[U-Boot] [PATCH 2/5] arm: Allow reset init to be controlled

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

Hello Simon,

On Tue,  3 Feb 2015 21:18:51 -0700, Simon Glass <sjg@chromium.org>
wrote:
> Some boards want to skip the normal reset init. For example OMAP4 SPL
> does not want to touch VBAR and many boards don't want to set up
> CP15.
> 
> Provide a return value from save_boot_params() which allows the board
> to indicate what reset processing should be done.

Does this have to be at run-time? I'd rather it were a build-time
config option.

> Signed-off-by: Simon Glass <sjg@chromium.org>
> ---
> 
>  arch/arm/cpu/armv7/exynos/spl_boot.c |  5 ++++-
>  arch/arm/cpu/armv7/start.S           | 11 ++++++++---
>  arch/arm/include/asm/system.h        | 15 +++++++++++++++
>  3 files changed, 27 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/cpu/armv7/exynos/spl_boot.c b/arch/arm/cpu/armv7/exynos/spl_boot.c
> index bc237c9..6e249f1 100644
> --- a/arch/arm/cpu/armv7/exynos/spl_boot.c
> +++ b/arch/arm/cpu/armv7/exynos/spl_boot.c
> @@ -309,4 +309,7 @@ void board_init_r(gd_t *id, ulong dest_addr)
>  	while (1)
>  		;
>  }
> -void save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3) {}
> +u32 save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3)
> +{
> +	return 0;
> +}
> diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S
> index c5f94ef..0ba26f7 100644
> --- a/arch/arm/cpu/armv7/start.S
> +++ b/arch/arm/cpu/armv7/start.S
> @@ -52,6 +52,9 @@ reset:
>   * Continue to use ROM code vector only in OMAP4 spl)
>   */
>  #if !(defined(CONFIG_OMAP44XX) && defined(CONFIG_SPL_BUILD))
> +	teq	r0, #RESET_SKIP_VBVAR
> +	bne	vbar_done
> +
>  	/* Set V=0 in CP15 SCTLR register - for VBAR to point to vector */
>  	mrc	p15, 0, r2, c1, c0, 0	@ Read CP15 SCTLR Register
>  	bic	r2, #CR_V		@ V = 0
> @@ -61,10 +64,11 @@ reset:
>  	ldr	r2, =_start
>  	mcr	p15, 0, r2, c12, c0, 0	@Set VBAR
>  #endif
> -
> +vbar_done:
>  	/* the mask ROM code should have PLL and others stable */
>  #ifndef CONFIG_SKIP_LOWLEVEL_INIT
> -	bl	cpu_init_cp15
> +	teq	r0, #RESET_SKIP_CP15
> +	bleq	cpu_init_cp15
>  	bl	cpu_init_crit
>  #endif
>  
> @@ -88,11 +92,12 @@ ENDPROC(c_runtime_cpu_setup)
>  
>  /*************************************************************************
>   *
> - * void save_boot_params(u32 r2, u32 r1, u32 r2, u32 r3)
> + * u32 save_boot_params(u32 r2, u32 r1, u32 r2, u32 r3)
>   *	__attribute__((weak));
>   *
>   * Stack pointer is not yet initialized at this moment
>   * Don't save anything to stack even if compiled with -O0
> + * Return flags - see RESET_... in system.h
>   *
>   *************************************************************************/
>  ENTRY(save_boot_params)
> diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
> index 89f2294..98e49a7 100644
> --- a/arch/arm/include/asm/system.h
> +++ b/arch/arm/include/asm/system.h
> @@ -140,8 +140,23 @@ void flush_l3_cache(void);
>   */
>  #define __asmeq(x, y)  ".ifnc " x "," y " ; .err ; .endif\n\t"
>  
> +/* Control bits for reset processing */
> +#define RESET_SKIP_VBVAR	(1 << 0)	/* Skip vector address setup */
> +#define RESET_SKIP_CP15		(1 << 1)	/* Skip CP15 setup */
> +
>  #ifndef __ASSEMBLY__
>  
> +/**
> + * save_boot_params() - Save boot parameters before starting reset sequence
> + *
> + * @r0:		Value of r0
> + * @r1:		Value of r1
> + * @r2:		Value of r2
> + * @r3:		Value of r3
> + * @return reset flags (see RESET_... above)
> + */
> +u32 save_boot_params(u32 r0, u32 r1, u32 r2, u32 r3);
> +
>  #define isb() __asm__ __volatile__ ("" : : : "memory")
>  
>  #define nop() __asm__ __volatile__("mov\tr0,r0\t@ nop\n\t");
> -- 
> 2.2.0.rc0.207.ga3a616c
> 



Amicalement,
-- 
Albert.