12.2.2 Peripherals Security Attribution

Security configurations related to the peripherals are handled by the PAC Controller.

Each peripheral can only be configured either in Secure or in Non-Secure mode except the IDAU peripheral which is always Secured.

The security configuration (Secure or Non-Secure) is propagated to each individual peripheral, thus it is the responsibility of the peripheral to grant or not the access with the following rules:

  • If the peripheral is configured as Non-Secure in the PAC:
    • Secure and Non-Secure accesses are granted
  • If the peripheral is configured as Secure in the PAC:
    • Secure access is granted
    • Non-Secure access is discarded (Write is ignored, read 0x0), a PAC error is triggered
      Important: These rules do not apply to the specific peripherals called Mix-Secure peripherals.
Note: The Secure application will usually provide an API for the Non-Secure application using the Non-Secure Callable region (NSC) to allow the Non-Secure application to request specific resources.
Table 12-2. Peripheral PAC Security Attribution (Excluding Mix-Secure Peripherals)
ModeSecure Host AccessNon-Secure Host Access
Non-SecureRead/WriteRead/Write
SecureRead/WriteDiscarded (Write ignored/Read 0x0)

PAC Error is generated

Important: Refer to “Memory and Peripheral Security Configurations” section for more details on the programming of NONSECA, NONSECB, and NONSECC parameters.