
MOTOROLA
Chapter 7. PCI Bus Interface
7-17
to another PCI bus (through a PCI-to-PCI bridge). Type 1 accesses are ignored by all targets
except PCI-to-PCI bridges.
To access the configuration space, a 32-bit value must be written to the CONFIG_ADDR
register that specifies the target PCI bus, the target device on that bus, and the configuration
register to be accessed within that device. A read or write to the CONFIG_DATA register
causes the MPC106 to translate the access into a PCI configuration cycle (provided the
enable bit in CONFIG_ADDR is set and the device number is not 0b1_1111).
The CONFIG_ADDR register is located at different addresses depending on the memory
address map in use. The address maps are described in Section 3.1, “Address Maps.” For
address map A in the contiguous mode, the 60x can access the CONFIG_ADDR register
through the MPC106 at 0x8000_0CF8. For address map A in the discontiguous mode, the
60x can access the CONFIG_ADDR register through the MPC106 at 0x8006_7018. For
address map B and the emulation mode address map, the 60x can access the
CONFIG_ADDR register at any location in the address range from 0xFEC0_0000 to
0xFEDF_FFFF. For simplicity, the address for CONFIG_ADDR is sometimes referred to
as CF8, 0x
nnnn
_
n
CF8, or (in the PCI literature as) CF8h. Although systems implementing
address map B or emulation mode address map can use any address in the range from
0xFEC0_0000 to 0xFEDF_FFFF for the CONFIG_ADDR register, the address
0xFEC0_0CF8 may be the most intuitive location.
The format of CONFIG_ADDR is shown in Figure 7-7.
Figure 7-7. Layout of CONFIG_ADDR Register
31 30
24 23
16 15
11 10
8 7
2 1
0
Bus Number
000 0000
Reserved
Device Number
Function Number
Register Number
E
00