drivers/hwmon/hih6130.c - arm/linux - Git at Google

 /* Honeywell HIH-6130/HIH-6131 humidity and temperature sensor driver
  *
  * Copyright (C) 2012 Iain Paton <ipaton0@gmail.com>
  *
  * heavily based on the sht21 driver
  * Copyright (C) 2010 Urs Fleisch <urs.fleisch@sensirion.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA
  *
  * Data sheets available (2012-06-22) at
  * http://sensing.honeywell.com/index.php?ci_id=3106&la_id=1&defId=44872
  */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
 #include <linux/hwmon.h>
 #include <linux/hwmon-sysfs.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
 #include <linux/device.h>
 #include <linux/delay.h>
 #include <linux/jiffies.h>

 /**
  * struct hih6130 - HIH-6130 device specific data
  * @hwmon_dev: device registered with hwmon
  * @lock: mutex to protect measurement values
  * @valid: only false before first measurement is taken
  * @last_update: time of last update (jiffies)
  * @temperature: cached temperature measurement value
  * @humidity: cached humidity measurement value
  * @write_length: length for I2C measurement request
  */
 struct hih6130 {
 	struct i2c_client *client;
 	struct mutex lock;
 	bool valid;
 	unsigned long last_update;
 	int temperature;
 	int humidity;
 	size_t write_length;
 };

 /**
  * hih6130_temp_ticks_to_millicelsius() - convert raw temperature ticks to
  * milli celsius
  * @ticks: temperature ticks value received from sensor
  */
 static inline int hih6130_temp_ticks_to_millicelsius(int ticks)
 {
 	ticks = ticks >> 2;
 	/*
 	 * from data sheet section 5.0
 	 * Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -40
 	 */
 	return (DIV_ROUND_CLOSEST(ticks * 1650, 16382) - 400) * 100;
 }

 /**
  * hih6130_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to
  * one-thousandths of a percent relative humidity
  * @ticks: humidity ticks value received from sensor
  */
 static inline int hih6130_rh_ticks_to_per_cent_mille(int ticks)
 {
 	ticks &= ~0xC000; /* clear status bits */
 	/*
 	 * from data sheet section 4.0
 	 * Formula RH = ( ticks / ( 2^14 -2 ) ) * 100
 	 */
 	return DIV_ROUND_CLOSEST(ticks * 1000, 16382) * 100;
 }

 /**
  * hih6130_update_measurements() - get updated measurements from device
  * @dev: device
  *
  * Returns 0 on success, else negative errno.
  */
 static int hih6130_update_measurements(struct device *dev)
 {
 	struct hih6130 *hih6130 = dev_get_drvdata(dev);
 	struct i2c_client *client = hih6130->client;
 	int ret = 0;
 	int t;
 	unsigned char tmp[4];
 	struct i2c_msg msgs[1] = {
 		{
 			.addr = client->addr,
 			.flags = I2C_M_RD,
 			.len = 4,
 			.buf = tmp,
 		}
 	};

 	mutex_lock(&hih6130->lock);

 	/*
 	 * While the measurement can be completed in ~40ms the sensor takes
 	 * much longer to react to a change in external conditions. How quickly
 	 * it reacts depends on airflow and other factors outwith our control.
 	 * The datasheet specifies maximum 'Response time' for humidity at 8s
 	 * and temperature at 30s under specified conditions.
 	 * We therefore choose to only read the sensor at most once per second.
 	 * This trades off pointless activity polling the sensor much faster
 	 * than it can react against better response times in conditions more
 	 * favourable than specified in the datasheet.
 	 */
 	if (time_after(jiffies, hih6130->last_update + HZ) || !hih6130->valid) {

 		/*
 		 * Write to slave address to request a measurement.
 		 * According with the datasheet it should be with no data, but
 		 * for systems with I2C bus drivers that do not allow zero
 		 * length packets we write one dummy byte to allow sensor
 		 * measurements on them.
 		 */
 		tmp[0] = 0;
 		ret = i2c_master_send(client, tmp, hih6130->write_length);
 		if (ret < 0)
 			goto out;

 		/* measurement cycle time is ~36.65msec */
 		msleep(40);

 		ret = i2c_transfer(client->adapter, msgs, 1);
 		if (ret < 0)
 			goto out;

 		if ((tmp[0] & 0xC0) != 0) {
 			dev_err(&client->dev, "Error while reading measurement result\n");
 			ret = -EIO;
 			goto out;
 		}

 		t = (tmp[0] << 8) + tmp[1];
 		hih6130->humidity = hih6130_rh_ticks_to_per_cent_mille(t);

 		t = (tmp[2] << 8) + tmp[3];
 		hih6130->temperature = hih6130_temp_ticks_to_millicelsius(t);

 		hih6130->last_update = jiffies;
 		hih6130->valid = true;
 	}
 out:
 	mutex_unlock(&hih6130->lock);

 	return ret >= 0 ? 0 : ret;
 }

 /**
  * hih6130_show_temperature() - show temperature measurement value in sysfs
  * @dev: device
  * @attr: device attribute
  * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
  *
  * Will be called on read access to temp1_input sysfs attribute.
  * Returns number of bytes written into buffer, negative errno on error.
  */
 static ssize_t hih6130_show_temperature(struct device *dev,
 					struct device_attribute *attr,
 					char *buf)
 {
 	struct hih6130 *hih6130 = dev_get_drvdata(dev);
 	int ret;

 	ret = hih6130_update_measurements(dev);
 	if (ret < 0)
 		return ret;
 	return sprintf(buf, "%d\n", hih6130->temperature);
 }

