[linux-2.6-block.git] / drivers / hwmon / hih6130.c

/* 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);

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_QUICK))
		hih6130->write_length = 1;

	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");
Commit	Line	Data
27f8b135 IP	1	/* Honeywell HIH-6130/HIH-6131 humidity and temperature sensor driver
	2	*
	3	* Copyright (C) 2012 Iain Paton <ipaton0@gmail.com>
	4	*
	5	* heavily based on the sht21 driver
	6	* Copyright (C) 2010 Urs Fleisch <urs.fleisch@sensirion.com>
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License as published by
	10	* the Free Software Foundation; either version 2 of the License, or
	11	* (at your option) any later version.
	12	*
	13	* This program is distributed in the hope that it will be useful,
	14	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	16	* GNU General Public License for more details.
	17	*
	18	* You should have received a copy of the GNU General Public License
	19	* along with this program; if not, write to the Free Software
	20	* Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA
	21	*
	22	* Data sheets available (2012-06-22) at
	23	* http://sensing.honeywell.com/index.php?ci_id=3106&la_id=1&defId=44872
	24	*/
	25
	26	#include <linux/module.h>
	27	#include <linux/init.h>
	28	#include <linux/slab.h>
	29	#include <linux/i2c.h>
	30	#include <linux/hwmon.h>
	31	#include <linux/hwmon-sysfs.h>
	32	#include <linux/err.h>
	33	#include <linux/mutex.h>
	34	#include <linux/device.h>
	35	#include <linux/delay.h>
dcd8f392	36	#include <linux/jiffies.h>
27f8b135 IP	37
	38	/**
	39	* struct hih6130 - HIH-6130 device specific data
	40	* @hwmon_dev: device registered with hwmon
	41	* @lock: mutex to protect measurement values
	42	* @valid: only false before first measurement is taken
	43	* @last_update: time of last update (jiffies)
	44	* @temperature: cached temperature measurement value
	45	* @humidity: cached humidity measurement value
efabcc21	46	* @write_length: length for I2C measurement request
27f8b135 IP	47	*/
27f8b135 IP	48	struct hih6130 {
a5afc18c	49	struct i2c_client *client;
27f8b135 IP	50	struct mutex lock;
	51	bool valid;
	52	unsigned long last_update;
	53	int temperature;
	54	int humidity;
efabcc21	55	size_t write_length;
27f8b135 IP	56	};
	57
	58	/**
	59	* hih6130_temp_ticks_to_millicelsius() - convert raw temperature ticks to
	60	* milli celsius
	61	* @ticks: temperature ticks value received from sensor
	62	*/
	63	static inline int hih6130_temp_ticks_to_millicelsius(int ticks)
	64	{
27f8b135 IP	65	ticks = ticks >> 2;
	66	/*
	67	* from data sheet section 5.0
	68	* Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -40
	69	*/
	70	return (DIV_ROUND_CLOSEST(ticks * 1650, 16382) - 400) * 100;
	71	}
	72
	73	/**
	74	* hih6130_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to
	75	* one-thousandths of a percent relative humidity
	76	* @ticks: humidity ticks value received from sensor
	77	*/
	78	static inline int hih6130_rh_ticks_to_per_cent_mille(int ticks)
	79	{
27f8b135 IP	80	ticks &= ~0xC000; /* clear status bits */
	81	/*
	82	* from data sheet section 4.0
	83	* Formula RH = ( ticks / ( 2^14 -2 ) ) * 100
	84	*/
	85	return DIV_ROUND_CLOSEST(ticks * 1000, 16382) * 100;
	86	}
	87
	88	/**
	89	* hih6130_update_measurements() - get updated measurements from device
a5afc18c	90	* @dev: device
27f8b135 IP	91	*
	92	* Returns 0 on success, else negative errno.
	93	*/
a5afc18c	94	static int hih6130_update_measurements(struct device *dev)
27f8b135	95	{
a5afc18c AL	96	struct hih6130 *hih6130 = dev_get_drvdata(dev);
a5afc18c AL	97	struct i2c_client *client = hih6130->client;
27f8b135 IP	98	int ret = 0;
27f8b135 IP	99	int t;
27f8b135 IP	100	unsigned char tmp[4];
	101	struct i2c_msg msgs[1] = {
	102	{
	103	.addr = client->addr,
	104	.flags = I2C_M_RD,
	105	.len = 4,
	106	.buf = tmp,
	107	}
	108	};
	109
	110	mutex_lock(&hih6130->lock);
	111
	112	/*
	113	* While the measurement can be completed in ~40ms the sensor takes
	114	* much longer to react to a change in external conditions. How quickly
	115	* it reacts depends on airflow and other factors outwith our control.
	116	* The datasheet specifies maximum 'Response time' for humidity at 8s
	117	* and temperature at 30s under specified conditions.
	118	* We therefore choose to only read the sensor at most once per second.
	119	* This trades off pointless activity polling the sensor much faster
	120	* than it can react against better response times in conditions more
	121	* favourable than specified in the datasheet.
	122	*/
