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m68knommu: add sched_clock() for the DMA timer

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with this printk() and other sched_clock() user use the more precise
timestamps. The highly optimized math is from arch/x86/kernel/tsc_32.c.

Signed-off-by: Sebastian Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
This commit is contained in:
Sebastian Siewior 2008-04-28 11:43:03 +02:00 committed by Greg Ungerer
parent 95469bd64a
commit 5bed10a5ee
1 changed files with 16 additions and 0 deletions
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16
arch/m68knommu/platform/coldfire/dma_timer.c
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@ -66,3 +66,19 @@ static int __init init_cf_dt_clocksource(void)
} }
arch_initcall(init_cf_dt_clocksource); arch_initcall(init_cf_dt_clocksource);
#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
#define CYC2NS_SCALE ((1000000 << CYC2NS_SCALE_FACTOR) / (DMA_FREQ / 1000))
static unsigned long long cycles2ns(unsigned long cycl)
{
return (unsigned long long) ((unsigned long long)cycl *
CYC2NS_SCALE) >> CYC2NS_SCALE_FACTOR;
}
unsigned long long sched_clock(void)
{
unsigned long cycl = __raw_readl(DTCN0);
return cycles2ns(cycl);
}