# NOTE
# I am still finishing changes for Ubuntu 24.04.1

This folder contains a `make-trees` script that can build device tree source (`.dts`) files with the correct upstream headers.

## Preparation / requirements

### Compile and make tooling
You need `build-essential` installed:
```console
apt install build-essential
```
*This will take a while.. as will most commands described here!*

By default the Device Tree compiler (`/usr/bin/dtc`) should already be installed in Ubuntu server, as should the linux-headers for the kernel.

### Enable source repos:
As root edit the file: `/etc/apt/sources.list.d/ubuntu.sources`

There should be two repo definitions, find the lines in them that say:
```console
Types: deb
```
And add `deb-src` so it now says:
```console
Types: deb deb-src
```
Save and exit editor.

Run
```console
sudo apt update
```
You should see a load of new (source) repos being updated, it is slow, let it finish.

## Install the linux sources
This should be done as a normal user
- Note that the command used here `apt source` will download the sources to the current working folder, not a fixed location.

We download the sources into the [sources](../sources) repo in this folder:
```console
cd source
apt source linux-riscv
```
Go for a coffee.. ignore the 'git clone' suggestion.
- This will use ~1.6Gb of space.. so be prepared.

# Updating sources
If you re-run the `apt source` command in this folder it will only download and update as needed, but is still somewhat slow since it verifies the existing downloads when updating.

-------------------------------------------
# Building the device tree(s)

As a normal user (the same user used to fetch the sources above) cd to this (`build-trees`) folder.

#### Terms
* `.dts` is a top-level Device Tree Source file.
* `.dtsi` is a include file for the `.dts`
* `.dtb` is the binary compiled device tree, this is what we are building here, and is supplied to the kernel at boot time.

## device tree sources
By default the standard `sun20i-d1-mangopi-mq-pro.dts` file from the Ubuntu source is linked here. 

Rather than modifying the default tree you should copy it to a custom name, eg 'my-project-mqpro.dts'. Or you can copy in examples from the [alt-trees](../alt-trees/) folder.

A full-on tutorial for device tree editing is far beyond the scope of both this document and author.
* The examples show some simple custom modifications.
* The upstream sources do not define all possible pin mappings, so note how additional pin mappings are added as needed to the custom trees.

## Compile the mq-pro dts with the current kernel headers

To compile all the includes and sources simply run `make-trees`.

This will:
* Create an output folder named after the kernel version
* Pre-compile all the source and include files in the current folder into the output folder using the correct kernel headers.
* In the output folder it then compiles *all* the `.dts` files present, and prefixes the output `.dtb` files with the kernel version.

```console
ubuntu@ubuntu:~/MQ-Pro-IO/build-trees$ ./make_dtb.sh
Compiling against headers for 6.8.0-41-generic
Creating new build directory: 6.8.0-41-generic
Precompiling all includes in build root into 6.8.0-41-generic build directory
  sun20i-common-regulators.dtsi -> 6.8.0-41-generic/sun20i-common-regulators.dtsi
  sun20i-d1.dtsi -> 6.8.0-41-generic/sun20i-d1.dtsi
  sun20i-d1s.dtsi -> 6.8.0-41-generic/sun20i-d1s.dtsi
  sunxi-d1-t113.dtsi -> 6.8.0-41-generic/sunxi-d1-t113.dtsi
  sunxi-d1s-t113.dtsi -> 6.8.0-41-generic/sunxi-d1s-t113.dtsi
Precompiling all sources in build root into 6.8.0-41-generic build directory
  my-project-mqpro.dts -> 6.8.0-41-generic/my-project-mqpro.dts
  sun20i-d1-mangopi-mq-pro.dts -> 6.8.0-41-generic/sun20i-d1-mangopi-mq-pro.dts
Compiling all device tree sources in 6.8.0-41-generic build directory
  6.8.0-41-generic/my-project-mqpro.dts -> 6.8.0-41-generic/6.8.0-41-generic-my-project-mqpro.dtb
  6.8.0-41-generic/sun20i-d1-mangopi-mq-pro.dts -> 6.8.0-41-generic/6.8.0-41-generic-sun20i-d1-mangopi-mq-pro.dtb
```

