Documentation/bindings: phy: document the Marvell comphy driver

The Marvell Armada 7K/8K SoCs contains an hardware block called COMPHY
that provides a number of shared PHYs used by various interfaces in the
SoC: network, SATA, PCIe, etc. This Device Tree binding allows to
describe this COMPHY hardware block.
Signed-off-by: NAntoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/phy/phy-mvebu-comphy.txt

+mvebu comphy driver
+-------------------
+
+A comphy controller can be found on Marvell Armada 7k/8k on the CP110. It
+provides a number of shared PHYs used by various interfaces (network, sata,
+usb, PCIe...).
+
+Required properties:
+
+- compatible: should be "marvell,comphy-cp110"
+- reg: should contain the comphy register location and length.
+- marvell,system-controller: should contain a phandle to the
+                             system controller node.
+- #address-cells: should be 1.
+- #size-cells: should be 0.
+
+A sub-node is required for each comphy lane provided by the comphy.
+
+Required properties (child nodes):
+
+- reg: comphy lane number.
+- #phy-cells : from the generic phy bindings, must be 1. Defines the
+               input port to use for a given comphy lane.
+
+Example:
+
+	cpm_comphy: phy@120000 {
+		compatible = "marvell,comphy-cp110";
+		reg = <0x120000 0x6000>;
+		marvell,system-controller = <&cpm_syscon0>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		cpm_comphy0: phy@0 {
+			reg = <0>;
+			#phy-cells = <1>;
+		};
+
+		cpm_comphy1: phy@1 {
+			reg = <1>;
+			#phy-cells = <1>;
+		};
+	};