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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 <[email protected]>
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) */
20static const unsigned char shtc1_cmd_measure_blocking_hpm[] = { 0x7C, 0xA2 };
21static const unsigned char shtc1_cmd_measure_nonblocking_hpm[] = { 0x78, 0x66 };
22
23/* commands (low precision mode) */
24static const unsigned char shtc1_cmd_measure_blocking_lpm[] = { 0x64, 0x58 };
25static const unsigned char shtc1_cmd_measure_nonblocking_lpm[] = { 0x60, 0x9c };
26
27/* command for reading the ID register */
28static 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
50enum shtcx_chips {
51 shtc1,
52 shtc3,
53};
54
55struct 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
71static 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 */
101static 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
132out:
133 mutex_unlock(&data->update_lock);
134
135 return ret == 0 ? data : ERR_PTR(ret);
136}
137
138static 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
149static 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
159static DEVICE_ATTR_RO(temp1_input);
160static DEVICE_ATTR_RO(humidity1_input);
161
162static struct attribute *shtc1_attrs[] = {
163 &dev_attr_temp1_input.attr,
164 &dev_attr_humidity1_input.attr,
165 NULL
166};
167
168ATTRIBUTE_GROUPS(shtc1);
169
170static 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
189static int shtc1_probe(struct i2c_client *client)
190{
191 int ret;
192 u16 id_reg;
193 char id_reg_buf[2];
194 struct shtc1_data *data;
195 struct device *hwmon_dev;
196 enum shtcx_chips chip = (uintptr_t)i2c_get_match_data(client);
197 struct i2c_adapter *adap = client->adapter;
198 struct device *dev = &client->dev;
199 struct device_node *np = dev->of_node;
200
201 if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) {
202 dev_err(dev, "plain i2c transactions not supported\n");
203 return -ENODEV;
204 }
205
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;
210 }
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);
214 return -ENODEV;
215 }
216
217 id_reg = be16_to_cpup((__be16 *)id_reg_buf);
218 if (chip == shtc3) {
219 if ((id_reg & SHTC3_ID_MASK) != SHTC3_ID) {
220 dev_err(dev, "SHTC3 ID register does not match\n");
221 return -ENODEV;
222 }
223 } else if ((id_reg & SHTC1_ID_MASK) != SHTC1_ID) {
224 dev_err(dev, "SHTC1 ID register does not match\n");
225 return -ENODEV;
226 }
227
228 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
229 if (!data)
230 return -ENOMEM;
231
232 data->setup.blocking_io = false;
233 data->setup.high_precision = true;
234 data->client = client;
235 data->chip = chip;
236
237 if (np) {
238 data->setup.blocking_io = of_property_read_bool(np, "sensirion,blocking-io");
239 data->setup.high_precision = !of_property_read_bool(np, "sensirion,low-precision");
240 } else {
241 if (client->dev.platform_data)
242 data->setup = *(struct shtc1_platform_data *)dev->platform_data;
243 }
244
245 shtc1_select_command(data);
246 mutex_init(&data->update_lock);
247
248 hwmon_dev = devm_hwmon_device_register_with_groups(dev,
249 client->name,
250 data,
251 shtc1_groups);
252 if (IS_ERR(hwmon_dev))
253 dev_dbg(dev, "unable to register hwmon device\n");
254
255 return PTR_ERR_OR_ZERO(hwmon_dev);
256}
257
258/* device ID table */
259static const struct i2c_device_id shtc1_id[] = {
260 { .name = "shtc1", .driver_data = shtc1 },
261 { .name = "shtw1", .driver_data = shtc1 },
262 { .name = "shtc3", .driver_data = shtc3 },
263 { }
264};
265MODULE_DEVICE_TABLE(i2c, shtc1_id);
266
267static const struct of_device_id shtc1_of_match[] = {
268 { .compatible = "sensirion,shtc1" },
269 { .compatible = "sensirion,shtw1" },
270 { .compatible = "sensirion,shtc3" },
271 { }
272};
273MODULE_DEVICE_TABLE(of, shtc1_of_match);
274
275static struct i2c_driver shtc1_i2c_driver = {
276 .driver = {
277 .name = "shtc1",
278 .of_match_table = shtc1_of_match,
279 },
280 .probe = shtc1_probe,
281 .id_table = shtc1_id,
282};
283
284module_i2c_driver(shtc1_i2c_driver);
285
286MODULE_AUTHOR("Johannes Winkelmann <[email protected]>");
287MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver");
288MODULE_LICENSE("GPL");