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"
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   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      </sect1>
  50
  51      <sect1><title>Delaying, scheduling, and timer routines</title>
  52 !Iinclude/linux/sched.h
  53 !Ekernel/sched.c
  54 !Iinclude/linux/completion.h
  55 !Ekernel/timer.c
  56      </sect1>
  57      <sect1><title>Wait queues and Wake events</title>
  58 !Iinclude/linux/wait.h
  59 !Ekernel/wait.c
  60      </sect1>
  61      <sect1><title>High-resolution timers</title>
  62 !Iinclude/linux/ktime.h
  63 !Iinclude/linux/hrtimer.h
  64 !Ekernel/hrtimer.c
  65      </sect1>
  66      <sect1><title>Workqueues and Kevents</title>
  67 !Ekernel/workqueue.c
  68      </sect1>
  69      <sect1><title>Internal Functions</title>
  70 !Ikernel/exit.c
  71 !Ikernel/signal.c
  72 !Iinclude/linux/kthread.h
  73 !Ekernel/kthread.c
  74      </sect1>
  75
  76      <sect1><title>Kernel objects manipulation</title>
  77 <!--
  78 X!Iinclude/linux/kobject.h
  79 -->
  80 !Elib/kobject.c
  81      </sect1>
  82
  83      <sect1><title>Kernel utility functions</title>
  84 !Iinclude/linux/kernel.h
  85 !Ekernel/printk.c
  86 !Ekernel/panic.c
  87 !Ekernel/sys.c
  88 !Ekernel/rcupdate.c
  89      </sect1>
  90
  91      <sect1><title>Device Resource Management</title>
  92 !Edrivers/base/devres.c
  93      </sect1>
  94
  95   </chapter>
  96
  97   <chapter id="devdrivers">
  98      <title>Device drivers infrastructure</title>
  99      <sect1><title>Device Drivers Base</title>
 100 <!--
 101 X!Iinclude/linux/device.h
 102 -->
 103 !Edrivers/base/driver.c
 104 !Edrivers/base/core.c
 105 !Edrivers/base/class.c
 106 !Edrivers/base/firmware_class.c
 107 !Edrivers/base/transport_class.c
 108 <!-- Cannot be included, because
 109      attribute_container_add_class_device_adapter
 110  and attribute_container_classdev_to_container
 111      exceed allowed 44 characters maximum
 112 X!Edrivers/base/attribute_container.c
 113 -->
 114 !Edrivers/base/sys.c
 115 <!--
 116 X!Edrivers/base/interface.c
 117 -->
 118 !Iinclude/linux/platform_device.h
 119 !Edrivers/base/platform.c
 120 !Edrivers/base/bus.c
 121      </sect1>
 122      <sect1><title>Device Drivers Power Management</title>
 123 !Edrivers/base/power/main.c
 124      </sect1>
 125      <sect1><title>Device Drivers ACPI Support</title>
 126 <!-- Internal functions only
 127 X!Edrivers/acpi/sleep/main.c
 128 X!Edrivers/acpi/sleep/wakeup.c
 129 X!Edrivers/acpi/motherboard.c
 130 X!Edrivers/acpi/bus.c
 131 -->
 132 !Edrivers/acpi/scan.c
 133 !Idrivers/acpi/scan.c
 134 <!-- No correct structured comments
 135 X!Edrivers/acpi/pci_bind.c
 136 -->
 137      </sect1>
 138      <sect1><title>Device drivers PnP support</title>
 139 !Idrivers/pnp/core.c
 140 <!-- No correct structured comments
 141 X!Edrivers/pnp/system.c
 142  -->
 143 !Edrivers/pnp/card.c
 144 !Idrivers/pnp/driver.c
 145 !Edrivers/pnp/manager.c
 146 !Edrivers/pnp/support.c
 147      </sect1>
 148      <sect1><title>Userspace IO devices</title>
 149 !Edrivers/uio/uio.c
 150 !Iinclude/linux/uio_driver.h
 151      </sect1>
 152   </chapter>
 153
 154   <chapter id="parportdev">
 155      <title>Parallel Port Devices</title>
 156 !Iinclude/linux/parport.h
 157 !Edrivers/parport/ieee1284.c
 158 !Edrivers/parport/share.c
