[U-Boot] [PATCH v2 1/2] Errata/ARM57: Add basic constructs to handle and apply A57 specific erratas

[Scott Wood <scottwood@freescale.com>]

On Wed, 2015-01-14 at 19:16 +0530, Bhupesh Sharma wrote:
> This patch adds basic constructs in the ARMv8 u-boot code
> to handle and apply Cortex-A57 specific erratas.
> 
> As and example, the framework showcases how erratas 833069, 826974
> and 828024 can be handled and applied.
> 
> Later on this framework can be extended to include other
> erratas.
> 
> Signed-off-by: Bhupesh Sharma <bhupesh.sharma@freescale.com>
> ---
> Changes from v1:
> 	- Addressed York's comment about x29 usage and calling the
> 	  core errata fxup function before the lowlevel_init function
> 	  is called.
> 
>  arch/arm/cpu/armv8/start.S   |   51 ++++++++++++++++++++++++++++++++++++++++++
>  arch/arm/include/asm/macro.h |   20 +++++++++++++++++
>  2 files changed, 71 insertions(+)
> 
> diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
> index 4b11aa4..df532f9 100644
> --- a/arch/arm/cpu/armv8/start.S
> +++ b/arch/arm/cpu/armv8/start.S
> @@ -67,6 +67,9 @@ reset:
>  	msr	cpacr_el1, x0			/* Enable FP/SIMD */
>  0:
>  
> +	/* Apply ARM core specific erratas */
> +	bl	apply_core_errata
> +
>  	/*
>  	 * Cache/BPB/TLB Invalidate
>  	 * i-cache is invalidated before enabled in icache_enable()
> @@ -97,6 +100,54 @@ master_cpu:
>  
>  /*-----------------------------------------------------------------------*/
>  
> +WEAK(apply_core_errata)
> +
> +	/* For now, we support Cortex-A57 specific errata only */
> +
> +	/* Check if we are running on a Cortex-A57 core */
> +	branch_if_a57_core x0, 1f
> +	b	2f
> +1:
> +	bl	apply_a57_core_errata
> +
> +2:

This is awkward.  How often are you expecting to use this macro?  Why
not just open-code it?  Or at least make it "branch_if_not_a57_core".
Or fix your lr problem by doing "branch_if_a57_core
apply_a57_core_errata" and having it branch back rather than "ret".

But I think opencoding would be best.  Just define symbols for the
actual core IDs.

> +WEAK(apply_a57_core_errata)

Why is this weak?

-Scott