staging:iio:ade7854: Rework SPI read function

Rework read SPI function to reduce the code duplication and centralizes
all the task in a single function.

Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/staging/iio/meter/ade7854-spi.c

@@ -67,9 +67,10 @@ unlock:
 	return ret;
 }
 
-static int ade7854_spi_read_reg_8(struct device *dev,
-				  u16 reg_address,
-				  u8 *val)
+static int ade7854_spi_read_reg(struct device *dev,
+				u16 reg_address,
+				u32 *val,
+				int bits)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct ade7854_state *st = iio_priv(indio_dev);
@@ -82,7 +83,7 @@ static int ade7854_spi_read_reg_8(struct device *dev,
 		}, {
 			.rx_buf = st->rx,
 			.bits_per_word = 8,
-			.len = 1,
+			.len = bits,
 		}
 	};
 
@@ -94,128 +95,57 @@ static int ade7854_spi_read_reg_8(struct device *dev,
 
 	ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
 	if (ret) {
-		dev_err(&st->spi->dev, "problem when reading 8 bit register 0x%02X",
+		dev_err(&st->spi->dev, "problem when reading register 0x%02X",
 			reg_address);
-		goto error_ret;
+		goto unlock;
+	}
+
+	switch (bits) {
+	case 8:
+		*val = st->rx[0];
+		break;
+	case 16:
+		*val = be16_to_cpup((const __be16 *)st->rx);
+		break;
+	case 24:
+		*val = (st->rx[0] << 16) | (st->rx[1] << 8) | st->rx[2];
+		break;
+	case 32:
+		*val = be32_to_cpup((const __be32 *)st->rx);
+		break;
 	}
-	*val = st->rx[0];
 
-error_ret:
+unlock:
 	mutex_unlock(&st->buf_lock);
 	return ret;
 }
 
+static int ade7854_spi_read_reg_8(struct device *dev,
+				  u16 reg_address,
+				  u8 *val)
+{
+	return ade7854_spi_read_reg(dev, reg_address, (u32 *)val, 8);
+}
+
 static int ade7854_spi_read_reg_16(struct device *dev,
 				   u16 reg_address,
 				   u16 *val)
 {
-	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
-	struct ade7854_state *st = iio_priv(indio_dev);
-	int ret;
-	struct spi_transfer xfers[] = {
-		{
-			.tx_buf = st->tx,
-			.bits_per_word = 8,
-			.len = 3,
-		}, {
-			.rx_buf = st->rx,
-			.bits_per_word = 8,
-			.len = 2,
-		}
-	};
-
-	mutex_lock(&st->buf_lock);
-	st->tx[0] = ADE7854_READ_REG;
-	st->tx[1] = (reg_address >> 8) & 0xFF;
-	st->tx[2] = reg_address & 0xFF;
-
-	ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
-	if (ret) {
-		dev_err(&st->spi->dev, "problem when reading 16 bit register 0x%02X",
-			reg_address);
-		goto error_ret;
-	}
-	*val = be16_to_cpup((const __be16 *)st->rx);
-
-error_ret:
-	mutex_unlock(&st->buf_lock);
-	return ret;
+	return ade7854_spi_read_reg(dev, reg_address, (u32 *)val, 16);
 }
 
 static int ade7854_spi_read_reg_24(struct device *dev,
 				   u16 reg_address,
 				   u32 *val)
 {
-	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
-	struct ade7854_state *st = iio_priv(indio_dev);
-	int ret;
-	struct spi_transfer xfers[] = {
-		{
-			.tx_buf = st->tx,
-			.bits_per_word = 8,
-			.len = 3,
-		}, {
-			.rx_buf = st->rx,
-			.bits_per_word = 8,
-			.len = 3,
-		}
-	};
-
-	mutex_lock(&st->buf_lock);
-
-	st->tx[0] = ADE7854_READ_REG;
-	st->tx[1] = (reg_address >> 8) & 0xFF;
-	st->tx[2] = reg_address & 0xFF;
-
-	ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
-	if (ret) {
-		dev_err(&st->spi->dev, "problem when reading 24 bit register 0x%02X",
-			reg_address);
-		goto error_ret;
-	}
-	*val = (st->rx[0] << 16) | (st->rx[1] << 8) | st->rx[2];
-
-error_ret:
-	mutex_unlock(&st->buf_lock);
-	return ret;
+	return ade7854_spi_read_reg(dev, reg_address, (u32 *)val, 24);
 }
 
 static int ade7854_spi_read_reg_32(struct device *dev,
 				   u16 reg_address,
 				   u32 *val)
 {
-	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
-	struct ade7854_state *st = iio_priv(indio_dev);
-	int ret;
-	struct spi_transfer xfers[] = {
-		{
-			.tx_buf = st->tx,
-			.bits_per_word = 8,
-			.len = 3,
-		}, {
-			.rx_buf = st->rx,
-			.bits_per_word = 8,
-			.len = 4,
-		}
-	};
-
-	mutex_lock(&st->buf_lock);
-
-	st->tx[0] = ADE7854_READ_REG;
-	st->tx[1] = (reg_address >> 8) & 0xFF;
-	st->tx[2] = reg_address & 0xFF;
-
-	ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
-	if (ret) {
-		dev_err(&st->spi->dev, "problem when reading 32 bit register 0x%02X",
-			reg_address);
-		goto error_ret;
-	}
-	*val = be32_to_cpup((const __be32 *)st->rx);
-
-error_ret:
-	mutex_unlock(&st->buf_lock);
-	return ret;
+	return ade7854_spi_read_reg(dev, reg_address, (u32 *)val, 32);
 }
 
 static int ade7854_spi_probe(struct spi_device *spi)