timekeeping: Move NTP adjusted clock multiplier to struct timekeeper
The clocksource structure has two multipliers, the unmodified multiplier
clock->mult_orig and the NTP corrected multiplier clock->mult. The NTP
multiplier is misplaced in the struct clocksource, this is private
information of the timekeeping code. Add the mult field to the struct
timekeeper to contain the NTP corrected value, keep the unmodifed
multiplier in clock->mult and remove clock->mult_orig.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Daniel Walker <dwalker@fifo99.com>
LKML-Reference: <20090814134810.149047645@de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/arm/plat-omap/common.c b/arch/arm/plat-omap/common.c
index ebcf0064..95587b6 100644
--- a/arch/arm/plat-omap/common.c
+++ b/arch/arm/plat-omap/common.c
@@ -253,11 +253,8 @@
*/
unsigned long long sched_clock(void)
{
- unsigned long long ret;
-
- ret = (unsigned long long)clocksource_32k.read(&clocksource_32k);
- ret = (ret * clocksource_32k.mult_orig) >> clocksource_32k.shift;
- return ret;
+ return clocksource_cyc2ns(clocksource_32k.read(&clocksource_32k),
+ clocksource_32k.mult, clocksource_32k.shift);
}
static int __init omap_init_clocksource_32k(void)
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index e12e309..e34015e 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -149,8 +149,7 @@
* @disable: optional function to disable the clocksource
* @mask: bitmask for two's complement
* subtraction of non 64 bit counters
- * @mult: cycle to nanosecond multiplier (adjusted by NTP)
- * @mult_orig: cycle to nanosecond multiplier (unadjusted by NTP)
+ * @mult: cycle to nanosecond multiplier
* @shift: cycle to nanosecond divisor (power of two)
* @flags: flags describing special properties
* @vread: vsyscall based read
@@ -168,7 +167,6 @@
void (*disable)(struct clocksource *cs);
cycle_t mask;
u32 mult;
- u32 mult_orig;
u32 shift;
unsigned long flags;
cycle_t (*vread)(void);
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index dfdab1c..f4056f6 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -41,6 +41,8 @@
/* Shift conversion between clock shifted nano seconds and
* ntp shifted nano seconds. */
int ntp_error_shift;
+ /* NTP adjusted clock multiplier */
+ u32 mult;
};
struct timekeeper timekeeper;
@@ -66,8 +68,8 @@
/* Do the ns -> cycle conversion first, using original mult */
tmp = NTP_INTERVAL_LENGTH;
tmp <<= clock->shift;
- tmp += clock->mult_orig/2;
- do_div(tmp, clock->mult_orig);
+ tmp += clock->mult/2;
+ do_div(tmp, clock->mult);
if (tmp == 0)
tmp = 1;
@@ -77,13 +79,20 @@
/* Go back from cycles -> shifted ns */
timekeeper.xtime_interval = (u64) interval * clock->mult;
timekeeper.raw_interval =
- ((u64) interval * clock->mult_orig) >> clock->shift;
+ ((u64) interval * clock->mult) >> clock->shift;
timekeeper.xtime_nsec = 0;
timekeeper.shift = clock->shift;
timekeeper.ntp_error = 0;
timekeeper.ntp_error_shift = NTP_SCALE_SHIFT - clock->shift;
+
+ /*
+ * The timekeeper keeps its own mult values for the currently
+ * active clocksource. These value will be adjusted via NTP
+ * to counteract clock drifting.
+ */
+ timekeeper.mult = clock->mult;
}
/*
@@ -154,14 +163,15 @@
cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
clock->cycle_last = cycle_now;
- nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
+ nsec = clocksource_cyc2ns(cycle_delta, timekeeper.mult,
+ timekeeper.shift);
/* If arch requires, add in gettimeoffset() */
nsec += arch_gettimeoffset();
timespec_add_ns(&xtime, nsec);
- nsec = clocksource_cyc2ns(cycle_delta, clock->mult_orig, clock->shift);
+ nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
timespec_add_ns(&raw_time, nsec);
}
@@ -193,8 +203,8 @@
cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
/* convert to nanoseconds: */
- nsecs = clocksource_cyc2ns(cycle_delta, clock->mult,
- clock->shift);
+ nsecs = clocksource_cyc2ns(cycle_delta, timekeeper.mult,
+ timekeeper.shift);
/* If arch requires, add in gettimeoffset() */
nsecs += arch_gettimeoffset();
@@ -228,8 +238,8 @@
cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
/* convert to nanoseconds: */
- nsecs += clocksource_cyc2ns(cycle_delta, clock->mult,
- clock->shift);
+ nsecs += clocksource_cyc2ns(cycle_delta, timekeeper.mult,
+ timekeeper.shift);
} while (read_seqretry(&xtime_lock, seq));
/*
@@ -271,8 +281,8 @@
cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
/* convert to nanoseconds: */
- nsecs = clocksource_cyc2ns(cycle_delta, clock->mult,
- clock->shift);
+ nsecs = clocksource_cyc2ns(cycle_delta, timekeeper.mult,
+ timekeeper.shift);
} while (read_seqretry(&xtime_lock, seq));
@@ -356,22 +366,10 @@
if (new->enable && !new->enable(new))
return;
- /*
- * The frequency may have changed while the clocksource
- * was disabled. If so the code in ->enable() must update
- * the mult value to reflect the new frequency. Make sure
- * mult_orig follows this change.
- */
- new->mult_orig = new->mult;
old = timekeeper.clock;
timekeeper_setup_internals(new);
- /*
- * Save mult_orig in mult so that the value can be restored
- * regardless if ->enable() updates the value of mult or not.
- */
- old->mult = old->mult_orig;
if (old->disable)
old->disable(old);
@@ -461,7 +459,7 @@
cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
/* convert to nanoseconds: */
- nsecs = clocksource_cyc2ns(cycle_delta, clock->mult_orig,
+ nsecs = clocksource_cyc2ns(cycle_delta, clock->mult,
clock->shift);
*ts = raw_time;
@@ -521,9 +519,6 @@
clock = clocksource_default_clock();
if (clock->enable)
clock->enable(clock);
- /* set mult_orig on enable */
- clock->mult_orig = clock->mult;
-
timekeeper_setup_internals(clock);
xtime.tv_sec = sec;
@@ -697,7 +692,7 @@
} else
return;
- timekeeper.clock->mult += adj;
+ timekeeper.mult += adj;
timekeeper.xtime_interval += interval;
timekeeper.xtime_nsec -= offset;
timekeeper.ntp_error -= (interval - offset) <<
@@ -789,7 +784,7 @@
timekeeper.ntp_error += timekeeper.xtime_nsec <<
timekeeper.ntp_error_shift;
- nsecs = clocksource_cyc2ns(offset, clock->mult, clock->shift);
+ nsecs = clocksource_cyc2ns(offset, timekeeper.mult, timekeeper.shift);
update_xtime_cache(nsecs);
/* check to see if there is a new clocksource to use */