xref: /linux/arch/m68k/kernel/early_printk.c (revision b4ada0618eed0fbd1b1630f73deb048c592b06a1)
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 
19 asmlinkage void __init debug_cons_nputs(struct console *c, const char *s, unsigned int n);
20 
21 static struct console early_console_instance = {
22 	.name  = "debug",
23 	.flags = CON_PRINTBUFFER | CON_BOOT,
24 	.index = -1
25 };
26 
27 static 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 }
43 early_param("earlyprintk", setup_early_printk);
44 
45 static 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 }
56 late_initcall(unregister_early_console);
57