ramips: add support for Rostelecom RT-FE-1A

ramips: add support for Rostelecom RT-FE-1A

Rostelecom RT-FE-1A is a wireless WiFi 5 router manufactured by Sercomm
company.

Device specification
--------------------
SoC Type: MediaTek MT7621AT
RAM: 256 MiB
Flash: 128 MiB
Wireless 2.4 GHz (MT7603EN): b/g/n, 2x2
Wireless 5 GHz (MT7615E): a/n/ac, 4x4
Ethernet: 5x GbE (WAN, LAN1, LAN2, LAN3, LAN4)
USB ports: No
Button: 2 buttons (Reset & WPS)
LEDs:
   - 1x Power (green, unmanaged)
   - 1x Status (green, gpio)
   - 1x 2.4G (green, hardware, mt76-phy0)
   - 1x 2.4G (blue, gpio)
   - 1x 5G (green, hardware, mt76-phy1)
   - 1x 5G (blue, gpio)
   - 5x Ethernet (green, hardware, 4x LAN & WAN)
Power: 12 VDC, 1.5 A
Connector type: barrel
Bootloader: U-Boot

Installation
-----------------

1.  Login to the router web interface (default http://192.168.0.1/)
    under "admin" account

2.  Navigate to Settings -> Configuration -> Save to Computer

3.  Decode the configuration. For example, using cfgtool.py tool (see
    related section):
    cfgtool.py -u configurationBackup.cfg

4.  Open configurationBackup.xml and find the following block:

<OBJECT name="User." type="object" writable="1" encryption="0" >
<OBJECT name="1." type="object" writable="1" encryption="0" >
<PARAMETER name="Password" type="string" value="<some value>" writable="1" encryption="1" password="1" />
</OBJECT>

5.  Replace <some value> by a new superadmin password and add a line
    which enabling superadmin login after. For example, the block after
    the changes:

<OBJECT name="User." type="object" writable="1" encryption="0" >
<OBJECT name="1." type="object" writable="1" encryption="0" >
<PARAMETER name="Password" type="string" value="s0meP@ss" writable="1" encryption="1" password="1" />
<PARAMETER name="Enable" type="boolean" value="1" writable="1" encryption="0"/>
</OBJECT>

6.  Encode the configuration. For example, using cfgtool.py tool:
       cfgtool.py -p configurationBackup.xml

7.  Upload the changed configuration (configurationBackup_changed.cfg) to
    the router

8.  Login to the router web interface (superadmin:xxxxxxxxxx, where
    xxxxxxxxxx is a new password from the p.5)

9.  Enable SSH access to the router (Settings -> Access control -> SSH)

10. Connect to the router using SSH shell using superadmin account

11. Run in SSH shell:
    sh

12. Make a mtd backup (optional, see related section)

13. Change bootflag to Sercomm1 and reboot:
    printf 1 | dd bs=1 seek=7 count=1 of=/dev/mtdblock3
    reboot

14. Login to the router web interface under admin account

15. Remove dots from the OpenWrt factory image filename

16. Update firmware via web using OpenWrt factory image

Revert to stock
---------------
Change bootflag to Sercomm1 in OpenWrt CLI and then reboot:
   printf 1 | dd bs=1 seek=7 count=1 of=/dev/mtdblock3

mtd backup
----------
1. Set up a tftp server (e.g. tftpd64 for windows)
2. Connect to a router using SSH shell and run the following commands:
   cd /tmp
   for i in 0 1 2 3 4 5 6 7 8 9; do nanddump -f mtd$i /dev/mtd$i; \
   tftp -l mtd$i -p 192.168.0.2; md5sum mtd$i >> mtd.md5; rm mtd$i; done
   tftp -l mtd.md5 -p 192.168.0.2

MAC Addresses
-------------
+-----+------------+---------+
| use | address    | example |
+-----+------------+---------+
| LAN | label      | f4:*:66 |
| WAN | label + 11 | f4:*:71 |
| 2g  | label + 2  | f4:*:68 |
| 5g  | label + 3  | f4:*:69 |
+-----+------------+---------+
The label MAC address was found in Factory, 0x21000

cfgtool.py
----------
A tool for decoding and encoding Sercomm configs.
Link: https://github.com/r3d5ky/sercomm_cfg_unpacker
Signed-off-by: Mikhail Zhilkin <csharper2005@gmail.com>