doc: boards: add Cubieboard7 documentation

This adds build and flash steps for Actions S700
based Cubieboard7 board.

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Amit Singh Tomar <amittomer25@gmail.com>

doc/board/actions/cubieboard7.rst

+.. SPDX-License-Identifier: GPL-2.0+
+.. Copyright (C) 2020 Amit Singh Tomar <amittomer25@gmail.com>
+
+CUBIEBOARD7
+===========
+
+About this
+----------
+
+This document describes build and flash steps for Actions S700 SoC based Cubieboard7
+board.
+
+Cubieboard7 initial configuration
+---------------------------------
+
+Default Cubieboard7 comes with pre-installed Android where U-Boot is configured with
+a bootdelay of 0, entering a prompt by pressing keys does not seem to work.
+
+Though, one can enter ADFU mode and flash debian image(from host machine) where
+getting into u-boot prompt is easy.
+
+Enter ADFU Mode
+----------------
+
+Before write the firmware, let the development board entering the ADFU mode: insert
+one end of the USB cable to the PC, press and hold the ADFU button, and then connect
+the other end of the USB cable to the Mini USB port of the development board, release
+the ADFU button, after connecting it will enter the ADFU mode.
+
+Check whether entered ADFU Mode
+--------------------------------
+
+The user needs to run the following command on the PC side to check if the ADFU
+device is detected. ID realted to "Actions Semiconductor Co., Ltd"  means that
+the PC side has been correctly detected ADFU device, the development board
+also enter into the ADFU mode.
+
+.. code-block:: none
+
+   $ lsusb
+   Bus 001 Device 005: ID 04f2:b2eb Chicony Electronics Co., Ltd
+   Bus 001 Device 004: ID 0a5c:21e6 Broadcom Corp. BCM20702 Bluetooth 4.0 [ThinkPad]
+   Bus 001 Device 003: ID 046d:c534 Logitech, Inc. Unifying Receiver
+   Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
+   Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
+   Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
+   Bus 003 Device 013: ID 10d6:10d6 Actions Semiconductor Co., Ltd
+   Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
+
+Flashing debian image
+---------------------
+
+.. code-block:: none
+
+   $ sudo ./ActionsFWU.py --fw=debian-stretch-desktop-cb7-emmc-v2.0.fw
+   ActionsFWU.py	: 1.0.150828.0830
+   libScript.so    : 2.3.150825.0951
+   libFileSystem.so: 2.3.150825.0952
+   libProduction.so: 2.3.150915.1527
+   =====burn all partition====
+   FW_VER: 3.10.37.180608
+   3% DOWNLOAD ADFUDEC ...
+   5% DOWNLOAD BOOT PARA ...
+   7% SWITCH ADFUDEC ...
+   12% DOWNLOAD BL31 ...
+   13% DOWNLOAD BL32 ...
+   15% DOWNLOAD VMLINUX ...
+   20% DOWNLOAD INITRD ...
+   24% DOWNLOAD FDT ...
+   27% DOWNLOAD ADFUS ...
+   30% SWITCH ADFUS ...
+   32% DOWNLOAD MBR ...
+   35% DOWNLOAD PARTITIONS ...
+   WRITE_MBRC_PARTITION
+   35% write p0 size = 2048 : ok
+   WRITE_BOOT_PARTITION
+   35% write p1 size = 2048 : ok
+   WRITE_MISC_PARTITION
+   36% write p2 size = 98304 : ok
+   WRITE_SYSTEM_PARTITION
+   94% write p3 size = 4608000 : ok
+   FORMAT_SWAP_PARTITION
+   94% write p4 size = 20480 : ok
+   95% TRANSFER OVER ...
+   Firmware upgrade successfully!
+
+Debian image can be downloaded from here[1].
+
+Once debian image is flashed, one can get into u-boot prompt by pressing any key and from
+there run ums command(make sure, usb cable is connected between host and target):
+
+.. code-block:: none
+
+   owl> ums 0 mmc 1
+
+Above command would mount debian image partition on host machine.
+
+Building U-BOOT proper image
+----------------------------
+
+.. code-block:: none
+
+   $ make clean
+   $ export CROSS_COMPILE=aarch64-linux-gnu-
+   $ make ARCH=arm cubieboard7_defconfig
+   $ make u-boot-dtb.img -j16
+
+u-boot-dtb.img can now be flashed to debian image partition mounted on host machine.
+
+.. code-block:: none
+
+   $ sudo dd if=u-boot-dtb.img of=/dev/sdb bs=1024 seek=3072
+
+[1]: https://pan.baidu.com/s/1uawPr0Jao2HgWFLZCLzHAg#list/path=%2FCubieBoard_Download%2FBoard%2FCubieBoard7%2F%E6%96%B9%E7%B3%96%E6%96%B9%E6%A1%88%E5%BC%80%E5%8F%91%E8%B5%84%E6%96%99%2FImage%2FDebian%2FV2.1-test&parentPath=%2F

doc/board/actions/index.rst

+.. SPDX-License-Identifier: GPL-2.0+
+.. Copyright (C) 2020 Amit Singh Tomar <amittomer25@gmail.com>
+
+Actions
+========
+
+.. toctree::
+   :maxdepth: 2
+
+   cubieboard7

doc/board/index.rst

@@ -6,6 +6,7 @@ Board-specific doc
 .. toctree::
    :maxdepth: 2
 
+   actions/index
    AndesTech/index
    atmel/index
    coreboot/index