1 | // SPDX-License-Identifier: GPL-2.0-or-later |
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 | * |
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> |
23 | #include <linux/jiffies.h> |
24 | |
25 | /** |
26 | * struct hih6130 - HIH-6130 device specific data |
27 | * @client: pointer to I2C client device |
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 |
33 | * @write_length: length for I2C measurement request |
34 | */ |
35 | struct hih6130 { |
36 | struct i2c_client *client; |
37 | struct mutex lock; |
38 | bool valid; |
39 | unsigned long last_update; |
40 | int temperature; |
41 | int humidity; |
42 | size_t write_length; |
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 | { |
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 | { |
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 |
77 | * @dev: device |
78 | * |
79 | * Returns 0 on success, else negative errno. |
80 | */ |
81 | static int hih6130_update_measurements(struct device *dev) |
82 | { |
83 | struct hih6130 *hih6130 = dev_get_drvdata(dev); |
84 | struct i2c_client *client = hih6130->client; |
85 | int ret = 0; |
86 | int t; |
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 | |
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, buf: tmp, count: hih6130->write_length); |
121 | if (ret < 0) |
122 | goto out; |
123 | |
124 | /* measurement cycle time is ~36.65msec */ |
125 | msleep(msecs: 40); |
126 | |
127 | ret = i2c_transfer(adap: client->adapter, msgs, num: 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(ticks: t); |
139 | |
140 | t = (tmp[2] << 8) + tmp[3]; |
141 | hih6130->temperature = hih6130_temp_ticks_to_millicelsius(ticks: t); |
142 | |
143 | hih6130->last_update = jiffies; |
144 | hih6130->valid = true; |
145 | } |
146 | out: |
147 | mutex_unlock(lock: &hih6130->lock); |
148 | |
149 | return ret >= 0 ? 0 : ret; |
150 | } |
151 | |
152 | /** |
153 | * hih6130_temperature_show() - 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 | */ |
161 | static ssize_t hih6130_temperature_show(struct device *dev, |
162 | struct device_attribute *attr, |
163 | char *buf) |
164 | { |
165 | struct hih6130 *hih6130 = dev_get_drvdata(dev); |
166 | int ret; |
167 | |
168 | ret = hih6130_update_measurements(dev); |
169 | if (ret < 0) |
170 | return ret; |
171 | return sprintf(buf, fmt: "%d\n" , hih6130->temperature); |
172 | } |
173 | |
174 | /** |
175 | * hih6130_humidity_show() - 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 | */ |
183 | static ssize_t hih6130_humidity_show(struct device *dev, |
184 | struct device_attribute *attr, char *buf) |
185 | { |
186 | struct hih6130 *hih6130 = dev_get_drvdata(dev); |
187 | int ret; |
188 | |
189 | ret = hih6130_update_measurements(dev); |
190 | if (ret < 0) |
191 | return ret; |
192 | return sprintf(buf, fmt: "%d\n" , hih6130->humidity); |
193 | } |
194 | |
195 | /* sysfs attributes */ |
196 | static SENSOR_DEVICE_ATTR_RO(temp1_input, hih6130_temperature, 0); |
197 | static SENSOR_DEVICE_ATTR_RO(humidity1_input, hih6130_humidity, 0); |
198 | |
199 | static struct attribute *hih6130_attrs[] = { |
200 | &sensor_dev_attr_temp1_input.dev_attr.attr, |
201 | &sensor_dev_attr_humidity1_input.dev_attr.attr, |
202 | NULL |
203 | }; |
204 | |
205 | ATTRIBUTE_GROUPS(hih6130); |
206 | |
207 | static int hih6130_probe(struct i2c_client *client) |
208 | { |
209 | struct device *dev = &client->dev; |
210 | struct hih6130 *hih6130; |
211 | struct device *hwmon_dev; |
212 | |
213 | if (!i2c_check_functionality(adap: client->adapter, I2C_FUNC_I2C)) { |
214 | dev_err(&client->dev, "adapter does not support true I2C\n" ); |
215 | return -ENODEV; |
216 | } |
217 | |
218 | hih6130 = devm_kzalloc(dev, size: sizeof(*hih6130), GFP_KERNEL); |
219 | if (!hih6130) |
220 | return -ENOMEM; |
221 | |
222 | hih6130->client = client; |
223 | mutex_init(&hih6130->lock); |
224 | |
225 | if (!i2c_check_functionality(adap: client->adapter, I2C_FUNC_SMBUS_QUICK)) |
226 | hih6130->write_length = 1; |
227 | |
228 | hwmon_dev = devm_hwmon_device_register_with_groups(dev, name: client->name, |
229 | drvdata: hih6130, |
230 | groups: hih6130_groups); |
231 | return PTR_ERR_OR_ZERO(ptr: hwmon_dev); |
232 | } |
233 | |
234 | /* Device ID table */ |
235 | static const struct i2c_device_id hih6130_id[] = { |
236 | { "hih6130" , 0 }, |
237 | { } |
238 | }; |
239 | MODULE_DEVICE_TABLE(i2c, hih6130_id); |
240 | |
241 | static const struct of_device_id __maybe_unused hih6130_of_match[] = { |
242 | { .compatible = "honeywell,hih6130" , }, |
243 | { } |
244 | }; |
245 | MODULE_DEVICE_TABLE(of, hih6130_of_match); |
246 | |
247 | static struct i2c_driver hih6130_driver = { |
248 | .driver = { |
249 | .name = "hih6130" , |
250 | .of_match_table = of_match_ptr(hih6130_of_match), |
251 | }, |
252 | .probe = hih6130_probe, |
253 | .id_table = hih6130_id, |
254 | }; |
255 | |
256 | module_i2c_driver(hih6130_driver); |
257 | |
258 | MODULE_AUTHOR("Iain Paton <ipaton0@gmail.com>" ); |
259 | MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver" ); |
260 | MODULE_LICENSE("GPL" ); |
261 | |