drivers/iio/light/opt3001.c - kernel/msm-4.9 - Gitiles

 /**
  * opt3001.c - Texas Instruments OPT3001 Light Sensor
  *
  * Copyright (C) 2014 Texas Instruments Incorporated - http://www.ti.com
  *
  * Author: Andreas Dannenberg <dannenberg@ti.com>
  * Based on previous work from: Felipe Balbi <balbi@ti.com>
  *
  * This program is free software: you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 of the License
  * as published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  * more details.
  */

 #include <linux/bitops.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/types.h>

 #include <linux/iio/events.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>

 #define OPT3001_RESULT		0x00
 #define OPT3001_CONFIGURATION	0x01
 #define OPT3001_LOW_LIMIT	0x02
 #define OPT3001_HIGH_LIMIT	0x03
 #define OPT3001_MANUFACTURER_ID	0x7e
 #define OPT3001_DEVICE_ID	0x7f

 #define OPT3001_CONFIGURATION_RN_MASK	(0xf << 12)
 #define OPT3001_CONFIGURATION_RN_AUTO	(0xc << 12)

 #define OPT3001_CONFIGURATION_CT	BIT(11)

 #define OPT3001_CONFIGURATION_M_MASK	(3 << 9)
 #define OPT3001_CONFIGURATION_M_SHUTDOWN (0 << 9)
 #define OPT3001_CONFIGURATION_M_SINGLE	(1 << 9)
 #define OPT3001_CONFIGURATION_M_CONTINUOUS (2 << 9) /* also 3 << 9 */

 #define OPT3001_CONFIGURATION_OVF	BIT(8)
 #define OPT3001_CONFIGURATION_CRF	BIT(7)
 #define OPT3001_CONFIGURATION_FH	BIT(6)
 #define OPT3001_CONFIGURATION_FL	BIT(5)
 #define OPT3001_CONFIGURATION_L		BIT(4)
 #define OPT3001_CONFIGURATION_POL	BIT(3)
 #define OPT3001_CONFIGURATION_ME	BIT(2)

 #define OPT3001_CONFIGURATION_FC_MASK	(3 << 0)

 /* The end-of-conversion enable is located in the low-limit register */
 #define OPT3001_LOW_LIMIT_EOC_ENABLE	0xc000

 #define OPT3001_REG_EXPONENT(n)		((n) >> 12)
 #define OPT3001_REG_MANTISSA(n)		((n) & 0xfff)

 /*
  * Time to wait for conversion result to be ready. The device datasheet
  * worst-case max value is 880ms. Add some slack to be on the safe side.
  */
 #define OPT3001_RESULT_READY_TIMEOUT	msecs_to_jiffies(1000)

 struct opt3001 {
 	struct i2c_client	*client;
 	struct device		*dev;

 	struct mutex		lock;
 	u16			ok_to_ignore_lock:1;
 	u16			result_ready:1;
 	wait_queue_head_t	result_ready_queue;
 	u16			result;

 	u32			int_time;
 	u32			mode;

 	u16			high_thresh_mantissa;
 	u16			low_thresh_mantissa;

 	u8			high_thresh_exp;
 	u8			low_thresh_exp;
 };

 struct opt3001_scale {
 	int	val;
 	int	val2;
 };

 static const struct opt3001_scale opt3001_scales[] = {
 	{
 		.val = 40,
 		.val2 = 950000,
 	},
 	{
 		.val = 81,
 		.val2 = 900000,
 	},
 	{
 		.val = 163,
 		.val2 = 800000,
 	},
 	{
 		.val = 327,
 		.val2 = 600000,
 	},
 	{
 		.val = 655,
 		.val2 = 200000,
 	},
 	{
 		.val = 1310,
 		.val2 = 400000,
 	},
 	{
 		.val = 2620,
 		.val2 = 800000,
 	},
 	{
 		.val = 5241,
 		.val2 = 600000,
 	},
 	{
 		.val = 10483,
 		.val2 = 200000,
 	},
 	{
 		.val = 20966,
 		.val2 = 400000,
 	},
 	{
 		.val = 83865,
 		.val2 = 600000,
 	},
 };

 static int opt3001_find_scale(const struct opt3001 *opt, int val,
 		int val2, u8 *exponent)
 {
 	int i;

 	for (i = 0; i < ARRAY_SIZE(opt3001_scales); i++) {
 		const struct opt3001_scale *scale = &opt3001_scales[i];

 		/*
 		 * Combine the integer and micro parts for comparison
 		 * purposes. Use milli lux precision to avoid 32-bit integer
 		 * overflows.
 		 */
 		if ((val * 1000 + val2 / 1000) <=
 				(scale->val * 1000 + scale->val2 / 1000)) {
 			*exponent = i;
 			return 0;
 		}
 	}

 	return -EINVAL;
 }

 static void opt3001_to_iio_ret(struct opt3001 *opt, u8 exponent,
 		u16 mantissa, int *val, int *val2)
 {
 	int lux;

 	lux = 10 * (mantissa << exponent);
 	*val = lux / 1000;
 	*val2 = (lux - (*val * 1000)) * 1000;
 }

 static void opt3001_set_mode(struct opt3001 *opt, u16 *reg, u16 mode)
 {
 	*reg &= ~OPT3001_CONFIGURATION_M_MASK;
 	*reg |= mode;
 	opt->mode = mode;
 }

 static IIO_CONST_ATTR_INT_TIME_AVAIL("0.1 0.8");

 static struct attribute *opt3001_attributes[] = {
 	&iio_const_attr_integration_time_available.dev_attr.attr,
 	NULL
 };

 static const struct attribute_group opt3001_attribute_group = {
 	.attrs = opt3001_attributes,
 };

 static const struct iio_event_spec opt3001_event_spec[] = {
 	{
 		.type = IIO_EV_TYPE_THRESH,
 		.dir = IIO_EV_DIR_RISING,
 		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
 			BIT(IIO_EV_INFO_ENABLE),
 	},
 	{
 		.type = IIO_EV_TYPE_THRESH,
 		.dir = IIO_EV_DIR_FALLING,
 		.mask_separate = BIT(IIO_EV_INFO_VALUE) |
 			BIT(IIO_EV_INFO_ENABLE),
 	},
 };

 static const struct iio_chan_spec opt3001_channels[] = {
 	{
 		.type = IIO_LIGHT,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
 				BIT(IIO_CHAN_INFO_INT_TIME),
 		.event_spec = opt3001_event_spec,
 		.num_event_specs = ARRAY_SIZE(opt3001_event_spec),
 	},
 	IIO_CHAN_SOFT_TIMESTAMP(1),
 };

 static int opt3001_get_lux(struct opt3001 *opt, int *val, int *val2)
 {
 	int ret;
 	u16 mantissa;
 	u16 reg;
 	u8 exponent;
 	u16 value;

