1 // SPDX-License-Identifier: GPL-2.0-or-later 2 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 curve 10 * 11 * 0: off 12 * 1-7: min 13 * 8-127: linear from min to max 14 */ 15 void 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 } 32 EXPORT_SYMBOL_GPL(fb_bl_default_curve); 33 #endif 34