drivers/video/backlight/as3711_bl.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * AS3711 PMIC backlight driver, using DCDC Step Up Converters
  *
  * Copyright (C) 2012 Renesas Electronics Corporation
  * Author: Guennadi Liakhovetski, <g.liakhovetski@gmx.de>
  */

 #include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/fb.h>
 #include <linux/kernel.h>
 #include <linux/mfd/as3711.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>

 enum as3711_bl_type {
 	AS3711_BL_SU1,
 	AS3711_BL_SU2,
 };

 struct as3711_bl_data {
 	bool powered;
 	enum as3711_bl_type type;
 	int brightness;
 	struct backlight_device *bl;
 };

 struct as3711_bl_supply {
 	struct as3711_bl_data su1;
 	struct as3711_bl_data su2;
 	const struct as3711_bl_pdata *pdata;
 	struct as3711 *as3711;
 };

 static struct as3711_bl_supply *to_supply(struct as3711_bl_data *su)
 {
 	switch (su->type) {
 	case AS3711_BL_SU1:
 		return container_of(su, struct as3711_bl_supply, su1);
 	case AS3711_BL_SU2:
 		return container_of(su, struct as3711_bl_supply, su2);
 	}
 	return NULL;
 }

 static int as3711_set_brightness_auto_i(struct as3711_bl_data *data,
 					unsigned int brightness)
 {
 	struct as3711_bl_supply *supply = to_supply(data);
 	struct as3711 *as3711 = supply->as3711;
 	const struct as3711_bl_pdata *pdata = supply->pdata;
 	int ret = 0;

 	/* Only all equal current values are supported */
 	if (pdata->su2_auto_curr1)
 		ret = regmap_write(as3711->regmap, AS3711_CURR1_VALUE,
 				   brightness);
 	if (!ret && pdata->su2_auto_curr2)
 		ret = regmap_write(as3711->regmap, AS3711_CURR2_VALUE,
 				   brightness);
 	if (!ret && pdata->su2_auto_curr3)
 		ret = regmap_write(as3711->regmap, AS3711_CURR3_VALUE,
 				   brightness);

 	return ret;
 }

 static int as3711_set_brightness_v(struct as3711 *as3711,
 				   unsigned int brightness,
 				   unsigned int reg)
 {
 	if (brightness > 31)
 		return -EINVAL;

 	return regmap_update_bits(as3711->regmap, reg, 0xf0,
 				  brightness << 4);
 }

 static int as3711_bl_su2_reset(struct as3711_bl_supply *supply)
 {
 	struct as3711 *as3711 = supply->as3711;
 	int ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_5,
 				     3, supply->pdata->su2_fbprot);
 	if (!ret)
 		ret = regmap_update_bits(as3711->regmap,
 					 AS3711_STEPUP_CONTROL_2, 1, 0);
 	if (!ret)
 		ret = regmap_update_bits(as3711->regmap,
 					 AS3711_STEPUP_CONTROL_2, 1, 1);
 	return ret;
 }

 /*
  * Someone with less fragile or less expensive hardware could try to simplify
  * the brightness adjustment procedure.
  */
 static int as3711_bl_update_status(struct backlight_device *bl)
 {
 	struct as3711_bl_data *data = bl_get_data(bl);
 	struct as3711_bl_supply *supply = to_supply(data);
 	struct as3711 *as3711 = supply->as3711;
 	int brightness;
 	int ret = 0;

 	brightness = backlight_get_brightness(bl);

 	if (data->type == AS3711_BL_SU1) {
 		ret = as3711_set_brightness_v(as3711, brightness,
 					      AS3711_STEPUP_CONTROL_1);
 	} else {
 		const struct as3711_bl_pdata *pdata = supply->pdata;

