K60P100M100SF2RM Datasheet, PDF (394/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Functional Description
18.4.1.1 Hit Determination
To determine if the current reference hits in the given region, two magnitude comparators
are used with the region's start and end addresses. The boolean equation for this portion
of the hit determination is:
region_hit = ((addr[31:5] >= RGDn_Word0[SRTADDR]) & (addr[31:5] <= RGDn_Word1[ENDADDR])) &
RGDn_Word3[VLD]
where addr is the current reference address, RGDn_Word0[SRTADDR] and
RGDn_Word1[ENDADDR] are the start and end addresses, and RGDn_Word3[VLD] is
the valid bit.
NOTE
The MPU does not verify that ENDADDR ≥ SRTADDR.
18.4.1.2 Privilege Violation Determination
While the access evaluation macro is determining region hit, the logic is also evaluating
if the current access is allowed by the permissions defined in the region descriptor. Using
the master and supervisor/user mode signals, a set of effective permissions is generated
from the appropriate fields in the region descriptor. The protection violation logic then
evaluates the access against the effective permissions using the specification shown
below.
Table 18-80. Protection Violation Definition
Description
MxUM
r
w
x
Protection
Violation?
Instruction fetch read
Data read
Data write
—
—
0
—
—
1
0
—
—
1
—
—
—
0
—
—
1
—
Yes, no execute permission
No, access is allowed
Yes, no read permission
No, access is allowed
Yes, no write permission
No, access is allowed
18.4.2 Putting It All Together and Error Terminations
For each slave port monitored, the MPU performs a reduction-AND of all the individual
terms from each access evaluation macro. This expression then terminates the bus cycle
with an error and reports a protection error for three conditions:
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
394
Freescale Semiconductor, Inc.