drivers/iio/chemical/vz89x.c - kernel/quantenna - Git at Google

 /*
  * vz89x.c - Support for SGX Sensortech MiCS VZ89X VOC sensors
  *
  * Copyright (C) 2015 Matt Ranostay <mranostay@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * 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/module.h>
 #include <linux/mutex.h>
 #include <linux/init.h>
 #include <linux/i2c.h>

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

 #define VZ89X_REG_MEASUREMENT		0x09
 #define VZ89X_REG_MEASUREMENT_SIZE	6

 #define VZ89X_VOC_CO2_IDX		0
 #define VZ89X_VOC_SHORT_IDX		1
 #define VZ89X_VOC_TVOC_IDX		2
 #define VZ89X_VOC_RESISTANCE_IDX	3

 struct vz89x_data {
 	struct i2c_client *client;
 	struct mutex lock;
 	int (*xfer)(struct vz89x_data *data, u8 cmd);

 	unsigned long last_update;
 	u8 buffer[VZ89X_REG_MEASUREMENT_SIZE];
 };

 static const struct iio_chan_spec vz89x_channels[] = {
 	{
 		.type = IIO_CONCENTRATION,
 		.channel2 = IIO_MOD_CO2,
 		.modified = 1,
 		.info_mask_separate =
 			BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
 		.address = VZ89X_VOC_CO2_IDX,
 	},
 	{
 		.type = IIO_CONCENTRATION,
 		.channel2 = IIO_MOD_VOC,
 		.modified = 1,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 		.address = VZ89X_VOC_SHORT_IDX,
 		.extend_name = "short",
 	},
 	{
 		.type = IIO_CONCENTRATION,
 		.channel2 = IIO_MOD_VOC,
 		.modified = 1,
 		.info_mask_separate =
 			BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
 		.address = VZ89X_VOC_TVOC_IDX,
 	},
 	{
 		.type = IIO_RESISTANCE,
 		.info_mask_separate =
 			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
 		.address = VZ89X_VOC_RESISTANCE_IDX,
 	},
 };

 static IIO_CONST_ATTR(in_concentration_co2_scale, "0.00000698689");
 static IIO_CONST_ATTR(in_concentration_voc_scale, "0.00000000436681223");

 static struct attribute *vz89x_attributes[] = {
 	&iio_const_attr_in_concentration_co2_scale.dev_attr.attr,
 	&iio_const_attr_in_concentration_voc_scale.dev_attr.attr,
 	NULL,
 };

 static const struct attribute_group vz89x_attrs_group = {
 	.attrs = vz89x_attributes,
 };

 /*
  * Chipset sometime updates in the middle of a reading causing it to reset the
  * data pointer, and causing invalid reading of previous data.
  * We can check for this by reading MSB of the resistance reading that is
  * always zero, and by also confirming the VOC_short isn't zero.
  */

 static int vz89x_measurement_is_valid(struct vz89x_data *data)
 {
 	if (data->buffer[VZ89X_VOC_SHORT_IDX] == 0)
 		return 1;

 	return !!(data->buffer[VZ89X_REG_MEASUREMENT_SIZE - 1] > 0);
 }

 static int vz89x_i2c_xfer(struct vz89x_data *data, u8 cmd)
 {
 	struct i2c_client *client = data->client;
 	struct i2c_msg msg[2];
 	int ret;
 	u8 buf[3] = { cmd, 0, 0};

 	msg[0].addr = client->addr;
 	msg[0].flags = client->flags;
 	msg[0].len = 3;
 	msg[0].buf  = (char *) &buf;

 	msg[1].addr = client->addr;
 	msg[1].flags = client->flags | I2C_M_RD;
 	msg[1].len = VZ89X_REG_MEASUREMENT_SIZE;
 	msg[1].buf = (char *) &data->buffer;

 	ret = i2c_transfer(client->adapter, msg, 2);

 	return (ret == 2) ? 0 : ret;
 }

 static int vz89x_smbus_xfer(struct vz89x_data *data, u8 cmd)
 {
 	struct i2c_client *client = data->client;
 	int ret;
 	int i;

 	ret = i2c_smbus_write_word_data(client, cmd, 0);
 	if (ret < 0)
 		return ret;

 	for (i = 0; i < VZ89X_REG_MEASUREMENT_SIZE; i++) {
 		ret = i2c_smbus_read_byte(client);
 		if (ret < 0)
 			return ret;
 		data->buffer[i] = ret;
 	}

 	return 0;
 }

 static int vz89x_get_measurement(struct vz89x_data *data)
 {
 	int ret;

