dt-bindings: net: dsa: yt921x: Add Motorcomm YT921x switch support

The Motorcomm YT921x series is a family of Ethernet switches with up to
8 internal GbE PHYs and up to 2 GMACs.

Signed-off-by: David Yang <[e-mail]>
Reviewed-by: Krzysztof Kozlowski <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

Documentation/devicetree/bindings/net/dsa/motorcomm,yt921x.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/dsa/motorcomm,yt921x.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Motorcomm YT921x Ethernet switch family
+
+maintainers:
+  - David Yang <[e-mail]>
+
+description: |
+  The Motorcomm YT921x series is a family of Ethernet switches with up to 8
+  internal GbE PHYs and up to 2 GMACs, including:
+
+    - YT9215S / YT9215RB / YT9215SC: 5 GbE PHYs (Port 0-4) + 2 GMACs (Port 8-9)
+    - YT9213NB: 2 GbE PHYs (Port 1/3) + 1 GMAC (Port 9)
+    - YT9214NB: 2 GbE PHYs (Port 1/3) + 2 GMACs (Port 8-9)
+    - YT9218N: 8 GbE PHYs (Port 0-7)
+    - YT9218MB: 8 GbE PHYs (Port 0-7) + 2 GMACs (Port 8-9)
+
+  Any port can be used as the CPU port.
+
+properties:
+  compatible:
+    const: motorcomm,yt9215
+
+  reg:
+    enum: [0x0, 0x1d]
+
+  reset-gpios:
+    maxItems: 1
+
+  mdio:
+    $ref: /schemas/net/mdio.yaml#
+    unevaluatedProperties: false
+    description:
+      Internal MDIO bus for the internal GbE PHYs. PHY 0-7 are used for Port
+      0-7 respectively.
+
+  mdio-external:
+    $ref: /schemas/net/mdio.yaml#
+    unevaluatedProperties: false
+    description:
+      External MDIO bus to access external components. External PHYs for GMACs
+      (Port 8-9) are expected to be connected to the external MDIO bus in
+      vendor's reference design, but that is not a hard limitation from the
+      chip.
+
+required:
+  - compatible
+  - reg
+
+allOf:
+  - $ref: dsa.yaml#/$defs/ethernet-ports
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    mdio {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        switch@1d {
+            compatible = "motorcomm,yt9215";
+            /* default 0x1d, alternate 0x0 */
+            reg = <0x1d>;
+            reset-gpios = <&tlmm 39 GPIO_ACTIVE_LOW>;
+
+            mdio {
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                sw_phy0: phy@0 {
+                    reg = <0x0>;
+                };
+
+                sw_phy1: phy@1 {
+                    reg = <0x1>;
+                };
+
+                sw_phy2: phy@2 {
+                    reg = <0x2>;
+                };
+
+                sw_phy3: phy@3 {
+                    reg = <0x3>;
+                };
+
+                sw_phy4: phy@4 {
+                    reg = <0x4>;
+                };
+            };
+
+            mdio-external {
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                phy1: phy@b {
+                    reg = <0xb>;
+                };
+            };
+
+            ethernet-ports {
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                ethernet-port@0 {
+                    reg = <0>;
+                    label = "lan1";
+                    phy-mode = "internal";
+                    phy-handle = <&sw_phy0>;
+                };
+
+                ethernet-port@1 {
+                    reg = <1>;
+                    label = "lan2";
+                    phy-mode = "internal";
+                    phy-handle = <&sw_phy1>;
+                };
+
+                ethernet-port@2 {
+                    reg = <2>;
+                    label = "lan3";
+                    phy-mode = "internal";
+                    phy-handle = <&sw_phy2>;
+                };
+
+                ethernet-port@3 {
+                    reg = <3>;
+                    label = "lan4";
+                    phy-mode = "internal";
+                    phy-handle = <&sw_phy3>;
+                };
+
+                ethernet-port@4 {
+                    reg = <4>;
+                    label = "lan5";
+                    phy-mode = "internal";
+                    phy-handle = <&sw_phy4>;
+                };
+
+                /* CPU port */
+                ethernet-port@8 {
+                    reg = <8>;
+                    phy-mode = "2500base-x";
+                    ethernet = <&eth0>;
+
+                    fixed-link {
+                        speed = <2500>;
+                        full-duplex;
+                    };
+                };
+
+                /* if external phy is connected to a MAC */
+                ethernet-port@9 {
+                    reg = <9>;
+                    label = "wan";
+                    phy-mode = "rgmii-id";
+                    phy-handle = <&phy1>;
+                };
+            };
+        };
+    };