Intel has been working towards Broadwell Linux support but there hasn't been any big code drops yet of Broadwell enablement within the Intel DRM / Mesa / xf86-video-intel. However, today by Intel's Imre Deak were a new set of eight patches implementing support for multiple power wells -- with Haswell there is just one dynamic well. "This patchset adds support for multiple dynamic power wells needed by
HW generations so far had only one always-on power well and optionally one dynamic power well. Upcoming HW gens may have multiple dynamic power wells, so add some infrastructure to support them.
The idea is to keep the existing power domain API used by the rest of the driver and create a mapping between these power domains and the underlying power wells. This mapping can differ from one HW to another but high level driver code doesn't need to know about this. Through the existing get/put API it would just ask for a given power domain and the power domain framework would make sure the relevant power wells get enabled in the right order.
The patch series can be found on intel-gfx.