security: Convert LSM into a static interface
[linux-2.6-block.git] / Documentation / DocBook / kernel-api.tmpl
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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="LinuxKernelAPI">
6 <bookinfo>
7 <title>The Linux Kernel API</title>
8
9 <legalnotice>
10 <para>
11 This documentation is free software; you can redistribute
12 it and/or modify it under the terms of the GNU General Public
13 License as published by the Free Software Foundation; either
14 version 2 of the License, or (at your option) any later
15 version.
16 </para>
17
18 <para>
19 This program is distributed in the hope that it will be
20 useful, but WITHOUT ANY WARRANTY; without even the implied
21 warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
22 See the GNU General Public License for more details.
23 </para>
24
25 <para>
26 You should have received a copy of the GNU General Public
27 License along with this program; if not, write to the Free
28 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
29 MA 02111-1307 USA
30 </para>
31
32 <para>
33 For more details see the file COPYING in the source
34 distribution of Linux.
35 </para>
36 </legalnotice>
37 </bookinfo>
38
39<toc></toc>
40
41 <chapter id="Basics">
42 <title>Driver Basics</title>
43 <sect1><title>Driver Entry and Exit points</title>
44!Iinclude/linux/init.h
45 </sect1>
46
47 <sect1><title>Atomic and pointer manipulation</title>
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48!Iinclude/asm-x86/atomic_32.h
49!Iinclude/asm-x86/unaligned_32.h
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50 </sect1>
51
1da177e4 52 <sect1><title>Delaying, scheduling, and timer routines</title>
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53!Iinclude/linux/sched.h
54!Ekernel/sched.c
55!Ekernel/timer.c
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56 </sect1>
57 <sect1><title>High-resolution timers</title>
58!Iinclude/linux/ktime.h
59!Iinclude/linux/hrtimer.h
60!Ekernel/hrtimer.c
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61 </sect1>
62 <sect1><title>Workqueues and Kevents</title>
63!Ekernel/workqueue.c
1da177e4 64 </sect1>
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65 <sect1><title>Internal Functions</title>
66!Ikernel/exit.c
67!Ikernel/signal.c
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68!Iinclude/linux/kthread.h
69!Ekernel/kthread.c
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70 </sect1>
71
72 <sect1><title>Kernel objects manipulation</title>
73<!--
74X!Iinclude/linux/kobject.h
75-->
76!Elib/kobject.c
77 </sect1>
78
79 <sect1><title>Kernel utility functions</title>
80!Iinclude/linux/kernel.h
ddad86c2 81!Ekernel/printk.c
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82!Ekernel/panic.c
83!Ekernel/sys.c
84!Ekernel/rcupdate.c
85 </sect1>
86
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87 <sect1><title>Device Resource Management</title>
88!Edrivers/base/devres.c
89 </sect1>
90
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91 </chapter>
92
93 <chapter id="adt">
94 <title>Data Types</title>
95 <sect1><title>Doubly Linked Lists</title>
96!Iinclude/linux/list.h
97 </sect1>
98 </chapter>
99
100 <chapter id="libc">
101 <title>Basic C Library Functions</title>
102
103 <para>
104 When writing drivers, you cannot in general use routines which are
105 from the C Library. Some of the functions have been found generally
106 useful and they are listed below. The behaviour of these functions
107 may vary slightly from those defined by ANSI, and these deviations
108 are noted in the text.
109 </para>
110
111 <sect1><title>String Conversions</title>
112!Ilib/vsprintf.c
113!Elib/vsprintf.c
114 </sect1>
115 <sect1><title>String Manipulation</title>
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116<!-- All functions are exported at now
