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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#include <linux/stat.h>
27
28#include <linux/iio/iio.h>
29#include <linux/iio/sysfs.h>
30
31/* Measure Relative Humidity, Hold Master Mode */
32#define SI7020CMD_RH_HOLD 0xE5
33/* Measure Temperature, Hold Master Mode */
34#define SI7020CMD_TEMP_HOLD 0xE3
35/* Software Reset */
36#define SI7020CMD_RESET 0xFE
37#define SI7020CMD_USR_WRITE 0xE6
38/* "Heater Enabled" bit in the User Register */
39#define SI7020_USR_HEATER_EN BIT(2)
40#define SI7020CMD_HEATER_WRITE 0x51
41/* Heater current configuration bits */
42#define SI7020_HEATER_VAL GENMASK(3, 0)
43
44struct si7020_data {
45 struct i2c_client *client;
46 /* Lock for cached register values */
47 struct mutex lock;
48 u8 user_reg;
49 u8 heater_reg;
50};
51
52static const int si7020_heater_vals[] = { 0, 1, 0xF };
53
54static int si7020_read_raw(struct iio_dev *indio_dev,
55 struct iio_chan_spec const *chan, int *val,
56 int *val2, long mask)
57{
58 struct si7020_data *data = iio_priv(indio_dev);
59 int ret;
60
61 switch (mask) {
62 case IIO_CHAN_INFO_RAW:
63 if (chan->type == IIO_CURRENT) {
64 *val = data->heater_reg;
65 return IIO_VAL_INT;
66 }
67
68 ret = i2c_smbus_read_word_swapped(data->client,
69 chan->type == IIO_TEMP ?
70 SI7020CMD_TEMP_HOLD :
71 SI7020CMD_RH_HOLD);
72 if (ret < 0)
73 return ret;
74 *val = ret >> 2;
75 /*
76 * Humidity values can slightly exceed the 0-100%RH
77 * range and should be corrected by software
78 */
79 if (chan->type == IIO_HUMIDITYRELATIVE)
80 *val = clamp_val(*val, 786, 13893);
81 return IIO_VAL_INT;
82 case IIO_CHAN_INFO_SCALE:
83 if (chan->type == IIO_TEMP)
84 *val = 175720; /* = 175.72 * 1000 */
85 else
86 *val = 125 * 1000;
87 *val2 = 65536 >> 2;
88 return IIO_VAL_FRACTIONAL;
89 case IIO_CHAN_INFO_OFFSET:
90 /*
91 * Since iio_convert_raw_to_processed_unlocked assumes offset
92 * is an integer we have to round these values and lose
93 * accuracy.
94 * Relative humidity will be 0.0032959% too high and
95 * temperature will be 0.00277344 degrees too high.
96 * This is no big deal because it's within the accuracy of the
97 * sensor.
98 */
99 if (chan->type == IIO_TEMP)
100 *val = -4368; /* = -46.85 * (65536 >> 2) / 175.72 */
101 else
102 *val = -786; /* = -6 * (65536 >> 2) / 125 */
103 return IIO_VAL_INT;
104 default:
105 break;
106 }
107
108 return -EINVAL;
109}
110
111static const struct iio_chan_spec si7020_channels[] = {
112 {
113 .type = IIO_HUMIDITYRELATIVE,
114 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
115 BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
116 },
117 {
118 .type = IIO_TEMP,
119 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
120 BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
121 },
122 {
123 .type = IIO_CURRENT,
124 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
125 .info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW),
126 .extend_name = "heater",
127 }
128};
129
130static int si7020_update_reg(struct si7020_data *data,
131 u8 *reg, u8 cmd, u8 mask, u8 val)
132{
133 u8 new = (*reg & ~mask) | val;
134 int ret;
135
136 ret = i2c_smbus_write_byte_data(data->client, cmd, new);
137 if (ret)
138 return ret;
139
140 *reg = new;
141
142 return 0;
143}
144
145static int si7020_write_raw(struct iio_dev *indio_dev,
146 struct iio_chan_spec const *chan,
147 int val, int val2, long mask)
148{
149 struct si7020_data *data = iio_priv(indio_dev);
150 int ret;
151
152 switch (mask) {
153 case IIO_CHAN_INFO_RAW:
154 if (chan->type != IIO_CURRENT || val2 != 0 ||
155 val < si7020_heater_vals[0] || val > si7020_heater_vals[2])
156 return -EINVAL;
157
158 scoped_guard(mutex, &data->lock)
159 ret = si7020_update_reg(data, &data->heater_reg,
