max8925_bl.c revision 81178e021689bf86c328f144aa0f0e1b50f5e94c 
1/*
2 * Backlight driver for Maxim MAX8925
3 *
4 * Copyright (C) 2009 Marvell International Ltd.
5 *      Haojian Zhuang <haojian.zhuang@marvell.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12#include <linux/init.h>
13#include <linux/kernel.h>
14#include <linux/platform_device.h>
15#include <linux/fb.h>
16#include <linux/i2c.h>
17#include <linux/backlight.h>
18#include <linux/mfd/max8925.h>
19#include <linux/slab.h>
20#include <linux/module.h>
21
22#define MAX_BRIGHTNESS		(0xff)
23#define MIN_BRIGHTNESS		(0)
24
25#define LWX_FREQ(x)		(((x - 601) / 100) & 0x7)
26
27struct max8925_backlight_data {
28	struct max8925_chip	*chip;
29
30	int		current_brightness;
31};
32
33static int max8925_backlight_set(struct backlight_device *bl, int brightness)
34{
35	struct max8925_backlight_data *data = bl_get_data(bl);
36	struct max8925_chip *chip = data->chip;
37	unsigned char value;
38	int ret;
39
40	if (brightness > MAX_BRIGHTNESS)
41		value = MAX_BRIGHTNESS;
42	else
43		value = brightness;
44
45	ret = max8925_reg_write(chip->i2c, MAX8925_WLED_CNTL, value);
46	if (ret < 0)
47		goto out;
48
49	if (!data->current_brightness && brightness)
50		/* enable WLED output */
51		ret = max8925_set_bits(chip->i2c, MAX8925_WLED_MODE_CNTL, 1, 1);
52	else if (!brightness)
53		/* disable WLED output */
54		ret = max8925_set_bits(chip->i2c, MAX8925_WLED_MODE_CNTL, 1, 0);
55	if (ret < 0)
56		goto out;
57	dev_dbg(chip->dev, "set brightness %d\n", value);
58	data->current_brightness = value;
59	return 0;
60out:
61	dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n",
62		value, ret);
63	return ret;
64}
65
66static int max8925_backlight_update_status(struct backlight_device *bl)
67{
68	int brightness = bl->props.brightness;
69
70	if (bl->props.power != FB_BLANK_UNBLANK)
71		brightness = 0;
72
73	if (bl->props.fb_blank != FB_BLANK_UNBLANK)
74		brightness = 0;
75
76	if (bl->props.state & BL_CORE_SUSPENDED)
77		brightness = 0;
78
79	return max8925_backlight_set(bl, brightness);
80}
81
82static int max8925_backlight_get_brightness(struct backlight_device *bl)
83{
84	struct max8925_backlight_data *data = bl_get_data(bl);
85	struct max8925_chip *chip = data->chip;
86	int ret;
87
88	ret = max8925_reg_read(chip->i2c, MAX8925_WLED_CNTL);
89	if (ret < 0)
90		return -EINVAL;
91	data->current_brightness = ret;
92	dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness);
93	return ret;
94}
95
96static const struct backlight_ops max8925_backlight_ops = {
97	.options	= BL_CORE_SUSPENDRESUME,
98	.update_status	= max8925_backlight_update_status,
99	.get_brightness	= max8925_backlight_get_brightness,
100};
101
102static int __devinit max8925_backlight_probe(struct platform_device *pdev)
103{
104	struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent);
105	struct max8925_platform_data *max8925_pdata;
106	struct max8925_backlight_pdata *pdata = NULL;
107	struct max8925_backlight_data *data;
108	struct backlight_device *bl;
109	struct backlight_properties props;
110	struct resource *res;
111	char name[MAX8925_NAME_SIZE];
112	unsigned char value;
113	int ret;
114
115	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
116	if (res == NULL) {
117		dev_err(&pdev->dev, "No I/O resource!\n");
118		return -EINVAL;
119	}
120
121	if (pdev->dev.parent->platform_data) {
122		max8925_pdata = pdev->dev.parent->platform_data;
123		pdata = max8925_pdata->backlight;
124	}
125
126	if (!pdata) {
127		dev_err(&pdev->dev, "platform data isn't assigned to "
128			"backlight\n");
129		return -EINVAL;
130	}
131
132	data = kzalloc(sizeof(struct max8925_backlight_data), GFP_KERNEL);
133	if (data == NULL)
134		return -ENOMEM;
135	strncpy(name, res->name, MAX8925_NAME_SIZE);
136	data->chip = chip;
137	data->current_brightness = 0;
138
139	memset(&props, 0, sizeof(struct backlight_properties));
140	props.type = BACKLIGHT_RAW;
141	props.max_brightness = MAX_BRIGHTNESS;
142	bl = backlight_device_register(name, &pdev->dev, data,
143					&max8925_backlight_ops, &props);
144	if (IS_ERR(bl)) {
145		dev_err(&pdev->dev, "failed to register backlight\n");
146		kfree(data);
147		return PTR_ERR(bl);
148	}
149	bl->props.brightness = MAX_BRIGHTNESS;
150
151	platform_set_drvdata(pdev, bl);
152
153	value = 0;
154	if (pdata->lxw_scl)
155		value |= (1 << 7);
156	if (pdata->lxw_freq)
157		value |= (LWX_FREQ(pdata->lxw_freq) << 4);
158	if (pdata->dual_string)
159		value |= (1 << 1);
160	ret = max8925_set_bits(chip->i2c, MAX8925_WLED_MODE_CNTL, 0xfe, value);
161	if (ret < 0)
162		goto out;
163
164	backlight_update_status(bl);
165	return 0;
166out:
167	backlight_device_unregister(bl);
168	kfree(data);
169	return ret;
170}
171
172static int __devexit max8925_backlight_remove(struct platform_device *pdev)
173{
174	struct backlight_device *bl = platform_get_drvdata(pdev);
175	struct max8925_backlight_data *data = bl_get_data(bl);
176
177	backlight_device_unregister(bl);
178	kfree(data);
179	return 0;
180}
181
182static struct platform_driver max8925_backlight_driver = {
183	.driver		= {
184		.name	= "max8925-backlight",
185		.owner	= THIS_MODULE,
186	},
187	.probe		= max8925_backlight_probe,
188	.remove		= __devexit_p(max8925_backlight_remove),
189};
190
191module_platform_driver(max8925_backlight_driver);
192
193MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925");
194MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
195MODULE_LICENSE("GPL");
196MODULE_ALIAS("platform:max8925-backlight");
197