/*
* ntp_loopfilter.c - implements the NTP loop filter algorithm
*
* ATTENTION: Get approval from Dave Mills on all changes to this file!
*
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include "ntpd.h"
#include "ntp_io.h"
#include "ntp_unixtime.h"
#include "ntp_stdlib.h"
#include <stdio.h>
#include <ctype.h>
#include <signal.h>
#include <setjmp.h>
#if defined(VMS) && defined(VMS_LOCALUNIT) /*wjm*/
#include "ntp_refclock.h"
#endif /* VMS */
#ifdef KERNEL_PLL
#include "ntp_syscall.h"
#endif /* KERNEL_PLL */
/*
* This is an implementation of the clock discipline algorithm described
* in UDel TR 97-4-3, as amended. It operates as an adaptive parameter,
* hybrid phase/frequency-lock loop. A number of sanity checks are
* included to protect against timewarps, timespikes and general mayhem.
* All units are in s and s/s, unless noted otherwise.
*/
#define CLOCK_MAX .128 /* default step threshold (s) */
#define CLOCK_MINSTEP 900. /* default stepout threshold (s) */
#define CLOCK_PANIC 1000. /* default panic threshold (s) */
#define CLOCK_PHI 15e-6 /* max frequency error (s/s) */
#define CLOCK_PLL 16. /* PLL loop gain (log2) */
#define CLOCK_AVG 8. /* parameter averaging constant */
#define CLOCK_FLL .25 /* FLL loop gain */
#define CLOCK_ALLAN 11 /* Allan intercept (log2 s) */
#define CLOCK_DAY 86400. /* one day in seconds (s) */
#define CLOCK_JUNE (CLOCK_DAY * 30) /* June in seconds (s) */
#define CLOCK_LIMIT 30 /* poll-adjust threshold */
#define CLOCK_PGATE 4. /* poll-adjust gate */
#define PPS_MAXAGE 120 /* kernel pps signal timeout (s) */
#define FREQTOD(x) ((x) / 65536e6) /* NTP to double */
#define DTOFREQ(x) ((int32)((x) * 65536e6)) /* double to NTP */
/*
* Clock discipline state machine. This is used to control the
* synchronization behavior during initialization and following a
* timewarp.
*
* State < step > step Comments
* ========================================================
* NSET FREQ step, FREQ freq not set
*
* FSET SYNC step, SYNC freq set
*
* FREQ if (mu < 900) if (mu < 900) set freq direct
* ignore ignore
* else else
* freq, SYNC freq, step, SYNC
*
* SYNC SYNC SPIK, ignore adjust phase/freq
*
* SPIK SYNC if (mu < 900) adjust phase/freq
* ignore
* step, SYNC
*/
/*
* Kernel PLL/PPS state machine. This is used with the kernel PLL
* modifications described in the documentation.
*
* If kernel support for the ntp_adjtime() system call is available, the
* ntp_control flag is set. The ntp_enable and kern_enable flags can be
* set at configuration time or run time using ntpdc. If ntp_enable is
* false, the discipline loop is unlocked and no corrections of any kind
* are made. If both ntp_control and kern_enable are set, the kernel
* support is used as described above; if false, the kernel is bypassed
* entirely and the daemon discipline used instead.
*
* There have been three versions of the kernel discipline code. The
* first (microkernel) now in Solaris discipilnes the microseconds. The
* second and third (nanokernel) disciplines the clock in nanoseconds.
* These versions are identifed if the symbol STA_PLL is present in the
* header file /usr/include/sys/timex.h. The third and current version
* includes TAI offset and is identified by the symbol NTP_API with
* value 4.
*
* Each PPS time/frequency discipline can be enabled by the atom driver
* or another driver. If enabled, the STA_PPSTIME and STA_FREQ bits are
* set in the kernel status word; otherwise, these bits are cleared.
* These bits are also cleard if the kernel reports an error.
*
* If an external clock is present, the clock driver sets STA_CLK in the
* status word. When the local clock driver sees this bit, it updates
* via this routine, which then calls ntp_adjtime() with the STA_PLL bit
* set to zero, in which case the system clock is not adjusted. This is
* also a signal for the external clock driver to discipline the system
* clock. Unless specified otherwise, all times are in seconds.
