UIO: fix up the UIO documentation

Remove references to the old uio_dummy demo module from UIO documentation.
Add a small paragraph to make it clearer that UIO is not a universal driver
interface.

Signed-off-by: Hans J Koch <hjk@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 32 insertions, 58 deletions

diff --git a/Documentation/DocBook/uio-howto.tmpl b/Documentation/DocBook/uio-howto.tmpl
index c119484258b8..fdd7f4f887b7 100644
--- a/Documentation/DocBook/uio-howto.tmpl
+++ b/Documentation/DocBook/uio-howto.tmpl
@@ -30,6 +30,12 @@
 
 <revhistory>
         <revision>
+        <revnumber>0.4</revnumber>
+        <date>2007-11-26</date>
+        <authorinitials>hjk</authorinitials>
+        <revremark>Removed section about uio_dummy.</revremark>
+        </revision>
+        <revision>
         <revnumber>0.3</revnumber>
         <date>2007-04-29</date>
         <authorinitials>hjk</authorinitials>
@@ -94,6 +100,26 @@ interested in translating it, please email me
         user space. This simplifies development and reduces the risk of
         serious bugs within a kernel module.
         </para>
+        <para>
+        Please note that UIO is not an universal driver interface. Devices
+        that are already handled well by other kernel subsystems (like
+        networking or serial or USB) are no candidates for an UIO driver.
+        Hardware that is ideally suited for an UIO driver fulfills all of
+        the following:
+        </para>
+<itemizedlist>
+<listitem>
+        <para>The device has memory that can be mapped. The device can be
+        controlled completely by writing to this memory.</para>
+</listitem>
+<listitem>
+        <para>The device usually generates interrupts.</para>
+</listitem>
+<listitem>
+        <para>The device does not fit into one of the standard kernel
+        subsystems.</para>
+</listitem>
+</itemizedlist>
 </sect1>
 
 <sect1 id="thanks">
@@ -174,8 +200,9 @@ interested in translating it, please email me
         For cards that don't generate interrupts but need to be
         polled, there is the possibility to set up a timer that
         triggers the interrupt handler at configurable time intervals.
-        See <filename>drivers/uio/uio_dummy.c</filename> for an
-        example of this technique.
+        This interrupt simulation is done by calling
+        <function>uio_event_notify()</function>
+        from the timer's event handler.
         </para>
 
         <para>
@@ -263,63 +290,11 @@ offset = N * getpagesize();
 </sect1>
 </chapter>
 
-<chapter id="using-uio_dummy" xreflabel="Using uio_dummy">
-<?dbhtml filename="using-uio_dummy.html"?>
-<title>Using uio_dummy</title>
-        <para>
-        Well, there is no real use for uio_dummy. Its only purpose is
-        to test most parts of the UIO system (everything except
-        hardware interrupts), and to serve as an example for the
-        kernel module that you will have to write yourself.
-        </para>
-
-<sect1 id="what_uio_dummy_does">
-<title>What uio_dummy does</title>
-        <para>
-        The kernel module <filename>uio_dummy.ko</filename> creates a
-        device that uses a timer to generate periodic interrupts. The
-        interrupt handler does nothing but increment a counter. The
-        driver adds two custom attributes, <varname>count</varname>
-        and <varname>freq</varname>, that appear under
-        <filename>/sys/devices/platform/uio_dummy/</filename>.
-        </para>
-
-        <para>
-        The attribute <varname>count</varname> can be read and
-        written.  The associated file
-        <filename>/sys/devices/platform/uio_dummy/count</filename>
-        appears as a normal text file and contains the total number of
-        timer interrupts. If you look at it (e.g. using
-        <function>cat</function>), you'll notice it is slowly counting
-        up.
-        </para>
-
-        <para>
-        The attribute <varname>freq</varname> can be read and written.
-        The content of
-        <filename>/sys/devices/platform/uio_dummy/freq</filename>
-        represents the number of system timer ticks between two timer
-        interrupts. The default value of <varname>freq</varname> is
-        the value of the kernel variable <varname>HZ</varname>, which
-        gives you an interval of one second. Lower values will
-        increase the frequency. Try the following:
-        </para>
-<programlisting format="linespecific">
-cd /sys/devices/platform/uio_dummy/
-echo 100 > freq
-</programlisting>
-        <para>
-        Use <function>cat count</function> to see how the interrupt
-        frequency changes.
-        </para>
-</sect1>
-</chapter>
-
 <chapter id="custom_kernel_module" xreflabel="Writing your own kernel module">
 <?dbhtml filename="custom_kernel_module.html"?>
 <title>Writing your own kernel module</title>
         <para>
-        Please have a look at <filename>uio_dummy.c</filename> as an
+        Please have a look at <filename>uio_cif.c</filename> as an
         example. The following paragraphs explain the different
         sections of this file.
         </para>
@@ -354,9 +329,8 @@ See the description below for details.
 interrupt, it's your modules task to determine the irq number during
 initialization. If you don't have a hardware generated interrupt but
 want to trigger the interrupt handler in some other way, set
-<varname>irq</varname> to <varname>UIO_IRQ_CUSTOM</varname>. The
-uio_dummy module does this as it triggers the event mechanism in a timer
-routine. If you had no interrupt at all, you could set
+<varname>irq</varname> to <varname>UIO_IRQ_CUSTOM</varname>.
+If you had no interrupt at all, you could set
 <varname>irq</varname> to <varname>UIO_IRQ_NONE</varname>, though this
 rarely makes sense.
 </para></listitem>