* In order for this driver to work, the local clock must be set to
* within +-500 ms by another means, such as a radio clock or NTP
* itself. The 1-pps signal is connected via a serial port and gadget
- * box consisting of a one-shot and RS232 level converter. When operated
- * at 38.4 kbps with a SPARCstation IPC, this arrangement has a worst-
- * case jitter less than 26 us.
+ * box consisting of a one-shot flopflop and RS232 level converter.
+ * Conntection is either via the carrier detect (DCD) lead or via the
+ * receive data (RD) lead. The incidental jitter using the DCD lead is
+ * essentially the interrupt latency. The incidental jitter using the RD
+ * lead has an additional component due to the line sampling clock. When
+ * operated at 38.4 kbps, this arrangement has a worst-case jitter less
+ * than 26 us.
*
- * There are three ways in which this driver can be used. The first way
- * uses the LDISC_PPS line discipline and works only for the baseboard
- * serial ports of the Sun SPARCstation. The PPS signal is connected via
- * a gadget box to the carrier detect (CD) line of a serial port and
- * flag3 of the driver configured for that port is set. This causes the
- * ppsclock streams module to be configured for that port and capture a
- * timestamp at the on-time transition of the PPS signal. This driver
- * then reads the timestamp directly by a designated ioctl() system
- * call. This provides the most accurate time and least jitter of any
- * other scheme. There is no need to configure a dedicated device for
- * this purpose, which ordinarily is the device used for the associated
- * radio clock.
+ * There are four ways in which this driver can be used. They are
+ * described in decreasing order of merit below. The first way uses the
+ * ppsapi STREAMS module and the LDISC_PPS line discipline, while the
+ * second way uses the ppsclock STREAMS module and the LDISC_PPS line
+ * discipline. Either of these works only for the baseboard serial ports
+ * of the Sun SPARC IPC and clones. However, the ppsapi uses the
+ * proposed IETF interface expected to become standard for PPS signals.
+ * The serial port to be used is specified by the pps command in the
+ * configuration file. This driver reads the timestamp directly by a
+ * designated ioctl() system call.
*
- * The second way uses the LDISC_CLKPPS line discipline and works for
+ * The third way uses the LDISC_CLKPPS line discipline and works for
* any architecture supporting a serial port. If after a few seconds
* this driver finds no ppsclock module configured, it attempts to open
* a serial port device /dev/pps%d, where %d is the unit number, and
* discipline, this produces an ASCII DEL character ('\377') followed by
* a timestamp at each seconds epoch.
*
- * The third way involves an auxiliary radio clock driver which calls
+ * The fourth way involves an auxiliary radio clock driver which calls
* the PPS driver with a timestamp captured by that driver. This use is
* documented in the source code for the driver(s) involved. Note that
* some drivers collect the sample information themselves before calling
- * our pps_sample(), and others call us knowing only that they are running
- * shortly after an on-time tick and they expect us to retrieve the PPS
+ * pps_sample(), and others call knowing only that they are running
+ * shortly after an on-time tick and they expect to retrieve the PPS
* offset, fudge their result, and insert it into the timestream.
*
* Fudge Factors
*
- * There are no special fudge factors other than the generic and those
- * explicitly defined above. The fudge time1 parameter can be used to
- * compensate for miscellaneous UART and OS delays. Allow about 247 us
- * for uart delays at 38400 bps and about 1 ms for SunOS streams
- * nonsense.
+ * There are no special fudge factors other than the generic. The fudge
+ * time1 parameter can be used to compensate for miscellaneous UART and
+ * OS delays. Allow about 247 us for uart delays at 38400 bps and about
+ * 1 ms for STREAMS nonsense with older workstations. Velocities may
+ * vary with modern workstations.
*/
-
/*
* Interface definitions
*/
{
register struct atomunit *up;
struct refclockproc *pp;
- struct timespec *tsp;
+ struct timespec ts;
l_fp lftmp;
double doffset;
int i;
* Convert the timeval to l_fp and save for billboards. Sign-
* extend the fraction and stash in the buffer. No harm is done
* if previous data are overwritten. If the discipline comes bum
- * or the data grow stale, just forget it.
