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 | #if IS_ENABLED(CONFIG_FB_CORE) |
84 | bool __video_get_options(const char *name, const char **options, bool is_of) |
85 | { |
86 | bool enabled = true; |
87 | const char *opt = NULL; |
88 | |
89 | if (video_of_only && !is_of) |
90 | enabled = false; |
91 | |
92 | opt = __video_get_option_string(name); |
93 | |
94 | if (options) |
95 | *options = opt; |
96 | |
97 | return enabled; |
98 | } |
99 | EXPORT_SYMBOL(__video_get_options); |
100 | #endif |
101 | |
102 | /* |
103 | * Process command line options for video adapters. This function is |
104 | * a __setup and __init function. It only stores the options. Drivers |
105 | * have to call video_get_options() as necessary. |
106 | */ |
107 | static int __init video_setup(char *options) |
108 | { |
109 | if (!options || !*options) |
110 | goto out; |
111 | |
112 | if (!strncmp(options, "ofonly" , 6)) { |
113 | video_of_only = true; |
114 | goto out; |
115 | } |
116 | |
117 | if (strchr(options, ':')) { |
118 | /* named */ |
119 | size_t i; |
120 | |
121 | for (i = 0; i < ARRAY_SIZE(video_options); i++) { |
122 | if (!video_options[i]) { |
123 | video_options[i] = options; |
124 | break; |
125 | } |
126 | } |
127 | } else { |
128 | /* global */ |
129 | video_option = options; |
130 | } |
131 | |
132 | out: |
133 | return 1; |
134 | } |
135 | __setup("video=" , video_setup); |
136 | |