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<table class="head">
<tr>
<td class="head-ltitle">AT45D(4)</td>
<td class="head-vol">Device Drivers Manual</td>
<td class="head-rtitle">AT45D(4)</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">at45d</code> — <span class="Nd">driver for
DataFlash(tm) non-volatile storage devices</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp">To compile this driver into the kernel, place the following line
in your kernel configuration file:</p>
<div class="Bd Pp Bd-indent"><code class="Cd">device at45d</code></div>
<p class="Pp">Alternatively, to load the driver as a module at boot time, place
the following line in <a class="Xr">loader.conf(5)</a>:</p>
<div class="Bd Pp Bd-indent Li">
<pre>at45d_load="YES"</pre>
</div>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">The <code class="Nm">at45d</code> driver provides support for the
family of non-volatile storage devices known collectively as DataFlash(tm).
DataFlash chips typically have part numbers beginning with AT45DB. The
<code class="Nm">at45d</code> driver supports only the SPI bus versions of
each AT45DB device, indicated by the last digit of the part number being 1
or 2.</p>
<p class="Pp">The <code class="Nm">at45d</code> driver uses opcode 0x9f to read
the manufacturer and device ID data to determine whether the device is
supported. The device ID is looked up using a table of data within the
driver which describes the attributes of each supported device, such as
block size, sector size, and device capacity. When a supported device is
found, the <code class="Nm">at45d</code> driver creates a disk device and
makes it accessible at <span class="Pa">/dev/flash/at45d?</span>. The new
disk device is then tasted by the available <a class="Xr">geom(4)</a>
modules as with any disk device.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="HARDWARE"><a class="permalink" href="#HARDWARE">HARDWARE</a></h1>
<p class="Pp">The <code class="Nm">at45d</code> driver provides support for the
following devices:</p>
<p class="Pp"></p>
<ul class="Bl-bullet Bl-compact">
<li>AT45DB011B</li>
<li>AT45DB021B</li>
<li>AT45DB041x</li>
<li>AT45DB081B</li>
<li>AT45DB161x</li>
<li>AT45DB321x</li>
<li>AT45DB321x</li>
<li>AT45DB641E</li>
<li>AT45DB642x</li>
</ul>
</section>
<section class="Sh">
<h1 class="Sh" id="FDT_CONFIGURATION"><a class="permalink" href="#FDT_CONFIGURATION">FDT
CONFIGURATION</a></h1>
<p class="Pp">On an <a class="Xr">fdt(4)</a> based system, the
<code class="Nm">at45d</code> device is defined as a slave device subnode of
the SPI bus controller node. All properties documented in the
<var class="Va">spibus.txt</var> bindings document can be used with the
<code class="Nm">at45d</code> device. The most commonly-used ones are
documented below.</p>
<p class="Pp">The following properties are required in the
<code class="Nm">at45d</code> device subnode:</p>
<dl class="Bl-tag">
<dt id="compatible"><var class="Va">compatible</var></dt>
<dd>Must be the string "atmel,at45".</dd>
<dt id="reg"><var class="Va">reg</var></dt>
<dd>Chip select address of device.</dd>
<dt id="spi-max-frequency"><var class="Va">spi-max-frequency</var></dt>
<dd>The maximum bus frequency to use when communicating with this slave
device. Actual bus speed may be lower, depending on the capabilities of
the SPI bus controller hardware.</dd>
</dl>
<p class="Pp">The following properties are optional for the
<code class="Nm">at45d</code> device subnode:</p>
<dl class="Bl-tag">
<dt id="freebsd,sectorsize"><var class="Va">freebsd,sectorsize</var></dt>
<dd>The sector size of the disk created for this storage device. It must be a
multiple of the device's page size. The default is the device page
size.</dd>
<dt id="spi-cpha"><var class="Va">spi-cpha</var></dt>
<dd>Empty property indicating the slave device requires shifted clock phase
(CPHA) mode.</dd>
<dt id="spi-cpol"><var class="Va">spi-cpol</var></dt>
<dd>Empty property indicating the slave device requires inverse clock polarity
(CPOL) mode.</dd>
<dt id="spi-cs-high"><var class="Va">spi-cs-high</var></dt>
<dd>Empty property indicating the slave device requires chip select active
high.</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="HINTS_CONFIGURATION"><a class="permalink" href="#HINTS_CONFIGURATION">HINTS
CONFIGURATION</a></h1>
<p class="Pp">On a <a class="Xr">device.hints(5)</a> based system, such as
<code class="Li">MIPS</code>, these values are configurable for
<code class="Nm">at45d</code>:</p>
<dl class="Bl-tag">
<dt id="hint.at45d._d.at"><var class="Va">hint.at45d.%d.at</var></dt>
<dd>The spibus the <code class="Nm">at45d</code> instance is attached to.</dd>
<dt id="hint.at45d._d.clock"><var class="Va">hint.at45d.%d.clock</var></dt>
<dd>The maximum bus frequency to use when communicating with this device.
Actual bus speed may be lower, depending on the capabilities of the SPI
bus controller hardware.</dd>
<dt id="hint.at45d._d.cs"><var class="Va">hint.at45d.%d.cs</var></dt>
<dd>The chip-select number to assert when performing I/O for this device. Set
the high bit (1 << 31) to invert the logic level of the chip select
line.</dd>
<dt id="hint.at45d._d.mode"><var class="Va">hint.at45d.%d.mode</var></dt>
<dd>The SPI mode (0-3) to use when communicating with this device.</dd>
<dt id="hint.at45d._d.sectorsize"><var class="Va">hint.at45d.%d.sectorsize</var></dt>
<dd>The sector size of the disk created for this storage device. It must be a
multiple of the device's page size. The default is the device page
size.</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="FILES"><a class="permalink" href="#FILES">FILES</a></h1>
<dl class="Bl-tag">
<dt><span class="Pa">/dev/flash/at45d?</span></dt>
<dd>Provides read/write access to the storage device.</dd>
<dt><span class="Pa">/dev/flash/spi?</span></dt>
<dd>An alias for the <span class="Pa">/dev/at45d?</span> device, for backwards
compatibility with older versions of the driver.</dd>
</dl>
</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">fdt(4)</a>, <a class="Xr">geom(4)</a></p>
</section>
<section class="Sh">
<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1>
<p class="Pp">The <code class="Nm">at45d</code> driver first appeared in
<span class="Ux">FreeBSD 6.0</span>.</p>
</section>
</div>
<table class="foot">
<tr>
<td class="foot-date">March 2, 2019</td>
<td class="foot-os">FreeBSD 15.0</td>
</tr>
</table>
|
