sys/kern/kern_ntptime.c

   1 /*      $NetBSD: kern_ntptime.c,v 1.51 2009/01/11 02:45:52 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 1.51 2009/01/11 02:45:52 christos Exp $");
  64
  65 #include "opt_ntp.h"
  66
  67 #include <sys/param.h>
  68 #include <sys/resourcevar.h>
  69 #include <sys/systm.h>
  70 #include <sys/kernel.h>
  71 #include <sys/proc.h>
  72 #include <sys/sysctl.h>
  73 #include <sys/timex.h>
  74 #include <sys/vnode.h>
  75 #include <sys/kauth.h>
  76 #include <sys/mount.h>
  77 #include <sys/syscallargs.h>
  78 #include <sys/cpu.h>
  79
  80 #include <compat/sys/timex.h>
  81
  82 /*
  83  * Single-precision macros for 64-bit machines
  84  */
  85 typedef int64_t l_fp;
  86 #define L_ADD(v, u)     ((v) += (u))
  87 #define L_SUB(v, u)     ((v) -= (u))
  88 #define L_ADDHI(v, a)   ((v) += (int64_t)(a) << 32)
  89 #define L_NEG(v)        ((v) = -(v))
  90 #define L_RSHIFT(v, n) \
  91         do { \
  92                 if ((v) < 0) \
  93                         (v) = -(-(v) >> (n)); \
  94                 else \
  95                         (v) = (v) >> (n); \
  96         } while (0)
  97 #define L_MPY(v, a)     ((v) *= (a))
  98 #define L_CLR(v)        ((v) = 0)
  99 #define L_ISNEG(v)      ((v) < 0)
 100 #define L_LINT(v, a)    ((v) = (int64_t)(a) << 32)
 101 #define L_GINT(v)       ((v) < 0 ? -(-(v) >> 32) : (v) >> 32)
 102
 103 #ifdef NTP
 104 /*
 105  * Generic NTP kernel interface
 106  *
 107  * These routines constitute the Network Time Protocol (NTP) interfaces
 108  * for user and daemon application programs. The ntp_gettime() routine
 109  * provides the time, maximum error (synch distance) and estimated error
 110  * (dispersion) to client user application programs. The ntp_adjtime()
 111  * routine is used by the NTP daemon to adjust the system clock to an
 112  * externally derived time. The time offset and related variables set by
 113  * this routine are used by other routines in this module to adjust the
 114  * phase and frequency of the clock discipline loop which controls the
 115  * system clock.
 116  *
 117  * When the kernel time is reckoned directly in nanoseconds (NTP_NANO
 118  * defined), the time at each tick interrupt is derived directly from
 119  * the kernel time variable. When the kernel time is reckoned in
 120  * microseconds, (NTP_NANO undefined), the time is derived from the
 121  * kernel time variable together with a variable representing the
 122  * leftover nanoseconds at the last tick interrupt. In either case, the
 123  * current nanosecond time is reckoned from these values plus an
 124  * interpolated value derived by the clock routines in another
 125  * architecture-specific module. The interpolation can use either a
 126  * dedicated counter or a processor cycle counter (PCC) implemented in
 127  * some architectures.
 128  *
 129  * Note that all routines must run at priority splclock or higher.
 130  */
 131 /*
 132  * Phase/frequency-lock loop (PLL/FLL) definitions
 133  *
 134  * The nanosecond clock discipline uses two variable types, time
 135  * variables and frequency variables. Both types are represented as 64-
 136  * bit fixed-point quantities with the decimal point between two 32-bit
 137  * halves. On a 32-bit machine, each half is represented as a single
 138  * word and mathematical operations are done using multiple-precision
 139  * arithmetic. On a 64-bit machine, ordinary computer arithmetic is
 140  * used.
 141  *
 142  * A time variable is a signed 64-bit fixed-point number in ns and
 143  * fraction. It represents the remaining time offset to be amortized
 144  * over succeeding tick interrupts. The maximum time offset is about
 145  * 0.5 s and the resolution is about 2.3e-10 ns.
 146  *
 147  *                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 148  *  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
 149  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 150  * |s s s|                       ns                                |
 151  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 152  * |                        fraction                               |
 153  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 154  *
 155  * A frequency variable is a signed 64-bit fixed-point number in ns/s
 156  * and fraction. It represents the ns and fraction to be added to the
 157  * kernel time variable at each second. The maximum frequency offset is
 158  * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s.
