1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Sensirion SHTC1 humidity and temperature sensor driver
3 *
4 * Copyright (C) 2014 Sensirion AG, Switzerland
5 * Author: Johannes Winkelmann <johannes.winkelmann@sensirion.com>
6 */
7
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>
17 #include <linux/of.h>
18
19 /* commands (high precision mode) */
20 static const unsigned char shtc1_cmd_measure_blocking_hpm[] = { 0x7C, 0xA2 };
21 static const unsigned char shtc1_cmd_measure_nonblocking_hpm[] = { 0x78, 0x66 };
22
23 /* commands (low precision mode) */
24 static const unsigned char shtc1_cmd_measure_blocking_lpm[] = { 0x64, 0x58 };
25 static const unsigned char shtc1_cmd_measure_nonblocking_lpm[] = { 0x60, 0x9c };
26
27 /* command for reading the ID register */
28 static const unsigned char shtc1_cmd_read_id_reg[] = { 0xef, 0xc8 };
29
30 /*
31 * constants for reading the ID register
32 * SHTC1: 0x0007 with mask 0x003f
33 * SHTW1: 0x0007 with mask 0x003f
34 * SHTC3: 0x0807 with mask 0x083f
35 */
36 #define SHTC3_ID 0x0807
37 #define SHTC3_ID_MASK 0x083f
38 #define SHTC1_ID 0x0007
39 #define SHTC1_ID_MASK 0x003f
40
41 /* delays for non-blocking i2c commands, both in us */
42 #define SHTC1_NONBLOCKING_WAIT_TIME_HPM 14400
43 #define SHTC1_NONBLOCKING_WAIT_TIME_LPM 1000
44 #define SHTC3_NONBLOCKING_WAIT_TIME_HPM 12100
45 #define SHTC3_NONBLOCKING_WAIT_TIME_LPM 800
46
47 #define SHTC1_CMD_LENGTH 2
48 #define SHTC1_RESPONSE_LENGTH 6
49
50 enum shtcx_chips {
51 shtc1,
52 shtc3,
53 };
54
55 struct shtc1_data {
56 struct i2c_client *client;
57 struct mutex update_lock;
58 bool valid;
59 unsigned long last_updated; /* in jiffies */
60
61 const unsigned char *command;
62 unsigned int nonblocking_wait_time; /* in us */
63
64 struct shtc1_platform_data setup;
65 enum shtcx_chips chip;
66
67 int temperature; /* 1000 * temperature in dgr C */
68 int humidity; /* 1000 * relative humidity in %RH */
69 };
70
shtc1_update_values(struct i2c_client * client,struct shtc1_data * data,char * buf,int bufsize)71 static int shtc1_update_values(struct i2c_client *client,
72 struct shtc1_data *data,
73 char *buf, int bufsize)
74 {
75 int ret = i2c_master_send(client, data->command, SHTC1_CMD_LENGTH);
76 if (ret != SHTC1_CMD_LENGTH) {
77 dev_err(&client->dev, "failed to send command: %d\n", ret);
78 return ret < 0 ? ret : -EIO;
79 }
80
81 /*
82 * In blocking mode (clock stretching mode) the I2C bus
83 * is blocked for other traffic, thus the call to i2c_master_recv()
84 * will wait until the data is ready. For non blocking mode, we
85 * have to wait ourselves.
86 */
87 if (!data->setup.blocking_io)
88 usleep_range(data->nonblocking_wait_time,
89 data->nonblocking_wait_time + 1000);
90
91 ret = i2c_master_recv(client, buf, bufsize);
92 if (ret != bufsize) {
93 dev_err(&client->dev, "failed to read values: %d\n", ret);
94 return ret < 0 ? ret : -EIO;
95 }
96
97 return 0;
98 }
99
100 /* sysfs attributes */
shtc1_update_client(struct device * dev)101 static struct shtc1_data *shtc1_update_client(struct device *dev)
102 {
103 struct shtc1_data *data = dev_get_drvdata(dev);
104 struct i2c_client *client = data->client;
105 unsigned char buf[SHTC1_RESPONSE_LENGTH];
106 int val;
107 int ret = 0;
108
109 mutex_lock(&data->update_lock);
110
111 if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) {
112 ret = shtc1_update_values(client, data, buf, sizeof(buf));
113 if (ret)
114 goto out;
115
116 /*
117 * From datasheet:
118 * T = -45 + 175 * ST / 2^16
119 * RH = 100 * SRH / 2^16
120 *
121 * Adapted for integer fixed point (3 digit) arithmetic.
122 */
123 val = be16_to_cpup((__be16 *)buf);
124 data->temperature = ((21875 * val) >> 13) - 45000;
125 val = be16_to_cpup((__be16 *)(buf + 3));
126 data->humidity = ((12500 * val) >> 13);
127
128 data->last_updated = jiffies;
129 data->valid = true;
130 }
131
132 out:
133 mutex_unlock(&data->update_lock);
134
135 return ret == 0 ? data : ERR_PTR(ret);
136 }
137
temp1_input_show(struct device * dev,struct device_attribute * attr,char * buf)138 static ssize_t temp1_input_show(struct device *dev,
139 struct device_attribute *attr,
140 char *buf)
141 {
142 struct shtc1_data *data = shtc1_update_client(dev);
143 if (IS_ERR(data))
144 return PTR_ERR(data);
145
146 return sprintf(buf, "%d\n", data->temperature);
147 }
148
humidity1_input_show(struct device * dev,struct device_attribute * attr,char * buf)149 static ssize_t humidity1_input_show(struct device *dev,
150 struct device_attribute *attr, char *buf)
151 {
152 struct shtc1_data *data = shtc1_update_client(dev);
153 if (IS_ERR(data))
154 return PTR_ERR(data);
155
156 return sprintf(buf, "%d\n", data->humidity);
157 }
158
159 static DEVICE_ATTR_RO(temp1_input);
160 static DEVICE_ATTR_RO(humidity1_input);
161
162 static struct attribute *shtc1_attrs[] = {
163 &dev_attr_temp1_input.attr,
164 &dev_attr_humidity1_input.attr,
165 NULL
166 };
167
168 ATTRIBUTE_GROUPS(shtc1);
169
shtc1_select_command(struct shtc1_data * data)170 static void shtc1_select_command(struct shtc1_data *data)
171 {
172 if (data->setup.high_precision) {
173 data->command = data->setup.blocking_io ?
