Intel Extensible Firmware Interface - Manual (Page 440)

Extensible Firmware Interface Specification
12-22 12/01/02 Version 1.10
EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL.Io.Read()
EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL.Io.Write()
Summary
Enables a PCI driver to access PCI controller registers in the PCI root bridge I/O space.
Prototype
typedef
EFI_STATUS
(EFIAPI *EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_IO_MEM) (
IN EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL
*This,
IN EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_WIDTH Width,
IN UINT64 Address,
IN UINTN Count,
IN OUT VOID *Buffer
);
Parameters
This A pointer to the EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL .
Type EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL is defined in
Section 12.2.
Width Signifies the width of the memory operations. Type
EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_WIDTH is defined
in Section 12.2.
Address The base address of the I/O operation. The caller is responsible for
aligning the
Address if required.
Count The number of I/O operations to perform. Bytes moved is Width
size * Count , starting at Address .
Buffer For read operations, the destination buffer to store the results. For
write operations, the source buffer to write data from.