Re: [PATCH v2 2/2] iio: adc: add Nuvoton NCT720x ADC driver

[Yu-Hsian Yang]

Dear David Lechner,

David Lechner <dlechner@xxxxxxxxxxxx> 於 2024年12月6日 週五 上午3:01寫道：
>
> On 12/5/24 12:22 PM, David Lechner wrote:
> > On 12/3/24 3:15 AM, Eason Yang wrote:
>
>
> >> +static int nct720x_read_raw(struct iio_dev *indio_dev,
> >> +                        struct iio_chan_spec const *chan,
> >> +                        int *val, int *val2, long mask)
> >> +{
> >> +    int index = nct720x_chan_to_index[chan->address];
> >> +    u16 volt;
> >> +    unsigned int value;
> >> +    int err;
> >> +    struct nct720x_chip_info *chip = iio_priv(indio_dev);
> >> +
> >> +    if (chan->type != IIO_VOLTAGE)
> >> +            return -EOPNOTSUPP;
> >> +
> >> +    guard(mutex)(&chip->access_lock);
> >> +    switch (mask) {
> >> +    case IIO_CHAN_INFO_RAW:
> >> +            err = regmap_read(chip->regmap16, REG_VIN[index], &value);
> >> +            if (err < 0)
> >> +                    return err;
> >> +            volt = (u16)value;
> >> +            *val = volt >> 3;
> >
> > It seems strange that this is 13 bits when the chips are 8 and 12 bit.
> >
> >> +            return IIO_VAL_INT;
> >> +    case IIO_CHAN_INFO_SCALE:
> >> +            /* From the datasheet, we have to multiply by 0.0004995 */
> >
> > The scale is the same for both 8 bit and 12 bit chips?
> >
> >> +            *val = 0;
> >> +            *val2 = 499500;
> >> +            return IIO_VAL_INT_PLUS_NANO;
> >> +    default:
> >> +            return -EINVAL;
> >> +    }
> >> +}
> >> +
>
> Sorry, I got confused. The difference between the two chips is the
> number of channels, not the number of bits. Please ignore these two
> comments.

Yes, The difference between nct7201 and nct7202 is the vin numbers.
And VOLTAGE SENSE DATA FORMAT is
Voltage(V) =13bitCountValue * 0.0004995