*/
/*
* Program variables that can be tinkered.
*/
double clock_max = CLOCK_MAX; /* step threshold */
double clock_minstep = CLOCK_MINSTEP; /* stepout threshold */
double clock_panic = CLOCK_PANIC; /* panic threshold */
double clock_phi = CLOCK_PHI; /* dispersion rate (s/s) */
u_char allan_xpt = CLOCK_ALLAN; /* Allan intercept (log2 s) */
/*
* Program variables
*/
static double clock_offset; /* offset */
double clock_jitter; /* offset jitter */
double drift_comp; /* frequency (s/s) */
double clock_stability; /* frequency stability (wander) (s/s) */
double clock_codec; /* audio codec frequency (samples/s) */
static u_long clock_epoch; /* last update */
u_int sys_tai; /* TAI offset from UTC */
static void rstclock (int, double); /* transition function */
static double direct_freq(double); /* direct set frequency */
static void set_freq(double); /* set frequency */
#ifdef KERNEL_PLL
static struct timex ntv; /* ntp_adjtime() parameters */
int pll_status; /* last kernel status bits */
#if defined(STA_NANO) && NTP_API == 4
static u_int loop_tai; /* last TAI offset */
#endif /* STA_NANO */
#endif /* KERNEL_PLL */
/*
* Clock state machine control flags
*/
int ntp_enable = 1; /* clock discipline enabled */
int pll_control; /* kernel support available */
int kern_enable = 1; /* kernel support enabled */
int pps_enable; /* kernel PPS discipline enabled */
int ext_enable; /* external clock enabled */
int pps_stratum; /* pps stratum */
int allow_panic = FALSE; /* allow panic correction */
int mode_ntpdate = FALSE; /* exit on first clock set */
/*
* Clock state machine variables
*/
int state; /* clock discipline state */
u_char sys_poll; /* time constant/poll (log2 s) */
int tc_counter; /* jiggle counter */
double last_offset; /* last offset (s) */
static u_long last_step; /* last clock step */
/*
* Huff-n'-puff filter variables
*/
static double *sys_huffpuff; /* huff-n'-puff filter */
static int sys_hufflen; /* huff-n'-puff filter stages */
static int sys_huffptr; /* huff-n'-puff filter pointer */
static double sys_mindly; /* huff-n'-puff filter min delay */
#if defined(KERNEL_PLL)
/* Emacs cc-mode goes nuts if we split the next line... */
#define MOD_BITS (MOD_OFFSET | MOD_MAXERROR | MOD_ESTERROR | \
MOD_STATUS | MOD_TIMECONST)
#ifdef SIGSYS
static void pll_trap (int); /* configuration trap */
static struct sigaction sigsys; /* current sigaction status */
static struct sigaction newsigsys; /* new sigaction status */
static sigjmp_buf env; /* environment var. for pll_trap() */
#endif /* SIGSYS */
#endif /* KERNEL_PLL */
/*
* init_loopfilter - initialize loop filter data
*/
void
init_loopfilter(void)
{
/*
* Initialize state variables.
*/
sys_poll = ntp_minpoll;
clock_jitter = LOGTOD(sys_precision);
}
/*
* local_clock - the NTP logical clock loop filter.
*
* Return codes:
* -1 update ignored: exceeds panic threshold
* 0 update ignored: popcorn or exceeds step threshold
* 1 clock was slewed
* 2 clock was stepped
*
* LOCKCLOCK: The only thing this routine does is set the
* sys_rootdisp variable equal to the peer dispersion.
*/
int
local_clock(
struct peer *peer, /* synch source peer structure */
double fp_offset /* clock offset (s) */
)
{
int rval; /* return code */
int osys_poll; /* old system poll */
double mu; /* interval since last update */
double clock_frequency; /* clock frequency */
double dtemp, etemp; /* double temps */
char tbuf[80]; /* report buffer */
/*
* If the loop is opened or the NIST LOCKCLOCK is in use,
* monitor and record the offsets anyway in order to determine
* the open-loop response and then go home.
