openpilot_comma/panda/board/stm32f4/peripherals.h

#ifdef BOOTSTUB
void gpio_usb_init(void) {
#else
static void gpio_usb_init(void) {
#endif
  // A11,A12: USB
  set_gpio_alternate(GPIOA, 11, GPIO_AF10_OTG_FS);
  set_gpio_alternate(GPIOA, 12, GPIO_AF10_OTG_FS);
  GPIOA->OSPEEDR = GPIO_OSPEEDER_OSPEEDR11 | GPIO_OSPEEDER_OSPEEDR12;
}

void gpio_spi_init(void) {
  // A4-A7: SPI
  set_gpio_alternate(GPIOA, 4, GPIO_AF5_SPI1);
  set_gpio_alternate(GPIOA, 5, GPIO_AF5_SPI1);
  set_gpio_alternate(GPIOA, 6, GPIO_AF5_SPI1);
  set_gpio_alternate(GPIOA, 7, GPIO_AF5_SPI1);
  register_set_bits(&(GPIOA->OSPEEDR), GPIO_OSPEEDER_OSPEEDR4 | GPIO_OSPEEDER_OSPEEDR5 | GPIO_OSPEEDER_OSPEEDR6 | GPIO_OSPEEDER_OSPEEDR7);
}

void gpio_usart2_init(void) {
  // A2,A3: USART 2 for debugging
  set_gpio_alternate(GPIOA, 2, GPIO_AF7_USART2);
  set_gpio_alternate(GPIOA, 3, GPIO_AF7_USART2);
}

// Common GPIO initialization
void common_init_gpio(void) {
  // TODO: Is this block actually doing something???
  // pull low to hold ESP in reset??
  // enable OTG out tied to ground
  GPIOA->ODR = 0;
  GPIOB->ODR = 0;
  GPIOA->PUPDR = 0;
  GPIOB->AFR[0] = 0;
  GPIOB->AFR[1] = 0;

  // C2: Voltage sense line
  set_gpio_mode(GPIOC, 2, MODE_ANALOG);

  gpio_usb_init();

  // B8,B9: CAN 1
  set_gpio_alternate(GPIOB, 8, GPIO_AF8_CAN1);
  set_gpio_alternate(GPIOB, 9, GPIO_AF8_CAN1);
}

void flasher_peripherals_init(void) {
  RCC->AHB1ENR |= RCC_AHB1ENR_DMA2EN;
  RCC->APB2ENR |= RCC_APB2ENR_SPI1EN;
  RCC->AHB2ENR |= RCC_AHB2ENR_OTGFSEN;
  RCC->APB1ENR |= RCC_APB1ENR_USART2EN;
}

// Peripheral initialization
void peripherals_init(void) {
  // enable GPIO(A,B,C,D)
  RCC->AHB1ENR |= RCC_AHB1ENR_GPIOAEN;
  RCC->AHB1ENR |= RCC_AHB1ENR_GPIOBEN;
  RCC->AHB1ENR |= RCC_AHB1ENR_GPIOCEN;
  RCC->AHB1ENR |= RCC_AHB1ENR_GPIODEN;

  // Supplemental
  RCC->AHB1ENR |= RCC_AHB1ENR_DMA2EN;
  RCC->APB1ENR |= RCC_APB1ENR_PWREN;   // for RTC config
  RCC->APB2ENR |= RCC_APB2ENR_SYSCFGEN;

  // Connectivity
  RCC->APB2ENR |= RCC_APB2ENR_SPI1EN;
  RCC->AHB2ENR |= RCC_AHB2ENR_OTGFSEN;
  RCC->APB1ENR |= RCC_APB1ENR_USART2EN;
  RCC->APB1ENR |= RCC_APB1ENR_USART3EN;
  RCC->APB1ENR |= RCC_APB1ENR_UART5EN;
  RCC->APB1ENR |= RCC_APB1ENR_CAN1EN;
  RCC->APB1ENR |= RCC_APB1ENR_CAN2EN;
  RCC->APB1ENR |= RCC_APB1ENR_CAN3EN;

  // Analog
  RCC->APB2ENR |= RCC_APB2ENR_ADC1EN;
  RCC->APB1ENR |= RCC_APB1ENR_DACEN;

  // Timers
  RCC->APB2ENR |= RCC_APB2ENR_TIM1EN;  // clock source timer
  RCC->APB1ENR |= RCC_APB1ENR_TIM2EN;  // main counter
  RCC->APB1ENR |= RCC_APB1ENR_TIM3EN;  // pedal and fan PWM
  RCC->APB1ENR |= RCC_APB1ENR_TIM4EN;  // IR PWM
  RCC->APB1ENR |= RCC_APB1ENR_TIM5EN;  // k-line init
  RCC->APB1ENR |= RCC_APB1ENR_TIM6EN;  // interrupt timer
  RCC->APB2ENR |= RCC_APB2ENR_TIM9EN;  // slow loop
}

void enable_interrupt_timer(void) {
  register_set_bits(&(RCC->APB1ENR), RCC_APB1ENR_TIM6EN);  // Enable interrupt timer peripheral
}