drivers/iio/adc/ad7291.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * AD7291 8-Channel, I2C, 12-Bit SAR ADC with Temperature Sensor
  *
  * Copyright 2010-2011 Analog Devices Inc.
  */

 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/regulator/consumer.h>
 #include <linux/slab.h>
 #include <linux/sysfs.h>

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

 #include <linux/platform_data/ad7291.h>

 /*
  * Simplified handling
  *
  * If no events enabled - single polled channel read
  * If event enabled direct reads disable unless channel
  * is in the read mask.
  *
  * The noise-delayed bit as per datasheet suggestion is always enabled.
  */

 /*
  * AD7291 registers definition
  */
 #define AD7291_COMMAND			0x00
 #define AD7291_VOLTAGE			0x01
 #define AD7291_T_SENSE			0x02
 #define AD7291_T_AVERAGE		0x03
 #define AD7291_DATA_HIGH(x)		((x) * 3 + 0x4)
 #define AD7291_DATA_LOW(x)		((x) * 3 + 0x5)
 #define AD7291_HYST(x)			((x) * 3 + 0x6)
 #define AD7291_VOLTAGE_ALERT_STATUS	0x1F
 #define AD7291_T_ALERT_STATUS		0x20

 #define AD7291_BITS			12
 #define AD7291_VOLTAGE_LIMIT_COUNT	8


 /*
  * AD7291 command
  */
 #define AD7291_AUTOCYCLE		BIT(0)
 #define AD7291_RESET			BIT(1)
 #define AD7291_ALERT_CLEAR		BIT(2)
 #define AD7291_ALERT_POLARITY		BIT(3)
 #define AD7291_EXT_REF			BIT(4)
 #define AD7291_NOISE_DELAY		BIT(5)
 #define AD7291_T_SENSE_MASK		BIT(7)
 #define AD7291_VOLTAGE_MASK		GENMASK(15, 8)
 #define AD7291_VOLTAGE_OFFSET		8

 /*
  * AD7291 value masks
  */
 #define AD7291_VALUE_MASK		GENMASK(11, 0)

 /*
  * AD7291 alert register bits
  */
 #define AD7291_T_LOW			BIT(0)
 #define AD7291_T_HIGH			BIT(1)
 #define AD7291_T_AVG_LOW		BIT(2)
 #define AD7291_T_AVG_HIGH		BIT(3)
 #define AD7291_V_LOW(x)			BIT((x) * 2)
 #define AD7291_V_HIGH(x)		BIT((x) * 2 + 1)


 struct ad7291_chip_info {
 	struct i2c_client	*client;
 	struct regulator	*reg;
 	u16			command;
 	u16			c_mask;	/* Active voltage channels for events */
 	struct mutex		state_lock;
 };

 static int ad7291_i2c_read(struct ad7291_chip_info *chip, u8 reg, u16 *data)
 {
 	struct i2c_client *client = chip->client;
 	int ret = 0;

 	ret = i2c_smbus_read_word_swapped(client, reg);
 	if (ret < 0) {
 		dev_err(&client->dev, "I2C read error\n");
 		return ret;
 	}

 	*data = ret;

 	return 0;
 }

 static int ad7291_i2c_write(struct ad7291_chip_info *chip, u8 reg, u16 data)
 {
 	return i2c_smbus_write_word_swapped(chip->client, reg, data);
 }

 static irqreturn_t ad7291_event_handler(int irq, void *private)
 {
 	struct iio_dev *indio_dev = private;
 	struct ad7291_chip_info *chip = iio_priv(private);
 	u16 t_status, v_status;
 	u16 command;
 	int i;
 	s64 timestamp = iio_get_time_ns(indio_dev);

 	if (ad7291_i2c_read(chip, AD7291_T_ALERT_STATUS, &t_status))
 		return IRQ_HANDLED;

 	if (ad7291_i2c_read(chip, AD7291_VOLTAGE_ALERT_STATUS, &v_status))
 		return IRQ_HANDLED;

 	if (!(t_status || v_status))
 		return IRQ_HANDLED;

 	command = chip->command | AD7291_ALERT_CLEAR;
 	ad7291_i2c_write(chip, AD7291_COMMAND, command);

 	command = chip->command & ~AD7291_ALERT_CLEAR;
 	ad7291_i2c_write(chip, AD7291_COMMAND, command);

