dt-bindings: Add devicetree bindings

Add snapshot of device tree bindings from keystone common kernel, branch
"android-mainline-keystone-qcom-release" at c4c12103f9c0 ("Snap for 9228065
from e32903b9a63bb558df8b803b076619c53c16baad to
android-mainline-keystone-qcom-release").

Change-Id: I7682079615cbd9f29340a5c1f2a1d84ec441a1f1
Signed-off-by: Melody Olvera <quic_molvera@quicinc.com>

bindings/interrupt-controller/arm,versatile-fpga-irq.txt

@@ -0,0 +1,36 @@
+* ARM Versatile FPGA interrupt controller
+
+One or more FPGA IRQ controllers can be synthesized in an ARM reference board
+such as the Integrator or Versatile family. The output of these different
+controllers are OR:ed together and fed to the CPU tile's IRQ input. Each
+instance can handle up to 32 interrupts.
+
+Required properties:
+- compatible: "arm,versatile-fpga-irq" or "oxsemi,ox810se-rps-irq"
+- interrupt-controller: Identifies the node as an interrupt controller
+- #interrupt-cells: The number of cells to define the interrupts.  Must be 1
+  as the FPGA IRQ controller has no configuration options for interrupt
+  sources.  The cell is a u32 and defines the interrupt number.
+- reg: The register bank for the FPGA interrupt controller.
+- clear-mask: a u32 number representing the mask written to clear all IRQs
+  on the controller at boot for example.
+- valid-mask: a u32 number representing a bit mask determining which of
+  the interrupts are valid. Unconnected/unused lines are set to 0, and
+  the system till not make it possible for devices to request these
+  interrupts.
+
+Example:
+
+pic: pic@14000000 {
+        compatible = "arm,versatile-fpga-irq";
+        #interrupt-cells = <1>;
+        interrupt-controller;
+        reg = <0x14000000 0x100>;
+        clear-mask = <0xffffffff>;
+        valid-mask = <0x003fffff>;
+};
+
+Optional properties:
+- interrupts: if the FPGA IRQ controller is cascaded, i.e. if its IRQ
+  output is simply connected to the input of another IRQ controller,
+  then the parent IRQ shall be specified in this property.