Chapter 9. Message Unit (with I
2
O)
9-9
I
2
O Interface
9.3.3.2.2 Outbound Post_List FIFO
The outbound post_list FIFO holds MFAs that are posted from the processor core to remote
processors. The processor core places messages in the outbound post_list FIFO by writing
the MFA to OPHPR. This software must then increment the value in OPHPR.
When the FIFO is not empty (head and tail pointers are not equal), the outbound post_list
queue interrupt bit in the outbound message interrupt status register (OMISR[OPQI]) is set.
Additionally, the external MPC8240 PCI interrupt signal (INTA) is asserted (if it is not
masked). When the head and tail pointers are equal, OMISR[OPQI] is cleared. The
outbound post_list queue interrupt can be masked using the outbound message interrupt
mask register (OMIMR).
An external PCI master reads the outbound FIFO queue port register (OFQPR) to cause the
MPC8240’s I
2
O unit to read the MFA from local memory pointed to by the OPTPR. The
I
2
O unit then automatically increments the value in OPTPR.
When the FIFO is empty (head and tail pointers are equal), the unit returns 0xFFFF_FFFF.
9.3.4 I
2
O Register Descriptions
The following sections provide detailed descriptions of the I
2
O registers and some of the
bits that control the generic message and doorbell register interface in these registers. See
Chapter 11, “Embedded Programmable Interrupt Controller (EPIC) Unit,” for more
information on the interrupt mechanisms of the MPC8240.
9.3.4.1 PCI-Accessible I
2
O Registers
The OMISR, OMIMR, IFQPR, and OFQPR registers are used by PCI masters to access the
MPC8240 I
2
O unit. The processor core cannot access any of these registers.
9.3.4.1.1 Outbound Message Interrupt Status Register (OMISR)
The OMISR contains the interrupt status of the I
2
O, doorbell register, and outbound
message register events that cause the assertion of INTA. These events are generated by
blocks in the MPC8240 and the assertion of INTA signals an interrupt to the PCI bus on
behalf of these blocks.
Writing a 1 to a set bit in OMISR clears the bit (except for read-only bits). Software
attempting to determine the source of the interrupts should always perform a logical AND
between the OMISR bits and their corresponding mask bits in the OMIMR.
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 ...