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Commit 049973b2 authored by Peter Meerwald's avatar Peter Meerwald Committed by Jonathan Cameron
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iio: Add si7005 relative humidity and temperature sensor driver 

sensor provides 12-bit relative humidity and 14-bit temperature
via I2C interface; temperature and linearity compensation is not
implemented (yet)

driver also supports the Si7015, but not the 2nd generation
sensors Si7013/Si7020/Si7021

datasheet is here
http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7005.pdf



v2: (thanks to Lars-Peter Clausen)
* fix coding style
* use devm_iio_device_register()
* change copyright year to 2014

Signed-off-by: default avatarPeter Meerwald <pmeerw@pmeerw.net>
Reviewed-by: default avatarLars-Peter Clausen <lars@metafoo.de>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent 4c45b1a8

drivers/iio/humidity/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -12,4 +12,14 @@ config DHT11 
	  Other sensors should work as well as long as they speak the

	  same protocol.



config SI7005

	tristate "SI7005 relative humidity and temperature sensor"

	depends on I2C

	help

	  Say yes here to build support for the Silabs Si7005 relative

	  humidity and temperature sensor.



	  To compile this driver as a module, choose M here: the module

	  will be called si7005.



endmenu

drivers/iio/humidity/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -3,3 +3,4 @@ 
#



obj-$(CONFIG_DHT11) += dht11.o

obj-$(CONFIG_SI7005) += si7005.o

drivers/iio/humidity/si7005.c

0 → 100644
+189 −0
Original line number Diff line number Diff line 
/*

 * si7005.c - Support for Silabs Si7005 humidity and temperature sensor

 *

 * Copyright (c) 2014 Peter Meerwald <pmeerw@pmeerw.net>

 *

 * This file is subject to the terms and conditions of version 2 of

 * the GNU General Public License.  See the file COPYING in the main

 * directory of this archive for more details.

 *

 * (7-bit I2C slave address 0x40)

 *

 * TODO: heater, fast mode, processed mode (temp. / linearity compensation)

 */



#include <linux/err.h>

#include <linux/i2c.h>

#include <linux/delay.h>

#include <linux/module.h>

#include <linux/pm.h>



#include <linux/iio/iio.h>

#include <linux/iio/sysfs.h>



#define SI7005_STATUS 0x00

#define SI7005_DATA 0x01 /* 16-bit, MSB */

#define SI7005_CONFIG 0x03

#define SI7005_ID 0x11



#define SI7005_STATUS_NRDY BIT(0)

#define SI7005_CONFIG_TEMP BIT(4)

#define SI7005_CONFIG_START BIT(0)



#define SI7005_ID_7005 0x50

#define SI7005_ID_7015 0xf0



struct si7005_data {

	struct i2c_client *client;

	struct mutex lock;

	u8 config;

};



static int si7005_read_measurement(struct si7005_data *data, bool temp)

{

	int tries = 50;

	int ret;



	mutex_lock(&data->lock);



	ret = i2c_smbus_write_byte_data(data->client, SI7005_CONFIG,

		data->config | SI7005_CONFIG_START |

		(temp ? SI7005_CONFIG_TEMP : 0));

	if (ret < 0)

		goto done;



	while (tries-- > 0) {

		msleep(20);

		ret = i2c_smbus_read_byte_data(data->client, SI7005_STATUS);

		if (ret < 0)

			goto done;

		if (!(ret & SI7005_STATUS_NRDY))

			break;

	}

	if (tries < 0) {

		ret = -EIO;

		goto done;

	}



	ret = i2c_smbus_read_word_swapped(data->client, SI7005_DATA);



done:

	mutex_unlock(&data->lock);



	return ret;

}



static int si7005_read_raw(struct iio_dev *indio_dev,

			    struct iio_chan_spec const *chan, int *val,

			    int *val2, long mask)

{

	struct si7005_data *data = iio_priv(indio_dev);

	int ret;



	switch (mask) {

	case IIO_CHAN_INFO_RAW:

		ret = si7005_read_measurement(data, chan->type == IIO_TEMP);

		if (ret < 0)

			return ret;

		*val = ret;

		return IIO_VAL_INT;

	case IIO_CHAN_INFO_SCALE:

		if (chan->type == IIO_TEMP) {

			*val = 7;

			*val2 = 812500;

		} else {

			*val = 3;

			*val2 = 906250;

		}

		return IIO_VAL_INT_PLUS_MICRO;

	case IIO_CHAN_INFO_OFFSET:

		if (chan->type == IIO_TEMP)

			*val = -50 * 32 * 4;

		else

			*val = -24 * 16 * 16;

		return IIO_VAL_INT;

	default:

		break;

	}



	return -EINVAL;

}



static const struct iio_chan_spec si7005_channels[] = {

	{

		.type = IIO_HUMIDITYRELATIVE,

		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |

			BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),

	},

	{

		.type = IIO_TEMP,

		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |

			BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),

	}

};



static const struct iio_info si7005_info = {

	.read_raw = si7005_read_raw,

	.driver_module = THIS_MODULE,

};



static int si7005_probe(struct i2c_client *client,

			 const struct i2c_device_id *id)

{

	struct iio_dev *indio_dev;

	struct si7005_data *data;

	int ret;



	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))

		return -ENODEV;



	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));

	if (!indio_dev)

		return -ENOMEM;



	data = iio_priv(indio_dev);

	i2c_set_clientdata(client, indio_dev);

	data->client = client;

	mutex_init(&data->lock);



	indio_dev->dev.parent = &client->dev;

	indio_dev->name = dev_name(&client->dev);

	indio_dev->modes = INDIO_DIRECT_MODE;

	indio_dev->info = &si7005_info;



	indio_dev->channels = si7005_channels;

	indio_dev->num_channels = ARRAY_SIZE(si7005_channels);



	ret = i2c_smbus_read_byte_data(client, SI7005_ID);

	if (ret < 0)

		return ret;

	if (ret != SI7005_ID_7005 && ret != SI7005_ID_7015)

		return -ENODEV;



	ret = i2c_smbus_read_byte_data(client, SI7005_CONFIG);

	if (ret < 0)

		return ret;

	data->config = ret;



	return devm_iio_device_register(&client->dev, indio_dev);

}



static const struct i2c_device_id si7005_id[] = {

	{ "si7005", 0 },

	{ }

};

MODULE_DEVICE_TABLE(i2c, si7005_id);



static struct i2c_driver si7005_driver = {

	.driver = {

		.name	= "si7005",

		.owner	= THIS_MODULE,

	},

	.probe = si7005_probe,

	.id_table = si7005_id,

};

module_i2c_driver(si7005_driver);



MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");

MODULE_DESCRIPTION("Silabs Si7005 humidity and temperature sensor driver");

MODULE_LICENSE("GPL");