 159  *
 160  *                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 161  *  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
 162  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 163  * |s s s s s s s s s s s s s|            ns/s                     |
 164  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 165  * |                        fraction                               |
 166  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 167  */
 168 /*
 169  * The following variables establish the state of the PLL/FLL and the
 170  * residual time and frequency offset of the local clock.
 171  */
 172 #define SHIFT_PLL       4               /* PLL loop gain (shift) */
 173 #define SHIFT_FLL       2               /* FLL loop gain (shift) */
 174
 175 static int time_state = TIME_OK;        /* clock state */
 176 static int time_status = STA_UNSYNC;    /* clock status bits */
 177 static long time_tai;                   /* TAI offset (s) */
 178 static long time_monitor;               /* last time offset scaled (ns) */
 179 static long time_constant;              /* poll interval (shift) (s) */
 180 static long time_precision = 1;         /* clock precision (ns) */
 181 static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */
 182 static long time_esterror = MAXPHASE / 1000; /* estimated error (us) */
 183 static long time_reftime;               /* time at last adjustment (s) */
 184 static l_fp time_offset;                /* time offset (ns) */
 185 static l_fp time_freq;                  /* frequency offset (ns/s) */
 186 #endif /* NTP */
 187
 188 static l_fp time_adj;                   /* tick adjust (ns/s) */
 189 int64_t time_adjtime;           /* correction from adjtime(2) (usec) */
 190
 191 extern int time_adjusted;       /* ntp might have changed the system time */
 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
 241         mutex_spin_enter(&timecounter_lock);
 242         nanotime(&ntv->time);
 243         ntv->maxerror = time_maxerror;
 244         ntv->esterror = time_esterror;
 245         ntv->tai = time_tai;
 246         ntv->time_state = time_state;
 247         mutex_spin_exit(&timecounter_lock);
 248 }
 249
 250 /* ARGSUSED */
 251 /*
 252  * ntp_adjtime() - NTP daemon application interface
 253  */
 254 int
 255 sys_ntp_adjtime(struct lwp *l, const struct sys_ntp_adjtime_args *uap, register_t *retval)
 256 {
 257         /* {
 258                 syscallarg(struct timex *) tp;
 259         } */
 260         struct timex ntv;
 261         int error = 0;
 262
 263         error = copyin((void *)SCARG(uap, tp), (void *)&ntv, sizeof(ntv));
 264         if (error != 0)
 265                 return (error);
 266
 267         if (ntv.modes != 0 && (error = kauth_authorize_system(l->l_cred,
 268             KAUTH_SYSTEM_TIME, KAUTH_REQ_SYSTEM_TIME_NTPADJTIME, NULL,
 269             NULL, NULL)) != 0)
 270                 return (error);
 271
 272         ntp_adjtime1(&ntv);
 273
 274         error = copyout((void *)&ntv, (void *)SCARG(uap, tp), sizeof(ntv));
 275         if (!error)
 276                 *retval = ntp_timestatus();
 277
 278         return error;
 279 }
 280
 281 void
 282 ntp_adjtime1(struct timex *ntv)
 283 {
 284         long freq;
 285         int modes;
 286
 287         /*
 288          * Update selected clock variables - only the superuser can
 289          * change anything. Note that there is no error checking here on
 290          * the assumption the superuser should know what it is doing.
 291          * Note that either the time constant or TAI offset are loaded
 292          * from the ntv.constant member, depending on the mode bits. If
 293          * the STA_PLL bit in the status word is cleared, the state and
 294          * status words are reset to the initial values at boot.
