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davinci: Implement sched_clock()

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Overwrite the default implementation of sched_clock that is based on
jiffies by something more precise. This improves timestamps in ftrace.
Implementation is copied from OMAP platform code.

Signed-off-by: Andreas Gaeer <Andreas.Gaer@baslerweb.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
This commit is contained in:
Andreas Gaeer 2010-10-06 10:38:55 +02:00 committed by Kevin Hilman
parent cf7d7e5a19
commit 6d1c57c84c
1 changed files with 23 additions and 1 deletions
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24
arch/arm/mach-davinci/time.c
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@ -272,14 +272,35 @@ static cycle_t read_cycles(struct clocksource *cs)
return (cycles_t)timer32_read(t);
}
/*
* Kernel assumes that sched_clock can be called early but may not have
* things ready yet.
*/
static cycle_t read_dummy(struct clocksource *cs)
{
return 0;
}
static struct clocksource clocksource_davinci = {
.rating = 300,
.read = read_cycles,
.read = read_dummy,
.mask = CLOCKSOURCE_MASK(32),
.shift = 24,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
/*
* Overwrite weak default sched_clock with something more precise
*/
unsigned long long notrace sched_clock(void)
{
const cycle_t cyc = clocksource_davinci.read(&clocksource_davinci);
return clocksource_cyc2ns(cyc, clocksource_davinci.mult,
clocksource_davinci.shift);
}
/*
* clockevent
*/
@ -377,6 +398,7 @@ static void __init davinci_timer_init(void)
davinci_clock_tick_rate = clk_get_rate(timer_clk);
/* setup clocksource */
clocksource_davinci.read = read_cycles;
clocksource_davinci.name = id_to_name[clocksource_id];
clocksource_davinci.mult =
clocksource_khz2mult(davinci_clock_tick_rate/1000,