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

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
  *
  * Copyright 2016 ArcticSand, Inc.
  * Author : Brian Dodge <bdodge@arcticsand.com>
  */

 #include <linux/backlight.h>
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/slab.h>

 enum arcxcnn_chip_id {
 	ARC2C0608
 };

 /**
  * struct arcxcnn_platform_data
  * @name		: Backlight driver name (NULL will use default)
  * @initial_brightness	: initial value of backlight brightness
  * @leden		: initial LED string enables, upper bit is global on/off
  * @led_config_0	: fading speed (period between intensity steps)
  * @led_config_1	: misc settings, see datasheet
  * @dim_freq		: pwm dimming frequency if in pwm mode
  * @comp_config		: misc config, see datasheet
  * @filter_config	: RC/PWM filter config, see datasheet
  * @trim_config		: full scale current trim, see datasheet
  */
 struct arcxcnn_platform_data {
 	const char *name;
 	u16 initial_brightness;
 	u8	leden;
 	u8	led_config_0;
 	u8	led_config_1;
 	u8	dim_freq;
 	u8	comp_config;
 	u8	filter_config;
 	u8	trim_config;
 };

 #define ARCXCNN_CMD		0x00	/* Command Register */
 #define ARCXCNN_CMD_STDBY	0x80	/*   I2C Standby */
 #define ARCXCNN_CMD_RESET	0x40	/*   Reset */
 #define ARCXCNN_CMD_BOOST	0x10	/*   Boost */
 #define ARCXCNN_CMD_OVP_MASK	0x0C	/*   --- Over Voltage Threshold */
 #define ARCXCNN_CMD_OVP_XXV	0x0C	/*   <rsvrd> Over Voltage Threshold */
 #define ARCXCNN_CMD_OVP_20V	0x08	/*   20v Over Voltage Threshold */
 #define ARCXCNN_CMD_OVP_24V	0x04	/*   24v Over Voltage Threshold */
 #define ARCXCNN_CMD_OVP_31V	0x00	/*   31.4v Over Voltage Threshold */
 #define ARCXCNN_CMD_EXT_COMP	0x01	/*   part (0) or full (1) ext. comp */

 #define ARCXCNN_CONFIG		0x01	/* Configuration */
 #define ARCXCNN_STATUS1		0x02	/* Status 1 */
 #define ARCXCNN_STATUS2		0x03	/* Status 2 */
 #define ARCXCNN_FADECTRL	0x04	/* Fading Control */
 #define ARCXCNN_ILED_CONFIG	0x05	/* ILED Configuration */
 #define ARCXCNN_ILED_DIM_PWM	0x00	/*   config dim mode pwm */
 #define ARCXCNN_ILED_DIM_INT	0x04	/*   config dim mode internal */
 #define ARCXCNN_LEDEN		0x06	/* LED Enable Register */
 #define ARCXCNN_LEDEN_ISETEXT	0x80	/*   Full-scale current set extern */
 #define ARCXCNN_LEDEN_MASK	0x3F	/*   LED string enables mask */
 #define ARCXCNN_LEDEN_BITS	0x06	/*   Bits of LED string enables */
 #define ARCXCNN_LEDEN_LED1	0x01
 #define ARCXCNN_LEDEN_LED2	0x02
 #define ARCXCNN_LEDEN_LED3	0x04
 #define ARCXCNN_LEDEN_LED4	0x08
 #define ARCXCNN_LEDEN_LED5	0x10
 #define ARCXCNN_LEDEN_LED6	0x20

 #define ARCXCNN_WLED_ISET_LSB	0x07	/* LED ISET LSB (in upper nibble) */
 #define ARCXCNN_WLED_ISET_LSB_SHIFT 0x04  /* ISET LSB Left Shift */
 #define ARCXCNN_WLED_ISET_MSB	0x08	/* LED ISET MSB (8 bits) */

 #define ARCXCNN_DIMFREQ		0x09
 #define ARCXCNN_COMP_CONFIG	0x0A
 #define ARCXCNN_FILT_CONFIG	0x0B
 #define ARCXCNN_IMAXTUNE	0x0C
 #define ARCXCNN_ID_MSB		0x1E
 #define ARCXCNN_ID_LSB		0x1F

