--- /dev/null
+/*
+ * 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/timex.h>
+
+#include <asm/div64.h>
+#include <asm/timex.h>
+
+/*
+ * 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)
+
+/*
+ * phase-lock loop variables
+ */
+/* TIME_ERROR prevents overwriting the CMOS clock */
+static int time_state = TIME_OK; /* clock synchronization status */
+int time_status = STA_UNSYNC; /* clock status bits */
+static long time_offset; /* time adjustment (ns) */
+static long time_constant = 2; /* pll time constant */
+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)*/
+static long time_reftime; /* time at last adjustment (s) */
+long time_adjust;
+
+#define CLOCK_TICK_OVERFLOW (LATCH * HZ - CLOCK_TICK_RATE)
+#define CLOCK_TICK_ADJUST (((s64)CLOCK_TICK_OVERFLOW * NSEC_PER_SEC) / \
+ (s64)CLOCK_TICK_RATE)
+
+static void ntp_update_frequency(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);
+
+ do_div(tick_length_base, HZ);
+
+ tick_nsec = tick_length_base >> TICK_LENGTH_SHIFT;
+}
+
+/**
+ * ntp_clear - Clears the NTP state variables
+ *
+ * Must be called while holding a write on the xtime_lock
+ */
+void ntp_clear(void)
+{
+ 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;
+}
+
+/*
+ * this routine handles the overflow of the microsecond field
+ *
+ * The tricky bits of code to handle the accurate clock support
+ * 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.
+ */
+void second_overflow(void)
+{
+ long time_adj;
+
+ /* Bump the maxerror field */
+ time_maxerror += MAXFREQ >> SHIFT_USEC;
+ if (time_maxerror > NTP_PHASE_LIMIT) {
+ time_maxerror = NTP_PHASE_LIMIT;
+ time_status |= STA_UNSYNC;
+ }
+
+ /*
+ * 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.
+ */
+ switch (time_state) {
+ case TIME_OK:
+ if (time_status & STA_INS)
+ time_state = TIME_INS;
+ else if (time_status & STA_DEL)
+ 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);
+ time_state = TIME_OOP;
+ clock_was_set();
+ 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);
+ time_state = TIME_WAIT;
+ clock_was_set();
+ printk(KERN_NOTICE "Clock: deleting leap second "
+ "23:59:59 UTC\n");
+ }
+ break;
+ case TIME_OOP:
+ time_state = TIME_WAIT;
+ break;
+ case TIME_WAIT:
+ if (!(time_status & (STA_INS | STA_DEL)))
+ time_state = TIME_OK;
+ }
+
+ /*
+ * Compute the phase adjustment for the next second. The offset is
+ * reduced by a fixed factor times the time constant.
+ */
+ tick_length = tick_length_base;
+ time_adj = shift_right(time_offset, SHIFT_PLL + time_constant);
+ 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 {
+ tick_length += (s64)(time_adjust * NSEC_PER_USEC /
+ HZ) << TICK_LENGTH_SHIFT;
+ time_adjust = 0;
+ }
+ }
+}
+
+/*
+ * 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.
+ */
+u64 current_tick_length(void)
+{
+ return tick_length;
+}
+
+
+void __attribute__ ((weak)) notify_arch_cmos_timer(void)
+{
+ return;
+}
+
+/* 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, temp64;
+ 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 )
+ 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)
+ return -EINVAL;
+
+ write_seqlock_irq(&xtime_lock);
+ result = time_state; /* mostly `TIME_OK' */
+
+ /* Save for later - semantics of adjtime is to return old value */
+ save_adjust = time_adjust;
+
+#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);
+ }
+
+ 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_ESTERROR) {
+ if (txc->esterror < 0 || txc->esterror >= NTP_PHASE_LIMIT) {
+ result = -EINVAL;
+ goto leave;
+ }
+ time_esterror = txc->esterror;
+ }
+
+ if (txc->modes & ADJ_TIMECONST) { /* p. 24 */
+ if (txc->constant < 0) { /* NTP v4 uses values > 6 */
+ result = -EINVAL;
+ goto leave;
+ }
+ time_constant = min(txc->constant + 4, (long)MAXTC);
+ }
+
+ 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 = (s64)time_offset * mtemp;
+ freq_adj = shift_right(freq_adj, time_constant * 2 +
+ (SHIFT_PLL + 2) * 2 - SHIFT_NSEC);
+ if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) {
+ temp64 = (s64)time_offset << (SHIFT_NSEC - SHIFT_FLL);
+ if (time_offset < 0) {
+ temp64 = -temp64;
+ do_div(temp64, mtemp);
+ freq_adj -= temp64;
+ } else {
+ do_div(temp64, mtemp);
+ freq_adj += temp64;
+ }
+ }
+ 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;
+
+ 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_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->maxerror = time_maxerror;
+ txc->esterror = time_esterror;
+ txc->status = time_status;
+ txc->constant = time_constant;
+ txc->precision = 1;
+ txc->tolerance = MAXFREQ;
+ txc->tick = tick_usec;
+
+ /* 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);
+}
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