net: ethernet: ixp4xx: Add DT bindings

This adds device tree bindings for the IXP4xx ethernet
controller with optional MDIO bridge.

Cc: Zoltan HERPAI <wigyori@uid0.hu>
Cc: Raylynn Knight <rayknight@me.com>
Cc: devicetree@vger.kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/intel,ixp4xx-ethernet.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# Copyright 2018 Linaro Ltd.
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/net/intel,ixp4xx-ethernet.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: Intel IXP4xx ethernet
+
+allOf:
+  - $ref: "ethernet-controller.yaml#"
+
+maintainers:
+  - Linus Walleij <linus.walleij@linaro.org>
+
+description: |
+  The Intel IXP4xx ethernet makes use of the IXP4xx NPE (Network
+  Processing Engine) and the IXP4xx Queue Manager to process
+  the ethernet frames. It can optionally contain an MDIO bus to
+  talk to PHYs.
+
+properties:
+  compatible:
+    const: intel,ixp4xx-ethernet
+
+  reg:
+    maxItems: 1
+    description: Ethernet MMIO address range
+
+  queue-rx:
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    maxItems: 1
+    description: phandle to the RX queue on the NPE
+
+  queue-txready:
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    maxItems: 1
+    description: phandle to the TX READY queue on the NPE
+
+  phy-mode: true
+
+  phy-handle: true
+
+  intel,npe-handle:
+    $ref: '/schemas/types.yaml#/definitions/phandle-array'
+    maxItems: 1
+    description: phandle to the NPE this ethernet instance is using
+      and the instance to use in the second cell
+
+  mdio:
+    type: object
+    $ref: "mdio.yaml#"
+    description: optional node for embedded MDIO controller
+
+required:
+  - compatible
+  - reg
+  - queue-rx
+  - queue-txready
+  - intel,npe-handle
+
+additionalProperties: false
+
+examples:
+  - |
+    npe: npe@c8006000 {
+      compatible = "intel,ixp4xx-network-processing-engine";
+      reg = <0xc8006000 0x1000>, <0xc8007000 0x1000>, <0xc8008000 0x1000>;
+    };
+
+    ethernet@c8009000 {
+      compatible = "intel,ixp4xx-ethernet";
+      reg = <0xc8009000 0x1000>;
+      status = "disabled";
+      queue-rx = <&qmgr 4>;
+      queue-txready = <&qmgr 21>;
+      intel,npe-handle = <&npe 1>;
+      phy-mode = "rgmii";
+      phy-handle = <&phy1>;
+    };
+
+    ethernet@c800c000 {
+      compatible = "intel,ixp4xx-ethernet";
+      reg = <0xc800c000 0x1000>;
+      status = "disabled";
+      queue-rx = <&qmgr 3>;
+      queue-txready = <&qmgr 20>;
+      intel,npe-handle = <&npe 2>;
+      phy-mode = "rgmii";
+      phy-handle = <&phy2>;
+
+      mdio {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        phy1: ethernet-phy@1 {
+          reg = <1>;
+        };
+        phy2: ethernet-phy@2 {
+          reg = <2>;
+        };
+      };
+    };