117X!Ilib/string.c
118 -->
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119!Elib/string.c
120 </sect1>
121 <sect1><title>Bit Operations</title>
f3cf31ad 122!Iinclude/asm-x86/bitops_32.h
1da177e4 123 </sect1>
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124 </chapter>
125
126 <chapter id="kernel-lib">
127 <title>Basic Kernel Library Functions</title>
128
129 <para>
130 The Linux kernel provides more basic utility functions.
131 </para>
132
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133 <sect1><title>Bitmap Operations</title>
134!Elib/bitmap.c
135!Ilib/bitmap.c
136 </sect1>
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137
138 <sect1><title>Command-line Parsing</title>
139!Elib/cmdline.c
140 </sect1>
2f72100c 141
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142 <sect1 id="crc"><title>CRC Functions</title>
143!Elib/crc7.c
2f72100c 144!Elib/crc16.c
ad241528 145!Elib/crc-itu-t.c
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146!Elib/crc32.c
147!Elib/crc-ccitt.c
148 </sect1>
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149 </chapter>
150
151 <chapter id="mm">
152 <title>Memory Management in Linux</title>
153 <sect1><title>The Slab Cache</title>
800590f5 154!Iinclude/linux/slab.h
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155!Emm/slab.c
156 </sect1>
157 <sect1><title>User Space Memory Access</title>
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158!Iinclude/asm-x86/uaccess_32.h
159!Earch/x86/lib/usercopy_32.c
1da177e4 160 </sect1>
4dc3b16b 161 <sect1><title>More Memory Management Functions</title>
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162!Emm/readahead.c
163!Emm/filemap.c
164!Emm/memory.c
165!Emm/vmalloc.c
88ca3b94 166!Imm/page_alloc.c
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167!Emm/mempool.c
168!Emm/page-writeback.c
169!Emm/truncate.c
170 </sect1>
171 </chapter>
172
173
174 <chapter id="ipc">
175 <title>Kernel IPC facilities</title>
176
177 <sect1><title>IPC utilities</title>
178!Iipc/util.c
179 </sect1>
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180 </chapter>
181
182 <chapter id="kfifo">
183 <title>FIFO Buffer</title>
184 <sect1><title>kfifo interface</title>
185!Iinclude/linux/kfifo.h
186!Ekernel/kfifo.c
187 </sect1>
188 </chapter>
189
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190 <chapter id="relayfs">
191 <title>relay interface support</title>
192
193 <para>
194 Relay interface support
195 is designed to provide an efficient mechanism for tools and
196 facilities to relay large amounts of data from kernel space to
197 user space.
198 </para>
199
200 <sect1><title>relay interface</title>
201!Ekernel/relay.c
202!Ikernel/relay.c
203 </sect1>
204 </chapter>
205
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206 <chapter id="netcore">
207 <title>Linux Networking</title>
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208 <sect1><title>Networking Base Types</title>
209!Iinclude/linux/net.h
210 </sect1>
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211 <sect1><title>Socket Buffer Functions</title>
212!Iinclude/linux/skbuff.h
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213!Iinclude/net/sock.h
214!Enet/socket.c
1da177e4 215!Enet/core/skbuff.c
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216!Enet/core/sock.c
217!Enet/core/datagram.c
218!Enet/core/stream.c
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219 </sect1>
220 <sect1><title>Socket Filter</title>
221!Enet/core/filter.c
222 </sect1>
223 <sect1><title>Generic Network Statistics</title>
224!Iinclude/linux/gen_stats.h
225!Enet/core/gen_stats.c
226!Enet/core/gen_estimator.c
227 </sect1>
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228 <sect1><title>SUN RPC subsystem</title>
229<!-- The !D functionality is not perfect, garbage has to be protected by comments
230!Dnet/sunrpc/sunrpc_syms.c
231-->
232!Enet/sunrpc/xdr.c
233!Enet/sunrpc/svcsock.c
234!Enet/sunrpc/sched.c
235 </sect1>
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236 </chapter>
237
238 <chapter id="netdev">
239 <title>Network device support</title>
240 <sect1><title>Driver Support</title>
241!Enet/core/dev.c
c2da8aca 242!Enet/ethernet/eth.c
bea3348e 243!Enet/sched/sch_generic.c
461ddf3b 244!Iinclude/linux/etherdevice.h
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245!Iinclude/linux/netdevice.h
246 </sect1>
247 <sect1><title>PHY Support</title>
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248!Edrivers/net/phy/phy.c
249!Idrivers/net/phy/phy.c
250!Edrivers/net/phy/phy_device.c
251!Idrivers/net/phy/phy_device.c
252!Edrivers/net/phy/mdio_bus.c
253!Idrivers/net/phy/mdio_bus.c
bea3348e 254 </sect1>
461ddf3b 255<!-- FIXME: Removed for now since no structured comments in source
bea3348e 256 <sect1><title>Wireless</title>
461ddf3b 257X!Enet/core/wireless.c
1da177e4 258 </sect1>
bea3348e 259-->
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260 <sect1><title>Synchronous PPP</title>
