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SubjectRe: [PATCH v3 1/4] staging: iio: ad7780: add gain & filter gpio support
On Thu, 14 Feb 2019 18:31:12 -0200
Renato Lui Geh <renatogeh@gmail.com> wrote:

> Hi Jonathan,
>
> Thanks for the review. Comments inline.
>
> Renato
>
> On 02/09, Jonathan Cameron wrote:
> >On Tue, 5 Feb 2019 15:13:00 -0200
> >Renato Lui Geh <renatogeh@gmail.com> 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@gmail.com>
> >> Signed-off-by: Giuliano Belinassi <giuliano.belinassi@usp.br>
> >> Co-developed-by: Giuliano Belinassi <giuliano.belinassi@usp.br>
> >Comments inline.
> >
> >> ---
> >> 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
> >>
> >> drivers/staging/iio/adc/ad7780.c | 95 ++++++++++++++++++++++++++++++--
> >> 1 file changed, 89 insertions(+), 6 deletions(-)
> >>
> >> diff --git a/drivers/staging/iio/adc/ad7780.c b/drivers/staging/iio/adc/ad7780.c
> >> index c4a85789c2db..6e4357800d31 100644
> >> --- a/drivers/staging/iio/adc/ad7780.c
> >> +++ b/drivers/staging/iio/adc/ad7780.c
> >> @@ -39,6 +39,15 @@
> >> #define AD7170_PATTERN (AD7780_PAT0 | AD7170_PAT2)
> >> #define AD7170_PATTERN_MASK (AD7780_PAT0 | AD7780_PAT1 | AD7170_PAT2)
> >>
> >> +#define AD7780_GAIN_GPIO 0
> >> +#define AD7780_FILTER_GPIO 1
> >What are these for?
>
> Sorry about that. That's leftover from a previous attempt.
> >
> >> +
> >> +#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 };
> >> +
> >> struct ad7780_chip_info {
> >> struct iio_chan_spec channel;
> >> unsigned int pattern_mask;
> >> @@ -50,7 +59,11 @@ 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 odr;
> >> + unsigned int int_vref_mv;
> >>
> >> struct ad_sigma_delta sd;
> >> };
> >> @@ -104,17 +117,65 @@ 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;
> >> + case IIO_CHAN_INFO_SAMP_FREQ:
> >> + *val = st->odr;
> >> + return IIO_VAL_INT;
> >> }
> >>
> >> 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;
> >> + st->odr = ad778x_odr_avail[val];
> >> + gpiod_set_value(st->filter_gpio, val);
> >> + break;
> >> + }
> >> +
> >> + return 0;
> >> +}
> >> +
> >> static int ad7780_postprocess_sample(struct ad_sigma_delta *sigma_delta,
> >> unsigned int raw_sample)
> >> {
> >> @@ -126,10 +187,8 @@ 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];
> >> + st->odr = ad778x_odr_avail[raw_sample & AD7780_FILTER];
> >> }
> >>
> >> return 0;
> >> @@ -173,6 +232,7 @@ 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 +282,29 @@ 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,
> >> + "gain",
> >
> >These are not particularly standard names (basically not "reset"),
> >so they should be vendor prefixed, so that people know to go
> >look at the device specific binding.
>
> I see. Should they be something like "adi,gain" and "adi,filter"? Am I
> correct to assume that I'll have to somehow mention these in the
> dt-binding?
yes and yes - name is just adi,gain-gpios rather than gain-gpios.

Take a look at the other drivers doing the same thing. We used to
be more lax on this so there are drivers without the prefixes, but
can't fix them now.

Jonathan

> >
> >> + 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,
> >> + "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;
> >> + }
> >> + }
> >> +
> >> ret = ad_sd_setup_buffer_and_trigger(indio_dev);
> >> if (ret)
> >> goto error_disable_reg;
> >


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