arch/mips/loongson/common/early_printk.c

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