7-18
MPC106 PCIB/MC User's Manual
MOTOROLA
Table 7-3 describes the fields within CONFIG_ADDR.
As with the CONFIG_ADDR register, the CONFIG_DATA register is located at different
addresses depending on the memory address map in use. For address map A in the
contiguous mode, the 60x can access the CONFIG_DATA register through the MPC106 at
0x8000_0CFC–0x8000_0CFF. For address map A in the discontiguous mode, the 60x can
access the CONFIG_DATA register through the MPC106 at 0x8006_701C–0x8006_701F.
For address map B and the emulation mode address map, the 60x can access the
CONFIG_DATA register at any location in the address range from 0xFEE0_0000 to
0xFEEF_FFFF. For simplicity, the address for CONFIG_DATA is sometimes referred to as
CFC, 0x
nnnn
_
n
CFC, or (in the PCI literature as) CFCh. Although systems implementing
address map B or emulation mode address map can use any address in the range from
0xFEE0_0000 to 0xFEEF_FFFF for the CONFIG_DATA register, the address
0xFEE0_0CFC–0xFEE0_0CFF may be the most intuitive location.
Note that the CONFIG_DATA register may contain 1, 2, 3, or 4 bytes depending on the size
of the register being accessed.
When the MPC106 detects an access to the CONFIG_DATA register, it checks the enable
flag and the device number in the CONFIG_ADDR register. If the enable bit is set, and the
device number is not 0b1_1111, the MPC106 performs a configuration cycle translation
and runs a configuration-read or configuration-write transaction on the PCI bus. The device
number 0b1_1111 is used for performing interrupt-acknowledge and special-cycle
transactions. See Section 7.4.6, “Other Bus Transactions,” for more information. If the bus
number corresponds to the local PCI bus (bus number = 0x00), the MPC106 performs a
type 0 configuration cycle translation. If the bus number indicates a nonlocal PCI bus, the
MPC106 performs a type 1 configuration cycle translation.
Table 7-3. CONFIG_ADDR Register Fields
Bits
Field Name
Description
31
E(nable)
The enable flag controls whether accesses to CONFIG_DATA are translated
into PCI configuration cycles.
1
Enabled
0
Disabled
30–24
—
Reserved (must be 0b000_0000)
23–16
Bus number
This field is an encoded value used to select the target bus of the configuration
access. For target devices on the PCI bus connected to the MPC106, this field
should be set to 0x00.
15–11
Device number
This field is used to select a specific device on the target bus.
10–8
Function number
This field is used to select a specific function in the requested device. Single-
function devices should respond to function number 0b000.
7–2
Register number
This field is used to select the address offset in the configuration space of the
target device.
1–0
—
Reserved (must be 0b00)