1.2.1 Phandles

The phandle property assigns a unique numerical identifier to a node within the device tree. Nodes can reference each other using their respective phandle values.

Example:

clocks {
		slow_xtal: slow_xtal {
			compatible = "fixed-clock";
			#clock-cells = <0>;
		};
};
clk32k: clock-controller@fffffe50 {
				compatible = "microchip,sam9x60-sckc";
				reg = <0xfffffe50 0x4>;
				clocks = <&slow_xtal>;    //Phandle used 
				#clock-cells = <1>;
			};