[PATCH v2] sunxi: add board documentation

[Heinrich Schuchardt]

On 12/27/21 16:07, Andre Przywara wrote:
> Add some long overdue instructions for building and installing U-Boot on
> Allwinner SoC based boards.
> This describes the building process, including TF-A and crust, plus
> installation to SD card, eMMC and SPI flash, both from Linux and U-Boot
> itself. Also describe FEL booting.
>
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
> ---
> Changelog v1 ... v2:
> - drop optional command line parameters (-j, -v, ...)
> - more links and explanations around crust
> - use "sudo dd" instead of "#" root prompt to indicate root privileges
> - add prominent note about BROM header inside GPT
> - more hints on SoCs with 128K boot offset ability
> - add Allwinner index to top-level index.rst
> - smaller typo fixes
>
>   doc/board/allwinner/index.rst |   9 +
>   doc/board/allwinner/sunxi.rst | 320 ++++++++++++++++++++++++++++++++++
>   doc/board/index.rst           |   1 +
>   3 files changed, 330 insertions(+)
>   create mode 100644 doc/board/allwinner/index.rst
>   create mode 100644 doc/board/allwinner/sunxi.rst
>
> diff --git a/doc/board/allwinner/index.rst b/doc/board/allwinner/index.rst
> new file mode 100644
> index 00000000000..7352ccd5c0a
> --- /dev/null
> +++ b/doc/board/allwinner/index.rst
> @@ -0,0 +1,9 @@
> +.. SPDX-License-Identifier: GPL-2.0+
> +
> +Allwinner (sunxi) boards
> +========================
> +
> +.. toctree::
> +   :maxdepth: 2
> +
> +   sunxi
> diff --git a/doc/board/allwinner/sunxi.rst b/doc/board/allwinner/sunxi.rst
> new file mode 100644
> index 00000000000..ea0f1be10b2
> --- /dev/null
> +++ b/doc/board/allwinner/sunxi.rst
> @@ -0,0 +1,320 @@
> +.. SPDX-License-Identifier: GPL-2.0+
> +.. Copyright (C) 2021 Arm Ltd.
> +
> +Allwinner SoC based boards
> +==========================
> +For boards using an Allwinner ARM based SoC ("sunxi"), the U-Boot build
> +system generates a single integrated image file: ``u-boot-sunxi-with-spl.bin.``
> +This file can be used on SD cards, eMMC devices, SPI flash and for the
> +USB-OTG based boot method (FEL). To build this file:
> +
> +* For 64-bit SoCs, build Trusted Firmware (TF-A, formerly known as ATF) first,
> +  you will need its ``bl31.bin``. See below for more details.
> +* Optionally on 64-bit SoCs, build the `crust`_ management processor firmware,
> +  you will need its ``scp.bin``. See below for more details.
> +* Build U-Boot::
> +
> +  $ export BL31=/path/to/bl31.bin		# required for 64-bit SoCs
> +  $ export SCP=/path/to/scp.bin			# optional for some 64-bit SoCs
> +  $ make <yourboardname>_defconfig
> +  $ make
> +* Transfer to an (micro)SD card (see below for more details)::
> +
> +  $ sudo dd if=u-boot-sunxi-with-spl.bin of=/dev/sdX bs=8k seek=1
> +* Boot and enjoy!
> +
> +.. note::
> +  The traditional SD card location the Allwinner BootROM loads from is 8KB
> +  (sector 16). This works fine with the old MBR partitioning scheme, which most
> +  SD cards come formatted with. However this is in the middle of a potential
> +  GPT partition table, which will become invalid in this step. Newer SoCs
> +  (starting with the H3 from late 2014) also support booting from 128KB, which
> +  is beyond even a GPT and thus a safer location.
> +

I will remove this duplicate blank line when merging.

Reviewed-by: Heinrich Schuchardt <xypron.glpk at gmx.de>

> +
> +For more details, and alternative boot locations or installations, see below.
> +
> +Building Arm Trusted Firmware (TF-A)
> +------------------------------------
> +Boards using a 64-bit Soc (A64, H5, H6, H616, R329) require the BL31 stage of
> +the `Arm Trusted Firmware-A`_ firmware. This provides the reference
> +implementation of secure software for Armv8-A, offering PSCI and SMCCC
> +services. Allwinner support is fully mainlined. To build bl31.bin::
> +
> +  $ git clone https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git
> +  $ cd trusted-firmware-a
> +  $ make CROSS_COMPILE=aarch64-linux-gnu- PLAT=sun50i_a64 DEBUG=1
> +  $ export BL31=$(pwd)/build/sun50i_a64/debug/bl31.bin
> +
> +The target platform (``PLAT=``) for A64 and H5 SoCs is sun50i_a64, for the H6
> +sun50i_h6, for the H616 sun50i_h616, and for the R329 sun50i_r329. Use::
> +
> +  $ find plat/allwinner -name platform.mk
> +
> +to find all supported platforms. TF-A's `docs/plat/allwinner.rst`_ contains
> +more information and lists some build options.