 295          */
 296         mutex_spin_enter(&timecounter_lock);
 297         modes = ntv->modes;
 298         if (modes != 0)
 299                 /* We need to save the system time during shutdown */
 300                 time_adjusted |= 2;
 301         if (modes & MOD_MAXERROR)
 302                 time_maxerror = ntv->maxerror;
 303         if (modes & MOD_ESTERROR)
 304                 time_esterror = ntv->esterror;
 305         if (modes & MOD_STATUS) {
 306                 if (time_status & STA_PLL && !(ntv->status & STA_PLL)) {
 307                         time_state = TIME_OK;
 308                         time_status = STA_UNSYNC;
 309 #ifdef PPS_SYNC
 310                         pps_shift = PPS_FAVG;
 311 #endif /* PPS_SYNC */
 312                 }
 313                 time_status &= STA_RONLY;
 314                 time_status |= ntv->status & ~STA_RONLY;
 315         }
 316         if (modes & MOD_TIMECONST) {
 317                 if (ntv->constant < 0)
 318                         time_constant = 0;
 319                 else if (ntv->constant > MAXTC)
 320                         time_constant = MAXTC;
 321                 else
 322                         time_constant = ntv->constant;
 323         }
 324         if (modes & MOD_TAI) {
 325                 if (ntv->constant > 0)  /* XXX zero & negative numbers ? */
 326                         time_tai = ntv->constant;
 327         }
 328 #ifdef PPS_SYNC
 329         if (modes & MOD_PPSMAX) {
 330                 if (ntv->shift < PPS_FAVG)
 331                         pps_shiftmax = PPS_FAVG;
 332                 else if (ntv->shift > PPS_FAVGMAX)
 333                         pps_shiftmax = PPS_FAVGMAX;
 334                 else
 335                         pps_shiftmax = ntv->shift;
 336         }
 337 #endif /* PPS_SYNC */
 338         if (modes & MOD_NANO)
 339                 time_status |= STA_NANO;
 340         if (modes & MOD_MICRO)
 341                 time_status &= ~STA_NANO;
 342         if (modes & MOD_CLKB)
 343                 time_status |= STA_CLK;
 344         if (modes & MOD_CLKA)
 345                 time_status &= ~STA_CLK;
 346         if (modes & MOD_FREQUENCY) {
 347                 freq = (ntv->freq * 1000LL) >> 16;
 348                 if (freq > MAXFREQ)
 349                         L_LINT(time_freq, MAXFREQ);
 350                 else if (freq < -MAXFREQ)
 351                         L_LINT(time_freq, -MAXFREQ);
 352                 else {
 353                         /*
 354                          * ntv.freq is [PPM * 2^16] = [us/s * 2^16]
 355                          * time_freq is [ns/s * 2^32]
 356                          */
 357                         time_freq = ntv->freq * 1000LL * 65536LL;
 358                 }
 359 #ifdef PPS_SYNC
 360                 pps_freq = time_freq;
 361 #endif /* PPS_SYNC */
 362         }
 363         if (modes & MOD_OFFSET) {
 364                 if (time_status & STA_NANO)
 365                         hardupdate(ntv->offset);
 366                 else
 367                         hardupdate(ntv->offset * 1000);
 368         }
 369
 370         /*
 371          * Retrieve all clock variables. Note that the TAI offset is
 372          * returned only by ntp_gettime();
 373          */
 374         if (time_status & STA_NANO)
 375                 ntv->offset = L_GINT(time_offset);
 376         else
 377                 ntv->offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */
 378         ntv->freq = L_GINT((time_freq / 1000LL) << 16);
 379         ntv->maxerror = time_maxerror;
 380         ntv->esterror = time_esterror;
 381         ntv->status = time_status;
 382         ntv->constant = time_constant;
 383         if (time_status & STA_NANO)
 384                 ntv->precision = time_precision;
 385         else
 386                 ntv->precision = time_precision / 1000;
 387         ntv->tolerance = MAXFREQ * SCALE_PPM;
 388 #ifdef PPS_SYNC
 389         ntv->shift = pps_shift;
 390         ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16);
 391         if (time_status & STA_NANO)
 392                 ntv->jitter = pps_jitter;
 393         else
 394                 ntv->jitter = pps_jitter / 1000;
 395         ntv->stabil = pps_stabil;
 396         ntv->calcnt = pps_calcnt;
 397         ntv->errcnt = pps_errcnt;
 398         ntv->jitcnt = pps_jitcnt;
 399         ntv->stbcnt = pps_stbcnt;
 400 #endif /* PPS_SYNC */
 401         mutex_spin_exit(&timecounter_lock);
 402 }
 403 #endif /* NTP */
 404
 405 /*
 406  * second_overflow() - called after ntp_tick_adjust()
 407  *
 408  * This routine is ordinarily called immediately following the above
 409  * routine ntp_tick_adjust(). While these two routines are normally
 410  * combined, they are separated here only for the purposes of
 411  * simulation.
