Pinenote DBus Service

A simple DBus service that exposes various controls and settings related to the Pine64 Pinenote via system-wide DBus interface. The service is written in rust and uses the dbus-rs crate (https://github.com/diwic/dbus-rs).

Warning This is my very first rust program and my very first DBus experience. Expect bugs and basically every beginners mistake related to rust and DBus ;-) I would be very grateful to any bug reports and style/programming suggestions!

Requirements and target platform

This program is intended solely to run on the Pine64 Pinenote (arm64) and requires the ebc driver modifications from here to be present:

https://github.com/m-weigand/linux/tree/mw/rk35/ebc-drm-v5-modifications-t1

These modifications are also merged in the user-usable kernel branch found here:

https://github.com/m-weigand/linux/tree/mw/rk35/pinenote-next-t1

Compilation

Compile with:

cargo build

Create a Debian package using cargo-deb:

cargo deb

Installation

Just calling the generated binary should suffice to register the dbus service on org.pinenote.* using the system bus:

• org.pinenote.ebc /ebc for ebc driver control
• org.pinenote.pen /pen for pen button driver control

A systemd unit is also supplied in the systemd_units/ subdirectory and should be the preferred way to start the service.

When generating and using the Debian package the systemd unit is automatically installed, enabled and started.

DBus services on the system bus are subject to security restrictions and require explicit permission setting. This was attempted using the configuration file dbus_security_configuration/pinenote.conf, which should be placed in here /etc/dbus-1/system.d/pinenote.conf (done automatically by the Debian package).

Usage

Please refer to the examples/ subdirectory for usage examples in various languages (shell/dbus-send, python, gjs, rust).

For the impatient, here are a few dbus-send commands:

# trigger full refresh
dbus-send --system --print-reply --dest=org.pinenote.ebc /ebc org.pinenote.ebc.TriggerGlobalRefresh
# set and get waveform used
dbus-send --system --print-reply --dest=org.pinenote.ebc /ebc org.pinenote.ebc.SetDefaultWaveform byte:2
dbus-send --print-reply --system --dest=org.pinenote.ebc /ebc org.pinenote.ebc.GetDefaultWaveform

# initiate a scan for the stylus (buttons). Repeatedly push the buttons
# during the 12-20 seconds scan interval
dbus-send --print-reply --system --dest=org.pinenote.pen /pen org.pinenote.pen.DoScan
dbus-send --print-reply --system --dest=org.pinenote.pen /pen org.pinenote.pen.AutoConnect
# connect to the mac address retrieved by the PenDoScan command
dbus-send --print-reply --system --dest=org.pinenote.pen /pen org.pinenote.pen.SetAddress string:"12:23:45:56:90:4b"
dbus-send --print-reply --system --dest=org.pinenote.pen /pen org.pinenote.pen.ForgetAddress
dbus-send --print-reply --system --dest=org.pinenote.pen /pen org.pinenote.pen.GetAddress
dbus-send --print-reply --system --dest=org.pinenote.pen /pen org.pinenote.pen.GetVersion
dbus-send --print-reply --system --dest=org.pinenote.pen /pen org.pinenote.pen.GetBattery

# travel mode
dbus-send --print-reply --system --dest=org.pinenote.misc /misc org.pinenote.pen.EnableTravelMode

Introspection

dbus-send --print-reply --system --dest=org.pinenote.ebc /ebc org.freedesktop.DBus.Introspectable.Introspect
dbus-send --print-reply --system --dest=org.pinenote.pen /pen org.freedesktop.DBus.Introspectable.Introspect
dbus-send --print-reply --system --dest=org.pinenote.usb /usb org.freedesktop.DBus.Introspectable.Introspect
dbus-send --print-reply --system --dest=org.pinenote.misc /misc org.freedesktop.DBus.Introspectable.Introspect

Some design choices that probably need revising

• At this point getter/setter functions are mostly implemented using dbus methods instead of using dbus properties (some are implement in both ways). While I see the benefits of the properties, I find using them a little bit awkward, especially introspecting them seems complicated. Need to look into this again...
• At the moment changing the waveform and changing the bw_mode parameter both emit the "WaveformChanged" signal. This does not fit. However, I would like to somehow prevent duplicate signals to be emitted. For example, at the moment I'm triggering both one global refresh for changing the waveform and for changing the bw_mode, leading to two refreshes when switching from grayscale to black/white+A2-waveform mode. Probably some kind of combined getter/setter-method+associated signal is the solution here.

License/Copying

The main.rs file started from this dbus-rs example: Based upon https://github.com/diwic/dbus-rs/blob/master/dbus-crossroads/examples/server_cr.rs Unless otherwise noted in the header of a given file, the code is Apache 2.0 / MIT dual licensed, following the licensing scheme of the dbus-rs project.

Copyright of the dbus-rs project: (c) 2014-2018 David Henningsson diwic@ubuntu.com and other contributors

Copyright of the rest: 2022-2024 Maximilian Weigand mweigand@mweigand.net