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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors4 * Copyright (c) 2013,2014 Uplogix, Inc.5 * David Barksdale <dbarksdale@uplogix.com>6 */7 8/*9 * The Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors10 * are i2c devices which have an identical programming interface for11 * measuring relative humidity and temperature. The Si7013 has an additional12 * temperature input which this driver does not support.13 *14 * Data Sheets:15 * Si7013: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7013.pdf16 * Si7020: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7020.pdf17 * Si7021: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7021.pdf18 */19 20#include <linux/delay.h>21#include <linux/i2c.h>22#include <linux/module.h>23#include <linux/mod_devicetable.h>24#include <linux/slab.h>25#include <linux/sysfs.h>26#include <linux/stat.h>27 28#include <linux/iio/iio.h>29#include <linux/iio/sysfs.h>30 31/* Measure Relative Humidity, Hold Master Mode */32#define SI7020CMD_RH_HOLD 0xE533/* Measure Temperature, Hold Master Mode */34#define SI7020CMD_TEMP_HOLD 0xE335/* Software Reset */36#define SI7020CMD_RESET 0xFE37#define SI7020CMD_USR_WRITE 0xE638/* "Heater Enabled" bit in the User Register */39#define SI7020_USR_HEATER_EN BIT(2)40#define SI7020CMD_HEATER_WRITE 0x5141/* Heater current configuration bits */42#define SI7020_HEATER_VAL GENMASK(3, 0)43 44struct si7020_data {45 struct i2c_client *client;46 /* Lock for cached register values */47 struct mutex lock;48 u8 user_reg;49 u8 heater_reg;50};51 52static const int si7020_heater_vals[] = { 0, 1, 0xF };53 54static int si7020_read_raw(struct iio_dev *indio_dev,55 struct iio_chan_spec const *chan, int *val,56 int *val2, long mask)57{58 struct si7020_data *data = iio_priv(indio_dev);59 int ret;60 61 switch (mask) {62 case IIO_CHAN_INFO_RAW:63 if (chan->type == IIO_CURRENT) {64 *val = data->heater_reg;65 return IIO_VAL_INT;66 }67 68 ret = i2c_smbus_read_word_swapped(data->client,69 chan->type == IIO_TEMP ?70 SI7020CMD_TEMP_HOLD :71 SI7020CMD_RH_HOLD);72 if (ret < 0)73 return ret;74 *val = ret >> 2;75 /*76 * Humidity values can slightly exceed the 0-100%RH77 * range and should be corrected by software78 */79 if (chan->type == IIO_HUMIDITYRELATIVE)80 *val = clamp_val(*val, 786, 13893);81 return IIO_VAL_INT;82 case IIO_CHAN_INFO_SCALE:83 if (chan->type == IIO_TEMP)84 *val = 175720; /* = 175.72 * 1000 */85 else86 *val = 125 * 1000;87 *val2 = 65536 >> 2;88 return IIO_VAL_FRACTIONAL;89 case IIO_CHAN_INFO_OFFSET:90 /*91 * Since iio_convert_raw_to_processed_unlocked assumes offset92 * is an integer we have to round these values and lose93 * accuracy.94 * Relative humidity will be 0.0032959% too high and95 * temperature will be 0.00277344 degrees too high.96 * This is no big deal because it's within the accuracy of the97 * sensor.98 */99 if (chan->type == IIO_TEMP)100 *val = -4368; /* = -46.85 * (65536 >> 2) / 175.72 */101 else102 *val = -786; /* = -6 * (65536 >> 2) / 125 */103 return IIO_VAL_INT;104 default:105 break;106 }107 108 return -EINVAL;109}110 111static const struct iio_chan_spec si7020_channels[] = {112 {113 .type = IIO_HUMIDITYRELATIVE,114 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |115 BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),116 },117 {118 .type = IIO_TEMP,119 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |120 BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),121 },122 {123 .type = IIO_CURRENT,124 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),125 .info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW),126 .extend_name = "heater",127 }128};129 130static int si7020_update_reg(struct si7020_data *data,131 u8 *reg, u8 cmd, u8 mask, u8 val)132{133 u8 new = (*reg & ~mask) | val;134 int ret;135 136 ret = i2c_smbus_write_byte_data(data->client, cmd, new);137 if (ret)138 return ret;139 140 *reg = new;141 142 return 0;143}144 145static int si7020_write_raw(struct iio_dev *indio_dev,146 struct iio_chan_spec