 		switch (pdata->su2_feedback) {
 		case AS3711_SU2_VOLTAGE:
 			ret = as3711_set_brightness_v(as3711, brightness,
 						      AS3711_STEPUP_CONTROL_2);
 			break;
 		case AS3711_SU2_CURR_AUTO:
 			ret = as3711_set_brightness_auto_i(data, brightness / 4);
 			if (ret < 0)
 				return ret;
 			if (brightness) {
 				ret = as3711_bl_su2_reset(supply);
 				if (ret < 0)
 					return ret;
 				udelay(500);
 				ret = as3711_set_brightness_auto_i(data, brightness);
 			} else {
 				ret = regmap_update_bits(as3711->regmap,
 						AS3711_STEPUP_CONTROL_2, 1, 0);
 			}
 			break;
 		/* Manual one current feedback pin below */
 		case AS3711_SU2_CURR1:
 			ret = regmap_write(as3711->regmap, AS3711_CURR1_VALUE,
 					   brightness);
 			break;
 		case AS3711_SU2_CURR2:
 			ret = regmap_write(as3711->regmap, AS3711_CURR2_VALUE,
 					   brightness);
 			break;
 		case AS3711_SU2_CURR3:
 			ret = regmap_write(as3711->regmap, AS3711_CURR3_VALUE,
 					   brightness);
 			break;
 		default:
 			ret = -EINVAL;
 		}
 	}
 	if (!ret)
 		data->brightness = brightness;

 	return ret;
 }

 static int as3711_bl_get_brightness(struct backlight_device *bl)
 {
 	struct as3711_bl_data *data = bl_get_data(bl);

 	return data->brightness;
 }

 static const struct backlight_ops as3711_bl_ops = {
 	.update_status	= as3711_bl_update_status,
 	.get_brightness	= as3711_bl_get_brightness,
 };

 static int as3711_bl_init_su2(struct as3711_bl_supply *supply)
 {
 	struct as3711 *as3711 = supply->as3711;
 	const struct as3711_bl_pdata *pdata = supply->pdata;
 	u8 ctl = 0;
 	int ret;

 	dev_dbg(as3711->dev, "%s(): use %u\n", __func__, pdata->su2_feedback);

 	/* Turn SU2 off */
 	ret = regmap_write(as3711->regmap, AS3711_STEPUP_CONTROL_2, 0);
 	if (ret < 0)
 		return ret;

 	switch (pdata->su2_feedback) {
 	case AS3711_SU2_VOLTAGE:
 		ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_4, 3, 0);
 		break;
 	case AS3711_SU2_CURR1:
 		ctl = 1;
 		ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_4, 3, 1);
 		break;
 	case AS3711_SU2_CURR2:
 		ctl = 4;
 		ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_4, 3, 2);
 		break;
 	case AS3711_SU2_CURR3:
 		ctl = 0x10;
 		ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_4, 3, 3);
 		break;
 	case AS3711_SU2_CURR_AUTO:
 		if (pdata->su2_auto_curr1)
 			ctl = 2;
 		if (pdata->su2_auto_curr2)
 			ctl |= 8;
 		if (pdata->su2_auto_curr3)
 			ctl |= 0x20;
 		ret = 0;
 		break;
 	default:
 		return -EINVAL;
 	}

 	if (!ret)
 		ret = regmap_write(as3711->regmap, AS3711_CURR_CONTROL, ctl);

 	return ret;
 }

 static int as3711_bl_register(struct platform_device *pdev,
 			      unsigned int max_brightness, struct as3711_bl_data *su)
 {
 	struct backlight_properties props = {.type = BACKLIGHT_RAW,};
 	struct backlight_device *bl;

