[PATCH v2 6/8] staging:iio:ade7854: Rework I2C read function

[Rodrigo Siqueira]

The read operation for the I2C function has many duplications that can
be generalized into a single function. This patch reworks the read
operation for I2C to centralizes all similar code in a single function.
Part of the rework includes a proper error handling and a fix on the
i2c_master_recv for 32 bits as pointed by John Syne patches.

It is possible to remove all the old interface to use the new one,
however, for keeping the things simple and working this patch maintain
legacy interface.

Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo at gmail.com>
Signed-off-by: John Syne <john3909 at gmail.com>
---
 drivers/staging/iio/meter/ade7854-i2c.c | 110 ++++++++++++--------------------
 1 file changed, 41 insertions(+), 69 deletions(-)

diff --git a/drivers/staging/iio/meter/ade7854-i2c.c b/drivers/staging/iio/meter/ade7854-i2c.c
index e95147a1bac1..20db8eedb84a 100644
--- a/drivers/staging/iio/meter/ade7854-i2c.c
+++ b/drivers/staging/iio/meter/ade7854-i2c.c
@@ -65,9 +65,10 @@ static int ade7854_i2c_write_reg(struct device *dev,
 	return ret < 0 ? ret : 0;
 }
 
-static int ade7854_i2c_read_reg_8(struct device *dev,
-				  u16 reg_address,
-				  u8 *val)
+static int ade7854_i2c_read_reg(struct device *dev,
+				u16 reg_address,
+				u32 *val,
+				int bytes)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
 	struct ade7854_state *st = iio_priv(indio_dev);
@@ -79,95 +80,66 @@ static int ade7854_i2c_read_reg_8(struct device *dev,
 
 	ret = i2c_master_send(st->i2c, st->tx, 2);
 	if (ret < 0)
-		goto out;
+		goto unlock;
 
-	ret = i2c_master_recv(st->i2c, st->rx, 1);
+	ret = i2c_master_recv(st->i2c, st->rx, bytes);
 	if (ret < 0)
-		goto out;
+		goto unlock;
+
+	switch (bytes) {
+	case DATA_SIZE_8_BITS:
+		*val = st->rx[0];
+		break;
+	case DATA_SIZE_16_BITS:
+		*val = (st->rx[0] << 8) | st->rx[1];
+		break;
+	case DATA_SIZE_24_BITS:
+		*val = (st->rx[0] << 16) | (st->rx[1] << 8) | st->rx[2];
+		break;
+	case DATA_SIZE_32_BITS:
+		*val = (st->rx[0] << 24) | (st->rx[1] << 16) |
+			(st->rx[2] << 8) | st->rx[3];
+		break;
+	default:
+		ret = -EINVAL;
+		goto unlock;
+	}
 
-	*val = st->rx[0];
-out:
+unlock:
 	mutex_unlock(&st->buf_lock);
 	return ret;
 }
 
+static int ade7854_i2c_read_reg_8(struct device *dev,
+				  u16 reg_address,
+				  u8 *val)
+{
+	return ade7854_i2c_read_reg(dev, reg_address, (u32 *)val,
+				    DATA_SIZE_8_BITS);
+}
+
 static int ade7854_i2c_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;
-
-	mutex_lock(&st->buf_lock);
-	st->tx[0] = (reg_address >> 8) & 0xFF;
-	st->tx[1] = reg_address & 0xFF;
-
-	ret = i2c_master_send(st->i2c, st->tx, 2);
-	if (ret < 0)
-		goto out;
-
-	ret = i2c_master_recv(st->i2c, st->rx, 2);
-	if (ret < 0)
-		goto out;
-
-	*val = (st->rx[0] << 8) | st->rx[1];
-out:
-	mutex_unlock(&st->buf_lock);
-	return ret;
+	return ade7854_i2c_read_reg(dev, reg_address, (u32 *)val,
+				    DATA_SIZE_16_BITS);
 }
 
 static int ade7854_i2c_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;
-
-	mutex_lock(&st->buf_lock);
-	st->tx[0] = (reg_address >> 8) & 0xFF;
-	st->tx[1] = reg_address & 0xFF;
-
-	ret = i2c_master_send(st->i2c, st->tx, 2);
-	if (ret < 0)
-		goto out;
-
-	ret = i2c_master_recv(st->i2c, st->rx, 3);
-	if (ret < 0)
-		goto out;
-
-	*val = (st->rx[0] << 16) | (st->rx[1] << 8) | st->rx[2];
-out:
-	mutex_unlock(&st->buf_lock);
-	return ret;
+	return ade7854_i2c_read_reg(dev, reg_address, (u32 *)val,
+				    DATA_SIZE_24_BITS);
 }
 
 static int ade7854_i2c_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;
-
-	mutex_lock(&st->buf_lock);
-	st->tx[0] = (reg_address >> 8) & 0xFF;
-	st->tx[1] = reg_address & 0xFF;
-
-	ret = i2c_master_send(st->i2c, st->tx, 2);
-	if (ret < 0)
-		goto out;
-
-	ret = i2c_master_recv(st->i2c, st->rx, 4);
-	if (ret < 0)
-		goto out;
-
-	*val = (st->rx[0] << 24) | (st->rx[1] << 16) |
-		(st->rx[2] << 8) | st->rx[3];
-out:
-	mutex_unlock(&st->buf_lock);
-	return ret;
+	return ade7854_i2c_read_reg(dev, reg_address, (u32 *)val,
+				    DATA_SIZE_32_BITS);
 }
 
 static int ade7854_i2c_probe(struct i2c_client *client,
-- 
2.16.2