[PATCH 2/4] iio: adc: ad7091r5: Add scale and external VREF support

[Beniamin Bia]

From: Paul Cercueil <paul.cercueil at analog.com>

The scale can now be obtained with the "in_voltage_scale" file.
By default, the scale returned corresponds to the internal VREF of 2.5V.

It is possible to use an external VREF (through the REFIN/REFOUT pin of
the chip), by passing a regulator to the driver. The scale will then be
calculated according to the voltage reported by the regulator.

Signed-off-by: Paul Cercueil <paul.cercueil at analog.com>
Co-developed-by: Beniamin Bia <beniamin.bia at analog.com>
Signed-off-by: Beniamin Bia <beniamin.bia at analog.com>
---
 drivers/iio/adc/ad7091r-base.c | 42 +++++++++++++++++++++++++++++++++-
 drivers/iio/adc/ad7091r-base.h |  1 +
 drivers/iio/adc/ad7091r5.c     |  5 ++++
 3 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ad7091r-base.c b/drivers/iio/adc/ad7091r-base.c
index 140413329754..d416f0912531 100644
--- a/drivers/iio/adc/ad7091r-base.c
+++ b/drivers/iio/adc/ad7091r-base.c
@@ -14,6 +14,7 @@
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
 
 #define AD7091R_REG_RESULT  0
 #define AD7091R_REG_CHANNEL 1
@@ -42,6 +43,7 @@ enum ad7091r_mode {
 struct ad7091r_state {
 	struct device *dev;
 	struct regmap *map;
+	struct regulator *reg;
 	const struct ad7091r_chip_info *chip_info;
 	enum ad7091r_mode mode;
 };
@@ -139,6 +141,21 @@ static int ad7091r_read_raw(struct iio_dev *iio_dev,
 		ret = IIO_VAL_INT;
 		break;
 
+	case IIO_CHAN_INFO_SCALE:
+		if (st->reg) {
+			ret = regulator_get_voltage(st->reg);
+			if (ret < 0)
+				goto unlock;
+
+			*val = ret / 1000;
+		} else {
+			*val = st->chip_info->vref_mV;
+		}
+
+		*val2 = chan->scan_type.realbits;
+		ret = IIO_VAL_FRACTIONAL_LOG2;
+		break;
+
 	default:
 		ret = -EINVAL;
 		break;
@@ -215,6 +232,18 @@ int ad7091r_probe(struct device *dev, const char *name,
 			return ret;
 	}
 
+	st->reg = devm_regulator_get_optional(dev, "vref");
+	if (IS_ERR(st->reg)) {
+		if (PTR_ERR(st->reg) == EPROBE_DEFER)
+			return -EPROBE_DEFER;
+
+		st->reg = NULL;
+	} else {
+		ret = regulator_enable(st->reg);
+		if (ret)
+			return ret;
+	}
+
 	/* Use command mode by default */
 	ret = ad7091r_set_mode(st, AD7091R_MODE_COMMAND);
 	if (ret < 0)
@@ -222,18 +251,29 @@ int ad7091r_probe(struct device *dev, const char *name,
 
 	ret = iio_device_register(iio_dev);
 	if (ret)
-		return ret;
+		goto err_disable_reg;
 
 	dev_dbg(dev, "Probed\n");
 	return 0;
+
+err_disable_reg:
+	if (st->reg)
+		regulator_disable(st->reg);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(ad7091r_probe);
 
 int ad7091r_remove(struct device *dev)
 {
 	struct iio_dev *iio_dev = dev_get_drvdata(dev);
+	struct ad7091r_state *st = iio_priv(iio_dev);
 
 	iio_device_unregister(iio_dev);
+
+	if (st->reg)
+		regulator_disable(st->reg);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(ad7091r_remove);
diff --git a/drivers/iio/adc/ad7091r-base.h b/drivers/iio/adc/ad7091r-base.h
index 7a29f86ea82b..cec4fb75fecc 100644
--- a/drivers/iio/adc/ad7091r-base.h
+++ b/drivers/iio/adc/ad7091r-base.h
@@ -18,6 +18,7 @@ struct ad7091r_state;
 struct ad7091r_chip_info {
 	unsigned int num_channels;
 	const struct iio_chan_spec *channels;
+	unsigned int vref_mV;
 };
 
 extern const struct regmap_config ad7091r_regmap_config;
diff --git a/drivers/iio/adc/ad7091r5.c b/drivers/iio/adc/ad7091r5.c
index 1ba838c58c31..65bcd8bb692a 100644
--- a/drivers/iio/adc/ad7091r5.c
+++ b/drivers/iio/adc/ad7091r5.c
@@ -35,10 +35,13 @@ static const struct iio_event_spec ad7091r5_events[] = {
 #define AD7091R_CHANNEL(idx, bits, ev, num_ev) { \
 	.type = IIO_VOLTAGE, \
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
 	.indexed = 1, \
 	.channel = idx, \
 	.event_spec = ev, \
 	.num_event_specs = num_ev, \
+	.scan_type.storagebits = 16, \
+	.scan_type.realbits = bits, \
 }
 static const struct iio_chan_spec ad7091r5_channels_irq[] = {
 	AD7091R_CHANNEL(0, 12, ad7091r5_events, ARRAY_SIZE(ad7091r5_events)),
@@ -58,11 +61,13 @@ static const struct iio_chan_spec ad7091r5_channels_noirq[] = {
 static const struct ad7091r_chip_info ad7091r5_chip_info_irq = {
 	.channels = ad7091r5_channels_irq,
 	.num_channels = ARRAY_SIZE(ad7091r5_channels_irq),
+	.vref_mV = 2500,
 };
 
 static const struct ad7091r_chip_info ad7091r5_chip_info_noirq = {
 	.channels = ad7091r5_channels_noirq,
 	.num_channels = ARRAY_SIZE(ad7091r5_channels_noirq),
+	.vref_mV = 2500,
 };
 
 static int ad7091r5_i2c_probe(struct i2c_client *i2c,
-- 
2.17.1