[rtems commit] kern_ntptime.c: Import from FreeBSD
Sebastian Huber
sebh at rtems.org
Mon Feb 21 13:14:59 UTC 2022
Module: rtems
Branch: master
Commit: 91057b3bdfa5c339a4435d0826e1581acd0ce197
Changeset: http://git.rtems.org/rtems/commit/?id=91057b3bdfa5c339a4435d0826e1581acd0ce197
Author: Sebastian Huber <sebastian.huber at embedded-brains.de>
Date: Mon Feb 7 15:37:54 2022 +0100
kern_ntptime.c: Import from FreeBSD
The file was imported from this repository:
https://github.com/freebsd/freebsd.git
This commit was used:
commit 3ec0dc367bff27c345ad83240625b2057af391b9
Author: Sebastian Huber <sebastian.huber at embedded-brains.de>
Date: Mon Feb 7 14:16:16 2022 -0700
kern_ntptime.c: Remove ntp_init()
The ntp_init() function did set a couple of global objects to zero. These
objects are in the .bss section and already initialized to zero during kernel
or module loading.
Update #2348.
---
cpukit/score/src/kern_ntptime.c | 1053 +++++++++++++++++++++++++++++++++++++++
1 file changed, 1053 insertions(+)
diff --git a/cpukit/score/src/kern_ntptime.c b/cpukit/score/src/kern_ntptime.c
new file mode 100644
index 0000000..96f14a4
--- /dev/null
+++ b/cpukit/score/src/kern_ntptime.c
@@ -0,0 +1,1053 @@
+/*-
+ ***********************************************************************
+ * *
+ * Copyright (c) David L. Mills 1993-2001 *
+ * *
+ * 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. *
+ * *
+ **********************************************************************/
+
+/*
+ * Adapted from the original sources for FreeBSD and timecounters by:
+ * Poul-Henning Kamp <phk at FreeBSD.org>.
+ *
+ * The 32bit version of the "LP" macros seems a bit past its "sell by"
+ * date so I have retained only the 64bit version and included it directly
+ * in this file.
+ *
+ * Only minor changes done to interface with the timecounters over in
+ * sys/kern/kern_clock.c. Some of the comments below may be (even more)
+ * confusing and/or plain wrong in that context.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include "opt_ntp.h"
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/sysproto.h>
+#include <sys/eventhandler.h>
+#include <sys/kernel.h>
+#include <sys/priv.h>
+#include <sys/proc.h>
+#include <sys/lock.h>
+#include <sys/mutex.h>
+#include <sys/time.h>
+#include <sys/timex.h>
+#include <sys/timetc.h>
+#include <sys/timepps.h>
+#include <sys/syscallsubr.h>
+#include <sys/sysctl.h>
+
+#ifdef PPS_SYNC
+FEATURE(pps_sync, "Support usage of external PPS signal by kernel PLL");
+#endif
+
+/*
+ * Single-precision macros for 64-bit machines
+ */
+typedef int64_t l_fp;
+#define L_ADD(v, u) ((v) += (u))
+#define L_SUB(v, u) ((v) -= (u))
+#define L_ADDHI(v, a) ((v) += (int64_t)(a) << 32)
+#define L_NEG(v) ((v) = -(v))
+#define L_RSHIFT(v, n) \
+ do { \
+ if ((v) < 0) \
+ (v) = -(-(v) >> (n)); \
+ else \
+ (v) = (v) >> (n); \
+ } while (0)
+#define L_MPY(v, a) ((v) *= (a))
+#define L_CLR(v) ((v) = 0)
+#define L_ISNEG(v) ((v) < 0)
+#define L_LINT(v, a) ((v) = (int64_t)(a) << 32)
+#define L_GINT(v) ((v) < 0 ? -(-(v) >> 32) : (v) >> 32)
+
+/*
+ * Generic NTP kernel interface
+ *
+ * These routines constitute 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 other routines in this module to adjust the
+ * phase and frequency of the clock discipline loop which controls the
+ * system clock.
+ *
+ * When the kernel time is reckoned directly in nanoseconds (NTP_NANO
+ * defined), the time at each tick interrupt is derived directly from
+ * the kernel time variable. When the kernel time is reckoned in
+ * microseconds, (NTP_NANO undefined), the time is derived from the
+ * kernel time variable together with a variable representing the
+ * leftover nanoseconds at the last tick interrupt. In either case, the
+ * current nanosecond time is reckoned from these values plus an
+ * interpolated value derived by the clock routines in another
+ * architecture-specific module. The interpolation can use either a
+ * dedicated counter or a processor cycle counter (PCC) implemented in
+ * some architectures.
+ *
+ * Note that all routines must run at priority splclock or higher.
+ */
+/*
+ * Phase/frequency-lock loop (PLL/FLL) definitions
+ *
+ * The nanosecond clock discipline uses two variable types, time
+ * variables and frequency variables. Both types are represented as 64-
+ * bit fixed-point quantities with the decimal point between two 32-bit
+ * halves. On a 32-bit machine, each half is represented as a single
+ * word and mathematical operations are done using multiple-precision
+ * arithmetic. On a 64-bit machine, ordinary computer arithmetic is
+ * used.
