Linaro Connect Bangkok

Most SoC designs today implement a central entity that orchestrates System and Power Management controls. Such an entity may often be referred to as the System Control Processor (SCP), which is often a microcontroller. We use the term SCP to refer to the concept of such an entity throughout the rest of this abstract. The communication interface to the SCP is via transport channels.

The ARM System Control & Management Interface (SCMI) specification v1.0 was designed to provide an industry standard transport independent interface to the SCP to enable system and power management. SCMI enables transport channels to ferry SCMI commands from an agent sitting on a Processing Entity (like an Application Processor) to the SCP. The SCP then decodes and implements the actions described by the SCMI commands. SCMIv1.0 is an already published specification supporting power, performance, clocks, sensors and system state management.

Our presentation will talk about the vision of SCMI to enable a truly scalable Power Management software stack that can work across all compliant devices with minimal modification, with device specific controls resident in firmware. It will talk about evolution of the ARM SCMI Specification and how the next revision of the specification will enable next-generation system designs, especially touching a few key areas as outlined below.

There is a growing requirement in certain segments of the industry to deploy virtualized systems, especially in the automotive domain. We will explain how SCMI can enable Power Management virtualization in such systems and design considerations thereof. We will also introduce the concept of Reset Domains and their Management via SCMI. Currently most Operating Systems manage Device Power, Clock and Performance via various frameworks in order to control a device. We envision a unified way of managing a device via a Device-centric model of Power Management. We will explain how SCMI can enable such a model and simplify current Power Management stacks.

Our presentation will be of interest to people and organizations who are looking to enable scalable Power Management stacks for future devices where multiple Operating Systems may run concurrently in the same SoC, either physically on different Processing Entities, or via Virtualization.