 	/*
 	 * Enable the end-of-conversion interrupt mechanism. Note that doing
 	 * so will overwrite the low-level limit value however we will restore
 	 * this value later on.
 	 */
 	ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_LOW_LIMIT,
 			OPT3001_LOW_LIMIT_EOC_ENABLE);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to write register %02x\n",
 				OPT3001_LOW_LIMIT);
 		return ret;
 	}

 	/* Reset data-ready indicator flag (will be set in the IRQ routine) */
 	opt->result_ready = false;

 	/* Allow IRQ to access the device despite lock being set */
 	opt->ok_to_ignore_lock = true;

 	/* Configure for single-conversion mode and start a new conversion */
 	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to read register %02x\n",
 				OPT3001_CONFIGURATION);
 		goto err;
 	}

 	reg = ret;
 	opt3001_set_mode(opt, &reg, OPT3001_CONFIGURATION_M_SINGLE);

 	ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_CONFIGURATION,
 			reg);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to write register %02x\n",
 				OPT3001_CONFIGURATION);
 		goto err;
 	}

 	/* Wait for the IRQ to indicate the conversion is complete */
 	ret = wait_event_timeout(opt->result_ready_queue, opt->result_ready,
 			OPT3001_RESULT_READY_TIMEOUT);

 err:
 	/* Disallow IRQ to access the device while lock is active */
 	opt->ok_to_ignore_lock = false;

 	if (ret == 0)
 		return -ETIMEDOUT;
 	else if (ret < 0)
 		return ret;

 	/*
 	 * Disable the end-of-conversion interrupt mechanism by restoring the
 	 * low-level limit value (clearing OPT3001_LOW_LIMIT_EOC_ENABLE). Note
 	 * that selectively clearing those enable bits would affect the actual
 	 * limit value due to bit-overlap and therefore can't be done.
 	 */
 	value = (opt->low_thresh_exp << 12) | opt->low_thresh_mantissa;
 	ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_LOW_LIMIT,
 			value);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to write register %02x\n",
 				OPT3001_LOW_LIMIT);
 		return ret;
 	}

 	exponent = OPT3001_REG_EXPONENT(opt->result);
 	mantissa = OPT3001_REG_MANTISSA(opt->result);

 	opt3001_to_iio_ret(opt, exponent, mantissa, val, val2);

 	return IIO_VAL_INT_PLUS_MICRO;
 }

 static int opt3001_get_int_time(struct opt3001 *opt, int *val, int *val2)
 {
 	*val = 0;
 	*val2 = opt->int_time;

 	return IIO_VAL_INT_PLUS_MICRO;
 }

 static int opt3001_set_int_time(struct opt3001 *opt, int time)
 {
 	int ret;
 	u16 reg;

 	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to read register %02x\n",
 				OPT3001_CONFIGURATION);
 		return ret;
 	}

 	reg = ret;

 	switch (time) {
 	case 100000:
 		reg &= ~OPT3001_CONFIGURATION_CT;
 		opt->int_time = 100000;
 		break;
 	case 800000:
 		reg |= OPT3001_CONFIGURATION_CT;
 		opt->int_time = 800000;
 		break;
 	default:
 		return -EINVAL;
 	}

 	return i2c_smbus_write_word_swapped(opt->client, OPT3001_CONFIGURATION,
 			reg);
 }

 static int opt3001_read_raw(struct iio_dev *iio,
 		struct iio_chan_spec const *chan, int *val, int *val2,
 		long mask)
 {
 	struct opt3001 *opt = iio_priv(iio);
 	int ret;

 	if (opt->mode == OPT3001_CONFIGURATION_M_CONTINUOUS)
 		return -EBUSY;

 	if (chan->type != IIO_LIGHT)
 		return -EINVAL;

 	mutex_lock(&opt->lock);

 	switch (mask) {
 	case IIO_CHAN_INFO_PROCESSED:
 		ret = opt3001_get_lux(opt, val, val2);
 		break;
 	case IIO_CHAN_INFO_INT_TIME:
 		ret = opt3001_get_int_time(opt, val, val2);
 		break;
 	default:
 		ret = -EINVAL;
 	}

 	mutex_unlock(&opt->lock);

 	return ret;
 }

 static int opt3001_write_raw(struct iio_dev *iio,
 		struct iio_chan_spec const *chan, int val, int val2,
 		long mask)
 {
 	struct opt3001 *opt = iio_priv(iio);
 	int ret;

 	if (opt->mode == OPT3001_CONFIGURATION_M_CONTINUOUS)
 		return -EBUSY;

 	if (chan->type != IIO_LIGHT)
 		return -EINVAL;

 	if (mask != IIO_CHAN_INFO_INT_TIME)
 		return -EINVAL;

 	if (val != 0)
 		return -EINVAL;

 	mutex_lock(&opt->lock);
 	ret = opt3001_set_int_time(opt, val2);
 	mutex_unlock(&opt->lock);