 159 !Idrivers/parport/daisy.c
 160   </chapter>
 161
 162   <chapter id="message_devices">
 163         <title>Message-based devices</title>
 164      <sect1><title>Fusion message devices</title>
 165 !Edrivers/message/fusion/mptbase.c
 166 !Idrivers/message/fusion/mptbase.c
 167 !Edrivers/message/fusion/mptscsih.c
 168 !Idrivers/message/fusion/mptscsih.c
 169 !Idrivers/message/fusion/mptctl.c
 170 !Idrivers/message/fusion/mptspi.c
 171 !Idrivers/message/fusion/mptfc.c
 172 !Idrivers/message/fusion/mptlan.c
 173      </sect1>
 174      <sect1><title>I2O message devices</title>
 175 !Iinclude/linux/i2o.h
 176 !Idrivers/message/i2o/core.h
 177 !Edrivers/message/i2o/iop.c
 178 !Idrivers/message/i2o/iop.c
 179 !Idrivers/message/i2o/config-osm.c
 180 !Edrivers/message/i2o/exec-osm.c
 181 !Idrivers/message/i2o/exec-osm.c
 182 !Idrivers/message/i2o/bus-osm.c
 183 !Edrivers/message/i2o/device.c
 184 !Idrivers/message/i2o/device.c
 185 !Idrivers/message/i2o/driver.c
 186 !Idrivers/message/i2o/pci.c
 187 !Idrivers/message/i2o/i2o_block.c
 188 !Idrivers/message/i2o/i2o_scsi.c
 189 !Idrivers/message/i2o/i2o_proc.c
 190      </sect1>
 191   </chapter>
 192
 193   <chapter id="snddev">
 194      <title>Sound Devices</title>
 195 !Iinclude/sound/core.h
 196 !Esound/sound_core.c
 197 !Iinclude/sound/pcm.h
 198 !Esound/core/pcm.c
 199 !Esound/core/device.c
 200 !Esound/core/info.c
 201 !Esound/core/rawmidi.c
 202 !Esound/core/sound.c
 203 !Esound/core/memory.c
 204 !Esound/core/pcm_memory.c
 205 !Esound/core/init.c
 206 !Esound/core/isadma.c
 207 !Esound/core/control.c
 208 !Esound/core/pcm_lib.c
 209 !Esound/core/hwdep.c
 210 !Esound/core/pcm_native.c
 211 !Esound/core/memalloc.c
 212 <!-- FIXME: Removed for now since no structured comments in source
 213 X!Isound/sound_firmware.c
 214 -->
 215   </chapter>
 216
 217   <chapter id="uart16x50">
 218      <title>16x50 UART Driver</title>
 219 !Iinclude/linux/serial_core.h
 220 !Edrivers/tty/serial/serial_core.c
 221 !Edrivers/tty/serial/8250.c
 222   </chapter>
 223
 224   <chapter id="fbdev">
 225      <title>Frame Buffer Library</title>
 226
 227      <para>
 228        The frame buffer drivers depend heavily on four data structures.
 229        These structures are declared in include/linux/fb.h.  They are
 230        fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
 231        The last three can be made available to and from userland.
 232      </para>
 233
 234      <para>
 235        fb_info defines the current state of a particular video card.
 236        Inside fb_info, there exists a fb_ops structure which is a
 237        collection of needed functions to make fbdev and fbcon work.
 238        fb_info is only visible to the kernel.
 239      </para>
 240
 241      <para>
 242        fb_var_screeninfo is used to describe the features of a video card
 243        that are user defined.  With fb_var_screeninfo, things such as
 244        depth and the resolution may be defined.
 245      </para>
 246
 247      <para>
 248        The next structure is fb_fix_screeninfo. This defines the
 249        properties of a card that are created when a mode is set and can't
 250        be changed otherwise.  A good example of this is the start of the
 251        frame buffer memory.  This "locks" the address of the frame buffer
 252        memory, so that it cannot be changed or moved.
