ECC_check.c

/*
  create a thread that checks for ECC errors in flash. We disable
  fault IRQs in the thread and monitor it from the main thread. If it
  doesn't complete in 1s then erase flash This is the only way I've
  found to check for ECC errors without causing a bus fault or
  unconditionally erasing flash
 */
struct ecccheck {
    const uint32_t *start;
    uint32_t size;
    uint32_t sum;
    bool done;
};

static void ecccheck_thread(void *arg)
{
    auto *m = (struct ecccheck *)arg;
    const uint32_t *p = m->start;
    __disable_fault_irq();
    for (uint32_t i=0; i<m->size/4; i++) {
        m->sum += *p++;
    }
    __enable_fault_irq();
    m->done = true;
}

void check_ecc_errors(void)
{
    struct ecccheck m {};
    m.start = (const uint32_t *)FLASH_BASE;
    m.size = BOARD_FLASH_SIZE*1024;
    auto *thd = chThdCreateFromHeap(NULL, 1024, "ECC_check", 1, ecccheck_thread, &m);
    for (uint32_t i=0; i<1000; i++) {
        thread_sleep_ms(1);
        if (m.done) {
            break;
        }
    }
    if (!m.done) {
        // we must have ECC errors in flash blocking the read. Erase
        // flash
        flash_set_keep_unlocked(true);
        uint32_t page = 0;
        while (stm32_flash_erasepage(flash_base_page+(page++))) ;
        flash_set_keep_unlocked(false);
        thread_sleep_ms(100);
    }
    chThdRelease(thd);
}