'\" t
.\"     Title: struct ff_device
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.78.1 <http://docbook.sf.net/>
.\"      Date: January 2017
.\"    Manual: Input Subsystem
.\"    Source: Kernel Hackers Manual 4.8.15
.\"  Language: English
.\"
.TH "STRUCT FF_DEVICE" "9" "January 2017" "Kernel Hackers Manual 4\&.8\&." "Input Subsystem"
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.SH "NAME"
struct_ff_device \- force\-feedback part of an input device
.SH "SYNOPSIS"
.sp
.nf
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[];
};  
.fi
.SH "MEMBERS"
.PP
upload
.RS 4
Called to upload an new effect into device
.RE
.PP
erase
.RS 4
Called to erase an effect from device
.RE
.PP
playback
.RS 4
Called to request device to start playing specified effect
.RE
.PP
set_gain
.RS 4
Called to set specified gain
.RE
.PP
set_autocenter
.RS 4
Called to auto\-center device
.RE
.PP
destroy
.RS 4
called by input core when parent input device is being destroyed
.RE
.PP
private
.RS 4
driver\-specific data, will be freed automatically
.RE
.PP
ffbit[BITS_TO_LONGS(FF_CNT)]
.RS 4
bitmap of force feedback capabilities truly supported by device (not emulated like ones in input_dev\->ffbit)
.RE
.PP
mutex
.RS 4
mutex for serializing access to the device
.RE
.PP
max_effects
.RS 4
maximum number of effects supported by device
.RE
.PP
effects
.RS 4
pointer to an array of effects currently loaded into device
.RE
.PP
effect_owners[]
.RS 4
array of effect owners; when file handle owning an effect gets closed the effect is automatically erased
.RE
.SH "DESCRIPTION"
.PP
Every force\-feedback device must implement
\fBupload\fR
and
\fBplayback\fR
methods;
\fBerase\fR
is optional\&.
\fBset_gain\fR
and
\fBset_autocenter\fR
need only be implemented if driver sets up FF_GAIN and FF_AUTOCENTER bits\&.
.PP
Note that
\fBplayback\fR,
\fBset_gain\fR
and
\fBset_autocenter\fR
are called with dev\->event_lock spinlock held and interrupts off and thus may not sleep\&.
.SH "COPYRIGHT"
.br