sys/kern/kern_ntptime.c

   1 /*-
   2  ***********************************************************************
   3  *                                                                     *
   4  * Copyright (c) David L. Mills 1993-2001                              *
   5  *                                                                     *
   6  * Permission to use, copy, modify, and distribute this software and   *
   7  * its documentation for any purpose and without fee is hereby         *
   8  * granted, provided that the above copyright notice appears in all    *
   9  * copies and that both the copyright notice and this permission       *
  10  * notice appear in supporting documentation, and that the name        *
  11  * University of Delaware not be used in advertising or publicity      *
  12  * pertaining to distribution of the software without specific,        *
  13  * written prior permission. The University of Delaware makes no       *
  14  * representations about the suitability this software for any         *
  15  * purpose. It is provided "as is" without express or implied          *
  16  * warranty.                                                           *
  17  *                                                                     *
  18  **********************************************************************/
  19
  20 /*
  21  * Adapted from the original sources for FreeBSD and timecounters by:
  22  * Poul-Henning Kamp <phk@FreeBSD.org>.
  23  *
  24  * The 32bit version of the "LP" macros seems a bit past its "sell by"
  25  * date so I have retained only the 64bit version and included it directly
  26  * in this file.
  27  *
  28  * Only minor changes done to interface with the timecounters over in
  29  * sys/kern/kern_clock.c.   Some of the comments below may be (even more)
  30  * confusing and/or plain wrong in that context.
  31  */
  32
  33 #include <sys/cdefs.h>
  34 __FBSDID("$FreeBSD$");
  35
  36 #include "opt_ntp.h"
  37
  38 #include <sys/param.h>
  39 #include <sys/systm.h>
  40 #include <sys/sysproto.h>
  41 #include <sys/eventhandler.h>
  42 #include <sys/kernel.h>
  43 #include <sys/priv.h>
  44 #include <sys/proc.h>
  45 #include <sys/lock.h>
  46 #include <sys/mutex.h>
  47 #include <sys/time.h>
  48 #include <sys/timex.h>
  49 #include <sys/timetc.h>
  50 #include <sys/timepps.h>
  51 #include <sys/syscallsubr.h>
  52 #include <sys/sysctl.h>
  53
  54 #ifdef PPS_SYNC
  55 FEATURE(pps_sync, "Support usage of external PPS signal by kernel PLL");
  56 #endif
  57
  58 /*
  59  * Single-precision macros for 64-bit machines
  60  */
  61 typedef int64_t l_fp;
  62 #define L_ADD(v, u)     ((v) += (u))
  63 #define L_SUB(v, u)     ((v) -= (u))
  64 #define L_ADDHI(v, a)   ((v) += (int64_t)(a) << 32)
  65 #define L_NEG(v)        ((v) = -(v))
  66 #define L_RSHIFT(v, n) \
  67         do { \
  68                 if ((v) < 0) \
  69                         (v) = -(-(v) >> (n)); \
  70                 else \
  71                         (v) = (v) >> (n); \
  72         } while (0)
  73 #define L_MPY(v, a)     ((v) *= (a))
  74 #define L_CLR(v)        ((v) = 0)
  75 #define L_ISNEG(v)      ((v) < 0)
  76 #define L_LINT(v, a)    ((v) = (int64_t)(a) << 32)
  77 #define L_GINT(v)       ((v) < 0 ? -(-(v) >> 32) : (v) >> 32)
  78
  79 /*
  80  * Generic NTP kernel interface
  81  *
  82  * These routines constitute the Network Time Protocol (NTP) interfaces
  83  * for user and daemon application programs. The ntp_gettime() routine
  84  * provides the time, maximum error (synch distance) and estimated error
  85  * (dispersion) to client user application programs. The ntp_adjtime()
  86  * routine is used by the NTP daemon to adjust the system clock to an
  87  * externally derived time. The time offset and related variables set by
  88  * this routine are used by other routines in this module to adjust the
  89  * phase and frequency of the clock discipline loop which controls the
  90  * system clock.
  91  *
  92  * When the kernel time is reckoned directly in nanoseconds (NTP_NANO
  93  * defined), the time at each tick interrupt is derived directly from
  94  * the kernel time variable. When the kernel time is reckoned in
  95  * microseconds, (NTP_NANO undefined), the time is derived from the
  96  * kernel time variable together with a variable representing the
  97  * leftover nanoseconds at the last tick interrupt. In either case, the
  98  * current nanosecond time is reckoned from these values plus an
  99  * interpolated value derived by the clock routines in another
 100  * architecture-specific module. The interpolation can use either a
 101  * dedicated counter or a processor cycle counter (PCC) implemented in
 102  * some architectures.
 103  *
 104  * Note that all routines must run at priority splclock or higher.
 105  */
 106 /*
 107  * Phase/frequency-lock loop (PLL/FLL) definitions
 108  *
 109  * The nanosecond clock discipline uses two variable types, time
 110  * variables and frequency variables. Both types are represented as 64-
 111  * bit fixed-point quantities with the decimal point between two 32-bit
 112  * halves. On a 32-bit machine, each half is represented as a single
 113  * word and mathematical operations are done using multiple-precision
 114  * arithmetic. On a 64-bit machine, ordinary computer arithmetic is
 115  * used.