 	return ret;
 }

 static int opt3001_read_event_value(struct iio_dev *iio,
 		const struct iio_chan_spec *chan, enum iio_event_type type,
 		enum iio_event_direction dir, enum iio_event_info info,
 		int *val, int *val2)
 {
 	struct opt3001 *opt = iio_priv(iio);
 	int ret = IIO_VAL_INT_PLUS_MICRO;

 	mutex_lock(&opt->lock);

 	switch (dir) {
 	case IIO_EV_DIR_RISING:
 		opt3001_to_iio_ret(opt, opt->high_thresh_exp,
 				opt->high_thresh_mantissa, val, val2);
 		break;
 	case IIO_EV_DIR_FALLING:
 		opt3001_to_iio_ret(opt, opt->low_thresh_exp,
 				opt->low_thresh_mantissa, val, val2);
 		break;
 	default:
 		ret = -EINVAL;
 	}

 	mutex_unlock(&opt->lock);

 	return ret;
 }

 static int opt3001_write_event_value(struct iio_dev *iio,
 		const struct iio_chan_spec *chan, enum iio_event_type type,
 		enum iio_event_direction dir, enum iio_event_info info,
 		int val, int val2)
 {
 	struct opt3001 *opt = iio_priv(iio);
 	int ret;

 	u16 mantissa;
 	u16 value;
 	u16 reg;

 	u8 exponent;

 	if (val < 0)
 		return -EINVAL;

 	mutex_lock(&opt->lock);

 	ret = opt3001_find_scale(opt, val, val2, &exponent);
 	if (ret < 0) {
 		dev_err(opt->dev, "can't find scale for %d.%06u\n", val, val2);
 		goto err;
 	}

 	mantissa = (((val * 1000) + (val2 / 1000)) / 10) >> exponent;
 	value = (exponent << 12) | mantissa;

 	switch (dir) {
 	case IIO_EV_DIR_RISING:
 		reg = OPT3001_HIGH_LIMIT;
 		opt->high_thresh_mantissa = mantissa;
 		opt->high_thresh_exp = exponent;
 		break;
 	case IIO_EV_DIR_FALLING:
 		reg = OPT3001_LOW_LIMIT;
 		opt->low_thresh_mantissa = mantissa;
 		opt->low_thresh_exp = exponent;
 		break;
 	default:
 		ret = -EINVAL;
 		goto err;
 	}

 	ret = i2c_smbus_write_word_swapped(opt->client, reg, value);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to write register %02x\n", reg);
 		goto err;
 	}

 err:
 	mutex_unlock(&opt->lock);

 	return ret;
 }

 static int opt3001_read_event_config(struct iio_dev *iio,
 		const struct iio_chan_spec *chan, enum iio_event_type type,
 		enum iio_event_direction dir)
 {
 	struct opt3001 *opt = iio_priv(iio);

 	return opt->mode == OPT3001_CONFIGURATION_M_CONTINUOUS;
 }

 static int opt3001_write_event_config(struct iio_dev *iio,
 		const struct iio_chan_spec *chan, enum iio_event_type type,
 		enum iio_event_direction dir, int state)
 {
 	struct opt3001 *opt = iio_priv(iio);
 	int ret;
 	u16 mode;
 	u16 reg;

 	if (state && opt->mode == OPT3001_CONFIGURATION_M_CONTINUOUS)
 		return 0;

 	if (!state && opt->mode == OPT3001_CONFIGURATION_M_SHUTDOWN)
 		return 0;

 	mutex_lock(&opt->lock);

 	mode = state ? OPT3001_CONFIGURATION_M_CONTINUOUS
 		: OPT3001_CONFIGURATION_M_SHUTDOWN;

 	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to read register %02x\n",
 				OPT3001_CONFIGURATION);
 		goto err;
 	}

 	reg = ret;
 	opt3001_set_mode(opt, &reg, mode);

 	ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_CONFIGURATION,
 			reg);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to write register %02x\n",
 				OPT3001_CONFIGURATION);
 		goto err;
 	}

 err:
 	mutex_unlock(&opt->lock);

 	return ret;
 }

 static const struct iio_info opt3001_info = {
 	.driver_module = THIS_MODULE,
 	.attrs = &opt3001_attribute_group,
 	.read_raw = opt3001_read_raw,
 	.write_raw = opt3001_write_raw,
 	.read_event_value = opt3001_read_event_value,
 	.write_event_value = opt3001_write_event_value,
 	.read_event_config = opt3001_read_event_config,
 	.write_event_config = opt3001_write_event_config,
 };

 static int opt3001_read_id(struct opt3001 *opt)
 {
 	char manufacturer[2];
 	u16 device_id;
 	int ret;

 	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_MANUFACTURER_ID);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to read register %02x\n",
 				OPT3001_MANUFACTURER_ID);
 		return ret;
 	}

 	manufacturer[0] = ret >> 8;
 	manufacturer[1] = ret & 0xff;

 	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_DEVICE_ID);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to read register %02x\n",
 				OPT3001_DEVICE_ID);
 		return ret;
 	}

 	device_id = ret;

 	dev_info(opt->dev, "Found %c%c OPT%04x\n", manufacturer[0],
 			manufacturer[1], device_id);

 	return 0;
 }

 static int opt3001_configure(struct opt3001 *opt)
 {
 	int ret;
 	u16 reg;

 	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to read register %02x\n",
 				OPT3001_CONFIGURATION);
 		return ret;
 	}

 	reg = ret;

 	/* Enable automatic full-scale setting mode */
 	reg &= ~OPT3001_CONFIGURATION_RN_MASK;
 	reg |= OPT3001_CONFIGURATION_RN_AUTO;

 	/* Reflect status of the device's integration time setting */
 	if (reg & OPT3001_CONFIGURATION_CT)
 		opt->int_time = 800000;
 	else
 		opt->int_time = 100000;

 	/* Ensure device is in shutdown initially */
 	opt3001_set_mode(opt, &reg, OPT3001_CONFIGURATION_M_SHUTDOWN);

