diff options
| author | James Bottomley <jejb@titanic.(none)> | 2005-06-17 19:42:23 -0400 |
|---|---|---|
| committer | James Bottomley <jejb@titanic.(none)> | 2005-06-17 19:42:23 -0400 |
| commit | 3237ee78fc00f786d5f5aec6f9310b0e39069f15 (patch) | |
| tree | 4c94e70ab846ffcb8bb5715fb3c8d8473358a323 /Documentation/DocBook | |
| parent | 9ee1c939d1cb936b1f98e8d81aeffab57bae46ab (diff) | |
| parent | df0ae2497ddefd72a87f3a3b34ff32455d7d4ae0 (diff) | |
merge by hand (fix up qla_os.c merge error)
Diffstat (limited to 'Documentation/DocBook')
| -rw-r--r-- | Documentation/DocBook/Makefile | 2 | ||||
| -rw-r--r-- | Documentation/DocBook/scsidrivers.tmpl | 193 |
2 files changed, 1 insertions, 194 deletions
diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile index e69b3d2e7884..87da3478fada 100644 --- a/Documentation/DocBook/Makefile +++ b/Documentation/DocBook/Makefile | |||
| @@ -8,7 +8,7 @@ | |||
| 8 | 8 | ||
| 9 | DOCBOOKS := wanbook.xml z8530book.xml mcabook.xml videobook.xml \ | 9 | DOCBOOKS := wanbook.xml z8530book.xml mcabook.xml videobook.xml \ |
| 10 | kernel-hacking.xml kernel-locking.xml deviceiobook.xml \ | 10 | kernel-hacking.xml kernel-locking.xml deviceiobook.xml \ |
| 11 | procfs-guide.xml writing_usb_driver.xml scsidrivers.xml \ | 11 | procfs-guide.xml writing_usb_driver.xml \ |
| 12 | sis900.xml kernel-api.xml journal-api.xml lsm.xml usb.xml \ | 12 | sis900.xml kernel-api.xml journal-api.xml lsm.xml usb.xml \ |
| 13 | gadget.xml libata.xml mtdnand.xml librs.xml | 13 | gadget.xml libata.xml mtdnand.xml librs.xml |
| 14 | 14 | ||
diff --git a/Documentation/DocBook/scsidrivers.tmpl b/Documentation/DocBook/scsidrivers.tmpl deleted file mode 100644 index d058e65daf19..000000000000 --- a/Documentation/DocBook/scsidrivers.tmpl +++ /dev/null | |||
| @@ -1,193 +0,0 @@ | |||
| 1 | <?xml version="1.0" encoding="UTF-8"?> | ||
| 2 | <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" | ||
| 3 | "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> | ||
| 4 | |||
| 5 | <book id="scsidrivers"> | ||
| 6 | <bookinfo> | ||
| 7 | <title>SCSI Subsystem Interfaces</title> | ||
| 8 | |||
| 9 | <authorgroup> | ||
| 10 | <author> | ||
| 11 | <firstname>Douglas</firstname> | ||
| 12 | <surname>Gilbert</surname> | ||
| 13 | <affiliation> | ||
| 14 | <address> | ||
| 15 | <email>dgilbert@interlog.com</email> | ||
| 16 | </address> | ||
| 17 | </affiliation> | ||
| 18 | </author> | ||
| 19 | </authorgroup> | ||
| 20 | <pubdate>2003-08-11</pubdate> | ||
| 21 | |||
| 22 | <copyright> | ||
| 23 | <year>2002</year> | ||
| 24 | <year>2003</year> | ||
| 25 | <holder>Douglas Gilbert</holder> | ||
| 26 | </copyright> | ||
| 27 | |||
| 28 | <legalnotice> | ||
| 29 | <para> | ||
| 30 | This documentation is free software; you can redistribute | ||
| 31 | it and/or modify it under the terms of the GNU General Public | ||
| 32 | License as published by the Free Software Foundation; either | ||
| 33 | version 2 of the License, or (at your option) any later | ||
| 34 | version. | ||
| 35 | </para> | ||
| 36 | |||
| 37 | <para> | ||
| 38 | This program is distributed in the hope that it will be | ||
| 39 | useful, but WITHOUT ANY WARRANTY; without even the implied | ||
| 40 | warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. | ||
| 41 | See the GNU General Public License for more details. | ||
| 42 | </para> | ||
| 43 | |||
| 44 | <para> | ||
| 45 | You should have received a copy of the GNU General Public | ||
| 46 | License along with this program; if not, write to the Free | ||
