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  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept id="GUID-092D336A-155A-4F18-AAF7-92E08473700E" xml:lang="en"><title>DMA

Overview</title><shortdesc>Dynamic Memory Access (DMA) uses a controller to copy data between

memory locations, or between memory and peripherals with minimal involvement

from the CPU.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<section id="GUID-04298BEC-F064-40C4-9A8C-DFB15953C85B"><title>Purpose</title><p>Dynamic

Memory Access (DMA) channels allow you to copy data between memory locations,

or between memory and peripherals, with limited involvement from the CPU.

The transfer operation is performed by the DMA controller. </p><p>The DMA

Framework provides a simplified and unified access to DMA resources in a device.

Generic transfer parameters abstract the underlying DMA hardware for basic

services, and fine-grained control is still available for platform-specific

features. </p></section>

<section id="GUID-140D36E7-EFC1-4206-A563-417AAB6BCC1C"><title>Architecture</title><p><fig id="GUID-0EF82751-1A74-4A39-BA92-E7E8F441E7F7">

<title>DMA Framework</title>

<image href="GUID-939A6B03-E5FA-411E-9ED0-D1F579BF5C1C_d0e325589_href.png" placement="inline"/>

</fig></p></section>

<section id="GUID-05B51EC6-F4CC-4C1C-AF91-1977FEE68FF6"><title>Use cases</title><p><ul>

<li><p>To adapt the DMA Framework to a new platform, you must implement its

Platform-Specific Layer. For more information, see the <xref href="GUID-95A33491-17AC-4F12-948E-A1352ADDA483.dita">Implementation</xref> section.</p></li>

<li><p>Using the DMA Framework is described in the <xref href="GUID-D1F7D21F-BA9D-482C-9B58-7C53A680145A.dita">DMA</xref> section

of the <xref href="GUID-C22974D8-CFB9-4A83-BE58-CCC97EA8DF13.dita">Device Driver

Writing Guide</xref>.</p></li>

</ul></p></section>

</conbody></concept>