1505c2549SNavin Sankar Velliangiri // SPDX-License-Identifier: GPL-2.0-only
2505c2549SNavin Sankar Velliangiri
3505c2549SNavin Sankar Velliangiri /*
4505c2549SNavin Sankar Velliangiri * Copyright (c) Linumiz 2021
5505c2549SNavin Sankar Velliangiri *
6505c2549SNavin Sankar Velliangiri * sht4x.c - Linux hwmon driver for SHT4x Temperature and Humidity sensor
7505c2549SNavin Sankar Velliangiri *
8505c2549SNavin Sankar Velliangiri * Author: Navin Sankar Velliangiri <navin@linumiz.com>
9505c2549SNavin Sankar Velliangiri */
10505c2549SNavin Sankar Velliangiri
11505c2549SNavin Sankar Velliangiri #include <linux/crc8.h>
12505c2549SNavin Sankar Velliangiri #include <linux/delay.h>
13505c2549SNavin Sankar Velliangiri #include <linux/hwmon.h>
14505c2549SNavin Sankar Velliangiri #include <linux/i2c.h>
15505c2549SNavin Sankar Velliangiri #include <linux/jiffies.h>
16505c2549SNavin Sankar Velliangiri #include <linux/module.h>
17505c2549SNavin Sankar Velliangiri
18505c2549SNavin Sankar Velliangiri /*
19505c2549SNavin Sankar Velliangiri * Poll intervals (in milliseconds)
20505c2549SNavin Sankar Velliangiri */
21505c2549SNavin Sankar Velliangiri #define SHT4X_MIN_POLL_INTERVAL 2000
22505c2549SNavin Sankar Velliangiri
23505c2549SNavin Sankar Velliangiri /*
24505c2549SNavin Sankar Velliangiri * I2C command delays (in microseconds)
25505c2549SNavin Sankar Velliangiri */
260e4190d7SDavid Mosberger-Tang #define SHT4X_MEAS_DELAY_HPM 8200 /* see t_MEAS,h in datasheet */
27505c2549SNavin Sankar Velliangiri #define SHT4X_DELAY_EXTRA 10000
28505c2549SNavin Sankar Velliangiri
29505c2549SNavin Sankar Velliangiri /*
30505c2549SNavin Sankar Velliangiri * Command Bytes
31505c2549SNavin Sankar Velliangiri */
32505c2549SNavin Sankar Velliangiri #define SHT4X_CMD_MEASURE_HPM 0b11111101
33505c2549SNavin Sankar Velliangiri #define SHT4X_CMD_RESET 0b10010100
34505c2549SNavin Sankar Velliangiri
35505c2549SNavin Sankar Velliangiri #define SHT4X_CMD_LEN 1
36505c2549SNavin Sankar Velliangiri #define SHT4X_CRC8_LEN 1
37505c2549SNavin Sankar Velliangiri #define SHT4X_WORD_LEN 2
38505c2549SNavin Sankar Velliangiri #define SHT4X_RESPONSE_LENGTH 6
39505c2549SNavin Sankar Velliangiri #define SHT4X_CRC8_POLYNOMIAL 0x31
40505c2549SNavin Sankar Velliangiri #define SHT4X_CRC8_INIT 0xff
41505c2549SNavin Sankar Velliangiri #define SHT4X_MIN_TEMPERATURE -45000
42505c2549SNavin Sankar Velliangiri #define SHT4X_MAX_TEMPERATURE 125000
43505c2549SNavin Sankar Velliangiri #define SHT4X_MIN_HUMIDITY 0
44505c2549SNavin Sankar Velliangiri #define SHT4X_MAX_HUMIDITY 100000
45505c2549SNavin Sankar Velliangiri
46505c2549SNavin Sankar Velliangiri DECLARE_CRC8_TABLE(sht4x_crc8_table);
47505c2549SNavin Sankar Velliangiri
48505c2549SNavin Sankar Velliangiri /**
49505c2549SNavin Sankar Velliangiri * struct sht4x_data - All the data required to operate an SHT4X chip
50505c2549SNavin Sankar Velliangiri * @client: the i2c client associated with the SHT4X
51505c2549SNavin Sankar Velliangiri * @lock: a mutex that is used to prevent parallel access to the i2c client
5210bd80e0SYang Li * @valid: validity of fields below