261!Edrivers/net/wan/syncppp.c
262 </sect1>
263 </chapter>
264
265 <chapter id="modload">
266 <title>Module Support</title>
267 <sect1><title>Module Loading</title>
268!Ekernel/kmod.c
269 </sect1>
270 <sect1><title>Inter Module support</title>
271 <para>
272 Refer to the file kernel/module.c for more information.
273 </para>
274<!-- FIXME: Removed for now since no structured comments in source
275X!Ekernel/module.c
276-->
277 </sect1>
278 </chapter>
279
280 <chapter id="hardware">
281 <title>Hardware Interfaces</title>
282 <sect1><title>Interrupt Handling</title>
8f2709b5 283!Ekernel/irq/manage.c
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284 </sect1>
285
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286 <sect1><title>DMA Channels</title>
287!Ekernel/dma.c
288 </sect1>
289
4dc3b16b 290 <sect1><title>Resources Management</title>
2b54960b 291!Ikernel/resource.c
e1ca66d1 292!Ekernel/resource.c
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293 </sect1>
294
1da177e4 295 <sect1><title>MTRR Handling</title>
f3cf31ad 296!Earch/x86/kernel/cpu/mtrr/main.c
1da177e4 297 </sect1>
b0ef371e 298
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299 <sect1><title>PCI Support Library</title>
300!Edrivers/pci/pci.c
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301!Edrivers/pci/pci-driver.c
302!Edrivers/pci/remove.c
303!Edrivers/pci/pci-acpi.c
d75763d2 304!Edrivers/pci/search.c
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305!Edrivers/pci/msi.c
306!Edrivers/pci/bus.c
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307<!-- FIXME: Removed for now since no structured comments in source
308X!Edrivers/pci/hotplug.c
309-->
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310!Edrivers/pci/probe.c
311!Edrivers/pci/rom.c
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312 </sect1>
313 <sect1><title>PCI Hotplug Support Library</title>
314!Edrivers/pci/hotplug/pci_hotplug_core.c
315 </sect1>
316 <sect1><title>MCA Architecture</title>
317 <sect2><title>MCA Device Functions</title>
318 <para>
f3cf31ad 319 Refer to the file arch/x86/kernel/mca_32.c for more information.
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320 </para>
321<!-- FIXME: Removed for now since no structured comments in source
f3cf31ad 322X!Earch/x86/kernel/mca_32.c
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323-->
324 </sect2>
325 <sect2><title>MCA Bus DMA</title>
f3cf31ad 326!Iinclude/asm-x86/mca_dma.h
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327 </sect2>
328 </sect1>
329 </chapter>
330
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331 <chapter id="firmware">
332 <title>Firmware Interfaces</title>
333 <sect1><title>DMI Interfaces</title>
334!Edrivers/firmware/dmi_scan.c
335 </sect1>
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336 <sect1><title>EDD Interfaces</title>
337!Idrivers/firmware/edd.c
338 </sect1>
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339 </chapter>
340
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341 <chapter id="security">
342 <title>Security Framework</title>
20510f2f 343!Isecurity/security.c
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344 </chapter>
345
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346 <chapter id="audit">
347 <title>Audit Interfaces</title>
348!Ekernel/audit.c
349!Ikernel/auditsc.c
350!Ikernel/auditfilter.c
351 </chapter>
352
353 <chapter id="accounting">
354 <title>Accounting Framework</title>
355!Ikernel/acct.c
356 </chapter>
357
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358 <chapter id="pmfuncs">
359 <title>Power Management</title>
360!Ekernel/power/pm.c
361 </chapter>
362
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363 <chapter id="devdrivers">
364 <title>Device drivers infrastructure</title>
365 <sect1><title>Device Drivers Base</title>
366<!--
367X!Iinclude/linux/device.h
368-->
369!Edrivers/base/driver.c
4dc3b16b 370!Edrivers/base/core.c
78b2290f 371!Edrivers/base/class.c
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372!Edrivers/base/firmware_class.c
373!Edrivers/base/transport_class.c
374!Edrivers/base/dmapool.c
375<!-- Cannot be included, because
376 attribute_container_add_class_device_adapter
377 and attribute_container_classdev_to_container
378 exceed allowed 44 characters maximum
379X!Edrivers/base/attribute_container.c
380-->
381!Edrivers/base/sys.c
382<!--
383X!Edrivers/base/interface.c
384-->
385!Edrivers/base/platform.c
386!Edrivers/base/bus.c
387 </sect1>
388 <sect1><title>Device Drivers Power Management</title>
3f51bed3 389!Edrivers/base/power/main.c
