treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157
[sfrench/cifs-2.6.git] / drivers / hwmon / shtc1.c
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) */
19 static const unsigned char shtc1_cmd_measure_blocking_hpm[]    = { 0x7C, 0xA2 };
20 static const unsigned char shtc1_cmd_measure_nonblocking_hpm[] = { 0x78, 0x66 };
21
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 };
25
26 /* command for reading the ID register */
27 static const unsigned char shtc1_cmd_read_id_reg[]             = { 0xef, 0xc8 };
28
29 /* constants for reading the ID register */
30 #define SHTC1_ID          0x07
31 #define SHTC1_ID_REG_MASK 0x1f
32
33 /* delays for non-blocking i2c commands, both in us */
34 #define SHTC1_NONBLOCKING_WAIT_TIME_HPM  14400
35 #define SHTC1_NONBLOCKING_WAIT_TIME_LPM   1000
36
37 #define SHTC1_CMD_LENGTH      2
38 #define SHTC1_RESPONSE_LENGTH 6
39
40 struct shtc1_data {
41         struct i2c_client *client;
42         struct mutex update_lock;
43         bool valid;
44         unsigned long last_updated; /* in jiffies */
45
46         const unsigned char *command;
47         unsigned int nonblocking_wait_time; /* in us */
48
49         struct shtc1_platform_data setup;
50
51         int temperature; /* 1000 * temperature in dgr C */
52         int humidity; /* 1000 * relative humidity in %RH */
53 };
54
55 static int shtc1_update_values(struct i2c_client *client,
56                                struct shtc1_data *data,
57                                char *buf, int bufsize)
58 {
59         int ret = i2c_master_send(client, data->command, SHTC1_CMD_LENGTH);
60         if (ret != SHTC1_CMD_LENGTH) {
61                 dev_err(&client->dev, "failed to send command: %d\n", ret);
62                 return ret < 0 ? ret : -EIO;
63         }
64
65         /*
66          * In blocking mode (clock stretching mode) the I2C bus
67          * is blocked for other traffic, thus the call to i2c_master_recv()
68          * will wait until the data is ready. For non blocking mode, we
69          * have to wait ourselves.
70          */
71         if (!data->setup.blocking_io)
72                 usleep_range(data->nonblocking_wait_time,
73                              data->nonblocking_wait_time + 1000);
74
75         ret = i2c_master_recv(client, buf, bufsize);
76         if (ret != bufsize) {
77                 dev_err(&client->dev, "failed to read values: %d\n", ret);
78                 return ret < 0 ? ret : -EIO;
79         }
80
81         return 0;
82 }
83
84 /* sysfs attributes */
85 static struct shtc1_data *shtc1_update_client(struct device *dev)
86 {
87         struct shtc1_data *data = dev_get_drvdata(dev);
88         struct i2c_client *client = data->client;
89         unsigned char buf[SHTC1_RESPONSE_LENGTH];
90         int val;
91         int ret = 0;
92
93         mutex_lock(&data->update_lock);
94
95         if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) {
96                 ret = shtc1_update_values(client, data, buf, sizeof(buf));
97                 if (ret)
98                         goto out;
99
100                 /*
101                  * From datasheet:
102                  * T = -45 + 175 * ST / 2^16
103                  * RH = 100 * SRH / 2^16
104                  *
105                  * Adapted for integer fixed point (3 digit) arithmetic.
