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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 <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
18/* commands (high precision mode) */
19static const unsigned char shtc1_cmd_measure_blocking_hpm[] = { 0x7C, 0xA2 };
20static const unsigned char shtc1_cmd_measure_nonblocking_hpm[] = { 0x78, 0x66 };
21
22/* commands (low precision mode) */
23static const unsigned char shtc1_cmd_measure_blocking_lpm[] = { 0x64, 0x58 };
24static const unsigned char shtc1_cmd_measure_nonblocking_lpm[] = { 0x60, 0x9c };
25
26/* command for reading the ID register */
27static const unsigned char shtc1_cmd_read_id_reg[] = { 0xef, 0xc8 };
28
29/*
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
34 */
35#define SHTC3_ID 0x0807
36#define SHTC3_ID_MASK 0x083f
37#define SHTC1_ID 0x0007
38#define SHTC1_ID_MASK 0x003f
39
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
45
46#define SHTC1_CMD_LENGTH 2
47#define SHTC1_RESPONSE_LENGTH 6
48
49enum shtcx_chips {
50 shtc1,
51 shtc3,
52};
53
54struct shtc1_data {
55 struct i2c_client *client;
56 struct mutex update_lock;
57 bool valid;
58 unsigned long last_updated; /* in jiffies */
59
60 const unsigned char *command;
61 unsigned int nonblocking_wait_time; /* in us */
62
63 struct shtc1_platform_data setup;
64 enum shtcx_chips chip;
65
66 int temperature; /* 1000 * temperature in dgr C */
67 int humidity; /* 1000 * relative humidity in %RH */
68};
69
70static int shtc1_update_values(struct i2c_client *client,
71 struct shtc1_data *data,
72 char *buf, int bufsize)
73{
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;
78 }
79
80 /*
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.
85 */
86 if (!data->setup.blocking_io)
87 usleep_range(data->nonblocking_wait_time,
88 data->nonblocking_wait_time + 1000);
89
90 ret = i2c_master_recv(client, buf, bufsize);
91 if (ret != bufsize) {
92 dev_err(&client->dev, "failed to read values: %d\n", ret);
93 return ret < 0 ? ret : -EIO;
94 }
95
96 return 0;
97}
98
99/* sysfs attributes */
100static struct shtc1_data *shtc1_update_client(struct device *dev)
101{
102 struct shtc1_data *data = dev_get_drvdata(dev);
103 struct i2c_client *client = data->client;
104 unsigned char buf[SHTC1_RESPONSE_LENGTH];
105 int val;
106 int ret = 0;
107
108 mutex_lock(&data->update_lock);
109
110 if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) {
111 ret = shtc1_update_values(client, data, buf, sizeof(buf));
112 if (ret)
113 goto out;
114
115 /*
116 * From datasheet:
117 * T = -45 + 175 * ST / 2^16
118 * RH = 100 * SRH / 2^16
119 *
120 * Adapted for integer fixed point (3 digit) arithmetic.
121 */
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);
126
127 data->last_updated = jiffies;
128 data->valid = true;
129 }
130
131out:
132 mutex_unlock(&data->update_lock);
133
134 return ret == 0 ? data : ERR_PTR(ret);
135}
136
137static ssize_t temp1_input_show(struct device *dev,
138 struct device_attribute *attr,
139 char *buf)
140{
141 struct shtc1_data *data = shtc1_update_client(dev);
142 if (IS_ERR(data))
143 return PTR_ERR(data);
144
145 return sprintf(buf, "%d\n", data->temperature);
146}
147
148static ssize_t humidity1_input_show(struct device *dev,
149 struct device_attribute *attr, char *buf)
150{
151 struct shtc1_data *data = shtc1_update_client(dev);
152 if (IS_ERR(data))
153 return PTR_ERR(data);
154
155 return sprintf(buf, "%d\n", data->humidity);
156}
157
158static DEVICE_ATTR_RO(temp1_input);
159static DEVICE_ATTR_RO(humidity1_input);
160
161static struct attribute *shtc1_attrs[] = {
162 &dev_attr_temp1_input.attr,
163 &dev_attr_humidity1_input.attr,
164 NULL
165};
166
167ATTRIBUTE_GROUPS(shtc1);
168
169static void shtc1_select_command(struct shtc1_data *data)
170{
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;
178 } else {
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;
185 }
186}
187
188static int shtc1_probe(struct i2c_client *client,
189 const struct i2c_device_id *id)
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 = id->driver_data;
197 struct i2c_adapter *adap = client->adapter;
198 struct device *dev = &client->dev;
199
200 if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) {
201 dev_err(dev, "plain i2c transactions not supported\n");
202 return -ENODEV;
203 }
204
205 ret = i2c_master_send(client, shtc1_cmd_read_id_reg, SHTC1_CMD_LENGTH);
206 if (ret != SHTC1_CMD_LENGTH) {
207 dev_err(dev, "could not send read_id_reg command: %d\n", ret);
208 return ret < 0 ? ret : -ENODEV;
209 }
210 ret = i2c_master_recv(client, id_reg_buf, sizeof(id_reg_buf));
211 if (ret != sizeof(id_reg_buf)) {
212 dev_err(dev, "could not read ID register: %d\n", ret);
213 return -ENODEV;
214 }
215
216 id_reg = be16_to_cpup((__be16 *)id_reg_buf);
217 if (chip == shtc3) {
218 if ((id_reg & SHTC3_ID_MASK) != SHTC3_ID) {
219 dev_err(dev, "SHTC3 ID register does not match\n");
220 return -ENODEV;
221 }
222 } else if ((id_reg & SHTC1_ID_MASK) != SHTC1_ID) {
223 dev_err(dev, "SHTC1 ID register does not match\n");
224 return -ENODEV;
225 }
226
227 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
228 if (!data)
229 return -ENOMEM;
230
231 data->setup.blocking_io = false;
232 data->setup.high_precision = true;
233 data->client = client;
234 data->chip = chip;
235
236 if (client->dev.platform_data)
237 data->setup = *(struct shtc1_platform_data *)dev->platform_data;
238 shtc1_select_command(data);
239 mutex_init(&data->update_lock);
240
241 hwmon_dev = devm_hwmon_device_register_with_groups(dev,
242 client->name,
243 data,
244 shtc1_groups);
245 if (IS_ERR(hwmon_dev))
246 dev_dbg(dev, "unable to register hwmon device\n");
247
248 return PTR_ERR_OR_ZERO(hwmon_dev);
249}
250
251/* device ID table */
252static const struct i2c_device_id shtc1_id[] = {
253 { "shtc1", shtc1 },
254 { "shtw1", shtc1 },
255 { "shtc3", shtc3 },
256 { }
257};
258MODULE_DEVICE_TABLE(i2c, shtc1_id);
259
260static struct i2c_driver shtc1_i2c_driver = {
261 .driver.name = "shtc1",
262 .probe = shtc1_probe,
263 .id_table = shtc1_id,
264};
265
266module_i2c_driver(shtc1_i2c_driver);
267
268MODULE_AUTHOR("Johannes Winkelmann <johannes.winkelmann@sensirion.com>");
269MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver");
270MODULE_LICENSE("GPL");