PM Features in Linux - 2022.1 English

Versal ACAP System Software Developers Guide (UG1304)

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2022.1 English
Note: Arm® AArch64 architecture is common between Zynq UltraScale+ MPSoC APU and the Versal® ACAP APU. The existing architectural reference nomenclature found in the Linux source also applies to Versal devices.

Linux executes at EL1, and the communication between Linux and the TF-A software layer is realized using SMC calls. Power management features based on the EEMI API have been ported to the Linux kernel, ensuring that the Linux-centric power management features use the EEMI services provided by the PMC. Additionally, the EEMI API can be accessed directly via debugfs for debugging purposes. Note that direct access to the EEMI API through debugfs will interfere with the kernel power management operations and may cause unexpected problems. All the Linux power management features presented in this chapter are available in the PetaLinux default configuration.