Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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 */
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#endif