Something

static irqreturn_t danubeasc_tx_int(int irq, void *port)
{
    printk("%s:%s[%d]\n", __FILE__, __func__, __LINE__);
    *(DANUBE_ASC1_IRNCR) = ASC_IRNCR_TIR;
    danubeasc_start_tx(port);

    /* clear any pending interrupts */
    mask_and_ack_danube_irq (DANUBEASC1_TIR);

    return IRQ_HANDLED;
}