1 /* $NetBSD: kern_ntptime.c,v 1.54 2010/04/13 22:46:10 pooka 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 1.54 2010/04/13 22:46:10 pooka 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)(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 { 242 243 mutex_spin_enter(&timecounter_lock); 244 nanotime(&ntv->time); 245 ntv->maxerror = time_maxerror; 246 ntv->esterror = time_esterror; 247 ntv->tai = time_tai; 248 ntv->time_state = time_state; 249 mutex_spin_exit(&timecounter_lock); 250 } 251 252 /* ARGSUSED */ 253 /* 254 * ntp_adjtime() - NTP daemon application interface 255 */ 256 int 257 sys_ntp_adjtime(struct lwp *l, const struct sys_ntp_adjtime_args *uap, register_t *retval) 258 { 259 /* { 260 syscallarg(struct timex *) tp; 261 } */ 262 struct timex ntv; 263 int error = 0; 264 265 error = copyin((void *)SCARG(uap, tp), (void *)&ntv, sizeof(ntv)); 266 if (error != 0) 267 return (error); 268 269 if (ntv.modes != 0 && (error = kauth_authorize_system(l->l_cred, 270 KAUTH_SYSTEM_TIME, KAUTH_REQ_SYSTEM_TIME_NTPADJTIME, NULL, 271 NULL, NULL)) != 0) 272 return (error); 273 274 ntp_adjtime1(&ntv); 275 276 error = copyout((void *)&ntv, (void *)SCARG(uap, tp), sizeof(ntv)); 277 if (!error) 278 *retval = ntp_timestatus(); 279 280 return error; 281 } 282 283 void 284 ntp_adjtime1(struct timex *ntv) 285 { 286 long freq; 287 int modes; 288 289 /* 290 * Update selected clock variables - only the superuser can 291 * change anything. Note that there is no error checking here on 292 * the assumption the superuser should know what it is doing. 293 * Note that either the time constant or TAI offset are loaded 294 * from the ntv.constant member, depending on the mode bits. If 295 * the STA_PLL bit in the status word is cleared, the state and 296 * status words are reset to the initial values at boot. 297 */ 298 mutex_spin_enter(&timecounter_lock); 299 modes = ntv->modes; 300 if (modes != 0) 301 /* We need to save the system time during shutdown */ 302 time_adjusted |= 2; 303 if (modes & MOD_MAXERROR) 304 time_maxerror = ntv->maxerror; 305 if (modes & MOD_ESTERROR) 306 time_esterror = ntv->esterror; 307 if (modes & MOD_STATUS) { 308 if (time_status & STA_PLL && !(ntv->status & STA_PLL)) { 309 time_state = TIME_OK; 310 time_status = STA_UNSYNC; 311 #ifdef PPS_SYNC 312 pps_shift = PPS_FAVG; 313 #endif /* PPS_SYNC */ 314 } 315 time_status &= STA_RONLY; 316 time_status |= ntv->status & ~STA_RONLY; 317 } 318 if (modes & MOD_TIMECONST) { 319 if (ntv->constant < 0) 320 time_constant = 0; 321 else if (ntv->constant > MAXTC) 322 time_constant = MAXTC; 323 else 324 time_constant = ntv->constant; 325 } 326 if (modes & MOD_TAI) { 327 if (ntv->constant > 0) /* XXX zero & negative numbers ? */ 328 time_tai = ntv->constant; 329 } 330 #ifdef PPS_SYNC 331 if (modes & MOD_PPSMAX) { 332 if (ntv->shift < PPS_FAVG) 333 pps_shiftmax = PPS_FAVG; 334 else if (ntv->shift > PPS_FAVGMAX) 335 pps_shiftmax = PPS_FAVGMAX; 336 else 337 pps_shiftmax = ntv->shift; 338 } 339 #endif /* PPS_SYNC */ 340 if (modes & MOD_NANO) 341 time_status |= STA_NANO; 342 if (modes & MOD_MICRO) 343 time_status &= ~STA_NANO; 344 if (modes & MOD_CLKB) 345 time_status |= STA_CLK; 346 if (modes & MOD_CLKA) 347 time_status &= ~STA_CLK; 348 if (modes & MOD_FREQUENCY) { 349 freq = (ntv->freq * 1000LL) >> 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 hardupdate(ntv->offset * 1000); 370 } 371 372 /* 373 * Retrieve all clock variables. Note that the TAI offset is 374 * returned only by ntp_gettime(); 375 */ 376 if (time_status & STA_NANO) 377 ntv->offset = L_GINT(time_offset); 378 else 379 ntv->offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */ 380 ntv->freq = L_GINT((time_freq / 1000LL) << 16); 381 ntv->maxerror = time_maxerror; 382 ntv->esterror = time_esterror; 383 ntv->status = time_status; 