arm: add initial support for Amlogic Meson and ODROID-C2

This adds platform code for the Amlogic Meson GXBaby (S905) SoC and a
board definition for ODROID-C2. This initial submission only supports
UART and Ethernet (through the existing Designware driver). DTS files
are the ones submitted to Linux arm-soc for 4.7 [1].

[1] https://patchwork.ozlabs.org/patch/603583/

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/board/hardkernel/odroid-c2/README b/board/hardkernel/odroid-c2/README
new file mode 100644
index 0000000..d6d266a
--- /dev/null
+++ b/board/hardkernel/odroid-c2/README
@@ -0,0 +1,60 @@
+U-Boot for ODROID-C2
+====================
+
+ODROID-C2 is a single board computer manufactured by Hardkernel
+Co. Ltd with the following specifications:
+
+ - Amlogic S905 ARM Cortex-A53 quad-core SoC @ 2GHz
+ - ARM Mali 450 GPU
+ - 2GB DDR3 SDRAM
+ - Gigabit Ethernet
+ - HDMI 2.0 4K/60Hz display
+ - 40-pin GPIO header
+ - 4 x USB 2.0 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
+ - Ethernet
+
+u-boot compilation
+==================
+
+ > export ARCH=arm
+ > export CROSS_COMPILE=aarch64-none-elf-
+ > make odroid-c2_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:
+
+ > DIR=odroid-c2
+ > git clone --depth 1 \
+       https://github.com/hardkernel/u-boot.git -b odroidc2-v2015.01 \
+       $DIR
+ > $DIR/fip/fip_create --bl30  $DIR/fip/gxb/bl30.bin \
+                       --bl301 $DIR/fip/gxb/bl301.bin \
+                       --bl31  $DIR/fip/gxb/bl31.bin \
+                       --bl33  u-boot.bin \
+                       $DIR/fip.bin
+ > $DIR/fip/fip_create --dump $DIR/fip.bin
+ > cat $DIR/fip/gxb/bl2.package $DIR/fip.bin > $DIR/boot_new.bin
+ > $DIR/fip/gxb/aml_encrypt_gxb --bootsig \
+                                --input $DIR/boot_new.bin \
+                                --output $DIR/u-boot.img
+ > dd if=$DIR/u-boot.img of=$DIR/u-boot.gxbb bs=512 skip=96
+
+and then write the image to SD with:
+
+ > DEV=/dev/your_sd_device
+ > BL1=$DIR/sd_fuse/bl1.bin.hardkernel
+ > dd if=$BL1 of=$DEV conv=fsync bs=1 count=442
+ > dd if=$BL1 of=$DEV conv=fsync bs=512 skip=1 seek=1
+ > dd if=$DIR/u-boot.gxbb of=$DEV conv=fsync bs=512 seek=97