Re: [PATCH v2] iio: max5487: Add support for Maxim digital potentiometers

From: Joachim Eastwood
Date: Sun Apr 10 2016 - 08:47:31 EST


Hi Cristina,

On 9 April 2016 at 10:24, Cristina Moraru <cristina.moraru09@xxxxxxxxx> wrote:
> Add implementation for Maxim MAX5487, MAX5488, MAX5489
> digital potentiometers.
>
> Datasheet:
> http://datasheets.maximintegrated.com/en/ds/MAX5487-MAX5489.pdf
>
> Signed-off-by: Cristina Moraru <cristina.moraru09@xxxxxxxxx>
> CC: Daniel Baluta <daniel.baluta@xxxxxxxxx>
> ---
...
> +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;

Newline before return.

> + 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);
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + if (val < 0 || val > MAX5487_MAX_POS)
> + return -EINVAL;
> + return regmap_write(data->regmap, chan->address, val);
> + default:
> + return -EINVAL;
> + }
> + return -EINVAL;

To be consistent with your max5487_read_raw() function you could do a:
if (mask != IIO_CHAN_INFO_RAW)
return -EINVAL;


> +static const struct iio_info max5487_info = {
> + .read_raw = &max5487_read_raw,
> + .write_raw = &max5487_write_raw,

Address operator should be unnecessary on functions.


> + data->regmap = devm_regmap_init_spi(spi, &max5487_regmap_config);
> + if (IS_ERR(data->regmap))
> + return PTR_ERR(data->regmap);

Nothing wrong with using regmap here, but since you are only using
simple regmap_write()'s you might as well have used spi_write()
directly. I am not telling you to switch, but I don't see the point of
using regmap here.

Which reminds me; for regmap you need to select REGMAP_SPI in your
Kconfig entry.


regards,
Joachim Eastwood