On 25.02.2022 11:03:44, Bastian Krause wrote:
> Activating the field return configuration returns a locked-down board
> (nearly) to its open state. In order to burn the FIELD_RETURN fuse, the
> CSF must contain a specific unlock command with the device's UID.
> 
> Signed-off-by: Bastian Krause <bst@pengutronix.de>
> ---
>  .../include/mach/habv4-imx6-gencsf-template.h        | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/arch/arm/mach-imx/include/mach/habv4-imx6-gencsf-template.h b/arch/arm/mach-imx/include/mach/habv4-imx6-gencsf-template.h
> index a60b485292..45da2981cb 100644
> --- a/arch/arm/mach-imx/include/mach/habv4-imx6-gencsf-template.h
> +++ b/arch/arm/mach-imx/include/mach/habv4-imx6-gencsf-template.h
> @@ -39,6 +39,18 @@ hab Engine = SETUP_HABV4_ENGINE
>  hab Features = SETUP_HABV4_FEATURES
>  #endif
>  
> +/*
> +// allow fusing FIELD_RETURN
> +// # ocotp0.permanent_write_enable=1
> +// # mw -l -d /dev/imx-ocotp 0xb8 0x1
> +hab [Unlock]
> +hab Engine = OCOTP
> +hab Features = FIELD RETURN
> +// device-specific UID:
> +// $ dd if=/sys/bus/nvmem/devices/imx-ocotp0/nvmem bs=4 skip=1 count=2 status=none | hexdump -ve '1/1 "0x%.2x, "' | sed 's/, $//'
> +hab UID = 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08

You probably want to comment this all out in the template...

> +*/
> +
>  hab [Install Key]
>  /* verification key index in key store (0, 2...4) */
>  hab Verification index = 0
> -- 
> 2.30.2
> 
>

Marc

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