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<table class="head">
<tr>
<td class="head-ltitle">nvmem(9)</td>
<td class="head-vol">Kernel Developer's Manual</td>
<td class="head-rtitle">nvmem(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">nvmem</code>,
<code class="Nm">nvmem_get_cell_len</code>,
<code class="Nm">nvmem_read_cell_by_name</code>,
<code class="Nm">nvmem_read_cell_by_idx</code>,
<code class="Nm">nvmem_write_cell_by_name</code>,
<code class="Nm">nvmem_write_cell_by_idx</code></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp"><code class="Cd">options FDT</code>
<br/>
<code class="Cd">device nvmem</code>
<br/>
<code class="In">#include
<<a class="In">sys/extres/nvmem/nvmem.h</a>></code></p>
<p class="Pp"><var class="Ft">int</var>
<br/>
<code class="Fn">nvmem_get_cell_len</code>(<var class="Fa" style="white-space: nowrap;">phandle_t
node</var>, <var class="Fa" style="white-space: nowrap;">const char
*name</var>);</p>
<p class="Pp"><var class="Ft">int</var>
<br/>
<code class="Fn">nvmem_read_cell_by_name</code>(<var class="Fa" style="white-space: nowrap;">phandle_t
node</var>, <var class="Fa" style="white-space: nowrap;">const char
*name</var>, <var class="Fa" style="white-space: nowrap;">void *cell</var>,
<var class="Fa" style="white-space: nowrap;">size_t buflen</var>);</p>
<p class="Pp"><var class="Ft">int</var>
<br/>
<code class="Fn">nvmem_read_cell_by_idx</code>(<var class="Fa" style="white-space: nowrap;">phandle_t
node</var>, <var class="Fa" style="white-space: nowrap;">int idx</var>,
<var class="Fa" style="white-space: nowrap;">void *cell</var>,
<var class="Fa" style="white-space: nowrap;">size_t buflen</var>);</p>
<p class="Pp"><var class="Ft">int</var>
<br/>
<code class="Fn">nvmem_write_cell_by_name</code>(<var class="Fa" style="white-space: nowrap;">phandle_t
node</var>, <var class="Fa" style="white-space: nowrap;">const char
*name</var>, <var class="Fa" style="white-space: nowrap;">void *cell</var>,
<var class="Fa" style="white-space: nowrap;">size_t buflen</var>);</p>
<p class="Pp"><var class="Ft">int</var>
<br/>
<code class="Fn">nvmem_write_cell_by_idx</code>(<var class="Fa" style="white-space: nowrap;">phandle_t
node</var>, <var class="Fa" style="white-space: nowrap;">int idx</var>,
<var class="Fa" style="white-space: nowrap;">void *cell</var>,
<var class="Fa" style="white-space: nowrap;">size_t buflen</var>);</p>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">On some embedded boards, the manufacturer stored some data on a
NVMEM (Non-Volatile Memory), this is generally stored in some eeprom or
fuses.</p>
<p class="Pp">The <code class="Nm">nvmem</code> API consist of helpers functions
for consumer and device methods for providers.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="FUNCTIONS"><a class="permalink" href="#FUNCTIONS">FUNCTIONS</a></h1>
<dl class="Bl-tag">
<dt id="nvmem_get_cell_len"><a class="permalink" href="#nvmem_get_cell_len"><code class="Fn">nvmem_get_cell_len</code></a>(<var class="Fa">phandle_t
node</var>, <var class="Fa">const char *name</var>)</dt>
<dd>Get the size of the cell base on the reg property on the node. Return the
size or ENOENT if the cell name wasn't found</dd>
<dt id="nvmem_read_cell_by_name"><a class="permalink" href="#nvmem_read_cell_by_name"><code class="Fn">nvmem_read_cell_by_name</code></a>(<var class="Fa">phandle_t
node</var>, <var class="Fa">const char *name</var>, <var class="Fa">void
*cell</var>, <var class="Fa">size_t buflen</var>)</dt>
<dd>Get the cell content based on the name. Return 0 on success or ENOENT if
the cell doesn't exists, ENXIO if no provider device was found, EINVAL if
the size isn't correct.</dd>
<dt id="nvmem_read_cell_by_idx"><a class="permalink" href="#nvmem_read_cell_by_idx"><code class="Fn">nvmem_read_cell_by_idx</code></a>(<var class="Fa">phandle_t
