Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
241
Address Translation Unit (PCI Express)—Intel
®
81341 and 81342
Inbound and outbound ATU transactions are best described by the data flows used on
the PCI Express Link and the 81341 and 81342 internal bus during read and write
operations. The following sections describe read and write operations for inbound ATU
transactions (PCI Express to internal bus) and outbound transactions (internal bus to
PCI Express). All transactions are full split and the requests and completions are
described separately.
Table 116. ATU Command Support
TLP Type
Fmt[1:0]
a
Type[4:0]
Supported as
Completer
Generated as
Requester
Valid Internal
Bus Command
MRd
00
01
0 0000
Yes
Yes
Read
MRdLk
00
01
0 0001
Unsupported
Request
No
N/A
MWr
10
11
0 0000
Yes
Yes
Write
IORd
00
0 0010
Yes
Yes
Read
IOWr
10
0 0010
Yes
Yes
Write
CfgRd0
00
0 0100
Yes
Yes
Read
CfgWr0
10
0 0100
Yes
Yes
Write
CfgRd1
00
0 0101
Unsupported
Request
Yes
N/A
CfgWr1
10
0 0101
Unsupported
Request
Yes
N/A
Msg
01
1 0r
2
r
1
r
0
Yes
Yes
Write
b
MsgD
11
1 0r
2
r
1
r
0
Yes
Yes
Write
Cpl
00
0 1010
Yes
Yes
Completion
CplD
10
0 1010
Yes
Yes
Completion
CplLk
00
0 1011
Unexpected
Completion
c
No
N/A
CplDLk
10
0 1011
Unexpected
Completion
No
N/A
All encodings not shown above are
reserved
Malformed
Packet
No
N/A
a. Requests with two Fmt[1:0] values shown can use either 32b (the first value) or 64b (the second value)
Addressing Packet formats.
b. As a completer, the ATU stores the message header and payload directly in memory mapped registers. No
internal bus traffic occurs.
c. ATU does not generate lock requests and any CplLk or CplDLk would be an unexpected completion.