Revision 5.03 – June 14, 2006
S5320 – PCI Match Maker: PCI Bus Protocol
Data Sheet
Figure 50. Engaging the LOCK# Signal
1
2
3
4
5
PCLK
(I)
FRAME#
LOCK#
AD[31:0]
(T
(I)
(I)
)
Address
Data
IRDY#
(T)
TRDY#
DEVSEL#
(T)
LOCK
MECHANISM
AVAILABLE
UPON FIRST
ACCESS
TARGET
BECOMES
LOCKED
(I) Driven by Initiator
(T) Driven by Target
BUS
IDLE
LOCK MECHANISM
AVAILABLE
LOCK
ESTABLISHED
LOCK
MAINTAINED
Table 42. Target Termination Type
Termination
Disconnect
Retry
DEVSEL#
STOP#
TRDY#
on
Comment
on
on
off
on
on
on
Data is transferred. Transaction needs to be re-initiated to complete.
Data was not transferred. Transaction should be tried later.
Data was not transferred. Fatal error.
off
Abort
off
Targets selected with LOCK# deasserted during the
assertion of FRAME# (clock period 1 of Figure 50),
which encounter the assertion of LOCK# during the
following clock (clock period 2 of Figure 50) are there-
after considered “locked.” A target, once locked,
requires that subsequent accesses to it deassert
LOCK# while FRAME# is asserted. Figure 51 shows a
subsequent access to a locked target by the master
which locked it. Because LOCK# is owned by a single
master, only that master is able to deassert it at the
beginning of a transaction (assuming successful
access to the locked target). A locked target can only
be unlocked during the clock period following the last
data transfer of a transaction when the LOCK# signal
is deasserted.
An unlocked target ignores LOCK# when it observes
that LOCK# is already asserted during the first clock
period of a transaction. This allows other masters to
access other (unlocked) targets. If an access to a
locked target is attempted by a master other than the
one that locked it, the target responds with a retry
request, as shown in Figure 52.
The S5320 responds to and supports bus masters
which lock it as a target.
96
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