Steppe Eagle is the codename for AMD's new embedded G-Series SoC that arrived this summer. Steppe Eagle boasts a TDP as little as five Watts and is a big upgrade over earlier G-Series hardware. The Steppe Eagle SoC features GCN-based Radeon graphics while the CPU is Jaguar-based and similar to Kabini. As of today, basic support for these latest-generation AMD embedded SoCs can be found within mainline Coreboot. This Coreboot tooling was done by Sage Electronic Engineering, the firm responsible for much of AMD's involvement in Coreboot.
Hitting mainline Coreboot was the binary PI vendorcode files, Avalon Southbridge support, Northbridge files, and the CPU files for Steppe Eagle. The CPU files also support AMD's Mullins APUs.
It's great to see AMD continuing to support Coreboot (through Sage Engineering) and hopefully we'll see more AMD motherboards and systems supported by this open-source project going forward.