Commit | Line | Data |
---|---|---|
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> | |
36 | ||
37 | /** | |
38 | * struct hih6130 - HIH-6130 device specific data | |
39 | * @hwmon_dev: device registered with hwmon | |
40 | * @lock: mutex to protect measurement values | |
41 | * @valid: only false before first measurement is taken | |
42 | * @last_update: time of last update (jiffies) | |
43 | * @temperature: cached temperature measurement value | |
44 | * @humidity: cached humidity measurement value | |
45 | */ | |
46 | struct hih6130 { | |
47 | struct device *hwmon_dev; | |
48 | struct mutex lock; | |
49 | bool valid; | |
50 | unsigned long last_update; | |
51 | int temperature; | |
52 | int humidity; | |
53 | }; | |
54 | ||
55 | /** | |
56 | * hih6130_temp_ticks_to_millicelsius() - convert raw temperature ticks to | |
57 | * milli celsius | |
58 | * @ticks: temperature ticks value received from sensor | |
59 | */ | |
60 | static inline int hih6130_temp_ticks_to_millicelsius(int ticks) | |
61 | { | |
62 | ||
63 | ticks = ticks >> 2; | |
64 | /* | |
65 | * from data sheet section 5.0 | |
66 | * Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -40 | |
67 | */ | |
68 | return (DIV_ROUND_CLOSEST(ticks * 1650, 16382) - 400) * 100; | |
69 | } | |
70 | ||
71 | /** | |
72 | * hih6130_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to | |
73 | * one-thousandths of a percent relative humidity | |
74 | * @ticks: humidity ticks value received from sensor | |
75 | */ | |
76 | static inline int hih6130_rh_ticks_to_per_cent_mille(int ticks) | |
77 | { | |
78 | ||
79 | ticks &= ~0xC000; /* clear status bits */ | |
80 | /* | |
81 | * from data sheet section 4.0 | |
82 | * Formula RH = ( ticks / ( 2^14 -2 ) ) * 100 | |
83 | */ | |
84 | return DIV_ROUND_CLOSEST(ticks * 1000, 16382) * 100; | |
85 | } | |
86 | ||
87 | /** | |
88 | * hih6130_update_measurements() - get updated measurements from device | |
89 | * @client: I2C client device | |
90 | * | |
91 | * Returns 0 on success, else negative errno. | |
92 | */ | |
93 | static int hih6130_update_measurements(struct i2c_client *client) | |
94 | { | |
95 | int ret = 0; | |
96 | int t; | |
97 | struct hih6130 *hih6130 = i2c_get_clientdata(client); | |
98 | unsigned char tmp[4]; | |
99 | struct i2c_msg msgs[1] = { | |
100 | { | |
101 | .addr = client->addr, | |
102 | .flags = I2C_M_RD, | |
103 | .len = 4, | |
104 | .buf = tmp, | |
105 | } | |
106 | }; | |
107 | ||
108 | mutex_lock(&hih6130->lock); | |
109 | ||
110 | /* | |
111 | * While the measurement can be completed in ~40ms the sensor takes | |
112 | * much longer to react to a change in external conditions. How quickly | |
113 | * it reacts depends on airflow and other factors outwith our control. | |
114 | * The datasheet specifies maximum 'Response time' for humidity at 8s | |
115 | * and temperature at 30s under specified conditions. | |
116 | * We therefore choose to only read the sensor at most once per second. | |
117 | * This trades off pointless activity polling the sensor much faster | |
118 | * than it can react against better response times in conditions more | |
119 | * favourable than specified in the datasheet. | |
120 | */ | |
121 | if (time_after(jiffies, hih6130->last_update + HZ) || !hih6130->valid) { | |
122 | ||
123 | /* write to slave address, no data, to request a measurement */ | |
124 | ret = i2c_master_send(client, tmp, 0); | |
125 | if (ret < 0) | |
126 | goto out; | |
127 | ||
128 | /* measurement cycle time is ~36.65msec */ | |
129 | msleep(40); | |
130 | ||
131 | ret = i2c_transfer(client->adapter, msgs, 1); | |
132 | if (ret < 0) | |
133 | goto out; | |
134 | ||
135 | if ((tmp[0] & 0xC0) != 0) { | |
136 | dev_err(&client->dev, "Error while reading measurement result\n"); | |
137 | ret = -EIO; | |
138 | goto out; | |
139 | } | |
140 | ||
141 | t = (tmp[0] << 8) + tmp[1]; | |
142 | hih6130->humidity = hih6130_rh_ticks_to_per_cent_mille(t); | |
143 | ||
144 | t = (tmp[2] << 8) + tmp[3]; | |
145 | hih6130->temperature = hih6130_temp_ticks_to_millicelsius(t); | |
146 | ||
147 | hih6130->last_update = jiffies; | |
148 | hih6130->valid = true; | |
149 | } | |
150 | out: | |
151 | mutex_unlock(&hih6130->lock); | |
152 | ||
153 | return ret >= 0 ? 0 : ret; | |
154 | } | |
155 | ||
156 | /** | |
157 | * hih6130_show_temperature() - show temperature measurement value in sysfs | |
158 | * @dev: device | |
159 | * @attr: device attribute | |
160 | * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to | |
161 | * | |
162 | * Will be called on read access to temp1_input sysfs attribute. | |
