configs/nanopc_t4: new defconfig

A defconfig for the friendlyarm nanopc-t4 was added in
c23895f06e, but then removed
in 8efd4463f7 because an ARM32
compiler was needed to build ATF, and this was not supported
back then.

Now, since package/arm-gnu-a-toolchain/ has been added, this
defconfig can be re-introduced.

Following new changes are introduced in comparision with the
older changeset:

	- updated readme
	- GPT partition layout is being used
	- update defconfig to build ATF
	- bump u-boot to 2020.07
	- bump linux to 5.8.2

Signed-off-by: Suniel Mahesh <sunil@amarulasolutions.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
[Arnout: fixate U-Boot version; remove blind BR2_TARGET_UBOOT_NEEDS_PYTHON]

board/friendlyarm/nanopc-t4/extlinux.conf

@@ -0,0 +1,4 @@
+label RK3399_NanoPC_T4 linux
+  kernel /Image
+  devicetree /rk3399-nanopc-t4.dtb
+  append earlycon=uart8250,mmio32,0xff1a0000 root=/dev/mmcblk1p4 rootwait

board/friendlyarm/nanopc-t4/genimage.cfg

@@ -0,0 +1,39 @@
+image boot.vfat {
+        vfat {
+                files = {
+                        "Image",
+                        "rk3399-nanopc-t4.dtb",
+                        "extlinux"
+                }
+        }
+        size = 64M
+}
+
+image sdcard.img {
+
+        hdimage {
+                gpt = true
+        }
+
+        partition loader1 {
+                image = "idbloader.img"
+                offset = 32K
+        }
+
+        partition loader2 {
+                image = "u-boot.itb"
+                offset = 8M
+        }
+
+        partition boot {
+                partition-type = 0xC
+                bootable = "true"
+                image = "boot.vfat"
+                offset = 16M
+        }
+
+        partition rootfs {
+                partition-type = 0x83
+                image = "rootfs.ext4"
+        }
+}

board/friendlyarm/nanopc-t4/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/friendlyarm/nanopc-t4/readme.txt

@@ -0,0 +1,45 @@
+FriendlyARM NANOPC-T4
+=====================
+
+Build:
+
+  $ make nanopc_t4_defconfig
+  $ make
+
+Files created in output directory
+=================================
+
+output/images
+
+├── bl31.elf
+├── boot.vfat
+├── extlinux
+├── idbloader.img
+├── Image
+├── rk3399-nanopc-t4.dtb
+├── rootfs.ext2
+├── rootfs.ext4 -> rootfs.ext2
+├── rootfs.tar
+├── sdcard.img
+├── u-boot.bin
+└── u-boot.itb
+
+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
+
+Serial console
+--------------
+
+Baudrate for this board is 1500000
+
+Login:
+------
+Apply power and press the PWR button for 3 sec. Enter 'root' as login user, and the prompt is ready.
+
+https://wiki.amarulasolutions.com/bsp/rockchip/rk3399/npc_t4.html