53505c2549SNavin Sankar Velliangiri * @update_interval: the minimum poll interval
54505c2549SNavin Sankar Velliangiri * @last_updated: the previous time that the SHT4X was polled
55505c2549SNavin Sankar Velliangiri * @temperature: the latest temperature value received from the SHT4X
56505c2549SNavin Sankar Velliangiri * @humidity: the latest humidity value received from the SHT4X
57505c2549SNavin Sankar Velliangiri */
58505c2549SNavin Sankar Velliangiri struct sht4x_data {
59505c2549SNavin Sankar Velliangiri struct i2c_client *client;
60505c2549SNavin Sankar Velliangiri struct mutex lock; /* atomic read data updates */
61505c2549SNavin Sankar Velliangiri bool valid; /* validity of fields below */
62505c2549SNavin Sankar Velliangiri long update_interval; /* in milli-seconds */
63505c2549SNavin Sankar Velliangiri long last_updated; /* in jiffies */
64505c2549SNavin Sankar Velliangiri s32 temperature;
65505c2549SNavin Sankar Velliangiri s32 humidity;
66505c2549SNavin Sankar Velliangiri };
67505c2549SNavin Sankar Velliangiri
68505c2549SNavin Sankar Velliangiri /**
69505c2549SNavin Sankar Velliangiri * sht4x_read_values() - read and parse the raw data from the SHT4X
7010bd80e0SYang Li * @data: the struct sht4x_data to use for the lock
7107c6621aSJoe Perches * Return: 0 if successful, -ERRNO if not
72505c2549SNavin Sankar Velliangiri */
sht4x_read_values(struct sht4x_data * data)73505c2549SNavin Sankar Velliangiri static int sht4x_read_values(struct sht4x_data *data)
74505c2549SNavin Sankar Velliangiri {
75505c2549SNavin Sankar Velliangiri int ret = 0;
76505c2549SNavin Sankar Velliangiri u16 t_ticks, rh_ticks;
77505c2549SNavin Sankar Velliangiri unsigned long next_update;
78505c2549SNavin Sankar Velliangiri struct i2c_client *client = data->client;
7907c6621aSJoe Perches u8 crc;
8007c6621aSJoe Perches u8 cmd[SHT4X_CMD_LEN] = {SHT4X_CMD_MEASURE_HPM};
8107c6621aSJoe Perches u8 raw_data[SHT4X_RESPONSE_LENGTH];
82505c2549SNavin Sankar Velliangiri
83505c2549SNavin Sankar Velliangiri mutex_lock(&data->lock);
84505c2549SNavin Sankar Velliangiri next_update = data->last_updated +
85505c2549SNavin Sankar Velliangiri msecs_to_jiffies(data->update_interval);
8607c6621aSJoe Perches
8707c6621aSJoe Perches if (data->valid && time_before_eq(jiffies, next_update))
8807c6621aSJoe Perches goto unlock;
8907c6621aSJoe Perches
90505c2549SNavin Sankar Velliangiri ret = i2c_master_send(client, cmd, SHT4X_CMD_LEN);
91505c2549SNavin Sankar Velliangiri if (ret < 0)
92505c2549SNavin Sankar Velliangiri goto unlock;
93505c2549SNavin Sankar Velliangiri
940e4190d7SDavid Mosberger-Tang usleep_range(SHT4X_MEAS_DELAY_HPM, SHT4X_MEAS_DELAY_HPM + SHT4X_DELAY_EXTRA);
95505c2549SNavin Sankar Velliangiri
96505c2549SNavin Sankar Velliangiri ret = i2c_master_recv(client, raw_data, SHT4X_RESPONSE_LENGTH);
97505c2549SNavin Sankar Velliangiri if (ret != SHT4X_RESPONSE_LENGTH) {
98505c2549SNavin Sankar Velliangiri if (ret >= 0)
99505c2549SNavin Sankar Velliangiri ret = -ENODATA;
100505c2549SNavin Sankar Velliangiri goto unlock;
