[U-Boot] [PATCH 1/3] ARM: implement some Cortex-A9 errata workarounds

[Albert ARIBAUD <albert.u.boot@aribaud.net>]

Hi Stephen,

On Tue, 26 Feb 2013 15:28:27 -0700, Stephen Warren
<swarren@wwwdotorg.org> wrote:

> From: Stephen Warren <swarren@nvidia.com>
> 
> Various errata exist in the Cortex-A9 CPU, and may be worked around by
> setting some bits in a CP15 diagnostic register. Add code to implement
> the workarounds, enabled by new CONFIG_ options.
> 
> This code was taken from the Linux kernel, v3.8, arch/arm/mm/proc-v7.S,
> and modified to remove the logic to conditionally apply the WAR (since we
> know exactly which CPU we're running on given the U-Boot configuration),
> and use r0 instead of r10 for consistency with the rest of U-Boot's
> cpu_init_cp15().
> 
> Signed-off-by: Stephen Warren <swarren@nvidia.com>
> ---
>  README                     |   10 ++++++++++
>  arch/arm/cpu/armv7/start.S |   19 +++++++++++++++++++
>  2 files changed, 29 insertions(+)
> 
> diff --git a/README b/README
> index d8cb394..f2b1c88 100644
> --- a/README
> +++ b/README
> @@ -485,6 +485,16 @@ The following options need to be configured:
>  		Thumb2 this flag will result in Thumb2 code generated by
>  		GCC.
>  
> +		CONFIG_ARM_ERRATA_742230
> +		CONFIG_ARM_ERRATA_743622
> +		CONFIG_ARM_ERRATA_751472
> +
> +		If set, the workarounds for these ARM errata are applied early
> +		during U-Boot startup. Note that these options force the
> +		workarounds to be applied; no CPU-type/version detection
> +		exists, unlike the similar options in the Linux kernel. Do not
> +		set these options unless they apply!
> +
>  - Linux Kernel Interface:
>  		CONFIG_CLOCKS_IN_MHZ
>  
> diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
> index 6b59529d..30f02d3 100644
> --- a/arch/arm/cpu/armv7/start.S
> +++ b/arch/arm/cpu/armv7/start.S
> @@ -309,6 +309,25 @@ ENTRY(cpu_init_cp15)
>  	orr	r0, r0, #0x00001000	@ set bit 12 (I) I-cache
>  #endif
>  	mcr	p15, 0, r0, c1, c0, 0
> +
> +#ifdef CONFIG_ARM_ERRATA_742230
> +	mrc	p15, 0, r0, c15, c0, 1	@ read diagnostic register
> +	orr	r0, r0, #1 << 4		@ set bit #4
> +	mcr	p15, 0, r0, c15, c0, 1	@ write diagnostic register
> +#endif
> +
> +#ifdef CONFIG_ARM_ERRATA_743622
> +	mrc	p15, 0, r0, c15, c0, 1	@ read diagnostic register
> +	orr	r0, r0, #1 << 6		@ set bit #6
> +	mcr	p15, 0, r0, c15, c0, 1	@ write diagnostic register
> +#endif
> +
> +#ifdef CONFIG_ARM_ERRATA_751472
> +	mrc	p15, 0, r0, c15, c0, 1	@ read diagnostic register
> +	orr	r0, r0, #1 << 11	@ set bit #11
> +	mcr	p15, 0, r0, c15, c0, 1	@ write diagnostic register
> +#endif
> +
>  	mov	pc, lr			@ back to my caller
>  ENDPROC(cpu_init_cp15)
>  

Applied to u-boot-arm/master, thanks!

Amicalement,
-- 
Albert.