1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors |
4 | * Copyright (c) 2013,2014 Uplogix, Inc. |
5 | * David Barksdale <dbarksdale@uplogix.com> |
6 | */ |
7 | |
8 | /* |
9 | * The Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors |
10 | * are i2c devices which have an identical programming interface for |
11 | * measuring relative humidity and temperature. The Si7013 has an additional |
12 | * temperature input which this driver does not support. |
13 | * |
14 | * Data Sheets: |
15 | * Si7013: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7013.pdf |
16 | * Si7020: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7020.pdf |
17 | * Si7021: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7021.pdf |
18 | */ |
19 | |
20 | #include <linux/delay.h> |
21 | #include <linux/i2c.h> |
22 | #include <linux/module.h> |
23 | #include <linux/mod_devicetable.h> |
24 | #include <linux/slab.h> |
25 | #include <linux/sysfs.h> |
26 | |
27 | #include <linux/iio/iio.h> |
28 | #include <linux/iio/sysfs.h> |
29 | |
30 | /* Measure Relative Humidity, Hold Master Mode */ |
31 | #define SI7020CMD_RH_HOLD 0xE5 |
32 | /* Measure Temperature, Hold Master Mode */ |
33 | #define SI7020CMD_TEMP_HOLD 0xE3 |
34 | /* Software Reset */ |
35 | #define SI7020CMD_RESET 0xFE |
36 | |
37 | static int si7020_read_raw(struct iio_dev *indio_dev, |
38 | struct iio_chan_spec const *chan, int *val, |
39 | int *val2, long mask) |
40 | { |
41 | struct i2c_client **client = iio_priv(indio_dev); |
42 | int ret; |
43 | |
44 | switch (mask) { |
45 | case IIO_CHAN_INFO_RAW: |
46 | ret = i2c_smbus_read_word_swapped(client: *client, |
47 | command: chan->type == IIO_TEMP ? |
48 | SI7020CMD_TEMP_HOLD : |
49 | SI7020CMD_RH_HOLD); |
50 | if (ret < 0) |
51 | return ret; |
52 | *val = ret >> 2; |
53 | /* |
54 | * Humidity values can slightly exceed the 0-100%RH |
55 | * range and should be corrected by software |
56 | */ |
57 | if (chan->type == IIO_HUMIDITYRELATIVE) |
58 | *val = clamp_val(*val, 786, 13893); |
59 | return IIO_VAL_INT; |
60 | case IIO_CHAN_INFO_SCALE: |
61 | if (chan->type == IIO_TEMP) |
62 | *val = 175720; /* = 175.72 * 1000 */ |
63 | else |
64 | *val = 125 * 1000; |
65 | *val2 = 65536 >> 2; |
66 | return IIO_VAL_FRACTIONAL; |
67 | case IIO_CHAN_INFO_OFFSET: |
68 | /* |
69 | * Since iio_convert_raw_to_processed_unlocked assumes offset |
70 | * is an integer we have to round these values and lose |
71 | * accuracy. |
72 | * Relative humidity will be 0.0032959% too high and |
73 | * temperature will be 0.00277344 degrees too high. |
74 | * This is no big deal because it's within the accuracy of the |
75 | * sensor. |
76 | */ |
77 | if (chan->type == IIO_TEMP) |
78 | *val = -4368; /* = -46.85 * (65536 >> 2) / 175.72 */ |
79 | else |
80 | *val = -786; /* = -6 * (65536 >> 2) / 125 */ |
81 | return IIO_VAL_INT; |
82 | default: |
83 | break; |
84 | } |
85 | |
86 | return -EINVAL; |
87 | } |
88 | |
89 | static const struct iio_chan_spec si7020_channels[] = { |
90 | { |
91 | .type = IIO_HUMIDITYRELATIVE, |
92 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | |
93 | BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET), |
94 | }, |
95 | { |
96 | .type = IIO_TEMP, |
97 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | |
98 | BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET), |
99 | } |
100 | }; |
101 | |
102 | static const struct iio_info si7020_info = { |
103 | .read_raw = si7020_read_raw, |
104 | }; |
105 | |
106 | static int si7020_probe(struct i2c_client *client) |
107 | { |
108 | struct iio_dev *indio_dev; |
109 | struct i2c_client **data; |
110 | int ret; |
111 | |
112 | if (!i2c_check_functionality(adap: client->adapter, |
113 | I2C_FUNC_SMBUS_WRITE_BYTE | |
114 | I2C_FUNC_SMBUS_READ_WORD_DATA)) |
115 | return -EOPNOTSUPP; |
116 | |
117 | /* Reset device, loads default settings. */ |
118 | ret = i2c_smbus_write_byte(client, SI7020CMD_RESET); |
119 | if (ret < 0) |
120 | return ret; |
121 | /* Wait the maximum power-up time after software reset. */ |
122 | msleep(msecs: 15); |
123 | |
124 | indio_dev = devm_iio_device_alloc(parent: &client->dev, sizeof_priv: sizeof(*data)); |
125 | if (!indio_dev) |
126 | return -ENOMEM; |
127 | |
128 | data = iio_priv(indio_dev); |
129 | *data = client; |
130 | |
131 | indio_dev->name = dev_name(dev: &client->dev); |
132 | indio_dev->modes = INDIO_DIRECT_MODE; |
133 | indio_dev->info = &si7020_info; |
134 | indio_dev->channels = si7020_channels; |
135 | indio_dev->num_channels = ARRAY_SIZE(si7020_channels); |
136 | |
137 | return devm_iio_device_register(&client->dev, indio_dev); |
138 | } |
139 | |
140 | static const struct i2c_device_id si7020_id[] = { |
141 | { "si7020" , 0 }, |
142 | { "th06" , 0 }, |
143 | { } |
144 | }; |
145 | MODULE_DEVICE_TABLE(i2c, si7020_id); |
146 | |
147 | static const struct of_device_id si7020_dt_ids[] = { |
148 | { .compatible = "silabs,si7020" }, |
149 | { } |
150 | }; |
151 | MODULE_DEVICE_TABLE(of, si7020_dt_ids); |
152 | |
153 | static struct i2c_driver si7020_driver = { |
154 | .driver = { |
155 | .name = "si7020" , |
156 | .of_match_table = si7020_dt_ids, |
157 | }, |
158 | .probe = si7020_probe, |
159 | .id_table = si7020_id, |
160 | }; |
161 | |
162 | module_i2c_driver(si7020_driver); |
163 | MODULE_DESCRIPTION("Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors" ); |
164 | MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>" ); |
165 | MODULE_LICENSE("GPL" ); |
166 | |