[U-Boot] [PATCH 3/6] armv8/mmu: Clean up TCR programming

[Marc Zyngier]

On 20/03/15 11:47, Thierry Reding wrote:
> From: Thierry Reding <treding at nvidia.com>
> 
> Use the inner shareable attribute for memory, which makes more sense
> considering that this code is called when caches are being enabled.
> 
> While at it, fix the values for the shareability attribute field to
> match the documentation.
> 
> Cc: Albert Aribaud <albert.u.boot at aribaud.net>
> Cc: Marc Zyngier <marc.zyngier at arm.com>
> Signed-off-by: Thierry Reding <treding at nvidia.com>
> ---
>  arch/arm/include/asm/armv8/mmu.h | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/include/asm/armv8/mmu.h b/arch/arm/include/asm/armv8/mmu.h
> index 4b9cb5296572..6d42f5533a74 100644
> --- a/arch/arm/include/asm/armv8/mmu.h
> +++ b/arch/arm/include/asm/armv8/mmu.h
> @@ -93,8 +93,8 @@
>  #define TCR_ORGN_WBNWA		(3 << 10)
>  #define TCR_ORGN_MASK		(3 << 10)
>  #define TCR_SHARED_NON		(0 << 12)
> -#define TCR_SHARED_OUTER	(1 << 12)
> -#define TCR_SHARED_INNER	(2 << 12)
> +#define TCR_SHARED_OUTER	(2 << 12)
> +#define TCR_SHARED_INNER	(3 << 12)
>  #define TCR_TG0_4K		(0 << 14)
>  #define TCR_TG0_64K		(1 << 14)
>  #define TCR_TG0_16K		(2 << 14)
> @@ -102,9 +102,9 @@
>  #define TCR_EL2_IPS_BITS	(3 << 16)	/* 42 bits physical address */
>  #define TCR_EL3_IPS_BITS	(3 << 16)	/* 42 bits physical address */
>  
> -/* PTWs cacheable, inner/outer WBWA and non-shareable */
> +/* PTWs cacheable, inner/outer WBWA and inner shareable */
>  #define TCR_FLAGS		(TCR_TG0_64K |		\
> -				TCR_SHARED_NON |	\
> +				TCR_SHARED_INNER |	\
>  				TCR_ORGN_WBWA |		\
>  				TCR_IRGN_WBWA |		\
>  				TCR_T0SZ(VA_BITS))
> 

Acked-by: Marc Zyngier <marc.zyngier at arm.com>

One thing though: the architecture doesn't mandate 64k pages to be
implemented by the HW. Actually, it doesn't mandate any particular page
size, you just have to implement at least one (4k, 16k or 64k).

It would be good to test if 64k pages are implemented (by testing
ID_AA64MMFR0_EL1) and not try to enable caches if not, possibly
displaying a warning for the unsuspecting u-boot hacker.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...