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• Drivers Ruling Input Devices Input
• Drivers Ruling Input Devices Examples
• Drivers Ruling Input Devices Device
• Drivers Ruling Input Devices
• Drivers Ruling Input Devices Definition

Note

The package provides the installation files for Microsoft USB Input Device Driver version 10.0.4. If the driver is already installed on your system, updating (overwrite-installing) may fix various issues, add new functions, or just upgrade to the available version. The driver uses a 'virtual audio device' instead of an actual hardware-based adapter, and highlights the different aspects of the audio offloading WDM audio driver architecture. Driver developers can use the framework in this sample to provide support for various audio devices without concern for hardware dependencies. Driver Description Download drivers for Toshiba ELAN Input Device input devices (Windows 10 x64), or install DriverPack Solution software for automatic driver download and update Are you tired of looking for the drivers for your devices? The dev-name should be set before registering the input device by the input device driver. It’s a string like ‘Generic button device’ containing a user friendly name of the device. The id. fields contain the bus ID (PCI, USB.), vendor ID and device ID of the device. The bus IDs are defined in input.h.

This topic is for developers who are creating drivers for keyboard and mouse HID clients. If you are looking to fix a mouse or keyboard, see:

This topic discusses keyboard and mouse HID client drivers. Keyboards and mice represent the first set of HID clients that were standardized in the HID Usage tables and implemented in Windows operating systems.

Keyboard and mouse HID client drivers are implemented in the form of HID Mapper Drivers. A HID mapper driver is a kernel-mode WDM filter driver that provides a bidirectional interface for I/O requests between a non-HID Class driver and the HID class driver. The mapper driver maps the I/O requests and data protocols of one to the other.

Windows provides system-supplied HID mapper drivers for HID keyboard, and HID mice devices.

Architecture and overview

The following figure illustrates the system-supplied driver stacks for USB keyboard and mouse/touchpad devices.

The figure above includes the following components:

• KBDHID.sys – HID client mapper driver for keyboards. Converts HID usages into scancodes to interface with the existing keyboard class driver.
• MOUHID.sys – HID client mapper driver for mice/touchpads. Converts HID usages into mouse commands (X/Y, buttons, wheel) to interface with the existing keyboard class driver.
• KBDCLASS.sys – The keyboard class driver maintains functionality for all keyboards and keypads on the system in a secure manner.
• MOUCLASS.sys – The mouse class driver maintains functionality for all mice / touchpads on the system. The driver does support both absolute and relative pointing devices. This is not the driver for touchscreens as that is managed by a different driver in Windows.
• HIDCLASS.sys - The HID class driver. The HID Class driver is the glue between KBDHID.sys and MOUHID.sys HID clients and various transports (USB, Bluetooth, etc).

The system builds the driver stack as follows:

• The transport stack creates a physical device object (PDO) for each HID device attached and loads the appropriate HID transport driver which in turn loads the HID Class Driver.
• The HID class driver creates a PDO for each keyboard or mouse TLC. Complex HID devices (more than 1 TLC) are exposed as multiple PDOs created by HID class driver. For example, a keyboard with an integrated mouse might have one collection for the standard keyboard controls and a different collection for the mouse.
• The keyboard or mouse hid client mapper drivers are loaded on the appropriate FDO.
• The HID mapper drivers create FDOs for keyboard and mouse, and load the class drivers.

Important notes:

• Vendor drivers are not required for keyboards and mice that are compliant with the supported HID Usages and top level collections.
• Vendors may optionally provide filter drivers in the HID stack to alter/enhance the functionality of these specific TLC.
• Vendors should create separate TLCs, that are vendor specific, to exchange vendor proprietary data between their hid client and the device. Avoid using filter drivers unless critical.
• The system opens all keyboard and mouse collections for its exclusive use.
• The system prevents disable/enabling a keyboard.
• The system provides support for horizontal/vertical wheels with smooth scrolling capabilities.

Driver Guidance

Microsoft provides the following guidance for IHVs writing drivers:

1. Driver developers are allowed to add additional drivers in the form of a filter driver or a new HID Client driver. The criteria are described below:

   1. Filters Drivers: Driver developers should ensure that their value-add driver is a filter driver and does not replace (or be used in place of) existing Windows HID drivers in the input stack.

