/*
- * linux/kernel/time/ntp.c
- *
* NTP state machine interfaces and logic.
*
* This code was mainly moved from kernel/timer.c and kernel/time.c
* Please see those files for relevant copyright info and historical
* changelogs.
*/
-
-#include <linux/mm.h>
-#include <linux/time.h>
+#include <linux/capability.h>
+#include <linux/clocksource.h>
+#include <linux/workqueue.h>
+#include <linux/hrtimer.h>
+#include <linux/jiffies.h>
+#include <linux/math64.h>
#include <linux/timex.h>
+#include <linux/time.h>
+#include <linux/mm.h>
+#include <linux/module.h>
-#include <asm/div64.h>
-#include <asm/timex.h>
+#include "tick-internal.h"
/*
- * Timekeeping variables
+ * NTP timekeeping variables:
*/
-unsigned long tick_usec = TICK_USEC; /* USER_HZ period (usec) */
-unsigned long tick_nsec; /* ACTHZ period (nsec) */
-static u64 tick_length, tick_length_base;
-#define MAX_TICKADJ 500 /* microsecs */
-#define MAX_TICKADJ_SCALED (((u64)(MAX_TICKADJ * NSEC_PER_USEC) << \
- TICK_LENGTH_SHIFT) / HZ)
+DEFINE_SPINLOCK(ntp_lock);
+
+
+/* USER_HZ period (usecs): */
+unsigned long tick_usec = TICK_USEC;
+
+/* ACTHZ period (nsecs): */
+unsigned long tick_nsec;
+
+static u64 tick_length;
+static u64 tick_length_base;
+
+#define MAX_TICKADJ 500LL /* usecs */
+#define MAX_TICKADJ_SCALED \
+ (((MAX_TICKADJ * NSEC_PER_USEC) << NTP_SCALE_SHIFT) / NTP_INTERVAL_FREQ)
/*
* phase-lock loop variables
*/
-/* TIME_ERROR prevents overwriting the CMOS clock */
-int time_state = TIME_OK; /* clock synchronization status */
-int time_status = STA_UNSYNC; /* clock status bits */
-long time_offset; /* time adjustment (ns) */
-long time_constant = 2; /* pll time constant */
-long time_precision = 1; /* clock precision (us) */
-long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */
-long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */
-long time_freq; /* frequency offset (scaled ppm)*/
-long time_reftime; /* time at last adjustment (s) */
-long time_adjust;
+
+/*
+ * clock synchronization status
+ *
+ * (TIME_ERROR prevents overwriting the CMOS clock)
+ */
+static int time_state = TIME_OK;
+
+/* clock status bits: */
+static int time_status = STA_UNSYNC;
+
+/* TAI offset (secs): */
+static long time_tai;
+
+/* time adjustment (nsecs): */
+static s64 time_offset;
+
+/* pll time constant: */
+static long time_constant = 2;
+
+/* maximum error (usecs): */
+static long time_maxerror = NTP_PHASE_LIMIT;
+
+/* estimated error (usecs): */
+static long time_esterror = NTP_PHASE_LIMIT;
+
+/* frequency offset (scaled nsecs/secs): */
+static s64 time_freq;
+
+/* time at last adjustment (secs): */
+static long time_reftime;
+
+static long time_adjust;
+
+/* constant (boot-param configurable) NTP tick adjustment (upscaled) */
+static s64 ntp_tick_adj;
+
+#ifdef CONFIG_NTP_PPS
+
+/*
+ * The following variables are used when a pulse-per-second (PPS) signal
+ * is available. They establish the engineering parameters of the clock
+ * discipline loop when controlled by the PPS signal.
+ */
+#define PPS_VALID 10 /* PPS signal watchdog max (s) */
+#define PPS_POPCORN 4 /* popcorn spike threshold (shift) */
+#define PPS_INTMIN 2 /* min freq interval (s) (shift) */
+#define PPS_INTMAX 8 /* max freq interval (s) (shift) */
+#define PPS_INTCOUNT 4 /* number of consecutive good intervals to
+ increase pps_shift or consecutive bad
+ intervals to decrease it */
+#define PPS_MAXWANDER 100000 /* max PPS freq wander (ns/s) */
+
+static int pps_valid; /* signal watchdog counter */
+static long pps_tf[3]; /* phase median filter */
+static long pps_jitter; /* current jitter (ns) */
+static struct timespec pps_fbase; /* beginning of the last freq interval */
+static int pps_shift; /* current interval duration (s) (shift) */
+static int pps_intcnt; /* interval counter */
+static s64 pps_freq; /* frequency offset (scaled ns/s) */
+static long pps_stabil; /* current stability (scaled ns/s) */
+
+/*
+ * 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 */
+
+
+/* PPS kernel consumer compensates the whole phase error immediately.
+ * Otherwise, reduce the offset by a fixed factor times the time constant.
