linux-kernel - [PATCH] omap: add sched_clock for omap1 based on MPU timer

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Date:	Fri, 22 May 2009 12:47:24 -0700
From:	Tim Bird <tim.bird@...sony.com>
To:	linux kernel <linux-kernel@...r.kernel.org>
CC:	Kevin Hilman <khilman@...prootsystems.com>,
	linux-arm-kernel <linux-arm-kernel@...ts.arm.linux.org.uk>,
	linux-omap-open-source@...ux.omap.com
Subject: [PATCH] omap: add sched_clock for omap1 based on MPU timer

Define a higher-resolution sched_clock for OMAP
using the MPU timer, when it is configured on.

This produces better results from ftrace.

Signed-off-by: Tim Bird <tim.bird@...sony.com>
---
 arch/arm/mach-omap1/time.c  |    9 +++++++++
 arch/arm/plat-omap/common.c |    2 ++
 2 files changed, 11 insertions(+)

--- a/arch/arm/mach-omap1/time.c
+++ b/arch/arm/mach-omap1/time.c
@@ -212,6 +212,15 @@ static struct clocksource clocksource_mp
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 };

+unsigned long long notrace sched_clock(void)
+{
+	unsigned long long ret;
+
+	ret = (unsigned long long) ~omap_mpu_timer_read(1);
+	ret = (ret * clocksource_mpu.mult_orig) >> clocksource_mpu.shift;
+	return ret;
+}
+
 static void __init omap_init_clocksource(unsigned long rate)
 {
 	static char err[] __initdata = KERN_ERR
--- a/arch/arm/plat-omap/common.c
+++ b/arch/arm/plat-omap/common.c
@@ -199,6 +199,7 @@ static struct clocksource clocksource_32
 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 };

+#ifndef CONFIG_OMAP_MPU_TIMER
 /*
  * Returns current time from boot in nsecs. It's OK for this to wrap
  * around for now, as it's just a relative time stamp.
@@ -211,6 +212,7 @@ unsigned long long notrace sched_clock(v
 	ret = (ret * clocksource_32k.mult_orig) >> clocksource_32k.shift;
 	return ret;
 }
+#endif

 static int __init omap_init_clocksource_32k(void)
 {

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