 	/* max tuning I = 31uA for voltage- and 38250uA for current-feedback */
 	props.max_brightness = max_brightness;

 	bl = devm_backlight_device_register(&pdev->dev,
 				       su->type == AS3711_BL_SU1 ?
 				       "as3711-su1" : "as3711-su2",
 				       &pdev->dev, su,
 				       &as3711_bl_ops, &props);
 	if (IS_ERR(bl)) {
 		dev_err(&pdev->dev, "failed to register backlight\n");
 		return PTR_ERR(bl);
 	}

 	bl->props.brightness = props.max_brightness;

 	backlight_update_status(bl);

 	su->bl = bl;

 	return 0;
 }

 static int as3711_backlight_parse_dt(struct device *dev)
 {
 	struct as3711_bl_pdata *pdata = dev_get_platdata(dev);
 	struct device_node *bl, *fb;
 	int ret;

 	bl = of_get_child_by_name(dev->parent->of_node, "backlight");
 	if (!bl) {
 		dev_dbg(dev, "backlight node not found\n");
 		return -ENODEV;
 	}

 	fb = of_parse_phandle(bl, "su1-dev", 0);
 	if (fb) {
 		of_node_put(fb);

 		pdata->su1_fb = true;

 		ret = of_property_read_u32(bl, "su1-max-uA", &pdata->su1_max_uA);
 		if (pdata->su1_max_uA <= 0)
 			ret = -EINVAL;
 		if (ret < 0)
 			goto err_put_bl;
 	}

 	fb = of_parse_phandle(bl, "su2-dev", 0);
 	if (fb) {
 		int count = 0;

 		of_node_put(fb);

 		pdata->su2_fb = true;

 		ret = of_property_read_u32(bl, "su2-max-uA", &pdata->su2_max_uA);
 		if (pdata->su2_max_uA <= 0)
 			ret = -EINVAL;
 		if (ret < 0)
 			goto err_put_bl;

 		if (of_find_property(bl, "su2-feedback-voltage", NULL)) {
 			pdata->su2_feedback = AS3711_SU2_VOLTAGE;
 			count++;
 		}
 		if (of_find_property(bl, "su2-feedback-curr1", NULL)) {
 			pdata->su2_feedback = AS3711_SU2_CURR1;
 			count++;
 		}
 		if (of_find_property(bl, "su2-feedback-curr2", NULL)) {
 			pdata->su2_feedback = AS3711_SU2_CURR2;
 			count++;
 		}
 		if (of_find_property(bl, "su2-feedback-curr3", NULL)) {
 			pdata->su2_feedback = AS3711_SU2_CURR3;
 			count++;
 		}
 		if (of_find_property(bl, "su2-feedback-curr-auto", NULL)) {
 			pdata->su2_feedback = AS3711_SU2_CURR_AUTO;
 			count++;
 		}
 		if (count != 1) {
 			ret = -EINVAL;
 			goto err_put_bl;
 		}

 		count = 0;
 		if (of_find_property(bl, "su2-fbprot-lx-sd4", NULL)) {
 			pdata->su2_fbprot = AS3711_SU2_LX_SD4;
 			count++;
 		}
 		if (of_find_property(bl, "su2-fbprot-gpio2", NULL)) {
 			pdata->su2_fbprot = AS3711_SU2_GPIO2;
 			count++;
 		}
 		if (of_find_property(bl, "su2-fbprot-gpio3", NULL)) {
 			pdata->su2_fbprot = AS3711_SU2_GPIO3;
 			count++;
 		}
 		if (of_find_property(bl, "su2-fbprot-gpio4", NULL)) {
 			pdata->su2_fbprot = AS3711_SU2_GPIO4;
 			count++;
 		}
 		if (count != 1) {
 			ret = -EINVAL;
 			goto err_put_bl;
 		}

 		count = 0;
 		if (of_find_property(bl, "su2-auto-curr1", NULL)) {
 			pdata->su2_auto_curr1 = true;
 			count++;
 		}
 		if (of_find_property(bl, "su2-auto-curr2", NULL)) {
 			pdata->su2_auto_curr2 = true;
 			count++;
 		}
 		if (of_find_property(bl, "su2-auto-curr3", NULL)) {
 			pdata->su2_auto_curr3 = true;
 			count++;
 		}