> +
> +Building the Crust management processor firmware
> +------------------------------------------------
> +For some SoCs and boards, the integrated OpenRISC management controller can
> +be used to provide power management services, foremost suspend to RAM.
> +There is a community supported Open Source implementation called `crust`_,
> +which runs on most SoCs featuring a management controller.
> +
> +This firmware part is optional, setting the SCP environment variable to
> +/dev/null avoids the warning message when building without one.
> +
> +To build crust's scp.bin, you need an OpenRISC (or1k) cross compiler, then::
> +
> +  $ git clone https://github.com/crust-firmware/crust.git
> +  $ cd crust
> +  $ make <yourboard>_defconfig
> +  $ make CROSS_COMPILE=or1k-none-elf- scp
> +  $ export SCP=$(pwd)/build/scp/scp.bin
> +
> +Find a list of supported board configurations in the `configs/`_ directory.
> +The `crust README`_ has more information about the building process, including
> +information about where to get OpenRISC cross compilers.
> +
> +Building the U-Boot image
> +-------------------------
> +Find the U-Boot defconfig file for your board first. Those files live in
> +the ``configs/`` directory; you can grep for the stub name of the devicetree
> +file, if you know that, or for the SoC name to find the right version::
> +
> +    $ git grep -l MACH_SUN8I_H3 configs
> +    $ git grep -l sun50i-h6-orangepi-3 configs
> +
> +The `linux-sunxi`_ wiki also lists the name of the defconfig file in the
> +respective board page. Then use this defconfig file to create the .config
> +file, and build the image::
> +
> +    $ make <yourboard>_defconfig
> +    $ make
> +
> +For 64-bit boards, this requires either the BL31 environment variable to be
> +set (as shown above in the TF-A build example), or it to be supplied on the
> +build command line::
> +
> +    $ make BL31=/src/tf-a.git/build/sun50i_h616/debug/bl31.bin
> +
> +The same applies to the (optional) SCP firmware.
> +
> +The file containing everything you need is called ``u-boot-sunxi-with-spl.bin``,
> +you will find it in the root folder of your U-Boot (build) tree. Except for
> +raw NAND flash devices this very same file can be used for any boot source.
> +It will contain the SPL image, fitted with the proper signature recognised by
> +the BROM, and the required checksum. Also it will contain at least U-Boot
> +proper, either wrapped in the legacy U-Boot image format, or in a FIT image.
> +The board's devicetree is also included, either appended to the U-Boot proper
> +image, or contained in the FIT image. If required by the SoC, this FIT file will
> +also include the other firmware images.
> +
> +Installing U-Boot
> +-----------------
> +
> +Installing on a (micro-) SD card
> +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> +All Allwinner SoCs will try to find a boot image at sector 16 (8KB) of
> +an SD card, connected to the first MMC controller. To transfer the generated
> +image to an SD card, from any Linux device (including the board itself) with
> +an (micro-)SD card reader, type::
> +
> +    $ sudo dd if=u-boot-sunxi-with-spl.bin of=/dev/sdX bs=1k seek=8
> +
> +``/dev/sdx`` needs to be replaced with the block device name of the SD card
> +reader. On some machines this could be ``/dev/mmcblkX``.
> +Newer SoCs (starting from the H3 from 2014, and including all ARM64 SoCs),
> +also look at sector 256 (128KB) for the signature (after having checked the
> +8KB location). Installing the firmware there has the advantage of not
> +overlapping with a GPT partition table. Simply replace the "``seek=8``" above
> +with "``seek=128``".
> +
> +You can also use an existing (mainline) U-Boot to write to the SD card. Load
> +the generated U-Boot image somewhere into DRAM (via ``ext4load``, ``fatload``,
> +or ``tftpboot``), then write to MMC device 0::
> +
> +    => fatload mmc 0:1 $kernel_addr_r u-boot-sunxi-with-spl.bin
> +    => mmc dev 0
> +    => mmc write $kernel_addr_r 0x10 0x7f0
> +
> +To use the alternative boot location on newer SoCs::
> +
> +    => mmc write $kernel_addr_r 0x100 0x700
> +
> +Installing on eMMC (on-board flash memory)
> +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> +Some boards have a soldered eMMC chip, some other boards have an eMMC socket
> +to receive an optional eMMC module. U-Boot can be installed to those chips,
> +to boot without an SD card inserted. The Boot-ROM can boot either from the
> +regular user data partition, or from one of the separate eMMC boot partitions.