*/
#ifdef LOCKCLOCK
return (0);
#else /* LOCKCLOCK */
if (!ntp_enable) {
record_loop_stats(fp_offset, drift_comp, clock_jitter,
clock_stability, sys_poll);
return (0);
}
/*
* If the clock is way off, panic is declared. The clock_panic
* defaults to 1000 s; if set to zero, the panic will never
* occur. The allow_panic defaults to FALSE, so the first panic
* will exit. It can be set TRUE by a command line option, in
* which case the clock will be set anyway and time marches on.
* But, allow_panic will be set FALSE when the update is less
* than the step threshold; so, subsequent panics will exit.
*/
if (fabs(fp_offset) > clock_panic && clock_panic > 0 &&
!allow_panic) {
snprintf(tbuf, sizeof(tbuf),
"%+.0f s; set clock manually within %.0f s.",
fp_offset, clock_panic);
report_event(EVNT_SYSFAULT, NULL, tbuf);
return (-1);
}
/*
* This section simulates ntpdate. If the offset exceeds the
* step threshold (128 ms), step the clock to that time and
* exit. Othewise, slew the clock to that time and exit. Note
* that the slew will persist and eventually complete beyond the
* life of this program. Note that while ntpdate is active, the
* terminal does not detach, so the termination message prints
* directly to the terminal.
*/
if (mode_ntpdate) {
if (fabs(fp_offset) > clock_max && clock_max > 0) {
step_systime(fp_offset);
msyslog(LOG_NOTICE, "ntpd: time set %+.6f s",
fp_offset);
printf("ntpd: time set %+.6fs\n", fp_offset);
} else {
adj_systime(fp_offset);
msyslog(LOG_NOTICE, "ntpd: time slew %+.6f s",
fp_offset);
printf("ntpd: time slew %+.6fs\n", fp_offset);
}
record_loop_stats(fp_offset, drift_comp, clock_jitter,
clock_stability, sys_poll);
exit (0);
}
/*
* The huff-n'-puff filter finds the lowest delay in the recent
* interval. This is used to correct the offset by one-half the
* difference between the sample delay and minimum delay. This
* is most effective if the delays are highly assymetric and
* clockhopping is avoided and the clock frequency wander is
* relatively small.
*/
if (sys_huffpuff != NULL) {
if (peer->delay < sys_huffpuff[sys_huffptr])
sys_huffpuff[sys_huffptr] = peer->delay;
if (peer->delay < sys_mindly)
sys_mindly = peer->delay;
if (fp_offset > 0)
dtemp = -(peer->delay - sys_mindly) / 2;
else
dtemp = (peer->delay - sys_mindly) / 2;
fp_offset += dtemp;
#ifdef DEBUG
if (debug)
printf(
"local_clock: size %d mindly %.6f huffpuff %.6f\n",
sys_hufflen, sys_mindly, dtemp);
#endif
}
/*
* Clock state machine transition function which defines how the
* system reacts to large phase and frequency excursion. There
* are two main regimes: when the offset exceeds the step
* threshold (128 ms) and when it does not. Under certain
* conditions updates are suspended until the stepout theshold
* (900 s) is exceeded. See the documentation on how these
* thresholds interact with commands and command line options.
*
* Note the kernel is disabled if step is disabled or greater
* than 0.5 s or in ntpdate mode.
*/
osys_poll = sys_poll;
if (sys_poll < peer->minpoll)
sys_poll = peer->minpoll;
if (sys_poll > peer->maxpoll)
sys_poll = peer->maxpoll;
mu = current_time - clock_epoch;
clock_frequency = drift_comp;
rval = 1;
if (fabs(fp_offset) > clock_max && clock_max > 0) {
switch (state) {
/*
* In SYNC state we ignore the first outlyer and switch
* to SPIK state.
*/
case EVNT_SYNC:
snprintf(tbuf, sizeof(tbuf), "%+.6f s",
fp_offset);
report_event(EVNT_SPIK, NULL, tbuf);
state = EVNT_SPIK;
return (0);
/*
* In FREQ state we ignore outlyers and inlyers. At the
* first outlyer after the stepout threshold, compute
* the apparent frequency correction and step the phase.
