[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 device *hwmon_dev;
	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
 * @client: I2C client device
 *
 * Returns 0 on success, else negative errno.
 */
static int hih6130_update_measurements(struct i2c_client *client)
{
	int ret = 0;
	int t;
	struct hih6130 *hih6130 = i2c_get_clientdata(client);
	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 i2c_client *client = to_i2c_client(dev);
	struct hih6130 *hih6130 = i2c_get_clientdata(client);
	int ret = hih6130_update_measurements(client);
	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 i2c_client *client = to_i2c_client(dev);
	struct hih6130 *hih6130 = i2c_get_clientdata(client);
	int ret = hih6130_update_measurements(client);
	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_attributes[] = {
	&sensor_dev_attr_temp1_input.dev_attr.attr,
	&sensor_dev_attr_humidity1_input.dev_attr.attr,
	NULL
};

static const struct attribute_group hih6130_attr_group = {
	.attrs = hih6130_attributes,
};

/**
 * hih6130_probe() - probe device
 * @client: I2C client device
 * @id: device ID
 *
 * Called by the I2C core when an entry in the ID table matches a
 * device's name.
 * Returns 0 on success.
 */
static int hih6130_probe(struct i2c_client *client,
				   const struct i2c_device_id *id)
{
	struct hih6130 *hih6130;
	int err;

	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(&client->dev, sizeof(*hih6130), GFP_KERNEL);
	if (!hih6130)
		return -ENOMEM;

	i2c_set_clientdata(client, hih6130);

	mutex_init(&hih6130->lock);

	err = sysfs_create_group(&client->dev.kobj, &hih6130_attr_group);
	if (err) {
		dev_dbg(&client->dev, "could not create sysfs files\n");
		return err;
	}

	hih6130->hwmon_dev = hwmon_device_register(&client->dev);
	if (IS_ERR(hih6130->hwmon_dev)) {
		dev_dbg(&client->dev, "unable to register hwmon device\n");
		err = PTR_ERR(hih6130->hwmon_dev);
		goto fail_remove_sysfs;
	}

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

	return 0;

fail_remove_sysfs:
	sysfs_remove_group(&client->dev.kobj, &hih6130_attr_group);
	return err;
}

/**
 * hih6130_remove() - remove device
 * @client: I2C client device
 */
static int hih6130_remove(struct i2c_client *client)
{
	struct hih6130 *hih6130 = i2c_get_clientdata(client);

	hwmon_device_unregister(hih6130->hwmon_dev);
	sysfs_remove_group(&client->dev.kobj, &hih6130_attr_group);

