[mirror_ubuntu-bionic-kernel.git] / drivers / iio / humidity / si7020.c

/*
 * si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors
 * Copyright (c) 2013,2014  Uplogix, Inc.
 * David Barksdale <dbarksdale@uplogix.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * 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.
 */

/*
 * The Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors
 * are i2c devices which have an identical programming interface for
 * measuring relative humidity and temperature. The Si7013 has an additional
 * temperature input which this driver does not support.
 *
 * Data Sheets:
 *   Si7013: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7013.pdf
 *   Si7020: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7020.pdf
 *   Si7021: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7021.pdf
 */

#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sysfs.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>

/* Measure Relative Humidity, Hold Master Mode */
#define SI7020CMD_RH_HOLD	0xE5
/* Measure Temperature, Hold Master Mode */
#define SI7020CMD_TEMP_HOLD	0xE3
/* Software Reset */
#define SI7020CMD_RESET		0xFE

static int si7020_read_raw(struct iio_dev *indio_dev,
			   struct iio_chan_spec const *chan, int *val,
			   int *val2, long mask)
{
	struct i2c_client *client = iio_priv(indio_dev);
	int ret;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		ret = i2c_smbus_read_word_data(client,
					       chan->type == IIO_TEMP ?
					       SI7020CMD_TEMP_HOLD :
					       SI7020CMD_RH_HOLD);
		if (ret < 0)
			return ret;
		*val = ret >> 2;
		if (chan->type == IIO_HUMIDITYRELATIVE)
			*val &= GENMASK(11, 0);
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		if (chan->type == IIO_TEMP)
			*val = 175720; /* = 175.72 * 1000 */
		else
			*val = 125 * 1000;
		*val2 = 65536 >> 2;
		return IIO_VAL_FRACTIONAL;
	case IIO_CHAN_INFO_OFFSET:
		/*
		 * Since iio_convert_raw_to_processed_unlocked assumes offset
		 * is an integer we have to round these values and lose
		 * accuracy.
		 * Relative humidity will be 0.0032959% too high and
		 * temperature will be 0.00277344 degrees too high.
		 * This is no big deal because it's within the accuracy of the
		 * sensor.
		 */
		if (chan->type == IIO_TEMP)
			*val = -4368; /* = -46.85 * (65536 >> 2) / 175.72 */
		else
			*val = -786; /* = -6 * (65536 >> 2) / 125 */
		return IIO_VAL_INT;
	default:
		break;
	}

	return -EINVAL;
}

static const struct iio_chan_spec si7020_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 si7020_info = {
	.read_raw = si7020_read_raw,
	.driver_module = THIS_MODULE,
};

static int si7020_probe(struct i2c_client *client,
			const struct i2c_device_id *id)
{
	struct iio_dev *indio_dev;
	struct i2c_client **data;
	int ret;

	if (!i2c_check_functionality(client->adapter,
				     I2C_FUNC_SMBUS_WRITE_BYTE |
				     I2C_FUNC_SMBUS_READ_WORD_DATA))
		return -ENODEV;

	/* Reset device, loads default settings. */
	ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);
	if (ret < 0)
		return ret;
	/* Wait the maximum power-up time after software reset. */
	msleep(15);

	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*client));
	if (!indio_dev)
		return -ENOMEM;

	data = iio_priv(indio_dev);
	*data = client;

	indio_dev->dev.parent = &client->dev;
	indio_dev->name = dev_name(&client->dev);
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->info = &si7020_info;
	indio_dev->channels = si7020_channels;
	indio_dev->num_channels = ARRAY_SIZE(si7020_channels);

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

static const struct i2c_device_id si7020_id[] = {
	{ "si7020", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, si7020_id);

static struct i2c_driver si7020_driver = {
	.driver.name	= "si7020",
	.probe		= si7020_probe,
	.id_table	= si7020_id,
};

