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fd534e9b | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
27f8b135 IP |
2 | /* Honeywell HIH-6130/HIH-6131 humidity and temperature sensor driver |
3 | * | |
4 | * Copyright (C) 2012 Iain Paton <ipaton0@gmail.com> | |
5 | * | |
6 | * heavily based on the sht21 driver | |
7 | * Copyright (C) 2010 Urs Fleisch <urs.fleisch@sensirion.com> | |
8 | * | |
27f8b135 IP |
9 | * Data sheets available (2012-06-22) at |
10 | * http://sensing.honeywell.com/index.php?ci_id=3106&la_id=1&defId=44872 | |
11 | */ | |
12 | ||
13 | #include <linux/module.h> | |
14 | #include <linux/init.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/i2c.h> | |
17 | #include <linux/hwmon.h> | |
18 | #include <linux/hwmon-sysfs.h> | |
19 | #include <linux/err.h> | |
20 | #include <linux/mutex.h> | |
21 | #include <linux/device.h> | |
22 | #include <linux/delay.h> | |
dcd8f392 | 23 | #include <linux/jiffies.h> |
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24 | |
25 | /** | |
26 | * struct hih6130 - HIH-6130 device specific data | |
a7a9b15a | 27 | * @client: pointer to I2C client device |
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28 | * @lock: mutex to protect measurement values |
29 | * @valid: only false before first measurement is taken | |
30 | * @last_update: time of last update (jiffies) | |
31 | * @temperature: cached temperature measurement value | |
32 | * @humidity: cached humidity measurement value | |
efabcc21 | 33 | * @write_length: length for I2C measurement request |
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34 | */ |
35 | struct hih6130 { | |
a5afc18c | 36 | struct i2c_client *client; |
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37 | struct mutex lock; |
38 | bool valid; | |
39 | unsigned long last_update; | |
40 | int temperature; | |
41 | int humidity; | |
efabcc21 | 42 | size_t write_length; |
27f8b135 IP |
43 | }; |
44 | ||
45 | /** | |
46 | * hih6130_temp_ticks_to_millicelsius() - convert raw temperature ticks to | |
47 | * milli celsius | |
48 | * @ticks: temperature ticks value received from sensor | |
49 | */ | |
50 | static inline int hih6130_temp_ticks_to_millicelsius(int ticks) | |
51 | { | |
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52 | ticks = ticks >> 2; |
53 | /* | |
54 | * from data sheet section 5.0 | |
55 | * Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -40 | |
56 | */ | |
57 | return (DIV_ROUND_CLOSEST(ticks * 1650, 16382) - 400) * 100; | |
58 | } | |
59 | ||
60 | /** | |
61 | * hih6130_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to | |
62 | * one-thousandths of a percent relative humidity | |
63 | * @ticks: humidity ticks value received from sensor | |
64 | */ | |
65 | static inline int hih6130_rh_ticks_to_per_cent_mille(int ticks) | |
66 | { | |
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67 | ticks &= ~0xC000; /* clear status bits */ |
68 | /* | |
69 | * from data sheet section 4.0 | |
70 | * Formula RH = ( ticks / ( 2^14 -2 ) ) * 100 | |
71 | */ | |
72 | return DIV_ROUND_CLOSEST(ticks * 1000, 16382) * 100; | |
73 | } | |
74 | ||
75 | /** | |
76 | * hih6130_update_measurements() - get updated measurements from device | |
a5afc18c | 77 | * @dev: device |
27f8b135 IP |
78 | * |
79 | * Returns 0 on success, else negative errno. | |
80 | */ | |
a5afc18c | 81 | static int hih6130_update_measurements(struct device *dev) |
27f8b135 | 82 | { |
a5afc18c AL |
83 | struct hih6130 *hih6130 = dev_get_drvdata(dev); |
84 | struct i2c_client *client = hih6130->client; | |