 	/* sensor can only be polled once a second max per datasheet */
 	if (!time_after(jiffies, data->last_update + HZ))
 		return 0;

 	ret = data->xfer(data, VZ89X_REG_MEASUREMENT);
 	if (ret < 0)
 		return ret;

 	ret = vz89x_measurement_is_valid(data);
 	if (ret)
 		return -EAGAIN;

 	data->last_update = jiffies;

 	return 0;
 }

 static int vz89x_get_resistance_reading(struct vz89x_data *data)
 {
 	u8 *buf = &data->buffer[VZ89X_VOC_RESISTANCE_IDX];

 	return buf[0] | (buf[1] << 8);
 }

 static int vz89x_read_raw(struct iio_dev *indio_dev,
 			  struct iio_chan_spec const *chan, int *val,
 			  int *val2, long mask)
 {
 	struct vz89x_data *data = iio_priv(indio_dev);
 	int ret = -EINVAL;

 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		mutex_lock(&data->lock);
 		ret = vz89x_get_measurement(data);
 		mutex_unlock(&data->lock);

 		if (ret)
 			return ret;

 		switch (chan->address) {
 		case VZ89X_VOC_CO2_IDX:
 		case VZ89X_VOC_SHORT_IDX:
 		case VZ89X_VOC_TVOC_IDX:
 			*val = data->buffer[chan->address];
 			return IIO_VAL_INT;
 		case VZ89X_VOC_RESISTANCE_IDX:
 			*val = vz89x_get_resistance_reading(data);
 			return IIO_VAL_INT;
 		default:
 			return -EINVAL;
 		}
 		break;
 	case IIO_CHAN_INFO_SCALE:
 		switch (chan->type) {
 		case IIO_RESISTANCE:
 			*val = 10;
 			return IIO_VAL_INT;
 		default:
 			return -EINVAL;
 		}
 		break;
 	case IIO_CHAN_INFO_OFFSET:
 		switch (chan->address) {
 		case VZ89X_VOC_CO2_IDX:
 			*val = 44;
 			*val2 = 250000;
 			return IIO_VAL_INT_PLUS_MICRO;
 		case VZ89X_VOC_TVOC_IDX:
 			*val = -13;
 			return IIO_VAL_INT;
 		default:
 			return -EINVAL;
 		}
 	}

 	return ret;
 }

 static const struct iio_info vz89x_info = {
 	.attrs		= &vz89x_attrs_group,
 	.read_raw	= vz89x_read_raw,
 	.driver_module	= THIS_MODULE,
 };

 static int vz89x_probe(struct i2c_client *client,
 		       const struct i2c_device_id *id)
 {
 	struct iio_dev *indio_dev;
 	struct vz89x_data *data;

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

 	if (i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 		data->xfer = vz89x_i2c_xfer;
 	else if (i2c_check_functionality(client->adapter,
 				I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BYTE))
 		data->xfer = vz89x_smbus_xfer;
 	else
 		return -EOPNOTSUPP;

 	i2c_set_clientdata(client, indio_dev);
 	data->client = client;
 	data->last_update = jiffies - HZ;
 	mutex_init(&data->lock);

 	indio_dev->dev.parent = &client->dev;
 	indio_dev->info = &vz89x_info,
 	indio_dev->name = dev_name(&client->dev);
 	indio_dev->modes = INDIO_DIRECT_MODE;

 	indio_dev->channels = vz89x_channels;
 	indio_dev->num_channels = ARRAY_SIZE(vz89x_channels);

 	return devm_iio_device_register(&client->dev, indio_dev);
 }

 static const struct i2c_device_id vz89x_id[] = {
 	{ "vz89x", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, vz89x_id);

 static const struct of_device_id vz89x_dt_ids[] = {
 	{ .compatible = "sgx,vz89x" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, vz89x_dt_ids);

 static struct i2c_driver vz89x_driver = {
 	.driver = {
 		.name	= "vz89x",
 		.of_match_table = of_match_ptr(vz89x_dt_ids),
 	},
 	.probe = vz89x_probe,
 	.id_table = vz89x_id,
 };
 module_i2c_driver(vz89x_driver);

 MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
 MODULE_DESCRIPTION("SGX Sensortech MiCS VZ89X VOC sensors");
 MODULE_LICENSE("GPL v2");
	/*
	* vz89x.c - Support for SGX Sensortech MiCS VZ89X VOC sensors
	*
	* Copyright (C) 2015 Matt Ranostay <mranostay@gmail.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* 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/module.h>
	#include <linux/mutex.h>
	#include <linux/init.h>
	#include <linux/i2c.h>

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

	#define VZ89X_REG_MEASUREMENT 0x09
	#define VZ89X_REG_MEASUREMENT_SIZE 6

	#define VZ89X_VOC_CO2_IDX 0
	#define VZ89X_VOC_SHORT_IDX 1
	#define VZ89X_VOC_TVOC_IDX 2
	#define VZ89X_VOC_RESISTANCE_IDX 3

	struct vz89x_data {
	struct i2c_client *client;
	struct mutex lock;
	int (xfer)(struct vz89x_data data, u8 cmd);

	unsigned long last_update;
	u8 buffer[VZ89X_REG_MEASUREMENT_SIZE];
	};

	static const struct iio_chan_spec vz89x_channels[] = {
	{
	.type = IIO_CONCENTRATION,
	.channel2 = IIO_MOD_CO2,
	.modified = 1,
	.info_mask_separate =
	BIT(IIO_CHAN_INFO_OFFSET) \| BIT(IIO_CHAN_INFO_RAW),
	.address = VZ89X_VOC_CO2_IDX,
	},
	{
	.type = IIO_CONCENTRATION,
	.channel2 = IIO_MOD_VOC,
	.modified = 1,
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
	.address = VZ89X_VOC_SHORT_IDX,
	.extend_name = "short",
	},
	{
	.type = IIO_CONCENTRATION,
	.channel2 = IIO_MOD_VOC,
	.modified = 1,
	.info_mask_separate =
	BIT(IIO_CHAN_INFO_OFFSET) \| BIT(IIO_CHAN_INFO_RAW),
	.address = VZ89X_VOC_TVOC_IDX,
	},
	{
	.type = IIO_RESISTANCE,
	.info_mask_separate =
	BIT(IIO_CHAN_INFO_RAW) \| BIT(IIO_CHAN_INFO_SCALE),
	.address = VZ89X_VOC_RESISTANCE_IDX,
	},
	};

	static IIO_CONST_ATTR(in_concentration_co2_scale, "0.00000698689");
	static IIO_CONST_ATTR(in_concentration_voc_scale, "0.00000000436681223");

	static struct attribute *vz89x_attributes[] = {
	&iio_const_attr_in_concentration_co2_scale.dev_attr.attr,
	&iio_const_attr_in_concentration_voc_scale.dev_attr.attr,
	NULL,
	};

	static const struct attribute_group vz89x_attrs_group = {
	.attrs = vz89x_attributes,
	};

	/*
	* Chipset sometime updates in the middle of a reading causing it to reset the
	* data pointer, and causing invalid reading of previous data.
	* We can check for this by reading MSB of the resistance reading that is
	* always zero, and by also confirming the VOC_short isn't zero.
	*/

	static int vz89x_measurement_is_valid(struct vz89x_data *data)
	{
	if (data->buffer[VZ89X_VOC_SHORT_IDX] == 0)
	return 1;

	return !!(data->buffer[VZ89X_REG_MEASUREMENT_SIZE - 1] > 0);
	}

	static int vz89x_i2c_xfer(struct vz89x_data *data, u8 cmd)
	{
	struct i2c_client *client = data->client;
	struct i2c_msg msg[2];
	int ret;
	u8 buf[3] = { cmd, 0, 0};

	msg[0].addr = client->addr;
	msg[0].flags = client->flags;
	msg[0].len = 3;
	msg[0].buf = (char *) &buf;

	msg[1].addr = client->addr;
	msg[1].flags = client->flags \| I2C_M_RD;
	msg[1].len = VZ89X_REG_MEASUREMENT_SIZE;
	msg[1].buf = (char *) &data->buffer;

	ret = i2c_transfer(client->adapter, msg, 2);

	return (ret == 2) ? 0 : ret;
	}

	static int vz89x_smbus_xfer(struct vz89x_data *data, u8 cmd)
	{
	struct i2c_client *client = data->client;
	int ret;
	int i;

	ret = i2c_smbus_write_word_data(client, cmd, 0);
	if (ret < 0)
	return ret;

	for (i = 0; i < VZ89X_REG_MEASUREMENT_SIZE; i++) {
	ret = i2c_smbus_read_byte(client);
	if (ret < 0)
	return ret;
	data->buffer[i] = ret;
	}

	return 0;
	}

	static int vz89x_get_measurement(struct vz89x_data *data)
	{
	int ret;

