ATMEL_US_RXRDY
if (pending & ATMEL_US_RXRDY)
atmel_uart_writel(port, ATMEL_US_IER, ATMEL_US_RXRDY);
while (!(atmel_uart_readl(port, ATMEL_US_CSR) & ATMEL_US_RXRDY))
ATMEL_US_RXRDY | atmel_port->tx_done_mask);
atmel_uart_writel(port, ATMEL_US_IER, ATMEL_US_RXRDY);
atmel_uart_writel(port, ATMEL_US_IDR, ATMEL_US_RXRDY);
while (status & ATMEL_US_RXRDY) {