 #define MAX_BRIGHTNESS		4095
 #define INIT_BRIGHT		60

 struct arcxcnn {
 	struct i2c_client *client;
 	struct backlight_device *bl;
 	struct device *dev;
 	struct arcxcnn_platform_data *pdata;
 };

 static int arcxcnn_update_field(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
 {
 	int ret;
 	u8 tmp;

 	ret = i2c_smbus_read_byte_data(lp->client, reg);
 	if (ret < 0) {
 		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
 		return ret;
 	}

 	tmp = (u8)ret;
 	tmp &= ~mask;
 	tmp |= data & mask;

 	return i2c_smbus_write_byte_data(lp->client, reg, tmp);
 }

 static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
 {
 	int ret;
 	u8 val;

 	/* lower nibble of brightness goes in upper nibble of LSB register */
 	val = (brightness & 0xF) << ARCXCNN_WLED_ISET_LSB_SHIFT;
 	ret = i2c_smbus_write_byte_data(lp->client,
 		ARCXCNN_WLED_ISET_LSB, val);
 	if (ret < 0)
 		return ret;

 	/* remaining 8 bits of brightness go in MSB register */
 	val = (brightness >> 4);
 	return i2c_smbus_write_byte_data(lp->client,
 		ARCXCNN_WLED_ISET_MSB, val);
 }

 static int arcxcnn_bl_update_status(struct backlight_device *bl)
 {
 	struct arcxcnn *lp = bl_get_data(bl);
 	u32 brightness = backlight_get_brightness(bl);
 	int ret;

 	ret = arcxcnn_set_brightness(lp, brightness);
 	if (ret)
 		return ret;

 	/* set power-on/off/save modes */
 	return arcxcnn_update_field(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY,
 		(bl->props.power == 0) ? 0 : ARCXCNN_CMD_STDBY);
 }

 static const struct backlight_ops arcxcnn_bl_ops = {
 	.options = BL_CORE_SUSPENDRESUME,
 	.update_status = arcxcnn_bl_update_status,
 };

 static int arcxcnn_backlight_register(struct arcxcnn *lp)
 {
 	struct backlight_properties *props;
 	const char *name = lp->pdata->name ? : "arctic_bl";

 	props = devm_kzalloc(lp->dev, sizeof(*props), GFP_KERNEL);
 	if (!props)
 		return -ENOMEM;

 	props->type = BACKLIGHT_PLATFORM;
 	props->max_brightness = MAX_BRIGHTNESS;

 	if (lp->pdata->initial_brightness > props->max_brightness)
 		lp->pdata->initial_brightness = props->max_brightness;

 	props->brightness = lp->pdata->initial_brightness;

 	lp->bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
 				       &arcxcnn_bl_ops, props);
 	return PTR_ERR_OR_ZERO(lp->bl);
 }

 static void arcxcnn_parse_dt(struct arcxcnn *lp)
 {
 	struct device *dev = lp->dev;
 	struct device_node *node = dev->of_node;
 	u32 prog_val, num_entry, entry, sources[ARCXCNN_LEDEN_BITS];
 	int ret;

 	/* device tree entry isn't required, defaults are OK */
 	if (!node)
 		return;

 	ret = of_property_read_string(node, "label", &lp->pdata->name);
 	if (ret < 0)
 		lp->pdata->name = NULL;

 	ret = of_property_read_u32(node, "default-brightness", &prog_val);
 	if (ret == 0)
 		lp->pdata->initial_brightness = prog_val;

 	ret = of_property_read_u32(node, "arc,led-config-0", &prog_val);
 	if (ret == 0)
 		lp->pdata->led_config_0 = (u8)prog_val;

 	ret = of_property_read_u32(node, "arc,led-config-1", &prog_val);
 	if (ret == 0)
 		lp->pdata->led_config_1 = (u8)prog_val;

 	ret = of_property_read_u32(node, "arc,dim-freq", &prog_val);
 	if (ret == 0)
 		lp->pdata->dim_freq = (u8)prog_val;

 	ret = of_property_read_u32(node, "arc,comp-config", &prog_val);
 	if (ret == 0)
 		lp->pdata->comp_config = (u8)prog_val;

