dt-bindings: net: add Vertexcom MSE102x support

Add devicetree binding for the Vertexcom MSE102x Homeplug GreenPHY chip
as SPI device.
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/vertexcom-mse102x.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/net/vertexcom-mse102x.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: The Vertexcom MSE102x (SPI) Device Tree Bindings
+
+maintainers:
+  - Stefan Wahren <stefan.wahren@in-tech.com>
+
+description:
+  Vertexcom's MSE102x are a family of HomePlug GreenPHY chips.
+  They can be connected either via RGMII, RMII or SPI to a host CPU.
+
+  In order to use a MSE102x chip as SPI device, it must be defined as
+  a child of an SPI master device in the device tree.
+
+  More information can be found at
+    http://www.vertexcom.com/doc/MSE1022%20Product%20Brief.pdf
+
+allOf:
+  - $ref: ethernet-controller.yaml#
+
+properties:
+  compatible:
+    enum:
+      - vertexcom,mse1021
+      - vertexcom,mse1022
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  spi-cpha: true
+
+  spi-cpol: true
+
+  spi-max-frequency:
+    minimum: 6000000
+    maximum: 7142857
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - spi-cpha
+  - spi-cpol
+  - spi-max-frequency
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    spi0 {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        ethernet@0 {
+            compatible = "vertexcom,mse1021";
+            reg = <0>;
+            interrupt-parent = <&gpio>;
+            interrupts = <23 IRQ_TYPE_EDGE_RISING>;
+            spi-cpha;
+            spi-cpol;
+            spi-max-frequency = <7142857>;
+        };
+    };