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515c096720
The device-tree enablement for max8925 has several problems, but besides the bindings being wrong (and not having seen review) there's also some bad coding practices on how to fill in the platform_data from device tree. I came across this since it causes a warning when compiling mmp2_defconfig, and instead of doing the minimal fix to silence the warning, I restructured the code a bit. This silences the warning: drivers/video/backlight/max8925_bl.c: In function 'max8925_backlight_probe': drivers/video/backlight/max8925_bl.c:177:3: warning: statement with no effect [-Wunused-value] Note that the bindings themselves need to be revisited too, but that will affect more than just the backlight driver and is best done separately; this just fixes the bad code for the backlight driver. Acked-by: Jingoo Han <jg1.han@samsung.com> Signed-off-by: Olof Johansson <olof@lixom.net>
222 lines
5.5 KiB
C
222 lines
5.5 KiB
C
/*
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* Backlight driver for Maxim MAX8925
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*
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* Copyright (C) 2009 Marvell International Ltd.
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* Haojian Zhuang <haojian.zhuang@marvell.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/fb.h>
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#include <linux/i2c.h>
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#include <linux/backlight.h>
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#include <linux/mfd/max8925.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#define MAX_BRIGHTNESS (0xff)
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#define MIN_BRIGHTNESS (0)
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#define LWX_FREQ(x) (((x - 601) / 100) & 0x7)
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struct max8925_backlight_data {
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struct max8925_chip *chip;
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int current_brightness;
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int reg_mode_cntl;
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int reg_cntl;
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};
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static int max8925_backlight_set(struct backlight_device *bl, int brightness)
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{
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struct max8925_backlight_data *data = bl_get_data(bl);
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struct max8925_chip *chip = data->chip;
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unsigned char value;
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int ret;
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if (brightness > MAX_BRIGHTNESS)
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value = MAX_BRIGHTNESS;
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else
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value = brightness;
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ret = max8925_reg_write(chip->i2c, data->reg_cntl, value);
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if (ret < 0)
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goto out;
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if (!data->current_brightness && brightness)
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/* enable WLED output */
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ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 1);
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else if (!brightness)
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/* disable WLED output */
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ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 1, 0);
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if (ret < 0)
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goto out;
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dev_dbg(chip->dev, "set brightness %d\n", value);
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data->current_brightness = value;
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return 0;
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out:
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dev_dbg(chip->dev, "set brightness %d failure with return value:%d\n",
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value, ret);
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return ret;
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}
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static int max8925_backlight_update_status(struct backlight_device *bl)
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{
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int brightness = bl->props.brightness;
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if (bl->props.power != FB_BLANK_UNBLANK)
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brightness = 0;
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if (bl->props.fb_blank != FB_BLANK_UNBLANK)
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brightness = 0;
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if (bl->props.state & BL_CORE_SUSPENDED)
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brightness = 0;
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return max8925_backlight_set(bl, brightness);
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}
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static int max8925_backlight_get_brightness(struct backlight_device *bl)
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{
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struct max8925_backlight_data *data = bl_get_data(bl);
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struct max8925_chip *chip = data->chip;
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int ret;
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ret = max8925_reg_read(chip->i2c, data->reg_cntl);
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if (ret < 0)
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return -EINVAL;
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data->current_brightness = ret;
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dev_dbg(chip->dev, "get brightness %d\n", data->current_brightness);
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return ret;
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}
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static const struct backlight_ops max8925_backlight_ops = {
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.options = BL_CORE_SUSPENDRESUME,
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.update_status = max8925_backlight_update_status,
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.get_brightness = max8925_backlight_get_brightness,
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};
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static void max8925_backlight_dt_init(struct platform_device *pdev)
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{
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struct device_node *nproot = pdev->dev.parent->of_node, *np;
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struct max8925_backlight_pdata *pdata;
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u32 val;
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if (!nproot || !IS_ENABLED(CONFIG_OF))
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return;
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pdata = devm_kzalloc(&pdev->dev,
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sizeof(struct max8925_backlight_pdata),
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GFP_KERNEL);
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if (!pdata)
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return;
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np = of_find_node_by_name(nproot, "backlight");
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if (!np) {
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dev_err(&pdev->dev, "failed to find backlight node\n");
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return;
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}
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if (!of_property_read_u32(np, "maxim,max8925-dual-string", &val))
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pdata->dual_string = val;
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pdev->dev.platform_data = pdata;
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}
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static int max8925_backlight_probe(struct platform_device *pdev)
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{
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struct max8925_chip *chip = dev_get_drvdata(pdev->dev.parent);
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struct max8925_backlight_pdata *pdata;
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struct max8925_backlight_data *data;
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struct backlight_device *bl;
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struct backlight_properties props;
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struct resource *res;
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unsigned char value;
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int ret = 0;
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data = devm_kzalloc(&pdev->dev, sizeof(struct max8925_backlight_data),
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GFP_KERNEL);
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if (data == NULL)
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return -ENOMEM;
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res = platform_get_resource(pdev, IORESOURCE_REG, 0);
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if (!res) {
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dev_err(&pdev->dev, "No REG resource for mode control!\n");
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return -ENXIO;
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}
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data->reg_mode_cntl = res->start;
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res = platform_get_resource(pdev, IORESOURCE_REG, 1);
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if (!res) {
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dev_err(&pdev->dev, "No REG resource for control!\n");
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return -ENXIO;
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}
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data->reg_cntl = res->start;
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data->chip = chip;
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data->current_brightness = 0;
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memset(&props, 0, sizeof(struct backlight_properties));
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props.type = BACKLIGHT_RAW;
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props.max_brightness = MAX_BRIGHTNESS;
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bl = backlight_device_register("max8925-backlight", &pdev->dev, data,
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&max8925_backlight_ops, &props);
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if (IS_ERR(bl)) {
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dev_err(&pdev->dev, "failed to register backlight\n");
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return PTR_ERR(bl);
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}
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bl->props.brightness = MAX_BRIGHTNESS;
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platform_set_drvdata(pdev, bl);
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value = 0;
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if (!pdev->dev.platform_data)
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max8925_backlight_dt_init(pdev);
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pdata = pdev->dev.platform_data;
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if (pdata) {
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if (pdata->lxw_scl)
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value |= (1 << 7);
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if (pdata->lxw_freq)
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value |= (LWX_FREQ(pdata->lxw_freq) << 4);
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if (pdata->dual_string)
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value |= (1 << 1);
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}
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ret = max8925_set_bits(chip->i2c, data->reg_mode_cntl, 0xfe, value);
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if (ret < 0)
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goto out_brt;
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backlight_update_status(bl);
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return 0;
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out_brt:
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backlight_device_unregister(bl);
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return ret;
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}
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static int max8925_backlight_remove(struct platform_device *pdev)
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{
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struct backlight_device *bl = platform_get_drvdata(pdev);
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backlight_device_unregister(bl);
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return 0;
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}
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static struct platform_driver max8925_backlight_driver = {
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.driver = {
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.name = "max8925-backlight",
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.owner = THIS_MODULE,
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},
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.probe = max8925_backlight_probe,
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.remove = max8925_backlight_remove,
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};
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module_platform_driver(max8925_backlight_driver);
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MODULE_DESCRIPTION("Backlight Driver for Maxim MAX8925");
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MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:max8925-backlight");
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