forked from Minki/linux
[SCSI] remove Documentation/DocBook/scsidrivers.tmpl
This document is rather rudimentary and totally outdated. Fortunately Documentation/scsi/scsi_mid_low_api.txt replaces it quite nicely. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This commit is contained in:
Christoph Hellwig
James Bottomley
parent
d8c37e7b9a
commit
90356ac319
@ -9,9 +9,9 @@
|
||||
DOCBOOKS := wanbook.xml z8530book.xml mcabook.xml videobook.xml \
|
||||
kernel-hacking.xml kernel-locking.xml via-audio.xml \
|
||||
deviceiobook.xml procfs-guide.xml tulip-user.xml \
|
||||
writing_usb_driver.xml scsidrivers.xml sis900.xml \
|
||||
kernel-api.xml journal-api.xml lsm.xml usb.xml \
|
||||
gadget.xml libata.xml mtdnand.xml librs.xml
|
||||
writing_usb_driver.xml sis900.xml kernel-api.xml \
|
||||
journal-api.xml lsm.xml usb.xml gadget.xml libata.xml \
|
||||
mtdnand.xml librs.xml
|
||||
|
||||
###
|
||||
# The build process is as follows (targets):
|
||||
|
||||
@ -1,193 +0,0 @@
|
||||
<?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="scsidrivers">
|
||||
<bookinfo>
|
||||
<title>SCSI Subsystem Interfaces</title>
|
||||
|
||||
<authorgroup>
|
||||
<author>
|
||||
<firstname>Douglas</firstname>
|
||||
<surname>Gilbert</surname>
|
||||
<affiliation>
|
||||
<address>
|
||||
<email>dgilbert@interlog.com</email>
|
||||
</address>
|
||||
</affiliation>
|
||||
</author>
|
||||
</authorgroup>
|
||||
<pubdate>2003-08-11</pubdate>
|
||||
|
||||
<copyright>
|
||||
<year>2002</year>
|
||||
<year>2003</year>
|
||||
<holder>Douglas Gilbert</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
|
||||
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
|
||||
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>
|
||||
|
||||
<toc></toc>
|
||||
|
||||
<chapter id="intro">
|
||||
<title>Introduction</title>
|
||||
<para>
|
||||
This document outlines the interface between the Linux scsi mid level
|
||||
and lower level drivers. Lower level drivers are variously called HBA
|
||||
(host bus adapter) drivers, host drivers (HD) or pseudo adapter drivers.
|
||||
The latter alludes to the fact that a lower level driver may be a
|
||||
bridge to another IO subsystem (and the "ide-scsi" driver is an example
|
||||
of this). There can be many lower level drivers active in a running
|
||||
system, but only one per hardware type. For example, the aic7xxx driver
|
||||
controls adaptec controllers based on the 7xxx chip series. Most lower
|
||||
level drivers can control one or more scsi hosts (a.k.a. scsi initiators).
|
||||
</para>
|
||||
<para>
|
||||
This document can been found in an ASCII text file in the linux kernel
|
||||
source: <filename>Documentation/scsi/scsi_mid_low_api.txt</filename> .
|
||||
It currently hold a little more information than this document. The
|
||||
<filename>drivers/scsi/hosts.h</filename> and <filename>
|
||||
drivers/scsi/scsi.h</filename> headers contain descriptions of members
|
||||
of important structures for the scsi subsystem.
|
||||
</para>
|
||||
</chapter>
|
||||
|
||||
<chapter id="driver-struct">
|
||||
<title>Driver structure</title>
|
||||
<para>
|
||||
Traditionally a lower level driver for the scsi subsystem has been
|
||||
at least two files in the drivers/scsi directory. For example, a
|
||||
driver called "xyz" has a header file "xyz.h" and a source file
|
||||
"xyz.c". [Actually there is no good reason why this couldn't all
|
||||
be in one file.] Some drivers that have been ported to several operating
|
||||
systems (e.g. aic7xxx which has separate files for generic and
|
||||
OS-specific code) have more than two files. Such drivers tend to have
|
||||
their own directory under the drivers/scsi directory.
