[PATCH 22/34] iio: inkern: only return error codes in iio_channel_get_*() APIs

["Nuno Sá" <nuno.sa@analog.com>]

APIs like of_iio_channel_get_by_name() and of_iio_channel_get_all() were
returning a mix of NULL and error pointers being NULL the way to
"notify" that we should do a "system" lookup for channels. This make
it very confusing and prone to errors as commit dbbccf7c20bf
("iio: inkern: fix return value in devm_of_iio_channel_get_by_name()")
proves. On top of this, patterns like 'if (channel != NULL) return channel'
were being used where channel could actually be an error code which
makes the code hard to read.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
---
 drivers/iio/inkern.c | 24 +++++++++++-------------
 1 file changed, 11 insertions(+), 13 deletions(-)

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index 87fd2a0d44f2..31d9c122199a 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -214,7 +214,7 @@ static struct iio_channel *of_iio_channel_get(struct device_node *np, int index)
 struct iio_channel *of_iio_channel_get_by_name(struct device_node *np,
 					       const char *name)
 {
-	struct iio_channel *chan = NULL;
+	struct iio_channel *chan;
 
 	/* Walk up the tree of devices looking for a matching iio channel */
 	while (np) {
@@ -231,11 +231,11 @@ struct iio_channel *of_iio_channel_get_by_name(struct device_node *np,
 							 name);
 		chan = of_iio_channel_get(np, index);
 		if (!IS_ERR(chan) || PTR_ERR(chan) == -EPROBE_DEFER)
-			break;
-		else if (name && index >= 0) {
+			return chan;
+		if (name && index >= 0) {
 			pr_err("ERROR: could not get IIO channel %pOF:%s(%i)\n",
 				np, name ? name : "", index);
-			return NULL;
+			return chan;
 		}
 
 		/*
@@ -245,10 +245,10 @@ struct iio_channel *of_iio_channel_get_by_name(struct device_node *np,
 		 */
 		np = np->parent;
 		if (np && !of_get_property(np, "io-channel-ranges", NULL))
-			return NULL;
+			return chan;
 	}
 
-	return chan;
+	return ERR_PTR(-ENODEV);
 }
 EXPORT_SYMBOL_GPL(of_iio_channel_get_by_name);
 
@@ -267,8 +267,8 @@ static struct iio_channel *of_iio_channel_get_all(struct device *dev)
 			break;
 	} while (++nummaps);
 
-	if (nummaps == 0)	/* no error, return NULL to search map table */
-		return NULL;
+	if (nummaps == 0)	/* return -ENODEV to search map table */
+		return ERR_PTR(-ENODEV);
 
 	/* NULL terminated array to save passing size */
 	chans = kcalloc(nummaps + 1, sizeof(*chans), GFP_KERNEL);
@@ -295,7 +295,7 @@ static struct iio_channel *of_iio_channel_get_all(struct device *dev)
 
 static inline struct iio_channel *of_iio_channel_get_all(struct device *dev)
 {
-	return NULL;
+	return ERR_PTR(-ENODEV);
 }
 
 #endif /* CONFIG_OF */
@@ -362,7 +362,7 @@ struct iio_channel *iio_channel_get(struct device *dev,
 	if (dev) {
 		channel = of_iio_channel_get_by_name(dev->of_node,
 						     channel_name);
-		if (channel != NULL)
+		if (!IS_ERR(channel) || PTR_ERR(channel) == -EPROBE_DEFER)
 			return channel;
 	}
 
@@ -412,8 +412,6 @@ struct iio_channel *devm_of_iio_channel_get_by_name(struct device *dev,
 	channel = of_iio_channel_get_by_name(np, channel_name);
 	if (IS_ERR(channel))
 		return channel;
-	if (!channel)
-		return ERR_PTR(-ENODEV);
 
 	ret = devm_add_action_or_reset(dev, devm_iio_channel_free, channel);
 	if (ret)
@@ -436,7 +434,7 @@ struct iio_channel *iio_channel_get_all(struct device *dev)
 		return ERR_PTR(-EINVAL);
 
 	chans = of_iio_channel_get_all(dev);
-	if (chans)
+	if (!IS_ERR(chans) || PTR_ERR(chans) == -EPROBE_DEFER)
 		return chans;
 
 	name = dev_name(dev);
-- 
2.36.1