Re: [PATCH v4 1/9] staging: iio: ad7780: add gain & filter gpio support

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, 2019-02-28 at 11:23 -0300, Renato Lui Geh wrote:
> 
> 
> Previously, the AD7780 driver only supported gpio for the 'powerdown'
> pin. This commit adds suppport for the 'gain' and 'filter' pin.
> 
> Signed-off-by: Renato Lui Geh <renatogeh@xxxxxxxxx>
> Signed-off-by: Giuliano Belinassi <giuliano.belinassi@xxxxxx>
> Co-developed-by: Giuliano Belinassi <giuliano.belinassi@xxxxxx>
> ---
> Changes in v3:
>  - Renamed ad7780_chip_info's filter to odr
>  - Renamed ad778x_filter to ad778x_odr_avail
>  - Changed vref variable from unsigned int to unsigned long long to avoid
>    overflow
>  - Removed unnecessary AD_SD_CHANNEL macro
> Changes in v4:
>  - Removed useless macro
>  - Added default case for switch to suppress warning
>  - Removed chunks belonging to filter reading, adding these as a
>    patch for itself
> 
>  drivers/staging/iio/adc/ad7780.c | 90 +++++++++++++++++++++++++++++---
>  1 file changed, 84 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/staging/iio/adc/ad7780.c
> b/drivers/staging/iio/adc/ad7780.c
> index c4a85789c2db..87fbcf510d45 100644
> --- a/drivers/staging/iio/adc/ad7780.c
> +++ b/drivers/staging/iio/adc/ad7780.c
> @@ -39,6 +39,12 @@
>  #define AD7170_PATTERN         (AD7780_PAT0 | AD7170_PAT2)
>  #define AD7170_PATTERN_MASK    (AD7780_PAT0 | AD7780_PAT1 | AD7170_PAT2)
> 
> +#define AD7780_GAIN_MIDPOINT   64
> +#define AD7780_FILTER_MIDPOINT 13350
> +
> +static const unsigned int ad778x_gain[2]      = { 1, 128 };
> +static const unsigned int ad778x_odr_avail[2] = { 10000, 16700 };

ad778x_odr_avail[2] is not used in this patch, so it should probably go
into the next one 
(i.e. staging: iio: ad7780: add filter reading to ad778x )

one good way of catching stuff like this is to do interactive rebase and
compile your driver on each patch to see if the compiler catches this;
i suspect the compiler would have thrown an error for this change


> 
>  struct ad7780_chip_info
>         struct iio_chan_spec    channel;
>         unsigned int            pattern_mask;
> @@ -50,7 +56,10 @@ struct ad7780_state {
>         const struct ad7780_chip_info   *chip_info;
>         struct regulator                *reg;
>         struct gpio_desc                *powerdown_gpio;
> -       unsigned int    gain;
> +       struct gpio_desc                *gain_gpio;
> +       struct gpio_desc                *filter_gpio;
> +       unsigned int                    gain;
> +       unsigned int                    int_vref_mv;
> 
>         struct ad_sigma_delta sd;
>  };
> @@ -104,17 +113,65 @@ static int ad7780_read_raw(struct iio_dev
> *indio_dev,
>                 voltage_uv = regulator_get_voltage(st->reg);
>                 if (voltage_uv < 0)
>                         return voltage_uv;
> -               *val = (voltage_uv / 1000) * st->gain;
> +               voltage_uv /= 1000;
> +               *val = voltage_uv * st->gain;
>                 *val2 = chan->scan_type.realbits - 1;
> +               st->int_vref_mv = voltage_uv;
>                 return IIO_VAL_FRACTIONAL_LOG2;
>         case IIO_CHAN_INFO_OFFSET:
>                 *val = -(1 << (chan->scan_type.realbits - 1));
>                 return IIO_VAL_INT;
> +       default:
> +       break;

The indentation of the break statement is inconsistent with other places.
Still, it does not add much value adding this change as-is, since it does
not change any behavior, and is not an element needed by this change (i.e.
adding gain & filter support via gpios)