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390 </sect1>
391 <sect1><title>Device Drivers ACPI Support</title>
392<!-- Internal functions only
393X!Edrivers/acpi/sleep/main.c
394X!Edrivers/acpi/sleep/wakeup.c
395X!Edrivers/acpi/motherboard.c
396X!Edrivers/acpi/bus.c
397-->
398!Edrivers/acpi/scan.c
d758a8fa 399!Idrivers/acpi/scan.c
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400<!-- No correct structured comments
401X!Edrivers/acpi/pci_bind.c
402-->
403 </sect1>
404 <sect1><title>Device drivers PnP support</title>
b8a36793 405!Idrivers/pnp/core.c
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406<!-- No correct structured comments
407X!Edrivers/pnp/system.c
408 -->
409!Edrivers/pnp/card.c
b8a36793 410!Idrivers/pnp/driver.c
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411!Edrivers/pnp/manager.c
412!Edrivers/pnp/support.c
413 </sect1>
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414 <sect1><title>Userspace IO devices</title>
415!Edrivers/uio/uio.c
416!Iinclude/linux/uio_driver.h
417 </sect1>
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418 </chapter>
419
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420 <chapter id="blkdev">
421 <title>Block Devices</title>
1d193f4f 422!Eblock/ll_rw_blk.c
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423 </chapter>
424
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425 <chapter id="chrdev">
426 <title>Char devices</title>
427!Efs/char_dev.c
428 </chapter>
429
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430 <chapter id="miscdev">
431 <title>Miscellaneous Devices</title>
432!Edrivers/char/misc.c
433 </chapter>
434
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435 <chapter id="parportdev">
436 <title>Parallel Port Devices</title>
437!Iinclude/linux/parport.h
438!Edrivers/parport/ieee1284.c
439!Edrivers/parport/share.c
440!Idrivers/parport/daisy.c
441 </chapter>
442
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443 <chapter id="message_devices">
444 <title>Message-based devices</title>
445 <sect1><title>Fusion message devices</title>
446!Edrivers/message/fusion/mptbase.c
447!Idrivers/message/fusion/mptbase.c
448!Edrivers/message/fusion/mptscsih.c
449!Idrivers/message/fusion/mptscsih.c
450!Idrivers/message/fusion/mptctl.c
451!Idrivers/message/fusion/mptspi.c
452!Idrivers/message/fusion/mptfc.c
453!Idrivers/message/fusion/mptlan.c
454 </sect1>
455 <sect1><title>I2O message devices</title>
456!Iinclude/linux/i2o.h
457!Idrivers/message/i2o/core.h
458!Edrivers/message/i2o/iop.c
459!Idrivers/message/i2o/iop.c
460!Idrivers/message/i2o/config-osm.c
461!Edrivers/message/i2o/exec-osm.c
462!Idrivers/message/i2o/exec-osm.c
463!Idrivers/message/i2o/bus-osm.c
464!Edrivers/message/i2o/device.c
465!Idrivers/message/i2o/device.c
466!Idrivers/message/i2o/driver.c
467!Idrivers/message/i2o/pci.c
468!Idrivers/message/i2o/i2o_block.c
469!Idrivers/message/i2o/i2o_scsi.c
470!Idrivers/message/i2o/i2o_proc.c
471 </sect1>
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472 </chapter>
473
474 <chapter id="snddev">
475 <title>Sound Devices</title>
4dc3b16b 476!Iinclude/sound/core.h
1da177e4 477!Esound/sound_core.c
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478!Iinclude/sound/pcm.h
479!Esound/core/pcm.c
480!Esound/core/device.c
481!Esound/core/info.c
482!Esound/core/rawmidi.c
483!Esound/core/sound.c
484!Esound/core/memory.c
485!Esound/core/pcm_memory.c
486!Esound/core/init.c
487!Esound/core/isadma.c
488!Esound/core/control.c
489!Esound/core/pcm_lib.c
490!Esound/core/hwdep.c
491!Esound/core/pcm_native.c
492!Esound/core/memalloc.c
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493<!-- FIXME: Removed for now since no structured comments in source
494X!Isound/sound_firmware.c
495-->
496 </chapter>
497
498 <chapter id="uart16x50">
499 <title>16x50 UART Driver</title>
4dc3b16b 500!Iinclude/linux/serial_core.h
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501!Edrivers/serial/serial_core.c
502!Edrivers/serial/8250.c
503 </chapter>
504
505 <chapter id="z85230">
506 <title>Z85230 Support Library</title>
507!Edrivers/net/wan/z85230.c
508 </chapter>
509
510 <chapter id="fbdev">
511 <title>Frame Buffer Library</title>
512
513 <para>
514 The frame buffer drivers depend heavily on four data structures.
515 These structures are declared in include/linux/fb.h. They are
516 fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
517 The last three can be made available to and from userland.
518 </para>
519
520 <para>
521 fb_info defines the current state of a particular video card.
