Documentation/DocBook/kernel-api.tmpl

   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>
  48 !Iinclude/asm-x86/atomic_32.h
  49 !Iinclude/asm-x86/unaligned.h
  50      </sect1>
  51
  52      <sect1><title>Delaying, scheduling, and timer routines</title>
  53 !Iinclude/linux/sched.h
  54 !Ekernel/sched.c
  55 !Ekernel/timer.c
  56      </sect1>
  57      <sect1><title>High-resolution timers</title>
  58 !Iinclude/linux/ktime.h
  59 !Iinclude/linux/hrtimer.h
  60 !Ekernel/hrtimer.c
  61      </sect1>
  62      <sect1><title>Workqueues and Kevents</title>
  63 !Ekernel/workqueue.c
  64      </sect1>
  65      <sect1><title>Internal Functions</title>
  66 !Ikernel/exit.c
  67 !Ikernel/signal.c
  68 !Iinclude/linux/kthread.h
  69 !Ekernel/kthread.c
  70      </sect1>
  71
  72      <sect1><title>Kernel objects manipulation</title>
  73 <!--
  74 X!Iinclude/linux/kobject.h
  75 -->
  76 !Elib/kobject.c
  77      </sect1>
  78
  79      <sect1><title>Kernel utility functions</title>
  80 !Iinclude/linux/kernel.h
  81 !Ekernel/printk.c
  82 !Ekernel/panic.c
  83 !Ekernel/sys.c
  84 !Ekernel/rcupdate.c
  85      </sect1>
  86
  87      <sect1><title>Device Resource Management</title>
  88 !Edrivers/base/devres.c
  89      </sect1>
  90
  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>
 116 <!-- All functions are exported at now
 117 X!Ilib/string.c
 118  -->
 119 !Elib/string.c
 120      </sect1>
 121      <sect1><title>Bit Operations</title>
 122 !Iinclude/asm-x86/bitops_32.h
 123      </sect1>
 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
 133      <sect1><title>Bitmap Operations</title>
 134 !Elib/bitmap.c
 135 !Ilib/bitmap.c
 136      </sect1>
 137
 138      <sect1><title>Command-line Parsing</title>
 139 !Elib/cmdline.c
 140      </sect1>
 141
 142      <sect1 id="crc"><title>CRC Functions</title>
 143 !Elib/crc7.c
 144 !Elib/crc16.c
 145 !Elib/crc-itu-t.c
 146 !Elib/crc32.c
 147 !Elib/crc-ccitt.c
 148      </sect1>
 149   </chapter>
 150
 151   <chapter id="mm">
 152      <title>Memory Management in Linux</title>
 153      <sect1><title>The Slab Cache</title>
 154 !Iinclude/linux/slab.h
 155 !Emm/slab.c
 156      </sect1>
 157      <sect1><title>User Space Memory Access</title>
 158 !Iinclude/asm-x86/uaccess_32.h
 159 !Earch/x86/lib/usercopy_32.c
 160      </sect1>
 161      <sect1><title>More Memory Management Functions</title>
 162 !Emm/readahead.c
 163 !Emm/filemap.c
 164 !Emm/memory.c
 165 !Emm/vmalloc.c
 166 !Imm/page_alloc.c
 167 !Emm/mempool.c
 168 !Emm/dmapool.c
 169 !Emm/page-writeback.c
 170 !Emm/truncate.c
 171      </sect1>
 172   </chapter>
 173
 174
 175   <chapter id="ipc">
 176      <title>Kernel IPC facilities</title>
 177
 178      <sect1><title>IPC utilities</title>
 179 !Iipc/util.c
 180      </sect1>
 181   </chapter>
 182
 183   <chapter id="kfifo">
 184      <title>FIFO Buffer</title>
 185      <sect1><title>kfifo interface</title>
 186 !Iinclude/linux/kfifo.h
 187 !Ekernel/kfifo.c
 188      </sect1>
 189   </chapter>
 190
 191   <chapter id="relayfs">
 192      <title>relay interface support</title>
 193
 194      <para>
 195         Relay interface support
 196         is designed to provide an efficient mechanism for tools and
 197         facilities to relay large amounts of data from kernel space to
 198         user space.