384 ntv->constant = time_constant; 385 if (time_status & STA_NANO) 386 ntv->precision = time_precision; 387 else 388 ntv->precision = time_precision / 1000; 389 ntv->tolerance = MAXFREQ * SCALE_PPM; 390 #ifdef PPS_SYNC 391 ntv->shift = pps_shift; 392 ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16); 393 if (time_status & STA_NANO) 394 ntv->jitter = pps_jitter; 395 else 396 ntv->jitter = pps_jitter / 1000; 397 ntv->stabil = pps_stabil; 398 ntv->calcnt = pps_calcnt; 399 ntv->errcnt = pps_errcnt; 400 ntv->jitcnt = pps_jitcnt; 401 ntv->stbcnt = pps_stbcnt; 402 #endif /* PPS_SYNC */ 403 mutex_spin_exit(&timecounter_lock); 404 } 405 #endif /* NTP */ 406 407 /* 408 * second_overflow() - called after ntp_tick_adjust() 409 * 410 * This routine is ordinarily called immediately following the above 411 * routine ntp_tick_adjust(). While these two routines are normally 412 * combined, they are separated here only for the purposes of 413 * simulation. 414 */ 415 void 416 ntp_update_second(int64_t *adjustment, time_t *newsec) 417 { 418 int tickrate; 419 l_fp ftemp; /* 32/64-bit temporary */ 420 421 KASSERT(mutex_owned(&timecounter_lock)); 422 423 #ifdef NTP 424 425 /* 426 * On rollover of the second both the nanosecond and microsecond 427 * clocks are updated and the state machine cranked as 428 * necessary. The phase adjustment to be used for the next 429 * second is calculated and the maximum error is increased by 430 * the tolerance. 431 */ 432 time_maxerror += MAXFREQ / 1000; 433 434 /* 435 * Leap second processing. If in leap-insert state at 436 * the end of the day, the system clock is set back one 437 * second; if in leap-delete state, the system clock is 438 * set ahead one second. The nano_time() routine or 439 * external clock driver will insure that reported time 440 * is always monotonic. 441 */ 442 switch (time_state) { 443 444 /* 445 * No warning. 446 */ 447 case TIME_OK: 448 if (time_status & STA_INS) 449 time_state = TIME_INS; 450 else if (time_status & STA_DEL) 451 time_state = TIME_DEL; 452 break; 453 454 /* 455 * Insert second 23:59:60 following second 456 * 23:59:59. 457 */ 458 case TIME_INS: 459 if (!(time_status & STA_INS)) 460 time_state = TIME_OK; 461 else if ((*newsec) % 86400 == 0) { 462 (*newsec)--; 463 time_state = TIME_OOP; 464 time_tai++; 465 } 466 break; 467 468 /* 469 * Delete second 23:59:59. 470 */ 471 case TIME_DEL: 472 if (!(time_status & STA_DEL)) 473 time_state = TIME_OK; 474 else if (((*newsec) + 1) % 86400 == 0) { 475 (*newsec)++; 476 time_tai--; 477 time_state = TIME_WAIT; 478 } 479 break; 480 481 /* 482 * Insert second in progress. 483 */ 484 case TIME_OOP: 485 time_state = TIME_WAIT; 486 break; 487 488 /* 489 * Wait for status bits to clear. 490 */ 491 case TIME_WAIT: 492 if (!(time_status & (STA_INS | STA_DEL))) 493 time_state = TIME_OK; 494 } 495 496 /* 497 * Compute the total time adjustment for the next second 498 * in ns. The offset is reduced by a factor depending on 499 * whether the PPS signal is operating. Note that the 500 * value is in effect scaled by the clock frequency, 501 * since the adjustment is added at each tick interrupt. 502 */ 503 ftemp = time_offset; 504 #ifdef PPS_SYNC 505 /* XXX even if PPS signal dies we should finish adjustment ? */ 506 if (time_status & STA_PPSTIME && time_status & 507 STA_PPSSIGNAL) 508 L_RSHIFT(ftemp, pps_shift); 509 else 510 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 511 #else 512 L_RSHIFT(ftemp, SHIFT_PLL + time_constant); 513 #endif /* PPS_SYNC */ 514 time_adj = ftemp; 515 L_SUB(time_offset, ftemp); 516 L_ADD(time_adj, time_freq); 517 518 #ifdef PPS_SYNC 519 if (pps_valid > 0) 520 pps_valid--; 521 else 522 time_status &= ~STA_PPSSIGNAL; 523 #endif /* PPS_SYNC */ 524 #else /* !NTP */ 525 L_CLR(time_adj); 526 #endif /* !NTP */ 527 528 /* 529 * Apply any correction from adjtime(2). If more than one second 530 * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM) 531 * until the last second is slewed the final < 500 usecs. 