Documentation/DocBook/device-drivers.tmpl

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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/core.c
  54 !Ikernel/sched/cpupri.c
  55 !Ikernel/sched/fair.c
  56 !Iinclude/linux/completion.h
  57 !Ekernel/time/timer.c
  58      </sect1>
  59      <sect1><title>Wait queues and Wake events</title>
  60 !Iinclude/linux/wait.h
  61 !Ekernel/sched/wait.c
  62      </sect1>
  63      <sect1><title>High-resolution timers</title>
  64 !Iinclude/linux/ktime.h
  65 !Iinclude/linux/hrtimer.h
  66 !Ekernel/time/hrtimer.c
  67      </sect1>
  68      <sect1><title>Workqueues and Kevents</title>
  69 !Iinclude/linux/workqueue.h
  70 !Ekernel/workqueue.c
  71      </sect1>
  72      <sect1><title>Internal Functions</title>
  73 !Ikernel/exit.c
  74 !Ikernel/signal.c
  75 !Iinclude/linux/kthread.h
  76 !Ekernel/kthread.c
  77      </sect1>
  78
  79      <sect1><title>Kernel objects manipulation</title>
  80 <!--
  81 X!Iinclude/linux/kobject.h
  82 -->
  83 !Elib/kobject.c
  84      </sect1>
  85
  86      <sect1><title>Kernel utility functions</title>
  87 !Iinclude/linux/kernel.h
  88 !Ekernel/printk/printk.c
  89 !Ekernel/panic.c
  90 !Ekernel/sys.c
  91 !Ekernel/rcu/srcu.c
  92 !Ekernel/rcu/tree.c
  93 !Ekernel/rcu/tree_plugin.h
  94 !Ekernel/rcu/update.c
  95      </sect1>
  96
  97      <sect1><title>Device Resource Management</title>
  98 !Edrivers/base/devres.c
  99      </sect1>
 100
 101   </chapter>
 102
 103   <chapter id="devdrivers">
 104      <title>Device drivers infrastructure</title>
 105      <sect1><title>The Basic Device Driver-Model Structures </title>
 106 !Iinclude/linux/device.h
 107      </sect1>
 108      <sect1><title>Device Drivers Base</title>
 109 !Idrivers/base/init.c
 110 !Edrivers/base/driver.c
 111 !Edrivers/base/core.c
 112 !Edrivers/base/syscore.c
 113 !Edrivers/base/class.c
 114 !Idrivers/base/node.c
 115 !Edrivers/base/firmware_class.c
 116 !Edrivers/base/transport_class.c
 117 <!-- Cannot be included, because
 118      attribute_container_add_class_device_adapter
 119  and attribute_container_classdev_to_container
 120      exceed allowed 44 characters maximum
 121 X!Edrivers/base/attribute_container.c
 122 -->
 123 !Edrivers/base/dd.c
 124 <!--
 125 X!Edrivers/base/interface.c
 126 -->
 127 !Iinclude/linux/platform_device.h
 128 !Edrivers/base/platform.c
 129 !Edrivers/base/bus.c
 130      </sect1>
 131      <sect1><title>Device Drivers DMA Management</title>
 132 !Edrivers/dma-buf/dma-buf.c
 133 !Edrivers/dma-buf/fence.c
 134 !Edrivers/dma-buf/seqno-fence.c
 135 !Iinclude/linux/fence.h
 136 !Iinclude/linux/seqno-fence.h
 137 !Edrivers/dma-buf/reservation.c
 138 !Iinclude/linux/reservation.h
 139 !Edrivers/base/dma-coherent.c
 140 !Edrivers/base/dma-mapping.c
 141      </sect1>
 142      <sect1><title>Device Drivers Power Management</title>
 143 !Edrivers/base/power/main.c
 144      </sect1>
 145      <sect1><title>Device Drivers ACPI Support</title>
 146 <!-- Internal functions only
 147 X!Edrivers/acpi/sleep/main.c
 148 X!Edrivers/acpi/sleep/wakeup.c
 149 X!Edrivers/acpi/motherboard.c
 150 X!Edrivers/acpi/bus.c
 151 -->
 152 !Edrivers/acpi/scan.c
 153 !Idrivers/acpi/scan.c
 154 <!-- No correct structured comments
 155 X!Edrivers/acpi/pci_bind.c
 156 -->
 157      </sect1>
 158      <sect1><title>Device drivers PnP support</title>
 159 !Idrivers/pnp/core.c
 160 <!-- No correct structured comments
 161 X!Edrivers/pnp/system.c
 162  -->
 163 !Edrivers/pnp/card.c
 164 !Idrivers/pnp/driver.c