> +U-Boot can be installed either from a running Linux instance on the device,
> +from a running (mainline) U-Boot, or via an adapter for the (removable)
> +eMMC module.
> +
> +Installing on an eMMC user data partition from Linux
> +````````````````````````````````````````````````````
> +If you have a running Linux instance on the device, and have somehow copied
> +over the image file to that device, you can write the image directly into the
> +eMMC device from there.
> +Find the name of the block device file first, it is one of the
> +``/dev/mmcblk<X>`` devices. eMMC devices typically also list a
> +``/dev/mmcblk<X>boot0`` partition (see below), this helps you to tell it apart
> +from the SD card device.
> +To install onto the user data partition::
> +
> +    $ sudo dd if=u-boot-sunxi-with-spl.bin of=/dev/dev/mmcblkX bs=1k seek=8
> +
> +Similar to SD cards, the BROM in newer SoCs (H3 and above) also checks
> +sector 256 of an eMMC, so you can use "``seek=128``" as well. Having a GPT
> +on an eMMC device is much more likely than on an SD card, so you should
> +probably stick to the alternative location, or use one of the boot partitions.
> +
> +Installing on an eMMC boot partition from Linux
> +```````````````````````````````````````````````
> +In the following examples, ``/dev/mmcblkX`` needs to be replaced with the block
> +device name of the eMMC device. The eMMC device can be recognised by also
> +listing the boot partitions (``/dev/mmcblkXboot0``) in ``/proc/partitions``.
> +
> +To allow booting from one of the eMMC boot partitions, this one needs to be
> +enabled first. This only needs to be done once, as this setting is
> +persistent, even though the boot partition can be disabled or changed again
> +any time later::
> +
> +    # apt-get install mmc-utils
> +    # mmc bootbus set single_hs x1 x4 /dev/mmcblkX
> +    # mmc bootpart enable 1 1 /dev/mmcblkX
> +
> +The first "1" in the last command points to the boot partition number to be
> +used, typically devices offer two boot partitions.
> +
> +By default Linux disables write access to the boot partitions, to prevent
> +accidental overwrites. You need to disable the write protection (until the
> +next reboot), then can write the U-Boot image to the *first* sector of the
> +selected boot partition::
> +
> +    # echo 0 > /sys/block/mmcblkXboot0/force_ro
> +    # dd if=u-boot-sunxi-with-spl.bin of=/dev/mmcblkXboot0 bs=1k
> +
> +Installing on an eMMC user data partition from U-Boot
> +`````````````````````````````````````````````````````
> +You can also write the generated image file to an SD card, boot the device
> +from there, and burn the very same image to the eMMC device from U-Boot.
> +The following commands copy the image from the SD card to the eMMC device::
> +
> +    => mmc dev 0
> +    => mmc read $kernel_addr_r 0x10 0x7f0
> +    => mmc dev 1
> +    => mmc write $kernel_addr_r 0x10 0x7f0
> +
> +You can also copy an image from the 8K offset of an SD card to the 128K
> +offset of the eMMC (or any combination), just change the "``0x10 0x7f0``" above
> +to "``0x100 0x700``", respectively. Of course the image file can be loaded via
> +any other loading method, including ``fatload``, ``ext4load``, ``tftpboot``.
> +
> +Installing on an eMMC boot partition from U-Boot
> +````````````````````````````````````````````````
> +The selected eMMC boot partition needs to be initially enabled first (same
> +as in Linux above), you can do this from U-Boot with::
> +
> +    => mmc dev 1
> +    => mmc bootbus 1 1 0 0
> +    => mmc partconf 1 1 1 1
> +
> +The first "1" in both commands denotes the MMC device number. The second "1"
> +in the partconf command sets the required ``BOOT_ACK`` option, the last two "1"s
> +selects the active boot partition and the target for the next data access,
> +respectively. So for the next "``mmc write``" command to address one of the boot
> +partitions, the last number must either be "1" or "2", "0" would switch (back)
> +to the normal user data partition.
> +
> +Then load the ``u-boot-sunxi-with-spl.bin`` image file into DRAM, either by
> +reading directly from an SD card or eMMC user data partition, or from a
> +file system or TFTP (see above), and transfer it to the boot partition::
> +
> +    => tftpboot $kernel_addr_r u-boot-sunxi-with-spl.bin
> +    => mmc write $kernel_addr_r 0 0x7f0
> +
> +After that the device should boot from the selected boot partition, which takes
> +precedence over booting from the user data partition.
> +
> +Installing on SPI flash
> +^^^^^^^^^^^^^^^^^^^^^^^
> +Some devices have a SPI NOR flash chip soldered on the board. If it is
> +connected to the SPI0 pins on PortC, the BROM can also boot from there.
> +Typically the SPI flash has the lowest boot priority, so SD card and eMMC
> +devices will be considered first.
