doc: Document Raspberry pi support

Including touchscreen support.

Author: mattiaswal

board/aarch64/README.md

@@ -7,3 +7,48 @@ Board Specific Documentation
 - [Marvell CN9130-CRB](cn9130-crb/)
 - [Microchip SparX-5i PCB135 (eMMC)](sparx5-pcb135/)
 - [NanoPi R2S](r2s/)
+- [Raspberry Pi 4 b](#raspberry-pi-4-b)
+
+# Raspberry Pi 4 b
+
+## Support level
+Full support for base board but not any extension board on the
+GPIOs.
+
+### Touch screen
+The [Raspberry Pi touch display v1][RPI-TOUCH] is supported, including
+touch functionality. There are multiple touchscreens on the market for
+Raspberry Pi, but only the official (first version with 800x480
+resolution) is currently supported. Infix supplies all drivers
+required to utilize the hardware, but you need to add the actual
+graphical application in a container.
+
+There are some important considerations you need to know about when
+using Infix for graphical applications. The container needs access to
+/dev/dri/ to be able to access the graphics card, and it also needs
+access to /run/udev to be able to find the input devices.
+
+Example of running Doom in Infix:
+
+```cli
+	admin@example:/> configure
+	admin@example:/config/> edit container doom
+	admin@example:/config/container/doom/> set image docker://mattiaswal/alpine-doom:latest
+	admin@example:/config/container/doom/> set privileged
+	admin@example:/config/container/doom/> edit mount udev
+	admin@example:/config/container/doom/mount/udev/> set type bind
+	admin@example:/config/container/doom/mount/udev/> set target /run/udev/
+	admin@example:/config/container/doom/mount/udev/> set source /run/udev/
+	admin@example:/config/container/doom/mount/udev/> end
+	admin@example:/config/container/doom/mount/xorg.conf/> set content U2VjdGlvbiAiU2VydmVyTGF5b3V0IgogICAgSWRlbnRpZmllciAiRGVmYXVsdExheW91dCIKICAgIFNjcmVlbiAwICJTY3JlZW4wIiAwIDAKRW5kU2VjdGlvbgpTZWN0aW9uICJEZXZpY2UiCiAgICBJZGVudGlmaWVyICJpTVggTENEIgogICAgRHJpdmVyICJtb2Rlc2V0dGluZyIKICAgIEJ1c0lEICJwbGF0Zm9ybTozMmZjNjAwMC5kaXNwbGF5LWNvbnRyb2xsZXIiCiAgICBPcHRpb24gImttc2RldiIgIi9kZXYvZHJpL2NhcmQxIgpFbmRTZWN0aW9uCgpTZWN0aW9uICJTY3JlZW4iCiAgICBJZGVudGlmaWVyICJTY3JlZW4wIgogICAgRGV2aWNlICJpTVggTENEIgogICAgRGVmYXVsdERlcHRoIDI0CkVuZFNlY3Rpb24KCg==
+	admin@example:/config/container/doom/mount/xorg.conf/> set target /etc/X11/xorg.conf
+	admin@example:/config/container/doom/mount/xorg.conf/> end
+	admin@example:/config/container/doom/> edit volume var
+	admin@example:/config/container/doom/volume/var/> set target /var
+	admin@example:/config/container/doom/volume/var/> leave
+	admin@example:/>
+
+```
+
+
+[RPI-TOUCH]: https://www.raspberrypi.com/products/raspberry-pi-touch-display/