532 */ 533 if (time_adjtime != 0) { 534 if (time_adjtime > 1000000) 535 tickrate = 5000; 536 else if (time_adjtime < -1000000) 537 tickrate = -5000; 538 else if (time_adjtime > 500) 539 tickrate = 500; 540 else if (time_adjtime < -500) 541 tickrate = -500; 542 else 543 tickrate = time_adjtime; 544 time_adjtime -= tickrate; 545 L_LINT(ftemp, tickrate * 1000); 546 L_ADD(time_adj, ftemp); 547 } 548 *adjustment = time_adj; 549 } 550 551 /* 552 * ntp_init() - initialize variables and structures 553 * 554 * This routine must be called after the kernel variables hz and tick 555 * are set or changed and before the next tick interrupt. In this 556 * particular implementation, these values are assumed set elsewhere in 557 * the kernel. The design allows the clock frequency and tick interval 558 * to be changed while the system is running. So, this routine should 559 * probably be integrated with the code that does that. 560 */ 561 void 562 ntp_init(void) 563 { 564 565 /* 566 * The following variables are initialized only at startup. Only 567 * those structures not cleared by the compiler need to be 568 * initialized, and these only in the simulator. In the actual 569 * kernel, any nonzero values here will quickly evaporate. 570 */ 571 L_CLR(time_adj); 572 #ifdef NTP 573 L_CLR(time_offset); 574 L_CLR(time_freq); 575 #ifdef PPS_SYNC 576 pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0; 577 pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0; 578 pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0; 579 pps_fcount = 0; 580 L_CLR(pps_freq); 581 #endif /* PPS_SYNC */ 582 #endif 583 } 584 585 #ifdef NTP 586 /* 587 * hardupdate() - local clock update 588 * 589 * This routine is called by ntp_adjtime() to update the local clock 590 * phase and frequency. The implementation is of an adaptive-parameter, 591 * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new 592 * time and frequency offset estimates for each call. If the kernel PPS 593 * discipline code is configured (PPS_SYNC), the PPS signal itself 594 * determines the new time offset, instead of the calling argument. 595 * Presumably, calls to ntp_adjtime() occur only when the caller 596 * believes the local clock is valid within some bound (+-128 ms with 597 * NTP). If the caller's time is far different than the PPS time, an 598 * argument will ensue, and it's not clear who will lose. 599 * 600 * For uncompensated quartz crystal oscillators and nominal update 601 * intervals less than 256 s, operation should be in phase-lock mode, 602 * where the loop is disciplined to phase. For update intervals greater 603 * than 1024 s, operation should be in frequency-lock mode, where the 604 * loop is disciplined to frequency. Between 256 s and 1024 s, the mode 605 * is selected by the STA_MODE status bit. 606 * 607 * Note: splclock() is in effect. 608 */ 609 void 610 hardupdate(long offset) 611 { 612 long mtemp; 613 l_fp ftemp; 614 615 KASSERT(mutex_owned(&timecounter_lock)); 616 617 /* 618 * Select how the phase is to be controlled and from which 619 * source. If the PPS signal is present and enabled to 620 * discipline the time, the PPS offset is used; otherwise, the 621 * argument offset is used. 622 */ 623 if (!(time_status & STA_PLL)) 624 return; 625 if (!