184 lines
8.8 KiB
Plaintext
184 lines
8.8 KiB
Plaintext
Allwinner 64-bit boards README
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==============================
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Newer Allwinner SoCs feature ARMv8 cores (ARM Cortex-A53) with support for
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both the 64-bit AArch64 mode and the ARMv7 compatible 32-bit AArch32 mode.
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Examples are the Allwinner A64 (used for instance on the Pine64 board) or
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the Allwinner H5 SoC (as used on the OrangePi PC 2).
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These SoCs are wired to start in AArch32 mode on reset and execute 32-bit
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code from the Boot ROM (BROM). As this has some implications on U-Boot, this
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file describes how to make full use of the 64-bit capabilities.
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Quick Start / Overview
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======================
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- Build the ARM Trusted Firmware binary (see "ARM Trusted Firmware (ATF)" below)
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$ cd /src/arm-trusted-firmware
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$ make PLAT=sun50i_a64 DEBUG=1 bl31
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- Build U-Boot (see "SPL/U-Boot" below)
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$ export BL31=/path/to/bl31.bin
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$ make pine64_plus_defconfig && make -j5
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- Transfer to an uSD card (see "microSD card" below)
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$ dd if=u-boot-sunxi-with-spl.bin of=/dev/sdx bs=8k seek=1
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- Boot and enjoy!
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Building the firmware
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=====================
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The Allwinner A64/H5 firmware consists of three parts: U-Boot's SPL, an
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ARM Trusted Firmware (ATF) build and the U-Boot proper.
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The SPL will load both ATF and U-Boot proper along with the right device
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tree blob (.dtb) and will pass execution to ATF (in EL3), which in turn will
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drop into the U-Boot proper (in EL2).
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As the ATF binary will become part of the U-Boot image file, you will need
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to build it first.
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ARM Trusted Firmware (ATF)
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----------------------------
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Checkout the latest master branch from the official ATF repository [1] and
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build it:
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$ export CROSS_COMPILE=aarch64-linux-gnu-
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$ make PLAT=sun50i_a64 DEBUG=1 bl31
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The resulting binary is build/sun50i_a64/debug/bl31.bin. Either put the
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location of this file into the BL31 environment variable or copy this to
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the root of your U-Boot build directory (or create a symbolic link).
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$ export BL31=/src/arm-trusted-firmware/build/sun50i_a64/debug/bl31.bin
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(adjust the actual path accordingly)
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The platform target "sun50i_a64" covers all boards with either an Allwinner
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A64 or H5 SoC (since they are very similar). For boards with an Allwinner H6
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SoC use "sun50i_h6".
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If you run into size issues with the resulting U-Boot image file, it might
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help to use a release build, by using "DEBUG=0" when building bl31.bin.
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As sometimes the ATF build process is a bit picky about the toolchain used,
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or if you can't be bothered with building ATF, there are known working
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binaries in the firmware repository[3], purely for convenience reasons.
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SPL/U-Boot
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------------
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Both U-Boot proper and the SPL are using the 64-bit mode. As the boot ROM
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enters the SPL still in AArch32 secure SVC mode, there is some shim code to
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enter AArch64 very early. The rest of the SPL runs in AArch64 EL3.
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U-Boot proper runs in EL2 and can load any AArch64 code (using the "go"
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command), EFI applications (with "bootefi") or arm64 Linux kernel images
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(often named "Image"), using the "booti" command.
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$ make clean
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$ export CROSS_COMPILE=aarch64-linux-gnu-
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$ make pine64_plus_defconfig
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$ make
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This will build the SPL in spl/sunxi-spl.bin and a FIT image called u-boot.itb,
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which contains the rest of the firmware. u-boot-sunxi-with-spl.bin joins those
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two components in one convenient image file.
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Boot process
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============
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The on-die BROM code will try several methods to load and execute the firmware.
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On a typical board like the Pine64 this will result in the following boot order:
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1) Reading 32KB from sector 16 (@8K) of the microSD card to SRAM A1. If the
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BROM finds the magic "eGON" header in the first bytes, it will execute that
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code. If not (no SD card at all or invalid magic), it will:
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2) Try to read 32KB from sector 16 (@8K) of memory connected to the MMC2
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controller, typically an on-board eMMC chip. If there is no eMMC or it does
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not contain a valid boot header, it will:
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3) Initialize the SPI0 controller and try to access a NOR flash connected to
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it (using the CS0 pin). If a flash chip is found, the BROM will load the
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first 32KB (from offset 0) into SRAM A1. Now it checks for the magic eGON
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header and checksum and will execute the code upon finding it. If not, it will:
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4) Initialize the USB OTG controller and will wait for a host to connect to
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it, speaking the Allwinner proprietary (but deciphered) "FEL" USB protocol.