101505c2549SNavin Sankar Velliangiri }
102505c2549SNavin Sankar Velliangiri
103505c2549SNavin Sankar Velliangiri t_ticks = raw_data[0] << 8 | raw_data[1];
104505c2549SNavin Sankar Velliangiri rh_ticks = raw_data[3] << 8 | raw_data[4];
105505c2549SNavin Sankar Velliangiri
106505c2549SNavin Sankar Velliangiri crc = crc8(sht4x_crc8_table, &raw_data[0], SHT4X_WORD_LEN, CRC8_INIT_VALUE);
107505c2549SNavin Sankar Velliangiri if (crc != raw_data[2]) {
108505c2549SNavin Sankar Velliangiri dev_err(&client->dev, "data integrity check failed\n");
109505c2549SNavin Sankar Velliangiri ret = -EIO;
110505c2549SNavin Sankar Velliangiri goto unlock;
111505c2549SNavin Sankar Velliangiri }
112505c2549SNavin Sankar Velliangiri
113505c2549SNavin Sankar Velliangiri crc = crc8(sht4x_crc8_table, &raw_data[3], SHT4X_WORD_LEN, CRC8_INIT_VALUE);
114505c2549SNavin Sankar Velliangiri if (crc != raw_data[5]) {
115505c2549SNavin Sankar Velliangiri dev_err(&client->dev, "data integrity check failed\n");
116505c2549SNavin Sankar Velliangiri ret = -EIO;
117505c2549SNavin Sankar Velliangiri goto unlock;
118505c2549SNavin Sankar Velliangiri }
119505c2549SNavin Sankar Velliangiri
120505c2549SNavin Sankar Velliangiri data->temperature = ((21875 * (int32_t)t_ticks) >> 13) - 45000;
121505c2549SNavin Sankar Velliangiri data->humidity = ((15625 * (int32_t)rh_ticks) >> 13) - 6000;
122505c2549SNavin Sankar Velliangiri data->last_updated = jiffies;
123505c2549SNavin Sankar Velliangiri data->valid = true;
12407c6621aSJoe Perches ret = 0;
125505c2549SNavin Sankar Velliangiri
126505c2549SNavin Sankar Velliangiri unlock:
127505c2549SNavin Sankar Velliangiri mutex_unlock(&data->lock);
128505c2549SNavin Sankar Velliangiri return ret;
129505c2549SNavin Sankar Velliangiri }
130505c2549SNavin Sankar Velliangiri
sht4x_interval_write(struct sht4x_data * data,long val)131505c2549SNavin Sankar Velliangiri static ssize_t sht4x_interval_write(struct sht4x_data *data, long val)
132505c2549SNavin Sankar Velliangiri {
133f9c0cf8fSJason A. Donenfeld data->update_interval = clamp_val(val, SHT4X_MIN_POLL_INTERVAL, INT_MAX);
134505c2549SNavin Sankar Velliangiri
135505c2549SNavin Sankar Velliangiri return 0;
136505c2549SNavin Sankar Velliangiri }
137505c2549SNavin Sankar Velliangiri
13807c6621aSJoe Perches /* sht4x_interval_read() - read the minimum poll interval in milliseconds */
sht4x_interval_read(struct sht4x_data * data,long * val)139505c2549SNavin Sankar Velliangiri static size_t sht4x_interval_read(struct sht4x_data *data, long *val)
140505c2549SNavin Sankar Velliangiri {
141505c2549SNavin Sankar Velliangiri *val = data->update_interval;
142505c2549SNavin Sankar Velliangiri return 0;
143505c2549SNavin Sankar Velliangiri }
144505c2549SNavin Sankar Velliangiri
14507c6621aSJoe Perches /* sht4x_temperature1_read() - read the temperature in millidegrees */
sht4x_temperature1_read(struct sht4x_data * data,long * val)146505c2549SNavin Sankar Velliangiri static int sht4x_temperature1_read(struct sht4x_data *data, long *val)
147505c2549SNavin Sankar Velliangiri {
148505c2549SNavin Sankar Velliangiri int ret;
