libopencm3
A free/libre/open-source firmware library for various ARM Cortex-M3 microcontrollers.
LPC13
Here is a list of all modules:
[detail level 12]
 LPC13xxLibraries for NXP Semiconductors LPC13xx series
 GPIOlibopencm3 LPC13xx General Purpose I/O
 LPC13xx DefinesDefined Constants and Types for the LPC13xx series
 GPIO DefinesDefined Constants and Types for the LPC13xx General Purpose I/O