Pci Address Translation Support - Motorola MPC8240 User Manual

PCI Host and Agent Modes
7.7.3 PCI Configuration Cycle Retry Capability in Agent
Mode
When the MPC8240 is configured for agent mode and is initializing from ROM located on
the local memory bus, it may be necessary to defer a remote host from completing PCI
configuration cycles until the local device can be tested and configured.
When the MPC8240 RTY_PCI_CFG bit (bit 10 in PACR) is set, the MPC8240's PCI bus
interface retries PCI configuration cycles. This mechanism allows the processor core to
complete configuration of the local memory controller in advance of a system host
controller. Once the MPC8240 has completed local configuration, it can clear the
RTY_PCI_CFG bit, enabling the system host controller to complete configuration.

7.7.4 PCI Address Translation Support

The MPC8240 allows remapping PCI memory space transactions to local memory and
processor core transactions to PCI memory space. Note that address translation is supported
only for agent mode; it is not supported when the MPC8240 is operating in host mode. Also
note that since agent mode is supported only for address map B, address translation is
supported only for address map B. The following sections summarize the address
translation support of the MPC8240. See Section 3.3, "Address Translation," for more
information about the MPC8240 address translation facility.
7.7.4.1 Inbound PCI Address Translation
Inbound transactions are PCI memory space accesses initiated by an external PCI master
that are targeted toward the MPC8240. Using inbound address translation, the MPC8240
claims the PCI memory space transaction and translates it to a local memory access. When
the MPC8240 is in agent mode, inbound address translation allows an external PCI master
to access local memory through a window in the PCI memory space.
Note that in agent mode, the MPC8240 ignores all PCI accesses to local memory until
inbound address translation is enabled. That is, in agent mode, the MPC8240 responds only
to the PCI configuration and to the embedded utilities memory block (EUMB) accesses
until inbound translation is enabled. See Section 3.3.1, "Inbound PCI Address Translation,"
for a complete description of inbound PCI address translation.
7.7.4.2 Outbound PCI Address Translation
Outbound transactions are accesses initiated by the processor core that are targeted to PCI
memory space. Using outbound address translation, the processor transaction is translated
to an address in PCI memory space. When the MPC8240 is in agent mode, outbound
address translation allows the MPC8240 to access (external) host memory in the lower 2
Gbytes of PCI memory space. See Section 3.3.2, "Outbound PCI Address Translation," for
a complete description of outbound PCI address translation.
7-34 MPC8240 Integrated Processor User's Manual