PCI Interface Functional Overview
P2P Capability
Copyright © 2002 Marvell
CONFIDENTIAL
Doc. No. MV-S300165-00, Rev. A
May 21, 2002, Preliminary
Document Classification: Proprietary Information
Page 47
5.1.1 Memory and I/O P2P Transactions
To support access between the two PCI interfaces, the GT-64260A contains two 32-bit Memory BARs and one 32-
bit I/O BAR. It also supports two additional Memory BARs for 64-bit addressing (DAC). A PCI address hit in one of
the P2P BARs results in transferring the transaction to the other PCI interface memory space.
5.1.2 Configuring P2P Transactions
Each PCI interface responds to a type 1 configuration transaction according to the settings of the PCI P2P Config-
uration register’s
2ndBusL
bits [7:0] and
2ndBusH
bits [15:8], at offsets 0x1d14 and 0x1d94. These fields specify
the range of the buses that reside on the PCI interface.
shows an example of a system configuration.
Figure 19: I/O P2P Transaction Example
For this example, the system configuration of the PCI P2P Configuration register must be initialized as follows.
Table 11:
PCI P2P Configuration Register Initialization Example
GT-64260A #1
GT-64260A #2
GT-64260A #3
PCI0
PCI1
PCI0
PCI1
PCI0
PCI1
2nd BusL
1
0
2
0
0
3
2nd BusH
3
0
2
3
2
3
GT-64260A #1
PCI0 PCI1
PCI #0
PCI #1
PCI #2
PCI #3
PCI1
PCI0
PCI0
PCI1
GT-64260A #2
GT-64260A #3