+ *
+ * A time variable is a signed 64-bit fixed-point number in ns and
+ * fraction. It represents the remaining time offset to be amortized
+ * over succeeding tick interrupts. The maximum time offset is about
+ * 0.5 s and the resolution is about 2.3e-10 ns.
+ *
+ * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
+ * 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
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |s s s| ns |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | fraction |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *
+ * A frequency variable is a signed 64-bit fixed-point number in ns/s
+ * and fraction. It represents the ns and fraction to be added to the
+ * kernel time variable at each second. The maximum frequency offset is
+ * about +-500000 ns/s and the resolution is about 2.3e-10 ns/s.
+ *
+ * 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
+ * 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
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |s s s s s s s s s s s s s| ns/s |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * | fraction |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ */
+/*
+ * The following variables establish the state of the PLL/FLL and the
+ * residual time and frequency offset of the local clock.
+ */
+#define SHIFT_PLL 4 /* PLL loop gain (shift) */
+#define SHIFT_FLL 2 /* FLL loop gain (shift) */
+
+static int time_state = TIME_OK; /* clock state */
+int time_status = STA_UNSYNC; /* clock status bits */
+static long time_tai; /* TAI offset (s) */
+static long time_monitor; /* last time offset scaled (ns) */
+static long time_constant; /* poll interval (shift) (s) */
+static long time_precision = 1; /* clock precision (ns) */
+static long time_maxerror = MAXPHASE / 1000; /* maximum error (us) */
+long time_esterror = MAXPHASE / 1000; /* estimated error (us) */
+static long time_reftime; /* uptime at last adjustment (s) */
+static l_fp time_offset; /* time offset (ns) */
+static l_fp time_freq; /* frequency offset (ns/s) */
+static l_fp time_adj; /* tick adjust (ns/s) */
+
+static int64_t time_adjtime; /* correction from adjtime(2) (usec) */
+
+static struct mtx ntp_lock;
+MTX_SYSINIT(ntp, &ntp_lock, "ntp", MTX_SPIN);
+
+#define NTP_LOCK() mtx_lock_spin(&ntp_lock)
+#define NTP_UNLOCK() mtx_unlock_spin(&ntp_lock)
+#define NTP_ASSERT_LOCKED() mtx_assert(&ntp_lock, MA_OWNED)
+
+#ifdef PPS_SYNC
+/*
+ * The following variables are used when a pulse-per-second (PPS) signal
+ * is available and connected via a modem control lead. They establish
+ * the engineering parameters of the clock discipline loop when
+ * controlled by the PPS signal.
+ */
+#define PPS_FAVG 2 /* min freq avg interval (s) (shift) */
+#define PPS_FAVGDEF 8 /* default freq avg int (s) (shift) */
+#define PPS_FAVGMAX 15 /* max freq avg interval (s) (shift) */
+#define PPS_PAVG 4 /* phase avg interval (s) (shift) */
+#define PPS_VALID 120 /* PPS signal watchdog max (s) */
+#define PPS_MAXWANDER 100000 /* max PPS wander (ns/s) */
+#define PPS_POPCORN 2 /* popcorn spike threshold (shift) */
+
+static struct timespec pps_tf[3]; /* phase median filter */
+static l_fp pps_freq; /* scaled frequency offset (ns/s) */
+static long pps_fcount; /* frequency accumulator */
+static long pps_jitter; /* nominal jitter (ns) */
+static long pps_stabil; /* nominal stability (scaled ns/s) */
+static long pps_lastsec; /* time at last calibration (s) */
+static int pps_valid; /* signal watchdog counter */
+static int pps_shift = PPS_FAVG; /* interval duration (s) (shift) */
+static int pps_shiftmax = PPS_FAVGDEF; /* max interval duration (s) (shift) */
+static int pps_intcnt; /* wander counter */
+
+/*
+ * PPS signal quality monitors
+ */
+static long pps_calcnt; /* calibration intervals */
+static long pps_jitcnt; /* jitter limit exceeded */
+static long pps_stbcnt; /* stability limit exceeded */
+static long pps_errcnt; /* calibration errors */
+#endif /* PPS_SYNC */
+/*
+ * End of phase/frequency-lock loop (PLL/FLL) definitions
+ */
+
+static void hardupdate(long offset);
+static void ntp_gettime1(struct ntptimeval *ntvp);
+static bool ntp_is_time_error(int tsl);
+
+static bool
+ntp_is_time_error(int tsl)
+{
+
+ /*
+ * 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 ((tsl & (STA_UNSYNC | STA_CLOCKERR)) ||
+
+ /*
+ * PPS signal lost when either time or frequency synchronization
+ * requested
+ */
+ (tsl & (STA_PPSFREQ | STA_PPSTIME) &&
+ !(tsl & STA_PPSSIGNAL)) ||
+
+ /*
+ * PPS jitter exceeded when time synchronization requested
+ */
+ (tsl & STA_PPSTIME && tsl & STA_PPSJITTER) ||
+
+ /*
+ * PPS wander exceeded or calibration error when frequency
+ * synchronization requested
+ */
+ (tsl & STA_PPSFREQ &&
+ tsl & (STA_PPSWANDER | STA_PPSERROR)))
+ return (true);
+
+ return (false);
+}
+
+static void
+ntp_gettime1(struct ntptimeval *ntvp)
+{
+ struct timespec atv; /* nanosecond time */
+
+ NTP_ASSERT_LOCKED();
+
+ nanotime(&atv);
+ ntvp->time.tv_sec = atv.tv_sec;
+ ntvp->time.tv_nsec = atv.tv_nsec;
+ ntvp->maxerror = time_maxerror;
+ ntvp->esterror = time_esterror;
+ ntvp->tai = time_tai;
+ ntvp->time_state = time_state;
+
+ if (ntp_is_time_error(time_status))
+ ntvp->time_state = TIME_ERROR;
+}
+
+/*
+ * ntp_gettime() - NTP user application interface
+ *
+ * See the timex.h header file for synopsis and API description. Note that
+ * the TAI offset is returned in the ntvtimeval.tai structure member.
