1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Sensirion SHTC1 humidity and temperature sensor driver
4 * Copyright (C) 2014 Sensirion AG, Switzerland
5 * Author: Johannes Winkelmann <johannes.winkelmann@sensirion.com>
8 #include <linux/module.h>
9 #include <linux/init.h>
10 #include <linux/slab.h>
11 #include <linux/i2c.h>
12 #include <linux/hwmon.h>
13 #include <linux/hwmon-sysfs.h>
14 #include <linux/err.h>
15 #include <linux/delay.h>
16 #include <linux/platform_data/shtc1.h>
18 /* commands (high precision mode) */
19 static const unsigned char shtc1_cmd_measure_blocking_hpm[] = { 0x7C, 0xA2 };
20 static const unsigned char shtc1_cmd_measure_nonblocking_hpm[] = { 0x78, 0x66 };
22 /* commands (low precision mode) */
23 static const unsigned char shtc1_cmd_measure_blocking_lpm[] = { 0x64, 0x58 };
24 static const unsigned char shtc1_cmd_measure_nonblocking_lpm[] = { 0x60, 0x9c };
26 /* command for reading the ID register */
27 static const unsigned char shtc1_cmd_read_id_reg[] = { 0xef, 0xc8 };
30 * constants for reading the ID register
31 * SHTC1: 0x0007 with mask 0x003f
32 * SHTW1: 0x0007 with mask 0x003f
33 * SHTC3: 0x0807 with mask 0x083f
35 #define SHTC3_ID 0x0807
36 #define SHTC3_ID_MASK 0x083f
37 #define SHTC1_ID 0x0007
38 #define SHTC1_ID_MASK 0x003f
40 /* delays for non-blocking i2c commands, both in us */
41 #define SHTC1_NONBLOCKING_WAIT_TIME_HPM 14400
42 #define SHTC1_NONBLOCKING_WAIT_TIME_LPM 1000
43 #define SHTC3_NONBLOCKING_WAIT_TIME_HPM 12100
44 #define SHTC3_NONBLOCKING_WAIT_TIME_LPM 800
46 #define SHTC1_CMD_LENGTH 2
47 #define SHTC1_RESPONSE_LENGTH 6
55 struct i2c_client *client;
56 struct mutex update_lock;
58 unsigned long last_updated; /* in jiffies */
60 const unsigned char *command;
61 unsigned int nonblocking_wait_time; /* in us */
63 struct shtc1_platform_data setup;
64 enum shtcx_chips chip;
66 int temperature; /* 1000 * temperature in dgr C */
67 int humidity; /* 1000 * relative humidity in %RH */
70 static int shtc1_update_values(struct i2c_client *client,
71 struct shtc1_data *data,
72 char *buf, int bufsize)
74 int ret = i2c_master_send(client, data->command, SHTC1_CMD_LENGTH);
75 if (ret != SHTC1_CMD_LENGTH) {
76 dev_err(&client->dev, "failed to send command: %d\n", ret);
77 return ret < 0 ? ret : -EIO;
81 * In blocking mode (clock stretching mode) the I2C bus
82 * is blocked for other traffic, thus the call to i2c_master_recv()
83 * will wait until the data is ready. For non blocking mode, we
84 * have to wait ourselves.
86 if (!data->setup.blocking_io)
87 usleep_range(data->nonblocking_wait_time,
88 data->nonblocking_wait_time + 1000);
90 ret = i2c_master_recv(client, buf, bufsize);
92 dev_err(&client->dev, "failed to read values: %d\n", ret);
93 return ret < 0 ? ret : -EIO;
99 /* sysfs attributes */
100 static struct shtc1_data *shtc1_update_client(struct device *dev)
102 struct shtc1_data *data = dev_get_drvdata(dev);
103 struct i2c_client *client = data->client;
104 unsigned char buf[SHTC1_RESPONSE_LENGTH];
108 mutex_lock(&data->update_lock);
110 if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) {
111 ret = shtc1_update_values(client, data, buf, sizeof(buf));
117 * T = -45 + 175 * ST / 2^16
118 * RH = 100 * SRH / 2^16
120 * Adapted for integer fixed point (3 digit) arithmetic.
