summaryrefslogtreecommitdiff
path: root/drivers/video/backlight/ot200_bl.c
blob: f5a5202dd79d4c1cbba5b11631f323fa5bf59ee3 (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
/*
 * Copyright (C) 2012 Bachmann electronic GmbH
 *	Christian Gmeiner <christian.gmeiner@gmail.com>
 *
 * Backlight driver for ot200 visualisation device from
 * Bachmann electronic GmbH.
 *
 * 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/fb.h>
#include <linux/backlight.h>
#include <linux/gpio.h>
#include <linux/platform_device.h>
#include <linux/cs5535.h>

static struct cs5535_mfgpt_timer *pwm_timer;

/* this array defines the mapping of brightness in % to pwm frequency */
static const u8 dim_table[101] = {0, 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2,
				  2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4,
				  4, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 9, 9,
				  10, 10, 11, 11, 12, 12, 13, 14, 15, 15, 16,
				  17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 28,
				  30, 31, 33, 35, 37, 39, 41, 43, 45, 47, 50,
				  53, 55, 58, 61, 65, 68, 72, 75, 79, 84, 88,
				  93, 97, 103, 108, 114, 120, 126, 133, 140,
				  147, 155, 163};

struct ot200_backlight_data {
	int current_brightness;
};

#define GPIO_DIMM	27
#define SCALE		1
#define CMP1MODE	0x2	/* compare on GE; output high on compare
				 * greater than or equal */
#define PWM_SETUP	(SCALE | CMP1MODE << 6 | MFGPT_SETUP_CNTEN)
#define MAX_COMP2	163

static int ot200_backlight_update_status(struct backlight_device *bl)
{
	struct ot200_backlight_data *data = bl_get_data(bl);
	int brightness = bl->props.brightness;

	if (bl->props.state & BL_CORE_FBBLANK)
		brightness = 0;

	/* enable or disable PWM timer */
	if (brightness == 0)
		cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, 0);
	else if (data->current_brightness == 0) {
		cs5535_mfgpt_write(pwm_timer, MFGPT_REG_COUNTER, 0);
		cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP,
			MFGPT_SETUP_CNTEN);
	}

	/* apply new brightness value */
	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1,
		MAX_COMP2 - dim_table[brightness]);
	data->current_brightness = brightness;

	return 0;
}

static int ot200_backlight_get_brightness(struct backlight_device *bl)
{
	struct ot200_backlight_data *data = bl_get_data(bl);
	return data->current_brightness;
}

static const struct backlight_ops ot200_backlight_ops = {
	.update_status	= ot200_backlight_update_status,
	.get_brightness	= ot200_backlight_get_brightness,
};

static int ot200_backlight_probe(struct platform_device *pdev)
{
	struct backlight_device *bl;
	struct ot200_backlight_data *data;
	struct backlight_properties props;
	int retval = 0;

	/* request gpio */
	if (devm_gpio_request(&pdev->dev, GPIO_DIMM,
				"ot200 backlight dimmer") < 0) {
		dev_err(&pdev->dev, "failed to request GPIO %d\n", GPIO_DIMM);
		return -ENODEV;
	}

	/* request timer */
	pwm_timer = cs5535_mfgpt_alloc_timer(7, MFGPT_DOMAIN_ANY);
	if (!pwm_timer) {
		dev_err(&pdev->dev, "MFGPT 7 not available\n");
		return -ENODEV;
	}

	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
	if (!data) {
		retval = -ENOMEM;
		goto error_devm_kzalloc;
	}

	/* setup gpio */
	cs5535_gpio_set(GPIO_DIMM, GPIO_OUTPUT_ENABLE);
	cs5535_gpio_set(GPIO_DIMM, GPIO_OUTPUT_AUX1);

	/* setup timer */
	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1, 0);
	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP2, MAX_COMP2);
	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, PWM_SETUP);

	data->current_brightness = 100;
	props.max_brightness = 100;
	props.brightness = 100;
	props.type = BACKLIGHT_RAW;

	bl = devm_backlight_device_register(&pdev->dev, dev_name(&pdev->dev),
					&pdev->dev, data, &ot200_backlight_ops,
					&props);
	if (IS_ERR(bl)) {
		dev_err(&pdev->dev, "failed to register backlight\n");
		retval = PTR_ERR(bl);
		goto error_devm_kzalloc;
	}

	platform_set_drvdata(pdev, bl);

	return 0;

error_devm_kzalloc:
	cs5535_mfgpt_free_timer(pwm_timer);
	return retval;
}

static int ot200_backlight_remove(struct platform_device *pdev)
{
	/* on module unload set brightness to 100% */
	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_COUNTER, 0);
	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_SETUP, MFGPT_SETUP_CNTEN);
	cs5535_mfgpt_write(pwm_timer, MFGPT_REG_CMP1,
		MAX_COMP2 - dim_table[100]);

	cs5535_mfgpt_free_timer(pwm_timer);

	return 0;
}

static struct platform_driver ot200_backlight_driver = {
	.driver		= {
		.name	= "ot200-backlight",
		.owner	= THIS_MODULE,
	},
	.probe		= ot200_backlight_probe,
	.remove		= ot200_backlight_remove,
};

module_platform_driver(ot200_backlight_driver);

MODULE_DESCRIPTION("backlight driver for ot200 visualisation device");
MODULE_AUTHOR("Christian Gmeiner <christian.gmeiner@gmail.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ot200-backlight");