This Gecko SDK Github repository has been discontinued. Updated versions of the SDK can be found here: https://github.com/SiliconLabs/gecko_sdk. Alternatively, download Simplicity Studio and use the Update Software button in the Launcher view to access the latest and previous SDK versions.
Full API documentation is available through docs.silabs.com, and within Simplicity Studio by clicking the Software Documentation tile.
For datasheets, reference manuals and other documentation items, download Simplicity Studio or head over to the document library.