522 Inside fb_info, there exists a fb_ops structure which is a
523 collection of needed functions to make fbdev and fbcon work.
524 fb_info is only visible to the kernel.
525 </para>
526
527 <para>
528 fb_var_screeninfo is used to describe the features of a video card
529 that are user defined. With fb_var_screeninfo, things such as
530 depth and the resolution may be defined.
531 </para>
532
533 <para>
534 The next structure is fb_fix_screeninfo. This defines the
535 properties of a card that are created when a mode is set and can't
536 be changed otherwise. A good example of this is the start of the
537 frame buffer memory. This "locks" the address of the frame buffer
538 memory, so that it cannot be changed or moved.
539 </para>
540
541 <para>
542 The last structure is fb_monospecs. In the old API, there was
543 little importance for fb_monospecs. This allowed for forbidden things
544 such as setting a mode of 800x600 on a fix frequency monitor. With
545 the new API, fb_monospecs prevents such things, and if used
546 correctly, can prevent a monitor from being cooked. fb_monospecs
547 will not be useful until kernels 2.5.x.
548 </para>
549
550 <sect1><title>Frame Buffer Memory</title>
551!Edrivers/video/fbmem.c
552 </sect1>
4dc3b16b 553<!--
1da177e4 554 <sect1><title>Frame Buffer Console</title>
4dc3b16b 555X!Edrivers/video/console/fbcon.c
1da177e4 556 </sect1>
4dc3b16b 557-->
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558 <sect1><title>Frame Buffer Colormap</title>
559!Edrivers/video/fbcmap.c
560 </sect1>
561<!-- FIXME:
562 drivers/video/fbgen.c has no docs, which stuffs up the sgml. Comment
563 out until somebody adds docs. KAO
564 <sect1><title>Frame Buffer Generic Functions</title>
565X!Idrivers/video/fbgen.c
566 </sect1>
567KAO -->
568 <sect1><title>Frame Buffer Video Mode Database</title>
569!Idrivers/video/modedb.c
570!Edrivers/video/modedb.c
571 </sect1>
572 <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
8f2709b5 573!Edrivers/video/macmodes.c
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574 </sect1>
575 <sect1><title>Frame Buffer Fonts</title>
576 <para>
577 Refer to the file drivers/video/console/fonts.c for more information.
578 </para>
579<!-- FIXME: Removed for now since no structured comments in source
580X!Idrivers/video/console/fonts.c
581-->
582 </sect1>
583 </chapter>
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584
585 <chapter id="input_subsystem">
586 <title>Input Subsystem</title>
587!Iinclude/linux/input.h
588!Edrivers/input/input.c
589!Edrivers/input/ff-core.c
590!Edrivers/input/ff-memless.c
591 </chapter>
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592
593 <chapter id="spi">
594 <title>Serial Peripheral Interface (SPI)</title>
595 <para>
596 SPI is the "Serial Peripheral Interface", widely used with
597 embedded systems because it is a simple and efficient
598 interface: basically a multiplexed shift register.
599 Its three signal wires hold a clock (SCK, often in the range
600 of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
601 a "Master In, Slave Out" (MISO) data line.
602 SPI is a full duplex protocol; for each bit shifted out the
603 MOSI line (one per clock) another is shifted in on the MISO line.
604 Those bits are assembled into words of various sizes on the
605 way to and from system memory.
606 An additional chipselect line is usually active-low (nCS);
607 four signals are normally used for each peripheral, plus
608 sometimes an interrupt.
609 </para>
610 <para>
611 The SPI bus facilities listed here provide a generalized
612 interface to declare SPI busses and devices, manage them
613 according to the standard Linux driver model, and perform
614 input/output operations.
615 At this time, only "master" side interfaces are supported,
616 where Linux talks to SPI peripherals and does not implement
617 such a peripheral itself.
618 (Interfaces to support implementing SPI slaves would
619 necessarily look different.)
620 </para>
621 <para>
622 The programming interface is structured around two kinds of driver,
623 and two kinds of device.
