drivers/iio/potentiometer/mcp4018.c

Source file repositories/reference/linux-study-clean/drivers/iio/potentiometer/mcp4018.c

File Facts

System
Linux kernel
Corpus path
drivers/iio/potentiometer/mcp4018.c
Extension
.c
Size
5023 bytes
Lines
189
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 mcp4018_cfg {
	int kohms;
};

enum mcp4018_type {
	MCP4018_502,
	MCP4018_103,
	MCP4018_503,
	MCP4018_104,
};

static const struct mcp4018_cfg mcp4018_cfg[] = {
	[MCP4018_502] = { .kohms =   5, },
	[MCP4018_103] = { .kohms =  10, },
	[MCP4018_503] = { .kohms =  50, },
	[MCP4018_104] = { .kohms = 100, },
};

struct mcp4018_data {
	struct i2c_client *client;
	const struct mcp4018_cfg *cfg;
};

static const struct iio_chan_spec mcp4018_channel = {
	.type = IIO_RESISTANCE,
	.indexed = 1,
	.output = 1,
	.channel = 0,
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
};

static int mcp4018_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int *val, int *val2, long mask)
{
	struct mcp4018_data *data = iio_priv(indio_dev);
	s32 ret;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		ret = i2c_smbus_read_byte(data->client);
		if (ret < 0)
			return ret;
		*val = ret;
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		*val = 1000 * data->cfg->kohms;
		*val2 = MCP4018_WIPER_MAX;
		return IIO_VAL_FRACTIONAL;
	}

	return -EINVAL;
}

static int mcp4018_write_raw(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan,
			     int val, int val2, long mask)
{
	struct mcp4018_data *data = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		if (val > MCP4018_WIPER_MAX || val < 0)
			return -EINVAL;
		break;
	default:
		return -EINVAL;
	}

	return i2c_smbus_write_byte(data->client, val);
}

static const struct iio_info mcp4018_info = {
	.read_raw = mcp4018_read_raw,
	.write_raw = mcp4018_write_raw,
};

#define MCP4018_ID_TABLE(_name, cfg) {				\
	.name = _name,						\
	.driver_data = (kernel_ulong_t)&mcp4018_cfg[cfg],	\
}

static const struct i2c_device_id mcp4018_id[] = {
	MCP4018_ID_TABLE("mcp4017-502", MCP4018_502),
	MCP4018_ID_TABLE("mcp4017-103", MCP4018_103),
	MCP4018_ID_TABLE("mcp4017-503", MCP4018_503),
	MCP4018_ID_TABLE("mcp4017-104", MCP4018_104),
	MCP4018_ID_TABLE("mcp4018-502", MCP4018_502),
	MCP4018_ID_TABLE("mcp4018-103", MCP4018_103),

Annotation

Implementation Notes