134 lines
3.1 KiB
C
134 lines
3.1 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Based on the fbdev code in drivers/video/fbdev/core/fb_cmdline:
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*
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* Copyright (C) 2014 Intel Corp
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* Copyright (C) 1994 Martin Schaller
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*
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* 2001 - Documented with DocBook
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* - Brad Douglas <brad@neruo.com>
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file COPYING in the main directory of this archive
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* for more details.
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*
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* Authors:
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* Daniel Vetter <daniel.vetter@ffwll.ch>
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*/
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#include <linux/fb.h> /* for FB_MAX */
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#include <linux/init.h>
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#include <video/cmdline.h>
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/*
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* FB_MAX is the maximum number of framebuffer devices and also
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* the maximum number of video= parameters. Although not directly
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* related to each other, it makes sense to keep it that way.
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*/
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static const char *video_options[FB_MAX] __read_mostly;
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static const char *video_option __read_mostly;
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static int video_of_only __read_mostly;
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static const char *__video_get_option_string(const char *name)
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{
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const char *options = NULL;
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size_t name_len = 0;
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if (name)
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name_len = strlen(name);
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if (name_len) {
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unsigned int i;
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const char *opt;
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for (i = 0; i < ARRAY_SIZE(video_options); ++i) {
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if (!video_options[i])
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continue;
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if (video_options[i][0] == '\0')
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continue;
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opt = video_options[i];
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if (!strncmp(opt, name, name_len) && opt[name_len] == ':')
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options = opt + name_len + 1;
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}
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}
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/* No match, return global options */
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if (!options)
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options = video_option;
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return options;
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}
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/**
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* video_get_options - get kernel boot parameters
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* @name: name of the output as it would appear in the boot parameter
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* line (video=<name>:<options>)
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*
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* Looks up the video= options for the given name. Names are connector
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* names with DRM, or driver names with fbdev. If no video option for
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* the name has been specified, the function returns the global video=
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* setting. A @name of NULL always returns the global video setting.
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*
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* Returns:
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* The string of video options for the given name, or NULL if no video
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* option has been specified.
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*/
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const char *video_get_options(const char *name)
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{
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return __video_get_option_string(name);
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}
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EXPORT_SYMBOL(video_get_options);
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bool __video_get_options(const char *name, const char **options, bool is_of)
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{
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bool enabled = true;
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const char *opt = NULL;
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if (video_of_only && !is_of)
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enabled = false;
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opt = __video_get_option_string(name);
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if (options)
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*options = opt;
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return enabled;
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}
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EXPORT_SYMBOL(__video_get_options);
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/*
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* Process command line options for video adapters. This function is
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* a __setup and __init function. It only stores the options. Drivers
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* have to call video_get_options() as necessary.
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*/
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static int __init video_setup(char *options)
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{
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if (!options || !*options)
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goto out;
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if (!strncmp(options, "ofonly", 6)) {
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video_of_only = true;
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goto out;
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}
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if (strchr(options, ':')) {
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/* named */
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size_t i;
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for (i = 0; i < ARRAY_SIZE(video_options); i++) {
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if (!video_options[i]) {
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video_options[i] = options;
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break;
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}
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}
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} else {
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/* global */
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video_option = options;
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}
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out:
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return 1;
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}
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__setup("video=", video_setup);
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