1 /* $NetBSD: kern_ntptime.c,v 1.60 2018/10/29 22:02:25 christos 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 1.60 2018/10/29 22:02:25 christos 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 = (ntv->freq * 1000LL) >> 16; 351 if (freq > MAXFREQ) 352 L_LINT(time_freq, MAXFREQ); 353 else if (freq < -MAXFREQ) 354 L_LINT(time_freq, -MAXFREQ); 355 else { 356 /* 357 * ntv.freq is [PPM * 2^16] = [us/s * 2^16] 358 * time_freq is [ns/s * 2^32] 359 */ 360 time_freq = ntv->freq * 1000LL * 65536LL; 361 } 362 #ifdef PPS_SYNC 363 pps_freq = time_freq; 364 #endif /* PPS_SYNC */ 365 } 366 if (modes & MOD_OFFSET) { 367 if (time_status & STA_NANO) 368 hardupdate(ntv->offset); 369 else 370 hardupdate(ntv->offset * 1000); 371 } 372 373 /* 374 * Retrieve all clock variables. Note that the TAI offset is 375 * returned only by ntp_gettime(); 376 */ 377 if (time_status & STA_NANO) 378 ntv->offset = L_GINT(time_offset); 379 else 380 ntv->offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */ 381 ntv->freq = L_GINT((time_freq / 1000LL) << 16); 382 ntv->maxerror = time_maxerror; 383 ntv->esterror = time_esterror; 384 ntv->status = time_status; 385 ntv->constant = time_constant; 386 if (time_status & STA_NANO) 387 ntv->precision = time_precision; 388 else 389 ntv->precision = time_precision / 1000; 390 ntv->tolerance = MAXFREQ * SCALE_PPM; 391 #ifdef PPS_SYNC 392 ntv->shift = pps_shift; 393 ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16); 394 if (time_status & STA_NANO) 395 ntv->jitter = pps_jitter; 396 else 397 ntv->jitter = pps_jitter / 1000; 398 ntv->stabil = pps_stabil; 399 ntv->calcnt = pps_calcnt; 400 ntv->errcnt = pps_errcnt; 401 ntv->jitcnt = pps_jitcnt; 402 ntv->stbcnt = pps_stbcnt; 403 #endif /* PPS_SYNC */ 404 mutex_spin_exit(&timecounter_lock); 405 } 406 #endif /* NTP */ 407 408 /* 409 * second_overflow() - called after ntp_tick_adjust() 410 * 411 * This routine is ordinarily called immediately following the above 412 * routine ntp_tick_adjust(). While these two routines are normally 413 * combined, they are separated here only for the purposes of 414 * simulation. 415 */ 416 void 417 ntp_update_second(int64_t *adjustment, time_t *newsec) 418 { 419 int tickrate; 420 l_fp ftemp; /* 32/64-bit temporary */ 421 422 KASSERT(mutex_owned(&timecounter_lock)); 423 424 #ifdef NTP 425 426 /* 427 * On rollover of the second both the nanosecond and microsecond 428 * clocks are updated and the state machine cranked as 429 * necessary. The phase adjustment to be used for the next 430 * second is calculated and the maximum error is increased by 431 * the tolerance. 432 */ 433 time_maxerror += MAXFREQ / 1000; 434 435 /* 436 * Leap second processing. If in leap-insert state at 437 * the end of the day, the system clock is set back one 438 * second; if in leap-delete state, the system clock is 439 * set ahead one second. The nano_time() routine or 440 * external clock driver will insure that reported time 441 * is always monotonic. 442 */ 443 switch (time_state) { 444 445 /* 446 * No warning. 447 */ 448 case TIME_OK: 449 if (time_status & STA_INS) 450 time_state = TIME_INS; 451 else if (time_status & STA_DEL) 452 time_state = TIME_DEL; 453 break; 454 455 /* 456 * Insert second 23:59:60 following second 457 * 23:59:59. 458 */ 459 case TIME_INS: 460 if (!(time_status & STA_INS)) 461 time_state = TIME_OK; 462 else if ((*newsec) % 86400 == 0) { 463 (*newsec)--; 464 time_state = TIME_OOP; 465 time_tai++; 466 } 467 break; 468 469 /* 470 * Delete second 23:59:59. 471 */ 472 case TIME_DEL: 473 if (!(time_status & STA_DEL)) 474 time_state = TIME_OK; 475 else if (((*newsec) + 1) % 86400 == 0) { 476 (*newsec)++; 477 time_tai--; 478 time_state = TIME_WAIT; 479 } 480 break; 481 482 /* 483 * Insert second in progress. 484 */ 485 case TIME_OOP: 486 time_state = TIME_WAIT; 487 break; 488 489 /* 490 * Wait for status bits to clear. 491 */ 492 case TIME_WAIT: 493 if (!