 412  */
 413 void
 414 ntp_update_second(int64_t *adjustment, time_t *newsec)
 415 {
 416         int tickrate;
 417         l_fp ftemp;             /* 32/64-bit temporary */
 418
 419         KASSERT(mutex_owned(&timecounter_lock));
 420
 421 #ifdef NTP
 422
 423         /*
 424          * On rollover of the second both the nanosecond and microsecond
 425          * clocks are updated and the state machine cranked as
 426          * necessary. The phase adjustment to be used for the next
 427          * second is calculated and the maximum error is increased by
 428          * the tolerance.
 429          */
 430         time_maxerror += MAXFREQ / 1000;
 431
 432         /*
 433          * Leap second processing. If in leap-insert state at
 434          * the end of the day, the system clock is set back one
 435          * second; if in leap-delete state, the system clock is
 436          * set ahead one second. The nano_time() routine or
 437          * external clock driver will insure that reported time
 438          * is always monotonic.
 439          */
 440         switch (time_state) {
 441
 442                 /*
 443                  * No warning.
 444                  */
 445                 case TIME_OK:
 446                 if (time_status & STA_INS)
 447                         time_state = TIME_INS;
 448                 else if (time_status & STA_DEL)
 449                         time_state = TIME_DEL;
 450                 break;
 451
 452                 /*
 453                  * Insert second 23:59:60 following second
 454                  * 23:59:59.
 455                  */
 456                 case TIME_INS:
 457                 if (!(time_status & STA_INS))
 458                         time_state = TIME_OK;
 459                 else if ((*newsec) % 86400 == 0) {
 460                         (*newsec)--;
 461                         time_state = TIME_OOP;
 462                         time_tai++;
 463                 }
 464                 break;
 465
 466                 /*
 467                  * Delete second 23:59:59.
 468                  */
 469                 case TIME_DEL:
 470                 if (!(time_status & STA_DEL))
 471                         time_state = TIME_OK;
 472                 else if (((*newsec) + 1) % 86400 == 0) {
 473                         (*newsec)++;
 474                         time_tai--;
 475                         time_state = TIME_WAIT;
 476                 }
 477                 break;
 478
 479                 /*
 480                  * Insert second in progress.
 481                  */
 482                 case TIME_OOP:
 483                         time_state = TIME_WAIT;
 484                 break;
 485
 486                 /*
 487                  * Wait for status bits to clear.
 488                  */
 489                 case TIME_WAIT:
 490                 if (!(time_status & (STA_INS | STA_DEL)))
 491                         time_state = TIME_OK;
 492         }
 493
 494         /*
 495          * Compute the total time adjustment for the next second
 496          * in ns. The offset is reduced by a factor depending on
 497          * whether the PPS signal is operating. Note that the
 498          * value is in effect scaled by the clock frequency,
 499          * since the adjustment is added at each tick interrupt.
 500          */
 501         ftemp = time_offset;
 502 #ifdef PPS_SYNC
 503         /* XXX even if PPS signal dies we should finish adjustment ? */
 504         if (time_status & STA_PPSTIME && time_status &
 505             STA_PPSSIGNAL)
 506                 L_RSHIFT(ftemp, pps_shift);
 507         else
 508                 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
 509 #else
 510                 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
 511 #endif /* PPS_SYNC */
 512         time_adj = ftemp;
 513         L_SUB(time_offset, ftemp);
 514         L_ADD(time_adj, time_freq);
 515
 516 #ifdef PPS_SYNC
 517         if (pps_valid > 0)
 518                 pps_valid--;
 519         else
 520                 time_status &= ~STA_PPSSIGNAL;
 521 #endif /* PPS_SYNC */
 522 #else  /* !NTP */
 523         L_CLR(time_adj);
 524 #endif /* !NTP */
 525
 526         /*
 527          * Apply any correction from adjtime(2).  If more than one second
 528          * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM)
 529          * until the last second is slewed the final < 500 usecs.
