| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors |
| * Copyright (c) 2013,2014 Uplogix, Inc. |
| * David Barksdale <dbarksdale@uplogix.com> |
| */ |
| |
| /* |
| * 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_swapped(*client, |
| chan->type == IIO_TEMP ? |
| SI7020CMD_TEMP_HOLD : |
| SI7020CMD_RH_HOLD); |
| if (ret < 0) |
| return ret; |
| *val = ret >> 2; |
| /* |
| * Humidity values can slightly exceed the 0-100%RH |
| * range and should be corrected by software |
| */ |
| if (chan->type == IIO_HUMIDITYRELATIVE) |
| *val = clamp_val(*val, 786, 13893); |
| 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, |
| }; |
| |
| 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 -EOPNOTSUPP; |
| |
| /* 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(*data)); |
| 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 }, |
| { "th06", 0 }, |
| { } |
| }; |
| MODULE_DEVICE_TABLE(i2c, si7020_id); |
| |
| static const struct of_device_id si7020_dt_ids[] = { |
| { .compatible = "silabs,si7020" }, |
| { } |
| }; |
| MODULE_DEVICE_TABLE(of, si7020_dt_ids); |
| |
| static struct i2c_driver si7020_driver = { |
| .driver = { |
| .name = "si7020", |
| .of_match_table = of_match_ptr(si7020_dt_ids), |
| }, |
| .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"); |