
OHCI Controller Programming Model
138
September 2005
SCPS110
7.5
Class Code and Revision ID Register
The class code and revision ID register categorizes the 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 74 for a complete description of the register contents.
Function 1 register offset: 08h
Register type:
Read-only
Default value:
0C00 1000h
BIT NUMBER
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
RESET STATE
0
1
0
BIT NUMBER
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RESET STATE
0
1
0
Table 74. Class Code and Revision ID Register Description
BIT
FIELD NAME
TYPE
DESCRIPTION
3124
BASECLASS
R
Base class. This field returns 0Ch when read, which broadly classifies the function as a serial bus
controller.
2316
SUBCLASS
R
Subclass. This field returns 00h when read, which specifically classifies the function as controlling an
IEEE 1394 serial bus.
158
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.
70
CHIPREV
R
Silicon revision. This field returns 00h when read, which indicates the silicon revision of the 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 controller. See Table 75 for a complete description of the
register contents.
Function 1 register offset: 0Ch
Register type:
Read/Write
Default value:
0000h
BIT NUMBER
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RESET STATE
0
Table 75. Latency Timer and Class Cache Line Size Register Description
BIT
FIELD NAME
TYPE
DESCRIPTION
158
LATENCY_TIMER
RW
PCI latency timer. The value in this register specifies the latency timer for the controller, in units of PCI
clock cycles. When the controller is a PCI bus initiator and asserts FRAME, the latency timer begins
counting from zero. If the latency timer expires before the transaction has terminated, then the controller
terminates the transaction when its GNT is deasserted. The default value for this field is 00h.
70
CACHELINE_SZ
RW
Cache line size. This value is used by the controller during memory write and invalidate, memory-read
line, and memory-read multiple transactions. The default value for this field is 00h.