iio: adc: ad7192: Correct reference voltage

From: Alisa-Dariana Roman <[email protected]>

The avdd and the reference voltage are two different sources but the reference voltage was assigned according to the avdd supply.

Add vref regulator structure and set the reference voltage according to the vref supply from the devicetree.

In case vref supply is missing, reference voltage is set according to the avdd supply for compatibility with old devicetrees.

Fixes b581f748cce0 ("staging: iio: adc: ad7192: move out of staging")

Signed-off-by Alisa-Dariana Roman <[email protected]>

Cc [email protected]

---
v1 -> v2

	- use dev_err_probe()
	Link: https://lore.kernel.org/lkml/[email protected]/

 drivers/iio/adc/ad7192.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

drivers/iio/adc/ad7192.c +25 -4

index 69d1103b9508..b64fd365f83f 100644
@@ -177,6 +177,7 @@ struct ad7192_chip_info {
 struct ad7192_state {
 	const struct ad7192_chip_info	*chip_info;
 	struct regulator		*avdd;
+	struct regulator		*vref;
 	struct clk			*mclk;
 	u16				int_vref_mv;
 	u32				fclk;

@@ -1008,10 +1009,30 @@ static int ad7192_probe(struct spi_device *spi)
 	if (ret)
 		return dev_err_probe(&spi->dev, ret, "Failed to enable specified DVdd supply\n");
 
-	ret = regulator_get_voltage(st->avdd);
-	if (ret < 0) {
-		dev_err(&spi->dev, "Device tree error, reference voltage undefined\n");
-		return ret;
+	st->vref = devm_regulator_get_optional(&spi->dev, "vref");
+	if (IS_ERR(st->vref)) {
+		if (PTR_ERR(st->vref) != -ENODEV)
+			return PTR_ERR(st->vref);
+
+		ret = regulator_get_voltage(st->avdd);
+		if (ret < 0)
+			return dev_err_probe(&spi->dev, ret,
+					     "Device tree error, AVdd voltage undefined\n");
+	} else {
+		ret = regulator_enable(st->vref);
+		if (ret) {
+			dev_err(&spi->dev, "Failed to enable specified Vref supply\n");
+			return ret;
+		}
+
+		ret = devm_add_action_or_reset(&spi->dev, ad7192_reg_disable, st->vref);
+		if (ret)
+			return ret;
+
+		ret = regulator_get_voltage(st->vref);
+		if (ret < 0)
+			return dev_err_probe(&spi->dev, ret,
+					     "Device tree error, Vref voltage undefined\n");
 	}
 	st->int_vref_mv = ret / 1000;