5–20
Chapter 5: IP Core Architecture
Avalon-MM Bridge TLPs
Arria V GZ Hard IP for PCI Express
November 2012
Altera Corporation
Each of the 512 possible entries corresponds to the base address of a PCI Express
memory segment of a specific size. The segment size of each entry must be identical.
The total size of all the memory segments is used to determine the number of address
MSB to be replaced. In addition, each entry has a 2-bit field,
Sp[1:0]
, that specifies 32-
bit or 64-bit PCI Express addressing for the translated address. Refer to
. The most significant bits of the Avalon-MM address are used by the
interconnect fabric to select the slave port and are not available to the slave. The next
most significant bits of the Avalon-MM address index the address translation entry to
be used for the translation process of MSB replacement.
For example, if the core is configured with an address translation table with the
following attributes:
■
Number of Address Pages
—
16
■
Size of Address Pages
—
1 MByte
■
PCI Express Address Size
—
64 bits
then the values in
are:
■
N
= 20 (due to the 1 MByte page size)
■
Q
= 16 (number of pages)
■
M
= 24 (20 + 4 bit page selection)
■
P
= 64
In this case, the Avalon address is interpreted as follows:
■
Bits [31:24] select the TX slave module port from among other slaves connected to
the same master by the system interconnect fabric. The decode is based on the base
addresses assigned in Qsys.
■
Bits [23:20] select the address translation table entry.
■
Bits [63:20] of the address translation table entry become PCI Express address bits
[63:20].
■
Bits [19:0] are passed through and become PCI Express address bits [19:0].
The address translation table is dynamically configured at run time. The address
translation table is implemented in memory and can be accessed through the CRA
slave module. Dynamic configuration is optimal in a typical PCI Express system
where address allocation occurs after BIOS initialization.
For more information about how to access the dynamic address translation table
through the CRA slave, refer to the
“Avalon-MM-to-PCI Express Address Translation