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![Iain Paton](/assets/img/avatar_default.png)
This is a new driver for the Honeywell Humidicon HIH-6130/HIH-6131 humidity sensor. The driver is based on the existing Sensiron sht21 driver with the necessary changes to the probe, update_measurements and conversion functions necessary to use the Honeywell sensors. There's no difference between the 6130 & 6131 other than the 6131 having an external condensation filter attached. Signed-off-by: Iain Paton <ipaton0@gmail.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
293 lines
8.1 KiB
C
293 lines
8.1 KiB
C
/* Honeywell HIH-6130/HIH-6131 humidity and temperature sensor driver
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*
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* Copyright (C) 2012 Iain Paton <ipaton0@gmail.com>
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*
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* heavily based on the sht21 driver
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* Copyright (C) 2010 Urs Fleisch <urs.fleisch@sensirion.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA
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*
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* Data sheets available (2012-06-22) at
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* http://sensing.honeywell.com/index.php?ci_id=3106&la_id=1&defId=44872
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/i2c.h>
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#include <linux/hwmon.h>
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#include <linux/hwmon-sysfs.h>
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#include <linux/err.h>
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#include <linux/mutex.h>
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#include <linux/device.h>
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#include <linux/delay.h>
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/**
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* struct hih6130 - HIH-6130 device specific data
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* @hwmon_dev: device registered with hwmon
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* @lock: mutex to protect measurement values
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* @valid: only false before first measurement is taken
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* @last_update: time of last update (jiffies)
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* @temperature: cached temperature measurement value
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* @humidity: cached humidity measurement value
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*/
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struct hih6130 {
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struct device *hwmon_dev;
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struct mutex lock;
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bool valid;
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unsigned long last_update;
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int temperature;
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int humidity;
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};
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/**
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* hih6130_temp_ticks_to_millicelsius() - convert raw temperature ticks to
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* milli celsius
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* @ticks: temperature ticks value received from sensor
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*/
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static inline int hih6130_temp_ticks_to_millicelsius(int ticks)
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{
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ticks = ticks >> 2;
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/*
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* from data sheet section 5.0
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* Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -40
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*/
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return (DIV_ROUND_CLOSEST(ticks * 1650, 16382) - 400) * 100;
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}
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/**
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* hih6130_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to
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* one-thousandths of a percent relative humidity
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* @ticks: humidity ticks value received from sensor
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*/
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static inline int hih6130_rh_ticks_to_per_cent_mille(int ticks)
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{
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ticks &= ~0xC000; /* clear status bits */
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/*
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* from data sheet section 4.0
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* Formula RH = ( ticks / ( 2^14 -2 ) ) * 100
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*/
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return DIV_ROUND_CLOSEST(ticks * 1000, 16382) * 100;
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}
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/**
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* hih6130_update_measurements() - get updated measurements from device
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* @client: I2C client device
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*
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* Returns 0 on success, else negative errno.
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*/
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static int hih6130_update_measurements(struct i2c_client *client)
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{
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int ret = 0;
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int t;
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struct hih6130 *hih6130 = i2c_get_clientdata(client);
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unsigned char tmp[4];
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struct i2c_msg msgs[1] = {
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{
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.addr = client->addr,
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.flags = I2C_M_RD,
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.len = 4,
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.buf = tmp,
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}
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};
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mutex_lock(&hih6130->lock);
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/*
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* While the measurement can be completed in ~40ms the sensor takes
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* much longer to react to a change in external conditions. How quickly
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* it reacts depends on airflow and other factors outwith our control.
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* The datasheet specifies maximum 'Response time' for humidity at 8s
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* and temperature at 30s under specified conditions.
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* We therefore choose to only read the sensor at most once per second.
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* This trades off pointless activity polling the sensor much faster
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* than it can react against better response times in conditions more
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* favourable than specified in the datasheet.
