[U-Boot] [PATCH 4/5] stm32mp1: Fixup the Linux DeviceTree with coprocessor information

[Suman Anna]

Hi Fabien,

On 10/9/19 10:36 AM, Fabien Dessenne wrote:
> When the coprocessor has been started, provide the context to Linux
> kernel so it can handle it:
> - update the coprocessor node of kernel DeviceTree with the
>   "early-booted" property.

Has this property been acked by DT maintainers at the kernel-level?
We have used something similar but moving away from it and instead just
relying on reading the hardware reset status in the kernel remoteproc
driver, and configuring the driver accordingly.

> - write the resource table address in a dedicated backup register.

Is this an actual register on the SoC or some block of memory dedicated
for sharing information from U-Boot to kernel?

We have the same problem and I am currently going with a
design-by-contract approach for early-booted usecases where I am
expecting the resource table to be placed at a specific location in
memory regions given to remoteproc.

regards
Suman

> 
> Signed-off-by: Fabien Dessenne <fabien.dessenne at st.com>
> ---
>  board/st/stm32mp1/stm32mp1.c | 16 +++++++++++++---
>  1 file changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/board/st/stm32mp1/stm32mp1.c b/board/st/stm32mp1/stm32mp1.c
> index 18f9b84..8c669d0 100644
> --- a/board/st/stm32mp1/stm32mp1.c
> +++ b/board/st/stm32mp1/stm32mp1.c
> @@ -891,6 +891,7 @@ void board_mtdparts_default(const char **mtdids, const char **mtdparts)
>  #if defined(CONFIG_OF_BOARD_SETUP)
>  int ft_board_setup(void *blob, bd_t *bd)
>  {
> +	int off, id = 0; /* Copro id fixed to 0 as only one coproc on mp1 */
>  #ifdef CONFIG_FDT_FIXUP_PARTITIONS
>  	struct node_info nodes[] = {
>  		{ "st,stm32f469-qspi",		MTD_DEV_TYPE_NOR,  },
> @@ -899,6 +900,17 @@ int ft_board_setup(void *blob, bd_t *bd)
>  	fdt_fixup_mtdparts(blob, nodes, ARRAY_SIZE(nodes));
>  #endif
>  
> +	/* Update DT if coprocessor started */
> +	off = fdt_path_offset(blob, "/mlahb/m4 at 10000000");
> +	if (off > 0) {
> +		if (!rproc_is_running(id)) {
> +			fdt_setprop_empty(blob, off, "early-booted");
> +		} else {
> +			fdt_delprop(blob, off, "early-booted");
> +			writel(0, TAMP_COPRO_RSC_TBL_ADDRESS);
> +		}
> +	}
> +
>  	return 0;
>  }
>  #endif
> @@ -918,10 +930,8 @@ static void board_copro_image_process(ulong fw_image, size_t fw_size)
>  	printf("Load Remote Processor %d with data at addr=0x%08lx %u bytes:%s\n",
>  	       id, fw_image, fw_size, ret ? " Failed!" : " Success!");
>  
> -	if (!ret) {
> +	if (!ret)
>  		rproc_start(id);
> -		env_set("copro_state", "booted");
> -	}
>  }
>  
>  U_BOOT_FIT_LOADABLE_HANDLER(IH_TYPE_COPRO, board_copro_image_process);
>