ATMEL_PDC_RNCR
atmel_uart_writel(port, ATMEL_PDC_RNCR, pdc->dma_size);
atmel_uart_writel(port, ATMEL_PDC_RNCR, PDC_BUFFER_SIZE);
writel(block_size / 2, chip->regs + ATMEL_PDC_RNCR);
writel(block_size / 2, chip->regs + ATMEL_PDC_RNCR);
.xncr = ATMEL_PDC_RNCR,