ATMEL_PDC_TPR
pointer_reg = ATMEL_PDC_TPR;
atmel_uart_writel(port, ATMEL_PDC_TPR, pdc->dma_addr + tail);
writel(runtime->dma_addr, chip->regs + ATMEL_PDC_TPR);
bytes = readl(chip->regs + ATMEL_PDC_TPR);
.xpr = ATMEL_PDC_TPR,