-----------------------

# Test Installing self-built DTB's

### Move dtb into the boot tree
* move the `.dtb` file into the `/boot` folder: `sudo mv 6.8.0-41-generic-my-project-mqpro.dtb /boot/dtbs`
* make a soft link in `/boot` to this: `sudo ln -s dtbs/6.8.0-41-generic-my-project-mqpro.dtb /boot/dtb-mqpro`

### Set up Grub to test boot the new DTB
Initially we will test the new dtb:
* backup the grub config: `sudo cp /etc/grub/grub.cfg /etc/grub/grub.cfg.generic-dtb`
* `sudo vi /etc/grub/grub.cfg`  (or use nano if you prefer)
  Find the 1st `menuentry` section (the default Ubuntu one) and edit the `devicetree` line to look like:
  `devicetree      /boot/dtb-mqpro`
* Reboot (`sudo reboot`) (remember the mq-pro is sloooow to reboot ;-) )
* If the reboot fails you can either attach a serial adapter to the GPIO pins and select the fallback kernel from the advanced options menu, and then restore the grub config backup once logged in.
  Or (if no serial available) remove the SD card, mount it on another computer and restore the file there.

### Quick check that we have the correct device tree!
`dtc -I fs /sys/firmware/devicetree/base | grep 'model'`
* ignore all the 'not a phandle reference' warnings
* you should see `model = "MangoPi MQ Pro"` at the end

----------------------------------------------------
## Pin Map tool
After rebooting you can run **list-pins.py** (see below) to verify the new mappings.

If you have errors rebooting (maybe a corrupt file if you rebuilt it etc..) you need to either boot using a USB serial adapter on the console pins and select the recovery image,  or, in grub, edit the command and revert to the generic `/boot/dtb`.
As a last resort you may have to remove the SD card, mount the `/boot` partition and edit `grub/grub.cfg` there.
* !! The 'default' dtb supplied by ubuntu should always be softlinked as `/boot/dtb`, so putting `devicetree      /boot/dtb` in grub in place of the custom `.dtb` should work and is predictable (no version numbers etc).

## Examining the DTB pin mappings:
In the [tools](../tools) folder there is a python script called `list-pins.py`.

To run the pin list tool you need to be in the tools directory, then run:
```console
python3 list-pins.py MangoPi-MQ-Pro
```
* The script requires root acces (via sudo) to read the pin maps.
* Running the script produces the same map I use in this documentation.
* The data used to assemble the `.gpio` map files identifies which interface a pin is attached to, but not it's specific function for the interface.
  * eg it can say 'pinX and pinY are mapped to UART2', but cannot identify which pin is the TX and which is the RX; a limitation of the data, my apologies..
  * You therefore need to reference the [D1 pin mapping table](../reference/d1-pins.pdf) to get the exact functions for pins when running this for yourself.
* The README files uploaded for alternate device trees *have been manually edited* to note full pin function for convenience.
-----------------------------------------------------

# Making Permanent:
<this needs expanding/fixing>
<can we do this via flash-kernel? it appears to have an 'override' dtb file config. ?????>

## Old method

(As Root) Edit: `/etc/grub.d/10_linux` line 458 to say:
```
  for i in "dtb-mqpro" "dtb-${version}" "dtb-${alt_version}" "dtb"; do
```

Note that we are adding `dtb-mqpro` to the start of this list, this is the 'search list' for the DTB files, the full section reads:
```bash
  dtb=
  for i in "dtb-mqpro" "dtb-${version}" "dtb-${alt_version}" "dtb"; do
    if test -e "${dirname}/${i}" ; then
      dtb="$i"
      break
    fi
  done
```
When Grub next rebuilds it *should* make the new DTB the default for all entries now. (this is untested, as of this writing there have not been any kernel upgrades to test them on)


# references/links:
https://manpages.ubuntu.com/manpages/focal/man1/dtc.1.html
https://forum.armbian.com/topic/29626-mango-pi-mq-pro-d1-device-tree-try-to-okay-serial/
https://github.com/torvalds/linux/tree/master/arch/riscv/boot/dts/allwinner
https://github.com/ners/MangoPi/tree/d2589d8211a2f9ae57d88f2e2c4d6a449d668f9e/MangoPi/linux/arch/riscv/boot/dts/allwinner
DTS version that is used in the official armbian image?
https://github.com/smaeul/u-boot/tree/329e94f16ff84f9cf9341f8dfdff7af1b1e6ee9a/arch/riscv/dts