149505c2549SNavin Sankar Velliangiri
150505c2549SNavin Sankar Velliangiri ret = sht4x_read_values(data);
151505c2549SNavin Sankar Velliangiri if (ret < 0)
152505c2549SNavin Sankar Velliangiri return ret;
153505c2549SNavin Sankar Velliangiri
154505c2549SNavin Sankar Velliangiri *val = data->temperature;
155505c2549SNavin Sankar Velliangiri
156505c2549SNavin Sankar Velliangiri return 0;
157505c2549SNavin Sankar Velliangiri }
158505c2549SNavin Sankar Velliangiri
15907c6621aSJoe Perches /* sht4x_humidity1_read() - read a relative humidity in millipercent */
sht4x_humidity1_read(struct sht4x_data * data,long * val)160505c2549SNavin Sankar Velliangiri static int sht4x_humidity1_read(struct sht4x_data *data, long *val)
161505c2549SNavin Sankar Velliangiri {
162505c2549SNavin Sankar Velliangiri int ret;
163505c2549SNavin Sankar Velliangiri
164505c2549SNavin Sankar Velliangiri ret = sht4x_read_values(data);
165505c2549SNavin Sankar Velliangiri if (ret < 0)
166505c2549SNavin Sankar Velliangiri return ret;
167505c2549SNavin Sankar Velliangiri
168505c2549SNavin Sankar Velliangiri *val = data->humidity;
169505c2549SNavin Sankar Velliangiri
170505c2549SNavin Sankar Velliangiri return 0;
171505c2549SNavin Sankar Velliangiri }
172505c2549SNavin Sankar Velliangiri
sht4x_hwmon_visible(const void * data,enum hwmon_sensor_types type,u32 attr,int channel)173505c2549SNavin Sankar Velliangiri static umode_t sht4x_hwmon_visible(const void *data,
174505c2549SNavin Sankar Velliangiri enum hwmon_sensor_types type,
175505c2549SNavin Sankar Velliangiri u32 attr, int channel)
176505c2549SNavin Sankar Velliangiri {
177505c2549SNavin Sankar Velliangiri switch (type) {
178505c2549SNavin Sankar Velliangiri case hwmon_temp:
179505c2549SNavin Sankar Velliangiri case hwmon_humidity:
180505c2549SNavin Sankar Velliangiri return 0444;
181505c2549SNavin Sankar Velliangiri case hwmon_chip:
182505c2549SNavin Sankar Velliangiri return 0644;
183505c2549SNavin Sankar Velliangiri default:
184505c2549SNavin Sankar Velliangiri return 0;
185505c2549SNavin Sankar Velliangiri }
186505c2549SNavin Sankar Velliangiri }
187505c2549SNavin Sankar Velliangiri
sht4x_hwmon_read(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long * val)188505c2549SNavin Sankar Velliangiri static int sht4x_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
189505c2549SNavin Sankar Velliangiri u32 attr, int channel, long *val)
190505c2549SNavin Sankar Velliangiri {
191505c2549SNavin Sankar Velliangiri struct sht4x_data *data = dev_get_drvdata(dev);
192505c2549SNavin Sankar Velliangiri
193505c2549SNavin Sankar Velliangiri switch (type) {
194505c2549SNavin Sankar Velliangiri case hwmon_temp:
195505c2549SNavin Sankar Velliangiri return sht4x_temperature1_read(data, val);
196505c2549SNavin Sankar Velliangiri case hwmon_humidity:
197505c2549SNavin Sankar Velliangiri return sht4x_humidity1_read(data, val);
198505c2549SNavin Sankar Velliangiri case hwmon_chip:
199505c2549SNavin Sankar Velliangiri return sht4x_interval_read(data, val);
200505c2549SNavin Sankar Velliangiri default:
