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IXP400 Software
Access-Layer Components: DMA Access Driver (IxDmaAcc) API
Programmer’s Guide IXP400 Software Version 2.0 April 2005
Document Number: 252539, Revision: 007 123
8.8 Data Flow
The purpose of the DMA access layer is to transfer DMA configuration information from its clients
to the NPEs. It is a control component where the actual DMA data flow is transparent to the
IxDmaAcc component.
8.9 Control Flow
For a DMA transaction to start, the client must initialize the DMA access layer, write to the queue
manager, and receive a status of the transaction.
The IxDmaAcc component simultaneously supports multiple services. Consequently, a new
request may be submitted before the confirmation of a previous DMA request is received from the
NPE. The DMA Access layer API, however, assumes that all requests originate from the same Intel
XScale core task. The DMA request is queued in the AQM’s request queue and waits to be serviced
by the DMA NPE.
Table 16. DMA Modes Supported for Addressing Mode of Fixed Source Address and
Incremental Destination Address
Increment
Source
Address
Increment
Destination
Address
Transfer Mode
Transfer Width
Source
Transfer Width
Destination
Copy Only
Copy and
Clear
Copy and
Bytes
Swapping
Copy and
Bytes Reverse
8-bit 8-bit Supported Supported Supported Supported
8-bit 16-bit Supported Supported Supported Supported
8-bit 32-bit Supported Supported Supported Supported
8-bit Burst Supported Supported Supported Supported
16-bit 8-bit Supported Supported Supported Supported
16-bit 16-bit Supported Supported Supported Supported
16-bit 32-bit Supported Supported Supported Supported
16-bit Burst Supported Supported Supported Supported
32-bit 8-bit Supported Supported Supported Supported
32-bit 16-bit Supported Supported Supported Supported
32-bit 32-bit Supported Supported Supported Supported
32-bit Burst Supported Supported Supported Supported
Burst 8-bit Not Supported Not Supported Not Supported Not Supported
Burst 16-bit Not Supported Not Supported Not Supported Not Supported
Burst 32-bit Not Supported Not Supported Not Supported Not Supported
Burst Burst Not Supported Not Supported Not Supported Not Supported