(time_status & (STA_INS | STA_DEL))) 494 time_state = TIME_OK; 495 } 496 497 /* 498 * Compute the total time adjustment for the next second 499 * in ns. The offset is reduced by a factor depending on 500 * whether the PPS signal is operating. Note that the 501 * value is in effect scaled by the clock frequency, 502 * since the adjustment is added at each tick interrupt. 503 */ 504 ftemp = time_offset; 505 #ifdef PPS_SYNC 506 /* XXX even if PPS signal dies we should finish adjustment ? */ 507 if (time_status & STA_PPSTIME && time_status & 508 STA_PPSSIGNAL) 509 L_RSHIFT(ftemp, pps_shift); 510 else 511 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 512 #else 513 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 514 #endif /* PPS_SYNC */ 515 time_adj = ftemp; 516 L_SUB(time_offset, ftemp); 517 L_ADD(time_adj, time_freq); 518 519 #ifdef PPS_SYNC 520 if (pps_valid > 0) 521 pps_valid--; 522 else 523 time_status &= ~STA_PPSSIGNAL; 524 #endif /* PPS_SYNC */ 525 #else /* !NTP */ 526 L_CLR(time_adj); 527 #endif /* !NTP */ 528 529 /* 530 * Apply any correction from adjtime(2). If more than one second 531 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM) 532 * until the last second is slewed the final < 500 usecs. 533 */ 534 if (time_adjtime != 0) { 535 if (time_adjtime > 1000000) 536 tickrate = 5000; 537 else if (time_adjtime < -1000000) 538 tickrate = -5000; 539 else if (time_adjtime > 500) 540 tickrate = 500; 541 else if (time_adjtime < -500) 542 tickrate = -500; 543 else 544 tickrate = time_adjtime; 545 time_adjtime -= tickrate; 546 L_LINT(ftemp, tickrate * 1000); 547 L_ADD(time_adj, ftemp); 548 } 549 *adjustment = time_adj; 550 } 551 552 /* 553 * ntp_init() - initialize variables and structures 554 * 555 * This routine must be called after the kernel variables hz and tick 556 * are set or changed and before the next tick interrupt. In this 557 * particular implementation, these values are assumed set elsewhere in 558 * the kernel. The design allows the clock frequency and tick interval 559 * to be changed while the system is running. So, this routine should 560 * probably be integrated with the code that does that. 561 */ 562 void 563 ntp_init(void) 564 { 565 566 /* 567 * The following variables are initialized only at startup. Only 568 * those structures not cleared by the compiler need to be 569 * initialized, and these only in the simulator. In the actual 570 * kernel, any nonzero values here will quickly evaporate. 571 */ 572 L_CLR(time_adj); 573 #ifdef NTP 574 L_CLR(time_offset); 575 L_CLR(time_freq); 576 #ifdef PPS_SYNC 577 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0; 578 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0; 579 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0; 580 pps_fcount = 0; 581 L_CLR(pps_freq); 582 #endif /* PPS_SYNC */ 583 #endif 584 } 585 586 #ifdef NTP 587 /* 588 * hardupdate() - local clock update 589 * 590 * This routine is called by ntp_adjtime() to update the local clock 591 * phase and frequency. The implementation is of an adaptive-parameter, 592 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new 593 * time and frequency offset estimates for each call. If the kernel PPS 594 * discipline code is configured (PPS_SYNC), the PPS signal itself 595 * determines the new time offset, instead of the calling argument. 596 * Presumably, calls to ntp_adjtime() occur only when the caller 597 * believes the local clock is valid within some bound (+-128 ms with 598 * NTP). If the caller's time is far different than the PPS time, an 599 * argument will ensue, and it's not clear who will lose. 600 * 601 * For uncompensated quartz crystal oscillators and nominal update 602 * intervals less than 256 s, operation should be in phase-lock mode, 603 * where the loop is disciplined to phase. For update intervals greater 604 * than 1024 s, operation should be in frequency-lock mode, where the 605 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode 606 * is selected by the STA_MODE status bit. 607 * 608 * Note: splclock() is in effect. 