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This version (04 Dec 2018 21:39) was approved by Michael Hennerich.

Table of Contents

Analog Device AXI-DMAC DMA Controller Linux Driver

Supported Devices

Description

The AXI DMAC is a high-speed, high-throughput, general purpose DMA controller intended to be used to transfer data between system memory and other peripherals like high-speed converters.

Features

  • Supports multiple interface types
    • AXI3/4 memory mapped
    • AXI4 Streaming
    • ADI FIFO interface
  • Zero-latency transfer switch-over architecture
    • Allows continuous high-speed streaming
  • Cyclic transfers
  • 2D transfers

Source Code

Status

Source Mainlined?
drivers/dma/dma-axi-dmac.c Yes

Files

Function File
driver drivers/dma/dma-axi-dmac.c
include include/dt-bindings/dma/axi-dmac.h
Documentation Documentation/devicetree/bindings/dma/adi,axi-dmac.txt

Example platform device initialization

The AXI-DMAC driver is a platform driver and can currently only be instantiated via device tree.

Required properties:

  • compatible: Must be “adi,axi-dmac-1.00.a”.
  • reg: Specification for the controllers memory mapped register map.
  • interrupts: Specification for the controllers interrupt.
  • clocks: Phandle and specifier to the controllers AXI interface clock
  • #dma-cells: Must be 1.

Required sub-nodes:

  • adi,channels: This sub-node must contain a sub-node for each DMA channel. For the channel sub-nodes the following bindings apply. They must match then configuration options of the peripheral as it was instantiated.

Required properties for adi,channels sub-node:

  • #size-cells: Must be 0
  • #address-cells: Must be 1

Required channel sub-node properties:

  • reg: Which channel this node refers to.
  • adi,length-width: Width of the DMA transfer length register.
  • adi,source-bus-width, adi,destination-bus-width: Width of the source or destination bus in bits.
  • adi,source-bus-type, adi,destination-bus-type: Type of the source or destination bus. Must be one of the following:
    • 0 (AXI_DMAC_TYPE_AXI_MM): Memory mapped AXI interface
    • 1 (AXI_DMAC_TYPE_AXI_STREAM): Streaming AXI interface
    • 2 (AXI_DMAC_TYPE_AXI_FIFO): FIFO interface

Optional channel properties:

  • adi,cyclic: Must be set if the channel supports hardware cyclic DMA transfers.
  • adi,2d: Must be set if the channel supports hardware 2D DMA transfers.

DMA clients connected to the AXI-DMAC DMA controller must use the format described in the dma.txt file using a one cell specifier. The value of the specifier refers to the DMA channel index.

Example: 

dma: dma@7c420000 {
	compatible = "adi,axi-dmac-1.00.a";
	reg = <0x7c420000 0x10000>;
	interrupts = <0 57 0>;
	clocks = <&clkc 16>;
	#dma-cells = <1>;

	adi,channels {
		#size-cells = <0>;
		#address-cells = <1>;

		dma-channel@0 {
			reg = <0>;
			adi,source-bus-width = <32>;
			adi,source-bus-type = <ADI_AXI_DMAC_TYPE_MM_AXI>;
			adi,destination-bus-width = <64>;
			adi,destination-bus-type = <ADI_AXI_DMAC_TYPE_FIFO>;
		};
	};
};

Enabling Linux driver support

Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”) 

Linux Kernel Configuration
	Device Drivers  --->
	<*>    DMA --->

            <*>   DMA Engine support  --->
	    [--snip--]
		<*>   Analog Devices AXI-DMAC DMA support
	    [--snip--]

More Information

resources/tools-software/linux-drivers/axi-dmac.txt · Last modified: 04 Dec 2018 21:39 by Michael Hennerich

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