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/lib/upgrade/platform.sh

@@ -0,0 +1,50 @@
+#
+# Copyright (C) 2010 OpenWrt.org
+#
+
+PART_NAME=firmware
+REQUIRE_IMAGE_METADATA=1
+
+platform_check_image() {
+	return 0
+}
+
+platform_do_upgrade() {
+	local board=$(board_name)
+
+	case "$board" in
+	mikrotik,rb750gr3|\
+	mikrotik,rbm11g|\
+	mikrotik,rbm33g)
+		[ -z "$(rootfs_type)" ] && mtd erase firmware
+		;;
+	asus,rt-ac65p|\
+	asus,rt-ac85p)
+		echo "Backing up firmware"
+		dd if=/dev/mtd4 bs=1024 count=4096  > /tmp/backup_firmware.bin
+		dd if=/dev/mtd5 bs=1024 count=52224 >> /tmp/backup_firmware.bin
+		mtd -e firmware2 write /tmp/backup_firmware.bin firmware2
+		;;
+	esac
+
+	case "$board" in
+	asus,rt-ac65p|\
+	asus,rt-ac85p|\
+	hiwifi,hc5962|\
+	netgear,r6220|\
+	netgear,r6260|\
+	netgear,r6350|\
+	netgear,r6850|\
+	xiaomi,mir3g|\
+	xiaomi,mir3p)
+		nand_do_upgrade "$1"
+		;;
+	ubiquiti,edgerouterx|\
+	ubiquiti,edgerouterx-sfp)
+		platform_upgrade_ubnt_erx "$1"
+		;;
+	*)
+		default_do_upgrade "$1"
+		;;
+	esac
+}

target/linux/ramips/mt7621/base-files/lib/upgrade/ubnt.sh

@@ -0,0 +1,78 @@
+#
+# Copyright (C) 2015 OpenWrt.org
+#
+
+. /lib/functions.sh
+#Note: this code also uses some functions from nand.sh, but it is expected to be run by nand.sh, so we are not
+#sourcing it explicitly here
+
+UBNT_ERX_KERNEL_INDEX_OFFSET=160
+
+ubnt_get_target_kernel() {
+	local factory_mtd=$1
+	local current_kernel_index=$(hexdump -s $UBNT_ERX_KERNEL_INDEX_OFFSET -n 1 -e '/1 "%X "' ${factory_mtd})
+
+	if [ $current_kernel_index == "0" ]; then
+		echo 'kernel2'
+	elif [ $current_kernel_index == "1" ]; then
+		echo 'kernel1'
+	fi
+}
+
+ubnt_update_target_kernel() {
+	local factory_mtd=$1
+	local kernel_part=$2
+
+	local new_kernel_index
+	if [ $kernel_part == "kernel1" ]; then
+		new_kernel_index="\x00"
+	elif [ $kernel_part == "kernel2" ]; then
+		new_kernel_index="\x01"
+	else
+		echo 'Unknown kernel image index' >&2
+		return 1
+	fi
+
+	if ! (echo -e $new_kernel_index | dd of=${factory_mtd} bs=1 count=1 seek=$UBNT_ERX_KERNEL_INDEX_OFFSET); then
+		echo 'Failed to update kernel bootup index' >&2
+		return 1
+	fi
+}
+
+platform_upgrade_ubnt_erx() {
+	local factory_mtd=$(find_mtd_part factory)
+	if [ -z "$factory_mtd" ]; then
+		echo "cannot find factory partition" >&2
+		exit 1
+	fi
+
+	local kernel_part="$(ubnt_get_target_kernel ${factory_mtd})"
+	if [ -z "$kernel_part" ]; then
+		echo "cannot find factory partition" >&2
+		exit 1
+	fi
+
+	# This is a global defined in nand.sh, sets partition kernel will be flashed into
+	CI_KERNPART=${kernel_part}
+
+	#Remove volume possibly left over from stock firmware
+	local ubidev="$( nand_find_ubi "$CI_UBIPART" )"
+	if [ -z "$ubidev" ]; then
+		local mtdnum="$( find_mtd_index "$CI_UBIPART" )"
+		if [ -z "$mtdnum" ]; then
+			echo "cannot find ubi mtd partition $CI_UBIPART" >&2
+			exit 1
+		fi
+		ubiattach -m "$mtdnum"
+		sync
+		ubidev="$( nand_find_ubi "$CI_UBIPART" )"
+	fi
+	if [ -n "$ubidev" ]; then
+		local troot_ubivol="$( nand_find_volume $ubidev troot )"
+		[ -n "$troot_ubivol" ] && ubirmvol /dev/$ubidev -N troot || true
+	fi
+
+	ubnt_update_target_kernel ${factory_mtd} ${kernel_part} || exit 1
+
+	nand_do_upgrade "$1"
+}