 253      </para>
 254
 255      <para>
 256        The last structure is fb_monospecs. In the old API, there was
 257        little importance for fb_monospecs. This allowed for forbidden things
 258        such as setting a mode of 800x600 on a fix frequency monitor. With
 259        the new API, fb_monospecs prevents such things, and if used
 260        correctly, can prevent a monitor from being cooked.  fb_monospecs
 261        will not be useful until kernels 2.5.x.
 262      </para>
 263
 264      <sect1><title>Frame Buffer Memory</title>
 265 !Edrivers/video/fbmem.c
 266      </sect1>
 267 <!--
 268      <sect1><title>Frame Buffer Console</title>
 269 X!Edrivers/video/console/fbcon.c
 270      </sect1>
 271 -->
 272      <sect1><title>Frame Buffer Colormap</title>
 273 !Edrivers/video/fbcmap.c
 274      </sect1>
 275 <!-- FIXME:
 276   drivers/video/fbgen.c has no docs, which stuffs up the sgml.  Comment
 277   out until somebody adds docs.  KAO
 278      <sect1><title>Frame Buffer Generic Functions</title>
 279 X!Idrivers/video/fbgen.c
 280      </sect1>
 281 KAO -->
 282      <sect1><title>Frame Buffer Video Mode Database</title>
 283 !Idrivers/video/modedb.c
 284 !Edrivers/video/modedb.c
 285      </sect1>
 286      <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
 287 !Edrivers/video/macmodes.c
 288      </sect1>
 289      <sect1><title>Frame Buffer Fonts</title>
 290         <para>
 291            Refer to the file drivers/video/console/fonts.c for more information.
 292         </para>
 293 <!-- FIXME: Removed for now since no structured comments in source
 294 X!Idrivers/video/console/fonts.c
 295 -->
 296      </sect1>
 297   </chapter>
 298
 299   <chapter id="input_subsystem">
 300      <title>Input Subsystem</title>
 301      <sect1><title>Input core</title>
 302 !Iinclude/linux/input.h
 303 !Edrivers/input/input.c
 304 !Edrivers/input/ff-core.c
 305 !Edrivers/input/ff-memless.c
 306      </sect1>
 307      <sect1><title>Multitouch Library</title>
 308 !Iinclude/linux/input/mt.h
 309 !Edrivers/input/input-mt.c
 310      </sect1>
 311      <sect1><title>Polled input devices</title>
 312 !Iinclude/linux/input-polldev.h
 313 !Edrivers/input/input-polldev.c
 314      </sect1>
 315      <sect1><title>Matrix keyboars/keypads</title>
 316 !Iinclude/linux/input/matrix_keypad.h
 317      </sect1>
 318      <sect1><title>Sparse keymap support</title>
 319 !Iinclude/linux/input/sparse-keymap.h
 320 !Edrivers/input/sparse-keymap.c
 321      </sect1>
 322   </chapter>
 323
 324   <chapter id="spi">
 325       <title>Serial Peripheral Interface (SPI)</title>
 326   <para>
 327         SPI is the "Serial Peripheral Interface", widely used with
 328         embedded systems because it is a simple and efficient
 329         interface:  basically a multiplexed shift register.
 330         Its three signal wires hold a clock (SCK, often in the range
 331         of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
 332         a "Master In, Slave Out" (MISO) data line.
 333         SPI is a full duplex protocol; for each bit shifted out the
 334         MOSI line (one per clock) another is shifted in on the MISO line.
 335         Those bits are assembled into words of various sizes on the
 336         way to and from system memory.
 337         An additional chipselect line is usually active-low (nCS);
 338         four signals are normally used for each peripheral, plus
 339         sometimes an interrupt.
 340   </para>
 341   <para>
 342         The SPI bus facilities listed here provide a generalized
 343         interface to declare SPI busses and devices, manage them
 344         according to the standard Linux driver model, and perform
 345         input/output operations.
 346         At this time, only "master" side interfaces are supported,
 347         where Linux talks to SPI peripherals and does not implement
 348         such a peripheral itself.
 349         (Interfaces to support implementing SPI slaves would
 350         necessarily look different.)