 	ret = of_property_read_u32(node, "arc,filter-config", &prog_val);
 	if (ret == 0)
 		lp->pdata->filter_config = (u8)prog_val;

 	ret = of_property_read_u32(node, "arc,trim-config", &prog_val);
 	if (ret == 0)
 		lp->pdata->trim_config = (u8)prog_val;

 	ret = of_property_count_u32_elems(node, "led-sources");
 	if (ret < 0) {
 		lp->pdata->leden = ARCXCNN_LEDEN_MASK; /* all on is default */
 	} else {
 		num_entry = ret;
 		if (num_entry > ARCXCNN_LEDEN_BITS)
 			num_entry = ARCXCNN_LEDEN_BITS;

 		ret = of_property_read_u32_array(node, "led-sources", sources,
 					num_entry);
 		if (ret < 0) {
 			dev_err(dev, "led-sources node is invalid.\n");
 			return;
 		}

 		lp->pdata->leden = 0;

 		/* for each enable in source, set bit in led enable */
 		for (entry = 0; entry < num_entry; entry++) {
 			u8 onbit = 1 << sources[entry];

 			lp->pdata->leden |= onbit;
 		}
 	}
 }

 static int arcxcnn_probe(struct i2c_client *cl)
 {
 	struct arcxcnn *lp;
 	int ret;

 	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 		return -EIO;

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

 	lp->client = cl;
 	lp->dev = &cl->dev;
 	lp->pdata = dev_get_platdata(&cl->dev);

 	/* reset the device */
 	ret = i2c_smbus_write_byte_data(lp->client,
 		ARCXCNN_CMD, ARCXCNN_CMD_RESET);
 	if (ret)
 		goto probe_err;

 	if (!lp->pdata) {
 		lp->pdata = devm_kzalloc(lp->dev,
 				sizeof(*lp->pdata), GFP_KERNEL);
 		if (!lp->pdata)
 			return -ENOMEM;

 		/* Setup defaults based on power-on defaults */
 		lp->pdata->name = NULL;
 		lp->pdata->initial_brightness = INIT_BRIGHT;
 		lp->pdata->leden = ARCXCNN_LEDEN_MASK;

 		lp->pdata->led_config_0 = i2c_smbus_read_byte_data(
 			lp->client, ARCXCNN_FADECTRL);

 		lp->pdata->led_config_1 = i2c_smbus_read_byte_data(
 			lp->client, ARCXCNN_ILED_CONFIG);
 		/* insure dim mode is not default pwm */
 		lp->pdata->led_config_1 |= ARCXCNN_ILED_DIM_INT;

 		lp->pdata->dim_freq = i2c_smbus_read_byte_data(
 			lp->client, ARCXCNN_DIMFREQ);

 		lp->pdata->comp_config = i2c_smbus_read_byte_data(
 			lp->client, ARCXCNN_COMP_CONFIG);

 		lp->pdata->filter_config = i2c_smbus_read_byte_data(
 			lp->client, ARCXCNN_FILT_CONFIG);

 		lp->pdata->trim_config = i2c_smbus_read_byte_data(
 			lp->client, ARCXCNN_IMAXTUNE);

 		if (IS_ENABLED(CONFIG_OF))
 			arcxcnn_parse_dt(lp);
 	}

 	i2c_set_clientdata(cl, lp);

 	/* constrain settings to what is possible */
 	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
 		lp->pdata->initial_brightness = MAX_BRIGHTNESS;

 	/* set initial brightness */
 	ret = arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
 	if (ret)
 		goto probe_err;

 	/* set other register values directly */
 	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_FADECTRL,
 		lp->pdata->led_config_0);
 	if (ret)
 		goto probe_err;

 	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_ILED_CONFIG,
 		lp->pdata->led_config_1);
 	if (ret)
 		goto probe_err;

 	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_DIMFREQ,
 		lp->pdata->dim_freq);
 	if (ret)
 		goto probe_err;

 	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_COMP_CONFIG,
 		lp->pdata->comp_config);
 	if (ret)
 		goto probe_err;

 	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_FILT_CONFIG,
 		lp->pdata->filter_config);
 	if (ret)
 		goto probe_err;

 	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_IMAXTUNE,
 		lp->pdata->trim_config);
 	if (ret)
 		goto probe_err;

