/****************************************************************************** * * * Copyright (c) David L. Mills 1993, 1994 * * * * Permission to use, copy, modify, and distribute this software and its * * documentation for any purpose and without fee is hereby granted, provided * * that the above copyright notice appears in all copies and that both the * * copyright notice and this permission notice appear in supporting * * documentation, and that the name University of Delaware not be used in * * advertising or publicity pertaining to distribution of the software * * without specific, written prior permission. The University of Delaware * * makes no representations about the suitability this software for any * * purpose. It is provided "as is" without express or implied warranty. * * * ******************************************************************************/ /* * Modification history kern_ntptime.c * * 24 Sep 94 David L. Mills * Tightened code at exits. * * 24 Mar 94 David L. Mills * Revised syscall interface to include new variables for PPS * time discipline. * * 14 Feb 94 David L. Mills * Added code for external clock * * 28 Nov 93 David L. Mills * Revised frequency scaling to conform with adjusted parameters * * 17 Sep 93 David L. Mills * Created file */ /* * ntp_gettime(), ntp_adjtime() - precision time interface for SunOS * V4.1.1 and V4.1.3 * * These routines consitute the Network Time Protocol (NTP) interfaces * for user and daemon application programs. The ntp_gettime() routine * provides the time, maximum error (synch distance) and estimated error * (dispersion) to client user application programs. The ntp_adjtime() * routine is used by the NTP daemon to adjust the system clock to an * externally derived time. The time offset and related variables set by * this routine are used by hardclock() to adjust the phase and * frequency of the phase-lock loop which controls the system clock. */ #include "opt_ntp.h" #include #include #include #include #include #include #include #include /* * Phase/frequency-lock loop (PLL/FLL) definitions * * The following variables are read and set by the ntp_adjtime() system * call. * * time_state shows the state of the system clock, with values defined * in the timex.h header file. * * time_status shows the status of the system clock, with bits defined * in the timex.h header file. * * time_offset is used by the PLL/FLL to adjust the system time in small * increments. * * time_constant determines the bandwidth or "stiffness" of the PLL. * * time_tolerance determines maximum frequency error or tolerance of the * CPU clock oscillator and is a property of the architecture; however, * in principle it could change as result of the presence of external * discipline signals, for instance. * * time_precision is usually equal to the kernel tick variable; however, * in cases where a precision clock counter or external clock is * available, the resolution can be much less than this and depend on * whether the external clock is working or not. * * time_maxerror is initialized by a ntp_adjtime() call and increased by * the kernel once each second to reflect the maximum error * bound growth. * * time_esterror is set and read by the ntp_adjtime() call, but * otherwise not used by the kernel. */ static int time_status = STA_UNSYNC; /* clock status bits */ static int time_state = TIME_OK; /* clock state */ static long time_offset = 0; /* time offset (us) */ static long time_constant = 0; /* pll time constant */ static long time_tolerance = MAXFREQ; /* frequency tolerance (scaled ppm) */ static long time_precision = 1; /* clock precision (us) */ static long time_maxerror = MAXPHASE; /* maximum error (us) */ static long time_esterror = MAXPHASE; /* estimated error (us) */ static int time_daemon = 0; /* No timedaemon active */ /* * The following variables establish the state of the PLL/FLL and the * residual time and frequency offset of the local clock. The scale * factors are defined in the timex.h header file. * * time_phase and time_freq are the phase increment and the frequency * increment, respectively, of the kernel time variable at each tick of * the clock. * * time_freq is set via ntp_adjtime() from a value stored in a file