| 47 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, | ||
| 48 | MA 02111-1307 USA | ||
| 49 | </para> | ||
| 50 | |||
| 51 | <para> | ||
| 52 | For more details see the file COPYING in the source | ||
| 53 | distribution of Linux. | ||
| 54 | </para> | ||
| 55 | </legalnotice> | ||
| 56 | |||
| 57 | </bookinfo> | ||
| 58 | |||
| 59 | <toc></toc> | ||
| 60 | |||
| 61 | <chapter id="intro"> | ||
| 62 | <title>Introduction</title> | ||
| 63 | <para> | ||
| 64 | This document outlines the interface between the Linux scsi mid level | ||
| 65 | and lower level drivers. Lower level drivers are variously called HBA | ||
| 66 | (host bus adapter) drivers, host drivers (HD) or pseudo adapter drivers. | ||
| 67 | The latter alludes to the fact that a lower level driver may be a | ||
| 68 | bridge to another IO subsystem (and the "ide-scsi" driver is an example | ||
| 69 | of this). There can be many lower level drivers active in a running | ||
| 70 | system, but only one per hardware type. For example, the aic7xxx driver | ||
| 71 | controls adaptec controllers based on the 7xxx chip series. Most lower | ||
| 72 | level drivers can control one or more scsi hosts (a.k.a. scsi initiators). | ||
| 73 | </para> | ||
| 74 | <para> | ||
| 75 | This document can been found in an ASCII text file in the linux kernel | ||
| 76 | source: <filename>Documentation/scsi/scsi_mid_low_api.txt</filename> . | ||
| 77 | It currently hold a little more information than this document. The | ||
| 78 | <filename>drivers/scsi/hosts.h</filename> and <filename> | ||
| 79 | drivers/scsi/scsi.h</filename> headers contain descriptions of members | ||
| 80 | of important structures for the scsi subsystem. | ||
| 81 | </para> | ||
| 82 | </chapter> | ||
| 83 | |||
| 84 | <chapter id="driver-struct"> | ||
| 85 | <title>Driver structure</title> | ||
| 86 | <para> | ||
| 87 | Traditionally a lower level driver for the scsi subsystem has been | ||
| 88 | at least two files in the drivers/scsi directory. For example, a | ||
| 89 | driver called "xyz" has a header file "xyz.h" and a source file | ||
| 90 | "xyz.c". [Actually there is no good reason why this couldn't all | ||
| 91 | be in one file.] Some drivers that have been ported to several operating | ||
| 92 | systems (e.g. aic7xxx which has separate files for generic and | ||
| 93 | OS-specific code) have more than two files. Such drivers tend to have | ||
| 94 | their own directory under the drivers/scsi directory. | ||
| 95 | </para> | ||
| 96 | <para> | ||
| 97 | scsi_module.c is normally included at the end of a lower | ||
| 98 | level driver. For it to work a declaration like this is needed before | ||
| 99 | it is included: | ||
| 100 | <programlisting> | ||
| 101 | static Scsi_Host_Template driver_template = DRIVER_TEMPLATE; | ||
| 102 | /* DRIVER_TEMPLATE should contain pointers to supported interface | ||
| 103 | functions. Scsi_Host_Template is defined hosts.h */ | ||
| 104 | #include "scsi_module.c" | ||
| 105 | </programlisting> | ||
| 106 | </para> | ||
| 107 | <para> | ||
| 108 | The scsi_module.c assumes the name "driver_template" is appropriately | ||
| 109 | defined. It contains 2 functions: | ||
| 110 | <orderedlist> | ||
| 111 | <listitem><para> | ||
| 112 | init_this_scsi_driver() called during builtin and module driver | ||
| 113 | initialization: invokes mid level's scsi_register_host() | ||
| 114 | </para></listitem> | ||
| 115 | <listitem><para> | ||
| 116 | exit_this_scsi_driver() called during closedown: invokes | ||
