/*
* 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;
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_get_measurement(struct vz89x_data *data)
{
int ret;
int i;
/* sensor can only be polled once a second max per datasheet */
if (!time_after(jiffies, data->last_update + HZ))
return 0;
ret = i2c_smbus_write_word_data(data->client,
VZ89X_REG_MEASUREMENT, 0);
if (ret < 0)
return ret;
for (i = 0; i < VZ89X_REG_MEASUREMENT_SIZE; i++) {
ret = i2c_smbus_read_byte(data->client);
if (ret < 0)
return ret;
data->buffer[i] = 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;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA |
I2C_FUNC_SMBUS_BYTE))
return -ENODEV;
indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
data = iio_priv(indio_dev);
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");