122 val = be16_to_cpup((__be16 *)buf);
123 data->temperature = ((21875 * val) >> 13) - 45000;
124 val = be16_to_cpup((__be16 *)(buf + 3));
125 data->humidity = ((12500 * val) >> 13);
127 data->last_updated = jiffies;
132 mutex_unlock(&data->update_lock);
134 return ret == 0 ? data : ERR_PTR(ret);
137 static ssize_t temp1_input_show(struct device *dev,
138 struct device_attribute *attr,
141 struct shtc1_data *data = shtc1_update_client(dev);
143 return PTR_ERR(data);
145 return sprintf(buf, "%d\n", data->temperature);
148 static ssize_t humidity1_input_show(struct device *dev,
149 struct device_attribute *attr, char *buf)
151 struct shtc1_data *data = shtc1_update_client(dev);
153 return PTR_ERR(data);
155 return sprintf(buf, "%d\n", data->humidity);
158 static DEVICE_ATTR_RO(temp1_input);
159 static DEVICE_ATTR_RO(humidity1_input);
161 static struct attribute *shtc1_attrs[] = {
162 &dev_attr_temp1_input.attr,
163 &dev_attr_humidity1_input.attr,
167 ATTRIBUTE_GROUPS(shtc1);
169 static void shtc1_select_command(struct shtc1_data *data)
171 if (data->setup.high_precision) {
172 data->command = data->setup.blocking_io ?
173 shtc1_cmd_measure_blocking_hpm :
174 shtc1_cmd_measure_nonblocking_hpm;
175 data->nonblocking_wait_time = (data->chip == shtc1) ?
176 SHTC1_NONBLOCKING_WAIT_TIME_HPM :
177 SHTC3_NONBLOCKING_WAIT_TIME_HPM;
179 data->command = data->setup.blocking_io ?
180 shtc1_cmd_measure_blocking_lpm :
181 shtc1_cmd_measure_nonblocking_lpm;
182 data->nonblocking_wait_time = (data->chip == shtc1) ?
183 SHTC1_NONBLOCKING_WAIT_TIME_LPM :
184 SHTC3_NONBLOCKING_WAIT_TIME_LPM;
188 static const struct i2c_device_id shtc1_id[];
190 static int shtc1_probe(struct i2c_client *client)
195 struct shtc1_data *data;
196 struct device *hwmon_dev;
197 enum shtcx_chips chip = i2c_match_id(shtc1_id, client)->driver_data;
198 struct i2c_adapter *adap = client->adapter;
199 struct device *dev = &client->dev;
201 if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) {
202 dev_err(dev, "plain i2c transactions not supported\n");
206 ret = i2c_master_send(client, shtc1_cmd_read_id_reg, SHTC1_CMD_LENGTH);
207 if (ret != SHTC1_CMD_LENGTH) {
208 dev_err(dev, "could not send read_id_reg command: %d\n", ret);
209 return ret < 0 ? ret : -ENODEV;
211 ret = i2c_master_recv(client, id_reg_buf, sizeof(id_reg_buf));
212 if (ret != sizeof(id_reg_buf)) {
213 dev_err(dev, "could not read ID register: %d\n", ret);
217 id_reg = be16_to_cpup((__be16 *)id_reg_buf);
219 if ((id_reg & SHTC3_ID_MASK) != SHTC3_ID) {
220 dev_err(dev, "SHTC3 ID register does not match\n");
223 } else if ((id_reg & SHTC1_ID_MASK) != SHTC1_ID) {
224 dev_err(dev, "SHTC1 ID register does not match\n");
228 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
232 data->setup.blocking_io = false;
233 data->setup.high_precision = true;
234 data->client = client;
237 if (client->dev.platform_data)
238 data->setup = *(struct shtc1_platform_data *)dev->platform_data;
239 shtc1_select_command(data);
240 mutex_init(&data->update_lock);
242 hwmon_dev = devm_hwmon_device_register_with_groups(dev,
246 if (IS_ERR(hwmon_dev))
247 dev_dbg(dev, "unable to register hwmon device\n");
249 return PTR_ERR_OR_ZERO(hwmon_dev);
252 /* device ID table */
253 static const struct i2c_device_id shtc1_id[] = {
259 MODULE_DEVICE_TABLE(i2c, shtc1_id);
261 static struct i2c_driver shtc1_i2c_driver = {
262 .driver.name = "shtc1",
263 .probe_new = shtc1_probe,
264 .id_table = shtc1_id,
267 module_i2c_driver(shtc1_i2c_driver);
269 MODULE_AUTHOR("Johannes Winkelmann <johannes.winkelmann@sensirion.com>");
270 MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver");
271 MODULE_LICENSE("GPL");