit occurs outside the range gate, 715 * keep the later hit for later comparison, but do not process 716 * it. 717 */ 718 time_status |= STA_PPSSIGNAL | STA_PPSJITTER; 719 time_status &= ~(STA_PPSWANDER | STA_PPSERROR); 720 pps_valid = PPS_VALID; 721 u_sec = tsp->tv_sec; 722 u_nsec = tsp->tv_nsec; 723 if (u_nsec >= (NANOSECOND >> 1)) { 724 u_nsec -= NANOSECOND; 725 u_sec++; 726 } 727 v_nsec = u_nsec - pps_tf[0].tv_nsec; 728 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - 729 MAXFREQ) 730 return; 731 pps_tf[2] = pps_tf[1]; 732 pps_tf[1] = pps_tf[0]; 733 pps_tf[0].tv_sec = u_sec; 734 pps_tf[0].tv_nsec = u_nsec; 735 736 /* 737 * Compute the difference between the current and previous 738 * counter values. If the difference exceeds 0.5 s, assume it 739 * has wrapped around, so correct 1.0 s. If the result exceeds 740 * the tick interval, the sample point has crossed a tick 741 * boundary during the last second, so correct the tick. Very 742 * intricate. 743 */ 744 u_nsec = nsec; 745 if (u_nsec > (NANOSECOND >> 1)) 746 u_nsec -= NANOSECOND; 747 else if (u_nsec < -(NANOSECOND >> 1)) 748 u_nsec += NANOSECOND; 749 pps_fcount += u_nsec; 750 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) 751 return; 752 time_status &= ~STA_PPSJITTER; 753 754 /* 755 * A three-stage median filter is used to help denoise the PPS 756 * time. The median sample becomes the time offset estimate; the 757 * difference between the other two samples becomes the time 758 * dispersion (jitter) estimate. 759 */ 760 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { 761 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { 762 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ 763 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; 764 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { 765 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ 766 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; 767 } else { 768 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ 769 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; 770 } 771 } else { 772 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { 773 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ 774 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; 775 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { 776 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ 777 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; 778 } else { 779 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ 780 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; 781 } 782 } 783 784 /* 785 * Nominal jitter is due to PPS signal noise and interrupt 786 * latency. If it exceeds the popcorn threshold, the sample is 787 * discarded. otherwise, if so enabled, the time offset is 788 * updated. We can tolerate a modest loss of data here without 789 * much degrading time accuracy. 790 */ 791 if (u_nsec > (pps_jitter << PPS_POPCORN)) { 792 time_status |= STA_PPSJITTER; 793 pps_jitcnt++; 794 } else if (time_status & STA_PPSTIME) { 795 time_monitor = -v_nsec; 796 L_LINT(time_offset, time_monitor); 797 } 798 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; 799 u_sec = pps_tf[0].tv_sec - pps_lastsec; 800 if (u_sec < (1 << pps_shift)) 801 return; 802 803 /* 804 * At the end of the calibration interval the difference between 805 * the first and last counter values becomes the scaled 806 * frequency. It will later be divided by the length of the 807 * interval to determine the frequency update. If the frequency 808 * exceeds a sanity threshold, or if the actual calibration 809 * interval is not equal to the expected length, the data are 810 * discarded. We can tolerate a modest loss of data here without 811 * much degrading frequency accuracy. 