when * the synchronization daemon is first started. Its value is retrieved * via ntp_adjtime() and written to the file about once per hour by the * daemon. * * time_adj is the adjustment added to the value of tick at each timer * interrupt and is recomputed from time_phase and time_freq at each * seconds rollover. * * time_reftime is the second's portion of the system time on the last * call to ntp_adjtime(). It is used to adjust the time_freq variable * and to increase the time_maxerror as the time since last update * increases. */ long time_phase = 0; /* phase offset (scaled us) */ static long time_freq = 0; /* frequency offset (scaled ppm) */ long time_adj = 0; /* tick adjust (scaled 1 / hz) */ static long time_reftime = 0; /* time at last adjustment (s) */ #ifdef PPS_SYNC /* * The following variables are used only if the kernel PPS discipline * code is configured (PPS_SYNC). The scale factors are defined in the * timex.h header file. * * pps_time contains the time at each calibration interval, as read by * microtime(). pps_count counts the seconds of the calibration * interval, the duration of which is nominally pps_shift in powers of * two. * * pps_offset is the time offset produced by the time median filter * pps_tf[], while pps_jitter is the dispersion (jitter) measured by * this filter. * * pps_freq is the frequency offset produced by the frequency median * filter pps_ff[], while pps_stabil is the dispersion (wander) measured * by this filter. * * pps_usec is latched from a high resolution counter or external clock * at pps_time. Here we want the hardware counter contents only, not the * contents plus the time_tv.usec as usual. * * pps_valid counts the number of seconds since the last PPS update. It * is used as a watchdog timer to disable the PPS discipline should the * PPS signal be lost. * * pps_glitch counts the number of seconds since the beginning of an * offset burst more than tick/2 from current nominal offset. It is used * mainly to suppress error bursts due to priority conflicts between the * PPS interrupt and timer interrupt. * * pps_intcnt counts the calibration intervals for use in the interval- * adaptation algorithm. It's just too complicated for words. */ static struct timeval pps_time; /* kernel time at last interval */ static long pps_offset = 0; /* pps time offset (us) */ static long pps_jitter = MAXTIME; /* pps time dispersion (jitter) (us) */ static long pps_tf[] = {0, 0, 0}; /* pps time offset median filter (us) */ static long pps_freq = 0; /* frequency offset (scaled ppm) */ static long pps_stabil = MAXFREQ; /* frequency dispersion (scaled ppm) */ static long pps_ff[] = {0, 0, 0}; /* frequency offset median filter */ static long pps_usec = 0; /* microsec counter at last interval */ static long pps_valid = PPS_VALID; /* pps signal watchdog counter */ static int pps_glitch = 0; /* pps signal glitch counter */ static int pps_count = 0; /* calibration interval counter (s) */ static int pps_shift = PPS_SHIFT; /* interval duration (s) (shift) */ static int pps_intcnt = 0; /* intervals at current duration */ /* * PPS signal quality monitors * * pps_jitcnt counts the seconds that have been discarded because the * jitter measured by the time median filter exceeds the limit MAXTIME * (100 us). * * pps_calcnt counts the frequency calibration intervals, which are * variable from 4 s to 256 s. * * pps_errcnt counts the calibration intervals which have been discarded * because the wander exceeds the limit MAXFREQ (100 ppm) or where the * calibration interval jitter exceeds two ticks. * * pps_stbcnt counts the calibration intervals that have been discarded * because the frequency wander exceeds the limit MAXFREQ / 4 (25 us). */ static long pps_jitcnt = 0; /* jitter limit exceeded */ static long pps_calcnt = 0; /* calibration intervals */ static long pps_errcnt = 0; /* calibration errors */ static long pps_stbcnt = 0; /* stability limit exceeded */ #endif /* PPS_SYNC */ static void hardupdate __P((int64_t offset, int prescaled)); /* * hardupdate() - local clock update * * This routine is called by ntp_adjtime() to update the local clock * phase and frequency. The implementation is of an adaptive-parameter, * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new * time and frequency offset estimates for each call. If the kernel PPS * discipline code is configured (PPS_SYNC), the PPS signal itself * determines the new time offset, instead of the calling argument. * Presumably, calls to ntp_adjtime() occur only when the caller * believes the local clock is valid within some bound (+-128 ms with * NTP). If the caller's time is far different than the PPS time, an * argument will ensue, and it's not clear who will lose. * * For uncompensated quartz crystal oscillatores and nominal update * intervals less than 1024 s, operation should be in phase-lock mode * (STA_FLL = 0), where the loop is disciplined to phase. For update * intervals greater than thiss, operation should be in frequency-lock * mode (STA_FLL = 1), where the loop is disciplined to frequency. * * Note: splclock() is in effect. */ static void hardupdate(offset, prescaled) int64_t offset; int prescaled; { long mtemp; int64_t ltemp; if (!(time_status & STA_PLL) && !(time_status & STA_PPSTIME)) return; if (prescaled) ltemp = offset; else ltemp = offset << SHIFT_UPDATE; #ifdef PPS_SYNC if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL) ltemp = pps_offset << SHIFT_UPDATE; #endif /* PPS_SYNC */ /* * Scale the phase adjustment and clamp to the operating range. */ if (ltemp > (MAXPHASE << SHIFT_UPDATE)) time_offset = MAXPHASE << SHIFT_UPDATE; else if (ltemp < -(MAXPHASE << SHIFT_UPDATE)) time_offset = -(MAXPHASE << SHIFT_UPDATE); else time_offset = ltemp; /* * Select whether the frequency is to be controlled and in which * mode (PLL or FLL). Clamp to the operating range. Ugly * multiply/divide should be replaced someday. */ if (time_status & STA_FREQHOLD || time_reftime == 0) time_reftime = time_second; mtemp = time_second - time_reftime; time_reftime = time_second; if (time_status & STA_FLL) { if (mtemp >= MINSEC) { ltemp = ((time_offset / mtemp) << (SHIFT_USEC - SHIFT_UPDATE)); if (ltemp < 0) time_freq -= -ltemp >> SHIFT_KH; else time_freq += ltemp >> SHIFT_KH; } } else { if (mtemp < MAXSEC) { ltemp = time_offset * mtemp; if (ltemp < 0) time_freq -= -ltemp >> ((int64_t)time_constant + time_constant + SHIFT_KF - SHIFT_USEC + SHIFT_UPDATE); else time_freq += ltemp >> ((int64_t)time_constant + time_constant + SHIFT_KF - SHIFT_USEC + SHIFT_UPDATE); } } if (time_freq > time_tolerance) time_freq = time_tolerance; else if (time_freq < -time_tolerance) time_freq = -time_tolerance; } /* * On rollover of the second the phase adjustment to be used for * the next second is calculated. Also, the maximum error is * increased by the tolerance. If the PPS frequency discipline * code is present, the phase is increased to compensate for the * CPU clock oscillator frequency error. * * On a 32-bit machine and given parameters in the timex.h * header file, the maximum phase adjustment is +-512 ms and * maximum frequency offset is a tad less than) +-512 ppm. On a * 64-bit machine, you shouldn't need to ask. */ void ntp_update_second(struct timecounter *tc) { u_int32_t *newsec; long ltemp; if (!time_daemon) return; newsec = &tc->tc_offset_sec; time_maxerror += time_tolerance >> SHIFT_USEC; /* * Compute the phase adjustment for the next second. In * PLL mode, the offset is reduced by a fixed factor * times the time constant. In FLL mode the offset is * used directly. In either mode, the maximum phase * adjustment for each second is clamped so as to spread * the adjustment over not more than the number of * seconds between updates. */ if (time_offset < 0) { ltemp = -time_offset; if (!(time_status & STA_FLL)) ltemp >>= SHIFT_KG + time_constant; if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE) ltemp = (MAXPHASE / MINSEC) << SHIFT_UPDATE; time_offset += ltemp; time_adj = -ltemp << (SHIFT_SCALE - SHIFT_UPDATE); } else { ltemp = time_offset; if (!