of: Warn when of_property_read_bool() is used on non-boolean properties

The use of of_property_read_bool() for non-boolean properties is
deprecated. The primary use of it was to test property presence, but
that has been replaced in favor of of_property_present(). With those
uses now fixed, add a warning to discourage new ones.

Reviewed-by: Krzysztof Kozlowski <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Rob Herring (Arm) <[email protected]>

Author: robherring

drivers/of/property.c

@@ -31,6 +31,32 @@
 
 #include "of_private.h"
 
+/**
+ * of_property_read_bool - Find a property
+ * @np:		device node from which the property value is to be read.
+ * @propname:	name of the property to be searched.
+ *
+ * Search for a boolean property in a device node. Usage on non-boolean
+ * property types is deprecated.
+ *
+ * Return: true if the property exists false otherwise.
+ */
+bool of_property_read_bool(const struct device_node *np, const char *propname)
+{
+	struct property *prop = of_find_property(np, propname, NULL);
+
+	/*
+	 * Boolean properties should not have a value. Testing for property
+	 * presence should either use of_property_present() or just read the
+	 * property value and check the returned error code.
+	 */
+	if (prop && prop->length)
+		pr_warn("%pOF: Read of boolean property '%s' with a value.\n", np, propname);
+
+	return prop ? true : false;
+}
+EXPORT_SYMBOL(of_property_read_bool);
+
 /**
  * of_graph_is_present() - check graph's presence
  * @node: pointer to device_node containing graph port

include/linux/of.h

@@ -311,6 +311,7 @@ extern struct device_node *of_find_node_with_property(
 extern struct property *of_find_property(const struct device_node *np,
 					 const char *name,
 					 int *lenp);
+extern bool of_property_read_bool(const struct device_node *np, const char *propname);
 extern int of_property_count_elems_of_size(const struct device_node *np,
 				const char *propname, int elem_size);
 extern int of_property_read_u32_index(const struct device_node *np,
@@ -615,6 +616,12 @@ static inline struct device_node *of_find_compatible_node(
 	return NULL;
 }
 
+static inline bool of_property_read_bool(const struct device_node *np,
+					const char *propname)
+{
+	return false;
+}
+
 static inline int of_property_count_elems_of_size(const struct device_node *np,
 			const char *propname, int elem_size)
 {
@@ -1242,24 +1249,6 @@ static inline int of_property_read_string_index(const struct device_node *np,
 	return rc < 0 ? rc : 0;
 }
 
-/**
- * of_property_read_bool - Find a property
- * @np:		device node from which the property value is to be read.
- * @propname:	name of the property to be searched.
- *
- * Search for a boolean property in a device node. Usage on non-boolean
- * property types is deprecated.
- *
- * Return: true if the property exists false otherwise.
- */
-static inline bool of_property_read_bool(const struct device_node *np,
-					 const char *propname)
-{
-	const struct property *prop = of_find_property(np, propname, NULL);
-
-	return prop ? true : false;
-}
-
 /**
  * of_property_present - Test if a property is present in a node
  * @np:		device node to search for the property.