*/
case EVNT_FREQ:
if (mu < clock_minstep)
return (0);
clock_frequency = direct_freq(fp_offset);
/* fall through to S_SPIK */
/*
* In SPIK state we ignore succeeding outlyers until
* either an inlyer is found or the stepout threshold is
* exceeded.
*/
case EVNT_SPIK:
if (mu < clock_minstep)
return (0);
/* fall through to default */
/*
* We get here by default in NSET and FSET states and
* from above in FREQ or SPIK states.
*
* In NSET state an initial frequency correction is not
* available, usually because the frequency file has not
* yet been written. Since the time is outside the step
* threshold, the clock is stepped. The frequency will
* be set directly following the stepout interval.
*
* In FSET state the initial frequency has been set from
* the frequency file. Since the time is outside the
* step threshold, the clock is stepped immediately,
* rather than after the stepout interval. Guys get
* nervous if it takes 15 minutes to set the clock for
* the first time.
*
* In FREQ and SPIK states the stepout threshold has
* expired and the phase is still above the step
* threshold. Note that a single spike greater than the
* step threshold is always suppressed, even with a
* long time constant.
*/
default:
snprintf(tbuf, sizeof(tbuf), "%+.6f s",
fp_offset);
report_event(EVNT_CLOCKRESET, NULL, tbuf);
step_systime(fp_offset);
reinit_timer();
tc_counter = 0;
clock_jitter = LOGTOD(sys_precision);
rval = 2;
if (state == EVNT_NSET || (current_time -
last_step) < clock_minstep * 2) {
rstclock(EVNT_FREQ, 0);
return (rval);
}
last_step = current_time;
break;
}
rstclock(EVNT_SYNC, 0);
} else {
/*
* The offset is less than the step threshold. Calculate
* the jitter as the exponentially weighted offset
* differences.
*/
etemp = SQUARE(clock_jitter);
dtemp = SQUARE(max(fabs(fp_offset - last_offset),
LOGTOD(sys_precision)));
clock_jitter = SQRT(etemp + (dtemp - etemp) /
CLOCK_AVG);
switch (state) {
/*
* In NSET state this is the first update received and
* the frequency has not been initialized. Adjust the
* phase, but do not adjust the frequency until after
* the stepout threshold.
*/
case EVNT_NSET:
rstclock(EVNT_FREQ, fp_offset);
break;
/*
* In FSET state this is the first update received and
* the frequency has been initialized. Adjust the phase,
* but do not adjust the frequency until the next
* update.
*/
case EVNT_FSET:
rstclock(EVNT_SYNC, fp_offset);
break;
/*
* In FREQ state ignore updates until the stepout
* threshold. After that, compute the new frequency, but
* do not adjust the phase or frequency until the next
* update.
*/
case EVNT_FREQ:
if (mu < clock_minstep)
return (0);
clock_frequency = direct_freq(fp_offset);
rstclock(EVNT_SYNC, 0);
break;
/*
* We get here by default in SYNC and SPIK states. Here
* we compute the frequency update due to PLL and FLL
* contributions.
*/
default:
allow_panic = FALSE;
/*
* The FLL and PLL frequency gain constants
* depend on the time constant and Allan
* intercept. The PLL is always used, but
* becomes ineffective above the Allan intercept
* where the FLL becomes effective.
*/
if (sys_poll >= allan_xpt)
clock_frequency += (fp_offset -
clock_offset) /
max(ULOGTOD(sys_poll), mu) *
CLOCK_FLL;
/*
* The PLL frequency gain (numerator) depends on
* the minimum of the update interval and Allan
* intercept. This reduces the PLL gain when the
* FLL becomes effective.
