External Bus Interface
MOTOROLA MPC823e REFERENCE MANUAL 13-39
EXTERNAL BUS
13
INTERFACE
The reservation protocol for a single-level (local) bus is illustrated in Figure 13-26. It
assumes that external logic on the bus performs the following functions:
• Snoops accesses to all local bus slaves
• Holds one reservation for each local master capable of storage reservations
• Sets the reservation when that master issues a load and reserve request
• Clears the reservation when some other master issues a store to the reservation
address
Figure 13-26. Reservation On Local Bus
S
R
RESERVATION
LOGIC
EXTERNAL BUS
INTERFACE
lwarx
Q
ENABLE
EXTERNAL stwcx ACCESS
E-BUS
MPC823e
MASTER
BUS
A[6:31]
CLKOUT
AT[0:3], RSV
,R/W,TS
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