609 */ 610 void 611 hardupdate(long offset) 612 { 613 long mtemp; 614 l_fp ftemp; 615 616 KASSERT(mutex_owned(&timecounter_lock)); 617 618 /* 619 * Select how the phase is to be controlled and from which 620 * source. If the PPS signal is present and enabled to 621 * discipline the time, the PPS offset is used; otherwise, the 622 * argument offset is used. 623 */ 624 if (!(time_status & STA_PLL)) 625 return; 626 if (!(time_status & STA_PPSTIME && time_status & 627 STA_PPSSIGNAL)) { 628 if (offset > MAXPHASE) 629 time_monitor = MAXPHASE; 630 else if (offset < -MAXPHASE) 631 time_monitor = -MAXPHASE; 632 else 633 time_monitor = offset; 634 L_LINT(time_offset, time_monitor); 635 } 636 637 /* 638 * Select how the frequency is to be controlled and in which 639 * mode (PLL or FLL). If the PPS signal is present and enabled 640 * to discipline the frequency, the PPS frequency is used; 641 * otherwise, the argument offset is used to compute it. 642 */ 643 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) { 644 time_reftime = time_second; 645 return; 646 } 647 if (time_status & STA_FREQHOLD || time_reftime == 0) 648 time_reftime = time_second; 649 mtemp = time_second - time_reftime; 650 L_LINT(ftemp, time_monitor); 651 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); 652 L_MPY(ftemp, mtemp); 653 L_ADD(time_freq, ftemp); 654 time_status &= ~STA_MODE; 655 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > 656 MAXSEC)) { 657 L_LINT(ftemp, (time_monitor << 4) / mtemp); 658 L_RSHIFT(ftemp, SHIFT_FLL + 4); 659 L_ADD(time_freq, ftemp); 660 time_status |= STA_MODE; 661 } 662 time_reftime = time_second; 663 if (L_GINT(time_freq) > MAXFREQ) 664 L_LINT(time_freq, MAXFREQ); 665 else if (L_GINT(time_freq) < -MAXFREQ) 666 L_LINT(time_freq, -MAXFREQ); 667 } 668 669 #ifdef PPS_SYNC 670 /* 671 * hardpps() - discipline CPU clock oscillator to external PPS signal 672 * 673 * This routine is called at each PPS interrupt in order to discipline 674 * the CPU clock oscillator to the PPS signal. It measures the PPS phase 675 * and leaves it in a handy spot for the hardclock() routine. It 676 * integrates successive PPS phase differences and calculates the 677 * frequency offset. This is used in hardclock() to discipline the CPU 678 * clock oscillator so that intrinsic frequency error is cancelled out. 679 * The code requires the caller to capture the time and hardware counter 680 * value at the on-time PPS signal transition. 681 * 682 * Note that, on some Unix systems, this routine runs at an interrupt 683 * priority level higher than the timer interrupt routine hardclock(). 684 * Therefore, the variables used are distinct from the hardclock() 685 * variables, except for certain exceptions: The PPS frequency pps_freq 686 * and phase pps_offset variables are determined by this routine and 687 * updated atomically. The time_tolerance variable can be considered a 688 * constant, since it is infrequently changed, and then only when the 689 * PPS signal is disabled. The watchdog counter pps_valid is updated 690 * once per second by hardclock() and is atomically cleared in this 691 * routine. 692 */ 693 void 694 hardpps(struct timespec *tsp, /* time at PPS */ 695 long nsec /* hardware counter at PPS */) 696 { 697 long u_sec, u_nsec, v_nsec; /* temps */ 698 l_fp ftemp; 699 700 KASSERT(mutex_owned(&timecounter_lock)); 701 702 /* 703 * The signal is first processed by a range gate and frequency 704 * discriminator. The range gate rejects noise spikes outside 705 * the range +-500 us. The frequency discriminator rejects input 706 * signals with apparent frequency outside the range 1 +-500 707 * PPM. If two hits occur in the same second, we ignore the 708 * later hit; if not and a hit occurs outside the range gate, 709 * keep the later hit for later comparison, but do not process 710 * it. 711 */ 712 time_status |= STA_PPSSIGNAL | STA_PPSJITTER; 713 time_status &= ~(STA_PPSWANDER | STA_PPSERROR); 714 pps_valid = PPS_VALID; 715 u_sec = tsp->tv_sec; 716 