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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> |
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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 |
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47 | */ |
48 | struct hih6130 { | |
a5afc18c | 49 | struct i2c_client *client; |
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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 | { | |
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65 | ticks = ticks >> 2; |
66 | /* | |
67 | * from data sheet section 5.0 | |
68 | * Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -40 | |
69 | */ | |
70 | return (DIV_ROUND_CLOSEST(ticks * 1650, 16382) - 400) * 100; | |
71 | } | |
72 | ||
73 | /** | |
74 | * hih6130_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to | |
75 | * one-thousandths of a percent relative humidity | |
76 | * @ticks: humidity ticks value received from sensor | |
77 | */ | |
78 | static inline int hih6130_rh_ticks_to_per_cent_mille(int ticks) | |
79 | { | |
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80 | ticks &= ~0xC000; /* clear status bits */ |
81 | /* | |
82 | * from data sheet section 4.0 | |
83 | * Formula RH = ( ticks / ( 2^14 -2 ) ) * 100 | |
84 | */ | |
85 | return DIV_ROUND_CLOSEST(ticks * 1000, 16382) * 100; | |
86 | } | |
87 | ||
88 | /** | |
89 | * hih6130_update_measurements() - get updated measurements from device | |
a5afc18c | 90 | * @dev: device |
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91 | * |
92 | * Returns 0 on success, else negative errno. | |
93 | */ | |
a5afc18c | 94 | static int hih6130_update_measurements(struct device *dev) |
27f8b135 | 95 | { |
a5afc18c AL |
96 | struct hih6130 *hih6130 = dev_get_drvdata(dev); |
97 | struct i2c_client *client = hih6130->client; | |
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98 | int ret = 0; |
99 | int t; | |
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100 | unsigned char tmp[4]; |
101 | struct i2c_msg msgs[1] = { | |
102 | { | |
103 | .addr = client->addr, | |
104 | .flags = I2C_M_RD, | |
105 | .len = 4, | |
106 | .buf = tmp, | |
107 | } | |
108 | }; | |
109 | ||
110 | mutex_lock(&hih6130->lock); | |
111 | ||
112 | /* | |
113 | * While the measurement can be completed in ~40ms the sensor takes | |
114 | * much longer to react to a change in external conditions. How quickly | |
115 | * it reacts depends on airflow and other factors outwith our control. | |
116 | * The datasheet specifies maximum 'Response time' for humidity at 8s | |
117 | * and temperature at 30s under specified conditions. | |
118 | * We therefore choose to only read the sensor at most once per second. | |
119 | * This trades off pointless activity polling the sensor much faster | |
120 | * than it can react against better response times in conditions more | |
121 | * favourable than specified in the datasheet. | |
122 | */ | |
123 | if (time_after(jiffies, hih6130->last_update + HZ) || !hih6130->valid) { | |
124 | ||
efabcc21 JMG |
125 | /* |
126 | * Write to slave address to request a measurement. | |
127 | * According with the datasheet it should be with no data, but | |
128 | * for systems with I2C bus drivers that do not allow zero | |
129 | * length packets we write one dummy byte to allow sensor | |
130 | * measurements on them. | |
131 | */ | |
132 | tmp[0] = 0; | |
133 | ret = i2c_master_send(client, tmp, hih6130->write_length); | |
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134 | if (ret < 0) |
135 | goto out; | |
136 | ||
137 | /* measurement cycle time is ~36.65msec */ | |
138 | msleep(40); | |
139 | ||
140 | ret = i2c_transfer(client->adapter, msgs, 1); | |
141 | if (ret < 0) | |
142 | goto out; | |
143 | ||
144 | if ((tmp[0] & 0xC0) != 0) { | |
145 | dev_err(&client->dev, "Error while reading measurement result\n"); | |
146 | ret = -EIO; | |
147 | goto out; | |
148 | } | |
149 | ||
150 | t = (tmp[0] << 8) + tmp[1]; | |
151 | hih6130->humidity = hih6130_rh_ticks_to_per_cent_mille(t); | |