+ */
+static inline s64 ntp_offset_chunk(s64 offset)
+{
+ if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL)
+ return offset;
+ else
+ return shift_right(offset, SHIFT_PLL + time_constant);
+}
+
+static inline void pps_reset_freq_interval(void)
+{
+ /* the PPS calibration interval may end
+ surprisingly early */
+ pps_shift = PPS_INTMIN;
+ pps_intcnt = 0;
+}
/**
- * ntp_clear - Clears the NTP state variables
+ * pps_clear - Clears the PPS state variables
+ *
+ * Must be called while holding a write on the ntp_lock
+ */
+static inline void pps_clear(void)
+{
+ pps_reset_freq_interval();
+ pps_tf[0] = 0;
+ pps_tf[1] = 0;
+ pps_tf[2] = 0;
+ pps_fbase.tv_sec = pps_fbase.tv_nsec = 0;
+ pps_freq = 0;
+}
+
+/* Decrease pps_valid to indicate that another second has passed since
+ * the last PPS signal. When it reaches 0, indicate that PPS signal is
+ * missing.
*
- * Must be called while holding a write on the xtime_lock
+ * Must be called while holding a write on the ntp_lock
+ */
+static inline void pps_dec_valid(void)
+{
+ if (pps_valid > 0)
+ pps_valid--;
+ else {
+ time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
+ STA_PPSWANDER | STA_PPSERROR);
+ pps_clear();
+ }
+}
+
+static inline void pps_set_freq(s64 freq)
+{
+ pps_freq = freq;
+}
+
+static inline int is_error_status(int status)
+{
+ return (time_status & (STA_UNSYNC|STA_CLOCKERR))
+ /* PPS signal lost when either PPS time or
+ * PPS frequency synchronization requested
+ */
+ || ((time_status & (STA_PPSFREQ|STA_PPSTIME))
+ && !(time_status & STA_PPSSIGNAL))
+ /* PPS jitter exceeded when
+ * PPS time synchronization requested */
+ || ((time_status & (STA_PPSTIME|STA_PPSJITTER))
+ == (STA_PPSTIME|STA_PPSJITTER))
+ /* PPS wander exceeded or calibration error when
+ * PPS frequency synchronization requested
+ */
+ || ((time_status & STA_PPSFREQ)
+ && (time_status & (STA_PPSWANDER|STA_PPSERROR)));
+}
+
+static inline void pps_fill_timex(struct timex *txc)
+{
+ txc->ppsfreq = shift_right((pps_freq >> PPM_SCALE_INV_SHIFT) *
+ PPM_SCALE_INV, NTP_SCALE_SHIFT);
+ txc->jitter = pps_jitter;
+ if (!(time_status & STA_NANO))
+ txc->jitter /= NSEC_PER_USEC;
+ txc->shift = pps_shift;
+ txc->stabil = pps_stabil;
+ txc->jitcnt = pps_jitcnt;
+ txc->calcnt = pps_calcnt;
+ txc->errcnt = pps_errcnt;
+ txc->stbcnt = pps_stbcnt;
+}
+
+#else /* !CONFIG_NTP_PPS */
+
+static inline s64 ntp_offset_chunk(s64 offset)
+{
+ return shift_right(offset, SHIFT_PLL + time_constant);
+}
+
+static inline void pps_reset_freq_interval(void) {}
+static inline void pps_clear(void) {}
+static inline void pps_dec_valid(void) {}
+static inline void pps_set_freq(s64 freq) {}
+
+static inline int is_error_status(int status)
+{
+ return status & (STA_UNSYNC|STA_CLOCKERR);
+}
+
+static inline void pps_fill_timex(struct timex *txc)
+{
+ /* PPS is not implemented, so these are zero */
+ txc->ppsfreq = 0;
+ txc->jitter = 0;
+ txc->shift = 0;
+ txc->stabil = 0;
+ txc->jitcnt = 0;
+ txc->calcnt = 0;
+ txc->errcnt = 0;
+ txc->stbcnt = 0;
+}
+
+#endif /* CONFIG_NTP_PPS */
+
+
+/**
+ * ntp_synced - Returns 1 if the NTP status is not UNSYNC
+ *
+ */
+static inline int ntp_synced(void)
+{
+ return !(time_status & STA_UNSYNC);
+}
+
+
+/*
+ * NTP methods:
+ */
+
+/*
+ * Update (tick_length, tick_length_base, tick_nsec), based
+ * on (tick_usec, ntp_tick_adj, time_freq):
+ */
+static void ntp_update_frequency(void)
+{
+ u64 second_length;
+ u64 new_base;
+
+ second_length = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ)
+ << NTP_SCALE_SHIFT;
+
+ second_length += ntp_tick_adj;
+ second_length += time_freq;
+
+ tick_nsec = div_u64(second_length, HZ) >> NTP_SCALE_SHIFT;
+ new_base = div_u64(second_length, NTP_INTERVAL_FREQ);
+
+ /*
+ * Don't wait for the next second_overflow, apply
+ * the change to the tick length immediately:
+ */
+ tick_length += new_base - tick_length_base;
+ tick_length_base = new_base;
+}
+
+static inline s64 ntp_update_offset_fll(s64 offset64, long secs)
+{
+ time_status &= ~STA_MODE;
+
+ if (secs < MINSEC)
+ return 0;
+
+ if (!(time_status & STA_FLL) && (secs <= MAXSEC))
+ return 0;
+
+ time_status |= STA_MODE;
+
+ return div64_long(offset64 << (NTP_SCALE_SHIFT - SHIFT_FLL), secs);
+}
+
+static void ntp_update_offset(long offset)
+{
+ s64 freq_adj;
+ s64 offset64;
+ long secs;
+
+ if (!(time_status & STA_PLL))
+ return;
+
+ if (!(time_status & STA_NANO))
+ offset *= NSEC_PER_USEC;
+
+ /*
+ * Scale the phase adjustment and
+ * clamp to the operating range.
