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SubjectRe: [PATCH v3 1/4] staging: iio: ad7780: add gain & filter gpio support
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?
>
>> + 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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