1*f0f6839bSThomas Zimmermann // SPDX-License-Identifier: GPL-2.0-or-later 2*f0f6839bSThomas Zimmermann 3*f0f6839bSThomas Zimmermann #include <linux/export.h> 4*f0f6839bSThomas Zimmermann #include <linux/fb.h> 5*f0f6839bSThomas Zimmermann #include <linux/mutex.h> 6*f0f6839bSThomas Zimmermann 7*f0f6839bSThomas Zimmermann #if IS_ENABLED(CONFIG_FB_BACKLIGHT) 8*f0f6839bSThomas Zimmermann /* 9*f0f6839bSThomas Zimmermann * This function generates a linear backlight curve 10*f0f6839bSThomas Zimmermann * 11*f0f6839bSThomas Zimmermann * 0: off 12*f0f6839bSThomas Zimmermann * 1-7: min 13*f0f6839bSThomas Zimmermann * 8-127: linear from min to max 14*f0f6839bSThomas Zimmermann */ fb_bl_default_curve(struct fb_info * fb_info,u8 off,u8 min,u8 max)15*f0f6839bSThomas Zimmermannvoid fb_bl_default_curve(struct fb_info *fb_info, u8 off, u8 min, u8 max) 16*f0f6839bSThomas Zimmermann { 17*f0f6839bSThomas Zimmermann unsigned int i, flat, count, range = (max - min); 18*f0f6839bSThomas Zimmermann 19*f0f6839bSThomas Zimmermann mutex_lock(&fb_info->bl_curve_mutex); 20*f0f6839bSThomas Zimmermann 21*f0f6839bSThomas Zimmermann fb_info->bl_curve[0] = off; 22*f0f6839bSThomas Zimmermann 23*f0f6839bSThomas Zimmermann for (flat = 1; flat < (FB_BACKLIGHT_LEVELS / 16); ++flat) 24*f0f6839bSThomas Zimmermann fb_info->bl_curve[flat] = min; 25*f0f6839bSThomas Zimmermann 26*f0f6839bSThomas Zimmermann count = FB_BACKLIGHT_LEVELS * 15 / 16; 27*f0f6839bSThomas Zimmermann for (i = 0; i < count; ++i) 28*f0f6839bSThomas Zimmermann fb_info->bl_curve[flat + i] = min + (range * (i + 1) / count); 29*f0f6839bSThomas Zimmermann 30*f0f6839bSThomas Zimmermann mutex_unlock(&fb_info->bl_curve_mutex); 31*f0f6839bSThomas Zimmermann } 32*f0f6839bSThomas Zimmermann EXPORT_SYMBOL_GPL(fb_bl_default_curve); 33*f0f6839bSThomas Zimmermann #endif 34