irqchip: s3c24xx: add devicetree support

Add the necessary code to initialize the interrupt controller
thru devicetree data using the irqchip infrastructure.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

Documentation/devicetree/bindings/interrupt-controller/samsung,s3c24xx-irq.txt

@@ -0,0 +1,53 @@
+Samsung S3C24XX Interrupt Controllers
+
+The S3C24XX SoCs contain a custom set of interrupt controllers providing a
+varying number of interrupt sources. The set consists of a main- and sub-
+controller and on newer SoCs even a second main controller.
+
+Required properties:
+- compatible: Compatible property value should be "samsung,s3c2410-irq"
+  for machines before s3c2416 and "samsung,s3c2416-irq" for s3c2416 and later.
+
+- reg: Physical base address of the controller and length of memory mapped
+  region.
+
+- interrupt-controller : Identifies the node as an interrupt controller
+
+- #interrupt-cells : Specifies the number of cells needed to encode an
+  interrupt source. The value shall be 4 and interrupt descriptor shall
+  have the following format:
+      <ctrl_num parent_irq ctrl_irq type>
+
+  ctrl_num contains the controller to use:
+      - 0 ... main controller
+      - 1 ... sub controller
+      - 2 ... second main controller on s3c2416 and s3c2450
+  parent_irq contains the parent bit in the main controller and will be
+             ignored in main controllers
+  ctrl_irq contains the interrupt bit of the controller
+  type contains the trigger type to use
+
+Example:
+
+	interrupt-controller@4a000000 {
+		compatible = "samsung,s3c2410-irq";
+		reg = <0x4a000000 0x100>;
+		interrupt-controller;
+		#interrupt-cells=<4>;
+	};
+
+	[...]
+
+	serial@50000000 {
+		compatible = "samsung,s3c2410-uart";
+		reg = <0x50000000 0x4000>;
+		interrupt-parent = <&subintc>;
+		interrupts = <1 28 0 4>, <1 28 1 4>;
+	};
+
+	rtc@57000000 {
+		compatible = "samsung,s3c2410-rtc";
+		reg = <0x57000000 0x100>;
+		interrupt-parent = <&intc>;
+		interrupts = <0 30 0 3>, <0 8 0 3>;
+	};