// SPDX-License-Identifier: GPL-2.0-only
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/*
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* si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors
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* Copyright (c) 2013,2014 Uplogix, Inc.
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* David Barksdale <dbarksdale@uplogix.com>
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*/
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/*
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* The Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors
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* are i2c devices which have an identical programming interface for
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* measuring relative humidity and temperature. The Si7013 has an additional
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* temperature input which this driver does not support.
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*
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* Data Sheets:
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* Si7013: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7013.pdf
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* Si7020: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7020.pdf
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* Si7021: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7021.pdf
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*/
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#include <linux/delay.h>
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#include <linux/i2c.h>
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#include <linux/module.h>
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#include <linux/mod_devicetable.h>
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#include <linux/slab.h>
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#include <linux/sysfs.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/sysfs.h>
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/* Measure Relative Humidity, Hold Master Mode */
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#define SI7020CMD_RH_HOLD 0xE5
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/* Measure Temperature, Hold Master Mode */
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#define SI7020CMD_TEMP_HOLD 0xE3
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/* Software Reset */
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#define SI7020CMD_RESET 0xFE
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static int si7020_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan, int *val,
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int *val2, long mask)
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{
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struct i2c_client **client = iio_priv(indio_dev);
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int ret;
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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ret = i2c_smbus_read_word_swapped(*client,
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chan->type == IIO_TEMP ?
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SI7020CMD_TEMP_HOLD :
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SI7020CMD_RH_HOLD);
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if (ret < 0)
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return ret;
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*val = ret >> 2;
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/*
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* Humidity values can slightly exceed the 0-100%RH
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* range and should be corrected by software
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*/
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if (chan->type == IIO_HUMIDITYRELATIVE)
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*val = clamp_val(*val, 786, 13893);
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return IIO_VAL_INT;
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case IIO_CHAN_INFO_SCALE:
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if (chan->type == IIO_TEMP)
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*val = 175720; /* = 175.72 * 1000 */
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else
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*val = 125 * 1000;
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*val2 = 65536 >> 2;
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return IIO_VAL_FRACTIONAL;
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case IIO_CHAN_INFO_OFFSET:
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/*
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* Since iio_convert_raw_to_processed_unlocked assumes offset
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* is an integer we have to round these values and lose
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* accuracy.
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* Relative humidity will be 0.0032959% too high and
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* temperature will be 0.00277344 degrees too high.
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* This is no big deal because it's within the accuracy of the
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* sensor.
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*/
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if (chan->type == IIO_TEMP)
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*val = -4368; /* = -46.85 * (65536 >> 2) / 175.72 */
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else
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*val = -786; /* = -6 * (65536 >> 2) / 125 */
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return IIO_VAL_INT;
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default:
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break;
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}
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return -EINVAL;
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}
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static const struct iio_chan_spec si7020_channels[] = {
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{
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.type = IIO_HUMIDITYRELATIVE,
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
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BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
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},
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{
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.type = IIO_TEMP,
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
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BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
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}
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};
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static const struct iio_info si7020_info = {
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.read_raw = si7020_read_raw,
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};
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static int si7020_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct iio_dev *indio_dev;
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struct i2c_client **data;
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int ret;
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if (!i2c_check_functionality(client->adapter,
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I2C_FUNC_SMBUS_WRITE_BYTE |
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I2C_FUNC_SMBUS_READ_WORD_DATA))
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return -EOPNOTSUPP;
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/* Reset device, loads default settings. */
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ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);
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if (ret < 0)
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return ret;
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/* Wait the maximum power-up time after software reset. */
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msleep(15);
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indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
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if (!indio_dev)
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return -ENOMEM;
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data = iio_priv(indio_dev);
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*data = client;
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indio_dev->name = dev_name(&client->dev);
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->info = &si7020_info;
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indio_dev->channels = si7020_channels;
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indio_dev->num_channels = ARRAY_SIZE(si7020_channels);
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return devm_iio_device_register(&client->dev, indio_dev);
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}
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static const struct i2c_device_id si7020_id[] = {
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{ "si7020", 0 },
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{ "th06", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, si7020_id);
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static const struct of_device_id si7020_dt_ids[] = {
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{ .compatible = "silabs,si7020" },
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{ }
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};
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MODULE_DEVICE_TABLE(of, si7020_dt_ids);
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static struct i2c_driver si7020_driver = {
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.driver = {
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.name = "si7020",
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.of_match_table = si7020_dt_ids,
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},
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.probe = si7020_probe,
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.id_table = si7020_id,
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};
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module_i2c_driver(si7020_driver);
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MODULE_DESCRIPTION("Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors");
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MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>");
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MODULE_LICENSE("GPL");
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