[linux.git] / drivers / hwmon / hih6130.c

/* Honeywell HIH-6130/HIH-6131 humidity and temperature sensor driver
 *
 * Copyright (C) 2012 Iain Paton <[email protected]>
 *
 * heavily based on the sht21 driver
 * Copyright (C) 2010 Urs Fleisch <[email protected]>
 *
 * 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
 */
struct hih6130 {
	struct device *hwmon_dev;
	struct mutex lock;
	bool valid;
	unsigned long last_update;
	int temperature;
	int humidity;
};

/**
 * 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, no data, to request a measurement */
		ret = i2c_master_send(client, tmp, 0);
		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;
	}

	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 <[email protected]>");
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 <[email protected]>
	4	*
	5	* heavily based on the sht21 driver
	6	* Copyright (C) 2010 Urs Fleisch <[email protected]>
	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
	46	*/
	47	struct hih6130 {
	48	struct device *hwmon_dev;
	49	struct mutex lock;
	50	bool valid;
	51	unsigned long last_update;
	52	int temperature;
	53	int humidity;
	54	};
	55
	56	/**
	57	* hih6130_temp_ticks_to_millicelsius() - convert raw temperature ticks to
	58	* milli celsius
	59	* @ticks: temperature ticks value received from sensor
	60	*/
	61	static inline int hih6130_temp_ticks_to_millicelsius(int ticks)
	62	{
	63
	64	ticks = ticks >> 2;
	65	/*
	66	* from data sheet section 5.0
	67	* Formula T = ( ticks / ( 2^14 - 2 ) ) * 165 -40
	68	*/
	69	return (DIV_ROUND_CLOSEST(ticks * 1650, 16382) - 400) * 100;
	70	}
	71
	72	/**
	73	* hih6130_rh_ticks_to_per_cent_mille() - convert raw humidity ticks to
	74	* one-thousandths of a percent relative humidity
	75	* @ticks: humidity ticks value received from sensor
	76	*/
	77	static inline int hih6130_rh_ticks_to_per_cent_mille(int ticks)
	78	{
	79
	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
	90	* @client: I2C client device
	91	*
	92	* Returns 0 on success, else negative errno.
	93	*/
	94	static int hih6130_update_measurements(struct i2c_client *client)
	95	{
	96	int ret = 0;
	97	int t;
	98	struct hih6130 *hih6130 = i2c_get_clientdata(client);
	99	unsigned char tmp[4];
	100	struct i2c_msg msgs[1] = {
101	{
102	.addr = client->addr,
103	.flags = I2C_M_RD,
104	.len = 4,
105	.buf = tmp,
106	}
107	};
108
109	mutex_lock(&hih6130->lock);
110
111	/*
112	* While the measurement can be completed in ~40ms the sensor takes
113	* much longer to react to a change in external conditions. How quickly
114	* it reacts depends on airflow and other factors outwith our control.
115	* The datasheet specifies maximum 'Response time' for humidity at 8s
116	* and temperature at 30s under specified conditions.
117	* We therefore choose to only read the sensor at most once per second.
118	* This trades off pointless activity polling the sensor much faster
119	* than it can react against better response times in conditions more
120	* favourable than specified in the datasheet.
121	*/
122	if (time_after(jiffies, hih6130->last_update + HZ) \|\| !hih6130->valid) {
123
124	/* write to slave address, no data, to request a measurement */
125	ret = i2c_master_send(client, tmp, 0);
126	if (ret < 0)
127	goto out;
128
129	/* measurement cycle time is ~36.65msec */
130	msleep(40);
131
132	ret = i2c_transfer(client->adapter, msgs, 1);
133	if (ret < 0)
134	goto out;
135
136	if ((tmp[0] & 0xC0) != 0) {
137	dev_err(&client->dev, "Error while reading measurement result\n");
138	ret = -EIO;
139	goto out;
140	}
141
142	t = (tmp[0] << 8) + tmp[1];
143	hih6130->humidity = hih6130_rh_ticks_to_per_cent_mille(t);
144
145	t = (tmp[2] << 8) + tmp[3];
146	hih6130->temperature = hih6130_temp_ticks_to_millicelsius(t);
147
148	hih6130->last_update = jiffies;
149	hih6130->valid = true;
150	}
151	out:
152	mutex_unlock(&hih6130->lock);
153
154	return ret >= 0 ? 0 : ret;
155	}
156
157	/**
158	* hih6130_show_temperature() - show temperature measurement value in sysfs
159	* @dev: device
160	* @attr: device attribute
