19.12.2 Security Types of SDMMC System Bus Clients

The SDMMC user interface is connected as a system bus client, and must be configured as Internal Securable to Peripheral (ISP).

Each region in the “Internal Securable to Peripheral” client type must be programmed with the following characteristics:

• The region must be programmed to be entirely secure or entirely non-secure. This is done with:
  • The split offset must be equal to the maximum size of 128 Mbytes so that the whole peripheral user interface is in the low area below the split. Code sample: MATRIX_SASSRx.SASPLITy = 0xF
  • The bits WRNSECH and RDNSECH must be set respectively to 0=”write secured” and 0=”read secured”. Code sample: MATRIX_SSRx.WRNSECHy = 0; MATRIX_SSRx.RDNSECHy = 0;
  • To set the peripheral to “secure”: the bit LANSECHy must be set to 0 (low area according to RDNSECH0 and WRNSECH0, hence secure).
  • To set the peripheral to “non-secure”: the bit LANSECHy must be set to 1 (low area is non-secure).
    Note: The MATRIX_SRTSRx register is not applicable for the “Internal Securable to Peripheral” type.
• The Security Peripheral Select registers (MATRIX_SPSELRx) must be set to the same security attributes for the corresponding Peripheral identifiers: MATRIX_SPSELRx.NSECPy.