+ */
+ offset = min(offset, MAXPHASE);
+ offset = max(offset, -MAXPHASE);
+
+ /*
+ * Select how the frequency is to be controlled
+ * and in which mode (PLL or FLL).
+ */
+ secs = get_seconds() - time_reftime;
+ if (unlikely(time_status & STA_FREQHOLD))
+ secs = 0;
+
+ time_reftime = get_seconds();
+
+ offset64 = offset;
+ freq_adj = ntp_update_offset_fll(offset64, secs);
+
+ /*
+ * Clamp update interval to reduce PLL gain with low
+ * sampling rate (e.g. intermittent network connection)
+ * to avoid instability.
+ */
+ if (unlikely(secs > 1 << (SHIFT_PLL + 1 + time_constant)))
+ secs = 1 << (SHIFT_PLL + 1 + time_constant);
+
+ freq_adj += (offset64 * secs) <<
+ (NTP_SCALE_SHIFT - 2 * (SHIFT_PLL + 2 + time_constant));
+
+ freq_adj = min(freq_adj + time_freq, MAXFREQ_SCALED);
+
+ time_freq = max(freq_adj, -MAXFREQ_SCALED);
+
+ time_offset = div_s64(offset64 << NTP_SCALE_SHIFT, NTP_INTERVAL_FREQ);
+}
+
+/**
+ * ntp_clear - Clears the NTP state variables
*/
void ntp_clear(void)
{
- time_adjust = 0; /* stop active adjtime() */
- time_status |= STA_UNSYNC;
- time_maxerror = NTP_PHASE_LIMIT;
- time_esterror = NTP_PHASE_LIMIT;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ntp_lock, flags);
+
+ time_adjust = 0; /* stop active adjtime() */
+ time_status |= STA_UNSYNC;
+ time_maxerror = NTP_PHASE_LIMIT;
+ time_esterror = NTP_PHASE_LIMIT;
ntp_update_frequency();
- tick_length = tick_length_base;
- time_offset = 0;
+ tick_length = tick_length_base;
+ time_offset = 0;
+
+ /* Clear PPS state variables */
+ pps_clear();
+ spin_unlock_irqrestore(&ntp_lock, flags);
+
}
-#define CLOCK_TICK_OVERFLOW (LATCH * HZ - CLOCK_TICK_RATE)
-#define CLOCK_TICK_ADJUST (((s64)CLOCK_TICK_OVERFLOW * NSEC_PER_SEC) / (s64)CLOCK_TICK_RATE)
-void ntp_update_frequency(void)
+u64 ntp_tick_length(void)
{
- tick_length_base = (u64)(tick_usec * NSEC_PER_USEC * USER_HZ) << TICK_LENGTH_SHIFT;
- tick_length_base += (s64)CLOCK_TICK_ADJUST << TICK_LENGTH_SHIFT;
- tick_length_base += (s64)time_freq << (TICK_LENGTH_SHIFT - SHIFT_NSEC);
+ unsigned long flags;
+ s64 ret;
- do_div(tick_length_base, HZ);
-
- tick_nsec = tick_length_base >> TICK_LENGTH_SHIFT;
+ spin_lock_irqsave(&ntp_lock, flags);
+ ret = tick_length;
+ spin_unlock_irqrestore(&ntp_lock, flags);
+ return ret;
}
+
/*
* this routine handles the overflow of the microsecond field
*
* were provided by Dave Mills (Mills@UDEL.EDU) of NTP fame.
* They were originally developed for SUN and DEC kernels.
* All the kudos should go to Dave for this stuff.
+ *
+ * Also handles leap second processing, and returns leap offset
*/
-void second_overflow(void)
+int second_overflow(unsigned long secs)
{
- long time_adj;
+ s64 delta;
+ int leap = 0;
+ unsigned long flags;
- /* Bump the maxerror field */
- time_maxerror += MAXFREQ >> SHIFT_USEC;
- if (time_maxerror > NTP_PHASE_LIMIT) {
- time_maxerror = NTP_PHASE_LIMIT;
- time_status |= STA_UNSYNC;
- }
+ spin_lock_irqsave(&ntp_lock, flags);
/*
* 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.
+ * state, the system clock is set ahead one second.