 	/* For now treat t_sense and t_sense_average the same */
 	if ((t_status & AD7291_T_LOW) || (t_status & AD7291_T_AVG_LOW))
 		iio_push_event(indio_dev,
 			       IIO_UNMOD_EVENT_CODE(IIO_TEMP,
 						    0,
 						    IIO_EV_TYPE_THRESH,
 						    IIO_EV_DIR_FALLING),
 			       timestamp);
 	if ((t_status & AD7291_T_HIGH) || (t_status & AD7291_T_AVG_HIGH))
 		iio_push_event(indio_dev,
 			       IIO_UNMOD_EVENT_CODE(IIO_TEMP,
 						    0,
 						    IIO_EV_TYPE_THRESH,
 						    IIO_EV_DIR_RISING),
 			       timestamp);

 	for (i = 0; i < AD7291_VOLTAGE_LIMIT_COUNT; i++) {
 		if (v_status & AD7291_V_LOW(i))
 			iio_push_event(indio_dev,
 				       IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
 							    i,
 							    IIO_EV_TYPE_THRESH,
 							    IIO_EV_DIR_FALLING),
 				       timestamp);
 		if (v_status & AD7291_V_HIGH(i))
 			iio_push_event(indio_dev,
 				       IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
 							    i,
 							    IIO_EV_TYPE_THRESH,
 							    IIO_EV_DIR_RISING),
 				       timestamp);
 	}

 	return IRQ_HANDLED;
 }

 static unsigned int ad7291_threshold_reg(const struct iio_chan_spec *chan,
 					 enum iio_event_direction dir,
 					 enum iio_event_info info)
 {
 	unsigned int offset;

 	switch (chan->type) {
 	case IIO_VOLTAGE:
 		offset = chan->channel;
 		break;
 	case IIO_TEMP:
 		offset = AD7291_VOLTAGE_OFFSET;
 		break;
 	default:
 	    return 0;
 	}

 	switch (info) {
 	case IIO_EV_INFO_VALUE:
 		if (dir == IIO_EV_DIR_FALLING)
 			return AD7291_DATA_HIGH(offset);
 		else
 			return AD7291_DATA_LOW(offset);
 	case IIO_EV_INFO_HYSTERESIS:
 		return AD7291_HYST(offset);
 	default:
 		break;
 	}
 	return 0;
 }

 static int ad7291_read_event_value(struct iio_dev *indio_dev,
 				   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 ad7291_chip_info *chip = iio_priv(indio_dev);
 	int ret;
 	u16 uval;

 	ret = ad7291_i2c_read(chip, ad7291_threshold_reg(chan, dir, info),
 			      &uval);
 	if (ret < 0)
 		return ret;

 	if (info == IIO_EV_INFO_HYSTERESIS || chan->type == IIO_VOLTAGE)
 		*val = uval & AD7291_VALUE_MASK;

 	else
 		*val = sign_extend32(uval, 11);

 	return IIO_VAL_INT;
 }

 static int ad7291_write_event_value(struct iio_dev *indio_dev,
 				    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 ad7291_chip_info *chip = iio_priv(indio_dev);

 	if (info == IIO_EV_INFO_HYSTERESIS || chan->type == IIO_VOLTAGE) {
 		if (val > AD7291_VALUE_MASK || val < 0)
 			return -EINVAL;
 	} else {
 		if (val > 2047 || val < -2048)
 			return -EINVAL;
 	}

 	return ad7291_i2c_write(chip, ad7291_threshold_reg(chan, dir, info),
 				val);
 }

 static int ad7291_read_event_config(struct iio_dev *indio_dev,
 				    const struct iio_chan_spec *chan,
 				    enum iio_event_type type,
 				    enum iio_event_direction dir)
 {
 	struct ad7291_chip_info *chip = iio_priv(indio_dev);
 	/*
 	 * To be enabled the channel must simply be on. If any are enabled
 	 * we are in continuous sampling mode
 	 */

 	switch (chan->type) {
 	case IIO_VOLTAGE:
 		return !!(chip->c_mask & BIT(15 - chan->channel));
 	case IIO_TEMP:
 		/* always on */
 		return 1;
 	default:
 		return -EINVAL;
 	}

