mediatek: rework support for BananaPi BPi-R64

**What's new**

 * Bring support for the Bananapi BPi-R64 to the level desirable for
   a nice hackable routerboard.
 * Use ARM Trusted Firmware A from source. (goodbye binary preloader)
 * Use Das U-Boot from source. (see previous commit)
 * Assemble SD-card image using OpenWrt image-commands.
   (no gen_sd_cruz_foo.sh added, this is not Raspbian)
 * Updated kernel options to support root filesystem.
 * Updated DTS to match OpenWrt LAN ports, known LEDs, buttons, ...
 * Detect root device, handle sysupgrade, config restore, ...
 * Wire up (known) LEDs and buttons in OpenWrt-fashion.
 * Build one set of images from SD-card and eMMC.
 * Hopefully provide a good example of how things can be done right
   from scratch.

**Installation and images**

 * Have an empty SD-card at hand
 * Write stuff to the card, as root (card device is /dev/mmcblkX)
   - write header, gpt, bl2, atf, u-boot and recovery kernel:
     `cat *bpi-r64-boot-sdcard.img *bpi-r64-initramfs-recovery.fit > /dev/mmcblkX`
   - rescan partitions:
     `blockdev --rereadpt /dev/mmcblkX`
   - write main system to production partition:
     `cat *bpi-r64-squashfs-sysupgrade.fit > /dev/mmcblkXp5`

 * Installation to eMMC works using SD-card bootloader via TFTP
   When running OpenWrt of SD-card, issue this to trigger installation
   to eMMC:
   `fw_setenv bootcmd run emmc_init`
   Be prepared to serve the content of bin/targets/mediatek/mt7622 on
   TFTP server address 192.168.1.254.

**What's missing**

 * The red LED is always on, probably a hardware bug.
 * AHCI (probably needs DTS changes)
 * Ship SD-card image ready with every needed for eMMC install.
 * The eMMC has a second, currently unused boot partition. This would
   be ideal to store the WiFi EEPROM and Ethernet MAC address(es).
   @sinovoip ideas?

Thanks to Thomas Hühn @thuehn for providing the hardware!

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

target/linux/mediatek/mt7622/base-files/lib/upgrade/platform.sh

@@ -1,15 +1,52 @@
-RAMFS_COPY_BIN='fw_printenv fw_setenv'
+RAMFS_COPY_BIN='fw_printenv fw_setenv blockdev'
 RAMFS_COPY_DATA='/etc/fw_env.config /var/lock/fw_printenv.lock'
 
+get_cmdline_var() {
+	local var=$1
+	local cmdlinevar tmp
+	local cmdline="$(cat /proc/cmdline)"
+
+	for cmdlinevar in $cmdline; do
+		tmp=${cmdlinevar##${var}}
+		[ "=" = "${tmp:0:1}" ] && echo ${tmp:1}
+	done
+}
+
+get_rootdev() {
+	local rootvol rootdev
+	rootvol=$(get_cmdline_var root)
+	rootvol=$(basename $rootvol)
+	[ -e /sys/class/block/$rootvol/partition ] || {
+		echo $rootvol
+		return
+	}
+	rootdev=$(busybox readlink -f /sys/class/block/$rootvol)
+	rootdev=$(basename ${rootdev%%/${rootvol}})
+	[ -e /sys/class/block/$rootdev ] && echo $rootdev
+}
+
+get_partition() {
+	for partname in /sys/class/block/$1/*/name; do
+		[ "$(cat ${partname})" = "$2" ] && {
+			basename ${partname%%/name}
+			break
+		}
+	done
+}
+
 platform_do_upgrade() {
 	local board=$(board_name)
 	local file_type=$(identify $1)
 
 	case "$board" in
-	bananapi,bpi-r64-rootdisk)
-		#2097152=0x200000 is the offset in bytes from the start
-		#of eMMC and to the location of the kernel
-		get_image "$1" | dd of=/dev/mmcblk0 bs=2097152 seek=1 conv=fsync
+	bananapi,bpi-r64)
+		local rootdev=$(get_rootdev)
+		local fitpart=$(get_partition $rootdev production)
+		[ "$fitpart" ] || exit 1
+		dd if=/dev/zero of=/dev/$fitpart bs=4096 count=1 2>/dev/null
+		blockdev --rereadpt /dev/$rootdev
+		get_image "$1" | dd of=/dev/$fitpart
+		echo $rootdev > /tmp/sysupgrade.rootdev
 		;;
 	linksys,e8450-ubi|\
 	mediatek,mt7622,ubi)
@@ -51,18 +88,20 @@ platform_check_image() {
 	return 0
 }
 
-platform_copy_config_emmc() {
-	mkdir -p /recovery
-	mount -o rw,noatime /dev/mmcblk0p6 /recovery
-	cp -af "$UPGRADE_BACKUP" "/recovery/$BACKUP_FILE"
+platform_copy_config_mmc() {
+	local rootdev=$(cat /tmp/sysupgrade.rootdev)
+	blockdev --rereadpt /dev/$rootdev
+	local datadev=$(get_partition $rootdev rootfs_data)
+	[ "$datadev" ] || echo "no rootfs_data partition, cannot keep configuration." >&2
+	dd if="$UPGRADE_BACKUP" of=/dev/$datadev
 	sync
-	umount /recovery
+	sleep 4
 }
 
 platform_copy_config() {
 	case "$(board_name)" in
-	bananapi,bpi-r64-rootdisk)
-		platform_copy_config_emmc
+	bananapi,bpi-r64)
+		platform_copy_config_mmc
 		;;
 	esac
 }