PI7C8152BMAE Pericom Semiconductor, PI7C8152BMAE Datasheet - Page 57

• Manufacturer Part Number: PI7C8152BMAE
• Description: IC PCI-PCI BRIDGE 2PORT 160-MQFP
• Manufacturer: Pericom Semiconductor

Specifications of PI7C8152BMAE

• Applications: *
• Interface: *
• Voltage - Supply: *
• Package / Case: 160-MQFP, 160-PQFP
• Mounting Type: Surface Mount
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: 0 C
• Mounting Style: SMD/SMT
• Operating Supply Voltage: 3 V to 3.6 V
• Supply Current (max): 246 mA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

7
7.1
7.2
7.2.1
EXCLUSIVE ACCESS
This chapter describes the use of the LOCK_L signal to implement exclusive access to a
target for transactions that cross PI7C8152x.
CONCURRENT LOCKS
The primary and secondary bus lock mechanisms operate concurrently except when
a locked transaction crosses PI7C8152x. A primary master can lock a primary target
without affecting the status of the lock on the secondary bus, and vice versa. This means
that a primary master can lock a primary target at the same time that a secondary master
locks a secondary target.
ACQUIRING EXCLUSIVE ACCESS ACROSS PI7C8152x
For any PCI bus, before acquiring access to the LOCK_L signal and starting a series of
locked transactions, the initiator must first check that both of the following conditions are
met:
!
!
The initiator leaves the LOCK_L signal de-asserted during the address phase and asserts
LOCK_L one clock cycle later. Once a data transfer is completed from the target, the target
lock has been achieved.
LOCKED TRANSACTIONS IN DOWNSTREAM DIRECTION
Locked transactions can cross PI7C8152x only in the downstream direction, from the
primary bus to the secondary bus.
When the target resides on another PCI bus, the master must acquire not only the lock on
its own PCI bus but also the lock on every bus between its bus and the target’s bus. When
PI7C8152x detects on the primary bus, an initial locked transaction intended for a target on
the secondary bus, PI7C8152x samples the address, transaction type, byte enable bits, and
parity, as described in Section 3.7.4. It also samples the lock signal. If there is a lock
established between 2 ports or the target bus is already locked by another master, then the
current lock cycle is retried without forward. Because a target retry is signaled to the
initiator, the initiator must relinquish the lock on the primary bus, and therefore the lock is
not yet established.
The first locked transaction must be a memory read transaction. Subsequent locked
transactions can be memory read or memory write transactions. Posted memory write
transactions that are a part of the locked transaction sequence are still posted. Memory read
transactions that are a part of the locked transaction sequence are not pre-fetched.
The PCI bus must be idle.
The LOCK_L signal must be de-asserted.
Page 57 of 90
2-PORT PCI-TO-PCI BRIDGE
October 16, 2003 – Revision 1.11
ADVANCE INFORMATION
PI7C8152A & PI7C8152B