* ARC-HS Interrupt Distribution Unit

  This optional 2nd level interrupt controller can be used in SMP configurations for
  dynamic IRQ routing, load balancing of common/external IRQs towards core intc.

Properties:

- compatible: "snps,archs-idu-intc"
- interrupt-controller: This is an interrupt controller.
- interrupt-parent: <reference to parent core intc>
- #interrupt-cells: Must be <1>.

  Value of the cell specifies the "common" IRQ from peripheral to IDU. Number N
  of the particular interrupt line of IDU corresponds to the line N+24 of the
  core interrupt controller.

  intc accessed via the special ARC AUX register interface, hence "reg" property
  is not specified.

Example:
	core_intc: core-interrupt-controller {
		compatible = "snps,archs-intc";
		interrupt-controller;
		#interrupt-cells = <1>;
	};

	idu_intc: idu-interrupt-controller {
		compatible = "snps,archs-idu-intc";
		interrupt-controller;
		interrupt-parent = <&core_intc>;
		#interrupt-cells = <1>;
	};

	some_device: serial@c0fc1000 {
		interrupt-parent = <&idu_intc>;
		interrupts = <0>;	/* upstream idu IRQ #24 */
	};