On Wed, 8 Sep 2021 17:25:24 +0200
Florian Boor <florian.boor@xxxxxxxxxxxxxxxxx> wrote:
> Make use of the AD7991_REF_SEL bit and support using the external
> reference voltage if 'vref-supply' is present.
>
> Signed-off-by: Florian Boor <florian.boor@xxxxxxxxxxxxxxxxx>
Hi Florian,
> ---
>
> Changes in v2:
> - Check if a provided external vref regulator is provided.
> - Drop unused setting
> - Add ad79xx documentation (second patch)
>
> drivers/iio/adc/ad799x.c | 21 +++++++++++++++++++--
> 1 file changed, 19 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c
> index 18bf8386d50a..2ff926a4e9b3 100644
> --- a/drivers/iio/adc/ad799x.c
> +++ b/drivers/iio/adc/ad799x.c
> @@ -770,6 +770,8 @@ static int ad799x_probe(struct i2c_client *client,
> const struct i2c_device_id *id)
> {
> int ret;
> + int extra_config = 0;
> + bool vref_external = true;
> struct ad799x_state *st;
> struct iio_dev *indio_dev;
> const struct ad799x_chip_info *chip_info =
> @@ -797,7 +799,15 @@ static int ad799x_probe(struct i2c_client *client,
> ret = regulator_enable(st->reg);
> if (ret)
> return ret;
> - st->vref = devm_regulator_get(&client->dev, "vref");
> +
> + /* check if an external reference is supplied */
> + st->vref = devm_regulator_get_optional(&client->dev, "vref");
> +
> + if (PTR_ERR(st->vref) == -ENODEV) {
> + vref_external = false;
> + /* get dummy */
> + st->vref = devm_regulator_get(&client->dev, "vref");
Why? Instead of doing this add if (st->vref) around the regulator
enable and disable. We don't want to pretend there is a regulator when
there isn't one connected and we are using VDD as the reference.
If we are in that mode, we need to change which regulator is read in
read_raw()
> + }
> if (IS_ERR(st->vref)) {
> ret = PTR_ERR(st->vref);
> goto error_disable_reg;
> @@ -806,6 +816,13 @@ static int ad799x_probe(struct i2c_client *client,
> if (ret)
> goto error_disable_reg;
>
> + /* use external reference voltage, optional if regulator present */
> + if (vref_external &&
> + ((st->id == ad7991) || (st->id == ad7995) || (st->id == ad7999))) {
> + dev_info(&client->dev, "Using external reference voltage\n");
> + extra_config |= AD7991_REF_SEL;
> + }
> +
> st->client = client;
>
> indio_dev->name = id->name;
> @@ -815,7 +832,7 @@ static int ad799x_probe(struct i2c_client *client,
> indio_dev->channels = st->chip_config->channel;
> indio_dev->num_channels = chip_info->num_channels;
>
> - ret = ad799x_update_config(st, st->chip_config->default_config);
> + ret = ad799x_update_config(st, st->chip_config->default_config | extra_config);
> if (ret)
> goto error_disable_vref;
>
