libopencm3
A free/libre/open-source firmware library for various ARM Cortex-M3 microcontrollers.
STM32L1
Here is a list of all modules:
[detail level 1234]
 STM32L1xxLibraries for ST Microelectronics STM32L1xx series
 ADClibopencm3 STM32L1xx Analog to Digital Converters
 CRClibopencm3 STM32L1xx CRC
 DAClibopencm3 STM32L1xx DAC
 DMAlibopencm3 STM32L1xx DMA
 FLASHlibopencm3 STM32L1xx FLASH
 GPIOlibopencm3 STM32L1xx General Purpose I/O
 I2Clibopencm3 STM32L1xx I2C
 IWDGlibopencm3 STM32L1xx Independent Watchdog Timer
 RCClibopencm3 STM32L1xx Reset and Clock Control
 RTClibopencm3 STM32L1xx RTC
 SPIlibopencm3 STM32L1xx SPI
 Timerslibopencm3 STM32L1xx Timers
 USARTlibopencm3 STM32L1xx USART
 STM32L1xx DefinesDefined Constants and Types for the STM32L1xx series
 ADC DefinesDefined Constants and Types for the STM32L1xx Analog to Digital Converters
 CRC Defineslibopencm3 Defined Constants and Types for the STM32L1xx CRC Generator
 DAC DefinesDefined Constants and Types for the STM32L1xx DAC
 DMA DefinesDefined Constants and Types for the STM32L1xx DMA Controller
 EXTI DefinesDefined Constants and Types for the STM32L1xx External Interrupts
 FLASH DefinesDefined Constants and Types for the STM32L1xx FLASH Memory
 GPIO DefinesDefined Constants and Types for the STM32L1xx General Purpose I/O
 I2C DefinesDefined Constants and Types for the STM32L1xx I2C
 IWDG DefinesDefined Constants and Types for the STM32L1xx Independent Watchdog Timer
 LCD DefinesDefined Constants and Types for the STM32L1xx LCD Controller
 PWR DefinesDefined Constants and Types for the STM32L1xx Power Control
 RCC DefinesDefined Constants and Types for the STM32L1xx Reset and Clock Control
 RTC DefinesDefined Constants and Types for the STM32L1xx RTC
 SPI DefinesDefined Constants and Types for the STM32L1xx SPI
 SYSCFG DefinesDefined Constants and Types for the STM32L1xx Sysconfig
 Timer Defineslibopencm3 Defined Constants and Types for the STM32L1xx Timers
 USART DefinesDefined Constants and Types for the STM32L1xx USART
 USB DefinesDefined Constants and Types for the STM32F* USB drivers
 Pwr_file