[PATCH v1 06/15] iio: adc: ad7768-1: Update reg_read function

[Jonathan Santos <Jonathan.Santos@analog.com>]

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

This patch adds an additional parameter to the register read function.
By passing the data pointer to the function, the returned value will used
only for status check.
With this change, the status check won't be confused with a register value
check:

ret = ad7768_spi_reg_read()
if (ret){}

Also this change removes the probability to interpret a negative value as
a return code (the ADC is a differential one)."

Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
---
 drivers/iio/adc/ad7768-1.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index 463a28d09c2e..881446462ff5 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -177,7 +177,7 @@ struct ad7768_state {
 };
 
 static int ad7768_spi_reg_read(struct ad7768_state *st, unsigned int addr,
-			       unsigned int len)
+			       unsigned int *data, unsigned int len)
 {
 	unsigned int shift;
 	int ret;
@@ -190,7 +190,9 @@ static int ad7768_spi_reg_read(struct ad7768_state *st, unsigned int addr,
 	if (ret < 0)
 		return ret;
 
-	return (be32_to_cpu(st->data.d32) >> shift);
+	*data = (be32_to_cpu(st->data.d32) >> shift);
+
+	return ret;
 }
 
 static int ad7768_spi_reg_write(struct ad7768_state *st,
@@ -206,11 +208,11 @@ static int ad7768_spi_reg_write(struct ad7768_state *st,
 static int ad7768_set_mode(struct ad7768_state *st,
 			   enum ad7768_conv_mode mode)
 {
-	int regval;
+	int ret, regval;
 
-	regval = ad7768_spi_reg_read(st, AD7768_REG_CONVERSION, 1);
-	if (regval < 0)
-		return regval;
+	ret = ad7768_spi_reg_read(st, AD7768_REG_CONVERSION, &regval, 1);
+	if (ret < 0)
+		return ret;
 
 	regval &= ~AD7768_CONV_MODE_MSK;
 	regval |= AD7768_CONV_MODE(mode);
@@ -234,9 +236,9 @@ static int ad7768_scan_direct(struct iio_dev *indio_dev)
 	if (!ret)
 		return -ETIMEDOUT;
 
-	readval = ad7768_spi_reg_read(st, AD7768_REG_ADC_DATA, 3);
-	if (readval < 0)
-		return readval;
+	ret = ad7768_spi_reg_read(st, AD7768_REG_ADC_DATA, &readval, 3);
+	if (ret < 0)
+		return ret;
 	/*
 	 * Any SPI configuration of the AD7768-1 can only be
 	 * performed in continuous conversion mode.
@@ -258,11 +260,9 @@ static int ad7768_reg_access(struct iio_dev *indio_dev,
 
 	mutex_lock(&st->lock);
 	if (readval) {
-		ret = ad7768_spi_reg_read(st, reg, 1);
+		ret = ad7768_spi_reg_read(st, reg, readval, 1);
 		if (ret < 0)
 			goto err_unlock;
-		*readval = ret;
-		ret = 0;
 	} else {
 		ret = ad7768_spi_reg_write(st, reg, writeval);
 	}
@@ -515,12 +515,13 @@ static int ad7768_buffer_postenable(struct iio_dev *indio_dev)
 static int ad7768_buffer_predisable(struct iio_dev *indio_dev)
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
+	unsigned int regval;
 
 	/*
 	 * To exit continuous read mode, perform a single read of the ADC_DATA
 	 * reg (0x2C), which allows further configuration of the device.
 	 */
-	return ad7768_spi_reg_read(st, AD7768_REG_ADC_DATA, 3);
+	return ad7768_spi_reg_read(st, AD7768_REG_ADC_DATA, &regval, 3);
 }
 
 static const struct iio_buffer_setup_ops ad7768_buffer_ops = {
-- 
2.34.1