Re: [PATCH v6 9/9] iio: adc: ad7173: Add support for AD411x devices

From: Ceclan, Dumitru
Date: Fri Jun 07 2024 - 05:41:54 EST


On 07/06/2024 12:20, Nuno Sá wrote:
> On Thu, 2024-06-06 at 19:07 +0300, Dumitru Ceclan via B4 Relay wrote:
>> From: Dumitru Ceclan <dumitru.ceclan@xxxxxxxxxx>
>>
>> Add support for AD4111/AD4112/AD4114/AD4115/AD4116.
>>
>> The AD411X family encompasses a series of low power, low noise, 24-bit,
>> sigma-delta analog-to-digital converters that offer a versatile range of
>> specifications.
>>
>> This family of ADCs integrates an analog front end suitable for processing
>> both fully differential and single-ended, bipolar voltage inputs
>> addressing a wide array of industrial and instrumentation requirements.
>>
>> - All ADCs have inputs with a precision voltage divider with a division
>>   ratio of 10.
>> - AD4116 has 5 low level inputs without a voltage divider.
>> - AD4111 and AD4112 support current inputs (0 mA to 20 mA) using a 50ohm
>>   shunt resistor.
>>
>> Signed-off-by: Dumitru Ceclan <dumitru.ceclan@xxxxxxxxxx>
>> ---
>>  drivers/iio/adc/ad7173.c | 317 ++++++++++++++++++++++++++++++++++++++++++----
>> -
>>  1 file changed, 285 insertions(+), 32 deletions(-)
>>
>> diff --git a/drivers/iio/adc/ad7173.c b/drivers/iio/adc/ad7173.c
>> index 58da5717fd36..cfcd12447e24 100644
>> --- a/drivers/iio/adc/ad7173.c
>> +++ b/drivers/iio/adc/ad7173.c
>>
> ...
>
>>  static const struct ad7173_device_info ad7172_2_device_info = {
>>   .name = "ad7172-2",
>>   .id = AD7172_2_ID,
>> - .num_inputs = 5,
>> + .num_voltage_in = 5,
>>   .num_channels = 4,
>>   .num_configs = 4,
>>   .num_gpios = 2,
>> + .higher_gpio_bits = false,
>
> No need to explicitly set to 'false'. Ditto for the other places...
>
> ...
>
>>
>>  static int ad7173_validate_voltage_ain_inputs(struct ad7173_state *st,
>>         unsigned int ain0, unsigned int
>> ain1)
>>  {
>> @@ -946,15 +1145,30 @@ static int ad7173_validate_voltage_ain_inputs(struct
>> ad7173_state *st,
>>       st->info->has_pow_supply_monitoring)
>>   return 0;
>>  
>> - special_input0 = AD7173_IS_REF_INPUT(ain0);
>> - special_input1 = AD7173_IS_REF_INPUT(ain1);
>> + special_input0 = AD7173_IS_REF_INPUT(ain0) ||
>> + (ain0 == AD4111_VINCOM_INPUT && st->info-
>>> has_vincom_input);
>> + special_input1 = AD7173_IS_REF_INPUT(ain1) ||
>> + (ain1 == AD4111_VINCOM_INPUT && st->info-
>>> has_vincom_input);
>> +
>
> Wondering... can ain1 (or ain0) be AD4111_VINCOM_INPUT and !st->info-
>> has_vincom_input? Would that actually be acceptable? It would assume it's not
> so we should check that right? Or am I missing something?
>
> - Nuno Sá
>

It will fail when we check for the number of voltage inputs:
(ain0 >= st->info->num_voltage_in && !special_input0)
as special_input will not be true if has_vincom_input is false

Indeed this check is a bit hidden, should it be more explicit?