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// GPIO functions on stm32f4
//
// Copyright (C) 2019 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "internal.h" // gpio_peripheral
static GPIO_TypeDef * const digital_regs[] = {
GPIOA, GPIOB, GPIOC
};
// Set the mode and extended function of a pin
void
gpio_peripheral(uint32_t gpio, uint32_t mode, uint32_t func, int pullup)
{
GPIO_TypeDef *regs = digital_regs[GPIO2PORT(gpio)];
uint32_t pup = pullup ? (pullup > 0 ? 1 : 2) : 0;
uint32_t pos = gpio % 16, af_reg = pos / 8;
uint32_t af_shift = (pos % 8) * 4, af_msk = 0x0f << af_shift;
uint32_t m_shift = pos * 2, m_msk = 0x03 << m_shift;
regs->AFR[af_reg] = (regs->AFR[af_reg] & ~af_msk) | (func << af_shift);
regs->MODER = (regs->MODER & ~m_msk) | (mode << m_shift);
regs->PUPDR = (regs->PUPDR & ~m_msk) | (pup << m_shift);
regs->OSPEEDR = (regs->OSPEEDR & ~m_msk) | (0x02 << m_shift);
}
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