 	/* set initial LED Enables */
 	arcxcnn_update_field(lp, ARCXCNN_LEDEN,
 		ARCXCNN_LEDEN_MASK, lp->pdata->leden);

 	ret = arcxcnn_backlight_register(lp);
 	if (ret)
 		goto probe_register_err;

 	backlight_update_status(lp->bl);

 	return 0;

 probe_register_err:
 	dev_err(lp->dev,
 		"failed to register backlight.\n");

 probe_err:
 	dev_err(lp->dev,
 		"failure ret: %d\n", ret);
 	return ret;
 }

 static void arcxcnn_remove(struct i2c_client *cl)
 {
 	struct arcxcnn *lp = i2c_get_clientdata(cl);

 	/* disable all strings (ignore errors) */
 	i2c_smbus_write_byte_data(lp->client,
 		ARCXCNN_LEDEN, 0x00);
 	/* reset the device (ignore errors) */
 	i2c_smbus_write_byte_data(lp->client,
 		ARCXCNN_CMD, ARCXCNN_CMD_RESET);

 	lp->bl->props.brightness = 0;

 	backlight_update_status(lp->bl);
 }

 static const struct of_device_id arcxcnn_dt_ids[] = {
 	{ .compatible = "arc,arc2c0608" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);

 static const struct i2c_device_id arcxcnn_ids[] = {
 	{"arc2c0608", ARC2C0608},
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);

 static struct i2c_driver arcxcnn_driver = {
 	.driver = {
 		.name = "arcxcnn_bl",
 		.of_match_table = of_match_ptr(arcxcnn_dt_ids),
 	},
 	.probe_new = arcxcnn_probe,
 	.remove = arcxcnn_remove,
 	.id_table = arcxcnn_ids,
 };
 module_i2c_driver(arcxcnn_driver);

 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Brian Dodge <bdodge@arcticsand.com>");
 MODULE_DESCRIPTION("ARCXCNN Backlight driver");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Backlight driver for ArcticSand ARC_X_C_0N_0N Devices
	*
	* Copyright 2016 ArcticSand, Inc.
	* Author : Brian Dodge <bdodge@arcticsand.com>
	*/

	#include <linux/backlight.h>
	#include <linux/err.h>
	#include <linux/i2c.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/slab.h>

	enum arcxcnn_chip_id {
	ARC2C0608
	};

	/**
	* struct arcxcnn_platform_data
	* @name : Backlight driver name (NULL will use default)
	* @initial_brightness : initial value of backlight brightness
	* @leden : initial LED string enables, upper bit is global on/off
	* @led_config_0 : fading speed (period between intensity steps)
	* @led_config_1 : misc settings, see datasheet
	* @dim_freq : pwm dimming frequency if in pwm mode
	* @comp_config : misc config, see datasheet
	* @filter_config : RC/PWM filter config, see datasheet
	* @trim_config : full scale current trim, see datasheet
	*/
	struct arcxcnn_platform_data {
	const char *name;
	u16 initial_brightness;
	u8 leden;
	u8 led_config_0;
	u8 led_config_1;
	u8 dim_freq;
	u8 comp_config;
	u8 filter_config;
	u8 trim_config;
	};

	#define ARCXCNN_CMD 0x00 /* Command Register */
	#define ARCXCNN_CMD_STDBY 0x80 /* I2C Standby */
	#define ARCXCNN_CMD_RESET 0x40 /* Reset */
	#define ARCXCNN_CMD_BOOST 0x10 /* Boost */
	#define ARCXCNN_CMD_OVP_MASK 0x0C /* --- Over Voltage Threshold */
	#define ARCXCNN_CMD_OVP_XXV 0x0C /* <rsvrd> Over Voltage Threshold */
	#define ARCXCNN_CMD_OVP_20V 0x08 /* 20v Over Voltage Threshold */
	#define ARCXCNN_CMD_OVP_24V 0x04 /* 24v Over Voltage Threshold */
	#define ARCXCNN_CMD_OVP_31V 0x00 /* 31.4v Over Voltage Threshold */
	#define ARCXCNN_CMD_EXT_COMP 0x01 /* part (0) or full (1) ext. comp */

