[openwrt/openwrt] bcm4908: add MTD support for repartitioning

[LEDE Commits]

rmilecki pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/2b4986b9424872ec8962a34ca38c399aae4a53b3

commit 2b4986b9424872ec8962a34ca38c399aae4a53b3
Author: Rafał Miłecki <rafal at milecki.pl>
AuthorDate: Mon Mar 22 07:38:06 2021 +0100

    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 at milecki.pl>
---
 .../patches-5.4/401-mtd-support-BLKRRPART.patch    | 28 ++++++++++++++++++++++
 1 file changed, 28 insertions(+)

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
index 0000000000..70a1896328
--- /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 at 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 at 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;
+ 	}
+ 	}