 116  *
 117  * A time variable is a signed 64-bit fixed-point number in ns and
 118  * fraction. It represents the remaining time offset to be amortized
 119  * over succeeding tick interrupts. The maximum time offset is about
 120  * 0.5 s and the resolution is about 2.3e-10 ns.
 121  *
 122  *                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 123  *  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
 124  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 125  * |s s s|                       ns                                |
 126  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 127  * |                        fraction                               |
 128  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 129  *
 130  * A frequency variable is a signed 64-bit fixed-point number in ns/s
 131  * and fraction. It represents the ns and fraction to be added to the
 132  * kernel time variable at each second. The maximum frequency offset is
 133  * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s.
 134  *
 135  *                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
 136  *  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
 137  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 138  * |s s s s s s s s s s s s s|            ns/s                     |
 139  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 140  * |                        fraction                               |
 141  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 142  */
 143 /*
 144  * The following variables establish the state of the PLL/FLL and the
 145  * residual time and frequency offset of the local clock.
 146  */
 147 #define SHIFT_PLL       4               /* PLL loop gain (shift) */
 148 #define SHIFT_FLL       2               /* FLL loop gain (shift) */
 149
 150 static int time_state = TIME_OK;        /* clock state */
 151 int time_status = STA_UNSYNC;   /* clock status bits */
 152 static long time_tai;                   /* TAI offset (s) */
 153 static long time_monitor;               /* last time offset scaled (ns) */
 154 static long time_constant;              /* poll interval (shift) (s) */
 155 static long time_precision = 1;         /* clock precision (ns) */
 156 static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */
 157 long time_esterror = MAXPHASE / 1000; /* estimated error (us) */
 158 static long time_reftime;               /* uptime at last adjustment (s) */
 159 static l_fp time_offset;                /* time offset (ns) */
 160 static l_fp time_freq;                  /* frequency offset (ns/s) */
 161 static l_fp time_adj;                   /* tick adjust (ns/s) */
 162
 163 static int64_t time_adjtime;            /* correction from adjtime(2) (usec) */
 164
 165 #ifdef PPS_SYNC
 166 /*
 167  * The following variables are used when a pulse-per-second (PPS) signal
 168  * is available and connected via a modem control lead. They establish
 169  * the engineering parameters of the clock discipline loop when
 170  * controlled by the PPS signal.
 171  */
 172 #define PPS_FAVG        2               /* min freq avg interval (s) (shift) */
 173 #define PPS_FAVGDEF     8               /* default freq avg int (s) (shift) */
 174 #define PPS_FAVGMAX     15              /* max freq avg interval (s) (shift) */
 175 #define PPS_PAVG        4               /* phase avg interval (s) (shift) */
 176 #define PPS_VALID       120             /* PPS signal watchdog max (s) */
 177 #define PPS_MAXWANDER   100000          /* max PPS wander (ns/s) */
 178 #define PPS_POPCORN     2               /* popcorn spike threshold (shift) */
 179
 180 static struct timespec pps_tf[3];       /* phase median filter */
 181 static l_fp pps_freq;                   /* scaled frequency offset (ns/s) */
 182 static long pps_fcount;                 /* frequency accumulator */
 183 static long pps_jitter;                 /* nominal jitter (ns) */
 184 static long pps_stabil;                 /* nominal stability (scaled ns/s) */
 185 static long pps_lastsec;                /* time at last calibration (s) */
 186 static int pps_valid;                   /* signal watchdog counter */
 187 static int pps_shift = PPS_FAVG;        /* interval duration (s) (shift) */
 188 static int pps_shiftmax = PPS_FAVGDEF;  /* max interval duration (s) (shift) */
 189 static int pps_intcnt;                  /* wander counter */
 190
 191 /*
 192  * PPS signal quality monitors
 193  */
 194 static long pps_calcnt;                 /* calibration intervals */
 195 static long pps_jitcnt;                 /* jitter limit exceeded */
 196 static long pps_stbcnt;                 /* stability limit exceeded */
 197 static long pps_errcnt;                 /* calibration errors */
 198 #endif /* PPS_SYNC */
 199 /*
 200  * End of phase/frequency-lock loop (PLL/FLL) definitions
 201  */
 202
 203 static void ntp_init(void);
 204 static void hardupdate(long offset);
 205 static void ntp_gettime1(struct ntptimeval *ntvp);
 206 static int ntp_is_time_error(void);
 207
 208 static int
 209 ntp_is_time_error(void)
 210 {
 211         /*
 212          * Status word error decode. If any of these conditions occur,
 213          * an error is returned, instead of the status word. Most
 214          * applications will care only about the fact the system clock
 215          * may not be trusted, not about the details.
