iio: __iio_update_buffers: Split enable and disable path into helper functions

__iio_update_buffers is already a rather large function with many different
error paths and it is going to get even larger. This patch factors out the
device enable and device disable paths into separate helper functions.

The patch also re-implements iio_disable_all_buffers() using the new
iio_disable_buffers() function removing a fair bit of redundant code.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/industrialio-buffer.c

@@ -539,28 +539,6 @@ static void iio_buffer_deactivate(struct iio_buffer *buffer)
 	iio_buffer_put(buffer);
 }
 
-void iio_disable_all_buffers(struct iio_dev *indio_dev)
-{
-	struct iio_buffer *buffer, *_buffer;
-
-	if (list_empty(&indio_dev->buffer_list))
-		return;
-
-	if (indio_dev->setup_ops->predisable)
-		indio_dev->setup_ops->predisable(indio_dev);
-
-	list_for_each_entry_safe(buffer, _buffer,
-			&indio_dev->buffer_list, buffer_list)
-		iio_buffer_deactivate(buffer);
-
-	indio_dev->currentmode = INDIO_DIRECT_MODE;
-	if (indio_dev->setup_ops->postdisable)
-		indio_dev->setup_ops->postdisable(indio_dev);
-
-	if (indio_dev->available_scan_masks == NULL)
-		kfree(indio_dev->active_scan_mask);
-}
-
 static void iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
 	struct iio_buffer *buffer)
 {
@@ -683,59 +661,14 @@ static int iio_verify_update(struct iio_dev *indio_dev,
 	return 0;
 }
 
-static int __iio_update_buffers(struct iio_dev *indio_dev,
-		       struct iio_buffer *insert_buffer,
-		       struct iio_buffer *remove_buffer)
+static int iio_enable_buffers(struct iio_dev *indio_dev,
+	struct iio_device_config *config)
 {
 	int ret;
-	const unsigned long *old_mask;
-	struct iio_device_config new_config;
-
-	ret = iio_verify_update(indio_dev, insert_buffer, remove_buffer,
-		&new_config);
-	if (ret)
-		return ret;
-
-	if (insert_buffer) {
-		ret = iio_buffer_request_update(indio_dev, insert_buffer);
-		if (ret)
-			goto err_free_config;
-	}
 
-	/* Wind down existing buffers - iff there are any */
-	if (!list_empty(&indio_dev->buffer_list)) {
-		if (indio_dev->setup_ops->predisable) {
-			ret = indio_dev->setup_ops->predisable(indio_dev);
-			if (ret)
-				goto err_free_config;
-		}
-		indio_dev->currentmode = INDIO_DIRECT_MODE;
-		if (indio_dev->setup_ops->postdisable) {
-			ret = indio_dev->setup_ops->postdisable(indio_dev);
-			if (ret)
-				goto err_free_config;
-		}
-	}
-	/* Keep a copy of current setup to allow roll back */
-	old_mask = indio_dev->active_scan_mask;
-	if (!indio_dev->available_scan_masks)
-		indio_dev->active_scan_mask = NULL;
-
-	if (remove_buffer)
-		iio_buffer_deactivate(remove_buffer);
-	if (insert_buffer)
-		iio_buffer_activate(indio_dev, insert_buffer);
-
-	/* If no buffers in list, we are done */
-	if (list_empty(&indio_dev->buffer_list)) {
-		indio_dev->currentmode = INDIO_DIRECT_MODE;
-		iio_free_scan_mask(indio_dev, old_mask);
-		return 0;
-	}
-
-	indio_dev->active_scan_mask = new_config.scan_mask;
-	indio_dev->scan_timestamp = new_config.scan_timestamp;
-	indio_dev->scan_bytes = new_config.scan_bytes;
+	indio_dev->active_scan_mask = config->scan_mask;
+	indio_dev->scan_timestamp = config->scan_timestamp;
+	indio_dev->scan_bytes = config->scan_bytes;
 
 	iio_update_demux(indio_dev);
 
@@ -745,7 +678,7 @@ static int __iio_update_buffers(struct iio_dev *indio_dev,
 		if (ret) {
 			dev_dbg(&indio_dev->dev,
 			       "Buffer not started: buffer preenable failed (%d)\n", ret);
-			goto error_remove_inserted;
+			goto err_undo_config;
 		}
 	}
 
@@ -757,39 +690,108 @@ static int __iio_update_buffers(struct iio_dev *indio_dev,
 			dev_dbg(&indio_dev->dev,
 				"Buffer not started: update scan mode failed (%d)\n",
 				ret);
-			goto error_run_postdisable;
+			goto err_run_postdisable;
 		}
 	}
 
