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Architecture
Table 5-3. Device Master Settings
Master
Privilege ID
Privilege Level
Access Type
EDMA3_0_CC0
Inherited
Inherited
DMA
EDMA3_0_TC0 and EDMA3_0_TC1
Inherited
Inherited
DMA
EDMA3_1_CC0
Inherited
Inherited
DMA
EDMA3_1_TC0
Inherited
Inherited
DMA
ARM (instruction access)
0
Software dependant
Instruction
ARM (data access)
0
Software dependant
Data
EMAC
4
Supervisor
Data/DMA
USB2.0
6
Supervisor
DMA
5.2.2 Memory Protection Ranges
NOTE:
In some cases the amount of physical memory in actual use may be less than the maximum
amount of memory supported by the device. For example, the device may support a total of
512 Mbytes of SDRAM memory, but your design may only populate 128 Mbytes. In such
cases, the unpopulated memory range must be protected in order to prevent
unintended/disallowed aliased access to protected memory. One of the programmable
address ranges could be used to detect accesses to this unpopulated memory.
The MPU divides its assigned memory into address ranges. Each MPU can support one fixed address
range and multiple programmable address ranges. The fixed address range is configured to an exact
address. The programmable address range allows software to program the start and end addresses.
Each address range has the following set of registers:
•
Range start and end address registers (MPSAR and MPEAR): Specifies the starting and ending
address of the address range.
•
Memory protection page attribute register (MPPA): Use to program the permission settings of the
address range.
It is allowed to configure ranges such that they overlap each other. In this case, all the overlapped ranges
must allow the access, otherwise the access is not allowed. The final permissions given to the access are
the lowest of each type of permission from any hit range.
Addresses not covered by a range are either allowed or disallowed based on the configuration of the
MPU. The MPU can be configured for assumed allowed or assumed disallowed mode as dictated by the
ASSUME_ALLOWED bit in the configuration register (CONFIG).
5.2.3 Permission Structures
The MPU defines a per-range permission structure with three permission fields in a 32-bit permission
entry.
shows the structure of a permission entry.
Figure 5-2. Permission Fields
31
22
21
20
19
18
17
16
Reserved
Allowed IDs
AID11
AID10
AID9
AID8
AID7
AID6
15
14
13
12
11
10
9
8
6
5
4
3
2
1
0
Allowed IDs
Reserved
Access Types
AID5
AID4
AID3
AID2
AID1
AID0
AIX
SR
SW
SX
UR
UW
UX
40
Memory Protection Unit (MPU)
SPRUGX5A
–
May 2011
Copyright
©
2011, Texas Instruments Incorporated
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