 351   </para>
 352   <para>
 353         The programming interface is structured around two kinds of driver,
 354         and two kinds of device.
 355         A "Controller Driver" abstracts the controller hardware, which may
 356         be as simple as a set of GPIO pins or as complex as a pair of FIFOs
 357         connected to dual DMA engines on the other side of the SPI shift
 358         register (maximizing throughput).  Such drivers bridge between
 359         whatever bus they sit on (often the platform bus) and SPI, and
 360         expose the SPI side of their device as a
 361         <structname>struct spi_master</structname>.
 362         SPI devices are children of that master, represented as a
 363         <structname>struct spi_device</structname> and manufactured from
 364         <structname>struct spi_board_info</structname> descriptors which
 365         are usually provided by board-specific initialization code.
 366         A <structname>struct spi_driver</structname> is called a
 367         "Protocol Driver", and is bound to a spi_device using normal
 368         driver model calls.
 369   </para>
 370   <para>
 371         The I/O model is a set of queued messages.  Protocol drivers
 372         submit one or more <structname>struct spi_message</structname>
 373         objects, which are processed and completed asynchronously.
 374         (There are synchronous wrappers, however.)  Messages are
 375         built from one or more <structname>struct spi_transfer</structname>
 376         objects, each of which wraps a full duplex SPI transfer.
 377         A variety of protocol tweaking options are needed, because
 378         different chips adopt very different policies for how they
 379         use the bits transferred with SPI.
 380   </para>
 381 !Iinclude/linux/spi/spi.h
 382 !Fdrivers/spi/spi.c spi_register_board_info
 383 !Edrivers/spi/spi.c
 384   </chapter>
 385
 386   <chapter id="i2c">
 387      <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
 388
 389      <para>
 390         I<superscript>2</superscript>C (or without fancy typography, "I2C")
 391         is an acronym for the "Inter-IC" bus, a simple bus protocol which is
 392         widely used where low data rate communications suffice.
 393         Since it's also a licensed trademark, some vendors use another
 394         name (such as "Two-Wire Interface", TWI) for the same bus.
 395         I2C only needs two signals (SCL for clock, SDA for data), conserving
 396         board real estate and minimizing signal quality issues.
 397         Most I2C devices use seven bit addresses, and bus speeds of up
 398         to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
 399         found wide use.
 400         I2C is a multi-master bus; open drain signaling is used to
 401         arbitrate between masters, as well as to handshake and to
 402         synchronize clocks from slower clients.
 403      </para>
 404
 405      <para>
 406         The Linux I2C programming interfaces support only the master
 407         side of bus interactions, not the slave side.
 408         The programming interface is structured around two kinds of driver,
 409         and two kinds of device.
 410         An I2C "Adapter Driver" abstracts the controller hardware; it binds
 411         to a physical device (perhaps a PCI device or platform_device) and
 412         exposes a <structname>struct i2c_adapter</structname> representing
 413         each I2C bus segment it manages.
 414         On each I2C bus segment will be I2C devices represented by a
 415         <structname>struct i2c_client</structname>.  Those devices will
 416         be bound to a <structname>struct i2c_driver</structname>,
 417         which should follow the standard Linux driver model.
 418         (At this writing, a legacy model is more widely used.)
 419         There are functions to perform various I2C protocol operations; at
 420         this writing all such functions are usable only from task context.
 421      </para>
 422
 423      <para>
 424         The System Management Bus (SMBus) is a sibling protocol.  Most SMBus
 425         systems are also I2C conformant.  The electrical constraints are
 426         tighter for SMBus, and it standardizes particular protocol messages
 427         and idioms.  Controllers that support I2C can also support most
 428         SMBus operations, but SMBus controllers don't support all the protocol
 429         options that an I2C controller will.
 430         There are functions to perform various SMBus protocol operations,
 431         either using I2C primitives or by issuing SMBus commands to
 432         i2c_adapter devices which don't support those I2C operations.
 433      </para>
 434
 435 !Iinclude/linux/i2c.h
 436 !Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
 437 !Edrivers/i2c/i2c-core.c
 438   </chapter>
 439
 440 </book>