UART_IRQ_SUM
ret = devm_request_irq(port->dev, mvuart->irq[UART_IRQ_SUM],
mvuart->irq[UART_IRQ_SUM]);
devm_free_irq(port->dev, mvuart->irq[UART_IRQ_SUM], port);
mvuart->irq[UART_IRQ_SUM] = irq;