	return 0;
}

/* 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,
	.remove      = hih6130_remove,
	.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	*/
	48	struct hih6130 {
	49	struct device *hwmon_dev;
	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	{
	65
	66	ticks = ticks >> 2;
	67	/*
	68	* from data sheet section 5.0
	69	* Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -40
	70	*/
	71	return (DIV_ROUND_CLOSEST(ticks * 1650, 16382) - 400) * 100;
	72	}
	73
	74	/**
	75	* hih6130_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to
	76	* one-thousandths of a percent relative humidity
	77	* @ticks: humidity ticks value received from sensor
	78	*/
	79	static inline int hih6130_rh_ticks_to_per_cent_mille(int ticks)
	80	{
	81
	82	ticks &= ~0xC000; /* clear status bits */
	83	/*
	84	* from data sheet section 4.0
	85	* Formula RH = ( ticks / ( 2^14 -2 ) ) * 100
	86	*/
	87	return DIV_ROUND_CLOSEST(ticks * 1000, 16382) * 100;
	88	}
	89
	90	/**
	91	* hih6130_update_measurements() - get updated measurements from device
	92	* @client: I2C client device
	93	*
	94	* Returns 0 on success, else negative errno.
	95	*/
	96	static int hih6130_update_measurements(struct i2c_client *client)
	97	{
	98	int ret = 0;
	99	int t;
	100	struct hih6130 *hih6130 = i2c_get_clientdata(client);
	101	unsigned char tmp[4];
	102	struct i2c_msg msgs[1] = {
	103	{
	104	.addr = client->addr,
	105	.flags = I2C_M_RD,
	106	.len = 4,
	107	.buf = tmp,
	108	}
	109	};
	110
	111	mutex_lock(&hih6130->lock);
	112
	113	/*
	114	* While the measurement can be completed in ~40ms the sensor takes
	115	* much longer to react to a change in external conditions. How quickly
	116	* it reacts depends on airflow and other factors outwith our control.
	117	* The datasheet specifies maximum 'Response time' for humidity at 8s
	118	* and temperature at 30s under specified conditions.
	119	* We therefore choose to only read the sensor at most once per second.
120	* This trades off pointless activity polling the sensor much faster
121	* than it can react against better response times in conditions more
122	* favourable than specified in the datasheet.
123	*/
124	if (time_after(jiffies, hih6130->last_update + HZ) \|\| !hih6130->valid) {
125
efabcc21 JMG	126	/*
	127	* Write to slave address to request a measurement.
	128	* According with the datasheet it should be with no data, but
	129	* for systems with I2C bus drivers that do not allow zero
	130	* length packets we write one dummy byte to allow sensor
	131	* measurements on them.
	132	*/
	133	tmp[0] = 0;
	134	ret = i2c_master_send(client, tmp, hih6130->write_length);
27f8b135 IP	135	if (ret < 0)
	136	goto out;
	137
	138	/* measurement cycle time is ~36.65msec */
	139	msleep(40);
	140
	141	ret = i2c_transfer(client->adapter, msgs, 1);
	142	if (ret < 0)
	143	goto out;
	144
	145	if ((tmp[0] & 0xC0) != 0) {
	146	dev_err(&client->dev, "Error while reading measurement result\n");
	147	ret = -EIO;
	148	goto out;
	149	}
	150
	151	t = (tmp[0] << 8) + tmp[1];
	152	hih6130->humidity = hih6130_rh_ticks_to_per_cent_mille(t);
	153
	154	t = (tmp[2] << 8) + tmp[3];
	155	hih6130->temperature = hih6130_temp_ticks_to_millicelsius(t);
	156
	157	hih6130->last_update = jiffies;
	158	hih6130->valid = true;
	159	}
	160	out:
	161	mutex_unlock(&hih6130->lock);
	162
	163	return ret >= 0 ? 0 : ret;
	164	}
	165
	166	/**
	167	* hih6130_show_temperature() - show temperature measurement value in sysfs
	168	* @dev: device
	169	* @attr: device attribute
	170	* @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
	171	*
	172	* Will be called on read access to temp1_input sysfs attribute.
	173	* Returns number of bytes written into buffer, negative errno on error.
	174	*/
	175	static ssize_t hih6130_show_temperature(struct device *dev,
	176	struct device_attribute *attr,
	177	char *buf)
	178	{
	179	struct i2c_client *client = to_i2c_client(dev);
	180	struct hih6130 *hih6130 = i2c_get_clientdata(client);
	181	int ret = hih6130_update_measurements(client);
	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	{
199	struct i2c_client *client = to_i2c_client(dev);
200	struct hih6130 *hih6130 = i2c_get_clientdata(client);
201	int ret = hih6130_update_measurements(client);
202	if (ret < 0)
203	return ret;
204	return sprintf(buf, "%d\n", hih6130->humidity);
205	}
206
207	/* sysfs attributes */
208	static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, hih6130_show_temperature,
209	NULL, 0);
210	static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, hih6130_show_humidity,
211	NULL, 0);
212
213	static struct attribute *hih6130_attributes[] = {
214	&sensor_dev_attr_temp1_input.dev_attr.attr,
215	&sensor_dev_attr_humidity1_input.dev_attr.attr,
216	NULL
217	};
218
219	static const struct attribute_group hih6130_attr_group = {
220	.attrs = hih6130_attributes,
221	};
222
223	/**
224	* hih6130_probe() - probe device
225	* @client: I2C client device
226	* @id: device ID
227	*
228	* Called by the I2C core when an entry in the ID table matches a
229	* device's name.
230	* Returns 0 on success.
231	*/
6c931ae1	232	static int hih6130_probe(struct i2c_client *client,
27f8b135 IP	233	const struct i2c_device_id *id)
	234	{
	235	struct hih6130 *hih6130;
	236	int err;
	237
	238	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
	239	dev_err(&client->dev, "adapter does not support true I2C\n");
	240	return -ENODEV;
	241	}
	242
	243	hih6130 = devm_kzalloc(&client->dev, sizeof(*hih6130), GFP_KERNEL);
	244	if (!hih6130)
	245	return -ENOMEM;
	246
	247	i2c_set_clientdata(client, hih6130);
	248
	249	mutex_init(&hih6130->lock);
	250
	251	err = sysfs_create_group(&client->dev.kobj, &hih6130_attr_group);
	252	if (err) {
	253	dev_dbg(&client->dev, "could not create sysfs files\n");
	254	return err;
	255	}
	256
	257	hih6130->hwmon_dev = hwmon_device_register(&client->dev);
	258	if (IS_ERR(hih6130->hwmon_dev)) {
	259	dev_dbg(&client->dev, "unable to register hwmon device\n");
	260	err = PTR_ERR(hih6130->hwmon_dev);
	261	goto fail_remove_sysfs;
	262	}
	263
efabcc21 JMG	264	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_QUICK))
	265	hih6130->write_length = 1;
	266
27f8b135 IP	267	return 0;
	268
	269	fail_remove_sysfs:
	270	sysfs_remove_group(&client->dev.kobj, &hih6130_attr_group);
	271	return err;
	272	}
	273
	274	/**
	275	* hih6130_remove() - remove device
	276	* @client: I2C client device
	277	*/
281dfd0b	278	static int hih6130_remove(struct i2c_client *client)
27f8b135 IP	279	{
	280	struct hih6130 *hih6130 = i2c_get_clientdata(client);
	281
	282	hwmon_device_unregister(hih6130->hwmon_dev);
	283	sysfs_remove_group(&client->dev.kobj, &hih6130_attr_group);
	284
	285	return 0;
	286	}
	287
	288	/* Device ID table */
	289	static const struct i2c_device_id hih6130_id[] = {
	290	{ "hih6130", 0 },
	291	{ }
	292	};
	293	MODULE_DEVICE_TABLE(i2c, hih6130_id);
	294
	295	static struct i2c_driver hih6130_driver = {
	296	.driver.name = "hih6130",
	297	.probe = hih6130_probe,
9e5e9b7a	298	.remove = hih6130_remove,
27f8b135 IP	299	.id_table = hih6130_id,
	300	};
	301
	302	module_i2c_driver(hih6130_driver);
	303
	304	MODULE_AUTHOR("Iain Paton <ipaton0@gmail.com>");
	305	MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver");
	306	MODULE_LICENSE("GPL");