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
 Routing Interface registersRegister definitions for the STM32L1xx Routing Interface
 ADClibopencm3 STM32L1xx Analog to Digital Converters
 CRClibopencm3 STM32L1xx CRC
 DMAlibopencm3 STM32L1xx DMA
 FLASHlibopencm3 STM32L1xx FLASH
 RCClibopencm3 STM32L1xx Reset and Clock Control
 USARTlibopencm3 STM32L1xx USART
 STM32L1xx DefinesDefined Constants and Types for the STM32L1xx series
 SYSCFG DefinesDefined Constants and Types for the STM32L1xx Sysconfig
 RTC DefinesDefined Constants and Types for the STM32L1xx RTC
 CRC Defineslibopencm3 Defined Constants and Types for the STM32L1xx CRC Generator
 DMA DefinesDefined Constants and Types for the STM32L1xx DMA Controller
 SPI DefinesDefined Constants and Types for the STM32L1xx SPI
 RCC DefinesDefined Constants and Types for the STM32L1xx Reset and Clock Control
 USART DefinesDefined Constants and Types for the STM32L1xx USART
 PWR DefinesDefined Constants and Types for the STM32L1xx Power Control
 FLASH DefinesDefined Constants and Types for the STM32L1xx FLASH Memory
 IWDG DefinesDefined Constants and Types for the STM32L1xx Independent Watchdog Timer
 EXTI DefinesDefined Constants and Types for the STM32L1xx External Interrupts
 DAC DefinesDefined Constants and Types for the STM32L1xx DAC
 ADC DefinesDefined Constants and Types for the STM32L1xx Analog to Digital Converters
 LCD DefinesDefined Constants and Types for the STM32L1xx LCD Controller
 Timer Defineslibopencm3 Defined Constants and Types for the STM32L1xx Timers
 I2C DefinesDefined Constants and Types for the STM32L1xx I2C
 GPIO DefinesDefined Constants and Types for the STM32L1xx General Purpose I/O
 User interrupt service routines (ISR) prototypes for STM32 L1 series
 DebuggingMacros and functions to aid in debugging
 NVIC Defineslibopencm3 Cortex Nested Vectored Interrupt Controller
 User interrupts for STM32 L1 series
 Cortex M0/M3/M4 System InterruptsIRQ numbers -3 and -6 to -9 are reserved
 SysTick Defineslibopencm3 Defined Constants and Types for the Cortex SysTick
 Clock source selection
 USB DefinesDefined Constants and Types for the STM32F* USB drivers
 USB DriversDefined Constants and Types for the USB Drivers
 USB Standard Structure DefinitionsDefined Constants and Types for the USB Standard Structure Definitions
 User interrupt service routines (ISR) defaults for STM32 L1 series
 NVIClibopencm3 Cortex Nested Vectored Interrupt Controller
 SysTicklibopencm3 Cortex System Tick Timer
 Generic USB DriversGeneric USB Drivers
 Generic USB Control RequestsGeneric USB Control Requests
 Generic USB Standard Request InterfaceGeneric USB Standard Request Interface
 Dac_file
 Gpio_file
 I2c_file
 Iwdg_file
 Pwr_file
 Rtc_file
 Spi_file
 Timer_file