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
15 extern void printch(int);
16
early_write(const char * s,unsigned n)17 static void early_write(const char *s, unsigned n)
18 {
19 while (n-- > 0) {
20 if (*s == '\n')
21 printch('\r');
22 printch(*s);
23 s++;
24 }
25 }
26
early_console_write(struct console * con,const char * s,unsigned n)27 static void early_console_write(struct console *con, const char *s, unsigned n)
28 {
29 early_write(s, n);
30 }
31
32 static struct console early_console = {
33 .name = "earlycon",
34 .write = early_console_write,
35 .flags = CON_PRINTBUFFER | CON_BOOT,
36 .index = -1,
37 };
38
early_printk(const char * fmt,...)39 asmlinkage void early_printk(const char *fmt, ...)
40 {
41 char buf[512];
42 int n;
43 va_list ap;
44
45 va_start(ap, fmt);
46 n = vscnprintf(buf, sizeof(buf), fmt, ap);
47 early_write(buf, n);
48 va_end(ap);
49 }
50
setup_early_printk(char * buf)51 static int __init setup_early_printk(char *buf)
52 {
53 register_console(&early_console);
54 return 0;
55 }
56
57 early_param("earlyprintk", setup_early_printk);
58