Intel
®
81341 and 81342—Messaging Unit
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
428
Order Number: 315037-002US
4.9.3
Inbound Doorbell Register - IDR
The Inbound Doorbell Register (IDR) is used to generate interrupts to the Intel XScale
®
processor. Bit 31 is reserved for generating an Error Doorbell interrupt. When bit 31 is
set, an Error interrupt may be generated to the Intel XScale
®
processor. All other bits,
when set, cause the Normal Messaging Unit interrupt line of the Intel XScale
®
processor to be asserted, when the interrupt is not masked by the Inbound Doorbell
Interrupt Mask bit in the Inbound Interrupt Mask Register. The bits in the IDR register
can only be set by an external Host I/O Interface agent and can only be cleared by the
Intel XScale
®
processor.
Table 267. Inbound Doorbell Register - IDR
Bit
Default
Description
31
0
2
Error Interrupt - Generate an Error Interrupt to the Intel XScale
®
processor.
30:00
00000000H Normal Interrupt - When any bit is set, generate a Normal interrupt to the Intel XScale
®
processor.
When all bits are clear, do not generate a Normal Interrupt.
PCI
IOP
Attributes
Attributes
28
24
20
16
12
8
4
0
31
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
rc
rs
Attribute Legend:
RV = Reserved
PR = Preserved
RS = Read/Set
RW = Read/Write
RC = Read Clear
RO = Read Only
NA = Not Accessible
MU/PCI Base Address Offset
IDR: 0020H
internal bus address offset
IDR: 4020H