1 // SPDX-License-Identifier: GPL-2.0-only
3 * Backlight driver for Maxim MAX8925
5 * Copyright (C) 2009 Marvell International Ltd.
6 * Haojian Zhuang <haojian.zhuang@marvell.com>
9 #include <linux/init.h>
10 #include <linux/kernel.h>
11 #include <linux/platform_device.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>
19 #define MAX_BRIGHTNESS (0xff)
20 #define MIN_BRIGHTNESS (0)
22 #define LWX_FREQ(x) (((x - 601) / 100) & 0x7)
24 struct max8925_backlight_data {
25 struct max8925_chip *chip;
27 int current_brightness;
32 static int max8925_backlight_set(struct backlight_device *bl, int brightness)
34 struct max8925_backlight_data *data = bl_get_data(bl);
35 struct max8925_chip *chip = data->chip;
39 if (brightness > MAX_BRIGHTNESS)
40 value = MAX_BRIGHTNESS;
44 ret = max8925_reg_write(chip->i2c, data->reg_cntl, value);
48 if (!data->current_brightness && brightness)
49 /* enable WLED output */
50 ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 1);
52 /* disable WLED output */
53 ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 0);
56 dev_dbg(chip->dev, "set brightness %d\n", value);
57 data->current_brightness = value;
60 dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n",
65 static int max8925_backlight_update_status(struct backlight_device *bl)
67 return max8925_backlight_set(bl, backlight_get_brightness(bl));
70 static int max8925_backlight_get_brightness(struct backlight_device *bl)
72 struct max8925_backlight_data *data = bl_get_data(bl);
73 struct max8925_chip *chip = data->chip;
76 ret = max8925_reg_read(chip->i2c, data->reg_cntl);
79 data->current_brightness = ret;
80 dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness);
84 static 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,
90 static void max8925_backlight_dt_init(struct platform_device *pdev)
92 struct device_node *nproot = pdev->dev.parent->of_node, *np;
93 struct max8925_backlight_pdata *pdata;
96 if (!nproot || !IS_ENABLED(CONFIG_OF))
99 pdata = devm_kzalloc(&pdev->dev,
100 sizeof(struct max8925_backlight_pdata),
105 np = of_get_child_by_name(nproot, "backlight");
107 dev_err(&pdev->dev, "failed to find backlight node\n");
111 if (!of_property_read_u32(np, "maxim,max8925-dual-string", &val))
112 pdata->dual_string = val;
116 pdev->dev.platform_data = pdata;
119 static int max8925_backlight_probe(struct platform_device *pdev)
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;
130 data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data),
135 res = platform_get_resource(pdev, IORESOURCE_REG, 0);
137 dev_err(&pdev->dev, "No REG resource for mode control!\n");
140 data->reg_mode_cntl = res->start;
141 res = platform_get_resource(pdev, IORESOURCE_REG, 1);
143 dev_err(&pdev->dev, "No REG resource for control!\n");
146 data->reg_cntl = res->start;
149 data->current_brightness = 0;
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",
156 &max8925_backlight_ops, &props);
158 dev_err(&pdev->dev, "failed to register backlight\n");
161 bl->props.brightness = MAX_BRIGHTNESS;
163 platform_set_drvdata(pdev, bl);
166 if (!pdev->dev.platform_data)
167 max8925_backlight_dt_init(pdev);
169 pdata = pdev->dev.platform_data;
174 value |= (LWX_FREQ(pdata->lxw_freq) << 4);
175 if (pdata->dual_string)
178 ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value);
181 backlight_update_status(bl);
185 static struct platform_driver max8925_backlight_driver = {
187 .name = "max8925-backlight",
189 .probe = max8925_backlight_probe,
192 module_platform_driver(max8925_backlight_driver);
194 MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925");
195 MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
196 MODULE_LICENSE("GPL");
197 MODULE_ALIAS("platform:max8925-backlight");