 	/* Configure for latched window-style comparison operation */
 	reg |= OPT3001_CONFIGURATION_L;
 	reg &= ~OPT3001_CONFIGURATION_POL;
 	reg &= ~OPT3001_CONFIGURATION_ME;
 	reg &= ~OPT3001_CONFIGURATION_FC_MASK;

 	ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_CONFIGURATION,
 			reg);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to write register %02x\n",
 				OPT3001_CONFIGURATION);
 		return ret;
 	}

 	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_LOW_LIMIT);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to read register %02x\n",
 				OPT3001_LOW_LIMIT);
 		return ret;
 	}

 	opt->low_thresh_mantissa = OPT3001_REG_MANTISSA(ret);
 	opt->low_thresh_exp = OPT3001_REG_EXPONENT(ret);

 	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_HIGH_LIMIT);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to read register %02x\n",
 				OPT3001_HIGH_LIMIT);
 		return ret;
 	}

 	opt->high_thresh_mantissa = OPT3001_REG_MANTISSA(ret);
 	opt->high_thresh_exp = OPT3001_REG_EXPONENT(ret);

 	return 0;
 }

 static irqreturn_t opt3001_irq(int irq, void *_iio)
 {
 	struct iio_dev *iio = _iio;
 	struct opt3001 *opt = iio_priv(iio);
 	int ret;

 	if (!opt->ok_to_ignore_lock)
 		mutex_lock(&opt->lock);

 	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to read register %02x\n",
 				OPT3001_CONFIGURATION);
 		goto out;
 	}

 	if ((ret & OPT3001_CONFIGURATION_M_MASK) ==
 			OPT3001_CONFIGURATION_M_CONTINUOUS) {
 		if (ret & OPT3001_CONFIGURATION_FH)
 			iio_push_event(iio,
 					IIO_UNMOD_EVENT_CODE(IIO_LIGHT, 0,
 							IIO_EV_TYPE_THRESH,
 							IIO_EV_DIR_RISING),
 					iio_get_time_ns());
 		if (ret & OPT3001_CONFIGURATION_FL)
 			iio_push_event(iio,
 					IIO_UNMOD_EVENT_CODE(IIO_LIGHT, 0,
 							IIO_EV_TYPE_THRESH,
 							IIO_EV_DIR_FALLING),
 					iio_get_time_ns());
 	} else if (ret & OPT3001_CONFIGURATION_CRF) {
 		ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_RESULT);
 		if (ret < 0) {
 			dev_err(opt->dev, "failed to read register %02x\n",
 					OPT3001_RESULT);
 			goto out;
 		}
 		opt->result = ret;
 		opt->result_ready = true;
 		wake_up(&opt->result_ready_queue);
 	}

 out:
 	if (!opt->ok_to_ignore_lock)
 		mutex_unlock(&opt->lock);

 	return IRQ_HANDLED;
 }

 static int opt3001_probe(struct i2c_client *client,
 		const struct i2c_device_id *id)
 {
 	struct device *dev = &client->dev;

 	struct iio_dev *iio;
 	struct opt3001 *opt;
 	int irq = client->irq;
 	int ret;

 	iio = devm_iio_device_alloc(dev, sizeof(*opt));
 	if (!iio)
 		return -ENOMEM;

 	opt = iio_priv(iio);
 	opt->client = client;
 	opt->dev = dev;

 	mutex_init(&opt->lock);
 	init_waitqueue_head(&opt->result_ready_queue);
 	i2c_set_clientdata(client, iio);

 	ret = opt3001_read_id(opt);
 	if (ret)
 		return ret;

 	ret = opt3001_configure(opt);
 	if (ret)
 		return ret;

 	iio->name = client->name;
 	iio->channels = opt3001_channels;
 	iio->num_channels = ARRAY_SIZE(opt3001_channels);
 	iio->dev.parent = dev;
 	iio->modes = INDIO_DIRECT_MODE;
 	iio->info = &opt3001_info;

 	ret = devm_iio_device_register(dev, iio);
 	if (ret) {
 		dev_err(dev, "failed to register IIO device\n");
 		return ret;
 	}

 	ret = request_threaded_irq(irq, NULL, opt3001_irq,
 			IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
 			"opt3001", iio);
 	if (ret) {
 		dev_err(dev, "failed to request IRQ #%d\n", irq);
 		return ret;
 	}

 	return 0;
 }

 static int opt3001_remove(struct i2c_client *client)
 {
 	struct iio_dev *iio = i2c_get_clientdata(client);
 	struct opt3001 *opt = iio_priv(iio);
 	int ret;
 	u16 reg;

 	free_irq(client->irq, iio);

 	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to read register %02x\n",
 				OPT3001_CONFIGURATION);
 		return ret;
 	}

 	reg = ret;
 	opt3001_set_mode(opt, &reg, OPT3001_CONFIGURATION_M_SHUTDOWN);

 	ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_CONFIGURATION,
 			reg);
 	if (ret < 0) {
 		dev_err(opt->dev, "failed to write register %02x\n",
 				OPT3001_CONFIGURATION);
 		return ret;
 	}

 	return 0;
 }

 static const struct i2c_device_id opt3001_id[] = {
 	{ "opt3001", 0 },
 	{ } /* Terminating Entry */
 };
 MODULE_DEVICE_TABLE(i2c, opt3001_id);

 static const struct of_device_id opt3001_of_match[] = {
 	{ .compatible = "ti,opt3001" },
 	{ }
 };

 static struct i2c_driver opt3001_driver = {
 	.probe = opt3001_probe,
 	.remove = opt3001_remove,
 	.id_table = opt3001_id,

 	.driver = {
 		.name = "opt3001",
 		.of_match_table = of_match_ptr(opt3001_of_match),
 	},
 };

 module_i2c_driver(opt3001_driver);

 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("Andreas Dannenberg <dannenberg@ti.com>");
 MODULE_DESCRIPTION("Texas Instruments OPT3001 Light Sensor Driver");
	/**
	* opt3001.c - Texas Instruments OPT3001 Light Sensor
	*
	* Copyright (C) 2014 Texas Instruments Incorporated - http://www.ti.com
	*
	* Author: Andreas Dannenberg <dannenberg@ti.com>
	* Based on previous work from: Felipe Balbi <balbi@ti.com>
	*
	* This program is free software: you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 of the License
	* as published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	* more details.
	*/

