Cypress S6J3200 Series, Manual

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CHAPTER 31:Memory Protection Unit for AXI
S6J3200 Series Hardware Manual Document Number: 002-04852 Rev. *G 1141
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MPU Priority Decision
MPU AXI provides start address and end address for each region. Start address specifies the first
address of the region and end address specifies the last address of the region. It is allowed in MPU AXI
that the region may overlap each other. Hence it is also possible that an AXI transaction address may
match with multiple regions.
For AXI protocol transaction following scenarios are possible.
2.
Lowest address and highest address might fall in the same region.
3.
Lowest address might match in one region, but highest address might match in some other region.
4.
Scenario mentioned in point 1 here, happens for multiple regions due to region overlapping.
5.
Scenario mentioned in point 2 here, happens for multiple regions due to region overlapping.
Figure 3-2 Example Region Overlapping
MPU AXI finds region match signals based on lowest address of AXI burst transaction and also separate
region match signals based on highest address. Due to overlapping of regions it is possible lowest
address and/or highest address may match with multiple regions.
MPU AXI supports upto eight regions. Each region is identified as region 1, region 2, region 3, and so on
upto region 8. Region 8 is given highest priority, region 7 has second highest priority, and so on with
region 1 as the second lowest priority region. Background region is the lowest priority region.
Whenever the AXI transaction lowest address matches with multiple regions the permissions
corresponding to the highest priority (among all matching region) region is applied. Similarly, if AXI
MPUXn_SADDR1:ADDR
MPUXn_SADDR2:ADDR
MPUXn_EADDR1:ADDR
MPUXn_EADDR2:ADDR
Legends
Region 1
Region 2
Region 1, Region 2 overlapping