iio: adc: ti-tsc2046: use devm_regulator_get_enable_read_voltage()

Use devm_regulator_get_enable_read_voltage() to replace
tsc2046_adc_configure_regulator() which does the same thing.
Signed-off-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://patch.msgid.link/20240725-iio-regulator-refactor-round-4-v1-1-55e9dc1de325@baylibre.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ti-tsc2046.c

@@ -142,7 +142,7 @@ enum tsc2046_state {
 struct tsc2046_adc_priv {
 	struct spi_device *spi;
 	const struct tsc2046_adc_dcfg *dcfg;
-	struct regulator *vref_reg;
+	bool internal_vref;
 
 	struct iio_trigger *trig;
 	struct hrtimer trig_timer;
@@ -258,7 +258,7 @@ static u8 tsc2046_adc_get_cmd(struct tsc2046_adc_priv *priv, int ch_idx,
 	case TI_TSC2046_ADDR_VBAT:
 	case TI_TSC2046_ADDR_TEMP0:
 		pd |= TI_TSC2046_SER;
-		if (!priv->vref_reg)
+		if (priv->internal_vref)
 			pd |= TI_TSC2046_PD1_VREF_ON;
 	}
 
@@ -741,49 +741,6 @@ static void tsc2046_adc_parse_fwnode(struct tsc2046_adc_priv *priv)
 	}
 }
 
-static void tsc2046_adc_regulator_disable(void *data)
-{
-	struct tsc2046_adc_priv *priv = data;
-
-	regulator_disable(priv->vref_reg);
-}
-
-static int tsc2046_adc_configure_regulator(struct tsc2046_adc_priv *priv)
-{
-	struct device *dev = &priv->spi->dev;
-	int ret;
-
-	priv->vref_reg = devm_regulator_get_optional(dev, "vref");
-	if (IS_ERR(priv->vref_reg)) {
-		/* If regulator exists but can't be get, return an error */
-		if (PTR_ERR(priv->vref_reg) != -ENODEV)
-			return PTR_ERR(priv->vref_reg);
-		priv->vref_reg = NULL;
-	}
-	if (!priv->vref_reg) {
-		/* Use internal reference */
-		priv->vref_mv = TI_TSC2046_INT_VREF;
-		return 0;
-	}
-
-	ret = regulator_enable(priv->vref_reg);
-	if (ret)
-		return ret;
-
-	ret = devm_add_action_or_reset(dev, tsc2046_adc_regulator_disable,
-				       priv);
-	if (ret)
-		return ret;
-
-	ret = regulator_get_voltage(priv->vref_reg);
-	if (ret < 0)
-		return ret;
-
-	priv->vref_mv = ret / MILLI;
-
-	return 0;
-}
-
 static int tsc2046_adc_probe(struct spi_device *spi)
 {
 	const struct tsc2046_adc_dcfg *dcfg;
@@ -825,10 +782,13 @@ static int tsc2046_adc_probe(struct spi_device *spi)
 	indio_dev->num_channels = dcfg->num_channels;
 	indio_dev->info = &tsc2046_adc_info;
 
-	ret = tsc2046_adc_configure_regulator(priv);
-	if (ret)
+	ret = devm_regulator_get_enable_read_voltage(dev, "vref");
+	if (ret < 0 && ret != -ENODEV)
 		return ret;
 
+	priv->internal_vref = ret == -ENODEV;
+	priv->vref_mv = priv->internal_vref ? TI_TSC2046_INT_VREF : ret / MILLI;
+
 	tsc2046_adc_parse_fwnode(priv);
 
 	ret = tsc2046_adc_setup_spi_msg(priv);