net: dsa: add tag protocol definition and binding

Added tag protocol definition and binding. Also introduced
zephyr,dsa-port compatible for future tag protocol driver Kconfig
dependency checking.

Updated existed dts.

Signed-off-by: Yangbo Lu <[email protected]>

Author: yangbolu1991

dts/arm/nxp/nxp_rt118x.dtsi

@@ -9,6 +9,7 @@
 #include <dt-bindings/i2c/i2c.h>
 #include <zephyr/dt-bindings/adc/adc.h>
 #include <zephyr/dt-bindings/pwm/pwm.h>
+#include <zephyr/dt-bindings/ethernet/dsa_tag_proto.h>
 
 / {
 	aliases {
@@ -663,30 +664,36 @@
 			#size-cells = <0>;
 
 			switch_port0: switch_port@0 {
+				compatible = "zephyr,dsa-port";
 				reg = <0>;
 				status = "disabled";
 			};
 
 			switch_port1: switch_port@1 {
+				compatible = "zephyr,dsa-port";
 				reg = <1>;
 				status = "disabled";
 			};
 
 			switch_port2: switch_port@2 {
+				compatible = "zephyr,dsa-port";
 				reg = <2>;
 				status = "disabled";
 			};
 
 			switch_port3: switch_port@3 {
+				compatible = "zephyr,dsa-port";
 				reg = <3>;
 				status = "disabled";
 			};
 
 			/* Internal port */
 			switch_port4: switch_port@4 {
+				compatible = "zephyr,dsa-port";
 				reg = <4>;
 				ethernet = <&enetc_psi1>;
 				phy-connection-type = "internal";
+				dsa-tag-protocol = <DSA_TAG_PROTO_NOTAG>;
 				status = "disabled";
 			};
 		};

dts/bindings/dsa/dsa.yaml

@@ -4,7 +4,9 @@
 description: DSA Device
 
 child-binding:
-  description: Properties of slave port
+  description: Properties of port
+
+  compatible: "zephyr,dsa-port"
 
   include:
     - name: pinctrl-device.yaml
@@ -25,3 +27,8 @@ child-binding:
       description:
         A phandle to a valid Ethernet device node. This host
         device is what the switch port is connected to.
+    dsa-tag-protocol:
+      type: int
+      description:
+        Tag protocol the switch using. The <zephyr/dt-bindings/ethernet/dsa_tag_proto.h>
+        which provides macros should be included to use.

include/zephyr/dt-bindings/ethernet/dsa_tag_proto.h

@@ -0,0 +1,14 @@
+/*
+ * Copyright 2025 NXP
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_DT_BINDINGS_DSA_TAG_PROTO_H_
+#define ZEPHYR_INCLUDE_DT_BINDINGS_DSA_TAG_PROTO_H_
+
+/* No switch tag protocol supported */
+#define DSA_TAG_PROTO_NOTAG	0
+/* NXP NETC switch tag protocol */
+#define DSA_TAG_PROTO_NETC	1
+
+#endif /* ZEPHYR_INCLUDE_DT_BINDINGS_DSA_TAG_PROTO_H_ */