293 lines
9.9 KiB
ReStructuredText
293 lines
9.9 KiB
ReStructuredText
![]() |
.. include:: <isonum.txt>
|
||
|
|
||
|
===================
|
||
|
Linux Input drivers
|
||
|
===================
|
||
|
|
||
|
:Copyright: |copy| 1999-2001 Vojtech Pavlik <vojtech@ucw.cz> - Sponsored by SuSE
|
||
|
|
||
|
Should you need to contact me, the author, you can do so either by e-mail
|
||
![]() |
- mail your message to <vojtech@ucw.cz>, or by paper mail: Vojtech Pavlik,
|
||
|
Simunkova 1594, Prague 8, 182 00 Czech Republic
|
||
|
|
||
![]() |
Introduction
|
||
|
============
|
||
|
|
||
|
This is a collection of drivers that is designed to support all input
|
||
![]() |
devices under Linux. While it is currently used only on for USB input
|
||
|
devices, future use (say 2.5/2.6) is expected to expand to replace
|
||
|
most of the existing input system, which is why it lives in
|
||
|
drivers/input/ instead of drivers/usb/.
|
||
|
|
||
![]() |
The centre of the input drivers is the input module, which must be
|
||
![]() |
loaded before any other of the input modules - it serves as a way of
|
||
|
communication between two groups of modules:
|
||
|
|
||
![]() |
Device drivers
|
||
|
--------------
|
||
|
|
||
|
These modules talk to the hardware (for example via USB), and provide
|
||
![]() |
events (keystrokes, mouse movements) to the input module.
|
||
|
|
||
![]() |
Event handlers
|
||
|
--------------
|
||
|
|
||
|
These modules get events from input and pass them where needed via
|
||
![]() |
various interfaces - keystrokes to the kernel, mouse movements via a
|
||
|
simulated PS/2 interface to GPM and X and so on.
|
||
|
|
||
![]() |
Simple Usage
|
||
|
============
|
||
|
|
||
|
For the most usual configuration, with one USB mouse and one USB keyboard,
|
||
![]() |
you'll have to load the following modules (or have them built in to the
|
||
![]() |
kernel)::
|
||
![]() |
|
||
|
input
|
||
|
mousedev
|
||
|
keybdev
|
||
|
usbcore
|
||
|
uhci_hcd or ohci_hcd or ehci_hcd
|
||
|
usbhid
|
||
|
|
||
![]() |
After this, the USB keyboard will work straight away, and the USB mouse
|
||
|
will be available as a character device on major 13, minor 63::
|
||
![]() |
|
||
|
crw-r--r-- 1 root root 13, 63 Mar 28 22:45 mice
|
||
|
|
||
![]() |
This device has to be created.
|
||
|
|
||
|
The commands to create it by hand are::
|
||
![]() |
|
||
|
cd /dev
|
||
|
mkdir input
|
||
|
mknod input/mice c 13 63
|
||
|
|
||
![]() |
After that you have to point GPM (the textmode mouse cut&paste tool) and
|
||
|
XFree to this device to use it - GPM should be called like::
|
||
![]() |
|
||
|
gpm -t ps2 -m /dev/input/mice
|
||
|
|
||
![]() |
And in X::
|
||
![]() |
|
||
|
Section "Pointer"
|
||
|
Protocol "ImPS/2"
|
||
|
Device "/dev/input/mice"
|
||
|
ZAxisMapping 4 5
|
||
|
EndSection
|
||
|
|
||
![]() |
When you do all of the above, you can use your USB mouse and keyboard.
|
||
![]() |
|
||
![]() |
Detailed Description
|
||
|
====================
|
||
|
|
||
|
Device drivers
|
||
|
--------------
|
||
|
|
||
|
Device drivers are the modules that generate events. The events are
|
||
![]() |
however not useful without being handled, so you also will need to use some
|
||
|
of the modules from section 3.2.
|
||
|
|
||
![]() |
usbhid
|
||
|
~~~~~~
|
||
|
|
||
|
usbhid is the largest and most complex driver of the whole suite. It
|
||
![]() |
handles all HID devices, and because there is a very wide variety of them,
|
||
|
and because the USB HID specification isn't simple, it needs to be this big.
|
||
|
|
||
![]() |
Currently, it handles USB mice, joysticks, gamepads, steering wheels
|
||
![]() |
keyboards, trackballs and digitizers.
|
||
|
|
||
![]() |
However, USB uses HID also for monitor controls, speaker controls, UPSs,
|
||
![]() |
LCDs and many other purposes.
|
||
|
|
||
![]() |
The monitor and speaker controls should be easy to add to the hid/input
|
||
![]() |
interface, but for the UPSs and LCDs it doesn't make much sense. For this,
|
||
![]() |
the hiddev interface was designed. See Documentation/hid/hiddev.txt
|
||
![]() |
for more information about it.
|
||
|
|
||
![]() |
The usage of the usbhid module is very simple, it takes no parameters,
|
||
![]() |
detects everything automatically and when a HID device is inserted, it
|
||
|
detects it appropriately.