163 | * Returns number of bytes written into buffer, negative errno on error. | |
164 | */ | |
165 | static ssize_t hih6130_show_temperature(struct device *dev, | |
166 | struct device_attribute *attr, | |
167 | char *buf) | |
168 | { | |
169 | struct i2c_client *client = to_i2c_client(dev); | |
170 | struct hih6130 *hih6130 = i2c_get_clientdata(client); | |
171 | int ret = hih6130_update_measurements(client); | |
172 | if (ret < 0) | |
173 | return ret; | |
174 | return sprintf(buf, "%d\n", hih6130->temperature); | |
175 | } | |
176 | ||
177 | /** | |
178 | * hih6130_show_humidity() - show humidity measurement value in sysfs | |
179 | * @dev: device | |
180 | * @attr: device attribute | |
181 | * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to | |
182 | * | |
183 | * Will be called on read access to humidity1_input sysfs attribute. | |
184 | * Returns number of bytes written into buffer, negative errno on error. | |
185 | */ | |
186 | static ssize_t hih6130_show_humidity(struct device *dev, | |
187 | struct device_attribute *attr, char *buf) | |
188 | { | |
189 | struct i2c_client *client = to_i2c_client(dev); | |
190 | struct hih6130 *hih6130 = i2c_get_clientdata(client); | |
191 | int ret = hih6130_update_measurements(client); | |
192 | if (ret < 0) | |
193 | return ret; | |
194 | return sprintf(buf, "%d\n", hih6130->humidity); | |
195 | } | |
196 | ||
197 | /* sysfs attributes */ | |
198 | static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, hih6130_show_temperature, | |
199 | NULL, 0); | |
200 | static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, hih6130_show_humidity, | |
201 | NULL, 0); | |
202 | ||
203 | static struct attribute *hih6130_attributes[] = { | |
204 | &sensor_dev_attr_temp1_input.dev_attr.attr, | |
205 | &sensor_dev_attr_humidity1_input.dev_attr.attr, | |
206 | NULL | |
207 | }; | |
208 | ||
209 | static const struct attribute_group hih6130_attr_group = { | |
210 | .attrs = hih6130_attributes, | |
211 | }; | |
212 | ||
213 | /** | |
214 | * hih6130_probe() - probe device | |
215 | * @client: I2C client device | |
216 | * @id: device ID | |
217 | * | |
218 | * Called by the I2C core when an entry in the ID table matches a | |
219 | * device's name. | |
220 | * Returns 0 on success. | |
221 | */ | |
222 | static int __devinit hih6130_probe(struct i2c_client *client, | |
223 | const struct i2c_device_id *id) | |
224 | { | |
225 | struct hih6130 *hih6130; | |
226 | int err; | |
227 | ||
228 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { | |
229 | dev_err(&client->dev, "adapter does not support true I2C\n"); | |
230 | return -ENODEV; | |
231 | } | |
232 | ||
233 | hih6130 = devm_kzalloc(&client->dev, sizeof(*hih6130), GFP_KERNEL); | |
234 | if (!hih6130) | |
235 | return -ENOMEM; | |
236 | ||
237 | i2c_set_clientdata(client, hih6130); | |
238 | ||
239 | mutex_init(&hih6130->lock); | |
240 | ||
241 | err = sysfs_create_group(&client->dev.kobj, &hih6130_attr_group); | |
242 | if (err) { | |
243 | dev_dbg(&client->dev, "could not create sysfs files\n"); | |
244 | return err; | |
245 | } | |
246 | ||
247 | hih6130->hwmon_dev = hwmon_device_register(&client->dev); | |
248 | if (IS_ERR(hih6130->hwmon_dev)) { | |
249 | dev_dbg(&client->dev, "unable to register hwmon device\n"); | |
250 | err = PTR_ERR(hih6130->hwmon_dev); | |
251 | goto fail_remove_sysfs; | |
252 | } | |
253 | ||
254 | return 0; | |
255 | ||
256 | fail_remove_sysfs: | |
257 | sysfs_remove_group(&client->dev.kobj, &hih6130_attr_group); | |
258 | return err; | |
259 | } | |
260 | ||
261 | /** | |
262 | * hih6130_remove() - remove device | |
263 | * @client: I2C client device | |
264 | */ | |
265 | static int __devexit hih6130_remove(struct i2c_client *client) | |
266 | { | |
267 | struct hih6130 *hih6130 = i2c_get_clientdata(client); | |
268 | ||
269 | hwmon_device_unregister(hih6130->hwmon_dev); | |
270 | sysfs_remove_group(&client->dev.kobj, &hih6130_attr_group); | |
271 | ||
272 | return 0; | |
273 | } | |
274 | ||
275 | /* Device ID table */ | |
276 | static const struct i2c_device_id hih6130_id[] = { | |
277 | { "hih6130", 0 }, | |
278 | { } | |
279 | }; | |
280 | MODULE_DEVICE_TABLE(i2c, hih6130_id); | |
281 | ||
282 | static struct i2c_driver hih6130_driver = { | |
283 | .driver.name = "hih6130", | |
284 | .probe = hih6130_probe, | |
285 | .remove = __devexit_p(hih6130_remove), | |
286 | .id_table = hih6130_id, | |
287 | }; | |
288 | ||
289 | module_i2c_driver(hih6130_driver); | |
290 | ||
291 | MODULE_AUTHOR("Iain Paton <ipaton0@gmail.com>"); | |
292 | MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver"); | |
293 | MODULE_LICENSE("GPL"); |