iio: adc: ad7192: use devm_regulator_get_enable_read_voltage

This makes use of the new devm_regulator_get_enable_read_voltage()
function to reduce boilerplate code.

Error messages have changed slightly since there are now fewer places
where we print an error. The rest of the logic of selecting which
supply to use as the reference voltage remains the same.

Also 1000 is replaced by MILLI in a few places for consistency.
Signed-off-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Alisa-Dariana Roman <alisa.roman@analog.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://patch.msgid.link/20240624124941.113010-2-alisa.roman@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad7192.c

@@ -200,8 +200,6 @@ 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				aincom_mv;
@@ -1189,18 +1187,12 @@ static const struct ad7192_chip_info ad7192_chip_info_tbl[] = {
 	},
 };
 
-static void ad7192_reg_disable(void *reg)
-{
-	regulator_disable(reg);
-}
-
 static int ad7192_probe(struct spi_device *spi)
 {
 	struct device *dev = &spi->dev;
 	struct ad7192_state *st;
 	struct iio_dev *indio_dev;
-	struct regulator *aincom;
-	int ret;
+	int ret, avdd_mv;
 
 	if (!spi->irq)
 		return dev_err_probe(dev, -ENODEV, "Failed to get IRQ\n");
@@ -1218,72 +1210,49 @@ static int ad7192_probe(struct spi_device *spi)
 	 * Newer firmware should provide a zero volt fixed supply if wired to
 	 * ground.
 	 */
-	aincom = devm_regulator_get_optional(dev, "aincom");
-	if (IS_ERR(aincom)) {
-		if (PTR_ERR(aincom) != -ENODEV)
-			return dev_err_probe(dev, PTR_ERR(aincom),
-					     "Failed to get AINCOM supply\n");
-
-		st->aincom_mv = 0;
-	} else {
-		ret = regulator_enable(aincom);
-		if (ret)
-			return dev_err_probe(dev, ret,
-					     "Failed to enable specified AINCOM supply\n");
-
-		ret = devm_add_action_or_reset(dev, ad7192_reg_disable, aincom);
-		if (ret)
-			return ret;
-
-		ret = regulator_get_voltage(aincom);
-		if (ret < 0)
-			return dev_err_probe(dev, ret,
-					     "Device tree error, AINCOM voltage undefined\n");
-		st->aincom_mv = ret / MILLI;
+	ret = devm_regulator_get_enable_read_voltage(dev, "aincom");
+	if (ret < 0 && ret != -ENODEV)
+		return dev_err_probe(dev, ret, "Failed to get AINCOM voltage\n");
+
+	st->aincom_mv = ret == -ENODEV ? 0 : ret / MILLI;
+
+	/* AVDD can optionally be used as reference voltage */
+	ret = devm_regulator_get_enable_read_voltage(dev, "avdd");
+	if (ret == -ENODEV || ret == -EINVAL) {
+		int ret2;
+
+		/*
+		 * We get -EINVAL if avdd is a supply with unknown voltage. We
+		 * still need to enable it since it is also a power supply.
+		 */
+		ret2 = devm_regulator_get_enable(dev, "avdd");
+		if (ret2)
+			return dev_err_probe(dev, ret2,
+					     "Failed to enable AVDD supply\n");
+	} else if (ret < 0) {
+		return dev_err_probe(dev, ret, "Failed to get AVDD voltage\n");
 	}
 
-	st->avdd = devm_regulator_get(dev, "avdd");
-	if (IS_ERR(st->avdd))
-		return PTR_ERR(st->avdd);
-
-	ret = regulator_enable(st->avdd);
-	if (ret)
-		return dev_err_probe(dev, ret,
-				     "Failed to enable specified AVdd supply\n");
-
-	ret = devm_add_action_or_reset(dev, ad7192_reg_disable, st->avdd);
-	if (ret)
-		return ret;
+	avdd_mv = ret == -ENODEV || ret == -EINVAL ? 0 : ret / MILLI;
 
 	ret = devm_regulator_get_enable(dev, "dvdd");
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to enable specified DVdd supply\n");
 
-	st->vref = devm_regulator_get_optional(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(dev, ret,
-					     "Device tree error, AVdd voltage undefined\n");
-	} else {
-		ret = regulator_enable(st->vref);
-		if (ret)
-			return dev_err_probe(dev, ret,
-					     "Failed to enable specified Vref supply\n");
-
-		ret = devm_add_action_or_reset(dev, ad7192_reg_disable, st->vref);
-		if (ret)
-			return ret;
-
-		ret = regulator_get_voltage(st->vref);
-		if (ret < 0)
-			return dev_err_probe(dev, ret,
-					     "Device tree error, Vref voltage undefined\n");
+	/*
+	 * This is either REFIN1 or REFIN2 depending on adi,refin2-pins-enable.
+	 * If this supply is not present, fall back to AVDD as reference.
+	 */
+	ret = devm_regulator_get_enable_read_voltage(dev, "vref");
+	if (ret == -ENODEV) {
+		if (avdd_mv == 0)
+			return dev_err_probe(dev, -ENODEV,
+					     "No reference voltage available\n");
+	} else if (ret < 0) {
+		return ret;
 	}
-	st->int_vref_mv = ret / 1000;
+
+	st->int_vref_mv = ret == -ENODEV ? avdd_mv : ret / MILLI;
 
 	st->chip_info = spi_get_device_match_data(spi);
 	indio_dev->name = st->chip_info->name;