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