[v4,20/20] docs: add Orange Pi PC document

diff --git a/docs/orangepi.rst b/docs/orangepi.rst
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+=========================
+Orange Pi PC Machine Type
+=========================
+
+The Xunlong Orange Pi PC is an Allwinner H3 System on Chip
+based embedded computer with mainline support in both U-Boot
+and Linux. The board comes with a Quad Core Cortex A7 @ 1.3GHz,
+1GiB RAM, 100Mbit ethernet, USB, SD/MMC, USB, HDMI and
+various other I/O.
+
+Supported devices
+-----------------
+
+The Orange Pi PC machine supports the following devices:
+
+ * SMP (Quad Core Cortex A7)
+ * Generic Interrupt Controller configuration
+ * SRAM mappings
+ * SDRAM controller
+ * Real Time Clock
+ * Timer device (re-used from Allwinner A10)
+ * UART
+ * SD/MMC storage controller
+ * EMAC ethernet
+ * USB 2.0 interfaces
+ * Clock Control Unit
+ * System Control module
+ * Security Identifier device
+
+Limitations
+-----------
+
+Currently, Orange Pi PC does *not* support the following features:
+
+- Graphical output via HDMI, GPU and/or the Display Engine
+- Audio output
+- Hardware Watchdog
+
+Also see the 'unimplemented' array in the Allwinner H3 SoC module
+for a complete list of unimplemented I/O devices:
+  ./hw/arm/allwinner-h3.c
+
+Using the Orange Pi PC machine type
+-----------------------------------
+
+Boot options
+~~~~~~~~~~~~
+
+The Orange Pi PC machine can start using the standard -kernel functionality
+for loading a Linux kernel or ELF executable. Additionally, the Orange Pi PC
+machine can also emulate the BootROM which is present on an actual Allwinner H3
+based SoC, which loads the bootloader from a SD card, specified via the -sd argument
+to qemu-system-arm.
+
+Running mainline Linux
+~~~~~~~~~~~~~~~~~~~~~~
+
+Mainline Linux kernels from 4.19 up to latest master are known to work.
+To build a Linux mainline kernel that can be booted by the Orange Pi PC machine,
+simply configure the kernel using the sunxi_defconfig configuration:
+
+  $ ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- make mrproper
+  $ ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- make sunxi_defconfig
+
+To be able to use USB storage, you need to manually enable the corresponding
+configuration item. Start the kconfig configuration tool:
+
+  $ ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- make menuconfig
+
+Navigate to the following item, enable it and save your configuration:
+
+  Device Drivers > USB support > USB Mass Storage support
+
+Build the Linux kernel with:
+
+  $ ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- make
+
+To boot the newly build linux kernel in QEMU with the Orange Pi PC machine, use:
+
+  $ qemu-system-arm -M orangepi-pc -nic user -nographic \
+      -kernel /path/to/linux/arch/arm/boot/zImage \
+      -append 'console=ttyS0,115200' \
+      -dtb /path/to/linux/arch/arm/boot/dts/sun8i-h3-orangepi-pc.dtb
+
+Orange Pi PC images
+~~~~~~~~~~~~~~~~~~~
+
+Note that the mainline kernel does not have a root filesystem. You may provide it
+with an official Orange Pi PC image from the official website:
+
+  http://www.orangepi.org/downloadresources/
+
+Another possibility is to run an Armbian image for Orange Pi PC which
+can be downloaded from:
+
+   https://www.armbian.com/orange-pi-pc/
+
+Alternatively, you can also choose to build you own image with buildroot
+using the orangepi_pc_defconfig. Also see https://buildroot.org for more information.
+
+You can choose to attach the selected image either as an SD card or as USB mass storage.
+For example, to boot using the Orange Pi PC Debian image on SD card, simply add the -sd
+argument and provide the proper root= kernel parameter:
+
+  $ qemu-system-arm -M orangepi-pc -nic user -nographic \
+      -kernel /path/to/linux/arch/arm/boot/zImage \
+      -append 'console=ttyS0,115200 root=/dev/mmcblk0p2' \
+      -dtb /path/to/linux/arch/arm/boot/dts/sun8i-h3-orangepi-pc.dtb \
+      -sd OrangePi_pc_debian_stretch_server_linux5.3.5_v1.0.img
+
+To attach the image as an USB mass storage device to the machine,
+simply append to the command:
+
+  -drive if=none,id=stick,file=myimage.img \
+  -device usb-storage,bus=usb-bus.0,drive=stick
+
+Instead of providing a custom Linux kernel via the -kernel command you may also
+choose to let the Orange Pi PC machine load the bootloader from SD card, just like
+a real board would do using the BootROM. Simply pass the selected image via the -sd
+argument and remove the -kernel, -append, -dbt and -initrd arguments:
+
+  $ qemu-system-arm -M orangepi-pc -nic user -nographic \
+       -sd Armbian_19.11.3_Orangepipc_buster_current_5.3.9.img
+
+Note that both the official Orange Pi PC images and Armbian images start
+a lot of userland programs via systemd. Depending on the host hardware and OS,
+they may be slow to emulate, especially due to emulating the 4 cores.
