ipq40xx: Add support for Teltonika RUTX10

ipq40xx: Add support for Teltonika RUTX10

This patch adds support for the Teltonika RUTX10.
This device is an industrial DIN-rail router with 4 ethernet ports,
2.4G/5G dualband WiFi, Bluetooth, a USB 2.0 port and two GPIOs.

The RUTX series devices are very similiar so common parts of the DTS
are kept in a DTSI file. They are based on the QCA AP-DK01.1-C1 dev
board.

See https://teltonika-networks.com/product/rutx10 for more info.

Hardware:
  SoC:                 Qualcomm IPQ4018
  RAM:                 256MB DDR3
  SPI Flash 1:         XTX XT25F128B (16MB, NOR)
  SPI Flash 2:         XTX XT26G02AWS (256MB, NAND)
  Ethernet:            Built-in IPQ4018 (SoC, QCA8075), 4x 10/100/1000 ports
  WiFi 1:              Qualcomm QCA4019 IEEE 802.11b/g/n
  Wifi 2:              Qualcomm QCA4019 IEEE 802.11a/n/ac
  USB Hub:             Genesys Logic GL852GT
  Bluetooth:           Qualcomm CSR8510 (A10U)
  LED/GPIO controller: STM32F030 with custom firmware
  Buttons:             Reset button
  Leds:                Power (green, cannot be controlled)
                       WiFi 2.4G activity (green)
                       WiFi 5G activity (green)

MACs Details verified with the stock firmware:
   eth0:             Partition 0:CONFIG Offset: 0x0
   eth1:             = eth0 + 1
   radio0 (2.4 GHz): = eth0 + 2
   radio1 (5.0 GHz): = eth0 + 3
Label MAC address is from eth0.

The LED/GPIO controller needs a separate kernel driver to function.
The driver was extracted from the Teltonika GPL sources and can be
found at following feed: https://github.com/0xFelix/teltonika-rutx-openwrt

USB detection of the bluetooth interface is sometimes a bit flaky. When
not detected power cycle the device. When the bluetooth interface was
detected properly it can be used with bluez / bluetoothctl.

Flash instructions via stock web interface (sysupgrade based):
  1. Set PC to fixed ip address 192.168.1.100
  2. Push reset button and power on the device
  3. Open u-boot HTTP recovery at http://192.168.1.1
  4. Upload latest stock firmware and wait until the device is rebooted
  5. Open stock web interface at http://192.168.1.1
  6. Set some password so the web interface is happy
  7. Go to firmware upgrade settings
  8. Choose
     openwrt-ipq40xx-generic-teltonika_rutx10-squashfs-nand-factory.ubi
  9. Set 'Keep settings' to off
  10. Click update, when warned that it is not a signed image proceed

Return to stock firmware:
  1. Set PC to fixed ip address 192.168.1.100
  2. Push reset button and power on the device
  3. Open u-boot HTTP recovery at http://192.168.1.1
  4. Upload latest stock firmware and wait until the device is rebooted

Note: The DTS expects OpenWrt to be running from the second rootfs
partition. u-boot on these devices hot-patches the DTS so running from the
first rootfs partition should also be possible. If you want to be save follow
the instructions above. u-boot HTTP recovery restores the device so that when
flashing OpenWrt from stock firmware it is flashed to the second rootfs
partition and the DTS matches.

Signed-off-by: Felix Matouschek <felix@matouschek.org>