+ */
+#ifndef _SYS_SYSPROTO_H_
+struct ntp_gettime_args {
+ struct ntptimeval *ntvp;
+};
+#endif
+/* ARGSUSED */
+int
+sys_ntp_gettime(struct thread *td, struct ntp_gettime_args *uap)
+{
+ struct ntptimeval ntv;
+
+ memset(&ntv, 0, sizeof(ntv));
+
+ NTP_LOCK();
+ ntp_gettime1(&ntv);
+ NTP_UNLOCK();
+
+ td->td_retval[0] = ntv.time_state;
+ return (copyout(&ntv, uap->ntvp, sizeof(ntv)));
+}
+
+static int
+ntp_sysctl(SYSCTL_HANDLER_ARGS)
+{
+ struct ntptimeval ntv; /* temporary structure */
+
+ memset(&ntv, 0, sizeof(ntv));
+
+ NTP_LOCK();
+ ntp_gettime1(&ntv);
+ NTP_UNLOCK();
+
+ return (sysctl_handle_opaque(oidp, &ntv, sizeof(ntv), req));
+}
+
+SYSCTL_NODE(_kern, OID_AUTO, ntp_pll, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
+ "");
+SYSCTL_PROC(_kern_ntp_pll, OID_AUTO, gettime, CTLTYPE_OPAQUE | CTLFLAG_RD |
+ CTLFLAG_MPSAFE, 0, sizeof(struct ntptimeval) , ntp_sysctl, "S,ntptimeval",
+ "");
+
+#ifdef PPS_SYNC
+SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shiftmax, CTLFLAG_RW,
+ &pps_shiftmax, 0, "Max interval duration (sec) (shift)");
+SYSCTL_INT(_kern_ntp_pll, OID_AUTO, pps_shift, CTLFLAG_RW,
+ &pps_shift, 0, "Interval duration (sec) (shift)");
+SYSCTL_LONG(_kern_ntp_pll, OID_AUTO, time_monitor, CTLFLAG_RD,
+ &time_monitor, 0, "Last time offset scaled (ns)");
+
+SYSCTL_S64(_kern_ntp_pll, OID_AUTO, pps_freq, CTLFLAG_RD | CTLFLAG_MPSAFE,
+ &pps_freq, 0,
+ "Scaled frequency offset (ns/sec)");
+SYSCTL_S64(_kern_ntp_pll, OID_AUTO, time_freq, CTLFLAG_RD | CTLFLAG_MPSAFE,
+ &time_freq, 0,
+ "Frequency offset (ns/sec)");
+#endif
+
+/*
+ * ntp_adjtime() - NTP daemon application interface
+ *
+ * See the timex.h header file for synopsis and API description. Note that
+ * the timex.constant structure member has a dual purpose to set the time
+ * constant and to set the TAI offset.
+ */
+int
+kern_ntp_adjtime(struct thread *td, struct timex *ntv, int *retvalp)
+{
+ long freq; /* frequency ns/s) */
+ int modes; /* mode bits from structure */
+ int error, retval;
+
+ /*
+ * 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.
+ * Note that either the time constant or TAI offset are loaded
+ * from the ntv.constant member, depending on the mode bits. If
+ * the STA_PLL bit in the status word is cleared, the state and
+ * status words are reset to the initial values at boot.
