3.1.3 Requirements of configuration register reads and writes
Reads and writes to the CCN-502 configuration registers must meet certain requirements.
If the following requirements are not met then this can result in
- All accesses must be of device type, either:
- Device, Strongly Ordered.
- nGnRE, nGnRnE.
- All accesses must have a data size of 32 bits or 64
- All accesses must be natively aligned, that is:
- 32-bit accesses must be aligned to a 32-bit
- 64-bit accesses must be aligned to a 64-bit
- For configuration register writes, all bits, 32 or
64, must be written, that is, all byte lanes must be valid:
- WRSTB must indicate that all bytes lanes are
valid if the write transaction is from an AMBA interface.
- BE must indicate that all byte lanes are
valid if the write transaction is sent from a CHI interface.
- Secure registers can only be accessed by a Secure
access, that is, NS =
registers can be accessed by either a Secure or Non-secure access.