bindings: soc: ti: add documentation for k3 ringacc

The Ring Accelerator (RINGACC or RA) provides hardware acceleration to
enable straightforward passing of work between a producer and a consumer.
There is one RINGACC module per NAVSS on TI AM65x and j721e.

This patch introduces RINGACC device tree bindings.
Signed-off-by: NGrygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: NPeter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: NRob Herring <robh@kernel.org>
Tested-by: NKeerthy <j-keerthy@ti.com>
Signed-off-by: NSantosh Shilimkar <santosh.shilimkar@oracle.com>

Documentation/devicetree/bindings/soc/ti/k3-ringacc.txt

+* Texas Instruments K3 NavigatorSS Ring Accelerator
+
+The Ring Accelerator (RA) is a machine which converts read/write accesses
+from/to a constant address into corresponding read/write accesses from/to a
+circular data structure in memory. The RA eliminates the need for each DMA
+controller which needs to access ring elements from having to know the current
+state of the ring (base address, current offset). The DMA controller
+performs a read or write access to a specific address range (which maps to the
+source interface on the RA) and the RA replaces the address for the transaction
+with a new address which corresponds to the head or tail element of the ring
+(head for reads, tail for writes).
+
+The Ring Accelerator is a hardware module that is responsible for accelerating
+management of the packet queues. The K3 SoCs can have more than one RA instances
+
+Required properties:
+- compatible	: Must be "ti,am654-navss-ringacc";
+- reg		: Should contain register location and length of the following
+		  named register regions.
+- reg-names	: should be
+		  "rt" - The RA Ring Real-time Control/Status Registers
+		  "fifos" - The RA Queues Registers
+		  "proxy_gcfg" - The RA Proxy Global Config Registers
+		  "proxy_target" - The RA Proxy Datapath Registers
+- ti,num-rings	: Number of rings supported by RA
+- ti,sci-rm-range-gp-rings : TI-SCI RM subtype for GP ring range
+- ti,sci	: phandle on TI-SCI compatible System controller node
+- ti,sci-dev-id	: TI-SCI device id of the ring accelerator
+- msi-parent	: phandle for "ti,sci-inta" interrupt controller
+
+Optional properties:
+ -- ti,dma-ring-reset-quirk : enable ringacc / udma ring state interoperability
+		  issue software w/a
+
+Example:
+
+ringacc: ringacc@3c000000 {
+	compatible = "ti,am654-navss-ringacc";
+	reg =	<0x0 0x3c000000 0x0 0x400000>,
+		<0x0 0x38000000 0x0 0x400000>,
+		<0x0 0x31120000 0x0 0x100>,
+		<0x0 0x33000000 0x0 0x40000>;
+	reg-names = "rt", "fifos",
+		    "proxy_gcfg", "proxy_target";
+	ti,num-rings = <818>;
+	ti,sci-rm-range-gp-rings = <0x2>; /* GP ring range */
+	ti,dma-ring-reset-quirk;
+	ti,sci = <&dmsc>;
+	ti,sci-dev-id = <187>;
+	msi-parent = <&inta_main_udmass>;
+};
+
+client:
+
+dma_ipx: dma_ipx@<addr> {
+	...
+	ti,ringacc = <&ringacc>;
+	...
+}