mtd: ofpart: grab device tree node directly from master device node

It seems more logical to use a device node directly associated with the
MTD master device (i.e., mtd->dev.of_node field) rather than requiring
auxiliary partition parser information to be passed in by the driver in
a separate struct.

This patch supports the mtd->dev.of_node field and deprecates the parser
data 'of_node' field

Driver conversions may now follow.

Additional side benefit to assigning mtd->dev.of_node rather than using
parser data: the driver core will automatically create a device -> node
symlink for us.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/ofpart.c

@@ -37,10 +37,11 @@ static int parse_ofpart_partitions(struct mtd_info *master,
 	bool dedicated = true;
 
 
-	if (!data)
-		return 0;
-
-	mtd_node = data->of_node;
+	/*
+	 * of_node can be provided through auxiliary parser data or (preferred)
+	 * by assigning the master device node
+	 */
+	mtd_node = data && data->of_node ? data->of_node : mtd_get_of_node(master);
 	if (!mtd_node)
 		return 0;
 
@@ -149,10 +150,11 @@ static int parse_ofoldpart_partitions(struct mtd_info *master,
 	} *part;
 	const char *names;
 
-	if (!data)
-		return 0;
-
-	dp = data->of_node;
+	/*
+	 * of_node can be provided through auxiliary parser data or (preferred)
+	 * by assigning the master device node
+	 */
+	dp = data && data->of_node ? data->of_node : mtd_get_of_node(master);
 	if (!dp)
 		return 0;
 

include/linux/mtd/partitions.h

@@ -56,7 +56,9 @@ struct device_node;
 /**
  * struct mtd_part_parser_data - used to pass data to MTD partition parsers.
  * @origin: for RedBoot, start address of MTD device
- * @of_node: for OF parsers, device node containing partitioning information
+ * @of_node: for OF parsers, device node containing partitioning information.
+ *           This field is deprecated, as the device node should simply be
+ *           assigned to the master struct device.
  */
 struct mtd_part_parser_data {
 	unsigned long origin;