 		/*
 		 * At least one su2-auto-curr* must be specified iff
 		 * AS3711_SU2_CURR_AUTO is used
 		 */
 		if (!count ^ (pdata->su2_feedback != AS3711_SU2_CURR_AUTO)) {
 			ret = -EINVAL;
 			goto err_put_bl;
 		}
 	}

 	of_node_put(bl);

 	return 0;

 err_put_bl:
 	of_node_put(bl);

 	return ret;
 }

 static int as3711_backlight_probe(struct platform_device *pdev)
 {
 	struct as3711_bl_pdata *pdata = dev_get_platdata(&pdev->dev);
 	struct as3711 *as3711 = dev_get_drvdata(pdev->dev.parent);
 	struct as3711_bl_supply *supply;
 	struct as3711_bl_data *su;
 	unsigned int max_brightness;
 	int ret;

 	if (!pdata) {
 		dev_err(&pdev->dev, "No platform data, exiting...\n");
 		return -ENODEV;
 	}

 	if (pdev->dev.parent->of_node) {
 		ret = as3711_backlight_parse_dt(&pdev->dev);
 		if (ret < 0) {
 			dev_err(&pdev->dev, "DT parsing failed: %d\n", ret);
 			return ret;
 		}
 	}

 	if (!pdata->su1_fb && !pdata->su2_fb) {
 		dev_err(&pdev->dev, "No framebuffer specified\n");
 		return -EINVAL;
 	}

 	/*
 	 * Due to possible hardware damage I chose to block all modes,
 	 * unsupported on my hardware. Anyone, wishing to use any of those modes
 	 * will have to first review the code, then activate and test it.
 	 */
 	if (pdata->su1_fb ||
 	    pdata->su2_fbprot != AS3711_SU2_GPIO4 ||
 	    pdata->su2_feedback != AS3711_SU2_CURR_AUTO) {
 		dev_warn(&pdev->dev,
 			 "Attention! An untested mode has been chosen!\n"
 			 "Please, review the code, enable, test, and report success:-)\n");
 		return -EINVAL;
 	}

 	supply = devm_kzalloc(&pdev->dev, sizeof(*supply), GFP_KERNEL);
 	if (!supply)
 		return -ENOMEM;

 	supply->as3711 = as3711;
 	supply->pdata = pdata;

 	if (pdata->su1_fb) {
 		su = &supply->su1;
 		su->type = AS3711_BL_SU1;

 		max_brightness = min(pdata->su1_max_uA, 31);
 		ret = as3711_bl_register(pdev, max_brightness, su);
 		if (ret < 0)
 			return ret;
 	}

 	if (pdata->su2_fb) {
 		su = &supply->su2;
 		su->type = AS3711_BL_SU2;

 		switch (pdata->su2_fbprot) {
 		case AS3711_SU2_GPIO2:
 		case AS3711_SU2_GPIO3:
 		case AS3711_SU2_GPIO4:
 		case AS3711_SU2_LX_SD4:
 			break;
 		default:
 			return -EINVAL;
 		}

 		switch (pdata->su2_feedback) {
 		case AS3711_SU2_VOLTAGE:
 			max_brightness = min(pdata->su2_max_uA, 31);
 			break;
 		case AS3711_SU2_CURR1:
 		case AS3711_SU2_CURR2:
 		case AS3711_SU2_CURR3:
 		case AS3711_SU2_CURR_AUTO:
 			max_brightness = min(pdata->su2_max_uA / 150, 255);
 			break;
 		default:
 			return -EINVAL;
 		}

 		ret = as3711_bl_init_su2(supply);
 		if (ret < 0)
 			return ret;

 		ret = as3711_bl_register(pdev, max_brightness, su);
 		if (ret < 0)
 			return ret;
 	}

 	platform_set_drvdata(pdev, supply);

 	return 0;
 }

 static struct platform_driver as3711_backlight_driver = {
 	.driver		= {
 		.name	= "as3711-backlight",
 	},
 	.probe		= as3711_backlight_probe,
 };

 module_platform_driver(as3711_backlight_driver);

