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PMS(4) NetBSD Kernel Interfaces Manual PMS(4)
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pms -- PS/2 auxiliary port mouse driver
pckbc* at isa?
pms* at pckbc?
wsmouse* at pms?
The pms driver provides an interface to PS/2 auxiliary port mice within
the wscons(4) framework. Parent device in terms of the autoconfiguration
framework is pckbc(4), the PC keyboard controller. ``pms'' is a generic
driver which supports mice using common variants of the PS/2 protocol,
including wheel mice of the ``IntelliMouse'' breed. Wheel movements are
mapped to a third (z-) axis. The driver is believed to work with both
3-button and 5-button mice with scroll wheels. Mice which use other pro-
tocol extensions are not currently supported, but might be if protocol
documentation could be found. Mouse related data are accessed by
The pms driver has been updated to attempt to renegotiate mouse protocol
after seeing suspicious or defective mouse protocol packets, or unusual
delays in the middle of a packet; this should improve the chances that a
mouse will recover after being switched away or reset (for instance, by a
The PMS_DISABLE_POWERHOOK kernel option disables PS/2 reset on resume.
In addition, the pms driver supports the ``Synaptics'', ``Elantech'' and
``ALPS'' touchpads in native mode, enabled with the
PMS_SYNAPTICS_TOUCHPAD, PMS_ELANTECH_TOUCHPAD and PMS_ALPS_TOUCHPAD ker-
nel options. This allows the driver to take advantage of extra features
available on Synaptics, Elantech and ALPS Touchpads.
The following sysctl(8) variables control behavior of Synaptics touch-
If the touchpad reports the existence of extra ("Up/Down") but-
tons, this value determines what kind of mouse events they
should generate. On certain clickpads, the Up/Down buttons may
be physical buttons that can be used instead of pressing the
pad down, or used as additional buttons.
· If set to 0, Up/Down events generate button 4 and 5 clicks.
· If set to 1, Up/Down events generate middle button clicks.
· If set to 2, the Up and Down buttons are used for Z-axis
emulation, which more closely resembles how mouse wheels
· If set to 3 (default), Up/Down events generate left/right
When the Up/Down buttons are used for Z-axis emulation, this
value specifies the emulated delta-Z value per click.
Gestures will not be recognised if the finger moves by more
than this amount between taps.
Gestures will not be recognised if the number of packets (at 80
packets per second) between taps exceeds this value.
These values define a border around the touchpad which will be
used for edge motion emulation during a drag gesture. If a
drag gesture is in progress and the finger moves into this bor-
der, the driver will behave as if the finger continues to move
in the same direction beyond the edge of the touchpad.
This specifies the pointer speed when edge motion is in effect.
The driver will ignore new finger events until the reported
pressure exceeds this value.
The driver will assume a finger remains on the touchpad until
the reported pressure drops below this value.
More recent touchpads can report the presence of more than one
finger on the pad. This value determines how such events are
· If set to 0 (default), two-finger events are ignored.
· If set to 1, two-finger events generate a right button
· If set to 2, two-finger events generate a middle button
Scale factor used to divide movement deltas derived from Synap-
tics coordinates (0-6143) to yield more reasonable values
(default 16 for x and y, 1 for z).
Limits pointer rate of change (after scaling) per reported
movement event (default 32 for x and y, 2 for z).
Movements of less than this value (in Synaptics coordinates)
are ignored (default 4).
Sets the top edge of the button emulation region on a clickpad.
Since a clickpad only reports left clicks this region is used
to emulate two or three buttons by detecting the finger loca-
tion and reporting either a button 2 or button 3 click iff the
click occurs within the region bounded by button_boundary and
the bottom of the clickpad.
This defines the left hand edge of the button 3 region. If a
click occurs in the region bounded by button_boundary, but-
ton3_edge and the right hand edge of the click pad then the
click will be reported as a button3 event. Button 3 emulation
can be disabled by setting button3_edge to the right hand edge
of the clickpad.
This defines the left hand edge of the button 2 region. The
button 2 region is bounded by button2_edge, button3_edge and
button_boundary. If a click occurs in this region then it will
be reported as a button2 event. For completeness, the region
between the left hand side of the clickpad, button2_edge and
button_boundary will be reported as a button1 event as will any
clicks that occur outside the button emulation region.
The minimum finger width at which the driver will start report-
ing vertical movements as Z axis events. Effectively, this
emulates a mouse scroll wheel by the user using two fingers
together on the click pad. The default value is 5, this value
cannot be less than 5 due to the way the clickpad reports fin-
The maximum finger width at which the driver will report finger
movement as Z axis events. The default value is 12 and cannot
be greater than 14.
This defines the number of packets to continue with the Z axis
emulation. Due to the nature of the clickpad maintaining con-
stant contact can be difficult. This hysteresis value prevents
the driver flipping between two finger scroll and normal mouse
movement erratically. Each time a valid finger scroll width is
detected the packet count is reset. If this variable is set
too high then mouse movements will be interpreted as Z-axis
events after the two finger scoll has finished. If the vari-
able is set too low then there will be mouse movements observed
during the two finger scroll.
This causes Y-axis movement on the "passthrough device" (e.g.
the TrackPoint on ThinkPads) to result in scrolling events
instead of Y-axis movement when the middle button is held.
The following sysctl(8) variables control behavior of Elantech touchpads:
Increased values improve the accuracy of X, Y, and Z-axis
reporting at the expense of slower mouse movement (default 2
for xy, and 3 for z).
For Elantech touchpads, the Z-axis is emulated using two-finger Y-axis
The following sysctl(8) variables control behavior of ALPS touchpads:
Decreased values improve the accuracy of X and Y-axis reporting
at the expense of slower mouse movement (default 2 for touchpad
and 1 for TrackStick).
pckbc(4), ums(4), wsmouse(4)
The pms driver was originally written by Christopher G. Demetriou. The
changes to merge the ``IntelliMouse'' protocol in, and reset the mouse in
the event of protocol problems, were contributed by Peter Seebach. Spe-
cial thanks to Ray Trent, at Synaptics, who contributed valuable insight
into how to identify bogus mouse data. The changes to add ``Synaptics''
pad support were by Ales Krenek, Kentaro A. Kurahone, and Steve C.
Woodford. The changes to add ``Elantech'' pad support were by Jared D.
It is possible for the driver to mistakenly negotiate the non-scroll-
wheel protocol, after which it is unlikely to recover until the device is
closed and reopened.
The ``Elantech'' pad code only supports trackpads with firmware version
2.48 or above.
NetBSD 9.3 October 1, 2020 NetBSD 9.3