libopencm3
A free/libre/open-source firmware library for various ARM Cortex-M3 microcontrollers.
STM32L0
Here is a list of all modules:
[detail level 1234]
 STM32L0xxLibraries for ST Microelectronics STM32L0xx series
 GPIOlibopencm3 STM32L0xx General Purpose I/O
 RCClibopencm3 STM32L0xx Reset and Clock Control
 STM32L0xx DefinesDefined Constants and Types for the STM32L0xx series
 RCC DefinesDefined Constants and Types for the STM32L0xx Reset and Clock Control
 RCC_AHBENR enable values
 RCC_APB2ENR enable values
 RCC_APB1ENR enable values
 USART DefinesDefined Constants and Types for the STM32L0xx USART
 USART Parity Selection
 USART Tx/Rx Mode Selection
 USART Stop Bit Selection
 USART Hardware Flow Control Selection
 USART Registers
 USART_CR1 Values
 USART_CR2 Values
 Auto baud rate modeABRMOD[1:0]: Auto baud rate mode
 USART_CR3 Values
 USART_GTPR Values
 USART_RTOR Values
 USART_RQR Values
 USART_ISR Values
 USART_ICR Values
 USART_RDR/TDR Values
 PWR DefinesDefined Constants and Types for the STM32L0xx PWR Control
 PVD level selection
 Voltage Scaling Output level selection
 FLASH DefinesDefined Constants and Types for the STM32L0xx Flash memory
 FLASH Wait States
 EXTI DefinesDefined Constants and Types for the STM32L0xx External Interrupts
 ADC DefinesDefined Constants and Types for the STM32L0xx Analog to Digital Converter
 ADC register base addresses
 ADC Channel Numbers
 Timer Defineslibopencm3 Defined Constants and Types for the STM32L0xx Timers
 Timer register base addresses
 TIMx_CR1 CKD[1:0] Clock Division Ratio
 TIMx_CR1 CMS[1:0]: Center-aligned Mode Selection
 TIMx_CR1 DIR: Direction
 TIMx_CR2_OIS: Force Output Idle State Control Values
 TIMx_CR2 MMS[6:4]: Master Mode Selection
 TS Trigger selection
 SMS Slave mode selection
 TIMx_DIER Timer DMA and Interrupt Enable Values
 TIMx_SR Timer Status Register Flags
 TIMx_EGR Timer Event Generator Values
 TIM_BDTR_LOCK Timer Lock Values
 I2C DefinesDefined Constants and Types for the STM32L0xx I2C
 I2C register base address
 GPIO DefinesDefined Constants and Types for the STM32F0xx General Purpose I/O
 GPIO Output Pin Speed
 GPIO Pin Identifiers
 GPIO Port IDs
 GPIO Pin Direction and Analog/Digital Mode
 GPIO Output Pin Driver TypePush Pull Open Drain
 GPIO Output Pin Pullup
 Alternate Function Pin Selection
 SYSCFG DefinesDefined Constants and Types for the STM32L0xx System Config
 USART register base addressesHolds all the U(S)ART peripherals supported
 User interrupt service routines (ISR) prototypes for STM32 L0 series
 DebuggingMacros and functions to aid in debugging
 NVIC Defineslibopencm3 Cortex Nested Vectored Interrupt Controller
 User interrupts for STM32 L0 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
 CRS DefinesSTM32 Clock Recovery System: Defined Constants and Types
 USB DefinesDefined Constants and Types for the STM32F* USB drivers
 U(S)ART convenience FlagsWe define the "common" lower flag bits using a standard name, allowing them to be used regardless of which usart peripheral version you have
 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 L0 series
 NVIClibopencm3 Cortex Nested Vectored Interrupt Controller
 SysTicklibopencm3 Cortex System Tick Timer
 CRSlibopencm3 STM32 Clock Recovery Subsystem
 Generic USB DriversGeneric USB Drivers
 Generic USB Control RequestsGeneric USB Control Requests
 Generic USB Standard Request InterfaceGeneric USB Standard Request Interface
 Rng_fileThis library supports the random number generator peripheral (RNG) in the STM32F4 series of ARM Cortex Microcontrollers by ST Microelectronics
 Adc_file
 Flash_file
 I2c_file
 Pwr_file
 Timer_file
 Usart_file