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27f8b135 IP |
1 | /* Honeywell HIH-6130/HIH-6131 humidity and temperature sensor driver |
2 | * | |
3 | * Copyright (C) 2012 Iain Paton <ipaton0@gmail.com> | |
4 | * | |
5 | * heavily based on the sht21 driver | |
6 | * Copyright (C) 2010 Urs Fleisch <urs.fleisch@sensirion.com> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA | |
21 | * | |
22 | * Data sheets available (2012-06-22) at | |
23 | * http://sensing.honeywell.com/index.php?ci_id=3106&la_id=1&defId=44872 | |
24 | */ | |
25 | ||
26 | #include <linux/module.h> | |
27 | #include <linux/init.h> | |
28 | #include <linux/slab.h> | |
29 | #include <linux/i2c.h> | |
30 | #include <linux/hwmon.h> | |
31 | #include <linux/hwmon-sysfs.h> | |
32 | #include <linux/err.h> | |
33 | #include <linux/mutex.h> | |
34 | #include <linux/device.h> | |
35 | #include <linux/delay.h> | |
dcd8f392 | 36 | #include <linux/jiffies.h> |
27f8b135 IP |
37 | |
38 | /** | |
39 | * struct hih6130 - HIH-6130 device specific data | |
40 | * @hwmon_dev: device registered with hwmon | |
41 | * @lock: mutex to protect measurement values | |
42 | * @valid: only false before first measurement is taken | |
43 | * @last_update: time of last update (jiffies) | |
44 | * @temperature: cached temperature measurement value | |
45 | * @humidity: cached humidity measurement value | |
efabcc21 | 46 | * @write_length: length for I2C measurement request |
27f8b135 IP |
47 | */ |
48 | struct hih6130 { | |
49 | struct device *hwmon_dev; | |
50 | struct mutex lock; | |
51 | bool valid; | |
52 | unsigned long last_update; | |
53 | int temperature; | |
54 | int humidity; | |
efabcc21 | 55 | size_t write_length; |
27f8b135 IP |
56 | }; |
57 | ||
58 | /** | |
59 | * hih6130_temp_ticks_to_millicelsius() - convert raw temperature ticks to | |
60 | * milli celsius | |
61 | * @ticks: temperature ticks value received from sensor | |
62 | */ | |
63 | static inline int hih6130_temp_ticks_to_millicelsius(int ticks) | |
64 | { | |
65 | ||
66 | ticks = ticks >> 2; | |
67 | /* | |
68 | * from data sheet section 5.0 | |
69 | * Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -40 | |
70 | */ | |
71 | return (DIV_ROUND_CLOSEST(ticks * 1650, 16382) - 400) * 100; | |
72 | } | |
73 | ||
74 | /** | |
75 | * hih6130_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to | |
76 | * one-thousandths of a percent relative humidity | |
77 | * @ticks: humidity ticks value received from sensor | |
78 | */ | |
79 | static inline int hih6130_rh_ticks_to_per_cent_mille(int ticks) | |
80 | { | |
81 | ||
82 | ticks &= ~0xC000; /* clear status bits */ | |
83 | /* | |
84 | * from data sheet section 4.0 | |
85 | * Formula RH = ( ticks / ( 2^14 -2 ) ) * 100 | |
86 | */ | |
87 | return DIV_ROUND_CLOSEST(ticks * 1000, 16382) * 100; | |
88 | } | |
89 | ||
90 | /** | |
91 | * hih6130_update_measurements() - get updated measurements from device | |
92 | * @client: I2C client device | |
93 | * | |
94 | * Returns 0 on success, else negative errno. | |
95 | */ | |
96 | static int hih6130_update_measurements(struct i2c_client *client) | |
97 | { | |
98 | int ret = 0; | |
99 | int t; | |
100 | struct hih6130 *hih6130 = i2c_get_clientdata(client); | |
101 | unsigned char tmp[4]; | |
102 | struct i2c_msg msgs[1] = { | |
103 | { | |
104 | .addr = client->addr, | |
105 | .flags = I2C_M_RD, | |
106 | .len = 4, | |
107 | .buf = tmp, | |
108 | } | |
109 | }; | |
110 | ||
111 | mutex_lock(&hih6130->lock); | |
112 | ||
113 | /* | |
114 | * While the measurement can be completed in ~40ms the sensor takes | |
