drivers/iio/potentiometer/max5487.c

Source file repositories/reference/linux-study-clean/drivers/iio/potentiometer/max5487.c

File Facts

System
Linux kernel
Corpus path
drivers/iio/potentiometer/max5487.c
Extension
.c
Size
3856 bytes
Lines
158
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 max5487_data {
	struct spi_device *spi;
	int kohms;
};

#define MAX5487_CHANNEL(ch, addr) {				\
	.type = IIO_RESISTANCE,					\
	.indexed = 1,						\
	.output = 1,						\
	.channel = ch,						\
	.address = addr,					\
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
}

static const struct iio_chan_spec max5487_channels[] = {
	MAX5487_CHANNEL(0, MAX5487_WRITE_WIPER_A),
	MAX5487_CHANNEL(1, MAX5487_WRITE_WIPER_B),
};

static int max5487_write_cmd(struct spi_device *spi, u16 cmd)
{
	return spi_write(spi, (const void *) &cmd, sizeof(u16));
}

static int max5487_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int *val, int *val2, long mask)
{
	struct max5487_data *data = iio_priv(indio_dev);

	if (mask != IIO_CHAN_INFO_SCALE)
		return -EINVAL;

	*val = 1000 * data->kohms;
	*val2 = MAX5487_MAX_POS;

	return IIO_VAL_FRACTIONAL;
}

static int max5487_write_raw(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan,
			     int val, int val2, long mask)
{
	struct max5487_data *data = iio_priv(indio_dev);

	if (mask != IIO_CHAN_INFO_RAW)
		return -EINVAL;

	if (val < 0 || val > MAX5487_MAX_POS)
		return -EINVAL;

	return max5487_write_cmd(data->spi, chan->address | val);
}

static const struct iio_info max5487_info = {
	.read_raw = max5487_read_raw,
	.write_raw = max5487_write_raw,
};

static int max5487_spi_probe(struct spi_device *spi)
{
	struct iio_dev *indio_dev;
	struct max5487_data *data;
	const struct spi_device_id *id = spi_get_device_id(spi);
	int ret;

	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
	if (!indio_dev)
		return -ENOMEM;

	spi_set_drvdata(spi, indio_dev);
	data = iio_priv(indio_dev);

	data->spi = spi;
	data->kohms = id->driver_data;

	indio_dev->info = &max5487_info;
	indio_dev->name = id->name;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = max5487_channels;
	indio_dev->num_channels = ARRAY_SIZE(max5487_channels);

	/* restore both wiper regs from NV regs */
	ret = max5487_write_cmd(data->spi, MAX5487_COPY_NV_TO_AB);
	if (ret < 0)
		return ret;

	return iio_device_register(indio_dev);
}

Annotation

Implementation Notes