 MODULE_DESCRIPTION("Backlight Driver for AS3711 PMICs");
 MODULE_AUTHOR("Guennadi Liakhovetski <g.liakhovetski@gmx.de");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("platform:as3711-backlight");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* AS3711 PMIC backlight driver, using DCDC Step Up Converters
	*
	* Copyright (C) 2012 Renesas Electronics Corporation
	* Author: Guennadi Liakhovetski, <g.liakhovetski@gmx.de>
	*/

	#include <linux/backlight.h>
	#include <linux/delay.h>
	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/fb.h>
	#include <linux/kernel.h>
	#include <linux/mfd/as3711.h>
	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/regmap.h>
	#include <linux/slab.h>

	enum as3711_bl_type {
	AS3711_BL_SU1,
	AS3711_BL_SU2,
	};

	struct as3711_bl_data {
	bool powered;
	enum as3711_bl_type type;
	int brightness;
	struct backlight_device *bl;
	};

	struct as3711_bl_supply {
	struct as3711_bl_data su1;
	struct as3711_bl_data su2;
	const struct as3711_bl_pdata *pdata;
	struct as3711 *as3711;
	};

	static struct as3711_bl_supply to_supply(struct as3711_bl_data su)
	{
	switch (su->type) {
	case AS3711_BL_SU1:
	return container_of(su, struct as3711_bl_supply, su1);
	case AS3711_BL_SU2:
	return container_of(su, struct as3711_bl_supply, su2);
	}
	return NULL;
	}

	static int as3711_set_brightness_auto_i(struct as3711_bl_data *data,
	unsigned int brightness)
	{
	struct as3711_bl_supply *supply = to_supply(data);
	struct as3711 *as3711 = supply->as3711;
	const struct as3711_bl_pdata *pdata = supply->pdata;
	int ret = 0;

	/* Only all equal current values are supported */
	if (pdata->su2_auto_curr1)
	ret = regmap_write(as3711->regmap, AS3711_CURR1_VALUE,
	brightness);
	if (!ret && pdata->su2_auto_curr2)
	ret = regmap_write(as3711->regmap, AS3711_CURR2_VALUE,
	brightness);
	if (!ret && pdata->su2_auto_curr3)
	ret = regmap_write(as3711->regmap, AS3711_CURR3_VALUE,
	brightness);

	return ret;
	}

	static int as3711_set_brightness_v(struct as3711 *as3711,
	unsigned int brightness,
	unsigned int reg)
	{
	if (brightness > 31)
	return -EINVAL;

	return regmap_update_bits(as3711->regmap, reg, 0xf0,
	brightness << 4);
	}

	static int as3711_bl_su2_reset(struct as3711_bl_supply *supply)
	{
	struct as3711 *as3711 = supply->as3711;
	int ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_5,
	3, supply->pdata->su2_fbprot);
	if (!ret)
	ret = regmap_update_bits(as3711->regmap,
	AS3711_STEPUP_CONTROL_2, 1, 0);
	if (!ret)
	ret = regmap_update_bits(as3711->regmap,
	AS3711_STEPUP_CONTROL_2, 1, 1);
	return ret;
	}

	/*
	* Someone with less fragile or less expensive hardware could try to simplify
	* the brightness adjustment procedure.
	*/
	static int as3711_bl_update_status(struct backlight_device *bl)
	{
	struct as3711_bl_data *data = bl_get_data(bl);
	struct as3711_bl_supply *supply = to_supply(data);
	struct as3711 *as3711 = supply->as3711;
	int brightness;
	int ret = 0;

	brightness = backlight_get_brightness(bl);

	if (data->type == AS3711_BL_SU1) {
	ret = as3711_set_brightness_v(as3711, brightness,
	AS3711_STEPUP_CONTROL_1);
	} else {
	const struct as3711_bl_pdata *pdata = supply->pdata;

