1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>usb_add_function</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="USB Gadget API for Linux"><link rel="up" href="composite.html" title="Composite Device Framework"><link rel="prev" href="API-config-ep-by-speed.html" title="config_ep_by_speed"><link rel="next" href="API-usb-function-deactivate.html" title="usb_function_deactivate"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span class="phrase">usb_add_function</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-config-ep-by-speed.html">Prev</a>&#160;</td><th width="60%" align="center">Composite Device Framework</th><td width="20%" align="right">&#160;<a accesskey="n" href="API-usb-function-deactivate.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-usb-add-function"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>usb_add_function &#8212; 
2     add a function to a configuration
3 </p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">usb_add_function </b>(</code></td><td>struct usb_configuration * <var class="pdparam">config</var>, </td></tr><tr><td>&#160;</td><td>struct usb_function * <var class="pdparam">function</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1124405596"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>config</code></em></span></dt><dd><p>
4     the configuration
5    </p></dd><dt><span class="term"><em class="parameter"><code>function</code></em></span></dt><dd><p>
6     the function being added
7    </p></dd></dl></div></div><div class="refsect1"><a name="idp1124408156"></a><h2>Context</h2><p>
8   single threaded during gadget setup
9</p></div><div class="refsect1"><a name="idp1124408780"></a><h2>Description</h2><p>
10   After initialization, each configuration must have one or more
11   functions added to it.  Adding a function involves calling its <em class="parameter"><code>bind</code></em>()
12   method to allocate resources such as interface and string identifiers
13   and endpoints.
14   </p><p>
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16   This function returns the value of the function's <code class="function">bind</code>, which is
17   zero for success else a negative errno value.
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