 530          */
 531         if (time_adjtime != 0) {
 532                 if (time_adjtime > 1000000)
 533                         tickrate = 5000;
 534                 else if (time_adjtime < -1000000)
 535                         tickrate = -5000;
 536                 else if (time_adjtime > 500)
 537                         tickrate = 500;
 538                 else if (time_adjtime < -500)
 539                         tickrate = -500;
 540                 else
 541                         tickrate = time_adjtime;
 542                 time_adjtime -= tickrate;
 543                 L_LINT(ftemp, tickrate * 1000);
 544                 L_ADD(time_adj, ftemp);
 545         }
 546         *adjustment = time_adj;
 547 }
 548
 549 /*
 550  * ntp_init() - initialize variables and structures
 551  *
 552  * This routine must be called after the kernel variables hz and tick
 553  * are set or changed and before the next tick interrupt. In this
 554  * particular implementation, these values are assumed set elsewhere in
 555  * the kernel. The design allows the clock frequency and tick interval
 556  * to be changed while the system is running. So, this routine should
 557  * probably be integrated with the code that does that.
 558  */
 559 void
 560 ntp_init(void)
 561 {
 562
 563         /*
 564          * The following variables are initialized only at startup. Only
 565          * those structures not cleared by the compiler need to be
 566          * initialized, and these only in the simulator. In the actual
 567          * kernel, any nonzero values here will quickly evaporate.
 568          */
 569         L_CLR(time_adj);
 570 #ifdef NTP
 571         L_CLR(time_offset);
 572         L_CLR(time_freq);
 573 #ifdef PPS_SYNC
 574         pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;
 575         pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;
 576         pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;
 577         pps_fcount = 0;
 578         L_CLR(pps_freq);
 579 #endif /* PPS_SYNC */
 580 #endif
 581 }
 582
 583 #ifdef NTP
 584 /*
 585  * hardupdate() - local clock update
 586  *
 587  * This routine is called by ntp_adjtime() to update the local clock
 588  * phase and frequency. The implementation is of an adaptive-parameter,
 589  * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
 590  * time and frequency offset estimates for each call. If the kernel PPS
 591  * discipline code is configured (PPS_SYNC), the PPS signal itself
 592  * determines the new time offset, instead of the calling argument.
 593  * Presumably, calls to ntp_adjtime() occur only when the caller
 594  * believes the local clock is valid within some bound (+-128 ms with
 595  * NTP). If the caller's time is far different than the PPS time, an
 596  * argument will ensue, and it's not clear who will lose.
 597  *
 598  * For uncompensated quartz crystal oscillators and nominal update
 599  * intervals less than 256 s, operation should be in phase-lock mode,
 600  * where the loop is disciplined to phase. For update intervals greater
 601  * than 1024 s, operation should be in frequency-lock mode, where the
 602  * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
 603  * is selected by the STA_MODE status bit.
 604  *
 605  * Note: splclock() is in effect.
 606  */
 607 void
 608 hardupdate(long offset)
 609 {
 610         long mtemp;
 611         l_fp ftemp;
 612
 613         KASSERT(mutex_owned(&timecounter_lock));
 614
 615         /*
 616          * Select how the phase is to be controlled and from which
 617          * source. If the PPS signal is present and enabled to
 618          * discipline the time, the PPS offset is used; otherwise, the
 619          * argument offset is used.
 620          */
 621         if (!(time_status & STA_PLL))
 622                 return;
 623         if (!(time_status & STA_PPSTIME && time_status &
 624             STA_PPSSIGNAL)) {
 625                 if (offset > MAXPHASE)
 626                         time_monitor = MAXPHASE;
 627                 else if (offset < -MAXPHASE)
 628                         time_monitor = -MAXPHASE;
 629                 else
 630                         time_monitor = offset;
 631                 L_LINT(time_offset, time_monitor);
 632         }
 633
 634         /*
 635          * Select how the frequency is to be controlled and in which
 636          * mode (PLL or FLL). If the PPS signal is present and enabled
 637          * to discipline the frequency, the PPS frequency is used;
 638          * otherwise, the argument offset is used to compute it.