	switch (pdata->su2_feedback) {
	case AS3711_SU2_VOLTAGE:
	ret = as3711_set_brightness_v(as3711, brightness,
	AS3711_STEPUP_CONTROL_2);
	break;
	case AS3711_SU2_CURR_AUTO:
	ret = as3711_set_brightness_auto_i(data, brightness / 4);
	if (ret < 0)
	return ret;
	if (brightness) {
	ret = as3711_bl_su2_reset(supply);
	if (ret < 0)
	return ret;
	udelay(500);
	ret = as3711_set_brightness_auto_i(data, brightness);
	} else {
	ret = regmap_update_bits(as3711->regmap,
	AS3711_STEPUP_CONTROL_2, 1, 0);
	}
	break;
	/* Manual one current feedback pin below */
	case AS3711_SU2_CURR1:
	ret = regmap_write(as3711->regmap, AS3711_CURR1_VALUE,
	brightness);
	break;
	case AS3711_SU2_CURR2:
	ret = regmap_write(as3711->regmap, AS3711_CURR2_VALUE,
	brightness);
	break;
	case AS3711_SU2_CURR3:
	ret = regmap_write(as3711->regmap, AS3711_CURR3_VALUE,
	brightness);
	break;
	default:
	ret = -EINVAL;
	}
	}
	if (!ret)
	data->brightness = brightness;

	return ret;
	}

	static int as3711_bl_get_brightness(struct backlight_device *bl)
	{
	struct as3711_bl_data *data = bl_get_data(bl);

	return data->brightness;
	}

	static const struct backlight_ops as3711_bl_ops = {
	.update_status = as3711_bl_update_status,
	.get_brightness = as3711_bl_get_brightness,
	};

	static int as3711_bl_init_su2(struct as3711_bl_supply *supply)
	{
	struct as3711 *as3711 = supply->as3711;
	const struct as3711_bl_pdata *pdata = supply->pdata;
	u8 ctl = 0;
	int ret;

	dev_dbg(as3711->dev, "%s(): use %u\n", __func__, pdata->su2_feedback);

	/* Turn SU2 off */
	ret = regmap_write(as3711->regmap, AS3711_STEPUP_CONTROL_2, 0);
	if (ret < 0)
	return ret;

	switch (pdata->su2_feedback) {
	case AS3711_SU2_VOLTAGE:
	ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_4, 3, 0);
	break;
	case AS3711_SU2_CURR1:
	ctl = 1;
	ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_4, 3, 1);
	break;
	case AS3711_SU2_CURR2:
	ctl = 4;
	ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_4, 3, 2);
	break;
	case AS3711_SU2_CURR3:
	ctl = 0x10;
	ret = regmap_update_bits(as3711->regmap, AS3711_STEPUP_CONTROL_4, 3, 3);
	break;
	case AS3711_SU2_CURR_AUTO:
	if (pdata->su2_auto_curr1)
	ctl = 2;
	if (pdata->su2_auto_curr2)
	ctl \|= 8;
	if (pdata->su2_auto_curr3)
	ctl \|= 0x20;
	ret = 0;
	break;
	default:
	return -EINVAL;
	}

	if (!ret)
	ret = regmap_write(as3711->regmap, AS3711_CURR_CONTROL, ctl);

	return ret;
	}

	static int as3711_bl_register(struct platform_device *pdev,
	unsigned int max_brightness, struct as3711_bl_data *su)
	{
	struct backlight_properties props = {.type = BACKLIGHT_RAW,};
	struct backlight_device *bl;