+ */
+ modes = ntv->modes;
+ error = 0;
+ if (modes)
+ error = priv_check(td, PRIV_NTP_ADJTIME);
+ if (error != 0)
+ return (error);
+ NTP_LOCK();
+ if (modes & MOD_MAXERROR)
+ time_maxerror = ntv->maxerror;
+ if (modes & MOD_ESTERROR)
+ time_esterror = ntv->esterror;
+ if (modes & MOD_STATUS) {
+ if (time_status & STA_PLL && !(ntv->status & STA_PLL)) {
+ time_state = TIME_OK;
+ time_status = STA_UNSYNC;
+#ifdef PPS_SYNC
+ pps_shift = PPS_FAVG;
+#endif /* PPS_SYNC */
+ }
+ time_status &= STA_RONLY;
+ time_status |= ntv->status & ~STA_RONLY;
+ }
+ if (modes & MOD_TIMECONST) {
+ if (ntv->constant < 0)
+ time_constant = 0;
+ else if (ntv->constant > MAXTC)
+ time_constant = MAXTC;
+ else
+ time_constant = ntv->constant;
+ }
+ if (modes & MOD_TAI) {
+ if (ntv->constant > 0) /* XXX zero & negative numbers ? */
+ time_tai = ntv->constant;
+ }
+#ifdef PPS_SYNC
+ if (modes & MOD_PPSMAX) {
+ if (ntv->shift < PPS_FAVG)
+ pps_shiftmax = PPS_FAVG;
+ else if (ntv->shift > PPS_FAVGMAX)
+ pps_shiftmax = PPS_FAVGMAX;
+ else
+ pps_shiftmax = ntv->shift;
+ }
+#endif /* PPS_SYNC */
+ if (modes & MOD_NANO)
+ time_status |= STA_NANO;
+ if (modes & MOD_MICRO)
+ time_status &= ~STA_NANO;
+ if (modes & MOD_CLKB)
+ time_status |= STA_CLK;
+ if (modes & MOD_CLKA)
+ time_status &= ~STA_CLK;
+ if (modes & MOD_FREQUENCY) {
+ freq = (ntv->freq * 1000LL) >> 16;
+ if (freq > MAXFREQ)
+ L_LINT(time_freq, MAXFREQ);
+ else if (freq < -MAXFREQ)
+ L_LINT(time_freq, -MAXFREQ);
+ else {
+ /*
+ * ntv->freq is [PPM * 2^16] = [us/s * 2^16]
+ * time_freq is [ns/s * 2^32]
+ */
+ time_freq = ntv->freq * 1000LL * 65536LL;
+ }
+#ifdef PPS_SYNC
+ pps_freq = time_freq;
+#endif /* PPS_SYNC */
+ }
+ if (modes & MOD_OFFSET) {
+ if (time_status & STA_NANO)
+ hardupdate(ntv->offset);
+ else
+ hardupdate(ntv->offset * 1000);
+ }
+
+ /*
+ * Retrieve all clock variables. Note that the TAI offset is
+ * returned only by ntp_gettime();
+ */
+ if (time_status & STA_NANO)
+ ntv->offset = L_GINT(time_offset);
+ else
+ ntv->offset = L_GINT(time_offset) / 1000; /* XXX rounding ? */
+ ntv->freq = L_GINT((time_freq / 1000LL) << 16);
+ ntv->maxerror = time_maxerror;
+ ntv->esterror = time_esterror;
+ ntv->status = time_status;
+ ntv->constant = time_constant;
+ if (time_status & STA_NANO)
+ ntv->precision = time_precision;
+ else
+ ntv->precision = time_precision / 1000;
+ ntv->tolerance = MAXFREQ * SCALE_PPM;
+#ifdef PPS_SYNC
+ ntv->shift = pps_shift;
+ ntv->ppsfreq = L_GINT((pps_freq / 1000LL) << 16);
+ if (time_status & STA_NANO)
+ ntv->jitter = pps_jitter;
+ else
+ ntv->jitter = pps_jitter / 1000;
+ ntv->stabil = pps_stabil;
+ ntv->calcnt = pps_calcnt;
+ ntv->errcnt = pps_errcnt;
+ ntv->jitcnt = pps_jitcnt;
+ ntv->stbcnt = pps_stbcnt;
+#endif /* PPS_SYNC */
+ retval = ntp_is_time_error(time_status) ? TIME_ERROR : time_state;
+ NTP_UNLOCK();
+
+ *retvalp = retval;
+ return (0);
+}
+
+#ifndef _SYS_SYSPROTO_H_
+struct ntp_adjtime_args {
+ struct timex *tp;
+};
+#endif
+
+int
+sys_ntp_adjtime(struct thread *td, struct ntp_adjtime_args *uap)
+{
+ struct timex ntv;
+ int error, retval;
+
+ error = copyin(uap->tp, &ntv, sizeof(ntv));
+ if (error == 0) {
+ error = kern_ntp_adjtime(td, &ntv, &retval);
+ if (error == 0) {
+ error = copyout(&ntv, uap->tp, sizeof(ntv));
+ if (error == 0)
+ td->td_retval[0] = retval;
+ }
+ }
+ return (error);
+}
+
+/*
+ * second_overflow() - called after ntp_tick_adjust()
+ *
+ * This routine is ordinarily called immediately following the above
+ * routine ntp_tick_adjust(). While these two routines are normally
+ * combined, they are separated here only for the purposes of
+ * simulation.
