VMEbus--Example Two

A DMA engine on a VMEbus in a SPARC machine has the following attributes:

• It can address the full 32-bit range.

• It has a 32-bit DMA counter register.

• It can handle byte-aligned transfers.

• It supports 2- to 256-byte burst sizes, and all powers of 2 in between.

• It has a minimum effective transfer size of 2 bytes.

• It has a 24-bit address register.

• It has a 17-element scatter-gather list.

• The device operates on sectors only.

The resulting attribute structure is:

	static ddi_dma_attr_t attributes = {
 		DMA_ATTR_V0,		/* Version number */
 		0x00000000,			/* low address */
 		0xFFFFFFFF,			/* high address */
 		0xFFFFFFFF,			/* counter register max */
 		1,						/* byte alignment */
 		0x1FE,				/* burst sizes */
 		0x2,					/* minimum transfer size */
 		0xFFFFFFFF,			/* max xfer size */
 		0xFFFFFF,			/* address register max */
 		17,					/* no scatter-gather */
 		512,					/* device operates on sectors */
 		0,						/* attr flag: set to 0 */
 	};