161	* @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
162	*
163	* Will be called on read access to temp1_input sysfs attribute.
164	* Returns number of bytes written into buffer, negative errno on error.
165	*/
166	static ssize_t hih6130_show_temperature(struct device *dev,
167	struct device_attribute *attr,
168	char *buf)
169	{
170	struct i2c_client *client = to_i2c_client(dev);
171	struct hih6130 *hih6130 = i2c_get_clientdata(client);
172	int ret = hih6130_update_measurements(client);
173	if (ret < 0)
174	return ret;
175	return sprintf(buf, "%d\n", hih6130->temperature);
176	}
177
178	/**
179	* hih6130_show_humidity() - show humidity measurement value in sysfs
180	* @dev: device
181	* @attr: device attribute
182	* @buf: sysfs buffer (PAGE_SIZE) where measurement values are written to
183	*
184	* Will be called on read access to humidity1_input sysfs attribute.
185	* Returns number of bytes written into buffer, negative errno on error.
186	*/
187	static ssize_t hih6130_show_humidity(struct device *dev,
188	struct device_attribute attr, char buf)
189	{
190	struct i2c_client *client = to_i2c_client(dev);
191	struct hih6130 *hih6130 = i2c_get_clientdata(client);
192	int ret = hih6130_update_measurements(client);
193	if (ret < 0)
194	return ret;
195	return sprintf(buf, "%d\n", hih6130->humidity);
196	}
197
198	/* sysfs attributes */
199	static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, hih6130_show_temperature,
200	NULL, 0);
201	static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, hih6130_show_humidity,
202	NULL, 0);
203
204	static struct attribute *hih6130_attributes[] = {
205	&sensor_dev_attr_temp1_input.dev_attr.attr,
206	&sensor_dev_attr_humidity1_input.dev_attr.attr,
207	NULL
208	};
209
210	static const struct attribute_group hih6130_attr_group = {
211	.attrs = hih6130_attributes,
212	};
213
214	/**
215	* hih6130_probe() - probe device
216	* @client: I2C client device
217	* @id: device ID
218	*
219	* Called by the I2C core when an entry in the ID table matches a
220	* device's name.
221	* Returns 0 on success.
222	*/
6c931ae1	223	static int hih6130_probe(struct i2c_client *client,
27f8b135 IP	224	const struct i2c_device_id *id)
	225	{
	226	struct hih6130 *hih6130;
	227	int err;
	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
	234	hih6130 = devm_kzalloc(&client->dev, sizeof(*hih6130), GFP_KERNEL);
	235	if (!hih6130)
	236	return -ENOMEM;
	237
	238	i2c_set_clientdata(client, hih6130);
	239
	240	mutex_init(&hih6130->lock);
	241
	242	err = sysfs_create_group(&client->dev.kobj, &hih6130_attr_group);
	243	if (err) {
	244	dev_dbg(&client->dev, "could not create sysfs files\n");
	245	return err;
	246	}
	247
	248	hih6130->hwmon_dev = hwmon_device_register(&client->dev);
	249	if (IS_ERR(hih6130->hwmon_dev)) {
	250	dev_dbg(&client->dev, "unable to register hwmon device\n");
	251	err = PTR_ERR(hih6130->hwmon_dev);
	252	goto fail_remove_sysfs;
	253	}
	254
	255	return 0;
	256
	257	fail_remove_sysfs:
	258	sysfs_remove_group(&client->dev.kobj, &hih6130_attr_group);
	259	return err;
	260	}
	261
	262	/**
	263	* hih6130_remove() - remove device
	264	* @client: I2C client device
	265	*/
281dfd0b	266	static int hih6130_remove(struct i2c_client *client)
27f8b135 IP	267	{
	268	struct hih6130 *hih6130 = i2c_get_clientdata(client);
	269
	270	hwmon_device_unregister(hih6130->hwmon_dev);
	271	sysfs_remove_group(&client->dev.kobj, &hih6130_attr_group);
	272
	273	return 0;
	274	}
	275
	276	/* Device ID table */
	277	static const struct i2c_device_id hih6130_id[] = {
	278	{ "hih6130", 0 },
	279	{ }
	280	};
	281	MODULE_DEVICE_TABLE(i2c, hih6130_id);
	282
	283	static struct i2c_driver hih6130_driver = {
	284	.driver.name = "hih6130",
	285	.probe = hih6130_probe,
9e5e9b7a	286	.remove = hih6130_remove,
27f8b135 IP	287	.id_table = hih6130_id,
	288	};
	289
	290	module_i2c_driver(hih6130_driver);
	291
	292	MODULE_AUTHOR("Iain Paton <[email protected]>");
	293	MODULE_DESCRIPTION("Honeywell HIH-6130 humidity and temperature sensor driver");
	294	MODULE_LICENSE("GPL");