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	int	reg_mode_cntl;
32	int	reg_cntl;
33};
34
35static int max8925_backlight_set(struct backlight_device *bl, int brightness)
36{
37	struct max8925_backlight_data *data = bl_get_data(bl);
38	struct max8925_chip *chip = data->chip;
39	unsigned char value;
40	int ret;
41
42	if (brightness > MAX_BRIGHTNESS)
43		value = MAX_BRIGHTNESS;
44	else
45		value = brightness;
46
47	ret = max8925_reg_write(chip->i2c, data->reg_cntl, value);
48	if (ret < 0)
49		goto out;
50
51	if (!data->current_brightness && brightness)
52		/* enable WLED output */
53		ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 1);
54	else if (!brightness)
55		/* disable WLED output */
56		ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 0);
57	if (ret < 0)
58		goto out;
59	dev_dbg(chip->dev, "set brightness %d\n", value);
60	data->current_brightness = value;
61	return 0;
62out:
63	dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n",
64		value, ret);
65	return ret;
66}
67
68static int max8925_backlight_update_status(struct backlight_device *bl)
69{
70	int brightness = bl->props.brightness;
71
72	if (bl->props.power != FB_BLANK_UNBLANK)
73		brightness = 0;
74
75	if (bl->props.fb_blank != FB_BLANK_UNBLANK)
76		brightness = 0;
77
78	if (bl->props.state & BL_CORE_SUSPENDED)
79		brightness = 0;
80
81	return max8925_backlight_set(bl, brightness);
82}
83
84static int max8925_backlight_get_brightness(struct backlight_device *bl)
85{
86	struct max8925_backlight_data *data = bl_get_data(bl);
87	struct max8925_chip *chip = data->chip;
88	int ret;
89
90	ret = max8925_reg_read(chip->i2c, data->reg_cntl);
91	if (ret < 0)
92		return -EINVAL;
93	data->current_brightness = ret;
94	dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness);
95	return ret;
96}
97
98static const struct backlight_ops max8925_backlight_ops = {
99	.options	= BL_CORE_SUSPENDRESUME,
100	.update_status	= max8925_backlight_update_status,
101	.get_brightness	= max8925_backlight_get_brightness,
102};
103
104static void max8925_backlight_dt_init(struct platform_device *pdev)
105{
106	struct device_node *nproot = pdev->dev.parent->of_node, *np;
107	struct max8925_backlight_pdata *pdata;
108	u32 val;
109
110	if (!nproot || !IS_ENABLED(CONFIG_OF))
111		return;
112
113	pdata = devm_kzalloc(&pdev->dev,
114			     sizeof(struct max8925_backlight_pdata),
115			     GFP_KERNEL);
116	if (!pdata)
117		return;
118
119	np = of_find_node_by_name(nproot, "backlight");
120	if (!np) {
121		dev_err(&pdev->dev, "failed to find backlight node\n");
122		return;
123	}
124
125	if (!of_property_read_u32(np, "maxim,max8925-dual-string", &val))
126		pdata->dual_string = val;
127
128	pdev->dev.platform_data = pdata;
129}
130
131static int max8925_backlight_probe(struct platform_device *pdev)
132{
133	struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent);
134	struct max8925_backlight_pdata *pdata;
135	struct max8925_backlight_data *data;
136	struct backlight_device *bl;
137	struct backlight_properties props;
138	struct resource *res;
139	unsigned char value;
140	int ret = 0;
141
142	data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data),
143			    GFP_KERNEL);
144	if (data == NULL)
145		return -ENOMEM;
146
147	res = platform_get_resource(pdev, IORESOURCE_REG, 0);
148	if (!res) {
149		dev_err(&pdev->dev, "No REG resource for mode control!\n");
150		return -ENXIO;
151	}
152	data->reg_mode_cntl = res->start;
153	res = platform_get_resource(pdev, IORESOURCE_REG, 1);
154	if (!res) {
155		dev_err(&pdev->dev, "No REG resource for control!\n");
156		return -ENXIO;
157	}
158	data->reg_cntl = res->start;
159
160	data->chip = chip;
161	data->current_brightness = 0;
162
163	memset(&props, 0, sizeof(struct backlight_properties));
164	props.type = BACKLIGHT_RAW;
165	props.max_brightness = MAX_BRIGHTNESS;
166	bl = devm_backlight_device_register(&pdev->dev, "max8925-backlight",
167					&pdev->dev, data,
168					&max8925_backlight_ops, &props);
169	if (IS_ERR(bl)) {
170		dev_err(&pdev->dev, "failed to register backlight\n");
171		return PTR_ERR(bl);
172	}
173	bl->props.brightness = MAX_BRIGHTNESS;
174
175	platform_set_drvdata(pdev, bl);
176
177	value = 0;
178	if (!pdev->dev.platform_data)
179		max8925_backlight_dt_init(pdev);
180
181	pdata = pdev->dev.platform_data;
182	if (pdata) {
183		if (pdata->lxw_scl)
184			value |= (1 << 7);
185		if (pdata->lxw_freq)
186			value |= (LWX_FREQ(pdata->lxw_freq) << 4);
187		if (pdata->dual_string)
188			value |= (1 << 1);
189	}
190	ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value);
191	if (ret < 0)
192		return ret;
193	backlight_update_status(bl);
194	return 0;
195}
196
197static struct platform_driver max8925_backlight_driver = {
198	.driver		= {
199		.name	= "max8925-backlight",
200	},
201	.probe		= max8925_backlight_probe,
202};
203
204module_platform_driver(max8925_backlight_driver);
205
206MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925");
207MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
208MODULE_LICENSE("GPL");
209MODULE_ALIAS("platform:max8925-backlight");
210