bcm4908: add MTD support for repartitioning

It's required for sysupgrade which requires:
1. Flashing new firmware
2. Finding updated bootfs partition
3. Updating bootfs content

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

diff --git a/target/linux/bcm4908/patches-5.4/401-mtd-support-BLKRRPART.patch b/target/linux/bcm4908/patches-5.4/401-mtd-support-BLKRRPART.patch
new file mode 100644 (file)
index 0000000..70a1896
--- /dev/null
+++ b/target/linux/bcm4908/patches-5.4/401-mtd-support-BLKRRPART.patch
@@ -0,0 +1,28 @@
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Mon, 22 Mar 2021 07:15:17 +0100
+Subject: [PATCH] mtd: support BLKRRPART
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Rescan MTD subpartitions on request.
+
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+---
+
+--- a/drivers/mtd/mtdchar.c
++++ b/drivers/mtd/mtdchar.c
+@@ -1015,8 +1015,11 @@ static int mtdchar_ioctl(struct file *fi
+ 
+       case BLKRRPART:
+       {
+-              /* No reread partition feature. Just return ok */
+-              ret = 0;
++              int nr_parts;
++
++              del_mtd_partitions(mtd);
++              nr_parts = parse_mtd_partitions(mtd, NULL, NULL);
++              ret = nr_parts < 0 ? nr_parts : 0;
+               break;
+       }
+       }