board: amlogic: add support for Odroid-N2

ODROID-N2 is a single board computer manufactured by Hardkernel Co. Ltd
with the following specifications:

 - Amlogic S922X ARM Cortex-A53 dual-core + Cortex-A73 quad-core SoC
 - 4GB DDR4 SDRAM
 - Gigabit Ethernet
 - HDMI 2.1 4K/60Hz display
 - 40-pin GPIO header
 - 4 x USB 3.0 Host, 1 x USB OTG
 - eMMC, microSD
 - Infrared receiver

The board directory is W400, the name of the Amlogic Reference Design
of Amlogic G12B with Gigabit boards, which will be used for similar
boards.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Mark Kettenis <kettenis@openbsd.org>
diff --git a/board/amlogic/w400/README.odroid-n2 b/board/amlogic/w400/README.odroid-n2
new file mode 100644
index 0000000..a8f2c3d
--- /dev/null
+++ b/board/amlogic/w400/README.odroid-n2
@@ -0,0 +1,130 @@
+U-Boot for ODROID-N2
+====================
+
+ODROID-N2 is a single board computer manufactured by Hardkernel
+Co. Ltd with the following specifications:
+
+ - Amlogic S922X ARM Cortex-A53 dual-core + Cortex-A73 quad-core SoC
+ - 4GB DDR4 SDRAM
+ - Gigabit Ethernet
+ - HDMI 2.1 4K/60Hz display
+ - 40-pin GPIO header
+ - 4 x USB 3.0 Host, 1 x USB OTG
+ - eMMC, microSD
+ - Infrared receiver
+
+Schematics are available on the manufacturer website.
+
+Currently the u-boot port supports the following devices:
+ - serial
+ - eMMC, microSD
+ - Ethernet
+ - I2C
+ - Regulators
+ - Reset controller
+ - Clock controller
+ - ADC
+
+u-boot compilation
+==================
+
+ > export ARCH=arm
+ > export CROSS_COMPILE=aarch64-none-elf-
+ > make odroid-n2_defconfig
+ > make
+
+Image creation
+==============
+
+Amlogic doesn't provide sources for the firmware and for tools needed
+to create the bootloader image, so it is necessary to obtain them from
+the git tree published by the board vendor:
+
+ > wget https://releases.linaro.org/archive/13.11/components/toolchain/binaries/gcc-linaro-aarch64-none-elf-4.8-2013.11_linux.tar.xz
+ > wget https://releases.linaro.org/archive/13.11/components/toolchain/binaries/gcc-linaro-arm-none-eabi-4.8-2013.11_linux.tar.xz
+ > tar xvfJ gcc-linaro-aarch64-none-elf-4.8-2013.11_linux.tar.xz
+ > tar xvfJ gcc-linaro-arm-none-eabi-4.8-2013.11_linux.tar.xz
+ > export PATH=$PWD/gcc-linaro-aarch64-none-elf-4.8-2013.11_linux/bin:$PWD/gcc-linaro-arm-none-eabi-4.8-2013.11_linux/bin:$PATH
+
+ > DIR=odroid-n2
+ > git clone --depth 1 \
+       https://github.com/hardkernel/u-boot.git -b odroidn2-v2015.01 \
+       $DIR
+
+ > cd odroid-n2
+ > make odroidn2_defconfig
+ > make
+ > export UBOOTDIR=$PWD
+
+ Go back to mainline U-Boot source tree then :
+ > mkdir fip
+
+ > wget https://github.com/BayLibre/u-boot/releases/download/v2017.11-libretech-cc/blx_fix_g12a.sh -O fip/blx_fix.sh
+ > cp $UBOOTDIR/build/scp_task/bl301.bin fip/
+ > cp $UBOOTDIR/build/board/hardkernel/odroidn2/firmware/acs.bin fip/
+ > cp $UBOOTDIR/fip/g12b/bl2.bin fip/
+ > cp $UBOOTDIR/fip/g12b/bl30.bin fip/
+ > cp $UBOOTDIR/fip/g12b/bl31.img fip/
+ > cp $UBOOTDIR/fip/g12b/ddr3_1d.fw fip/
+ > cp $UBOOTDIR/fip/g12b/ddr4_1d.fw fip/
+ > cp $UBOOTDIR/fip/g12b/ddr4_2d.fw fip/
+ > cp $UBOOTDIR/fip/g12b/diag_lpddr4.fw fip/
+ > cp $UBOOTDIR/fip/g12b/lpddr4_1d.fw fip/
+ > cp $UBOOTDIR/fip/g12b/lpddr4_2d.fw fip/
+ > cp $UBOOTDIR/fip/g12b/piei.fw fip/
+ > cp $UBOOTDIR/fip/g12b/aml_ddr.fw fip/
+ > cp u-boot.bin fip/bl33.bin
+
+ > sh fip/blx_fix.sh \
+	fip/bl30.bin \
+	fip/zero_tmp \
+	fip/bl30_zero.bin \
+	fip/bl301.bin \
+	fip/bl301_zero.bin \
+	fip/bl30_new.bin \
+	bl30
+
+ > sh fip/blx_fix.sh \
+	fip/bl2.bin \
+	fip/zero_tmp \
+	fip/bl2_zero.bin \
+	fip/acs.bin \
+	fip/bl21_zero.bin \
+	fip/bl2_new.bin \
+	bl2
+
+ > $UBOOTDIR/fip/g12b/aml_encrypt_g12b --bl30sig --input fip/bl30_new.bin \
+					--output fip/bl30_new.bin.g12a.enc \
+					--level v3
+ > $UBOOTDIR/fip/g12b/aml_encrypt_g12b --bl3sig --input fip/bl30_new.bin.g12a.enc \
+					--output fip/bl30_new.bin.enc \
+					--level v3 --type bl30
+ > $UBOOTDIR/fip/g12b/aml_encrypt_g12b --bl3sig --input fip/bl31.img \
+					--output fip/bl31.img.enc \
+					--level v3 --type bl31
+ > $UBOOTDIR/fip/g12b/aml_encrypt_g12b --bl3sig --input fip/bl33.bin --compress lz4 \
+					--output fip/bl33.bin.enc \
+					--level v3 --type bl33 --compress lz4
+ > $UBOOTDIR/fip/g12b/aml_encrypt_g12b --bl2sig --input fip/bl2_new.bin \
+					--output fip/bl2.n.bin.sig
+ > $UBOOTDIR/fip/g12b/aml_encrypt_g12b --bootmk \
+		--output fip/u-boot.bin \
+		--bl2 fip/bl2.n.bin.sig \
+		--bl30 fip/bl30_new.bin.enc \
+		--bl31 fip/bl31.img.enc \
+		--bl33 fip/bl33.bin.enc \
+		--ddrfw1 fip/ddr4_1d.fw \
+		--ddrfw2 fip/ddr4_2d.fw \
+		--ddrfw3 fip/ddr3_1d.fw \
+		--ddrfw4 fip/piei.fw \
+		--ddrfw5 fip/lpddr4_1d.fw \
+		--ddrfw6 fip/lpddr4_2d.fw \
+		--ddrfw7 fip/diag_lpddr4.fw \
+		--ddrfw8 fip/aml_ddr.fw \
+		--level v3
+
+and then write the image to SD with:
+
+ > DEV=/dev/your_sd_device
+ > dd if=fip/u-boot.bin.sd.bin of=$DEV conv=fsync,notrunc bs=512 skip=1 seek=1
+ > dd if=fip/u-boot.bin.sd.bin of=$DEV conv=fsync,notrunc bs=1 count=444