ipq806x: add support for Buffalo WXR-2533DHP

Buffalo WXR-2533DHP is a 2.4/5 GHz band 11ac router, based on Qualcomm
IPQ8064.

The U-Boot on WXR-2533DHP employs a complicated dual firmware
protection scheme against corruptions of the kernel and rootfs
images. See the notes in buffalo.sh for details.

specifications:

- Qualcomm IPQ8064 (384 - 1,400 MHz, 2C2T)
- 512 MB of RAM (DDR3)
- 256 MB of Flash (NAND)
- 4T4R 2.4/5 GHz Wlan (QCA9980)
- 5x 10/100/1000 Mbps Ethernet
- 10x LEDs, 8x keys (6x buttons, 2x slide-switches)
- 2x USB 3.0 Type-A
- 12VDC/4A AC Adapter
- UART through-hole on PCB
  - J3: Vcc, GND, TX, RX from USB port side
  - 115200n8

Boot instructions for the initramfs image:

1. Prepare the TFTP server with the initramfs image renamed to
   "wxr2300dhp-initramfs.uImage" and IP address "192.168.11.10".
2. Press the "AOSS" button while powering on the WXR-2533DHP.
3. Wait until the "Wireless" LED flashes before releasing the AOSS button.
   The WXR-2533DHP will grab the image from TFTP server and will boot it.

Flashing instructions:

To persistently write the firmware, flash an openwrt sysupgrade image
from inside the initramfs, for example transfer
via `scp <sysupgrade> root@192.168.1.1:/tmp` and flash on the device
with `sysupgrade -n /tmp/<sysupgrade>`. Then wait ~120 seconds to
let it finish the flashing process.

Signed-off-by: INAGAKI Hiroshi <musashino.open@gmail.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com> [reworded message]

2 files changed, 50 insertions, 0 deletions

diff --git a/target/linux/ipq806x/base-files/lib/upgrade/buffalo.sh b/target/linux/ipq806x/base-files/lib/upgrade/buffalo.sh
new file mode 100644
index 0000000000..77fa65e60e
--- /dev/null
+++ b/target/linux/ipq806x/base-files/lib/upgrade/buffalo.sh
@@ -0,0 +1,45 @@
+#!/bin/sh
+# Copyright (C) 2018 OpenWrt.org
+#
+
+. /lib/functions.sh
+
+# The mtd partition 'ubi' and 'rootfs_1' on NAND flash are os-image
+# partitions. These partitions are called as "Bank1/Bank2" in U-Boot
+# on WXR-2533DHP, and they are checked conditions when booting.
+# Then, U-Boot checks kernel and rootfs volumes in ubi, but U-Boot
+# needs "ubi_rootfs" as rootfs volume name. And, U-Boot checks the
+# checksum at the end of rootfs (ubi_rootfs).
+# When U-Boot writes os-image into the Bank, only kernel, rootfs
+# (ubi_rootfs) and rootfs_data (ubi_rootfs_data) volumes are wrote
+# into the Bank. (not full ubi image)
+#
+# == U-Boot Behaviors ==
+# - Bank1/Bank2 images are good, images are different
+#   -> writes os-image to Bank1 from Bank2
+#      (this behavior is used to firmware upgrade in stock firmware)
+# - Bank1 image is broken (or checksum error)
+#   -> writes os-image to Bank1 from Bank2
+# - Bank2 image is broken (or checksum error)
+#   -> writes os-image to Bank2 from Bank1
+# - Bank1/Bank2 images are broken (or checksum error)
+#   -> start tftp
+
+buffalo_upgrade_prepare_ubi() {
+	local ubidev="$( nand_find_ubi ubi )"
+	local mtdnum2="$( find_mtd_index rootfs_1 )"
+
+	if [ ! "$mtdnum2" ]; then
+		echo "cannot find second ubi mtd partition rootfs_1"
+		return 1
+	fi
+
+	local ubidev2="$( nand_find_ubi rootfs_1 )"
+	if [ ! "$ubidev2" ] && [ -n "$mtdnum2" ]; then
+		ubiattach -m "$mtdnum2"
+		ubidev2="$( nand_find_ubi rootfs_1 )"
+	fi
+
+	ubirmvol /dev/$ubidev -N ubi_rootfs_data &> /dev/null || true
+	ubirmvol /dev/$ubidev2 -N kernel &> /dev/null || true
+}
diff --git a/target/linux/ipq806x/base-files/lib/upgrade/platform.sh b/target/linux/ipq806x/base-files/lib/upgrade/platform.sh
index 4b88f9cf5e..2f0190629e 100644
--- a/target/linux/ipq806x/base-files/lib/upgrade/platform.sh
+++ b/target/linux/ipq806x/base-files/lib/upgrade/platform.sh
@@ -10,6 +10,11 @@ platform_check_image() {
 
 platform_do_upgrade() {
 	case "$(board_name)" in
+	buffalo,wxr-2533dhp)
+		buffalo_upgrade_prepare_ubi
+		CI_ROOTPART="ubi_rootfs"
+		nand_do_upgrade "$ARGV"
+		;;
 	compex,wpq864|\
 	netgear,d7800 |\
 	netgear,r7500 |\