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Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DocBook/uio-howto.tmpl | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/Documentation/DocBook/uio-howto.tmpl b/Documentation/DocBook/uio-howto.tmpl index df87d1b93605..6116b93608df 100644 --- a/Documentation/DocBook/uio-howto.tmpl +++ b/Documentation/DocBook/uio-howto.tmpl @@ -42,6 +42,12 @@ GPL version 2. <revhistory> <revision> + <revnumber>0.6</revnumber> + <date>2008-12-05</date> + <authorinitials>hjk</authorinitials> + <revremark>Added description of portio sysfs attributes.</revremark> + </revision> + <revision> <revnumber>0.5</revnumber> <date>2008-05-22</date> <authorinitials>hjk</authorinitials> @@ -318,6 +324,54 @@ interested in translating it, please email me offset = N * getpagesize(); </programlisting> +<para> + Sometimes there is hardware with memory-like regions that can not be + mapped with the technique described here, but there are still ways to + access them from userspace. The most common example are x86 ioports. + On x86 systems, userspace can access these ioports using + <function>ioperm()</function>, <function>iopl()</function>, + <function>inb()</function>, <function>outb()</function>, and similar + functions. +</para> +<para> + Since these ioport regions can not be mapped, they will not appear under + <filename>/sys/class/uio/uioX/maps/</filename> like the normal memory + described above. Without information about the port regions a hardware + has to offer, it becomes difficult for the userspace part of the + driver to find out which ports belong to which UIO device. +</para> +<para> + To address this situation, the new directory + <filename>/sys/class/uio/uioX/portio/</filename> was added. It only + exists if the driver wants to pass information about one or more port + regions to userspace. If that is the case, subdirectories named + <filename>port0</filename>, <filename>port1</filename>, and so on, + will appear underneath + <filename>/sys/class/uio/uioX/portio/</filename>. +</para> +<para> + Each <filename>portX/</filename> directory contains three read-only + files that show start, size, and type of the port region: +</para> +<itemizedlist> +<listitem> + <para> + <filename>start</filename>: The first port of this region. + </para> +</listitem> +<listitem> + <para> + <filename>size</filename>: The number of ports in this region. + </para> +</listitem> +<listitem> + <para> + <filename>porttype</filename>: A string describing the type of port. + </para> +</listitem> +</itemizedlist> + + </sect1> </chapter> @@ -356,6 +410,13 @@ See the description below for details. </para></listitem> <listitem><para> +<varname>struct uio_port port[ MAX_UIO_PORTS_REGIONS ]</varname>: Required +if you want to pass information about ioports to userspace. For each port +region you need to fill one of the <varname>uio_port</varname> structures. +See the description below for details. +</para></listitem> + +<listitem><para> <varname>long irq</varname>: Required. If your hardware generates an interrupt, it's your modules task to determine the irq number during initialization. If you don't have a hardware generated interrupt but @@ -448,6 +509,42 @@ Please do not touch the <varname>kobj</varname> element of <varname>struct uio_mem</varname>! It is used by the UIO framework to set up sysfs files for this mapping. Simply leave it alone. </para> + +<para> +Sometimes, your device can have one or more port regions which can not be +mapped to userspace. But if there are other possibilities for userspace to +access these ports, it makes sense to make information about the ports +available in sysfs. For each region, you have to set up a +<varname>struct uio_port</varname> in the <varname>port[]</varname> array. +Here's a description of the fields of <varname>struct uio_port</varname>: +</para> + +<itemizedlist> +<listitem><para> +<varname>char *porttype</varname>: Required. Set this to one of the predefined +constants. Use <varname>UIO_PORT_X86</varname> for the ioports found in x86 +architectures. +</para></listitem> + +<listitem><para> +<varname>unsigned long start</varname>: Required if the port region is used. +Fill in the number of the first port of this region. +</para></listitem> + +<listitem><para> +<varname>unsigned long size</varname>: Fill in the number of ports in this +region. If <varname>size</varname> is zero, the region is considered unused. +Note that you <emphasis>must</emphasis> initialize <varname>size</varname> +with zero for all unused regions. +</para></listitem> +</itemizedlist> + +<para> +Please do not touch the <varname>portio</varname> element of +<varname>struct uio_port</varname>! It is used internally by the UIO +framework to set up sysfs files for this region. Simply leave it alone. +</para> + </sect1> <sect1 id="adding_irq_handler"> |