 }

 static int ad7291_write_event_config(struct iio_dev *indio_dev,
 				     const struct iio_chan_spec *chan,
 				     enum iio_event_type type,
 				     enum iio_event_direction dir,
 				     int state)
 {
 	int ret = 0;
 	struct ad7291_chip_info *chip = iio_priv(indio_dev);
 	unsigned int mask;
 	u16 regval;

 	mutex_lock(&chip->state_lock);
 	regval = chip->command;
 	/*
 	 * To be enabled the channel must simply be on. If any are enabled
 	 * use continuous sampling mode.
 	 * Possible to disable temp as well but that makes single read tricky.
 	 */

 	mask = BIT(15 - chan->channel);

 	switch (chan->type) {
 	case IIO_VOLTAGE:
 		if ((!state) && (chip->c_mask & mask))
 			chip->c_mask &= ~mask;
 		else if (state && (!(chip->c_mask & mask)))
 			chip->c_mask |= mask;
 		else
 			break;

 		regval &= ~AD7291_AUTOCYCLE;
 		regval |= chip->c_mask;
 		if (chip->c_mask) /* Enable autocycle? */
 			regval |= AD7291_AUTOCYCLE;

 		ret = ad7291_i2c_write(chip, AD7291_COMMAND, regval);
 		if (ret < 0)
 			goto error_ret;

 		chip->command = regval;
 		break;
 	default:
 		ret = -EINVAL;
 	}

 error_ret:
 	mutex_unlock(&chip->state_lock);
 	return ret;
 }

 static int ad7291_read_raw(struct iio_dev *indio_dev,
 			   struct iio_chan_spec const *chan,
 			   int *val,
 			   int *val2,
 			   long mask)
 {
 	int ret;
 	struct ad7291_chip_info *chip = iio_priv(indio_dev);
 	u16 regval;

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		switch (chan->type) {
 		case IIO_VOLTAGE:
 			mutex_lock(&chip->state_lock);
 			/* If in autocycle mode drop through */
 			if (chip->command & AD7291_AUTOCYCLE) {
 				mutex_unlock(&chip->state_lock);
 				return -EBUSY;
 			}
 			/* Enable this channel alone */
 			regval = chip->command & (~AD7291_VOLTAGE_MASK);
 			regval |= BIT(15 - chan->channel);
 			ret = ad7291_i2c_write(chip, AD7291_COMMAND, regval);
 			if (ret < 0) {
 				mutex_unlock(&chip->state_lock);
 				return ret;
 			}
 			/* Read voltage */
 			ret = i2c_smbus_read_word_swapped(chip->client,
 							  AD7291_VOLTAGE);
 			if (ret < 0) {
 				mutex_unlock(&chip->state_lock);
 				return ret;
 			}
 			*val = ret & AD7291_VALUE_MASK;
 			mutex_unlock(&chip->state_lock);
 			return IIO_VAL_INT;
 		case IIO_TEMP:
 			/* Assumes tsense bit of command register always set */
 			ret = i2c_smbus_read_word_swapped(chip->client,
 							  AD7291_T_SENSE);
 			if (ret < 0)
 				return ret;
 			*val = sign_extend32(ret, 11);
 			return IIO_VAL_INT;
 		default:
 			return -EINVAL;
 		}
 	case IIO_CHAN_INFO_AVERAGE_RAW:
 		ret = i2c_smbus_read_word_swapped(chip->client,
 						  AD7291_T_AVERAGE);
 			if (ret < 0)
 				return ret;
 			*val = sign_extend32(ret, 11);
 			return IIO_VAL_INT;
 	case IIO_CHAN_INFO_SCALE:
 		switch (chan->type) {
 		case IIO_VOLTAGE:
 			if (chip->reg) {
 				int vref;

 				vref = regulator_get_voltage(chip->reg);
 				if (vref < 0)
 					return vref;
 				*val = vref / 1000;
 			} else {
 				*val = 2500;
 			}
 			*val2 = AD7291_BITS;
 			return IIO_VAL_FRACTIONAL_LOG2;
 		case IIO_TEMP:
 			/*
 			 * One LSB of the ADC corresponds to 0.25 deg C.
 			 * The temperature reading is in 12-bit twos
 			 * complement format
 			 */
 			*val = 250;
 			return IIO_VAL_INT;
 		default:
 			return -EINVAL;
 		}
 	default:
 		return -EINVAL;
 	}
 }

 static const struct iio_event_spec ad7291_events[] = {
 	{
 		.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),
 	}, {
 		.type = IIO_EV_TYPE_THRESH,
 		.dir = IIO_EV_DIR_EITHER,
 		.mask_separate = BIT(IIO_EV_INFO_HYSTERESIS),
 	},
 };