|
||||
</para>
|
||||
<para>
|
||||
scsi_module.c is normally included at the end of a lower
|
||||
level driver. For it to work a declaration like this is needed before
|
||||
it is included:
|
||||
<programlisting>
|
||||
static Scsi_Host_Template driver_template = DRIVER_TEMPLATE;
|
||||
/* DRIVER_TEMPLATE should contain pointers to supported interface
|
||||
functions. Scsi_Host_Template is defined hosts.h */
|
||||
#include "scsi_module.c"
|
||||
</programlisting>
|
||||
</para>
|
||||
<para>
|
||||
The scsi_module.c assumes the name "driver_template" is appropriately
|
||||
defined. It contains 2 functions:
|
||||
<orderedlist>
|
||||
<listitem><para>
|
||||
init_this_scsi_driver() called during builtin and module driver
|
||||
initialization: invokes mid level's scsi_register_host()
|
||||
</para></listitem>
|
||||
<listitem><para>
|
||||
exit_this_scsi_driver() called during closedown: invokes
|
||||
mid level's scsi_unregister_host()
|
||||
</para></listitem>
|
||||
</orderedlist>
|
||||
</para>
|
||||
<para>
|
||||
When a new, lower level driver is being added to Linux, the following
|
||||
files (all found in the drivers/scsi directory) will need some attention:
|
||||
Makefile, Config.help and Config.in . It is probably best to look at what
|
||||
an existing lower level driver does in this regard.
|
||||
</para>
|
||||
</chapter>
|
||||
|
||||
<chapter id="intfunctions">
|
||||
<title>Interface Functions</title>
|
||||
!EDocumentation/scsi/scsi_mid_low_api.txt
|
||||
</chapter>
|
||||
|
||||
<chapter id="locks">
|
||||
<title>Locks</title>
|
||||
<para>
|
||||
Each Scsi_Host instance has a spin_lock called Scsi_Host::default_lock
|
||||
which is initialized in scsi_register() [found in hosts.c]. Within the
|
||||
same function the Scsi_Host::host_lock pointer is initialized to point
|
||||
at default_lock with the scsi_assign_lock() function. Thereafter
|
||||
lock and unlock operations performed by the mid level use the
|
||||
Scsi_Host::host_lock pointer.
|
||||
</para>
|
||||
<para>
|
||||
Lower level drivers can override the use of Scsi_Host::default_lock by
|
||||
using scsi_assign_lock(). The earliest opportunity to do this would
|
||||
be in the detect() function after it has invoked scsi_register(). It
|
||||
could be replaced by a coarser grain lock (e.g. per driver) or a
|
||||
lock of equal granularity (i.e. per host). Using finer grain locks
|
||||
(e.g. per scsi device) may be possible by juggling locks in
|
||||
queuecommand().
|
||||
</para>
|
||||
</chapter>
|
||||
|
||||
<chapter id="changes">
|
||||
<title>Changes since lk 2.4 series</title>
|
||||
<para>
|
||||
io_request_lock has been replaced by several finer grained locks. The lock
|
||||
relevant to lower level drivers is Scsi_Host::host_lock and there is one
|
||||
per scsi host.
|
||||
</para>
|
||||
<para>
|
||||
The older error handling mechanism has been removed. This means the
|
||||
lower level interface functions abort() and reset() have been removed.
|
||||
</para>
|
||||
<para>
|
||||
In the 2.4 series the scsi subsystem configuration descriptions were
|
||||
aggregated with the configuration descriptions from all other Linux
|
||||
subsystems in the Documentation/Configure.help file. In the 2.5 series,
|
||||
the scsi subsystem now has its own (much smaller) drivers/scsi/Config.help
|
||||
file.
|
||||
</para>
|
||||
</chapter>
|
||||
|
||||
<chapter id="credits">
|
||||
<title>Credits</title>
|
||||
<para>
|
||||
The following people have contributed to this document:
|
||||
<orderedlist>
|
||||
<listitem><para>
|
||||
Mike Anderson <email>andmike@us.ibm.com</email>
|
||||
</para></listitem>
|
||||
<listitem><para>
|
||||
James Bottomley <email>James.Bottomley@steeleye.com</email>
|
||||
</para></listitem>
|
||||
<listitem><para>
|
||||
Patrick Mansfield <email>patmans@us.ibm.com</email>
|
||||
</para></listitem>
|
||||
</orderedlist>
|
||||
</para>
|
||||
</chapter>
|
||||
|
||||
</book>
|
||||
Loading…
Reference in New Issue
Block a user