summaryrefslogtreecommitdiff
path: root/drivers/video/backlight/pwm_bl.c
blob: 8346dfc01cf695266a39872c7999f7ec7bd387c7 (plain)
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
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
/*
 * linux/drivers/video/backlight/pwm_bl.c
 *
 * simple PWM based backlight control, board code has to setup
 * 1) pin configuration so PWM waveforms can output
 * 2) platform_data casts to the PWM id (0/1/2/3 on PXA)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/fb.h>
#include <linux/backlight.h>
#include <linux/err.h>
#include <linux/pwm.h>
#include <linux/pwm_backlight.h>

struct pwm_bl_data {
	struct pwm_device	*pwm;
	unsigned int		period;
	int			(*notify)(int brightness);
};

static int pwm_backlight_update_status(struct backlight_device *bl)
{
	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
	int brightness = bl->props.brightness;
	int max = bl->props.max_brightness;

	if (bl->props.power != FB_BLANK_UNBLANK)
		brightness = 0;

	if (bl->props.fb_blank != FB_BLANK_UNBLANK)
		brightness = 0;

	if (pb->notify)
		brightness = pb->notify(brightness);

	if (brightness == 0) {
		pwm_config(pb->pwm, 0, pb->period);
		pwm_disable(pb->pwm);
	} else {
		pwm_config(pb->pwm, brightness * pb->period / max, pb->period);
		pwm_enable(pb->pwm);
	}
	return 0;
}

static int pwm_backlight_get_brightness(struct backlight_device *bl)
{
	return bl->props.brightness;
}

static struct backlight_ops pwm_backlight_ops = {
	.update_status	= pwm_backlight_update_status,
	.get_brightness	= pwm_backlight_get_brightness,
};

static int pwm_backlight_probe(struct platform_device *pdev)
{
	struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
	struct backlight_device *bl;
	struct pwm_bl_data *pb;
	int ret;

	if (!data)
		return -EINVAL;

	if (data->init) {
		ret = data->init(&pdev->dev);
		if (ret < 0)
			return ret;
	}

	pb = kzalloc(sizeof(*pb), GFP_KERNEL);
	if (!pb) {
		ret = -ENOMEM;
		goto err_alloc;
	}

	pb->period = data->pwm_period_ns;
	pb->notify = data->notify;

	pb->pwm = pwm_request(data->pwm_id, "backlight");
	if (pb->pwm == NULL) {
		dev_err(&pdev->dev, "unable to request PWM for backlight\n");
		ret = -EBUSY;
		goto err_pwm;
	}

	bl = backlight_device_register(pdev->name, &pdev->dev,
			pb, &pwm_backlight_ops);
	if (IS_ERR(bl)) {
		dev_err(&pdev->dev, "failed to register backlight\n");
		ret = PTR_ERR(bl);
		goto err_bl;
	}

	bl->props.max_brightness = data->max_brightness;
	bl->props.brightness = data->dft_brightness;
	backlight_update_status(bl);

	platform_set_drvdata(pdev, bl);
	return 0;

err_bl:
	pwm_free(pb->pwm);
err_pwm:
	kfree(pb);
err_alloc:
	if (data->exit)
		data->exit(&pdev->dev);
	return ret;
}

static int pwm_backlight_remove(struct platform_device *pdev)
{
	struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
	struct backlight_device *bl = platform_get_drvdata(pdev);
	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);

	backlight_device_unregister(bl);
	pwm_config(pb->pwm, 0, pb->period);
	pwm_disable(pb->pwm);
	pwm_free(pb->pwm);
	kfree(pb);
	if (data->exit)
		data->exit(&pdev->dev);
	return 0;
}

#ifdef CONFIG_PM
static int pwm_backlight_suspend(struct platform_device *pdev,
				 pm_message_t state)
{
	struct backlight_device *bl = platform_get_drvdata(pdev);
	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);

	pwm_config(pb->pwm, 0, pb->period);
	pwm_disable(pb->pwm);
	return 0;
}

static int pwm_backlight_resume(struct platform_device *pdev)
{
	struct backlight_device *bl = platform_get_drvdata(pdev);

	backlight_update_status(bl);
	return 0;
}
#else
#define pwm_backlight_suspend	NULL
#define pwm_backlight_resume	NULL
#endif

static struct platform_driver pwm_backlight_driver = {
	.driver		= {
		.name	= "pwm-backlight",
		.owner	= THIS_MODULE,
	},
	.probe		= pwm_backlight_probe,
	.remove		= pwm_backlight_remove,
	.suspend	= pwm_backlight_suspend,
	.resume		= pwm_backlight_resume,
};

static int __init pwm_backlight_init(void)
{
	return platform_driver_register(&pwm_backlight_driver);
}
module_init(pwm_backlight_init);

static void __exit pwm_backlight_exit(void)
{
	platform_driver_unregister(&pwm_backlight_driver);
}
module_exit(pwm_backlight_exit);

MODULE_DESCRIPTION("PWM based Backlight Driver");
MODULE_LICENSE("GPL");