This commit adds the file Documentation/input/evdev-codes.txt.
Cc: Henrik Rydberg <[email protected]>
Cc: Peter Hutterer <[email protected]>
Cc: Nikolai Kondrashov <[email protected]>
Cc: [email protected]
Cc: [email protected]
Acked-by: Henrik Rydberg <[email protected]>
Signed-off-by: Chase Douglas <[email protected]>
Signed-off-by: Chris Bagwell <[email protected]>
---
Documentation/input/evdev-codes.txt | 256 +++++++++++++++++++++++++++++++++++
1 files changed, 256 insertions(+), 0 deletions(-)
create mode 100644 Documentation/input/evdev-codes.txt
diff --git a/Documentation/input/evdev-codes.txt b/Documentation/input/evdev-codes.txt
new file mode 100644
index 0000000..b50bc49
--- /dev/null
+++ b/Documentation/input/evdev-codes.txt
@@ -0,0 +1,256 @@
+The evdev protocol uses a map of types and codes to express input device values
+to userspace. This document describes the types and codes and how and when they
+may be used.
+
+A single hardware event generates multiple input events. Each input event
+contains the new value of a single data item. A special event type, EV_SYN, is
+used to separate input events into packets of input data changes occurring at
+the same moment in time. In the following, the term "event" refers to a single
+input event encompassing a type, code, and value.
+
+The evdev protocol is a stateful protocol. Events are emitted only when values
+of evdev codes have changed. However, the state is maintained within the Linux
+input subsystem; drivers do not need to maintain the state and may attempt to
+emit unchanged values without harm. Userspace may obtain the current state of
+evdev code values using the EVIOCG* ioctls defined in linux/input.h. The evdev
+reports supported by a device are also provided by sysfs in
+class/input/event*/device/capabilities/, and the properties of a device are
+provided in class/input/event*/device/properties.
+
+Types:
+==========
+Types are groupings of codes under a logical input construct. Each type has a
+set of applicable codes to be used in generating events. See the Codes section
+for details on valid codes for each type.
+
+* EV_SYN:
+ - Used as markers to separate events. Events may be separated in time or in
+ space, such as with the multitouch protocol.
+
+* EV_KEY:
+ - Used to describe state changes of keyboards, buttons, or other key-like
+ devices.
+
+* EV_REL:
+ - Used to describe relative axis value changes, e.g. moving the mouse 5 units
+ to the left.
+
+* EV_ABS:
+ - Used to describe absolute axis value changes, e.g. describing the
+ coordinates of a touch on a touchscreen.
+
+* EV_MSC:
+ - Used to describe miscellaneous input data that do not fit into other types.
+
+* EV_SW:
+ - Used to describe binary state input switches.
+
+* EV_LED:
+ - Used to turn LEDs on devices on and off.
+
+* EV_SND:
+ - Used to output sound to devices.
+
+* EV_REP:
+ - Used for autorepeating devices.
+
+* EV_FF:
+ - Used to send force feedback commands to an input device.
+
+* EV_PWR:
+ - A special type for power button and switch input.
+
+* EV_FF_STATUS:
+ - Used to receive force feedback device status.
+
+Codes:
+==========
+Codes define the precise type of event.
+
+EV_SYN:
+----------
+EV_SYN event values are undefined. Their usage is defined only by when they are
+sent in the evdev event stream.
+
+* SYN_REPORT:
+ - Used to synchronize and separate events into packets of input data changes
+ occurring at the same moment in time. For example, motion of a mouse may set
+ the REL_X and REL_Y values for one motion, then emit a SYN_REPORT. The next
+ motion will emit more REL_X and REL_Y values and send another SYN_REPORT.
+
+* SYN_CONFIG:
+ - TBD
+
+* SYN_MT_REPORT:
+ - Used to synchronize and separate touch events. See the
+ multi-touch-protocol.txt document for more information.
+
+EV_KEY:
+----------
+EV_KEY events take the form KEY_<name> or BTN_<name>. For example, KEY_A is used
+to represent the 'A' key on a keyboard. When a key is depressed, an event with
+the key's code is emitted with value 1. When the key is released, an event is
+emitted with value 0. Some hardware send events when a key is repeated. These
+events have a value of 2. In general, KEY_<name> is used for keyboard keys, and
+BTN_<name> is used for other types of momentary switch events.
