fb_backlight.c

 1// SPDX-License-Identifier: GPL-2.0-or-later
 2
 3#include <linux/backlight.h>
 4#include <linux/export.h>
 5#include <linux/fb.h>
 6#include <linux/mutex.h>
 7
 8#if IS_ENABLED(CONFIG_FB_BACKLIGHT)
 9/*
10 * This function generates a linear backlight curve
11 *
12 *     0: off
13 *   1-7: min
14 * 8-127: linear from min to max
15 */
16void fb_bl_default_curve(struct fb_info *fb_info, u8 off, u8 min, u8 max)
17{
18	unsigned int i, flat, count, range = (max - min);
19
20	mutex_lock(&fb_info->bl_curve_mutex);
21
22	fb_info->bl_curve[0] = off;
23
24	for (flat = 1; flat < (FB_BACKLIGHT_LEVELS / 16); ++flat)
25		fb_info->bl_curve[flat] = min;
26
27	count = FB_BACKLIGHT_LEVELS * 15 / 16;
28	for (i = 0; i < count; ++i)
29		fb_info->bl_curve[flat + i] = min + (range * (i + 1) / count);
30
31	mutex_unlock(&fb_info->bl_curve_mutex);
32}
33EXPORT_SYMBOL_GPL(fb_bl_default_curve);
34
35struct backlight_device *fb_bl_device(struct fb_info *info)
36{
37	return info->bl_dev;
38}
39EXPORT_SYMBOL(fb_bl_device);
40
41void fb_bl_notify_blank(struct fb_info *info, int old_blank)
42{
43	bool on = info->blank == FB_BLANK_UNBLANK;
44	bool prev_on = old_blank == FB_BLANK_UNBLANK;
45
46	if (info->bl_dev)
47		backlight_notify_blank(info->bl_dev, info->device, on, prev_on);
48	else
49		backlight_notify_blank_all(info->device, on, prev_on);
50}
51#endif