const *chan,147 int val, int val2, long mask)148{149 struct si7020_data *data = iio_priv(indio_dev);150 int ret;151 152 switch (mask) {153 case IIO_CHAN_INFO_RAW:154 if (chan->type != IIO_CURRENT || val2 != 0 ||155 val < si7020_heater_vals[0] || val > si7020_heater_vals[2])156 return -EINVAL;157 158 scoped_guard(mutex, &data->lock)159 ret = si7020_update_reg(data, &data->heater_reg,160 SI7020CMD_HEATER_WRITE, SI7020_HEATER_VAL, val);161 return ret;162 default:163 return -EINVAL;164 }165}166 167static int si7020_read_available(struct iio_dev *indio_dev,168 struct iio_chan_spec const *chan,169 const int **vals,170 int *type, int *length, long mask)171{172 if (mask != IIO_CHAN_INFO_RAW || chan->type != IIO_CURRENT)173 return -EINVAL;174 175 *vals = si7020_heater_vals;176 *type = IIO_VAL_INT;177 178 return IIO_AVAIL_RANGE;179}180 181static ssize_t si7020_show_heater_en(struct device *dev,182 struct device_attribute *attr, char *buf)183{184 struct iio_dev *indio_dev = dev_to_iio_dev(dev);185 struct si7020_data *data = iio_priv(indio_dev);186 187 return sysfs_emit(buf, "%d\n", !!(data->user_reg & SI7020_USR_HEATER_EN));188}189 190static ssize_t si7020_store_heater_en(struct device *dev,191 struct device_attribute *attr,192 const char *buf, size_t len)193{194 struct iio_dev *indio_dev = dev_to_iio_dev(dev);195 struct si7020_data *data = iio_priv(indio_dev);196 int ret;197 bool val;198 199 ret = kstrtobool(buf, &val);200 if (ret)201 return ret;202 203 scoped_guard(mutex, &data->lock)204 ret = si7020_update_reg(data, &data->user_reg, SI7020CMD_USR_WRITE,205 SI7020_USR_HEATER_EN, val ? SI7020_USR_HEATER_EN : 0);206 207 return ret < 0 ? ret : len;208}209 210static IIO_DEVICE_ATTR(heater_enable, 0644,211 si7020_show_heater_en, si7020_store_heater_en, 0);212 213static struct attribute *si7020_attributes[] = {214 &iio_dev_attr_heater_enable.dev_attr.attr,215 NULL216};217 218static const struct attribute_group si7020_attribute_group = {219 .attrs = si7020_attributes,220};221 222static const struct iio_info si7020_info = {223 .read_raw = si7020_read_raw,224 .write_raw = si7020_write_raw,225 .read_avail = si7020_read_available,226 .attrs = &si7020_attribute_group,227};228 229static int si7020_probe(struct i2c_client *client)230{231 struct iio_dev *indio_dev;232 struct si7020_data *data;233 int ret;234 235 if (!i2c_check_functionality(client->adapter,236 I2C_FUNC_SMBUS_WRITE_BYTE |237 I2C_FUNC_SMBUS_READ_WORD_DATA))238 return -EOPNOTSUPP;239 240 /* Reset device, loads default settings. */241 ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);242 if (ret < 0)243 return ret;244 /* Wait the maximum power-up time after software reset. */245 msleep(15);246 247 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));248 if (!indio_dev)249 return -ENOMEM;250 251 data = iio_priv(indio_dev);252 i2c_set_clientdata(client, indio_dev);253 data->client = client;254 mutex_init(&data->lock);255 256 indio_dev->name = dev_name(&client->dev);257 indio_dev->modes = INDIO_DIRECT_MODE;258 indio_dev->info = &si7020_info;259 indio_dev->channels = si7020_channels;260 indio_dev->num_channels = ARRAY_SIZE(si7020_channels);261 262 /* All the "reserved" bits in the User Register are 1s by default */263 data->user_reg = 0x3A;264 data->heater_reg = 0x0;265 266 return devm_iio_device_register(&client->dev, indio_dev);267}268 269static const struct i2c_device_id si7020_id[] = {270 { "si7020" },271 { "th06" },272 { }273};274MODULE_DEVICE_TABLE(i2c, si7020_id);275 276static const struct of_device_id si7020_dt_ids[] = {277 { .compatible = "silabs,si7020" },278 { }279};280MODULE_DEVICE_TABLE(of, si7020_dt_ids);281 282static struct i2c_driver si7020_driver = {283 .driver = {284 .name = "si7020",285 .of_match_table = si7020_dt_ids,286 },287 .probe = si7020_probe,288 .id_table = si7020_id,289};290 291module_i2c_driver(si7020_driver);292MODULE_DESCRIPTION("Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors");293MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>");294MODULE_LICENSE("GPL");295