+ * or the data grow stale, just forget it. Round the nanoseconds
+ * to microseconds with great care.
*/
#ifdef HAVE_PPSAPI
i = up->pps_info.assert_sequence;
return (1);
if (i == up->pps_info.assert_sequence)
return (2);
- if(pps_assert)
- tsp = &up->pps_info.assert_timestamp;
+ if (pps_assert)
+ ts = up->pps_info.assert_timestamp;
else
- tsp = &up->pps_info.clear_timestamp;
- pp->lastrec.l_ui = tsp->tv_sec + JAN_1970;
- TVUTOTSF(tsp->tv_nsec, pp->lastrec.l_uf);
-
-printf("pps %d %s\n", up->pps_info.assert_sequence, lfptoa(&pp->lastrec, 6));
-
+ ts = up->pps_info.clear_timestamp;
+ pp->lastrec.l_ui = ts.tv_sec + JAN_1970;
+ ts.tv_nsec = (ts.tv_nsec + 500) / 1000;
+ if (ts.tv_nsec > 1000000) {
+ ts.tv_nsec -= 1000000;
+ ts.tv_sec++;
+ }
+ TVUTOTSF(ts.tv_nsec, pp->lastrec.l_uf);
#else
-
i = up->ev.serial;
if (fdpps <= 0)
return (1);
L_CLR(&lftmp);
L_ADDF(&lftmp, pp->lastrec.l_f);
LFPTOD(&lftmp, doffset);
- pp->filter[pp->coderecv++ % pp->nstages] = -doffset + pp->fudgetime1;
+ pp->filter[pp->coderecv++ % pp->nstages] = -doffset +
+ pp->fudgetime1;
up->pollcnt = 2 * 60;
return (0);
}
/*
* Save the timestamp for billboards. Sign-extend the fraction
* and stash in the buffer. No harm is done if previous data are
- * overwritten. Do this only if the ppsclock gizmo is not working.
+ * overwritten. Do this only if the ppsclock gizmo is not
+ * working.
*/
if (up->flags & FLAG_PPS)
return;
double doffset;
/*
- * This routine is called once per second when the external clock driver
- * processes PPS information. It processes the pps timestamp
- * and saves the sign-extended fraction in a circular
+ * This routine is called once per second when the external
+ * clock driver processes PPS information. It processes the pps
+ * timestamp and saves the sign-extended fraction in a circular
* buffer for processing at the next poll event.
*/
peer = pps_peer;
-
if (peer == 0) /* nobody home */
return 1;
-
pp = peer->procptr;
up = (struct atomunit *)pp->unitptr;
L_CLR(&lftmp);
L_ADDF(&lftmp, pp->lastrec.l_f);
LFPTOD(&lftmp, doffset);
- pp->filter[pp->coderecv++ % pp->nstages] = -doffset + pp->fudgetime1;
+ pp->filter[pp->coderecv++ % pp->nstages] = -doffset +
+ pp->fudgetime1;
up->pollcnt = 2 * 60;
return (0);
}
/*
* Accumulate samples in the median filter. At the end of each
- * poll interval, do a little bookeeping and process the samples.
+ * poll interval, do a little bookeeping and process the
+ * samples.
*/
pp = peer->procptr;
up = (struct atomunit *)pp->unitptr;
#if defined(PPS) || defined(HAVE_PPSAPI)
if (!(up->flags & FLAG_AUX)) {
- if (atom_pps(peer))
- return;
+ if (atom_pps(peer))
+ return;
}
if (peer->burst > 0)
return;
* the pps time is within +-0.5 s of the local time and the
* seconds numbering is unambiguous.
*/
- if (pps_update)
+ if (pps_update) {
pp->leap = LEAP_NOWARNING;
- else {
+ } else {
pp->leap = LEAP_NOTINSYNC;
return;
}
projects / thirdparty / ntp.git / commitdiff
