[U-Boot] [PATCH 8/8] MIPS: clear TagLo select 2 during cache init

[Daniel Schwierzeck]

Am 26.01.2015 um 16:03 schrieb Paul Burton:
> Current MIPS cores from Imagination Technologies use TagLo select 2 for
> the data cache. The architecture requires that it is safe for software
> to write to this register even if it isn't present, so take the trivial
> option of clearing both selects 0 & 2.
> 
> Signed-off-by: Paul Burton <paul.burton at imgtec.com>
> Cc: Daniel Schwierzeck <daniel.schwierzeck at gmail.com>
> ---
>  arch/mips/lib/cache_init.S | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/mips/lib/cache_init.S b/arch/mips/lib/cache_init.S
> index 04a36b2..137d728 100644
> --- a/arch/mips/lib/cache_init.S
> +++ b/arch/mips/lib/cache_init.S
> @@ -139,6 +139,14 @@ LEAF(mips_cache_reset)
>  #endif /* CONFIG_SYS_MIPS_CACHE_INIT_RAM_LOAD */
>  
>  	/*
> +	 * The TagLo registers used depend upon the CPU implementation, but the
> +	 * architecture requires that it is safe for software to write to both
> +	 * TagLo selects 0 & 2 covering supported cases.
> +	 */
> +	mtc0		zero, CP0_TAGLO
> +	mtc0		zero, CP0_TAGLO, 2

maybe we should add new definitions to asm/mipsregs.h. In an out-of-tree
SoC port I have something like this

 #define CP0_ECC $26
 #define CP0_CACHEERR $27
 #define CP0_TAGLO $28
+#define CP0_ITAGLO $28
+#define CP0_IDATALO $28,1
+#define CP0_DTAGLO $28,2
+#define CP0_DDATALO $28,3
+#define CP0_L23TAGLO $28,4
+#define CP0_L23DATALO $28,5
 #define CP0_TAGHI $29
+#define CP0_IDATAHI $29,1
+#define CP0_DTAGHI $29,2
+#define CP0_L23TAGHI $29,4
+#define CP0_L23DATAHI $29,5
 #define CP0_ERROREPC $30
 #define CP0_DESAVE $31


> +
> +	/*
>  	 * The caches are probably in an indeterminate state, so we force good
>  	 * parity into them by doing an invalidate for each line. If
>  	 * CONFIG_SYS_MIPS_CACHE_INIT_RAM_LOAD is set then we'll proceed to
> @@ -151,7 +159,6 @@ LEAF(mips_cache_reset)
>  	 * Initialize the I-cache first,
>  	 */
>  	blez		t2, 1f
> -	mtc0		zero, CP0_TAGLO
>  	PTR_LI		t0, INDEX_BASE
>  	PTR_ADDU	t1, t0, t2
>  	/* clear tag to invalidate */
> @@ -169,7 +176,6 @@ LEAF(mips_cache_reset)
>  	 * then initialize D-cache.
>  	 */
>  1:	blez		t3, 3f
> -	mtc0		zero, CP0_TAGLO
>  	PTR_LI		t0, INDEX_BASE
>  	PTR_ADDU	t1, t0, t3
>  	/* clear all tags */
> 

-- 
- Daniel