trezor-firmware/embed/boardloader/lowlevel.c

#include STM32_HAL_H

#include "lowlevel.h"

#define WANTED_WRP (OB_WRP_SECTOR_0 | OB_WRP_SECTOR_1 | OB_WRP_SECTOR_2)
#define WANTED_RDP (OB_RDP_LEVEL_2)

void flash_set_option_bytes(void)
{
    FLASH_OBProgramInitTypeDef opts;

    HAL_FLASHEx_OBGetConfig(&opts);

    opts.OptionType = 0;

    if (opts.WRPSector != WANTED_WRP) {
        opts.OptionType |= OPTIONBYTE_WRP;
        opts.WRPState = OB_WRPSTATE_ENABLE;
        opts.WRPSector = WANTED_WRP;
        opts.Banks = FLASH_BANK_1;
    }

    if (opts.RDPLevel != WANTED_RDP) {
        opts.OptionType |= OPTIONBYTE_RDP;
        opts.RDPLevel = WANTED_RDP;
    }

    if (opts.OptionType == 0) {
        return; // protections are configured
    }

    // attempt to lock down the boardloader sectors
    HAL_FLASH_Unlock();
    HAL_FLASH_OB_Unlock();
    HAL_FLASHEx_OBProgram(&opts);
    HAL_FLASH_OB_Launch();
    HAL_FLASH_OB_Lock();
    HAL_FLASH_Lock();
}

#define FLASH_OPTION_BYTES_1 (*(const uint64_t *)0x1FFFC000)
#define FLASH_OPTION_BYTES_2 (*(const uint64_t *)0x1FFFC008)

secbool flash_check_option_bytes(void)
{
    //                         RDP level 2                   WRP for sectors 0, 1 and 2         flash option control register matches
    if (((FLASH_OPTION_BYTES_1 & 0xFFEC) == 0xCCEC) && ((FLASH_OPTION_BYTES_2 & 0x0FFF) == 0x0FF8) && (FLASH->OPTCR == 0x0FF8CCED)) {
        return sectrue;
    }
    return secfalse;
}

void periph_init(void)
{
    // STM32F4xx HAL library initialization:
    //  - configure the Flash prefetch, instruction and data caches
    //  - configure the Systick to generate an interrupt each 1 msec
    //  - set NVIC Group Priority to 4
    //  - global MSP (MCU Support Package) initialization
    HAL_Init();

    // Enable GPIO clocks
    __HAL_RCC_GPIOA_CLK_ENABLE();
    __HAL_RCC_GPIOB_CLK_ENABLE();
    __HAL_RCC_GPIOC_CLK_ENABLE();
    __HAL_RCC_GPIOD_CLK_ENABLE();

    // enable the PVD (programmable voltage detector).
    // select the "2.6V" threshold (level 4).
    // this detector will be active regardless of the
    // flash option byte BOR setting.
    __HAL_RCC_PWR_CLK_ENABLE();
    PWR_PVDTypeDef pvd_config;
    pvd_config.PVDLevel = PWR_PVDLEVEL_4;
    pvd_config.Mode = PWR_PVD_MODE_IT_RISING_FALLING;
    HAL_PWR_ConfigPVD(&pvd_config);
    HAL_PWR_EnablePVD();
    NVIC_EnableIRQ(PVD_IRQn);
}

secbool reset_flags_init(void)
{
/*
#if PRODUCTION
    // this is effective enough that it makes development painful, so only use it for production.
    // check the reset flags to assure that we arrive here due to a regular full power-on event,
    // and not as a result of a lesser reset.
    if ((RCC->CSR & (RCC_CSR_LPWRRSTF | RCC_CSR_WWDGRSTF | RCC_CSR_IWDGRSTF | RCC_CSR_SFTRSTF | RCC_CSR_PORRSTF | RCC_CSR_PINRSTF | RCC_CSR_BORRSTF)) != (RCC_CSR_PORRSTF | RCC_CSR_PINRSTF | RCC_CSR_BORRSTF)) {
        return secfalse;
    }
#endif
*/

    RCC->CSR |= RCC_CSR_RMVF; // clear the reset flags

    return sectrue;
}