User-space Keyboard input?

User-space Keyboard input?

[Mario Lang]

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Hi.

I'm working on BRLTTY[1], a user-space daemon which handles braille displays
on UNIX platforms.  One of our display drivers recently gained the ability
to receive (set 2) scancodes from a keyboard connected directly to the display.
This is a very cool feature, since the display in question has
a bluetooth interface, making it effectively into a complete wireless
terminal (input and output through the same connection).

However, this creates some problems.  First of all, we now have to deal
with keyboard layouts.  Additionally, since we currently insert via
TIOCSTI I think this might get problematic as soon as one switches
to an X Windows console and modifiers come into play.

Does anyone know (and can point me into the right direction) if
Linux has some mechanism to allow for user-space keyboard data to
be processed by the kernel as if it were received from the system
keyboard?  I.e., keyboard layout would be handled by the same
mapping which is configured for the system.

-- 
Thanks,
  Mario

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Re: User-space Keyboard input?

[Marcel Holtmann]

Hi Mario,

> I'm working on BRLTTY[1], a user-space daemon which handles braille displays
> on UNIX platforms.  One of our display drivers recently gained the ability
> to receive (set 2) scancodes from a keyboard connected directly to the display.
> This is a very cool feature, since the display in question has
> a bluetooth interface, making it effectively into a complete wireless
> terminal (input and output through the same connection).

tell me more about this Bluetooth device.

> However, this creates some problems.  First of all, we now have to deal
> with keyboard layouts.  Additionally, since we currently insert via
> TIOCSTI I think this might get problematic as soon as one switches
> to an X Windows console and modifiers come into play.
> 
> Does anyone know (and can point me into the right direction) if
> Linux has some mechanism to allow for user-space keyboard data to
> be processed by the kernel as if it were received from the system
> keyboard?  I.e., keyboard layout would be handled by the same
> mapping which is configured for the system.

Take a look at the user level driver support (uinput).

Regards

Marcel

Re: User-space Keyboard input?

[Marcel Holtmann]

Hi Mario,

> >> I'm working on BRLTTY[1], a user-space daemon which handles braille displays
> >> on UNIX platforms.  One of our display drivers recently gained the ability
> >> to receive (set 2) scancodes from a keyboard connected directly to the display.
> >> This is a very cool feature, since the display in question has
> >> a bluetooth interface, making it effectively into a complete wireless
> >> terminal (input and output through the same connection).
> >
> > tell me more about this Bluetooth device.
> 
> Its a Braille Star 40 from HandyTech.  Originally sold, the device had two
> alternative ports, serial or USB.  They recently offered an additional
> bluetooth module.  I don't really know what you want to know though :-).

what kind of profiles do this Bluetooth module support? Is it a HID
compatible device or do it uses a vendor specific protocol? Do you
tested it with Linux?

> >> However, this creates some problems.  First of all, we now have to deal
> >> with keyboard layouts.  Additionally, since we currently insert via
> >> TIOCSTI I think this might get problematic as soon as one switches
> >> to an X Windows console and modifiers come into play.
> >> 
> >> Does anyone know (and can point me into the right direction) if
> >> Linux has some mechanism to allow for user-space keyboard data to
> >> be processed by the kernel as if it were received from the system
> >> keyboard?  I.e., keyboard layout would be handled by the same
> >> mapping which is configured for the system.
> >
> > Take a look at the user level driver support (uinput).
> Yup, thats it, thanks.  Now I just need to find some example code on how
> to use it :-).

The BlueZ CVS repository utils2 contains the old bthid code that makes
use of the uinput kernel module.

Regards

Marcel

Re: User-space Keyboard input?

[Samuel Thibault]

Hi Mario,

About modifiers, I submitted a patch to Dave to handle them
properly.

But ascii to scancode translation still depends on scancode to ascii
translation performed by the kernel indeed and the question still
applies. I'll have a look at uinput.

Regards,
Samuel

Re: User-space Keyboard input?

[Mario Lang]

Samuel Thibault <samuel.thibault@ens-lyon.org> writes:

> About modifiers, I submitted a patch to Dave to handle them
> properly.
>
> But ascii to scancode translation still depends on scancode to ascii
> translation performed by the kernel indeed and the question still
> applies. I'll have a look at uinput.

uinput support is now committed to scr_linux.c.  I am using the exernal
keyboard of my bluetooth capable braille display to type this email already
via uinput :-).  The same layout is used as is configured on the box.
Our generic AT2 support maps to VAL_PASSKEY commands and
the AT2 support for Linux maps the AT2 scancode set to what Linux internally
uses for scancodes (a sort of XT scancode set, but not really).


-- 
CYa,
  Mario