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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Copyright (C) 2023 Anshul Dalal <anshulusr@gmail.com>4 *5 * Driver for Aosong AGS02MA6 *7 * Datasheet:8 * https://asairsensors.com/wp-content/uploads/2021/09/AGS02MA.pdf9 * Product Page:10 * http://www.aosong.com/m/en/products-33.html11 */12 13#include <linux/crc8.h>14#include <linux/delay.h>15#include <linux/i2c.h>16#include <linux/module.h>17 18#include <linux/iio/iio.h>19 20#define AGS02MA_TVOC_READ_REG 0x0021#define AGS02MA_VERSION_REG 0x1122 23#define AGS02MA_VERSION_PROCESSING_DELAY 3024#define AGS02MA_TVOC_READ_PROCESSING_DELAY 150025 26#define AGS02MA_CRC8_INIT 0xff27#define AGS02MA_CRC8_POLYNOMIAL 0x3128 29DECLARE_CRC8_TABLE(ags02ma_crc8_table);30 31struct ags02ma_data {32 struct i2c_client *client;33};34 35struct ags02ma_reading {36 __be32 data;37 u8 crc;38} __packed;39 40static int ags02ma_register_read(struct i2c_client *client, u8 reg, u16 delay,41 u32 *val)42{43 int ret;44 u8 crc;45 struct ags02ma_reading read_buffer;46 47 ret = i2c_master_send(client, ®, sizeof(reg));48 if (ret < 0) {49 dev_err(&client->dev,50 "Failed to send data to register 0x%x: %d", reg, ret);51 return ret;52 }53 54 /* Processing Delay, Check Table 7.7 in the datasheet */55 msleep_interruptible(delay);56 57 ret = i2c_master_recv(client, (u8 *)&read_buffer, sizeof(read_buffer));58 if (ret < 0) {59 dev_err(&client->dev,60 "Failed to receive from register 0x%x: %d", reg, ret);61 return ret;62 }63 64 crc = crc8(ags02ma_crc8_table, (u8 *)&read_buffer.data,65 sizeof(read_buffer.data), AGS02MA_CRC8_INIT);66 if (crc != read_buffer.crc) {67 dev_err(&client->dev, "CRC error\n");68 return -EIO;69 }70 71 *val = be32_to_cpu(read_buffer.data);72 return 0;73}74 75static int ags02ma_read_raw(struct iio_dev *iio_device,76 struct iio_chan_spec const *chan, int *val,77 int *val2, long mask)78{79 int ret;80 struct ags02ma_data *data = iio_priv(iio_device);81 82 switch (mask) {83 case IIO_CHAN_INFO_RAW:84 ret = ags02ma_register_read(data->client, AGS02MA_TVOC_READ_REG,85 AGS02MA_TVOC_READ_PROCESSING_DELAY,86 val);87 if (ret < 0)88 return ret;89 return IIO_VAL_INT;90 case IIO_CHAN_INFO_SCALE:91 /* The sensor reads data as ppb */92 *val = 0;93 *val2 = 100;94 return IIO_VAL_INT_PLUS_NANO;95 default:96 return -EINVAL;97 }98}99 100static const struct iio_info ags02ma_info = {101 .read_raw = ags02ma_read_raw,102};103 104static const struct iio_chan_spec ags02ma_channel = {105 .type = IIO_CONCENTRATION,106 .channel2 = IIO_MOD_VOC,107 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |108 BIT(IIO_CHAN_INFO_SCALE),109};110 111static int ags02ma_probe(struct i2c_client *client)112{113 int ret;114 struct ags02ma_data *data;115 struct iio_dev *indio_dev;116 u32 version;117 118 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));119 if (!indio_dev)120 return -ENOMEM;121 122 crc8_populate_msb(ags02ma_crc8_table, AGS02MA_CRC8_POLYNOMIAL);123 124 ret = ags02ma_register_read(client, AGS02MA_VERSION_REG,125 AGS02MA_VERSION_PROCESSING_DELAY, &version);126 if (ret < 0)127 return dev_err_probe(&client->dev, ret,128 "Failed to read device version\n");129 dev_dbg(&client->dev, "Aosong AGS02MA, Version: 0x%x", version);130 131 data = iio_priv(indio_dev);132 data->client = client;133 indio_dev->info = &ags02ma_info;134 indio_dev->channels = &ags02ma_channel;135 indio_dev->num_channels = 1;136 indio_dev->name = "ags02ma";137 138 return devm_iio_device_register(&client->dev, indio_dev);139}140 141static const struct i2c_device_id ags02ma_id_table[] = {142 { "ags02ma" },143 { /* Sentinel */ }144};145MODULE_DEVICE_TABLE(i2c, ags02ma_id_table);146 147static const struct of_device_id ags02ma_of_table[] = {148 { .compatible = "aosong,ags02ma" },149 { /* Sentinel */ }150};151MODULE_DEVICE_TABLE(of, ags02ma_of_table);152 153static struct i2c_driver ags02ma_driver = {154 .driver = {155 .name = "ags02ma",156 .of_match_table = ags02ma_of_table,157 },158 .id_table = ags02ma_id_table,159 .probe = ags02ma_probe,160};161module_i2c_driver(ags02ma_driver);162 163MODULE_AUTHOR("Anshul Dalal <anshulusr@gmail.com>");164MODULE_DESCRIPTION("Aosong AGS02MA TVOC Driver");165MODULE_LICENSE("GPL");166