 216          *
 217          * Hardware or software error
 218          */
 219         if ((time_status & (STA_UNSYNC | STA_CLOCKERR)) ||
 220
 221         /*
 222          * PPS signal lost when either time or frequency synchronization
 223          * requested
 224          */
 225             (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
 226             !(time_status & STA_PPSSIGNAL)) ||
 227
 228         /*
 229          * PPS jitter exceeded when time synchronization requested
 230          */
 231             (time_status & STA_PPSTIME &&
 232             time_status & STA_PPSJITTER) ||
 233
 234         /*
 235          * PPS wander exceeded or calibration error when frequency
 236          * synchronization requested
 237          */
 238             (time_status & STA_PPSFREQ &&
 239             time_status & (STA_PPSWANDER | STA_PPSERROR)))
 240                 return (1);
 241
 242         return (0);
 243 }
 244
 245 static void
 246 ntp_gettime1(struct ntptimeval *ntvp)
 247 {
 248         struct timespec atv;    /* nanosecond time */
 249
 250         GIANT_REQUIRED;
 251
 252         nanotime(&atv);
 253         ntvp->time.tv_sec = atv.tv_sec;
 254         ntvp->time.tv_nsec = atv.tv_nsec;
 255         ntvp->maxerror = time_maxerror;
 256         ntvp->esterror = time_esterror;
 257         ntvp->tai = time_tai;
 258         ntvp->time_state = time_state;
 259
 260         if (ntp_is_time_error())
 261                 ntvp->time_state = TIME_ERROR;
 262 }
 263
 264 /*
 265  * ntp_gettime() - NTP user application interface
 266  *
 267  * See the timex.h header file for synopsis and API description.  Note that
 268  * the TAI offset is returned in the ntvtimeval.tai structure member.
 269  */
 270 #ifndef _SYS_SYSPROTO_H_
 271 struct ntp_gettime_args {
 272         struct ntptimeval *ntvp;
 273 };
 274 #endif
 275 /* ARGSUSED */
 276 int
 277 sys_ntp_gettime(struct thread *td, struct ntp_gettime_args *uap)
 278 {
 279         struct ntptimeval ntv;
 280
 281         mtx_lock(&Giant);
 282         ntp_gettime1(&ntv);
 283         mtx_unlock(&Giant);
 284
 285         td->td_retval[0] = ntv.time_state;
 286         return (copyout(&ntv, uap->ntvp, sizeof(ntv)));
 287 }
 288
 289 static int
 290 ntp_sysctl(SYSCTL_HANDLER_ARGS)
 291 {
 292         struct ntptimeval ntv;  /* temporary structure */
 293
 294         ntp_gettime1(&ntv);
 295
 296         return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req));
 297 }
 298
 299 SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW, 0, "");
 300 SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD,
 301         0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", "");
 302
 303 #ifdef PPS_SYNC
 304 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW,
 305     &pps_shiftmax, 0, "Max interval duration (sec) (shift)");
 306 SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW,
 307     &pps_shift, 0, "Interval duration (sec) (shift)");
 308 SYSCTL_LONG(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD,
 309     &time_monitor, 0, "Last time offset scaled (ns)");
 310
 311 SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD,
 312     &pps_freq, sizeof(pps_freq), "I", "Scaled frequency offset (ns/sec)");
 313 SYSCTL_OPAQUE(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD,
 314     &time_freq, sizeof(time_freq), "I", "Frequency offset (ns/sec)");
 315 #endif
 316
 317 /*
 318  * ntp_adjtime() - NTP daemon application interface
 319  *
 320  * See the timex.h header file for synopsis and API description.  Note that
 321  * the timex.constant structure member has a dual purpose to set the time
 322  * constant and to set the TAI offset.
 323  */
 324 #ifndef _SYS_SYSPROTO_H_
 325 struct ntp_adjtime_args {
 326         struct timex *tp;
 327 };
 328 #endif
 329
 330 int
 331 sys_ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap)
 332 {
 333         struct timex ntv;       /* temporary structure */
 334         long freq;              /* frequency ns/s) */
 335         int modes;              /* mode bits from structure */
 336         int s;                  /* caller priority */
 337         int error;
 338
 339         error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv));
 340         if (error)
 341                 return(error);
 342
 343         /*
 344          * Update selected clock variables - only the superuser can
 345          * change anything. Note that there is no error checking here on
 346          * the assumption the superuser should know what it is doing.
 347          * Note that either the time constant or TAI offset are loaded
 348          * from the ntv.constant member, depending on the mode bits. If
 349          * the STA_PLL bit in the status word is cleared, the state and
 350          * status words are reset to the initial values at boot.