+
+A few EV_KEY codes have special meanings:
+
+* BTN_TOOL_<name>:
+ - These codes are used in conjunction with input trackpads, tablets, and
+ touchscreens. These devices may be used with fingers, pens, or other tools.
+ When an event occurs and a tool is used, the corresponding BTN_TOOL_<name>
+ code should be set to a value of 1. When the tool is no longer interacting
+ with the input device, the BTN_TOOL_<name> code should be reset to 0. All
+ trackpads, tablets, and touchscreens should use at least one BTN_TOOL_<name>
+ code when events are generated.
+
+* BTN_TOUCH:
+ BTN_TOUCH is used for touch contact. While an input tool is determined to be
+ within meaningful physical contact, the value of this property must be set
+ to 1. Meaningful physical contact may mean any contact, or it may mean
+ contact conditioned by an implementation defined property. For example, a
+ touchpad may set the value to 1 only when the touch pressure rises above a
+ certain value. BTN_TOUCH may be combined with BTN_TOOL_<name> codes. For
+ example, a pen tablet may set BTN_TOOL_PEN to 1 and BTN_TOUCH to 0 while the
+ pen is hovering over but not touching the tablet surface.
+
+Note: For appropriate function of the legacy mousedev emulation driver,
+BTN_TOUCH must be the first evdev code emitted in a synchronization frame.
+
+Note: Historically a touch device with BTN_TOOL_FINGER and BTN_TOUCH was
+interpreted as a touchpad by userspace, while a similar device without
+BTN_TOOL_FINGER was interpreted as a touchscreen. For backwards compatibility
+with current userspace it is recommended to follow this distinction. In the
+future, this distinction will be deprecated and the device properties ioctl
+EVIOCGPROP, defined in linux/input.h, will be used to convey the device type.
+
+* BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP, BTN_TOOL_TRIPLETAP, BTN_TOOL_QUADTAP:
+ - These codes denote one, two, three, and four finger interaction on a
+ trackpad or touchscreen. For example, if the user uses two fingers and moves
+ them on the touchpad in an effort to scroll content on screen,
+ BTN_TOOL_DOUBLETAP should be set to value 1 for the duration of the motion.
+ Note that all BTN_TOOL_<name> codes and the BTN_TOUCH code are orthogonal in
+ purpose. A trackpad event generated by finger touches should generate events
+ for one code from each group. At most only one of these BTN_TOOL_<name>
+ codes should have a value of 1 during any synchronization frame.
+
+Note: Historically some drivers emitted multiple of the finger count codes with
+a value of 1 in the same synchronization frame. This usage is deprecated.
+
+Note: In multitouch drivers, the input_mt_report_finger_count() function should
+be used to emit these codes. Please see multi-touch-protocol.txt for details.
+
+EV_REL:
+----------
+EV_REL events describe relative changes in a property. For example, a mouse may
+move to the left by a certain number of units, but its absolute position in
+space is unknown. If the absolute position is known, EV_ABS codes should be used
+instead of EV_REL codes.
+
+A few EV_REL codes have special meanings:
+
+* REL_WHEEL, REL_HWHEEL:
+ - These codes are used for vertical and horizontal scroll wheels,
+ respectively.
+
+EV_ABS:
+----------
+EV_ABS events describe absolute changes in a property. For example, a touchpad
+may emit coordinates for a touch location.
+
+A few EV_ABS codes have special meanings:
+
+* ABS_DISTANCE:
+ - Used to describe the distance of a tool from an interaction surface. This
+ event should only be emitted while the tool is hovering, meaning in close
+ proximity of the device and while the value of the BTN_TOUCH code is 0. If
+ the input device may be used freely in three dimensions, consider ABS_Z
+ instead.
+
+* ABS_MT_<name>:
+ - Used to describe multitouch input events. Please see
+ multi-touch-protocol.txt for details.
+
+EV_SW:
+----------
+EV_SW events describe stateful binary switches. For example, the SW_LID code is
+used to denote when a laptop lid is closed.
