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MPC555
/
MPC556
L-BUS TO U-BUS INTERFACE (L2U)
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
11-13
For these registers a bus cycle will be performed on the L-bus and the U-bus with the
address as shown in
.
.
11.8.1 U-bus Access
The L2U registers are accessible from the U-bus side only if it is a supervisor mode
data access and the register address is correct and it is indicated on the U-bus that it
is a PPC register access.
A user mode access, or an access marked as instruction, to L2U registers from the U-
bus side will cause a data error on the U-bus.
11.8.2 Transaction Size
All L2U registers are defined by PowerPC architecture as being 32-bit registers. There
is no PowerPC instruction to access either a half word or a byte of the special purpose
register. All L2U registers are only word accessible (read and write) in peripheral
mode. A half-word or byte access in peripheral mode will result in a word transaction.
11.8.3 L2U Module Configuration Register (L2U_MCR)
The L2U module configuration register (L2U_MCR) is used to control the L2U module
operation.
Table 11-6 Hex Address For SPR Cycles
A0:17
A18:22
A23:27
A28:31
0
spr0:4
spr5:9
0
L2U_MCR
— L2U Module Configuration Register
SPR 568
MSB
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
SP
LSHOW
RESERVED
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
LSB
31
RESERVED
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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