Chapter 9. Message Unit (with I
2
O)
9-3
Message and Doorbell Register Programming Model
9.2.2 Message Register Descriptions
The IMRs allow a remote host or PCI master to write a 32-bit value that automatically
generates an interrupt to the processor core through the EPIC unit. The OMRs allow the
processor core to write an outbound message that automatically causes the outbound
interrupt signal INTA to be asserted on the PCI bus. These interrupts can be masked in the
IMIMR and OMIMR. When the message registers are written, their corresponding
interrupt status bits in the IMISR and OMISR are set. Figure 9-1 shows the bits of the IMRs
and OMRs.
.
Figure 9-1. Message Registers (IMRs and OMRs)
Table 9-3 shows the bits settings for the IMRs and OMRs.
9.2.3 Doorbell Register Descriptions
The IDBR allows a remote processor to set a bit in the register from the PCI bus. This, in
turn, generates an interrupt to the processor core through the EPIC unit if the interrupt is
not masked in IMIMR, or generates mcp (if it is not masked in IMIMR). After the local
interrupt (or mcp) is generated, it can only be cleared by the processor core by writing a 1
to the bits that are set in the IDBR. The remote processor can only generate the local
interrupt through the IDBR; it cannot clear the interrupt. Figure 9-2 shows the IDBR.
Figure 9-2. Inbound Doorbell Register (IDBR)
Table 9-3. IMR and OMR Field Descriptions—Offsets 0x050–0x05C,
0x0_0050–0x0_005C
Bits
Name
Reset Value
R/W
Description
31–0
MSG
Undefined
R/W
The inbound and outbound message registers contain generic message
data to be passed between the processor core and remote processors.
MSG
31
0
DBn
31
30
0
MC
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 ...