(time_status & STA_PPSTIME && time_status & 626 STA_PPSSIGNAL)) { 627 if (offset > MAXPHASE) 628 time_monitor = MAXPHASE; 629 else if (offset < -MAXPHASE) 630 time_monitor = -MAXPHASE; 631 else 632 time_monitor = offset; 633 L_LINT(time_offset, time_monitor); 634 } 635 636 /* 637 * Select how the frequency is to be controlled and in which 638 * mode (PLL or FLL). If the PPS signal is present and enabled 639 * to discipline the frequency, the PPS frequency is used; 640 * otherwise, the argument offset is used to compute it. 641 */ 642 if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) { 643 time_reftime = time_second; 644 return; 645 } 646 if (time_status & STA_FREQHOLD || time_reftime == 0) 647 time_reftime = time_second; 648 mtemp = time_second - time_reftime; 649 L_LINT(ftemp, time_monitor); 650 L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1); 651 L_MPY(ftemp, mtemp); 652 L_ADD(time_freq, ftemp); 653 time_status &= ~STA_MODE; 654 if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > 655 MAXSEC)) { 656 L_LINT(ftemp, (time_monitor << 4) / mtemp); 657 L_RSHIFT(ftemp, SHIFT_FLL + 4); 658 L_ADD(time_freq, ftemp); 659 time_status |= STA_MODE; 660 } 661 time_reftime = time_second; 662 if (L_GINT(time_freq) > MAXFREQ) 663 L_LINT(time_freq, MAXFREQ); 664 else if (L_GINT(time_freq) < -MAXFREQ) 665 L_LINT(time_freq, -MAXFREQ); 666 } 667 668 #ifdef PPS_SYNC 669 /* 670 * hardpps() - discipline CPU clock oscillator to external PPS signal 671 * 672 * This routine is called at each PPS interrupt in order to discipline 673 * the CPU clock oscillator to the PPS signal. It measures the PPS phase 674 * and leaves it in a handy spot for the hardclock() routine. It 675 * integrates successive PPS phase differences and calculates the 676 * frequency offset. This is used in hardclock() to discipline the CPU 677 * clock oscillator so that intrinsic frequency error is cancelled out. 678 * The code requires the caller to capture the time and hardware counter 679 * value at the on-time PPS signal transition. 680 * 681 * Note that, on some Unix systems, this routine runs at an interrupt 682 * priority level higher than the timer interrupt routine hardclock(). 683 * Therefore, the variables used are distinct from the hardclock() 684 * variables, except for certain exceptions: The PPS frequency pps_freq 685 * and phase pps_offset variables are determined by this routine and 686 * updated atomically. The time_tolerance variable can be considered a 687 * constant, since it is infrequently changed, and then only when the 688 * PPS signal is disabled. The watchdog counter pps_valid is updated 689 * once per second by hardclock() and is atomically cleared in this 690 * routine. 691 */ 692 void 693 hardpps(struct timespec *tsp, /* time at PPS */ 694 long nsec /* hardware counter at PPS */) 695 { 696 long u_sec, u_nsec, v_nsec; /* temps */ 697 l_fp ftemp; 698 699 KASSERT(mutex_owned(&timecounter_lock)); 700 701 /* 702 * The signal is first processed by a range gate and frequency 703 * discriminator. The range gate rejects noise spikes outside 704 * the range +-500 us. The frequency discriminator rejects input 705 * signals with apparent frequency outside the range 1 +-500 706 * PPM. If two hits occur in the same second, we ignore the 707 * later hit; if not and a hit occurs outside the range gate, 708 * keep the later hit for later comparison, but do not process 709 * it. 710 */ 711 time_status |= STA_PPSSIGNAL | STA_PPSJITTER; 712 time_status &= ~(STA_PPSWANDER | STA_PPSERROR); 713 pps_valid = PPS_VALID; 714 u_sec = tsp->tv_sec; 715 u_nsec = tsp->tv_nsec; 716 if (u_nsec >= (NANOSECOND >> 1)) { 717 u_nsec -= NANOSECOND; 718 u_sec++; 719 } 720 v_nsec = u_nsec - pps_tf[0].tv_nsec; 721 if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - 722 MAXFREQ) 723 return; 724 pps_tf[2] = pps_tf[1]; 725 pps_tf[1] = pps_tf[0]; 726 pps_tf[0].tv_sec = u_sec; 727 pps_tf[0].tv_nsec = u_nsec; 728 729 /* 730 * Compute the difference between the current and previous 731 * counter values. If the difference exceeds 0.5 s, assume it 732 * has wrapped around, so correct 1.0 s. If the result exceeds 733 * the tick interval, the sample point has crossed a tick 734 * boundary during the last second, so correct the tick. Very 735 * intricate. 