 199      </para>
 200
 201      <sect1><title>relay interface</title>
 202 !Ekernel/relay.c
 203 !Ikernel/relay.c
 204      </sect1>
 205   </chapter>
 206
 207   <chapter id="modload">
 208      <title>Module Support</title>
 209      <sect1><title>Module Loading</title>
 210 !Ekernel/kmod.c
 211      </sect1>
 212      <sect1><title>Inter Module support</title>
 213         <para>
 214            Refer to the file kernel/module.c for more information.
 215         </para>
 216 <!-- FIXME: Removed for now since no structured comments in source
 217 X!Ekernel/module.c
 218 -->
 219      </sect1>
 220   </chapter>
 221
 222   <chapter id="hardware">
 223      <title>Hardware Interfaces</title>
 224      <sect1><title>Interrupt Handling</title>
 225 !Ekernel/irq/manage.c
 226      </sect1>
 227
 228      <sect1><title>DMA Channels</title>
 229 !Ekernel/dma.c
 230      </sect1>
 231
 232      <sect1><title>Resources Management</title>
 233 !Ikernel/resource.c
 234 !Ekernel/resource.c
 235      </sect1>
 236
 237      <sect1><title>MTRR Handling</title>
 238 !Earch/x86/kernel/cpu/mtrr/main.c
 239      </sect1>
 240
 241      <sect1><title>PCI Support Library</title>
 242 !Edrivers/pci/pci.c
 243 !Edrivers/pci/pci-driver.c
 244 !Edrivers/pci/remove.c
 245 !Edrivers/pci/pci-acpi.c
 246 !Edrivers/pci/search.c
 247 !Edrivers/pci/msi.c
 248 !Edrivers/pci/bus.c
 249 <!-- FIXME: Removed for now since no structured comments in source
 250 X!Edrivers/pci/hotplug.c
 251 -->
 252 !Edrivers/pci/probe.c
 253 !Edrivers/pci/rom.c
 254      </sect1>
 255      <sect1><title>PCI Hotplug Support Library</title>
 256 !Edrivers/pci/hotplug/pci_hotplug_core.c
 257      </sect1>
 258      <sect1><title>MCA Architecture</title>
 259         <sect2><title>MCA Device Functions</title>
 260            <para>
 261               Refer to the file arch/x86/kernel/mca_32.c for more information.
 262            </para>
 263 <!-- FIXME: Removed for now since no structured comments in source
 264 X!Earch/x86/kernel/mca_32.c
 265 -->
 266         </sect2>
 267         <sect2><title>MCA Bus DMA</title>
 268 !Iinclude/asm-x86/mca_dma.h
 269         </sect2>
 270      </sect1>
 271   </chapter>
 272
 273   <chapter id="firmware">
 274      <title>Firmware Interfaces</title>
 275      <sect1><title>DMI Interfaces</title>
 276 !Edrivers/firmware/dmi_scan.c
 277      </sect1>
 278      <sect1><title>EDD Interfaces</title>
 279 !Idrivers/firmware/edd.c
 280      </sect1>
 281   </chapter>
 282
 283   <chapter id="security">
 284      <title>Security Framework</title>
 285 !Isecurity/security.c
 286   </chapter>
 287
 288   <chapter id="audit">
 289      <title>Audit Interfaces</title>
 290 !Ekernel/audit.c
 291 !Ikernel/auditsc.c
 292 !Ikernel/auditfilter.c
 293   </chapter>
 294
 295   <chapter id="accounting">
 296      <title>Accounting Framework</title>
 297 !Ikernel/acct.c
 298   </chapter>
 299
 300   <chapter id="pmfuncs">
 301      <title>Power Management</title>
 302 !Ekernel/power/pm.c
 303   </chapter>
 304
 305   <chapter id="devdrivers">
 306      <title>Device drivers infrastructure</title>
 307      <sect1><title>Device Drivers Base</title>
 308 <!--
 309 X!Iinclude/linux/device.h
 310 -->
 311 !Edrivers/base/driver.c
 312 !Edrivers/base/core.c
 313 !Edrivers/base/class.c
 314 !Edrivers/base/firmware_class.c
 315 !Edrivers/base/transport_class.c
 316 <!-- Cannot be included, because
 317      attribute_container_add_class_device_adapter
 318  and attribute_container_classdev_to_container
 319      exceed allowed 44 characters maximum
 320 X!Edrivers/base/attribute_container.c
 321 -->
 322 !Edrivers/base/sys.c
 323 <!--
 324 X!Edrivers/base/interface.c
 325 -->
 326 !Edrivers/base/platform.c
 327 !Edrivers/base/bus.c
 328      </sect1>
 329      <sect1><title>Device Drivers Power Management</title>
 330 !Edrivers/base/power/main.c
 331      </sect1>
 332      <sect1><title>Device Drivers ACPI Support</title>
 333 <!-- Internal functions only
 334 X!Edrivers/acpi/sleep/main.c
 335 X!Edrivers/acpi/sleep/wakeup.c
 336 X!Edrivers/acpi/motherboard.c
 337 X!Edrivers/acpi/bus.c
 338 -->
 339 !Edrivers/acpi/scan.c
 340 !Idrivers/acpi/scan.c
 341 <!-- No correct structured comments
 342 X!Edrivers/acpi/pci_bind.c
 343 -->
 344      </sect1>
 345      <sect1><title>Device drivers PnP support</title>
 346 !Idrivers/pnp/core.c
 347 <!-- No correct structured comments
 348 X!Edrivers/pnp/system.c
 349  -->
 350 !Edrivers/pnp/card.c
 351 !Idrivers/pnp/driver.c
 352 !Edrivers/pnp/manager.c
 353 !Edrivers/pnp/support.c
 354      </sect1>
 355      <sect1><title>Userspace IO devices</title>
 356 !Edrivers/uio/uio.c
 357 !Iinclude/linux/uio_driver.h
 358      </sect1>
 359   </chapter>
 360
 361   <chapter id="blkdev">
 362      <title>Block Devices</title>
 363 !Eblock/blk-core.c
 364 <<<<<<< HEAD:Documentation/DocBook/kernel-api.tmpl
 365 =======
 366 !Iblock/blk-core.c
 367 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:Documentation/DocBook/kernel-api.tmpl
 368 !Eblock/blk-map.c
 369 !Iblock/blk-sysfs.c
 370 !Eblock/blk-settings.c
 371 !Eblock/blk-exec.c
 372 !Eblock/blk-barrier.c
 373 !Eblock/blk-tag.c
 374 <<<<<<< HEAD:Documentation/DocBook/kernel-api.tmpl
 375 =======
 376 !Iblock/blk-tag.c
 377 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:Documentation/DocBook/kernel-api.tmpl
 378   </chapter>
 379
 380   <chapter id="chrdev">
 381         <title>Char devices</title>
 382 !Efs/char_dev.c
 383   </chapter>
 384
 385   <chapter id="miscdev">
 386      <title>Miscellaneous Devices</title>
 387 !Edrivers/char/misc.c
 388   </chapter>
 389
 390   <chapter id="parportdev">
 391      <title>Parallel Port Devices</title>
 392 !Iinclude/linux/parport.h
 393 !Edrivers/parport/ieee1284.c
 394 !Edrivers/parport/share.c
 395 !Idrivers/parport/daisy.c
 396   </chapter>
 397
 398   <chapter id="message_devices">
 399         <title>Message-based devices</title>
 400      <sect1><title>Fusion message devices</title>
 401 !Edrivers/message/fusion/mptbase.c
 402 !Idrivers/message/fusion/mptbase.c
 403 !Edrivers/message/fusion/mptscsih.c
 404 !Idrivers/message/fusion/mptscsih.c
 405 !Idrivers/message/fusion/mptctl.c
 406 !Idrivers/message/fusion/mptspi.c
 407 !Idrivers/message/fusion/mptfc.c
 408 !Idrivers/message/fusion/mptlan.c
 409      </sect1>
 410      <sect1><title>I2O message devices</title>
 411 !Iinclude/linux/i2o.h
 412 !Idrivers/message/i2o/core.h
 413 !Edrivers/message/i2o/iop.c
 414 !Idrivers/message/i2o/iop.c
 415 !Idrivers/message/i2o/config-osm.c
 416 !Edrivers/message/i2o/exec-osm.c
 417 !Idrivers/message/i2o/exec-osm.c
 418 !Idrivers/message/i2o/bus-osm.c
 419 !Edrivers/message/i2o/device.c
 420 !Idrivers/message/i2o/device.c
 421 !Idrivers/message/i2o/driver.c
 422 !Idrivers/message/i2o/pci.c
 423 !Idrivers/message/i2o/i2o_block.c
 424 !Idrivers/message/i2o/i2o_scsi.c
 425 !Idrivers/message/i2o/i2o_proc.c
 426      </sect1>
 427   </chapter>
 428
 429   <chapter id="snddev">
 430      <title>Sound Devices</title>
 431 !Iinclude/sound/core.h
 432 !Esound/sound_core.c
 433 !Iinclude/sound/pcm.h
 434 !Esound/core/pcm.c
 435 !Esound/core/device.c
 436 !Esound/core/info.c
 437 !Esound/core/rawmidi.c
 438 !Esound/core/sound.c
 439 !Esound/core/memory.c
 440 !Esound/core/pcm_memory.c
 441 !Esound/core/init.c
 442 !Esound/core/isadma.c
 443 !Esound/core/control.c
 444 !Esound/core/pcm_lib.c
 445 !Esound/core/hwdep.c
 446 !Esound/core/pcm_native.c
 447 !Esound/core/memalloc.c
 448 <!-- FIXME: Removed for now since no structured comments in source
 449 X!Isound/sound_firmware.c
 450 -->
 451   </chapter>
 452
 453   <chapter id="uart16x50">
 454      <title>16x50 UART Driver</title>
 455 !Iinclude/linux/serial_core.h
 456 !Edrivers/serial/serial_core.c
 457 !Edrivers/serial/8250.c
 458   </chapter>
 459
 460   <chapter id="fbdev">
 461      <title>Frame Buffer Library</title>
 462
 463      <para>
 464        The frame buffer drivers depend heavily on four data structures.
 465        These structures are declared in include/linux/fb.h.  They are
 466        fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
 467        The last three can be made available to and from userland.
 468      </para>
 469
 470      <para>
 471        fb_info defines the current state of a particular video card.
 472        Inside fb_info, there exists a fb_ops structure which is a
 473        collection of needed functions to make fbdev and fbcon work.
 474        fb_info is only visible to the kernel.
 475      </para>
 476
 477      <para>
 478        fb_var_screeninfo is used to describe the features of a video card
 479        that are user defined.  With fb_var_screeninfo, things such as
