Altera Embedded Peripherals IP - Manual (Page 140)

All PCI read transactions are completed as delayed reads. However, only one delayed read is accepted and
processed at a time.
PCI-to-Avalon Address Translation
The bits in the PCI address that are used in the BAR matching process are replaced by an Avalon-MM
base address that is specific to that BAR.
Figure 14-2: PCI-to-Avalon Address Translation
Avalon_Addr_B0
Avalon Address PCI Address
High Low
Hardcoded BAR Specific
Avalon Addresses
Matched BAR
Selects Avalon
Addresses
Inside PCI Lite Core
BAR Specific Number
of High Avalon Bits
N = Number of Pass Thro ugh Bits (BAR Specific)
M = Number of Avalon Address Bits
P = Number of PCI Address Bits (64/32)
Low Address Bits Unchanged
(BAR Specific Number of Bits)
Avalon_Addr_B1
Avalon_Addr_B2
0 N-1 M-1 N
High Low
0 P-1 N N-1
BAR0
BAR1
BAR2
Avalon-to-PCI Address Translation
Avalon-to-PCI address translation is done through a translation table. Low order Avalon-MM address
bits are passed to PCI unchanged; higher order Avalon-MM address bits are used to index into the
address translation table. The value found in the table entry is used as the higher order PCI address bits.
Figure 14-3: Avalon-to-PCI Address Translation
Avalon Address PCI Address
High Low
N = Number of Pass Thro ugh Bits
M = Number of Avalon Address Bits
P = Number of PCI Address Bits
Q = Number of Translation Ta ble Entries
Sp = Space Indication
for Each Ent ry
Low Address Bits Unchanged
Avalon to PCI Address
Translation Ta ble
(Q Entries by P-N Bits wide)
PCI Address from Ta ble Entry
Used as High PCI Address Bits
Space Indication
Ta ble Updates via
Control Register Port
High Avalon Address
Bits Index Ta ble
PCI Address 0 Sp0
PCI Address 1 Sp1
PCI Address Q- 1 SpQ-1
0 N-1 M-1 N
High Low
0 P-1 N N-1
The address size selections in the translation table determine both the number of entries in the Avalon-to-
PCI address translation table, and the number of bits that are passed through the transaction table
unchanged.
14-6 PCI-to-Avalon Address Translation
UG-01085
2014.24.07
Altera Corporation PCI Lite Core
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