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. & Insititute of Computing Technology
   5  *  Author: Wu Zhangjin, wuzj@lemote.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 #include <machine.h>
  16
  17 #define PORT(base, offset) (u8 *)(base + offset)
  18
  19 static inline unsigned int serial_in(phys_addr_t base, int offset)
  20 {
  21         return readb(PORT(base, offset));
  22 }
  23
  24 static inline void serial_out(phys_addr_t base, int offset, int value)
  25 {
  26         writeb(value, PORT(base, offset));
  27 }
  28
  29 void prom_putchar(char c)
  30 {
  31         phys_addr_t uart_base =
  32                 (phys_addr_t) ioremap_nocache(LOONGSON_UART_BASE, 8);
  33
  34         while ((serial_in(uart_base, UART_LSR) & UART_LSR_THRE) == 0)
  35                 ;
  36
  37         serial_out(uart_base, UART_TX, c);
  38 }