dt-bindings: nvmem: add YAML schema for the sl28 vpd layout

Add a schema for the NVMEM layout on Kontron's sl28 boards.
Signed-off-by: NMichael Walle <michael@walle.cc>
Signed-off-by: NMiquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NSrinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20221118063932.6418-12-srinivas.kandagatla@linaro.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/nvmem/layouts/kontron,sl28-vpd.yaml

+# 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@walle.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.
+
+select: false
+
+properties:
+  compatible:
+    const: kontron,sl28-vpd
+
+  serial-number:
+    type: object
+    description: The board's serial number
+
+    additionalProperties: false
+
+  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>;
+              };
+          };
+      };
+
+...

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
+
 properties:
   compatible: true