*/
switch (time_state) {
case TIME_OK:
time_state = TIME_DEL;
break;
case TIME_INS:
- if (xtime.tv_sec % 86400 == 0) {
- xtime.tv_sec--;
- wall_to_monotonic.tv_sec++;
- /*
- * The timer interpolator will make time change
- * gradually instead of an immediate jump by one second
- */
- time_interpolator_update(-NSEC_PER_SEC);
+ if (secs % 86400 == 0) {
+ leap = -1;
time_state = TIME_OOP;
- clock_was_set();
- printk(KERN_NOTICE "Clock: inserting leap second "
- "23:59:60 UTC\n");
+ printk(KERN_NOTICE
+ "Clock: inserting leap second 23:59:60 UTC\n");
}
break;
case TIME_DEL:
- if ((xtime.tv_sec + 1) % 86400 == 0) {
- xtime.tv_sec++;
- wall_to_monotonic.tv_sec--;
- /*
- * Use of time interpolator for a gradual change of
- * time
- */
- time_interpolator_update(NSEC_PER_SEC);
+ if ((secs + 1) % 86400 == 0) {
+ leap = 1;
+ time_tai--;
time_state = TIME_WAIT;
- clock_was_set();
- printk(KERN_NOTICE "Clock: deleting leap second "
- "23:59:59 UTC\n");
+ printk(KERN_NOTICE
+ "Clock: deleting leap second 23:59:59 UTC\n");
}
break;
case TIME_OOP:
+ time_tai++;
time_state = TIME_WAIT;
break;
+
case TIME_WAIT:
if (!(time_status & (STA_INS | STA_DEL)))
- time_state = TIME_OK;
+ time_state = TIME_OK;
+ break;
+ }
+
+
+ /* Bump the maxerror field */
+ time_maxerror += MAXFREQ / NSEC_PER_USEC;
+ if (time_maxerror > NTP_PHASE_LIMIT) {
+ time_maxerror = NTP_PHASE_LIMIT;
+ time_status |= STA_UNSYNC;
+ }
+
+ /* Compute the phase adjustment for the next second */
+ tick_length = tick_length_base;
+
+ delta = ntp_offset_chunk(time_offset);
+ time_offset -= delta;
+ tick_length += delta;
+
+ /* Check PPS signal */
+ pps_dec_valid();
+
+ if (!time_adjust)
+ goto out;
+
+ if (time_adjust > MAX_TICKADJ) {
+ time_adjust -= MAX_TICKADJ;
+ tick_length += MAX_TICKADJ_SCALED;
+ goto out;
}
+ if (time_adjust < -MAX_TICKADJ) {
+ time_adjust += MAX_TICKADJ;
+ tick_length -= MAX_TICKADJ_SCALED;
+ goto out;
+ }
+
+ tick_length += (s64)(time_adjust * NSEC_PER_USEC / NTP_INTERVAL_FREQ)
+ << NTP_SCALE_SHIFT;
+ time_adjust = 0;
+
+
+
+out:
+ spin_unlock_irqrestore(&ntp_lock, flags);
+
+ return leap;
+}
+
+#ifdef CONFIG_GENERIC_CMOS_UPDATE
+
+static void sync_cmos_clock(struct work_struct *work);
+
+static DECLARE_DELAYED_WORK(sync_cmos_work, sync_cmos_clock);
+
+static void sync_cmos_clock(struct work_struct *work)
+{
+ struct timespec now, next;
+ int fail = 1;
+
/*
- * 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 we have an externally synchronized Linux clock, then update
+ * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
+ * called as close as possible to 500 ms before the new second starts.
+ * This code is run on a timer. If the clock is set, that timer
+ * may not expire at the correct time. Thus, we adjust...
*/
- tick_length = tick_length_base;
- time_adj = time_offset;
- if (!(time_status & STA_FLL))
- time_adj = shift_right(time_adj, SHIFT_KG + time_constant);
- time_adj = min(time_adj, -((MAXPHASE / HZ) << SHIFT_UPDATE) / MINSEC);
- time_adj = max(time_adj, ((MAXPHASE / HZ) << SHIFT_UPDATE) / MINSEC);
- time_offset -= time_adj;
- tick_length += (s64)time_adj << (TICK_LENGTH_SHIFT - SHIFT_UPDATE);
-
- if (unlikely(time_adjust)) {
- if (time_adjust > MAX_TICKADJ) {
- time_adjust -= MAX_TICKADJ;
- tick_length += MAX_TICKADJ_SCALED;
- } else if (time_adjust < -MAX_TICKADJ) {
- time_adjust += MAX_TICKADJ;
- tick_length -= MAX_TICKADJ_SCALED;
- } else {
- time_adjust = 0;
- tick_length += (s64)(time_adjust * NSEC_PER_USEC /
- HZ) << TICK_LENGTH_SHIFT;
- }
+ if (!ntp_synced()) {
+ /*
+ * Not synced, exit, do not restart a timer (if one is
+ * running, let it run out).
+ */
+ return;
+ }
+
+ getnstimeofday(&now);
+ if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2)
+ fail = update_persistent_clock(now);
+
+ next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec - (TICK_NSEC / 2);
+ if (next.tv_nsec <= 0)
+ next.tv_nsec += NSEC_PER_SEC;
+
+ if (!fail)
+ next.tv_sec = 659;
+ else
+ next.tv_sec = 0;
+
+ if (next.tv_nsec >= NSEC_PER_SEC) {
+ next.tv_sec++;
+ next.tv_nsec -= NSEC_PER_SEC;
}
+ schedule_delayed_work(&sync_cmos_work, timespec_to_jiffies(&next));
}
+static void notify_cmos_timer(void)
+{
+ schedule_delayed_work(&sync_cmos_work, 0);
+}
+
+#else
+static inline void notify_cmos_timer(void) { }
+#endif
+
+
/*
- * Return how long ticks are at the moment, that is, how much time
- * update_wall_time_one_tick will add to xtime next time we call it
- * (assuming no calls to do_adjtimex in the meantime).