(time_status & STA_FLL)) ltemp >>= SHIFT_KG + time_constant; if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE) ltemp = (MAXPHASE / MINSEC) << SHIFT_UPDATE; time_offset -= ltemp; time_adj = ltemp << (SHIFT_SCALE - SHIFT_UPDATE); } /* * Compute the frequency estimate and additional phase * adjustment due to frequency error for the next * second. When the PPS signal is engaged, gnaw on the * watchdog counter and update the frequency computed by * the pll and the PPS signal. */ #ifdef PPS_SYNC pps_valid++; if (pps_valid == PPS_VALID) { pps_jitter = MAXTIME; pps_stabil = MAXFREQ; time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR); } ltemp = time_freq + pps_freq; #else ltemp = time_freq; #endif /* PPS_SYNC */ if (ltemp < 0) time_adj -= -ltemp << (SHIFT_SCALE - SHIFT_USEC); else time_adj += ltemp << (SHIFT_SCALE - SHIFT_USEC); tc->tc_adjustment = time_adj; /* XXX - this is really bogus, but can't be fixed until xntpd's idea of the system clock is fixed to know how the user wants leap seconds handled; in the mean time, we assume that users of NTP are running without proper leap second support (this is now the default anyway) */ /* * Leap second processing. If in leap-insert state at * the end of the day, the system clock is set back one * second; if in leap-delete state, the system clock is * set ahead one second. The microtime() routine or * external clock driver will insure that reported time * is always monotonic. The ugly divides should be * replaced. */ switch (time_state) { case TIME_OK: if (time_status & STA_INS) time_state = TIME_INS; else if (time_status & STA_DEL) time_state = TIME_DEL; break; case TIME_INS: if ((*newsec) % 86400 == 0) { (*newsec)--; time_state = TIME_OOP; } break; case TIME_DEL: if (((*newsec) + 1) % 86400 == 0) { (*newsec)++; time_state = TIME_WAIT; } break; case TIME_OOP: time_state = TIME_WAIT; break; case TIME_WAIT: if (!(time_status & (STA_INS | STA_DEL))) time_state = TIME_OK; break; } } static int ntp_sysctl SYSCTL_HANDLER_ARGS { struct timeval atv; struct ntptimeval ntv; int s; s = splclock(); microtime(&atv); ntv.time = atv; ntv.maxerror = time_maxerror; ntv.esterror = time_esterror; splx(s); ntv.time_state = time_state; /* * Status word error decode. If any of these conditions * occur, an error is returned, instead of the status * word. Most applications will care only about the fact * the system clock may not be trusted, not about the * details. * * Hardware or software error */ if (time_status & (STA_UNSYNC | STA_CLOCKERR)) { ntv.time_state = TIME_ERROR; } /* * PPS signal lost when either time or frequency * synchronization requested */ if (time_status & (STA_PPSFREQ | STA_PPSTIME) && !(time_status & STA_PPSSIGNAL)) { ntv.time_state = TIME_ERROR; } /* * PPS jitter exceeded when time synchronization * requested */ if (time_status & STA_PPSTIME && time_status & STA_PPSJITTER) { ntv.time_state = TIME_ERROR; } /* * PPS wander exceeded or calibration error when * frequency synchronization requested */ if (time_status & STA_PPSFREQ && time_status & (STA_PPSWANDER | STA_PPSERROR)) { ntv.time_state = TIME_ERROR; } return (sysctl_handle_opaque(oidp, &ntv, sizeof ntv, req)); } SYSCTL_NODE(_kern, KERN_NTP_PLL, ntp_pll, CTLFLAG_RW, 0, "NTP kernel PLL related stuff"); SYSCTL_PROC(_kern_ntp_pll, NTP_PLL_GETTIME, gettime, CTLTYPE_OPAQUE|CTLFLAG_RD, 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval", ""); /* * ntp_adjtime() - NTP daemon application interface */ #ifndef _SYS_SYSPROTO_H_ struct ntp_adjtime_args { struct timex *tp; }; #endif int ntp_adjtime(struct proc *p, struct ntp_adjtime_args *uap) { struct timex ntv; int modes; int s; int error; time_daemon = 1; error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv)); if (error) return error; /* * Update selected clock variables - only the superuser can * change anything. Note that there is no error checking here on * the assumption the superuser should know what it is doing. */ modes = ntv.modes; if ((modes != 0) && (error = suser(p->p_cred->pc_ucred, &p->p_acflag))) return error; s = splclock(); if (modes & MOD_FREQUENCY) #ifdef PPS_SYNC time_freq = ntv.freq - pps_freq; #else /* PPS_SYNC */ time_freq = ntv.freq; #endif /* PPS_SYNC */ if (modes & MOD_MAXERROR) time_maxerror = ntv.maxerror; if (modes & MOD_ESTERROR) time_esterror = ntv.esterror; if (modes & MOD_STATUS) { time_status &= STA_RONLY; time_status |= ntv.status & ~STA_RONLY; } if (modes & MOD_TIMECONST) time_constant = ntv.constant; if (modes & MOD_OFFSET) hardupdate(ntv.offset, modes & MOD_DOSCALE); ntv.modes |= MOD_CANSCALE; /* * Retrieve all clock variables */ if (modes & MOD_DOSCALE) ntv.offset = time_offset; else