openocd supports the new STM32L0 family of very low-power Cortex-M0+ parts from ST. The common dev kits for them are the Discovery and Nucleo boards which can both use the stm32l0discovery.cfg file introduced in this commit. Your openocd.cfg can just be:

source [find board/stm32l0discovery.cfg]

This pulls in the STLink-v2.1 driver as well the the relevant target settings.

I refactored the STM32Lx flash driver a while back – this commit so you can reflash your STM32L0 in openocd like you would expect. The STM32L0 flash controller is very similar to the STM32L1 but has a few geometry differences.