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    ALSA: Add support for key reporting via the jack interface · ebb812cb
    Mark Brown 提交于
    Some devices provide support for detection of a small number of
    buttons on their jacks. One common implementation provides a single
    button, implemented by shorting the microphone to ground and detected
    along with microphone presence detection by detecting varying current
    draws on the microphone bias signal.
    
    Provide support for up to three buttons via the jack interface. These
    default to reporting BTN_n but an API is provided to allow these to
    be remapped to other keys by the machine driver where it knows what
    the keys are. More keys can be added with ease if required.
    
    This is only intended to support simple accessory button designs. If
    the interface is limiting then either creating a child device for the
    accessory or accessing the input device in the jack directly is
    recommended.
    Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>
    ebb812cb
jack.h 2.4 KB