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1// SPDX-License-Identifier: GPL-2.0-or-later2/* Honeywell HIH-6130/HIH-6131 humidity and temperature sensor driver3 *4 * Copyright (C) 2012 Iain Paton <ipaton0@gmail.com>5 *6 * heavily based on the sht21 driver7 * Copyright (C) 2010 Urs Fleisch <urs.fleisch@sensirion.com>8 *9 * Data sheets available (2012-06-22) at10 * http://sensing.honeywell.com/index.php?ci_id=3106&la_id=1&defId=4487211 */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 data27 * @client: pointer to I2C client device28 * @lock: mutex to protect measurement values29 * @valid: only false before first measurement is taken30 * @last_update: time of last update (jiffies)31 * @temperature: cached temperature measurement value32 * @humidity: cached humidity measurement value33 * @write_length: length for I2C measurement request34 */35struct 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 to47 * milli celsius48 * @ticks: temperature ticks value received from sensor49 */50static inline int hih6130_temp_ticks_to_millicelsius(int ticks)51{52 ticks = ticks >> 2;53 /*54 * from data sheet section 5.055 * Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -4056 */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 to62 * one-thousandths of a percent relative humidity63 * @ticks: humidity ticks value received from sensor64 */65static inline int hih6130_rh_ticks_to_per_cent_mille(int ticks)66{67 ticks &= ~0xC000; /* clear status bits */68 /*69 * from data sheet section 4.070 * Formula RH = ( ticks / ( 2^14 -2 ) ) * 10071 */72 return DIV_ROUND_CLOSEST(ticks * 1000, 16382) * 100;73}74 75/**76 * hih6130_update_measurements() - get updated measurements from device77 * @dev: device78 *79 * Returns 0 on success, else negative errno.80 */81static 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 takes101 * much longer to react to a change in external conditions. How quickly102 * it reacts depends on airflow and other factors outwith our control.103 * The datasheet specifies maximum 'Response time' for humidity at 8s104 * 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 faster107 * than it can react against better response times in conditions more108 * 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, but115 * for systems with I2C bus drivers that do not allow zero116 * length packets we write one dummy byte to allow sensor117 * measurements on them.118 */119 tmp[0] = 0;120 ret = i2c_master_send(client, tmp, hih6130->write_length);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 }146out:147 mutex_unlock(&hih6130->lock);148 149 return ret >= 0 ? 0 : ret;150}151 152/**153 * hih6130_temperature_show() - show temperature measurement value in sysfs154 * @dev: device155 * @attr: device attribute156 * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to157 *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 */161static 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, "%d\n", hih6130->temperature);172}173 174/**175 * hih6130_humidity_show() - show humidity measurement value in sysfs176 * @dev: device177 * @attr: device attribute178 * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to179 *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 */183static 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, "%d\n", hih6130->humidity);193}194 195/* sysfs attributes */196static SENSOR_DEVICE_ATTR_RO(temp1_input, hih6130_temperature, 0);197static SENSOR_DEVICE_ATTR_RO(humidity1_input, hih6130_humidity, 0);198 199static struct attribute *hih6130_attrs[] = {200 &sensor_dev_attr_temp1_input.dev_attr.attr,201 &sensor_dev_attr_humidity1_input.dev_attr.attr,202 NULL203};204 205ATTRIBUTE_GROUPS(hih6130);206 207static 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(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, 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(client->adapter, I2C_FUNC_SMBUS_QUICK))226 hih6130->write_length = 1;227 228 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,229 hih6130,230 hih6130_groups);231 return PTR_ERR_OR_ZERO(hwmon_dev);232}233 234/* Device ID table */235static const struct i2c_device_id hih6130_id[] = {236 { "hih6130" },237 { }238};239MODULE_DEVICE_TABLE(i2c, hih6130_id);240 241static const struct of_device_id __maybe_unused hih6130_of_match[] = {242 { .compatible = "honeywell,hih6130", },243 { }244};245MODULE_DEVICE_TABLE(of, hih6130_of_match);246 247static 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 256module_i2c_driver(hih6130_driver);257 258MODULE_AUTHOR("Iain Paton <ipaton0@gmail.com>");259MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver");260MODULE_LICENSE("GPL");261