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7−5
7.5 Class Code and Revision ID Register
The class code and revision ID register categorizes the PCI7x21/PCI7x11 controller as a serial bus controller (0Ch),
controlling an IEEE 1394 bus (00h), with an OHCI programming model (10h). Furthermore, the TI chip revision is
indicated in the least significant byte. See Table 7−4 for a complete description of the register contents.
Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Name Class code and revision ID
Type R R R R R R R R R R R R R R R R
Default 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Name Class code and revision ID
Type R R R R R R R R R R R R R R R R
Default 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0
Register: Class code and revision ID
Offset: 08h
Type: Read-only
Default: 0C00 1000h
Table 7−4. Class Code and Revision ID Register Description
BIT FIELD NAME TYPE DESCRIPTION
31−24 BASECLASS R
Base class. This field returns 0Ch when read, which broadly classifies the function as a serial bus
controller.
23−16 SUBCLASS R
Subclass. This field returns 00h when read, which specifically classifies the function as controlling an
IEEE 1394 serial bus.
15−8 PGMIF R
Programming interface. This field returns 10h when read, which indicates that the programming model
is compliant with the 1394 Open Host Controller Interface Specification.
7−0 CHIPREV R
Silicon revision. This field returns 00h when read, which indicates the silicon revision of the
PCI7x21/PCI7x11 controller.
7.6 Latency Timer and Class Cache Line Size Register
The latency timer and class cache line size register is programmed by host BIOS to indicate system cache line size
and the latency timer associated with the PCI7x21/PCI7x11 controller. See Table 7−5 for a complete description of
the register contents.
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Name Latency timer and class cache line size
Type RW RW RW RW RW RW RW RW RW RW RW RW RW RW RW RW
Default 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Register: Latency timer and class cache line size
Offset: 0Ch
Type: Read/Write
Default: 0000h
Table 7−5. Latency Timer and Class Cache Line Size Register Description
BIT FIELD NAME TYPE DESCRIPTION
15−8 LATENCY_TIMER RW
PCI latency timer. The value in this register specifies the latency timer for the PCI7x21/PCI7x11 controller,
in units of PCI clock cycles. When the PCI7x21/PCI7x11 controller is a PCI bus initiator and asserts
FRAME, the latency timer begins counting from zero. If the latency timer expires before the
PCI7x21/PCI7x11 transaction has terminated, then the PCI7x21/PCI7x11 controller terminates the
transaction when its GNT
is deasserted. The default value for this field is 00h.
7−0 CACHELINE_SZ RW
Cache line size. This value is used by the PCI7x21/PCI7x11 controller during memory write and invalidate,
memory-read line, and memory-read multiple transactions. The default value for this field is 00h.