 639          */
 640         if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {
 641                 time_reftime = time_second;
 642                 return;
 643         }
 644         if (time_status & STA_FREQHOLD || time_reftime == 0)
 645                 time_reftime = time_second;
 646         mtemp = time_second - time_reftime;
 647         L_LINT(ftemp, time_monitor);
 648         L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
 649         L_MPY(ftemp, mtemp);
 650         L_ADD(time_freq, ftemp);
 651         time_status &= ~STA_MODE;
 652         if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
 653             MAXSEC)) {
 654                 L_LINT(ftemp, (time_monitor << 4) / mtemp);
 655                 L_RSHIFT(ftemp, SHIFT_FLL + 4);
 656                 L_ADD(time_freq, ftemp);
 657                 time_status |= STA_MODE;
 658         }
 659         time_reftime = time_second;
 660         if (L_GINT(time_freq) > MAXFREQ)
 661                 L_LINT(time_freq, MAXFREQ);
 662         else if (L_GINT(time_freq) < -MAXFREQ)
 663                 L_LINT(time_freq, -MAXFREQ);
 664 }
 665
 666 #ifdef PPS_SYNC
 667 /*
 668  * hardpps() - discipline CPU clock oscillator to external PPS signal
 669  *
 670  * This routine is called at each PPS interrupt in order to discipline
 671  * the CPU clock oscillator to the PPS signal. It measures the PPS phase
 672  * and leaves it in a handy spot for the hardclock() routine. It
 673  * integrates successive PPS phase differences and calculates the
 674  * frequency offset. This is used in hardclock() to discipline the CPU
 675  * clock oscillator so that intrinsic frequency error is cancelled out.
 676  * The code requires the caller to capture the time and hardware counter
 677  * value at the on-time PPS signal transition.
 678  *
 679  * Note that, on some Unix systems, this routine runs at an interrupt
 680  * priority level higher than the timer interrupt routine hardclock().
 681  * Therefore, the variables used are distinct from the hardclock()
 682  * variables, except for certain exceptions: The PPS frequency pps_freq
 683  * and phase pps_offset variables are determined by this routine and
 684  * updated atomically. The time_tolerance variable can be considered a
 685  * constant, since it is infrequently changed, and then only when the
 686  * PPS signal is disabled. The watchdog counter pps_valid is updated
 687  * once per second by hardclock() and is atomically cleared in this
 688  * routine.
 689  */
 690 void
 691 hardpps(struct timespec *tsp,           /* time at PPS */
 692         long nsec                       /* hardware counter at PPS */)
 693 {
 694         long u_sec, u_nsec, v_nsec; /* temps */
 695         l_fp ftemp;
 696
 697         KASSERT(mutex_owned(&timecounter_lock));
 698
 699         /*
 700          * The signal is first processed by a range gate and frequency
 701          * discriminator. The range gate rejects noise spikes outside
 702          * the range +-500 us. The frequency discriminator rejects input
 703          * signals with apparent frequency outside the range 1 +-500
 704          * PPM. If two hits occur in the same second, we ignore the
 705          * later hit; if not and a hit occurs outside the range gate,
 706          * keep the later hit for later comparison, but do not process
 707          * it.
 708          */
 709         time_status |= STA_PPSSIGNAL | STA_PPSJITTER;
 710         time_status &= ~(STA_PPSWANDER | STA_PPSERROR);
 711         pps_valid = PPS_VALID;
 712         u_sec = tsp->tv_sec;
 713         u_nsec = tsp->tv_nsec;
 714         if (u_nsec >= (NANOSECOND >> 1)) {
 715                 u_nsec -= NANOSECOND;
 716                 u_sec++;
 717         }
 718         v_nsec = u_nsec - pps_tf[0].tv_nsec;
 719         if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND -
 720             MAXFREQ)
 721                 return;
 722         pps_tf[2] = pps_tf[1];
 723         pps_tf[1] = pps_tf[0];
 724         pps_tf[0].tv_sec = u_sec;
 725         pps_tf[0].tv_nsec = u_nsec;
 726
 727         /*
 728          * Compute the difference between the current and previous
 729          * counter values. If the difference exceeds 0.5 s, assume it
 730          * has wrapped around, so correct 1.0 s. If the result exceeds
 731          * the tick interval, the sample point has crossed a tick
 732          * boundary during the last second, so correct the tick. Very
 733          * intricate.
 734          */
 735         u_nsec = nsec;
 736         if (u_nsec > (NANOSECOND >> 1))
 737                 u_nsec -= NANOSECOND;
 738         else if (u_nsec < -(NANOSECOND >> 1))
 739                 u_nsec += NANOSECOND;
 740         pps_fcount += u_nsec;
 741         if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
 742                 return;
 743         time_status &= ~STA_PPSJITTER;
 744
 745         /*
 746          * A three-stage median filter is used to help denoise the PPS
 747          * time. The median sample becomes the time offset estimate; the
 748          * difference between the other two samples becomes the time
 749          * dispersion (jitter) estimate.