115 | * much longer to react to a change in external conditions. How quickly | |
116 | * it reacts depends on airflow and other factors outwith our control. | |
117 | * The datasheet specifies maximum 'Response time' for humidity at 8s | |
118 | * and temperature at 30s under specified conditions. | |
119 | * We therefore choose to only read the sensor at most once per second. | |
120 | * This trades off pointless activity polling the sensor much faster | |
121 | * than it can react against better response times in conditions more | |
122 | * favourable than specified in the datasheet. | |
123 | */ | |
124 | if (time_after(jiffies, hih6130->last_update + HZ) || !hih6130->valid) { | |
125 | ||
efabcc21 JMG |
126 | /* |
127 | * Write to slave address to request a measurement. | |
128 | * According with the datasheet it should be with no data, but | |
129 | * for systems with I2C bus drivers that do not allow zero | |
130 | * length packets we write one dummy byte to allow sensor | |
131 | * measurements on them. | |
132 | */ | |
133 | tmp[0] = 0; | |
134 | ret = i2c_master_send(client, tmp, hih6130->write_length); | |
27f8b135 IP |
135 | if (ret < 0) |
136 | goto out; | |
137 | ||
138 | /* measurement cycle time is ~36.65msec */ | |
139 | msleep(40); | |
140 | ||
141 | ret = i2c_transfer(client->adapter, msgs, 1); | |
142 | if (ret < 0) | |
143 | goto out; | |
144 | ||
145 | if ((tmp[0] & 0xC0) != 0) { | |
146 | dev_err(&client->dev, "Error while reading measurement result\n"); | |
147 | ret = -EIO; | |
148 | goto out; | |
149 | } | |
150 | ||
151 | t = (tmp[0] << 8) + tmp[1]; | |
152 | hih6130->humidity = hih6130_rh_ticks_to_per_cent_mille(t); | |
153 | ||
154 | t = (tmp[2] << 8) + tmp[3]; | |
155 | hih6130->temperature = hih6130_temp_ticks_to_millicelsius(t); | |
156 | ||
157 | hih6130->last_update = jiffies; | |
158 | hih6130->valid = true; | |
159 | } | |
160 | out: | |
161 | mutex_unlock(&hih6130->lock); | |
162 | ||
163 | return ret >= 0 ? 0 : ret; | |
164 | } | |
165 | ||
166 | /** | |
167 | * hih6130_show_temperature() - show temperature measurement value in sysfs | |
168 | * @dev: device | |
169 | * @attr: device attribute | |
170 | * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to | |
171 | * | |
172 | * Will be called on read access to temp1_input sysfs attribute. | |
173 | * Returns number of bytes written into buffer, negative errno on error. | |
174 | */ | |
175 | static ssize_t hih6130_show_temperature(struct device *dev, | |
176 | struct device_attribute *attr, | |
177 | char *buf) | |
178 | { | |
179 | struct i2c_client *client = to_i2c_client(dev); | |
180 | struct hih6130 *hih6130 = i2c_get_clientdata(client); | |
181 | int ret = hih6130_update_measurements(client); | |
182 | if (ret < 0) | |
183 | return ret; | |
184 | return sprintf(buf, "%d\n", hih6130->temperature); | |
185 | } | |
186 | ||
187 | /** | |
188 | * hih6130_show_humidity() - show humidity measurement value in sysfs | |
189 | * @dev: device | |
190 | * @attr: device attribute | |
191 | * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to | |
192 | * | |
193 | * Will be called on read access to humidity1_input sysfs attribute. | |
194 | * Returns number of bytes written into buffer, negative errno on error. | |
195 | */ | |
196 | static ssize_t hih6130_show_humidity(struct device *dev, | |
197 | struct device_attribute *attr, char *buf) | |
198 | { | |
199 | struct i2c_client *client = to_i2c_client(dev); | |
200 | struct hih6130 *hih6130 = i2c_get_clientdata(client); | |
201 | int ret = hih6130_update_measurements(client); | |