	#define ARCXCNN_CONFIG 0x01 /* Configuration */
	#define ARCXCNN_STATUS1 0x02 /* Status 1 */
	#define ARCXCNN_STATUS2 0x03 /* Status 2 */
	#define ARCXCNN_FADECTRL 0x04 /* Fading Control */
	#define ARCXCNN_ILED_CONFIG 0x05 /* ILED Configuration */
	#define ARCXCNN_ILED_DIM_PWM 0x00 /* config dim mode pwm */
	#define ARCXCNN_ILED_DIM_INT 0x04 /* config dim mode internal */
	#define ARCXCNN_LEDEN 0x06 /* LED Enable Register */
	#define ARCXCNN_LEDEN_ISETEXT 0x80 /* Full-scale current set extern */
	#define ARCXCNN_LEDEN_MASK 0x3F /* LED string enables mask */
	#define ARCXCNN_LEDEN_BITS 0x06 /* Bits of LED string enables */
	#define ARCXCNN_LEDEN_LED1 0x01
	#define ARCXCNN_LEDEN_LED2 0x02
	#define ARCXCNN_LEDEN_LED3 0x04
	#define ARCXCNN_LEDEN_LED4 0x08
	#define ARCXCNN_LEDEN_LED5 0x10
	#define ARCXCNN_LEDEN_LED6 0x20

	#define ARCXCNN_WLED_ISET_LSB 0x07 /* LED ISET LSB (in upper nibble) */
	#define ARCXCNN_WLED_ISET_LSB_SHIFT 0x04 /* ISET LSB Left Shift */
	#define ARCXCNN_WLED_ISET_MSB 0x08 /* LED ISET MSB (8 bits) */

	#define ARCXCNN_DIMFREQ 0x09
	#define ARCXCNN_COMP_CONFIG 0x0A
	#define ARCXCNN_FILT_CONFIG 0x0B
	#define ARCXCNN_IMAXTUNE 0x0C
	#define ARCXCNN_ID_MSB 0x1E
	#define ARCXCNN_ID_LSB 0x1F

	#define MAX_BRIGHTNESS 4095
	#define INIT_BRIGHT 60

	struct arcxcnn {
	struct i2c_client *client;
	struct backlight_device *bl;
	struct device *dev;
	struct arcxcnn_platform_data *pdata;
	};

	static int arcxcnn_update_field(struct arcxcnn *lp, u8 reg, u8 mask, u8 data)
	{
	int ret;
	u8 tmp;

	ret = i2c_smbus_read_byte_data(lp->client, reg);
	if (ret < 0) {
	dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
	return ret;
	}

	tmp = (u8)ret;
	tmp &= ~mask;
	tmp \|= data & mask;

	return i2c_smbus_write_byte_data(lp->client, reg, tmp);
	}

	static int arcxcnn_set_brightness(struct arcxcnn *lp, u32 brightness)
	{
	int ret;
	u8 val;

	/* lower nibble of brightness goes in upper nibble of LSB register */
	val = (brightness & 0xF) << ARCXCNN_WLED_ISET_LSB_SHIFT;
	ret = i2c_smbus_write_byte_data(lp->client,
	ARCXCNN_WLED_ISET_LSB, val);
	if (ret < 0)
	return ret;

	/* remaining 8 bits of brightness go in MSB register */
	val = (brightness >> 4);
	return i2c_smbus_write_byte_data(lp->client,
	ARCXCNN_WLED_ISET_MSB, val);
	}

	static int arcxcnn_bl_update_status(struct backlight_device *bl)
	{
	struct arcxcnn *lp = bl_get_data(bl);
	u32 brightness = backlight_get_brightness(bl);
	int ret;

	ret = arcxcnn_set_brightness(lp, brightness);
	if (ret)
	return ret;