152 | ||
153 | t = (tmp[2] << 8) + tmp[3]; | |
154 | hih6130->temperature = hih6130_temp_ticks_to_millicelsius(t); | |
155 | ||
156 | hih6130->last_update = jiffies; | |
157 | hih6130->valid = true; | |
158 | } | |
159 | out: | |
160 | mutex_unlock(&hih6130->lock); | |
161 | ||
162 | return ret >= 0 ? 0 : ret; | |
163 | } | |
164 | ||
165 | /** | |
166 | * hih6130_show_temperature() - show temperature measurement value in sysfs | |
167 | * @dev: device | |
168 | * @attr: device attribute | |
169 | * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to | |
170 | * | |
171 | * Will be called on read access to temp1_input sysfs attribute. | |
172 | * Returns number of bytes written into buffer, negative errno on error. | |
173 | */ | |
174 | static ssize_t hih6130_show_temperature(struct device *dev, | |
175 | struct device_attribute *attr, | |
176 | char *buf) | |
177 | { | |
a5afc18c AL |
178 | struct hih6130 *hih6130 = dev_get_drvdata(dev); |
179 | int ret; | |
180 | ||
181 | ret = hih6130_update_measurements(dev); | |
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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 | { | |
a5afc18c AL |
199 | struct hih6130 *hih6130 = dev_get_drvdata(dev); |
200 | int ret; | |
201 | ||
202 | ret = hih6130_update_measurements(dev); | |
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203 | if (ret < 0) |
204 | return ret; | |
205 | return sprintf(buf, "%d\n", hih6130->humidity); | |
206 | } | |
207 | ||
208 | /* sysfs attributes */ | |
209 | static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, hih6130_show_temperature, | |
210 | NULL, 0); | |
211 | static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, hih6130_show_humidity, | |
212 | NULL, 0); | |
213 | ||
a5afc18c | 214 | static struct attribute *hih6130_attrs[] = { |
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215 | &sensor_dev_attr_temp1_input.dev_attr.attr, |
216 | &sensor_dev_attr_humidity1_input.dev_attr.attr, | |
217 | NULL | |
218 | }; | |
219 | ||
a5afc18c | 220 | ATTRIBUTE_GROUPS(hih6130); |
27f8b135 | 221 | |
6c931ae1 | 222 | static int hih6130_probe(struct i2c_client *client, |
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223 | const struct i2c_device_id *id) |
224 | { | |
a5afc18c | 225 | struct device *dev = &client->dev; |
27f8b135 | 226 | struct hih6130 *hih6130; |
a5afc18c | 227 | struct device *hwmon_dev; |
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228 | |
229 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { | |
230 | dev_err(&client->dev, "adapter does not support true I2C\n"); | |
231 | return -ENODEV; | |
232 | } | |
233 | ||
a5afc18c | 234 | hih6130 = devm_kzalloc(dev, sizeof(*hih6130), GFP_KERNEL); |
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235 | if (!hih6130) |
236 | return -ENOMEM; | |
237 | ||
a5afc18c | 238 | hih6130->client = client; |
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239 | mutex_init(&hih6130->lock); |
240 | ||
eeeafd38 AL |
241 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_QUICK)) |
242 | hih6130->write_length = 1; | |
243 | ||
a5afc18c AL |
244 | hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, |
245 | hih6130, | |
246 | hih6130_groups); | |
247 | return PTR_ERR_OR_ZERO(hwmon_dev); | |
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248 | } |
249 | ||
250 | /* Device ID table */ | |
251 | static const struct i2c_device_id hih6130_id[] = { | |
252 | { "hih6130", 0 }, | |
253 | { } | |
254 | }; | |
255 | MODULE_DEVICE_TABLE(i2c, hih6130_id); | |
256 | ||
257 | static struct i2c_driver hih6130_driver = { | |
258 | .driver.name = "hih6130", | |
259 | .probe = hih6130_probe, | |
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260 | .id_table = hih6130_id, |
261 | }; | |
262 | ||
263 | module_i2c_driver(hih6130_driver); | |
264 | ||
265 | MODULE_AUTHOR("Iain Paton <ipaton0@gmail.com>"); | |
266 | MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver"); | |
267 | MODULE_LICENSE("GPL"); |