2. PCI Interface
79
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
2.6.11
I
2
0 Inbound Queue
A read from the I
2
O Inbound Queue returns the next available MFA from the I
2
O Inbound Free List
FIFO. This is a destructive read.
A write to this offset is used to place a MFA into the I
2
O Inbound Post List FIFO. The PowerSpan II
accepts the write cycle as a posted write and is responsible for completing the cycle on the destination
bus.
When the I
2
0 Interface in PowerSpan II is not enabled, the IN_Q register is not visible to read or write
access. The register essentially disappears from all PowerSpan II memory maps.
Register Name: IN_Q
Register Offset: 040
PCI
Bits
Function
PPC
Bits
31-24
MFA
0-7
23-16
MFA
8-15
15-08
MFA
16-23
07-00
MFA
24-31
Name
Type
Reset
By
Reset
State
Function
MFA[31:0]
R/W
Px_RST
0
Inbound Message Frame Address
The Inbound Message Frame Address specifies locations in
the IOP memory map where Inbound Message Frames
reside.
The MFA is the offset from the beginning of the I
2
O target
image window in the destination bus memory map and the
destination address where the Message Frame begins.