mediatek: add build for MT7981 RFB
Add build for the MTK3943 reference board for MT7981B+MT7976C.
**Hardware specification:**
- SoC: MediaTek MT7981B 2x A53
- Flash: various options
- RAM: 256MB DDR3
- Ethernet: 4 x 10/100/1000 Mbps via MT7531AE switch
EITHER 1 x 10/100/1000 Mbps built-in PHY
OR 1 x 10/100/1000/2500 Mbps MaxLinear GPY211C
- Switch: MediaTek MT7531AE
- WiFi: MediaTek MT7976C
- Button: RST, WPS
**Flash instructions for SPIM-NAND:**
- write *mt7981-rfb-spim-nand-preloader.bin to 'BL2' partition
- write *mt7981-rfb-spim-nand-bl31-uboot.fip to 'FIP' partition
- erase 'ubi' partition
- reset board
- create ubootenv and ubootenv2 UBI volumes in U-Boot
- edit environment and set bootcmd, e.g.
setenv bootconf 'config-1#mt7981-rfb-spim-nand#mt7981-rfb-mxl-2p5g-phy-eth1'
setenv bootcmd 'ubi read $loadaddr fit; bootm $loadaddr#$bootconf'
- load initramfs image via TFTP:
setenv serverip 192.168.1.254
setenv ipaddr 192.168.1.1
setenv bootfile openwrt-mediatek-filogic-mediatek_mt7981-rfb-initramfs.itb
saveenv ; saveenv
tftpboot
bootm $loadaddr#$bootconf
- Now use sysupgrade to write OpenWrt firmware to flash.
SNFI-NAND, SPIM-NOR and eMMC all work very similar, a bootable SD card image
is also being generated. However, as the board I've been provided only comes
with SPIM-NAND all other boot media are untested.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
(cherry picked from commit
ce7209bd21661e3daa4a7f2f58dafdff990da19f)