82C881 Datasheet, PDF (23/46 Pages) List of Unclassifed Manufacturers – FireLink 1394 OHCI Link Controller

FireLink 1394 OHCI
®
82C881
5.0 Register Descriptions
The 82C881 register set implements the OHCI registers, the FIFO Configuration registers, and the PCI bus configuration
registers.
5.1 OHCI and Bus Management Control and Status Registers
The OHCI Registers are memory mapped to Memory Base Address Register 1 (10h) and I/O mapped to I/O Base Address
Register 1 (18h) of PCI Configuration space.
The OHCI Registers and bus management control and status registers are implemented per the 1394 OHCI Specification,
Revision 1.0. For the register definitions, bit-mapping into the registers and access requirements for writing and reading the
registers, refer to the 1394 OHCI Specification, Revision 1.0.
5.2 FIFO Configuration Registers
As the FIFOs are configurable, the configuration can be changed by programming the FIFO Configuration registers. For each
sub-FIFO, there is a 32 bit Register containing the configuration value.
The FIFO Configuration registers are accessed as offsets from a base address. The access can be either through memory or
I/O space depending on the PCI base address configuration selected: a memory base address can be programmed in
PCICFG 14h, while an I/O base address can be programmed in PCICFG 1Ch.
Note: After programming new FIFO Configuration register values, the FIFO Config Enable bit at OFST 1Ch[0] must be set to
actually load the changed values.
There are eight registers in the FIFO Configuration register set:
• Isochronous Tx Configuration
• Asynchronous Tx Response Configuration
• Asynchronous Tx Request Configuration
• Physical Tx Configuration
• Miscellaneous Rx Configuration
• Asynchronous Rx Response Configuration
• Physical Rx Configuration
• Miscellaneous.
The first seven registers hold the FIFO Configuration values, while the Miscellaneous register is used to initiate loading of the
values programmed into the first seven registers and to selectively enable/disable specific P1394a features.
912-2000-031
Revision: 1.0
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