node</var>, <var class="Fa">int idx</var>, <var class="Fa">void *cell</var>,
<var class="Fa">size_t buflen</var>)</dt>
<dd>Get the cell content based on the id. Return 0 on success or ENOENT if the
cell doesn't exists, ENXIO if no provider device was found, EINVAL if the
size isn't correct.</dd>
<dt id="nvmem_write_cell_by_name"><a class="permalink" href="#nvmem_write_cell_by_name"><code class="Fn">nvmem_write_cell_by_name</code></a>(<var class="Fa">phandle_t
node</var>, <var class="Fa">const char *name</var>, <var class="Fa">void
*cell</var>, <var class="Fa">size_t buflen</var>)</dt>
<dd>Write the cell content based on the name. Return 0 on success or ENOENT if
the cell doesn't exists, ENXIO if no provider device was found, EINVAL if
the size isn't correct.</dd>
<dt id="nvmem_write_cell_by_idx"><a class="permalink" href="#nvmem_write_cell_by_idx"><code class="Fn">nvmem_write_cell_by_idx</code></a>(<var class="Fa">phandle_t
node</var>, <var class="Fa">int idx</var>, <var class="Fa">void *cell</var>,
<var class="Fa">size_t buflen</var>)</dt>
<dd>Write the cell content based on the id. Return 0 on success or ENOENT if
the cell doesn't exists, ENXIO if no provider device was found, EINVAL if
the size isn't correct.</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="DEVICE_METHODS"><a class="permalink" href="#DEVICE_METHODS">DEVICE
METHODS</a></h1>
<dl class="Bl-tag">
<dt id="nvmem_read"><a class="permalink" href="#nvmem_read"><code class="Fn">nvmem_read</code></a>(<var class="Fa">device_t
dev</var>, <var class="Fa">uint32_t offset</var>, <var class="Fa">uint32_t
size</var>, <var class="Fa">uint8_t *buffer</var>)</dt>
<dd>Provider device method to read a cell content.</dd>
<dt id="nvmem_write"><a class="permalink" href="#nvmem_write"><code class="Fn">nvmem_write</code></a>(<var class="Fa">device_t
dev</var>, <var class="Fa">uint32_t offset</var>, <var class="Fa">uint32_t
size</var>, <var class="Fa">uint8_t *buffer</var>)</dt>
<dd>Provider device method to write a cell content.</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="EXAMPLES"><a class="permalink" href="#EXAMPLES">EXAMPLES</a></h1>
<p class="Pp">Consider this DTS</p>
<div class="Bd Pp Li">
<pre>/* Provider */
eeprom: eeprom@20000 {
board_id: id@0 {
reg = <0x0 0x4>;
};
};
/* Consumer */
device@30000 {
...
nvmem-cells = <&board_id>
nvmem-cell-names = "boardid";
};</pre>
</div>
<p class="Pp">The device driver for eeprom@20000 needs to expose itself as a
provider</p>
<div class="Bd Pp Li">
<pre>#include "nvmem_if.h"
int
foo_nvmem_read(device_t dev, uint32_t offset, uint32_t size, uint8_t *buffer)
{
/* Read the data */
}
int
foo_attach(device_t dev)
{
phandle_t node;
node = ofw_bus_get_node(dev);
...
/* Registering the device so the consumers can find us */
OF_device_register_xref(OF_xref_from_node(node), dev);
...
}
static device_method_t foo_methods[] = {
...
/* nvmem interface */
DEVMETHOD(nvmem_read, foo_nvmem_read),
/* Terminate method list */
DEVMETHOD_END
};</pre>
</div>
<p class="Pp">The consumer device driver for device@30000 can now read the nvmem
data</p>
<div class="Bd Pp Li">
<pre>int
bar_attach(device_t dev)
{
phandle_t node;
uint32_t boardid;
...
node = ofw_bus_get_node(dev);
nvmem_read_cell_by_name(node, "boardid", (void *)&boardid, sizeof(boardid));
...
}</pre>
</div>
</section>
<section class="Sh">
<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1>
<p class="Pp">The nvmem related function first appear in
<span class="Ux">FreeBSD 12.0</span>. The nvmem interface and manual page
was written by <span class="An">Emmanuel Vadot</span>
<<a class="Mt" href="mailto:manu@FreeBSD.org">manu@FreeBSD.org</a>>.</p>
</section>
</div>
<table class="foot">
<tr>
<td class="foot-date">July 24, 2018</td>
<td class="foot-os">FreeBSD 15.0</td>
</tr>
</table>
|
