rockchip: add support for PX30 Ringneck SoM on Haikou Devkit

The PX30-µQ7 (Ringneck) is a system-on-module featuring the Rockchip
PX30 in a micro Qseven-compatible form-factor.

PX30-µQ7 features:
        * CPU: quad-core Cortex-A35
        * DRAM: 2GB dual-channel
        * eMMC: onboard eMMC
        * SD/MMC
        * TI DP83825I 10/100Mbps PHY
        * USB:
                * USB2.0 dual role port
                * 3x USB2.0 host via onboard USB2.0 hub
        * Display: MIPI-DSI
        * Camera: MIPI-CSI
        * onboard 2.4GHz WiFi + Bluetooth module
        * Companion Controller: on-board additional microcontroller
	  (STM32 Cortex-M0 or ATtiny):
                * RTC
                * fan controller
                * CAN (only STM32)

The non-U-Boot DTS files are imported from Linux v6.2-rc2.

Cc: Quentin Schulz <foss+uboot@0leil.net>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
diff --git a/board/theobroma-systems/ringneck_px30/README b/board/theobroma-systems/ringneck_px30/README
new file mode 100644
index 0000000..e756b3a
--- /dev/null
+++ b/board/theobroma-systems/ringneck_px30/README
@@ -0,0 +1,69 @@
+Introduction
+============
+
+The PX30-uQ7 (Ringneck) SoM is a µQseven-compatible (40mmx70mm, MXM-230
+connector) system-on-module from Theobroma Systems[1], featuring the
+Rockchip PX30.
+
+It provides the following feature set:
+  * up to 4GB DDR4
+  * up to 128GB on-module eMMC (with 8-bit 1.8V interface)
+  * SD card (on a baseboard) via edge connector
+  * Fast Ethernet with on-module TI DP83825I PHY
+  * MIPI-DSI/LVDS
+  * MIPI-CSI
+  * USB
+    - 1x USB 2.0 dual-role
+    - 3x USB 2.0 host
+  * on-module companion controller (STM32 Cortex-M0 or ATtiny), implementing:
+    - low-power RTC functionality (ISL1208 emulation)
+    - fan controller (AMC6821 emulation)
+    - USB<->CAN bridge controller (STM32 only)
+  * on-module Espressif ESP32 for Bluetooth + 2.4GHz WiFi
+  * on-module NXP SE05x Secure Element
+
+Here is the step-by-step to boot to U-Boot on px30.
+
+Get the Source and build ATF binary
+===================================
+
+  > git clone https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git
+
+Compile the ATF
+===============
+
+  > cd trusted-firmware-a
+  > make CROSS_COMPILE=aarch64-linux-gnu- PLAT=px30 bl31
+  > cp build/px30/release/bl31/bl31.elf ../u-boot/bl31.elf
+
+Compile the U-Boot
+==================
+
+  > cd ../u-boot
+  > make CROSS_COMPILE=aarch64-linux-gnu- ringneck-px30_defconfig all
+
+Flash the image
+===============
+
+Copy u-boot-rockchip.bin to offset 32k for SD/eMMC.
+
+SD-Card
+-------
+
+  > dd if=u-boot-rockchip.bin of=/dev/sdb seek=64
+
+eMMC
+----
+
+rkdeveloptool allows to flash the on-board eMMC via the USB OTG interface with
+help of the Rockchip loader binary.
+
+  > git clone https://github.com/rockchip-linux/rkdeveloptool
+  > cd rkdeveloptool
+  > autoreconf -i && ./configure && make
+  > git clone https://github.com/rockchip-linux/rkbin.git
+  > cd rkbin
+  > ./tools/boot_merger RKBOOT/PX30MINIALL.ini
+  > cd ..
+  > ./rkdeveloptool db rkbin/px30_loader_v1.16.131.bin
+  > ./rkdeveloptool wl 64 ../u-boot-rockchip.bin