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9-2
MPC8240 Integrated Processor User’s Manual
Message and Doorbell Register Programming Model
9.2 Message and Doorbell Register Programming
Model
The message and doorbell registers are described in the following subsections. Note that
the interrupt status and interrupt mask bits for the message and doorbell registers are in the
OMISR, OMIMR, IMISR, and IMIMR I
2
O registers. See Section 9.3.4.1, “PCI-Accessible
I2O Registers” and Section 9.3.4.2, “Processor-Accessible I2O Registers,” for more
information about these registers.
The outbound message and doorbell registers are used to communicate with a PCI host by
asserting the INTA signal on the PCI bus. The PCI host is defined as the device that handles
the PCI interrupts.
The message and doorbell registers can also be used to perform peer-to-peer
communication such as between multiple MPC8240 devices in a system. In this scenario,
only the inbound registers need to be used and should be all mapped to different PCSRBAR
locations. Because there is not a host in this scenario, INTA is not generated (and the
outbound registers are not used).
9.2.1 Message and Doorbell Register Summary
MPC8240 contains two 32-bit inbound message registers (IMR0 and IMR1) and two 32-bit
outbound message registers (OMR0 and OMR1) that function in both host and agent mode.
Table 9-1 summarizes the message registers.
The MPC8240 also contains a 32-bit inbound and a 32-bit outbound doorbell register
(IDBR and ODBR, respectively). Table 9-2 summarizes the doorbell registers.
Table 9-1. Message Register Summary
PCI Offset
Local Memory
Offset
Acronym
Name
0x050
0x0_0050
IMR0
Inbound message register 0
0x054
0x0_0054
IMR1
Inbound message register 1
0x058
0x0_0058
OMR0
Outbound message register 0
0x05C
0x0_005C
OMR1
Outbound message register 1
Table 9-2. Doorbell Register Summary
PCI Offset
Local Memory
Offset
Acronym
Name
0x060
0x0_0060
ODBR
Outbound doorbell register
0x068
0x0_0068
IDBR
Inbound doorbell register
Summary of Contents for MPC8240
Page 1: ...MPC8240UM D Rev 1 1 2001 MPC8240 Integrated Processor User s Manual ...
Page 38: ...xviii MPC8240 Integrated Processor User s Manual TABLES Table Number Title Page Number ...
Page 48: ...xlviii MPC8240 Integrated Processor User s Manual Acronyms and Abbreviations ...
Page 312: ...6 94 MPC8240 Integrated Processor User s Manual ROM Flash Interface Operation ...
Page 348: ...7 36 MPC8240 Integrated Processor User s Manual PCI Host and Agent Modes ...
Page 372: ...8 24 MPC8240 Integrated Processor User s Manual DMA Register Descriptions ...
Page 394: ...9 22 MPC8240 Integrated Processor User s Manual I2O Interface ...
Page 412: ...10 18 MPC8240 Integrated Processor User s Manual Programming Guidelines ...
Page 454: ...12 14 MPC8240 Integrated Processor User s Manual Internal Arbitration ...
Page 466: ...13 12 MPC8240 Integrated Processor User s Manual Exception Latencies ...
Page 516: ...16 14 Watchpoint Trigger Applications ...
Page 538: ...B 16 MPC8240 Integrated Processor User s Manual Setting the Endian Mode of Operation ...
Page 546: ...C 8 MPC8240 Integrated Processor User s Manual ...
Page 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...