 #define AD7291_VOLTAGE_CHAN(_chan)					\
 {									\
 	.type = IIO_VOLTAGE,						\
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),		\
 	.indexed = 1,							\
 	.channel = _chan,						\
 	.event_spec = ad7291_events,					\
 	.num_event_specs = ARRAY_SIZE(ad7291_events),			\
 }

 static const struct iio_chan_spec ad7291_channels[] = {
 	AD7291_VOLTAGE_CHAN(0),
 	AD7291_VOLTAGE_CHAN(1),
 	AD7291_VOLTAGE_CHAN(2),
 	AD7291_VOLTAGE_CHAN(3),
 	AD7291_VOLTAGE_CHAN(4),
 	AD7291_VOLTAGE_CHAN(5),
 	AD7291_VOLTAGE_CHAN(6),
 	AD7291_VOLTAGE_CHAN(7),
 	{
 		.type = IIO_TEMP,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 				BIT(IIO_CHAN_INFO_AVERAGE_RAW) |
 				BIT(IIO_CHAN_INFO_SCALE),
 		.indexed = 1,
 		.channel = 0,
 		.event_spec = ad7291_events,
 		.num_event_specs = ARRAY_SIZE(ad7291_events),
 	}
 };

 static const struct iio_info ad7291_info = {
 	.read_raw = &ad7291_read_raw,
 	.read_event_config = &ad7291_read_event_config,
 	.write_event_config = &ad7291_write_event_config,
 	.read_event_value = &ad7291_read_event_value,
 	.write_event_value = &ad7291_write_event_value,
 };

 static int ad7291_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
 	struct ad7291_platform_data *pdata = client->dev.platform_data;
 	struct ad7291_chip_info *chip;
 	struct iio_dev *indio_dev;
 	int ret;

 	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
 	if (!indio_dev)
 		return -ENOMEM;
 	chip = iio_priv(indio_dev);

 	if (pdata && pdata->use_external_ref) {
 		chip->reg = devm_regulator_get(&client->dev, "vref");
 		if (IS_ERR(chip->reg))
 			return PTR_ERR(chip->reg);

 		ret = regulator_enable(chip->reg);
 		if (ret)
 			return ret;
 	}

 	mutex_init(&chip->state_lock);
 	/* this is only used for device removal purposes */
 	i2c_set_clientdata(client, indio_dev);

 	chip->client = client;

 	chip->command = AD7291_NOISE_DELAY |
 			AD7291_T_SENSE_MASK | /* Tsense always enabled */
 			AD7291_ALERT_POLARITY; /* set irq polarity low level */

 	if (pdata && pdata->use_external_ref)
 		chip->command |= AD7291_EXT_REF;

 	indio_dev->name = id->name;
 	indio_dev->channels = ad7291_channels;
 	indio_dev->num_channels = ARRAY_SIZE(ad7291_channels);

 	indio_dev->dev.parent = &client->dev;
 	indio_dev->dev.of_node = client->dev.of_node;
 	indio_dev->info = &ad7291_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;

 	ret = ad7291_i2c_write(chip, AD7291_COMMAND, AD7291_RESET);
 	if (ret) {
 		ret = -EIO;
 		goto error_disable_reg;
 	}

 	ret = ad7291_i2c_write(chip, AD7291_COMMAND, chip->command);
 	if (ret) {
 		ret = -EIO;
 		goto error_disable_reg;
 	}

 	if (client->irq > 0) {
 		ret = request_threaded_irq(client->irq,
 					   NULL,
 					   &ad7291_event_handler,
 					   IRQF_TRIGGER_LOW | IRQF_ONESHOT,
 					   id->name,
 					   indio_dev);
 		if (ret)
 			goto error_disable_reg;
 	}

 	ret = iio_device_register(indio_dev);
 	if (ret)
 		goto error_unreg_irq;

 	return 0;

 error_unreg_irq:
 	if (client->irq)
 		free_irq(client->irq, indio_dev);
 error_disable_reg:
 	if (chip->reg)
 		regulator_disable(chip->reg);

 	return ret;
 }

 static int ad7291_remove(struct i2c_client *client)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
 	struct ad7291_chip_info *chip = iio_priv(indio_dev);

 	iio_device_unregister(indio_dev);

 	if (client->irq)
 		free_irq(client->irq, indio_dev);

 	if (chip->reg)
 		regulator_disable(chip->reg);

 	return 0;
 }

 static const struct i2c_device_id ad7291_id[] = {
 	{ "ad7291", 0 },
 	{}
 };

