Keyboard and mouse HID client drivers. 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. 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.

Note

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.

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.

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)

Microsoft Ps/2 Keyboard Driver Windows 10

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.

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

Driver Microsoft Natural Ps 2 Keyboard

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.

This topic describes the features of I8042prt, the Microsoft Windows 2000 and later system function driver for PS/2-style keyboard and mouse devices.

I8042prt implements the I8042prt service and its executable image is i8042prt.sys.

The features of I8042prt include:

• Hardware-dependent, simultaneous operation of a PS/2-style keyboard and mouse device.

  The keyboard and mouse share I/O ports, but use different interrupts, interrupt service routines (ISR), and ISR dispatch completion routines.

• Plug and Play, power management, and WMI

• Operation of legacy devices.

• Connection of a keyboard class service callback routine and a mouse class service callback routine.

  I8042prt uses the class service callback to transfer data from the input data buffer of I8042prt to the data buffer of the class driver.

• Addition of a vendor-supplied PI8042_KEYBOARD_INITIALIZATION_ROUTINE callback routines for a keyboard device.

  An optional upper-level device filter driver provides the callback routines.

• Addition of a vendor-supplied PI8042_KEYBOARD_ISR callback routine and a custom PI8042_MOUSE_ISR callback routine.

  Optional upper-level device filter drivers provide these callbacks routines.

• Keyboard write buffer request and mouse write buffer request.

  An upper-level device filter driver can use write buffer requests to synchronize its writes to a device with the ISR of the device and other reads and writes on the device.

• Keyboard start information request and mouse start information request.

  The start information request passes a pointer to an interrupt object of a device to an upper-level filter driver. The filter driver can use the interrupt object to synchronize its operation with the ISR of the device.

• I8042prt callback routines.

  An upper-level device filter driver can use the callback routines in the context of the ISR of a device to write to a device, and to queue data packets from the device.

Registry settings associated with the PS/2 driver

The following is a list of registry keys associated with the PS/2 port driver.

Standard Ps 2 Keyboard Driver

• EnableWheelDetection [REG_DWORD] – Determines whether the driver attempts to detect and enable the wheel on the mouse device. Some devices are equipped with a mouse wheel to provide rapid scrolling and other control features if supported by an application.
• ResendIterations [REG_DWORD] – Specifies the maximum number of times a hardware operation is attempted. If the number of trials exceeds the value of this entry, Windows considers the operation to have failed.
• NumberOfButtons [REG_DWORD] – Specifies the number of buttons on the mouse-port mouse at startup. If the number of buttons detected at startup is incorrect, you can override it by changing the value of this entry.
• KeyboardDataQueueSize [REG_DWORD] – Specifies the number of keyboard events that the keyboard driver buffers. This entry is also used in calculating the size of the keyboard driver's internal buffer in nonpaged memory pool. To determine the number of bytes to allocate for the buffer, the system multiplies the size of the KEYBOARD_INPUT_DATA structure by the value of KeyboardDataQueueSize.
• PollStatusIterations [REG_DWORD] – Specifies the maximum number of times the system verifies interrupts on the i8042 controller status register. If the interrupt cannot be verified in the number of trials specified in the value of this entry, the interrupt is ignored.
• PollingIterations [REG_DWORD] - Specifies the maximum number of times Windows 2000 polls the hardware. If the number of trials specified in this entry is exceeded, Windows 2000 stops polling.
• SampleRate [REG_DWORD] – Specifies how often the PS/2 driver measures the characteristics and activities of the PS/2 mouse. The driver uses the information gathered through sampling to optimize the operation of the mouse device.
• PollingIterationsMaximum [REG_DWORD] – Specifies the maximum number of times Windows 2000 polls the hardware on older-style AT keyboards. If the number of trials specified in this entry is exceeded, Windows stops polling.
• MouseResendStallTime [REG_DWORD] – Determines how long the mouse driver waits for an acknowledgement (ACK) of a reset if a RESEND message is returned without an ACK. This entry is used when the mouse driver interrupt service routine includes a reset.
• OverrideKeyboardType [REG_DWORD] – Specifies the keyboard type. You can add this entry to the registry to correct an error in the keyboard type detected at startup.
• OverrideKeyboardSubtype [REG_DWORD] – Specifies the OEM-dependent keyboard subtype. You can add this entry to the registry to correct an error in the keyboard subtype detected at startup.

Microsoft Natural Ps/2 Keyboard Driver Xp

For additional information, please see: