linux-kernel - Re: [PATCH v3 4/6] dt-bindings: nvmem: add YAML schema for the sl28 vpd layout

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Date:   Thu, 10 Nov 2022 13:31:08 -0600
From:   Rob Herring <robh@...nel.org>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Krzysztof Kozlowski <krzk+dt@...nel.org>,
        devicetree@...r.kernel.org,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        linux-kernel@...r.kernel.org,
        Robert Marko <robert.marko@...tura.hr>,
        Luka Perkov <luka.perkov@...tura.hr>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Michael Walle <michael@...le.cc>,
        linux-arm-kernel@...ts.infradead.org,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Christian Eggers <ceggers@...i.de>,
        Cory Tusar <cory.tusar@...1solutions.com>
Subject: Re: [PATCH v3 4/6] dt-bindings: nvmem: add YAML schema for the sl28
 vpd layout

On Thu, Nov 10, 2022 at 06:38:55PM +0100, Miquel Raynal wrote:
> Hi Rob,
> 
> robh@...nel.org wrote on Thu, 10 Nov 2022 07:49:18 -0600:
> 
> > On Fri, Nov 04, 2022 at 05:38:31PM +0100, Miquel Raynal wrote:
> > > From: Michael Walle <michael@...le.cc>
> > > 
> > > Add a schema for the NVMEM layout on Kontron's sl28 boards.
> > > 
> > > Signed-off-by: Michael Walle <michael@...le.cc>
> > > Signed-off-by: Miquel Raynal <miquel.raynal@...tlin.com>
> > > ---
> > >  .../nvmem/layouts/kontron,sl28-vpd.yaml       | 60 +++++++++++++++++++
> > >  .../bindings/nvmem/layouts/nvmem-layout.yaml  |  3 +
> > >  2 files changed, 63 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/nvmem/layouts/kontron,sl28-vpd.yaml
> > > 
> > > diff --git a/Documentation/devicetree/bindings/nvmem/layouts/kontron,sl28-vpd.yaml b/Documentation/devicetree/bindings/nvmem/layouts/kontron,sl28-vpd.yaml
> > > new file mode 100644
> > > index 000000000000..44088c8b4153
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/nvmem/layouts/kontron,sl28-vpd.yaml
> > > @@ -0,0 +1,60 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/nvmem/layouts/kontron,sl28-vpd.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: NVMEM layout of the Kontron SMARC-sAL28 vital product data
> > > +
> > > +maintainers:
> > > +  - Michael Walle <michael@...le.cc>
> > > +
> > > +description:
> > > +  The vital product data (VPD) of the sl28 boards contains a serial
> > > +  number and a base MAC address. The actual MAC addresses for the
> > > +  on-board ethernet devices are derived from this base MAC address by
> > > +  adding an offset.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: kontron,sl28-vpd
> > > +
> > > +  serial-number:
> > > +    type: object
> > > +    description: The board's serial number
> > > +
> > > +  base-mac-address:
> > > +    type: object
> > > +    description:
> > > +      Base MAC address for all on-module network interfaces. The first
> > > +      argument of the phandle will be treated as an offset.
> > > +
> > > +    properties:
> > > +      "#nvmem-cell-cells":
> > > +        const: 1
> > > +
> > > +    additionalProperties: false
> > > +
> > > +required:
> > > +  - compatible
> > > +
> > > +additionalProperties: false
> > > +
> > > +examples:
> > > +  - |
> > > +      otp-1 {
> > > +          compatible = "user-otp";
> > > +
> > > +          nvmem-layout {
> > > +              compatible = "kontron,sl28-vpd";
> > > +
> > > +              serial_number: serial-number {
> > > +              };
> > > +
> > > +              base_mac_address: base-mac-address {
> > > +                  #nvmem-cell-cells = <1>;
> > > +              };
> > > +          };
> > > +      };
> > > +
> > > +...
> > > diff --git a/Documentation/devicetree/bindings/nvmem/layouts/nvmem-layout.yaml b/Documentation/devicetree/bindings/nvmem/layouts/nvmem-layout.yaml
> > > index ecc7c37cbc1f..f64ea2fa362d 100644
> > > --- a/Documentation/devicetree/bindings/nvmem/layouts/nvmem-layout.yaml
> > > +++ b/Documentation/devicetree/bindings/nvmem/layouts/nvmem-layout.yaml
> > > @@ -17,6 +17,9 @@ description: |
> > >    define and might require dynamic reading of the NVMEM device in order to
> > >    perform their parsing. The nvmem-layout container is here to describe these.
> > >  
> > > +oneOf:
> > > +  - $ref: kontron,sl28-vpd.yaml  
> > 
> > This is the other way around from how we normally structure things. 
> > Normally, the specific schema would reference the common/base schema. 
> > This works, though you will be applying the schema twice. Once here and 
> > then by matching on compatible string. Not a big deal as that happens 
> > fairly often, but a 'select: false' in kontron,sl28-vpd.yaml would 
> > prevent that. This way does more to enforce the overall structure of 
> > nodes.
> 
> Oh right, I knew about the "select: false" thing, but I forgot it in
> the two layouts.
> 
> > The one downside I see with it this way is nvmem-layout can't ever have 
> > common properties defined without listing them in each layout schema.
> 
> Oh that's right, actually I solved it in the mtd dt-binding series with:
> 
> partitions.yaml:
> 
> 	oneOf:
> 	  - $ref: <parser>.yaml
> 
> 	generic-property:
> 	  $ref: something
> 	  min/max...: foo
> 
> <parser>.yaml:
> 	generic-property: true
> 
> But in this case, are the constraints provided by partitions.yaml on
> "generic-property" actually still enforced?

Yes, they are. 

Rob