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ARM: mxs: Setup scheduler clock 

Setup scheduler clock on ARM MXS platforms with a 32-bit timrot
such as i.MX28. This allows the scheduler to use sub-jiffy resolution.

The corresponding change for 16-bit v1 timrots is not possible
at the moment due to rounding issues with clock values wrapping
faster than once per several seconds in the common ARM platform code.

Signed-off-by: Stanislav Meduna <stano@meduna.org>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
This commit is contained in:
Stanislav Meduna 2012-11-08 23:39:14 +01:00 committed by Shawn Guo
parent 24196d5c59
commit 67948adad1
1 changed files with 9 additions and 1 deletions
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10
arch/arm/mach-mxs/timer.c
View File

@ -29,6 +29,7 @@
#include <linux/of_irq.h>
#include <asm/mach/time.h>
#include <asm/sched_clock.h>
#include <mach/mxs.h>
#include <mach/common.h>
@ -233,15 +234,22 @@ static struct clocksource clocksource_mxs = {
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static u32 notrace mxs_read_sched_clock_v2(void)
{
return ~readl_relaxed(mxs_timrot_base + HW_TIMROT_RUNNING_COUNTn(1));
}
static int __init mxs_clocksource_init(struct clk *timer_clk)
{
unsigned int c = clk_get_rate(timer_clk);
if (timrot_is_v1())
clocksource_register_hz(&clocksource_mxs, c);
else
else {
clocksource_mmio_init(mxs_timrot_base + HW_TIMROT_RUNNING_COUNTn(1),
"mxs_timer", c, 200, 32, clocksource_mmio_readl_down);
setup_sched_clock(mxs_read_sched_clock_v2, 32, c);
}
return 0;
}