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.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 !Iinclude/linux/platform_device.h
 115 !Edrivers/base/platform.c
 116 !Edrivers/base/bus.c
 117      </sect1>
 118      <sect1><title>Device Drivers Power Management</title>
 119 !Edrivers/base/power/main.c
 120      </sect1>
 121      <sect1><title>Device Drivers ACPI Support</title>
 122 <!-- Internal functions only
 123 X!Edrivers/acpi/sleep/main.c
 124 X!Edrivers/acpi/sleep/wakeup.c
 125 X!Edrivers/acpi/motherboard.c
 126 X!Edrivers/acpi/bus.c
 127 -->
 128 !Edrivers/acpi/scan.c
 129 !Idrivers/acpi/scan.c
 130 <!-- No correct structured comments
 131 X!Edrivers/acpi/pci_bind.c
 132 -->
 133      </sect1>
 134      <sect1><title>Device drivers PnP support</title>
 135 !Idrivers/pnp/core.c
 136 <!-- No correct structured comments
 137 X!Edrivers/pnp/system.c
 138  -->
 139 !Edrivers/pnp/card.c
 140 !Idrivers/pnp/driver.c
 141 !Edrivers/pnp/manager.c
 142 !Edrivers/pnp/support.c
 143      </sect1>
 144      <sect1><title>Userspace IO devices</title>
 145 !Edrivers/uio/uio.c
 146 !Iinclude/linux/uio_driver.h
 147      </sect1>
 148   </chapter>
 149
 150   <chapter id="parportdev">
 151      <title>Parallel Port Devices</title>
 152 !Iinclude/linux/parport.h
 153 !Edrivers/parport/ieee1284.c
 154 !Edrivers/parport/share.c
 155 !Idrivers/parport/daisy.c
 156   </chapter>
 157
 158   <chapter id="message_devices">
 159         <title>Message-based devices</title>
 160      <sect1><title>Fusion message devices</title>
 161 !Edrivers/message/fusion/mptbase.c
 162 !Idrivers/message/fusion/mptbase.c
 163 !Edrivers/message/fusion/mptscsih.c
 164 !Idrivers/message/fusion/mptscsih.c
 165 !Idrivers/message/fusion/mptctl.c
 166 !Idrivers/message/fusion/mptspi.c
 167 !Idrivers/message/fusion/mptfc.c
 168 !Idrivers/message/fusion/mptlan.c
 169      </sect1>
 170      <sect1><title>I2O message devices</title>
 171 !Iinclude/linux/i2o.h
 172 !Idrivers/message/i2o/core.h
 173 !Edrivers/message/i2o/iop.c
 174 !Idrivers/message/i2o/iop.c
 175 !Idrivers/message/i2o/config-osm.c
 176 !Edrivers/message/i2o/exec-osm.c
 177 !Idrivers/message/i2o/exec-osm.c
 178 !Idrivers/message/i2o/bus-osm.c
 179 !Edrivers/message/i2o/device.c
 180 !Idrivers/message/i2o/device.c
 181 !Idrivers/message/i2o/driver.c
 182 !Idrivers/message/i2o/pci.c
 183 !Idrivers/message/i2o/i2o_block.c
 184 !Idrivers/message/i2o/i2o_scsi.c
 185 !Idrivers/message/i2o/i2o_proc.c
 186      </sect1>
 187   </chapter>
 188
 189   <chapter id="snddev">
 190      <title>Sound Devices</title>
 191 !Iinclude/sound/core.h
 192 !Esound/sound_core.c
 193 !Iinclude/sound/pcm.h
 194 !Esound/core/pcm.c
 195 !Esound/core/device.c
 196 !Esound/core/info.c
 197 !Esound/core/rawmidi.c
 198 !Esound/core/sound.c
 199 !Esound/core/memory.c
 200 !Esound/core/pcm_memory.c
 201 !Esound/core/init.c
 202 !Esound/core/isadma.c
 203 !Esound/core/control.c
 204 !Esound/core/pcm_lib.c
 205 !Esound/core/hwdep.c
 206 !Esound/core/pcm_native.c
 207 !Esound/core/memalloc.c
 208 <!-- FIXME: Removed for now since no structured comments in source
 209 X!Isound/sound_firmware.c
 210 -->
 211   </chapter>
 212
 213   <chapter id="uart16x50">
 214      <title>16x50 UART Driver</title>
 215 !Iinclude/linux/serial_core.h
 216 !Edrivers/serial/serial_core.c
 217 !Edrivers/serial/8250.c
 218   </chapter>
 219
 220   <chapter id="fbdev">
 221      <title>Frame Buffer Library</title>
 222
 223      <para>
 224        The frame buffer drivers depend heavily on four data structures.
 225        These structures are declared in include/linux/fb.h.  They are
 226        fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
 227        The last three can be made available to and from userland.
 228      </para>
 229
 230      <para>
 231        fb_info defines the current state of a particular video card.
