device property: keep single value inplace

BugLink: http://bugs.launchpad.net/bugs/1533035

We may save a lot of lines of code and space by keeping single values inside
the struct property_entry. Refactor the implementation to do so.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit 66586bab)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/base/property.c

@@ -72,7 +72,10 @@ static void *pset_prop_find(struct property_set *pset, const char *propname,
 	prop = pset_prop_get(pset, propname);
 	if (!prop)
 		return ERR_PTR(-EINVAL);
-	pointer = prop->value.raw_data;
+	if (prop->is_array)
+		pointer = prop->pointer.raw_data;
+	else
+		pointer = &prop->value.raw_data;
 	if (!pointer)
 		return ERR_PTR(-ENODATA);
 	if (length > prop->length)
@@ -167,6 +170,31 @@ static int pset_prop_read_string_array(struct property_set *pset,
 	return 0;
 }
 
+static int pset_prop_read_string(struct property_set *pset,
+				 const char *propname, const char **strings)
+{
+	struct property_entry *prop;
+	const char **pointer;
+
+	prop = pset_prop_get(pset, propname);
+	if (!prop)
+		return -EINVAL;
+	if (!prop->is_string)
+		return -EILSEQ;
+	if (prop->is_array) {
+		pointer = prop->pointer.str;
+		if (!pointer)
+			return -ENODATA;
+	} else {
+		pointer = &prop->value.str;
+		if (*pointer && strnlen(*pointer, prop->length) >= prop->length)
+			return -EILSEQ;
+	}
+
+	*strings = *pointer;
+	return 0;
+}
+
 static inline struct fwnode_handle *dev_fwnode(struct device *dev)
 {
 	return IS_ENABLED(CONFIG_OF) && dev->of_node ?
@@ -566,8 +594,7 @@ int fwnode_property_read_string(struct fwnode_handle *fwnode,
 		return acpi_node_prop_read(fwnode, propname, DEV_PROP_STRING,
 					   val, 1);
 	else if (is_pset_node(fwnode))
-		return pset_prop_read_string_array(to_pset_node(fwnode),
-						   propname, val, 1);
+		return pset_prop_read_string(to_pset_node(fwnode), propname, val);
 	return -ENXIO;
 }
 EXPORT_SYMBOL_GPL(fwnode_property_read_string);

include/linux/property.h

@@ -145,19 +145,34 @@ static inline int fwnode_property_read_u64(struct fwnode_handle *fwnode,
  * struct property_entry - "Built-in" device property representation.
  * @name: Name of the property.
  * @length: Length of data making up the value.
- * @value: Value of the property (an array of items of the given type).
+ * @is_array: True when the property is an array.
+ * @is_string: True when property is a string.
+ * @pointer: Pointer to the property (an array of items of the given type).
+ * @value: Value of the property (when it is a single item of the given type).
  */
 struct property_entry {
 	const char *name;
 	size_t length;
+	bool is_array;
+	bool is_string;
 	union {
-		void *raw_data;
-		u8 *u8_data;
-		u16 *u16_data;
-		u32 *u32_data;
-		u64 *u64_data;
-		const char **str;
-	} value;
+		union {
+			void *raw_data;
+			u8 *u8_data;
+			u16 *u16_data;
+			u32 *u32_data;
+			u64 *u64_data;
+			const char **str;
+		} pointer;
+		union {
+			unsigned long long raw_data;
+			u8 u8_data;
+			u16 u16_data;
+			u32 u32_data;
+			u64 u64_data;
+			const char *str;
+		} value;
+	};
 };
 
 /**