174 shtc1_cmd_measure_blocking_hpm :
175 shtc1_cmd_measure_nonblocking_hpm;
176 data->nonblocking_wait_time = (data->chip == shtc1) ?
177 SHTC1_NONBLOCKING_WAIT_TIME_HPM :
178 SHTC3_NONBLOCKING_WAIT_TIME_HPM;
179 } else {
180 data->command = data->setup.blocking_io ?
181 shtc1_cmd_measure_blocking_lpm :
182 shtc1_cmd_measure_nonblocking_lpm;
183 data->nonblocking_wait_time = (data->chip == shtc1) ?
184 SHTC1_NONBLOCKING_WAIT_TIME_LPM :
185 SHTC3_NONBLOCKING_WAIT_TIME_LPM;
186 }
187 }
188
189 static const struct i2c_device_id shtc1_id[];
190
shtc1_probe(struct i2c_client * client)191 static int shtc1_probe(struct i2c_client *client)
192 {
193 int ret;
194 u16 id_reg;
195 char id_reg_buf[2];
196 struct shtc1_data *data;
197 struct device *hwmon_dev;
198 enum shtcx_chips chip = i2c_match_id(shtc1_id, client)->driver_data;
199 struct i2c_adapter *adap = client->adapter;
200 struct device *dev = &client->dev;
201 struct device_node *np = dev->of_node;
202
203 if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) {
204 dev_err(dev, "plain i2c transactions not supported\n");
205 return -ENODEV;
206 }
207
208 ret = i2c_master_send(client, shtc1_cmd_read_id_reg, SHTC1_CMD_LENGTH);
209 if (ret != SHTC1_CMD_LENGTH) {
210 dev_err(dev, "could not send read_id_reg command: %d\n", ret);
211 return ret < 0 ? ret : -ENODEV;
212 }
213 ret = i2c_master_recv(client, id_reg_buf, sizeof(id_reg_buf));
214 if (ret != sizeof(id_reg_buf)) {
215 dev_err(dev, "could not read ID register: %d\n", ret);
216 return -ENODEV;
217 }
218
219 id_reg = be16_to_cpup((__be16 *)id_reg_buf);
220 if (chip == shtc3) {
221 if ((id_reg & SHTC3_ID_MASK) != SHTC3_ID) {
222 dev_err(dev, "SHTC3 ID register does not match\n");
223 return -ENODEV;
224 }
225 } else if ((id_reg & SHTC1_ID_MASK) != SHTC1_ID) {
226 dev_err(dev, "SHTC1 ID register does not match\n");
227 return -ENODEV;
228 }
229
230 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
231 if (!data)
232 return -ENOMEM;
233
234 data->setup.blocking_io = false;
235 data->setup.high_precision = true;
236 data->client = client;
237 data->chip = chip;
238
239 if (np) {
240 data->setup.blocking_io = of_property_read_bool(np, "sensirion,blocking-io");
241 data->setup.high_precision = !of_property_read_bool(np, "sensirion,low-precision");
242 } else {
243 if (client->dev.platform_data)
244 data->setup = *(struct shtc1_platform_data *)dev->platform_data;
245 }
246
247 shtc1_select_command(data);
248 mutex_init(&data->update_lock);
249
250 hwmon_dev = devm_hwmon_device_register_with_groups(dev,
251 client->name,
252 data,
253 shtc1_groups);
254 if (IS_ERR(hwmon_dev))
255 dev_dbg(dev, "unable to register hwmon device\n");
256
257 return PTR_ERR_OR_ZERO(hwmon_dev);
258 }
259
260 /* device ID table */
261 static const struct i2c_device_id shtc1_id[] = {
262 { "shtc1", shtc1 },
263 { "shtw1", shtc1 },
264 { "shtc3", shtc3 },
265 { }
266 };
267 MODULE_DEVICE_TABLE(i2c, shtc1_id);
268
269 static const struct of_device_id shtc1_of_match[] = {
270 { .compatible = "sensirion,shtc1" },
271 { .compatible = "sensirion,shtw1" },
272 { .compatible = "sensirion,shtc3" },
273 { }
274 };
275 MODULE_DEVICE_TABLE(of, shtc1_of_match);
276
277 static struct i2c_driver shtc1_i2c_driver = {
278 .driver = {
279 .name = "shtc1",
280 .of_match_table = shtc1_of_match,
281 },
282 .probe = shtc1_probe,
283 .id_table = shtc1_id,
284 };
285
286 module_i2c_driver(shtc1_i2c_driver);
287
288 MODULE_AUTHOR("Johannes Winkelmann <johannes.winkelmann@sensirion.com>");
289 MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver");
290 MODULE_LICENSE("GPL");
291