[U-Boot] [PATCH v4 10/18] rockchip: boot0 hook: support early return for RK3188/RK3066-style BROM

[Andy Yan]

Hi Philipp:

On 2017年10月07日 03:28, Philipp Tomsich wrote:
> Some Rockchip BROM versions (e.g. the RK3188 and RK3066) first read 1KB data
> from NAND into SRAM and executes it. Then, following a return to bootrom, the
> BROM loads additional code to SRAM (not overwriting the first block read) and
> reenters at the same address as the first time.
>
> To support booting either a TPL (on the RK3066) or SPL (on the RK3188) using
> this model of having to count entries, this commit adds code to the boot0
> hook to track the number of entries and handle them accordingly.
>
> Signed-off-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>
> Signed-off-by: Paweł Jarosz <paweljarosz3691 at gmail.com>
> ---
>
> Changes in v4: None
> Changes in v3: None
> Changes in v2: None
>
>   arch/arm/include/asm/arch-rockchip/boot0.h | 24 ++++++++++++++++++------
>   arch/arm/mach-rockchip/Kconfig             | 28 ++++++++++++++++++++++++++++
>   2 files changed, 46 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/include/asm/arch-rockchip/boot0.h b/arch/arm/include/asm/arch-rockchip/boot0.h
> index f7c6146..06091d0 100644
> --- a/arch/arm/include/asm/arch-rockchip/boot0.h
> +++ b/arch/arm/include/asm/arch-rockchip/boot0.h
> @@ -19,12 +19,24 @@
>   	 * beginning of the executable.	 However, as we want to keep
>   	 * this generic and make it applicable to builds that are like
>   	 * the RK3368 (TPL needs this, SPL doesn't) or the RK3399 (no
> -	 * TPL, but extra space needed in the SPL), we simply repeat
> -	 * the 'b reset' with the expectation that the first one will
> -	 * be overwritten, if this is the first stage contained in the
> -	 * final image created with mkimage)...
> +	 * TPL, but extra space needed in the SPL), we simply insert
> +	 * a branch-to-next-instruction-word with the expectation that
> +	 * the first one may be overwritten, if this is the first stage
> +	 * contained in the final image created with mkimage)...
>   	 */
> -	b reset	 /* may be overwritten --- should be 'nop' or a 'b reset' */
> +	b 1f	 /* if overwritten, entry-address is at the next word */
> +1:
> +#endif
> +#if CONFIG_IS_ENABLED(ROCKCHIP_EARLYRETURN_TO_BROM)
> +	adr     r3, entry_counter
> +	ldr	r0, [r3]
> +	cmp	r0, #1           /* check if entry_counter == 1 */
> +	beq	reset            /* regular bootup */
> +	add     r0, #1
> +	str	r0, [r3]         /* increment the entry_counter in memory */
> +	bx	lr               /* return to bootrom */
     This seems not work on rk3188, When I track the code flow with DS-5, I
found the entry_counter always be zero when we run here from 
bootrom(even it is set to 1 before return to bootrom), so it return to 
bootrom again and again.
> +entry_counter:
> +	.word   0
>   #endif
>   	b reset
>   #if !defined(CONFIG_ARM64)
> @@ -32,7 +44,7 @@
>   	 * For armv7, the addr '_start' will used as vector start address
>   	 * and write to VBAR register, which needs to aligned to 0x20.
>   	 */
> -	.align(5)
> +	.align(5), 0x0
>   _start:
>   	ARM_VECTORS
>   #endif
> diff --git a/arch/arm/mach-rockchip/Kconfig b/arch/arm/mach-rockchip/Kconfig
> index 31e9864..d59a1d5 100644
> --- a/arch/arm/mach-rockchip/Kconfig
> +++ b/arch/arm/mach-rockchip/Kconfig
> @@ -158,6 +158,34 @@ config ROCKCHIP_SPL_RESERVE_IRAM
>   config ROCKCHIP_BROM_HELPER
>   	bool
>   
> +config SPL_ROCKCHIP_EARLYRETURN_TO_BROM
> +        bool "SPL requires early-return (for RK3188-style BROM) to BROM"
> +	depends on SPL && ENABLE_ARM_SOC_BOOT0_HOOK
> +	help
> +	  Some Rockchip BROM variants (e.g. on the RK3188) load the
> +	  first stage in segments and enter multiple times. E.g. on
> +	  the RK3188, the first 1KB of the first stage are loaded
> +	  first and entered; after returning to the BROM, the
> +	  remainder of the first stage is loaded, but the BROM
> +	  re-enters at the same address/to the same code as previously.
> +
> +	  This enables support code in the BOOT0 hook for the SPL stage
> +	  to allow multiple entries.
> +
> +config TPL_ROCKCHIP_EARLYRETURN_TO_BROM
> +        bool "TPL requires early-return (for RK3188-style BROM) to BROM"
> +	depends on TPL && ENABLE_ARM_SOC_BOOT0_HOOK
> +	help
> +	  Some Rockchip BROM variants (e.g. on the RK3188) load the
> +	  first stage in segments and enter multiple times. E.g. on
> +	  the RK3188, the first 1KB of the first stage are loaded
> +	  first and entered; after returning to the BROM, the
> +	  remainder of the first stage is loaded, but the BROM
> +	  re-enters at the same address/to the same code as previously.
> +
> +	  This enables support code in the BOOT0 hook for the TPL stage
> +	  to allow multiple entries.
> +
>   config SPL_MMC_SUPPORT
>   	default y if !SPL_ROCKCHIP_BACK_TO_BROM
>