 351          */
 352         mtx_lock(&Giant);
 353         modes = ntv.modes;
 354         if (modes)
 355                 error = priv_check(td, PRIV_NTP_ADJTIME);
 356         if (error)
 357                 goto done2;
 358         s = splclock();
 359         if (modes & MOD_MAXERROR)
 360                 time_maxerror = ntv.maxerror;
 361         if (modes & MOD_ESTERROR)
 362                 time_esterror = ntv.esterror;
 363         if (modes & MOD_STATUS) {
 364                 if (time_status & STA_PLL && !(ntv.status & STA_PLL)) {
 365                         time_state = TIME_OK;
 366                         time_status = STA_UNSYNC;
 367 #ifdef PPS_SYNC
 368                         pps_shift = PPS_FAVG;
 369 #endif /* PPS_SYNC */
 370                 }
 371                 time_status &= STA_RONLY;
 372                 time_status |= ntv.status & ~STA_RONLY;
 373         }
 374         if (modes & MOD_TIMECONST) {
 375                 if (ntv.constant < 0)
 376                         time_constant = 0;
 377                 else if (ntv.constant > MAXTC)
 378                         time_constant = MAXTC;
 379                 else
 380                         time_constant = ntv.constant;
 381         }
 382         if (modes & MOD_TAI) {
 383                 if (ntv.constant > 0) /* XXX zero & negative numbers ? */
 384                         time_tai = ntv.constant;
 385         }
 386 #ifdef PPS_SYNC
 387         if (modes & MOD_PPSMAX) {
 388                 if (ntv.shift < PPS_FAVG)
 389                         pps_shiftmax = PPS_FAVG;
 390                 else if (ntv.shift > PPS_FAVGMAX)
 391                         pps_shiftmax = PPS_FAVGMAX;
 392                 else
 393                         pps_shiftmax = ntv.shift;
 394         }
 395 #endif /* PPS_SYNC */
 396         if (modes & MOD_NANO)
 397                 time_status |= STA_NANO;
 398         if (modes & MOD_MICRO)
 399                 time_status &= ~STA_NANO;
 400         if (modes & MOD_CLKB)
 401                 time_status |= STA_CLK;
 402         if (modes & MOD_CLKA)
 403                 time_status &= ~STA_CLK;
 404         if (modes & MOD_FREQUENCY) {
 405                 freq = (ntv.freq * 1000LL) >> 16;
 406                 if (freq > MAXFREQ)
 407                         L_LINT(time_freq, MAXFREQ);
 408                 else if (freq < -MAXFREQ)
 409                         L_LINT(time_freq, -MAXFREQ);
 410                 else {
 411                         /*
 412                          * ntv.freq is [PPM * 2^16] = [us/s * 2^16]
 413                          * time_freq is [ns/s * 2^32]
 414                          */
 415                         time_freq = ntv.freq * 1000LL * 65536LL;
 416                 }
 417 #ifdef PPS_SYNC
 418                 pps_freq = time_freq;
 419 #endif /* PPS_SYNC */
 420         }
 421         if (modes & MOD_OFFSET) {
 422                 if (time_status & STA_NANO)
 423                         hardupdate(ntv.offset);
 424                 else
 425                         hardupdate(ntv.offset * 1000);
 426         }
 427
 428         /*
 429          * Retrieve all clock variables. Note that the TAI offset is
 430          * returned only by ntp_gettime();
 431          */
 432         if (time_status & STA_NANO)
 433                 ntv.offset = L_GINT(time_offset);
 434         else
 435                 ntv.offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */
 436         ntv.freq = L_GINT((time_freq / 1000LL) << 16);
 437         ntv.maxerror = time_maxerror;
 438         ntv.esterror = time_esterror;
 439         ntv.status = time_status;
 440         ntv.constant = time_constant;
 441         if (time_status & STA_NANO)
 442                 ntv.precision = time_precision;
 443         else
 444                 ntv.precision = time_precision / 1000;
 445         ntv.tolerance = MAXFREQ * SCALE_PPM;
 446 #ifdef PPS_SYNC
 447         ntv.shift = pps_shift;
 448         ntv.ppsfreq = L_GINT((pps_freq / 1000LL) << 16);
 449         if (time_status & STA_NANO)
 450                 ntv.jitter = pps_jitter;
 451         else
 452                 ntv.jitter = pps_jitter / 1000;
 453         ntv.stabil = pps_stabil;
 454         ntv.calcnt = pps_calcnt;
 455         ntv.errcnt = pps_errcnt;
 456         ntv.jitcnt = pps_jitcnt;
 457         ntv.stbcnt = pps_stbcnt;
 458 #endif /* PPS_SYNC */
 459         splx(s);
 460
 461         error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv));
 462         if (error)
 463                 goto done2;
 464
 465         if (ntp_is_time_error())
 466                 td->td_retval[0] = TIME_ERROR;
 467         else
 468                 td->td_retval[0] = time_state;
 469
 470 done2:
 471         mtx_unlock(&Giant);
 472         return (error);
 473 }
 474
 475 /*
 476  * second_overflow() - called after ntp_tick_adjust()
 477  *
 478  * This routine is ordinarily called immediately following the above
 479  * routine ntp_tick_adjust(). While these two routines are normally
 480  * combined, they are separated here only for the purposes of
 481  * simulation.
 482  */
 483 void
 484 ntp_update_second(int64_t *adjustment, time_t *newsec)
 485 {
 486         int tickrate;
 487         l_fp ftemp;             /* 32/64-bit temporary */
 488
 489         /*
 490          * On rollover of the second both the nanosecond and microsecond
 491          * clocks are updated and the state machine cranked as
 492          * necessary. The phase adjustment to be used for the next
 493          * second is calculated and the maximum error is increased by
 494          * the tolerance.
 495          */
 496         time_maxerror += MAXFREQ / 1000;
 497
 498         /*
 499          * Leap second processing. If in leap-insert state at
 500          * the end of the day, the system clock is set back one
 501          * second; if in leap-delete state, the system clock is
 502          * set ahead one second. The nano_time() routine or
 503          * external clock driver will insure that reported time
 504          * is always monotonic.
 505          */
 506         switch (time_state) {
 507
 508                 /*
 509                  * No warning.
 510                  */
 511                 case TIME_OK:
 512                 if (time_status & STA_INS)
 513                         time_state = TIME_INS;
 514                 else if (time_status & STA_DEL)
 515                         time_state = TIME_DEL;
 516                 break;
 517
 518                 /*
 519                  * Insert second 23:59:60 following second
 520                  * 23:59:59.