	#include <linux/bitops.h>
	#include <linux/delay.h>
	#include <linux/device.h>
	#include <linux/i2c.h>
	#include <linux/interrupt.h>
	#include <linux/irq.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/slab.h>
	#include <linux/types.h>

	#include <linux/iio/events.h>
	#include <linux/iio/iio.h>
	#include <linux/iio/sysfs.h>

	#define OPT3001_RESULT 0x00
	#define OPT3001_CONFIGURATION 0x01
	#define OPT3001_LOW_LIMIT 0x02
	#define OPT3001_HIGH_LIMIT 0x03
	#define OPT3001_MANUFACTURER_ID 0x7e
	#define OPT3001_DEVICE_ID 0x7f

	#define OPT3001_CONFIGURATION_RN_MASK (0xf << 12)
	#define OPT3001_CONFIGURATION_RN_AUTO (0xc << 12)

	#define OPT3001_CONFIGURATION_CT BIT(11)

	#define OPT3001_CONFIGURATION_M_MASK (3 << 9)
	#define OPT3001_CONFIGURATION_M_SHUTDOWN (0 << 9)
	#define OPT3001_CONFIGURATION_M_SINGLE (1 << 9)
	#define OPT3001_CONFIGURATION_M_CONTINUOUS (2 << 9) /* also 3 << 9 */

	#define OPT3001_CONFIGURATION_OVF BIT(8)
	#define OPT3001_CONFIGURATION_CRF BIT(7)
	#define OPT3001_CONFIGURATION_FH BIT(6)
	#define OPT3001_CONFIGURATION_FL BIT(5)
	#define OPT3001_CONFIGURATION_L BIT(4)
	#define OPT3001_CONFIGURATION_POL BIT(3)
	#define OPT3001_CONFIGURATION_ME BIT(2)

	#define OPT3001_CONFIGURATION_FC_MASK (3 << 0)

	/* The end-of-conversion enable is located in the low-limit register */
	#define OPT3001_LOW_LIMIT_EOC_ENABLE 0xc000

	#define OPT3001_REG_EXPONENT(n) ((n) >> 12)
	#define OPT3001_REG_MANTISSA(n) ((n) & 0xfff)

	/*
	* Time to wait for conversion result to be ready. The device datasheet
	* worst-case max value is 880ms. Add some slack to be on the safe side.
	*/
	#define OPT3001_RESULT_READY_TIMEOUT msecs_to_jiffies(1000)

	struct opt3001 {
	struct i2c_client *client;
	struct device *dev;

	struct mutex lock;
	u16 ok_to_ignore_lock:1;
	u16 result_ready:1;
	wait_queue_head_t result_ready_queue;
	u16 result;

	u32 int_time;
	u32 mode;

	u16 high_thresh_mantissa;
	u16 low_thresh_mantissa;

	u8 high_thresh_exp;
	u8 low_thresh_exp;
	};

	struct opt3001_scale {
	int val;
	int val2;
	};

	static const struct opt3001_scale opt3001_scales[] = {
	{
	.val = 40,
	.val2 = 950000,
	},
	{
	.val = 81,
	.val2 = 900000,
	},
	{
	.val = 163,
	.val2 = 800000,
	},
	{
	.val = 327,
	.val2 = 600000,
	},
	{
	.val = 655,
	.val2 = 200000,
	},
	{
	.val = 1310,
	.val2 = 400000,
	},
	{
	.val = 2620,
	.val2 = 800000,
	},
	{
	.val = 5241,
	.val2 = 600000,
	},
	{
	.val = 10483,
	.val2 = 200000,
	},
	{
	.val = 20966,
	.val2 = 400000,
	},
	{
	.val = 83865,
	.val2 = 600000,
	},
	};

	static int opt3001_find_scale(const struct opt3001 *opt, int val,
	int val2, u8 *exponent)
	{
	int i;

	for (i = 0; i < ARRAY_SIZE(opt3001_scales); i++) {
	const struct opt3001_scale *scale = &opt3001_scales[i];

	/*
	* Combine the integer and micro parts for comparison
	* purposes. Use milli lux precision to avoid 32-bit integer
	* overflows.
	*/
	if ((val * 1000 + val2 / 1000) <=
	(scale->val * 1000 + scale->val2 / 1000)) {
	*exponent = i;
	return 0;
	}
	}

	return -EINVAL;
	}

	static void opt3001_to_iio_ret(struct opt3001 *opt, u8 exponent,
	u16 mantissa, int val, int val2)
	{
	int lux;

	lux = 10 * (mantissa << exponent);
	*val = lux / 1000;
	val2 = (lux - (val * 1000)) * 1000;
	}

	static void opt3001_set_mode(struct opt3001 opt, u16 reg, u16 mode)
	{
	*reg &= ~OPT3001_CONFIGURATION_M_MASK;
	*reg \|= mode;
	opt->mode = mode;
	}

	static IIO_CONST_ATTR_INT_TIME_AVAIL("0.1 0.8");

	static struct attribute *opt3001_attributes[] = {
	&iio_const_attr_integration_time_available.dev_attr.attr,
	NULL
	};

	static const struct attribute_group opt3001_attribute_group = {
	.attrs = opt3001_attributes,
	};

	static const struct iio_event_spec opt3001_event_spec[] = {
	{
	.type = IIO_EV_TYPE_THRESH,
	.dir = IIO_EV_DIR_RISING,
	.mask_separate = BIT(IIO_EV_INFO_VALUE) \|
	BIT(IIO_EV_INFO_ENABLE),
	},
	{
	.type = IIO_EV_TYPE_THRESH,
	.dir = IIO_EV_DIR_FALLING,
	.mask_separate = BIT(IIO_EV_INFO_VALUE) \|
	BIT(IIO_EV_INFO_ENABLE),
	},
	};

	static const struct iio_chan_spec opt3001_channels[] = {
	{
	.type = IIO_LIGHT,
	.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) \|
	BIT(IIO_CHAN_INFO_INT_TIME),
	.event_spec = opt3001_event_spec,
	.num_event_specs = ARRAY_SIZE(opt3001_event_spec),
	},
	IIO_CHAN_SOFT_TIMESTAMP(1),
	};

	static int opt3001_get_lux(struct opt3001 opt, int val, int *val2)
	{
	int ret;
	u16 mantissa;
	u16 reg;
	u8 exponent;
	u16 value;