 MODULE_DEVICE_TABLE(i2c, ad7291_id);

 static struct i2c_driver ad7291_driver = {
 	.driver = {
 		.name = KBUILD_MODNAME,
 	},
 	.probe = ad7291_probe,
 	.remove = ad7291_remove,
 	.id_table = ad7291_id,
 };
 module_i2c_driver(ad7291_driver);

 MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
 MODULE_DESCRIPTION("Analog Devices AD7291 ADC driver");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* AD7291 8-Channel, I2C, 12-Bit SAR ADC with Temperature Sensor
	*
	* Copyright 2010-2011 Analog Devices Inc.
	*/

	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/i2c.h>
	#include <linux/interrupt.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/mutex.h>
	#include <linux/regulator/consumer.h>
	#include <linux/slab.h>
	#include <linux/sysfs.h>

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

	#include <linux/platform_data/ad7291.h>

	/*
	* Simplified handling
	*
	* If no events enabled - single polled channel read
	* If event enabled direct reads disable unless channel
	* is in the read mask.
	*
	* The noise-delayed bit as per datasheet suggestion is always enabled.
	*/

	/*
	* AD7291 registers definition
	*/
	#define AD7291_COMMAND 0x00
	#define AD7291_VOLTAGE 0x01
	#define AD7291_T_SENSE 0x02
	#define AD7291_T_AVERAGE 0x03
	#define AD7291_DATA_HIGH(x) ((x) * 3 + 0x4)
	#define AD7291_DATA_LOW(x) ((x) * 3 + 0x5)
	#define AD7291_HYST(x) ((x) * 3 + 0x6)
	#define AD7291_VOLTAGE_ALERT_STATUS 0x1F
	#define AD7291_T_ALERT_STATUS 0x20

	#define AD7291_BITS 12
	#define AD7291_VOLTAGE_LIMIT_COUNT 8


	/*
	* AD7291 command
	*/
	#define AD7291_AUTOCYCLE BIT(0)
	#define AD7291_RESET BIT(1)
	#define AD7291_ALERT_CLEAR BIT(2)
	#define AD7291_ALERT_POLARITY BIT(3)
	#define AD7291_EXT_REF BIT(4)
	#define AD7291_NOISE_DELAY BIT(5)
	#define AD7291_T_SENSE_MASK BIT(7)
	#define AD7291_VOLTAGE_MASK GENMASK(15, 8)
	#define AD7291_VOLTAGE_OFFSET 8

	/*
	* AD7291 value masks
	*/
	#define AD7291_VALUE_MASK GENMASK(11, 0)

	/*
	* AD7291 alert register bits
	*/
	#define AD7291_T_LOW BIT(0)
	#define AD7291_T_HIGH BIT(1)
	#define AD7291_T_AVG_LOW BIT(2)
	#define AD7291_T_AVG_HIGH BIT(3)
	#define AD7291_V_LOW(x) BIT((x) * 2)
	#define AD7291_V_HIGH(x) BIT((x) * 2 + 1)


	struct ad7291_chip_info {
	struct i2c_client *client;
	struct regulator *reg;
	u16 command;
	u16 c_mask; /* Active voltage channels for events */
	struct mutex state_lock;
	};

	static int ad7291_i2c_read(struct ad7291_chip_info chip, u8 reg, u16 data)
	{
	struct i2c_client *client = chip->client;
	int ret = 0;

	ret = i2c_smbus_read_word_swapped(client, reg);
	if (ret < 0) {
	dev_err(&client->dev, "I2C read error\n");
	return ret;
	}

	*data = ret;

	return 0;
	}

	static int ad7291_i2c_write(struct ad7291_chip_info *chip, u8 reg, u16 data)
	{
	return i2c_smbus_write_word_swapped(chip->client, reg, data);
	}

	static irqreturn_t ad7291_event_handler(int irq, void *private)
	{
	struct iio_dev *indio_dev = private;
	struct ad7291_chip_info *chip = iio_priv(private);
	u16 t_status, v_status;
	u16 command;
	int i;
	s64 timestamp = iio_get_time_ns(indio_dev);

	if (ad7291_i2c_read(chip, AD7291_T_ALERT_STATUS, &t_status))
	return IRQ_HANDLED;

	if (ad7291_i2c_read(chip, AD7291_VOLTAGE_ALERT_STATUS, &v_status))
	return IRQ_HANDLED;

	if (!(t_status \|\| v_status))
	return IRQ_HANDLED;

	command = chip->command \| AD7291_ALERT_CLEAR;
	ad7291_i2c_write(chip, AD7291_COMMAND, command);

	command = chip->command & ~AD7291_ALERT_CLEAR;
	ad7291_i2c_write(chip, AD7291_COMMAND, command);

