ChibiOS Free Embedded RTOS

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typedef enum
{
    RELEASE = 0,
    WAITING_FOR_CATCH,
    OTHER_CORE_CAUGHT,
} flash_access_state_t;

static volatile flash_access_state_t flash_access_state = RELEASE;

void RAM_FUNCTION(catch_core0)(void)
{
    if (port_get_core_id() != 0)
    {
        // we got the wrong core, nothing we can do about
        return;
    }

    if (flash_access_state == WAITING_FOR_CATCH)
    {
        // do not reschedule this thread anymore, block all IRQs
        chSysDisable();
        
        flash_access_state = OTHER_CORE_CAUGHT;
        __DMB();
        
        // spin here until the other core releases us again
        while (flash_access_state != RELEASE);
        
        chSysEnable();
    }
}

void RAM_FUNCTION(read_out_flash_id)(void)
{
    rom_connect_internal_flash_func();
    rom_flash_exit_xip_func();

    // TODO: real flash access functions go here
    
    rom_flash_flush_cache_func();
    flash_enable_xip_via_boot2();
    
    // XIP should now work again as before
}

void cmd_flash_id(BaseSequentialStream *chp, int argc, char *argv[])
{
    (void)argv; (void)argc;
    
    // this function can just be called from core1
    // this is necessary because we need to lock the other core
    // during direct flash access
    if (port_get_core_id() != 1)
    {
        chprintf(chp, "ERROR: flash_id called from the wrong core!\r\n");
        return;
    }

    flash_access_state = WAITING_FOR_CATCH;
    __DMB();
    
    chEvtSignal(&ch0.mainthread, EVT_CATCH_CORE0);

    // TODO: probably add some timeout
    while (flash_access_state != OTHER_CORE_CAUGHT);

    // now we can lock the OS
    chSysLock();
    
    read_out_flash_id();

    chSysUnlock();

    // release the other core again
    flash_access_state = RELEASE;
    __DMB();
    
    chprintf(chp, "we back to XIP\r\n");
}