yaml schema and sub-nodes with vendor prefixes

[Lars-Peter Clausen <lars@metafoo.de>]

Hi,

I'm trying to convert Xilinx XADC devicetree bindings[1] description to 
yaml format. And I'm running into issue with describing a sub-node with 
a vendor prefix.

A typical devicetree entry for the XADC looks like

     xadc@43200000 {
         compatible = "xlnx,axi-xadc-1.00.a";

         xlnx,channels {
             #address-cells = <1>;
             #size-cells = <0>;
             channel@0 {
                 reg = <0>;
                 xlnx,bipolar;
             };
         };
     };

So there is the 'xlnx,channels' sub-node which contains a set of other 
nodes which represent the individual channels.

The way I'm trying to describe it in the yaml file is like

  xlnx,channels:
     description: Node containing all the channel nodes
     type: object
     properties:
       '#address-cells':
          const: 1
       '#size-cells':
          const: 0

     patternProperties:
       "^channel@([0-9]|1[0-6])$":
         type: object
         properties:
           reg:
             description: ...
           xlnx,bipolar:
             description: If set the channel is used in bipolar mode.
             type: boolean
         required:
           - reg
         additionalProperties: false

     required:
       - '#address-cells'
       - '#size-cells'
     additionalProperties: false

This now fails validation, presumably because there is no match in 
meta-schemas/vendor-props.yaml. If I drop the vendor prefix from the 
property name validation passes. I can also make validation pass by 
adding an arbitrary $ref property, but there is no 'node' type in 
types.yaml.

What's the best way to describe a node with a vendor prefix?

Thanks,

- Lars

[1] 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/iio/adc/xilinx-xadc.txt