+
+Upon binding to a device or resuming from suspend, a driver must report the
+the current switch state. This ensures that the device, kernel, and userspace
+state is in sync.
+
+Upon resume, if the switch state is the same as before suspend, then the input
+subsystem will filter out the duplicate switch state reports. The driver does
+not need to keep the state of the switch at any time.
+
+EV_MSC:
+----------
+EV_MSC events are used for input and output events that do not fall under other
+categories.
+
+EV_LED:
+----------
+EV_LED events are used for input and output to set and query the state of
+various LEDs on devices.
+
+EV_REP:
+----------
+EV_REP events are used for specifying autorepeating events.
+
+EV_SND:
+----------
+EV_SND events are used for sending sound commands to simple sound output
+devices.
+
+EV_FF:
+----------
+EV_FF events are used to initialize a force feedback capable device and to cause
+such device to feedback.
+
+EV_PWR:
+----------
+EV_PWR events are a special type of event used specifically for power
+mangement. Its usage is not well defined. To be addressed later.
+
+Guidelines:
+==========
+The guidelines below ensure proper single-touch and multi-finger functionality.
+For multi-touch functionality, see the multi-touch-protocol.txt document for
+more information.
+
+Mice:
+----------
+REL_{X,Y} must be reported when the mouse moves. BTN_LEFT must be used to report
+the primary button press. BTN_{MIDDLE,RIGHT,4,5,etc.} should be used to report
+further buttons of the device. REL_WHEEL and REL_HWHEEL should be used to report
+scroll wheel events where available.
+
+Touchscreens:
+----------
+ABS_{X,Y} must be reported with the location of the touch. BTN_TOUCH must be
+used to report when a touch is active on the screen.
+BTN_{MOUSE,LEFT,MIDDLE,RIGHT} must not be reported as the result of touch
+contact. BTN_TOOL_<name> events should be reported where possible.
+
+Trackpads:
+----------
+Legacy trackpads that only provide relative position information must report
+events like mice described above.
+
+Trackpads that provide absolute touch position must report ABS_{X,Y} for the
+location of the touch. BTN_TOUCH should be used to report when a touch is active
+on the trackpad. Where multi-finger support is available, BTN_TOOL_<name> should
+be used to report the number of touches active on the trackpad.
+
+Tablets:
+----------
+BTN_TOOL_<name> events must be reported when a stylus or other tool is active on
+the tablet. ABS_{X,Y} must be reported with the location of the tool. BTN_TOUCH
+should be used to report when the tool is in contact with the tablet.
+BTN_{STYLUS,STYLUS2} should be used to report buttons on the tool itself. Any
+button may be used for buttons on the tablet except BTN_{MOUSE,LEFT}.
+BTN_{0,1,2,etc} are good generic codes for unlabeled buttons. Do not use
+meaningful buttons, like BTN_FORWARD, unless the button is labeled for that
+purpose on the device.
--
1.7.4.1
Since the documentation is getting longer, having a diff between revisions
is helpful. Please use this only as informational, and reply only to the
proposed patch.
Thanks,
-- Chase
diff --git a/Documentation/input/evdev-codes.txt b/Documentation/input/evdev-codes.txt
index 473ce9d..b50bc49 100644
--- a/Documentation/input/evdev-codes.txt
+++ b/Documentation/input/evdev-codes.txt
@@ -2,6 +2,12 @@ The evdev protocol uses a map of types and codes to express input device values
to userspace. This document describes the types and codes and how and when they
may be used.
+A single hardware event generates multiple input events. Each input event
+contains the new value of a single data item. A special event type, EV_SYN, is
+used to separate input events into packets of input data changes occurring at
+the same moment in time. In the following, the term "event" refers to a single
+input event encompassing a type, code, and value.
+
The evdev protocol is a stateful protocol. Events are emitted only when values
of evdev codes have changed. However, the state is maintained within the Linux
input subsystem; drivers do not need to maintain the state and may attempt to
@@ -22,19 +28,19 @@ for details on valid codes for each type.
space, such as with the multitouch protocol.
* EV_KEY:
- - Used to describe keyboard and other key-like input events.
