libopencm3
A free/libre/open-source firmware library for various ARM Cortex-M3 microcontrollers.
STM32F1
Here is a list of all modules:
[detail level 123]
 STM32F1xxLibraries for ST Microelectronics STM32F1xx series
 ADClibopencm3 STM32F1xx Analog to Digital Converters
 CRClibopencm3 STM32F1xx CRC
 DAClibopencm3 STM32F1xx DAC
 DMAlibopencm3 STM32F1xx DMA
 FLASHlibopencm3 STM32F1xx FLASH Memory
 GPIOlibopencm3 STM32F1xx General Purpose I/O
 I2Clibopencm3 STM32F1xx I2C
 IWDGlibopencm3 STM32F1xx Independent Watchdog Timer
 PWRlibopencm3 STM32F1xx Power Control
 RCClibopencm3 STM32F1xx Reset and Clock Control
 RTClibopencm3 STM32F1xx RTC
 SPIlibopencm3 STM32F1xx SPI
 Timerslibopencm3 STM32F1xx Timers
 USARTlibopencm3 STM32F1xx USART
 STM32F1xx DefinesDefined Constants and Types for the STM32F1xx series
 ADC DefinesDefined Constants and Types for the STM32F1xx Analog to Digital Converters
 CRC Defineslibopencm3 Defined Constants and Types for the STM32F1xx CRC Generator
 DAC DefinesDefined Constants and Types for the STM32F1xx DAC
 DMA DefinesDefined Constants and Types for the STM32F1xx DMA Controller
 EXTI DefinesDefined Constants and Types for the STM32F1xx External Interrupts
 FLASH DefinesDefined Constants and Types for the STM32F1xx FLASH Memory
 GPIO DefinesDefined Constants and Types for the STM32F1xx General Purpose I/O
 I2C DefinesDefined Constants and Types for the STM32F1xx I2C
 IWDG DefinesDefined Constants and Types for the STM32F1xx Independent Watchdog Timer
 PWR DefinesDefined Constants and Types for the STM32F1xx PWR Control
 RCC DefinesDefined Constants and Types for the STM32F1xx Reset and Clock Control
 RTC DefinesDefined Constants and Types for the STM32F1xx Real Time Clock
 SPI DefinesDefined Constants and Types for the STM32F1xx SPI
 Timer Defineslibopencm3 Defined Constants and Types for the STM32F1xx Timers
 USART DefinesDefined Constants and Types for the STM32F1xx USART
 USB DefinesDefined Constants and Types for the STM32F* USB drivers