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authorSebastian Siewior <bigeasy@linutronix.de>2008-04-28 11:43:03 +0200
committerGreg Ungerer <gerg@uclinux.org>2008-07-23 15:11:28 +1000
commit5bed10a5ee272fbf18ce0ce764245bbb8f28e2e6 (patch)
treee358b64949a0b709982c31b87381f40821af9873 /arch/m68knommu
parent95469bd64a7a9ab405b566deb8c81d4aaf67ed9e (diff)
m68knommu: add sched_clock() for the DMA timer
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>
Diffstat (limited to 'arch/m68knommu')
-rw-r--r--arch/m68knommu/platform/coldfire/dma_timer.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/m68knommu/platform/coldfire/dma_timer.c b/arch/m68knommu/platform/coldfire/dma_timer.c
index b623c993219e..772578b1084f 100644
--- a/arch/m68knommu/platform/coldfire/dma_timer.c
+++ b/arch/m68knommu/platform/coldfire/dma_timer.c
@@ -66,3 +66,19 @@ static int __init init_cf_dt_clocksource(void)
}
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);
+}