5–16
Chapter 5: IP Core Architecture
Avalon-MM Bridge TLPs
Arria V GZ Hard IP for PCI Express
November 2012
Altera Corporation
PCI Express-to-Avalon-MM Address Translation for Endpoints
The PCI Express Avalon-MM Bridge translates the system-level physical addresses,
typically up to 64 bits, to the significantly smaller addresses required by the
Application Layer’s Avalon-MM slave components. 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 Settings” on
. The PCI Express Avalon-MM Bridge also translates Application Layer
addresses to system-level physical addresses as described in
Express Address Translation Algorithm” on page 5–19
provides a high-level view of address translation in both directions.
1
When configured as a Root Port, a single RX Avalon-MM master forwards all RX TLPs
to the Qsys interconnect.
The Avalon-MM RX master module port has an 8-byte datapath in 64-bit mode and a
16-byte datapath in 128-bit mode. The Qsys interconnect fabric manages mismatched
port widths transparently.
As Memory Request TLPs are received from the PCIe link, the most significant bits are
used in the BAR matching as described in the PCI specifications. The least significant
bits not used in the BAR match process are passed unchanged as the Avalon-MM
address for that BAR's RX Master port.
For example, consider the following configuration specified using the Base Address
Registers in the GUI.
1. BAR1:0 is a
64-bit prefetchable memory
that is
4KBytes -12 bits
2. System software programs BAR1:0 to have a base address of
0x00001234 56789000
Figure 5–7. Address Translation in TX and RX Directions For Endpoints
Transaction,
Data Link,
and PHY
DMA
Cntrl
On-
Chip
Mem
Avalon-MM
Byte Address
Avalon-MM
Byte Address
Avalon-MM
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
Fabric
Avalon-MM Ha
r
d IP fo
r
PCI Exp
r
ess End Poin
t
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[5]
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
RX_BAR0
Mas
t
e
r
RX_BAR5
Mas
t
e
r
= TX Avalon-MM Slave
S
BAR[0]
S
S