drivers/video/fbdev/core/fb_cmdline.c

   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  *      Returns zero.
  80  *
  81  */
  82 static int __init video_setup(char *options)
  83 {
  84         int i, global = 0;
  85
  86         if (!options || !*options)
  87                 global = 1;
  88
  89         if (!global && !strncmp(options, "ofonly", 6)) {
  90                 ofonly = 1;
  91                 global = 1;
  92         }
  93
  94         if (!global && !strchr(options, ':')) {
  95                 fb_mode_option = options;
  96                 global = 1;
  97         }
  98
  99         if (!global) {
 100                 for (i = 0; i < FB_MAX; i++) {
 101                         if (video_options[i] == NULL) {
 102                                 video_options[i] = options;
 103                                 break;
 104                         }
 105                 }
 106         }
 107
 108         return 1;
 109 }
 110 __setup("video=", video_setup);