ATMEL_PDC_PTSR
pdc_tx = atmel_uart_readl(port, ATMEL_PDC_PTSR) & ATMEL_PDC_TXTEN;
if (is_pdc && (atmel_uart_readl(port, ATMEL_PDC_PTSR)
ptcr = readl(chip->regs + ATMEL_PDC_PTSR);