      • Filter drivers are allowed in the following scenarios:
        • As an upper filter to kbdhid/mouhid
        • As an upper filter to kbdclass/mouclass
      • Filter drivers are not recommended as a filter between HIDCLASS and HID Transport minidriver

   2. Function Drivers: Alternatively vendors can create a function driver (instead of a filter driver) but only for vendor specific HID PDOs (with a user mode service if necessary).

      Function drivers are allowed in the following scenarios:

      • Only load on the specific vendor’s hardware

   3. Transport Drivers: Windows team does not recommend creating additional HID Transport minidriver as they are complex drivers to write/maintain. If a partner is creating a new HID Transport minidriver, especially on SoC systems, we recommend a detailed architectural review to understand the reasoning and ensure that the driver is developed correctly.

2. Driver developers should leverage driver Frameworks (KMDF or UMDF) and not rely on WDM for their filter drivers.

3. Driver developers should reduce the number of kernel-user transitions between their service and the driver stack.

4. Driver developers should ensure ability to wake the system via both keyboard and touchpad functionality (adjustable by the end user (device manager) or the PC manufacturer). In addition on SoC systems, these devices must be able to wake themselves from a lower powered state while the system is in a working S0 state.

5. Driver developers should ensure that their hardware is power managed efficiently.

   • Device can go into its lowest power state when the device is idle.
   • Device is in the lowest power state when the system is in a low power state (for example, standby (S3) or connected standby).

Keyboard layout

A keyboard layout fully describes a keyboard's input characteristics for Microsoft Windows 2000 and later versions. For example, a keyboard layout specifies the language, keyboard type and version, modifiers, scan codes, and so on.

Drivers Ruling Input Devices Input

See the following for information about keyboard layouts:

• Keyboard header file, kdb.h, in the Windows Driver Development Kit (DDK), which documents general information about keyboard layouts.

• Sample keyboard layouts.

To visualize the layout of a specific keyboard, see Windows Keyboard Layouts.

For additional details around the keyboard layout, visit Control PanelClock, Language, and RegionLanguage.

Supported buttons and wheels on mice

The following table identifies the features supported across different client versions of the Windows operating system.

Activating buttons 4-5 and wheel on PS/2 mice

The method used by Windows to activate the new 4&5-button + wheel mode is an extension of the method used to activate the third button and the wheel in IntelliMouse-compatible mice:

• First, the mouse is set to the 3-button wheel mode, which is accomplished by setting the report rate consecutively to 200 reports/second, then to 100 reports/second, then to 80 reports/second, and then reading the ID from the mouse. The mouse should report an ID of 3 when this sequence is completed.
• Next, the mouse is set to the 5-button wheel mode, which is accomplished by setting the report rate consecutively to 200 reports/second, then to 200 reports/second again, then to 80 reports/second, and then reading the ID from the mouse. Once this sequence is completed, a 5-button wheel mouse should report an ID of 4 (whereas an IntelliMouse-compatible 3-button wheel mouse would still report an ID of 3).

Note that this is applicable to PS/2 mice only and is not applicable to HID mice (HID mice must report accurate usages in their report descriptor).

Standard PS/2-compatible mouse data packet format (2 Buttons)

Note

Windows mouse drivers do not check the overflow bits. In case of overflow, the mouse should simply send the maximal signed displacement value.

Standard PS/2-compatible mouse data packet format (3 Buttons + VerticalWheel)

Standard PS/2-compatible mouse data packet format (5 Buttons + VerticalWheel)

Important

Notice that the Z/wheel data for a 5-button wheel mouse has been reduced to four bits instead of the 8 bits used in the IntelliMouse-compatible 3-button wheel mode. This reduction is made possible by the fact that the wheel typically cannot generate values beyond the range +7/-8 during any given interrupt period. Windows mouse drivers will sign extend the four Z/wheel data bits when the mouse is in the 5-button wheel mode, and the full Z/wheel data byte when the mouse operates in the 3-button wheel mode.

Buttons 4 & 5 on are mapped to WM_APPCOMMAND messages and correspond to App_Back and App_Forward.

Devices not requiring vendor drivers

Vendor drivers are not required for the following devices:

• Devices that comply with the HID Standard.
• Keyboard, mouse, or game port devices operated by the system-supplied non-HIDClass drivers.

