[PATCH v2 15/19] of: export new of_cdev_find helper

[Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>]

__of_find_path goes through the hassle of determining the cdev, only to
discard it again and return either zero or an error code.

Follow up commits will need to get the cdev corresponding to a path in
the DT. So let's make that easier by exporting a suitable helper function.

Reviewed-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx>
Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
---
v1 -> v2:
  - fix typo (Ulrich)
  - Add Marco's Reviewed-by
---
 drivers/of/of_path.c | 59 ++++++++++++++++++++++++++++++--------------
 include/of.h         |  1 +
 2 files changed, 41 insertions(+), 19 deletions(-)

diff --git a/drivers/of/of_path.c b/drivers/of/of_path.c
index d11cb2a524eb..22903da15ed6 100644
--- a/drivers/of/of_path.c
+++ b/drivers/of/of_path.c
@@ -27,21 +27,17 @@ struct device *of_find_device_by_node_path(const char *path)
 }
 
 /**
- * __of_find_path
+ * __of_cdev_find
  *
  * @node: The node to find the cdev for, can be the device or a
  *        partition in the device
  * @part: Optionally, a description of a partition of @node.  See of_find_path
- * @outpath: if this function returns 0 outpath will contain the path belonging
- *           to the input path description. Must be freed with free().
- * @flags: use OF_FIND_PATH_FLAGS_BB to return the .bb device if available
  *
  */
-static int __of_find_path(struct device_node *node, const char *part, char **outpath, unsigned flags)
+static struct cdev *__of_cdev_find(struct device_node *node, const char *part)
 {
 	struct device *dev;
 	struct cdev *cdev;
-	bool add_bb = false;
 
 	/*
 	 * On EFI, where devices are not instantiated from device tree, the
@@ -64,24 +60,17 @@ static int __of_find_path(struct device_node *node, const char *part, char **out
 
 			/* when partuuid is specified short-circuit the search for the cdev */
 			ret = of_property_read_string(node, "partuuid", &uuid);
-			if (!ret) {
-				cdev = cdev_by_partuuid(uuid);
-				if (!cdev)
-					return -ENODEV;
-
-				*outpath = basprintf("/dev/%s", cdev->name);
-
-				return 0;
-			}
+			if (!ret)
+				return cdev_by_partuuid(uuid) ?: ERR_PTR(-ENODEV);
 		}
 
 		dev = of_find_device_by_node_path(devnode->full_name);
 		if (!dev)
-			return -ENODEV;
+			return ERR_PTR(-ENODEV);
 	}
 
 	if (dev->bus && !dev->driver)
-		return -EPROBE_DEFER;
+		return ERR_PTR(-EPROBE_DEFER);
 
 	device_detect(dev);
 
@@ -90,8 +79,40 @@ static int __of_find_path(struct device_node *node, const char *part, char **out
 	else
 		cdev = cdev_by_device_node(node);
 
-	if (!cdev)
-		return -ENOENT;
+	return cdev ?: ERR_PTR(-ENOENT);
+}
+
+/**
+ * of_cdev_find
+ *
+ * @node: The node to find the cdev for, can be the device or a
+ *        partition in the device
+ *
+ */
+struct cdev *of_cdev_find(struct device_node *node)
+{
+	return __of_cdev_find(node, NULL);
+}
+
+/**
+ * __of_find_path
+ *
+ * @node: The node to find the cdev for, can be the device or a
+ *        partition in the device
+ * @part: Optionally, a description of a partition of @node.  See of_find_path
+ * @outpath: if this function returns 0 outpath will contain the path belonging
+ *           to the input path description. Must be freed with free().
+ * @flags: use OF_FIND_PATH_FLAGS_BB to return the .bb device if available
+ *
+ */
+static int __of_find_path(struct device_node *node, const char *part, char **outpath, unsigned flags)
+{
+	bool add_bb = false;
+	struct cdev *cdev;
+
+	cdev = __of_cdev_find(node, part);
+	if (IS_ERR(cdev))
+		return PTR_ERR(cdev);
 
 	if ((flags & OF_FIND_PATH_FLAGS_BB) && cdev->mtd &&
 	    mtd_can_have_bb(cdev->mtd))
diff --git a/include/of.h b/include/of.h
index c716f9283316..2b75ce63e185 100644
--- a/include/of.h
+++ b/include/of.h
@@ -331,6 +331,7 @@ int of_add_memory_bank(struct device_node *node, bool dump, int r,
 struct device *of_find_device_by_node_path(const char *path);
 #define OF_FIND_PATH_FLAGS_BB 1		/* return .bb device if available */
 int of_find_path(struct device_node *node, const char *propname, char **outpath, unsigned flags);
+struct cdev *of_cdev_find(struct device_node *node);
 int of_find_path_by_node(struct device_node *node, char **outpath, unsigned flags);
 struct device_node *of_find_node_by_devpath(struct device_node *root, const char *path);
 int of_register_fixup(int (*fixup)(struct device_node *, void *), void *context);
-- 
2.39.2