202 | if (ret < 0) | |
203 | return ret; | |
204 | return sprintf(buf, "%d\n", hih6130->humidity); | |
205 | } | |
206 | ||
207 | /* sysfs attributes */ | |
208 | static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, hih6130_show_temperature, | |
209 | NULL, 0); | |
210 | static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, hih6130_show_humidity, | |
211 | NULL, 0); | |
212 | ||
213 | static struct attribute *hih6130_attributes[] = { | |
214 | &sensor_dev_attr_temp1_input.dev_attr.attr, | |
215 | &sensor_dev_attr_humidity1_input.dev_attr.attr, | |
216 | NULL | |
217 | }; | |
218 | ||
219 | static const struct attribute_group hih6130_attr_group = { | |
220 | .attrs = hih6130_attributes, | |
221 | }; | |
222 | ||
223 | /** | |
224 | * hih6130_probe() - probe device | |
225 | * @client: I2C client device | |
226 | * @id: device ID | |
227 | * | |
228 | * Called by the I2C core when an entry in the ID table matches a | |
229 | * device's name. | |
230 | * Returns 0 on success. | |
231 | */ | |
6c931ae1 | 232 | static int hih6130_probe(struct i2c_client *client, |
27f8b135 IP |
233 | const struct i2c_device_id *id) |
234 | { | |
235 | struct hih6130 *hih6130; | |
236 | int err; | |
237 | ||
238 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { | |
239 | dev_err(&client->dev, "adapter does not support true I2C\n"); | |
240 | return -ENODEV; | |
241 | } | |
242 | ||
243 | hih6130 = devm_kzalloc(&client->dev, sizeof(*hih6130), GFP_KERNEL); | |
244 | if (!hih6130) | |
245 | return -ENOMEM; | |
246 | ||
247 | i2c_set_clientdata(client, hih6130); | |
248 | ||
249 | mutex_init(&hih6130->lock); | |
250 | ||
251 | err = sysfs_create_group(&client->dev.kobj, &hih6130_attr_group); | |
252 | if (err) { | |
253 | dev_dbg(&client->dev, "could not create sysfs files\n"); | |
254 | return err; | |
255 | } | |
256 | ||
257 | hih6130->hwmon_dev = hwmon_device_register(&client->dev); | |
258 | if (IS_ERR(hih6130->hwmon_dev)) { | |
259 | dev_dbg(&client->dev, "unable to register hwmon device\n"); | |
260 | err = PTR_ERR(hih6130->hwmon_dev); | |
261 | goto fail_remove_sysfs; | |
262 | } | |
263 | ||
efabcc21 JMG |
264 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_QUICK)) |
265 | hih6130->write_length = 1; | |
266 | ||
27f8b135 IP |
267 | return 0; |
268 | ||
269 | fail_remove_sysfs: | |
270 | sysfs_remove_group(&client->dev.kobj, &hih6130_attr_group); | |
271 | return err; | |
272 | } | |
273 | ||
274 | /** | |
275 | * hih6130_remove() - remove device | |
276 | * @client: I2C client device | |
277 | */ | |
281dfd0b | 278 | static int hih6130_remove(struct i2c_client *client) |
27f8b135 IP |
279 | { |
280 | struct hih6130 *hih6130 = i2c_get_clientdata(client); | |
281 | ||
282 | hwmon_device_unregister(hih6130->hwmon_dev); | |
283 | sysfs_remove_group(&client->dev.kobj, &hih6130_attr_group); | |
284 | ||
285 | return 0; | |
286 | } | |
287 | ||
288 | /* Device ID table */ | |
289 | static const struct i2c_device_id hih6130_id[] = { | |
290 | { "hih6130", 0 }, | |
291 | { } | |
292 | }; | |
293 | MODULE_DEVICE_TABLE(i2c, hih6130_id); | |
294 | ||
295 | static struct i2c_driver hih6130_driver = { | |
296 | .driver.name = "hih6130", | |
297 | .probe = hih6130_probe, | |
9e5e9b7a | 298 | .remove = hih6130_remove, |
27f8b135 IP |
299 | .id_table = hih6130_id, |
300 | }; | |
301 | ||
302 | module_i2c_driver(hih6130_driver); | |
303 | ||
304 | MODULE_AUTHOR("Iain Paton <ipaton0@gmail.com>"); | |
305 | MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver"); | |
306 | MODULE_LICENSE("GPL"); |