[PATCH v2 1/2] staging: iio: ad7780: add gain & filter gpio support
Popa, Stefan Serban
StefanSerban.Popa at analog.com
Wed Jan 30 12:23:05 UTC 2019
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 at gmail.com>
> Signed-off-by: Giuliano Belinassi <giuliano.belinassi at usp.br>
> Co-developed-by: Giuliano Belinassi <giuliano.belinassi at usp.br>
> ---
> Changes in v2:
> - Filter reading changed to mHz
> - Storing filter, gain and voltage to chip_info
Hi,
Comments inline.
Regards,
Stefan
>
> drivers/staging/iio/adc/ad7780.c | 103 ++++++++++++++++++++++---
> include/linux/iio/adc/ad_sigma_delta.h | 5 ++
> 2 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 @@
> #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
> +
> +#define AD7780_GAIN_MIDPOINT 64
> +#define AD7780_FILTER_MIDPOINT 13350
> +
> +static const unsigned int ad778x_gain[2] = { 1, 128 };
> +static const unsigned int ad778x_filter[2] = { 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.
> +
> 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 filter;
Also, this could be renamed as 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->filter;
> + 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;
> + int vref, gain;
> + unsigned int full_scale;
> +
> + 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;
From the datasheet, the VREF is ±5 V, therefore your vref variable will
overflow. You probably need unsigned long long.
> + full_scale = 1 << (chip_info->channel.scane_type.realbis
> - 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->filter = ad778x_filter[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->filter = ad778x_filter[raw_sample & AD7780_FILTER];
> }
>
> return 0;
> @@ -141,18 +200,20 @@ static const struct ad_sigma_delta_info
> ad7780_sigma_delta_info = {
> .has_registers = false,
> };
>
> -#define AD7780_CHANNEL(bits, wordsize) \
> +#define AD7170_CHANNEL(bits, wordsize) \
> AD_SD_CHANNEL_NO_SAMP_FREQ(1, 0, 0, bits, 32, wordsize - bits)
> +#define AD7780_CHANNEL(bits, wordsize) \
> + AD_SD_CHANNEL_GAIN_FILTER(1, 0, 0, bits, 32, wordsize - bits)
>
> static const struct ad7780_chip_info ad7780_chip_info_tbl[] = {
> [ID_AD7170] = {
> - .channel = AD7780_CHANNEL(12, 24),
> + .channel = AD7170_CHANNEL(12, 24),
> .pattern = AD7170_PATTERN,
> .pattern_mask = AD7170_PATTERN_MASK,
> .is_ad778x = false,
> },
> [ID_AD7171] = {
> - .channel = AD7780_CHANNEL(16, 24),
> + .channel = AD7170_CHANNEL(16, 24),
> .pattern = AD7170_PATTERN,
> .pattern_mask = AD7170_PATTERN_MASK,
> .is_ad778x = false,
> @@ -173,6 +234,7 @@ 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 +284,29 @@ 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",
> + 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;
> 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);
> __AD_SD_CHANNEL(_si, _channel, -1, _address, _bits, \
> _storagebits, _shift, NULL, IIO_VOLTAGE, 0)
>
> +#define AD_SD_CHANNEL_GAIN_FILTER(_si, _channel, _address, _bits, \
> + _storagebits, _shift) \
> + __AD_SD_CHANNEL(_si, _channel, -1, _address, _bits, \
> + _storagebits, _shift, NULL, IIO_VOLTAGE,
> BIT(IIO_CHAN_INFO_RAW))
> +
Do you need to define a new macro?
> #define AD_SD_TEMP_CHANNEL(_si, _address, _bits, _storagebits, _shift) \
> __AD_SD_CHANNEL(_si, 0, -1, _address, _bits, \
> _storagebits, _shift, NULL, IIO_TEMP, \
> --
> 2.20.1
>
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