	/* set power-on/off/save modes */
	return arcxcnn_update_field(lp, ARCXCNN_CMD, ARCXCNN_CMD_STDBY,
	(bl->props.power == 0) ? 0 : ARCXCNN_CMD_STDBY);
	}

	static const struct backlight_ops arcxcnn_bl_ops = {
	.options = BL_CORE_SUSPENDRESUME,
	.update_status = arcxcnn_bl_update_status,
	};

	static int arcxcnn_backlight_register(struct arcxcnn *lp)
	{
	struct backlight_properties *props;
	const char *name = lp->pdata->name ? : "arctic_bl";

	props = devm_kzalloc(lp->dev, sizeof(*props), GFP_KERNEL);
	if (!props)
	return -ENOMEM;

	props->type = BACKLIGHT_PLATFORM;
	props->max_brightness = MAX_BRIGHTNESS;

	if (lp->pdata->initial_brightness > props->max_brightness)
	lp->pdata->initial_brightness = props->max_brightness;

	props->brightness = lp->pdata->initial_brightness;

	lp->bl = devm_backlight_device_register(lp->dev, name, lp->dev, lp,
	&arcxcnn_bl_ops, props);
	return PTR_ERR_OR_ZERO(lp->bl);
	}

	static void arcxcnn_parse_dt(struct arcxcnn *lp)
	{
	struct device *dev = lp->dev;
	struct device_node *node = dev->of_node;
	u32 prog_val, num_entry, entry, sources[ARCXCNN_LEDEN_BITS];
	int ret;

	/* device tree entry isn't required, defaults are OK */
	if (!node)
	return;

	ret = of_property_read_string(node, "label", &lp->pdata->name);
	if (ret < 0)
	lp->pdata->name = NULL;

	ret = of_property_read_u32(node, "default-brightness", &prog_val);
	if (ret == 0)
	lp->pdata->initial_brightness = prog_val;

	ret = of_property_read_u32(node, "arc,led-config-0", &prog_val);
	if (ret == 0)
	lp->pdata->led_config_0 = (u8)prog_val;

	ret = of_property_read_u32(node, "arc,led-config-1", &prog_val);
	if (ret == 0)
	lp->pdata->led_config_1 = (u8)prog_val;

	ret = of_property_read_u32(node, "arc,dim-freq", &prog_val);
	if (ret == 0)
	lp->pdata->dim_freq = (u8)prog_val;

	ret = of_property_read_u32(node, "arc,comp-config", &prog_val);
	if (ret == 0)
	lp->pdata->comp_config = (u8)prog_val;

	ret = of_property_read_u32(node, "arc,filter-config", &prog_val);
	if (ret == 0)
	lp->pdata->filter_config = (u8)prog_val;

	ret = of_property_read_u32(node, "arc,trim-config", &prog_val);
	if (ret == 0)
	lp->pdata->trim_config = (u8)prog_val;

	ret = of_property_count_u32_elems(node, "led-sources");
	if (ret < 0) {
	lp->pdata->leden = ARCXCNN_LEDEN_MASK; /* all on is default */
	} else {
	num_entry = ret;
	if (num_entry > ARCXCNN_LEDEN_BITS)
	num_entry = ARCXCNN_LEDEN_BITS;

	ret = of_property_read_u32_array(node, "led-sources", sources,
	num_entry);
	if (ret < 0) {
	dev_err(dev, "led-sources node is invalid.\n");
	return;
	}

	lp->pdata->leden = 0;

	/* for each enable in source, set bit in led enable */
	for (entry = 0; entry < num_entry; entry++) {
	u8 onbit = 1 << sources[entry];

	lp->pdata->leden \|= onbit;
	}
	}
	}

	static int arcxcnn_probe(struct i2c_client *cl)
	{
	struct arcxcnn *lp;
	int ret;

	if (!i2c_check_functionality(cl->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
	return -EIO;

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

	lp->client = cl;
	lp->dev = &cl->dev;
	lp->pdata = dev_get_platdata(&cl->dev);

	/* reset the device */
	ret = i2c_smbus_write_byte_data(lp->client,
	ARCXCNN_CMD, ARCXCNN_CMD_RESET);
	if (ret)
	goto probe_err;

	if (!lp->pdata) {
	lp->pdata = devm_kzalloc(lp->dev,
	sizeof(*lp->pdata), GFP_KERNEL);
	if (!lp->pdata)
	return -ENOMEM;

