dt-bindings: phy: Add documentation for NSP USB3 PHY

Add documentation for USB3 PHY available in Northstar plus SoC

Signed-off-by: Yendapally Reddy Dhananjaya Reddy <yendapally.reddy@broadcom.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

diff --git a/Documentation/devicetree/bindings/phy/brcm,nsp-usb3-phy.txt b/Documentation/devicetree/bindings/phy/brcm,nsp-usb3-phy.txt
new file mode 100644 (file)
index 0000000..e68ae5d
--- /dev/null
+++ b/Documentation/devicetree/bindings/phy/brcm,nsp-usb3-phy.txt
@@ -0,0 +1,39 @@
+Broadcom USB3 phy binding for northstar plus SoC
+The USB3 phy is internal to the SoC and is accessed using mdio interface.
+
+Required mdio bus properties:
+- reg: Should be 0x0 for SoC internal USB3 phy
+- #address-cells: must be 1
+- #size-cells: must be 0
+
+Required USB3 PHY properties:
+- compatible: should be "brcm,nsp-usb3-phy"
+- reg: USB3 Phy address on SoC internal MDIO bus and it should be 0x10.
+- usb3-ctrl-syscon: handler of syscon node defining physical address
+  of usb3 control register.
+- #phy-cells: must be 0
+
+Required usb3 control properties:
+- compatible: should be "brcm,nsp-usb3-ctrl"
+- reg: offset and length of the control registers
+
+Example:
+
+       mdio@0 {
+               reg = <0x0>;
+               #address-cells = <1>;
+               #size-cells = <0>;
+
+               usb3_phy: usb-phy@10 {
+                       compatible = "brcm,nsp-usb3-phy";
+                       reg = <0x10>;
+                       usb3-ctrl-syscon = <&usb3_ctrl>;
+                       #phy-cells = <0>;
+                       status = "disabled";
+               };
+       };
+
+       usb3_ctrl: syscon@104408 {
+               compatible = "brcm,nsp-usb3-ctrl", "syscon";
+               reg = <0x104408 0x3fc>;
+       };