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Date: Sat, 9 Feb 2019 16:25:06 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Renato Lui Geh <renatogeh@...il.com>
Cc: lars@...afoo.de, Michael.Hennerich@...log.com, knaack.h@....de,
pmeerw@...erw.net, gregkh@...uxfoundation.org,
stefan.popa@...log.com, alexandru.Ardelean@...log.com,
giuliano.belinassi@....br, linux-iio@...r.kernel.org,
devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
kernel-usp@...glegroups.com
Subject: Re: [PATCH v3 1/4] staging: iio: ad7780: add gain & filter gpio
support
On Tue, 5 Feb 2019 15:13:00 -0200
Renato Lui Geh <renatogeh@...il.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@...il.com>
> Signed-off-by: Giuliano Belinassi <giuliano.belinassi@....br>
> Co-developed-by: Giuliano Belinassi <giuliano.belinassi@....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?
> +
> +#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.
> + 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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