	/* For now treat t_sense and t_sense_average the same */
	if ((t_status & AD7291_T_LOW) \|\| (t_status & AD7291_T_AVG_LOW))
	iio_push_event(indio_dev,
	IIO_UNMOD_EVENT_CODE(IIO_TEMP,
	0,
	IIO_EV_TYPE_THRESH,
	IIO_EV_DIR_FALLING),
	timestamp);
	if ((t_status & AD7291_T_HIGH) \|\| (t_status & AD7291_T_AVG_HIGH))
	iio_push_event(indio_dev,
	IIO_UNMOD_EVENT_CODE(IIO_TEMP,
	0,
	IIO_EV_TYPE_THRESH,
	IIO_EV_DIR_RISING),
	timestamp);

	for (i = 0; i < AD7291_VOLTAGE_LIMIT_COUNT; i++) {
	if (v_status & AD7291_V_LOW(i))
	iio_push_event(indio_dev,
	IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
	i,
	IIO_EV_TYPE_THRESH,
	IIO_EV_DIR_FALLING),
	timestamp);
	if (v_status & AD7291_V_HIGH(i))
	iio_push_event(indio_dev,
	IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
	i,
	IIO_EV_TYPE_THRESH,
	IIO_EV_DIR_RISING),
	timestamp);
	}

	return IRQ_HANDLED;
	}

	static unsigned int ad7291_threshold_reg(const struct iio_chan_spec *chan,
	enum iio_event_direction dir,
	enum iio_event_info info)
	{
	unsigned int offset;

	switch (chan->type) {
	case IIO_VOLTAGE:
	offset = chan->channel;
	break;
	case IIO_TEMP:
	offset = AD7291_VOLTAGE_OFFSET;
	break;
	default:
	return 0;
	}

	switch (info) {
	case IIO_EV_INFO_VALUE:
	if (dir == IIO_EV_DIR_FALLING)
	return AD7291_DATA_HIGH(offset);
	else
	return AD7291_DATA_LOW(offset);
	case IIO_EV_INFO_HYSTERESIS:
	return AD7291_HYST(offset);
	default:
	break;
	}
	return 0;
	}

	static int ad7291_read_event_value(struct iio_dev *indio_dev,
	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 ad7291_chip_info *chip = iio_priv(indio_dev);
	int ret;
	u16 uval;

	ret = ad7291_i2c_read(chip, ad7291_threshold_reg(chan, dir, info),
	&uval);
	if (ret < 0)
	return ret;

	if (info == IIO_EV_INFO_HYSTERESIS \|\| chan->type == IIO_VOLTAGE)
	*val = uval & AD7291_VALUE_MASK;

	else
	*val = sign_extend32(uval, 11);

	return IIO_VAL_INT;
	}

	static int ad7291_write_event_value(struct iio_dev *indio_dev,
	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 ad7291_chip_info *chip = iio_priv(indio_dev);

	if (info == IIO_EV_INFO_HYSTERESIS \|\| chan->type == IIO_VOLTAGE) {
	if (val > AD7291_VALUE_MASK \|\| val < 0)
	return -EINVAL;
	} else {
	if (val > 2047 \|\| val < -2048)
	return -EINVAL;
	}

	return ad7291_i2c_write(chip, ad7291_threshold_reg(chan, dir, info),
	val);
	}

	static int ad7291_read_event_config(struct iio_dev *indio_dev,
	const struct iio_chan_spec *chan,
	enum iio_event_type type,
	enum iio_event_direction dir)
	{
	struct ad7291_chip_info *chip = iio_priv(indio_dev);
	/*
	* To be enabled the channel must simply be on. If any are enabled
	* we are in continuous sampling mode
	*/

	switch (chan->type) {
	case IIO_VOLTAGE:
	return !!(chip->c_mask & BIT(15 - chan->channel));
	case IIO_TEMP:
	/* always on */
	return 1;
	default:
	return -EINVAL;
	}