- * The return value is in fixed-point nanoseconds shifted by the
- * specified number of bits to the right of the binary point.
- * This function has no side-effects.
+ * Propagate a new txc->status value into the NTP state:
*/
-u64 current_tick_length(void)
+static inline void process_adj_status(struct timex *txc, struct timespec *ts)
{
- return tick_length;
-}
+ if ((time_status & STA_PLL) && !(txc->status & STA_PLL)) {
+ time_state = TIME_OK;
+ time_status = STA_UNSYNC;
+ /* restart PPS frequency calibration */
+ pps_reset_freq_interval();
+ }
+
+ /*
+ * If we turn on PLL adjustments then reset the
+ * reference time to current time.
+ */
+ if (!(time_status & STA_PLL) && (txc->status & STA_PLL))
+ time_reftime = get_seconds();
+ /* only set allowed bits */
+ time_status &= STA_RONLY;
+ time_status |= txc->status & ~STA_RONLY;
-void __attribute__ ((weak)) notify_arch_cmos_timer(void)
+}
+/*
+ * Called with the xtime lock held, so we can access and modify
+ * all the global NTP state:
+ */
+static inline void process_adjtimex_modes(struct timex *txc, struct timespec *ts)
{
- return;
+ if (txc->modes & ADJ_STATUS)
+ process_adj_status(txc, ts);
+
+ if (txc->modes & ADJ_NANO)
+ time_status |= STA_NANO;
+
+ if (txc->modes & ADJ_MICRO)
+ time_status &= ~STA_NANO;
+
+ if (txc->modes & ADJ_FREQUENCY) {
+ time_freq = txc->freq * PPM_SCALE;
+ time_freq = min(time_freq, MAXFREQ_SCALED);
+ time_freq = max(time_freq, -MAXFREQ_SCALED);
+ /* update pps_freq */
+ pps_set_freq(time_freq);
+ }
+
+ if (txc->modes & ADJ_MAXERROR)
+ time_maxerror = txc->maxerror;
+
+ if (txc->modes & ADJ_ESTERROR)
+ time_esterror = txc->esterror;
+
+ if (txc->modes & ADJ_TIMECONST) {
+ time_constant = txc->constant;
+ if (!(time_status & STA_NANO))
+ time_constant += 4;
+ time_constant = min(time_constant, (long)MAXTC);
+ time_constant = max(time_constant, 0l);
+ }
+
+ if (txc->modes & ADJ_TAI && txc->constant > 0)
+ time_tai = txc->constant;
+
+ if (txc->modes & ADJ_OFFSET)
+ ntp_update_offset(txc->offset);
+
+ if (txc->modes & ADJ_TICK)
+ tick_usec = txc->tick;
+
+ if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET))
+ ntp_update_frequency();
}
-/* adjtimex mainly allows reading (and writing, if superuser) of
+/*
+ * adjtimex mainly allows reading (and writing, if superuser) of
* kernel time-keeping variables. used by xntpd.
*/
int do_adjtimex(struct timex *txc)
{
- long ltemp, mtemp, save_adjust;
- s64 freq_adj;
+ struct timespec ts;
int result;
- /* In order to modify anything, you gotta be super-user! */
- if (txc->modes && !capable(CAP_SYS_TIME))
- return -EPERM;
-
- /* Now we validate the data before disabling interrupts */
-
- if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
- /* singleshot must not be used with any other mode bits */
- if (txc->modes != ADJ_OFFSET_SINGLESHOT)
- return -EINVAL;
-
- if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
- /* adjustment Offset limited to +- .512 seconds */
- if (txc->offset <= - MAXPHASE || txc->offset >= MAXPHASE )
+ /* Validate the data before disabling interrupts */
+ if (txc->modes & ADJ_ADJTIME) {
+ /* singleshot must not be used with any other mode bits */
+ if (!(txc->modes & ADJ_OFFSET_SINGLESHOT))
return -EINVAL;
-
- /* if the quartz is off by more than 10% something is VERY wrong ! */
- if (txc->modes & ADJ_TICK)
- if (txc->tick < 900000/USER_HZ ||
- txc->tick > 1100000/USER_HZ)
+ if (!(txc->modes & ADJ_OFFSET_READONLY) &&
+ !capable(CAP_SYS_TIME))
+ return -EPERM;
+ } else {
+ /* In order to modify anything, you gotta be super-user! */
+ if (txc->modes && !capable(CAP_SYS_TIME))
+ return -EPERM;
+
+ /*
+ * if the quartz is off by more than 10% then
+ * something is VERY wrong!
