1 // SPDX-License-Identifier: GPL-2.0-only
6  * sht4x.c - Linux hwmon driver for SHT4x Temperature and Humidity sensor
41 #define SHT4X_MIN_TEMPERATURE	-45000
49  * struct sht4x_data - All the data required to operate an SHT4X chip
56  * @humidity: the latest humidity value received from the SHT4X
62 	long			update_interval;	/* in milli-seconds */
65 	s32			humidity;  member
69  * sht4x_read_values() - read and parse the raw data from the SHT4X
71  * Return: 0 if successful, -ERRNO if not
78 	struct i2c_client *client = data->client;  in sht4x_read_values()
83 	mutex_lock(&data->lock);  in sht4x_read_values()
84 	next_update = data->last_updated +  in sht4x_read_values()
85 		      msecs_to_jiffies(data->update_interval);  in sht4x_read_values()
87 	if (data->valid && time_before_eq(jiffies, next_update))  in sht4x_read_values()
99 			ret = -ENODATA;  in sht4x_read_values()
108 		dev_err(&client->dev, "data integrity check failed\n");  in sht4x_read_values()
109 		ret = -EIO;  in sht4x_read_values()
115 		dev_err(&client->dev, "data integrity check failed\n");  in sht4x_read_values()
116 		ret = -EIO;  in sht4x_read_values()
120 	data->temperature = ((21875 * (int32_t)t_ticks) >> 13) - 45000;  in sht4x_read_values()
121 	data->humidity = ((15625 * (int32_t)rh_ticks) >> 13) - 6000;  in sht4x_read_values()
122 	data->last_updated = jiffies;  in sht4x_read_values()
123 	data->valid = true;  in sht4x_read_values()
127 	mutex_unlock(&data->lock);  in sht4x_read_values()
133 	data->update_interval = clamp_val(val, SHT4X_MIN_POLL_INTERVAL, INT_MAX);  in sht4x_interval_write()
138 /* sht4x_interval_read() - read the minimum poll interval in milliseconds */
141 	*val = data->update_interval;  in sht4x_interval_read()
145 /* sht4x_temperature1_read() - read the temperature in millidegrees */
154 	*val = data->temperature;  in sht4x_temperature1_read()
159 /* sht4x_humidity1_read() - read a relative humidity in millipercent */
168 	*val = data->humidity;  in sht4x_humidity1_read()
201 		return -EOPNOTSUPP;  in sht4x_hwmon_read()
214 		return -EOPNOTSUPP;  in sht4x_hwmon_write()
221 	HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT),
238 	struct device *device = &client->dev;  in sht4x_probe()
245 	 * we require full i2c support since the sht4x uses multi-byte read and  in sht4x_probe()
246 	 * writes as well as multi-byte commands which are not supported by  in sht4x_probe()
249 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))  in sht4x_probe()
250 		return -EOPNOTSUPP;  in sht4x_probe()
254 		return -ENOMEM;  in sht4x_probe()
256 	data->update_interval = SHT4X_MIN_POLL_INTERVAL;  in sht4x_probe()
257 	data->client = client;  in sht4x_probe()
259 	mutex_init(&data->lock);  in sht4x_probe()
267 		return -EIO;  in sht4x_probe()
270 							 client->name,  in sht4x_probe()
302 MODULE_DESCRIPTION("Sensirion SHT4x humidity and temperature sensor driver");