	/* max tuning I = 31uA for voltage- and 38250uA for current-feedback */
	props.max_brightness = max_brightness;

	bl = devm_backlight_device_register(&pdev->dev,
	su->type == AS3711_BL_SU1 ?
	"as3711-su1" : "as3711-su2",
	&pdev->dev, su,
	&as3711_bl_ops, &props);
	if (IS_ERR(bl)) {
	dev_err(&pdev->dev, "failed to register backlight\n");
	return PTR_ERR(bl);
	}

	bl->props.brightness = props.max_brightness;

	backlight_update_status(bl);

	su->bl = bl;

	return 0;
	}

	static int as3711_backlight_parse_dt(struct device *dev)
	{
	struct as3711_bl_pdata *pdata = dev_get_platdata(dev);
	struct device_node bl, fb;
	int ret;

	bl = of_get_child_by_name(dev->parent->of_node, "backlight");
	if (!bl) {
	dev_dbg(dev, "backlight node not found\n");
	return -ENODEV;
	}

	fb = of_parse_phandle(bl, "su1-dev", 0);
	if (fb) {
	of_node_put(fb);

	pdata->su1_fb = true;

	ret = of_property_read_u32(bl, "su1-max-uA", &pdata->su1_max_uA);
	if (pdata->su1_max_uA <= 0)
	ret = -EINVAL;
	if (ret < 0)
	goto err_put_bl;
	}

	fb = of_parse_phandle(bl, "su2-dev", 0);
	if (fb) {
	int count = 0;

	of_node_put(fb);

	pdata->su2_fb = true;

	ret = of_property_read_u32(bl, "su2-max-uA", &pdata->su2_max_uA);
	if (pdata->su2_max_uA <= 0)
	ret = -EINVAL;
	if (ret < 0)
	goto err_put_bl;

	if (of_find_property(bl, "su2-feedback-voltage", NULL)) {
	pdata->su2_feedback = AS3711_SU2_VOLTAGE;
	count++;
	}
	if (of_find_property(bl, "su2-feedback-curr1", NULL)) {
	pdata->su2_feedback = AS3711_SU2_CURR1;
	count++;
	}
	if (of_find_property(bl, "su2-feedback-curr2", NULL)) {
	pdata->su2_feedback = AS3711_SU2_CURR2;
	count++;
	}
	if (of_find_property(bl, "su2-feedback-curr3", NULL)) {
	pdata->su2_feedback = AS3711_SU2_CURR3;
	count++;
	}
	if (of_find_property(bl, "su2-feedback-curr-auto", NULL)) {
	pdata->su2_feedback = AS3711_SU2_CURR_AUTO;
	count++;
	}
	if (count != 1) {
	ret = -EINVAL;
	goto err_put_bl;
	}

	count = 0;
	if (of_find_property(bl, "su2-fbprot-lx-sd4", NULL)) {
	pdata->su2_fbprot = AS3711_SU2_LX_SD4;
	count++;
	}
	if (of_find_property(bl, "su2-fbprot-gpio2", NULL)) {
	pdata->su2_fbprot = AS3711_SU2_GPIO2;
	count++;
	}
	if (of_find_property(bl, "su2-fbprot-gpio3", NULL)) {
	pdata->su2_fbprot = AS3711_SU2_GPIO3;
	count++;
	}
	if (of_find_property(bl, "su2-fbprot-gpio4", NULL)) {
	pdata->su2_fbprot = AS3711_SU2_GPIO4;
	count++;
	}
	if (count != 1) {
	ret = -EINVAL;
	goto err_put_bl;
	}

	count = 0;
	if (of_find_property(bl, "su2-auto-curr1", NULL)) {
	pdata->su2_auto_curr1 = true;
	count++;
	}
	if (of_find_property(bl, "su2-auto-curr2", NULL)) {
	pdata->su2_auto_curr2 = true;
	count++;
	}
	if (of_find_property(bl, "su2-auto-curr3", NULL)) {
	pdata->su2_auto_curr3 = true;
	count++;
	}

