[PATCH 1/7] iio: adc: max1027: Add debugfs register read support

[Miquel Raynal <miquel.raynal@bootlin.com>]

Until now, only write operations were supported. Force two bytes read
operation when reading from this register (might be wrong when reading
the temperature, but will work with any other value).

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/iio/adc/max1027.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
index 214883458582..6cdfe9ef73fc 100644
--- a/drivers/iio/adc/max1027.c
+++ b/drivers/iio/adc/max1027.c
@@ -309,8 +309,11 @@ static int max1027_debugfs_reg_access(struct iio_dev *indio_dev,
 	struct max1027_state *st = iio_priv(indio_dev);
 	u8 *val = (u8 *)st->buffer;
 
-	if (readval != NULL)
-		return -EINVAL;
+	if (readval) {
+		int ret = spi_read(st->spi, val, 2);
+		*readval = be16_to_cpu(st->buffer[0]);
+		return ret;
+	}
 
 	*val = (u8)writeval;
 	return spi_write(st->spi, val, 1);
-- 
2.20.1