 232        Inside fb_info, there exists a fb_ops structure which is a
 233        collection of needed functions to make fbdev and fbcon work.
 234        fb_info is only visible to the kernel.
 235      </para>
 236
 237      <para>
 238        fb_var_screeninfo is used to describe the features of a video card
 239        that are user defined.  With fb_var_screeninfo, things such as
 240        depth and the resolution may be defined.
 241      </para>
 242
 243      <para>
 244        The next structure is fb_fix_screeninfo. This defines the
 245        properties of a card that are created when a mode is set and can't
 246        be changed otherwise.  A good example of this is the start of the
 247        frame buffer memory.  This "locks" the address of the frame buffer
 248        memory, so that it cannot be changed or moved.
 249      </para>
 250
 251      <para>
 252        The last structure is fb_monospecs. In the old API, there was
 253        little importance for fb_monospecs. This allowed for forbidden things
 254        such as setting a mode of 800x600 on a fix frequency monitor. With
 255        the new API, fb_monospecs prevents such things, and if used
 256        correctly, can prevent a monitor from being cooked.  fb_monospecs
 257        will not be useful until kernels 2.5.x.
 258      </para>
 259
 260      <sect1><title>Frame Buffer Memory</title>
 261 !Edrivers/video/fbmem.c
 262      </sect1>
 263 <!--
 264      <sect1><title>Frame Buffer Console</title>
 265 X!Edrivers/video/console/fbcon.c
 266      </sect1>
 267 -->
 268      <sect1><title>Frame Buffer Colormap</title>
 269 !Edrivers/video/fbcmap.c
 270      </sect1>
 271 <!-- FIXME:
 272   drivers/video/fbgen.c has no docs, which stuffs up the sgml.  Comment
 273   out until somebody adds docs.  KAO
 274      <sect1><title>Frame Buffer Generic Functions</title>
 275 X!Idrivers/video/fbgen.c
 276      </sect1>
 277 KAO -->
 278      <sect1><title>Frame Buffer Video Mode Database</title>
 279 !Idrivers/video/modedb.c
 280 !Edrivers/video/modedb.c
 281      </sect1>
 282      <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
 283 !Edrivers/video/macmodes.c
 284      </sect1>
 285      <sect1><title>Frame Buffer Fonts</title>
 286         <para>
 287            Refer to the file drivers/video/console/fonts.c for more information.
 288         </para>
 289 <!-- FIXME: Removed for now since no structured comments in source
 290 X!Idrivers/video/console/fonts.c
 291 -->
 292      </sect1>
 293   </chapter>
 294
 295   <chapter id="input_subsystem">
 296      <title>Input Subsystem</title>
 297      <sect1><title>Input core</title>
 298 !Iinclude/linux/input.h
 299 !Edrivers/input/input.c
 300 !Edrivers/input/ff-core.c
 301 !Edrivers/input/ff-memless.c
 302      </sect1>
 303      <sect1><title>Polled input devices</title>
 304 !Iinclude/linux/input-polldev.h
 305 !Edrivers/input/input-polldev.c
 306      </sect1>
 307      <sect1><title>Matrix keyboars/keypads</title>
 308 !Iinclude/linux/input/matrix_keypad.h
 309      </sect1>
 310      <sect1><title>Sparse keymap support</title>
 311 !Iinclude/linux/input/sparse-keymap.h
 312 !Edrivers/input/sparse-keymap.c
 313      </sect1>
 314   </chapter>
 315
 316   <chapter id="spi">
 317       <title>Serial Peripheral Interface (SPI)</title>
 318   <para>
 319         SPI is the "Serial Peripheral Interface", widely used with
 320         embedded systems because it is a simple and efficient
 321         interface:  basically a multiplexed shift register.
 322         Its three signal wires hold a clock (SCK, often in the range
 323         of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
 324         a "Master In, Slave Out" (MISO) data line.
 325         SPI is a full duplex protocol; for each bit shifted out the
 326         MOSI line (one per clock) another is shifted in on the MISO line.
 327         Those bits are assembled into words of various sizes on the
 328         way to and from system memory.
 329         An additional chipselect line is usually active-low (nCS);
 330         four signals are normally used for each peripheral, plus
 331         sometimes an interrupt.
