ARM: renesas: Scrub duplicate memory nodes from DT on Gen3

Scrub duplicate /memory@* node entries here. Some R-Car DTs might
contain multiple /memory@* nodes, however fdt_fixup_memory_banks()
either generates single /memory node or updates the first /memory
node. Any remaining memory nodes are thus potential duplicates.

However, it is not possible to delete all the memory nodes right
away, since some of those might not be DRAM memory nodes, but some
sort of other memory. Thus, delete only the memory nodes which are
in the R-Car3 DBSC ranges.
Signed-off-by: NMarek Vasut <marek.vasut+renesas@gmail.com>

arch/arm/mach-rmobile/Kconfig

@@ -13,6 +13,7 @@ config RCAR_GEN3
 	select ARM64
 	select PHY
 	select CMD_CACHE
+	select OF_BOARD_SETUP
 	select PINCTRL
 	select PINCONF
 	select PINCTRL_PFC

board/renesas/rcar-common/common.c

@@ -43,4 +43,84 @@ int dram_init_banksize(void)
 
 	return 0;
 }
+
+#if defined(CONFIG_OF_BOARD_SETUP)
+static int is_mem_overlap(void *blob, int first_mem_node, int curr_mem_node)
+{
+	struct fdt_resource first_mem_res, curr_mem_res;
+	int curr_mem_reg, first_mem_reg = 0;
+	int ret;
+
+	for (;;) {
+		ret = fdt_get_resource(blob, first_mem_node, "reg",
+				       first_mem_reg++, &first_mem_res);
+		if (ret) /* No more entries, no overlap found */
+			return 0;
+
+		curr_mem_reg = 0;
+		for (;;) {
+			ret = fdt_get_resource(blob, curr_mem_node, "reg",
+					       curr_mem_reg++, &curr_mem_res);
+			if (ret) /* No more entries, check next tuple */
+				break;
+
+			if (curr_mem_res.end < first_mem_res.start)
+				continue;
+
+			if (curr_mem_res.start >= first_mem_res.end)
+				continue;
+
+			printf("Overlap found: 0x%llx..0x%llx / 0x%llx..0x%llx\n",
+				first_mem_res.start, first_mem_res.end,
+				curr_mem_res.start, curr_mem_res.end);
+
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+int ft_board_setup(void *blob, struct bd_info *bd)
+{
+	/*
+	 * Scrub duplicate /memory@* node entries here. Some R-Car DTs might
+	 * contain multiple /memory@* nodes, however fdt_fixup_memory_banks()
+	 * either generates single /memory node or updates the first /memory
+	 * node. Any remaining memory nodes are thus potential duplicates.
+	 *
+	 * However, it is not possible to delete all the memory nodes right
+	 * away, since some of those might not be DRAM memory nodes, but some
+	 * sort of other memory. Thus, delete only the memory nodes which are
+	 * in the R-Car3 DBSC ranges.
+	 */
+	int mem = 0, first_mem_node = 0;
+
+	for (;;) {
+		mem = fdt_node_offset_by_prop_value(blob, mem,
+						    "device_type", "memory", 7);
+		if (mem < 0)
+			break;
+		if (!fdtdec_get_is_enabled(blob, mem))
+			continue;
+
+		/* First memory node, patched by U-Boot */
+		if (!first_mem_node) {
+			first_mem_node = mem;
+			continue;
+		}
+
+		/* Check the remaining nodes and delete duplicates */
+		if (!is_mem_overlap(blob, first_mem_node, mem))
+			continue;
+
+		/* Delete duplicate node, start again */
+		fdt_del_node(blob, mem);
+		first_mem_node = 0;
+		mem = 0;
+	}
+
+	return 0;
+}
+#endif
 #endif