Date:	Mon, 22 Dec 2008 11:03:32 -0800
From:	Randy Dunlap <randy.dunlap@...cle.com>
To:	"Hans J. Koch" <hjk@...utronix.de>
Cc:	linux-kernel@...r.kernel.org, gregkh@...e.de,
	Mike Frysinger <vapier@...too.org>,
	John Ogness <jogness@...utronix.de>,
	Benedikt Spranger <b.spranger@...utronix.de>
Subject: Re: [PATCH 2/2] UIO: Documentation for UIO ioport info handling

On Sat, 6 Dec 2008 02:25:13 +0100 Hans J. Koch wrote:

> This patch updates UIO documentation with the changes introduced by
> PATCH 1/2.
> 
> Signed-off-by: Hans J. Koch <hjk@...utronix.de>
> 
> ---
>  Documentation/DocBook/uio-howto.tmpl |   97 +++++++++++++++++++++++++++++++++++
>  1 file changed, 97 insertions(+)
> 
> Index: linux-2.6.28-rc/Documentation/DocBook/uio-howto.tmpl
> ===================================================================
> --- linux-2.6.28-rc.orig/Documentation/DocBook/uio-howto.tmpl	2008-12-06 01:13:56.000000000 +0100
> +++ linux-2.6.28-rc/Documentation/DocBook/uio-howto.tmpl	2008-12-06 01:54:14.000000000 +0100
> @@ -42,6 +42,12 @@
>  
>  <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 @@
>  offset = N * getpagesize();
>  </programlisting>
>  
> +<para>
> +	Sometimes there is hardware with memory-like regions that can not be

	                                                          cannot

> +	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

ditto

> +	<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 @@
>  </para></listitem>
>  
>  <listitem><para>
> +<varname>struct uio_port port[ MAX_UIO_PORTS_REGIONS ]</varname>: Required

odd spacing:  port[ MAX_UIO_PORTS_REGIONS ]

> +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 @@
>  <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

                                                                  cannot

> +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">


---
~Randy
--
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