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This code is mostly taken from the 1.1 port (which was in turn taken from Dave Mills's kern.tar.Z example). A few significant differences: 1) ntp_gettime() is now a MIB variable rather than a system call. A few fiddles are done in libc to make it behave the same. 2) mono_time does not participate in the PLL adjustments. 3) A new interface has been defined (in <machine/clock.h>) for doing possibly machine-dependent things around the time of the clock update. This is used in Pentium kernels to disable interrupts, set `time', and reset the CPU cycle counter as quickly as possible to avoid jitter in microtime(). Measurements show an apparent resolution of a bit more than 8.14usec, which is reasonable given system-call overhead.
270 lines
8.0 KiB
C
270 lines
8.0 KiB
C
/******************************************************************************
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* *
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* Copyright (c) David L. Mills 1993, 1994 *
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* *
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* Permission to use, copy, modify, and distribute this software and its *
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* documentation for any purpose and without fee is hereby granted, provided *
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* that the above copyright notice appears in all copies and that both the *
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* copyright notice and this permission notice appear in supporting *
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* documentation, and that the name University of Delaware not be used in *
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* advertising or publicity pertaining to distribution of the software *
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* without specific, written prior permission. The University of Delaware *
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* makes no representations about the suitability this software for any *
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* purpose. It is provided "as is" without express or implied warranty. *
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* *
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******************************************************************************/
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/*
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* Modification history kern_ntptime.c
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*
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* 24 Mar 94 David L. Mills
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* Revised syscall interface to include new variables for PPS
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* time discipline.
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*
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* 14 Feb 94 David L. Mills
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* Added code for external clock
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*
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* 28 Nov 93 David L. Mills
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* Revised frequency scaling to conform with adjusted parameters
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*
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* 17 Sep 93 David L. Mills
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* Created file
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*/
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/*
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* ntp_gettime(), ntp_adjtime() - precision time interface for SunOS
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* 4.1.1 and 4.1.3
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*
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* These routines consitute the Network Time Protocol (NTP) interfaces
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* for user and daemon application programs. The ntp_gettime() routine
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* provides the time, maximum error (synch distance) and estimated error
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* (dispersion) to client user application programs. The ntp_adjtime()
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* routine is used by the NTP daemon to adjust the system clock to an
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* externally derived time. The time offset and related variables set by
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* this routine are used by hardclock() to adjust the phase and
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* frequency of the phase-lock loop which controls the system clock.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/proc.h>
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#include <sys/timex.h>
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#include <sys/sysctl.h>
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/*
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* The following variables are used by the hardclock() routine in the
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* kern_clock.c module and are described in that module.
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*/
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extern struct timeval time; /* kernel time variable */
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extern int time_state; /* clock state */
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extern int time_status; /* clock status bits */
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extern long time_offset; /* time adjustment (us) */
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extern long time_freq; /* frequency offset (scaled ppm) */
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extern long time_maxerror; /* maximum error (us) */
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extern long time_esterror; /* estimated error (us) */
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extern long time_constant; /* pll time constant */
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extern long time_precision; /* clock precision (us) */
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extern long time_tolerance; /* frequency tolerance (scaled ppm) */
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#ifdef PPS_SYNC
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/*
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* The following variables are used only if the PPS signal discipline
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* is configured in the kernel.
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*/
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extern int pps_shift; /* interval duration (s) (shift) */
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extern long pps_freq; /* pps frequency offset (scaled ppm) */
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extern long pps_jitter; /* pps jitter (us) */
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extern long pps_stabil; /* pps stability (scaled ppm) */
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extern long pps_jitcnt; /* jitter limit exceeded */
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extern long pps_calcnt; /* calibration intervals */
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extern long pps_errcnt; /* calibration errors */
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extern long pps_stbcnt; /* stability limit exceeded */
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#endif /* PPS_SYNC */
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int
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ntp_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp,
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void *newp, size_t newlen, struct proc *p)
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{
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struct timeval atv;
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struct ntptimeval ntv;
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int s;
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/* All names at this level are terminal. */
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if (namelen != 1) {
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return ENOTDIR;
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}
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if (name[0] != NTP_PLL_GETTIME) {
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return EOPNOTSUPP;
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}
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s = splclock();
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#ifdef EXT_CLOCK
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/*
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* The microtime() external clock routine returns a
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* status code. If less than zero, we declare an error
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* in the clock status word and return the kernel
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* (software) time variable. While there are other
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* places that call microtime(), this is the only place
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* that matters from an application point of view.
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*/
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if (microtime(&atv) < 0) {
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time_status |= STA_CLOCKERR;
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ntv.time = time;
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} else {
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time_status &= ~STA_CLOCKERR;
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}
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#else /* EXT_CLOCK */
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microtime(&atv);
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#endif /* EXT_CLOCK */
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ntv.time = atv;
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ntv.maxerror = time_maxerror;
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ntv.esterror = time_esterror;
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splx(s);
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ntv.time_state = time_state;
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/*
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* Status word error decode. If any of these conditions
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* occur, an error is returned, instead of the status
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* word. Most applications will care only about the fact
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* the system clock may not be trusted, not about the
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* details.
