Re: [PATCH v2 5/5] iio: adc: add support for ad4052

[David Lechner <dlechner@baylibre.com>]

On 6/2/25 6:16 AM, Jorge Marques wrote:
> Hi David,
> 
> On Fri, Apr 25, 2025 at 06:13:48PM -0500, David Lechner wrote:
>> On 4/22/25 6:34 AM, Jorge Marques wrote:

...

>>> +static int ad4052_probe(struct spi_device *spi)
>>> +{
>>> +	const struct ad4052_chip_info *chip;
>>> +	struct device *dev = &spi->dev;
>>> +	struct iio_dev *indio_dev;
>>> +	struct ad4052_state *st;
>>> +	int ret = 0;
>>> +
>>> +	chip = spi_get_device_match_data(spi);
>>> +	if (!chip)
>>> +		return dev_err_probe(dev, -ENODEV,
>>> +				     "Could not find chip info data\n");
>>> +
>>> +	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
>>> +	if (!indio_dev)
>>> +		return -ENOMEM;
>>> +
>>> +	st = iio_priv(indio_dev);
>>> +	st->spi = spi;
>>> +	spi_set_drvdata(spi, st);
>>> +	init_completion(&st->completion);
>>> +
>>> +	st->regmap = devm_regmap_init_spi(spi, &ad4052_regmap_config);
>>> +	if (IS_ERR(st->regmap))
>>> +		return dev_err_probe(dev, PTR_ERR(st->regmap),
>>> +				     "Failed to initialize regmap\n");
>>> +
>>> +	st->mode = AD4052_SAMPLE_MODE;
>>> +	st->wait_event = false;
>>> +	st->chip = chip;
>>> +	st->grade = chip->prod_id <= 0x75 ? AD4052_2MSPS : AD4052_500KSPS;
>>> +	st->oversampling_frequency = AD4052_FS_OFFSET(st->grade);
>>> +	st->events_frequency = AD4052_FS_OFFSET(st->grade);
>>
>> Somewhere around here, we should be turning on the power supplies. Also, it
>> looks like we need some special handling to get the reference voltage. If there
>> is a supply connected to REF, use that, if not, use VDD which requires writing
>> to a register to let the chip know.
>>
> Yes, v3 will add regulators.
> Vref can be sourced from either REF (default) or VDD.
> So the idea is, if REF node not provided, set VDD as REF?
> 
Yes, you can do this with devm_regulator_get_enable_read_voltage() if it
returns -ENODEV, for the REF supply, then call it again on the VDD supply.