release/src-rt-6.x.4708/linux/linux-2.6.36/arch/arm/kernel/early_printk.c

   1 /* Modified by Broadcom Corp. Portions Copyright (c) Broadcom Corp, 2012. */
   2 /*
   3  *  linux/arch/arm/kernel/early_printk.c
   4  *
   5  *  Copyright (C) 2009 Sascha Hauer <s.hauer@pengutronix.de>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/console.h>
  14 #include <linux/init.h>
  15
  16 #ifdef CONFIG_DEBUG_LL
  17 extern void printch(int);
  18 #else
  19 #define printch(a)
  20 #endif
  21
  22 static void early_write(const char *s, unsigned n)
  23 {
  24         while (n-- > 0) {
  25                 if (*s == '\n')
  26                         printch('\r');
  27                 printch(*s);
  28                 s++;
  29         }
  30 }
  31
  32 static void early_console_write(struct console *con, const char *s, unsigned n)
  33 {
  34         early_write(s, n);
  35 }
  36
  37 static struct console early_console = {
  38         .name =         "earlycon",
  39         .write =        early_console_write,
  40         .flags =        CON_PRINTBUFFER | CON_BOOT,
  41         .index =        -1,
  42 };
  43
  44 asmlinkage void early_printk(const char *fmt, ...)
  45 {
  46         char buf[512];
  47         int n;
  48         va_list ap;
  49
  50         va_start(ap, fmt);
  51         n = vscnprintf(buf, sizeof(buf), fmt, ap);
  52         early_write(buf, n);
  53         va_end(ap);
  54 }
  55
  56 static int __init setup_early_printk(char *buf)
  57 {
  58         register_console(&early_console);
  59         return 0;
  60 }
  61
  62 early_param("earlyprintk", setup_early_printk);