736 */ 737 u_nsec = nsec; 738 if (u_nsec > (NANOSECOND >> 1)) 739 u_nsec -= NANOSECOND; 740 else if (u_nsec < -(NANOSECOND >> 1)) 741 u_nsec += NANOSECOND; 742 pps_fcount += u_nsec; 743 if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ) 744 return; 745 time_status &= ~STA_PPSJITTER; 746 747 /* 748 * A three-stage median filter is used to help denoise the PPS 749 * time. The median sample becomes the time offset estimate; the 750 * difference between the other two samples becomes the time 751 * dispersion (jitter) estimate. 752 */ 753 if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) { 754 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) { 755 v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */ 756 u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec; 757 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) { 758 v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */ 759 u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec; 760 } else { 761 v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */ 762 u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec; 763 } 764 } else { 765 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) { 766 v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */ 767 u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec; 768 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) { 769 v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */ 770 u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec; 771 } else { 772 v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */ 773 u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec; 774 } 775 } 776 777 /* 778 * Nominal jitter is due to PPS signal noise and interrupt 779 * latency. If it exceeds the popcorn threshold, the sample is 780 * discarded. otherwise, if so enabled, the time offset is 781 * updated. We can tolerate a modest loss of data here without 782 * much degrading time accuracy. 783 */ 784 if (u_nsec > (pps_jitter << PPS_POPCORN)) { 785 time_status |= STA_PPSJITTER; 786 pps_jitcnt++; 787 } else if (time_status & STA_PPSTIME) { 788 time_monitor = -v_nsec; 789 L_LINT(time_offset, time_monitor); 790 } 791 pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG; 792 u_sec = pps_tf[0].tv_sec - pps_lastsec; 793 if (u_sec < (1 << pps_shift)) 794 return; 795 796 /* 797 * At the end of the calibration interval the difference between 798 * the first and last counter values becomes the scaled 799 * frequency. It will later be divided by the length of the 800 * interval to determine the frequency update. If the frequency 801 * exceeds a sanity threshold, or if the actual calibration 802 * interval is not equal to the expected length, the data are 803 * discarded. We can tolerate a modest loss of data here without 804 * much degrading frequency accuracy. 805 */ 806 pps_calcnt++; 807 v_nsec = -pps_fcount; 808 pps_lastsec = pps_tf[0].tv_sec; 809 pps_fcount = 0; 810 u_nsec = MAXFREQ << pps_shift; 811 if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << 812 pps_shift)) { 813 time_status |= STA_PPSERROR; 814 pps_errcnt++; 815 return; 816 } 817 818 /* 819 * Here the raw frequency offset and wander (stability) is 820 * calculated. If the wander is less than the wander threshold 821 * for four consecutive averaging intervals, the interval is 822 * doubled; if it is greater than the threshold for four 823 * consecutive intervals, the interval is halved. The scaled 824 * frequency offset is converted to frequency offset. The 825 * stability metric is calculated as the average of recent 826 * frequency changes, but is used only for performance 827 * monitoring. 