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85 | int ret = 0; |
86 | int t; | |
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87 | unsigned char tmp[4]; |
88 | struct i2c_msg msgs[1] = { | |
89 | { | |
90 | .addr = client->addr, | |
91 | .flags = I2C_M_RD, | |
92 | .len = 4, | |
93 | .buf = tmp, | |
94 | } | |
95 | }; | |
96 | ||
97 | mutex_lock(&hih6130->lock); | |
98 | ||
99 | /* | |
100 | * While the measurement can be completed in ~40ms the sensor takes | |
101 | * much longer to react to a change in external conditions. How quickly | |
102 | * it reacts depends on airflow and other factors outwith our control. | |
103 | * The datasheet specifies maximum 'Response time' for humidity at 8s | |
104 | * and temperature at 30s under specified conditions. | |
105 | * We therefore choose to only read the sensor at most once per second. | |
106 | * This trades off pointless activity polling the sensor much faster | |
107 | * than it can react against better response times in conditions more | |
108 | * favourable than specified in the datasheet. | |
109 | */ | |
110 | if (time_after(jiffies, hih6130->last_update + HZ) || !hih6130->valid) { | |
111 | ||
efabcc21 JMG |
112 | /* |
113 | * Write to slave address to request a measurement. | |
114 | * According with the datasheet it should be with no data, but | |
115 | * for systems with I2C bus drivers that do not allow zero | |
116 | * length packets we write one dummy byte to allow sensor | |
117 | * measurements on them. | |
118 | */ | |
119 | tmp[0] = 0; | |
120 | ret = i2c_master_send(client, tmp, hih6130->write_length); | |
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121 | if (ret < 0) |
122 | goto out; | |
123 | ||
124 | /* measurement cycle time is ~36.65msec */ | |
125 | msleep(40); | |
126 | ||
127 | ret = i2c_transfer(client->adapter, msgs, 1); | |
128 | if (ret < 0) | |
129 | goto out; | |
130 | ||
131 | if ((tmp[0] & 0xC0) != 0) { | |
132 | dev_err(&client->dev, "Error while reading measurement result\n"); | |
133 | ret = -EIO; | |
134 | goto out; | |
135 | } | |
136 | ||
137 | t = (tmp[0] << 8) + tmp[1]; | |
138 | hih6130->humidity = hih6130_rh_ticks_to_per_cent_mille(t); | |
139 | ||
140 | t = (tmp[2] << 8) + tmp[3]; | |
141 | hih6130->temperature = hih6130_temp_ticks_to_millicelsius(t); | |
142 | ||
143 | hih6130->last_update = jiffies; | |
144 | hih6130->valid = true; | |
145 | } | |
146 | out: | |
147 | mutex_unlock(&hih6130->lock); | |
148 | ||
149 | return ret >= 0 ? 0 : ret; | |
150 | } | |
151 | ||
152 | /** | |
153 | * hih6130_show_temperature() - show temperature measurement value in sysfs | |
154 | * @dev: device | |
155 | * @attr: device attribute | |
156 | * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to | |
157 | * | |
158 | * Will be called on read access to temp1_input sysfs attribute. | |
159 | * Returns number of bytes written into buffer, negative errno on error. | |
160 | */ | |
1640bb59 | 161 | static ssize_t hih6130_temperature_show(struct device *dev, |
27f8b135 IP |
162 | struct device_attribute *attr, |
163 | char *buf) | |
164 | { | |
a5afc18c AL |
165 | struct hih6130 *hih6130 = dev_get_drvdata(dev); |
166 | int ret; | |
167 | ||
168 | ret = hih6130_update_measurements(dev); | |
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169 | if (ret < 0) |
170 | return ret; | |
171 | return sprintf(buf, "%d\n", hih6130->temperature); | |
172 | } | |
173 | ||
174 | /** | |
175 | * hih6130_show_humidity() - show humidity measurement value in sysfs | |
176 | * @dev: device | |
