Re: [PATCH v2 2/2] schemas: Add a schema for binman

[Alper Nebi Yasak <alpernebiyasak@gmail.com>]

On 2023-07-20 22:56 +03:00, Simon Glass wrote:
> With this version I have done with a generic name, in this case 'data',
> as suggested by Alper Nebi Yasak. This may be controversial, but we may
> as well have the dicussion now. I assume that there are no other
> ongoing attempts to define the layout of firmware in devicetree.
> 
> Signed-off-by: Simon Glass <sjg@chromium.org>
> ---
> 
> Changes in v2:
> - Reworked significantly based on Alper's comments
> 
>  dtschema/schemas/firmware/binman/entry.yaml | 80 +++++++++++++++++++++
>  dtschema/schemas/firmware/image.yaml        | 77 ++++++++++++++++++++
>  2 files changed, 157 insertions(+)
>  create mode 100644 dtschema/schemas/firmware/binman/entry.yaml
>  create mode 100644 dtschema/schemas/firmware/image.yaml
> 
> diff --git a/dtschema/schemas/firmware/binman/entry.yaml b/dtschema/schemas/firmware/binman/entry.yaml
> new file mode 100644
> index 0000000..d50f96d
> --- /dev/null
> +++ b/dtschema/schemas/firmware/binman/entry.yaml
> @@ -0,0 +1,80 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +# Copyright 2023 Google LLC
> +
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/firmware/image/entry.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Image entry
> +
> +maintainers:
> +  - Simon Glass <sjg@chromium.org>
> +
> +description: |
> +  The entry node specifies a single entry in the firmware image.
> +
> +  Entries have a specific type, such as "u-boot" or "atf-bl31". This is provided
> +  using compatible = "data,<type>".
> +
> +  Note: This definition is intended to be hierarchical, so that entries can
> +  appear in other entries. Schema for that is TBD.
> +
> +properties:
> +  $nodename:
> +    pattern: "^[-a-z]+(-[0-9]+)?$"
> +
> +  compatible:
> +    $ref: /schemas/types.yaml#/definitions/string
> +
> +  offset:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: |
> +      Provides the offset of this entry from the start of its parent section.
> +
> +      This may be omitted in the description provided by Binman, in which case
> +      the value is calculated as part of image packing.
> +
> +  size:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    description: |
> +      Provides the size of this entry in bytes.
> +
> +      This may be omitted in the description provided by Binman, in which case
> +      the value is calculated as part of image packing.

So AFAIU, binman will take none/one/both of "offset" and "size" as
inputs and will pass them to the output unmodified, instead adding a
"reg" pair of their calculated final values?

Is there a schema-computational way to ensure that "reg" has to contain
the same values as "offset" and "size"? Or is that not a restriction at
all and "reg" overrides the others?

> +
> +  reg:
> +    description: |
> +      Defines the offset and size of this entry, with reference to its parent
> +      image / section.
> +
> +      Note This is typically omitted in the description provided to Binman,
> +      since the value is calculated as part of image packing. Separate
> +      properties are provided for the size and offset of an entry, so that it is
> +      easy to specify none, one or both. The `reg` property is the only one that
> +      needs to be looked at once the image has been built.
> +

Do we not need a $ref for "reg"? Is there anything applicable?

BTW, I'm not that familiar with device-tree interpretation, I
occasionally saw 'reg' being used as an <offset size> pair, and was
mostly just asking if it's appropriate.

(Also TIL "ranges", and I'm imagining ranges = <0 $size 4G-$size 4G>; as
an end-at-4gb replacement/generalization :P, but I know, later, later.)

> +required:
> +  - compatible
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    firmware {
> +      image {
> +        compatible = "data,image";
> +        #address-cells = <1>;
> +        $size-cells = <1>;
> +
> +        u-boot@0 {
> +          compatible = "data,u-boot";
> +          reg = <0 0xa0000>;
> +        };
> +
> +        atf-bl31@0x100000 {
> +          compatible = "data,atf-bl31";
> +          reg = <0x100000 0x20000>;
> +        };
> +      };
> +    };
> diff --git a/dtschema/schemas/firmware/image.yaml b/dtschema/schemas/firmware/image.yaml
> new file mode 100644
> index 0000000..949b067
> --- /dev/null
> +++ b/dtschema/schemas/firmware/image.yaml
> @@ -0,0 +1,77 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +# Copyright 2023 Google LLC
> +
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/firmware/image.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Binman firmware layout
> +
> +maintainers:
> +  - Simon Glass <sjg@chromium.org>
> +
> +description: |
> +  The image node provides a layout for firmware, used when packaging firmware
> +  from multiple projects. For now it just supports a very simple set of
> +  features, as a starting point for discussion.
> +
> +  The Binman tool processes this node to produce a final image which can be
> +  loaded into suitable storage device. Documentation is at:
> +
> +  https://u-boot.readthedocs.io/en/latest/develop/package/binman.html
> +
> +  The current image-description format is here:
> +
> +  https://u-boot.readthedocs.io/en/latest/develop/package/binman.html#image-description-format
> +
> +  It is desirable to reference the image from the storage-device node, perhaps
> +  using an image-desc property:
> +
> +    spiflash@0 {
> +      compatible = "spidev", "jedec,spi-nor";
> +      image-desc = <&image>;

Bikeshedding, but maybe "layout" or "data,layout" would be nicer.

> +    };
> +
> +  Note that the intention is to change Binman to use whatever schema is agreed
> +  here.
> +
> +properties:
> +  $nodename:
> +    const: binman

Doesn't match the example, and I guess you mean "^[-a-z]+(-[0-9]+)?$"
like the entry one.

> +
> +  compatible:
> +    const: data,image
> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 1
> +
> +required:
> +  - compatible
> +  - "#address-cell"
> +  - "#size-cells"
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    firmware {
> +      image {
> +        compatible = "data,image";
> +        #address-cells = <1>;
> +        $size-cells = <1>;
> +
> +        u-boot@0 {
> +          compatible = "data,u-boot";
> +          reg = <0 0xa0000>;
> +        };
> +
> +        atf-bl31@0x100000 {
> +          compatible = "data,atf-bl31";
> +          reg = <0x100000 0x20000>;
> +        };
> +      };
> +    };