AMDGPU is AMD's new fully open source unified graphics driver for Linux. AMDGPU currently only supports cards built upon GCN 1.2 or higher, previous cards are not supported yet. GCN 1.2 includes Carrizo APUs, the Fury lineup, and the R9 380.
AMDGPU also has an optional closed-source component that operates on top of the open source AMDGPU for better intensive 3D application support known as AMDGPU-PRO.
References
AMDGPU Wikipedia(Text) CC BY-SA