LXR linux/arch/mips/loongson/common/early

   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