mediatek: store MAC address in boot partition on Banana Pi R2

Like many boards, the Banana Pi R2 doesn't have permanant storage of
its MAC address, and we store the first random one that the kernel
generates in order to use it later and at least be consistent.

Store it in the FAT boot partition, just as the U7623 board (and others)
do.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

target/linux/mediatek/mt7623/base-files/lib/preinit/07_set_iface_mac

@@ -1,23 +1,19 @@
 # Copyright (C) 2018 OpenWrt.org
 
-RECOVERY_PART=/dev/mmcblk0p1
+. /lib/functions.sh
+. /lib/functions/system.sh
 
-preinit_set_mac_address() {
+set_recovery_mac_address() {
+	local RECOVERY_PART="$1"
 	local mac
 
-	. /lib/functions.sh
-	. /lib/functions/system.sh
-
-	case $(board_name) in
-	unielec,u7623-02-emmc-512m)
-		if [ -b $RECOVERY_PART ]; then
-			insmod nls_cp437
-			insmod nls_iso8859-1
-			insmod fat
-			insmod vfat
-			mkdir -p /tmp/recovery
-			mount -o rw,noatime $RECOVERY_PART /tmp/recovery
-
+	if [ -b $RECOVERY_PART ]; then
+		insmod nls_cp437
+		insmod nls_iso8859-1
+		insmod fat
+		insmod vfat
+		mkdir -p /tmp/recovery
+		if mount -o rw,noatime $RECOVERY_PART -t vfat /tmp/recovery; then
 			if [ -f "/tmp/recovery/mac_addr" ];
 			then
 				mac=$(cat /tmp/recovery/mac_addr)
@@ -28,17 +24,34 @@ preinit_set_mac_address() {
 
 			sync
 			umount /tmp/recovery
-			rm -rf /tmp/recovery
+			rmdir /tmp/recovery
+
+			ip link set dev wan address $mac 2> /dev/null
+
+			mac=$(macaddr_add $mac 1)
+
+			ip link set dev lan0 address $mac 2>/dev/null
+			ip link set dev lan1 address $mac 2>/dev/null
+			ip link set dev lan2 address $mac 2>/dev/null
+			ip link set dev lan3 address $mac 2>/dev/null
 		fi
+	fi
+}
 
-		ip link set dev wan address $mac 2> /dev/null
+preinit_set_mac_address() {
+	local rootpart
 
-		mac=$(macaddr_add $mac 1)
-
-		ip link set dev lan0 address $mac 2>/dev/null
-		ip link set dev lan1 address $mac 2>/dev/null
-		ip link set dev lan2 address $mac 2>/dev/null
-		ip link set dev lan3 address $mac 2>/dev/null
+	case $(board_name) in
+	bananapi,bpi-r2)
+		rootpart=$(cat /proc/cmdline)
+		rootpart="${rootpart##*root=}"
+		rootpart="${rootpart%%p3 *}"
+		if [ "$rootpart" = "/dev/mmcblk0" -o "$rootpart" = "/dev/mmcblk1" ]; then
+			set_recovery_mac_address ${rootpart}p2
+		fi
+		;;
+	unielec,u7623-02-emmc-512m)
+		set_recovery_mac_address /dev/mmcblk0p1
 		;;
 	esac
 }