staging: iio: tsl2x7x: add common function for writing to the control register

There were four places where the same chunk of code was used to write
to the control register. This patch creates a common function
tsl2x7x_write_control_reg() to reduce duplicate code.

The function tsl2x7x_chip_off() did not correctly return an error
code so this patch also corrects that issue.
Signed-off-by: Brian Masney <masneyb@onstation.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/staging/iio/light/tsl2x7x.c

@@ -307,6 +307,21 @@ static int tsl2x7x_read_status(struct tsl2X7X_chip *chip)
 	return ret;
 }
 
+static int tsl2x7x_write_control_reg(struct tsl2X7X_chip *chip, u8 data)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(chip->client,
+					TSL2X7X_CMD_REG | TSL2X7X_CNTRL, data);
+	if (ret < 0) {
+		dev_err(&chip->client->dev,
+			"%s: failed to write to control register %x: %d\n",
+			__func__, data, ret);
+	}
+
+	return ret;
+}
+
 /**
  * tsl2x7x_get_lux() - Reads and calculates current lux value.
  * @indio_dev:	pointer to IIO device
@@ -597,7 +612,6 @@ static int tsl2x7x_chip_on(struct iio_dev *indio_dev)
 	int i;
 	int ret = 0;
 	u8 *dev_reg;
-	u8 utmp;
 	int als_count;
 	int als_time;
 	struct tsl2X7X_chip *chip = iio_priv(indio_dev);
@@ -659,14 +673,9 @@ static int tsl2x7x_chip_on(struct iio_dev *indio_dev)
 	 * TSL2X7X Specific power-on / adc enable sequence
 	 * Power on the device 1st.
 	 */
-	utmp = TSL2X7X_CNTL_PWR_ON;
-	ret = i2c_smbus_write_byte_data(chip->client,
-					TSL2X7X_CMD_REG | TSL2X7X_CNTRL, utmp);
-	if (ret < 0) {
-		dev_err(&chip->client->dev,
-			"%s: failed on CNTRL reg.\n", __func__);
+	ret = tsl2x7x_write_control_reg(chip, TSL2X7X_CNTL_PWR_ON);
+	if (ret < 0)
 		return ret;
-	}
 
 	/*
 	 * Use the following shadow copy for our delay before enabling ADC.
@@ -691,16 +700,12 @@ static int tsl2x7x_chip_on(struct iio_dev *indio_dev)
 	 * NOW enable the ADC
 	 * initialize the desired mode of operation
 	 */
-	utmp = TSL2X7X_CNTL_PWR_ON |
-			TSL2X7X_CNTL_ADC_ENBL |
-			TSL2X7X_CNTL_PROX_DET_ENBL;
-	ret = i2c_smbus_write_byte_data(chip->client,
-					TSL2X7X_CMD_REG | TSL2X7X_CNTRL, utmp);
-	if (ret < 0) {
-		dev_err(&chip->client->dev,
-			"%s: failed on 2nd CTRL reg.\n", __func__);
+	ret = tsl2x7x_write_control_reg(chip,
+					TSL2X7X_CNTL_PWR_ON |
+					TSL2X7X_CNTL_ADC_ENBL |
+					TSL2X7X_CNTL_PROX_DET_ENBL);
+	if (ret < 0)
 		return ret;
-	}
 
 	chip->tsl2x7x_chip_status = TSL2X7X_CHIP_WORKING;
 
@@ -713,13 +718,9 @@ static int tsl2x7x_chip_on(struct iio_dev *indio_dev)
 			reg_val |= TSL2X7X_CNTL_PROX_DET_ENBL;
 
 		reg_val |= chip->settings.interrupts_en;
-		ret = i2c_smbus_write_byte_data(chip->client,
-						TSL2X7X_CMD_REG | TSL2X7X_CNTRL,
-						reg_val);
+		ret = tsl2x7x_write_control_reg(chip, reg_val);
 		if (ret < 0)
-			dev_err(&chip->client->dev,
-				"%s: failed in tsl2x7x_IOCTL_INT_SET.\n",
-				__func__);
+			return ret;
 
 		ret = tsl2x7x_clear_interrupts(chip,
 					       TSL2X7X_CMD_PROXALS_INT_CLR);
@@ -732,16 +733,11 @@ static int tsl2x7x_chip_on(struct iio_dev *indio_dev)
 
 static int tsl2x7x_chip_off(struct iio_dev *indio_dev)
 {
-	int ret;
 	struct tsl2X7X_chip *chip = iio_priv(indio_dev);
 
 	/* turn device off */
 	chip->tsl2x7x_chip_status = TSL2X7X_CHIP_SUSPENDED;
-
-	ret = i2c_smbus_write_byte_data(chip->client,
-					TSL2X7X_CMD_REG | TSL2X7X_CNTRL, 0x00);
-
-	return ret;
+	return tsl2x7x_write_control_reg(chip, 0x00);
 }
 
 /**