1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Backlight driver for Maxim MAX8925
4  *
5  * Copyright (C) 2009 Marvell International Ltd.
6  *      Haojian Zhuang <haojian.zhuang@marvell.com>
7  */
8 
9 #include <linux/init.h>
10 #include <linux/kernel.h>
11 #include <linux/platform_device.h>
12 #include <linux/i2c.h>
13 #include <linux/backlight.h>
14 #include <linux/mfd/max8925.h>
15 #include <linux/slab.h>
16 #include <linux/module.h>
17 
18 #define MAX_BRIGHTNESS		(0xff)
19 #define MIN_BRIGHTNESS		(0)
20 
21 #define LWX_FREQ(x)		(((x - 601) / 100) & 0x7)
22 
23 struct max8925_backlight_data {
24 	struct max8925_chip	*chip;
25 
26 	int	current_brightness;
27 	int	reg_mode_cntl;
28 	int	reg_cntl;
29 };
30 
max8925_backlight_set(struct backlight_device * bl,int brightness)31 static int max8925_backlight_set(struct backlight_device *bl, int brightness)
32 {
33 	struct max8925_backlight_data *data = bl_get_data(bl);
34 	struct max8925_chip *chip = data->chip;
35 	unsigned char value;
36 	int ret;
37 
38 	if (brightness > MAX_BRIGHTNESS)
39 		value = MAX_BRIGHTNESS;
40 	else
41 		value = brightness;
42 
43 	ret = max8925_reg_write(chip->i2c, data->reg_cntl, value);
44 	if (ret < 0)
45 		goto out;
46 
47 	if (!data->current_brightness && brightness)
48 		/* enable WLED output */
49 		ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 1);
50 	else if (!brightness)
51 		/* disable WLED output */
52 		ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 0);
53 	if (ret < 0)
54 		goto out;
55 	dev_dbg(chip->dev, "set brightness %d\n", value);
56 	data->current_brightness = value;
57 	return 0;
58 out:
59 	dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n",
60 		value, ret);
61 	return ret;
62 }
63 
max8925_backlight_update_status(struct backlight_device * bl)64 static int max8925_backlight_update_status(struct backlight_device *bl)
65 {
66 	return max8925_backlight_set(bl, backlight_get_brightness(bl));
67 }
68 
max8925_backlight_get_brightness(struct backlight_device * bl)69 static int max8925_backlight_get_brightness(struct backlight_device *bl)
70 {
71 	struct max8925_backlight_data *data = bl_get_data(bl);
72 	struct max8925_chip *chip = data->chip;
73 	int ret;
74 
75 	ret = max8925_reg_read(chip->i2c, data->reg_cntl);
76 	if (ret < 0)
77 		return -EINVAL;
78 	data->current_brightness = ret;
79 	dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness);
80 	return ret;
81 }
82 
83 static const struct backlight_ops max8925_backlight_ops = {
84 	.options	= BL_CORE_SUSPENDRESUME,
85 	.update_status	= max8925_backlight_update_status,
86 	.get_brightness	= max8925_backlight_get_brightness,
87 };
88 
max8925_backlight_dt_init(struct platform_device * pdev)89 static void max8925_backlight_dt_init(struct platform_device *pdev)
90 {
91 	struct device_node *nproot = pdev->dev.parent->of_node, *np;
92 	struct max8925_backlight_pdata *pdata;
93 	u32 val;
94 
95 	if (!nproot || !IS_ENABLED(CONFIG_OF))
96 		return;
97 
98 	pdata = devm_kzalloc(&pdev->dev,
99 			     sizeof(struct max8925_backlight_pdata),
100 			     GFP_KERNEL);
101 	if (!pdata)
102 		return;
103 
104 	np = of_get_child_by_name(nproot, "backlight");
105 	if (!np) {
106 		dev_err(&pdev->dev, "failed to find backlight node\n");
107 		return;
108 	}
109 
110 	if (!of_property_read_u32(np, "maxim,max8925-dual-string", &val))
111 		pdata->dual_string = val;
112 
113 	of_node_put(np);
114 
115 	pdev->dev.platform_data = pdata;
116 }
117 
max8925_backlight_probe(struct platform_device * pdev)118 static int max8925_backlight_probe(struct platform_device *pdev)
119 {
120 	struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent);
121 	struct max8925_backlight_pdata *pdata;
122 	struct max8925_backlight_data *data;
123 	struct backlight_device *bl;
124 	struct backlight_properties props;
125 	struct resource *res;
126 	unsigned char value;
127 	int ret = 0;
128 
129 	data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data),
130 			    GFP_KERNEL);
131 	if (data == NULL)
132 		return -ENOMEM;
133 
134 	res = platform_get_resource(pdev, IORESOURCE_REG, 0);
135 	if (!res) {
136 		dev_err(&pdev->dev, "No REG resource for mode control!\n");
137 		return -ENXIO;
138 	}
139 	data->reg_mode_cntl = res->start;
140 	res = platform_get_resource(pdev, IORESOURCE_REG, 1);
141 	if (!res) {
142 		dev_err(&pdev->dev, "No REG resource for control!\n");
143 		return -ENXIO;
144 	}
145 	data->reg_cntl = res->start;
146 
147 	data->chip = chip;
148 	data->current_brightness = 0;
149 
150 	memset(&props, 0, sizeof(struct backlight_properties));
151 	props.type = BACKLIGHT_RAW;
152 	props.max_brightness = MAX_BRIGHTNESS;
153 	bl = devm_backlight_device_register(&pdev->dev, "max8925-backlight",
154 					&pdev->dev, data,
155 					&max8925_backlight_ops, &props);
156 	if (IS_ERR(bl)) {
157 		dev_err(&pdev->dev, "failed to register backlight\n");
158 		return PTR_ERR(bl);
159 	}
160 	bl->props.brightness = MAX_BRIGHTNESS;
161 
162 	platform_set_drvdata(pdev, bl);
163 
164 	value = 0;
165 	if (!pdev->dev.platform_data)
166 		max8925_backlight_dt_init(pdev);
167 
168 	pdata = pdev->dev.platform_data;
169 	if (pdata) {
170 		if (pdata->lxw_scl)
171 			value |= (1 << 7);
172 		if (pdata->lxw_freq)
173 			value |= (LWX_FREQ(pdata->lxw_freq) << 4);
174 		if (pdata->dual_string)
175 			value |= (1 << 1);
176 	}
177 	ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value);
178 	if (ret < 0)
179 		return ret;
180 	backlight_update_status(bl);
181 	return 0;
182 }
183 
184 static struct platform_driver max8925_backlight_driver = {
185 	.driver		= {
186 		.name	= "max8925-backlight",
187 	},
188 	.probe		= max8925_backlight_probe,
189 };
190 
191 module_platform_driver(max8925_backlight_driver);
192 
193 MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925");
194 MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
195 MODULE_LICENSE("GPL");
196 MODULE_ALIAS("platform:max8925-backlight");
197