 521                  */
 522                 case TIME_INS:
 523                 if (!(time_status & STA_INS))
 524                         time_state = TIME_OK;
 525                 else if ((*newsec) % 86400 == 0) {
 526                         (*newsec)--;
 527                         time_state = TIME_OOP;
 528                         time_tai++;
 529                 }
 530                 break;
 531
 532                 /*
 533                  * Delete second 23:59:59.
 534                  */
 535                 case TIME_DEL:
 536                 if (!(time_status & STA_DEL))
 537                         time_state = TIME_OK;
 538                 else if (((*newsec) + 1) % 86400 == 0) {
 539                         (*newsec)++;
 540                         time_tai--;
 541                         time_state = TIME_WAIT;
 542                 }
 543                 break;
 544
 545                 /*
 546                  * Insert second in progress.
 547                  */
 548                 case TIME_OOP:
 549                         time_state = TIME_WAIT;
 550                 break;
 551
 552                 /*
 553                  * Wait for status bits to clear.
 554                  */
 555                 case TIME_WAIT:
 556                 if (!(time_status & (STA_INS | STA_DEL)))
 557                         time_state = TIME_OK;
 558         }
 559
 560         /*
 561          * Compute the total time adjustment for the next second
 562          * in ns. The offset is reduced by a factor depending on
 563          * whether the PPS signal is operating. Note that the
 564          * value is in effect scaled by the clock frequency,
 565          * since the adjustment is added at each tick interrupt.
 566          */
 567         ftemp = time_offset;
 568 #ifdef PPS_SYNC
 569         /* XXX even if PPS signal dies we should finish adjustment ? */
 570         if (time_status & STA_PPSTIME && time_status &
 571             STA_PPSSIGNAL)
 572                 L_RSHIFT(ftemp, pps_shift);
 573         else
 574                 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
 575 #else
 576                 L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
 577 #endif /* PPS_SYNC */
 578         time_adj = ftemp;
 579         L_SUB(time_offset, ftemp);
 580         L_ADD(time_adj, time_freq);
 581
 582         /*
 583          * Apply any correction from adjtime(2).  If more than one second
 584          * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500PPM)
 585          * until the last second is slewed the final < 500 usecs.
 586          */
 587         if (time_adjtime != 0) {
 588                 if (time_adjtime > 1000000)
 589                         tickrate = 5000;
 590                 else if (time_adjtime < -1000000)
 591                         tickrate = -5000;
 592                 else if (time_adjtime > 500)
 593                         tickrate = 500;
 594                 else if (time_adjtime < -500)
 595                         tickrate = -500;
 596                 else
 597                         tickrate = time_adjtime;
 598                 time_adjtime -= tickrate;
 599                 L_LINT(ftemp, tickrate * 1000);
 600                 L_ADD(time_adj, ftemp);
 601         }
 602         *adjustment = time_adj;
 603
 604 #ifdef PPS_SYNC
 605         if (pps_valid > 0)
 606                 pps_valid--;
 607         else
 608                 time_status &= ~STA_PPSSIGNAL;
 609 #endif /* PPS_SYNC */
 610 }
 611
 612 /*
 613  * ntp_init() - initialize variables and structures
 614  *
 615  * This routine must be called after the kernel variables hz and tick
 616  * are set or changed and before the next tick interrupt. In this
 617  * particular implementation, these values are assumed set elsewhere in
 618  * the kernel. The design allows the clock frequency and tick interval
 619  * to be changed while the system is running. So, this routine should
 620  * probably be integrated with the code that does that.
 621  */
 622 static void
 623 ntp_init()
 624 {
 625
 626         /*
 627          * The following variables are initialized only at startup. Only
 628          * those structures not cleared by the compiler need to be
 629          * initialized, and these only in the simulator. In the actual
 630          * kernel, any nonzero values here will quickly evaporate.
 631          */
 632         L_CLR(time_offset);
 633         L_CLR(time_freq);
 634 #ifdef PPS_SYNC
 635         pps_tf[0].tv_sec = pps_tf[0].tv_nsec = 0;
 636         pps_tf[1].tv_sec = pps_tf[1].tv_nsec = 0;
 637         pps_tf[2].tv_sec = pps_tf[2].tv_nsec = 0;
 638         pps_fcount = 0;
 639         L_CLR(pps_freq);
 640 #endif /* PPS_SYNC */
 641 }
 642
 643 SYSINIT(ntpclocks, SI_SUB_CLOCKS, SI_ORDER_MIDDLE, ntp_init, NULL);
 644
 645 /*
 646  * hardupdate() - local clock update
 647  *
 648  * This routine is called by ntp_adjtime() to update the local clock
 649  * phase and frequency. The implementation is of an adaptive-parameter,
 650  * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
 651  * time and frequency offset estimates for each call. If the kernel PPS
 652  * discipline code is configured (PPS_SYNC), the PPS signal itself
 653  * determines the new time offset, instead of the calling argument.
 654  * Presumably, calls to ntp_adjtime() occur only when the caller
 655  * believes the local clock is valid within some bound (+-128 ms with
 656  * NTP). If the caller's time is far different than the PPS time, an
 657  * argument will ensue, and it's not clear who will lose.