Kbfiltr sample

Kbfiltr is designed to be used with Kbdclass, the system class driver for keyboard devices and I8042prt, the function driver for a PS/2-style keyboard. Kbfiltr demonstrates how to filter I/O requests and how to add callback routines that modify the operation of Kbdclass and I8042prt.

For more information about Kbfiltr operation, see the following:

• The ntddkbd.h WDK header file.

• The sample Kbfiltr source code.

Kbfiltr IOCTLs

IOCTL_INTERNAL_I8042_HOOK_KEYBOARD

The IOCTL_INTERNAL_I8042_HOOK_KEYBOARD request does the following:

• Adds an initialization callback routine to the I8042prt keyboard initialization routine.
• Adds an ISR callback routine to the I8042prt keyboard ISR.

The initialization and ISR callbacks are optional and are provided by an upper-level filter driver for a PS/2-style keyboard device.

After I8042prt receives an IOCTL_INTERNAL_KEYBOARD_CONNECT request, it sends a synchronous IOCTL_INTERNAL_I8042_HOOK_KEYBOARD request to the top of the keyboard device stack.

After Kbfiltr receives the hook keyboard request, Kbfiltr filters the request in the following way:

• Saves the upper-level information passed to Kbfiltr, which includes the context of an upper-level device object, a pointer to an initialization callback, and a pointer to an ISR callback.
• Replaces the upper-level information with its own.
• Saves the context of I8042prt and pointers to callbacks that the Kbfiltr ISR callback can use.

IOCTL_INTERNAL_KEYBOARD_CONNECT

The IOCTL_INTERNAL_KEYBOARD_CONNECT request connects the Kbdclass service to the keyboard device. Kbdclass sends this request down the keyboard device stack before it opens the keyboard device.

After Kbfiltr received the keyboard connect request, Kbfiltr filters the connect request in the following way:

• Saves a copy of Kbdclass's CONNECT_DATA (Kbdclass) structure that is passed to the filter driver by Kbdclass.
• Substitutes its own connect information for the class driver connect information.
• Sends the IOCTL_INTERNAL_KEYBOARD_CONNECT request down the device stack.

If the request is not successful, Kbfiltr completes the request with an appropriate error status.

Kbfiltr provides a template for a filter service callback routine that can supplement the operation of KeyboardClassServiceCallback, the Kbdclass class service callback routine. The filter service callback can filter the input data that is transferred from the device input buffer to the class data queue.

IOCTL_INTERNAL_KEYBOARD_DISCONNECT

The IOCTL_INTERNAL_KEYBOARD_DISCONNECT request is completed with a status of STATUS_NOT_IMPLEMENTED. Note that a Plug and Play keyboard can be added or removed by the Plug and Play manager.

For all other device control requests, Kbfiltr skips the current IRP stack and sends the request down the device stack without further processing.

Callback routines implemented by Kbfiltr

KbFilter_InitializationRoutine

See PI8042_KEYBOARD_INITIALIZATION_ROUTINE

The KbFilter_InitializationRoutine is not needed if the I8042prt default initialization of a keyboard is sufficient.

I8042prt calls KbFilter_InitializationRoutine when it initializes the keyboard. Default keyboard initialization includes the following operations:

• reset the keyboard
• set the typematic rate and delay
• set the light-emitting diodes (LED)

KbFilter_IsrHook

See PI8042_KEYBOARD_ISR. This callback is not needed if the default operation of I8042prt is sufficient.

The I8042prt keyboard ISR calls KbFilter_IsrHook after it validates the interrupt and reads the scan code.

KbFilter_IsrHook runs in kernel mode at the IRQL of the I8042prt keyboard.

KbFilter_ServiceCallback

See PSERVICE_CALLBACK_ROUTINE.

The ISR dispatch completion routine of the function driver calls KbFilter_ServiceCallback, which then calls the keyboard class driver's implementation of PSERVICE_CALLBACK_ROUTINE. A vendor can implement a filter service callback to modify the input data that is transferred from the device's input buffer to the class data queue. For example, the callback can delete, transform, or insert data.

Moufiltr sample

Moufiltr is designed to be used with Mouclass, the system class driver for mouse devices used with Windows 2000 and later versions, and I8042prt, the function driver for a PS/2-style mouse used with Windows 2000 and later. Moufiltr demonstrates how to filter I/O requests and add callback routines that modify the operation of Mouclass and I8042prt.