+ - Used to describe state changes of keyboards, buttons, or other key-like
+ devices.
* EV_REL:
- - Used to describe relative input events, e.g. moving the mouse 5 units to the
- left.
+ - Used to describe relative axis value changes, e.g. moving the mouse 5 units
+ to the left.
* EV_ABS:
- - Used to describe absolute input events, e.g. describing the coordinates of a
- touch on a touchscreen.
+ - Used to describe absolute axis value changes, e.g. describing the
+ coordinates of a touch on a touchscreen.
* EV_MSC:
- - Used to describe miscellaneous input events that do not fit into other
- types.
+ - Used to describe miscellaneous input data that do not fit into other types.
* EV_SW:
- Used to describe binary state input switches.
@@ -63,14 +69,14 @@ Codes define the precise type of event.
EV_SYN:
----------
-EV_SYN event values are undefined. Their usage is
-defined only by when they are sent in the evdev event stream.
+EV_SYN event values are undefined. Their usage is defined only by when they are
+sent in the evdev event stream.
* SYN_REPORT:
- - Used to synchronize and separate events into frames of time. For example,
- motion of a mouse may set the REL_X and REL_Y values for one motion, then
- emit a SYN_REPORT. The next motion will emit more REL_X and REL_Y values and
- send another SYN_REPORT.
+ - Used to synchronize and separate events into packets of input data changes
+ occurring at the same moment in time. For example, motion of a mouse may set
+ the REL_X and REL_Y values for one motion, then emit a SYN_REPORT. The next
+ motion will emit more REL_X and REL_Y values and send another SYN_REPORT.
* SYN_CONFIG:
- TBD
@@ -157,9 +163,10 @@ A few EV_ABS codes have special meanings:
* ABS_DISTANCE:
- Used to describe the distance of a tool from an interaction surface. This
- should only be used while the tool is hovering, meaning in close proximity
- of the device. If the input device may be used freely in three dimensions,
- consider ABS_Z instead.
+ event should only be emitted while the tool is hovering, meaning in close
+ proximity of the device and while the value of the BTN_TOUCH code is 0. If
+ the input device may be used freely in three dimensions, consider ABS_Z
+ instead.
* ABS_MT_<name>:
- Used to describe multitouch input events. Please see
@@ -224,8 +231,8 @@ Touchscreens:
----------
ABS_{X,Y} must be reported with the location of the touch. BTN_TOUCH must be
used to report when a touch is active on the screen.
-BTN_{MOUSE,LEFT,MIDDLE,RIGHT} must not be reported. BTN_TOOL_<name> events
-should be reported where possible.
+BTN_{MOUSE,LEFT,MIDDLE,RIGHT} must not be reported as the result of touch
+contact. BTN_TOOL_<name> events should be reported where possible.
Trackpads:
----------
@@ -236,3 +243,14 @@ Trackpads that provide absolute touch position must report ABS_{X,Y} for the
location of the touch. BTN_TOUCH should be used to report when a touch is active
on the trackpad. Where multi-finger support is available, BTN_TOOL_<name> should
be used to report the number of touches active on the trackpad.
+
+Tablets:
+----------
+BTN_TOOL_<name> events must be reported when a stylus or other tool is active on
+the tablet. ABS_{X,Y} must be reported with the location of the tool. BTN_TOUCH
+should be used to report when the tool is in contact with the tablet.
+BTN_{STYLUS,STYLUS2} should be used to report buttons on the tool itself. Any
+button may be used for buttons on the tablet except BTN_{MOUSE,LEFT}.
+BTN_{0,1,2,etc} are good generic codes for unlabeled buttons. Do not use
+meaningful buttons, like BTN_FORWARD, unless the button is labeled for that
+purpose on the device.
Hi Chase,
On Wed, Apr 06, 2011 at 04:19:31PM -0400, Chase Douglas wrote:
> This commit adds the file Documentation/input/evdev-codes.txt.