 480        depth and the resolution may be defined.
 481      </para>
 482
 483      <para>
 484        The next structure is fb_fix_screeninfo. This defines the
 485        properties of a card that are created when a mode is set and can't
 486        be changed otherwise.  A good example of this is the start of the
 487        frame buffer memory.  This "locks" the address of the frame buffer
 488        memory, so that it cannot be changed or moved.
 489      </para>
 490
 491      <para>
 492        The last structure is fb_monospecs. In the old API, there was
 493        little importance for fb_monospecs. This allowed for forbidden things
 494        such as setting a mode of 800x600 on a fix frequency monitor. With
 495        the new API, fb_monospecs prevents such things, and if used
 496        correctly, can prevent a monitor from being cooked.  fb_monospecs
 497        will not be useful until kernels 2.5.x.
 498      </para>
 499
 500      <sect1><title>Frame Buffer Memory</title>
 501 !Edrivers/video/fbmem.c
 502      </sect1>
 503 <!--
 504      <sect1><title>Frame Buffer Console</title>
 505 X!Edrivers/video/console/fbcon.c
 506      </sect1>
 507 -->
 508      <sect1><title>Frame Buffer Colormap</title>
 509 !Edrivers/video/fbcmap.c
 510      </sect1>
 511 <!-- FIXME:
 512   drivers/video/fbgen.c has no docs, which stuffs up the sgml.  Comment
 513   out until somebody adds docs.  KAO
 514      <sect1><title>Frame Buffer Generic Functions</title>
 515 X!Idrivers/video/fbgen.c
 516      </sect1>
 517 KAO -->
 518      <sect1><title>Frame Buffer Video Mode Database</title>
 519 !Idrivers/video/modedb.c
 520 !Edrivers/video/modedb.c
 521      </sect1>
 522      <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
 523 !Edrivers/video/macmodes.c
 524      </sect1>
 525      <sect1><title>Frame Buffer Fonts</title>
 526         <para>
 527            Refer to the file drivers/video/console/fonts.c for more information.
 528         </para>
 529 <!-- FIXME: Removed for now since no structured comments in source
 530 X!Idrivers/video/console/fonts.c
 531 -->
 532      </sect1>
 533   </chapter>
 534
 535   <chapter id="input_subsystem">
 536      <title>Input Subsystem</title>
 537 !Iinclude/linux/input.h
 538 !Edrivers/input/input.c
 539 !Edrivers/input/ff-core.c
 540 !Edrivers/input/ff-memless.c
 541   </chapter>
 542
 543   <chapter id="spi">
 544       <title>Serial Peripheral Interface (SPI)</title>
 545   <para>
 546         SPI is the "Serial Peripheral Interface", widely used with
 547         embedded systems because it is a simple and efficient
 548         interface:  basically a multiplexed shift register.
 549         Its three signal wires hold a clock (SCK, often in the range
 550         of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
 551         a "Master In, Slave Out" (MISO) data line.
 552         SPI is a full duplex protocol; for each bit shifted out the
 553         MOSI line (one per clock) another is shifted in on the MISO line.
 554         Those bits are assembled into words of various sizes on the
 555         way to and from system memory.
 556         An additional chipselect line is usually active-low (nCS);
 557         four signals are normally used for each peripheral, plus
 558         sometimes an interrupt.
