[U-Boot] [PATCH] nios2: set default cache configuration in start.S

[Marek Vasut]

On Tuesday, October 06, 2015 at 10:21:48 AM, Thomas Chou wrote:
> Set default icache and dcache configuration for start.S.
> The values are chosen so that it will work for most configurations.
> During initialization, cpu information will be extracted from
> device tree. Then cache flush operations will have correct
> cache configurations.
> 
> Signed-off-by: Thomas Chou <thomas at wytron.com.tw>
> ---
>  arch/nios2/cpu/start.S | 22 +++++++++++++++-------
>  1 file changed, 15 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/nios2/cpu/start.S b/arch/nios2/cpu/start.S
> index 00cec40..83d1576 100644
> --- a/arch/nios2/cpu/start.S
> +++ b/arch/nios2/cpu/start.S
> @@ -9,6 +9,15 @@
>  #include <config.h>
>  #include <version.h>
> 
> +/*
> + * icache and dcache configuration used only for start.S.
> + * the values are chosen so that it will work for all configuration.
> + */
> +#define ICACHE_LINE_SIZE	32 /* fixed 32 */
> +#define ICACHE_SIZE_MAX		0x10000 /* 64k max */
> +#define DCACHE_LINE_SIZE_MIN	4 /* 4, 16, 32 */
> +#define DCACHE_SIZE_MAX		0x10000 /* 64k max */
> +
>  /*************************************************************************
>   * RESTART
>   ************************************************************************/
> @@ -25,9 +34,9 @@ _start:
>  	 * just be invalidating the cache a second time. If cache
>  	 * is not implemented initi behaves as nop.
>  	 */
> -	ori	r4, r0, %lo(CONFIG_SYS_ICACHELINE_SIZE)
> -	movhi	r5, %hi(CONFIG_SYS_ICACHE_SIZE)
> -	ori	r5, r5, %lo(CONFIG_SYS_ICACHE_SIZE)
> +	ori	r4, r0, %lo(ICACHE_LINE_SIZE)
> +	movhi	r5, %hi(ICACHE_SIZE_MAX)
> +	ori	r5, r5, %lo(ICACHE_SIZE_MAX)
>  0:	initi	r5
>  	sub	r5, r5, r4
>  	bgt	r5, r0, 0b
> @@ -54,10 +63,9 @@ _except_end:
>  	 * DCACHE INIT -- if dcache not implemented, initd behaves as
>  	 * nop.
>  	 */
> -	movhi	r4, %hi(CONFIG_SYS_DCACHELINE_SIZE)
> -	ori	r4, r4, %lo(CONFIG_SYS_DCACHELINE_SIZE)
> -	movhi	r5, %hi(CONFIG_SYS_DCACHE_SIZE)
> -	ori	r5, r5, %lo(CONFIG_SYS_DCACHE_SIZE)
> +	ori	r4, r0, %lo(DCACHE_LINE_SIZE_MIN)
> +	movhi	r5, %hi(DCACHE_SIZE_MAX)
> +	ori	r5, r5, %lo(DCACHE_SIZE_MAX)
>  	mov	r6, r0
>  1:	initd	0(r6)
>  	add	r6, r6, r4

Did I miss the DT part somewhere or is that not part of this patch ?

Another question I have is -- why don't we set CONFIG_SYS_{I,D}CACHE_SIZE to
maximum value? This should work for all nios2 cache configurations and it should
also be correct, no ? Speed might be a bit of an issue here, but I doubt the
impact would be that large.

Best regards,
Marek Vasut