>
> Cc: Henrik Rydberg <[email protected]>
> Cc: Peter Hutterer <[email protected]>
> Cc: Nikolai Kondrashov <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Acked-by: Henrik Rydberg <[email protected]>
> Signed-off-by: Chase Douglas <[email protected]>
> Signed-off-by: Chris Bagwell <[email protected]>
Thank you very much for doing this. I am very happy with the state of
document at the moment and I want to apply it and get in .39.
The only 2 changes I'd like (I'll do them on my side) is renaming the
file from evdev-codes to event-codes and evdev protocol to input
protocol since the data applicable not only to evdev but to entire input
core.
Thanks.
--
Dmitry
On Wed, Apr 06, 2011 at 04:19:31PM -0400, Chase Douglas wrote:
> This commit adds the file Documentation/input/evdev-codes.txt.
>
> Cc: Henrik Rydberg <[email protected]>
> Cc: Peter Hutterer <[email protected]>
> Cc: Nikolai Kondrashov <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Acked-by: Henrik Rydberg <[email protected]>
> Signed-off-by: Chase Douglas <[email protected]>
> Signed-off-by: Chris Bagwell <[email protected]>
> ---
> Documentation/input/evdev-codes.txt | 256 +++++++++++++++++++++++++++++++++++
> 1 files changed, 256 insertions(+), 0 deletions(-)
> create mode 100644 Documentation/input/evdev-codes.txt
>
Reviewed-by: Peter Hutterer <[email protected]>
thanks!
Cheers,
Peter
> diff --git a/Documentation/input/evdev-codes.txt b/Documentation/input/evdev-codes.txt
> new file mode 100644
> index 0000000..b50bc49
> --- /dev/null
> +++ b/Documentation/input/evdev-codes.txt
> @@ -0,0 +1,256 @@
> +The evdev protocol uses a map of types and codes to express input device values
> +to userspace. This document describes the types and codes and how and when they
> +may be used.
> +
> +A single hardware event generates multiple input events. Each input event
> +contains the new value of a single data item. A special event type, EV_SYN, is
> +used to separate input events into packets of input data changes occurring at
> +the same moment in time. In the following, the term "event" refers to a single
> +input event encompassing a type, code, and value.
> +
> +The evdev protocol is a stateful protocol. Events are emitted only when values
> +of evdev codes have changed. However, the state is maintained within the Linux
> +input subsystem; drivers do not need to maintain the state and may attempt to
> +emit unchanged values without harm. Userspace may obtain the current state of
> +evdev code values using the EVIOCG* ioctls defined in linux/input.h. The evdev
> +reports supported by a device are also provided by sysfs in
> +class/input/event*/device/capabilities/, and the properties of a device are
> +provided in class/input/event*/device/properties.
> +
> +Types:
> +==========
> +Types are groupings of codes under a logical input construct. Each type has a
> +set of applicable codes to be used in generating events. See the Codes section
> +for details on valid codes for each type.
> +
> +* EV_SYN:
> + - Used as markers to separate events. Events may be separated in time or in
> + space, such as with the multitouch protocol.
> +
> +* EV_KEY:
> + - Used to describe state changes of keyboards, buttons, or other key-like
> + devices.
> +
> +* EV_REL:
> + - Used to describe relative axis value changes, e.g. moving the mouse 5 units
> + to the left.
> +
> +* EV_ABS:
> + - Used to describe absolute axis value changes, e.g. describing the
> + coordinates of a touch on a touchscreen.
> +
> +* EV_MSC:
> + - Used to describe miscellaneous input data that do not fit into other types.
> +
> +* EV_SW:
> + - Used to describe binary state input switches.
> +
> +* EV_LED:
> + - Used to turn LEDs on devices on and off.
> +
> +* EV_SND:
> + - Used to output sound to devices.
> +
> +* EV_REP:
> + - Used for autorepeating devices.
> +
> +* EV_FF:
> + - Used to send force feedback commands to an input device.
> +
> +* EV_PWR:
> + - A special type for power button and switch input.
> +
> +* EV_FF_STATUS:
> + - Used to receive force feedback device status.
> +
> +Codes:
> +==========
> +Codes define the precise type of event.
> +
> +EV_SYN:
> +----------
> +EV_SYN event values are undefined. Their usage is defined only by when they are
> +sent in the evdev event stream.
