2 * vz89x.c - Support for SGX Sensortech MiCS VZ89X VOC sensors
4 * Copyright (C) 2015 Matt Ranostay <mranostay@gmail.com>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
18 #include <linux/module.h>
19 #include <linux/mutex.h>
20 #include <linux/init.h>
21 #include <linux/i2c.h>
23 #include <linux/iio/iio.h>
24 #include <linux/iio/sysfs.h>
26 #define VZ89X_REG_MEASUREMENT 0x09
27 #define VZ89X_REG_MEASUREMENT_SIZE 6
29 #define VZ89X_VOC_CO2_IDX 0
30 #define VZ89X_VOC_SHORT_IDX 1
31 #define VZ89X_VOC_TVOC_IDX 2
32 #define VZ89X_VOC_RESISTANCE_IDX 3
35 struct i2c_client *client;
37 unsigned long last_update;
39 u8 buffer[VZ89X_REG_MEASUREMENT_SIZE];
42 static const struct iio_chan_spec vz89x_channels[] = {
44 .type = IIO_CONCENTRATION,
45 .channel2 = IIO_MOD_CO2,
48 BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
49 .address = VZ89X_VOC_CO2_IDX,
52 .type = IIO_CONCENTRATION,
53 .channel2 = IIO_MOD_VOC,
55 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
56 .address = VZ89X_VOC_SHORT_IDX,
57 .extend_name = "short",
60 .type = IIO_CONCENTRATION,
61 .channel2 = IIO_MOD_VOC,
64 BIT(IIO_CHAN_INFO_OFFSET) | BIT(IIO_CHAN_INFO_RAW),
65 .address = VZ89X_VOC_TVOC_IDX,
68 .type = IIO_RESISTANCE,
70 BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
71 .address = VZ89X_VOC_RESISTANCE_IDX,
75 static IIO_CONST_ATTR(in_concentration_co2_scale, "0.00000698689");
76 static IIO_CONST_ATTR(in_concentration_voc_scale, "0.00000000436681223");
78 static struct attribute *vz89x_attributes[] = {
79 &iio_const_attr_in_concentration_co2_scale.dev_attr.attr,
80 &iio_const_attr_in_concentration_voc_scale.dev_attr.attr,
84 static const struct attribute_group vz89x_attrs_group = {
85 .attrs = vz89x_attributes,
89 * Chipset sometime updates in the middle of a reading causing it to reset the
90 * data pointer, and causing invalid reading of previous data.
91 * We can check for this by reading MSB of the resistance reading that is
92 * always zero, and by also confirming the VOC_short isn't zero.
95 static int vz89x_measurement_is_valid(struct vz89x_data *data)
97 if (data->buffer[VZ89X_VOC_SHORT_IDX] == 0)
100 return !!(data->buffer[VZ89X_REG_MEASUREMENT_SIZE - 1] > 0);
103 static int vz89x_get_measurement(struct vz89x_data *data)
108 /* sensor can only be polled once a second max per datasheet */
109 if (!time_after(jiffies, data->last_update + HZ))
112 ret = i2c_smbus_write_word_data(data->client,
113 VZ89X_REG_MEASUREMENT, 0);
117 for (i = 0; i < VZ89X_REG_MEASUREMENT_SIZE; i++) {
118 ret = i2c_smbus_read_byte(data->client);
121 data->buffer[i] = ret;
124 ret = vz89x_measurement_is_valid(data);
128 data->last_update = jiffies;
133 static int vz89x_get_resistance_reading(struct vz89x_data *data)
135 u8 *buf = &data->buffer[VZ89X_VOC_RESISTANCE_IDX];
137 return buf[0] | (buf[1] << 8);
140 static int vz89x_read_raw(struct iio_dev *indio_dev,
141 struct iio_chan_spec const *chan, int *val,
142 int *val2, long mask)
144 struct vz89x_data *data = iio_priv(indio_dev);
148 case IIO_CHAN_INFO_RAW:
149 mutex_lock(&data->lock);
150 ret = vz89x_get_measurement(data);
151 mutex_unlock(&data->lock);
156 switch (chan->address) {
157 case VZ89X_VOC_CO2_IDX:
158 case VZ89X_VOC_SHORT_IDX:
159 case VZ89X_VOC_TVOC_IDX:
160 *val = data->buffer[chan->address];
162 case VZ89X_VOC_RESISTANCE_IDX:
163 *val = vz89x_get_resistance_reading(data);
169 case IIO_CHAN_INFO_SCALE:
170 switch (chan->type) {
178 case IIO_CHAN_INFO_OFFSET:
179 switch (chan->address) {
180 case VZ89X_VOC_CO2_IDX:
183 return IIO_VAL_INT_PLUS_MICRO;
184 case VZ89X_VOC_TVOC_IDX:
195 static const struct iio_info vz89x_info = {
196 .attrs = &vz89x_attrs_group,
197 .read_raw = vz89x_read_raw,
198 .driver_module = THIS_MODULE,
201 static int vz89x_probe(struct i2c_client *client,
202 const struct i2c_device_id *id)
204 struct iio_dev *indio_dev;
205 struct vz89x_data *data;
207 if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA |
208 I2C_FUNC_SMBUS_BYTE))
211 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
215 data = iio_priv(indio_dev);
216 i2c_set_clientdata(client, indio_dev);
217 data->client = client;
218 data->last_update = jiffies - HZ;
219 mutex_init(&data->lock);
221 indio_dev->dev.parent = &client->dev;
222 indio_dev->info = &vz89x_info,
223 indio_dev->name = dev_name(&client->dev);
224 indio_dev->modes = INDIO_DIRECT_MODE;
226 indio_dev->channels = vz89x_channels;
227 indio_dev->num_channels = ARRAY_SIZE(vz89x_channels);
229 return devm_iio_device_register(&client->dev, indio_dev);
232 static const struct i2c_device_id vz89x_id[] = {
236 MODULE_DEVICE_TABLE(i2c, vz89x_id);
238 static const struct of_device_id vz89x_dt_ids[] = {
239 { .compatible = "sgx,vz89x" },
242 MODULE_DEVICE_TABLE(of, vz89x_dt_ids);
244 static struct i2c_driver vz89x_driver = {
247 .of_match_table = of_match_ptr(vz89x_dt_ids),
249 .probe = vz89x_probe,
250 .id_table = vz89x_id,
252 module_i2c_driver(vz89x_driver);
254 MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
255 MODULE_DESCRIPTION("SGX Sensortech MiCS VZ89X VOC sensors");
256 MODULE_LICENSE("GPL v2");