[PATCH] of/platform: Avoid compilation warning

[Miquel Raynal]

The of_find_device_by_node() helper has its dummy counterpart for when
CONFIG_OF is not enabled. However, it is clearly stated in the kernel
documentation that it "takes a reference to the embedded struct device
which needs to be dropped after use". Which means the of_dev_put()
helper might have to be called afterwards. Unfortunately, there is no
of_dev_put() dummy function if OF_CONFIG is not enabled which seems
odd in this case. The of_dev_put() helper is pretty simple, it just
checks the validity of the single argument and calls put_device() on
it. One can just call put_device() directly to avoid any build issue
but I find much more accurate in this case to create the dummy
helper.

With this helper, a file using of_find_device_by_node() can also call
of_dev_put() without triggering the following:

error: implicit declaration of function âof_dev_putâ; did you mean âof_node_putâ? [-Werror=implicit-function-declaration]

Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
---
 include/linux/of_platform.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/of_platform.h b/include/linux/of_platform.h
index 84a966623e78..84d9e60e517e 100644
--- a/include/linux/of_platform.h
+++ b/include/linux/of_platform.h
@@ -54,11 +54,13 @@ extern struct platform_device *of_device_alloc(struct device_node *np,
 					 struct device *parent);
 #ifdef CONFIG_OF
 extern struct platform_device *of_find_device_by_node(struct device_node *np);
+extern void of_dev_put(struct platform_device *dev);
 #else
 static inline struct platform_device *of_find_device_by_node(struct device_node *np)
 {
 	return NULL;
 }
+static inline void of_dev_put(struct platform_device *dev) { }
 #endif
 
 /* Platform devices and busses creation */
-- 
2.20.1