	123	if (time_after(jiffies, hih6130->last_update + HZ) \|\| !hih6130->valid) {
	124
efabcc21 JMG	125	/*
	126	* Write to slave address to request a measurement.
	127	* According with the datasheet it should be with no data, but
	128	* for systems with I2C bus drivers that do not allow zero
	129	* length packets we write one dummy byte to allow sensor
	130	* measurements on them.
	131	*/
	132	tmp[0] = 0;
	133	ret = i2c_master_send(client, tmp, hih6130->write_length);
27f8b135 IP	134	if (ret < 0)
	135	goto out;
	136
	137	/* measurement cycle time is ~36.65msec */
	138	msleep(40);
	139
	140	ret = i2c_transfer(client->adapter, msgs, 1);
	141	if (ret < 0)
	142	goto out;
	143
	144	if ((tmp[0] & 0xC0) != 0) {
	145	dev_err(&client->dev, "Error while reading measurement result\n");
	146	ret = -EIO;
	147	goto out;
	148	}
	149
	150	t = (tmp[0] << 8) + tmp[1];
	151	hih6130->humidity = hih6130_rh_ticks_to_per_cent_mille(t);
	152
	153	t = (tmp[2] << 8) + tmp[3];
	154	hih6130->temperature = hih6130_temp_ticks_to_millicelsius(t);
	155
	156	hih6130->last_update = jiffies;
	157	hih6130->valid = true;
	158	}
	159	out:
	160	mutex_unlock(&hih6130->lock);
	161
	162	return ret >= 0 ? 0 : ret;
	163	}
	164
	165	/**
	166	* hih6130_show_temperature() - show temperature measurement value in sysfs
	167	* @dev: device
	168	* @attr: device attribute
	169	* @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
	170	*
	171	* Will be called on read access to temp1_input sysfs attribute.
	172	* Returns number of bytes written into buffer, negative errno on error.
	173	*/
	174	static ssize_t hih6130_show_temperature(struct device *dev,
	175	struct device_attribute *attr,
	176	char *buf)
	177	{
a5afc18c AL	178	struct hih6130 *hih6130 = dev_get_drvdata(dev);
	179	int ret;
	180
	181	ret = hih6130_update_measurements(dev);
27f8b135 IP	182	if (ret < 0)
	183	return ret;
	184	return sprintf(buf, "%d\n", hih6130->temperature);
	185	}
	186
	187	/**
	188	* hih6130_show_humidity() - show humidity measurement value in sysfs
	189	* @dev: device
	190	* @attr: device attribute
	191	* @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
	192	*
	193	* Will be called on read access to humidity1_input sysfs attribute.
	194	* Returns number of bytes written into buffer, negative errno on error.
	195	*/
	196	static ssize_t hih6130_show_humidity(struct device *dev,
	197	struct device_attribute attr, char buf)
	198	{
a5afc18c AL	199	struct hih6130 *hih6130 = dev_get_drvdata(dev);
	200	int ret;
	201
	202	ret = hih6130_update_measurements(dev);
27f8b135 IP	203	if (ret < 0)
	204	return ret;
	205	return sprintf(buf, "%d\n", hih6130->humidity);
	206	}
	207
	208	/* sysfs attributes */
	209	static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, hih6130_show_temperature,
	210	NULL, 0);
	211	static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, hih6130_show_humidity,
	212	NULL, 0);
	213
a5afc18c	214	static struct attribute *hih6130_attrs[] = {
27f8b135 IP	215	&sensor_dev_attr_temp1_input.dev_attr.attr,
	216	&sensor_dev_attr_humidity1_input.dev_attr.attr,
	217	NULL
	218	};
	219
a5afc18c	220	ATTRIBUTE_GROUPS(hih6130);
27f8b135	221
6c931ae1	222	static int hih6130_probe(struct i2c_client *client,
27f8b135 IP	223	const struct i2c_device_id *id)
27f8b135 IP	224	{
a5afc18c	225	struct device *dev = &client->dev;
27f8b135	226	struct hih6130 *hih6130;
a5afc18c	227	struct device *hwmon_dev;
27f8b135 IP	228
	229	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
	230	dev_err(&client->dev, "adapter does not support true I2C\n");
	231	return -ENODEV;
	232	}
	233
a5afc18c	234	hih6130 = devm_kzalloc(dev, sizeof(*hih6130), GFP_KERNEL);
27f8b135 IP	235	if (!hih6130)
	236	return -ENOMEM;
	237
a5afc18c	238	hih6130->client = client;
27f8b135 IP	239	mutex_init(&hih6130->lock);
27f8b135 IP	240
eeeafd38 AL	241	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_QUICK))
	242	hih6130->write_length = 1;
	243
a5afc18c AL	244	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
	245	hih6130,
	246	hih6130_groups);
	247	return PTR_ERR_OR_ZERO(hwmon_dev);
27f8b135 IP	248	}
	249
	250	/* Device ID table */
	251	static const struct i2c_device_id hih6130_id[] = {
	252	{ "hih6130", 0 },
	253	{ }
	254	};
	255	MODULE_DEVICE_TABLE(i2c, hih6130_id);
	256
	257	static struct i2c_driver hih6130_driver = {
	258	.driver.name = "hih6130",
	259	.probe = hih6130_probe,
27f8b135 IP	260	.id_table = hih6130_id,
	261	};
	262
	263	module_i2c_driver(hih6130_driver);
	264
	265	MODULE_AUTHOR("Iain Paton <ipaton0@gmail.com>");
	266	MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver");
	267	MODULE_LICENSE("GPL");