	/*
	* Enable the end-of-conversion interrupt mechanism. Note that doing
	* so will overwrite the low-level limit value however we will restore
	* this value later on.
	*/
	ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_LOW_LIMIT,
	OPT3001_LOW_LIMIT_EOC_ENABLE);
	if (ret < 0) {
	dev_err(opt->dev, "failed to write register %02x\n",
	OPT3001_LOW_LIMIT);
	return ret;
	}

	/* Reset data-ready indicator flag (will be set in the IRQ routine) */
	opt->result_ready = false;

	/* Allow IRQ to access the device despite lock being set */
	opt->ok_to_ignore_lock = true;

	/* Configure for single-conversion mode and start a new conversion */
	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
	if (ret < 0) {
	dev_err(opt->dev, "failed to read register %02x\n",
	OPT3001_CONFIGURATION);
	goto err;
	}

	reg = ret;
	opt3001_set_mode(opt, &reg, OPT3001_CONFIGURATION_M_SINGLE);

	ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_CONFIGURATION,
	reg);
	if (ret < 0) {
	dev_err(opt->dev, "failed to write register %02x\n",
	OPT3001_CONFIGURATION);
	goto err;
	}

	/* Wait for the IRQ to indicate the conversion is complete */
	ret = wait_event_timeout(opt->result_ready_queue, opt->result_ready,
	OPT3001_RESULT_READY_TIMEOUT);

	err:
	/* Disallow IRQ to access the device while lock is active */
	opt->ok_to_ignore_lock = false;

	if (ret == 0)
	return -ETIMEDOUT;
	else if (ret < 0)
	return ret;

	/*
	* Disable the end-of-conversion interrupt mechanism by restoring the
	* low-level limit value (clearing OPT3001_LOW_LIMIT_EOC_ENABLE). Note
	* that selectively clearing those enable bits would affect the actual
	* limit value due to bit-overlap and therefore can't be done.
	*/
	value = (opt->low_thresh_exp << 12) \| opt->low_thresh_mantissa;
	ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_LOW_LIMIT,
	value);
	if (ret < 0) {
	dev_err(opt->dev, "failed to write register %02x\n",
	OPT3001_LOW_LIMIT);
	return ret;
	}

	exponent = OPT3001_REG_EXPONENT(opt->result);
	mantissa = OPT3001_REG_MANTISSA(opt->result);

	opt3001_to_iio_ret(opt, exponent, mantissa, val, val2);

	return IIO_VAL_INT_PLUS_MICRO;
	}

	static int opt3001_get_int_time(struct opt3001 opt, int val, int *val2)
	{
	*val = 0;
	*val2 = opt->int_time;

	return IIO_VAL_INT_PLUS_MICRO;
	}

	static int opt3001_set_int_time(struct opt3001 *opt, int time)
	{
	int ret;
	u16 reg;

	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
	if (ret < 0) {
	dev_err(opt->dev, "failed to read register %02x\n",
	OPT3001_CONFIGURATION);
	return ret;
	}

	reg = ret;

	switch (time) {
	case 100000:
	reg &= ~OPT3001_CONFIGURATION_CT;
	opt->int_time = 100000;
	break;
	case 800000:
	reg \|= OPT3001_CONFIGURATION_CT;
	opt->int_time = 800000;
	break;
	default:
	return -EINVAL;
	}

	return i2c_smbus_write_word_swapped(opt->client, OPT3001_CONFIGURATION,
	reg);
	}

	static int opt3001_read_raw(struct iio_dev *iio,
	struct iio_chan_spec const chan, int val, int *val2,
	long mask)
	{
	struct opt3001 *opt = iio_priv(iio);
	int ret;

	if (opt->mode == OPT3001_CONFIGURATION_M_CONTINUOUS)
	return -EBUSY;

	if (chan->type != IIO_LIGHT)
	return -EINVAL;

	mutex_lock(&opt->lock);

	switch (mask) {
	case IIO_CHAN_INFO_PROCESSED:
	ret = opt3001_get_lux(opt, val, val2);
	break;
	case IIO_CHAN_INFO_INT_TIME:
	ret = opt3001_get_int_time(opt, val, val2);
	break;
	default:
	ret = -EINVAL;
	}

	mutex_unlock(&opt->lock);

	return ret;
	}

	static int opt3001_write_raw(struct iio_dev *iio,
	struct iio_chan_spec const *chan, int val, int val2,
	long mask)
	{
	struct opt3001 *opt = iio_priv(iio);
	int ret;

	if (opt->mode == OPT3001_CONFIGURATION_M_CONTINUOUS)
	return -EBUSY;

	if (chan->type != IIO_LIGHT)
	return -EINVAL;

	if (mask != IIO_CHAN_INFO_INT_TIME)
	return -EINVAL;

	if (val != 0)
	return -EINVAL;

	mutex_lock(&opt->lock);
	ret = opt3001_set_int_time(opt, val2);
	mutex_unlock(&opt->lock);

	return ret;
	}

	static int opt3001_read_event_value(struct iio_dev *iio,
	const struct iio_chan_spec *chan, enum iio_event_type type,
	enum iio_event_direction dir, enum iio_event_info info,
	int val, int val2)
	{
	struct opt3001 *opt = iio_priv(iio);
	int ret = IIO_VAL_INT_PLUS_MICRO;