160 SI7020CMD_HEATER_WRITE, SI7020_HEATER_VAL, val);
161 return ret;
162 default:
163 return -EINVAL;
164 }
165}
166
167static int si7020_read_available(struct iio_dev *indio_dev,
168 struct iio_chan_spec const *chan,
169 const int **vals,
170 int *type, int *length, long mask)
171{
172 if (mask != IIO_CHAN_INFO_RAW || chan->type != IIO_CURRENT)
173 return -EINVAL;
174
175 *vals = si7020_heater_vals;
176 *type = IIO_VAL_INT;
177
178 return IIO_AVAIL_RANGE;
179}
180
181static ssize_t si7020_show_heater_en(struct device *dev,
182 struct device_attribute *attr, char *buf)
183{
184 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
185 struct si7020_data *data = iio_priv(indio_dev);
186
187 return sysfs_emit(buf, "%d\n", !!(data->user_reg & SI7020_USR_HEATER_EN));
188}
189
190static ssize_t si7020_store_heater_en(struct device *dev,
191 struct device_attribute *attr,
192 const char *buf, size_t len)
193{
194 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
195 struct si7020_data *data = iio_priv(indio_dev);
196 int ret;
197 bool val;
198
199 ret = kstrtobool(buf, &val);
200 if (ret)
201 return ret;
202
203 scoped_guard(mutex, &data->lock)
204 ret = si7020_update_reg(data, &data->user_reg, SI7020CMD_USR_WRITE,
205 SI7020_USR_HEATER_EN, val ? SI7020_USR_HEATER_EN : 0);
206
207 return ret < 0 ? ret : len;
208}
209
210static IIO_DEVICE_ATTR(heater_enable, 0644,
211 si7020_show_heater_en, si7020_store_heater_en, 0);
212
213static struct attribute *si7020_attributes[] = {
214 &iio_dev_attr_heater_enable.dev_attr.attr,
215 NULL
216};
217
218static const struct attribute_group si7020_attribute_group = {
219 .attrs = si7020_attributes,
220};
221
222static const struct iio_info si7020_info = {
223 .read_raw = si7020_read_raw,
224 .write_raw = si7020_write_raw,
225 .read_avail = si7020_read_available,
226 .attrs = &si7020_attribute_group,
227};
228
229static int si7020_probe(struct i2c_client *client)
230{
231 struct iio_dev *indio_dev;
232 struct si7020_data *data;
233 int ret;
234
235 if (!i2c_check_functionality(client->adapter,
236 I2C_FUNC_SMBUS_WRITE_BYTE |
237 I2C_FUNC_SMBUS_READ_WORD_DATA))
238 return -EOPNOTSUPP;
239
240 /* Reset device, loads default settings. */
241 ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);
242 if (ret < 0)
243 return ret;
244 /* Wait the maximum power-up time after software reset. */
245 msleep(15);
246
247 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
248 if (!indio_dev)
249 return -ENOMEM;
250
251 data = iio_priv(indio_dev);
252 i2c_set_clientdata(client, indio_dev);
253 data->client = client;
254 mutex_init(&data->lock);
255
256 indio_dev->name = dev_name(&client->dev);
257 indio_dev->modes = INDIO_DIRECT_MODE;
258 indio_dev->info = &si7020_info;
259 indio_dev->channels = si7020_channels;
260 indio_dev->num_channels = ARRAY_SIZE(si7020_channels);
261
262 /* All the "reserved" bits in the User Register are 1s by default */
263 data->user_reg = 0x3A;
264 data->heater_reg = 0x0;
265
266 return devm_iio_device_register(&client->dev, indio_dev);
267}
268
269static const struct i2c_device_id si7020_id[] = {
270 { "si7020" },
271 { "th06" },
272 { }
273};
274MODULE_DEVICE_TABLE(i2c, si7020_id);
275
276static const struct of_device_id si7020_dt_ids[] = {
277 { .compatible = "silabs,si7020" },
278 { }
279};
280MODULE_DEVICE_TABLE(of, si7020_dt_ids);
281
282static struct i2c_driver si7020_driver = {
283 .driver = {
284 .name = "si7020",
285 .of_match_table = si7020_dt_ids,
286 },
287 .probe = si7020_probe,
288 .id_table = si7020_id,
289};
290
291module_i2c_driver(si7020_driver);
292MODULE_DESCRIPTION("Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors");
293MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>");
294MODULE_LICENSE("GPL");