Re: [PATCH v3 8/8] iio: adc: ti-ads112c14: add measurement channel support

[Jonathan Cameron]

On Fri, 10 Jul 2026 17:50:41 -0500
"David Lechner (TI)" <dlechner@xxxxxxxxxxxx> wrote:

> Add support for parsing devicetree properties for measurement channels
> and doing direct reads on these.
> 
> There are quite a lot of conditions that have to be met for each
> measurement to be made, so quite a bit of state and algorithms are
> required to handle it.
> 
> Channels are created dynamically since the number of possibilities is
> unreasonably large.
> 
> Signed-off-by: David Lechner (TI) <dlechner@xxxxxxxxxxxx>
A few little things,

Thanks,

Jonathan

> ---
> v3 changes:
> * Checked error when getting "label" property.
> * Removed call of fwnode_device_is_available().
> * Used IIO_VAL_DECIMAL64_PICO for scale.
> * Added switch in ads112c14_read_avail() to reduce future diff.
> 
> v2 changes:
> * Adapted for changes in DT bindings.
> * Fixed bug in IDAC current register value calculation.
> * Fix uninitialized variable bug.
> * Fix bug in data->num_measurements calculation.
> * Use IIO_RESISTANCE instead of IIO_VOLTAGE when external reference is
>   used and it is a resistor rather than a voltage source.
> * Fix bug with negative input mux selection on single-ended measurements.
> * Fixed return checks of devm_regulator_get_enable_read_voltage().
> ---
>  drivers/iio/adc/ti-ads112c14.c | 551 +++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 533 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/iio/adc/ti-ads112c14.c b/drivers/iio/adc/ti-ads112c14.c
> index 2ce4411a0d86..a310abd69d8f 100644
> --- a/drivers/iio/adc/ti-ads112c14.c
> +++ b/drivers/iio/adc/ti-ads112c14.c
> @@ -200,9 +222,32 @@ static const struct iio_chan_spec ads112c14_sys_mon_channels[] = {
>  	},
>  };
>  
> +struct ads112c14_measurement {
> +	const char *label;
> +	u32 vref_source;
> +	u8 iunit;
> +	u8 idac1_mag;
> +	u8 idac2_mag;
> +	u8 idac1_mux;
> +	u8 idac2_mux;
> +	u8 iadc_count;
> +	u8 gain_val;
> +	u8 burnout;

Sashiko calls out that this is set but not used.
I'd leave parsing the stuff to set it for now and bring that in when
you want burnt out support.

> +	bool global_chop;
> +	bool bipolar;
> +	s64 scale_available[ARRAY_SIZE(ads112c14_pga_gains_x10)];
> +};

> @@ -257,12 +302,113 @@ static const struct regmap_config ads112c14_regmap_config = {
>  	.cache_type = REGCACHE_MAPLE,
>  };
>  
> +static int ads112c14_prepare_measurement_channel(struct ads112c14_data *data,
> +						 const struct iio_chan_spec *chan)
> +{
> +	struct ads112c14_measurement *measurement = &data->measurements[chan->scan_index];
> +	u32 refp_buf_en, refn_buf_en, ref_val, ref_sel;
> +	int ret;
> +
> +	ret = regmap_update_bits(data->regmap, ADS112C14_REG_MUX_CFG,
> +				 ADS112C14_MUX_CFG_AINP | ADS112C14_MUX_CFG_AINN,
> +				 FIELD_PREP(ADS112C14_MUX_CFG_AINP, chan->channel) |
> +				 FIELD_PREP(ADS112C14_MUX_CFG_AINN, chan->channel2));
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_update_bits(data->regmap, ADS112C14_REG_DIGITAL_CFG,
> +				 ADS112C14_DIGITAL_CFG_CODING,
> +				 FIELD_PREP(ADS112C14_DIGITAL_CFG_CODING,
> +					    measurement->bipolar ? 0 : 1));

You could use regmap_assign_bits(data->regmap, ADS112C14_REG_DIGITAL_CFG,
				 ADS112C14_DIGITAL_CFG_CODING,
				 measurement->bipolar);

I'm not particularly sure that is any clearer however so up to you.

  
> @@ -436,14 +592,29 @@ static int ads112c14_read_avail(struct iio_dev *indio_dev,
>  {
>  	struct ads112c14_data *data = iio_priv(indio_dev);
>  
> -	if (chan->channel == ADS112C14_SYS_MON_CHANNEL_SHORT) {
> -		*vals = (const int *)data->sys_mon_chan_short_scale_available;
> -		*length = 2 * ARRAY_SIZE(data->sys_mon_chan_short_scale_available);
> -		*type = IIO_VAL_DECIMAL64_PICO;
> -		return IIO_AVAIL_LIST;
> -	}
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:

Move introduction of switch to earlier patch?  Doesn't look like it would
be wrong at that point and it would reduce churn a tiny bit.

> +		if (chan->channel < ADS112C14_SYS_MON_CHANNEL_BASE) {
> +			struct ads112c14_measurement *measurement;
> +
> +			measurement = &data->measurements[chan->scan_index];
> +			*vals = (const int *)measurement->scale_available;
> +			*length = 2 * ARRAY_SIZE(measurement->scale_available);
> +			*type = IIO_VAL_DECIMAL64_PICO;
> +			return IIO_AVAIL_LIST;
> +		}
> +
> +		if (chan->channel == ADS112C14_SYS_MON_CHANNEL_SHORT) {
> +			*vals = (const int *)data->sys_mon_chan_short_scale_available;
> +			*length = 2 * ARRAY_SIZE(data->sys_mon_chan_short_scale_available);
> +			*type = IIO_VAL_DECIMAL64_PICO;
> +			return IIO_AVAIL_LIST;
> +		}
>  
> -	return -EINVAL;
> +		return -EINVAL;
> +	default:
> +		return -EINVAL;
> +	}
>  }