Allwinner 64-bit boards README
  ==============================
  
  Newer Allwinner SoCs feature ARMv8 cores (ARM Cortex-A53) with support for
  both the 64-bit AArch64 mode and the ARMv7 compatible 32-bit AArch32 mode.
  Examples are the Allwinner A64 (used for instance on the Pine64 board) or
  the Allwinner H5 SoC (as used on the OrangePi PC 2).
  These SoCs are wired to start in AArch32 mode on reset and execute 32-bit
  code from the Boot ROM (BROM). As this has some implications on U-Boot, this
  file describes how to make full use of the 64-bit capabilities.
  
  Quick Start / Overview
  ======================
  - Build the ARM Trusted Firmware binary (see "ARM Trusted Firmware (ATF)" below)
  - Build U-Boot (see "SPL/U-Boot" below)
  - Transfer to an uSD card (see "microSD card" below)
  - Boot and enjoy!
  
  Building the firmware
  =====================
  
  The Allwinner A64/H5 firmware consists of three parts: U-Boot's SPL, an
  ARM Trusted Firmware (ATF) build and the U-Boot proper.
  The SPL will load both ATF and U-Boot proper along with the right device
  tree blob (.dtb) and will pass execution to ATF (in EL3), which in turn will
  drop into the U-Boot proper (in EL2).
  As the ATF binary will become part of the U-Boot image file, you will need
  to build it first.
  
   ARM Trusted Firmware (ATF)
  ----------------------------
  Checkout the "allwinner" branch from the github repository [1] and build it:
  $ export CROSS_COMPILE=aarch64-linux-gnu-
  $ make PLAT=sun50iw1p1 DEBUG=1 bl31
  The resulting binary is build/sun50iw1p1/debug/bl31.bin. Either put the
  location of this file into the BL31 environment variable or copy this to
  the root of your U-Boot build directory (or create a symbolic link).
  $ export BL31=/src/arm-trusted-firmware/build/sun50iw1p1/debug/bl31.bin
    (adjust the actual path accordingly)
  
   SPL/U-Boot
  ------------
  Both U-Boot proper and the SPL are using the 64-bit mode. As the boot ROM
  enters the SPL still in AArch32 secure SVC mode, there is some shim code to
  enter AArch64 very early. The rest of the SPL runs in AArch64 EL3.
  U-Boot proper runs in EL2 and can load any AArch64 code (using the "go"
  command), EFI applications (with "bootefi") or arm64 Linux kernel images
  (often named "Image"), using the "booti" command.
  
  $ make clean
  $ export CROSS_COMPILE=aarch64-linux-gnu-
  $ make pine64_plus_defconfig
  $ make
  
  This will build the SPL in spl/sunxi-spl.bin and a FIT image called u-boot.itb,
  which contains the rest of the firmware.
  
  
  Boot process
  ============
  The on-die BROM code will try several methods to load and execute the firmware.
  On a typical board like the Pine64 this will result in the following boot order:
  
  1) Reading 32KB from sector 16 (@8K) of the microSD card to SRAM A1. If the
  BROM finds the magic "eGON" header in the first bytes, it will execute that
  code. If not (no SD card at all or invalid magic), it will:
  2) Try to read 32KB from sector 16 (@8K) of memory connected to the MMC2
  controller, typically an on-board eMMC chip. If there is no eMMC or it does
  not contain a valid boot header, it will:
  3) Initialize the SPI0 controller and try to access a NOR flash connected to
  it (using the CS0 pin). If a flash chip is found, the BROM will load the
  first 32KB (from offset 0) into SRAM A1. Now it checks for the magic eGON
  header and checksum and will execute the code upon finding it. If not, it will:
  4) Initialize the USB OTG controller and will wait for a host to connect to
  it, speaking the Allwinner proprietary (but deciphered) "FEL" USB protocol.
  
  
  To boot the Pine64 board, you can use U-Boot and any of the described methods.
  