if (time_offset < 0) ntv.offset = -(-time_offset >> SHIFT_UPDATE); else ntv.offset = time_offset >> SHIFT_UPDATE; #ifdef PPS_SYNC ntv.freq = time_freq + pps_freq; #else /* PPS_SYNC */ ntv.freq = time_freq; #endif /* PPS_SYNC */ ntv.maxerror = time_maxerror; ntv.esterror = time_esterror; ntv.status = time_status; ntv.constant = time_constant; ntv.precision = time_precision; ntv.tolerance = time_tolerance; #ifdef PPS_SYNC ntv.shift = pps_shift; ntv.ppsfreq = pps_freq; ntv.jitter = pps_jitter >> PPS_AVG; ntv.stabil = pps_stabil; ntv.calcnt = pps_calcnt; ntv.errcnt = pps_errcnt; ntv.jitcnt = pps_jitcnt; ntv.stbcnt = pps_stbcnt; #endif /* PPS_SYNC */ (void)splx(s); error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv)); if (!error) { /* * Status word error decode. See comments in * ntp_gettime() routine. */ p->p_retval[0] = time_state; if (time_status & (STA_UNSYNC | STA_CLOCKERR)) p->p_retval[0] = TIME_ERROR; if (time_status & (STA_PPSFREQ | STA_PPSTIME) && !(time_status & STA_PPSSIGNAL)) p->p_retval[0] = TIME_ERROR; if (time_status & STA_PPSTIME && time_status & STA_PPSJITTER) p->p_retval[0] = TIME_ERROR; if (time_status & STA_PPSFREQ && time_status & (STA_PPSWANDER | STA_PPSERROR)) p->p_retval[0] = TIME_ERROR; } return error; } #ifdef PPS_SYNC /* We need this ugly monster twice, so let's macroize it. */ #define MEDIAN3X(a, m, s, i1, i2, i3) \ do { \ m = a[i2]; \ s = a[i1] - a[i3]; \ } while (0) #define MEDIAN3(a, m, s) \ do { \ if (a[0] > a[1]) { \ if (a[1] > a[2]) \ MEDIAN3X(a, m, s, 0, 1, 2); \ else if (a[2] > a[0]) \ MEDIAN3X(a, m, s, 2, 0, 1); \ else \ MEDIAN3X(a, m, s, 0, 2, 1); \ } else { \ if (a[2] > a[1]) \ MEDIAN3X(a, m, s, 2, 1, 0); \ else if (a[0] > a[2]) \ MEDIAN3X(a, m, s, 1, 0, 2); \ else \ MEDIAN3X(a, m, s, 1, 2, 0); \ } \ } while (0) /* * hardpps() - discipline CPU clock oscillator to external PPS signal * * This routine is called at each PPS interrupt in order to discipline * the CPU clock oscillator to the PPS signal. It measures the PPS phase * and leaves it in a handy spot for the hardclock() routine. It * integrates successive PPS phase differences and calculates the * frequency offset. This is used in hardclock() to discipline the CPU * clock oscillator so that intrinsic frequency error is cancelled out. * The code requires the caller to capture the time and hardware counter * value at the on-time PPS signal transition. * * Note that, on some Unix systems, this routine runs at an interrupt * priority level higher than the timer interrupt routine hardclock(). * Therefore, the variables used are distinct from the hardclock() * variables, except for certain exceptions: The PPS frequency pps_freq * and phase pps_offset variables are determined by this routine and * updated atomically. The time_tolerance variable can be considered a * constant, since it is infrequently changed, and then only when the * PPS signal is disabled. The watchdog counter pps_valid is updated * once per second by hardclock() and is atomically cleared in this * routine. */ void hardpps(tvp, p_usec) struct timeval *tvp; /* time at PPS */ long p_usec; /* hardware counter at PPS */ { long u_usec, v_usec, bigtick; long cal_sec, cal_usec; /* * An occasional glitch can be produced when the PPS interrupt * occurs in the hardclock() routine before the time variable is * updated. Here the offset is discarded when the difference * between it and the last one is greater than tick/2, but not * if the interval since the first discard exceeds 30 s. */ time_status |= STA_PPSSIGNAL; time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR); pps_valid = 0; u_usec = -tvp->tv_usec; if (u_usec < -500000) u_usec += 1000000; v_usec = pps_offset - u_usec; if (v_usec < 0) v_usec = -v_usec; if (v_usec > (tick >> 1)) { if (pps_glitch > MAXGLITCH) { pps_glitch = 0; pps_tf[2] = u_usec; pps_tf[1] = u_usec; } else { pps_glitch++; u_usec = pps_offset; } } else pps_glitch = 0; /* * A three-stage median filter is used to help deglitch the pps * time. The median sample becomes the time offset estimate; the * difference between the other two samples becomes the time * dispersion (jitter) estimate. */ pps_tf[2] = pps_tf[1]; pps_tf[1] = pps_tf[0]; pps_tf[0] = u_usec; MEDIAN3(pps_tf, pps_offset, v_usec); if (v_usec > MAXTIME) pps_jitcnt++; v_usec = (v_usec << PPS_AVG) - pps_jitter; if (v_usec < 0) pps_jitter -= -v_usec >> PPS_AVG; else pps_jitter += v_usec >> PPS_AVG; if (pps_jitter > (MAXTIME >> 1)) time_status |= STA_PPSJITTER; /* * During the calibration interval adjust the starting time when * the tick overflows. At the end of the interval compute the * duration of the interval and the difference of the hardware * counters at the beginning and end of the interval. This code * is deliciously complicated by the fact valid differences may * exceed the value of tick when using long calibration * intervals and small ticks. Note that the counter can be * greater than tick if caught at just the wrong instant, but * the values returned and used here are correct. */ bigtick = (long)tick << SHIFT_USEC; pps_usec -= pps_freq; if (pps_usec >= bigtick) pps_usec -= bigtick; if (pps_usec < 0) pps_usec += bigtick; pps_time.tv_sec++; pps_count++; if (pps_count < (1 << pps_shift)) return; pps_count = 0; pps_calcnt++; u_usec = p_usec << SHIFT_USEC; v_usec = pps_usec - u_usec; if (v_usec >= bigtick >> 1) v_usec -= bigtick; if (v_usec < -(bigtick >> 1)) v_usec += bigtick; if (v_usec < 0) v_usec = -(-v_usec >> pps_shift); else v_usec = v_usec >> pps_shift; pps_usec = u_usec; cal_sec = tvp->tv_sec; cal_usec = tvp->tv_usec; cal_sec -= pps_time.tv_sec; cal_usec -= pps_time.tv_usec; if (cal_usec < 0) { cal_usec += 1000000; cal_sec--; } pps_time = *tvp; /* * Check for lost interrupts, noise, excessive jitter and * excessive frequency error. The number of timer ticks during * the interval may vary +-1 tick. Add to this a margin of one * tick for the PPS signal jitter and maximum frequency * deviation. If the limits are exceeded, the calibration * interval is reset to the minimum and we start over. */ u_usec = (long)tick << 1; if (!((cal_sec == -1 && cal_usec > (1000000 - u_usec)) || (cal_sec == 0 && cal_usec < u_usec)) || v_usec > time_tolerance || v_usec < -time_tolerance) { pps_errcnt++; pps_shift = PPS_SHIFT; pps_intcnt = 0; time_status |= STA_PPSERROR; return; } /* * A three-stage median filter is used to help deglitch the pps * frequency. The median sample becomes the frequency offset * estimate; the difference between the other two samples * becomes the frequency dispersion (stability) estimate. */ pps_ff[2] = pps_ff[1]; pps_ff[1] = pps_ff[0]; pps_ff[0] = v_usec; MEDIAN3(pps_ff, u_usec, v_usec); /* * Here the frequency dispersion (stability) is updated. If it * is less than one-fourth the maximum (MAXFREQ), the frequency * offset is updated as well, but clamped to the tolerance. It * will be processed later by the hardclock() routine. */ v_usec = (v_usec >> 1) - pps_stabil; if (v_usec < 0) pps_stabil -= -v_usec >> PPS_AVG; else pps_stabil += v_usec >> PPS_AVG; if (pps_stabil > MAXFREQ >> 2) { pps_stbcnt++; time_status |= STA_PPSWANDER; return; } if (time_status & STA_PPSFREQ) { if (u_usec < 0) { pps_freq -= -u_usec >> PPS_AVG; if (pps_freq < -time_tolerance) pps_freq = -time_tolerance; u_usec = -u_usec; } else { pps_freq += u_usec >> PPS_AVG; if (pps_freq > time_tolerance) pps_freq = time_tolerance; } } /* * Here the calibration interval is adjusted. If the maximum * time difference is greater than tick / 4, reduce the interval * by half. If this is not the case for four consecutive * intervals, double the interval. */ if (u_usec << pps_shift > bigtick >> 2) { pps_intcnt = 0; if (pps_shift > PPS_SHIFT) pps_shift--; } else if (pps_intcnt >= 4) { pps_intcnt = 0; if (pps_shift < PPS_SHIFTMAX) pps_shift++; } else pps_intcnt++; } #endif /* PPS_SYNC */ int std_pps_ioctl(u_long cmd, caddr_t data, pps_params_t *pp, pps_info_t *pi, int ppscap) { pps_params_t *app; pps_info_t *api; switch (cmd) { case PPS_IOC_CREATE: return (0); case PPS_IOC_DESTROY: return (0); case PPS_IOC_SETPARAMS: app = (pps_params_t *)data; if (app->mode & ~ppscap) return (EINVAL); *pp = *app; return (0); case PPS_IOC_GETPARAMS: app = (pps_params_t *)data; *app = *pp; return (0); case PPS_IOC_GETCAP: *(int*)data = ppscap; return (0); case PPS_IOC_FETCH: api = (pps_info_t *)data; *api = *pi; pi->current_mode = pp->mode; return (0); case PPS_IOC_WAIT: return (EOPNOTSUPP); default: return (ENODEV); } }