Coreboot Merges Support For Intel's Arm-Based PSE Offload Engine

As of yesterday Intel's contributed Programmable Services Engine "PSE" support has been merged into mainline Coreboot for supporting this Arm-based dedicated offload engine found within select Intel processors.

The Intel Programmable Services Engine (PSE) is initially found in Elkhart Lake and from the hardware side is an Arm Cortex-M7 micro-controller. The PSE can be used for a variety of tasks while the latest description of it in the Coreboot code describes it as, "independent, low-DMIPS computing and low-speed I/Os for IoT applications, plus dedicated services for real-time computing and time-sensitive synchronization."

With Elkhart Lake the Programmable Services Engine can be used for out-of-band device management, network proxy, EC-Lite functionality, and Intel Sensor Hub support too.

This commit implements the initial Intel PSE support in the codebase with the current focus on the Elkhart Lake platform. After that initial commit was also another patch providing PSE TSN (Time Sensitive Networking) support for the Ethernet controller capabilities.

Previously developers called on Intel to open-source the PSE firmware required for using this dedicated offload engine. Unfortunately, as of writing, the PSE firmware still appears to be a closed-source/binary-only firmware component.