board: rockchip: add Anbernic RGXX3 Series Devices

The Anbernic RGxx3 is a "pseudo-device" that encompasses the following
devices:

 - Anbernic RG353M
 - Anbernic RG353P
 - Anbernic RG353V
 - Anbernic RG353VS
 - Anbernic RG503

The rk3566-anbernic-rgxx3.dtsi is synced with upstream Linux, but
rk3566-anbernic-rgxx3.dts is a U-Boot specific devicetree that
is used for all RGxx3 devices.

Via the board.c file, the bootloader automatically sets the correct
fdtfile, board, and board_name environment variables so that the
correct devicetree can be passed to Linux. It is also possible to
simply hard-code a single devicetree in the boot.scr file and use
that to load Linux as well.

The common specifications for each device are:

 - Rockchip RK3566 SoC
 - 2 external SDMMC slots
 - 1 USB-C host port, 1 USB-C peripheral port
 - 1 mini-HDMI output
 - MIPI-DSI based display panel
 - ADC controlled joysticks with a GPIO mux
 - GPIO buttons
 - A PWM controlled vibrator
 - An ADC controlled button

All of the common features are defined in the devicetree synced from
upstream Linux.

TODO: DSI panel auto-detection for the RG353 devices (requires porting
of DSI controller driver and DSI-DPHY driver to send DSI commands to
the panel).

Signed-off-by: Chris Morgan <[email protected]>
Reviewed-by: Kever Yang <[email protected]>

4 files changed, 60 insertions, 0 deletions

diff --git a/doc/board/anbernic/index.rst b/doc/board/anbernic/index.rst
new file mode 100644
index 00000000000..03758d86137
--- /dev/null
+++ b/doc/board/anbernic/index.rst
@@ -0,0 +1,9 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+Anbernic
+========
+
+.. toctree::
+   :maxdepth: 2
+
+   rgxx3.rst
diff --git a/doc/board/anbernic/rgxx3.rst b/doc/board/anbernic/rgxx3.rst
new file mode 100644
index 00000000000..afa7538282f
--- /dev/null
+++ b/doc/board/anbernic/rgxx3.rst
@@ -0,0 +1,47 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+U-Boot for Anbernic RGxx3 Devices
+=================================
+
+This allows U-Boot to boot the following Anbernic devices:
+
+ - Anbernic RG353M
+ - Anbernic RG353P
+ - Anbernic RG353V
+ - Anbernic RG353VS
+ - Anbernic RG503
+
+The correct device is detected automatically by comparing ADC values
+from ADC channel 1. In the event of an RG353V, an attempt is then made
+to probe for an eMMC and if it fails the device is assumed to be an
+RG353VS. Based on the detected device, the environment variables
+"board", "board_name", and "fdtfile" are set to the correct values
+corresponding to the board which can be read by a boot script to boot
+with the correct device tree.
+
+Please note that there are some versions of the RG353 devices with
+different panels. Panel auto-detection is planned for a later date.
+
+Building U-Boot
+---------------
+
+.. code-block:: bash
+
+    $ export CROSS_COMPILE=aarch64-none-elf-
+    $ export BL31=../rkbin/bin/rk35/rk3568_bl31_v1.34.elf
+    $ export ROCKCHIP_TPL=../rkbin/bin/rk35/rk3568_ddr_1056MHz_v1.13.bin
+    $ make anbernic-rgxx3_defconfig
+    $ make
+
+This will build ``u-boot-rockchip.bin`` which can be written to an SD
+card.
+
+Image installation
+------------------
+
+Write the ``u-boot-rockchip.bin`` to an SD card offset 32kb from the
+start.
+
+.. code-block:: bash
+
+    $ dd if=u-boot-rockchip.bin of=/dev/mmcblk0 bs=512 seek=64
diff --git a/doc/board/index.rst b/doc/board/index.rst
index b2da6ec5532..120daa48ee2 100644
--- a/doc/board/index.rst
+++ b/doc/board/index.rst
@@ -11,6 +11,7 @@ Board-specific doc
    AndesTech/index
    allwinner/index
    amlogic/index
+   anbernic/index
    apple/index
    armltd/index
    atmel/index
diff --git a/doc/board/rockchip/rockchip.rst b/doc/board/rockchip/rockchip.rst
index 1dccb17d725..a21399c88e1 100644
--- a/doc/board/rockchip/rockchip.rst
+++ b/doc/board/rockchip/rockchip.rst
@@ -87,6 +87,9 @@ List of mainline supported Rockchip boards:
      - Rockchip Evb-RK3399 (evb_rk3399)
      - Theobroma Systems RK3399-Q7 SoM - Puma (puma_rk3399)
 
+* rk3566
+     - Anbernic RGxx3 (rgxx3-rk3566)
+
 * rk3568
      - Rockchip Evb-RK3568 (evb-rk3568)