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@@ -719,6 +719,62 @@ framework to set up sysfs files for this region. Simply leave it alone.
</para>
</sect1>
+<sect1 id="using uio_dmem_genirq">
+<title>Using uio_dmem_genirq for platform devices</title>
+ <para>
+ In addition to statically allocated memory ranges, they may also be
+ a desire to use dynamically allocated regions in a user space driver.
+ In particular, being able to access memory made available through the
+ dma-mapping API, may be particularly useful. The
+ <varname>uio_dmem_genirq</varname> driver provides a way to accomplish
+ this.
+ </para>
+ <para>
+ This driver is used in a similar manner to the
+ <varname>"uio_pdrv_genirq"</varname> driver with respect to interrupt
+ configuration and handling.
+ </para>
+ <para>
+ Set the <varname>.name</varname> element of
+ <varname>struct platform_device</varname> to
+ <varname>"uio_dmem_genirq"</varname> to use this driver.
+ </para>
+ <para>
+ When using this driver, fill in the <varname>.platform_data</varname>
+ element of <varname>struct platform_device</varname>, which is of type
+ <varname>struct uio_dmem_genirq_pdata</varname> and which contains the
+ following elements:
+ </para>
+ <itemizedlist>
+ <listitem><varname>struct uio_info uioinfo</varname>: The same
+ structure used as the <varname>uio_pdrv_genirq</varname> platform
+ data</listitem>
+ <listitem><varname>unsigned int *dynamic_region_sizes</varname>:
+ Pointer to list of sizes of dynamic memory regions to be mapped into
+ user space.
+ </listitem>
+ <listitem><varname>unsigned int num_dynamic_regions</varname>:
+ Number of elements in <varname>dynamic_region_sizes</varname> array.
+ </listitem>
+ </itemizedlist>
+ <para>
+ The dynamic regions defined in the platform data will be appended to
+ the <varname> mem[] </varname> array after the platform device
+ resources, which implies that the total number of static and dynamic
+ memory regions cannot exceed <varname>MAX_UIO_MAPS</varname>.
+ </para>
+ <para>
+ The dynamic memory regions will be allocated when the UIO device file,
+ <varname>/dev/uioX</varname> is opened.
+ Simiar to static memory resources, the memory region information for
+ dynamic regions is then visible via sysfs at
+ <varname>/sys/class/uio/uioX/maps/mapY/*</varname>.
+ The dynmaic memory regions will be freed when the UIO device file is
+ closed. When no processes are holding the device file open, the address
+ returned to userspace is ~0.
+ </para>
+</sect1>
+
</chapter>
<chapter id="userspace_driver" xreflabel="Writing a driver in user space">