text: /*
   * AD7291 8-Channel, I2C, 12-Bit SAR ADC with Temperature Sensor
   *
   * Copyright 2010-2011 Analog Devices Inc.
   *
   * Licensed under the GPL-2 or later.
   */
  
  #include <linux/interrupt.h>
  #include <linux/device.h>
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/sysfs.h>
  #include <linux/i2c.h>
  #include <linux/module.h>
  #include <linux/mutex.h>
  #include <linux/regulator/consumer.h>
  #include <linux/err.h>
  
  #include <linux/iio/iio.h>
  #include <linux/iio/sysfs.h>
  #include <linux/iio/events.h>
  
  #include "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_VOLTAGE_LIMIT_COUNT	8
  
  
  /*
   * AD7291 command
   */
  #define AD7291_AUTOCYCLE		(1 << 0)
  #define AD7291_RESET			(1 << 1)
  #define AD7291_ALERT_CLEAR		(1 << 2)
  #define AD7291_ALERT_POLARITY		(1 << 3)
  #define AD7291_EXT_REF			(1 << 4)
  #define AD7291_NOISE_DELAY		(1 << 5)
  #define AD7291_T_SENSE_MASK		(1 << 7)
  #define AD7291_VOLTAGE_MASK		0xFF00
  #define AD7291_VOLTAGE_OFFSET		0x8
  
  /*
   * AD7291 value masks
   */
  #define AD7291_CHANNEL_MASK		0xF000
  #define AD7291_BITS			12
  #define AD7291_VALUE_MASK		0xFFF
  #define AD7291_T_VALUE_SIGN		0x400
  #define AD7291_T_VALUE_FLOAT_OFFSET	2
  #define AD7291_T_VALUE_FLOAT_MASK	0x2
  
  #define AD7291_BITS			12
  
  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();
  
  	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 & (1 << 0)) || (t_status & (1 << 2)))
  		iio_push_event(indio_dev,
  			       IIO_UNMOD_EVENT_CODE(IIO_TEMP,
  						    0,
  						    IIO_EV_TYPE_THRESH,
  						    IIO_EV_DIR_FALLING),
  			       timestamp);
  	if ((t_status & (1 << 1)) || (t_status & (1 << 3)))
  		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*2; i += 2) {
  		if (v_status & (1 << i))
  			iio_push_event(indio_dev,
  				       IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
  							    i/2,
  							    IIO_EV_TYPE_THRESH,
  							    IIO_EV_DIR_FALLING),
  				       timestamp);
  		if (v_status & (1 << (i + 1)))
  			iio_push_event(indio_dev,
  				       IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE,
  							    i/2,
  							    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 = 8;
  		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:
  		if (chip->c_mask & (1 << (15 - chan->channel)))
  			return 1;
  		else
  			return 0;
  	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 |= 1 << (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,
  	.driver_module = THIS_MODULE,
  };
  
  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 = 0;
  
  	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 ret;
  
  		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->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");
  