mtd: partitions: Add OF support to RedBoot partitions

This adds device tree support for RedBoot partitioning. We
read out the FIS directory block information from the device
tree and then parse the partition table from there.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>

drivers/mtd/parsers/redboot.c

@@ -25,7 +25,7 @@
 #include <linux/slab.h>
 #include <linux/init.h>
 #include <linux/vmalloc.h>
-
+#include <linux/of.h>
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/partitions.h>
 #include <linux/module.h>
@@ -56,6 +56,27 @@ static inline int redboot_checksum(struct fis_image_desc *img)
 	return 1;
 }
 
+static void parse_redboot_of(struct mtd_info *master)
+{
+	struct device_node *np;
+	u32 dirblock;
+	int ret;
+
+	np = mtd_get_of_node(master);
+	if (!np)
+		return;
+
+	ret = of_property_read_u32(np, "fis-index-block", &dirblock);
+	if (ret)
+		return;
+
+	/*
+	 * Assign the block found in the device tree to the local
+	 * directory block pointer.
+	 */
+	directory = dirblock;
+}
+
 static int parse_redboot_partitions(struct mtd_info *master,
 				    const struct mtd_partition **pparts,
 				    struct mtd_part_parser_data *data)
@@ -76,6 +97,8 @@ static int parse_redboot_partitions(struct mtd_info *master,
 	static char nullstring[] = "unallocated";
 #endif
 
+	parse_redboot_of(master);
+
 	if ( directory < 0 ) {
 		offset = master->size + directory * master->erasesize;
 		while (mtd_block_isbad(master, offset)) {
@@ -289,9 +312,16 @@ static int parse_redboot_partitions(struct mtd_info *master,
 	return ret;
 }
 
+static const struct of_device_id mtd_parser_redboot_of_match_table[] = {
+	{ .compatible = "redboot-fis" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, mtd_parser_redboot_of_match_table);
+
 static struct mtd_part_parser redboot_parser = {
 	.parse_fn = parse_redboot_partitions,
 	.name = "RedBoot",
+	.of_match_table = mtd_parser_redboot_of_match_table,
 };
 module_mtd_part_parser(redboot_parser);