Re: [PATCH v3 2/2] iio: adc: ad9467: support write/read offset

[Jonathan Cameron <jic23@kernel.org>]

On Wed, 03 Dec 2025 11:05:50 +0000
Nuno Sá <noname.nuno@gmail.com> wrote:

> On Wed, 2025-12-03 at 09:28 +0000, Tomas Melin wrote:
> > Support configuring output calibration value. Among the devices
> > currently supported by this driver, this setting is specific to
> > ad9434. The offset can be used to calibrate the output against
> > a known input. The register is called offset, but the procedure
> > is best mapped internally with calibbias operation.
> > 
> > Reviewed-by: David Lechner <dlechner@baylibre.com>
> > Signed-off-by: Tomas Melin <tomas.melin@vaisala.com>
> > ---  
> 
> Still don't really like the style in .info_mask_shared_by_type and 
> .info_mask_shared_by_type_available. But ok, it seems I'm the only one. So:
> 
> Reviewed-by: Nuno Sá <nuno.sa@analog.com>

Applied but with via _calibbias added to the patch title to make
it clear this isn't via _offset which might make people waste time
wondering what is going on.

Note this is on my local tree that I might push out as testing
but will only become togreg after I rebase on rc1 in a week or so.

Thanks,

Jonathan

> 
> >  drivers/iio/adc/ad9467.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 59 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/iio/adc/ad9467.c b/drivers/iio/adc/ad9467.c
> > index 2d8f8da3671dac61994a1864a82cdbef7f54c1af..48c10acb1566ba471be0804e7c39b0b553d76188 100644
> > --- a/drivers/iio/adc/ad9467.c
> > +++ b/drivers/iio/adc/ad9467.c
> > @@ -145,6 +145,7 @@ struct ad9467_chip_info {
> >  	unsigned int num_lanes;
> >  	unsigned int dco_en;
> >  	unsigned int test_points;
> > +	const int *offset_range;
> >  	/* data clock output */
> >  	bool has_dco;
> >  	bool has_dco_invert;
> > @@ -234,6 +235,10 @@ static int ad9467_reg_access(struct iio_dev *indio_dev, unsigned int reg,
> >  	return 0;
> >  }
> >  
> > +static const int ad9434_offset_range[] = {
> > +	-128, 1, 127,
> > +};
> > +
> >  static const unsigned int ad9265_scale_table[][2] = {
> >  	{1250, 0x00}, {1500, 0x40}, {1750, 0x80}, {2000, 0xC0},
> >  };
> > @@ -298,7 +303,24 @@ static void __ad9467_get_scale(struct ad9467_state *st, int index,
> >  }
> >  
> >  static const struct iio_chan_spec ad9434_channels[] = {
> > -	AD9467_CHAN(0, BIT(IIO_CHAN_INFO_SCALE), 0, 12, 's'),
> > +	{
> > +		.type = IIO_VOLTAGE,
> > +		.indexed = 1,
> > +		.channel = 0,
> > +		.info_mask_shared_by_type =
> > +			BIT(IIO_CHAN_INFO_SCALE) |
> > +			BIT(IIO_CHAN_INFO_SAMP_FREQ) |
> > +			BIT(IIO_CHAN_INFO_CALIBBIAS),
> > +		.info_mask_shared_by_type_available =
> > +			BIT(IIO_CHAN_INFO_SCALE) |
> > +			BIT(IIO_CHAN_INFO_CALIBBIAS),
> > +		.scan_index = 0,
> > +		.scan_type = {
> > +			.sign = 's',
> > +			.realbits = 12,
> > +			.storagebits = 16,
> > +		},
> > +	},
> >  };
> >  
> >  static const struct iio_chan_spec ad9467_channels[] = {
> > @@ -367,6 +389,7 @@ static const struct ad9467_chip_info ad9434_chip_tbl = {
> >  	.default_output_mode = AD9434_DEF_OUTPUT_MODE,
> >  	.vref_mask = AD9434_REG_VREF_MASK,
> >  	.num_lanes = 6,
> > +	.offset_range = ad9434_offset_range,
> >  };
> >  
> >  static const struct ad9467_chip_info ad9265_chip_tbl = {
> > @@ -499,6 +522,33 @@ static int ad9467_set_scale(struct ad9467_state *st, int val, int val2)
> >  	return -EINVAL;
> >  }
> >  
> > +static int ad9467_get_offset(struct ad9467_state *st, int *val)
> > +{
> > +	int ret;
> > +
> > +	ret = ad9467_spi_read(st, AN877_ADC_REG_OFFSET);
> > +	if (ret < 0)
> > +		return ret;
> > +	*val = ret;
> > +
> > +	return IIO_VAL_INT;
> > +}
> > +
> > +static int ad9467_set_offset(struct ad9467_state *st, int val)
> > +{
> > +	int ret;
> > +
> > +	if (val < st->info->offset_range[0] || val > st->info->offset_range[2])
> > +		return -EINVAL;
> > +
> > +	ret = ad9467_spi_write(st, AN877_ADC_REG_OFFSET, val);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	return ad9467_spi_write(st, AN877_ADC_REG_TRANSFER,
> > +				AN877_ADC_TRANSFER_SYNC);
> > +}
> > +
> >  static int ad9467_outputmode_set(struct ad9467_state *st, unsigned int mode)
> >  {
> >  	int ret;
> > @@ -802,6 +852,8 @@ static int ad9467_read_raw(struct iio_dev *indio_dev,
> >  	struct ad9467_state *st = iio_priv(indio_dev);
> >  
> >  	switch (m) {
> > +	case IIO_CHAN_INFO_CALIBBIAS:
> > +		return ad9467_get_offset(st, val);
> >  	case IIO_CHAN_INFO_SCALE:
> >  		return ad9467_get_scale(st, val, val2);
> >  	case IIO_CHAN_INFO_SAMP_FREQ:
> > @@ -836,6 +888,8 @@ static int ad9467_write_raw(struct iio_dev *indio_dev,
> >  	int ret;
> >  
> >  	switch (mask) {
> > +	case IIO_CHAN_INFO_CALIBBIAS:
> > +		return ad9467_set_offset(st, val);
> >  	case IIO_CHAN_INFO_SCALE:
> >  		return ad9467_set_scale(st, val, val2);
> >  	case IIO_CHAN_INFO_SAMP_FREQ:
> > @@ -874,6 +928,10 @@ static int ad9467_read_avail(struct iio_dev *indio_dev,
> >  	const struct ad9467_chip_info *info = st->info;
> >  
> >  	switch (mask) {
> > +	case IIO_CHAN_INFO_CALIBBIAS:
> > +		*type = IIO_VAL_INT;
> > +		*vals = info->offset_range;
> > +		return IIO_AVAIL_RANGE;
> >  	case IIO_CHAN_INFO_SCALE:
> >  		*vals = (const int *)st->scales;
> >  		*type = IIO_VAL_INT_PLUS_MICRO;