drivers/iio/chemical/ags02ma.c

Source file repositories/reference/linux-study-clean/drivers/iio/chemical/ags02ma.c

File Facts

System
Linux kernel
Corpus path
drivers/iio/chemical/ags02ma.c
Extension
.c
Size
3966 bytes
Lines
166
Domain
Driver Families
Bucket
drivers/iio
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

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, &reg, 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;

Annotation

Implementation Notes