From: Sergiu Cuciurean <sergiu.cuciurean@analog.com>

This commit adds the ad7768_spi_reg_write_masked() which is a helper
function for writing specific bits inside a register, without interfering
with the other bit values.

Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
---
 drivers/iio/adc/ad7768-1.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index 574d735f2c3a..675af9ea856d 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c

@@ -242,6 +242,21 @@ static int ad7768_spi_reg_write(struct ad7768_state *st,
 	return spi_write(st->spi, st->data.d8, 2);
 }
 
+static int ad7768_spi_reg_write_masked(struct ad7768_state *st,
+				       unsigned int addr,
+				       unsigned int mask,
+				       unsigned int val)
+{
+	unsigned int reg_val;
+	int ret;
+
+	ret = ad7768_spi_reg_read(st, addr, &reg_val, 1);
+	if (ret < 0)
+		return ret;
+
+	return ad7768_spi_reg_write(st, addr, (reg_val & ~mask) | val);
+}
+
 static int ad7768_set_mode(struct ad7768_state *st,
 			   enum ad7768_conv_mode mode)
 {