624 A "Controller Driver" abstracts the controller hardware, which may
625 be as simple as a set of GPIO pins or as complex as a pair of FIFOs
626 connected to dual DMA engines on the other side of the SPI shift
627 register (maximizing throughput). Such drivers bridge between
628 whatever bus they sit on (often the platform bus) and SPI, and
629 expose the SPI side of their device as a
630 <structname>struct spi_master</structname>.
631 SPI devices are children of that master, represented as a
632 <structname>struct spi_device</structname> and manufactured from
633 <structname>struct spi_board_info</structname> descriptors which
634 are usually provided by board-specific initialization code.
635 A <structname>struct spi_driver</structname> is called a
636 "Protocol Driver", and is bound to a spi_device using normal
637 driver model calls.
638 </para>
639 <para>
640 The I/O model is a set of queued messages. Protocol drivers
641 submit one or more <structname>struct spi_message</structname>
642 objects, which are processed and completed asynchronously.
643 (There are synchronous wrappers, however.) Messages are
644 built from one or more <structname>struct spi_transfer</structname>
645 objects, each of which wraps a full duplex SPI transfer.
646 A variety of protocol tweaking options are needed, because
647 different chips adopt very different policies for how they
648 use the bits transferred with SPI.
649 </para>
650!Iinclude/linux/spi/spi.h
651!Fdrivers/spi/spi.c spi_register_board_info
652!Edrivers/spi/spi.c
653 </chapter>
654
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655 <chapter id="i2c">
656 <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
657
658 <para>
659 I<superscript>2</superscript>C (or without fancy typography, "I2C")
660 is an acronym for the "Inter-IC" bus, a simple bus protocol which is
661 widely used where low data rate communications suffice.
662 Since it's also a licensed trademark, some vendors use another
663 name (such as "Two-Wire Interface", TWI) for the same bus.
664 I2C only needs two signals (SCL for clock, SDA for data), conserving
665 board real estate and minimizing signal quality issues.
666 Most I2C devices use seven bit addresses, and bus speeds of up
667 to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
668 found wide use.
669 I2C is a multi-master bus; open drain signaling is used to
670 arbitrate between masters, as well as to handshake and to
671 synchronize clocks from slower clients.
672 </para>
673
674 <para>
675 The Linux I2C programming interfaces support only the master
676 side of bus interactions, not the slave side.
677 The programming interface is structured around two kinds of driver,
678 and two kinds of device.
679 An I2C "Adapter Driver" abstracts the controller hardware; it binds
680 to a physical device (perhaps a PCI device or platform_device) and
681 exposes a <structname>struct i2c_adapter</structname> representing
682 each I2C bus segment it manages.
683 On each I2C bus segment will be I2C devices represented by a
684 <structname>struct i2c_client</structname>. Those devices will
685 be bound to a <structname>struct i2c_driver</structname>,
686 which should follow the standard Linux driver model.
687 (At this writing, a legacy model is more widely used.)
688 There are functions to perform various I2C protocol operations; at
689 this writing all such functions are usable only from task context.
690 </para>
691
692 <para>
693 The System Management Bus (SMBus) is a sibling protocol. Most SMBus
694 systems are also I2C conformant. The electrical constraints are
695 tighter for SMBus, and it standardizes particular protocol messages
696 and idioms. Controllers that support I2C can also support most
697 SMBus operations, but SMBus controllers don't support all the protocol
698 options that an I2C controller will.
699 There are functions to perform various SMBus protocol operations,
700 either using I2C primitives or by issuing SMBus commands to
701 i2c_adapter devices which don't support those I2C operations.
702 </para>
703
704!Iinclude/linux/i2c.h
705!Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
706!Edrivers/i2c/i2c-core.c
707 </chapter>
708
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709 <chapter id="splice">
710 <title>splice API</title>
79685b8d 711 <para>
932cc6d4 712 splice is a method for moving blocks of data around inside the
79685b8d 713 kernel, without continually transferring them between the kernel
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714 and user space.
715 </para>
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716!Ffs/splice.c
717 </chapter>
718
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719 <chapter id="pipes">
720 <title>pipes API</title>
721 <para>
722 Pipe interfaces are all for in-kernel (builtin image) use.
723 They are not exported for use by modules.
724 </para>
725!Iinclude/linux/pipe_fs_i.h
726!Ffs/pipe.c
727 </chapter>
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1da177e4 729</book>