1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
|
/*
* si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors
* Copyright (c) 2013,2014 Uplogix, Inc.
* David Barksdale <dbarksdale@uplogix.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* 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.
*/
/*
* The Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors
* are i2c devices which have an identical programming interface for
* measuring relative humidity and temperature. The Si7013 has an additional
* temperature input which this driver does not support.
*
* Data Sheets:
* Si7013: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7013.pdf
* Si7020: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7020.pdf
* Si7021: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7021.pdf
*/
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
/* Measure Relative Humidity, Hold Master Mode */
#define SI7020CMD_RH_HOLD 0xE5
/* Measure Temperature, Hold Master Mode */
#define SI7020CMD_TEMP_HOLD 0xE3
/* Software Reset */
#define SI7020CMD_RESET 0xFE
static int si7020_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int *val,
int *val2, long mask)
{
struct i2c_client **client = iio_priv(indio_dev);
int ret;
switch (mask) {
case IIO_CHAN_INFO_RAW:
ret = i2c_smbus_read_word_data(*client,
chan->type == IIO_TEMP ?
SI7020CMD_TEMP_HOLD :
SI7020CMD_RH_HOLD);
if (ret < 0)
return ret;
if (chan->type == IIO_TEMP)
*val = ret >> 2;
else
*val = (ret & 0x3FFF) >> 2;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
if (chan->type == IIO_TEMP)
*val = 175720; /* = 175.72 * 1000 */
else
*val = 125 * 1000;
*val2 = 65536 >> 2;
return IIO_VAL_FRACTIONAL;
case IIO_CHAN_INFO_OFFSET:
/*
* Since iio_convert_raw_to_processed_unlocked assumes offset
* is an integer we have to round these values and lose
* accuracy.
* Relative humidity will be 0.0032959% too high and
* temperature will be 0.00277344 degrees too high.
* This is no big deal because it's within the accuracy of the
* sensor.
*/
if (chan->type == IIO_TEMP)
*val = -4368; /* = -46.85 * (65536 >> 2) / 175.72 */
else
*val = -786; /* = -6 * (65536 >> 2) / 125 */
return IIO_VAL_INT;
default:
break;
}
return -EINVAL;
}
static const struct iio_chan_spec si7020_channels[] = {
{
.type = IIO_HUMIDITYRELATIVE,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
},
{
.type = IIO_TEMP,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
}
};
static const struct iio_info si7020_info = {
.read_raw = si7020_read_raw,
.driver_module = THIS_MODULE,
};
static int si7020_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct iio_dev *indio_dev;
struct i2c_client **data;
int ret;
if (!i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_WRITE_BYTE |
I2C_FUNC_SMBUS_READ_WORD_DATA))
return -ENODEV;
/* Reset device, loads default settings. */
ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);
if (ret < 0)
return ret;
/* Wait the maximum power-up time after software reset. */
msleep(15);
indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*client));
if (!indio_dev)
return -ENOMEM;
data = iio_priv(indio_dev);
*data = client;
i2c_set_clientdata(client, indio_dev);
indio_dev->dev.parent = &client->dev;
indio_dev->name = dev_name(&client->dev);
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->info = &si7020_info;
indio_dev->channels = si7020_channels;
indio_dev->num_channels = ARRAY_SIZE(si7020_channels);
return devm_iio_device_register(&client->dev, indio_dev);
}
static const struct i2c_device_id si7020_id[] = {
{ "si7020", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, si7020_id);
static struct i2c_driver si7020_driver = {
.driver.name = "si7020",
.probe = si7020_probe,
.id_table = si7020_id,
};
module_i2c_driver(si7020_driver);
MODULE_DESCRIPTION("Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors");
MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>");
MODULE_LICENSE("GPL");
|