 559   </para>
 560   <para>
 561         The SPI bus facilities listed here provide a generalized
 562         interface to declare SPI busses and devices, manage them
 563         according to the standard Linux driver model, and perform
 564         input/output operations.
 565         At this time, only "master" side interfaces are supported,
 566         where Linux talks to SPI peripherals and does not implement
 567         such a peripheral itself.
 568         (Interfaces to support implementing SPI slaves would
 569         necessarily look different.)
 570   </para>
 571   <para>
 572         The programming interface is structured around two kinds of driver,
 573         and two kinds of device.
 574         A "Controller Driver" abstracts the controller hardware, which may
 575         be as simple as a set of GPIO pins or as complex as a pair of FIFOs
 576         connected to dual DMA engines on the other side of the SPI shift
 577         register (maximizing throughput).  Such drivers bridge between
 578         whatever bus they sit on (often the platform bus) and SPI, and
 579         expose the SPI side of their device as a
 580         <structname>struct spi_master</structname>.
 581         SPI devices are children of that master, represented as a
 582         <structname>struct spi_device</structname> and manufactured from
 583         <structname>struct spi_board_info</structname> descriptors which
 584         are usually provided by board-specific initialization code.
 585         A <structname>struct spi_driver</structname> is called a
 586         "Protocol Driver", and is bound to a spi_device using normal
 587         driver model calls.
 588   </para>
 589   <para>
 590         The I/O model is a set of queued messages.  Protocol drivers
 591         submit one or more <structname>struct spi_message</structname>
 592         objects, which are processed and completed asynchronously.
 593         (There are synchronous wrappers, however.)  Messages are
 594         built from one or more <structname>struct spi_transfer</structname>
 595         objects, each of which wraps a full duplex SPI transfer.
 596         A variety of protocol tweaking options are needed, because
 597         different chips adopt very different policies for how they
 598         use the bits transferred with SPI.
 599   </para>
 600 !Iinclude/linux/spi/spi.h
 601 !Fdrivers/spi/spi.c spi_register_board_info
 602 !Edrivers/spi/spi.c
 603   </chapter>
 604
 605   <chapter id="i2c">
 606      <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
 607
 608      <para>
 609         I<superscript>2</superscript>C (or without fancy typography, "I2C")
 610         is an acronym for the "Inter-IC" bus, a simple bus protocol which is
 611         widely used where low data rate communications suffice.
 612         Since it's also a licensed trademark, some vendors use another
 613         name (such as "Two-Wire Interface", TWI) for the same bus.
 614         I2C only needs two signals (SCL for clock, SDA for data), conserving
 615         board real estate and minimizing signal quality issues.
 616         Most I2C devices use seven bit addresses, and bus speeds of up
 617         to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
 618         found wide use.
 619         I2C is a multi-master bus; open drain signaling is used to
 620         arbitrate between masters, as well as to handshake and to
 621         synchronize clocks from slower clients.
 622      </para>
 623
 624      <para>
 625         The Linux I2C programming interfaces support only the master
 626         side of bus interactions, not the slave side.
 627         The programming interface is structured around two kinds of driver,
 628         and two kinds of device.
 629         An I2C "Adapter Driver" abstracts the controller hardware; it binds
 630         to a physical device (perhaps a PCI device or platform_device) and
 631         exposes a <structname>struct i2c_adapter</structname> representing
 632         each I2C bus segment it manages.
 633         On each I2C bus segment will be I2C devices represented by a
 634         <structname>struct i2c_client</structname>.  Those devices will
 635         be bound to a <structname>struct i2c_driver</structname>,
 636         which should follow the standard Linux driver model.
 637         (At this writing, a legacy model is more widely used.)
 638         There are functions to perform various I2C protocol operations; at
 639         this writing all such functions are usable only from task context.
 640      </para>
 641
 642      <para>
 643         The System Management Bus (SMBus) is a sibling protocol.  Most SMBus
 644         systems are also I2C conformant.  The electrical constraints are
 645         tighter for SMBus, and it standardizes particular protocol messages
 646         and idioms.  Controllers that support I2C can also support most
 647         SMBus operations, but SMBus controllers don't support all the protocol
 648         options that an I2C controller will.
 649         There are functions to perform various SMBus protocol operations,
 650         either using I2C primitives or by issuing SMBus commands to
 651         i2c_adapter devices which don't support those I2C operations.
 652      </para>
 653
 654 !Iinclude/linux/i2c.h
 655 !Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
 656 !Edrivers/i2c/i2c-core.c
 657   </chapter>
 658
 659 </book>