For more information about Moufiltr operation, see the following:

• The ntddmou.h WDK header file.

• The sample Moufiltr source code.

Moufiltr control codes

IOCTL_INTERNAL_I8042_HOOK_MOUSE

The IOCTL_INTERNAL_I8042_HOOK_MOUSE request adds an ISR callback routine to the I8042prt mouse ISR. The ISR callback is optional and is provided by an upper-level mouse filter driver.

I8042prt sends this request after it receives an IOCTL_INTERNAL_MOUSE_CONNECT request. I8042prt sends a synchronous IOCTL_INTERNAL_I8042_HOOK_MOUSE request to the top of the mouse device stack.

After Moufiltr receives the hook mouse request, it filters the request in the following way:

• Saves the upper-level information passed to Moufiltr, which includes the context of an upper-level device object and a pointer to an ISR callback.
• Replaces the upper-level information with its own.
• Saves the context of I8042prt and pointers to callbacks that the Moufiltr ISR callbacks can use.

Moufiltr Callback Routines

IOCTL_INTERNAL_MOUSE_CONNECT

The IOCTL_INTERNAL_MOUSE_CONNECT request connects Mouclass service to a mouse device.

Drivers Ruling Input Devices Examples

IOCTL_INTERNAL_MOUSE_DISCONNECT

The IOCTL_INTERNAL_MOUSE_DISCONNECT request is completed by Moufiltr with an error status of STATUS_NOT_IMPLEMENTED.

For all other requests, Moufiltr skips the current IRP stack and sends the request down the device stack without further processing.

Callback routines

MouFilter_IsrHook

See PI8042_MOUSE_ISR.

A MouFilter_IsrHook callback is not needed if the default operation of I8042prt is sufficient.

The I8042prt mouse ISR calls MouFilter_IsrHook after it validates the interrupt.

To reset a mouse, I8042prt goes through a sequence of operational substates, each one of which is identified by an MOUSE_RESET_SUBSTATE enumeration value. For more information about how I8042prt resets a mouse and the corresponding mouse reset substates, see the documentation of MOUSE_RESET_SUBSTATE in ntdd8042.h.

MouFilter_IsrHook runs in kernel mode at the IRQL of the I8042prt mouse ISR.

MouFilter_ServiceCallback

See PSERVICE_CALLBACK_ROUTINE

The ISR DPC of I8042prt calls MouFilter_ServiceCallback, which then calls MouseClassServiceCallback. A filter service callback can be configured to modify the input data that is transferred from the device's input buffer to the class data queue. For example, the callback can delete, transform, or insert data.

1.1. The simplest example¶

Here comes a very simple example of an input device driver. The device hasjust one button and the button is accessible at i/o port BUTTON_PORT. Whenpressed or released a BUTTON_IRQ happens. The driver could look like:

1.2. What the example does¶

First it has to include the <linux/input.h> file, which interfaces to theinput subsystem. This provides all the definitions needed.

In the _init function, which is called either upon module load or whenbooting the kernel, it grabs the required resources (it should also checkfor the presence of the device).

Then it allocates a new input device structure with input_allocate_device()and sets up input bitfields. This way the device driver tells the otherparts of the input systems what it is - what events can be generated oraccepted by this input device. Our example device can only generate EV_KEYtype events, and from those only BTN_0 event code. Thus we only set thesetwo bits. We could have used:

as well, but with more than single bits the first approach tends to beshorter.

Then the example driver registers the input device structure by calling:

This adds the button_dev structure to linked lists of the input driver andcalls device handler modules _connect functions to tell them a new inputdevice has appeared. input_register_device() may sleep and therefore mustnot be called from an interrupt or with a spinlock held.

While in use, the only used function of the driver is:

which upon every interrupt from the button checks its state and reports itvia the:

call to the input system. There is no need to check whether the interruptroutine isn’t reporting two same value events (press, press for example) tothe input system, because the input_report_* functions check thatthemselves.

Then there is the:

call to tell those who receive the events that we’ve sent a complete report.This doesn’t seem important in the one button case, but is quite importantfor for example mouse movement, where you don’t want the X and Y valuesto be interpreted separately, because that’d result in a different movement.

