kernel: use add_mtd_partitions() helper when using OpenWrt parsers

This helper uses hierarchical partitions layout following the way
upstream parsers work. It's closer to what we should use when mainlining
our solutions. It also doesn't require hacky casting of struct
mtd_partition to the const.

THIS WILL AFFECT KERNEL PRINTING PARTITIONS IN THE LOG

Something like:
[    3.930158] 0x0000004e0000-0x000001fb0000 : "rootfs_data"
will get replaced by:
[    3.907338] Creating 1 MTD partitions on "rootfs":
[    3.912142] 0x00000031d400-0x000001ded400 : "rootfs_data"

It's important to understand that "rootfs_data" in above example is a
*subpartition* of the "rootfs" now. To get absolute addresses (e.g. for
some debugging purposes) one has to add them to the "rootfs", e.g.
[    3.912548] 0x0000001c2c00-0x000001fb0000 : "rootfs"

(0x1c2c00 + 0x31d400 = 0x4e0000)

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

target/linux/generic/pending-4.14/401-mtd-add-support-for-different-partition-parser-types.patch

@@ -20,18 +20,18 @@ Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
  
  /*
   * Given a pointer to the MTD object in the mtd_part structure, we can retrieve
-@@ -751,6 +755,36 @@ int mtd_del_partition(struct mtd_info *m
+@@ -751,6 +755,28 @@ int mtd_del_partition(struct mtd_info *m
  }
  EXPORT_SYMBOL_GPL(mtd_del_partition);
  
-+static int
-+run_parsers_by_type(struct mtd_part *slave, enum mtd_parser_type type)
++static int run_parsers_by_type(struct mtd_part *slave,
++			       enum mtd_parser_type type)
 +{
-+	struct mtd_partition *parts;
++	const struct mtd_partition *parts;
 +	int nr_parts;
-+	int i;
++	int err;
 +
-+	nr_parts = parse_mtd_partitions_by_type(&slave->mtd, type, (const struct mtd_partition **)&parts,
++	nr_parts = parse_mtd_partitions_by_type(&slave->mtd, type, &parts,
 +						NULL);
 +	if (nr_parts <= 0)
 +		return nr_parts;
@@ -39,25 +39,17 @@ Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
 +	if (WARN_ON(!parts))
 +		return 0;
 +
-+	for (i = 0; i < nr_parts; i++) {
-+		/* adjust partition offsets */
-+		parts[i].offset += slave->offset;
-+
-+		mtd_add_partition(slave->parent,
-+				  parts[i].name,
-+				  parts[i].offset,
-+				  parts[i].size);
-+	}
++	err = add_mtd_partitions(&slave->mtd, parts, nr_parts);
 +
 +	kfree(parts);
 +
-+	return nr_parts;
++	return err ? err : nr_parts;
 +}
 +
  #ifdef CONFIG_MTD_SPLIT_FIRMWARE_NAME
  #define SPLIT_FIRMWARE_NAME	CONFIG_MTD_SPLIT_FIRMWARE_NAME
  #else
-@@ -1122,6 +1156,61 @@ void mtd_part_parser_cleanup(struct mtd_
+@@ -1122,6 +1148,61 @@ void mtd_part_parser_cleanup(struct mtd_
  	}
  }
  

target/linux/generic/pending-4.14/402-mtd-use-typed-mtd-parsers-for-rootfs-and-firmware-split.patch

@@ -10,7 +10,7 @@ Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
 
 --- a/drivers/mtd/mtdpart.c
 +++ b/drivers/mtd/mtdpart.c
-@@ -793,6 +793,7 @@ run_parsers_by_type(struct mtd_part *sla
+@@ -785,6 +785,7 @@ static int run_parsers_by_type(struct mt
  
  static void split_firmware(struct mtd_info *master, struct mtd_part *part)
  {
@@ -18,7 +18,7 @@ Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
  }
  
  static void mtd_partition_split(struct mtd_info *master, struct mtd_part *part)
-@@ -802,6 +803,12 @@ static void mtd_partition_split(struct m
+@@ -794,6 +795,12 @@ static void mtd_partition_split(struct m
  	if (rootfs_found)
  		return;
  

target/linux/generic/pending-4.14/404-mtd-add-more-helper-functions.patch

@@ -11,7 +11,7 @@ Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
 
 --- a/drivers/mtd/mtdpart.c
 +++ b/drivers/mtd/mtdpart.c
-@@ -1235,6 +1235,24 @@ int mtd_is_partition(const struct mtd_in
+@@ -1227,6 +1227,24 @@ int mtd_is_partition(const struct mtd_in
  }
  EXPORT_SYMBOL_GPL(mtd_is_partition);