cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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si7020.c (4549B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * si7020.c - Silicon Labs Si7013/20/21 Relative Humidity and Temp Sensors
      4 * 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 Sensors
     10 * are i2c devices which have an identical programming interface for
     11 * measuring relative humidity and temperature. The Si7013 has an additional
     12 * temperature input which this driver does not support.
     13 *
     14 * Data Sheets:
     15 *   Si7013: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7013.pdf
     16 *   Si7020: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7020.pdf
     17 *   Si7021: http://www.silabs.com/Support%20Documents/TechnicalDocs/Si7021.pdf
     18 */
     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
     27#include <linux/iio/iio.h>
     28#include <linux/iio/sysfs.h>
     29
     30/* Measure Relative Humidity, Hold Master Mode */
     31#define SI7020CMD_RH_HOLD	0xE5
     32/* Measure Temperature, Hold Master Mode */
     33#define SI7020CMD_TEMP_HOLD	0xE3
     34/* Software Reset */
     35#define SI7020CMD_RESET		0xFE
     36
     37static int si7020_read_raw(struct iio_dev *indio_dev,
     38			   struct iio_chan_spec const *chan, int *val,
     39			   int *val2, long mask)
     40{
     41	struct i2c_client **client = iio_priv(indio_dev);
     42	int ret;
     43
     44	switch (mask) {
     45	case IIO_CHAN_INFO_RAW:
     46		ret = i2c_smbus_read_word_swapped(*client,
     47						  chan->type == IIO_TEMP ?
     48						  SI7020CMD_TEMP_HOLD :
     49						  SI7020CMD_RH_HOLD);
     50		if (ret < 0)
     51			return ret;
     52		*val = ret >> 2;
     53		/*
     54		 * Humidity values can slightly exceed the 0-100%RH
     55		 * range and should be corrected by software
     56		 */
     57		if (chan->type == IIO_HUMIDITYRELATIVE)
     58			*val = clamp_val(*val, 786, 13893);
     59		return IIO_VAL_INT;
     60	case IIO_CHAN_INFO_SCALE:
     61		if (chan->type == IIO_TEMP)
     62			*val = 175720; /* = 175.72 * 1000 */
     63		else
     64			*val = 125 * 1000;
     65		*val2 = 65536 >> 2;
     66		return IIO_VAL_FRACTIONAL;
     67	case IIO_CHAN_INFO_OFFSET:
     68		/*
     69		 * Since iio_convert_raw_to_processed_unlocked assumes offset
     70		 * is an integer we have to round these values and lose
     71		 * accuracy.
     72		 * Relative humidity will be 0.0032959% too high and
     73		 * temperature will be 0.00277344 degrees too high.
     74		 * This is no big deal because it's within the accuracy of the
     75		 * sensor.
     76		 */
     77		if (chan->type == IIO_TEMP)
     78			*val = -4368; /* = -46.85 * (65536 >> 2) / 175.72 */
     79		else
     80			*val = -786; /* = -6 * (65536 >> 2) / 125 */
     81		return IIO_VAL_INT;
     82	default:
     83		break;
     84	}
     85
     86	return -EINVAL;
     87}
     88
     89static const struct iio_chan_spec si7020_channels[] = {
     90	{
     91		.type = IIO_HUMIDITYRELATIVE,
     92		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
     93			BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
     94	},
     95	{
     96		.type = IIO_TEMP,
     97		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
     98			BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
     99	}
    100};
    101
    102static const struct iio_info si7020_info = {
    103	.read_raw = si7020_read_raw,
    104};
    105
    106static int si7020_probe(struct i2c_client *client,
    107			const struct i2c_device_id *id)
    108{
    109	struct iio_dev *indio_dev;
    110	struct i2c_client **data;
    111	int ret;
    112
    113	if (!i2c_check_functionality(client->adapter,
    114				     I2C_FUNC_SMBUS_WRITE_BYTE |
    115				     I2C_FUNC_SMBUS_READ_WORD_DATA))
    116		return -EOPNOTSUPP;
    117
    118	/* Reset device, loads default settings. */
    119	ret = i2c_smbus_write_byte(client, SI7020CMD_RESET);
    120	if (ret < 0)
    121		return ret;
    122	/* Wait the maximum power-up time after software reset. */
    123	msleep(15);
    124
    125	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
    126	if (!indio_dev)
    127		return -ENOMEM;
    128
    129	data = iio_priv(indio_dev);
    130	*data = client;
    131
    132	indio_dev->name = dev_name(&client->dev);
    133	indio_dev->modes = INDIO_DIRECT_MODE;
    134	indio_dev->info = &si7020_info;
    135	indio_dev->channels = si7020_channels;
    136	indio_dev->num_channels = ARRAY_SIZE(si7020_channels);
    137
    138	return devm_iio_device_register(&client->dev, indio_dev);
    139}
    140
    141static const struct i2c_device_id si7020_id[] = {
    142	{ "si7020", 0 },
    143	{ "th06", 0 },
    144	{ }
    145};
    146MODULE_DEVICE_TABLE(i2c, si7020_id);
    147
    148static const struct of_device_id si7020_dt_ids[] = {
    149	{ .compatible = "silabs,si7020" },
    150	{ }
    151};
    152MODULE_DEVICE_TABLE(of, si7020_dt_ids);
    153
    154static struct i2c_driver si7020_driver = {
    155	.driver = {
    156		.name = "si7020",
    157		.of_match_table = si7020_dt_ids,
    158	},
    159	.probe		= si7020_probe,
    160	.id_table	= si7020_id,
    161};
    162
    163module_i2c_driver(si7020_driver);
    164MODULE_DESCRIPTION("Silicon Labs Si7013/20/21 Relative Humidity and Temperature Sensors");
    165MODULE_AUTHOR("David Barksdale <dbarksdale@uplogix.com>");
    166MODULE_LICENSE("GPL");