Intel IXP400 manual Data Flow, Control Flow

Intel® IXP400 Software

Access-Layer Components: DMA Access Driver (IxDmaAcc) API

Table 16. DMA Modes Supported for Addressing Mode of Fixed Source Address and Incremental Destination Address

Increment	Increment
Source	Destination		Transfer Mode
Address	Address
Transfer Width	Transfer Width	Copy Only	Copy and	Copy and	Copy and
				Bytes
Source	Destination		Clear		Bytes Reverse
				Swapping
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

8.8Data 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.

8.9Control 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.

Programmer’s Guide	IXP400 Software Version 2.0	April 2005
	Document Number: 252539, Revision: 007	123