I have created an initial version of a customizable framebuffer driver for WS2812B and APA102 (untested) RGBLed strings
connected to SPI via a 74HCT125 acting as a level translator.
I am currently cleaning up the code and trying to get it upstreamed and into the official foundation kernels.
If anyone is interrested: here the code on git-hub:
Please look at the wiki page for how to configure it - note that it is compiled as an external module, so you have to have the kernel built yourself before you can compile this module...