reflow-oven-control-sw/stm-firmware/stm-periph/option-bytes.c

/* Reflow Oven Controller
 *
 * Copyright (C) 2021  Mario Hüttel <mario.huettel@gmx.net>
 *
 * This file is part of the Reflow Oven Controller Project.
 *
 * The reflow oven controller is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * The Reflow Oven Control Firmware is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with the reflow oven controller project.
 * If not, see <http://www.gnu.org/licenses/>.
 */

#include <stm-periph/option-bytes.h>
#include <stm32/stm32f4xx.h>

/**
 * @brief First key for unlocking hte option byte write access
 */
#define FLASH_OPTION_KEY1 (0x08192A3BUL)

/**
 * @brief Second key for unlocking hte option byte write access
 */
#define FLASH_OPTION_KEY2 (0x4C5D6E7FUL)

void stm_option_bytes_read(struct option_bytes *opts)
{
	uint32_t opt_reg;

	if (!opts)
		return;

	opt_reg = FLASH->OPTCR;
	opts->brown_out_level = (opt_reg & FLASH_OPTCR_BOR_LEV) >> 2;
	opts->nrst_standby = (opt_reg & FLASH_OPTCR_nRST_STDBY) >> 7;
	opts->nrst_stop = (opt_reg & FLASH_OPTCR_nRST_STOP) >> 6;
	opts->nwrpi = (opt_reg & FLASH_OPTCR_nWRP) >> 16;
	opts->read_protection = (opt_reg & FLASH_OPTCR_RDP) >> 8;
	opts->wdg_sw = (opt_reg & FLASH_OPTCR_WDG_SW) >> 5;
}

int stm_option_bytes_program(const struct option_bytes *opts)
{
	uint32_t reg;

	FLASH->OPTKEYR = FLASH_OPTION_KEY1;
	FLASH->OPTKEYR = FLASH_OPTION_KEY2;

	__DSB();

	if (FLASH->OPTCR & FLASH_OPTCR_OPTLOCK) {
		/* Unlocking failed */
		return -1;
	}

	reg = FLASH->OPTCR;
	reg &= ~FLASH_OPTCR_BOR_LEV;
	reg &= ~FLASH_OPTCR_nRST_STDBY;
	reg &= ~FLASH_OPTCR_nRST_STOP;
	reg &= ~FLASH_OPTCR_nWRP;
	reg &= ~FLASH_OPTCR_RDP;
	reg &= ~FLASH_OPTCR_WDG_SW;

	reg |= (opts->brown_out_level << 2) & FLASH_OPTCR_BOR_LEV;
	reg |= (opts->nrst_standby << 7) & FLASH_OPTCR_nRST_STDBY;
	reg |= (opts->nrst_stop << 6) & FLASH_OPTCR_nRST_STOP;
	reg |= (opts->nwrpi << 16) & FLASH_OPTCR_nWRP;
	reg |= (opts->read_protection << 8) & FLASH_OPTCR_RDP;
	reg |= (opts->wdg_sw << 5) & FLASH_OPTCR_WDG_SW;

	while (FLASH->SR & FLASH_SR_BSY)
		;

	FLASH->OPTCR = reg;
	FLASH->OPTCR |= FLASH_OPTCR_OPTSTRT;
	__DSB();
	while (FLASH->SR & FLASH_SR_BSY)
		;

	FLASH->OPTCR |= FLASH_OPTCR_OPTLOCK;

	__DSB();
	return 0;
}