+ */
+void
+ntp_update_second(int64_t *adjustment, time_t *newsec)
+{
+ int tickrate;
+ l_fp ftemp; /* 32/64-bit temporary */
+
+ NTP_LOCK();
+
+ /*
+ * On rollover of the second both the nanosecond and microsecond
+ * clocks are updated and the state machine cranked as
+ * necessary. The phase adjustment to be used for the next
+ * second is calculated and the maximum error is increased by
+ * the tolerance.
+ */
+ time_maxerror += MAXFREQ / 1000;
+
+ /*
+ * 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 nano_time() routine or
+ * external clock driver will insure that reported time
+ * is always monotonic.
+ */
+ switch (time_state) {
+ /*
+ * No warning.
+ */
+ case TIME_OK:
+ if (time_status & STA_INS)
+ time_state = TIME_INS;
+ else if (time_status & STA_DEL)
+ time_state = TIME_DEL;
+ break;
+
+ /*
+ * Insert second 23:59:60 following second
+ * 23:59:59.
+ */
+ case TIME_INS:
+ if (!(time_status & STA_INS))
+ time_state = TIME_OK;
+ else if ((*newsec) % 86400 == 0) {
+ (*newsec)--;
+ time_state = TIME_OOP;
+ time_tai++;
+ }
+ break;
+
+ /*
+ * Delete second 23:59:59.
+ */
+ case TIME_DEL:
+ if (!(time_status & STA_DEL))
+ time_state = TIME_OK;
+ else if (((*newsec) + 1) % 86400 == 0) {
+ (*newsec)++;
+ time_tai--;
+ time_state = TIME_WAIT;
+ }
+ break;
+
+ /*
+ * Insert second in progress.
+ */
+ case TIME_OOP:
+ time_state = TIME_WAIT;
+ break;
+
+ /*
+ * Wait for status bits to clear.
+ */
+ case TIME_WAIT:
+ if (!(time_status & (STA_INS | STA_DEL)))
+ time_state = TIME_OK;
+ }
+
+ /*
+ * Compute the total time adjustment for the next second
+ * in ns. The offset is reduced by a factor depending on
+ * whether the PPS signal is operating. Note that the
+ * value is in effect scaled by the clock frequency,
+ * since the adjustment is added at each tick interrupt.
+ */
+ ftemp = time_offset;
+#ifdef PPS_SYNC
+ /* XXX even if PPS signal dies we should finish adjustment ? */
+ if (time_status & STA_PPSTIME && time_status &
+ STA_PPSSIGNAL)
+ L_RSHIFT(ftemp, pps_shift);
+ else
+ L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
+#else
+ L_RSHIFT(ftemp, SHIFT_PLL + time_constant);
+#endif /* PPS_SYNC */
+ time_adj = ftemp;
+ L_SUB(time_offset, ftemp);
+ L_ADD(time_adj, time_freq);
+
+ /*
+ * Apply any correction from adjtime(2). If more than one second
+ * off we slew at a rate of 5ms/s (5000 PPM) else 500us/s (500 PPM)
+ * until the last second is slewed the final < 500 usecs.
+ */
+ if (time_adjtime != 0) {
+ if (time_adjtime > 1000000)
+ tickrate = 5000;
+ else if (time_adjtime < -1000000)
+ tickrate = -5000;
+ else if (time_adjtime > 500)
+ tickrate = 500;
+ else if (time_adjtime < -500)
+ tickrate = -500;
+ else
+ tickrate = time_adjtime;
+ time_adjtime -= tickrate;
+ L_LINT(ftemp, tickrate * 1000);
+ L_ADD(time_adj, ftemp);
+ }
+ *adjustment = time_adj;
+
+#ifdef PPS_SYNC
+ if (pps_valid > 0)
+ pps_valid--;
+ else
+ time_status &= ~STA_PPSSIGNAL;
+#endif /* PPS_SYNC */
+
+ NTP_UNLOCK();
+}
+
+/*
+ * 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 oscillators and nominal update
+ * intervals less than 256 s, operation should be in phase-lock mode,
+ * where the loop is disciplined to phase. For update intervals greater
+ * than 1024 s, operation should be in frequency-lock mode, where the
+ * loop is disciplined to frequency. Between 256 s and 1024 s, the mode
+ * is selected by the STA_MODE status bit.
+ */
+static void
+hardupdate(offset)
+ long offset; /* clock offset (ns) */
+{
+ long mtemp;
+ l_fp ftemp;
+
+ NTP_ASSERT_LOCKED();
+
+ /*
+ * Select how the phase is to be controlled and from which
+ * source. If the PPS signal is present and enabled to
+ * discipline the time, the PPS offset is used; otherwise, the
+ * argument offset is used.
