mtd: ofpart: add compatible check for child nodes

In case that the nand device will support some features like Nand Flash
Controller, we want to make the sub feature as a sub node of nand device.

Use such organization it is easy to enable/disable feature, also it is back
compatible and more readable.

If the sub-node has a compatible property then it is a driver not partition.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
Acked-by: Brian Norris <computersforpeace@gmail.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
[ added a missing newline -Brian ]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

Documentation/devicetree/bindings/mtd/partition.txt

@@ -4,6 +4,7 @@ Partitions can be represented by sub-nodes of an mtd device. This can be used
 on platforms which have strong conventions about which portions of a flash are
 used for what purposes, but which don't use an on-flash partition table such
 as RedBoot.
+NOTE: if the sub-node has a compatible string, then it is not a partition.
 
 #address-cells & #size-cells must both be present in the mtd device. There are
 two valid values for both:

drivers/mtd/ofpart.c

@@ -20,6 +20,11 @@
 #include <linux/slab.h>
 #include <linux/mtd/partitions.h>
 
+static bool node_has_compatible(struct device_node *pp)
+{
+	return of_get_property(pp, "compatible", NULL);
+}
+
 static int parse_ofpart_partitions(struct mtd_info *master,
 				   struct mtd_partition **pparts,
 				   struct mtd_part_parser_data *data)
@@ -40,8 +45,12 @@ static int parse_ofpart_partitions(struct mtd_info *master,
 	/* First count the subnodes */
 	pp = NULL;
 	nr_parts = 0;
-	while ((pp = of_get_next_child(node, pp)))
+	while ((pp = of_get_next_child(node, pp))) {
+		if (node_has_compatible(pp))
+			continue;
+
 		nr_parts++;
+	}
 
 	if (nr_parts == 0)
 		return 0;
@@ -57,6 +66,9 @@ static int parse_ofpart_partitions(struct mtd_info *master,
 		int len;
 		int a_cells, s_cells;
 
+		if (node_has_compatible(pp))
+			continue;
+
 		reg = of_get_property(pp, "reg", &len);
 		if (!reg) {
 			nr_parts--;