1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>spi_sync</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="Linux Device Drivers"><link rel="up" href="spi.html" title="Chapter&#160;9.&#160;Serial Peripheral Interface (SPI)"><link rel="prev" href="API-spi-async-locked.html" title="spi_async_locked"><link rel="next" href="API-spi-sync-locked.html" title="spi_sync_locked"></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">spi_sync</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-spi-async-locked.html">Prev</a>&#160;</td><th width="60%" align="center">Chapter&#160;9.&#160;Serial Peripheral Interface (SPI)</th><td width="20%" align="right">&#160;<a accesskey="n" href="API-spi-sync-locked.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="API-spi-sync"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>spi_sync &#8212; 
2     blocking/synchronous SPI data transfers
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">spi_sync </b>(</code></td><td>struct spi_device * <var class="pdparam">spi</var>, </td></tr><tr><td>&#160;</td><td>struct spi_message * <var class="pdparam">message</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer">&#160;</div></div></div><div class="refsect1"><a name="idp1115173036"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>spi</code></em></span></dt><dd><p>
4     device with which data will be exchanged
5    </p></dd><dt><span class="term"><em class="parameter"><code>message</code></em></span></dt><dd><p>
6     describes the data transfers
7    </p></dd></dl></div></div><div class="refsect1"><a name="idp1115175684"></a><h2>Context</h2><p>
8   can sleep
9</p></div><div class="refsect1"><a name="idp1115176276"></a><h2>Description</h2><p>
10   This call may only be used from a context that may sleep.  The sleep
11   is non-interruptible, and has no timeout.  Low-overhead controller
12   drivers may DMA directly into and out of the message buffers.
13   </p><p>
14
15   Note that the SPI device's chip select is active during the message,
16   and then is normally disabled between messages.  Drivers for some
17   frequently-used devices may want to minimize costs of selecting a chip,
18   by leaving it selected in anticipation that the next message will go
19   to the same chip.  (That may increase power usage.)
20   </p><p>
21
22   Also, the caller is guaranteeing that the memory associated with the
23   message will not be freed before this call returns.
24   </p><p>
25
26   It returns zero on success, else a negative error code.
27</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-spi-async-locked.html">Prev</a>&#160;</td><td width="20%" align="center"><a accesskey="u" href="spi.html">Up</a></td><td width="40%" align="right">&#160;<a accesskey="n" href="API-spi-sync-locked.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">spi_async_locked</span>&#160;</td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top">&#160;<span class="phrase">spi_sync_locked</span></td></tr></table></div></body></html>
28