targets.json was not specifying the same macro name as the code was
checking for, so setting was ineffective.
Making this work tripped up not-supported checks in ARMv8-M - rather than deal
with making this work, support it instead.
Both ARMv7-M and ARMv8-M slightly reduce code size and runtime impact if
mpu-rom-end is 0x1fffffff, using one fewer region.
This means default setup for ARMv8-M now requires 5 regions, with
mpu-rom-end set to default 0x0fffffff, but this can be put back to 4 by
changing the setting.
As we build for a specific CPU, a runtime check for number of MPU
regions in release builds is not worthwhile. Make it an assert only.
Saves a little space in develop images, a lot in release.
Switch to higher-level calls and macros, and fix an error in the ARMv8-M
version - "inner" attributes were not being set correctly due to a
copy/paste error - "outer" was being set twice.
This means RAM would have been marked WTRA rather than WBWA for the
inner cache.
Slightly reduces ARMv7-M init code size by feeding region number
into RBAR instead of using RNR.
Make the following changes:
-Allow a vector specific ARM MPU driver by defining MBED_MPU_CUSTOM
-Allow ROM address to be configured for ARMv7-M devices by
setting the define MBED_MPU_ROM_END
-Add ROM write protection
-Add new functions and lock
-enable at boot
-disable during flash programming
Create a dedicated MPU directory for standard Arm MPU implementations
in preparation for the Arm v8m MPU. Replace MBED_MPU_ENABLED with
DEVICE_MPU to align with the porting layer of other HAL APIs.
Kevin Bracey
Russ Butler