[PATCH v7 usb-next 1/4] dt-bindings: usb: add the documentation for USB root-hub

@@ -0,0 +1,46 @@
+Generic USB root-hub Properties
+
+similar to the USB device bindings (documented in usb-device.txt from the
+current directory) this provides support for configuring the root-hub.
+
+Required properties:
+- compatible: should be at least one of "usb1d6b,3", "usb1d6b,2"
+- reg: must be 0.
+- address-cells: must be 1
+- size-cells: must be 0
+
+Required sub-nodes:
+a sub-node per actual USB port is required. each sub-node supports the
+following properties:
+  Required properties:
+    - reg: the port number on the root-hub (mandatory)
+  Optional properties:
+    - phys: optional, from the *Generic PHY* bindings (mandatory needed
+      when phy-names is given)
+    - phy-names: optional, from the *Generic PHY* bindings; supported names
+      are "usb2-phy" or "usb3-phy"
+
+Example:
+	&usb1 {
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		roothub@0 {
+			compatible = "usb1d6b,3", "usb1d6b,2";
+			#address-cells = <1>;
+			#size-cells = <0>;
+			reg = <0>;
+
+			port@1 {
+				reg = <1>;
+				phys = <&usb2_phy1>, <&usb3_phy1>;
+				phy-names = "usb2-phy", "usb3-phy";
+			};
+
+			port@2 {
+				reg = <2>;
+				phys = <&usb2_phy2>, <&usb3_phy2>;
+				phy-names = "usb2-phy", "usb3-phy";
+			};
+		};
+	}

@@ -30,6 +30,13 @@ Optional properties:
   - usb3-lpm-capable: determines if platform is USB3 LPM capable
   - quirk-broken-port-ped: set if the controller has broken port disable mechanism
 
+sub-nodes:
+- optionally there can be a node for the root-hub, see usb-roothub.txt in the
+  current directory
+- one or more nodes with reg 1-31 for each port to which a device is connected.
+  See usb-device.txt in the current directory for more information.
+
+
 Example:
 	usb@f0931000 {
 		compatible = "generic-xhci";