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<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
needs to know before developing a device driver.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>The DMA framework bypasses the CPU for data transfers. Without
DMA, the CPU would have to copy each piece of data from the source
to the destination.<ul>
<li><p><b>Device Driver:</b> A set of methods that tells the platform
how to use a specific piece of hardware.</p></li>
</ul><ul>
<li><p><b>DMA Framework:</b> 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></li>
</ul><ul>
<li><p><b>DMA Operation:</b> Before any DMA transfers can be undertaken,
the DMA channel to be used and the source and destination addresses
of the data to be transferred have to be specified. The transfer details
are placed onto a queue for the DMA channel specified. The item at
the head of the queue will be the active transfer and the rest of
the queue will be pending transfers. </p></li>
</ul></p>
</conbody><related-links>
<link href="GUID-AB5370D9-9F0B-4583-A825-11CBF7C6365C.dita"><linktext>DMA
Tutorials Overview</linktext></link>
<link href="GUID-EDC1C30B-4078-4434-95AC-2E37AF809A51.dita"><linktext>DMA
Implementation Overview</linktext></link>
<link href="GUID-4E3C086B-25BE-4DAC-9E21-CFC4F8B792A5.dita"><linktext>DMA
Technology Guide</linktext></link>
</related-links></concept>