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diff --git a/Documentation/input/input.rst b/Documentation/input/input.rst index ac7669ad3e76..3b3a22975106 100644 --- a/Documentation/input/input.rst +++ b/Documentation/input/input.rst @@ -1,25 +1,20 @@ .. include:: <isonum.txt> -=================== -Linux Input drivers -=================== +============ +Introduction +============ :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 +Architecture ============ -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/. +Input subsystem a collection of drivers that is designed to support +all input devices under Linux. Most of the drivers reside in +drivers/input, although quite a few live in drivers/hid and +drivers/platform. -The centre of the input drivers is the input module, which must be +The core of the input subsystem 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: @@ -32,9 +27,9 @@ 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. +These modules get events from input core 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 ============ @@ -45,19 +40,18 @@ kernel):: input mousedev - keybdev usbcore uhci_hcd or ohci_hcd or ehci_hcd usbhid + hid_generic 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:: +This device usually created automatically by the system. The commands +to create it by hand are:: cd /dev mkdir input @@ -81,100 +75,50 @@ When you do all of the above, you can use your USB mouse and keyboard. Detailed Description ==================== -Device drivers +Event handlers -------------- -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. +Event handlers distribute the events from the devices to userspace and +in-kernel consumers, as needed. -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 +evdev ~~~~~ -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. +``evdev`` is the generic input event interface. It passes the events +generated in the kernel straight to the program, with timestamps. The +event codes are the same on all architectures and are hardware +independent. -iforce -~~~~~~ +This is the preferred interface for userspace to consume user +input, and all clients are encouraged to use it. -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. +See :ref:`event-interface` for notes on API. -Event handlers --------------- +The devices are in /dev/input:: -Event handlers distribute the events from the devices to userland and -kernel, as needed. + 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 + ... -keybdev -~~~~~~~ +There are two ranges of minors: 64 through 95 is the static legacy +range. If there are more than 32 input devices in a system, additional +evdev nodes are created with minors starting with 256. -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. +keyboard +~~~~~~~~ -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. +``keyboard`` is in-kernel input handler ad is a part of VT code. It +consumes keyboard keystrokes and handles user input for VT consoles. mousedev ~~~~~~~~ -mousedev is also a hack to make programs that use mouse input +``mousedev`` is a hack to make legacy 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 +userland. Mousedev devices in /dev/input (as shown above) are:: @@ -190,8 +134,9 @@ Mousedev devices in /dev/input (as shown above) are:: 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. +present. This is useful for hotplugging USB mice, so that older programs +that do not handle hotplug 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 @@ -208,11 +153,10 @@ 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:: +``joydev`` implements v0.x and v1.x Linux joystick API. See +:ref:`joystick-api` 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 @@ -220,56 +164,99 @@ on:: crw-r--r-- 1 root root 13, 3 Apr 1 10:50 js3 ... -And so on up to js31. +And so on up to js31 in legacy range, and additional nodes with minors +above 256 if there are more joystick devices. -evdev -~~~~~ +Device drivers +-------------- -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. +Device drivers are the modules that generate events. -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. +hid-generic +~~~~~~~~~~~ -The devices are in /dev/input:: +``hid-generic`` is one of 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. - 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 - ... +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. -And so on up to event31. +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. + +psmouse +~~~~~~~ + +This is driver for all flavors of pointing devices using PS/2 +protocol, including Synaptics and ALPS touchpads, Intellimouse +Explorer devices, Logitech PS/2 mice and so on. + +atkbd +~~~~~ + +This is driver for PS/2 (AT) keyboards. + +iforce +~~~~~~ + +A driver for I-Force joysticks and wheels, both over USB and RS232. +It includes Force Feedback support now, even though Immersion +Corp. considers the protocol a trade secret and won't disclose a word +about it. 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 +a 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). +available in the joystick package (see :ref:`joystick-doc`). -You can test the event devices with the ``evtest`` utility available -in the LinuxConsole project CVS archive (see the URL below). +You can test the event devices with the ``evtest`` utility. + +.. _event-interface: 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 +You can use blocking and nonblocking reads, and 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:: @@ -290,3 +277,5 @@ 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. + +See :ref:`input-event-codes` for more information about various even codes. |