 165 !Edrivers/pnp/manager.c
 166 !Edrivers/pnp/support.c
 167      </sect1>
 168      <sect1><title>Userspace IO devices</title>
 169 !Edrivers/uio/uio.c
 170 !Iinclude/linux/uio_driver.h
 171      </sect1>
 172   </chapter>
 173
 174   <chapter id="parportdev">
 175      <title>Parallel Port Devices</title>
 176 !Iinclude/linux/parport.h
 177 !Edrivers/parport/ieee1284.c
 178 !Edrivers/parport/share.c
 179 !Idrivers/parport/daisy.c
 180   </chapter>
 181
 182   <chapter id="message_devices">
 183         <title>Message-based devices</title>
 184      <sect1><title>Fusion message devices</title>
 185 !Edrivers/message/fusion/mptbase.c
 186 !Idrivers/message/fusion/mptbase.c
 187 !Edrivers/message/fusion/mptscsih.c
 188 !Idrivers/message/fusion/mptscsih.c
 189 !Idrivers/message/fusion/mptctl.c
 190 !Idrivers/message/fusion/mptspi.c
 191 !Idrivers/message/fusion/mptfc.c
 192 !Idrivers/message/fusion/mptlan.c
 193      </sect1>
 194   </chapter>
 195
 196   <chapter id="snddev">
 197      <title>Sound Devices</title>
 198 !Iinclude/sound/core.h
 199 !Esound/sound_core.c
 200 !Iinclude/sound/pcm.h
 201 !Esound/core/pcm.c
 202 !Esound/core/device.c
 203 !Esound/core/info.c
 204 !Esound/core/rawmidi.c
 205 !Esound/core/sound.c
 206 !Esound/core/memory.c
 207 !Esound/core/pcm_memory.c
 208 !Esound/core/init.c
 209 !Esound/core/isadma.c
 210 !Esound/core/control.c
 211 !Esound/core/pcm_lib.c
 212 !Esound/core/hwdep.c
 213 !Esound/core/pcm_native.c
 214 !Esound/core/memalloc.c
 215 <!-- FIXME: Removed for now since no structured comments in source
 216 X!Isound/sound_firmware.c
 217 -->
 218   </chapter>
 219
 220   <chapter id="mediadev">
 221      <title>Media Devices</title>
 222
 223      <sect1><title>Video2Linux devices</title>
 224 !Iinclude/media/tuner.h
 225 !Iinclude/media/tuner-types.h
 226 !Iinclude/media/tveeprom.h
 227 !Iinclude/media/v4l2-async.h
 228 !Iinclude/media/v4l2-ctrls.h
 229 !Iinclude/media/v4l2-dv-timings.h
 230 !Iinclude/media/v4l2-event.h
 231 !Iinclude/media/v4l2-flash-led-class.h
 232 !Iinclude/media/v4l2-mediabus.h
 233 !Iinclude/media/v4l2-mem2mem.h
 234 !Iinclude/media/v4l2-of.h
 235 !Iinclude/media/v4l2-subdev.h
 236 !Iinclude/media/videobuf2-core.h
 237 !Iinclude/media/videobuf2-v4l2.h
 238 !Iinclude/media/videobuf2-memops.h
 239      </sect1>
 240      <sect1><title>Digital TV (DVB) devices</title>
 241         <sect1><title>Digital TV Common functions</title>
 242 !Idrivers/media/dvb-core/dvb_math.h
 243 !Idrivers/media/dvb-core/dvb_ringbuffer.h
 244 !Idrivers/media/dvb-core/dvbdev.h
 245         </sect1>
 246         <sect1><title>Digital TV Frontend kABI</title>
 247 !Pdrivers/media/dvb-core/dvb_frontend.h Digital TV Frontend
 248 !Idrivers/media/dvb-core/dvb_frontend.h
 249         </sect1>
 250         <sect1><title>Digital TV Demux kABI</title>
 251 !Pdrivers/media/dvb-core/demux.h Digital TV Demux
 252         <sect1><title>Demux Callback API</title>
 253 !Pdrivers/media/dvb-core/demux.h Demux Callback
 254         </sect1>
 255 !Idrivers/media/dvb-core/demux.h
 256         </sect1>
 257         <sect1><title>Digital TV Conditional Access kABI</title>
 258 !Idrivers/media/dvb-core/dvb_ca_en50221.h
 259         </sect1>
 260      </sect1>
 261     <sect1><title>Remote Controller devices</title>
 262 !Iinclude/media/rc-core.h
 263 !Iinclude/media/lirc_dev.h
 264     </sect1>
 265     <sect1><title>Media Controller devices</title>
 266 !Iinclude/media/media-device.h
 267 !Iinclude/media/media-devnode.h
 268 !Iinclude/media/media-entity.h