+ */
+ if (txc->modes & ADJ_TICK &&
+ (txc->tick < 900000/USER_HZ ||
+ txc->tick > 1100000/USER_HZ))
return -EINVAL;
+ }
- write_seqlock_irq(&xtime_lock);
- result = time_state; /* mostly `TIME_OK' */
+ if (txc->modes & ADJ_SETOFFSET) {
+ struct timespec delta;
+ delta.tv_sec = txc->time.tv_sec;
+ delta.tv_nsec = txc->time.tv_usec;
+ if (!capable(CAP_SYS_TIME))
+ return -EPERM;
+ if (!(txc->modes & ADJ_NANO))
+ delta.tv_nsec *= 1000;
+ result = timekeeping_inject_offset(&delta);
+ if (result)
+ return result;
+ }
- /* Save for later - semantics of adjtime is to return old value */
- save_adjust = time_adjust;
+ getnstimeofday(&ts);
-#if 0 /* STA_CLOCKERR is never set yet */
- time_status &= ~STA_CLOCKERR; /* reset STA_CLOCKERR */
-#endif
- /* If there are input parameters, then process them */
- if (txc->modes)
- {
- if (txc->modes & ADJ_STATUS) /* only set allowed bits */
- time_status = (txc->status & ~STA_RONLY) |
- (time_status & STA_RONLY);
-
- if (txc->modes & ADJ_FREQUENCY) { /* p. 22 */
- if (txc->freq > MAXFREQ || txc->freq < -MAXFREQ) {
- result = -EINVAL;
- goto leave;
- }
- time_freq = ((s64)txc->freq * NSEC_PER_USEC) >> (SHIFT_USEC - SHIFT_NSEC);
- }
+ spin_lock_irq(&ntp_lock);
- if (txc->modes & ADJ_MAXERROR) {
- if (txc->maxerror < 0 || txc->maxerror >= NTP_PHASE_LIMIT) {
- result = -EINVAL;
- goto leave;
- }
- time_maxerror = txc->maxerror;
- }
+ if (txc->modes & ADJ_ADJTIME) {
+ long save_adjust = time_adjust;
- if (txc->modes & ADJ_ESTERROR) {
- if (txc->esterror < 0 || txc->esterror >= NTP_PHASE_LIMIT) {
- result = -EINVAL;
- goto leave;
+ if (!(txc->modes & ADJ_OFFSET_READONLY)) {
+ /* adjtime() is independent from ntp_adjtime() */
+ time_adjust = txc->offset;
+ ntp_update_frequency();
}
- time_esterror = txc->esterror;
- }
+ txc->offset = save_adjust;
+ } else {
- if (txc->modes & ADJ_TIMECONST) { /* p. 24 */
- if (txc->constant < 0) { /* NTP v4 uses values > 6 */
- result = -EINVAL;
- goto leave;
- }
- time_constant = txc->constant;
- }
+ /* If there are input parameters, then process them: */
+ if (txc->modes)
+ process_adjtimex_modes(txc, &ts);
- if (txc->modes & ADJ_OFFSET) { /* values checked earlier */
- if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
- /* adjtime() is independent from ntp_adjtime() */
- time_adjust = txc->offset;
- }
- else if (time_status & STA_PLL) {
- ltemp = txc->offset * NSEC_PER_USEC;
-
- /*
- * Scale the phase adjustment and
- * clamp to the operating range.
- */
- time_offset = min(ltemp, MAXPHASE * NSEC_PER_USEC);
- time_offset = max(time_offset, -MAXPHASE * NSEC_PER_USEC);
-
- /*
- * 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 = xtime.tv_sec;
- mtemp = xtime.tv_sec - time_reftime;
- time_reftime = xtime.tv_sec;
- freq_adj = 0;
- if (time_status & STA_FLL) {
- if (mtemp >= MINSEC) {
- freq_adj = (s64)time_offset << (SHIFT_NSEC - SHIFT_KH);
- if (time_offset < 0) {
- freq_adj = -freq_adj;
- do_div(freq_adj, mtemp);
- freq_adj = -freq_adj;
- } else
- do_div(freq_adj, mtemp);
- } else /* calibration interval too short (p. 12) */
- result = TIME_ERROR;
- } else { /* PLL mode */
- if (mtemp < MAXSEC) {
- freq_adj = (s64)ltemp * mtemp;
- freq_adj = shift_right(freq_adj,(time_constant +
- time_constant +
- SHIFT_KF - SHIFT_NSEC));
- } else /* calibration interval too long (p. 12) */
- result = TIME_ERROR;
- }
- freq_adj += time_freq;
- freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
- time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);
- time_offset = (time_offset / HZ) << SHIFT_UPDATE;
- } /* STA_PLL */
- } /* txc->modes & ADJ_OFFSET */
- if (txc->modes & ADJ_TICK)
- tick_usec = txc->tick;
+ txc->offset = shift_right(time_offset * NTP_INTERVAL_FREQ,
+ NTP_SCALE_SHIFT);
+ if (!(time_status & STA_NANO))
+ txc->offset /= NSEC_PER_USEC;
+ }
- if (txc->modes & (ADJ_TICK|ADJ_FREQUENCY|ADJ_OFFSET))
- ntp_update_frequency();
- } /* txc->modes */
-leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0)
+ result = time_state; /* mostly `TIME_OK' */
+ /* check for errors */
+ if (is_error_status(time_status))