*/
etemp = min(ULOGTOD(allan_xpt), mu);
dtemp = 4 * CLOCK_PLL * ULOGTOD(sys_poll);
clock_frequency += fp_offset * etemp / (dtemp *
dtemp);
rstclock(EVNT_SYNC, fp_offset);
break;
}
}
#ifdef KERNEL_PLL
/*
* This code segment works when clock adjustments are made using
* precision time kernel support and the ntp_adjtime() system
* call. This support is available in Solaris 2.6 and later,
* Digital Unix 4.0 and later, FreeBSD, Linux and specially
* modified kernels for HP-UX 9 and Ultrix 4. In the case of the
* DECstation 5000/240 and Alpha AXP, additional kernel
* modifications provide a true microsecond clock and nanosecond
* clock, respectively.
*
* Important note: The kernel discipline is used only if the
* step threshold is less than 0.5 s, as anything higher can
* lead to overflow problems. This might occur if some misguided
* lad set the step threshold to something ridiculous.
*/
if (pll_control && kern_enable) {
/*
* We initialize the structure for the ntp_adjtime()
* system call. We have to convert everything to
* microseconds or nanoseconds first. Do not update the
* system variables if the ext_enable flag is set. In
* this case, the external clock driver will update the
* variables, which will be read later by the local
* clock driver. Afterwards, remember the time and
* frequency offsets for jitter and stability values and
* to update the frequency file.
*/
memset(&ntv, 0, sizeof(ntv));
if (ext_enable) {
ntv.modes = MOD_STATUS;
} else {
#ifdef STA_NANO
ntv.modes = MOD_BITS | MOD_NANO;
#else /* STA_NANO */
ntv.modes = MOD_BITS;
#endif /* STA_NANO */
if (clock_offset < 0)
dtemp = -.5;
else
dtemp = .5;
#ifdef STA_NANO
ntv.offset = (int32)(clock_offset * 1e9 +
dtemp);
ntv.constant = sys_poll;
#else /* STA_NANO */
ntv.offset = (int32)(clock_offset * 1e6 +
dtemp);
ntv.constant = sys_poll - 4;
#endif /* STA_NANO */
ntv.esterror = (u_int32)(clock_jitter * 1e6);
ntv.maxerror = (u_int32)((sys_rootdelay / 2 +
sys_rootdisp) * 1e6);
ntv.status = STA_PLL;
/*
* Enable/disable the PPS if requested.
*/
if (pps_enable) {
if (!(pll_status & STA_PPSTIME))
report_event(EVNT_KERN,
NULL, "PPS enabled");
ntv.status |= STA_PPSTIME | STA_PPSFREQ;
} else {
if (pll_status & STA_PPSTIME)
report_event(EVNT_KERN,
NULL, "PPS disabled");
ntv.status &= ~(STA_PPSTIME |
STA_PPSFREQ);
}
if (sys_leap == LEAP_ADDSECOND)
ntv.status |= STA_INS;
else if (sys_leap == LEAP_DELSECOND)
ntv.status |= STA_DEL;
}
/*
* Pass the stuff to the kernel. If it squeals, turn off
* the pps. In any case, fetch the kernel offset,
* frequency and jitter.
*/
if (ntp_adjtime(&ntv) == TIME_ERROR) {
if (!(ntv.status & STA_PPSSIGNAL))
report_event(EVNT_KERN, NULL,
"PPS no signal");
}
pll_status = ntv.status;
#ifdef STA_NANO
clock_offset = ntv.offset / 1e9;
#else /* STA_NANO */
clock_offset = ntv.offset / 1e6;
#endif /* STA_NANO */
clock_frequency = FREQTOD(ntv.freq);
/*
* If the kernel PPS is lit, monitor its performance.
*/
if (ntv.status & STA_PPSTIME) {
#ifdef STA_NANO
clock_jitter = ntv.jitter / 1e9;
#else /* STA_NANO */
clock_jitter = ntv.jitter / 1e6;
#endif /* STA_NANO */
}
#if defined(STA_NANO) && NTP_API == 4
/*
* If the TAI changes, update the kernel TAI.
*/
if (loop_tai != sys_tai) {
loop_tai = sys_tai;
ntv.modes = MOD_TAI;
ntv.constant = sys_tai;
ntp_adjtime(&ntv);
}
#endif /* STA_NANO */
}
#endif /* KERNEL_PLL */
/*
* Clamp the frequency within the tolerance range and calculate
* the frequency difference since the last update.
