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

Renato Lui Geh
2019-03-16T02:12:35Z

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>
---
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);
+ 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;
+
+
+ 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)
--
2.21.0