Documentation/DocBook/device-drivers.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="LinuxDriversAPI">
   6  <bookinfo>
   7   <title>Linux Device Drivers</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 !Iarch/x86/include/asm/atomic_32.h
  49 !Iarch/x86/include/asm/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="devdrivers">
  94      <title>Device drivers infrastructure</title>
  95      <sect1><title>Device Drivers Base</title>
  96 <!--
  97 X!Iinclude/linux/device.h
  98 -->
  99 !Edrivers/base/driver.c
 100 !Edrivers/base/core.c
 101 !Edrivers/base/class.c
 102 !Edrivers/base/firmware_class.c
 103 !Edrivers/base/transport_class.c
 104 <!-- Cannot be included, because
 105      attribute_container_add_class_device_adapter
 106  and attribute_container_classdev_to_container
 107      exceed allowed 44 characters maximum
 108 X!Edrivers/base/attribute_container.c
 109 -->
 110 !Edrivers/base/sys.c
 111 <!--
 112 X!Edrivers/base/interface.c
 113 -->
 114 !Edrivers/base/platform.c
 115 !Edrivers/base/bus.c
 116      </sect1>
 117      <sect1><title>Device Drivers Power Management</title>
 118 !Edrivers/base/power/main.c
 119      </sect1>
 120      <sect1><title>Device Drivers ACPI Support</title>
 121 <!-- Internal functions only
 122 X!Edrivers/acpi/sleep/main.c
 123 X!Edrivers/acpi/sleep/wakeup.c
 124 X!Edrivers/acpi/motherboard.c
 125 X!Edrivers/acpi/bus.c
 126 -->
 127 !Edrivers/acpi/scan.c
 128 !Idrivers/acpi/scan.c
 129 <!-- No correct structured comments
 130 X!Edrivers/acpi/pci_bind.c
 131 -->
 132      </sect1>
 133      <sect1><title>Device drivers PnP support</title>
 134 !Idrivers/pnp/core.c
 135 <!-- No correct structured comments
 136 X!Edrivers/pnp/system.c
 137  -->
 138 !Edrivers/pnp/card.c
 139 !Idrivers/pnp/driver.c
 140 !Edrivers/pnp/manager.c
 141 !Edrivers/pnp/support.c
 142      </sect1>
 143      <sect1><title>Userspace IO devices</title>
 144 !Edrivers/uio/uio.c
 145 !Iinclude/linux/uio_driver.h
 146      </sect1>
 147   </chapter>
 148
 149   <chapter id="parportdev">
 150      <title>Parallel Port Devices</title>
 151 !Iinclude/linux/parport.h
 152 !Edrivers/parport/ieee1284.c
 153 !Edrivers/parport/share.c
 154 !Idrivers/parport/daisy.c
 155   </chapter>
 156
 157   <chapter id="message_devices">
 158         <title>Message-based devices</title>
 159      <sect1><title>Fusion message devices</title>
 160 !Edrivers/message/fusion/mptbase.c
 161 !Idrivers/message/fusion/mptbase.c
 162 !Edrivers/message/fusion/mptscsih.c
 163 !Idrivers/message/fusion/mptscsih.c
 164 !Idrivers/message/fusion/mptctl.c
 165 !Idrivers/message/fusion/mptspi.c
 166 !Idrivers/message/fusion/mptfc.c
 167 !Idrivers/message/fusion/mptlan.c
 168      </sect1>
 169      <sect1><title>I2O message devices</title>
 170 !Iinclude/linux/i2o.h
 171 !Idrivers/message/i2o/core.h
 172 !Edrivers/message/i2o/iop.c
 173 !Idrivers/message/i2o/iop.c
 174 !Idrivers/message/i2o/config-osm.c
 175 !Edrivers/message/i2o/exec-osm.c
 176 !Idrivers/message/i2o/exec-osm.c
 177 !Idrivers/message/i2o/bus-osm.c
 178 !Edrivers/message/i2o/device.c
 179 !Idrivers/message/i2o/device.c
 180 !Idrivers/message/i2o/driver.c
 181 !Idrivers/message/i2o/pci.c
 182 !Idrivers/message/i2o/i2o_block.c
 183 !Idrivers/message/i2o/i2o_scsi.c
 184 !Idrivers/message/i2o/i2o_proc.c
 185      </sect1>
 186   </chapter>
 187
 188   <chapter id="snddev">
 189      <title>Sound Devices</title>
 190 !Iinclude/sound/core.h
 191 !Esound/sound_core.c
 192 !Iinclude/sound/pcm.h
 193 !Esound/core/pcm.c
 194 !Esound/core/device.c
 195 !Esound/core/info.c
 196 !Esound/core/rawmidi.c
 197 !Esound/core/sound.c
 198 !Esound/core/memory.c
 199 !Esound/core/pcm_memory.c
 200 !Esound/core/init.c
 201 !Esound/core/isadma.c
 202 !Esound/core/control.c
 203 !Esound/core/pcm_lib.c
 204 !Esound/core/hwdep.c
 205 !Esound/core/pcm_native.c
 206 !Esound/core/memalloc.c
 207 <!-- FIXME: Removed for now since no structured comments in source
 208 X!Isound/sound_firmware.c
 209 -->
 210   </chapter>
 211
 212   <chapter id="uart16x50">
 213      <title>16x50 UART Driver</title>
 214 !Iinclude/linux/serial_core.h