+ */
+ if (!(time_status & STA_PLL))
+ return;
+ if (!(time_status & STA_PPSTIME && time_status &
+ STA_PPSSIGNAL)) {
+ if (offset > MAXPHASE)
+ time_monitor = MAXPHASE;
+ else if (offset < -MAXPHASE)
+ time_monitor = -MAXPHASE;
+ else
+ time_monitor = offset;
+ L_LINT(time_offset, time_monitor);
+ }
+
+ /*
+ * Select how the frequency is to be controlled and in which
+ * mode (PLL or FLL). If the PPS signal is present and enabled
+ * to discipline the frequency, the PPS frequency is used;
+ * otherwise, the argument offset is used to compute it.
+ */
+ if (time_status & STA_PPSFREQ && time_status & STA_PPSSIGNAL) {
+ time_reftime = time_uptime;
+ return;
+ }
+ if (time_status & STA_FREQHOLD || time_reftime == 0)
+ time_reftime = time_uptime;
+ mtemp = time_uptime - time_reftime;
+ L_LINT(ftemp, time_monitor);
+ L_RSHIFT(ftemp, (SHIFT_PLL + 2 + time_constant) << 1);
+ L_MPY(ftemp, mtemp);
+ L_ADD(time_freq, ftemp);
+ time_status &= ~STA_MODE;
+ if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp >
+ MAXSEC)) {
+ L_LINT(ftemp, (time_monitor << 4) / mtemp);
+ L_RSHIFT(ftemp, SHIFT_FLL + 4);
+ L_ADD(time_freq, ftemp);
+ time_status |= STA_MODE;
+ }
+ time_reftime = time_uptime;
+ if (L_GINT(time_freq) > MAXFREQ)
+ L_LINT(time_freq, MAXFREQ);
+ else if (L_GINT(time_freq) < -MAXFREQ)
+ L_LINT(time_freq, -MAXFREQ);
+}
+
+#ifdef PPS_SYNC
+/*
+ * 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. There are two independent
+ * first-order feedback loops, one for the phase, the other for the
+ * frequency. The phase loop measures and grooms the PPS phase offset
+ * and leaves it in a handy spot for the seconds overflow routine. The
+ * frequency loop averages successive PPS phase differences and
+ * calculates the PPS frequency offset, which is also processed by the
+ * seconds overflow routine. The code requires the caller to capture the
+ * time and architecture-dependent hardware counter values in
+ * nanoseconds 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 the actual time and frequency variables, which
+ * are determined by this routine and updated atomically.
+ *
+ * tsp - time at PPS
+ * nsec - hardware counter at PPS
+ */
+void
+hardpps(struct timespec *tsp, long nsec)
+{
+ long u_sec, u_nsec, v_nsec; /* temps */
+ l_fp ftemp;
+
+ NTP_LOCK();
+
+ /*
+ * The signal is first processed by a range gate and frequency
+ * discriminator. The range gate rejects noise spikes outside
+ * the range +-500 us. The frequency discriminator rejects input
+ * signals with apparent frequency outside the range 1 +-500
+ * PPM. If two hits occur in the same second, we ignore the
+ * later hit; if not and a hit occurs outside the range gate,
+ * keep the later hit for later comparison, but do not process
+ * it.
+ */
+ time_status |= STA_PPSSIGNAL | STA_PPSJITTER;
+ time_status &= ~(STA_PPSWANDER | STA_PPSERROR);
+ pps_valid = PPS_VALID;
+ u_sec = tsp->tv_sec;
+ u_nsec = tsp->tv_nsec;
+ if (u_nsec >= (NANOSECOND >> 1)) {
+ u_nsec -= NANOSECOND;
+ u_sec++;
+ }
+ v_nsec = u_nsec - pps_tf[0].tv_nsec;
+ if (u_sec == pps_tf[0].tv_sec && v_nsec < NANOSECOND - MAXFREQ)
+ goto out;
+ pps_tf[2] = pps_tf[1];
+ pps_tf[1] = pps_tf[0];
+ pps_tf[0].tv_sec = u_sec;
+ pps_tf[0].tv_nsec = u_nsec;
+
+ /*
+ * Compute the difference between the current and previous
+ * counter values. If the difference exceeds 0.5 s, assume it
+ * has wrapped around, so correct 1.0 s. If the result exceeds
+ * the tick interval, the sample point has crossed a tick
+ * boundary during the last second, so correct the tick. Very
+ * intricate.
+ */
+ u_nsec = nsec;
+ if (u_nsec > (NANOSECOND >> 1))
+ u_nsec -= NANOSECOND;
+ else if (u_nsec < -(NANOSECOND >> 1))
+ u_nsec += NANOSECOND;
+ pps_fcount += u_nsec;
+ if (v_nsec > MAXFREQ || v_nsec < -MAXFREQ)
+ goto out;
+ time_status &= ~STA_PPSJITTER;
+
+ /*
+ * A three-stage median filter is used to help denoise the PPS
+ * time. The median sample becomes the time offset estimate; the
+ * difference between the other two samples becomes the time
+ * dispersion (jitter) estimate.
