libopencm3
A free/libre/open-source firmware library for various ARM Cortex-M3 microcontrollers.
STM32F4
Here is a list of all modules:
[detail level 123]
 STM32F4xxLibraries for ST Microelectronics STM32F4xx series
 ADClibopencm3 STM32F4xx Analog to Digital Converters
 CRClibopencm3 STM32F4xx CRC
 CRYPTOlibopencm3 STM32F4xx CRYPTO
 DAClibopencm3 STM32F4xx DAC
 DMAlibopencm3 STM32F4xx DMA
 FLASHlibopencm3 STM32F4xx FLASH
 GPIOlibopencm3 STM32F4xx General Purpose I/O
 HASHlibopencm3 STM32F4xx Hash Processor
 I2Clibopencm3 STM32F4xx I2C
 IWDGlibopencm3 STM32F4xx Independent Watchdog Timer
 LTDClibopencm3 STM32F4xx LTDC
 PWRlibopencm3 STM32F4xx Power Control
 RCClibopencm3 STM32F4xx Reset and Clock Control
 RTClibopencm3 STM32F4xx RTC
 SPIlibopencm3 STM32F4xx SPI
 Timerslibopencm3 STM32F4xx Timers
 USARTlibopencm3 STM32F4xx USART
 STM32F4xx DefinesDefined Constants and Types for the STM32F4xx series
 ADC DefinesDefined Constants and Types for the STM32F4xx Analog to Digital Converters
 CRC Defineslibopencm3 Defined Constants and Types for the STM32F4xx CRC Generator
 CRYPTO DefinesDefined constants and Types for the STM32F4xx Crypto Coprocessor
 DAC DefinesDefined Constants and Types for the STM32F4xx DAC
 DMA DefinesDefined Constants and Types for the STM32F4xx DMA Controller
 DMA2D DefinesDefined Constants and Macros for the STM32x4xx DMA2D Peripheral
 DSI DefinesDefined Constants and Macros for the STM32F4xx DSI Peripheral
 EXTI DefinesDefined Constants and Types for the STM32F4xx External Interrupts
 FLASH DefinesDefined Constants and Types for the STM32F4xx FLASH Memory
 GPIO DefinesDefined Constants and Types for the STM32F4xx General Purpose I/O
 HASH DefinesDefined Constants and Types for the STM32F4xx HASH Controller
 I2C DefinesDefined Constants and Types for the STM32F4xx I2C
 IWDG DefinesDefined Constants and Types for the STM32F4xx Independent Watchdog Timer
 PWR DefinesDefined Constants and Types for the STM32F4xx Power Control
 RCC DefinesDefined Constants and Types for the STM32F4xx Reset and Clock Control
 RTC DefinesDefined Constants and Types for the STM32F4xx RTC
 SPI DefinesDefined Constants and Types for the STM32F4xx SPI
 SYSCFG DefinesDefined Constants and Types for the STM32F4xx Sysconfig
 Timer Defineslibopencm3 Defined Constants and Types for the STM32F4xx Timers
 USART DefinesDefined Constants and Types for the STM32F4xx USART
 USB DefinesDefined Constants and Types for the STM32F* USB drivers