	}

	static int ad7291_write_event_config(struct iio_dev *indio_dev,
	const struct iio_chan_spec *chan,
	enum iio_event_type type,
	enum iio_event_direction dir,
	int state)
	{
	int ret = 0;
	struct ad7291_chip_info *chip = iio_priv(indio_dev);
	unsigned int mask;
	u16 regval;

	mutex_lock(&chip->state_lock);
	regval = chip->command;
	/*
	* To be enabled the channel must simply be on. If any are enabled
	* use continuous sampling mode.
	* Possible to disable temp as well but that makes single read tricky.
	*/

	mask = BIT(15 - chan->channel);

	switch (chan->type) {
	case IIO_VOLTAGE:
	if ((!state) && (chip->c_mask & mask))
	chip->c_mask &= ~mask;
	else if (state && (!(chip->c_mask & mask)))
	chip->c_mask \|= mask;
	else
	break;

	regval &= ~AD7291_AUTOCYCLE;
	regval \|= chip->c_mask;
	if (chip->c_mask) /* Enable autocycle? */
	regval \|= AD7291_AUTOCYCLE;

	ret = ad7291_i2c_write(chip, AD7291_COMMAND, regval);
	if (ret < 0)
	goto error_ret;

	chip->command = regval;
	break;
	default:
	ret = -EINVAL;
	}

	error_ret:
	mutex_unlock(&chip->state_lock);
	return ret;
	}

	static int ad7291_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const *chan,
	int *val,
	int *val2,
	long mask)
	{
	int ret;
	struct ad7291_chip_info *chip = iio_priv(indio_dev);
	u16 regval;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	switch (chan->type) {
	case IIO_VOLTAGE:
	mutex_lock(&chip->state_lock);
	/* If in autocycle mode drop through */
	if (chip->command & AD7291_AUTOCYCLE) {
	mutex_unlock(&chip->state_lock);
	return -EBUSY;
	}
	/* Enable this channel alone */
	regval = chip->command & (~AD7291_VOLTAGE_MASK);
	regval \|= BIT(15 - chan->channel);
	ret = ad7291_i2c_write(chip, AD7291_COMMAND, regval);
	if (ret < 0) {
	mutex_unlock(&chip->state_lock);
	return ret;
	}
	/* Read voltage */
	ret = i2c_smbus_read_word_swapped(chip->client,
	AD7291_VOLTAGE);
	if (ret < 0) {
	mutex_unlock(&chip->state_lock);
	return ret;
	}
	*val = ret & AD7291_VALUE_MASK;
	mutex_unlock(&chip->state_lock);
	return IIO_VAL_INT;
	case IIO_TEMP:
	/* Assumes tsense bit of command register always set */
	ret = i2c_smbus_read_word_swapped(chip->client,
	AD7291_T_SENSE);
	if (ret < 0)
	return ret;
	*val = sign_extend32(ret, 11);
	return IIO_VAL_INT;
	default:
	return -EINVAL;
	}
	case IIO_CHAN_INFO_AVERAGE_RAW:
	ret = i2c_smbus_read_word_swapped(chip->client,
	AD7291_T_AVERAGE);
	if (ret < 0)
	return ret;
	*val = sign_extend32(ret, 11);
	return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
	switch (chan->type) {
	case IIO_VOLTAGE:
	if (chip->reg) {
	int vref;

	vref = regulator_get_voltage(chip->reg);
	if (vref < 0)
	return vref;
	*val = vref / 1000;
	} else {
	*val = 2500;
	}
	*val2 = AD7291_BITS;
	return IIO_VAL_FRACTIONAL_LOG2;
	case IIO_TEMP:
	/*
	* One LSB of the ADC corresponds to 0.25 deg C.
	* The temperature reading is in 12-bit twos
	* complement format
	*/
	*val = 250;
	return IIO_VAL_INT;
	default:
	return -EINVAL;
	}
	default:
	return -EINVAL;
	}
	}

	static const struct iio_event_spec ad7291_events[] = {
	{
	.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),
	}, {
	.type = IIO_EV_TYPE_THRESH,
	.dir = IIO_EV_DIR_EITHER,
	.mask_separate = BIT(IIO_EV_INFO_HYSTERESIS),
	},
	};

