static/freebsd/man9/OF_node_from_xref.9 3.html


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<table class="head">
  <tr>
    <td class="head-ltitle">OF_NODE_FROM_XREF(9)</td>
    <td class="head-vol">Kernel Developer's Manual</td>
    <td class="head-rtitle">OF_NODE_FROM_XREF(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">OF_node_from_xref</code>,
    <code class="Nm">OF_xref_from_node</code> &#x2014; <span class="Nd">convert
    between kernel phandle and effective phandle</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
    &lt;<a class="In">dev/ofw/ofw_bus.h</a>&gt;</code>
  <br/>
  <code class="In">#include
    &lt;<a class="In">dev/ofw/ofw_bus_subr.h</a>&gt;</code></p>
<p class="Pp"><var class="Ft">phandle_t</var>
  <br/>
  <code class="Fn">OF_node_from_xref</code>(<var class="Fa" style="white-space: nowrap;">phandle_t
    xref</var>);</p>
<p class="Pp"><var class="Ft">phandle_t</var>
  <br/>
  <code class="Fn">OF_xref_from_node</code>(<var class="Fa" style="white-space: nowrap;">phandle_t
    node</var>);</p>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">Some OpenFirmware implementations (FDT, IBM) have a concept of
    effective phandle or xrefs. They are used to cross-reference device tree
    nodes. For instance, a framebuffer controller may refer to a GPIO controller
    and pin that controls the backlight. In this example, the GPIO node would
    have a cell (32-bit integer) property with a reserved name like
    &quot;phandle&quot; or &quot;linux,phandle&quot; whose value uniquely
    identifies the node. The actual name depends on the implementation. The
    framebuffer node would have a property with the name described by device
    bindings (device-specific set of properties). It can be a cell property or a
    combined property with one part of it being a cell. The value of the
    framebuffer node's property would be the same as the value of the GPIO
    &quot;phandle&quot; property so it can be said that the framebuffer node
    refers to the GPIO node. The kernel uses internal logic to assign unique
    identifiers to the device tree nodes, and these values do not match the
    values of &quot;phandle&quot; properties.
    <a class="permalink" href="#OF_node_from_xref"><code class="Fn" id="OF_node_from_xref">OF_node_from_xref</code></a>()
    and <code class="Fn">OF_xref_from_node</code>() are used to perform
    conversion between these two kinds of node identifiers.</p>
<p class="Pp" id="OF_node_from_xref~2"><a class="permalink" href="#OF_node_from_xref~2"><code class="Fn">OF_node_from_xref</code></a>()
    returns the kernel phandle for the effective phandle
    <var class="Fa">xref</var>. If one cannot be found or the OpenFirmware
    implementation does not support effective phandles, the function returns the
    input value.</p>
<p class="Pp" id="OF_xref_from_node"><a class="permalink" href="#OF_xref_from_node"><code class="Fn">OF_xref_from_node</code></a>()
    returns the effective phandle for the kernel phandle
    <var class="Fa">node</var>. If one cannot be found or the OpenFirmware
    implementation does not support effective phandles, the function returns the
    input value.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="EXAMPLES"><a class="permalink" href="#EXAMPLES">EXAMPLES</a></h1>
<div class="Bd Li">
<pre>    phandle_t panelnode, panelxref;
    char *model;

    if (OF_getencprop(node, &quot;lcd-panel&quot;, &amp;panelxref) &lt;= 0)
        return;

    panelnode = OF_node_from_xref(panelxref);
    if (OF_getprop_alloc(hdminode, &quot;model&quot;, (void **)&amp;model) &lt;= 0)
        return;</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">OF_device_from_xref(9)</a>,
    <a class="Xr">OF_device_register_xref(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">Oleksandr
    Tymoshenko</span>
    &lt;<a class="Mt" href="mailto:gonzo@FreeBSD.org">gonzo@FreeBSD.org</a>&gt;.</p>
</section>
</div>
<table class="foot">
  <tr>
    <td class="foot-date">April 9, 2018</td>
    <td class="foot-os">FreeBSD 15.0</td>
  </tr>
</table>