177 | * @attr: device attribute | |
178 | * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to | |
179 | * | |
180 | * Will be called on read access to humidity1_input sysfs attribute. | |
181 | * Returns number of bytes written into buffer, negative errno on error. | |
182 | */ | |
1640bb59 | 183 | static ssize_t hih6130_humidity_show(struct device *dev, |
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184 | struct device_attribute *attr, char *buf) |
185 | { | |
a5afc18c AL |
186 | struct hih6130 *hih6130 = dev_get_drvdata(dev); |
187 | int ret; | |
188 | ||
189 | ret = hih6130_update_measurements(dev); | |
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190 | if (ret < 0) |
191 | return ret; | |
192 | return sprintf(buf, "%d\n", hih6130->humidity); | |
193 | } | |
194 | ||
195 | /* sysfs attributes */ | |
1640bb59 GR |
196 | static SENSOR_DEVICE_ATTR_RO(temp1_input, hih6130_temperature, 0); |
197 | static SENSOR_DEVICE_ATTR_RO(humidity1_input, hih6130_humidity, 0); | |
27f8b135 | 198 | |
a5afc18c | 199 | static struct attribute *hih6130_attrs[] = { |
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200 | &sensor_dev_attr_temp1_input.dev_attr.attr, |
201 | &sensor_dev_attr_humidity1_input.dev_attr.attr, | |
202 | NULL | |
203 | }; | |
204 | ||
a5afc18c | 205 | ATTRIBUTE_GROUPS(hih6130); |
27f8b135 | 206 | |
6c931ae1 | 207 | static int hih6130_probe(struct i2c_client *client, |
27f8b135 IP |
208 | const struct i2c_device_id *id) |
209 | { | |
a5afc18c | 210 | struct device *dev = &client->dev; |
27f8b135 | 211 | struct hih6130 *hih6130; |
a5afc18c | 212 | struct device *hwmon_dev; |
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213 | |
214 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { | |
215 | dev_err(&client->dev, "adapter does not support true I2C\n"); | |
216 | return -ENODEV; | |
217 | } | |
218 | ||
a5afc18c | 219 | hih6130 = devm_kzalloc(dev, sizeof(*hih6130), GFP_KERNEL); |
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220 | if (!hih6130) |
221 | return -ENOMEM; | |
222 | ||
a5afc18c | 223 | hih6130->client = client; |
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224 | mutex_init(&hih6130->lock); |
225 | ||
eeeafd38 AL |
226 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_QUICK)) |
227 | hih6130->write_length = 1; | |
228 | ||
a5afc18c AL |
229 | hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, |
230 | hih6130, | |
231 | hih6130_groups); | |
232 | return PTR_ERR_OR_ZERO(hwmon_dev); | |
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233 | } |
234 | ||
235 | /* Device ID table */ | |
236 | static const struct i2c_device_id hih6130_id[] = { | |
237 | { "hih6130", 0 }, | |
238 | { } | |
239 | }; | |
240 | MODULE_DEVICE_TABLE(i2c, hih6130_id); | |
241 | ||
a62fe340 | 242 | static const struct of_device_id __maybe_unused hih6130_of_match[] = { |
89bff8c2 AK |
243 | { .compatible = "honeywell,hih6130", }, |
244 | { } | |
245 | }; | |
246 | MODULE_DEVICE_TABLE(of, hih6130_of_match); | |
247 | ||
27f8b135 | 248 | static struct i2c_driver hih6130_driver = { |
89bff8c2 AK |
249 | .driver = { |
250 | .name = "hih6130", | |
251 | .of_match_table = of_match_ptr(hih6130_of_match), | |
252 | }, | |
27f8b135 | 253 | .probe = hih6130_probe, |
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254 | .id_table = hih6130_id, |
255 | }; | |
256 | ||
257 | module_i2c_driver(hih6130_driver); | |
258 | ||
259 | MODULE_AUTHOR("Iain Paton <ipaton0@gmail.com>"); | |
260 | MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver"); | |
261 | MODULE_LICENSE("GPL"); |