1/*  early printk support
2 *
3 *  Copyright (c) 2009 Philippe Vachon <philippe@cowpig.ca>
4 *  Copyright (c) 2009 Lemote Inc.
5 *  Author: Wu Zhangjin, wuzhangjin@gmail.com
6 *
7 *  This program is free software; you can redistribute	 it and/or modify it
8 *  under  the terms of	 the GNU General  Public License as published by the
9 *  Free Software Foundation;  either version 2 of the	License, or (at your
10 *  option) any later version.
11 */
12#include <linux/serial_reg.h>
13
14#include <loongson.h>
15
16#define PORT(base, offset) (u8 *)(base + offset)
17
18static inline unsigned int serial_in(unsigned char *base, int offset)
19{
20	return readb(PORT(base, offset));
21}
22
23static inline void serial_out(unsigned char *base, int offset, int value)
24{
25	writeb(value, PORT(base, offset));
26}
27
28void prom_putchar(char c)
29{
30	int timeout;
31	unsigned char *uart_base;
32
33	uart_base = (unsigned char *)_loongson_uart_base;
34	timeout = 1024;
35
36	while (((serial_in(uart_base, UART_LSR) & UART_LSR_THRE) == 0) &&
37			(timeout-- > 0))
38		;
39
40	serial_out(uart_base, UART_TX, c);
41}
42