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
serial_in(unsigned char * base,int offset)18 static inline unsigned int serial_in(unsigned char *base, int offset)
19 {
20 return readb(PORT(base, offset));
21 }
22
serial_out(unsigned char * base,int offset,int value)23 static inline void serial_out(unsigned char *base, int offset, int value)
24 {
25 writeb(value, PORT(base, offset));
26 }
27
prom_putchar(char c)28 void 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