mtd: ofpart: support partitions of 4 GiB and larger

Previously, partitions were limited to less than 4 GiB in size because
the address and size were read as 32-bit values. Add support for 64-bit
values to support devices of 4 GiB and larger.

Signed-off-by: Joe Schaack <jschaack@xes-inc.com>
Signed-off-by: Nate Case <ncase@xes-inc.com>
Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

Documentation/devicetree/bindings/mtd/partition.txt

@@ -5,8 +5,12 @@ 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.
 
-#address-cells & #size-cells must both be present in the mtd device and be
-equal to 1.
+#address-cells & #size-cells must both be present in the mtd device. There are
+two valid values for both:
+<1>: for partitions that require a single 32-bit cell to represent their
+     size/address (aka the value is below 4 GiB)
+<2>: for partitions that require two 32-bit cells to represent their
+     size/address (aka the value is 4 GiB or greater).
 
 Required properties:
 - reg : The partition's offset and size within the mtd bank.
@@ -36,3 +40,31 @@ flash@0 {
 		reg = <0x0100000 0x200000>;
 	};
 };
+
+flash@1 {
+	#address-cells = <1>;
+	#size-cells = <2>;
+
+	/* a 4 GiB partition */
+	partition@0 {
+		label = "filesystem";
+		reg = <0x00000000 0x1 0x00000000>;
+	};
+};
+
+flash@2 {
+	#address-cells = <2>;
+	#size-cells = <2>;
+
+	/* an 8 GiB partition */
+	partition@0 {
+		label = "filesystem #1";
+		reg = <0x0 0x00000000 0x2 0x00000000>;
+	};
+
+	/* a 4 GiB partition */
+	partition@200000000 {
+		label = "filesystem #2";
+		reg = <0x2 0x00000000 0x1 0x00000000>;
+	};
+};

drivers/mtd/ofpart.c

@@ -55,15 +55,18 @@ static int parse_ofpart_partitions(struct mtd_info *master,
 	while ((pp = of_get_next_child(node, pp))) {
 		const __be32 *reg;
 		int len;
+		int a_cells, s_cells;
 
 		reg = of_get_property(pp, "reg", &len);
 		if (!reg) {
 			nr_parts--;
 			continue;
 		}
 
-		(*pparts)[i].offset = be32_to_cpu(reg[0]);
-		(*pparts)[i].size = be32_to_cpu(reg[1]);
+		a_cells = of_n_addr_cells(pp);
+		s_cells = of_n_size_cells(pp);
+		(*pparts)[i].offset = of_read_number(reg, a_cells);
+		(*pparts)[i].size = of_read_number(reg + a_cells, s_cells);
 
 		partname = of_get_property(pp, "label", &len);
 		if (!partname)