 215 !Edrivers/serial/serial_core.c
 216 !Edrivers/serial/8250.c
 217   </chapter>
 218
 219   <chapter id="fbdev">
 220      <title>Frame Buffer Library</title>
 221
 222      <para>
 223        The frame buffer drivers depend heavily on four data structures.
 224        These structures are declared in include/linux/fb.h.  They are
 225        fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
 226        The last three can be made available to and from userland.
 227      </para>
 228
 229      <para>
 230        fb_info defines the current state of a particular video card.
 231        Inside fb_info, there exists a fb_ops structure which is a
 232        collection of needed functions to make fbdev and fbcon work.
 233        fb_info is only visible to the kernel.
 234      </para>
 235
 236      <para>
 237        fb_var_screeninfo is used to describe the features of a video card
 238        that are user defined.  With fb_var_screeninfo, things such as
 239        depth and the resolution may be defined.
 240      </para>
 241
 242      <para>
 243        The next structure is fb_fix_screeninfo. This defines the
 244        properties of a card that are created when a mode is set and can't
 245        be changed otherwise.  A good example of this is the start of the
 246        frame buffer memory.  This "locks" the address of the frame buffer
 247        memory, so that it cannot be changed or moved.
 248      </para>
 249
 250      <para>
 251        The last structure is fb_monospecs. In the old API, there was
 252        little importance for fb_monospecs. This allowed for forbidden things
 253        such as setting a mode of 800x600 on a fix frequency monitor. With
 254        the new API, fb_monospecs prevents such things, and if used
 255        correctly, can prevent a monitor from being cooked.  fb_monospecs
 256        will not be useful until kernels 2.5.x.
 257      </para>
 258
 259      <sect1><title>Frame Buffer Memory</title>
 260 !Edrivers/video/fbmem.c
 261      </sect1>
 262 <!--
 263      <sect1><title>Frame Buffer Console</title>
 264 X!Edrivers/video/console/fbcon.c
 265      </sect1>
 266 -->
 267      <sect1><title>Frame Buffer Colormap</title>
 268 !Edrivers/video/fbcmap.c
 269      </sect1>
 270 <!-- FIXME:
 271   drivers/video/fbgen.c has no docs, which stuffs up the sgml.  Comment
 272   out until somebody adds docs.  KAO
 273      <sect1><title>Frame Buffer Generic Functions</title>
 274 X!Idrivers/video/fbgen.c
 275      </sect1>
 276 KAO -->
 277      <sect1><title>Frame Buffer Video Mode Database</title>
 278 !Idrivers/video/modedb.c
 279 !Edrivers/video/modedb.c
 280      </sect1>
 281      <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
 282 !Edrivers/video/macmodes.c
 283      </sect1>
 284      <sect1><title>Frame Buffer Fonts</title>
 285         <para>
 286            Refer to the file drivers/video/console/fonts.c for more information.
 287         </para>
 288 <!-- FIXME: Removed for now since no structured comments in source
 289 X!Idrivers/video/console/fonts.c
 290 -->
 291      </sect1>
 292   </chapter>
 293
 294   <chapter id="input_subsystem">
 295      <title>Input Subsystem</title>
 296 !Iinclude/linux/input.h
 297 !Edrivers/input/input.c
 298 !Edrivers/input/ff-core.c
 299 !Edrivers/input/ff-memless.c
 300   </chapter>
 301
 302   <chapter id="spi">
 303       <title>Serial Peripheral Interface (SPI)</title>
 304   <para>
 305         SPI is the "Serial Peripheral Interface", widely used with
 306         embedded systems because it is a simple and efficient
 307         interface:  basically a multiplexed shift register.
 308         Its three signal wires hold a clock (SCK, often in the range
 309         of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
 310         a "Master In, Slave Out" (MISO) data line.
 311         SPI is a full duplex protocol; for each bit shifted out the
 312         MOSI line (one per clock) another is shifted in on the MISO line.
 313         Those bits are assembled into words of various sizes on the
 314         way to and from system memory.
