ARM: dt: Add binding for Tegra PMC

The Tegra PMC (Power Management Controller) interfaces with an external
PMU (Power Management Unit), and controls wake-up from sleep modes.

This initial binding is the bare minimum required to control the PMC's
inversion of the PMU's interrupt signal.
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Olof Johansson <olof@lixom.net>

Documentation/devicetree/bindings/arm/tegra/nvidia,tegra20-pmc.txt

+NVIDIA Tegra Power Management Controller (PMC)
+
+Properties:
+- name : Should be pmc
+- compatible : Should contain "nvidia,tegra<chip>-pmc".
+- reg : Offset and length of the register set for the device
+- nvidia,invert-interrupt : If present, inverts the PMU interrupt signal.
+  The PMU is an external Power Management Unit, whose interrupt output
+  signal is fed into the PMC. This signal is optionally inverted, and then
+  fed into the ARM GIC. The PMC is not involved in the detection or
+  handling of this interrupt signal, merely its inversion.
+
+Example:
+
+pmc@7000f400 {
+	compatible = "nvidia,tegra20-pmc";
+	reg = <0x7000e400 0x400>;
+	nvidia,invert-interrupt;
+};

arch/arm/boot/dts/tegra-harmony.dts

@@ -10,6 +10,10 @@ memory@0 {
 		reg = < 0x00000000 0x40000000 >;
 	};
 
+	pmc@7000f400 {
+		nvidia,invert-interrupt;
+	};
+
 	i2c@7000c000 {
 		clock-frequency = <400000>;
 

arch/arm/boot/dts/tegra20.dtsi

@@ -4,6 +4,11 @@ / {
 	compatible = "nvidia,tegra20";
 	interrupt-parent = <&intc>;
 
+	pmc@7000f400 {
+		compatible = "nvidia,tegra20-pmc";
+		reg = <0x7000e400 0x400>;
+	};
+
 	intc: interrupt-controller@50041000 {
 		compatible = "arm,cortex-a9-gic";
 		interrupt-controller;

arch/arm/boot/dts/tegra30.dtsi

@@ -4,6 +4,11 @@ / {
 	compatible = "nvidia,tegra30";
 	interrupt-parent = <&intc>;
 
+	pmc@7000f400 {
+		compatible = "nvidia,tegra20-pmc", "nvidia,tegra30-pmc";
+		reg = <0x7000e400 0x400>;
+	};
+
 	intc: interrupt-controller@50041000 {
 		compatible = "arm,cortex-a9-gic";
 		interrupt-controller;