+ */
+ if (pps_tf[0].tv_nsec > pps_tf[1].tv_nsec) {
+ if (pps_tf[1].tv_nsec > pps_tf[2].tv_nsec) {
+ v_nsec = pps_tf[1].tv_nsec; /* 0 1 2 */
+ u_nsec = pps_tf[0].tv_nsec - pps_tf[2].tv_nsec;
+ } else if (pps_tf[2].tv_nsec > pps_tf[0].tv_nsec) {
+ v_nsec = pps_tf[0].tv_nsec; /* 2 0 1 */
+ u_nsec = pps_tf[2].tv_nsec - pps_tf[1].tv_nsec;
+ } else {
+ v_nsec = pps_tf[2].tv_nsec; /* 0 2 1 */
+ u_nsec = pps_tf[0].tv_nsec - pps_tf[1].tv_nsec;
+ }
+ } else {
+ if (pps_tf[1].tv_nsec < pps_tf[2].tv_nsec) {
+ v_nsec = pps_tf[1].tv_nsec; /* 2 1 0 */
+ u_nsec = pps_tf[2].tv_nsec - pps_tf[0].tv_nsec;
+ } else if (pps_tf[2].tv_nsec < pps_tf[0].tv_nsec) {
+ v_nsec = pps_tf[0].tv_nsec; /* 1 0 2 */
+ u_nsec = pps_tf[1].tv_nsec - pps_tf[2].tv_nsec;
+ } else {
+ v_nsec = pps_tf[2].tv_nsec; /* 1 2 0 */
+ u_nsec = pps_tf[1].tv_nsec - pps_tf[0].tv_nsec;
+ }
+ }
+
+ /*
+ * Nominal jitter is due to PPS signal noise and interrupt
+ * latency. If it exceeds the popcorn threshold, the sample is
+ * discarded. otherwise, if so enabled, the time offset is
+ * updated. We can tolerate a modest loss of data here without
+ * much degrading time accuracy.
+ *
+ * The measurements being checked here were made with the system
+ * timecounter, so the popcorn threshold is not allowed to fall below
+ * the number of nanoseconds in two ticks of the timecounter. For a
+ * timecounter running faster than 1 GHz the lower bound is 2ns, just
+ * to avoid a nonsensical threshold of zero.
+ */
+ if (u_nsec > lmax(pps_jitter << PPS_POPCORN,
+ 2 * (NANOSECOND / (long)qmin(NANOSECOND, tc_getfrequency())))) {
+ time_status |= STA_PPSJITTER;
+ pps_jitcnt++;
+ } else if (time_status & STA_PPSTIME) {
+ time_monitor = -v_nsec;
+ L_LINT(time_offset, time_monitor);
+ }
+ pps_jitter += (u_nsec - pps_jitter) >> PPS_FAVG;
+ u_sec = pps_tf[0].tv_sec - pps_lastsec;
+ if (u_sec < (1 << pps_shift))
+ goto out;
+
+ /*
+ * At the end of the calibration interval the difference between
+ * the first and last counter values becomes the scaled
+ * frequency. It will later be divided by the length of the
+ * interval to determine the frequency update. If the frequency
+ * exceeds a sanity threshold, or if the actual calibration
+ * interval is not equal to the expected length, the data are
+ * discarded. We can tolerate a modest loss of data here without
+ * much degrading frequency accuracy.
+ */
+ pps_calcnt++;
+ v_nsec = -pps_fcount;
+ pps_lastsec = pps_tf[0].tv_sec;
+ pps_fcount = 0;
+ u_nsec = MAXFREQ << pps_shift;
+ if (v_nsec > u_nsec || v_nsec < -u_nsec || u_sec != (1 << pps_shift)) {
+ time_status |= STA_PPSERROR;
+ pps_errcnt++;
+ goto out;
+ }
+
+ /*
+ * Here the raw frequency offset and wander (stability) is
+ * calculated. If the wander is less than the wander threshold
+ * for four consecutive averaging intervals, the interval is
+ * doubled; if it is greater than the threshold for four
+ * consecutive intervals, the interval is halved. The scaled
+ * frequency offset is converted to frequency offset. The
+ * stability metric is calculated as the average of recent
+ * frequency changes, but is used only for performance
+ * monitoring.
+ */
+ L_LINT(ftemp, v_nsec);
+ L_RSHIFT(ftemp, pps_shift);
+ L_SUB(ftemp, pps_freq);
+ u_nsec = L_GINT(ftemp);
+ if (u_nsec > PPS_MAXWANDER) {
+ L_LINT(ftemp, PPS_MAXWANDER);
+ pps_intcnt--;
+ time_status |= STA_PPSWANDER;
+ pps_stbcnt++;
+ } else if (u_nsec < -PPS_MAXWANDER) {
+ L_LINT(ftemp, -PPS_MAXWANDER);
+ pps_intcnt--;
+ time_status |= STA_PPSWANDER;
+ pps_stbcnt++;
+ } else {
+ pps_intcnt++;
+ }
+ if (pps_intcnt >= 4) {
+ pps_intcnt = 4;
+ if (pps_shift < pps_shiftmax) {
+ pps_shift++;
+ pps_intcnt = 0;
+ }
+ } else if (pps_intcnt <= -4 || pps_shift > pps_shiftmax) {
+ pps_intcnt = -4;
+ if (pps_shift > PPS_FAVG) {
+ pps_shift--;
+ pps_intcnt = 0;
+ }
+ }
+ if (u_nsec < 0)
+ u_nsec = -u_nsec;
+ pps_stabil += (u_nsec * SCALE_PPM - pps_stabil) >> PPS_FAVG;
+
+ /*
+ * The PPS frequency is recalculated and clamped to the maximum
+ * MAXFREQ. If enabled, the system clock frequency is updated as
+ * well.
