System Control Module (SCM)
MCF52235 ColdFire® Integrated Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor
13-11
If MPARK[TIMEOUT] is set, a counter increments for each master for every cycle it is denied access.
When a counter reaches the limit set by MPARK[LCKOUT_TIME], the arbitration algorithm is changed
to round-robin arbitration mode until all locks are cleared. The arbitration then returns to fixed mode and
the highest priority master is granted the bus.
As in round-robin mode, if no masters are requesting, the arbitration pointer parks on the highest priority
master if MPARK[PRK_LAST] is set or parks on the master whose last requested the bus if cleared.
13.6.3
Bus Master Park Register (MPARK)
The MPARK controls the operation of the system bus arbitration module. The platform bus master
connections are defined as the following:
•
Master 2 (M2): 4-channel DMA
•
Master 3 (M3): Fast Ethernet controller (FEC)
•
Master 0 (M0): V2 ColdFire Core
IPSBAR
Offset: 0x001C (MPARK)
Access: read/write
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
R
0
0
0
0
0
0
M2_
P_EN
BCR
24BIT
M3_PRTY
M2_PRTY
M0_PRTY
0
0
W
Reset
0
0
1
1
0
0
0
0
1
1
1
0
0
0
0
1
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R
0
FIXED
TIME
OUT
PRK
LAST
LCKOUT_TIME
0
0
0
0
0
0
0
0
W
Reset
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Figure 13-7. Default Bus Master Park Register (MPARK)
Table 13-6. MPARK Field Descriptions
Field
Description
31–26
Reserved, should be cleared.
25
M2_P_EN
DMA bandwidth control enable
0 Disable the use of the DMA's bandwidth control to elevate the priority of its bus requests.
1 Enable the use of the DMA's bandwidth control to elevate the priority of its bus requests.
24
BCR24BIT
Enables the use of 24 bit byte count registers in the DMA module
0 DMA BCRs function as 16 bit counters.
1 DMA BCRs function as 24 bit counters.
23–22
M3_PRTY
Master priority level for master 3 (FEC)
00 Fourth (lowest) priority
01 Third priority
10 Second priority
11 First (highest) priority
Because
of
an
order
from
the
United
States
International
Trade
Commission,
BGA-packaged
product
lines
and
part
numbers
indicated
here
currently
are
not
available
from
Freescale
for
import
or
sale
in
the
United
States
prior
to
September
2010:MCF52234CVM60,
MCF52235CVM60