dt-bindings: irqchip: Introduce TISCI Interrupt router bindings

Add the DT binding documentation for Interrupt router driver.
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt

+Texas Instruments K3 Interrupt Router
+=====================================
+
+The Interrupt Router (INTR) module provides a mechanism to mux M
+interrupt inputs to N interrupt outputs, where all M inputs are selectable
+to be driven per N output. An Interrupt Router can either handle edge triggered
+or level triggered interrupts and that is fixed in hardware.
+
+                                 Interrupt Router
+                             +----------------------+
+                             |  Inputs     Outputs  |
+        +-------+            | +------+    +-----+  |
+        | GPIO  |----------->| | irq0 |    |  0  |  |       Host IRQ
+        +-------+            | +------+    +-----+  |      controller
+                             |    .           .     |      +-------+
+        +-------+            |    .           .     |----->|  IRQ  |
+        | INTA  |----------->|    .           .     |      +-------+
+        +-------+            |    .        +-----+  |
+                             | +------+    |  N  |  |
+                             | | irqM |    +-----+  |
+                             | +------+             |
+                             |                      |
+                             +----------------------+
+
+There is one register per output (MUXCNTL_N) that controls the selection.
+Configuration of these MUXCNTL_N registers is done by a system controller
+(like the Device Memory and Security Controller on K3 AM654 SoC). System
+controller will keep track of the used and unused registers within the Router.
+Driver should request the system controller to get the range of GIC IRQs
+assigned to the requesting hosts. It is the drivers responsibility to keep
+track of Host IRQs.
+
+Communication between the host processor running an OS and the system
+controller happens through a protocol called TI System Control Interface
+(TISCI protocol). For more details refer:
+Documentation/devicetree/bindings/arm/keystone/ti,sci.txt
+
+TISCI Interrupt Router Node:
+----------------------------
+Required Properties:
+- compatible:		Must be "ti,sci-intr".
+- ti,intr-trigger-type:	Should be one of the following:
+			1: If intr supports edge triggered interrupts.
+			4: If intr supports level triggered interrupts.
+- interrupt-controller:	Identifies the node as an interrupt controller
+- #interrupt-cells:	Specifies the number of cells needed to encode an
+			interrupt source. The value should be 2.
+			First cell should contain the TISCI device ID of source
+			Second cell should contain the interrupt source offset
+			within the device.
+- ti,sci:		Phandle to TI-SCI compatible System controller node.
+- ti,sci-dst-id:	TISCI device ID of the destination IRQ controller.
+- ti,sci-rm-range-girq:	Array of TISCI subtype ids representing the host irqs
+			assigned to this interrupt router. Each subtype id
+			corresponds to a range of host irqs.
+
+For more details on TISCI IRQ resource management refer:
+http://downloads.ti.com/tisci/esd/latest/2_tisci_msgs/rm/rm_irq.html
+
+Example:
+--------
+The following example demonstrates both interrupt router node and the consumer
+node(main gpio) on the AM654 SoC:
+
+main_intr: interrupt-controller0 {
+	compatible = "ti,sci-intr";
+	ti,intr-trigger-type = <1>;
+	interrupt-controller;
+	interrupt-parent = <&gic500>;
+	#interrupt-cells = <2>;
+	ti,sci = <&dmsc>;
+	ti,sci-dst-id = <56>;
+	ti,sci-rm-range-girq = <0x1>;
+};
+
+main_gpio0: gpio@600000 {
+	...
+	interrupt-parent = <&main_intr>;
+	interrupts = <57 256>, <57 257>, <57 258>,
+		     <57 259>, <57 260>, <57 261>;
+	...
+};

MAINTAINERS

@@ -15349,6 +15349,7 @@ F:	Documentation/devicetree/bindings/reset/ti,sci-reset.txt
 F:	Documentation/devicetree/bindings/clock/ti,sci-clk.txt
 F:	drivers/clk/keystone/sci-clk.c
 F:	drivers/reset/reset-ti-sci.c
+F:	Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt
 
 Texas Instruments ASoC drivers
 M:	Peter Ujfalusi <peter.ujfalusi@ti.com>