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*/
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if (time_after(jiffies, hih6130->last_update + HZ) || !hih6130->valid) {
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/* write to slave address, no data, to request a measurement */
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ret = i2c_master_send(client, tmp, 0);
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if (ret < 0)
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goto out;
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/* measurement cycle time is ~36.65msec */
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msleep(40);
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ret = i2c_transfer(client->adapter, msgs, 1);
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if (ret < 0)
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goto out;
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if ((tmp[0] & 0xC0) != 0) {
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dev_err(&client->dev, "Error while reading measurement result\n");
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ret = -EIO;
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goto out;
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}
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t = (tmp[0] << 8) + tmp[1];
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hih6130->humidity = hih6130_rh_ticks_to_per_cent_mille(t);
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t = (tmp[2] << 8) + tmp[3];
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hih6130->temperature = hih6130_temp_ticks_to_millicelsius(t);
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hih6130->last_update = jiffies;
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hih6130->valid = true;
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}
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out:
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mutex_unlock(&hih6130->lock);
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return ret >= 0 ? 0 : ret;
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}
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/**
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* hih6130_show_temperature() - show temperature measurement value in sysfs
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* @dev: device
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* @attr: device attribute
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* @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
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*
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* Will be called on read access to temp1_input sysfs attribute.
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* Returns number of bytes written into buffer, negative errno on error.
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*/
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static ssize_t hih6130_show_temperature(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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struct i2c_client *client = to_i2c_client(dev);
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struct hih6130 *hih6130 = i2c_get_clientdata(client);
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int ret = hih6130_update_measurements(client);
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if (ret < 0)
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return ret;
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return sprintf(buf, "%d\n", hih6130->temperature);
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}
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/**
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* hih6130_show_humidity() - show humidity measurement value in sysfs
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* @dev: device
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* @attr: device attribute
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* @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
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*
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* Will be called on read access to humidity1_input sysfs attribute.
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* Returns number of bytes written into buffer, negative errno on error.
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*/
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static ssize_t hih6130_show_humidity(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct i2c_client *client = to_i2c_client(dev);
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struct hih6130 *hih6130 = i2c_get_clientdata(client);
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int ret = hih6130_update_measurements(client);
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if (ret < 0)
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return ret;
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return sprintf(buf, "%d\n", hih6130->humidity);
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}
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/* sysfs attributes */
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static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, hih6130_show_temperature,
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NULL, 0);
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static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, hih6130_show_humidity,
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NULL, 0);
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static struct attribute *hih6130_attributes[] = {
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&sensor_dev_attr_temp1_input.dev_attr.attr,
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&sensor_dev_attr_humidity1_input.dev_attr.attr,
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NULL
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};
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static const struct attribute_group hih6130_attr_group = {
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.attrs = hih6130_attributes,
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};
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/**
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* hih6130_probe() - probe device
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* @client: I2C client device
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* @id: device ID
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*
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* Called by the I2C core when an entry in the ID table matches a
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* device's name.
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* Returns 0 on success.
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*/
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static int __devinit hih6130_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct hih6130 *hih6130;
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int err;
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
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dev_err(&client->dev, "adapter does not support true I2C\n");
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return -ENODEV;
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}
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hih6130 = devm_kzalloc(&client->dev, sizeof(*hih6130), GFP_KERNEL);
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if (!hih6130)
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return -ENOMEM;
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i2c_set_clientdata(client, hih6130);
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mutex_init(&hih6130->lock);
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err = sysfs_create_group(&client->dev.kobj, &hih6130_attr_group);
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if (err) {
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dev_dbg(&client->dev, "could not create sysfs files\n");
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return err;
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}
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hih6130->hwmon_dev = hwmon_device_register(&client->dev);
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if (IS_ERR(hih6130->hwmon_dev)) {
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dev_dbg(&client->dev, "unable to register hwmon device\n");
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err = PTR_ERR(hih6130->hwmon_dev);
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goto fail_remove_sysfs;
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}
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return 0;
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fail_remove_sysfs:
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sysfs_remove_group(&client->dev.kobj, &hih6130_attr_group);
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return err;
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}
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/**
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* hih6130_remove() - remove device
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* @client: I2C client device
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*/
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static int __devexit hih6130_remove(struct i2c_client *client)
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{
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struct hih6130 *hih6130 = i2c_get_clientdata(client);
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hwmon_device_unregister(hih6130->hwmon_dev);
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sysfs_remove_group(&client->dev.kobj, &hih6130_attr_group);
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return 0;
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}
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/* Device ID table */
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static const struct i2c_device_id hih6130_id[] = {
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{ "hih6130", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, hih6130_id);
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static struct i2c_driver hih6130_driver = {
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.driver.name = "hih6130",
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.probe = hih6130_probe,
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.remove = __devexit_p(hih6130_remove),
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.id_table = hih6130_id,
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};
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module_i2c_driver(hih6130_driver);
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MODULE_AUTHOR("Iain Paton <ipaton0@gmail.com>");
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MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver");
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MODULE_LICENSE("GPL");
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