	#define AD7291_VOLTAGE_CHAN(_chan) \
	{ \
	.type = IIO_VOLTAGE, \
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
	.indexed = 1, \
	.channel = _chan, \
	.event_spec = ad7291_events, \
	.num_event_specs = ARRAY_SIZE(ad7291_events), \
	}

	static const struct iio_chan_spec ad7291_channels[] = {
	AD7291_VOLTAGE_CHAN(0),
	AD7291_VOLTAGE_CHAN(1),
	AD7291_VOLTAGE_CHAN(2),
	AD7291_VOLTAGE_CHAN(3),
	AD7291_VOLTAGE_CHAN(4),
	AD7291_VOLTAGE_CHAN(5),
	AD7291_VOLTAGE_CHAN(6),
	AD7291_VOLTAGE_CHAN(7),
	{
	.type = IIO_TEMP,
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \|
	BIT(IIO_CHAN_INFO_AVERAGE_RAW) \|
	BIT(IIO_CHAN_INFO_SCALE),
	.indexed = 1,
	.channel = 0,
	.event_spec = ad7291_events,
	.num_event_specs = ARRAY_SIZE(ad7291_events),
	}
	};

	static const struct iio_info ad7291_info = {
	.read_raw = &ad7291_read_raw,
	.read_event_config = &ad7291_read_event_config,
	.write_event_config = &ad7291_write_event_config,
	.read_event_value = &ad7291_read_event_value,
	.write_event_value = &ad7291_write_event_value,
	};

	static int ad7291_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct ad7291_platform_data *pdata = client->dev.platform_data;
	struct ad7291_chip_info *chip;
	struct iio_dev *indio_dev;
	int ret;

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*chip));
	if (!indio_dev)
	return -ENOMEM;
	chip = iio_priv(indio_dev);

	if (pdata && pdata->use_external_ref) {
	chip->reg = devm_regulator_get(&client->dev, "vref");
	if (IS_ERR(chip->reg))
	return PTR_ERR(chip->reg);

	ret = regulator_enable(chip->reg);
	if (ret)
	return ret;
	}

	mutex_init(&chip->state_lock);
	/* this is only used for device removal purposes */
	i2c_set_clientdata(client, indio_dev);

	chip->client = client;

	chip->command = AD7291_NOISE_DELAY \|
	AD7291_T_SENSE_MASK \| /* Tsense always enabled */
	AD7291_ALERT_POLARITY; /* set irq polarity low level */

	if (pdata && pdata->use_external_ref)
	chip->command \|= AD7291_EXT_REF;

	indio_dev->name = id->name;
	indio_dev->channels = ad7291_channels;
	indio_dev->num_channels = ARRAY_SIZE(ad7291_channels);

	indio_dev->dev.parent = &client->dev;
	indio_dev->dev.of_node = client->dev.of_node;
	indio_dev->info = &ad7291_info;
	indio_dev->modes = INDIO_DIRECT_MODE;

	ret = ad7291_i2c_write(chip, AD7291_COMMAND, AD7291_RESET);
	if (ret) {
	ret = -EIO;
	goto error_disable_reg;
	}

	ret = ad7291_i2c_write(chip, AD7291_COMMAND, chip->command);
	if (ret) {
	ret = -EIO;
	goto error_disable_reg;
	}

	if (client->irq > 0) {
	ret = request_threaded_irq(client->irq,
	NULL,
	&ad7291_event_handler,
	IRQF_TRIGGER_LOW \| IRQF_ONESHOT,
	id->name,
	indio_dev);
	if (ret)
	goto error_disable_reg;
	}

	ret = iio_device_register(indio_dev);
	if (ret)
	goto error_unreg_irq;

	return 0;

	error_unreg_irq:
	if (client->irq)
	free_irq(client->irq, indio_dev);
	error_disable_reg:
	if (chip->reg)
	regulator_disable(chip->reg);

	return ret;
	}

	static int ad7291_remove(struct i2c_client *client)
	{
	struct iio_dev *indio_dev = i2c_get_clientdata(client);
	struct ad7291_chip_info *chip = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);

	if (client->irq)
	free_irq(client->irq, indio_dev);

	if (chip->reg)
	regulator_disable(chip->reg);

	return 0;
	}

	static const struct i2c_device_id ad7291_id[] = {
	{ "ad7291", 0 },
	{}
	};

	MODULE_DEVICE_TABLE(i2c, ad7291_id);

	static struct i2c_driver ad7291_driver = {
	.driver = {
	.name = KBUILD_MODNAME,
	},
	.probe = ad7291_probe,
	.remove = ad7291_remove,
	.id_table = ad7291_id,
	};
	module_i2c_driver(ad7291_driver);

	MODULE_AUTHOR("Sonic Zhang <sonic.zhang@analog.com>");
	MODULE_DESCRIPTION("Analog Devices AD7291 ADC driver");
	MODULE_LICENSE("GPL v2");