/iptsd

Userspace daemon for Intel Precise Touch & Stylus

Primary LanguageCGNU General Public License v2.0GPL-2.0

Intel Precise Touch & Stylus

This is the userspace part of IPTS (Intel Precise Touch & Stylus) for Linux.

With IPTS the Intel Management Engine acts as an interface for a touch controller, returning raw capacitive touch data. This data is processed outside of the ME and then relayed into the HID / input subsystem of the OS.

This daemon relies on a kernel driver that can be found here: https://github.com/linux-surface/intel-precise-touch

The driver will establish and manage the connection to the IPTS hardware. It will also set up an API that can be used by userspace to read the touch data from IPTS.

The daemon will connect to the IPTS UAPI and start reading data. It will parse the data, and generate input events using uinput devices. The reason for doing this in userspace is that parsing the data requires floating points, which are not allowed in the kernel.

What is working?

  • MS Surface Gen 4-6:
    • Stylus Input
    • Multitouch Finger Input
  • MS Surface Gen 7:
    • Singletouch Finger Input
  • HP Spectre 13 x2 (only non-surface device to use IPTS)
    • Entirely untested

What doesn't work?

  • MS Surface Gen 4-6:
    • Multitouch pressure / contact area calculation
    • Finger tracking can glitch when pressing hard on the display
  • MS Surface Gen 7:
    • Multitouch Input
    • Stylus Input
  • HP Spectre 13 x2
    • Entirely untested

NOTE: The multitouch code has not been tested on all devices. It is very likely that it will still need adjustments to run correctly on some devices. If you have a device with IPTS and want to test it, feel free to open an issue or join ##linux-surface on Freenode IRC and get in touch.

Tested Devices:

  • Surface Book 1
  • Surface Book 2 (13" and 15")
  • Surface Pro 4 (1B96:006A variant)
  • Surface Pro 5
  • Surface Pro 6

Building

You need to install git, a c compiler, meson, ninja through your distributions package manager.

We are using libinih to parse configuration files. You should install it if your distribution already packages it. All the major distros have it in their repos already.

$ sudo apt install libinih1 libinih-dev
$ sudo pacman -S libinih
$ sudo dnf install inih inih-devel
$ sudo zypper install libinih0 libinih-devel

If libinih is not found on your system, a copy will be downloaded and included automatically.

Use meson and ninja to build iptsd, and then run it with sudo.

$ git clone https://github.com/linux-surface/iptsd
$ cd iptsd
$ meson build
$ ninja -C build
$ sudo ./build/iptsd

You need to have the latest UAPI version of the IPTS kernel driver installed. All recent linux-surface kernels already include this. To check if you have the correct driver installed and loaded, check if a file called /dev/ipts/0 exists.

$ ls -l /dev/ipts/

Installing

Note: iptsd is included as a package in the linux-surface repository. Unless you are doing development, or need the latest version from master, it is recommended to use the version from the repository.

If you want to permanently install the daemon, we provide a systemd service configuration that you can use. If your distro does not use systemd, you will have to write your own definition, but it shouldn't be too hard.

Patches with support for other service managers are welcome!

You need to run the steps from "Building" first.

$ sudo cp ./build/iptsd /usr/bin/
$ sudo cp ./etc/systemd/iptsd.service /etc/systemd/system/
$ sudo cp ./etc/udev/50-ipts.rules /etc/udev/rules.d/
$ sudo cp -r ./config/ /usr/share/ipts
$ sudo systemctl daemon-reload
$ sudo systemctl enable --now iptsd