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166 lines
4.4 KiB
166 lines
4.4 KiB
// 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 <[email protected]> |
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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 <[email protected]>"); |
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MODULE_LICENSE("GPL");
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