 /**
  * hih6130_show_humidity() - show humidity measurement value in sysfs
  * @dev: device
  * @attr: device attribute
  * @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
  *
  * Will be called on read access to humidity1_input sysfs attribute.
  * Returns number of bytes written into buffer, negative errno on error.
  */
 static ssize_t hih6130_show_humidity(struct device *dev,
 				     struct device_attribute *attr, char *buf)
 {
 	struct hih6130 *hih6130 = dev_get_drvdata(dev);
 	int ret;

 	ret = hih6130_update_measurements(dev);
 	if (ret < 0)
 		return ret;
 	return sprintf(buf, "%d\n", hih6130->humidity);
 }

 /* sysfs attributes */
 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, hih6130_show_temperature,
 	NULL, 0);
 static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, hih6130_show_humidity,
 	NULL, 0);

 static struct attribute *hih6130_attrs[] = {
 	&sensor_dev_attr_temp1_input.dev_attr.attr,
 	&sensor_dev_attr_humidity1_input.dev_attr.attr,
 	NULL
 };

 ATTRIBUTE_GROUPS(hih6130);

 static int hih6130_probe(struct i2c_client *client,
 				   const struct i2c_device_id *id)
 {
 	struct device *dev = &client->dev;
 	struct hih6130 *hih6130;
 	struct device *hwmon_dev;

 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
 		dev_err(&client->dev, "adapter does not support true I2C\n");
 		return -ENODEV;
 	}

 	hih6130 = devm_kzalloc(dev, sizeof(*hih6130), GFP_KERNEL);
 	if (!hih6130)
 		return -ENOMEM;

 	hih6130->client = client;
 	mutex_init(&hih6130->lock);

 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 							   hih6130,
 							   hih6130_groups);
 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }

 /* Device ID table */
 static const struct i2c_device_id hih6130_id[] = {
 	{ "hih6130", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, hih6130_id);

 static struct i2c_driver hih6130_driver = {
 	.driver.name = "hih6130",
 	.probe       = hih6130_probe,
 	.id_table    = hih6130_id,
 };

 module_i2c_driver(hih6130_driver);

 MODULE_AUTHOR("Iain Paton <ipaton0@gmail.com>");
 MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver");
 MODULE_LICENSE("GPL");
	/* Honeywell HIH-6130/HIH-6131 humidity and temperature sensor driver
	*
	* Copyright (C) 2012 Iain Paton <ipaton0@gmail.com>
	*
	* heavily based on the sht21 driver
	* Copyright (C) 2010 Urs Fleisch <urs.fleisch@sensirion.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA
	*
	* Data sheets available (2012-06-22) at
	* http://sensing.honeywell.com/index.php?ci_id=3106&la_id=1&defId=44872
	*/

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/slab.h>
	#include <linux/i2c.h>
	#include <linux/hwmon.h>
	#include <linux/hwmon-sysfs.h>
	#include <linux/err.h>
	#include <linux/mutex.h>
	#include <linux/device.h>
	#include <linux/delay.h>
	#include <linux/jiffies.h>

	/**
	* struct hih6130 - HIH-6130 device specific data
	* @hwmon_dev: device registered with hwmon
	* @lock: mutex to protect measurement values
	* @valid: only false before first measurement is taken
	* @last_update: time of last update (jiffies)
	* @temperature: cached temperature measurement value
	* @humidity: cached humidity measurement value
	* @write_length: length for I2C measurement request
	*/
	struct hih6130 {
	struct i2c_client *client;
	struct mutex lock;
	bool valid;
	unsigned long last_update;
	int temperature;
	int humidity;
	size_t write_length;
	};

	/**
	* hih6130_temp_ticks_to_millicelsius() - convert raw temperature ticks to
	* milli celsius
	* @ticks: temperature ticks value received from sensor
	*/
	static inline int hih6130_temp_ticks_to_millicelsius(int ticks)
	{
	ticks = ticks >> 2;
	/*
	* from data sheet section 5.0
	* Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -40
	*/
	return (DIV_ROUND_CLOSEST(ticks * 1650, 16382) - 400) * 100;
	}

	/**
	* hih6130_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to
	* one-thousandths of a percent relative humidity
	* @ticks: humidity ticks value received from sensor
	*/
	static inline int hih6130_rh_ticks_to_per_cent_mille(int ticks)
	{
	ticks &= ~0xC000; /* clear status bits */
	/*
	* from data sheet section 4.0
	* Formula RH = ( ticks / ( 2^14 -2 ) ) * 100
	*/
	return DIV_ROUND_CLOSEST(ticks * 1000, 16382) * 100;
	}