201505c2549SNavin Sankar Velliangiri return -EOPNOTSUPP;
202505c2549SNavin Sankar Velliangiri }
203505c2549SNavin Sankar Velliangiri }
204505c2549SNavin Sankar Velliangiri
sht4x_hwmon_write(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long val)205505c2549SNavin Sankar Velliangiri static int sht4x_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
206505c2549SNavin Sankar Velliangiri u32 attr, int channel, long val)
207505c2549SNavin Sankar Velliangiri {
208505c2549SNavin Sankar Velliangiri struct sht4x_data *data = dev_get_drvdata(dev);
209505c2549SNavin Sankar Velliangiri
210505c2549SNavin Sankar Velliangiri switch (type) {
211505c2549SNavin Sankar Velliangiri case hwmon_chip:
212505c2549SNavin Sankar Velliangiri return sht4x_interval_write(data, val);
213505c2549SNavin Sankar Velliangiri default:
214505c2549SNavin Sankar Velliangiri return -EOPNOTSUPP;
215505c2549SNavin Sankar Velliangiri }
216505c2549SNavin Sankar Velliangiri }
217505c2549SNavin Sankar Velliangiri
21811c1dff5SKrzysztof Kozlowski static const struct hwmon_channel_info * const sht4x_info[] = {
219505c2549SNavin Sankar Velliangiri HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL),
220505c2549SNavin Sankar Velliangiri HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
221505c2549SNavin Sankar Velliangiri HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT),
222505c2549SNavin Sankar Velliangiri NULL,
223505c2549SNavin Sankar Velliangiri };
224505c2549SNavin Sankar Velliangiri
225505c2549SNavin Sankar Velliangiri static const struct hwmon_ops sht4x_hwmon_ops = {
226505c2549SNavin Sankar Velliangiri .is_visible = sht4x_hwmon_visible,
227505c2549SNavin Sankar Velliangiri .read = sht4x_hwmon_read,
228505c2549SNavin Sankar Velliangiri .write = sht4x_hwmon_write,
229505c2549SNavin Sankar Velliangiri };
230505c2549SNavin Sankar Velliangiri
231505c2549SNavin Sankar Velliangiri static const struct hwmon_chip_info sht4x_chip_info = {
232505c2549SNavin Sankar Velliangiri .ops = &sht4x_hwmon_ops,
233505c2549SNavin Sankar Velliangiri .info = sht4x_info,
234505c2549SNavin Sankar Velliangiri };
235505c2549SNavin Sankar Velliangiri
sht4x_probe(struct i2c_client * client)236deeab9eaSStephen Kitt static int sht4x_probe(struct i2c_client *client)
237505c2549SNavin Sankar Velliangiri {
238505c2549SNavin Sankar Velliangiri struct device *device = &client->dev;
239505c2549SNavin Sankar Velliangiri struct device *hwmon_dev;
240505c2549SNavin Sankar Velliangiri struct sht4x_data *data;
241505c2549SNavin Sankar Velliangiri u8 cmd[] = {SHT4X_CMD_RESET};
242505c2549SNavin Sankar Velliangiri int ret;
243505c2549SNavin Sankar Velliangiri
244505c2549SNavin Sankar Velliangiri /*
245505c2549SNavin Sankar Velliangiri * we require full i2c support since the sht4x uses multi-byte read and
246505c2549SNavin Sankar Velliangiri * writes as well as multi-byte commands which are not supported by
247505c2549SNavin Sankar Velliangiri * the smbus protocol
248505c2549SNavin Sankar Velliangiri */
249505c2549SNavin Sankar Velliangiri if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
