ATF Application Binary Interface - 2020.2 English

Versal ACAP System Software Developers Guide (UG1304)

Document ID
Release Date
2020.2 English

All APU executable layers below EL3 might indirectly communicate with the PMC through ATF. The ATF receives all calls made from the lower ELs, consolidates all requests, and sends the requests to the PMC.

Following ArmĀ® 's SMC calling convention, the PM communication from the non-secure world to the ATF is organized as SiP Service Calls, using a predefined SMC function identifier and SMC sub-range ownership.

The EEMI API implementation for the APU is compliant only with the SMC64 calling convention. EEMI API calls made from the hypervisor, secure OS, or OS and pass the 32-bit API ID as the SMC Function Identifier, and up to four 32-bit arguments as well. As all PM arguments are 32-bit values, pairs of two are combined into one 64-bit value.

ATF returns up to five 32-bit return values:

  • Return status, either success or error and reason
  • Additional information from the PM controller