	/* sensor can only be polled once a second max per datasheet */
	if (!time_after(jiffies, data->last_update + HZ))
	return 0;

	ret = data->xfer(data, VZ89X_REG_MEASUREMENT);
	if (ret < 0)
	return ret;

	ret = vz89x_measurement_is_valid(data);
	if (ret)
	return -EAGAIN;

	data->last_update = jiffies;

	return 0;
	}

	static int vz89x_get_resistance_reading(struct vz89x_data *data)
	{
	u8 *buf = &data->buffer[VZ89X_VOC_RESISTANCE_IDX];

	return buf[0] \| (buf[1] << 8);
	}

	static int vz89x_read_raw(struct iio_dev *indio_dev,
	struct iio_chan_spec const chan, int val,
	int *val2, long mask)
	{
	struct vz89x_data *data = iio_priv(indio_dev);
	int ret = -EINVAL;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
	mutex_lock(&data->lock);
	ret = vz89x_get_measurement(data);
	mutex_unlock(&data->lock);

	if (ret)
	return ret;

	switch (chan->address) {
	case VZ89X_VOC_CO2_IDX:
	case VZ89X_VOC_SHORT_IDX:
	case VZ89X_VOC_TVOC_IDX:
	*val = data->buffer[chan->address];
	return IIO_VAL_INT;
	case VZ89X_VOC_RESISTANCE_IDX:
	*val = vz89x_get_resistance_reading(data);
	return IIO_VAL_INT;
	default:
	return -EINVAL;
	}
	break;
	case IIO_CHAN_INFO_SCALE:
	switch (chan->type) {
	case IIO_RESISTANCE:
	*val = 10;
	return IIO_VAL_INT;
	default:
	return -EINVAL;
	}
	break;
	case IIO_CHAN_INFO_OFFSET:
	switch (chan->address) {
	case VZ89X_VOC_CO2_IDX:
	*val = 44;
	*val2 = 250000;
	return IIO_VAL_INT_PLUS_MICRO;
	case VZ89X_VOC_TVOC_IDX:
	*val = -13;
	return IIO_VAL_INT;
	default:
	return -EINVAL;
	}
	}

	return ret;
	}

	static const struct iio_info vz89x_info = {
	.attrs = &vz89x_attrs_group,
	.read_raw = vz89x_read_raw,
	.driver_module = THIS_MODULE,
	};

	static int vz89x_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct iio_dev *indio_dev;
	struct vz89x_data *data;

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

	if (i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
	data->xfer = vz89x_i2c_xfer;
	else if (i2c_check_functionality(client->adapter,
	I2C_FUNC_SMBUS_WORD_DATA \| I2C_FUNC_SMBUS_BYTE))
	data->xfer = vz89x_smbus_xfer;
	else
	return -EOPNOTSUPP;

	i2c_set_clientdata(client, indio_dev);
	data->client = client;
	data->last_update = jiffies - HZ;
	mutex_init(&data->lock);

	indio_dev->dev.parent = &client->dev;
	indio_dev->info = &vz89x_info,
	indio_dev->name = dev_name(&client->dev);
	indio_dev->modes = INDIO_DIRECT_MODE;

	indio_dev->channels = vz89x_channels;
	indio_dev->num_channels = ARRAY_SIZE(vz89x_channels);

	return devm_iio_device_register(&client->dev, indio_dev);
	}

	static const struct i2c_device_id vz89x_id[] = {
	{ "vz89x", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, vz89x_id);

	static const struct of_device_id vz89x_dt_ids[] = {
	{ .compatible = "sgx,vz89x" },
	{ }
	};
	MODULE_DEVICE_TABLE(of, vz89x_dt_ids);

	static struct i2c_driver vz89x_driver = {
	.driver = {
	.name = "vz89x",
	.of_match_table = of_match_ptr(vz89x_dt_ids),
	},
	.probe = vz89x_probe,
	.id_table = vz89x_id,
	};
	module_i2c_driver(vz89x_driver);

	MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
	MODULE_DESCRIPTION("SGX Sensortech MiCS VZ89X VOC sensors");
	MODULE_LICENSE("GPL v2");