result = TIME_ERROR;
- if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
- txc->offset = save_adjust;
- else
- txc->offset = shift_right(time_offset, SHIFT_UPDATE) * HZ / 1000;
- txc->freq = (time_freq / NSEC_PER_USEC) << (SHIFT_USEC - SHIFT_NSEC);
+ txc->freq = shift_right((time_freq >> PPM_SCALE_INV_SHIFT) *
+ PPM_SCALE_INV, NTP_SCALE_SHIFT);
txc->maxerror = time_maxerror;
txc->esterror = time_esterror;
txc->status = time_status;
txc->constant = time_constant;
- txc->precision = time_precision;
- txc->tolerance = MAXFREQ;
+ txc->precision = 1;
+ txc->tolerance = MAXFREQ_SCALED / PPM_SCALE;
txc->tick = tick_usec;
+ txc->tai = time_tai;
- /* PPS is not implemented, so these are zero */
- txc->ppsfreq = 0;
- txc->jitter = 0;
- txc->shift = 0;
- txc->stabil = 0;
- txc->jitcnt = 0;
- txc->calcnt = 0;
- txc->errcnt = 0;
- txc->stbcnt = 0;
- write_sequnlock_irq(&xtime_lock);
- do_gettimeofday(&txc->time);
- notify_arch_cmos_timer();
- return(result);
+ /* fill PPS status fields */
+ pps_fill_timex(txc);
+
+ spin_unlock_irq(&ntp_lock);
+
+ txc->time.tv_sec = ts.tv_sec;
+ txc->time.tv_usec = ts.tv_nsec;
+ if (!(time_status & STA_NANO))
+ txc->time.tv_usec /= NSEC_PER_USEC;
+
+ notify_cmos_timer();
+
+ return result;
+}
+
+#ifdef CONFIG_NTP_PPS
+
+/* actually struct pps_normtime is good old struct timespec, but it is
+ * semantically different (and it is the reason why it was invented):
+ * pps_normtime.nsec has a range of ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ]
+ * while timespec.tv_nsec has a range of [0, NSEC_PER_SEC) */
+struct pps_normtime {
+ __kernel_time_t sec; /* seconds */
+ long nsec; /* nanoseconds */
+};
+
+/* normalize the timestamp so that nsec is in the
+ ( -NSEC_PER_SEC / 2, NSEC_PER_SEC / 2 ] interval */
+static inline struct pps_normtime pps_normalize_ts(struct timespec ts)
+{
+ struct pps_normtime norm = {
+ .sec = ts.tv_sec,
+ .nsec = ts.tv_nsec
+ };
+
+ if (norm.nsec > (NSEC_PER_SEC >> 1)) {
+ norm.nsec -= NSEC_PER_SEC;
+ norm.sec++;
+ }
+
+ return norm;
+}
+
+/* get current phase correction and jitter */
+static inline long pps_phase_filter_get(long *jitter)
+{
+ *jitter = pps_tf[0] - pps_tf[1];
+ if (*jitter < 0)
+ *jitter = -*jitter;
+
+ /* TODO: test various filters */
+ return pps_tf[0];
+}
+
+/* add the sample to the phase filter */
+static inline void pps_phase_filter_add(long err)
+{
+ pps_tf[2] = pps_tf[1];
+ pps_tf[1] = pps_tf[0];
+ pps_tf[0] = err;
+}
+
+/* decrease frequency calibration interval length.
+ * It is halved after four consecutive unstable intervals.
+ */
+static inline void pps_dec_freq_interval(void)
+{
+ if (--pps_intcnt <= -PPS_INTCOUNT) {
+ pps_intcnt = -PPS_INTCOUNT;
+ if (pps_shift > PPS_INTMIN) {
+ pps_shift--;
+ pps_intcnt = 0;
+ }
+ }
+}
+
+/* increase frequency calibration interval length.
+ * It is doubled after four consecutive stable intervals.
+ */
+static inline void pps_inc_freq_interval(void)
+{
+ if (++pps_intcnt >= PPS_INTCOUNT) {
+ pps_intcnt = PPS_INTCOUNT;
+ if (pps_shift < PPS_INTMAX) {
+ pps_shift++;
+ pps_intcnt = 0;
+ }
+ }
+}
+
+/* update clock frequency based on MONOTONIC_RAW clock PPS signal
+ * timestamps
+ *
+ * At the end of the calibration interval the difference between the
+ * first and last MONOTONIC_RAW clock timestamps divided by the length
+ * of the interval becomes the frequency update. If the interval was
+ * too long, the data are discarded.
+ * Returns the difference between old and new frequency values.
+ */
+static long hardpps_update_freq(struct pps_normtime freq_norm)
+{
+ long delta, delta_mod;
+ s64 ftemp;
+
+ /* check if the frequency interval was too long */
+ if (freq_norm.sec > (2 << pps_shift)) {
+ time_status |= STA_PPSERROR;
+ pps_errcnt++;
+ pps_dec_freq_interval();
+ pr_err("hardpps: PPSERROR: interval too long - %ld s\n",
+ freq_norm.sec);
+ return 0;
+ }
+
+ /* here the raw frequency offset and wander (stability) is
+ * calculated. If the wander is less than the wander threshold
+ * the interval is increased; otherwise it is decreased.
