ramips: split base-files into subtargets

While most of the target's contents are split into subtargets, the
base-files are maintained for the target as a whole.

However, OpenWrt already implements a mechanism that will use (and
even prefer) files in the subtargets' directories. This can be
exploited to make several scripts subtarget-specific and thus save
some space.

In certain cases, keeping files in parent (=target) base-files was
more convenient, and thus no splitting was performed for those.

Note that this will increase overall code lines, but reduce code
per subtarget.

base-files ipk size reduction:
master (mt7621)   60958 B
split (mt7620)    46358 B (- 14.3 kiB)
split (mt7621)    48759 B (- 11.9 kiB)
split (mt76x8)    44948 B (- 15.6 kiB)
split (rt288x)    43508 B (- 17.0 kiB)
split (rt305x)    45616 B (- 15.0 kiB)
split (rt3883)    44176 B (- 16.4 kiB)

Run-tested on:
GL.iNet GL-MT300N-V2 (mt76x8)
D-Link DWR-116 (mt7620)

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

target/linux/ramips/mt7621/base-files/sbin/fixup-mac-address

@@ -0,0 +1,80 @@
+#!/bin/sh
+. /lib/functions.sh
+. /lib/functions/system.sh
+
+partname=""
+offset=""
+NEW_MAC=
+YES=
+
+board=$(board_name)
+case $board in
+	mqmaker,witi)
+		partname=factory
+		offset=$((0xe000))
+	;;
+	*)
+		echo "Unsupported board"
+		exit 1
+	;;
+esac
+
+while [ -n "$1" ]; do
+	case "$1" in
+		??:??:??:??:??:??) NEW_MAC="$1";;
+		-y) YES=1;;
+		*)
+			cat <<EOF
+Unknown option/argument '$1'
+Usage: $0 [-y] [<macaddr>]
+EOF
+			exit 1
+		;;
+	esac
+	shift
+done
+
+ask_bool() {
+	local message="$1"
+	local default="$((! ${2:-0}))"
+	[ -n "$YES" ] && return 0
+	echo -n "$message "
+	read opt
+	case "$opt" in
+		y|Y) return 0;;
+		n|N) return 1;;
+		*) return $default;;
+	esac
+}
+
+convert_hex() {
+	hexdump -e '/1 "%02x "'
+}
+
+gen_mac() {
+	dd if=/dev/urandom bs=6 count=1 2>/dev/null
+}
+
+mac="$(mtd_get_mac_binary $partname $offset)"
+case "$mac" in
+	00:00:00:00:00:00);;
+	ff:ff:ff:ff:ff:ff);;
+	*)
+		echo "Current MAC address: $mac"
+		ask_bool "Overwrite (y/N)?" 0 || exit
+	;;
+esac
+
+if [ -n "$NEW_MAC" ]; then
+	set -- $(echo "$NEW_MAC" | sed 's,:, ,g')
+else
+	set -- $(gen_mac | convert_hex)
+	set -- $(printf %02x $(( (0x$1 & 0xfe) | 0x02 ))) $2 $3 $4 $5 $6
+fi
+echo "New MAC address: $1:$2:$3:$4:$5:$6"
+ask_bool "Write to EEPROM (y/N)?" || exit
+
+part=$(find_mtd_part "$partname")
+[ -n "$part" ] || exit
+echo -ne "\x$1\x$2\x$3\x$4\x$5\x$6" | dd of=$part conv=notrunc bs=1 count=6 seek=$offset 2>/dev/null
+echo "Done"