Subject: [PATCH] ARM: cache: flush to LoUU instead of LoUIS on uniprocessor CPUs

From: [email-masked] (Santosh Shilimkar)
Date: Thu, 20 Dec 2012 12:36:20 +0530

On Monday 17 December 2012 09:40 PM, Will Deacon wrote:
> flush_cache_louis flushes the D-side caches to the point of unification
> inner-shareable. On uniprocessor CPUs, this is defined as zero and
> therefore no flushing will take place. Rather than invent a new interface
> for UP systems, instead use our SMP_ON_UP patching code to read the
> LoUU from the CLIDR instead.
>
> Cc: Lorenzo Pieralisi <[email-masked]>
> Tested-by: Guennadi Liakhovetski <[email-masked]>
> Signed-off-by: Will Deacon <[email-masked]>
> ---
Looks reasonable idea.
Acked-by: Santosh Shilimkar <[email-masked]>

>   arch/arm/mm/cache-v7.S | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/mm/cache-v7.S b/arch/arm/mm/cache-v7.S
> index cd95664..7539ec2 100644
> --- a/arch/arm/mm/cache-v7.S
> +++ b/arch/arm/mm/cache-v7.S
> @@ -44,8 +44,10 @@ ENDPROC(v7_flush_icache_all)
>   ENTRY(v7_flush_dcache_louis)
>   	dmb					@ ensure ordering with previous memory accesses
>   	mrc	p15, 1, r0, c0, c0, 1		@ read clidr, r0 = clidr
> -	ands	r3, r0, #0xe00000		@ extract LoUIS from clidr
> -	mov	r3, r3, lsr #20			@ r3 = LoUIS * 2
> +	ALT_SMP(ands	r3, r0, #(7 << 21))	@ extract LoUIS from clidr
> +	ALT_UP(ands	r3, r0, #(7 << 27))	@ extract LoUU from clidr
> +	ALT_SMP(mov	r3, r3, lsr #20)	@ r3 = LoUIS * 2
> +	ALT_UP(mov	r3, r3, lsr #26)	@ r3 = LoUU * 2
>   	moveq	pc, lr				@ return if level == 0
>   	mov	r10, #0				@ r10 (starting level) = 0
>   	b	flush_levels			@ start flushing cache levels
>