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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2023 Anshul Dalal <anshulusr@gmail.com>
*
* Driver for Aosong AGS02MA
*
* Datasheet:
* https://asairsensors.com/wp-content/uploads/2021/09/AGS02MA.pdf
* Product Page:
* http://www.aosong.com/m/en/products-33.html
*/
#include <linux/crc8.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/iio/iio.h>
#define AGS02MA_TVOC_READ_REG 0x00
#define AGS02MA_VERSION_REG 0x11
#define AGS02MA_VERSION_PROCESSING_DELAY 30
#define AGS02MA_TVOC_READ_PROCESSING_DELAY 1500
#define AGS02MA_CRC8_INIT 0xff
#define AGS02MA_CRC8_POLYNOMIAL 0x31
DECLARE_CRC8_TABLE(ags02ma_crc8_table);
struct ags02ma_data {
struct i2c_client *client;
};
struct ags02ma_reading {
__be32 data;
u8 crc;
} __packed;
static int ags02ma_register_read(struct i2c_client *client, u8 reg, u16 delay,
u32 *val)
{
int ret;
u8 crc;
struct ags02ma_reading read_buffer;
ret = i2c_master_send(client, ®, sizeof(reg));
if (ret < 0) {
dev_err(&client->dev,
"Failed to send data to register 0x%x: %d", reg, ret);
return ret;
}
/* Processing Delay, Check Table 7.7 in the datasheet */
msleep_interruptible(delay);
ret = i2c_master_recv(client, (u8 *)&read_buffer, sizeof(read_buffer));
if (ret < 0) {
dev_err(&client->dev,
"Failed to receive from register 0x%x: %d", reg, ret);
return ret;
}
crc = crc8(ags02ma_crc8_table, (u8 *)&read_buffer.data,
sizeof(read_buffer.data), AGS02MA_CRC8_INIT);
if (crc != read_buffer.crc) {
dev_err(&client->dev, "CRC error\n");
return -EIO;
}
*val = be32_to_cpu(read_buffer.data);
return 0;
}
static int ags02ma_read_raw(struct iio_dev *iio_device,
struct iio_chan_spec const *chan, int *val,
int *val2, long mask)
{
int ret;
struct ags02ma_data *data = iio_priv(iio_device);
switch (mask) {
case IIO_CHAN_INFO_RAW:
ret = ags02ma_register_read(data->client, AGS02MA_TVOC_READ_REG,
AGS02MA_TVOC_READ_PROCESSING_DELAY,
val);
if (ret < 0)
return ret;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
/* The sensor reads data as ppb */
*val = 0;
*val2 = 100;
return IIO_VAL_INT_PLUS_NANO;
default:
return -EINVAL;
}
}
static const struct iio_info ags02ma_info = {
.read_raw = ags02ma_read_raw,
};
static const struct iio_chan_spec ags02ma_channel = {
.type = IIO_CONCENTRATION,
.channel2 = IIO_MOD_VOC,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE),
};
static int ags02ma_probe(struct i2c_client *client)
{
int ret;
struct ags02ma_data *data;
struct iio_dev *indio_dev;
u32 version;
indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
crc8_populate_msb(ags02ma_crc8_table, AGS02MA_CRC8_POLYNOMIAL);
ret = ags02ma_register_read(client, AGS02MA_VERSION_REG,
AGS02MA_VERSION_PROCESSING_DELAY, &version);
if (ret < 0)
return dev_err_probe(&client->dev, ret,
"Failed to read device version\n");
dev_dbg(&client->dev, "Aosong AGS02MA, Version: 0x%x", version);
data = iio_priv(indio_dev);
data->client = client;
indio_dev->info = &ags02ma_info;
indio_dev->channels = &ags02ma_channel;
indio_dev->num_channels = 1;
indio_dev->name = "ags02ma";
return devm_iio_device_register(&client->dev, indio_dev);
}
static const struct i2c_device_id ags02ma_id_table[] = {
{ "ags02ma" },
{ /* Sentinel */ }
};
MODULE_DEVICE_TABLE(i2c, ags02ma_id_table);
static const struct of_device_id ags02ma_of_table[] = {
{ .compatible = "aosong,ags02ma" },
{ /* Sentinel */ }
};
MODULE_DEVICE_TABLE(of, ags02ma_of_table);
static struct i2c_driver ags02ma_driver = {
.driver = {
.name = "ags02ma",
.of_match_table = ags02ma_of_table,
},
.id_table = ags02ma_id_table,
.probe = ags02ma_probe,
};
module_i2c_driver(ags02ma_driver);
MODULE_AUTHOR("Anshul Dalal <anshulusr@gmail.com>");
MODULE_DESCRIPTION("Aosong AGS02MA TVOC Driver");
MODULE_LICENSE("GPL");
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