[PATCH 2/4] ARM: beaglebone: add helper init script for checking if BBBW

[Sascha Hauer]

On Mon, Jun 14, 2021 at 08:26:37AM +1000, Marc Reilly wrote:
> This adds a check against the eeprom contents to see if the board is a
> Beaglebone black wireless. (two bytes at offset 0x12 of eeprom will be
> "BW").
> If it is, the global board.variant is updated to "boneblackwireless"
> 
> Signed-off-by: Marc Reilly <marc at cpdesign.com.au>
> ---
>  .../defaultenv-beaglebone/data/bbb-eeprom-0x0C      |  1 +
>  .../defaultenv-beaglebone/init/check-bbb-type       | 13 +++++++++++++
>  2 files changed, 14 insertions(+)
>  create mode 100644 arch/arm/boards/beaglebone/defaultenv-beaglebone/data/bbb-eeprom-0x0C
>  create mode 100644 arch/arm/boards/beaglebone/defaultenv-beaglebone/init/check-bbb-type
> 
> diff --git a/arch/arm/boards/beaglebone/defaultenv-beaglebone/data/bbb-eeprom-0x0C b/arch/arm/boards/beaglebone/defaultenv-beaglebone/data/bbb-eeprom-0x0C
> new file mode 100644
> index 000000000..258b93951
> --- /dev/null
> +++ b/arch/arm/boards/beaglebone/defaultenv-beaglebone/data/bbb-eeprom-0x0C
> @@ -0,0 +1 @@
> +BW
> diff --git a/arch/arm/boards/beaglebone/defaultenv-beaglebone/init/check-bbb-type b/arch/arm/boards/beaglebone/defaultenv-beaglebone/init/check-bbb-type
> new file mode 100644
> index 000000000..b7c8b3683
> --- /dev/null
> +++ b/arch/arm/boards/beaglebone/defaultenv-beaglebone/init/check-bbb-type
> @@ -0,0 +1,13 @@
> +#!/bin/sh
> +
> +memcmp -b -s /dev/eeprom0 -d /env/data/bbb-eeprom-0x0C 0x0c 0x00 2
> +result=$?
> +echo $result
> +
> +if [ $result = 0 ]
> +then
> +        echo "Beaglebone Wireless detected"
> +        global.board.variant=boneblackwireless
> +else
> +        echo "Beaglebone Black (non-wireless) detected"
> +fi

I think it's worth doing this in C code. A good template for this is in
https://git.pengutronix.de/cgit/barebox/tree/arch/arm/boards/skov-imx6/board.c#n435
Here the board compatible is prepended with a more specific variant, for
the BBB this would be "ti,am335x-bone-black-wireless". With this
bootspec could pick the entry with the right devicetree without further
interventions.

Sascha

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