UTDR
UART(UTDR) = c;
ch = readl(micro->base + UTDR);
writel(tx->buf[tx->index], micro->base + UTDR);
#define UART_GET_CHAR(sport) __raw_readl((sport)->port.membase + UTDR)
#define UART_PUT_CHAR(sport,v) __raw_writel((v),(sport)->port.membase + UTDR)