Re: [PATCH v9 8/8] iio: adc: ad4030: Support common-mode channels with SPI offloading

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 16 Feb 2026 12:01:27 -0300
Marcelo Schmitt <marcelo.schmitt@analog.com> wrote:

> AD4030 and similar devices can read common-mode voltage together with
> ADC sample data. When enabled, common-mode voltage data is provided in a
> separate IIO channel since it measures something other than the primary
> ADC input signal and requires separate scaling to convert to voltage
> units. The initial SPI offload support patch for AD4030 only provided
> differential channels. Now, extend the AD4030 driver to also provide
> common-mode IIO channels when setup with SPI offloading capability.
> 
> Reviewed-by: David Lechner <dlechner@baylible.com>
> Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>


>  static int ad4030_regulators_get(struct ad4030_state *st)
> @@ -1409,43 +1422,19 @@ static int ad4030_spi_offload_setup(struct iio_dev *indio_dev,
>  static int ad4030_setup_pga(struct device *dev, struct iio_dev *indio_dev,
>  			    struct ad4030_state *st)
>  {
> -	unsigned int i;
> -	int pga_gain_dB;
> -	int ret;
> +	/* Setup GPIOs for PGA control */
> +	st->pga_gpios = devm_gpiod_get_array(dev, "pga", GPIOD_OUT_LOW);
> +	if (IS_ERR(st->pga_gpios))
> +		return dev_err_probe(dev, PTR_ERR(st->pga_gpios),
> +				     "Failed to get PGA gpios.\n");
>  
> -	ret = device_property_read_u32(dev, "adi,pga-gain-db", &pga_gain_dB);
This had me confused, but I guess is patch break up stuff you mention in reply
to Andy in patch 7.  So I'll wait for v10 before taking another look.

> -	if (ret == -EINVAL) {
> -		/* Setup GPIOs for PGA control */
> -		st->pga_gpios = devm_gpiod_get_array(dev, "pga", GPIOD_OUT_LOW);
> -		if (IS_ERR(st->pga_gpios))
> -			return dev_err_probe(dev, PTR_ERR(st->pga_gpios),
> -					     "Failed to get PGA gpios.\n");
> +	if (st->pga_gpios->ndescs != ADAQ4616_PGA_PINS)
> +		return dev_err_probe(dev, -EINVAL,
> +				     "Expected %d GPIOs for PGA control.\n",
> +				     ADAQ4616_PGA_PINS);
>  
> -		if (st->pga_gpios->ndescs != ADAQ4616_PGA_PINS)
> -			return dev_err_probe(dev, -EINVAL,
> -					     "Expected 2 GPIOs for PGA control.\n");
> -
> -		st->scale_avail_size = ARRAY_SIZE(adaq4216_hw_gains_db);
> -		st->pga_index = 0;
> -		return 0;
> -	} else if (ret) {
> -		return dev_err_probe(dev, ret, "Failed to get PGA value.\n");
> -	}
> -
> -	/* Set ADC driver to handle pin-strapped PGA pins setup */
> -	for (i = 0; i < ARRAY_SIZE(adaq4216_hw_gains_db); i++) {
> -		if (pga_gain_dB != adaq4216_hw_gains_db[i])
> -			continue;
> -
> -		st->pga_index = i;
> -		break;
> -	}
> -	if (i == ARRAY_SIZE(adaq4216_hw_gains_db))
> -		return dev_err_probe(dev, -EINVAL, "Invalid PGA gain: %d.\n",
> -				     pga_gain_dB);
> -
> -	st->scale_avail_size = 1;
> -	st->pga_gpios = NULL;
> +	st->scale_avail_size = ARRAY_SIZE(adaq4216_hw_gains_vpv);
> +	st->pga_index = 0;
>  
>  	return 0;
>  }