Re: [PATCH v2 1/2] staging: iio: ad7780: add gain & filter gpio support

[Popa, Stefan Serban]

On Du, 2019-01-27 at 18:30 -0200, 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 v2:
> ÂÂÂÂÂÂÂÂ- Filter reading changed to mHz
> ÂÂÂÂÂÂÂÂ- Storing filter, gain and voltage to chip_info

Hi,

Comments inline.

Regards,
Stefan

> 
> Âdrivers/staging/iio/adc/ad7780.cÂÂÂÂÂÂÂ| 103 ++++++++++++++++++++++---
> Âinclude/linux/iio/adc/ad_sigma_delta.h |ÂÂÂ5 ++
> Â2 files changed, 99 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/staging/iio/adc/ad7780.c
> b/drivers/staging/iio/adc/ad7780.c
> index c4a85789c2db..82394e31b168 100644
> --- a/drivers/staging/iio/adc/ad7780.c
> +++ b/drivers/staging/iio/adc/ad7780.c
> @@ -39,6 +39,15 @@
> Â#define AD7170_PATTERNÂÂÂÂÂÂÂÂÂ(AD7780_PAT0 | AD7170_PAT2)
> Â#define AD7170_PATTERN_MASKÂÂÂÂ(AD7780_PAT0 | AD7780_PAT1 | AD7170_PAT2)
> 
> +#define AD7780_GAIN_GPIOÂÂÂÂÂÂÂ0
> +#define AD7780_FILTER_GPIOÂÂÂÂÂ1
> +
> +#define AD7780_GAIN_MIDPOINTÂÂÂ64
> +#define AD7780_FILTER_MIDPOINT 13350
> +
> +static const unsigned int ad778x_gain[2]ÂÂÂÂ= { 1, 128 };
> +static const unsigned int ad778x_filter[2]ÂÂ= { 10000, 16700 };
I would name this array ad778x_odr_avail or something like that. We should
also consider adding the option to read the available sampling frequencies
from user space, but let's leave this for another commit.
> +
> Âstruct ad7780_chip_info {
> ÂÂÂÂÂÂÂÂstruct iio_chan_specÂÂÂÂchannel;
> ÂÂÂÂÂÂÂÂunsigned intÂÂÂÂÂÂÂÂÂÂÂÂpattern_mask;
> @@ -50,7 +59,11 @@ struct ad7780_state {
> ÂÂÂÂÂÂÂÂconst struct ad7780_chip_infoÂÂÂ*chip_info;
> ÂÂÂÂÂÂÂÂstruct regulatorÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ*reg;
> ÂÂÂÂÂÂÂÂstruct gpio_descÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ*powerdown_gpio;
> -ÂÂÂÂÂÂÂunsigned intÂÂÂÂgain;
> +ÂÂÂÂÂÂÂstruct gpio_descÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ*gain_gpio;
> +ÂÂÂÂÂÂÂstruct gpio_descÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ*filter_gpio;
> +ÂÂÂÂÂÂÂunsigned intÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂgain;
> +ÂÂÂÂÂÂÂunsigned intÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂfilter;

Also, this could be renamed as odr.