*/
if (fabs(clock_frequency) > NTP_MAXFREQ)
msyslog(LOG_NOTICE,
"frequency error %.0f PPM exceeds tolerance %.0f PPM",
clock_frequency * 1e6, NTP_MAXFREQ * 1e6);
dtemp = SQUARE(clock_frequency - drift_comp);
if (clock_frequency > NTP_MAXFREQ)
drift_comp = NTP_MAXFREQ;
else if (clock_frequency < -NTP_MAXFREQ)
drift_comp = -NTP_MAXFREQ;
else
drift_comp = clock_frequency;
/*
* Calculate the wander as the exponentially weighted RMS
* frequency differences. Record the change for the frequency
* file update.
*/
etemp = SQUARE(clock_stability);
clock_stability = SQRT(etemp + (dtemp - etemp) / CLOCK_AVG);
drift_file_sw = TRUE;
/*
* Here we adjust the timeconstan by comparing the current
* offset with the clock jitter. If the offset is less than the
* clock jitter times a constant, then the averaging interval is
* increased, otherwise it is decreased. A bit of hysteresis
* helps calm the dance. Works best using burst mode.
*/
if (fabs(clock_offset) < CLOCK_PGATE * clock_jitter) {
tc_counter += sys_poll;
if (tc_counter > CLOCK_LIMIT) {
tc_counter = CLOCK_LIMIT;
if (sys_poll < peer->maxpoll) {
tc_counter = 0;
sys_poll++;
}
}
} else {
tc_counter -= sys_poll << 1;
if (tc_counter < -CLOCK_LIMIT) {
tc_counter = -CLOCK_LIMIT;
if (sys_poll > peer->minpoll) {
tc_counter = 0;
sys_poll--;
}
}
}
/*
* If the time constant has changed, update the poll variables.
*/
if (osys_poll != sys_poll)
poll_update(peer, sys_poll);
/*
* Yibbidy, yibbbidy, yibbidy; that'h all folks.
*/
record_loop_stats(clock_offset, drift_comp, clock_jitter,
clock_stability, sys_poll);
#ifdef DEBUG
if (debug)
printf(
"local_clock: offset %.9f jit %.9f freq %.3f stab %.3f poll %d\n",
clock_offset, clock_jitter, drift_comp * 1e6,
clock_stability * 1e6, sys_poll);
#endif /* DEBUG */
return (rval);
#endif /* LOCKCLOCK */
}
/*
* adj_host_clock - Called once every second to update the local clock.
*
* LOCKCLOCK: The only thing this routine does is increment the
* sys_rootdisp variable.
*/
void
adj_host_clock(
void
)
{
double adjustment;
/*
* Update the dispersion since the last update. In contrast to
* NTPv3, NTPv4 does not declare unsynchronized after one day,
* since the dispersion check serves this function. Also,
* since the poll interval can exceed one day, the old test
* would be counterproductive.
*/
sys_rootdisp += clock_phi;
#ifndef LOCKCLOCK
/*
* If clock discipline is disabled or if the kernel is enabled,
* get out of Dodge quick.
*/
if (!ntp_enable || mode_ntpdate || (pll_control &&
kern_enable))
return;
/*
* Implement the phase and frequency adjustments. The gain
* factor (denominator) increases with poll interval, so is
* dominated by the FLL above the Allan intercept.
*/
adjustment = clock_offset / (CLOCK_PLL * ULOGTOD(sys_poll));
clock_offset -= adjustment;
adj_systime(adjustment + drift_comp);
#endif /* LOCKCLOCK */
}
/*
* Clock state machine. Enter new state and set state variables.
*/
static void
rstclock(
int trans, /* new state */
double offset /* new offset */
)
{
#ifdef DEBUG
if (debug > 1)
printf("local_clock: mu %lu state %d poll %d count %d\n",
current_time - clock_epoch, trans, sys_poll,
tc_counter);
#endif
if (trans != state && trans != EVNT_FSET)
report_event(trans, NULL, NULL);
state = trans;
last_offset = clock_offset = offset;
clock_epoch = current_time;
}
/*
* calc_freq - calculate frequency directly
*
* This is very carefully done. When the offset is first computed at the
* first update, a residual frequency component results. Subsequently,
* updates are suppresed until the end of the measurement interval while
* the offset is amortized. At the end of the interval the frequency is
* calculated from the current offset, residual offset, length of the
* interval and residual frequency component. At the same time the
* frequenchy file is armed for update at the next hourly stats.
