bcm53xx: properly support sysupgrade using Seama on NAND devices

It updates kernel and then formats UBI without loosing erase counters.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>

target/linux/bcm53xx/base-files/lib/upgrade/platform.sh

@@ -197,6 +197,53 @@ platform_pre_upgrade_trx() {
 	nand_do_upgrade /tmp/root.ubi
 }
 
+platform_pre_upgrade_seama() {
+	local dir="/tmp/sysupgrade-bcm53xx"
+	local seama="$1"
+	local tmp
+
+	# Extract Seama entity from Seama seal
+	rm -fR $dir
+	mkdir -p $dir
+	oseama extract "$seama" \
+		-e 0 \
+		-o $dir/seama.entity
+	[ $? -ne 0 ] && {
+		echo "Failed to extract Seama entity."
+		return
+	}
+	local entity_size=$(wc -c $dir/seama.entity | cut -d ' ' -f 1)
+
+	local ubi_offset=0
+	tmp=0
+	while [ 1 ]; do
+		[ $tmp -ge $entity_size ] && break
+		[ "$(dd if=$dir/seama.entity skip=$tmp bs=1 count=4 2>/dev/null)" = "UBI#" ] && {
+			ubi_offset=$tmp
+			break
+		}
+		tmp=$(($tmp + 131072))
+	done
+	[ $ubi_offset -eq 0 ] && {
+		echo "Failed to find UBI in Seama entity."
+		return
+	}
+
+	local ubi_length=0
+	while [ "$(dd if=$dir/seama.entity skip=$(($ubi_offset + $ubi_length)) bs=1 count=4 2>/dev/null)" = "UBI#" ]; do
+		ubi_length=$(($ubi_length + 131072))
+	done
+
+	dd if=$dir/seama.entity of=$dir/kernel.seama bs=131072 count=$(($ubi_offset / 131072)) 2>/dev/null
+	dd if=$dir/seama.entity of=$dir/root.ubi bs=131072 skip=$(($ubi_offset / 131072)) count=$(($ubi_length / 131072)) 2>/dev/null
+
+	# Flash
+	local kernel_size=$(sed -n 's/mtd[0-9]*: \([0-9a-f]*\).*"\(kernel\|linux\)".*/\1/p' /proc/mtd)
+	mtd write $dir/kernel.seama firmware
+	mtd ${kernel_size:+-c 0x$kernel_size} fixseama firmware
+	nand_do_upgrade $dir/root.ubi
+}
+
 platform_pre_upgrade() {
 	export RAMFS_COPY_BIN="${RAMFS_COPY_BIN} /usr/bin/oseama /bin/sed"
 
@@ -208,7 +255,7 @@ platform_pre_upgrade() {
 	case "$file_type" in
 		"chk")		platform_pre_upgrade_trx "$1" $((0x$(get_magic_long_at "$1" 4)));;
 		"cybertan")	platform_pre_upgrade_trx "$1" 32;;
-		"seama")	return;;
+		"seama")	platform_pre_upgrade_seama "$1";;
 		"trx")		platform_pre_upgrade_trx "$1";;
 	esac
 }