Re: [PATCH v6 3/5] iio: adc: ad7192: Add aincom supply

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 17 Apr 2024 20:00:52 +0300
Alisa-Dariana Roman <alisadariana@gmail.com> wrote:

> AINCOM should actually be a supply. AINx inputs are referenced to AINCOM
> in pseduo-differential operation mode. AINCOM voltage represets the
> offset of corresponding channels.
> 
> Signed-off-by: Alisa-Dariana Roman <alisa.roman@analog.com>
One request inline to make my life easier :)

Otherwise, I noticed a subset of what Andy picked up on so won't
repeat his comments!

Thanks,

Jonathan

> ---
>  drivers/iio/adc/ad7192.c | 37 +++++++++++++++++++++++++++++++++++--
>  1 file changed, 35 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7192.c b/drivers/iio/adc/ad7192.c
> index fe8dbb68a8ba..8d56cf889973 100644
> --- a/drivers/iio/adc/ad7192.c
> +++ b/drivers/iio/adc/ad7192.c
> @@ -186,6 +186,7 @@ struct ad7192_state {
>  	struct regulator		*vref;
>  	struct clk			*mclk;
>  	u16				int_vref_mv;
> +	u32				aincom_mv;
>  	u32				fclk;
>  	u32				mode;
>  	u32				conf;
> @@ -742,10 +743,19 @@ static int ad7192_read_raw(struct iio_dev *indio_dev,
>  			*val = -(1 << (chan->scan_type.realbits - 1));
>  		else
>  			*val = 0;
> +		switch (chan->type) {
> +		case IIO_VOLTAGE:
> +			if (st->aincom_mv && !chan->differential)
> +				*val += DIV_ROUND_CLOSEST_ULL((u64)st->aincom_mv * 1000000000,
> +							      st->scale_avail[gain][1]);
> +			return IIO_VAL_INT;
>  		/* Kelvin to Celsius */
> -		if (chan->type == IIO_TEMP)
> +		case IIO_TEMP:
>  			*val -= 273 * ad7192_get_temp_scale(unipolar);
> -		return IIO_VAL_INT;
> +			return IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
>  	case IIO_CHAN_INFO_SAMP_FREQ:
>  		*val = DIV_ROUND_CLOSEST(ad7192_get_f_adc(st), 1024);
>  		return IIO_VAL_INT;
> @@ -1052,6 +1062,7 @@ static int ad7192_probe(struct spi_device *spi)
>  {
>  	struct ad7192_state *st;
>  	struct iio_dev *indio_dev;
> +	struct regulator *aincom;
>  	int ret;
>  
>  	if (!spi->irq) {
> @@ -1067,6 +1078,27 @@ static int ad7192_probe(struct spi_device *spi)
>  
>  	mutex_init(&st->lock);
>  
As we are going around again, could you do me a favour and add a comment
here along the lines of.

	/*
	 * aincom is optional to maintain compatibility with older DT.
	 * Newer firmware should provide a zero volt fixed supply if
	 * this is wired to ground.	 
	 */

Aim being to discourage this getting cut and paste into other drivers
that support the common voltage from the start!


> +	aincom = devm_regulator_get_optional(&spi->dev, "aincom");
> +	if (!IS_ERR(aincom)) {
> +		ret = regulator_enable(aincom);
> +		if (ret) {
> +			dev_err(&spi->dev, "Failed to enable specified AINCOM supply\n");
> +			return ret;
> +		}
> +
> +		ret = devm_add_action_or_reset(&spi->dev, ad7192_reg_disable, aincom);
> +		if (ret)
> +			return ret;
> +
> +		ret = regulator_get_voltage(aincom);
> +		if (ret < 0)
> +			return dev_err_probe(&spi->dev, ret,
> +					     "Device tree error, AINCOM voltage undefined\n");
> +		st->aincom_mv = ret / 1000;
> +	} else {
> +		st->aincom_mv = 0;
> +	}
> +
>  	st->avdd = devm_regulator_get(&spi->dev, "avdd");
>  	if (IS_ERR(st->avdd))
>  		return PTR_ERR(st->avdd);
> @@ -1113,6 +1145,7 @@ static int ad7192_probe(struct spi_device *spi)
>  	st->int_vref_mv = ret / 1000;
>  
>  	st->chip_info = spi_get_device_match_data(spi);
> +
>  	indio_dev->name = st->chip_info->name;
>  	indio_dev->modes = INDIO_DIRECT_MODE;
>  	indio_dev->channels = st->chip_info->channels;