u_nsec = tsp->tv_nsec; 717 if (u_nsec >= (NANOSECOND >> 1)) { 718 u_nsec -= NANOSECOND; 719 u_sec++; 720 } 721 v_nsec = u_nsec - pps_tf[0].tv_nsec; 722 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - 723 MAXFREQ) 724 return; 725 pps_tf[2] = pps_tf[1]; 726 pps_tf[1] = pps_tf[0]; 727 pps_tf[0].tv_sec = u_sec; 728 pps_tf[0].tv_nsec = u_nsec; 729 730 /* 731 * Compute the difference between the current and previous 732 * counter values. If the difference exceeds 0.5 s, assume it 733 * has wrapped around, so correct 1.0 s. If the result exceeds 734 * the tick interval, the sample point has crossed a tick 735 * boundary during the last second, so correct the tick. Very 736 * intricate. 737 */ 738 u_nsec = nsec; 739 if (u_nsec > (NANOSECOND >> 1)) 740 u_nsec -= NANOSECOND; 741 else if (u_nsec < -(NANOSECOND >> 1)) 742 u_nsec += NANOSECOND; 743 pps_fcount += u_nsec; 744 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) 745 return; 746 time_status &= ~STA_PPSJITTER; 747 748 /* 749 * A three-stage median filter is used to help denoise the PPS 750 * time. The median sample becomes the time offset estimate; the 751 * difference between the other two samples becomes the time 752 * dispersion (jitter) estimate. 753 */ 754 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { 755 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { 756 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ 757 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; 758 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { 759 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ 760 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; 761 } else { 762 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ 763 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; 764 } 765 } else { 766 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { 767 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ 768 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; 769 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { 770 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ 771 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; 772 } else { 773 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ 774 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; 775 } 776 } 777 778 /* 779 * Nominal jitter is due to PPS signal noise and interrupt 780 * latency. If it exceeds the popcorn threshold, the sample is 781 * discarded. otherwise, if so enabled, the time offset is 782 * updated. We can tolerate a modest loss of data here without 783 * much degrading time accuracy. 784 */ 785 if (u_nsec > (pps_jitter << PPS_POPCORN)) { 786 time_status |= STA_PPSJITTER; 787 pps_jitcnt++; 788 } else if (time_status & STA_PPSTIME) { 789 time_monitor = -v_nsec; 790 L_LINT(time_offset, time_monitor); 791 } 792 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; 793 u_sec = pps_tf[0].tv_sec - pps_lastsec; 794 if (u_sec < (1 << pps_shift)) 795 return; 796 797 /* 798 * At the end of the calibration interval the difference between 799 * the first and last counter values becomes the scaled 800 * frequency. It will later be divided by the length of the 801 * interval to determine the frequency update. If the frequency 802 * exceeds a sanity threshold, or if the actual calibration 803 * interval is not equal to the expected length, the data are 804 * discarded. We can tolerate a modest loss of data here without 805 * much degrading frequency accuracy. 806 */ 807 pps_calcnt++; 808 v_nsec = -pps_fcount; 809 pps_lastsec = pps_tf[0].tv_sec; 810 pps_fcount = 0; 811 u_nsec = MAXFREQ << pps_shift; 812 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << 813 pps_shift)) { 814 time_status |= STA_PPSERROR; 815 pps_errcnt++; 816 return; 817 } 818 819 /* 820 * Here the raw frequency offset and wander (stability) is 821 * calculated. If the wander is less than the wander threshold 822 * for four consecutive averaging intervals, the interval is 823 * doubled; if it is greater than the threshold for four 824 * consecutive intervals, the interval is halved. The scaled 825 * frequency offset is converted to frequency offset. The 826 * stability metric is calculated as the average of recent 827 * frequency changes, but is used only for performance 828 * monitoring. 