Chapter 5: IP Core Architecture
5–15
PCI Express Avalon-MM Bridge
June 2012
Altera Corporation
Stratix V Hard IP for PCI Express
PCI Express-to-Avalon-MM Downstream Read Requests
The PCI Express Avalon-MM bridge sends PCI Express read packets to the
interconnect fabric as burst reads with a maximum burst size of 512 bytes. The bridge
converts the PCI Express address to the Avalon-MM address space based on the BAR
hit information and address translation lookup table values. You can set up the
Address Translation Table Configuration using the parameter editor. Unsupported
read requests generate a completer abort response.
Avalon-MM-to-PCI Express Read Completions
The PCI Express Avalon-MM bridge converts read response data from Application
Layer Avalon-MM slaves to PCI Express completion packets and sends them to the
Transaction Layer.
A single read request may produce multiple completion packets based on the
Maximum payload size
and the size of the received read request. For example, if the
read is 512 bytes but the
Maximum payload size
128 bytes, the bridge produces four
completion packets of 128 bytes each. The bridge does not generate out-of-order
completions. You can specify the
Maximum payload size
parameter on the
Device
tab under the
PCI Express/PCI Capabilities
heading in the parameter editor. Refer to
“PCI Express and PCI Capabilities Parameters” on page 4–6
.
PCI Express-to-Avalon-MM Address Translation
The PCI Express Avalon-MM Bridge translates the system-level physical addresses,
typically up to 64 bits, to the 32-bit byte addresses used by the Application Layer. You
can specify up to six BARs for address translation when you customize your Hard IP
for PCI Express as described in
“Base Address Register (BAR) and Expansion ROM
. The PCI Express Avalon-MM Bridge also translates the 32-bit
byte addresses used by the Application Layer to system-level physical addresses as
described in
“Avalon-MM-to-PCI Express Address Translation” on page 5–16
.
provides a high-level view of address translation in both directions.
Figure 5–7. Address Translation in TX and RX Directions
Transaction,
Data Link,
and PHY
DMA
Avalon-MM
32-Bit Byte Address
Avalon-MM
32-Bit Byte Address
PCIe TLP
Address
PCIe TLP
Address
Q
sys Gene
r
a
t
ed Endpoin
t
wi
t
h DMA Con
tr
olle
r
and On-Chip RAM
TX
PCIe
Link
RX
PCIe
Link
PCI Exp
r
ess Avalon-MM B
r
idge
Interconnect
Avalon-MM S
tr
a
t
ix V Ha
r
d IP fo
r
PCI Exp
r
ess
Number of address pages (1-512)
Size of address pages
Add
r
ess T
r
ansla
t
ion Table Pa
r
ame
t
e
r
s
Avalon-MM-
t
o-PCIe Add
r
ess T
r
ansla
t
ion
BAR (0-5)
BAR Type
BAR Size
PCI Base Add
r
ess Regis
t
e
r
s (BAR)
PCIe-
t
o-Avalon-MM Add
r
ess T
r
ansla
t
ion
On-
Chip
RAM
M
S
= RX Avalon-MM Master
= TX Avalon-MM Slave
S
M