iio: tcs3472: power down chip on probe failure

If tcs3472_probe() fails after enabling the chip (by writing PON | AEN
to the ENABLE register), the error paths return without powering down
the device.

Add an 'error_powerdown' label at the end of the cleanup chain that
calls tcs3472_powerdown() to power down the chip. The existing label
cascade is rerouted to fall through to the new label.

Move tcs3472_powerdown() above tcs3472_probe() so the probe can call
it without a forward declaration.

Found by code inspection while reviewing the probe error paths in
preparation for the devm_ conversion.

Fixes: eb869ad ("iio: Add tcs3472 color light sensor driver")
Signed-off-by: Aldo Conte <aldocontelk@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Author: aldocontelk

drivers/iio/light/tcs3472.c

@@ -440,6 +440,23 @@ static const struct iio_info tcs3472_info = {
 	.attrs = &tcs3472_attribute_group,
 };
 
+static int tcs3472_powerdown(struct tcs3472_data *data)
+{
+	int ret;
+	u8 enable_mask = TCS3472_ENABLE_AEN | TCS3472_ENABLE_PON;
+
+	mutex_lock(&data->lock);
+
+	ret = i2c_smbus_write_byte_data(data->client, TCS3472_ENABLE,
+					data->enable & ~enable_mask);
+	if (!ret)
+		data->enable &= ~enable_mask;
+
+	mutex_unlock(&data->lock);
+
+	return ret;
+}
+
 static int tcs3472_probe(struct i2c_client *client)
 {
 	struct tcs3472_data *data;
@@ -513,7 +530,7 @@ static int tcs3472_probe(struct i2c_client *client)
 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
 		tcs3472_trigger_handler, NULL);
 	if (ret < 0)
-		return ret;
+		goto error_powerdown;
 
 	if (client->irq) {
 		ret = request_threaded_irq(client->irq, NULL,
@@ -536,23 +553,8 @@ static int tcs3472_probe(struct i2c_client *client)
 		free_irq(client->irq, indio_dev);
 buffer_cleanup:
 	iio_triggered_buffer_cleanup(indio_dev);
-	return ret;
-}
-
-static int tcs3472_powerdown(struct tcs3472_data *data)
-{
-	int ret;
-	u8 enable_mask = TCS3472_ENABLE_AEN | TCS3472_ENABLE_PON;
-
-	mutex_lock(&data->lock);
-
-	ret = i2c_smbus_write_byte_data(data->client, TCS3472_ENABLE,
-		data->enable & ~enable_mask);
-	if (!ret)
-		data->enable &= ~enable_mask;
-
-	mutex_unlock(&data->lock);
-
+error_powerdown:
+	tcs3472_powerdown(data);
 	return ret;
 }