+To help reduce the performance slow down due to emulating the 4 cores, you can
+give the following kernel parameters (or via -append):
+
+  => setenv extraargs 'systemd.default_timeout_start_sec=9000 loglevel=7 nosmp console=ttyS0,115200'
+
+Running U-Boot
+~~~~~~~~~~~~~~
+
+U-Boot mainline can be build and configured using the orangepi_pc_defconfig
+using similar commands as describe above for Linux. Note that it is recommended
+for development/testing to select the following configuration setting in U-Boot:
+
+  Device Tree Control > Provider for DTB for DT Control > Embedded DTB
+
+To start U-Boot using the Orange Pi PC machine, provide the
+u-boot binary to the -kernel argument:
+
+  $ qemu-system-arm -M orangepi-pc -nic user -nographic \
+      -kernel /path/to/uboot/u-boot -sd disk.img
+
+Use the following U-boot commands to load and boot a Linux kernel from SD card:
+
+  -> setenv bootargs console=ttyS0,115200
+  -> ext2load mmc 0 0x42000000 zImage
+  -> ext2load mmc 0 0x43000000 sun8i-h3-orangepi-pc.dtb
+  -> bootz 0x42000000 - 0x43000000
+
+Running NetBSD
+~~~~~~~~~~~~~~
+
+The NetBSD operating system also includes support for Allwinner H3 based boards,
+including the Orange Pi PC. NetBSD 9.0 is known to work best for the Orange Pi PC
+board and provides a fully working system with serial console, networking and storage.
+
+Currently NetBSD 9.0 is in testing, but release candidate 1 can be started
+successfully on the Orange Pi PC machine. Get the 'evbarm-earmv7hf' based image from:
+
+  https://cdn.netbsd.org/pub/NetBSD/NetBSD-9.0_RC1/evbarm-earmv7hf/binary/gzimg/armv7.img.gz
+
+The image requires manually installing U-Boot in the image. Build U-Boot with
+the orangepi_pc_defconfig configuration as described in the previous section.
+Next, unzip the NetBSD image and write the U-Boot binary including SPL using:
+
+  $ gunzip armv7.img.gz
+  $ dd if=/path/to/u-boot-sunxi-with-spl.bin of=armv7.img bs=1024 seek=8 conv=notrunc
+
+Start the machine using the following command:
+
+  $ qemu-system-arm -M orangepi-pc -nic user -nographic \
+        -sd armv7.img
+
+At the U-Boot stage, interrupt the automatic boot process by pressing a key
+and set the following environment variables before booting:
+
+  => setenv bootargs root=ld0a
+  => setenv kernel netbsd-GENERIC.ub
+  => setenv fdtfile dtb/sun8i-h3-orangepi-pc.dtb
+  => setenv bootcmd 'fatload mmc 0:1 ${kernel_addr_r} ${kernel}; fatload mmc 0:1 ${fdt_addr_r} ${fdtfile}; fdt addr ${fdt_addr_r}; bootm ${kernel_addr_r} - ${fdt_addr_r}'
+
+Optionally you may save the environment variables to SD card with 'saveenv'.
+To continue booting simply give the 'boot' command and NetBSD boots.
+
+Orange Pi PC acceptance tests
+-----------------------------
+
+The Orange Pi PC machine has several acceptance tests included.
+To run the whole set of tests, build QEMU from source and simply
+provide the following command:
+
+  $ AVOCADO_ALLOW_LARGE_STORAGE=yes avocado --show=app,console run \
+     -t machine:orangepi-pc tests/acceptance/boot_linux_console.py
+
diff --git a/MAINTAINERS b/MAINTAINERS
index e99797eec9..8b7096070c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -488,6 +488,7 @@  S: Maintained
 F: hw/*/allwinner-h3*
 F: include/hw/*/allwinner-h3*
 F: hw/arm/orangepi.c
+F: docs/orangepi.rst
 
 ARM PrimeCell and CMSDK devices
 M: Peter Maydell <peter.maydell@linaro.org>