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9#include <linux/init.h>
10#include <linux/kernel.h>
11#include <linux/platform_device.h>
12#include <linux/fb.h>
13#include <linux/i2c.h>
14#include <linux/backlight.h>
15#include <linux/mfd/max8925.h>
16#include <linux/slab.h>
17#include <linux/module.h>
18
19#define MAX_BRIGHTNESS (0xff)
20#define MIN_BRIGHTNESS (0)
21
22#define LWX_FREQ(x) (((x - 601) / 100) & 0x7)
23
24struct max8925_backlight_data {
25 struct max8925_chip *chip;
26
27 int current_brightness;
28 int reg_mode_cntl;
29 int reg_cntl;
30};
31
32static int max8925_backlight_set(struct backlight_device *bl, int brightness)
33{
34 struct max8925_backlight_data *data = bl_get_data(bl);
35 struct max8925_chip *chip = data->chip;
36 unsigned char value;
37 int ret;
38
39 if (brightness > MAX_BRIGHTNESS)
40 value = MAX_BRIGHTNESS;
41 else
42 value = brightness;
43
44 ret = max8925_reg_write(chip->i2c, data->reg_cntl, value);
45 if (ret < 0)
46 goto out;
47
48 if (!data->current_brightness && brightness)
49
50 ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 1);
51 else if (!brightness)
52
53 ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 0);
54 if (ret < 0)
55 goto out;
56 dev_dbg(chip->dev, "set brightness %d\n", value);
57 data->current_brightness = value;
58 return 0;
59out:
60 dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n",
61 value, ret);
62 return ret;
63}
64
65static int max8925_backlight_update_status(struct backlight_device *bl)
66{
67 return max8925_backlight_set(bl, backlight_get_brightness(bl));
68}
69
70static int max8925_backlight_get_brightness(struct backlight_device *bl)
71{
72 struct max8925_backlight_data *data = bl_get_data(bl);
73 struct max8925_chip *chip = data->chip;
74 int ret;
75
76 ret = max8925_reg_read(chip->i2c, data->reg_cntl);
77 if (ret < 0)
78 return -EINVAL;
79 data->current_brightness = ret;
80 dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness);
81 return ret;
82}
83
84static const struct backlight_ops max8925_backlight_ops = {
85 .options = BL_CORE_SUSPENDRESUME,
86 .update_status = max8925_backlight_update_status,
87 .get_brightness = max8925_backlight_get_brightness,
88};
89
90static void max8925_backlight_dt_init(struct platform_device *pdev)
91{
92 struct device_node *nproot = pdev->dev.parent->of_node, *np;
93 struct max8925_backlight_pdata *pdata;
94 u32 val;
95
96 if (!nproot || !IS_ENABLED(CONFIG_OF))
97 return;
98
99 pdata = devm_kzalloc(&pdev->dev,
100 sizeof(struct max8925_backlight_pdata),
101 GFP_KERNEL);
102 if (!pdata)
103 return;
104
105 np = of_get_child_by_name(nproot, "backlight");
106 if (!np) {
107 dev_err(&pdev->dev, "failed to find backlight node\n");
108 return;
109 }
110
111 if (!of_property_read_u32(np, "maxim,max8925-dual-string", &val))
112 pdata->dual_string = val;
113
114 of_node_put(np);
115
116 pdev->dev.platform_data = pdata;
117}
118
119static int max8925_backlight_probe(struct platform_device *pdev)
120{
121 struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent);
122 struct max8925_backlight_pdata *pdata;
123 struct max8925_backlight_data *data;
124 struct backlight_device *bl;
125 struct backlight_properties props;
126 struct resource *res;
127 unsigned char value;
128 int ret = 0;
129
130 data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data),
131 GFP_KERNEL);
132 if (data == NULL)
133 return -ENOMEM;
134
135 res = platform_get_resource(pdev, IORESOURCE_REG, 0);
136 if (!res) {
137 dev_err(&pdev->dev, "No REG resource for mode control!\n");
138 return -ENXIO;
139 }
140 data->reg_mode_cntl = res->start;
141 res = platform_get_resource(pdev, IORESOURCE_REG, 1);
142 if (!res) {
143 dev_err(&pdev->dev, "No REG resource for control!\n");
144 return -ENXIO;
145 }
146 data->reg_cntl = res->start;
147
148 data->chip = chip;
149 data->current_brightness = 0;
150
151 memset(&props, 0, sizeof(struct backlight_properties));
152 props.type = BACKLIGHT_RAW;
153 props.max_brightness = MAX_BRIGHTNESS;
154 bl = devm_backlight_device_register(&pdev->dev, "max8925-backlight",
155 &pdev->dev, data,
156 &max8925_backlight_ops, &props);
157 if (IS_ERR(bl)) {
158 dev_err(&pdev->dev, "failed to register backlight\n");
159 return PTR_ERR(bl);
160 }
161 bl->props.brightness = MAX_BRIGHTNESS;
162
163 platform_set_drvdata(pdev, bl);
164
165 value = 0;
166 if (!pdev->dev.platform_data)
167 max8925_backlight_dt_init(pdev);
168
169 pdata = pdev->dev.platform_data;
170 if (pdata) {
171 if (pdata->lxw_scl)
172 value |= (1 << 7);
173 if (pdata->lxw_freq)
174 value |= (LWX_FREQ(pdata->lxw_freq) << 4);
175 if (pdata->dual_string)
176 value |= (1 << 1);
177 }
178 ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value);
179 if (ret < 0)
180 return ret;
181 backlight_update_status(bl);
182 return 0;
183}
184
185static struct platform_driver max8925_backlight_driver = {
186 .driver = {
187 .name = "max8925-backlight",
188 },
189 .probe = max8925_backlight_probe,
190};
191
192module_platform_driver(max8925_backlight_driver);
193
194MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925");
195MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
196MODULE_LICENSE("GPL");
197MODULE_ALIAS("platform:max8925-backlight");
198
