Documentation: dt: soc: add Keystone Navigator DMA bindings

Keystone Navigator DMA Controller

This document explains the device tree bindings for the packet dma

on keystone devices. The Keystone Navigator DMA driver sets up the dma

channels and flows for the QMSS(Queue Manager SubSystem) who triggers

the actual data movements across clients using destination queues. Every

client modules like  NETCP(Network Coprocessor), SRIO(Serial Rapid IO),

CRYPTO Engines etc has its own instance of dma hardware. QMSS has also

an internal packet DMA module which is used as an infrastructure DMA

with zero copy.

Navigator DMA cloud layout:

	------------------

	| Navigator DMAs |

	------------------

		|

		|-> DMA instance #0

		|

		|-> DMA instance #1

			.

			.

		|

		|-> DMA instance #n

Navigator DMA properties:

Required properties:

 - compatible: Should be "ti,keystone-navigator-dma"

 - clocks: phandle to dma instances clocks. The clock handles can be as

	many as the dma instances. The order should be maintained as per

	the dma instances.

 - ti,navigator-cloud-address: Should contain base address for the multi-core

	navigator cloud and number of addresses depends on SOC integration

	configuration.. Navigator cloud global address needs to be programmed

	into DMA and the DMA uses it as the physical addresses to reach queue

	managers. Note that these addresses though points to queue managers,

	they are relevant only from DMA perspective. The QMSS may not choose to

	use them since it has a different address space view to reach all

	its components.

DMA instance properties:

Required properties:

 - reg: Should contain register location and length of the following dma

	register regions. Register regions should be specified in the following

	order.

	- Global control register region (global).

	- Tx DMA channel configuration register region (txchan).

	- Rx DMA channel configuration register region (rxchan).

	- Tx DMA channel Scheduler configuration register region (txsched).

	- Rx DMA flow configuration register region (rxflow).

Optional properties:

 - reg-names: Names for the register regions.

 - ti,enable-all: Enable all DMA channels vs clients opening specific channels

	what they need. This property is useful for the userspace fast path

	case where the linux drivers enables the channels used by userland

	stack.

 - ti,loop-back: To loopback Tx streaming I/F to Rx streaming I/F. Used for

	      infrastructure transfers.

 - ti,rx-retry-timeout: Number of dma cycles to wait before retry on buffer

		     starvation.

Example:

	knav_dmas: knav_dmas@0 {

		compatible = "ti,keystone-navigator-dma";

		clocks = <&papllclk>, <&clkxge>;

		#address-cells = <1>;

		#size-cells = <1>;

		ranges;

		ti,navigator-cloud-address = <0x23a80000 0x23a90000

					   0x23aa0000 0x23ab0000>;

		dma_gbe: dma_gbe@0 {

			reg = <0x2004000 0x100>,

				  <0x2004400 0x120>,

				  <0x2004800 0x300>,

				  <0x2004c00 0x120>,

				  <0x2005000 0x400>;

			reg-names = "global", "txchan", "rxchan",

					"txsched", "rxflow";

		};

		dma_xgbe: dma_xgbe@0 {

			reg = <0x2fa1000 0x100>,

				<0x2fa1400 0x200>,

				<0x2fa1800 0x200>,

				<0x2fa1c00 0x200>,

				<0x2fa2000 0x400>;

			reg-names = "global", "txchan", "rxchan",

					"txsched", "rxflow";

		};

	};

Navigator DMA client:

Required properties:

 - ti,navigator-dmas: List of one or more DMA specifiers, each consisting of

			- A phandle pointing to DMA instance node

			- A DMA channel number as a phandle arg.

 - ti,navigator-dma-names: Contains dma channel name for each DMA specifier in

			the 'ti,navigator-dmas' property.

Example:

	netcp: netcp@2090000 {

		..

		ti,navigator-dmas = <&dma_gbe 22>,

				<&dma_gbe 23>,

				<&dma_gbe 8>;

		ti,navigator-dma-names = "netrx0", "netrx1", "nettx";

		..

	};