The RRAM memory can be divided into several regions and these regions can be configured to restrict accesses.
Each region is configured using the REGION[n].ADDRESS and REGION[n].CONFIG registers.
When the region write-once feature is enabled, writes to a 32-bit words in the region are allowed only when the current data is 0xFFFFFFFF, else the writes are ignored.
When the region configuration registers are writable, the region configuration registers can be updated until the lock bit is set to Enabled. However, the register fields Secure, Read, Write, amd Execute can be written to 0, even if the lock bit is set to Enabled.
After changing the region protecton, CACHE must be invalidated to stay coherent with the updated RRAM configuration. Failure to do so will cause unpredictable results, such as being able to read cached content from a memory region that was just configured to be non-readable.