cx28500 Mindspeed Technologies, cx28500 Datasheet - Page 59

• Manufacturer Part Number: cx28500
• Description: Cx28500 Multichannel Synchronous Communications Controller
• Manufacturer: Mindspeed Technologies

CX28500 only responds to Type 0 configuration cycles. Type 1 cycles, which pass a configuration request on to
another PCI bus are ignored.
CX28500 is a single function PCI agent; therefore, it implements configuration space for Function 0 only.
The address phase during a CX28500 configuration cycle indicates the function number and register number being
addressed, which can be decoded by observing the status of the address lines AD[63:0].
address lines during configuration cycle.
Figure 3-2.
The value of the signal lines AD[10:8] selects the function being addressed. Since CX28500 supports Function 0
only, it ignores these bits.
The value of the signal lines AD[7:2] during the address phase of configuration cycles selects the register of the
configuration space to access. Valid values are 0 through 15. Accessing registers outside this range results in an
all 0s value being returned on reads, and no action being taken on writes.
The value of the signal lines AD[1:0] must be 00b for CX28500 to respond. If these bits are 0 and the IDSEL* signal
line is asserted, then CX28500 responds to the configuration cycle.
The Base Code register contains the Class Code, Sub Class Code, and Register Level Programming Interface
registers.
Table 3-1.
28500-DSH-002-C
Register
Number
0
1
2
3
4
Table 3-1
Address Lines During Configuration Cycle
PCI Configuration Space
Byte Offset (hex)
FOOTNOTE:
(1)
(2)
(3)
illustrates the PCI Configuration Space.
CX28500 supports Function 0 only.
CX28500 supports Registers 0 through 15, inclusively.
CX28500 supports Type 0 configuration cycles.
63/31
00h
04h
08h
0Ch
10h
31
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Mindspeed Technologies
Reserved
Don’t Care
24
(3)
Device ID
Status
Header Type
CX28500 Base Address Register (BAR)
Base Code
16
8 7
®
Register
Number
6-Bit
(2)
Latency Timer
2 1
Number
2-Bit
Type
0
(1)
8
Bit
Number
Figure 3-2
Command
Vendor ID
500052_019a
Host Interface
Revision Id
illustrates the
Reserved
0
44