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");