Quoting Rob Herring (2018-04-20 11:15:04)
> On Fri, Apr 20, 2018 at 11:47 AM, Stephen Boyd <sboyd@xxxxxxxxxx> wrote:
> > Quoting Rob Herring (2018-04-18 15:29:05)
> >> diff --git a/Documentation/devicetree/bindings/example-schema.yaml b/Documentation/devicetree/bindings/example-schema.yaml
> >> new file mode 100644
> >> index 000000000000..fe0a3bd1668e
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/example-schema.yaml
> >> @@ -0,0 +1,149 @@
> >> +
> >> + The end of the description is marked by indentation less than the first line
> >> + in the description.
> >> +
> >> +select: false
> >> + # 'select' is a schema applied to a DT node to determine if this binding
> >> + # schema should be applied to the node. It is optional and by default the
> >> + # possible compatible strings are extracted and used to match.
> >
> > Can we get a concrete example here?
>
> select: true
>
> :) Which is apply to every node.
>
> A better one is from the memory node schema ('$nodename' gets added :
>
> select:
> required: ["$nodename"]
> properties:
> $nodename:
> oneOf:
> - pattern: "^memory@[0-9a-f]*"
> - const: "memory" # 'memory' only allowed for selecting
>
>
> I expect the vast majority of device bindings will not use select at
> all and rely on compatible string matching.
Thanks! I was looking to see how the select syntax would work and this
shows one example nicely. I suppose another way would be to show how a
compatible string would be matched through select, even though it's
redundant.
Is there a way we can enforce node names through the schema too? For
example to enforce that a clock controller is called 'clock-controller'
or a spi master is called 'spi'.
>
> >> +
> >> +properties:
> > [...]
> >> +
> >> + interrupts:
> >> + # Either 1 or 2 interrupts can be present
> >> + minItems: 1
> >> + maxItems: 2
> >> + items:
> >> + - description: tx or combined interrupt
> >> + - description: rx interrupt
> >> +
> >> + description: |
> >
> > The '|' is needed to make yaml happy?
>
> Yes, this is simply how you do literal text blocks in yaml.
>
> We don't really need for this one really, but for the top-level
> 'description' we do. The long term intent is 'description' would be
> written in sphinx/rst and can be extracted into the DT spec (for
> common bindings). Grant has experimented with that some.
Ok. That sounds cool. Then we could embed links to datasheets and SVGs
too.
>
> >> + A variable number of interrupts warrants a description of what conditions
> >> + affect the number of interrupts. Otherwise, descriptions on standard
> >> + properties are not necessary.
> >> +
> >> + interrupt-names:
> >> + # minItems must be specified here because the default would be 2
> >> + minItems: 1
> >> + items:
> >> + - const: "tx irq"
> >> + - const: "rx irq"
> >> +
> >> + # Property names starting with '#' must be quoted
> >> + '#interrupt-cells':
> >> + # A simple case where the value must always be '2'.
> >> + # The core schema handles that this must be a single integer.
> >> + const: 2
> >> +
> >> + interrupt-controller: {}
> >
> > Does '{}' mean nothing to see here?
>
> Yes. It's just an empty schema that's always valid.
Could we include another schema to indicate that this is an interrupt
controller? I'm sort of asking for multi-schema inheritance.
>
> >> + foo-gpios:
> >> + maxItems: 1
> >> + description: A connection of the 'foo' gpio line.
> >> +
> >> + vendor,int-property:
> >> + description: Vendor specific properties must have a description
> >> + type: integer # A type is also required
> >> + enum: [2, 4, 6, 8, 10]
> >> +
> >> + vendor,bool-property:
> >> + description: Vendor specific properties must have a description
> >> + type: boolean
> >> +
> >> +required:
> >> + - compatible
> >> + - reg
> >> + - interrupts
> >> + - interrupt-controller
> >
> > Can the required or optional parts go under each property instead of
> > having a different section?
>
> No, because then it is not json-schema language.
>
> > Or does that make the schema parser
> > difficult to implement?
>
> Yes, because then we have to implement a schema parser.
:/
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