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    10 <!DOCTYPE concept

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

    12 <concept id="GUID-EE50283A-543C-446F-A5D1-E64043F988ED" xml:lang="en"><title>DMA Device Driver Guide</title><shortdesc>Explains the key concepts that the device driver creator

    13 needs to know before developing a device driver.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <p>The DMA framework bypasses the CPU for data transfers. Without

    15 DMA, the CPU would have to copy each piece of data from the source

    16 to the destination.<ul>

    17 <li><p><b>Device Driver:</b> A set of methods that tells the platform

    18 how to use a specific piece of hardware.</p></li>

    19 </ul><ul>

    20 <li><p><b>DMA Framework:</b> The DMA framework provides a simplified

    21 and unified access to DMA resources in a device. Generic transfer

    22 parameters abstract the underlying DMA hardware for basic services,

    23 and fine-grained control is still available for platform-specific

    24 features. </p></li>

    25 </ul><ul>

    26 <li><p><b>DMA Operation:</b> Before any DMA transfers can be undertaken,

    27 the DMA channel to be used and the source and destination addresses

    28 of the data to be transferred have to be specified. The transfer details

    29 are placed onto a queue for the DMA channel specified. The item at

    30 the head of the queue will be the active transfer and the rest of

    31 the queue will be pending transfers. </p></li>

    32 </ul></p>

    33 </conbody><related-links>

    34 <link href="GUID-AB5370D9-9F0B-4583-A825-11CBF7C6365C.dita"><linktext>DMA

    35 Tutorials Overview</linktext></link>

    36 <link href="GUID-EDC1C30B-4078-4434-95AC-2E37AF809A51.dita"><linktext>DMA

    37 Implementation Overview</linktext></link>

    38 <link href="GUID-4E3C086B-25BE-4DAC-9E21-CFC4F8B792A5.dita"><linktext>DMA

    39 Technology Guide</linktext></link>

    40 </related-links></concept>