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1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * Based on the fbdev code in drivers/video/fbdev/core/fb_cmdline: | |
4 | * | |
5 | * Copyright (C) 2014 Intel Corp | |
6 | * Copyright (C) 1994 Martin Schaller | |
7 | * | |
8 | * 2001 - Documented with DocBook | |
9 | * - Brad Douglas <brad@neruo.com> | |
10 | * | |
11 | * This file is subject to the terms and conditions of the GNU General Public | |
12 | * License. See the file COPYING in the main directory of this archive | |
13 | * for more details. | |
14 | * | |
15 | * Authors: | |
16 | * Daniel Vetter <daniel.vetter@ffwll.ch> | |
17 | */ | |
18 | ||
19 | #include <linux/fb.h> /* for FB_MAX */ | |
20 | #include <linux/init.h> | |
21 | ||
22 | #include <video/cmdline.h> | |
23 | ||
24 | /* | |
25 | * FB_MAX is the maximum number of framebuffer devices and also | |
26 | * the maximum number of video= parameters. Although not directly | |
27 | * related to each other, it makes sense to keep it that way. | |
28 | */ | |
29 | static const char *video_options[FB_MAX] __read_mostly; | |
30 | static const char *video_option __read_mostly; | |
31 | static int video_of_only __read_mostly; | |
32 | ||
33 | static const char *__video_get_option_string(const char *name) | |
34 | { | |
35 | const char *options = NULL; | |
36 | size_t name_len = 0; | |
37 | ||
38 | if (name) | |
39 | name_len = strlen(name); | |
40 | ||
41 | if (name_len) { | |
42 | unsigned int i; | |
43 | const char *opt; | |
44 | ||
45 | for (i = 0; i < ARRAY_SIZE(video_options); ++i) { | |
46 | if (!video_options[i]) | |
47 | continue; | |
48 | if (video_options[i][0] == '\0') | |
49 | continue; | |
50 | opt = video_options[i]; | |
51 | if (!strncmp(opt, name, name_len) && opt[name_len] == ':') | |
52 | options = opt + name_len + 1; | |
53 | } | |
54 | } | |
55 | ||
56 | /* No match, return global options */ | |
57 | if (!options) | |
58 | options = video_option; | |
59 | ||
60 | return options; | |
61 | } | |
62 | ||
63 | /** | |
64 | * video_get_options - get kernel boot parameters | |
65 | * @name: name of the output as it would appear in the boot parameter | |
66 | * line (video=<name>:<options>) | |
67 | * | |
68 | * Looks up the video= options for the given name. Names are connector | |
69 | * names with DRM, or driver names with fbdev. If no video option for | |
70 | * the name has been specified, the function returns the global video= | |
71 | * setting. A @name of NULL always returns the global video setting. | |
72 | * | |
73 | * Returns: | |
74 | * The string of video options for the given name, or NULL if no video | |
75 | * option has been specified. | |
76 | */ | |
77 | const char *video_get_options(const char *name) | |
78 | { | |
79 | return __video_get_option_string(name); | |
80 | } | |
81 | EXPORT_SYMBOL(video_get_options); | |
82 | ||
83 | bool __video_get_options(const char *name, const char **options, bool is_of) | |
84 | { | |
85 | bool enabled = true; | |
86 | const char *opt = NULL; | |
87 | ||
88 | if (video_of_only && !is_of) | |
89 | enabled = false; | |
90 | ||
91 | opt = __video_get_option_string(name); | |
92 | ||
93 | if (options) | |
94 | *options = opt; | |
95 | ||
96 | return enabled; | |
97 | } | |
98 | EXPORT_SYMBOL(__video_get_options); | |
99 | ||
100 | /* | |
101 | * Process command line options for video adapters. This function is | |
102 | * a __setup and __init function. It only stores the options. Drivers | |
103 | * have to call video_get_options() as necessary. | |
104 | */ | |
105 | static int __init video_setup(char *options) | |
106 | { | |
107 | if (!options || !*options) | |
108 | goto out; | |
109 | ||
110 | if (!strncmp(options, "ofonly", 6)) { | |
111 | video_of_only = true; | |
112 | goto out; | |
113 | } | |
114 | ||
115 | if (strchr(options, ':')) { | |
116 | /* named */ | |
117 | size_t i; | |
118 | ||
119 | for (i = 0; i < ARRAY_SIZE(video_options); i++) { | |
120 | if (!video_options[i]) { | |
121 | video_options[i] = options; | |
122 | break; | |
123 | } | |
124 | } | |
125 | } else { | |
126 | /* global */ | |
127 | video_option = options; | |
128 | } | |
129 | ||
130 | out: | |
131 | return 1; | |
132 | } | |
133 | __setup("video=", video_setup); |