[PATCH] ARM: mxs: Setup scheduler clock

[Shawn Guo]

On Thu, Nov 08, 2012 at 11:45:45PM +0100, Stanislav Meduna wrote:
> Hi,
> 
> OK, as the problem with 16-bit fast ticking timer looks to
> be more complicated, I'd like to submit the patch for the 32-bit
> ones.
> 
> Thanks
> -- 
>                                     Stano
> 

> From 74092cc0217a5bab6f80ee07aa188a54f5792634 Mon Sep 17 00:00:00 2001
> From: Stanislav Meduna <stano at meduna.org>
> Date: Mon, 8 Nov 2012 23:39:14 +0100
> Subject: [PATCH] ARM: mxs: Setup scheduler clock
> 
> Setup scheduler clock on ARM MXS platforms with a 32-bit timrot
> such as MX.28. This allows the scheduler to use sub-jiffy resolution.
> 
s/MX.28/i.MX28

I fixed it up and applied the patch.  Thanks.

Shawn

> 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 at meduna.org>
> ---
>  arch/arm/mach-mxs/timer.c |   10 +++++++++-
>  1 files changed, 9 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/arm/mach-mxs/timer.c b/arch/arm/mach-mxs/timer.c
> index 564a632..4b6e36c 100644
> --- a/arch/arm/mach-mxs/timer.c
> +++ b/arch/arm/mach-mxs/timer.c
> @@ -26,6 +26,7 @@
>  #include <linux/clk.h>
>  
>  #include <asm/mach/time.h>
> +#include <asm/sched_clock.h>
>  #include <mach/mxs.h>
>  #include <mach/common.h>
>  
> @@ -230,15 +231,22 @@ 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;
>  }
> -- 
> 1.7.0.4
>