qualcommax: ipq50xx: add support for Xiaomi Redmi AX5400

qualcommax: ipq50xx: add support for Xiaomi Redmi AX5400

Add support for Xiaomi AX5400 (RA74).

Specifications:
* SoC: Qualcomm IPQ5018 (64-bit dual-core ARM Cortex-A53 @ 1.0Ghz)
* Memory: Etrontech EM6HE16EWAKG 512 MiB DDR3L-933
* Serial Port: 1v8 TTL 115200n8
* Wi-Fi: IPQ5018 (2x2 2.4 Ghz 802.11b/g/n/ax - up to 574 Mbps)
	 QCN9024 (4x4 5 Ghz 802.11an/ac/ax - up to 4804 Mbps)
* Ethernet: IPQ5018 integrated virtual switch connected to an
	    external QCA8337 switch   (3 LAN Ports 10/100/1000)
* Flash: Gigadevice GD5F1GQ5REYIG (128 MiB)
* LEDs: 1x System Blue   (GPIO 24 Active High)
	1x System Yellow (GPIO 25 Active High)
	1x WAN Link Blue (GPIO 26 Active High)
	1x WAN Link Yellow   (GPIO 27 Active High)
* Buttons: 1x Reset  (GPIO 38 Active Low)
	   1x WPS    (GPIO 28 Active Low)
* MAC address layout: LAN (eth1): 0:art @ offset 0x0
		      WAN (eth0): 0:art @ offset 0x6

Flash instructions: (use redmi-ax5400 image for the Redmi AX5400)

Download XMIR Patcher: https://github.com/openwrt-xiaomi/xmir-patcher

First flash a ubinized OpenWrt initramfs that will serve as the intermediate step, since
OpenWrt uses unified rootfs in order to fully utilize NAND and provide enough space for
packages, through either of the below two methods:

Installation via XMIR Patcher:

1. Load the initramfs image: openwrt-qualcommax-ipq50xx-xiaomi_redmi-ax5400-initramfs-factory.ubi

Installation via ubiformat method, through SSH:

1. If needed, enable SSH using XMIR Patcher.
2. Copy the file openwrt-qualcommax-ipq50xx-xiaomi_redmi-ax5400-initramfs-factory.ubi to the /tmp directory
3. Open an SSH shell to the router
4. Check which rootfs partition is your router booted in (0 = rootfs | 1 = rootfs_1):
nvram get flag_boot_rootfs
5. Find the rootfs and rootfs_1 mtd indexes respectively:
cat /proc/mtd
Please confirm if mtd18 and mtd19 are the correct indexes from above!
6. Use the command ubiformat to flash the opposite mtd with UBI image:
If nvram get flag_boot_rootfs returned 0:
ubiformat /dev/mtd19 -y -f /tmp/openwrt-qualcommax-ipq50xx-xiaomi_redmi-ax5400-initramfs-factory.ubi && nvram set flag_boot_rootfs=1 && nvram set flag_last_success=1 && nvram commit
otherwise:
ubiformat /dev/mtd18 -y -f /tmp/openwrt-qualcommax-ipq50xx-xiaomi_redmi-ax5400-initramfs-factory.ubi && nvram set flag_boot_rootfs=0 && nvram set flag_last_success=0 && nvram commit
7. Reboot the device by:
reboot

Continue in order to pernamently flash OpenWrt:
1. Upload the sysupgrade image to /tmp/ using SCP:
scp -O <path to image> root@192.168.1.1:/tmp/
2. Open an SSH shell to 192.168.1.1 from a PC within the same subnet
3. Use sysupgrade to flash the sysupgrade image:
sysupgrade -n -v /tmp/openwrt-qualcommax-ipq50xx-xiaomi_redmi-ax5400-squashfs-sysupgrade.bin

Device will reboot with OpenWrt, and then sysupgrade can be used to upgrade the device when desired.

Signed-off-by: George Moussalem <george.moussalem@outlook.com>
Link: https://github.com/openwrt/openwrt/pull/23374
Signed-off-by: Robert Marko <robimarko@gmail.com>