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

[Simon Glass]

Hi Alper,

On Thu, 3 Aug 2023 at 14:29, Alper Nebi Yasak <alpernebiyasak at gmail.com>
wrote:
>
> 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 at 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 at 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?

Probably we can do that in Python. But I don't expect people would use
'reg' in the image description as it is a pain.

>
> > +
> > +  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?

Not from what I can tell. I think it is special?

>
> 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.)

Right, that is an x86-ism but is pretty helpful as it is otherwise widely
confusing to deal with these addresses.

>
> > +required:
> > +  - compatible
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    firmware {
> > +      image {
> > +        compatible = "data,image";
> > +        #address-cells = <1>;
> > +        $size-cells = <1>;
> > +
> > +        u-boot at 0 {
> > +          compatible = "data,u-boot";
> > +          reg = <0 0xa0000>;
> > +        };
> > +
> > +        atf-bl31 at 0x100000 {
> > +          compatible = "data,atf-bl31";
> > +          reg = <0x100000 0x20000>;
> > +        };
> > +      };
> > +    };
> > diff --git a/dtschema/schemas/firmware/image.yaml
b/dtschema/schemas/firmware/image.yaml
> > new file mode 100644
> > index 0000000..949b067
> > --- /dev/null
> > +++ b/dtschema/schemas/firmware/image.yaml
> > @@ -0,0 +1,77 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +# Copyright 2023 Google LLC
> > +
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/firmware/image.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Binman firmware layout
> > +
> > +maintainers:
> > +  - Simon Glass <sjg at 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 at 0 {
> > +      compatible = "spidev", "jedec,spi-nor";
> > +      image-desc = <&image>;
>
> Bikeshedding, but maybe "layout" or "data,layout" would be nicer.

OK

>
> > +    };
> > +
> > +  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.

Right.

>
> > +
> > +  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 at 0 {
> > +          compatible = "data,u-boot";
> > +          reg = <0 0xa0000>;
> > +        };
> > +
> > +        atf-bl31 at 0x100000 {
> > +          compatible = "data,atf-bl31";
> > +          reg = <0x100000 0x20000>;
> > +        };
> > +      };
> > +    };

Regards,
Simon