early_printk.c

 1/*
 2 * This file is subject to the terms and conditions of the GNU General Public
 3 * License.  See the file "COPYING" in the main directory of this archive
 4 * for more details.
 5 *
 6 * Copyright (c) 2014 Finn Thain
 7 */
 8
 9#include <linux/kernel.h>
10#include <linux/console.h>
11#include <linux/init.h>
12#include <linux/string.h>
13#include <asm/setup.h>
14
15
16#include "../mvme147/mvme147.h"
17#include "../mvme16x/mvme16x.h"
18
19asmlinkage void __init debug_cons_nputs(struct console *c, const char *s, unsigned int n);
20
21static struct console early_console_instance = {
22	.name  = "debug",
23	.flags = CON_PRINTBUFFER | CON_BOOT,
24	.index = -1
25};
26
27static int __init setup_early_printk(char *buf)
28{
29	if (early_console || buf)
30		return 0;
31
32	if (MACH_IS_MVME147)
33		early_console_instance.write = mvme147_scc_write;
34	else if (MACH_IS_MVME16x)
35		early_console_instance.write = mvme16x_cons_write;
36	else
37		early_console_instance.write = debug_cons_nputs;
38	early_console = &early_console_instance;
39	register_console(early_console);
40
41	return 0;
42}
43early_param("earlyprintk", setup_early_printk);
44
45static int __init unregister_early_console(void)
46{
47	/*
48	 * debug_cons_nputs() defined in arch/m68k/kernel/head.S cannot be
49	 * called after init sections are discarded (for platforms that use it).
50	 */
51	if (early_console && early_console->write == debug_cons_nputs)
52		return unregister_console(early_console);
53
54	return 0;
55}
56late_initcall(unregister_early_console);