devicetree: bindings: net: Add bindings doc for Sunplus SP7021.

Add bindings documentation for Sunplus SP7021 SoC.
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NWells Lu <wellslutw@gmail.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>

Documentation/devicetree/bindings/net/sunplus,sp7021-emac.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+# Copyright (C) Sunplus Co., Ltd. 2021
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/sunplus,sp7021-emac.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Sunplus SP7021 Dual Ethernet MAC Device Tree Bindings
+
+maintainers:
+  - Wells Lu <wellslutw@gmail.com>
+
+description: |
+  Sunplus SP7021 dual 10M/100M Ethernet MAC controller.
+  Device node of the controller has following properties.
+
+properties:
+  compatible:
+    const: sunplus,sp7021-emac
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  resets:
+    maxItems: 1
+
+  ethernet-ports:
+    type: object
+    description: Ethernet ports to PHY
+
+    properties:
+      "#address-cells":
+        const: 1
+
+      "#size-cells":
+        const: 0
+
+    patternProperties:
+      "^port@[0-1]$":
+        type: object
+        description: Port to PHY
+
+        properties:
+          reg:
+            minimum: 0
+            maximum: 1
+
+          phy-handle:
+            maxItems: 1
+
+          phy-mode:
+            maxItems: 1
+
+          nvmem-cells:
+            items:
+              - description: nvmem cell address of MAC address
+
+          nvmem-cell-names:
+            description: names corresponding to the nvmem cells
+            items:
+              - const: mac-address
+
+        required:
+          - reg
+          - phy-handle
+          - phy-mode
+          - nvmem-cells
+          - nvmem-cell-names
+
+  mdio:
+    $ref: mdio.yaml#
+    unevaluatedProperties: false
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - resets
+  - pinctrl-0
+  - pinctrl-names
+  - ethernet-ports
+  - mdio
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    ethernet@9c108000 {
+        compatible = "sunplus,sp7021-emac";
+        reg = <0x9c108000 0x400>;
+        interrupt-parent = <&intc>;
+        interrupts = <66 IRQ_TYPE_LEVEL_HIGH>;
+        clocks = <&clkc 0xa7>;
+        resets = <&rstc 0x97>;
+        pinctrl-0 = <&emac_demo_board_v3_pins>;
+        pinctrl-names = "default";
+
+        ethernet-ports {
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            port@0 {
+                reg = <0>;
+                phy-handle = <&eth_phy0>;
+                phy-mode = "rmii";
+                nvmem-cells = <&mac_addr0>;
+                nvmem-cell-names = "mac-address";
+            };
+
+            port@1 {
+                reg = <1>;
+                phy-handle = <&eth_phy1>;
+                phy-mode = "rmii";
+                nvmem-cells = <&mac_addr1>;
+                nvmem-cell-names = "mac-address";
+            };
+        };
+
+        mdio {
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            eth_phy0: ethernet-phy@0 {
+                reg = <0>;
+            };
+
+            eth_phy1: ethernet-phy@1 {
+                reg = <1>;
+            };
+        };
+    };
+...

MAINTAINERS

@@ -18908,6 +18908,13 @@ L:	netdev@vger.kernel.org
 S:	Maintained
 F:	drivers/net/ethernet/dlink/sundance.c
 
+SUNPLUS ETHERNET DRIVER
+M:	Wells Lu <wellslutw@gmail.com>
+L:	netdev@vger.kernel.org
+S:	Maintained
+W:	https://sunplus.atlassian.net/wiki/spaces/doc/overview
+F:	Documentation/devicetree/bindings/net/sunplus,sp7021-emac.yaml
+
 SUNPLUS OCOTP DRIVER
 M:	Vincent Shih <vincent.sunplus@gmail.com>
 S:	Maintained