[PATCH 4.4 087/133] iio: dac: ad5624r: Fix incorrect handling of an optional regulator.

[Greg Kroah-Hartman]

From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>

[ Upstream commit 97683c851f9cdbd3ea55697cbe2dcb6af4287bbd ]

The naming of the regulator is problematic.  VCC is usually a supply
voltage whereas these devices have a separate VREF pin.

Secondly, the regulator core might have provided a stub regulator if
a real regulator wasn't provided. That would in turn have failed to
provide a voltage when queried. So reality was that there was no way
to use the internal reference.

In order to avoid breaking any dts out in the wild, make sure to fallback
to the original vcc naming if vref is not available.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Acked-by: Nuno Sá <nuno.sa@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20210627163244.1090296-9-jic23@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/iio/dac/ad5624r_spi.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/dac/ad5624r_spi.c b/drivers/iio/dac/ad5624r_spi.c
index 5489ec43b95d..e5cefdb674f8 100644
--- a/drivers/iio/dac/ad5624r_spi.c
+++ b/drivers/iio/dac/ad5624r_spi.c
@@ -231,7 +231,7 @@ static int ad5624r_probe(struct spi_device *spi)
 	if (!indio_dev)
 		return -ENOMEM;
 	st = iio_priv(indio_dev);
-	st->reg = devm_regulator_get(&spi->dev, "vcc");
+	st->reg = devm_regulator_get_optional(&spi->dev, "vref");
 	if (!IS_ERR(st->reg)) {
 		ret = regulator_enable(st->reg);
 		if (ret)
@@ -242,6 +242,22 @@ static int ad5624r_probe(struct spi_device *spi)
 			goto error_disable_reg;
 
 		voltage_uv = ret;
+	} else {
+		if (PTR_ERR(st->reg) != -ENODEV)
+			return PTR_ERR(st->reg);
+		/* Backwards compatibility. This naming is not correct */
+		st->reg = devm_regulator_get_optional(&spi->dev, "vcc");
+		if (!IS_ERR(st->reg)) {
+			ret = regulator_enable(st->reg);
+			if (ret)
+				return ret;
+
+			ret = regulator_get_voltage(st->reg);
+			if (ret < 0)
+				goto error_disable_reg;
+
+			voltage_uv = ret;
+		}
 	}
 
 	spi_set_drvdata(spi, indio_dev);
-- 
2.30.2