arch/arm/kernel/early_printk.c

   1 /*
   2  *  linux/arch/arm/kernel/early_printk.c
   3  *
   4  *  Copyright (C) 2009 Sascha Hauer <s.hauer@pengutronix.de>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/console.h>
  13 #include <linux/init.h>
  14 #include <linux/string.h>
  15
  16 extern void printascii(const char *);
  17
  18 static void early_write(const char *s, unsigned n)
  19 {
  20         char buf[128];
  21         while (n) {
  22                 unsigned l = min(n, sizeof(buf)-1);
  23                 memcpy(buf, s, l);
  24                 buf[l] = 0;
  25                 s += l;
  26                 n -= l;
  27                 printascii(buf);
  28         }
  29 }
  30
  31 static void early_console_write(struct console *con, const char *s, unsigned n)
  32 {
  33         early_write(s, n);
  34 }
  35
  36 static struct console early_console_dev = {
  37         .name =         "earlycon",
  38         .write =        early_console_write,
  39         .flags =        CON_PRINTBUFFER | CON_BOOT,
  40         .index =        -1,
  41 };
  42
  43 static int __init setup_early_printk(char *buf)
  44 {
  45         early_console = &early_console_dev;
  46         register_console(&early_console_dev);
  47         return 0;
  48 }
  49
  50 early_param("earlyprintk", setup_early_printk);