Add nix run visionFive2_* commands

visionfive2/README.md

@@ -0,0 +1,61 @@
+
+# VisionFive 2
+
+As of writing, VisionFive 2 support is quite experimental.
+
+## Flash the bootloader via serial connection
+
+This step may be optional.
+
+Make the serial connection according to the section "Recovering the Bootloader" in <https://doc-en.rvspace.org/VisionFive2/PDF/VisionFive2_QSG.pdf>.
+Flip the tiny switches towards the H (as opposed to L) marking on the PCB (towards edge of the board) as described that section (Step 2).
+Power up, and assuming your serial device is `/dev/ttyUSB0`, run:
+
+```shellSession
+nix run .#visionFive2_bootloader_recover /dev/ttyUSB0
+```
+
+## Write a bootable SD card
+
+```shellSession
+$ nix build .#images.visionfive2-cross
+```
+
+Insert an SD card of which all contents will be replaced.
+
+These instructions assume your SD card reader is `/dev/mmcblk0`.
+
+Make sure no partitions are mounted.
+
+```shellSession
+$ echo /dev/mmcblk0p*
+$ sudo umount /dev/mmcblk0p1
+$ sudo umount /dev/mmcblk0p2
+... repeat for all partitions
+```
+
+`pv` provides a rough progress indicator based on the compressed size.
+If you don't have `pv`, run in `nix shell nixpkgs#pv` or use `cat` instead.
+
+```shellSession
+$ sudo sh -c 'pv <result/sd-image/nixos-sd-image-*.img.zst | zstd -d | dd of=/dev/mmcblk0'
+$ sync
+```
+
+## Other commands
+
+### Enter the firmware recovery via serial
+
+Prepare as you would for flashing the bootloader, and then:
+
+```shellSession
+nix run .#visionFive2_recovery_start /dev/ttyUSB0
+```
+
+### Establish a serial connection
+
+Compatible with the recovery mode, but also suitable for the Linux terminal
+
+```shellSession
+nix run .#visionFive2_recovery_resume /dev/ttyUSB0
+```