> +ÂÂÂÂÂÂÂunsigned intÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂint_vref_mv;
> 
> ÂÂÂÂÂÂÂÂstruct ad_sigma_delta sd;
> Â};
> @@ -104,17 +117,65 @@ static int ad7780_read_raw(struct iio_dev
> *indio_dev,
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂvoltage_uv = regulator_get_voltage(st->reg);
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂif (voltage_uv < 0)
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂreturn voltage_uv;
> -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ*val = (voltage_uv / 1000) * st->gain;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂvoltage_uv /= 1000;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ*val = voltage_uv * st->gain;
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ*val2 = chan->scan_type.realbits - 1;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂst->int_vref_mv = voltage_uv;
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂreturn IIO_VAL_FRACTIONAL_LOG2;
> ÂÂÂÂÂÂÂÂcase IIO_CHAN_INFO_OFFSET:
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ*val = -(1 << (chan->scan_type.realbits - 1));
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂreturn IIO_VAL_INT;
> +ÂÂÂÂÂÂÂcase IIO_CHAN_INFO_SAMP_FREQ:
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ*val = st->filter;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂreturn IIO_VAL_INT;
> ÂÂÂÂÂÂÂÂ}
> 
> ÂÂÂÂÂÂÂÂreturn -EINVAL;
> Â}
> 
> +static int ad7780_write_raw(struct iio_dev *indio_dev,
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂstruct iio_chan_spec const *chan,
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂint val,
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂint val2,
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂlong m)
> +{
> +ÂÂÂÂÂÂÂstruct ad7780_state *st = iio_priv(indio_dev);
> +ÂÂÂÂÂÂÂconst struct ad7780_chip_info *chip_info = st->chip_info;
> +ÂÂÂÂÂÂÂint vref, gain;
> +ÂÂÂÂÂÂÂunsigned int full_scale;
> +
> +ÂÂÂÂÂÂÂif (!chip_info->is_ad778x)
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂreturn 0;
> +
> +ÂÂÂÂÂÂÂswitch (m) {
> +ÂÂÂÂÂÂÂcase IIO_CHAN_INFO_SCALE:
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂif (val != 0)
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂreturn -EINVAL;
> +
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂvref = st->int_vref_mv * 1000000LL;

From the datasheet, the VREF isÂÂ5 V, therefore your vref variable will
overflow. You probably needÂunsigned long long.

> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂfull_scale = 1 << (chip_info->channel.scane_type.realbis
> - 1);
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂgain = DIV_ROUND_CLOSEST(vref, full_scale);
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂgain = DIV_ROUND_CLOSEST(gain, val2);
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂst->gain = gain;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂif (gain < AD7780_GAIN_MIDPOINT)
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂgain = 0;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂelse
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂgain = 1;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂgpiod_set_value(st->gain_gpio, gain);
> +ÂÂÂÂÂÂÂbreak;
> +ÂÂÂÂÂÂÂcase IIO_CHAN_INFO_SAMP_FREQ:
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂif (1000*val + val2/1000 < AD7780_FILTER_MIDPOINT)
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂval = 0;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂelse
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂval = 1;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂst->filter = ad778x_filter[val];
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂgpiod_set_value(st->filter_gpio, val);
> +ÂÂÂÂÂÂÂbreak;
> +ÂÂÂÂÂÂÂ}
> +
> +ÂÂÂÂÂÂÂreturn 0;
> +}
> +
> Âstatic int ad7780_postprocess_sample(struct ad_sigma_delta *sigma_delta,
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂunsigned int raw_sample)
> Â{
> @@ -126,10 +187,8 @@ static int ad7780_postprocess_sample(struct
> ad_sigma_delta *sigma_delta,
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂreturn -EIO;
> 
> ÂÂÂÂÂÂÂÂif (chip_info->is_ad778x) {
> -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂif (raw_sample & AD7780_GAIN)
> -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂst->gain = 1;
> -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂelse
> -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂst->gain = 128;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂst->gain = ad778x_gain[raw_sample & AD7780_GAIN];
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂst->filter = ad778x_filter[raw_sample & AD7780_FILTER];
> ÂÂÂÂÂÂÂÂ}
> 
> ÂÂÂÂÂÂÂÂreturn 0;
> @@ -141,18 +200,20 @@ static const struct ad_sigma_delta_info
> ad7780_sigma_delta_info = {
> ÂÂÂÂÂÂÂÂ.has_registers = false,
> Â};
> 
> -#define AD7780_CHANNEL(bits, wordsize) \
> +#define AD7170_CHANNEL(bits, wordsize) \
> ÂÂÂÂÂÂÂÂAD_SD_CHANNEL_NO_SAMP_FREQ(1, 0, 0, bits, 32, wordsize - bits)
> +#define AD7780_CHANNEL(bits, wordsize) \
> +ÂÂÂÂÂÂÂAD_SD_CHANNEL_GAIN_FILTER(1, 0, 0, bits, 32, wordsize - bits)
> 
> Âstatic const struct ad7780_chip_info ad7780_chip_info_tbl[] = {
> ÂÂÂÂÂÂÂÂ[ID_AD7170] = {
> -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ.channel = AD7780_CHANNEL(12, 24),
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ.channel = AD7170_CHANNEL(12, 24),
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ.pattern = AD7170_PATTERN,
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ.pattern_mask = AD7170_PATTERN_MASK,
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ.is_ad778x = false,
> ÂÂÂÂÂÂÂÂ},
> ÂÂÂÂÂÂÂÂ[ID_AD7171] = {
> -ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ.channel = AD7780_CHANNEL(16, 24),
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ.channel = AD7170_CHANNEL(16, 24),
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ.pattern = AD7170_PATTERN,
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ.pattern_mask = AD7170_PATTERN_MASK,
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ.is_ad778x = false,
> @@ -173,6 +234,7 @@ static const struct ad7780_chip_info
> ad7780_chip_info_tbl[] = {
> 
> Âstatic const struct iio_info ad7780_info = {
> ÂÂÂÂÂÂÂÂ.read_raw = ad7780_read_raw,
> +ÂÂÂÂÂÂÂ.write_raw = ad7780_write_raw,
> Â};
> 
> Âstatic int ad7780_probe(struct spi_device *spi)
> @@ -222,6 +284,29 @@ static int ad7780_probe(struct spi_device *spi)
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂgoto error_disable_reg;
> ÂÂÂÂÂÂÂÂ}
> 
> +ÂÂÂÂÂÂÂif (st->chip_info->is_ad778x) {
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂst->gain_gpio = devm_gpiod_get_optional(&spi->dev,
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ"gain",
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂGPIOD_OUT_HIGH);
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂif (IS_ERR(st->gain_gpio)) {
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂret = PTR_ERR(st->gain_gpio);
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂdev_err(&spi->dev, "Failed to request gain GPIO:
> %d\n",
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂret);
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂgoto error_disable_reg;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ}
> +
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂst->filter_gpio = devm_gpiod_get_optional(&spi->dev,
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ"filter",
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂGPIOD_OUT_HIGH)
> ;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂif (IS_ERR(st->filter_gpio)) {
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂret = PTR_ERR(st->filter_gpio);
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂdev_err(&spi->dev,
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ"Failed to request filter GPIO: %d\n",
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂret);
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂgoto error_disable_reg;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ}
> +ÂÂÂÂÂÂÂ}
> +
> ÂÂÂÂÂÂÂÂret = ad_sd_setup_buffer_and_trigger(indio_dev);
> ÂÂÂÂÂÂÂÂif (ret)
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂgoto error_disable_reg;
> diff --git a/include/linux/iio/adc/ad_sigma_delta.h
> b/include/linux/iio/adc/ad_sigma_delta.h
> index 7e84351fa2c0..c01da869de83 100644
> --- a/include/linux/iio/adc/ad_sigma_delta.h
> +++ b/include/linux/iio/adc/ad_sigma_delta.h
> @@ -176,6 +176,11 @@ int ad_sd_validate_trigger(struct iio_dev
> *indio_dev, struct iio_trigger *trig);
> ÂÂÂÂÂÂÂÂ__AD_SD_CHANNEL(_si, _channel, -1, _address, _bits, \
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ_storagebits, _shift, NULL, IIO_VOLTAGE, 0)
> 
> +#define AD_SD_CHANNEL_GAIN_FILTER(_si, _channel, _address, _bits, \
> +ÂÂÂÂÂÂÂ_storagebits, _shift) \
> +ÂÂÂÂÂÂÂ__AD_SD_CHANNEL(_si, _channel, -1, _address, _bits, \
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ_storagebits, _shift, NULL, IIO_VOLTAGE,
> BIT(IIO_CHAN_INFO_RAW))
> +

Do you need to define a new macro?

> Â#define AD_SD_TEMP_CHANNEL(_si, _address, _bits, _storagebits, _shift) \
> ÂÂÂÂÂÂÂÂ__AD_SD_CHANNEL(_si, 0, -1, _address, _bits, \
> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ_storagebits, _shift, NULL, IIO_TEMP, \
> --
> 2.20.1
>