by Jonathan Cameron

[permalink] [raw]

Subject: Re: [PATCH v5 01/11] staging: iio: ad7780: add gain & filter gpio support

On Sat, 16 Mar 2019 17:46:40 +0000
Jonathan Cameron <[email protected]> wrote:

> On Fri, 15 Mar 2019 23:12:27 -0300
> Renato Lui Geh <[email protected]> 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 <[email protected]>
> > Signed-off-by: Giuliano Belinassi <[email protected]>
> > Co-developed-by: Giuliano Belinassi <[email protected]>
> Something a little odd happened when trying to use git am on this,
> but patch was happy so I did it that way. Please give it a quick
> sanity check once I push the tree out incase we have a real problem.
>
> Applied to the togreg branch of iio.git to be shortly pushed out
> as testing for the autobuilders to play with it.

Ah, we missed a 64 bit being divided below. Found by 0day.

>
> Thanks,
>
> Jonathan
>
> > ---
> > 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
> > Changes in v5:
> > - ad778x_odr_avail moved to filter patch
> > - Split gain reading to its own patch
> > - Init GPIOs in a separate function
> >
> > drivers/staging/iio/adc/ad7780.c | 114 ++++++++++++++++++++++++++-----
> > 1 file changed, 96 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/staging/iio/adc/ad7780.c b/drivers/staging/iio/adc/ad7780.c
> > index c4a85789c2db..07e5e35c92a3 100644
> > --- a/drivers/staging/iio/adc/ad7780.c
> > +++ b/drivers/staging/iio/adc/ad7780.c
> > @@ -39,6 +39,9 @@
> > #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
> > +
> > struct ad7780_chip_info {
> > struct iio_chan_spec channel;
> > unsigned int pattern_mask;
> > @@ -50,7 +53,10 @@ 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;
> > };
> > @@ -104,8 +110,10 @@ 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));
> > @@ -115,6 +123,50 @@ static int ad7780_read_raw(struct iio_dev *indio_dev,
> > 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 -EINVAL;
> > +
> > + 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);

DIV_ROUND_CLOSEST_ULL needed as vref is long long.

I'll fix up.

Jonathan

> > + 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)
> > {
> > @@ -125,13 +177,6 @@ static int ad7780_postprocess_sample(struct ad_sigma_delta *sigma_delta,
> > ((raw_sample & chip_info->pattern_mask) != chip_info->pattern))
> > return -EIO;
> >
> > - if (chip_info->is_ad778x) {
> > - if (raw_sample & AD7780_GAIN)
> > - st->gain = 1;
> > - else
> > - st->gain = 128;
> > - }
> > -
> > return 0;
> > }
> >
> > @@ -173,8 +218,47 @@ 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_init_gpios(struct device *dev, struct ad7780_state *st)
> > +{
> > + int ret;
> > +
> > + 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;
> > + }
> > +
> > + if (!st->chip_info->is_ad778x)
> > + return 0;
> > +
> nitpick: One blank line is always enough. More just reduces the amount of
> code that can be seen at a time.
>
> > +
> > + 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;
> > +}
> > +
> > static int ad7780_probe(struct spi_device *spi)
> > {
> > struct ad7780_state *st;
> > @@ -212,15 +296,9 @@ static int ad7780_probe(struct spi_device *spi)
> > indio_dev->num_channels = 1;
> > indio_dev->info = &ad7780_info;
> >
> > - st->powerdown_gpio = devm_gpiod_get_optional(&spi->dev,
> > - "powerdown",
> > - GPIOD_OUT_LOW);
> > - if (IS_ERR(st->powerdown_gpio)) {
> > - ret = PTR_ERR(st->powerdown_gpio);
> > - dev_err(&spi->dev, "Failed to request powerdown GPIO: %d\n",
> > - ret);
> > - goto error_disable_reg;
> > - }
> > + ret = ad7780_init_gpios(&spi->dev, st);
> > + if (ret)
> > + goto error_cleanup_buffer_and_trigger;
> >
> > ret = ad_sd_setup_buffer_and_trigger(indio_dev);
> > if (ret)
>