firmware: ti_sci: Add support for Resoure Management at R5 SPL stage.

On J721e and J7200, MCU R5 core (boot master) itself would run Device
Manager (DM) Firmware and interact with TI Foundational Security (TIFS)
firmware to enable DMA and such other Resource Management (RM) services.
So, during R5 SPL stage there is no such RM service available and ti_sci
driver will have to directly interact with TIFS using DM to DMSC
channels to request RM resources.

Therefore add DT binding and driver for the same. This driver will
handle Resource Management services at R5 SPL stage.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Link: https://lore.kernel.org/r/20210607141753.28796-4-vigneshr@ti.com
diff --git a/doc/device-tree-bindings/firmware/ti,j721e-dm-sci.txt b/doc/device-tree-bindings/firmware/ti,j721e-dm-sci.txt
new file mode 100644
index 0000000..0217341
--- /dev/null
+++ b/doc/device-tree-bindings/firmware/ti,j721e-dm-sci.txt
@@ -0,0 +1,32 @@
+Bindings for Texas Instruments System Control Interface (TI-SCI) Message
+Protocol for Device Manager(DM) to TI Foundational Security(TIFS)
+Firmware communication
+
+Required properties:
+--------------------
+- compatible: should be "ti,j721e-dm-sci"
+- mbox-names:
+	"rx" - Mailbox corresponding to receive path
+	"tx" - Mailbox corresponding to transmit path
+
+- mboxes: Mailboxes corresponding to the mbox-names. Each value of the mboxes
+	  property should contain a phandle to the mailbox controller device
+	  node and an args specifier that will be the phandle to the intended
+	  sub-mailbox child node to be used for communication.
+
+- ti,host-id: Host ID to use for communication.
+
+Optional Properties:
+--------------------
+- ti,secure-host: If the host is defined as secure.
+
+Example:
+--------
+	dm_tifs: dm-tifs {
+		compatible = "ti,j721e-dm-sci";
+		ti,host-id = <3>;
+		ti,secure-host;
+		mbox-names = "rx", "tx";
+		mboxes= <&mcu_secproxy 21>,
+			<&mcu_secproxy 23>;
+	};