 750          */
 751         if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {
 752                 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {
 753                         v_nsec = pps_tf[1].tv_nsec;     /* 0 1 2 */
 754                         u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;
 755                 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {
 756                         v_nsec = pps_tf[0].tv_nsec;     /* 2 0 1 */
 757                         u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;
 758                 } else {
 759                         v_nsec = pps_tf[2].tv_nsec;     /* 0 2 1 */
 760                         u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;
 761                 }
 762         } else {
 763                 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {
 764                         v_nsec = pps_tf[1].tv_nsec;     /* 2 1 0 */
 765                         u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;
 766                 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {
 767                         v_nsec = pps_tf[0].tv_nsec;     /* 1 0 2 */
 768                         u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;
 769                 } else {
 770                         v_nsec = pps_tf[2].tv_nsec;     /* 1 2 0 */
 771                         u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;
 772                 }
 773         }
 774
 775         /*
 776          * Nominal jitter is due to PPS signal noise and interrupt
 777          * latency. If it exceeds the popcorn threshold, the sample is
 778          * discarded. otherwise, if so enabled, the time offset is
 779          * updated. We can tolerate a modest loss of data here without
 780          * much degrading time accuracy.
 781          */
 782         if (u_nsec > (pps_jitter << PPS_POPCORN)) {
 783                 time_status |= STA_PPSJITTER;
 784                 pps_jitcnt++;
 785         } else if (time_status & STA_PPSTIME) {
 786                 time_monitor = -v_nsec;
 787                 L_LINT(time_offset, time_monitor);
 788         }
 789         pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;
 790         u_sec = pps_tf[0].tv_sec - pps_lastsec;
 791         if (u_sec < (1 << pps_shift))
 792                 return;
 793
 794         /*
 795          * At the end of the calibration interval the difference between
 796          * the first and last counter values becomes the scaled
 797          * frequency. It will later be divided by the length of the
 798          * interval to determine the frequency update. If the frequency
 799          * exceeds a sanity threshold, or if the actual calibration
 800          * interval is not equal to the expected length, the data are
 801          * discarded. We can tolerate a modest loss of data here without
 802          * much degrading frequency accuracy.
 803          */
 804         pps_calcnt++;
 805         v_nsec = -pps_fcount;
 806         pps_lastsec = pps_tf[0].tv_sec;
 807         pps_fcount = 0;
 808         u_nsec = MAXFREQ << pps_shift;
 809         if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 <<
 810             pps_shift)) {
 811                 time_status |= STA_PPSERROR;
 812                 pps_errcnt++;
 813                 return;
 814         }
 815
 816         /*
 817          * Here the raw frequency offset and wander (stability) is
 818          * calculated. If the wander is less than the wander threshold
 819          * for four consecutive averaging intervals, the interval is
 820          * doubled; if it is greater than the threshold for four
 821          * consecutive intervals, the interval is halved. The scaled
 822          * frequency offset is converted to frequency offset. The
 823          * stability metric is calculated as the average of recent
 824          * frequency changes, but is used only for performance
 825          * monitoring.
 826          */
 827         L_LINT(ftemp, v_nsec);
 828         L_RSHIFT(ftemp, pps_shift);
 829         L_SUB(ftemp, pps_freq);
 830         u_nsec = L_GINT(ftemp);
 831         if (u_nsec > PPS_MAXWANDER) {
 832                 L_LINT(ftemp, PPS_MAXWANDER);
 833                 pps_intcnt--;
 834                 time_status |= STA_PPSWANDER;
 835                 pps_stbcnt++;
 836         } else if (u_nsec < -PPS_MAXWANDER) {
 837                 L_LINT(ftemp, -PPS_MAXWANDER);
 838                 pps_intcnt--;
 839                 time_status |= STA_PPSWANDER;
 840                 pps_stbcnt++;
 841         } else {
 842                 pps_intcnt++;
 843         }
 844         if (pps_intcnt >= 4) {
 845                 pps_intcnt = 4;
 846                 if (pps_shift < pps_shiftmax) {
 847                         pps_shift++;
 848                         pps_intcnt = 0;
 849                 }
 850         } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {
 851                 pps_intcnt = -4;
 852                 if (pps_shift > PPS_FAVG) {
 853                         pps_shift--;
 854                         pps_intcnt = 0;
 855                 }
 856         }
 857         if (u_nsec < 0)
 858                 u_nsec = -u_nsec;
 859         pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;
 860
 861         /*
 862          * The PPS frequency is recalculated and clamped to the maximum
 863          * MAXFREQ. If enabled, the system clock frequency is updated as
 864          * well.
