Re: [PATCH] dt-bindings: firmware: coreboot: Convert to YAML

[Krzysztof Kozlowski]

On Tue, Nov 25, 2025 at 02:48:49PM +0800, Chen-Yu Tsai wrote:
> Convert the existing text binding to YAML.
> 
> The description has been change to reflect the possibility of coreboot
> inserting the node itself.
> 
> The example has been modified to compile and pass validation without
> any errors. A comment was added to note what the firmware actually
> emits.
> 
> Signed-off-by: Chen-Yu Tsai <wenst@xxxxxxxxxxxx>
> ---
>  .../devicetree/bindings/firmware/coreboot.txt | 33 ----------
>  .../bindings/firmware/coreboot.yaml           | 60 +++++++++++++++++++
>  2 files changed, 60 insertions(+), 33 deletions(-)
>  delete mode 100644 Documentation/devicetree/bindings/firmware/coreboot.txt
>  create mode 100644 Documentation/devicetree/bindings/firmware/coreboot.yaml
> 
> diff --git a/Documentation/devicetree/bindings/firmware/coreboot.txt b/Documentation/devicetree/bindings/firmware/coreboot.txt
> deleted file mode 100644
> index 4c955703cea8..000000000000
> --- a/Documentation/devicetree/bindings/firmware/coreboot.txt
> +++ /dev/null
> @@ -1,33 +0,0 @@
> -COREBOOT firmware information
> -
> -The device tree node to communicate the location of coreboot's memory-resident
> -bookkeeping structures to the kernel. Since coreboot itself cannot boot a
> -device-tree-based kernel (yet), this node needs to be inserted by a
> -second-stage bootloader (a coreboot "payload").
> -
> -Required properties:
> - - compatible: Should be "coreboot"
> - - reg: Address and length of the following two memory regions, in order:
> -	1.) The coreboot table. This is a list of variable-sized descriptors
> -	that contain various compile- and run-time generated firmware
> -	parameters. It is identified by the magic string "LBIO" in its first
> -	four bytes.
> -	See coreboot's src/commonlib/include/commonlib/coreboot_tables.h for
> -	details.
> -	2.) The CBMEM area. This is a downward-growing memory region used by
> -	coreboot to dynamically allocate data structures that remain resident.
> -	It may or may not include the coreboot table as one of its members. It
> -	is identified by a root node descriptor with the magic number
> -	0xc0389481 that resides in the topmost 8 bytes of the area.
> -	See coreboot's src/include/imd.h for details.
> -
> -Example:
> -	firmware {
> -		ranges;
> -
> -		coreboot {
> -			compatible = "coreboot";
> -			reg = <0xfdfea000 0x264>,
> -			      <0xfdfea000 0x16000>;
> -		}
> -	};
> diff --git a/Documentation/devicetree/bindings/firmware/coreboot.yaml b/Documentation/devicetree/bindings/firmware/coreboot.yaml
> new file mode 100644
> index 000000000000..568afd1abb92
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/firmware/coreboot.yaml
> @@ -0,0 +1,60 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/firmware/coreboot.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: COREBOOT firmware information

Coreboot

> +
> +maintainers:
> +  - Julius Werner <jwerner@xxxxxxxxxxxx>
> +
> +description:
> +  The device tree node to communicate the location of coreboot's
> +  memory-resident bookkeeping structures to the kernel. Coreboot's
> +  FIT image payload can insert the node into the device tree. If a
> +  second-stage bootloader (a coreboot "payload") is used, then it
> +  is responsible for inserting the node.
> +
> +properties:
> +  compatible:
> +    const: coreboot

Blank line (it is always here, there is no example without, which makes
me wonder which file you took as starting point)

> +  reg:
> +    description: Address and length of the following two memory regions

Drop description, redundant.

> +    items:
> +      - description:
> +          The coreboot table. This is a list of variable-sized descriptors
> +          that contain various compile- and run-time generated firmware
> +          parameters. It is identified by the magic string "LBIO" in its first
> +          four bytes.
> +
> +          See coreboot's src/commonlib/include/commonlib/coreboot_tables.h for
> +          details.
> +      - description:
> +          The CBMEM area. This is a downward-growing memory region used by
> +          coreboot to dynamically allocate data structures that remain resident.
> +          It may or may not include the coreboot table as one of its members. It
> +          is identified by a root node descriptor with the magic number
> +          0xc0389481 that resides in the topmost 8 bytes of the area.
> +
> +          See coreboot's src/include/imd.h for details.
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    firmware {
> +        #address-cells = <1>;
> +        #size-cells = <1>;
> +        ranges;
> +
> +        /* Firmware actually emits "coreboot" node without unit name */
> +        coreboot@fdfea000 {
> +            compatible = "coreboot";
> +            reg = <0xfdfea000 0x264>, <0xfdfea000 0x16000>;

That's the same address in both places, so the same one entry. You need
two distinctive addresses or binding needs changes to have only one item
as well.

Best regards,
Krzysztof