Intel Extensible Firmware Interface - Manual (Page 482)

Extensible Firmware Interface Specification
12-64 12/01/02 Version 1.10
DMA Bus Master Read Operation
• Call
Map() for EfiPciIoOperationBusMasterRead .
• Program the DMA Bus Master with the
DeviceAddress returned by Map().
• Start the DMA Bus Master.
• Wait for DMA Bus Master to complete the read operation.
• Call
Unmap() .
DMA Bus Master Write Operation
• Call
Map() for EfiPciOperationBusMasterWrite .
• Program the DMA Bus Master with the
DeviceAddress returned by Map() .
• Start the DMA Bus Master.
• Wait for DMA Bus Master to complete the write operation.
• Perform a PCI controller specific read transaction to flush all PCI write buffers (See PCI
Specification Section 3.2.5.2) .
• Call
Flush() .
• Call
Unmap() .
DMA Bus Master Common Buffer Operation
• Call
AllocateBuffer() to allocate a common buffer.
•
Call Map() for EfiPciIoOperationBusMasterCommonBuffer .
• Program the DMA Bus Master with the
DeviceAddress returned by Map() .
• The common buffer can now be accessed equally by the processor and the DMA bus master.
•
Call Unmap() .
•
Call FreeBuffer() .