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authorjohn stultz <johnstul@us.ibm.com>2006-09-30 23:28:22 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-01 00:39:26 -0700
commit4c7ee8de956fc250fe31e2fa91f6da980fabe317 (patch)
treee2d7c207a7ca9f785c256513686f6d7f7234ef93 /kernel/time/ntp.c
parentc902e0a0102f1095eec4b3511c13c84ca2bc4577 (diff)
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[PATCH] NTP: Move all the NTP related code to ntp.c
Move all the NTP related code to ntp.c [akpm@osdl.org: cleanups, build fix] Signed-off-by: John Stultz <johnstul@us.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Roman Zippel <zippel@linux-m68k.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/time/ntp.c')
-rw-r--r--kernel/time/ntp.c389
1 files changed, 389 insertions, 0 deletions
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
new file mode 100644
index 00000000000..8ccce15b4b2
--- /dev/null
+++ b/kernel/time/ntp.c
@@ -0,0 +1,389 @@
+/*
+ * 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>
+
+/* Don't completely fail for HZ > 500. */
+int tickadj = 500/HZ ? : 1; /* microsecs */
+
+/*
+ * 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 (us) */
+long time_constant = 2; /* pll time constant */
+long time_tolerance = MAXFREQ; /* frequency tolerance (ppm) */
+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 = (((NSEC_PER_SEC + HZ/2) % HZ - HZ/2) << SHIFT_USEC) / NSEC_PER_USEC;
+ /* frequency offset (scaled ppm)*/
+static long time_adj; /* tick adjust (scaled 1 / HZ) */
+long time_reftime; /* time at last adjustment (s) */
+long time_adjust;
+long time_next_adjust;
+
+/*
+ * 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 ltemp;
+
+ /* Bump the maxerror field */
+ time_maxerror += time_tolerance >> 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. 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.
+ */
+ ltemp = time_offset;
+ if (!(time_status & STA_FLL))
+ ltemp = shift_right(ltemp, SHIFT_KG + time_constant);
+ ltemp = min(ltemp, (MAXPHASE / MINSEC) << SHIFT_UPDATE);
+ ltemp = max(ltemp, -(MAXPHASE / MINSEC) << SHIFT_UPDATE);
+ time_offset -= ltemp;
+ time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ - SHIFT_UPDATE);
+
+ /*
+ * Compute the frequency estimate and additional phase adjustment due
+ * to frequency error for the next second.
+ */
+ ltemp = time_freq;
+ time_adj += shift_right(ltemp,(SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE));
+
+#if HZ == 100
+ /*
+ * Compensate for (HZ==100) != (1 << SHIFT_HZ). Add 25% and 3.125% to
+ * get 128.125; => only 0.125% error (p. 14)
+ */
+ time_adj += shift_right(time_adj, 2) + shift_right(time_adj, 5);
+#endif
+#if HZ == 250
+ /*
+ * Compensate for (HZ==250) != (1 << SHIFT_HZ). Add 1.5625% and
+ * 0.78125% to get 255.85938; => only 0.05% error (p. 14)
+ */
+ time_adj += shift_right(time_adj, 6) + shift_right(time_adj, 7);
+#endif
+#if HZ == 1000
+ /*
+ * Compensate for (HZ==1000) != (1 << SHIFT_HZ). Add 1.5625% and
+ * 0.78125% to get 1023.4375; => only 0.05% error (p. 14)
+ */
+ time_adj += shift_right(time_adj, 6) + shift_right(time_adj, 7);
+#endif
+}
+
+/*
+ * Returns how many microseconds we need to add to xtime this tick
+ * in doing an adjustment requested with adjtime.
+ */
+static long adjtime_adjustment(void)
+{
+ long time_adjust_step;
+
+ time_adjust_step = time_adjust;
+ if (time_adjust_step) {
+ /*
+ * We are doing an adjtime thing. Prepare time_adjust_step to
+ * be within bounds. Note that a positive time_adjust means we
+ * want the clock to run faster.
+ *
+ * Limit the amount of the step to be in the range
+ * -tickadj .. +tickadj
+ */
+ time_adjust_step = min(time_adjust_step, (long)tickadj);
+ time_adjust_step = max(time_adjust_step, (long)-tickadj);
+ }
+ return time_adjust_step;
+}
+
+/* in the NTP reference this is called "hardclock()" */
+void update_ntp_one_tick(void)
+{
+ long time_adjust_step;
+
+ time_adjust_step = adjtime_adjustment();
+ if (time_adjust_step)
+ /* Reduce by this step the amount of time left */
+ time_adjust -= time_adjust_step;
+
+ /* Changes by adjtime() do not take effect till next tick. */
+ if (time_next_adjust != 0) {
+ time_adjust = time_next_adjust;
+ time_next_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)
+{
+ long delta_nsec;
+ u64 ret;
+
+ /* calculate the finest interval NTP will allow.
+ * ie: nanosecond value shifted by (SHIFT_SCALE - 10)
+ */
+ delta_nsec = tick_nsec + adjtime_adjustment() * 1000;
+ ret = (u64)delta_nsec << TICK_LENGTH_SHIFT;
+ ret += (s64)time_adj << (TICK_LENGTH_SHIFT - (SHIFT_SCALE - 10));
+
+ return ret;
+}
+
+
+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;
+ 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_next_adjust ? time_next_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 = txc->freq;
+ }
+
+ 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 = txc->constant;
+ }
+
+ if (txc->modes & ADJ_OFFSET) { /* values checked earlier */
+ if (txc->modes == ADJ_OFFSET_SINGLESHOT) {
+ /* adjtime() is independent from ntp_adjtime() */
+ if ((time_next_adjust = txc->offset) == 0)
+ time_adjust = 0;
+ }
+ else if (time_status & STA_PLL) {
+ ltemp = txc->offset;
+
+ /*
+ * Scale the phase adjustment and
+ * clamp to the operating range.
+ */
+ if (ltemp > MAXPHASE)
+ time_offset = MAXPHASE << SHIFT_UPDATE;
+ else if (ltemp < -MAXPHASE)
+ time_offset = -(MAXPHASE << SHIFT_UPDATE);
+ else
+ time_offset = ltemp << SHIFT_UPDATE;
+
+ /*
+ * 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;
+ if (time_status & STA_FLL) {
+ if (mtemp >= MINSEC) {
+ ltemp = (time_offset / mtemp) << (SHIFT_USEC -
+ SHIFT_UPDATE);
+ time_freq += shift_right(ltemp, SHIFT_KH);
+ } else /* calibration interval too short (p. 12) */
+ result = TIME_ERROR;
+ } else { /* PLL mode */
+ if (mtemp < MAXSEC) {
+ ltemp *= mtemp;
+ time_freq += shift_right(ltemp,(time_constant +
+ time_constant +
+ SHIFT_KF - SHIFT_USEC));
+ } else /* calibration interval too long (p. 12) */
+ result = TIME_ERROR;
+ }
+ time_freq = min(time_freq, time_tolerance);
+ time_freq = max(time_freq, -time_tolerance);
+ } /* STA_PLL */
+ } /* txc->modes & ADJ_OFFSET */
+ if (txc->modes & ADJ_TICK) {
+ tick_usec = txc->tick;
+ tick_nsec = TICK_USEC_TO_NSEC(tick_usec);
+ }
+ } /* 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);
+ }
+ txc->freq = time_freq;
+ txc->maxerror = time_maxerror;
+ txc->esterror = time_esterror;
+ txc->status = time_status;
+ txc->constant = time_constant;
+ txc->precision = time_precision;
+ txc->tolerance = time_tolerance;
+ 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);
+}