linux-kernel - Re: [PATCH v2 1/4] dt-bindings: Add cros-ec Type C port driver

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Date:   Tue, 11 Feb 2020 11:28:16 +0100
From:   Enric Balletbo i Serra <enric.balletbo@...labora.com>
To:     Prashant Malani <pmalani@...omium.org>,
        linux-kernel@...r.kernel.org
Cc:     heikki.krogerus@...el.com, bleung@...omium.org,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Guenter Roeck <groeck@...omium.org>,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v2 1/4] dt-bindings: Add cros-ec Type C port driver

Hi Prashant,

On 7/2/20 21:37, Prashant Malani wrote:
> Some Chrome OS devices with Embedded Controllers (EC) can read and
> modify Type C port state.
> 
> Add an entry in the DT Bindings documentation that lists out the logical
> device and describes the relevant port information, to be used by the
> corresponding driver.
> 
> Signed-off-by: Prashant Malani <pmalani@...omium.org>
> ---
> 
> Changes in v2:
> - No changes. Patch first introduced in v2 of series.
> 
>  .../bindings/chrome/google,cros-ec-typec.yaml | 77 +++++++++++++++++++
>  1 file changed, 77 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/chrome/google,cros-ec-typec.yaml
> 
> diff --git a/Documentation/devicetree/bindings/chrome/google,cros-ec-typec.yaml b/Documentation/devicetree/bindings/chrome/google,cros-ec-typec.yaml
> new file mode 100644
> index 00000000000000..46ebcbe76db3c2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/chrome/google,cros-ec-typec.yaml
> @@ -0,0 +1,77 @@
> +# SPDX-License-Identifier: GPL-2.0

I think that Google is fine with the dual licensing here. Would be good if this
can be (GPL-2.0-only OR BSD-2-Clause)

> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/chrome/google,cros-ec-typec.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Google Chrome OS EC(Embedded Controller) Type C port driver.
> +
> +maintainers:
> +  - Benson Leung <bleung@...omium.org>
> +  - Prashant Malani <pmalani@...omium.org>
> +
> +description:
> +  Chrome OS devices have an Embedded Controller(EC) which has access to
> +  Type C port state. This node is intended to allow the host to read and
> +  control the Type C ports. The node for this device should be under a
> +  cros-ec node like google,cros-ec-spi.
> +
> +properties:
> +  compatible:
> +    const: google,cros-ec-typec
> +
> +  port:
> +    description: A node that represents a physical Type C port on the
> +      device.
> +    type: object
> +    properties:
> +      port-number:
> +        description: The number used by the Chrome OS EC to identify
> +          this type C port.
> +        $ref: /schemas/types.yaml#/definitions/uint32

Any range of values allowed? 0 is okay?

> +      power-role:

Sorry if this question is silly, aren't this and below properties the same as
provided by usb-connector?  Can't this be usb-c-connector?

Documentation/devicetree/bindings/connector/usb-connector.txt

> +        description: Determines the power role that the Type C port will
> +          adopt.
> +        oneOf:
> +          - items:
> +            - const: sink
> +            - const: source
> +            - const: dual
> +      data-role:
> +        description: Determines the data role that the Type C port will
> +          adopt.
> +        oneOf:
> +          - items:
> +            - const: host
> +            - const: device
> +            - const: dual
> +      try-power-role:
> +        description: Determines the preferred power role of the Type C port.
> +        oneOf:
> +          - items:
> +            - const: sink
> +            - const: source
> +            - const: dual
> +
> +    required:
> +      - port-number
> +      - power-role
> +      - data-role
> +      - try-power-role
> +
> +required:
> +  - compatible
> +  - port
> +
> +examples:
> +  - |+

Rob can confirm, but I think is a good practice add the parent node, so add the
cros-ec-spi node here?

> +    typec {
> +      compatible = "google,cros-ec-typec";
> +
> +      port@0 {

You can run:

  make dt_binding_check DT_SCHEMA_FILES=<...>/chrome/google,cros-ec-typec.yaml

And you'll get an error:

 typec: 'port' is a required property

> +        port-number = <0>;
> +        power-role = "dual";
> +        data-role = "dual";
> +        try-power-role = "source";
> +      };
> +    };
> 
Thanks,

 Enric