configs/rock_pi_n8: new defconfig

Add initial support for RK3288 SOM based radxa rockpi-n8
target with below features:

- Custom U-Boot 2020.07-rc4
  https://github.com/amarula/u-boot-amarula.git
  commit: "ba120841bf40ebaed049d64bb4f980083a1cf6b7"
- Custom Linux 5.7.0-rc1
  https://github.com/amarula/linux-amarula.git
  commit: "5dcb0132685b07beb82065c5d7521e6c555c55b6"
- GPT partition layout is being used
- Default packages from buildroot

Signed-off-by: Suniel Mahesh <sunil@amarulasolutions.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

board/radxa/rockpi-n8/extlinux.conf

@@ -0,0 +1,4 @@
+label RK3288_ROCKPI_N8 linux
+  kernel /zImage
+  devicetree /rk3288-rock-pi-n8.dtb
+  append console=ttyS2,115200n8 root=/dev/mmcblk0p4 rw rootwait

board/radxa/rockpi-n8/genimage.cfg

@@ -0,0 +1,39 @@
+image boot.vfat {
+	vfat {
+		files = {
+			"zImage",
+			"rk3288-rock-pi-n8.dtb",
+			"extlinux"
+		}
+	}
+	size = 16M
+}
+
+image sdcard.img {
+
+	hdimage {
+		gpt = true
+	}
+
+	partition loader1 {
+		image = "idbloader.img"
+		offset = 32K
+	}
+
+	partition loader2 {
+		image = "u-boot-dtb.img"
+		offset = 8M
+	}
+
+	partition boot {
+		partition-type = 0xC
+		bootable = "true"
+		image = "boot.vfat"
+		offset = 16M
+	}
+
+	partition rootfs {
+		partition-type = 0x83
+		image = "rootfs.ext4"
+	}
+}

board/radxa/rockpi-n8/post-build.sh

@@ -0,0 +1,5 @@
+#!/bin/sh
+
+BOARD_DIR="$(dirname $0)"
+
+install -m 0644 -D $BOARD_DIR/extlinux.conf $BINARIES_DIR/extlinux/extlinux.conf

board/radxa/rockpi-n8/readme.txt

@@ -0,0 +1,61 @@
+RADXA ROCKPI-N8
+================
+https://wiki.radxa.com/RockpiN8
+
+Build:
+======
+  $ make rock_pi_n8_defconfig
+  $ make
+
+Files created in output directory
+=================================
+
+output/images
+.
+├── boot.vfat
+├── extlinux
+├── idbloader.img
+├── rk3288-rock-pi-n8.dtb
+├── rootfs.ext2
+├── rootfs.ext4 -> rootfs.ext2
+├── rootfs.tar
+├── sdcard.img
+├── u-boot.bin
+├── u-boot-dtb.bin
+├── u-boot-dtb.img
+└── zImage
+
+Creating bootable SD card:
+==========================
+
+Simply invoke (as root)
+
+sudo dd if=output/images/sdcard.img of=/dev/sdX && sync
+
+Where X is your SD card device.
+
+Booting:
+========
+
+Serial console:
+---------------
+RockPi-N8 has a 40-pin GPIO header. The pin layout is as follows:
+
+pin 6:  gnd
+pin 8:  tx
+pin 10: rx
+
+Baudrate for this board is 115200.
+
+The boot order on rockpi-n8 is emmc, sd. If emmc contains a valid Image, the board
+always boots from emmc. To boot from SD, erase emmc as per the guide:
+
+https://wiki.amarulasolutions.com/bsp/setup/rockchip/rk3399_emmc.html
+
+Login:
+------
+Enter 'root' as login user, and the prompt is ready.
+
+wiki link:
+----------
+https://wiki.amarulasolutions.com/bsp/rockchip/rk3288/rock-pi-n8.html