+ */
+ L_ADD(pps_freq, ftemp);
+ u_nsec = L_GINT(pps_freq);
+ if (u_nsec > MAXFREQ)
+ L_LINT(pps_freq, MAXFREQ);
+ else if (u_nsec < -MAXFREQ)
+ L_LINT(pps_freq, -MAXFREQ);
+ if (time_status & STA_PPSFREQ)
+ time_freq = pps_freq;
+
+out:
+ NTP_UNLOCK();
+}
+#endif /* PPS_SYNC */
+
+#ifndef _SYS_SYSPROTO_H_
+struct adjtime_args {
+ struct timeval *delta;
+ struct timeval *olddelta;
+};
+#endif
+/* ARGSUSED */
+int
+sys_adjtime(struct thread *td, struct adjtime_args *uap)
+{
+ struct timeval delta, olddelta, *deltap;
+ int error;
+
+ if (uap->delta) {
+ error = copyin(uap->delta, &delta, sizeof(delta));
+ if (error)
+ return (error);
+ deltap = δ
+ } else
+ deltap = NULL;
+ error = kern_adjtime(td, deltap, &olddelta);
+ if (uap->olddelta && error == 0)
+ error = copyout(&olddelta, uap->olddelta, sizeof(olddelta));
+ return (error);
+}
+
+int
+kern_adjtime(struct thread *td, struct timeval *delta, struct timeval *olddelta)
+{
+ struct timeval atv;
+ int64_t ltr, ltw;
+ int error;
+
+ if (delta != NULL) {
+ error = priv_check(td, PRIV_ADJTIME);
+ if (error != 0)
+ return (error);
+ ltw = (int64_t)delta->tv_sec * 1000000 + delta->tv_usec;
+ }
+ NTP_LOCK();
+ ltr = time_adjtime;
+ if (delta != NULL)
+ time_adjtime = ltw;
+ NTP_UNLOCK();
+ if (olddelta != NULL) {
+ atv.tv_sec = ltr / 1000000;
+ atv.tv_usec = ltr % 1000000;
+ if (atv.tv_usec < 0) {
+ atv.tv_usec += 1000000;
+ atv.tv_sec--;
+ }
+ *olddelta = atv;
+ }
+ return (0);
+}
+
+static struct callout resettodr_callout;
+static int resettodr_period = 1800;
+
+static void
+periodic_resettodr(void *arg __unused)
+{
+
+ /*
+ * Read of time_status is lock-less, which is fine since
+ * ntp_is_time_error() operates on the consistent read value.
+ */
+ if (!ntp_is_time_error(time_status))
+ resettodr();
+ if (resettodr_period > 0)
+ callout_schedule(&resettodr_callout, resettodr_period * hz);
+}
+
+static void
+shutdown_resettodr(void *arg __unused, int howto __unused)
+{
+
+ callout_drain(&resettodr_callout);
+ /* Another unlocked read of time_status */
+ if (resettodr_period > 0 && !ntp_is_time_error(time_status))
+ resettodr();
+}
+
+static int
+sysctl_resettodr_period(SYSCTL_HANDLER_ARGS)
+{
+ int error;
+
+ error = sysctl_handle_int(oidp, oidp->oid_arg1, oidp->oid_arg2, req);
+ if (error || !req->newptr)
+ return (error);
+ if (cold)
+ goto done;
+ if (resettodr_period == 0)
+ callout_stop(&resettodr_callout);
+ else
+ callout_reset(&resettodr_callout, resettodr_period * hz,
+ periodic_resettodr, NULL);
+done:
+ return (0);
+}
+
+SYSCTL_PROC(_machdep, OID_AUTO, rtc_save_period, CTLTYPE_INT | CTLFLAG_RWTUN |
+ CTLFLAG_MPSAFE, &resettodr_period, 1800, sysctl_resettodr_period, "I",
+ "Save system time to RTC with this period (in seconds)");
+
+static void
+start_periodic_resettodr(void *arg __unused)
+{
+
+ EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_resettodr, NULL,
+ SHUTDOWN_PRI_FIRST);
+ callout_init(&resettodr_callout, 1);
+ if (resettodr_period == 0)
+ return;
+ callout_reset(&resettodr_callout, resettodr_period * hz,
+ periodic_resettodr, NULL);
+}
+
+SYSINIT(periodic_resettodr, SI_SUB_LAST, SI_ORDER_MIDDLE,
+ start_periodic_resettodr, NULL);
More information about the vc
mailing list