Re: [PATCH v6 07/17] iio: adc: at91-sama5d2_adc: adapt the driver for sama7d65

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 6 Aug 2026 13:10:14 +0530
Varshini Rajendran <varshini.rajendran@microchip.com> wrote:

> Add support for sama7d65 ADC. The differences are highlighted with the
> compatible. The calibration data layout is the main difference.
> 
> Update Kconfig help text to mention SAMA7 SoC family support.
> 
> Signed-off-by: Varshini Rajendran <varshini.rajendran@microchip.com>

The Sashiko feedback on this one is interesting.

https://sashiko.dev/#/patchset/20260806074024.531259-1-varshini.rajendran%40microchip.com

The timestamp in the chan_spec array isn't the last one - the
timestamp comes after it which is going to break in various
unhelpful ways - as iio_push_to_buffers_with_timestamp() requires
the timestamp to be the last scan index.

in at91_adc_trigger_handler_nodma() there is a comment saying
that it can only be used with voltage channels. That's fine but
if they aren't useful, why are the scan_index values not -1
which is how we hide those interfaces for channels for which
buffered capture is not supported.

Given you have the hardware set up, can you check if the
scan_elements/*_en is there for the temp channel and
that for cases where it is enabled, we get an error in the
buffer preenable callback?

So I think it's a false positive but fair enough given the
current user interfaces seems likely to be rather odd.

Please sanity check all this.

One other thing inline.

Jonathan


> ---
>  drivers/iio/adc/Kconfig            |  2 +-
>  drivers/iio/adc/at91-sama5d2_adc.c | 30 ++++++++++++++++++++++++++++++
>  2 files changed, 31 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 3755a81c1efd..85b443853a08 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -647,7 +647,7 @@ config AT91_SAMA5D2_ADC
>  	select IIO_TRIGGERED_BUFFER
>  	help
>  	  Say yes here to build support for Atmel SAMA5D2 ADC which is
> -	  available on SAMA5D2 SoC family.
> +	  available on SAMA5D2 and SAMA7 SoC families.
>  
>  	  To compile this driver as a module, choose M here: the module will be
>  	  called at91-sama5d2_adc.
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index 3e9feb824a66..c1e5139a058c 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -528,6 +528,15 @@ static const struct at91_adc_temp_calib_layout sama7g5_temp_calib = {
>  	.p1_scale = { .numerator = 1000, .denominator = 1 },
>  };
>  
> +static const struct at91_adc_temp_calib_layout sama7d65_temp_calib = {
> +	.tag_idx = 1,
> +	.p1_idx = 3,
> +	.p4_idx = 2,
> +	.p6_idx = 5,
> +	.min_len = 11,
> +	.p1_scale = { .numerator = 1, .denominator = 1000 },
> +};
> +
>  /* Temperature sensor calibration - Vtemp voltage sensitivity to temperature. */
>  #define AT91_ADC_TS_VTEMP_DT		(2080U)
>  
> @@ -766,6 +775,24 @@ static const struct at91_adc_platform sama7g5_platform = {
>  	.temp_calib_layout = &sama7g5_temp_calib,
>  };
>  
> +static const struct at91_adc_platform sama7d65_platform = {
> +	.layout = &sama7g5_layout,
> +	.adc_channels = &at91_sama7g5_adc_channels,
> +	.nr_channels = AT91_SAMA7G5_SINGLE_CHAN_CNT +
> +		       AT91_SAMA7G5_DIFF_CHAN_CNT +
> +		       AT91_SAMA7G5_TEMP_CHAN_CNT,
> +	.max_channels = ARRAY_SIZE(at91_sama7g5_adc_channels),
> +	.max_index = AT91_SAMA7G5_MAX_CHAN_IDX,
> +	.hw_trig_cnt = AT91_SAMA7G5_HW_TRIG_CNT,
> +	.osr_mask = GENMASK(18, 16),
> +	.oversampling_avail = { 1, 4, 16, 64, 256 },
> +	.oversampling_avail_no = 5,
> +	.chan_realbits = 16,
> +	.temp_sensor = true,
> +	.temp_chan = AT91_SAMA7G5_ADC_TEMP_CHANNEL,
Is this ever used?

> +	.temp_calib_layout = &sama7d65_temp_calib,
> +};
> +
>  static int at91_adc_chan_xlate(struct iio_dev *indio_dev, int chan)
>  {
>  	int i;
> @@ -2632,6 +2659,9 @@ static const struct of_device_id at91_adc_dt_match[] = {
>  	}, {
>  		.compatible = "microchip,sama7g5-adc",
>  		.data = &sama7g5_platform,
> +	}, {
> +		.compatible = "microchip,sama7d65-adc",
> +		.data = &sama7d65_platform,
>  	}, {
>  		/* sentinel */
>  	}