+ */
+ ftemp = div_s64(((s64)(-freq_norm.nsec)) << NTP_SCALE_SHIFT,
+ freq_norm.sec);
+ delta = shift_right(ftemp - pps_freq, NTP_SCALE_SHIFT);
+ pps_freq = ftemp;
+ if (delta > PPS_MAXWANDER || delta < -PPS_MAXWANDER) {
+ pr_warning("hardpps: PPSWANDER: change=%ld\n", delta);
+ time_status |= STA_PPSWANDER;
+ pps_stbcnt++;
+ pps_dec_freq_interval();
+ } else { /* good sample */
+ pps_inc_freq_interval();
+ }
+
+ /* the stability metric is calculated as the average of recent
+ * frequency changes, but is used only for performance
+ * monitoring
+ */
+ delta_mod = delta;
+ if (delta_mod < 0)
+ delta_mod = -delta_mod;
+ pps_stabil += (div_s64(((s64)delta_mod) <<
+ (NTP_SCALE_SHIFT - SHIFT_USEC),
+ NSEC_PER_USEC) - pps_stabil) >> PPS_INTMIN;
+
+ /* if enabled, the system clock frequency is updated */
+ if ((time_status & STA_PPSFREQ) != 0 &&
+ (time_status & STA_FREQHOLD) == 0) {
+ time_freq = pps_freq;
+ ntp_update_frequency();
+ }
+
+ return delta;
+}
+
+/* correct REALTIME clock phase error against PPS signal */
+static void hardpps_update_phase(long error)
+{
+ long correction = -error;
+ long jitter;
+
+ /* add the sample to the median filter */
+ pps_phase_filter_add(correction);
+ correction = pps_phase_filter_get(&jitter);
+
+ /* Nominal jitter is due to PPS signal noise. If it exceeds the
+ * threshold, the sample is discarded; otherwise, if so enabled,
+ * the time offset is updated.
+ */
+ if (jitter > (pps_jitter << PPS_POPCORN)) {
+ pr_warning("hardpps: PPSJITTER: jitter=%ld, limit=%ld\n",
+ jitter, (pps_jitter << PPS_POPCORN));
+ time_status |= STA_PPSJITTER;
+ pps_jitcnt++;
+ } else if (time_status & STA_PPSTIME) {
+ /* correct the time using the phase offset */
+ time_offset = div_s64(((s64)correction) << NTP_SCALE_SHIFT,
+ NTP_INTERVAL_FREQ);
+ /* cancel running adjtime() */
+ time_adjust = 0;
+ }
+ /* update jitter */
+ pps_jitter += (jitter - pps_jitter) >> PPS_INTMIN;
+}
+
+/*
+ * hardpps() - discipline CPU clock oscillator to external PPS signal
+ *
+ * This routine is called at each PPS signal arrival in order to
+ * discipline the CPU clock oscillator to the PPS signal. It takes two
+ * parameters: REALTIME and MONOTONIC_RAW clock timestamps. The former
+ * is used to correct clock phase error and the latter is used to
+ * correct the frequency.
+ *
+ * This code is based on David Mills's reference nanokernel
+ * implementation. It was mostly rewritten but keeps the same idea.
+ */
+void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts)
+{
+ struct pps_normtime pts_norm, freq_norm;
+ unsigned long flags;
+
+ pts_norm = pps_normalize_ts(*phase_ts);
+
+ spin_lock_irqsave(&ntp_lock, flags);
+
+ /* clear the error bits, they will be set again if needed */
+ time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
+
+ /* indicate signal presence */
+ time_status |= STA_PPSSIGNAL;
+ pps_valid = PPS_VALID;
+
+ /* when called for the first time,
+ * just start the frequency interval */
+ if (unlikely(pps_fbase.tv_sec == 0)) {
+ pps_fbase = *raw_ts;
+ spin_unlock_irqrestore(&ntp_lock, flags);
+ return;
+ }
+
+ /* ok, now we have a base for frequency calculation */
+ freq_norm = pps_normalize_ts(timespec_sub(*raw_ts, pps_fbase));
+
+ /* check that the signal is in the range
+ * [1s - MAXFREQ us, 1s + MAXFREQ us], otherwise reject it */
+ if ((freq_norm.sec == 0) ||
+ (freq_norm.nsec > MAXFREQ * freq_norm.sec) ||
+ (freq_norm.nsec < -MAXFREQ * freq_norm.sec)) {
+ time_status |= STA_PPSJITTER;
+ /* restart the frequency calibration interval */
+ pps_fbase = *raw_ts;
+ spin_unlock_irqrestore(&ntp_lock, flags);
+ pr_err("hardpps: PPSJITTER: bad pulse\n");
+ return;
+ }
+
+ /* signal is ok */
+
+ /* check if the current frequency interval is finished */
+ if (freq_norm.sec >= (1 << pps_shift)) {
+ pps_calcnt++;
+ /* restart the frequency calibration interval */
+ pps_fbase = *raw_ts;
+ hardpps_update_freq(freq_norm);
+ }
+
+ hardpps_update_phase(pts_norm.nsec);
+
+ spin_unlock_irqrestore(&ntp_lock, flags);
+}
+EXPORT_SYMBOL(hardpps);
+
+#endif /* CONFIG_NTP_PPS */
+
+static int __init ntp_tick_adj_setup(char *str)
+{
+ ntp_tick_adj = simple_strtol(str, NULL, 0);
+ ntp_tick_adj <<= NTP_SCALE_SHIFT;
+
+ return 1;
+}
+
+__setup("ntp_tick_adj=", ntp_tick_adj_setup);
+
+void __init ntp_init(void)
+{
+ ntp_clear();
}
Code Review / linux-2.6.git / blobdiff