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