250505c2549SNavin Sankar Velliangiri return -EOPNOTSUPP;
251505c2549SNavin Sankar Velliangiri
252505c2549SNavin Sankar Velliangiri data = devm_kzalloc(device, sizeof(*data), GFP_KERNEL);
253505c2549SNavin Sankar Velliangiri if (!data)
254505c2549SNavin Sankar Velliangiri return -ENOMEM;
255505c2549SNavin Sankar Velliangiri
256505c2549SNavin Sankar Velliangiri data->update_interval = SHT4X_MIN_POLL_INTERVAL;
257505c2549SNavin Sankar Velliangiri data->client = client;
258505c2549SNavin Sankar Velliangiri
259505c2549SNavin Sankar Velliangiri mutex_init(&data->lock);
260505c2549SNavin Sankar Velliangiri
261505c2549SNavin Sankar Velliangiri crc8_populate_msb(sht4x_crc8_table, SHT4X_CRC8_POLYNOMIAL);
262505c2549SNavin Sankar Velliangiri
263505c2549SNavin Sankar Velliangiri ret = i2c_master_send(client, cmd, SHT4X_CMD_LEN);
264505c2549SNavin Sankar Velliangiri if (ret < 0)
265505c2549SNavin Sankar Velliangiri return ret;
266505c2549SNavin Sankar Velliangiri if (ret != SHT4X_CMD_LEN)
267505c2549SNavin Sankar Velliangiri return -EIO;
268505c2549SNavin Sankar Velliangiri
269505c2549SNavin Sankar Velliangiri hwmon_dev = devm_hwmon_device_register_with_info(device,
270505c2549SNavin Sankar Velliangiri client->name,
271505c2549SNavin Sankar Velliangiri data,
272505c2549SNavin Sankar Velliangiri &sht4x_chip_info,
273505c2549SNavin Sankar Velliangiri NULL);
274505c2549SNavin Sankar Velliangiri
275505c2549SNavin Sankar Velliangiri return PTR_ERR_OR_ZERO(hwmon_dev);
276505c2549SNavin Sankar Velliangiri }
277505c2549SNavin Sankar Velliangiri
278505c2549SNavin Sankar Velliangiri static const struct i2c_device_id sht4x_id[] = {
279*d8a66f36SUwe Kleine-König { "sht4x" },
280505c2549SNavin Sankar Velliangiri { },
281505c2549SNavin Sankar Velliangiri };
282505c2549SNavin Sankar Velliangiri MODULE_DEVICE_TABLE(i2c, sht4x_id);
283505c2549SNavin Sankar Velliangiri
28462cfc057SDavid Mosberger-Tang static const struct of_device_id sht4x_of_match[] = {
28562cfc057SDavid Mosberger-Tang { .compatible = "sensirion,sht4x" },
28662cfc057SDavid Mosberger-Tang { }
28762cfc057SDavid Mosberger-Tang };
28862cfc057SDavid Mosberger-Tang MODULE_DEVICE_TABLE(of, sht4x_of_match);
28962cfc057SDavid Mosberger-Tang
290505c2549SNavin Sankar Velliangiri static struct i2c_driver sht4x_driver = {
291505c2549SNavin Sankar Velliangiri .driver = {
292505c2549SNavin Sankar Velliangiri .name = "sht4x",
29362cfc057SDavid Mosberger-Tang .of_match_table = sht4x_of_match,
294505c2549SNavin Sankar Velliangiri },
2951975d167SUwe Kleine-König .probe = sht4x_probe,
296505c2549SNavin Sankar Velliangiri .id_table = sht4x_id,
297505c2549SNavin Sankar Velliangiri };
298505c2549SNavin Sankar Velliangiri
299505c2549SNavin Sankar Velliangiri module_i2c_driver(sht4x_driver);
300505c2549SNavin Sankar Velliangiri
301505c2549SNavin Sankar Velliangiri MODULE_AUTHOR("Navin Sankar Velliangiri <navin@linumiz.com>");
302505c2549SNavin Sankar Velliangiri MODULE_DESCRIPTION("Sensirion SHT4x humidity and temperature sensor driver");
303505c2549SNavin Sankar Velliangiri MODULE_LICENSE("GPL v2");
304