Re: [RFC PATCH 3/4] dt-bindings: mtd: add OTP bindings

[Rob Herring <robh@kernel.org>]

On Mon, Mar 22, 2021 at 07:19:48PM +0100, Michael Walle wrote:
> Flash devices can have one-time-programmable regions. Add a nvmem
> binding so they can be used as a nvmem provider.
> 
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---
>  .../devicetree/bindings/mtd/mtd.yaml          | 71 +++++++++++++++++++
>  1 file changed, 71 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mtd/mtd.yaml b/Documentation/devicetree/bindings/mtd/mtd.yaml
> index 321259aab0f6..2b852f91a6a9 100644
> --- a/Documentation/devicetree/bindings/mtd/mtd.yaml
> +++ b/Documentation/devicetree/bindings/mtd/mtd.yaml
> @@ -21,6 +21,25 @@ properties:
>        based name) in order to ease flash device identification and/or
>        describe what they are used for.
>  
> +patternProperties:
> +  "^otp(-[0-9]+)?":

Needs '$' on the end.

> +    type: object
> +    $ref: ../nvmem/nvmem.yaml#
> +
> +    description: |
> +      An OTP memory region. Some flashes provide a one-time-programmable
> +      memory whose content can either be programmed by a user or is already
> +      pre-programmed by the factory. Some flashes might provide both.
> +
> +    properties:
> +      compatible:
> +        enum:
> +          - mtd-user-otp
> +          - mtd-factory-otp
> +
> +    required:
> +      - compatible
> +
>  additionalProperties: true
>  
>  examples:
> @@ -36,4 +55,56 @@ examples:
>          };
>      };
>  
> +  - |
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        flash@0 {
> +            reg = <0>;
> +            compatible = "some,flash";

Soon (in linux-next, but off by default) this will be a warning for 
undocumented compatible string. Use a real device.

> +
> +            otp {
> +                compatible = "mtd-user-otp";
> +                #address-cells = <1>;
> +                #size-cells = <1>;
> +
> +                serial-number@0 {
> +                    reg = <0 16>;
> +                };
> +            };
> +        };
> +    };
> +
> +  - |
> +    spi {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        flash@0 {
> +            reg = <0>;
> +            compatible = "some,flash";
> +
> +            otp-1 {
> +                compatible = "mtd-factory-otp";
> +                #address-cells = <1>;
> +                #size-cells = <1>;
> +
> +                electronic-serial-number@0 {
> +                    reg = <0 8>;
> +                };
> +            };
> +
> +            otp-2 {
> +                compatible = "mtd-user-otp";
> +                #address-cells = <1>;
> +                #size-cells = <1>;
> +
> +                mac-address@0 {
> +                    reg = <0 6>;
> +                };
> +            };
> +        };
> +    };

The 2nd example is a superset of the 1st, so drop the first one.

Rob