PI7C7300D Datasheet, PDF (22/107 Pages) Pericom Semiconductor Corporation – 3-PORT PCI-to-PCI BRIDGE

PI7C7300D
3-PORT PCI-TO-PCI BRIDGE
As indicated in Table 4-1, the following PCI commands are not supported by
PI7C7300D:
PI7C7300D never initiates a PCI transaction with a reserved command code and, as
a target, PI7C7300D ignores reserved command codes.
PI7C7300D does not generate interrupt acknowledge transactions. PI7C7300D
ignores interrupt acknowledge transactions as a target.
PI7C7300D does not respond to special cycle transactions. PI7C7300D cannot
guarantee delivery of a special cycle transaction to downstream buses because of the
broadcast nature of the special cycle command and the inability to control the
transaction as a target. To generate special cycle transactions on other PCI buses,
either upstream or downstream, Type 1 configuration write must be used.
PI7C7300D neither generates Type 0 configuration transactions on the primary PCI
bus nor responds to Type 0 configuration transactions on the secondary PCI buses.
4.2
SINGLE ADDRESS PHASE
A 32-bit address uses a single address phase. This address is driven on P_AD[31:0], and
the bus command is driven on P_CBE[3:0]. PI7C7300D supports the linear increment
address mode only, which is indicated when the lowest two address bits are equal to zero.
If either of the lowest two address bits is nonzero, PI7C7300D automatically disconnects
the transaction after the first data transfer.
4.3
DUAL ADDRESS PHASE
A 64-bit address uses two address phases. The first address phase is denoted by
the asserting edge of FRAME#. The second address phase always follows on the
next clock cycle.
For a 32-bit interface, the first address phase contains dual address command code on the
C/BE#[3:0] lines, and the low 32 address bits on the AD[31:0] lines. The second address
phase consists of the specific memory transaction command code on the C/BE#[3:0]
lines, and the high 32 address bits on the AD[31:0] lines. In this way, 64-bit addressing
can be supported on 32-bit PCI buses.
The PCI-to-PCI Bridge Architecture Specification supports the use of dual address
transactions in the prefetchable memory range only. See Section 5.3.2 for a discussion of
prefetchable address space. The PI7C7300D supports dual address transactions in both
the upstream and the downstream direction. The PI7C7300D supports a programmable
64-bit address range in prefetchable memory for downstream forwarding of dual address
transactions. Dual address transactions falling outside the prefetchable address range are
forwarded upstream, but not downstream. Prefetching and posting are performed in a
manner consistent with
the guidelines given in this specification for each type of memory transaction in
prefetchable memory space.
Pericom Semiconductor
Page 22 of 107
November 2005 - Revision 1.01