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STRUCT FF_DEVICE(9) Input Subsystem STRUCT FF_DEVICE(9)

NAME

struct_ff_device - force-feedback part of an input device

SYNOPSIS

struct ff_device {


  int (* upload) (struct input_dev *dev, struct ff_effect *effect,struct ff_effect *old);


  int (* erase) (struct input_dev *dev, int effect_id);


  int (* playback) (struct input_dev *dev, int effect_id, int value);


  void (* set_gain) (struct input_dev *dev, u16 gain);


  void (* set_autocenter) (struct input_dev *dev, u16 magnitude);


  void (* destroy) (struct ff_device *);


  void * private;


  unsigned long ffbit[BITS_TO_LONGS(FF_CNT)];


  struct mutex mutex;


  int max_effects;


  struct ff_effect * effects;


  struct file * effect_owners[];
};

MEMBERS

upload

Called to upload an new effect into device

erase

Called to erase an effect from device

playback

Called to request device to start playing specified effect

set_gain

Called to set specified gain

set_autocenter

Called to auto-center device

destroy

called by input core when parent input device is being destroyed

private

driver-specific data, will be freed automatically

ffbit[BITS_TO_LONGS(FF_CNT)]

bitmap of force feedback capabilities truly supported by device (not emulated like ones in input_dev->ffbit)

mutex

mutex for serializing access to the device

max_effects

maximum number of effects supported by device

effects

pointer to an array of effects currently loaded into device

effect_owners[]

array of effect owners; when file handle owning an effect gets closed the effect is automatically erased

DESCRIPTION

Every force-feedback device must implement upload and playback methods; erase is optional. set_gain and set_autocenter need only be implemented if driver sets up FF_GAIN and FF_AUTOCENTER bits.

Note that playback, set_gain and set_autocenter are called with dev->event_lock spinlock held and interrupts off and thus may not sleep.

COPYRIGHT

June 2024 Kernel Hackers Manual 3.10