
Altera Corporation User Guide Version 11.1 3–27
October 2011
Functional Description
PCI Bus
Commands
Table 3–11 shows the PCI bus commands that can be initiated or
responded to by the PCI MegaCore functions.
During the address phase of a transaction, the cben[3..0] bus is used
to indicate the transaction type (Table 3–11).
The PCI MegaCore functions respond to standard memory read/write,
cache-line memory read/write, I/O read/write, and configuration
read/write commands. The bus commands are discussed in greater detail
in “Target Mode Operation” on page 3–44 and “Master Mode Operation”
on page 3–88.
Table 3–11. PCI Bus Command Support Summary
cben[3..0] Value Bus Command Cycle Master Target
0000
Interrupt acknowledge No Yes (1)
0001
Special cycle No Ignored
0010
I/O read Yes Yes
0011
I/O write Yes Yes
0100
Reserved Ignored Ignored
0101
Reserved Ignored Ignored
0110
Memory read Yes Yes
0111
Memory write Yes Yes
1000
Reserved Ignored Ignored
1001
Reserved Ignored Ignored
1010
Configuration read Yes Yes
1011
Configuration write Yes Yes
1100
Memory read multiple (2) Ye s Ye s
1101
Dual address cycle (DAC) Yes (3) Ye s (3)
1110
Memory read line (2) Ye s Ye s
1111
Memory write and invalidate (2) Ye s Ye s
Notes to Ta b le 3 – 11 :
(1) Interrupt acknowledge support can be enabled on the Advanced PCI MegaCore
Function Features page of the Parameterize - PCI Compiler wizard. When
support is enabled, the target accepts the interrupt acknowledge command and
aliases it as a memory read command.
(2) The memory read multiple and memory read line commands are treated as
memory reads. The memory write and invalidate command is treated as a
memory write. The local side sees the exact command on the l_cmdo[3..0] bus
with the encoding shown in Table 3–11.
(3) This command is not supported by the pci_mt32 and pci_t32 MegaCore
functions.
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