106                  */
107                 val = be16_to_cpup((__be16 *)buf);
108                 data->temperature = ((21875 * val) >> 13) - 45000;
109                 val = be16_to_cpup((__be16 *)(buf + 3));
110                 data->humidity = ((12500 * val) >> 13);
111
112                 data->last_updated = jiffies;
113                 data->valid = true;
114         }
115
116 out:
117         mutex_unlock(&data->update_lock);
118
119         return ret == 0 ? data : ERR_PTR(ret);
120 }
121
122 static ssize_t temp1_input_show(struct device *dev,
123                                 struct device_attribute *attr,
124                                 char *buf)
125 {
126         struct shtc1_data *data = shtc1_update_client(dev);
127         if (IS_ERR(data))
128                 return PTR_ERR(data);
129
130         return sprintf(buf, "%d\n", data->temperature);
131 }
132
133 static ssize_t humidity1_input_show(struct device *dev,
134                                     struct device_attribute *attr, char *buf)
135 {
136         struct shtc1_data *data = shtc1_update_client(dev);
137         if (IS_ERR(data))
138                 return PTR_ERR(data);
139
140         return sprintf(buf, "%d\n", data->humidity);
141 }
142
143 static DEVICE_ATTR_RO(temp1_input);
144 static DEVICE_ATTR_RO(humidity1_input);
145
146 static struct attribute *shtc1_attrs[] = {
147         &dev_attr_temp1_input.attr,
148         &dev_attr_humidity1_input.attr,
149         NULL
150 };
151
152 ATTRIBUTE_GROUPS(shtc1);
153
154 static void shtc1_select_command(struct shtc1_data *data)
155 {
156         if (data->setup.high_precision) {
157                 data->command = data->setup.blocking_io ?
158                                 shtc1_cmd_measure_blocking_hpm :
159                                 shtc1_cmd_measure_nonblocking_hpm;
160                 data->nonblocking_wait_time = SHTC1_NONBLOCKING_WAIT_TIME_HPM;
161
162         } else {
163                 data->command = data->setup.blocking_io ?
164                                 shtc1_cmd_measure_blocking_lpm :
165                                 shtc1_cmd_measure_nonblocking_lpm;
166                 data->nonblocking_wait_time = SHTC1_NONBLOCKING_WAIT_TIME_LPM;
167         }
168 }
169
170 static int shtc1_probe(struct i2c_client *client,
171                        const struct i2c_device_id *id)
172 {
173         int ret;
174         char id_reg[2];
175         struct shtc1_data *data;
176         struct device *hwmon_dev;
177         struct i2c_adapter *adap = client->adapter;
178         struct device *dev = &client->dev;
179
180         if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) {
181                 dev_err(dev, "plain i2c transactions not supported\n");
182                 return -ENODEV;
183         }
184
185         ret = i2c_master_send(client, shtc1_cmd_read_id_reg, SHTC1_CMD_LENGTH);
186         if (ret != SHTC1_CMD_LENGTH) {
187                 dev_err(dev, "could not send read_id_reg command: %d\n", ret);
188                 return ret < 0 ? ret : -ENODEV;
189         }
190         ret = i2c_master_recv(client, id_reg, sizeof(id_reg));
191         if (ret != sizeof(id_reg)) {
192                 dev_err(dev, "could not read ID register: %d\n", ret);
193                 return -ENODEV;
194         }
195         if ((id_reg[1] & SHTC1_ID_REG_MASK) != SHTC1_ID) {
196                 dev_err(dev, "ID register doesn't match\n");
197                 return -ENODEV;
198         }
199
200         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
201         if (!data)
202                 return -ENOMEM;
203
204         data->setup.blocking_io = false;
205         data->setup.high_precision = true;
206         data->client = client;
207
208         if (client->dev.platform_data)
209                 data->setup = *(struct shtc1_platform_data *)dev->platform_data;
210         shtc1_select_command(data);
211         mutex_init(&data->update_lock);
212
213         hwmon_dev = devm_hwmon_device_register_with_groups(dev,
214                                                            client->name,
215                                                            data,
216                                                            shtc1_groups);
217         if (IS_ERR(hwmon_dev))
218                 dev_dbg(dev, "unable to register hwmon device\n");
219
220         return PTR_ERR_OR_ZERO(hwmon_dev);
221 }
222
223 /* device ID table */
224 static const struct i2c_device_id shtc1_id[] = {
225         { "shtc1", 0 },
226         { "shtw1", 0 },
227         { }
228 };
229 MODULE_DEVICE_TABLE(i2c, shtc1_id);
230
231 static struct i2c_driver shtc1_i2c_driver = {
232         .driver.name  = "shtc1",
233         .probe        = shtc1_probe,
234         .id_table     = shtc1_id,
235 };
236
237 module_i2c_driver(shtc1_i2c_driver);
238
239 MODULE_AUTHOR("Johannes Winkelmann <johannes.winkelmann@sensirion.com>");
240 MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver");
241 MODULE_LICENSE("GPL");