*/
static double
direct_freq(
double fp_offset
)
{
#ifdef KERNEL_PLL
/*
* If the kernel is enabled, we need the residual offset to
* calculate the frequency correction.
*/
if (pll_control && kern_enable) {
memset(&ntv, 0, sizeof(ntv));
ntp_adjtime(&ntv);
#ifdef STA_NANO
clock_offset = ntv.offset / 1e9;
#else /* STA_NANO */
clock_offset = ntv.offset / 1e6;
#endif /* STA_NANO */
drift_comp = FREQTOD(ntv.freq);
}
#endif /* KERNEL_PLL */
set_freq((fp_offset - clock_offset) / (current_time -
clock_epoch) + drift_comp);
wander_resid = 0;
return (drift_comp);
}
/*
* set_freq - set clock frequency
*/
static void
set_freq(
double freq /* frequency update */
)
{
char tbuf[80];
drift_comp = freq;
#ifdef KERNEL_PLL
/*
* If the kernel is enabled, update the kernel frequency.
*/
if (pll_control && kern_enable) {
memset(&ntv, 0, sizeof(ntv));
ntv.modes = MOD_FREQUENCY;
ntv.freq = DTOFREQ(drift_comp);
ntp_adjtime(&ntv);
snprintf(tbuf, sizeof(tbuf), "kernel %.3f PPM",
drift_comp * 1e6);
report_event(EVNT_FSET, NULL, tbuf);
} else {
snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM",
drift_comp * 1e6);
report_event(EVNT_FSET, NULL, tbuf);
}
#else /* KERNEL_PLL */
snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp *
1e6);
report_event(EVNT_FSET, NULL, tbuf);
#endif /* KERNEL_PLL */
}
/*
* huff-n'-puff filter
*/
void
huffpuff()
{
int i;
if (sys_huffpuff == NULL)
return;
sys_huffptr = (sys_huffptr + 1) % sys_hufflen;
sys_huffpuff[sys_huffptr] = 1e9;
sys_mindly = 1e9;
for (i = 0; i < sys_hufflen; i++) {
if (sys_huffpuff[i] < sys_mindly)
sys_mindly = sys_huffpuff[i];
}
}
/*
* loop_config - configure the loop filter
*
* LOCKCLOCK: The LOOP_DRIFTINIT and LOOP_DRIFTCOMP cases are no-ops.
*/
void
loop_config(
int item,
double freq
)
{
int i;
#ifdef DEBUG
if (debug > 1)
printf("loop_config: item %d freq %f\n", item, freq);
#endif
switch (item) {
/*
* We first assume the kernel supports the ntp_adjtime()
* syscall. If that syscall works, initialize the kernel time
* variables. Otherwise, continue leaving no harm behind.
*/
case LOOP_DRIFTINIT:
#ifndef LOCKCLOCK
#ifdef KERNEL_PLL
if (mode_ntpdate)
break;
pll_control = 1;
memset(&ntv, 0, sizeof(ntv));
ntv.modes = MOD_BITS;
ntv.status = STA_PLL;
ntv.maxerror = MAXDISPERSE;
ntv.esterror = MAXDISPERSE;
ntv.constant = sys_poll;
#ifdef SIGSYS
/*
* Use sigsetjmp() to save state and then call
* ntp_adjtime(); if it fails, then siglongjmp() is used
* to return control
*/
newsigsys.sa_handler = pll_trap;
newsigsys.sa_flags = 0;
if (sigaction(SIGSYS, &newsigsys, &sigsys)) {
msyslog(LOG_ERR,
"sigaction() fails to save SIGSYS trap: %m");
pll_control = 0;
}
if (sigsetjmp(env, 1) == 0)
ntp_adjtime(&ntv);
if ((sigaction(SIGSYS, &sigsys,
(struct sigaction *)NULL))) {
msyslog(LOG_ERR,
"sigaction() fails to restore SIGSYS trap: %m");
pll_control = 0;
}
#else /* SIGSYS */
ntp_adjtime(&ntv);
#endif /* SIGSYS */
/*
* Save the result status and light up an external clock
* if available.