> +
> +* SYN_REPORT:
> + - Used to synchronize and separate events into packets of input data changes
> + occurring at the same moment in time. For example, motion of a mouse may set
> + the REL_X and REL_Y values for one motion, then emit a SYN_REPORT. The next
> + motion will emit more REL_X and REL_Y values and send another SYN_REPORT.
> +
> +* SYN_CONFIG:
> + - TBD
> +
> +* SYN_MT_REPORT:
> + - Used to synchronize and separate touch events. See the
> + multi-touch-protocol.txt document for more information.
> +
> +EV_KEY:
> +----------
> +EV_KEY events take the form KEY_<name> or BTN_<name>. For example, KEY_A is used
> +to represent the 'A' key on a keyboard. When a key is depressed, an event with
> +the key's code is emitted with value 1. When the key is released, an event is
> +emitted with value 0. Some hardware send events when a key is repeated. These
> +events have a value of 2. In general, KEY_<name> is used for keyboard keys, and
> +BTN_<name> is used for other types of momentary switch events.
> +
> +A few EV_KEY codes have special meanings:
> +
> +* BTN_TOOL_<name>:
> + - These codes are used in conjunction with input trackpads, tablets, and
> + touchscreens. These devices may be used with fingers, pens, or other tools.
> + When an event occurs and a tool is used, the corresponding BTN_TOOL_<name>
> + code should be set to a value of 1. When the tool is no longer interacting
> + with the input device, the BTN_TOOL_<name> code should be reset to 0. All
> + trackpads, tablets, and touchscreens should use at least one BTN_TOOL_<name>
> + code when events are generated.
> +
> +* BTN_TOUCH:
> + BTN_TOUCH is used for touch contact. While an input tool is determined to be
> + within meaningful physical contact, the value of this property must be set
> + to 1. Meaningful physical contact may mean any contact, or it may mean
> + contact conditioned by an implementation defined property. For example, a
> + touchpad may set the value to 1 only when the touch pressure rises above a
> + certain value. BTN_TOUCH may be combined with BTN_TOOL_<name> codes. For
> + example, a pen tablet may set BTN_TOOL_PEN to 1 and BTN_TOUCH to 0 while the
> + pen is hovering over but not touching the tablet surface.
> +
> +Note: For appropriate function of the legacy mousedev emulation driver,
> +BTN_TOUCH must be the first evdev code emitted in a synchronization frame.
> +
> +Note: Historically a touch device with BTN_TOOL_FINGER and BTN_TOUCH was
> +interpreted as a touchpad by userspace, while a similar device without
> +BTN_TOOL_FINGER was interpreted as a touchscreen. For backwards compatibility
> +with current userspace it is recommended to follow this distinction. In the
> +future, this distinction will be deprecated and the device properties ioctl
> +EVIOCGPROP, defined in linux/input.h, will be used to convey the device type.
> +
> +* BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP, BTN_TOOL_TRIPLETAP, BTN_TOOL_QUADTAP:
> + - These codes denote one, two, three, and four finger interaction on a
> + trackpad or touchscreen. For example, if the user uses two fingers and moves
> + them on the touchpad in an effort to scroll content on screen,
> + BTN_TOOL_DOUBLETAP should be set to value 1 for the duration of the motion.
> + Note that all BTN_TOOL_<name> codes and the BTN_TOUCH code are orthogonal in
> + purpose. A trackpad event generated by finger touches should generate events
> + for one code from each group. At most only one of these BTN_TOOL_<name>
> + codes should have a value of 1 during any synchronization frame.
> +
> +Note: Historically some drivers emitted multiple of the finger count codes with
> +a value of 1 in the same synchronization frame. This usage is deprecated.
> +
> +Note: In multitouch drivers, the input_mt_report_finger_count() function should
> +be used to emit these codes. Please see multi-touch-protocol.txt for details.
> +
> +EV_REL:
> +----------
> +EV_REL events describe relative changes in a property. For example, a mouse may
> +move to the left by a certain number of units, but its absolute position in
> +space is unknown. If the absolute position is known, EV_ABS codes should be used
> +instead of EV_REL codes.