-	indio_dev->currentmode = new_config.mode;
+	indio_dev->currentmode = config->mode;
 
 	if (indio_dev->setup_ops->postenable) {
 		ret = indio_dev->setup_ops->postenable(indio_dev);
 		if (ret) {
 			dev_dbg(&indio_dev->dev,
 			       "Buffer not started: postenable failed (%d)\n", ret);
-			indio_dev->currentmode = INDIO_DIRECT_MODE;
-			if (indio_dev->setup_ops->postdisable)
-				indio_dev->setup_ops->postdisable(indio_dev);
-			goto error_disable_all_buffers;
+			goto err_run_postdisable;
 		}
 	}
 
-	iio_free_scan_mask(indio_dev, old_mask);
-
 	return 0;
 
-error_disable_all_buffers:
+err_run_postdisable:
 	indio_dev->currentmode = INDIO_DIRECT_MODE;
-error_run_postdisable:
 	if (indio_dev->setup_ops->postdisable)
 		indio_dev->setup_ops->postdisable(indio_dev);
-error_remove_inserted:
-	if (insert_buffer)
-		iio_buffer_deactivate(insert_buffer);
-	iio_free_scan_mask(indio_dev, indio_dev->active_scan_mask);
-	indio_dev->active_scan_mask = old_mask;
+err_undo_config:
+	indio_dev->active_scan_mask = NULL;
+
 	return ret;
+}
+
+static int iio_disable_buffers(struct iio_dev *indio_dev)
+{
+	int ret;
+
+	/* Wind down existing buffers - iff there are any */
+	if (list_empty(&indio_dev->buffer_list))
+		return 0;
+
+	if (indio_dev->setup_ops->predisable) {
+		ret = indio_dev->setup_ops->predisable(indio_dev);
+		if (ret)
+			return ret;
+	}
+
+	indio_dev->currentmode = INDIO_DIRECT_MODE;
+
+	if (indio_dev->setup_ops->postdisable) {
+		ret = indio_dev->setup_ops->postdisable(indio_dev);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int __iio_update_buffers(struct iio_dev *indio_dev,
+		       struct iio_buffer *insert_buffer,
+		       struct iio_buffer *remove_buffer)
+{
+	int ret;
+	const unsigned long *old_mask;
+	struct iio_device_config new_config;
+
+	ret = iio_verify_update(indio_dev, insert_buffer, remove_buffer,
+		&new_config);
+	if (ret)
+		return ret;
+
+	if (insert_buffer) {
+		ret = iio_buffer_request_update(indio_dev, insert_buffer);
+		if (ret)
+			goto err_free_config;
+	}
+
+	/* Keep a copy of current setup to allow roll back */
+	old_mask = indio_dev->active_scan_mask;
+	indio_dev->active_scan_mask = NULL;
+
+	ret = iio_disable_buffers(indio_dev);
+	if (ret) {
+		iio_free_scan_mask(indio_dev, old_mask);
+		goto err_free_config;
+	}
+
+	if (remove_buffer)
+		iio_buffer_deactivate(remove_buffer);
+	if (insert_buffer)
+		iio_buffer_activate(indio_dev, insert_buffer);
+
+	/* If no buffers in list, we are done */
+	if (list_empty(&indio_dev->buffer_list)) {
+		iio_free_scan_mask(indio_dev, old_mask);
+		return 0;
+	}
+
+	ret = iio_enable_buffers(indio_dev, &new_config);
+	if (ret) {
+		if (insert_buffer)
+			iio_buffer_deactivate(insert_buffer);
+		indio_dev->active_scan_mask = old_mask;
+		goto err_free_config;
+	}
+
+	iio_free_scan_mask(indio_dev, old_mask);
+	return 0;
 
 err_free_config:
 	iio_free_scan_mask(indio_dev, new_config.scan_mask);
@@ -834,6 +836,19 @@ int iio_update_buffers(struct iio_dev *indio_dev,
 }
 EXPORT_SYMBOL_GPL(iio_update_buffers);
 
+void iio_disable_all_buffers(struct iio_dev *indio_dev)
+{
+	struct iio_buffer *buffer, *_buffer;
+
+	iio_disable_buffers(indio_dev);
+	iio_free_scan_mask(indio_dev, indio_dev->active_scan_mask);
+	indio_dev->active_scan_mask = NULL;
+
+	list_for_each_entry_safe(buffer, _buffer,
+			&indio_dev->buffer_list, buffer_list)
+		iio_buffer_deactivate(buffer);
+}
+
 static ssize_t iio_buffer_store_enable(struct device *dev,
 				       struct device_attribute *attr,
 				       const char *buf,