|
||
|
|
||
![]() |
However, because the devices vary wildly, you might happen to have a
|
||
![]() |
device that doesn't work well. In that case #define DEBUG at the beginning
|
||
|
of hid-core.c and send me the syslog traces.
|
||
|
|
||
![]() |
usbmouse
|
||
|
~~~~~~~~
|
||
|
|
||
|
For embedded systems, for mice with broken HID descriptors and just any
|
||
![]() |
other use when the big usbhid wouldn't be a good choice, there is the
|
||
|
usbmouse driver. It handles USB mice only. It uses a simpler HIDBP
|
||
|
protocol. This also means the mice must support this simpler protocol. Not
|
||
|
all do. If you don't have any strong reason to use this module, use usbhid
|
||
|
instead.
|
||
|
|
||
![]() |
usbkbd
|
||
|
~~~~~~
|
||
|
|
||
|
Much like usbmouse, this module talks to keyboards with a simplified
|
||
![]() |
HIDBP protocol. It's smaller, but doesn't support any extra special keys.
|
||
|
Use usbhid instead if there isn't any special reason to use this.
|
||
|
|
||
![]() |
wacom
|
||
|
~~~~~
|
||
|
|
||
|
This is a driver for Wacom Graphire and Intuos tablets. Not for Wacom
|
||
![]() |
PenPartner, that one is handled by the HID driver. Although the Intuos and
|
||
|
Graphire tablets claim that they are HID tablets as well, they are not and
|
||
|
thus need this specific driver.
|
||
|
|
||
![]() |
iforce
|
||
|
~~~~~~
|
||
|
|
||
|
A driver for I-Force joysticks and wheels, both over USB and RS232.
|
||
![]() |
It includes ForceFeedback support now, even though Immersion
|
||
|
Corp. considers the protocol a trade secret and won't disclose a word
|
||
![]() |
about it.
|
||
|
|
||
|
Event handlers
|
||
|
--------------
|
||
![]() |
|
||
![]() |
Event handlers distribute the events from the devices to userland and
|
||
![]() |
kernel, as needed.
|
||
|
|
||
![]() |
keybdev
|
||
|
~~~~~~~
|
||
|
|
||
|
keybdev is currently a rather ugly hack that translates the input
|
||
![]() |
events into architecture-specific keyboard raw mode (Xlated AT Set2 on
|
||
|
x86), and passes them into the handle_scancode function of the
|
||
|
keyboard.c module. This works well enough on all architectures that
|
||
|
keybdev can generate rawmode on, other architectures can be added to
|
||
|
it.
|
||
|
|
||
![]() |
The right way would be to pass the events to keyboard.c directly,
|
||
![]() |
best if keyboard.c would itself be an event handler. This is done in
|
||
![]() |
the input patch, available on the webpage mentioned below.
|
||
![]() |
|
||
![]() |
mousedev
|
||
|
~~~~~~~~
|
||
|
|
||
|
mousedev is also a hack to make programs that use mouse input
|
||
![]() |
work. It takes events from either mice or digitizers/tablets and makes
|
||
|
a PS/2-style (a la /dev/psaux) mouse device available to the
|
||
|
userland. Ideally, the programs could use a more reasonable interface,
|
||
|
for example evdev
|
||
|
|
||
![]() |
Mousedev devices in /dev/input (as shown above) are::
|
||
![]() |
|
||
|
crw-r--r-- 1 root root 13, 32 Mar 28 22:45 mouse0
|
||
|
crw-r--r-- 1 root root 13, 33 Mar 29 00:41 mouse1
|
||
|
crw-r--r-- 1 root root 13, 34 Mar 29 00:41 mouse2
|
||
|
crw-r--r-- 1 root root 13, 35 Apr 1 10:50 mouse3
|
||
|
...
|
||
|
...
|
||
|
crw-r--r-- 1 root root 13, 62 Apr 1 10:50 mouse30
|
||
|
crw-r--r-- 1 root root 13, 63 Apr 1 10:50 mice
|
||
|
|
||
![]() |
Each ``mouse`` device is assigned to a single mouse or digitizer, except
|
||
|
the last one - ``mice``. This single character device is shared by all
|
||
![]() |
mice and digitizers, and even if none are connected, the device is
|
||
|
present. This is useful for hotplugging USB mice, so that programs
|
||
|
can open the device even when no mice are present.
|
||
|
|
||
![]() |
CONFIG_INPUT_MOUSEDEV_SCREEN_[XY] in the kernel configuration are
|
||
![]() |
the size of your screen (in pixels) in XFree86. This is needed if you
|
||
|
want to use your digitizer in X, because its movement is sent to X
|
||
|
via a virtual PS/2 mouse and thus needs to be scaled
|
||
|
accordingly. These values won't be used if you use a mouse only.
