C.H.I.P is a small $9 Linux SBC with onboard eMMC, bluetooth, wireless and LIPO battery charger. This can provide an all in one gateway device. There is also the PocketCHIP which puts the C.H.I.P, small screen, battery and keyboard in a small case.
At present the standard kernels don't appear to provide SPI access, however there are community kernels and device tree's that will enable SPI.
Currently the only tested code is Mikes C++ code initially written for the Pi UKHasNET-PiNode from GitHub. The only change needed for use on the CHIP was to change the SPI device used in the config file.
Depending on the Libraries used other code written for the Pi may work.