1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* gpio_backlight.c - Simple GPIO-controlled backlight
*/
#include <linux/backlight.h>
#include <linux/err.h>
#include <linux/fb.h>
#include <linux/gpio/consumer.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_data/gpio_backlight.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/slab.h>
struct gpio_backlight {
struct device *dev;
struct gpio_desc *gpiod;
};
static int gpio_backlight_update_status(struct backlight_device *bl)
{
struct gpio_backlight *gbl = bl_get_data(bl);
gpiod_set_value_cansleep(gbl->gpiod, backlight_get_brightness(bl));
return 0;
}
static int gpio_backlight_check_fb(struct backlight_device *bl,
struct fb_info *info)
{
struct gpio_backlight *gbl = bl_get_data(bl);
return !gbl->dev || gbl->dev == info->device;
}
static const struct backlight_ops gpio_backlight_ops = {
.options = BL_CORE_SUSPENDRESUME,
.update_status = gpio_backlight_update_status,
.check_fb = gpio_backlight_check_fb,
};
static int gpio_backlight_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct gpio_backlight_platform_data *pdata = dev_get_platdata(dev);
struct device_node *of_node = dev->of_node;
struct backlight_properties props;
struct backlight_device *bl;
struct gpio_backlight *gbl;
int ret, init_brightness, def_value;
gbl = devm_kzalloc(dev, sizeof(*gbl), GFP_KERNEL);
if (gbl == NULL)
return -ENOMEM;
if (pdata)
gbl->dev = pdata->dev;
def_value = device_property_read_bool(dev, "default-on");
gbl->gpiod = devm_gpiod_get(dev, NULL, GPIOD_ASIS);
if (IS_ERR(gbl->gpiod)) {
ret = PTR_ERR(gbl->gpiod);
if (ret != -EPROBE_DEFER)
dev_err(dev,
"Error: The gpios parameter is missing or invalid.\n");
return ret;
}
memset(&props, 0, sizeof(props));
props.type = BACKLIGHT_RAW;
props.max_brightness = 1;
bl = devm_backlight_device_register(dev, dev_name(dev), dev, gbl,
&gpio_backlight_ops, &props);
if (IS_ERR(bl)) {
dev_err(dev, "failed to register backlight\n");
return PTR_ERR(bl);
}
/* Set the initial power state */
if (!of_node || !of_node->phandle)
/* Not booted with device tree or no phandle link to the node */
bl->props.power = def_value ? FB_BLANK_UNBLANK
: FB_BLANK_POWERDOWN;
else if (gpiod_get_value_cansleep(gbl->gpiod) == 0)
bl->props.power = FB_BLANK_POWERDOWN;
else
bl->props.power = FB_BLANK_UNBLANK;
bl->props.brightness = 1;
init_brightness = backlight_get_brightness(bl);
ret = gpiod_direction_output(gbl->gpiod, init_brightness);
if (ret) {
dev_err(dev, "failed to set initial brightness\n");
return ret;
}
platform_set_drvdata(pdev, bl);
return 0;
}
static struct of_device_id gpio_backlight_of_match[] = {
{ .compatible = "gpio-backlight" },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, gpio_backlight_of_match);
static struct platform_driver gpio_backlight_driver = {
.driver = {
.name = "gpio-backlight",
.of_match_table = gpio_backlight_of_match,
},
.probe = gpio_backlight_probe,
};
module_platform_driver(gpio_backlight_driver);
MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
MODULE_DESCRIPTION("GPIO-based Backlight Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:gpio-backlight");
|