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To boot the Pine64 board, you can use U-Boot and any of the described methods.
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FEL boot (USB OTG)
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------------------
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FEL is the name of the Allwinner defined USB boot protocol built in the
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mask ROM of most Allwinner SoCs. It allows to bootstrap a board solely
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by using the USB-OTG interface and a host port on another computer.
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As the FEL mode is controlled by the boot ROM, it expects to be running in
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AArch32. For now the AArch64 SPL cannot properly return into FEL mode, so the
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feature is disabled in the configuration at the moment.
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The repository in [3] contains FEL capable SPL binaries, built using an
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off-tree branch to generate 32-bit ARM code (along with instructions
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how to re-create them).
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microSD card
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------------
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Transfer the SPL and the U-Boot FIT image directly to an uSD card:
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# dd if=spl/sunxi-spl.bin of=/dev/sdx bs=8k seek=1
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# dd if=u-boot.itb of=/dev/sdx bs=8k seek=5
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# sync
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(replace /dev/sdx with you SD card device file name, which could be
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/dev/mmcblk[x] as well).
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Alternatively you can use the SPL and the U-Boot FIT image combined into a
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single file and transfer that instead:
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# dd if=u-boot-sunxi-with-spl.bin of=/dev/sdx bs=8k seek=1
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You can partition the microSD card, but leave the first MB unallocated (most
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partitioning tools will do this anyway).
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NOR flash
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---------
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Some boards (like the SoPine, Pinebook or the OrangePi PC2) come with a
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soldered SPI NOR flash chip. On other boards like the Pine64 such a chip
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can be connected to the SPI0/CS0 pins on the PI-2 headers.
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Create the SPL and FIT image like described above for the SD card.
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Now connect either an "A to A" USB cable to the upper USB port on the Pine64
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or get an adaptor and use a regular A-microB cable connected to it. Other
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boards often have a proper micro-B USB socket connected to the USB OTB port.
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Remove a microSD card from the slot and power on the board.
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On your host computer download and build the sunxi-tools package[2], then
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use "sunxi-fel" to access the board:
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$ ./sunxi-fel ver -v -p
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This should give you an output starting with: AWUSBFEX soc=00001689(A64) ...
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Now use the sunxi-fel tool to write to the NOR flash:
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$ ./sunxi-fel spiflash-write 0 spl/sunxi-spl.bin
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$ ./sunxi-fel spiflash-write 32768 u-boot.itb
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Now boot the board without an SD card inserted and you should see the
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U-Boot prompt on the serial console.
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(Legacy) boot0 method
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---------------------
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boot0 is Allwinner's secondary program loader and it can be used as some kind
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of SPL replacement to get U-Boot up and running from an microSD card.
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For some time using boot0 was the only option to get the Pine64 booted.
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With working DRAM init code in U-Boot's SPL this is no longer necessary,
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but this method is described here for the sake of completeness.
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Please note that this method works only with the boot0 files shipped with
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A64 based boards, the H5 uses an incompatible layout which is not supported
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by this method.
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The boot0 binary is a 32 KByte blob and contained in the official Pine64 images
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distributed by Pine64 or Allwinner. It can be easily extracted from a micro
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SD card or an image file:
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# dd if=/dev/sd<x> of=boot0.bin bs=8k skip=1 count=4
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where /dev/sd<x> is the device name of the uSD card or the name of the image
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file. Apparently Allwinner allows re-distribution of this proprietary code
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"as-is".
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This boot0 blob takes care of DRAM initialisation and loads the remaining
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firmware parts, then switches the core into AArch64 mode.
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The original boot0 code looks for U-Boot at a certain place on an uSD card
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(at 19096 KB), also it expects a header with magic bytes and a checksum.
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There is a tool called boot0img[3] which takes a boot0.bin image and a compiled
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U-Boot binary (plus other binaries) and will populate that header accordingly.
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To make space for the magic header, the pine64_plus_defconfig will make sure
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there is sufficient space at the beginning of the U-Boot binary.
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boot0img will also take care of putting the different binaries at the right
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places on the uSD card and works around unused, but mandatory parts by using
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trampoline code. See the output of "boot0img -h" for more information.
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boot0img can also patch boot0 to avoid loading U-Boot from 19MB, instead
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fetching it from just behind the boot0 binary (-B option).
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$ ./boot0img -o firmware.img -B boot0.img -u u-boot-dtb.bin -e -s bl31.bin \
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-a 0x44008 -d trampoline64:0x44000
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Then write this image to a microSD card, replacing /dev/sdx with the right
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device file (see above):
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$ dd if=firmware.img of=/dev/sdx bs=8k seek=1
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[1] https://github.com/ARM-software/arm-trusted-firmware.git
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[2] git://github.com/linux-sunxi/sunxi-tools.git
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[3] https://github.com/apritzel/pine64/
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