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