	/**
	* hih6130_update_measurements() - get updated measurements from device
	* @dev: device
	*
	* Returns 0 on success, else negative errno.
	*/
	static int hih6130_update_measurements(struct device *dev)
	{
	struct hih6130 *hih6130 = dev_get_drvdata(dev);
	struct i2c_client *client = hih6130->client;
	int ret = 0;
	int t;
	unsigned char tmp[4];
	struct i2c_msg msgs[1] = {
	{
	.addr = client->addr,
	.flags = I2C_M_RD,
	.len = 4,
	.buf = tmp,
	}
	};

	mutex_lock(&hih6130->lock);

	/*
	* While the measurement can be completed in ~40ms the sensor takes
	* much longer to react to a change in external conditions. How quickly
	* it reacts depends on airflow and other factors outwith our control.
	* The datasheet specifies maximum 'Response time' for humidity at 8s
	* and temperature at 30s under specified conditions.
	* We therefore choose to only read the sensor at most once per second.
	* This trades off pointless activity polling the sensor much faster
	* than it can react against better response times in conditions more
	* favourable than specified in the datasheet.
	*/
	if (time_after(jiffies, hih6130->last_update + HZ) \|\| !hih6130->valid) {

	/*
	* Write to slave address to request a measurement.
	* According with the datasheet it should be with no data, but
	* for systems with I2C bus drivers that do not allow zero
	* length packets we write one dummy byte to allow sensor
	* measurements on them.
	*/
	tmp[0] = 0;
	ret = i2c_master_send(client, tmp, hih6130->write_length);
	if (ret < 0)
	goto out;

	/* measurement cycle time is ~36.65msec */
	msleep(40);

	ret = i2c_transfer(client->adapter, msgs, 1);
	if (ret < 0)
	goto out;

	if ((tmp[0] & 0xC0) != 0) {
	dev_err(&client->dev, "Error while reading measurement result\n");
	ret = -EIO;
	goto out;
	}

	t = (tmp[0] << 8) + tmp[1];
	hih6130->humidity = hih6130_rh_ticks_to_per_cent_mille(t);

	t = (tmp[2] << 8) + tmp[3];
	hih6130->temperature = hih6130_temp_ticks_to_millicelsius(t);

	hih6130->last_update = jiffies;
	hih6130->valid = true;
	}
	out:
	mutex_unlock(&hih6130->lock);

	return ret >= 0 ? 0 : ret;
	}

	/**
	* hih6130_show_temperature() - show temperature measurement value in sysfs
	* @dev: device
	* @attr: device attribute
	* @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
	*
	* Will be called on read access to temp1_input sysfs attribute.
	* Returns number of bytes written into buffer, negative errno on error.
	*/
	static ssize_t hih6130_show_temperature(struct device *dev,
	struct device_attribute *attr,
	char *buf)
	{
	struct hih6130 *hih6130 = dev_get_drvdata(dev);
	int ret;

	ret = hih6130_update_measurements(dev);
	if (ret < 0)
	return ret;
	return sprintf(buf, "%d\n", hih6130->temperature);
	}

	/**
	* hih6130_show_humidity() - show humidity measurement value in sysfs
	* @dev: device
	* @attr: device attribute
	* @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
	*
	* Will be called on read access to humidity1_input sysfs attribute.
	* Returns number of bytes written into buffer, negative errno on error.
	*/
	static ssize_t hih6130_show_humidity(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct hih6130 *hih6130 = dev_get_drvdata(dev);
	int ret;

	ret = hih6130_update_measurements(dev);
	if (ret < 0)
	return ret;
	return sprintf(buf, "%d\n", hih6130->humidity);
	}

	/* sysfs attributes */
	static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, hih6130_show_temperature,
	NULL, 0);
	static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, hih6130_show_humidity,
	NULL, 0);

	static struct attribute *hih6130_attrs[] = {
	&sensor_dev_attr_temp1_input.dev_attr.attr,
	&sensor_dev_attr_humidity1_input.dev_attr.attr,
	NULL
	};

	ATTRIBUTE_GROUPS(hih6130);

	static int hih6130_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct device *dev = &client->dev;
	struct hih6130 *hih6130;
	struct device *hwmon_dev;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
	dev_err(&client->dev, "adapter does not support true I2C\n");
	return -ENODEV;
	}

	hih6130 = devm_kzalloc(dev, sizeof(*hih6130), GFP_KERNEL);
	if (!hih6130)
	return -ENOMEM;

	hih6130->client = client;
	mutex_init(&hih6130->lock);

	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
	hih6130,
	hih6130_groups);
	return PTR_ERR_OR_ZERO(hwmon_dev);
	}

	/* Device ID table */
	static const struct i2c_device_id hih6130_id[] = {
	{ "hih6130", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, hih6130_id);

	static struct i2c_driver hih6130_driver = {
	.driver.name = "hih6130",
	.probe = hih6130_probe,
	.id_table = hih6130_id,
	};

	module_i2c_driver(hih6130_driver);

	MODULE_AUTHOR("Iain Paton <ipaton0@gmail.com>");
	MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver");
	MODULE_LICENSE("GPL");