From: Sebastian Siewior <bigeasy@linutronix.de>
Date: Mon, 28 Apr 2008 09:43:03 +0000 (+0200)
Subject: m68knommu: add sched_clock() for the DMA timer
X-Git-Tag: v2.6.27-rc1~519^2~8
X-Git-Url: http://www.pilppa.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=5bed10a5ee272fbf18ce0ce764245bbb8f28e2e6;p=linux-2.6-omap-h63xx.git

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>
---

diff --git a/arch/m68knommu/platform/coldfire/dma_timer.c b/arch/m68knommu/platform/coldfire/dma_timer.c
index b623c993219..772578b1084 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);
+}