L-Bus to U-Bus Interface (L2U)
MPC561/MPC563 Reference Manual, Rev. 1.2
11-12
Freescale Semiconductor
•
The L2U does not provide show cycle for any L-bus addresses that fall in the L-bus CALRAM
address space if the CALRAM protection [SP] bit is set in the L2U_MCR.
summarizes the L2U show cycle support.
11.8
L2U Programming Model
The L2U control registers control the L2U bus interface and the DMPU. They are accessible via the mtspr
and mfspr instructions. They are also accessible by an external master when EMCR[CONT] bit is cleared.
L2U control registers are accessible from both the L-bus side and the U-bus side in one clock cycle. As
with all SPRs, L2U registers are accessible in supervisor mode only.
Any unimplemented bits in L2U registers return 0’s on a read, and the writes to those register bits are
ignored.
shows L2U registers along with their SPR numbers and hexadecimal addresses that are used to
access L2U registers during a peripheral mode access.
.
Table 11-4. L2U Show Cycle Support Chart
Case
Destination
LB AACK
LB ABORT
Comments
1
L-bus Slave
1
1
L-bus slave includes all address in the L-bus address space.
No
X
2
2
X indicates don’t care conditions.
Not show cycled
[Cycle will be retried one clock later]
3
3
There will be a 1-clock turnaround because the L-bus retry information is not available in time to
negate the L-bus arbitration.
2
L2U
4
4
L2U indicates L2U registers.
X
X
Not show cycled
3
U-bus/E-bus
5
5
U-bus/E-bus refers to all destinations through the L2U interface.
X
X
Not show cycled
4
L-bus slave
1
Yes
No
Show cycled
5
L-bus slave
1
Yes
Yes
Not show cycled
[L-bus will be released next clock]
Table 11-5. L2U (PPC) Register Decode
Name
SPR #
SPR[5:9]
SPR[0:4]
Address for
External Master
Access
1
Access
Description
L2U_MCR
568
10001
11000
0x0000_3110
SUPR
L2U Module Configuration Register
L2U_RBA0
792
11000
11000
0x0000_3180
SUPR
Region Base Address Register 0
L2U_RBA1
793
11000
11001
0x0000_3380
SUPR
Region Base Address Register 1
L2U_RBA2
794
11000
11010
0x0000_3580
SUPR
Region Base Address Register 2
L2U_RBA3
795
11000
11011
0x0000_3780
SUPR
Region Base Address Register 3
L2U_RA0
824
11001
11000
0x0000_3190
SUPR
Region Attribute Register 0
L2U_RA1
825
11001
11001
0x0000_3390
SUPR
Region Attribute Register 1
Summary of Contents for MPC561
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