	/* Setup defaults based on power-on defaults */
	lp->pdata->name = NULL;
	lp->pdata->initial_brightness = INIT_BRIGHT;
	lp->pdata->leden = ARCXCNN_LEDEN_MASK;

	lp->pdata->led_config_0 = i2c_smbus_read_byte_data(
	lp->client, ARCXCNN_FADECTRL);

	lp->pdata->led_config_1 = i2c_smbus_read_byte_data(
	lp->client, ARCXCNN_ILED_CONFIG);
	/* insure dim mode is not default pwm */
	lp->pdata->led_config_1 \|= ARCXCNN_ILED_DIM_INT;

	lp->pdata->dim_freq = i2c_smbus_read_byte_data(
	lp->client, ARCXCNN_DIMFREQ);

	lp->pdata->comp_config = i2c_smbus_read_byte_data(
	lp->client, ARCXCNN_COMP_CONFIG);

	lp->pdata->filter_config = i2c_smbus_read_byte_data(
	lp->client, ARCXCNN_FILT_CONFIG);

	lp->pdata->trim_config = i2c_smbus_read_byte_data(
	lp->client, ARCXCNN_IMAXTUNE);

	if (IS_ENABLED(CONFIG_OF))
	arcxcnn_parse_dt(lp);
	}

	i2c_set_clientdata(cl, lp);

	/* constrain settings to what is possible */
	if (lp->pdata->initial_brightness > MAX_BRIGHTNESS)
	lp->pdata->initial_brightness = MAX_BRIGHTNESS;

	/* set initial brightness */
	ret = arcxcnn_set_brightness(lp, lp->pdata->initial_brightness);
	if (ret)
	goto probe_err;

	/* set other register values directly */
	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_FADECTRL,
	lp->pdata->led_config_0);
	if (ret)
	goto probe_err;

	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_ILED_CONFIG,
	lp->pdata->led_config_1);
	if (ret)
	goto probe_err;

	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_DIMFREQ,
	lp->pdata->dim_freq);
	if (ret)
	goto probe_err;

	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_COMP_CONFIG,
	lp->pdata->comp_config);
	if (ret)
	goto probe_err;

	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_FILT_CONFIG,
	lp->pdata->filter_config);
	if (ret)
	goto probe_err;

	ret = i2c_smbus_write_byte_data(lp->client, ARCXCNN_IMAXTUNE,
	lp->pdata->trim_config);
	if (ret)
	goto probe_err;

	/* set initial LED Enables */
	arcxcnn_update_field(lp, ARCXCNN_LEDEN,
	ARCXCNN_LEDEN_MASK, lp->pdata->leden);

	ret = arcxcnn_backlight_register(lp);
	if (ret)
	goto probe_register_err;

	backlight_update_status(lp->bl);

	return 0;

	probe_register_err:
	dev_err(lp->dev,
	"failed to register backlight.\n");

	probe_err:
	dev_err(lp->dev,
	"failure ret: %d\n", ret);
	return ret;
	}

	static void arcxcnn_remove(struct i2c_client *cl)
	{
	struct arcxcnn *lp = i2c_get_clientdata(cl);

	/* disable all strings (ignore errors) */
	i2c_smbus_write_byte_data(lp->client,
	ARCXCNN_LEDEN, 0x00);
	/* reset the device (ignore errors) */
	i2c_smbus_write_byte_data(lp->client,
	ARCXCNN_CMD, ARCXCNN_CMD_RESET);

	lp->bl->props.brightness = 0;

	backlight_update_status(lp->bl);
	}

	static const struct of_device_id arcxcnn_dt_ids[] = {
	{ .compatible = "arc,arc2c0608" },
	{ }
	};
	MODULE_DEVICE_TABLE(of, arcxcnn_dt_ids);

	static const struct i2c_device_id arcxcnn_ids[] = {
	{"arc2c0608", ARC2C0608},
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, arcxcnn_ids);

	static struct i2c_driver arcxcnn_driver = {
	.driver = {
	.name = "arcxcnn_bl",
	.of_match_table = of_match_ptr(arcxcnn_dt_ids),
	},
	.probe_new = arcxcnn_probe,
	.remove = arcxcnn_remove,
	.id_table = arcxcnn_ids,
	};
	module_i2c_driver(arcxcnn_driver);

	MODULE_LICENSE("GPL v2");
	MODULE_AUTHOR("Brian Dodge <bdodge@arcticsand.com>");
	MODULE_DESCRIPTION("ARCXCNN Backlight driver");