 865          */
 866         L_ADD(pps_freq, ftemp);
 867         u_nsec = L_GINT(pps_freq);
 868         if (u_nsec > MAXFREQ)
 869                 L_LINT(pps_freq, MAXFREQ);
 870         else if (u_nsec < -MAXFREQ)
 871                 L_LINT(pps_freq, -MAXFREQ);
 872         if (time_status & STA_PPSFREQ)
 873                 time_freq = pps_freq;
 874 }
 875 #endif /* PPS_SYNC */
 876 #endif /* NTP */
 877
 878 #ifdef NTP
 879 int
 880 ntp_timestatus(void)
 881 {
 882         int rv;
 883
 884         /*
 885          * Status word error decode. If any of these conditions
 886          * occur, an error is returned, instead of the status
 887          * word. Most applications will care only about the fact
 888          * the system clock may not be trusted, not about the
 889          * details.
 890          *
 891          * Hardware or software error
 892          */
 893         mutex_spin_enter(&timecounter_lock);
 894         if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||
 895
 896         /*
 897          * PPS signal lost when either time or frequency
 898          * synchronization requested
 899          */
 900             (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
 901              !(time_status & STA_PPSSIGNAL)) ||
 902
 903         /*
 904          * PPS jitter exceeded when time synchronization
 905          * requested
 906          */
 907             (time_status & STA_PPSTIME &&
 908              time_status & STA_PPSJITTER) ||
 909
 910         /*
 911          * PPS wander exceeded or calibration error when
 912          * frequency synchronization requested
 913          */
 914             (time_status & STA_PPSFREQ &&
 915              time_status & (STA_PPSWANDER | STA_PPSERROR)))
 916                 rv = TIME_ERROR;
 917         else
 918                 rv = time_state;
 919         mutex_spin_exit(&timecounter_lock);
 920
 921         return rv;
 922 }
 923
 924 /*ARGSUSED*/
 925 /*
 926  * ntp_gettime() - NTP user application interface
 927  */
 928 int
 929 sys___ntp_gettime50(struct lwp *l, const struct sys___ntp_gettime50_args *uap, register_t *retval)
 930 {
 931         /* {
 932                 syscallarg(struct ntptimeval *) ntvp;
 933         } */
 934         struct ntptimeval ntv;
 935         int error = 0;
 936
 937         if (SCARG(uap, ntvp)) {
 938                 ntp_gettime(&ntv);
 939
 940                 error = copyout((void *)&ntv, (void *)SCARG(uap, ntvp),
 941                                 sizeof(ntv));
 942         }
 943         if (!error) {
 944                 *retval = ntp_timestatus();
 945         }
 946         return(error);
 947 }
 948
 949 /*
 950  * return information about kernel precision timekeeping
 951  */
 952 static int
 953 sysctl_kern_ntptime(SYSCTLFN_ARGS)
 954 {
 955         struct sysctlnode node;
 956         struct ntptimeval ntv;
 957
 958         ntp_gettime(&ntv);
 959
 960         node = *rnode;
 961         node.sysctl_data = &ntv;
 962         node.sysctl_size = sizeof(ntv);
 963         return (sysctl_lookup(SYSCTLFN_CALL(&node)));
 964 }
 965
 966 SYSCTL_SETUP(sysctl_kern_ntptime_setup, "sysctl kern.ntptime node setup")
 967 {
 968
 969         sysctl_createv(clog, 0, NULL, NULL,
 970                        CTLFLAG_PERMANENT,
 971                        CTLTYPE_NODE, "kern", NULL,
 972                        NULL, 0, NULL, 0,
 973                        CTL_KERN, CTL_EOL);
 974
 975         sysctl_createv(clog, 0, NULL, NULL,
 976                        CTLFLAG_PERMANENT,
 977                        CTLTYPE_STRUCT, "ntptime",
 978                        SYSCTL_DESCR("Kernel clock values for NTP"),
 979                        sysctl_kern_ntptime, 0, NULL,
 980                        sizeof(struct ntptimeval),
 981                        CTL_KERN, KERN_NTPTIME, CTL_EOL);
 982 }
 983 #endif /* !NTP */