1 // SPDX-License-Identifier: GPL-2.0-only
6  * sht4x.c - Linux hwmon driver for SHT4x Temperature and Humidity sensor
14 #include <linux/hwmon-sysfs.h>
48 #define SHT4X_MIN_TEMPERATURE	-45000
56  * struct sht4x_data - All the data required to operate an SHT4X chip
74 	u32			heater_power;	/* in milli-watts */
75 	u32			heater_time;	/* in milli-seconds */
77 	long			update_interval;	/* in milli-seconds */
84  * sht4x_read_values() - read and parse the raw data from the SHT4X
86  * Return: 0 if successful, -ERRNO if not
93 	struct i2c_client *client = data->client;  in sht4x_read_values()
99 	mutex_lock(&data->lock);  in sht4x_read_values()
102 	if (time_before(curr_jiffies, data->heating_complete))  in sht4x_read_values()
103 		msleep(jiffies_to_msecs(data->heating_complete - curr_jiffies));  in sht4x_read_values()
105 	if (data->data_pending &&  in sht4x_read_values()
106 	    time_before(jiffies, data->heating_complete + data->update_interval)) {  in sht4x_read_values()
107 		data->data_pending = false;  in sht4x_read_values()
109 		next_update = data->last_updated +  in sht4x_read_values()
110 			msecs_to_jiffies(data->update_interval);  in sht4x_read_values()
112 		if (data->valid && time_before_eq(jiffies, next_update))  in sht4x_read_values()
125 			ret = -ENODATA;  in sht4x_read_values()
134 		dev_err(&client->dev, "data integrity check failed\n");  in sht4x_read_values()
135 		ret = -EIO;  in sht4x_read_values()
141 		dev_err(&client->dev, "data integrity check failed\n");  in sht4x_read_values()
142 		ret = -EIO;  in sht4x_read_values()
146 	data->temperature = ((21875 * (int32_t)t_ticks) >> 13) - 45000;  in sht4x_read_values()
147 	data->humidity = ((15625 * (int32_t)rh_ticks) >> 13) - 6000;  in sht4x_read_values()
148 	data->last_updated = jiffies;  in sht4x_read_values()
149 	data->valid = true;  in sht4x_read_values()
153 	mutex_unlock(&data->lock);  in sht4x_read_values()
159 	data->update_interval = clamp_val(val, SHT4X_MIN_POLL_INTERVAL, INT_MAX);  in sht4x_interval_write()
164 /* sht4x_interval_read() - read the minimum poll interval in milliseconds */
167 	*val = data->update_interval;  in sht4x_interval_read()
171 /* sht4x_temperature1_read() - read the temperature in millidegrees */
180 	*val = data->temperature;  in sht4x_temperature1_read()
185 /* sht4x_humidity1_read() - read a relative humidity in millipercent */
194 	*val = data->humidity;  in sht4x_humidity1_read()
201 				   u32 attr, int channel)  in sht4x_hwmon_visible()  argument
215 			    u32 attr, int channel, long *val)  in sht4x_hwmon_read()  argument
227 		return -EOPNOTSUPP;  in sht4x_hwmon_read()
232 			     u32 attr, int channel, long val)  in sht4x_hwmon_write()  argument
240 		return -EOPNOTSUPP;  in sht4x_hwmon_write()
245 				  struct device_attribute *attr,  in heater_enable_show()  argument
250 	return sysfs_emit(buf, "%u\n", time_before(jiffies, data->heating_complete));  in heater_enable_show()
254 				   struct device_attribute *attr,  in heater_enable_store()  argument
268 		return -EINVAL;  in heater_enable_store()
270 	if (data->heater_time == 100) {  in heater_enable_store()
271 		if (data->heater_power == 20)  in heater_enable_store()
273 		else if (data->heater_power == 110)  in heater_enable_store()
275 		else /* data->heater_power == 200 */  in heater_enable_store()
279 	} else { /* data->heater_time == 1000 */  in heater_enable_store()
280 		if (data->heater_power == 20)  in heater_enable_store()
282 		else if (data->heater_power == 110)  in heater_enable_store()
284 		else /* data->heater_power == 200 */  in heater_enable_store()
290 	mutex_lock(&data->lock);  in heater_enable_store()
292 	if (time_before(jiffies, data->heating_complete)) {  in heater_enable_store()
293 		ret = -EBUSY;  in heater_enable_store()
297 	ret = i2c_master_send(data->client, &cmd, SHT4X_CMD_LEN);  in heater_enable_store()
301 	data->heating_complete = jiffies + msecs_to_jiffies(heating_time_bound);  in heater_enable_store()
302 	data->data_pending = true;  in heater_enable_store()
304 	mutex_unlock(&data->lock);  in heater_enable_store()
309 				 struct device_attribute *attr,  in heater_power_show()  argument
314 	return sysfs_emit(buf, "%u\n", data->heater_power);  in heater_power_show()
318 				  struct device_attribute *attr,  in heater_power_store()  argument
331 		return -EINVAL;  in heater_power_store()
333 	data->heater_power = power;  in heater_power_store()
339 				struct device_attribute *attr,  in heater_time_show()  argument
344 	return sysfs_emit(buf, "%u\n", data->heater_time);  in heater_time_show()
348 				 struct device_attribute *attr,  in heater_time_store()  argument
361 		return -EINVAL;  in heater_time_store()
363 	data->heater_time = time;  in heater_time_store()
373 	&dev_attr_heater_enable.attr,
374 	&dev_attr_heater_power.attr,
375 	&dev_attr_heater_time.attr,
401 	struct device *device = &client->dev;  in sht4x_probe()
408 	 * we require full i2c support since the sht4x uses multi-byte read and  in sht4x_probe()
409 	 * writes as well as multi-byte commands which are not supported by  in sht4x_probe()
412 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))  in sht4x_probe()
413 		return -EOPNOTSUPP;  in sht4x_probe()
417 		return -ENOMEM;  in sht4x_probe()
419 	data->update_interval = SHT4X_MIN_POLL_INTERVAL;  in sht4x_probe()
420 	data->client = client;  in sht4x_probe()
421 	data->heater_power = 200;  in sht4x_probe()
422 	data->heater_time = 1000;  in sht4x_probe()
423 	data->heating_complete = jiffies;  in sht4x_probe()
425 	mutex_init(&data->lock);  in sht4x_probe()
433 		return -EIO;  in sht4x_probe()
436 							 client->name,  in sht4x_probe()