dt-bindings: Add documentation for mpm irqchip

Add documentation for mpm interrupt controller.

Change-Id: I00a6435f0402b5fb0c5c4c0c54c37edd8d7dfd74

bindings/interrupt-controller/qcom,mpm.txt

@@ -0,0 +1,72 @@
+QTI MPM interrupt controller
+MPM (MSM sleep Power Manager) is QTI's platform parent
+interrupt controller. It manages subsystem wakeups and
+resources during sleep. This driver marks the wakeup
+interrupts in APSS such that it monitors the interrupts
+when the system is asleep, wakes up the APSS when one
+of these interrupts occur and replays it to the subsystem
+interrupt controller after it becomes operational.
+
+Platform interrupt controller MPM is next in hierarchy,
+followed by others.
+
+This defines 2 interrupt controllers to monitor the
+interrupts when system is asleep:
+
+One to monitor the wakeup capable gic interrupts called
+wakegic.
+
+Properties:
+
+- compatible:
+	Usage: required
+	Value type: <string>
+	Definition: Should contain "qcom,mpm-gic" and the respective
+	target compatible flag from below ones.
+		"qcom,mpm-gic-holi"
+
+- interrupts:
+	Usage: required
+	Value type: <prop-encoded-array>
+	Definition: should specify the IRQ used by remote processor to
+	wakeup APSS.
+
+- interrupt-parent:
+	Usage: required
+	Value type: <phandle>
+	Definition: Specifies the interrupt parent necessary for
+	hierarchical domain to operate.
+
+- interrupt-controller:
+	Usage: required
+	Value type: <bool>
+	Definition: Identifies the node as an interrupt controller.
+
+- reg:
+	Usage: required
+	Value type: <prop-encoded-array>
+	Definition: Specifies the base physical address to trigger an
+	interrupt into remote processor.
+
+-reg-names:
+	Usage: required
+	Value type: <string>, <string>
+	Definition: Specifies the address field names.
+
+- qcom,num-mpm-irqs:
+	Usage: optional
+	Value type: <value>
+	Defination: Specifies the number of interrupts supported.
+
+Example:
+
+wakegic: wake-gic@7781b8 {
+	compatible = "qcom,mpm", "qcom,mpm-gic-holi";
+	interrupts = <GIC_SPI 171 IRQ_TYPE_EDGE_RISING>;
+	reg = <0x601d4 0x1000>,
+	    <0xb011008 0x4>;  /* MSM_APCS_GCC_BASE 4K */
+	reg-names = "vmpm", "ipc";
+	interrupt-controller;
+	interrupt-parent = <&intc>;
+	#interrupt-cells = <3>;
+};