829 */ 830 L_LINT(ftemp, v_nsec); 831 L_RSHIFT(ftemp, pps_shift); 832 L_SUB(ftemp, pps_freq); 833 u_nsec = L_GINT(ftemp); 834 if (u_nsec > PPS_MAXWANDER) { 835 L_LINT(ftemp, PPS_MAXWANDER); 836 pps_intcnt--; 837 time_status |= STA_PPSWANDER; 838 pps_stbcnt++; 839 } else if (u_nsec < -PPS_MAXWANDER) { 840 L_LINT(ftemp, -PPS_MAXWANDER); 841 pps_intcnt--; 842 time_status |= STA_PPSWANDER; 843 pps_stbcnt++; 844 } else { 845 pps_intcnt++; 846 } 847 if (pps_intcnt >= 4) { 848 pps_intcnt = 4; 849 if (pps_shift < pps_shiftmax) { 850 pps_shift++; 851 pps_intcnt = 0; 852 } 853 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { 854 pps_intcnt = -4; 855 if (pps_shift > PPS_FAVG) { 856 pps_shift--; 857 pps_intcnt = 0; 858 } 859 } 860 if (u_nsec < 0) 861 u_nsec = -u_nsec; 862 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; 863 864 /* 865 * The PPS frequency is recalculated and clamped to the maximum 866 * MAXFREQ. If enabled, the system clock frequency is updated as 867 * well. 868 */ 869 L_ADD(pps_freq, ftemp); 870 u_nsec = L_GINT(pps_freq); 871 if (u_nsec > MAXFREQ) 872 L_LINT(pps_freq, MAXFREQ); 873 else if (u_nsec < -MAXFREQ) 874 L_LINT(pps_freq, -MAXFREQ); 875 if (time_status & STA_PPSFREQ) 876 time_freq = pps_freq; 877 } 878 #endif /* PPS_SYNC */ 879 #endif /* NTP */ 880 881 #ifdef NTP 882 int 883 ntp_timestatus(void) 884 { 885 int rv; 886 887 /* 888 * Status word error decode. If any of these conditions 889 * occur, an error is returned, instead of the status 890 * word. Most applications will care only about the fact 891 * the system clock may not be trusted, not about the 892 * details. 893 * 894 * Hardware or software error 895 */ 896 mutex_spin_enter(&timecounter_lock); 897 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 898 899 /* 900 * PPS signal lost when either time or frequency 901 * synchronization requested 902 */ 903 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 904 !(time_status & STA_PPSSIGNAL)) || 905 906 /* 907 * PPS jitter exceeded when time synchronization 908 * requested 909 */ 910 (time_status & STA_PPSTIME && 911 time_status & STA_PPSJITTER) || 912 913 /* 914 * PPS wander exceeded or calibration error when 915 * frequency synchronization requested 916 */ 917 (time_status & STA_PPSFREQ && 918 time_status & (STA_PPSWANDER | STA_PPSERROR))) 919 rv = TIME_ERROR; 920 else 921 rv = time_state; 922 mutex_spin_exit(&timecounter_lock); 923 924 return rv; 925 } 926 927 /*ARGSUSED*/ 928 /* 929 * ntp_gettime() - NTP user application interface 930 */ 931 int 932 sys___ntp_gettime50(struct lwp *l, const struct sys___ntp_gettime50_args *uap, register_t *retval) 933 { 934 /* { 935 syscallarg(struct ntptimeval *) ntvp; 936 } */ 937 struct ntptimeval ntv; 938 int error = 0; 939 940 if (SCARG(uap, ntvp)) { 941 ntp_gettime(&ntv); 942 943 error = copyout((void *)&ntv, (void *)SCARG(uap, ntvp), 944 sizeof(ntv)); 945 } 946 if (!error) { 947 *retval = ntp_timestatus(); 948 } 949 return(error); 950 } 951 952 /* 953 * return information about kernel precision timekeeping 954 */ 955 static int 956 sysctl_kern_ntptime(SYSCTLFN_ARGS) 957 { 958 struct sysctlnode node; 959 struct ntptimeval ntv; 960 961 ntp_gettime(&ntv); 962 963 node = *rnode; 964 node.sysctl_data = &ntv; 965 node.sysctl_size = sizeof(ntv); 966 return (sysctl_lookup(SYSCTLFN_CALL(&node))); 967 } 968 969 SYSCTL_SETUP(sysctl_kern_ntptime_setup, "sysctl kern.ntptime node setup") 970 { 971 972 sysctl_createv(clog, 0, NULL, NULL, 973 CTLFLAG_PERMANENT, 974 CTLTYPE_STRUCT, "ntptime", 975 SYSCTL_DESCR("Kernel clock values for NTP"), 976 sysctl_kern_ntptime, 0, NULL, 977 sizeof(struct ntptimeval), 978 CTL_KERN, KERN_NTPTIME, CTL_EOL); 979 } 980 #endif /* !NTP */ 981