linux-kernel - Re: [PATCH 1/2] dt-bindings: power: syscon-reboot: Convert bindings to json-schema

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Message-ID: <CAJKOXPfO0yBzGFPvF_WwsGGJBZSBGMLsFi2CQ2Eg5RVfyfW3nA@mail.gmail.com>
Date:   Tue, 3 Sep 2019 09:46:49 +0200
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Sebastian Reichel <sre@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "open list:THERMAL" <linux-pm@...r.kernel.org>,
        devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] dt-bindings: power: syscon-reboot: Convert bindings
 to json-schema

On Tue, 3 Sep 2019 at 09:14, Rob Herring <robh+dt@...nel.org> wrote:
>
> On Mon, Sep 2, 2019 at 4:03 PM Krzysztof Kozlowski <krzk@...nel.org> wrote:
> >
> > Convert the Syscon reboot bindings to DT schema format using
> > json-schema.
> >
> > Signed-off-by: Krzysztof Kozlowski <krzk@...nel.org>
> > ---
> >  .../bindings/power/reset/syscon-reboot.txt    | 30 --------
> >  .../bindings/power/reset/syscon-reboot.yaml   | 68 +++++++++++++++++++
> >  2 files changed, 68 insertions(+), 30 deletions(-)
> >  delete mode 100644 Documentation/devicetree/bindings/power/reset/syscon-reboot.txt
> >  create mode 100644 Documentation/devicetree/bindings/power/reset/syscon-reboot.yaml
>
> > diff --git a/Documentation/devicetree/bindings/power/reset/syscon-reboot.yaml b/Documentation/devicetree/bindings/power/reset/syscon-reboot.yaml
> > new file mode 100644
> > index 000000000000..a583f3dc8ef4
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/power/reset/syscon-reboot.yaml
> > @@ -0,0 +1,68 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/power/reset/syscon-reboot.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Generic SYSCON mapped register reset driver
> > +
> > +maintainers:
> > +  - Sebastian Reichel <sre@...nel.org>
> > +
> > +description: |+
> > +  This is a generic reset driver using syscon to map the reset register.
> > +  The reset is generally performed with a write to the reset register
> > +  defined by the register map pointed by syscon reference plus the offset
> > +  with the value and mask defined in the reboot node.
> > +  Default will be little endian mode, 32 bit access only.
> > +
> > +properties:
> > +  compatible:
> > +    const: syscon-reboot
> > +
> > +  mask:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: Update only the register bits defined by the mask (32 bit).
> > +    maxItems: 1
>
> Drop this as that is already defined for uint32.
>
> It also doesn't actually work. The $ref has to be under an 'allOf' if
> you have additional schemas. A quirk of json-schema...
>
> > +
> > +  offset:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: Offset in the register map for the reboot register (in bytes).
> > +    maxItems: 1
> > +
> > +  regmap:
> > +    $ref: /schemas/types.yaml#/definitions/phandle
> > +    description: Phandle to the register map node.
> > +    maxItems: 1
> > +
> > +  value:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: The reset value written to the reboot register (32 bit access).
> > +    maxItems: 1
> > +
> > +required:
> > +  - compatible
> > +  - regmap
> > +  - offset
> > +
> > +allOf:
> > +  - if:
> > +      properties:
> > +        value:
> > +          not:
> > +            type: array
>
> I think you could make this a bit more readable with:
>
> if:
>   not:
>     required:
>       - value

I do not understand how does it work (value is not mentioned in the
required fields so why checking of it?)... but it works fine.

> However, if the tree is free of legacy usage, then you could just drop all this.

One of them - mask or value - has to be provided.

Thanks for review,
Kryzsztof