irqchip: Add brcm, bcm6345-l1-intc device tree binding

Add device tree binding for the BCM6345 interrupt controller.

This controller is similar to the SMP-capable BCM7038 and
the BCM3380 but with packed interrupt registers.
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Acked-by: Rob Herring <robh@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: Jonas Gorski <jogo@openwrt.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc: devicetree@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11804/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Documentation/devicetree/bindings/interrupt-controller/brcm,bcm6345-l1-intc.txt

+Broadcom BCM6345-style Level 1 interrupt controller
+
+This block is a first level interrupt controller that is typically connected
+directly to one of the HW INT lines on each CPU.
+
+Key elements of the hardware design include:
+
+- 32, 64 or 128 incoming level IRQ lines
+
+- Most onchip peripherals are wired directly to an L1 input
+
+- A separate instance of the register set for each CPU, allowing individual
+  peripheral IRQs to be routed to any CPU
+
+- Contains one or more enable/status word pairs per CPU
+
+- No atomic set/clear operations
+
+- No polarity/level/edge settings
+
+- No FIFO or priority encoder logic; software is expected to read all
+  2-4 status words to determine which IRQs are pending
+
+Required properties:
+
+- compatible: should be "brcm,bcm<soc>-l1-intc", "brcm,bcm6345-l1-intc"
+- reg: specifies the base physical address and size of the registers;
+  the number of supported IRQs is inferred from the size argument
+- interrupt-controller: identifies the node as an interrupt controller
+- #interrupt-cells: specifies the number of cells needed to encode an interrupt
+  source, should be 1.
+- interrupt-parent: specifies the phandle to the parent interrupt controller(s)
+  this one is cascaded from
+- interrupts: specifies the interrupt line(s) in the interrupt-parent controller
+  node; valid values depend on the type of parent interrupt controller
+
+If multiple reg ranges and interrupt-parent entries are present on an SMP
+system, the driver will allow IRQ SMP affinity to be set up through the
+/proc/irq/ interface.  In the simplest possible configuration, only one
+reg range and one interrupt-parent is needed.
+
+The driver operates in native CPU endian by default, there is no support for
+specifying an alternative endianness.
+
+Example:
+
+periph_intc: interrupt-controller@10000000 {
+        compatible = "brcm,bcm63168-l1-intc", "brcm,bcm6345-l1-intc";
+        reg = <0x10000020 0x20>,
+              <0x10000040 0x20>;
+
+        interrupt-controller;
+        #interrupt-cells = <1>;
+
+        interrupt-parent = <&cpu_intc>;
+        interrupts = <2>, <3>;
+};