  FEL boot (USB OTG)
  ------------------
  FEL is the name of the Allwinner defined USB boot protocol built in the
  mask ROM of most Allwinner SoCs. It allows to bootstrap a board solely
  by using the USB-OTG interface and a host port on another computer.
  As the FEL mode is controlled by the boot ROM, it expects to be running in
  AArch32. For now the AArch64 SPL cannot properly return into FEL mode, so the
  feature is disabled in the configuration at the moment.
  
  microSD card
  ------------
  Transfer the SPL and the U-Boot FIT image directly to an uSD card:
  # dd if=spl/sunxi-spl.bin of=/dev/sdx bs=8k seek=1
  # dd if=u-boot.itb of=/dev/sdx bs=8k seek=5
  # sync
  (replace /dev/sdx with you SD card device file name, which could be
  /dev/mmcblk[x] as well).
  
  Alternatively you can concatenate the SPL and the U-Boot FIT image into a
  single file and transfer that instead:
  $ cat spl/sunxi-spl.bin u-boot.itb > u-boot-sunxi-with-spl.bin
  # dd if=u-boot-sunxi-with-spl.bin of=/dev/sdx bs=8k seek=1
  
  You can partition the microSD card, but leave the first MB unallocated (most
  partitioning tools will do this anyway).
  
  NOR flash
  ---------
  Some boards (like the SoPine, Pinebook or the OrangePi PC2) come with a
  soldered SPI NOR flash chip. On other boards like the Pine64 such a chip
  can be connected to the SPI0/CS0 pins on the PI-2 headers.
  Create the SPL and FIT image like described above for the SD card.
  Now connect either an "A to A" USB cable to the upper USB port on the Pine64
  or get an adaptor and use a regular A-microB cable connected to it. Other
  boards often have a proper micro-B USB socket connected to the USB OTB port.
  Remove a microSD card from the slot and power on the board.
  On your host computer download and build the sunxi-tools package[2], then
  use "sunxi-fel" to access the board:
  $ ./sunxi-fel ver -v -p
  This should give you an output starting with: AWUSBFEX soc=00001689(A64) ...
  Now use the sunxi-fel tool to write to the NOR flash:
  $ ./sunxi-fel spiflash-write 0 spl/sunxi-spl.bin
  $ ./sunxi-fel spiflash-write 32768 u-boot.itb
  Now boot the board without an SD card inserted and you should see the
  U-Boot prompt on the serial console.
  
  (Legacy) boot0 method
  ---------------------
  boot0 is Allwiner's secondary program loader and it can be used as some kind
  of SPL replacement to get U-Boot up and running from an microSD card.
  For some time using boot0 was the only option to get the Pine64 booted.
  With working DRAM init code in U-Boot's SPL this is no longer necessary,
  but this method is described here for the sake of completeness.
  Please note that this method works only with the boot0 files shipped with
  A64 based boards, the H5 uses an incompatible layout which is not supported
  by this method.
  
  The boot0 binary is a 32 KByte blob and contained in the official Pine64 images
  distributed by Pine64 or Allwinner. It can be easily extracted from a micro
  SD card or an image file:
  # dd if=/dev/sd<x> of=boot0.bin bs=8k skip=1 count=4
  where /dev/sd<x> is the device name of the uSD card or the name of the image
  file. Apparently Allwinner allows re-distribution of this proprietary code
  "as-is".
  This boot0 blob takes care of DRAM initialisation and loads the remaining
  firmware parts, then switches the core into AArch64 mode.
  The original boot0 code looks for U-Boot at a certain place on an uSD card
  (at 19096 KB), also it expects a header with magic bytes and a checksum.
  There is a tool called boot0img[3] which takes a boot0.bin image and a compiled
  U-Boot binary (plus other binaries) and will populate that header accordingly.
  To make space for the magic header, the pine64_plus_defconfig will make sure
  there is sufficient space at the beginning of the U-Boot binary.
  boot0img will also take care of putting the different binaries at the right
  places on the uSD card and works around unused, but mandatory parts by using
  trampoline code. See the output of "boot0img -h" for more information.
  boot0img can also patch boot0 to avoid loading U-Boot from 19MB, instead
  fetching it from just behind the boot0 binary (-B option).
  $ ./boot0img -o firmware.img -B boot0.img -u u-boot-dtb.bin -e -s bl31.bin \
  -a 0x44008 -d trampoline64:0x44000
  Then write this image to a microSD card, replacing /dev/sdx with the right
  device file (see above):
  $ dd if=firmware.img of=/dev/sdx bs=8k seek=1
  
  [1] https://github.com/apritzel/arm-trusted-firmware.git
  [2] git://github.com/linux-sunxi/sunxi-tools.git
  [3] https://github.com/apritzel/pine64/