ATMEL_PDC_RCR
counter_reg = ATMEL_PDC_RCR;
atmel_uart_writel(port, ATMEL_PDC_RCR, PDC_BUFFER_SIZE);
writel(block_size / 2, chip->regs + ATMEL_PDC_RCR);
.xcr = ATMEL_PDC_RCR,