 315         An additional chipselect line is usually active-low (nCS);
 316         four signals are normally used for each peripheral, plus
 317         sometimes an interrupt.
 318   </para>
 319   <para>
 320         The SPI bus facilities listed here provide a generalized
 321         interface to declare SPI busses and devices, manage them
 322         according to the standard Linux driver model, and perform
 323         input/output operations.
 324         At this time, only "master" side interfaces are supported,
 325         where Linux talks to SPI peripherals and does not implement
 326         such a peripheral itself.
 327         (Interfaces to support implementing SPI slaves would
 328         necessarily look different.)
 329   </para>
 330   <para>
 331         The programming interface is structured around two kinds of driver,
 332         and two kinds of device.
 333         A "Controller Driver" abstracts the controller hardware, which may
 334         be as simple as a set of GPIO pins or as complex as a pair of FIFOs
 335         connected to dual DMA engines on the other side of the SPI shift
 336         register (maximizing throughput).  Such drivers bridge between
 337         whatever bus they sit on (often the platform bus) and SPI, and
 338         expose the SPI side of their device as a
 339         <structname>struct spi_master</structname>.
 340         SPI devices are children of that master, represented as a
 341         <structname>struct spi_device</structname> and manufactured from
 342         <structname>struct spi_board_info</structname> descriptors which
 343         are usually provided by board-specific initialization code.
 344         A <structname>struct spi_driver</structname> is called a
 345         "Protocol Driver", and is bound to a spi_device using normal
 346         driver model calls.
 347   </para>
 348   <para>
 349         The I/O model is a set of queued messages.  Protocol drivers
 350         submit one or more <structname>struct spi_message</structname>
 351         objects, which are processed and completed asynchronously.
 352         (There are synchronous wrappers, however.)  Messages are
 353         built from one or more <structname>struct spi_transfer</structname>
 354         objects, each of which wraps a full duplex SPI transfer.
 355         A variety of protocol tweaking options are needed, because
 356         different chips adopt very different policies for how they
 357         use the bits transferred with SPI.
 358   </para>
 359 !Iinclude/linux/spi/spi.h
 360 !Fdrivers/spi/spi.c spi_register_board_info
 361 !Edrivers/spi/spi.c
 362   </chapter>
 363
 364   <chapter id="i2c">
 365      <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
 366
 367      <para>
 368         I<superscript>2</superscript>C (or without fancy typography, "I2C")
 369         is an acronym for the "Inter-IC" bus, a simple bus protocol which is
 370         widely used where low data rate communications suffice.
 371         Since it's also a licensed trademark, some vendors use another
 372         name (such as "Two-Wire Interface", TWI) for the same bus.
 373         I2C only needs two signals (SCL for clock, SDA for data), conserving
 374         board real estate and minimizing signal quality issues.
 375         Most I2C devices use seven bit addresses, and bus speeds of up
 376         to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
 377         found wide use.
 378         I2C is a multi-master bus; open drain signaling is used to
 379         arbitrate between masters, as well as to handshake and to
 380         synchronize clocks from slower clients.
 381      </para>
 382
 383      <para>
 384         The Linux I2C programming interfaces support only the master
 385         side of bus interactions, not the slave side.
 386         The programming interface is structured around two kinds of driver,
 387         and two kinds of device.
 388         An I2C "Adapter Driver" abstracts the controller hardware; it binds
 389         to a physical device (perhaps a PCI device or platform_device) and
 390         exposes a <structname>struct i2c_adapter</structname> representing
 391         each I2C bus segment it manages.
 392         On each I2C bus segment will be I2C devices represented by a
 393         <structname>struct i2c_client</structname>.  Those devices will
 394         be bound to a <structname>struct i2c_driver</structname>,
 395         which should follow the standard Linux driver model.
 396         (At this writing, a legacy model is more widely used.)
 397         There are functions to perform various I2C protocol operations; at
 398         this writing all such functions are usable only from task context.
 399      </para>
 400
 401      <para>
 402         The System Management Bus (SMBus) is a sibling protocol.  Most SMBus
 403         systems are also I2C conformant.  The electrical constraints are
 404         tighter for SMBus, and it standardizes particular protocol messages
 405         and idioms.  Controllers that support I2C can also support most
 406         SMBus operations, but SMBus controllers don't support all the protocol
 407         options that an I2C controller will.
 408         There are functions to perform various SMBus protocol operations,
 409         either using I2C primitives or by issuing SMBus commands to
 410         i2c_adapter devices which don't support those I2C operations.
 411      </para>
 412
 413 !Iinclude/linux/i2c.h
 414 !Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
 415 !Edrivers/i2c/i2c-core.c
 416   </chapter>
 417
 418 </book>