[U-Boot] [PATCH 2/6] dm: adc: uclass: get reference regulator once

[Fabrice Gasnier]

device_get_supply_regulator() only needs to be called once.
But each time there's call to adc_vxx_value() for instance, it calls
adc_vxx_platdata_update() -> device_get_supply_regulator().

This also allows vdd_supply/vss_supply to be provided directly from
uc_pdata, e.g dt-binding variant like stm32-adc provide its own
'vref-supply'.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier at st.com>
---

 drivers/adc/adc-uclass.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/adc/adc-uclass.c b/drivers/adc/adc-uclass.c
index 17c1a4e..70f4cde 100644
--- a/drivers/adc/adc-uclass.c
+++ b/drivers/adc/adc-uclass.c
@@ -264,10 +264,13 @@ static int adc_vdd_platdata_update(struct udevice *dev)
 	 * will bind before its supply regulator device, then the below 'get'
 	 * will return an error.
 	 */
-	ret = device_get_supply_regulator(dev, "vdd-supply",
-					  &uc_pdata->vdd_supply);
-	if (ret)
-		return ret;
+	if (!uc_pdata->vdd_supply) {
+		/* Only get vdd_supply once */
+		ret = device_get_supply_regulator(dev, "vdd-supply",
+						  &uc_pdata->vdd_supply);
+		if (ret)
+			return ret;
+	}
 
 	ret = regulator_get_value(uc_pdata->vdd_supply);
 	if (ret < 0)
@@ -283,10 +286,12 @@ static int adc_vss_platdata_update(struct udevice *dev)
 	struct adc_uclass_platdata *uc_pdata = dev_get_uclass_platdata(dev);
 	int ret;
 
-	ret = device_get_supply_regulator(dev, "vss-supply",
-					  &uc_pdata->vss_supply);
-	if (ret)
-		return ret;
+	if (!uc_pdata->vss_supply) {
+		ret = device_get_supply_regulator(dev, "vss-supply",
+						  &uc_pdata->vss_supply);
+		if (ret)
+			return ret;
+	}
 
 	ret = regulator_get_value(uc_pdata->vss_supply);
 	if (ret < 0)
-- 
1.9.1