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*
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* Hardware or software error
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*/
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if (time_status & (STA_UNSYNC | STA_CLOCKERR)) {
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ntv.time_state = TIME_ERROR;
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}
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/*
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* PPS signal lost when either time or frequency
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* synchronization requested
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*/
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if (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
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!(time_status & STA_PPSSIGNAL)) {
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ntv.time_state = TIME_ERROR;
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}
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/*
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* PPS jitter exceeded when time synchronization
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* requested
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*/
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if (time_status & STA_PPSTIME &&
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time_status & STA_PPSJITTER) {
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ntv.time_state = TIME_ERROR;
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}
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/*
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* PPS wander exceeded or calibration error when
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* frequency synchronization requested
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*/
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if (time_status & STA_PPSFREQ &&
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time_status & (STA_PPSWANDER | STA_PPSERROR)) {
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ntv.time_state = TIME_ERROR;
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}
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return(sysctl_rdstruct(oldp, oldlenp, newp, &ntv, sizeof ntv));
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}
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/*
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* ntp_adjtime() - NTP daemon application interface
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*/
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struct ntp_adjtime_args {
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struct timex *tp;
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};
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int
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ntp_adjtime(struct proc *p, struct ntp_adjtime_args *uap, int *retval)
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{
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struct timex ntv;
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int modes;
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int s;
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int error;
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error = copyin((caddr_t)uap->tp, (caddr_t)&ntv, sizeof(ntv));
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if (error)
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return error;
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/*
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* Update selected clock variables - only the superuser can
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* change anything. Note that there is no error checking here on
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* the assumption the superuser should know what it is doing.
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*/
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modes = ntv.modes;
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if ((modes != 0)
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&& (error = suser(p->p_cred->pc_ucred, &p->p_acflag)))
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return error;
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s = splclock();
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if (modes & MOD_FREQUENCY)
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#ifdef PPS_SYNC
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time_freq = ntv.freq - pps_freq;
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#else /* PPS_SYNC */
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time_freq = ntv.freq;
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#endif /* PPS_SYNC */
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if (modes & MOD_MAXERROR)
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time_maxerror = ntv.maxerror;
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if (modes & MOD_ESTERROR)
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time_esterror = ntv.esterror;
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if (modes & MOD_STATUS) {
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time_status &= STA_RONLY;
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time_status |= ntv.status & ~STA_RONLY;
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}
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if (modes & MOD_TIMECONST)
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time_constant = ntv.constant;
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if (modes & MOD_OFFSET)
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hardupdate(ntv.offset);
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/*
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* Retrieve all clock variables
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*/
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if (time_offset < 0)
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ntv.offset = -(-time_offset >> SHIFT_UPDATE);
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else
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ntv.offset = time_offset >> SHIFT_UPDATE;
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#ifdef PPS_SYNC
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ntv.freq = time_freq + pps_freq;
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#else /* PPS_SYNC */
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ntv.freq = time_freq;
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#endif /* PPS_SYNC */
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ntv.maxerror = time_maxerror;
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ntv.esterror = time_esterror;
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ntv.status = time_status;
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ntv.constant = time_constant;
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ntv.precision = time_precision;
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ntv.tolerance = time_tolerance;
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#ifdef PPS_SYNC
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ntv.shift = pps_shift;
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ntv.ppsfreq = pps_freq;
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ntv.jitter = pps_jitter >> PPS_AVG;
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ntv.stabil = pps_stabil;
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ntv.calcnt = pps_calcnt;
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ntv.errcnt = pps_errcnt;
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ntv.jitcnt = pps_jitcnt;
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ntv.stbcnt = pps_stbcnt;
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#endif /* PPS_SYNC */
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(void)splx(s);
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error = copyout((caddr_t)&ntv, (caddr_t)uap->tp, sizeof(ntv));
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if (!error) {
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/*
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* Status word error decode. See comments in
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* ntp_gettime() routine.
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*/
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retval[0] = time_state;
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if (time_status & (STA_UNSYNC | STA_CLOCKERR))
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retval[0] = TIME_ERROR;
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if (time_status & (STA_PPSFREQ | STA_PPSTIME) &&
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!(time_status & STA_PPSSIGNAL))
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retval[0] = TIME_ERROR;
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if (time_status & STA_PPSTIME &&
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time_status & STA_PPSJITTER)
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retval[0] = TIME_ERROR;
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if (time_status & STA_PPSFREQ &&
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time_status & (STA_PPSWANDER | STA_PPSERROR))
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retval[0] = TIME_ERROR;
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}
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return error;
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}
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