rockchip: add support for Theobroma Systems SOM-RK3588-Q7 Tiger module

The RK3588-Q7 SoM is a Qseven-compatible (70mm x 70mm, MXM-230
connector) system-on-module from Theobroma Systems, featuring the
Rockchip RK3588.

It provides the following feature set:
 * up to 16GB LPDDR4x
 * on-module eMMC
 * SD card (on a baseboard) via edge connector
 * Gigabit Ethernet with on-module GbE PHY
 * HDMI/eDP
 * MIPI-DSI
 * 4x MIPI-CSI (3x on FPC connectors, 1x over Q7)
 * HDMI input over FPC connector
 * CAN
 * USB
   - 1x USB 3.0 dual-role (direct connection)
   - 2x USB 3.0 host + 1x USB 2.0 host
 * PCIe
   - 1x PCIe 2.1 Gen3, 4 lanes
   - 2xSATA / 2x PCIe 2.1 Gen1, 2 lanes
 * on-module ATtiny816 companion controller, implementing:
   - low-power RTC functionality (ISL1208 emulation)
   - fan controller (AMC6821 emulation)
 * on-module Secure Element with Global Platform 2.2.1 compliant
   JavaCard environment

The support is added for Tiger on Haikou devkit, similarly to RK3399
Puma and PX30 Ringneck.

Cc: Quentin Schulz <foss+uboot@0leil.net>
Signed-off-by: Quentin Schulz <quentin.schulz@cherry.de>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/doc/board/theobroma-systems/tiger_rk3588.rst b/doc/board/theobroma-systems/tiger_rk3588.rst
new file mode 100644
index 0000000..a73eec7
--- /dev/null
+++ b/doc/board/theobroma-systems/tiger_rk3588.rst
@@ -0,0 +1,102 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+SOM-RK3588-Q7 Tiger
+===================
+
+The RK3588-Q7 SoM is a Qseven-compatible (70mm x 70mm, MXM-230
+connector) system-on-module from Theobroma Systems, featuring the
+Rockchip RK3588.
+
+It provides the following feature set:
+ * up to 16GB LPDDR4x
+ * on-module eMMC
+ * SD card (on a baseboard) via edge connector
+ * Gigabit Ethernet with on-module GbE PHY
+ * HDMI/eDP
+ * MIPI-DSI
+ * 4x MIPI-CSI (3x on FPC connectors, 1x over Q7)
+ * HDMI input over FPC connector
+ * CAN
+ * USB
+   - 1x USB 3.0 dual-role (direct connection)
+   - 2x USB 3.0 host + 1x USB 2.0 host
+ * PCIe
+   - 1x PCIe 2.1 Gen3, 4 lanes
+   - 2xSATA / 2x PCIe 2.1 Gen1, 2 lanes
+ * on-module ATtiny816 companion controller, implementing:
+   - low-power RTC functionality (ISL1208 emulation)
+   - fan controller (AMC6821 emulation)
+ * on-module Secure Element with Global Platform 2.2.1 compliant
+   JavaCard environment
+
+Here is the step-by-step to boot to U-Boot on SOM-RK3588-Q7 Tiger from Theobroma
+Systems.
+
+Get the TF-A and DDR init (TPL) binaries
+----------------------------------------
+
+.. prompt:: bash
+
+   git clone https://github.com/rockchip-linux/rkbin
+   cd rkbin
+   export RKBIN=$(pwd)
+   export BL31=$RKBIN/bin/rk35/rk3588_bl31_v1.38.elf
+   export ROCKCHIP_TPL=$RKBIN/bin/rk35/rk3588_ddr_lp4_2112MHz_lp5_2736MHz_v1.11.bin
+   sed -i 's/^uart baudrate=.*$/uart baudrate=115200/' tools/ddrbin_param.txt
+   sed -i 's/^uart iomux=.*$/uart iomux=2/' tools/ddrbin_param.txt
+   ./tools/ddrbin_tool tools/ddrbin_param.txt "$ROCKCHIP_TPL"
+   ./tools/boot_merger RKBOOT/RK3588MINIALL.ini
+   export RKDB=$RKBIN/rk3588_spl_loader_v1.11.112.bin
+
+This will setup all required external dependencies for compiling U-Boot. This will
+be updated in the future once upstream Trusted-Firmware-A supports RK3588 or U-Boot
+gains support for open-source DRAM initialization in TPL.
+
+Build U-Boot
+------------
+
+.. prompt:: bash
+
+   cd ../u-boot
+   make CROSS_COMPILE=aarch64-linux-gnu- tiger-rk3588_defconfig all
+
+This will build ``u-boot-rockchip.bin`` which can be written to an MMC device
+(eMMC or SD card).
+
+Flash the image
+---------------
+
+Copy ``u-boot-rockchip.bin`` to offset 32k for SD/eMMC.
+
+SD-Card
+~~~~~~~
+
+.. prompt:: bash
+
+   dd if=u-boot-rockchip.bin of=/dev/sdX seek=64
+
+.. note::
+
+   Replace ``/dev/sdX`` to match your SD card kernel device.
+
+eMMC
+~~~~
+
+``rkdeveloptool`` allows to flash the on-board eMMC via the USB OTG interface
+with help of the Rockchip loader binary.
+
+To enter the USB flashing mode on Haikou baseboard, remove any SD card, insert a
+micro-USB cable in the ``Q7 USB P1`` connector (P8), move ``SW5`` switch into
+``BIOS Disable`` mode, power cycle or reset the board and move ``SW5`` switch
+back to ``Normal Boot`` mode. A new USB device should have appeared on your PC
+(check with ``lsusb -d 2207:350b``).
+
+To flash U-Boot on the eMMC with ``rkdeveloptool``:
+
+.. prompt:: bash
+
+   git clone https://github.com/rockchip-linux/rkdeveloptool
+   cd rkdeveloptool
+   autoreconf -i && CPPFLAGS=-Wno-format-truncation ./configure && make
+   ./rkdeveloptool db "$RKDB"
+   ./rkdeveloptool wl 64 ../u-boot-rockchip.bin