1 /*
2  *  linux/drivers/video/fb_cmdline.c
3  *
4  *  Copyright (C) 2014 Intel Corp
5  *  Copyright (C) 1994 Martin Schaller
6  *
7  *	2001 - Documented with DocBook
8  *	- Brad Douglas <brad@neruo.com>
9  *
10  * This file is subject to the terms and conditions of the GNU General Public
11  * License.  See the file COPYING in the main directory of this archive
12  * for more details.
13  *
14  * Authors:
15  *    Vetter <danie.vetter@ffwll.ch>
16  */
17 #include <linux/init.h>
18 #include <linux/fb.h>
19 
20 static char *video_options[FB_MAX] __read_mostly;
21 static int ofonly __read_mostly;
22 
23 const char *fb_mode_option;
24 EXPORT_SYMBOL_GPL(fb_mode_option);
25 
26 /**
27  * fb_get_options - get kernel boot parameters
28  * @name:   framebuffer name as it would appear in
29  *          the boot parameter line
30  *          (video=<name>:<options>)
31  * @option: the option will be stored here
32  *
33  * NOTE: Needed to maintain backwards compatibility
34  */
35 int fb_get_options(const char *name, char **option)
36 {
37 	char *opt, *options = NULL;
38 	int retval = 0;
39 	int name_len = strlen(name), i;
40 
41 	if (name_len && ofonly && strncmp(name, "offb", 4))
42 		retval = 1;
43 
44 	if (name_len && !retval) {
45 		for (i = 0; i < FB_MAX; i++) {
46 			if (video_options[i] == NULL)
47 				continue;
48 			if (!video_options[i][0])
49 				continue;
50 			opt = video_options[i];
51 			if (!strncmp(name, opt, name_len) &&
52 			    opt[name_len] == ':')
53 				options = opt + name_len + 1;
54 		}
55 	}
56 	/* No match, pass global option */
57 	if (!options && option && fb_mode_option)
58 		options = kstrdup(fb_mode_option, GFP_KERNEL);
59 	if (options && !strncmp(options, "off", 3))
60 		retval = 1;
61 
62 	if (option)
63 		*option = options;
64 
65 	return retval;
66 }
67 EXPORT_SYMBOL(fb_get_options);
68 
69 /**
70  *	video_setup - process command line options
71  *	@options: string of options
72  *
73  *	Process command line options for frame buffer subsystem.
74  *
75  *	NOTE: This function is a __setup and __init function.
76  *            It only stores the options.  Drivers have to call
77  *            fb_get_options() as necessary.
78  */
79 static int __init video_setup(char *options)
80 {
81 	if (!options || !*options)
82 		goto out;
83 
84 	if (!strncmp(options, "ofonly", 6)) {
85 		ofonly = 1;
86 		goto out;
87 	}
88 
89 	if (strchr(options, ':')) {
90 		/* named */
91 		int i;
92 
93 		for (i = 0; i < FB_MAX; i++) {
94 			if (video_options[i] == NULL) {
95 				video_options[i] = options;
96 				break;
97 			}
98 		}
99 	} else {
100 		/* global */
101 		fb_mode_option = options;
102 	}
103 
104 out:
105 	return 1;
106 }
107 __setup("video=", video_setup);
108