 332   </para>
 333   <para>
 334         The SPI bus facilities listed here provide a generalized
 335         interface to declare SPI busses and devices, manage them
 336         according to the standard Linux driver model, and perform
 337         input/output operations.
 338         At this time, only "master" side interfaces are supported,
 339         where Linux talks to SPI peripherals and does not implement
 340         such a peripheral itself.
 341         (Interfaces to support implementing SPI slaves would
 342         necessarily look different.)
 343   </para>
 344   <para>
 345         The programming interface is structured around two kinds of driver,
 346         and two kinds of device.
 347         A "Controller Driver" abstracts the controller hardware, which may
 348         be as simple as a set of GPIO pins or as complex as a pair of FIFOs
 349         connected to dual DMA engines on the other side of the SPI shift
 350         register (maximizing throughput).  Such drivers bridge between
 351         whatever bus they sit on (often the platform bus) and SPI, and
 352         expose the SPI side of their device as a
 353         <structname>struct spi_master</structname>.
 354         SPI devices are children of that master, represented as a
 355         <structname>struct spi_device</structname> and manufactured from
 356         <structname>struct spi_board_info</structname> descriptors which
 357         are usually provided by board-specific initialization code.
 358         A <structname>struct spi_driver</structname> is called a
 359         "Protocol Driver", and is bound to a spi_device using normal
 360         driver model calls.
 361   </para>
 362   <para>
 363         The I/O model is a set of queued messages.  Protocol drivers
 364         submit one or more <structname>struct spi_message</structname>
 365         objects, which are processed and completed asynchronously.
 366         (There are synchronous wrappers, however.)  Messages are
 367         built from one or more <structname>struct spi_transfer</structname>
 368         objects, each of which wraps a full duplex SPI transfer.
 369         A variety of protocol tweaking options are needed, because
 370         different chips adopt very different policies for how they
 371         use the bits transferred with SPI.
 372   </para>
 373 !Iinclude/linux/spi/spi.h
 374 !Fdrivers/spi/spi.c spi_register_board_info
 375 !Edrivers/spi/spi.c
 376   </chapter>
 377
 378   <chapter id="i2c">
 379      <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
 380
 381      <para>
 382         I<superscript>2</superscript>C (or without fancy typography, "I2C")
 383         is an acronym for the "Inter-IC" bus, a simple bus protocol which is
 384         widely used where low data rate communications suffice.
 385         Since it's also a licensed trademark, some vendors use another
 386         name (such as "Two-Wire Interface", TWI) for the same bus.
 387         I2C only needs two signals (SCL for clock, SDA for data), conserving
 388         board real estate and minimizing signal quality issues.
 389         Most I2C devices use seven bit addresses, and bus speeds of up
 390         to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
 391         found wide use.
 392         I2C is a multi-master bus; open drain signaling is used to
 393         arbitrate between masters, as well as to handshake and to
 394         synchronize clocks from slower clients.
 395      </para>
 396
 397      <para>
 398         The Linux I2C programming interfaces support only the master
 399         side of bus interactions, not the slave side.
 400         The programming interface is structured around two kinds of driver,
 401         and two kinds of device.
 402         An I2C "Adapter Driver" abstracts the controller hardware; it binds
 403         to a physical device (perhaps a PCI device or platform_device) and
 404         exposes a <structname>struct i2c_adapter</structname> representing
 405         each I2C bus segment it manages.
 406         On each I2C bus segment will be I2C devices represented by a
 407         <structname>struct i2c_client</structname>.  Those devices will
 408         be bound to a <structname>struct i2c_driver</structname>,
 409         which should follow the standard Linux driver model.
 410         (At this writing, a legacy model is more widely used.)
 411         There are functions to perform various I2C protocol operations; at
 412         this writing all such functions are usable only from task context.
 413      </para>
 414
 415      <para>
 416         The System Management Bus (SMBus) is a sibling protocol.  Most SMBus
 417         systems are also I2C conformant.  The electrical constraints are
 418         tighter for SMBus, and it standardizes particular protocol messages
 419         and idioms.  Controllers that support I2C can also support most
 420         SMBus operations, but SMBus controllers don't support all the protocol
 421         options that an I2C controller will.
 422         There are functions to perform various SMBus protocol operations,
 423         either using I2C primitives or by issuing SMBus commands to
 424         i2c_adapter devices which don't support those I2C operations.
 425      </para>
 426
 427 !Iinclude/linux/i2c.h
 428 !Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
 429 !Edrivers/i2c/i2c-core.c
 430   </chapter>
 431
 432 </book>