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

[York Sun <yorksun@freescale.com>]

On 01/13/2015 05:19 AM, 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 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>
> ---
>  arch/arm/cpu/armv8/start.S   |   47 ++++++++++++++++++++++++++++++++++++++++++
>  arch/arm/include/asm/macro.h |   20 ++++++++++++++++++
>  2 files changed, 67 insertions(+)
> 
> diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
> index 4b11aa4..d5bcf12 100644
> --- a/arch/arm/cpu/armv8/start.S
> +++ b/arch/arm/cpu/armv8/start.S
> @@ -100,6 +100,8 @@ master_cpu:
>  WEAK(lowlevel_init)
>  	mov	x29, lr			/* Save LR */
>  
> +	bl	apply_core_errata
> +
>  #if defined(CONFIG_GICV2) || defined(CONFIG_GICV3)
>  	branch_if_slave x0, 1f
>  	ldr	x0, =GICD_BASE
> @@ -155,6 +157,51 @@ ENDPROC(smp_kick_all_cpus)
>  
>  /*-----------------------------------------------------------------------*/
>  
> +WEAK(apply_core_errata)
> +	mov	x29, lr			/* Save LR */
> +
> +	/* 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:
> +	mov	lr, x29			/* Restore LR */
> +	ret
> +ENDPROC(apply_core_errata)
> +
> +/*-----------------------------------------------------------------------*/
> +
> +WEAK(apply_a57_core_errata)
> +	mov	x29, lr			/* Save LR */
> +
> +#ifdef CONFIG_ARM_ERRATA_828024
> +	mrs	x0, S3_1_c15_c2_0	/* cpuactlr_el1 */
> +	/* Disable non-allocate hint of w-b-n-a memory type */
> +	mov	x0, #0x1 << 49
> +	/* Disable write streaming no L1-allocate threshold */
> +	mov	x0, #0x3 << 25
> +	/* Disable write streaming no-allocate threshold */
> +	mov	x0, #0x3 << 27
> +	msr	S3_1_c15_c2_0, x0	/* cpuactlr_el1 */
> +#endif
> +
> +#ifdef CONFIG_ARM_ERRATA_826974
> +	mrs	x0, S3_1_c15_c2_0	/* cpuactlr_el1 */
> +	/* Disable speculative load execution ahead of a DMB */
> +	mov	x0, #0x1 << 59
> +	msr	S3_1_c15_c2_0, x0	/* cpuactlr_el1 */
> +#endif
> +
> +	mov	lr, x29			/* Restore LR */
> +	ret
> +ENDPROC(apply_a57_core_errata)
> +

Bhupesh,

Have you tested your patch on simulator/emulator? It seems you use x29
recursively. x29 holds the return address for function lowlevel_init. You use it
multiple times, so the program will not run correctly.

Beside, you implement this framework in lowlevel_init function, which is a weak
function. I guess you may have tested for LS2085A simulator, but we have a
different lowlevel_init function implemented. You may want to add a new function
call before "bl lowlevel_init".

York