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c942fddf | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1a539d37 TP |
2 | /* Sensirion SHTC1 humidity and temperature sensor driver |
3 | * | |
4 | * Copyright (C) 2014 Sensirion AG, Switzerland | |
5 | * Author: Johannes Winkelmann <johannes.winkelmann@sensirion.com> | |
1a539d37 TP |
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 */ | |
ffd96868 | 27 | static const unsigned char shtc1_cmd_read_id_reg[] = { 0xef, 0xc8 }; |
1a539d37 | 28 | |
ffd96868 DR |
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 | |
1a539d37 TP |
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 | |
ffd96868 DR |
43 | #define SHTC3_NONBLOCKING_WAIT_TIME_HPM 12100 |
44 | #define SHTC3_NONBLOCKING_WAIT_TIME_LPM 800 | |
1a539d37 TP |
45 | |
46 | #define SHTC1_CMD_LENGTH 2 | |
47 | #define SHTC1_RESPONSE_LENGTH 6 | |
48 | ||
ffd96868 DR |
49 | enum shtcx_chips { |
50 | shtc1, | |
51 | shtc3, | |
52 | }; | |
53 | ||
1a539d37 TP |
54 | struct 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; | |
ffd96868 | 64 | enum shtcx_chips chip; |
1a539d37 TP |
65 | |
66 | int temperature; /* 1000 * temperature in dgr C */ | |
67 | int humidity; /* 1000 * relative humidity in %RH */ | |
68 | }; | |
69 | ||
70 | static 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 */ | |
100 | static 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 | ||
131 | out: | |
132 | mutex_unlock(&data->update_lock); | |
133 | ||
134 | return ret == 0 ? data : ERR_PTR(ret); | |
135 | } | |
136 | ||
137 | static 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 | ||
148 | static 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 | ||
158 | static DEVICE_ATTR_RO(temp1_input); | |
159 | static DEVICE_ATTR_RO(humidity1_input); | |
160 | ||
161 | static struct attribute *shtc1_attrs[] = { | |
162 | &dev_attr_temp1_input.attr, | |
163 | &dev_attr_humidity1_input.attr, | |
164 | NULL | |
165 | }; | |
166 | ||
167 | ATTRIBUTE_GROUPS(shtc1); | |
168 | ||
169 | static 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; | |
ffd96868 DR |
175 | data->nonblocking_wait_time = (data->chip == shtc1) ? |
176 | SHTC1_NONBLOCKING_WAIT_TIME_HPM : | |
177 | SHTC3_NONBLOCKING_WAIT_TIME_HPM; | |
1a539d37 TP |
178 | } else { |
179 | data->command = data->setup.blocking_io ? | |
180 | shtc1_cmd_measure_blocking_lpm : | |
181 | shtc1_cmd_measure_nonblocking_lpm; | |
ffd96868 DR |
182 | data->nonblocking_wait_time = (data->chip == shtc1) ? |
183 | SHTC1_NONBLOCKING_WAIT_TIME_LPM : | |
184 | SHTC3_NONBLOCKING_WAIT_TIME_LPM; | |
1a539d37 TP |
185 | } |
186 | } | |
187 | ||
188 | static int shtc1_probe(struct i2c_client *client, | |
189 | const struct i2c_device_id *id) | |
190 | { | |
191 | int ret; | |
ffd96868 DR |
192 | u16 id_reg; |
193 | char id_reg_buf[2]; | |
1a539d37 TP |
194 | struct shtc1_data *data; |
195 | struct device *hwmon_dev; | |
ffd96868 | 196 | enum shtcx_chips chip = id->driver_data; |
1a539d37 TP |
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 | } | |
ffd96868 DR |
210 | ret = i2c_master_recv(client, id_reg_buf, sizeof(id_reg_buf)); |
211 | if (ret != sizeof(id_reg_buf)) { | |
1a539d37 TP |
212 | dev_err(dev, "could not read ID register: %d\n", ret); |
213 | return -ENODEV; | |
214 | } | |
ffd96868 DR |
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"); | |
1a539d37 TP |
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; | |
ffd96868 | 234 | data->chip = chip; |
1a539d37 TP |
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 */ | |
252 | static const struct i2c_device_id shtc1_id[] = { | |
ffd96868 DR |
253 | { "shtc1", shtc1 }, |
254 | { "shtw1", shtc1 }, | |
255 | { "shtc3", shtc3 }, | |
1a539d37 TP |
256 | { } |
257 | }; | |
258 | MODULE_DEVICE_TABLE(i2c, shtc1_id); | |
259 | ||
260 | static struct i2c_driver shtc1_i2c_driver = { | |
261 | .driver.name = "shtc1", | |
262 | .probe = shtc1_probe, | |
263 | .id_table = shtc1_id, | |
264 | }; | |
265 | ||
266 | module_i2c_driver(shtc1_i2c_driver); | |
267 | ||
268 | MODULE_AUTHOR("Johannes Winkelmann <johannes.winkelmann@sensirion.com>"); | |
269 | MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver"); | |
270 | MODULE_LICENSE("GPL"); |