	/*
	* At least one su2-auto-curr* must be specified iff
	* AS3711_SU2_CURR_AUTO is used
	*/
	if (!count ^ (pdata->su2_feedback != AS3711_SU2_CURR_AUTO)) {
	ret = -EINVAL;
	goto err_put_bl;
	}
	}

	of_node_put(bl);

	return 0;

	err_put_bl:
	of_node_put(bl);

	return ret;
	}

	static int as3711_backlight_probe(struct platform_device *pdev)
	{
	struct as3711_bl_pdata *pdata = dev_get_platdata(&pdev->dev);
	struct as3711 *as3711 = dev_get_drvdata(pdev->dev.parent);
	struct as3711_bl_supply *supply;
	struct as3711_bl_data *su;
	unsigned int max_brightness;
	int ret;

	if (!pdata) {
	dev_err(&pdev->dev, "No platform data, exiting...\n");
	return -ENODEV;
	}

	if (pdev->dev.parent->of_node) {
	ret = as3711_backlight_parse_dt(&pdev->dev);
	if (ret < 0) {
	dev_err(&pdev->dev, "DT parsing failed: %d\n", ret);
	return ret;
	}
	}

	if (!pdata->su1_fb && !pdata->su2_fb) {
	dev_err(&pdev->dev, "No framebuffer specified\n");
	return -EINVAL;
	}

	/*
	* Due to possible hardware damage I chose to block all modes,
	* unsupported on my hardware. Anyone, wishing to use any of those modes
	* will have to first review the code, then activate and test it.
	*/
	if (pdata->su1_fb \|\|
	pdata->su2_fbprot != AS3711_SU2_GPIO4 \|\|
	pdata->su2_feedback != AS3711_SU2_CURR_AUTO) {
	dev_warn(&pdev->dev,
	"Attention! An untested mode has been chosen!\n"
	"Please, review the code, enable, test, and report success:-)\n");
	return -EINVAL;
	}

	supply = devm_kzalloc(&pdev->dev, sizeof(*supply), GFP_KERNEL);
	if (!supply)
	return -ENOMEM;

	supply->as3711 = as3711;
	supply->pdata = pdata;

	if (pdata->su1_fb) {
	su = &supply->su1;
	su->type = AS3711_BL_SU1;

	max_brightness = min(pdata->su1_max_uA, 31);
	ret = as3711_bl_register(pdev, max_brightness, su);
	if (ret < 0)
	return ret;
	}

	if (pdata->su2_fb) {
	su = &supply->su2;
	su->type = AS3711_BL_SU2;

	switch (pdata->su2_fbprot) {
	case AS3711_SU2_GPIO2:
	case AS3711_SU2_GPIO3:
	case AS3711_SU2_GPIO4:
	case AS3711_SU2_LX_SD4:
	break;
	default:
	return -EINVAL;
	}

	switch (pdata->su2_feedback) {
	case AS3711_SU2_VOLTAGE:
	max_brightness = min(pdata->su2_max_uA, 31);
	break;
	case AS3711_SU2_CURR1:
	case AS3711_SU2_CURR2:
	case AS3711_SU2_CURR3:
	case AS3711_SU2_CURR_AUTO:
	max_brightness = min(pdata->su2_max_uA / 150, 255);
	break;
	default:
	return -EINVAL;
	}

	ret = as3711_bl_init_su2(supply);
	if (ret < 0)
	return ret;

	ret = as3711_bl_register(pdev, max_brightness, su);
	if (ret < 0)
	return ret;
	}

	platform_set_drvdata(pdev, supply);

	return 0;
	}

	static struct platform_driver as3711_backlight_driver = {
	.driver = {
	.name = "as3711-backlight",
	},
	.probe = as3711_backlight_probe,
	};

	module_platform_driver(as3711_backlight_driver);

	MODULE_DESCRIPTION("Backlight Driver for AS3711 PMICs");
	MODULE_AUTHOR("Guennadi Liakhovetski <g.liakhovetski@gmx.de");
	MODULE_LICENSE("GPL v2");
	MODULE_ALIAS("platform:as3711-backlight");