MOTOROLA
Chapter 7. PCI Bus Interface
7-21
Figure 7-9. Direct-Access PCI Configuration Transaction
The MPC106 decodes transactions in the 60x processor address range from 0x8080_0000–
0x80FF_FFFF, clears the most-significant address bit, and copies without modification the
30 low-order bits of the 60x bus address onto the AD[31–0] signals during the address
phase of a configuration cycle. The two least-significant bits of the 60x bus address, A[30–
31], must be 0b00. Note that the direct-access method is limited to generating IDSEL on
AD[11–22]. Also note that AD23 is always asserted for direct-access configuration cycles.
Therefore, no PCI device should use AD23 for the IDSEL input on systems using address
map A.
For type 1 translations, the MPC106 copies without modification the 30 high-order bits of
the CONFIG_ADDR register onto the AD[31–2] signals during the address phase. The
MPC106 automatically translates AD[1–0] into 0b01 during the address phase to indicate
a type 1 configuration cycle.
7.4.6 Other Bus Transactions
There are two other PCI transactions that the MPC106 supports—interrupt-acknowledge
and special-cycles. As a master, the MPC106 may initiate both interrupt-acknowledge and
special-cycle transactions; however, as a target, the MPC106 ignores interrupt-
acknowledge and special-cycle transactions. Both transactions make use of the
CONFIG_ADDR and CONFIG_DATA registers discussed in Section 7.4.5.2, “Accessing
the PCI Configuration Space.”
7.4.6.1 Interrupt Acknowledge Transactions
The PCI bus supports an interrupt-acknowledge transaction. The interrupt-acknowledge
command is a read operation implicitly addressed to the system interrupt controller.
31 30
24 23 22
11 10
8 7
2 1
0
000 0000
Reserved
Function Number
Register Number
1
00
31 30
24 23 22
11 10
2 1
0
IDSEL–only one signal high
Function/Register Number
00
60x bus address (A[0–31]) in the range
0x8080_0000–0x80FF_FFFF
AD[31–0] Signals
During Address Phase
IDSEL–only one signal high
1
000 0000
0
1