| 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(lock: &fb_info->bl_curve_mutex); |
| 31 | } |
| 32 | EXPORT_SYMBOL_GPL(fb_bl_default_curve); |
| 33 | #endif |
| 34 |