kirkwood: add ZyXEL NSA310b

kirkwood: add ZyXEL NSA310b

The ZyXEL NSA310 device is a Kirkwood based NAS:

- SoC: Marvell 88F6702 1200Mhz
- SDRAM memory: 256MB DDR2 400Mhz
- Gigabit ethernet: Realtek (over pcie)
- Flash memory: 128MB
- 1 Power button
- 1 Power LED (blue)
- 5 Status LED (green/red)
- 1 Copy/Sync button
- 1 Reset button
- 2 SATA II port (1 internal and 1 external)
- 2 USB 2.0 ports (1 front and 1 back)
- Smart fan

The stock u-boot cannot read ubi so it should be replaced with the
LEDE/OpenWRT's u-boot or with a u-boot from here
https://github.com/mibodhi/u-boot-kirkwood

This device's boot ROM supports "kwboot" tool
(in mainline u-boot, built automatically if CONFIG_KIRKWOOD is declared)
that sends an uboot image to the board over serial connection, it is very easy to unbrick.

The stock bootloader can use usb and read from FAT filesystems,
so the installation process is simple, place the uboot file on a USB flashdrive
formatted as FAT (here it is "openwrt-kirkwood-nsa310.bin", then connect TTL
to the board and write the following commands in the bootloader console:

usb reset
fatload usb 0 0x1000000 openwrt-kirkwood-nsa310.bin
nand write 0x1000000 0x00000 0x100000
reset

Now you are rebooting in the new u-boot, write this in its console to install the firmware:

usb reset
fatload usb 0 0x2000000 lede-kirkwood-nsa310b-squashfs-factory.bin
nand erase.part ubi
nand write 0x2000000 ubi 0x600000

If your firmware file is bigger than 6 MiBs you should write its size in hex
instead of 0x600000 above, or remove that number entirely (it will take a while in this case).

If you are using another uboot that can read ubi, set mtdparts like this

mtdparts=mtdparts=orion_nand:0x00c0000(uboot),0x80000(uboot_env),0x7ec0000(ubi)

And set your bootcmd to be like this

bootcmd=run setenv bootargs; ubi part ubi; ubi read 0x800000 kernel; bootm 0x800000

Then you can install the firmware as described above.

After you installed (or configured) the u-boot for booting the firmware,
write the device's mac address in the ethaddr u-boot env.
The MAC address is usually on a sticker under the device (one of the two codes is the serial),
it should begin with "107BEF" as it is assigned to ZyXEL.

write in the u-boot console (use your MAC address instead of the example)

setenv ethaddr 10:7B:EF:00:00:00
saveenv

to save the mac address in the u-boot.

Signed-off-by: Alberto Bursi <alberto.bursi@outlook.it>