|
||
|
|
||
![]() |
Mousedev will generate either PS/2, ImPS/2 (Microsoft IntelliMouse) or
|
||
![]() |
ExplorerPS/2 (IntelliMouse Explorer) protocols, depending on what the
|
||
|
program reading the data wishes. You can set GPM and X to any of
|
||
|
these. You'll need ImPS/2 if you want to make use of a wheel on a USB
|
||
![]() |
mouse and ExplorerPS/2 if you want to use extra (up to 5) buttons.
|
||
|
|
||
|
joydev
|
||
|
~~~~~~
|
||
![]() |
|
||
![]() |
Joydev implements v0.x and v1.x Linux joystick api, much like
|
||
![]() |
drivers/char/joystick/joystick.c used to in earlier versions. See
|
||
|
joystick-api.txt in the Documentation subdirectory for details. As
|
||
|
soon as any joystick is connected, it can be accessed in /dev/input
|
||
![]() |
on::
|
||
![]() |
|
||
|
crw-r--r-- 1 root root 13, 0 Apr 1 10:50 js0
|
||
|
crw-r--r-- 1 root root 13, 1 Apr 1 10:50 js1
|
||
|
crw-r--r-- 1 root root 13, 2 Apr 1 10:50 js2
|
||
|
crw-r--r-- 1 root root 13, 3 Apr 1 10:50 js3
|
||
|
...
|
||
|
|
||
|
And so on up to js31.
|
||
|
|
||
![]() |
evdev
|
||
|
~~~~~
|
||
|
|
||
|
evdev is the generic input event interface. It passes the events
|
||
![]() |
generated in the kernel straight to the program, with timestamps. The
|
||
![]() |
API is still evolving, but should be usable now. It's described in
|
||
![]() |
section 5.
|
||
![]() |
|
||
![]() |
This should be the way for GPM and X to get keyboard and mouse
|
||
![]() |
events. It allows for multihead in X without any specific multihead
|
||
|
kernel support. The event codes are the same on all architectures and
|
||
|
are hardware independent.
|
||
|
|
||
![]() |
The devices are in /dev/input::
|
||
![]() |
|
||
|
crw-r--r-- 1 root root 13, 64 Apr 1 10:49 event0
|
||
|
crw-r--r-- 1 root root 13, 65 Apr 1 10:50 event1
|
||
|
crw-r--r-- 1 root root 13, 66 Apr 1 10:50 event2
|
||
|
crw-r--r-- 1 root root 13, 67 Apr 1 10:50 event3
|
||
|
...
|
||
|
|
||
|
And so on up to event31.
|
||
|
|
||
![]() |
Verifying if it works
|
||
|
=====================
|
||
|
|
||
|
Typing a couple keys on the keyboard should be enough to check that
|
||
![]() |
a USB keyboard works and is correctly connected to the kernel keyboard
|
||
![]() |
driver.
|
||
![]() |
|
||
![]() |
Doing a ``cat /dev/input/mouse0`` (c, 13, 32) will verify that a mouse
|
||
![]() |
is also emulated; characters should appear if you move it.
|
||
![]() |
|
||
![]() |
You can test the joystick emulation with the ``jstest`` utility,
|
||
![]() |
available in the joystick package (see Documentation/input/joystick.txt).
|
||
|
|
||
![]() |
You can test the event devices with the ``evtest`` utility available
|
||
![]() |
in the LinuxConsole project CVS archive (see the URL below).
|
||
|
|
||
![]() |
Event interface
|
||
|
===============
|
||
|
|
||
|
Should you want to add event device support into any application (X, gpm,
|
||
![]() |
svgalib ...) I <vojtech@ucw.cz> will be happy to provide you any help I
|
||
|
can. Here goes a description of the current state of things, which is going
|
||
|
to be extended, but not changed incompatibly as time goes:
|
||
|
|
||
![]() |
You can use blocking and nonblocking reads, also select() on the
|
||
![]() |
/dev/input/eventX devices, and you'll always get a whole number of input
|
||
![]() |
events on a read. Their layout is::
|
||
![]() |
|
||
![]() |
struct input_event {
|
||
|
struct timeval time;
|
||
|
unsigned short type;
|
||
|
unsigned short code;
|
||
|
unsigned int value;
|
||
|
};
|
||
![]() |
|
||
![]() |
``time`` is the timestamp, it returns the time at which the event happened.
|
||
![]() |
Type is for example EV_REL for relative moment, EV_KEY for a keypress or
|
||
![]() |
release. More types are defined in include/uapi/linux/input-event-codes.h.
|
||
![]() |
|
||
![]() |
``code`` is event code, for example REL_X or KEY_BACKSPACE, again a complete
|
||
![]() |
list is in include/uapi/linux/input-event-codes.h.
|
||
![]() |
|
||
![]() |
``value`` is the value the event carries. Either a relative change for
|
||
![]() |
EV_REL, absolute new value for EV_ABS (joysticks ...), or 0 for EV_KEY for
|
||
|
release, 1 for keypress and 2 for autorepeat.
|