ARM System Control and Management Interface (SCMI) protocol is a
set of operating system-independent software interfaces that are
used in system management. SCMI is extensible and currently provides
interfaces for: Discovery and self-description of the interfaces
it supports, Power domain management which is the ability to place
a given device or domain into the various power-saving states that
it supports, Performance management which is the ability to control
the performance of a domain that is composed of compute engines
such as application processors and other accelerators, Clock
management which is the ability to set and inquire rates on platform
managed clocks and Sensor management which is the ability to read
sensor data, and be notified of sensor value.

This protocol library provides interface for all the client drivers
making use of the features offered by the SCMI.

source code:

drivers/firmware/arm_scmi/