812 */ 813 pps_calcnt++; 814 v_nsec = -pps_fcount; 815 pps_lastsec = pps_tf[0].tv_sec; 816 pps_fcount = 0; 817 u_nsec = MAXFREQ << pps_shift; 818 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << 819 pps_shift)) { 820 time_status |= STA_PPSERROR; 821 pps_errcnt++; 822 return; 823 } 824 825 /* 826 * Here the raw frequency offset and wander (stability) is 827 * calculated. If the wander is less than the wander threshold 828 * for four consecutive averaging intervals, the interval is 829 * doubled; if it is greater than the threshold for four 830 * consecutive intervals, the interval is halved. The scaled 831 * frequency offset is converted to frequency offset. The 832 * stability metric is calculated as the average of recent 833 * frequency changes, but is used only for performance 834 * monitoring. 835 */ 836 L_LINT(ftemp, v_nsec); 837 L_RSHIFT(ftemp, pps_shift); 838 L_SUB(ftemp, pps_freq); 839 u_nsec = L_GINT(ftemp); 840 if (u_nsec > PPS_MAXWANDER) { 841 L_LINT(ftemp, PPS_MAXWANDER); 842 pps_intcnt--; 843 time_status |= STA_PPSWANDER; 844 pps_stbcnt++; 845 } else if (u_nsec < -PPS_MAXWANDER) { 846 L_LINT(ftemp, -PPS_MAXWANDER); 847 pps_intcnt--; 848 time_status |= STA_PPSWANDER; 849 pps_stbcnt++; 850 } else { 851 pps_intcnt++; 852 } 853 if (pps_intcnt >= 4) { 854 pps_intcnt = 4; 855 if (pps_shift < pps_shiftmax) { 856 pps_shift++; 857 pps_intcnt = 0; 858 } 859 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { 860 pps_intcnt = -4; 861 if (pps_shift > PPS_FAVG) { 862 pps_shift--; 863 pps_intcnt = 0; 864 } 865 } 866 if (u_nsec < 0) 867 u_nsec = -u_nsec; 868 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; 869 870 /* 871 * The PPS frequency is recalculated and clamped to the maximum 872 * MAXFREQ. If enabled, the system clock frequency is updated as 873 * well. 874 */ 875 L_ADD(pps_freq, ftemp); 876 u_nsec = L_GINT(pps_freq); 877 if (u_nsec > MAXFREQ) 878 L_LINT(pps_freq, MAXFREQ); 879 else if (u_nsec < -MAXFREQ) 880 L_LINT(pps_freq, -MAXFREQ); 881 if (time_status & STA_PPSFREQ) 882 time_freq = pps_freq; 883 } 884 #endif /* PPS_SYNC */ 885 #endif /* NTP */ 886 887 #ifdef NTP 888 int 889 ntp_timestatus(void) 890 { 891 int rv; 892 893 /* 894 * Status word error decode. If any of these conditions 895 * occur, an error is returned, instead of the status 896 * word. Most applications will care only about the fact 897 * the system clock may not be trusted, not about the 898 * details. 899 * 900 * Hardware or software error 901 */ 902 mutex_spin_enter(&timecounter_lock); 903 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 904 905 /* 906 * PPS signal lost when either time or frequency 907 * synchronization requested 908 */ 909 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 910 !(time_status & STA_PPSSIGNAL)) || 911 912 /* 913 * PPS jitter exceeded when time synchronization 914 * requested 915 */ 916 (time_status & STA_PPSTIME && 917 time_status & STA_PPSJITTER) || 918 919 /* 920 * PPS wander exceeded or calibration error when 921 * frequency synchronization requested 922 */ 923 (time_status & STA_PPSFREQ && 924 time_status & (STA_PPSWANDER | STA_PPSERROR))) 925 rv = TIME_ERROR; 926 else 927 rv = time_state; 928 mutex_spin_exit(&timecounter_lock); 929 930 return rv; 931 } 932 933 /*ARGSUSED*/ 934 /* 935 * ntp_gettime() - NTP user application interface 936 */ 937 int 938 sys___ntp_gettime50(struct lwp *l, const struct sys___ntp_gettime50_args *uap, register_t *retval) 939 { 940 /* { 941 syscallarg(struct ntptimeval *) ntvp; 942 } */ 943 struct ntptimeval ntv; 944 int error = 0; 945 946 if (SCARG(uap, ntvp)) { 947 ntp_gettime(&ntv); 948 949 error = copyout((void *)&ntv, (void *)SCARG(uap, ntvp), 950 sizeof(ntv)); 951 } 952 if (!error) { 953 *retval = ntp_timestatus(); 954 } 955 return(error); 956 } 957 958 /* 959 * return information about kernel precision timekeeping 960 */ 961 static int 962 sysctl_kern_ntptime(SYSCTLFN_ARGS) 963 { 964 struct sysctlnode node; 965 struct ntptimeval ntv; 966 967 ntp_gettime(&ntv); 968 969 node = *rnode; 970 node.sysctl_data = &ntv; 971 node.sysctl_size = sizeof(ntv); 972 return (sysctl_lookup(SYSCTLFN_CALL(&node))); 973 } 974 975 SYSCTL_SETUP(sysctl_kern_ntptime_setup, "sysctl kern.ntptime node setup") 976 { 977 978 sysctl_createv(clog, 0, NULL, NULL, 979 CTLFLAG_PERMANENT, 980 CTLTYPE_STRUCT, "ntptime", 981 SYSCTL_DESCR("Kernel clock values for NTP"), 982 sysctl_kern_ntptime, 0, NULL, 983 sizeof(struct ntptimeval), 984 CTL_KERN, KERN_NTPTIME, CTL_EOL); 985 } 986 #endif /* !NTP */ 987