> +
> +Installing on SPI flash from Linux
> +``````````````````````````````````
> +If the devicetree enables and describes the SPI flash device, you can access
> +the SPI flash content from Linux, using the `MTD utils`_::
> +
> +    # apt-get install mtd-utils
> +    # mtdinfo
> +    # mtd_debug erase /dev/mtdX 0 0xf0000
> +    # mtd_debug write /dev/mtdX 0 0xf0000 u-boot-sunxi-with-spl.bin
> +
> +``/dev/mtdX`` needs to be replaced with the respective device name, as listed
> +in the output of ``mtdinfo``.
> +
> +Installing on SPI flash from U-Boot
> +```````````````````````````````````
> +If SPI flash driver and command support (``CONFIG_CMD_SF``) is enabled in the
> +U-Boot configuration, the image file can be installed via U-Boot as well::
> +
> +    => tftpboot $kernel_addr_r u-boot-sunxi-with-spl.bin
> +    => sf probe
> +    => sf erase 0 +0xf0000
> +    => sf write $kernel_addr_r 0 $filesize
> +
> +Installing on SPI flash via USB in FEL mode
> +```````````````````````````````````````````
> +If the device is in FEL mode (see below), the SPI flash can also be written to
> +with the sunxi-fel utility, via an USB(-OTG) cable from any USB host machine::
> +
> +    $ sunxi-fel spiflash-write 0 u-boot-sunxi-with-spl.bin
> +
> +Booting via the USB(-OTG) FEL mode
> +----------------------------------
> +If none of the boot locations checked by the BROM contains a medium or valid
> +signature, the BROM will enter the so-called FEL mode, in which it will
> +listen to commands from a host on the SoC's USB-OTG interface. Those commands
> +allow to read from and write to arbitrary memory locations, also to start
> +execution at any address, which allows to bootstrap a board solely via an
> +USB cable. Some boards feature a "FEL" or "U-Boot" button, which forces
> +FEL mode despite a valid boot location being present. The same can be achieved
> +via a `magic binary`_ on an SD card, which allows to enter FEL mode on any
> +board.
> +
> +To use FEL booting, let the board enter FEL mode, via any of the mentioned
> +methods (no boot media, FEL button, SD card with FEL binary), then connect
> +a USB cable to the board's USB OTG port. Some boards (Pine64, TV boxes) don't
> +have a separate OTG port. In this case mostly one of the USB-A ports is
> +connected to USB0, and can be used via a non-standard USB-A to USB-A cable.
> +
> +Typically there is no on-board indication of FEL mode, other than a new USB
> +device appearing on the connected host computer. The USB vendor/device ID
> +is 1f3a:efe8. Mostly this will identify as "sunxi SoC OTG connector in
> +FEL/flashing mode", but older distributions might still report "Onda
> +(unverified) V972 tablet in flashing mode".
> +
> +The `sunxi_fel`_ tool implements the proprietary BROM protocol, and allows to
> +bootstrap U-Boot by just providing our venerable u-boot-sunxi-with-spl.bin::
> +
> +    $ sudo apt-get install sunxi-tools
> +    $ sunxi-fel uboot u-boot-sunxi-with-spl.bin
> +
> +Additional binaries like a kernel, an initial ramdisk or a boot script, can
> +also be uploaded via FEL, check the Wiki's `FEL page`_ for more details.
> +
> +.. _`Arm Trusted Firmware-A`:  https://www.trustedfirmware.org/projects/tf-a/
> +.. _`docs/plat/allwinner.rst`: https://trustedfirmware-a.readthedocs.io/en/latest/plat/allwinner.html
> +.. _`crust`: https://github.com/crust-firmware/crust
> +.. _`configs/`: https://github.com/crust-firmware/crust/tree/master/configs
> +.. _`crust README`: https://github.com/crust-firmware/crust/blob/master/README.md#building-the-firmware
> +.. _`linux-sunxi`: https://linux-sunxi.org
> +.. _`MTD utils`: http://www.linux-mtd.infradead.org/
> +.. _`magic binary`: https://github.com/linux-sunxi/sunxi-tools/raw/master/bin/fel-sdboot.sunxi
> +.. _`sunxi_fel`: https://github.com/linux-sunxi/sunxi-tools
> +.. _`FEL page`: https://linux-sunxi.org/FEL/USBBoot
> diff --git a/doc/board/index.rst b/doc/board/index.rst
> index 74ea33e0816..4555af5f119 100644
> --- a/doc/board/index.rst
> +++ b/doc/board/index.rst
> @@ -9,6 +9,7 @@ Board-specific doc
>      actions/index
>      advantech/index
>      AndesTech/index
> +   allwinner/index
>      amlogic/index
>      apple/index
>      atmel/index