drivers/iio/chemical/ags02ma.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2023 Anshul Dalal <anshulusr@gmail.com>
   4  *
   5  * Driver for Aosong AGS02MA
   6  *
   7  * Datasheet:
   8  *   https://asairsensors.com/wp-content/uploads/2021/09/AGS02MA.pdf
   9  * Product Page:
  10  *   http://www.aosong.com/m/en/products-33.html
  11  */
  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              0x00
  21 #define AGS02MA_VERSION_REG                0x11
  22
  23 #define AGS02MA_VERSION_PROCESSING_DELAY   30
  24 #define AGS02MA_TVOC_READ_PROCESSING_DELAY 1500
  25
  26 #define AGS02MA_CRC8_INIT                  0xff
  27 #define AGS02MA_CRC8_POLYNOMIAL            0x31
  28
  29 DECLARE_CRC8_TABLE(ags02ma_crc8_table);
  30
  31 struct ags02ma_data {
  32         struct i2c_client *client;
  33 };
  34
  35 struct ags02ma_reading {
  36         __be32 data;
  37         u8 crc;
  38 } __packed;
  39
  40 static 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, &reg, 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
  75 static 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
 100 static const struct iio_info ags02ma_info = {
 101         .read_raw = ags02ma_read_raw,
 102 };
 103
 104 static 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
 111 static 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
 141 static const struct i2c_device_id ags02ma_id_table[] = {
 142         { "ags02ma" },
 143         { /* Sentinel */ }
 144 };
 145 MODULE_DEVICE_TABLE(i2c, ags02ma_id_table);
 146
 147 static const struct of_device_id ags02ma_of_table[] = {
 148         { .compatible = "aosong,ags02ma" },
 149         { /* Sentinel */ }
 150 };
 151 MODULE_DEVICE_TABLE(of, ags02ma_of_table);
 152
 153 static 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 };
 161 module_i2c_driver(ags02ma_driver);
 162
 163 MODULE_AUTHOR("Anshul Dalal <anshulusr@gmail.com>");
 164 MODULE_DESCRIPTION("Aosong AGS02MA TVOC Driver");
 165 MODULE_LICENSE("GPL");