[PATCH 1/2] staging: iio: ad7780: Add gain & filter gpio support

Giuliano Belinassi
2018-11-28T18:16:08Z

Previously, the AD7780 driver only supported gpio for the 'powerdown'
pin. This commit adds suppport for the 'gain' and 'filter' pin.

Signed-off-by: Giuliano Belinassi <giuliano.belinassi@usp.br>
---
Changes in v2:
- Now this patch is part of the patchset that aims to remove ad7780
out of staging. https://marc.info/?l=linux-iio&m=154282349808890&w=2
- Also, now it reads voltage and filter values from the userspace
instead of gpio pin states.

drivers/staging/iio/adc/ad7780.c | 78 ++++++++++++++++++++++++--
include/linux/iio/adc/ad_sigma_delta.h | 5 ++
2 files changed, 79 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/iio/adc/ad7780.c b/drivers/staging/iio/adc/ad7780.c
index c4a85789c2db..05979a79fda3 100644
--- a/drivers/staging/iio/adc/ad7780.c
+++ b/drivers/staging/iio/adc/ad7780.c
@@ -39,6 +39,12 @@
#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
+
struct ad7780_chip_info {
struct iio_chan_spec channel;
unsigned int pattern_mask;
@@ -50,6 +56,8 @@ struct ad7780_state {
const struct ad7780_chip_info *chip_info;
struct regulator *reg;
struct gpio_desc *powerdown_gpio;
+ struct gpio_desc *gain_gpio;
+ struct gpio_desc *filter_gpio;
unsigned int gain;

struct ad_sigma_delta sd;
@@ -115,18 +123,65 @@ 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;
+ int uvref, gain;
+ unsigned int full_scale;
+
+ if (!chip_info->is_ad778x)
+ return 0;
+
+ switch (m) {
+ case IIO_CHAN_INFO_SCALE:
+ if (val != 0)
+ return -EINVAL;
+
+ uvref = regulator_get_voltage(st->reg);
+
+ if (uvref < 0)
+ return uvref;
+
+ full_scale = 1 << (chip_info->channel.scan_type.realbits - 1);
+ gain = DIV_ROUND_CLOSEST(uvref, full_scale);
+ gain = DIV_ROUND_CLOSEST(gain, val2);
+
+ gpiod_set_value(st->gain_gpio, gain < AD7780_GAIN_MIDPOINT ? 0 : 1);
+ break;
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ if (val2 != 0)
+ return -EINVAL;
+
+ gpiod_set_value(st->filter_gpio, val < AD7780_FILTER_MIDPOINT ? 0 : 1);
+ break;
+ }
+
+ return 0;
+}
+
static int ad7780_postprocess_sample(struct ad_sigma_delta *sigma_delta,
unsigned int raw_sample)
{
struct ad7780_state *st = ad_sigma_delta_to_ad7780(sigma_delta);
const struct ad7780_chip_info *chip_info = st->chip_info;
+ int val;

if ((raw_sample & AD7780_ERR) ||
((raw_sample & chip_info->pattern_mask) != chip_info->pattern))
return -EIO;

if (chip_info->is_ad778x) {
- if (raw_sample & AD7780_GAIN)
+ val = raw_sample & AD7780_GAIN;
+
+ if (val != gpiod_get_value(st->gain_gpio))
+ return -EIO;
+
+ if (val)
st->gain = 1;
else
st->gain = 128;
@@ -141,18 +196,20 @@ 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 +230,7 @@ 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 +280,18 @@ 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;
+ }
+ }
+
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 730ead1a46df..6cadab6fd5fd 100644
--- a/include/linux/iio/adc/ad_sigma_delta.h
+++ b/include/linux/iio/adc/ad_sigma_delta.h
@@ -173,6 +173,11 @@ 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))
+
#define AD_SD_TEMP_CHANNEL(_si, _address, _bits, _storagebits, _shift) \
__AD_SD_CHANNEL(_si, 0, -1, _address, _bits, \
_storagebits, _shift, NULL, IIO_TEMP, \
--
2.19.1