1.3. dev->open() and dev->close()¶

In case the driver has to repeatedly poll the device, because it doesn’thave an interrupt coming from it and the polling is too expensive to be doneall the time, or if the device uses a valuable resource (eg. interrupt), itcan use the open and close callback to know when it can stop polling orrelease the interrupt and when it must resume polling or grab the interruptagain. To do that, we would add this to our example driver:

Note that input core keeps track of number of users for the device andmakes sure that dev->open() is called only when the first user connectsto the device and that dev->close() is called when the very last userdisconnects. Calls to both callbacks are serialized.

The open() callback should return a 0 in case of success or any nonzero valuein case of failure. The close() callback (which is void) must always succeed.

1.4. Basic event types¶

The most simple event type is EV_KEY, which is used for keys and buttons.It’s reported to the input system via:

See uapi/linux/input-event-codes.h for the allowable values of code (from 0 toKEY_MAX). Value is interpreted as a truth value, ie any nonzero value means keypressed, zero value means key released. The input code generates events onlyin case the value is different from before.

In addition to EV_KEY, there are two more basic event types: EV_REL andEV_ABS. They are used for relative and absolute values supplied by thedevice. A relative value may be for example a mouse movement in the X axis.The mouse reports it as a relative difference from the last position,because it doesn’t have any absolute coordinate system to work in. Absoluteevents are namely for joysticks and digitizers - devices that do work in anabsolute coordinate systems.

Having the device report EV_REL buttons is as simple as with EV_KEY, simplyset the corresponding bits and call the:

function. Events are generated only for nonzero value.

However EV_ABS requires a little special care. Before callinginput_register_device, you have to fill additional fields in the input_devstruct for each absolute axis your device has. If our button device had alsothe ABS_X axis:

Or, you can just say:

This setting would be appropriate for a joystick X axis, with the minimum of0, maximum of 255 (which the joystick must be able to reach, no problem ifit sometimes reports more, but it must be able to always reach the min andmax values), with noise in the data up to +- 4, and with a center flatposition of size 8.

If you don’t need absfuzz and absflat, you can set them to zero, which meanthat the thing is precise and always returns to exactly the center position(if it has any).

1.5. BITS_TO_LONGS(), BIT_WORD(), BIT_MASK()¶

These three macros from bitops.h help some bitfield computations:

1.6. The id* and name fields¶

The dev->name should be set before registering the input device by the inputdevice driver. It’s a string like ‘Generic button device’ containing auser friendly name of the device.

The id* fields contain the bus ID (PCI, USB, ...), vendor ID and device IDof the device. The bus IDs are defined in input.h. The vendor and device idsare defined in pci_ids.h, usb_ids.h and similar include files. These fieldsshould be set by the input device driver before registering it.

The idtype field can be used for specific information for the input devicedriver.

The id and name fields can be passed to userland via the evdev interface.

1.7. The keycode, keycodemax, keycodesize fields¶

These three fields should be used by input devices that have dense keymaps.The keycode is an array used to map from scancodes to input system keycodes.The keycode max should contain the size of the array and keycodesize thesize of each entry in it (in bytes).

Userspace can query and alter current scancode to keycode mappings usingEVIOCGKEYCODE and EVIOCSKEYCODE ioctls on corresponding evdev interface.When a device has all 3 aforementioned fields filled in, the driver mayrely on kernel’s default implementation of setting and querying keycodemappings.

1.8. dev->getkeycode() and dev->setkeycode()¶

getkeycode() and setkeycode() callbacks allow drivers to override defaultkeycode/keycodesize/keycodemax mapping mechanism provided by input coreand implement sparse keycode maps.

1.9. Key autorepeat¶

... is simple. It is handled by the input.c module. Hardware autorepeat isnot used, because it’s not present in many devices and even where it ispresent, it is broken sometimes (at keyboards: Toshiba notebooks). To enableautorepeat for your device, just set EV_REP in dev->evbit. All will behandled by the input system.

1.10. Other event types, handling output events¶

The other event types up to now are:

Drivers Ruling Input Devices Device

• EV_LED - used for the keyboard LEDs.
• EV_SND - used for keyboard beeps.

Drivers Ruling Input Devices

They are very similar to for example key events, but they go in the otherdirection - from the system to the input device driver. If your input devicedriver can handle these events, it has to set the respective bits in evbit,and also the callback routine:

Drivers Ruling Input Devices Definition

This callback routine can be called from an interrupt or a BH (although thatisn’t a rule), and thus must not sleep, and must not take too long to finish.