	mutex_lock(&opt->lock);

	switch (dir) {
	case IIO_EV_DIR_RISING:
	opt3001_to_iio_ret(opt, opt->high_thresh_exp,
	opt->high_thresh_mantissa, val, val2);
	break;
	case IIO_EV_DIR_FALLING:
	opt3001_to_iio_ret(opt, opt->low_thresh_exp,
	opt->low_thresh_mantissa, val, val2);
	break;
	default:
	ret = -EINVAL;
	}

	mutex_unlock(&opt->lock);

	return ret;
	}

	static int opt3001_write_event_value(struct iio_dev *iio,
	const struct iio_chan_spec *chan, enum iio_event_type type,
	enum iio_event_direction dir, enum iio_event_info info,
	int val, int val2)
	{
	struct opt3001 *opt = iio_priv(iio);
	int ret;

	u16 mantissa;
	u16 value;
	u16 reg;

	u8 exponent;

	if (val < 0)
	return -EINVAL;

	mutex_lock(&opt->lock);

	ret = opt3001_find_scale(opt, val, val2, &exponent);
	if (ret < 0) {
	dev_err(opt->dev, "can't find scale for %d.%06u\n", val, val2);
	goto err;
	}

	mantissa = (((val * 1000) + (val2 / 1000)) / 10) >> exponent;
	value = (exponent << 12) \| mantissa;

	switch (dir) {
	case IIO_EV_DIR_RISING:
	reg = OPT3001_HIGH_LIMIT;
	opt->high_thresh_mantissa = mantissa;
	opt->high_thresh_exp = exponent;
	break;
	case IIO_EV_DIR_FALLING:
	reg = OPT3001_LOW_LIMIT;
	opt->low_thresh_mantissa = mantissa;
	opt->low_thresh_exp = exponent;
	break;
	default:
	ret = -EINVAL;
	goto err;
	}

	ret = i2c_smbus_write_word_swapped(opt->client, reg, value);
	if (ret < 0) {
	dev_err(opt->dev, "failed to write register %02x\n", reg);
	goto err;
	}

	err:
	mutex_unlock(&opt->lock);

	return ret;
	}

	static int opt3001_read_event_config(struct iio_dev *iio,
	const struct iio_chan_spec *chan, enum iio_event_type type,
	enum iio_event_direction dir)
	{
	struct opt3001 *opt = iio_priv(iio);

	return opt->mode == OPT3001_CONFIGURATION_M_CONTINUOUS;
	}

	static int opt3001_write_event_config(struct iio_dev *iio,
	const struct iio_chan_spec *chan, enum iio_event_type type,
	enum iio_event_direction dir, int state)
	{
	struct opt3001 *opt = iio_priv(iio);
	int ret;
	u16 mode;
	u16 reg;

	if (state && opt->mode == OPT3001_CONFIGURATION_M_CONTINUOUS)
	return 0;

	if (!state && opt->mode == OPT3001_CONFIGURATION_M_SHUTDOWN)
	return 0;

	mutex_lock(&opt->lock);

	mode = state ? OPT3001_CONFIGURATION_M_CONTINUOUS
	: OPT3001_CONFIGURATION_M_SHUTDOWN;

	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
	if (ret < 0) {
	dev_err(opt->dev, "failed to read register %02x\n",
	OPT3001_CONFIGURATION);
	goto err;
	}

	reg = ret;
	opt3001_set_mode(opt, &reg, mode);

	ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_CONFIGURATION,
	reg);
	if (ret < 0) {
	dev_err(opt->dev, "failed to write register %02x\n",
	OPT3001_CONFIGURATION);
	goto err;
	}

	err:
	mutex_unlock(&opt->lock);

	return ret;
	}

	static const struct iio_info opt3001_info = {
	.driver_module = THIS_MODULE,
	.attrs = &opt3001_attribute_group,
	.read_raw = opt3001_read_raw,
	.write_raw = opt3001_write_raw,
	.read_event_value = opt3001_read_event_value,
	.write_event_value = opt3001_write_event_value,
	.read_event_config = opt3001_read_event_config,
	.write_event_config = opt3001_write_event_config,
	};

	static int opt3001_read_id(struct opt3001 *opt)
	{
	char manufacturer[2];
	u16 device_id;
	int ret;

	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_MANUFACTURER_ID);
	if (ret < 0) {
	dev_err(opt->dev, "failed to read register %02x\n",
	OPT3001_MANUFACTURER_ID);
	return ret;
	}

	manufacturer[0] = ret >> 8;
	manufacturer[1] = ret & 0xff;

	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_DEVICE_ID);
	if (ret < 0) {
	dev_err(opt->dev, "failed to read register %02x\n",
	OPT3001_DEVICE_ID);
	return ret;
	}

	device_id = ret;

	dev_info(opt->dev, "Found %c%c OPT%04x\n", manufacturer[0],
	manufacturer[1], device_id);

	return 0;
	}

	static int opt3001_configure(struct opt3001 *opt)
	{
	int ret;
	u16 reg;

	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
	if (ret < 0) {
	dev_err(opt->dev, "failed to read register %02x\n",
	OPT3001_CONFIGURATION);
	return ret;
	}

	reg = ret;

	/* Enable automatic full-scale setting mode */
	reg &= ~OPT3001_CONFIGURATION_RN_MASK;
	reg \|= OPT3001_CONFIGURATION_RN_AUTO;

	/* Reflect status of the device's integration time setting */
	if (reg & OPT3001_CONFIGURATION_CT)
	opt->int_time = 800000;
	else
	opt->int_time = 100000;

	/* Ensure device is in shutdown initially */
	opt3001_set_mode(opt, &reg, OPT3001_CONFIGURATION_M_SHUTDOWN);

	/* Configure for latched window-style comparison operation */
	reg \|= OPT3001_CONFIGURATION_L;
	reg &= ~OPT3001_CONFIGURATION_POL;
	reg &= ~OPT3001_CONFIGURATION_ME;
	reg &= ~OPT3001_CONFIGURATION_FC_MASK;

	ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_CONFIGURATION,
	reg);
	if (ret < 0) {
	dev_err(opt->dev, "failed to write register %02x\n",
	OPT3001_CONFIGURATION);
	return ret;
	}

	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_LOW_LIMIT);
	if (ret < 0) {
	dev_err(opt->dev, "failed to read register %02x\n",
	OPT3001_LOW_LIMIT);
	return ret;
	}

	opt->low_thresh_mantissa = OPT3001_REG_MANTISSA(ret);
	opt->low_thresh_exp = OPT3001_REG_EXPONENT(ret);

	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_HIGH_LIMIT);
	if (ret < 0) {
	dev_err(opt->dev, "failed to read register %02x\n",
	OPT3001_HIGH_LIMIT);
	return ret;
	}

	opt->high_thresh_mantissa = OPT3001_REG_MANTISSA(ret);
	opt->high_thresh_exp = OPT3001_REG_EXPONENT(ret);

	return 0;
	}

	static irqreturn_t opt3001_irq(int irq, void *_iio)
	{
	struct iio_dev *iio = _iio;
	struct opt3001 *opt = iio_priv(iio);
	int ret;

	if (!opt->ok_to_ignore_lock)
	mutex_lock(&opt->lock);

	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
	if (ret < 0) {
	dev_err(opt->dev, "failed to read register %02x\n",
	OPT3001_CONFIGURATION);
	goto out;
	}

	if ((ret & OPT3001_CONFIGURATION_M_MASK) ==
	OPT3001_CONFIGURATION_M_CONTINUOUS) {
	if (ret & OPT3001_CONFIGURATION_FH)
	iio_push_event(iio,
	IIO_UNMOD_EVENT_CODE(IIO_LIGHT, 0,
	IIO_EV_TYPE_THRESH,
	IIO_EV_DIR_RISING),
	iio_get_time_ns());
	if (ret & OPT3001_CONFIGURATION_FL)
	iio_push_event(iio,
	IIO_UNMOD_EVENT_CODE(IIO_LIGHT, 0,
	IIO_EV_TYPE_THRESH,
	IIO_EV_DIR_FALLING),
	iio_get_time_ns());
	} else if (ret & OPT3001_CONFIGURATION_CRF) {
	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_RESULT);
	if (ret < 0) {
	dev_err(opt->dev, "failed to read register %02x\n",
	OPT3001_RESULT);
	goto out;
	}
	opt->result = ret;
	opt->result_ready = true;
	wake_up(&opt->result_ready_queue);
	}

	out:
	if (!opt->ok_to_ignore_lock)
	mutex_unlock(&opt->lock);

	return IRQ_HANDLED;
	}

	static int opt3001_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct device *dev = &client->dev;

	struct iio_dev *iio;
	struct opt3001 *opt;
	int irq = client->irq;
	int ret;

	iio = devm_iio_device_alloc(dev, sizeof(*opt));
	if (!iio)
	return -ENOMEM;

	opt = iio_priv(iio);
	opt->client = client;
	opt->dev = dev;

	mutex_init(&opt->lock);
	init_waitqueue_head(&opt->result_ready_queue);
	i2c_set_clientdata(client, iio);

	ret = opt3001_read_id(opt);
	if (ret)
	return ret;

	ret = opt3001_configure(opt);
	if (ret)
	return ret;

	iio->name = client->name;
	iio->channels = opt3001_channels;
	iio->num_channels = ARRAY_SIZE(opt3001_channels);
	iio->dev.parent = dev;
	iio->modes = INDIO_DIRECT_MODE;
	iio->info = &opt3001_info;

	ret = devm_iio_device_register(dev, iio);
	if (ret) {
	dev_err(dev, "failed to register IIO device\n");
	return ret;
	}

	ret = request_threaded_irq(irq, NULL, opt3001_irq,
	IRQF_TRIGGER_FALLING \| IRQF_ONESHOT,
	"opt3001", iio);
	if (ret) {
	dev_err(dev, "failed to request IRQ #%d\n", irq);
	return ret;
	}

	return 0;
	}

	static int opt3001_remove(struct i2c_client *client)
	{
	struct iio_dev *iio = i2c_get_clientdata(client);
	struct opt3001 *opt = iio_priv(iio);
	int ret;
	u16 reg;

	free_irq(client->irq, iio);

	ret = i2c_smbus_read_word_swapped(opt->client, OPT3001_CONFIGURATION);
	if (ret < 0) {
	dev_err(opt->dev, "failed to read register %02x\n",
	OPT3001_CONFIGURATION);
	return ret;
	}

	reg = ret;
	opt3001_set_mode(opt, &reg, OPT3001_CONFIGURATION_M_SHUTDOWN);

	ret = i2c_smbus_write_word_swapped(opt->client, OPT3001_CONFIGURATION,
	reg);
	if (ret < 0) {
	dev_err(opt->dev, "failed to write register %02x\n",
	OPT3001_CONFIGURATION);
	return ret;
	}

	return 0;
	}

	static const struct i2c_device_id opt3001_id[] = {
	{ "opt3001", 0 },
	{ } /* Terminating Entry */
	};
	MODULE_DEVICE_TABLE(i2c, opt3001_id);

	static const struct of_device_id opt3001_of_match[] = {
	{ .compatible = "ti,opt3001" },
	{ }
	};

	static struct i2c_driver opt3001_driver = {
	.probe = opt3001_probe,
	.remove = opt3001_remove,
	.id_table = opt3001_id,

	.driver = {
	.name = "opt3001",
	.of_match_table = of_match_ptr(opt3001_of_match),
	},
	};

	module_i2c_driver(opt3001_driver);

	MODULE_LICENSE("GPL v2");
	MODULE_AUTHOR("Andreas Dannenberg <dannenberg@ti.com>");
	MODULE_DESCRIPTION("Texas Instruments OPT3001 Light Sensor Driver");