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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>struct ff_device</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="Linux Device Drivers" /><link rel="up" href="ch08.html" title="Chapter 8. Input Subsystem" /><link rel="prev" href="re705.html" title="struct input_handle" /><link rel="next" href="re707.html" title="input_event" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>struct ff_device</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re705.html">Prev</a> </td><th width="60%" align="center">Chapter 8. Input Subsystem</th><td width="20%" align="right"> <a accesskey="n" href="re707.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="struct ff_device"><a id="API-struct-ff-device"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>struct ff_device —
force-feedback part of an input device
</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><pre class="programlisting">
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[];
}; </pre></div><div class="refsect1" title="Members"><a id="id2699418"></a><h2>Members</h2><div class="variablelist"><dl><dt><span class="term">upload</span></dt><dd><p>
Called to upload an new effect into device
</p></dd><dt><span class="term">erase</span></dt><dd><p>
Called to erase an effect from device
</p></dd><dt><span class="term">playback</span></dt><dd><p>
Called to request device to start playing specified effect
</p></dd><dt><span class="term">set_gain</span></dt><dd><p>
Called to set specified gain
</p></dd><dt><span class="term">set_autocenter</span></dt><dd><p>
Called to auto-center device
</p></dd><dt><span class="term">destroy</span></dt><dd><p>
called by input core when parent input device is being
destroyed
</p></dd><dt><span class="term">private</span></dt><dd><p>
driver-specific data, will be freed automatically
</p></dd><dt><span class="term">ffbit[BITS_TO_LONGS(FF_CNT)]</span></dt><dd><p>
bitmap of force feedback capabilities truly supported by
device (not emulated like ones in input_dev->ffbit)
</p></dd><dt><span class="term">mutex</span></dt><dd><p>
mutex for serializing access to the device
</p></dd><dt><span class="term">max_effects</span></dt><dd><p>
maximum number of effects supported by device
</p></dd><dt><span class="term">effects</span></dt><dd><p>
pointer to an array of effects currently loaded into device
</p></dd><dt><span class="term">effect_owners[]</span></dt><dd><p>
array of effect owners; when file handle owning
an effect gets closed the effect is automatically erased
</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id2699577"></a><h2>Description</h2><p>
Every force-feedback device must implement <code class="function">upload</code> and <code class="function">playback</code>
methods; <code class="function">erase</code> is optional. <code class="function">set_gain</code> and <code class="function">set_autocenter</code> need
only be implemented if driver sets up FF_GAIN and FF_AUTOCENTER
bits.
</p><p>
Note that <code class="function">playback</code>, <code class="function">set_gain</code> and <code class="function">set_autocenter</code> are called with
dev->event_lock spinlock held and interrupts off and thus may not
sleep.
</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="re705.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch08.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="re707.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span>struct input_handle</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span>input_event</span></td></tr></table></div></body></html>
