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<table class="head">
<tr>
<td class="head-ltitle">DEVICE_IDENTIFY(9)</td>
<td class="head-vol">Kernel Developer's Manual</td>
<td class="head-rtitle">DEVICE_IDENTIFY(9)</td>
</tr>
</table>
<div class="manual-text">
<section class="Sh">
<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1>
<p class="Pp"><code class="Nm">DEVICE_IDENTIFY</code> —
<span class="Nd">identify new child devices and register them</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp"><code class="In">#include
<<a class="In">sys/param.h</a>></code>
<br/>
<code class="In">#include <<a class="In">sys/bus.h</a>></code></p>
<p class="Pp"><var class="Ft">void</var>
<br/>
<code class="Fn">DEVICE_IDENTIFY</code>(<var class="Fa" style="white-space: nowrap;">driver_t
*driver</var>, <var class="Fa" style="white-space: nowrap;">device_t
parent</var>);</p>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">The identify method of a device driver is used to add devices that
cannot be enumerated by the standard method on a bus device. Devices can be
enumerated in various ways including accessing non-ambiguous device
registers and parsing firmware tables. Software-only pseudo devices are also
often enumerated via identify methods.</p>
<p class="Pp">For each newly identified device, a new device instance should be
created by invoking the <a class="Xr">BUS_ADD_CHILD(9)</a> method. If the
identify method is able to discover other properties about the new device,
those should also be set. For example, device resources should be added to
the device by calling <a class="Xr">bus_set_resource(9)</a> for each
resource.</p>
<p class="Pp">An identify method might be invoked multiple times. If a device
driver is unloaded and loaded, the identify method will be called a second
time after being reloaded. As a result, the identify method should avoid
duplicate devices. Devices added by identify methods typically use a fixed
device name in which case <a class="Xr">device_find_child(9)</a> can be used
to detect existing devices.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="EXAMPLES"><a class="permalink" href="#EXAMPLES">EXAMPLES</a></h1>
<p class="Pp">The following pseudo-code shows an example of a function that
probes for a piece of hardware and registers it and its resource (an I/O
port) with the parent bus device.</p>
<div class="Bd Pp Li">
<pre>void
foo_identify(driver_t *driver, device_t parent)
{
device_t child;
retrieve_device_information;
if (devices matches one of your supported devices &&
device_find_child(parent, "foo", DEVICE_UNIT_ANY) == NULL) {
child = BUS_ADD_CHILD(parent, 0, "foo", DEVICE_UNIT_ANY);
bus_set_resource(child, SYS_RES_IOPORT, 0, FOO_IOADDR, 1);
}
}</pre>
</div>
</section>
<section class="Sh">
<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE
ALSO</a></h1>
<p class="Pp"><a class="Xr">BUS_ADD_CHILD(9)</a>,
<a class="Xr">bus_identify_children(9)</a>,
<a class="Xr">bus_set_resource(9)</a>, <a class="Xr">device(9)</a>,
<a class="Xr">device_find_child(9)</a></p>
</section>
<section class="Sh">
<h1 class="Sh" id="AUTHORS"><a class="permalink" href="#AUTHORS">AUTHORS</a></h1>
<p class="Pp">This manual page was written by <span class="An">Alexander
Langer</span>
<<a class="Mt" href="mailto:alex@FreeBSD.org">alex@FreeBSD.org</a>>.</p>
</section>
</div>
<table class="foot">
<tr>
<td class="foot-date">February 5, 2025</td>
<td class="foot-os">FreeBSD 15.0</td>
</tr>
</table>
|