> +
> +A few EV_REL codes have special meanings:
> +
> +* REL_WHEEL, REL_HWHEEL:
> + - These codes are used for vertical and horizontal scroll wheels,
> + respectively.
> +
> +EV_ABS:
> +----------
> +EV_ABS events describe absolute changes in a property. For example, a touchpad
> +may emit coordinates for a touch location.
> +
> +A few EV_ABS codes have special meanings:
> +
> +* ABS_DISTANCE:
> + - Used to describe the distance of a tool from an interaction surface. This
> + event should only be emitted while the tool is hovering, meaning in close
> + proximity of the device and while the value of the BTN_TOUCH code is 0. If
> + the input device may be used freely in three dimensions, consider ABS_Z
> + instead.
> +
> +* ABS_MT_<name>:
> + - Used to describe multitouch input events. Please see
> + multi-touch-protocol.txt for details.
> +
> +EV_SW:
> +----------
> +EV_SW events describe stateful binary switches. For example, the SW_LID code is
> +used to denote when a laptop lid is closed.
> +
> +Upon binding to a device or resuming from suspend, a driver must report the
> +the current switch state. This ensures that the device, kernel, and userspace
> +state is in sync.
> +
> +Upon resume, if the switch state is the same as before suspend, then the input
> +subsystem will filter out the duplicate switch state reports. The driver does
> +not need to keep the state of the switch at any time.
> +
> +EV_MSC:
> +----------
> +EV_MSC events are used for input and output events that do not fall under other
> +categories.
> +
> +EV_LED:
> +----------
> +EV_LED events are used for input and output to set and query the state of
> +various LEDs on devices.
> +
> +EV_REP:
> +----------
> +EV_REP events are used for specifying autorepeating events.
> +
> +EV_SND:
> +----------
> +EV_SND events are used for sending sound commands to simple sound output
> +devices.
> +
> +EV_FF:
> +----------
> +EV_FF events are used to initialize a force feedback capable device and to cause
> +such device to feedback.
> +
> +EV_PWR:
> +----------
> +EV_PWR events are a special type of event used specifically for power
> +mangement. Its usage is not well defined. To be addressed later.
> +
> +Guidelines:
> +==========
> +The guidelines below ensure proper single-touch and multi-finger functionality.
> +For multi-touch functionality, see the multi-touch-protocol.txt document for
> +more information.
> +
> +Mice:
> +----------
> +REL_{X,Y} must be reported when the mouse moves. BTN_LEFT must be used to report
> +the primary button press. BTN_{MIDDLE,RIGHT,4,5,etc.} should be used to report
> +further buttons of the device. REL_WHEEL and REL_HWHEEL should be used to report
> +scroll wheel events where available.
> +
> +Touchscreens:
> +----------
> +ABS_{X,Y} must be reported with the location of the touch. BTN_TOUCH must be
> +used to report when a touch is active on the screen.
> +BTN_{MOUSE,LEFT,MIDDLE,RIGHT} must not be reported as the result of touch
> +contact. BTN_TOOL_<name> events should be reported where possible.
> +
> +Trackpads:
> +----------
> +Legacy trackpads that only provide relative position information must report
> +events like mice described above.
> +
> +Trackpads that provide absolute touch position must report ABS_{X,Y} for the
> +location of the touch. BTN_TOUCH should be used to report when a touch is active
> +on the trackpad. Where multi-finger support is available, BTN_TOOL_<name> should
> +be used to report the number of touches active on the trackpad.
> +
> +Tablets:
> +----------
> +BTN_TOOL_<name> events must be reported when a stylus or other tool is active on
> +the tablet. ABS_{X,Y} must be reported with the location of the tool. BTN_TOUCH
> +should be used to report when the tool is in contact with the tablet.
> +BTN_{STYLUS,STYLUS2} should be used to report buttons on the tool itself. Any
> +button may be used for buttons on the tablet except BTN_{MOUSE,LEFT}.
> +BTN_{0,1,2,etc} are good generic codes for unlabeled buttons. Do not use
> +meaningful buttons, like BTN_FORWARD, unless the button is labeled for that
> +purpose on the device.
> --
> 1.7.4.1
>