 658  *
 659  * For uncompensated quartz crystal oscillators and nominal update
 660  * intervals less than 256 s, operation should be in phase-lock mode,
 661  * where the loop is disciplined to phase. For update intervals greater
 662  * than 1024 s, operation should be in frequency-lock mode, where the
 663  * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
 664  * is selected by the STA_MODE status bit.
 665  */
 666 static void
 667 hardupdate(offset)
 668         long offset;            /* clock offset (ns) */
 669 {
 670         long mtemp;
 671         l_fp ftemp;
 672
 673         /*
 674          * Select how the phase is to be controlled and from which
 675          * source. If the PPS signal is present and enabled to
 676          * discipline the time, the PPS offset is used; otherwise, the
 677          * argument offset is used.
 678          */
 679         if (!(time_status & STA_PLL))
 680                 return;
 681         if (!(time_status & STA_PPSTIME && time_status &
 682             STA_PPSSIGNAL)) {
 683                 if (offset > MAXPHASE)
 684                         time_monitor = MAXPHASE;
 685                 else if (offset < -MAXPHASE)
 686                         time_monitor = -MAXPHASE;
 687                 else
 688                         time_monitor = offset;
 689                 L_LINT(time_offset, time_monitor);
 690         }
 691
 692         /*
 693          * Select how the frequency is to be controlled and in which
 694          * mode (PLL or FLL). If the PPS signal is present and enabled
 695          * to discipline the frequency, the PPS frequency is used;
 696          * otherwise, the argument offset is used to compute it.
 697          */
 698         if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {
 699                 time_reftime = time_uptime;
 700                 return;
 701         }
 702         if (time_status & STA_FREQHOLD || time_reftime == 0)
 703                 time_reftime = time_uptime;
 704         mtemp = time_uptime - time_reftime;
 705         L_LINT(ftemp, time_monitor);
 706         L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
 707         L_MPY(ftemp, mtemp);
 708         L_ADD(time_freq, ftemp);
 709         time_status &= ~STA_MODE;
 710         if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
 711             MAXSEC)) {
 712                 L_LINT(ftemp, (time_monitor << 4) / mtemp);
 713                 L_RSHIFT(ftemp, SHIFT_FLL + 4);
 714                 L_ADD(time_freq, ftemp);
 715                 time_status |= STA_MODE;
 716         }
 717         time_reftime = time_uptime;
 718         if (L_GINT(time_freq) > MAXFREQ)
 719                 L_LINT(time_freq, MAXFREQ);
 720         else if (L_GINT(time_freq) < -MAXFREQ)
 721                 L_LINT(time_freq, -MAXFREQ);
 722 }
 723
 724 #ifdef PPS_SYNC
 725 /*
 726  * hardpps() - discipline CPU clock oscillator to external PPS signal
 727  *
 728  * This routine is called at each PPS interrupt in order to discipline
 729  * the CPU clock oscillator to the PPS signal. There are two independent
 730  * first-order feedback loops, one for the phase, the other for the
 731  * frequency. The phase loop measures and grooms the PPS phase offset
 732  * and leaves it in a handy spot for the seconds overflow routine. The
 733  * frequency loop averages successive PPS phase differences and
 734  * calculates the PPS frequency offset, which is also processed by the
 735  * seconds overflow routine. The code requires the caller to capture the
 736  * time and architecture-dependent hardware counter values in
 737  * nanoseconds at the on-time PPS signal transition.
 738  *
 739  * Note that, on some Unix systems this routine runs at an interrupt
 740  * priority level higher than the timer interrupt routine hardclock().
 741  * Therefore, the variables used are distinct from the hardclock()
 742  * variables, except for the actual time and frequency variables, which
 743  * are determined by this routine and updated atomically.
 744  */
 745 void
 746 hardpps(tsp, nsec)
 747         struct timespec *tsp;   /* time at PPS */
 748         long nsec;              /* hardware counter at PPS */
 749 {
 750         long u_sec, u_nsec, v_nsec; /* temps */
 751         l_fp ftemp;
 752
 753         /*
 754          * The signal is first processed by a range gate and frequency
 755          * discriminator. The range gate rejects noise spikes outside
 756          * the range +-500 us. The frequency discriminator rejects input
 757          * signals with apparent frequency outside the range 1 +-500
 758          * PPM. If two hits occur in the same second, we ignore the
 759          * later hit; if not and a hit occurs outside the range gate,
 760          * keep the later hit for later comparison, but do not process
 761          * it.
 762          */
 763         time_status |= STA_PPSSIGNAL | STA_PPSJITTER;
 764         time_status &= ~(STA_PPSWANDER | STA_PPSERROR);
 765         pps_valid = PPS_VALID;
 766         u_sec = tsp->tv_sec;
 767         u_nsec = tsp->tv_nsec;
 768         if (u_nsec >= (NANOSECOND >> 1)) {
 769                 u_nsec -= NANOSECOND;
 770                 u_sec++;
 771         }
 772         v_nsec = u_nsec - pps_tf[0].tv_nsec;
 773         if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND -
 774             MAXFREQ)
 775                 return;
 776         pps_tf[2] = pps_tf[1];
 777         pps_tf[1] = pps_tf[0];
 778         pps_tf[0].tv_sec = u_sec;
 779         pps_tf[0].tv_nsec = u_nsec;
 780
 781         /*
 782          * Compute the difference between the current and previous
 783          * counter values. If the difference exceeds 0.5 s, assume it
 784          * has wrapped around, so correct 1.0 s. If the result exceeds
 785          * the tick interval, the sample point has crossed a tick
 786          * boundary during the last second, so correct the tick. Very
 787          * intricate.
 788          */
 789         u_nsec = nsec;
 790         if (u_nsec > (NANOSECOND >> 1))
 791                 u_nsec -= NANOSECOND;
 792         else if (u_nsec < -(NANOSECOND >> 1))
 793                 u_nsec += NANOSECOND;
 794         pps_fcount += u_nsec;
 795         if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
 796                 return;
 797         time_status &= ~STA_PPSJITTER;
 798
 799         /*
 800          * A three-stage median filter is used to help denoise the PPS
 801          * time. The median sample becomes the time offset estimate; the
 802          * difference between the other two samples becomes the time
 803          * dispersion (jitter) estimate.
 804          */
 805         if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {
 806                 if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {
 807                         v_nsec = pps_tf[1].tv_nsec;     /* 0 1 2 */
 808                         u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;
 809                 } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {
 810                         v_nsec = pps_tf[0].tv_nsec;     /* 2 0 1 */
 811                         u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;
 812                 } else {
 813                         v_nsec = pps_tf[2].tv_nsec;     /* 0 2 1 */
 814                         u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;
 815                 }
 816         } else {
 817                 if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {
 818                         v_nsec = pps_tf[1].tv_nsec;     /* 2 1 0 */
 819                         u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;
 820                 } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {
 821                         v_nsec = pps_tf[0].tv_nsec;     /* 1 0 2 */
 822                         u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;
 823                 } else {
 824                         v_nsec = pps_tf[2].tv_nsec;     /* 1 2 0 */
 825                         u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;
 826                 }
 827         }
 828
 829         /*
 830          * Nominal jitter is due to PPS signal noise and interrupt
 831          * latency. If it exceeds the popcorn threshold, the sample is
 832          * discarded. otherwise, if so enabled, the time offset is
 833          * updated. We can tolerate a modest loss of data here without
 834          * much degrading time accuracy.
 835          *
 836          * The measurements being checked here were made with the system
 837          * timecounter, so the popcorn threshold is not allowed to fall below
 838          * the number of nanoseconds in two ticks of the timecounter.  For a
 839          * timecounter running faster than 1 GHz the lower bound is 2ns, just
 840          * to avoid a nonsensical threshold of zero.
 841         */
 842         if (u_nsec > lmax(pps_jitter << PPS_POPCORN,
 843             2 * (NANOSECOND / (long)qmin(NANOSECOND, tc_getfrequency())))) {
 844                 time_status |= STA_PPSJITTER;
 845                 pps_jitcnt++;
 846         } else if (time_status & STA_PPSTIME) {
 847                 time_monitor = -v_nsec;
 848                 L_LINT(time_offset, time_monitor);
 849         }
 850         pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;
 851         u_sec = pps_tf[0].tv_sec - pps_lastsec;
 852         if (u_sec < (1 << pps_shift))
 853                 return;
 854
 855         /*
 856          * At the end of the calibration interval the difference between
 857          * the first and last counter values becomes the scaled
 858          * frequency. It will later be divided by the length of the
 859          * interval to determine the frequency update. If the frequency
 860          * exceeds a sanity threshold, or if the actual calibration
 861          * interval is not equal to the expected length, the data are
 862          * discarded. We can tolerate a modest loss of data here without
 863          * much degrading frequency accuracy.
 864          */
 865         pps_calcnt++;
 866         v_nsec = -pps_fcount;
 867         pps_lastsec = pps_tf[0].tv_sec;
 868         pps_fcount = 0;
 869         u_nsec = MAXFREQ << pps_shift;
 870         if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 <<
 871             pps_shift)) {
 872                 time_status |= STA_PPSERROR;
 873                 pps_errcnt++;
 874                 return;
 875         }
 876
 877         /*
 878          * Here the raw frequency offset and wander (stability) is
 879          * calculated. If the wander is less than the wander threshold
 880          * for four consecutive averaging intervals, the interval is
 881          * doubled; if it is greater than the threshold for four
 882          * consecutive intervals, the interval is halved. The scaled
 883          * frequency offset is converted to frequency offset. The
 884          * stability metric is calculated as the average of recent
 885          * frequency changes, but is used only for performance
 886          * monitoring.
 887          */
 888         L_LINT(ftemp, v_nsec);
 889         L_RSHIFT(ftemp, pps_shift);
 890         L_SUB(ftemp, pps_freq);
 891         u_nsec = L_GINT(ftemp);
 892         if (u_nsec > PPS_MAXWANDER) {
 893                 L_LINT(ftemp, PPS_MAXWANDER);
 894                 pps_intcnt--;
 895                 time_status |= STA_PPSWANDER;
 896                 pps_stbcnt++;
 897         } else if (u_nsec < -PPS_MAXWANDER) {
 898                 L_LINT(ftemp, -PPS_MAXWANDER);
 899                 pps_intcnt--;
 900                 time_status |= STA_PPSWANDER;
 901                 pps_stbcnt++;
 902         } else {
 903                 pps_intcnt++;
 904         }
 905         if (pps_intcnt >= 4) {
 906                 pps_intcnt = 4;
 907                 if (pps_shift < pps_shiftmax) {
 908                         pps_shift++;
 909                         pps_intcnt = 0;
 910                 }
 911         } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {
 912                 pps_intcnt = -4;
 913                 if (pps_shift > PPS_FAVG) {
 914                         pps_shift--;
 915                         pps_intcnt = 0;
 916                 }
 917         }
 918         if (u_nsec < 0)
 919                 u_nsec = -u_nsec;
 920         pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;
 921
 922         /*
 923          * The PPS frequency is recalculated and clamped to the maximum
 924          * MAXFREQ. If enabled, the system clock frequency is updated as
 925          * well.
