// SPDX-License-Identifier: GPL-2.0
/*
 * Based on the fbdev code in drivers/video/fbdev/core/fb_cmdline:
 *
 *  Copyright (C) 2014 Intel Corp
 *  Copyright (C) 1994 Martin Schaller
 *
 *      2001 - Documented with DocBook
 *      - Brad Douglas <brad@neruo.com>
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 *
 * Authors:
 *    Daniel Vetter <daniel.vetter@ffwll.ch>
 */

#include <linux/fb.h> /* for FB_MAX */
#include <linux/init.h>

#include <video/cmdline.h>

/*
 * FB_MAX is the maximum number of framebuffer devices and also
 * the maximum number of video= parameters. Although not directly
 * related to each other, it makes sense to keep it that way.
 */
static const char *video_options[FB_MAX] __read_mostly;
static const char *video_option __read_mostly;
static int video_of_only __read_mostly;

static const char *__video_get_option_string(const char *name)
{
        const char *options = NULL;
        size_t name_len = 0;

        if (name)
                name_len = strlen(name);

        if (name_len) {
                unsigned int i;
                const char *opt;

                for (i = 0; i < ARRAY_SIZE(video_options); ++i) {
                        if (!video_options[i])
                                continue;
                        if (video_options[i][0] == '\0')
                                continue;
                        opt = video_options[i];
                        if (!strncmp(opt, name, name_len) && opt[name_len] == ':')
                                options = opt + name_len + 1;
                }
        }

        /* No match, return global options */
        if (!options)
                options = video_option;

        return options;
}

/**
 * video_get_options - get kernel boot parameters
 * @name:       name of the output as it would appear in the boot parameter
 *              line (video=<name>:<options>)
 *
 * Looks up the video= options for the given name. Names are connector
 * names with DRM, or driver names with fbdev. If no video option for
 * the name has been specified, the function returns the global video=
 * setting. A @name of NULL always returns the global video setting.
 *
 * Returns:
 * The string of video options for the given name, or NULL if no video
 * option has been specified.
 */
const char *video_get_options(const char *name)
{
        return __video_get_option_string(name);
}
EXPORT_SYMBOL(video_get_options);

#if IS_ENABLED(CONFIG_FB_CORE)
bool __video_get_options(const char *name, const char **options, bool is_of)
{
        bool enabled = true;
        const char *opt = NULL;

        if (video_of_only && !is_of)
                enabled = false;

        opt = __video_get_option_string(name);

        if (options)
                *options = opt;

        return enabled;
}
EXPORT_SYMBOL(__video_get_options);
#endif

/*
 * Process command line options for video adapters. This function is
 * a __setup and __init function. It only stores the options. Drivers
 * have to call video_get_options() as necessary.
 */
static int __init video_setup(char *options)
{
        if (!options || !*options)
                goto out;

        if (!strncmp(options, "ofonly", 6)) {
                video_of_only = true;
                goto out;
        }

        if (strchr(options, ':')) {
                /* named */
                size_t i;

                for (i = 0; i < ARRAY_SIZE(video_options); i++) {
                        if (!video_options[i]) {
                                video_options[i] = options;
                                break;
                        }
                }
        } else {
                /* global */
                video_option = options;
        }

out:
        return 1;
}
__setup("video=", video_setup);