ARM: fix regression in IXP4xx clocksource

From: Richard Cochran <richardcochran@gmail.com>

Commit 234b6ceddb4fc2a4bc5b9a7670f070f6e69e0868

   clocksource: convert ARM 32-bit up counting clocksources

broke the build for ixp4xx and made big endian operation impossible.
This commit restores the original behaviour.

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Signed-off-by: Krzysztof Hałasa <khc@pm.waw.pl>

Did you see Thomas' reply to your last patch?  Would you mind responding
to that please, before asking Linus to merge this?

On Wed, Jul 06, 2011 at 11:02:17PM +0200, Krzysztof Halasa wrote:
> From: Richard Cochran <richardcochran@gmail.com>
> 
> Commit 234b6ceddb4fc2a4bc5b9a7670f070f6e69e0868
> 
>    clocksource: convert ARM 32-bit up counting clocksources
> 
> broke the build for ixp4xx and made big endian operation impossible.
> This commit restores the original behaviour.
> 
> Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
> Signed-off-by: Krzysztof Hałasa <khc@pm.waw.pl>
> 
> diff --git a/arch/arm/mach-ixp4xx/common.c b/arch/arm/mach-ixp4xx/common.c
> index 74ed81a..0777257 100644
> --- a/arch/arm/mach-ixp4xx/common.c
> +++ b/arch/arm/mach-ixp4xx/common.c
> @@ -419,14 +419,20 @@ static void notrace ixp4xx_update_sched_clock(void)
>  /*
>   * clocksource
>   */
> +
> +static cycle_t ixp4xx_clocksource_read(struct clocksource *c)
> +{
> +	return *IXP4XX_OSTS;
> +}
> +
>  unsigned long ixp4xx_timer_freq = IXP4XX_TIMER_FREQ;
>  EXPORT_SYMBOL(ixp4xx_timer_freq);
>  static void __init ixp4xx_clocksource_init(void)
>  {
>  	init_sched_clock(&cd, ixp4xx_update_sched_clock, 32, ixp4xx_timer_freq);
>  
> -	clocksource_mmio_init(&IXP4XX_OSTS, "OSTS", ixp4xx_timer_freq, 200, 32,
> -			clocksource_mmio_readl_up);
> +	clocksource_mmio_init(NULL, "OSTS", ixp4xx_timer_freq, 200, 32,
> +			ixp4xx_clocksource_read);
>  }
>  
>  /*
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Russell King - ARM Linux <linux@arm.linux.org.uk> writes:

> Did you see Thomas' reply to your last patch?  Would you mind responding
> to that please, before asking Linus to merge this?

I like the BE (or endian-neutral value-preserving) accessor idea.
Nevertheless Linux on IXP4xx doesn't even build at this time and I think
fixing this before 3.0 is well worth it.

I assume changing the common ARM code to use new accessors will happen
post-3.0.

(BTW that was Richard Cochran's patch)

On Wed, Jul 06, 2011 at 11:02:17PM +0200, Krzysztof Halasa wrote:
> From: Richard Cochran <richardcochran@gmail.com>
> 
> Commit 234b6ceddb4fc2a4bc5b9a7670f070f6e69e0868
> 
>    clocksource: convert ARM 32-bit up counting clocksources
> 
> broke the build for ixp4xx and made big endian operation impossible.
> This commit restores the original behaviour.

I know I nag, but can we *please* have this patch in 3.0?
Big endian IXP really, really does not work without it.

Thanks,

Richard

> 
> Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
> Signed-off-by: Krzysztof Hałasa <khc@pm.waw.pl>
> 
> diff --git a/arch/arm/mach-ixp4xx/common.c b/arch/arm/mach-ixp4xx/common.c
> index 74ed81a..0777257 100644
> --- a/arch/arm/mach-ixp4xx/common.c
> +++ b/arch/arm/mach-ixp4xx/common.c
> @@ -419,14 +419,20 @@ static void notrace ixp4xx_update_sched_clock(void)
>  /*
>   * clocksource
>   */
> +
> +static cycle_t ixp4xx_clocksource_read(struct clocksource *c)
> +{
> +	return *IXP4XX_OSTS;
> +}
> +
>  unsigned long ixp4xx_timer_freq = IXP4XX_TIMER_FREQ;
>  EXPORT_SYMBOL(ixp4xx_timer_freq);
>  static void __init ixp4xx_clocksource_init(void)
>  {
>  	init_sched_clock(&cd, ixp4xx_update_sched_clock, 32, ixp4xx_timer_freq);
>  
> -	clocksource_mmio_init(&IXP4XX_OSTS, "OSTS", ixp4xx_timer_freq, 200, 32,
> -			clocksource_mmio_readl_up);
> +	clocksource_mmio_init(NULL, "OSTS", ixp4xx_timer_freq, 200, 32,
> +			ixp4xx_clocksource_read);
>  }
>  
>  /*
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

On Tue, Jul 12, 2011 at 10:05:13AM +0200, Richard Cochran wrote:
> On Wed, Jul 06, 2011 at 11:02:17PM +0200, Krzysztof Halasa wrote:
> > From: Richard Cochran <richardcochran@gmail.com>
> > 
> > Commit 234b6ceddb4fc2a4bc5b9a7670f070f6e69e0868
> > 
> >    clocksource: convert ARM 32-bit up counting clocksources
> > 
> > broke the build for ixp4xx and made big endian operation impossible.
> > This commit restores the original behaviour.
> 
> I know I nag, but can we *please* have this patch in 3.0?
> Big endian IXP really, really does not work without it.

Thomas Glexnier said:
> Thinking more about it we should add BE accessor functions to the mmio
> clocksource as this might be useful for other architectures as well.

It seems that I can't rely on others, so I'm going to have to fit
this into my busy schedule at some point.