 926          */
 927         L_ADD(pps_freq, ftemp);
 928         u_nsec = L_GINT(pps_freq);
 929         if (u_nsec > MAXFREQ)
 930                 L_LINT(pps_freq, MAXFREQ);
 931         else if (u_nsec < -MAXFREQ)
 932                 L_LINT(pps_freq, -MAXFREQ);
 933         if (time_status & STA_PPSFREQ)
 934                 time_freq = pps_freq;
 935 }
 936 #endif /* PPS_SYNC */
 937
 938 #ifndef _SYS_SYSPROTO_H_
 939 struct adjtime_args {
 940         struct timeval *delta;
 941         struct timeval *olddelta;
 942 };
 943 #endif
 944 /* ARGSUSED */
 945 int
 946 sys_adjtime(struct thread *td, struct adjtime_args *uap)
 947 {
 948         struct timeval delta, olddelta, *deltap;
 949         int error;
 950
 951         if (uap->delta) {
 952                 error = copyin(uap->delta, &delta, sizeof(delta));
 953                 if (error)
 954                         return (error);
 955                 deltap = &delta;
 956         } else
 957                 deltap = NULL;
 958         error = kern_adjtime(td, deltap, &olddelta);
 959         if (uap->olddelta && error == 0)
 960                 error = copyout(&olddelta, uap->olddelta, sizeof(olddelta));
 961         return (error);
 962 }
 963
 964 int
 965 kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta)
 966 {
 967         struct timeval atv;
 968         int error;
 969
 970         mtx_lock(&Giant);
 971         if (olddelta) {
 972                 atv.tv_sec = time_adjtime / 1000000;
 973                 atv.tv_usec = time_adjtime % 1000000;
 974                 if (atv.tv_usec < 0) {
 975                         atv.tv_usec += 1000000;
 976                         atv.tv_sec--;
 977                 }
 978                 *olddelta = atv;
 979         }
 980         if (delta) {
 981                 if ((error = priv_check(td, PRIV_ADJTIME))) {
 982                         mtx_unlock(&Giant);
 983                         return (error);
 984                 }
 985                 time_adjtime = (int64_t)delta->tv_sec * 1000000 +
 986                     delta->tv_usec;
 987         }
 988         mtx_unlock(&Giant);
 989         return (0);
 990 }
 991
 992 static struct callout resettodr_callout;
 993 static int resettodr_period = 1800;
 994
 995 static void
 996 periodic_resettodr(void *arg __unused)
 997 {
 998
 999         if (!ntp_is_time_error()) {
1000                 mtx_lock(&Giant);
1001                 resettodr();
1002                 mtx_unlock(&Giant);
1003         }
1004         if (resettodr_period > 0)
1005                 callout_schedule(&resettodr_callout, resettodr_period * hz);
1006 }
1007
1008 static void
1009 shutdown_resettodr(void *arg __unused, int howto __unused)
1010 {
1011
1012         callout_drain(&resettodr_callout);
1013         if (resettodr_period > 0 && !ntp_is_time_error()) {
1014                 mtx_lock(&Giant);
1015                 resettodr();
1016                 mtx_unlock(&Giant);
1017         }
1018 }
1019
1020 static int
1021 sysctl_resettodr_period(SYSCTL_HANDLER_ARGS)
1022 {
1023         int error;
1024
1025         error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
1026         if (error || !req->newptr)
1027                 return (error);
1028         if (cold)
1029                 goto done;
1030         if (resettodr_period == 0)
1031                 callout_stop(&resettodr_callout);
1032         else
1033                 callout_reset(&resettodr_callout, resettodr_period * hz,
1034                     periodic_resettodr, NULL);
1035 done:
1036         return (0);
1037 }
1038
1039 SYSCTL_PROC(_machdep, OID_AUTO, rtc_save_period, CTLTYPE_INT|CTLFLAG_RWTUN,
1040         &resettodr_period, 1800, sysctl_resettodr_period, "I",
1041         "Save system time to RTC with this period (in seconds)");
1042
1043 static void
1044 start_periodic_resettodr(void *arg __unused)
1045 {
1046
1047         EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_resettodr, NULL,
1048             SHUTDOWN_PRI_FIRST);
1049         callout_init(&resettodr_callout, 1);
1050         if (resettodr_period == 0)
1051                 return;
1052         callout_reset(&resettodr_callout, resettodr_period * hz,
1053             periodic_resettodr, NULL);
1054 }
1055
1056 SYSINIT(periodic_resettodr, SI_SUB_LAST, SI_ORDER_MIDDLE,
1057         start_periodic_resettodr, NULL);