Re: [PATCH v4 1/2] dt-bindings: mtd: partitions: Document new dynamic-partition nodes

Rob Herring
2022-06-01T21:07:06Z

On Thu, May 19, 2022 at 01:32:57AM +0200, Ansuel Smith wrote:
> Document new dynamic-partition nodes used to provide an OF node for
> partition registred at runtime by parsers. This is required for nvmem
> system to declare and detect nvmem-cells.
>
> With these special partitions, the reg / offset is not required.
> The label binding is used to match the partition allocated by the
> parser at runtime and the parser will provide reg and offset of the mtd.
>
> NVMEM will use the data from the parser and provide the NVMEM cells
> declared in the DTS, "connecting" the dynamic partition with a
> static declaration of cells in them.
>
> Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
> ---
> .../mtd/partitions/dynamic-partition.yaml | 57 +++++++++++++++++++
> .../mtd/partitions/qcom,smem-part.yaml | 4 ++
> 2 files changed, 61 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/mtd/partitions/dynamic-partition.yaml
>
> diff --git a/Documentation/devicetree/bindings/mtd/partitions/dynamic-partition.yaml b/Documentation/devicetree/bindings/mtd/partitions/dynamic-partition.yaml
> new file mode 100644
> index 000000000000..f57d7b9cae7f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/partitions/dynamic-partition.yaml
> @@ -0,0 +1,57 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/mtd/partitions/dynamic-partition.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Dynamic Partition
> +
> +description: |
> + This binding describes a single flash partition that is dynamically allocated
> + by a dedicated parser that is not a fixed-partition parser.
> +
> + Each child of the parser partition node is then compared and if a match with
> + the provided label is found then the OF node is assigned.
> +
> + These special partition definition can be used to give a dynamic partition
> + an OF node to declare NVMEM cells. An example is declaring the partition
> + label and all the NVMEM cells in it. The parser will detect the correct reg
> + and offset and the NVMEM will register the cells in it based on the data
> + extracted by the parser.
> +
> +maintainers:
> + - Ansuel Smith <ansuelsmth@gmail.com>
> +
> +properties:
> + label:
> + description: The label / name for the partition assigned by the parser at
> + runtime. This is needed for sybsystem like NVMEM to define cells and

typo

> + register with this OF node.
> +
> +required:
> + - label
> +
> +additionalProperties: true
> +
> +examples:
> + - |
> + flash {
> + partitions {
> + compatible = "qcom,smem-part";
> +
> + partition-art {
> + compatible = "nvmem-cells";
> + #address-cells = <1>;
> + #size-cells = <1>;
> + label = "0:art";
> +
> + macaddr_art_0: macaddr@0 {
> + reg = <0x0 0x6>;
> + };
> +
> + macaddr_art_6: macaddr@6 {
> + reg = <0x6 0x6>;
> + };

There's a problem with the schema structure for this which is a common
problem where we have parent and child nodes with parent defined
properties in the child nodes (label in this case). The issue is that
there is not a single schema applied to the child node which contains
all possible properties sub-node names. This is necessary to check for
extra, undocumented properties using unevaluatedProperties. The creation
of spi-periphera-props.yaml is an example of how to address this. I
suspect that all the partition schemas may need similar restructuring.

The nvmem-cells schema may happen to already have 'label', so it happens
to work (that and unevaluatedProperties is probably missing in places).

Given this schema is really just one property which is already
documented for 'partition' nodes, all we really need is to say is if
'reg' is not present, then 'label' is required:

if:
not:
required: [ reg ]
then:
required: [ label ]

> + };
> + };
> + };
> diff --git a/Documentation/devicetree/bindings/mtd/partitions/qcom,smem-part.yaml b/Documentation/devicetree/bindings/mtd/partitions/qcom,smem-part.yaml
> index cf3f8c1e035d..b6fa25949fe2 100644
> --- a/Documentation/devicetree/bindings/mtd/partitions/qcom,smem-part.yaml
> +++ b/Documentation/devicetree/bindings/mtd/partitions/qcom,smem-part.yaml
> @@ -19,6 +19,10 @@ properties:
> compatible:
> const: qcom,smem-part
>
> +patternProperties:
> + "^partition-[0-9a-z]+$":
> + $ref: dynamic-partition.yaml#
> +
> required:
> - compatible
>
> --
> 2.34.1
>
>