40 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2 3#include <linux/export.h>4#include <linux/fb.h>5#include <linux/mutex.h>6 7#if IS_ENABLED(CONFIG_FB_BACKLIGHT)8/*9 * This function generates a linear backlight curve10 *11 * 0: off12 * 1-7: min13 * 8-127: linear from min to max14 */15void fb_bl_default_curve(struct fb_info *fb_info, u8 off, u8 min, u8 max)16{17 unsigned int i, flat, count, range = (max - min);18 19 mutex_lock(&fb_info->bl_curve_mutex);20 21 fb_info->bl_curve[0] = off;22 23 for (flat = 1; flat < (FB_BACKLIGHT_LEVELS / 16); ++flat)24 fb_info->bl_curve[flat] = min;25 26 count = FB_BACKLIGHT_LEVELS * 15 / 16;27 for (i = 0; i < count; ++i)28 fb_info->bl_curve[flat + i] = min + (range * (i + 1) / count);29 30 mutex_unlock(&fb_info->bl_curve_mutex);31}32EXPORT_SYMBOL_GPL(fb_bl_default_curve);33 34struct backlight_device *fb_bl_device(struct fb_info *info)35{36 return info->bl_dev;37}38EXPORT_SYMBOL(fb_bl_device);39#endif40