| 117 | mid level's scsi_unregister_host() | ||
| 118 | </para></listitem> | ||
| 119 | </orderedlist> | ||
| 120 | </para> | ||
| 121 | <para> | ||
| 122 | When a new, lower level driver is being added to Linux, the following | ||
| 123 | files (all found in the drivers/scsi directory) will need some attention: | ||
| 124 | Makefile, Config.help and Config.in . It is probably best to look at what | ||
| 125 | an existing lower level driver does in this regard. | ||
| 126 | </para> | ||
| 127 | </chapter> | ||
| 128 | |||
| 129 | <chapter id="intfunctions"> | ||
| 130 | <title>Interface Functions</title> | ||
| 131 | !EDocumentation/scsi/scsi_mid_low_api.txt | ||
| 132 | </chapter> | ||
| 133 | |||
| 134 | <chapter id="locks"> | ||
| 135 | <title>Locks</title> | ||
| 136 | <para> | ||
| 137 | Each Scsi_Host instance has a spin_lock called Scsi_Host::default_lock | ||
| 138 | which is initialized in scsi_register() [found in hosts.c]. Within the | ||
| 139 | same function the Scsi_Host::host_lock pointer is initialized to point | ||
| 140 | at default_lock with the scsi_assign_lock() function. Thereafter | ||
| 141 | lock and unlock operations performed by the mid level use the | ||
| 142 | Scsi_Host::host_lock pointer. | ||
| 143 | </para> | ||
| 144 | <para> | ||
| 145 | Lower level drivers can override the use of Scsi_Host::default_lock by | ||
| 146 | using scsi_assign_lock(). The earliest opportunity to do this would | ||
| 147 | be in the detect() function after it has invoked scsi_register(). It | ||
| 148 | could be replaced by a coarser grain lock (e.g. per driver) or a | ||
| 149 | lock of equal granularity (i.e. per host). Using finer grain locks | ||
| 150 | (e.g. per scsi device) may be possible by juggling locks in | ||
| 151 | queuecommand(). | ||
| 152 | </para> | ||
| 153 | </chapter> | ||
| 154 | |||
| 155 | <chapter id="changes"> | ||
| 156 | <title>Changes since lk 2.4 series</title> | ||
| 157 | <para> | ||
| 158 | io_request_lock has been replaced by several finer grained locks. The lock | ||
| 159 | relevant to lower level drivers is Scsi_Host::host_lock and there is one | ||
| 160 | per scsi host. | ||
| 161 | </para> | ||
| 162 | <para> | ||
| 163 | The older error handling mechanism has been removed. This means the | ||
| 164 | lower level interface functions abort() and reset() have been removed. | ||
| 165 | </para> | ||
| 166 | <para> | ||
| 167 | In the 2.4 series the scsi subsystem configuration descriptions were | ||
| 168 | aggregated with the configuration descriptions from all other Linux | ||
| 169 | subsystems in the Documentation/Configure.help file. In the 2.5 series, | ||
| 170 | the scsi subsystem now has its own (much smaller) drivers/scsi/Config.help | ||
| 171 | file. | ||
| 172 | </para> | ||
| 173 | </chapter> | ||
| 174 | |||
| 175 | <chapter id="credits"> | ||
| 176 | <title>Credits</title> | ||
| 177 | <para> | ||
| 178 | The following people have contributed to this document: | ||
| 179 | <orderedlist> | ||
| 180 | <listitem><para> | ||
| 181 | Mike Anderson <email>andmike@us.ibm.com</email> | ||
| 182 | </para></listitem> | ||
| 183 | <listitem><para> | ||
| 184 | James Bottomley <email>James.Bottomley@steeleye.com</email> | ||
| 185 | </para></listitem> | ||
| 186 | <listitem><para> | ||
| 187 | Patrick Mansfield <email>patmans@us.ibm.com</email> | ||
| 188 | </para></listitem> | ||
| 189 | </orderedlist> | ||
| 190 | </para> | ||
| 191 | </chapter> | ||
| 192 | |||
| 193 | </book> | ||
