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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
+ "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
+<book id="s390drivers">
+ <bookinfo>
+ <title>Writing s390 channel device drivers</title>
+ <authorgroup>
+ <author>
+ <firstname>Cornelia</firstname>
+ <surname>Huck</surname>
+ <affiliation>
+ <address>
+ <email>cornelia.huck@de.ibm.com</email>
+ </address>
+ </affiliation>
+ </author>
+ </authorgroup>
+ <copyright>
+ <year>2007</year>
+ <holder>IBM Corp.</holder>
+ </copyright>
+ <legalnotice>
+ <para>
+ This documentation is free software; you can redistribute
+ it and/or modify it under the terms of the GNU General Public
+ License as published by the Free Software Foundation; either
+ version 2 of the License, or (at your option) any later
+ version.
+ </para>
+ <para>
+ This program is distributed in the hope that it will be
+ useful, but WITHOUT ANY WARRANTY; without even the implied
+ See the GNU General Public License for more details.
+ </para>
+ <para>
+ You should have received a copy of the GNU General Public
+ License along with this program; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ MA 02111-1307 USA
+ </para>
+ <para>
+ For more details see the file COPYING in the source
+ distribution of Linux.
+ </para>
+ </legalnotice>
+ </bookinfo>
+ <chapter id="intro">
+ <title>Introduction</title>
+ <para>
+ This document describes the interfaces available for device drivers that
+ drive s390 based channel attached I/O devices. This includes interfaces for
+ interaction with the hardware and interfaces for interacting with the
+ common driver core. Those interfaces are provided by the s390 common I/O
+ layer.
+ </para>
+ <para>
+ The document assumes a familarity with the technical terms associated
+ with the s390 channel I/O architecture. For a description of this
+ architecture, please refer to the "z/Architecture: Principles of
+ Operation", IBM publication no. SA22-7832.
+ </para>
+ <para>
+ While most I/O devices on a s390 system are typically driven through the
+ channel I/O mechanism described here, there are various other methods
+ (like the diag interface). These are out of the scope of this document.
+ </para>
+ <para>
+ Some additional information can also be found in the kernel source
+ under Documentation/s390/driver-model.txt.
+ </para>
+ </chapter>
+ <chapter id="ccw">
+ <title>The ccw bus</title>
+ <para>
+ The ccw bus typically contains the majority of devices available to
+ a s390 system. Named after the channel command word (ccw), the basic
+ command structure used to address its devices, the ccw bus contains
+ so-called channel attached devices. They are addressed via I/O
+ subchannels, visible on the css bus. A device driver for
+ channel-attached devices, however, will never interact with the
+ subchannel directly, but only via the I/O device on the ccw bus,
+ the ccw device.
+ </para>
+ <sect1 id="channelIO">
+ <title>I/O functions for channel-attached devices</title>
+ <para>
+ Some hardware structures have been translated into C structures for use
+ by the common I/O layer and device drivers. For more information on
+ the hardware structures represented here, please consult the Principles
+ of Operation.
+ </para>
+ </sect1>
+ <sect1 id="ccwdev">
+ <title>ccw devices</title>
+ <para>
+ Devices that want to initiate channel I/O need to attach to the ccw bus.
+ Interaction with the driver core is done via the common I/O layer, which
+ provides the abstractions of ccw devices and ccw device drivers.
+ </para>
+ <para>
+ The functions that initiate or terminate channel I/O all act upon a
+ ccw device structure. Device drivers must not bypass those functions
+ or strange side effects may happen.
+ </para>
+ </sect1>
+ <sect1 id="cmf">
+ <title>The channel-measurement facility</title>
+ <para>
+ The channel-measurement facility provides a means to collect
+ measurement data which is made available by the channel subsystem
+ for each channel attached device.
+ </para>
+ </sect1>
+ </chapter>
+ <chapter id="ccwgroup">
+ <title>The ccwgroup bus</title>
+ <para>
+ The ccwgroup bus only contains artificial devices, created by the user.
+ Many networking devices (e.g. qeth) are in fact composed of several
+ ccw devices (like read, write and data channel for qeth). The
+ ccwgroup bus provides a mechanism to create a meta-device which
+ contains those ccw devices as slave devices and can be associated
+ with the netdevice.
+ </para>
+ <sect1 id="ccwgroupdevices">
+ <title>ccw group devices</title>
+ </sect1>
+ </chapter>
+ <chapter id="genericinterfaces">
+ <title>Generic interfaces</title>
+ <para>
+ Some interfaces are available to other drivers that do not necessarily
+ have anything to do with the busses described above, but still are
+ indirectly using basic infrastructure in the common I/O layer.
+ One example is the support for adapter interrupts.
+ </para>
+ </chapter>