module_i2c_driver(si7020_driver);
MODULE_DESCRIPTION("Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors");
MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>");
MODULE_LICENSE("GPL");
Commit	Line	Data
064a7463 DB	1	/*
	2	* si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors
	3	* Copyright (c) 2013,2014 Uplogix, Inc.
	4	* David Barksdale <dbarksdale@uplogix.com>
	5	*
	6	* This program is free software; you can redistribute it and/or modify it
	7	* under the terms and conditions of the GNU General Public License,
	8	* version 2, as published by the Free Software Foundation.
	9	*
	10	* This program is distributed in the hope that it will be useful,
	11	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	13	* GNU General Public License for more details.
	14	*/
	15
	16	/*
	17	* The Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors
	18	* are i2c devices which have an identical programming interface for
	19	* measuring relative humidity and temperature. The Si7013 has an additional
	20	* temperature input which this driver does not support.
	21	*
	22	* Data Sheets:
	23	* Si7013: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7013.pdf
	24	* Si7020: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7020.pdf
	25	* Si7021: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7021.pdf
	26	*/
	27
	28	#include <linux/delay.h>
	29	#include <linux/i2c.h>
	30	#include <linux/module.h>
	31	#include <linux/slab.h>
	32	#include <linux/sysfs.h>
	33
	34	#include <linux/iio/iio.h>
	35	#include <linux/iio/sysfs.h>
	36
	37	/* Measure Relative Humidity, Hold Master Mode */
	38	#define SI7020CMD_RH_HOLD 0xE5
	39	/* Measure Temperature, Hold Master Mode */
	40	#define SI7020CMD_TEMP_HOLD 0xE3
	41	/* Software Reset */
	42	#define SI7020CMD_RESET 0xFE
	43
	44	static int si7020_read_raw(struct iio_dev *indio_dev,
	45	struct iio_chan_spec const chan, int val,
	46	int *val2, long mask)
	47	{
e0922e5e	48	struct i2c_client *client = iio_priv(indio_dev);
064a7463 DB	49	int ret;
	50
	51	switch (mask) {
	52	case IIO_CHAN_INFO_RAW:
e0922e5e	53	ret = i2c_smbus_read_word_data(client,
064a7463 DB	54	chan->type == IIO_TEMP ?
	55	SI7020CMD_TEMP_HOLD :
	56	SI7020CMD_RH_HOLD);
	57	if (ret < 0)
	58	return ret;
345b4830 HK	59	*val = ret >> 2;
	60	if (chan->type == IIO_HUMIDITYRELATIVE)
	61	*val &= GENMASK(11, 0);
064a7463 DB	62	return IIO_VAL_INT;
	63	case IIO_CHAN_INFO_SCALE:
	64	if (chan->type == IIO_TEMP)
	65	val = 175720; / = 175.72 * 1000 */
	66	else
	67	val = 125 1000;
	68	*val2 = 65536 >> 2;
	69	return IIO_VAL_FRACTIONAL;
	70	case IIO_CHAN_INFO_OFFSET:
	71	/*
	72	* Since iio_convert_raw_to_processed_unlocked assumes offset
	73	* is an integer we have to round these values and lose
	74	* accuracy.
	75	* Relative humidity will be 0.0032959% too high and
	76	* temperature will be 0.00277344 degrees too high.
	77	* This is no big deal because it's within the accuracy of the
	78	* sensor.
	79	*/
	80	if (chan->type == IIO_TEMP)
	81	val = -4368; / = -46.85 * (65536 >> 2) / 175.72 */
	82	else
	83	val = -786; / = -6 * (65536 >> 2) / 125 */
	84	return IIO_VAL_INT;
	85	default:
	86	break;
	87	}
	88
	89	return -EINVAL;
	90	}
	91
	92	static const struct iio_chan_spec si7020_channels[] = {
	93	{
	94	.type = IIO_HUMIDITYRELATIVE,
	95	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \|
	96	BIT(IIO_CHAN_INFO_SCALE) \| BIT(IIO_CHAN_INFO_OFFSET),
	97	},
	98	{
	99	.type = IIO_TEMP,
	100	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \|
	101	BIT(IIO_CHAN_INFO_SCALE) \| BIT(IIO_CHAN_INFO_OFFSET),
	102	}
	103	};
	104
	105	static const struct iio_info si7020_info = {
	106	.read_raw = si7020_read_raw,
	107	.driver_module = THIS_MODULE,
	108	};
	109
	110	static int si7020_probe(struct i2c_client *client,
	111	const struct i2c_device_id *id)
	112	{
	113	struct iio_dev *indio_dev;
	114	struct i2c_client **data;
	115	int ret;
	116
	117	if (!i2c_check_functionality(client->adapter,
	118	I2C_FUNC_SMBUS_WRITE_BYTE \|
	119	I2C_FUNC_SMBUS_READ_WORD_DATA))
	120	return -ENODEV;
	121
	122	/* Reset device, loads default settings. */
	123	ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);
	124	if (ret < 0)
	125	return ret;
126	/* Wait the maximum power-up time after software reset. */
127	msleep(15);
128
129	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*client));
130	if (!indio_dev)
131	return -ENOMEM;
132
133	data = iio_priv(indio_dev);
134	*data = client;
064a7463 DB	135
	136	indio_dev->dev.parent = &client->dev;
	137	indio_dev->name = dev_name(&client->dev);
	138	indio_dev->modes = INDIO_DIRECT_MODE;
	139	indio_dev->info = &si7020_info;
	140	indio_dev->channels = si7020_channels;
	141	indio_dev->num_channels = ARRAY_SIZE(si7020_channels);
	142
	143	return devm_iio_device_register(&client->dev, indio_dev);
	144	}
	145
	146	static const struct i2c_device_id si7020_id[] = {
	147	{ "si7020", 0 },
	148	{ }
	149	};
	150	MODULE_DEVICE_TABLE(i2c, si7020_id);
	151
	152	static struct i2c_driver si7020_driver = {
	153	.driver.name = "si7020",
	154	.probe = si7020_probe,
	155	.id_table = si7020_id,
	156	};
	157
	158	module_i2c_driver(si7020_driver);
	159	MODULE_DESCRIPTION("Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors");
	160	MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>");
	161	MODULE_LICENSE("GPL");