828 */ 829 L_LINT(ftemp, v_nsec); 830 L_RSHIFT(ftemp, pps_shift); 831 L_SUB(ftemp, pps_freq); 832 u_nsec = L_GINT(ftemp); 833 if (u_nsec > PPS_MAXWANDER) { 834 L_LINT(ftemp, PPS_MAXWANDER); 835 pps_intcnt--; 836 time_status |= STA_PPSWANDER; 837 pps_stbcnt++; 838 } else if (u_nsec < -PPS_MAXWANDER) { 839 L_LINT(ftemp, -PPS_MAXWANDER); 840 pps_intcnt--; 841 time_status |= STA_PPSWANDER; 842 pps_stbcnt++; 843 } else { 844 pps_intcnt++; 845 } 846 if (pps_intcnt >= 4) { 847 pps_intcnt = 4; 848 if (pps_shift < pps_shiftmax) { 849 pps_shift++; 850 pps_intcnt = 0; 851 } 852 } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) { 853 pps_intcnt = -4; 854 if (pps_shift > PPS_FAVG) { 855 pps_shift--; 856 pps_intcnt = 0; 857 } 858 } 859 if (u_nsec < 0) 860 u_nsec = -u_nsec; 861 pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG; 862 863 /* 864 * The PPS frequency is recalculated and clamped to the maximum 865 * MAXFREQ. If enabled, the system clock frequency is updated as 866 * well. 867 */ 868 L_ADD(pps_freq, ftemp); 869 u_nsec = L_GINT(pps_freq); 870 if (u_nsec > MAXFREQ) 871 L_LINT(pps_freq, MAXFREQ); 872 else if (u_nsec < -MAXFREQ) 873 L_LINT(pps_freq, -MAXFREQ); 874 if (time_status & STA_PPSFREQ) 875 time_freq = pps_freq; 876 } 877 #endif /* PPS_SYNC */ 878 #endif /* NTP */ 879 880 #ifdef NTP 881 int 882 ntp_timestatus(void) 883 { 884 int rv; 885 886 /* 887 * Status word error decode. If any of these conditions 888 * occur, an error is returned, instead of the status 889 * word. Most applications will care only about the fact 890 * the system clock may not be trusted, not about the 891 * details. 892 * 893 * Hardware or software error 894 */ 895 mutex_spin_enter(&timecounter_lock); 896 if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) || 897 898 /* 899 * PPS signal lost when either time or frequency 900 * synchronization requested 901 */ 902 (time_status & (STA_PPSFREQ | STA_PPSTIME) && 903 !(time_status & STA_PPSSIGNAL)) || 904 905 /* 906 * PPS jitter exceeded when time synchronization 907 * requested 908 */ 909 (time_status & STA_PPSTIME && 910 time_status & STA_PPSJITTER) || 911 912 /* 913 * PPS wander exceeded or calibration error when 914 * frequency synchronization requested 915 */ 916 (time_status & STA_PPSFREQ && 917 time_status & (STA_PPSWANDER | STA_PPSERROR))) 918 rv = TIME_ERROR; 919 else 920 rv = time_state; 921 mutex_spin_exit(&timecounter_lock); 922 923 return rv; 924 } 925 926 /*ARGSUSED*/ 927 /* 928 * ntp_gettime() - NTP user application interface 929 */ 930 int 931 sys___ntp_gettime50(struct lwp *l, const struct sys___ntp_gettime50_args *uap, register_t *retval) 932 { 933 /* { 934 syscallarg(struct ntptimeval *) ntvp; 935 } */ 936 struct ntptimeval ntv; 937 int error = 0; 938 939 if (SCARG(uap, ntvp)) { 940 ntp_gettime(&ntv); 941 942 error = copyout((void *)&ntv, (void *)SCARG(uap, ntvp), 943 sizeof(ntv)); 944 } 945 if (!error) { 946 *retval = ntp_timestatus(); 947 } 948 return(error); 949 } 950 951 /* 952 * return information about kernel precision timekeeping 953 */ 954 static int 955 sysctl_kern_ntptime(SYSCTLFN_ARGS) 956 { 957 struct sysctlnode node; 958 struct ntptimeval ntv; 959 960 ntp_gettime(&ntv); 961 962 node = *rnode; 963 node.sysctl_data = &ntv; 964 node.sysctl_size = sizeof(ntv); 965 return (sysctl_lookup(SYSCTLFN_CALL(&node))); 966 } 967 968 SYSCTL_SETUP(sysctl_kern_ntptime_setup, "sysctl kern.ntptime node setup") 969 { 970 971 sysctl_createv(clog, 0, NULL, NULL, 972 CTLFLAG_PERMANENT, 973 CTLTYPE_NODE, "kern", NULL, 974 NULL, 0, NULL, 0, 975 CTL_KERN, CTL_EOL); 976 977 sysctl_createv(clog, 0, NULL, NULL, 978 CTLFLAG_PERMANENT, 979 CTLTYPE_STRUCT, "ntptime", 980 SYSCTL_DESCR("Kernel clock values for NTP"), 981 sysctl_kern_ntptime, 0, NULL, 982 sizeof(struct ntptimeval), 983 CTL_KERN, KERN_NTPTIME, CTL_EOL); 984 } 985 #endif /* !NTP */ 986