Hi Chase, On Fri, Jan 7, 2011 at 3:28 PM, Chase Douglas <chase.douglas@xxxxxxxxxxxxx> wrote: > This commit adds the file Documentation/input/evdev-codes.txt. > > Cc: Henrik Rydberg <rydberg@xxxxxxxxxxx> > Cc: Chris Bagwell <chris@xxxxxxxxxxxxxx> > Cc: Peter Hutterer <peter.hutterer@xxxxxxxxx> > Cc: Nikolai Kondrashov <spbnick@xxxxxxxxx> > Cc: linux-input@xxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > Signed-off-by: Chase Douglas <chase.douglas@xxxxxxxxxxxxx> > --- > Documentation/input/evdev-codes.txt | 206 +++++++++++++++++++++++++++++++++++ > 1 files changed, 206 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..8d7262c > --- /dev/null > +++ b/Documentation/input/evdev-codes.txt > @@ -0,0 +1,206 @@ > +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. > + > +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 EVIOCGABS ioctl defined in linux/input.h. > + > +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 keyboard and other key-like input events. > + > +* EV_REL: > + - Used to describe relative input events, 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. > + > +* EV_MSC: > + - Used to describe miscellaneous input events 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 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. > + > +* 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 these codes and the BTN_TOOL_<name> and BTN_TOUCH codes 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 > + codes should have a value of 1 during any synchronization frame. I think the "Note" sentence needs an update. I can interpret it as defining 3 groups but only 2 exist. Maybe: "Note that all BTN_TOOL_<name> codes (include these finger touch codes) and the BTN_TOUCH code are orthogonal in purpose. " Thats my only comment. This doc will be great to have! I'll propose a couple of example event sequences to add once this gets committed. Chris > + > +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. > + > +* KEY_SUSPEND, KEY_POWER: > + - These codes are reserved for the EV_PWR type. > + > +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 > + 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. > + > +* 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. > + > +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 key event used specifically for monitoring > +power buttons and switches. The two codes in use are: > + > +* KEY_POWER: > + - Used to denote a power button event. > + > +* KEY_SUSPEND: > + - Used to denote a suspend button event. > -- > 1.7.1 > > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