>         }
> 
>         return -EINVAL;
>  }
> 
> +static int ad7780_write_raw(struct iio_dev *indio_dev,
> +                           struct iio_chan_spec const *chan,
> +                           int val,
> +                           int val2,
> +                           long m)
> +{
> +       struct ad7780_state *st = iio_priv(indio_dev);
> +       const struct ad7780_chip_info *chip_info = st->chip_info;
> +       unsigned long long vref;
> +       unsigned int full_scale, gain;
> +
> +       if (!chip_info->is_ad778x)
> +               return 0;
> +
> +       switch (m) {
> +       case IIO_CHAN_INFO_SCALE:
> +               if (val != 0)
> +                       return -EINVAL;
> +
> +               vref = st->int_vref_mv * 1000000LL;
> +               full_scale = 1 << (chip_info->channel.scan_type.realbits
> - 1);
> +               gain = DIV_ROUND_CLOSEST(vref, full_scale);
> +               gain = DIV_ROUND_CLOSEST(gain, val2);
> +               st->gain = gain;
> +               if (gain < AD7780_GAIN_MIDPOINT)
> +                       gain = 0;
> +               else
> +                       gain = 1;
> +               gpiod_set_value(st->gain_gpio, gain);
> +               break;
> +       case IIO_CHAN_INFO_SAMP_FREQ:
> +               if (1000*val + val2/1000 < AD7780_FILTER_MIDPOINT)
> +                       val = 0;
> +               else
> +                       val = 1;
> +               gpiod_set_value(st->filter_gpio, val);
> +               break;
> +       default:
> +       break;
> +       }
> +
> +       return 0;
> +}
> +
>  static int ad7780_postprocess_sample(struct ad_sigma_delta *sigma_delta,
>                                      unsigned int raw_sample)
>  {
> @@ -126,10 +183,7 @@ static int ad7780_postprocess_sample(struct
> ad_sigma_delta *sigma_delta,
>                 return -EIO;
> 
>         if (chip_info->is_ad778x) {
> -               if (raw_sample & AD7780_GAIN)
> -                       st->gain = 1;
> -               else
> -                       st->gain = 128;
> +               st->gain = ad778x_gain[raw_sample & AD7780_GAIN];

The new `ad778x_gain[]` array could have been it's own patch, but from my
side it's fine to leave it here.
I do like this change, but it's not a patch that semantically has to do
anything with adding gain & filter gpio support.


Let's see what Jonathan says.

>         }
> 
>         return 0;
> @@ -173,6 +227,7 @@ static const struct ad7780_chip_info
> ad7780_chip_info_tbl[] = {
> 
>  static const struct iio_info ad7780_info = {
>         .read_raw = ad7780_read_raw,
> +       .write_raw = ad7780_write_raw,
>  };
> 
>  static int ad7780_probe(struct spi_device *spi)
> @@ -222,6 +277,29 @@ static int ad7780_probe(struct spi_device *spi)
>                 goto error_disable_reg;
>         }
> 
> +       if (st->chip_info->is_ad778x) {
> +               st->gain_gpio = devm_gpiod_get_optional(&spi->dev,
> +                                                       "adi,gain",
> +                                                       GPIOD_OUT_HIGH);
> +               if (IS_ERR(st->gain_gpio)) {
> +                       ret = PTR_ERR(st->gain_gpio);
> +                       dev_err(&spi->dev, "Failed to request gain GPIO:
> %d\n",
> +                               ret);
> +                       goto error_disable_reg;
> +               }
> +
> +               st->filter_gpio = devm_gpiod_get_optional(&spi->dev,
> +                                                         "adi,filter",
> +                                                         GPIOD_OUT_HIGH)
> ;
> +               if (IS_ERR(st->filter_gpio)) {
> +                       ret = PTR_ERR(st->filter_gpio);
> +                       dev_err(&spi->dev,
> +                               "Failed to request filter GPIO: %d\n",
> +                               ret);
> +                       goto error_disable_reg;
> +               }
> +       }
> +

This is just a preference of mine [feel free to ignore for this patch].
But, for this block of code, I would have added a separate function [
called something like ad7780_init_gpios(struct device *dev, struct
ad7780_state *st) )

you could also move the powerdown gpio there; and do something like

static int ad7780_init_gpios(struct device *dev, struct ad7780_state *st)
{

      st->powerdown_gpio = devm_gpiod_get_optional(dev,
                                                     "powerdown",
                                                     GPIOD_OUT_LOW);
        if (IS_ERR(st->powerdown_gpio)) {
              ret = PTR_ERR(st->powerdown_gpio);
              dev_err(dev, "Failed to request powerdown GPIO: %d\n", ret);
              return ret;
        }

       /**
        * Note Alex: I'm a big fan of keeping things to a minimal 
        * indentation level [especially where things can be elegant], 
        * but that's a preference of mine
        */
       if (!st->chip_info->is_ad778x)
           return 0;


        st->gain_gpio = devm_gpiod_get_optional(dev,
                        "adi,gain",
                        GPIOD_OUT_HIGH);
        if (IS_ERR(st->gain_gpio)) {
                ret = PTR_ERR(st->gain_gpio);
                dev_err(dev, "Failed to request gain GPIO: %d\n", ret);
                return ret;
        }

        st->filter_gpio = devm_gpiod_get_optional(dev,
                        "adi,filter",
                        GPIOD_OUT_HIGH);

        if (IS_ERR(st->filter_gpio)) {
                ret = PTR_ERR(st->filter_gpio);
                dev_err(dev, "Failed to request filter GPIO: %d\n", ret);
                return ret;
        }

        return 0;
}



>         ret = ad_sd_setup_buffer_and_trigger(indio_dev);
>         if (ret)
>                 goto error_disable_reg;
> --
> 2.21.0
> 
_______________________________________________
devel mailing list
devel@xxxxxxxxxxxxxxxxxxxxxx
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel



[Index of Archives]     [Linux Driver Backports]     [DMA Engine]     [Linux GPIO]     [Linux SPI]     [Video for Linux]     [Linux USB Devel]     [Linux Coverity]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [Yosemite Backpacking]
  Powered by Linux