*/
pll_status = ntv.status;
if (pll_control) {
#ifdef STA_NANO
if (pll_status & STA_CLK)
ext_enable = 1;
#endif /* STA_NANO */
report_event(EVNT_KERN, NULL,
"kernel time sync enabled");
}
#endif /* KERNEL_PLL */
#endif /* LOCKCLOCK */
break;
/*
* Initialize the frequency. If the frequency file is missing or
* broken, set the initial frequency to zero and set the state
* to NSET. Otherwise, set the initial frequency to the given
* value and the state to FSET.
*/
case LOOP_DRIFTCOMP:
#ifndef LOCKCLOCK
if (freq > NTP_MAXFREQ || freq < -NTP_MAXFREQ) {
set_freq(0);
rstclock(EVNT_NSET, 0);
} else {
set_freq(freq);
rstclock(EVNT_FSET, 0);
}
#endif /* LOCKCLOCK */
break;
/*
* Disable the kernel at shutdown. The microkernel just abandons
* ship. The nanokernel carefully cleans up so applications can
* see this. Note the last programmed offset and frequency are
* left in place.
*/
case LOOP_KERN_CLEAR:
#ifndef LOCKCLOCK
#ifdef KERNEL_PLL
if (pll_control && kern_enable) {
memset((char *)&ntv, 0, sizeof(ntv));
ntv.modes = MOD_STATUS;
ntv.status = STA_UNSYNC;
ntp_adjtime(&ntv);
report_event(EVNT_KERN, NULL,
"kernel time sync disabledx");
}
#endif /* KERNEL_PLL */
#endif /* LOCKCLOCK */
break;
/*
* Tinker command variables for Ulrich Windl. Very dangerous.
*/
case LOOP_ALLAN: /* Allan intercept (log2) (allan) */
allan_xpt = (u_char)freq;
break;
case LOOP_CODEC: /* audio codec frequency (codec) */
clock_codec = freq / 1e6;
break;
case LOOP_PHI: /* dispersion threshold (dispersion) */
clock_phi = freq / 1e6;
break;
case LOOP_FREQ: /* initial frequency (freq) */
set_freq(freq / 1e6);
rstclock(EVNT_FSET, 0);
break;
case LOOP_HUFFPUFF: /* huff-n'-puff length (huffpuff) */
if (freq < HUFFPUFF)
freq = HUFFPUFF;
sys_hufflen = (int)(freq / HUFFPUFF);
sys_huffpuff = (double *)emalloc(sizeof(double) *
sys_hufflen);
for (i = 0; i < sys_hufflen; i++)
sys_huffpuff[i] = 1e9;
sys_mindly = 1e9;
break;
case LOOP_PANIC: /* panic threshold (panic) */
clock_panic = freq;
break;
case LOOP_MAX: /* step threshold (step) */
clock_max = freq;
if (clock_max == 0 || clock_max > 0.5)
kern_enable = 0;
break;
case LOOP_MINSTEP: /* stepout threshold (stepout) */
clock_minstep = freq;
break;
case LOOP_LEAP: /* not used */
default:
msyslog(LOG_NOTICE,
"loop_config: unsupported option %d", item);
}
}
#if defined(KERNEL_PLL) && defined(SIGSYS)
/*
* _trap - trap processor for undefined syscalls
*
* This nugget is called by the kernel when the SYS_ntp_adjtime()
* syscall bombs because the silly thing has not been implemented in
* the kernel. In this case the phase-lock loop is emulated by
* the stock adjtime() syscall and a lot of indelicate abuse.
*/
static RETSIGTYPE
pll_trap(
int arg
)
{
pll_control = 0;
siglongjmp(env, 1);
}
#endif /* KERNEL_PLL && SIGSYS */
FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>