Line data    Source code

       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           0 : static const char *__video_get_option_string(const char *name)
      34             : {
      35           0 :         const char *options = NULL;
      36           0 :         size_t name_len = 0;
      37             : 
      38           0 :         if (name)
      39             :                 name_len = strlen(name);
      40             : 
      41           0 :         if (name_len) {
      42             :                 unsigned int i;
      43             :                 const char *opt;
      44             : 
      45           0 :                 for (i = 0; i < ARRAY_SIZE(video_options); ++i) {
      46           0 :                         if (!video_options[i])
      47           0 :                                 continue;
      48           0 :                         if (video_options[i][0] == '\0')
      49           0 :                                 continue;
      50           0 :                         opt = video_options[i];
      51           0 :                         if (!strncmp(opt, name, name_len) && opt[name_len] == ':')
      52           0 :                                 options = opt + name_len + 1;
      53             :                 }
      54             :         }
      55             : 
      56             :         /* No match, return global options */
      57           0 :         if (!options)
      58           0 :                 options = video_option;
      59             : 
      60           0 :         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           0 : const char *video_get_options(const char *name)
      78             : {
      79           0 :         return __video_get_option_string(name);
      80             : }
      81             : EXPORT_SYMBOL(video_get_options);
      82             : 
      83           0 : bool __video_get_options(const char *name, const char **options, bool is_of)
      84             : {
      85           0 :         bool enabled = true;
      86           0 :         const char *opt = NULL;
      87             : 
      88           0 :         if (video_of_only && !is_of)
      89           0 :                 enabled = false;
      90             : 
      91           0 :         opt = __video_get_option_string(name);
      92             : 
      93           0 :         if (options)
      94           0 :                 *options = opt;
      95             : 
      96           0 :         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           0 : static int __init video_setup(char *options)
     106             : {
     107           0 :         if (!options || !*options)
     108             :                 goto out;
     109             : 
     110           0 :         if (!strncmp(options, "ofonly", 6)) {
     111           0 :                 video_of_only = true;
     112           0 :                 goto out;
     113             :         }
     114             : 
     115           0 :         if (strchr(options, ':')) {
     116             :                 /* named */
     117             :                 size_t i;
     118             : 
     119           0 :                 for (i = 0; i < ARRAY_SIZE(video_options); i++) {
     120           0 :                         if (!video_options[i]) {
     121           0 :                                 video_options[i] = options;
     122           0 :                                 break;
     123             :                         }
     124             :                 }
     125             :         } else {
     126             :                 /* global */
     127           0 :                 video_option = options;
     128             :         }
     129             : 
     130             : out:
     131           0 :         return 1;
     132             : }
     133             : __setup("video=", video_setup);