 269     </sect1>
 270
 271   </chapter>
 272
 273   <chapter id="uart16x50">
 274      <title>16x50 UART Driver</title>
 275 !Edrivers/tty/serial/serial_core.c
 276 !Edrivers/tty/serial/8250/8250_core.c
 277   </chapter>
 278
 279   <chapter id="fbdev">
 280      <title>Frame Buffer Library</title>
 281
 282      <para>
 283        The frame buffer drivers depend heavily on four data structures.
 284        These structures are declared in include/linux/fb.h.  They are
 285        fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
 286        The last three can be made available to and from userland.
 287      </para>
 288
 289      <para>
 290        fb_info defines the current state of a particular video card.
 291        Inside fb_info, there exists a fb_ops structure which is a
 292        collection of needed functions to make fbdev and fbcon work.
 293        fb_info is only visible to the kernel.
 294      </para>
 295
 296      <para>
 297        fb_var_screeninfo is used to describe the features of a video card
 298        that are user defined.  With fb_var_screeninfo, things such as
 299        depth and the resolution may be defined.
 300      </para>
 301
 302      <para>
 303        The next structure is fb_fix_screeninfo. This defines the
 304        properties of a card that are created when a mode is set and can't
 305        be changed otherwise.  A good example of this is the start of the
 306        frame buffer memory.  This "locks" the address of the frame buffer
 307        memory, so that it cannot be changed or moved.
 308      </para>
 309
 310      <para>
 311        The last structure is fb_monospecs. In the old API, there was
 312        little importance for fb_monospecs. This allowed for forbidden things
 313        such as setting a mode of 800x600 on a fix frequency monitor. With
 314        the new API, fb_monospecs prevents such things, and if used
 315        correctly, can prevent a monitor from being cooked.  fb_monospecs
 316        will not be useful until kernels 2.5.x.
 317      </para>
 318
 319      <sect1><title>Frame Buffer Memory</title>
 320 !Edrivers/video/fbdev/core/fbmem.c
 321      </sect1>
 322 <!--
 323      <sect1><title>Frame Buffer Console</title>
 324 X!Edrivers/video/console/fbcon.c
 325      </sect1>
 326 -->
 327      <sect1><title>Frame Buffer Colormap</title>
 328 !Edrivers/video/fbdev/core/fbcmap.c
 329      </sect1>
 330 <!-- FIXME:
 331   drivers/video/fbgen.c has no docs, which stuffs up the sgml.  Comment
 332   out until somebody adds docs.  KAO
 333      <sect1><title>Frame Buffer Generic Functions</title>
 334 X!Idrivers/video/fbgen.c
 335      </sect1>
 336 KAO -->
 337      <sect1><title>Frame Buffer Video Mode Database</title>
 338 !Idrivers/video/fbdev/core/modedb.c
 339 !Edrivers/video/fbdev/core/modedb.c
 340      </sect1>
 341      <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
 342 !Edrivers/video/fbdev/macmodes.c
 343      </sect1>
 344      <sect1><title>Frame Buffer Fonts</title>
 345         <para>
 346            Refer to the file lib/fonts/fonts.c for more information.
 347         </para>
 348 <!-- FIXME: Removed for now since no structured comments in source
 349 X!Ilib/fonts/fonts.c
 350 -->
 351      </sect1>
 352   </chapter>
 353
 354   <chapter id="input_subsystem">
 355      <title>Input Subsystem</title>
 356      <sect1><title>Input core</title>
 357 !Iinclude/linux/input.h
 358 !Edrivers/input/input.c
 359 !Edrivers/input/ff-core.c
 360 !Edrivers/input/ff-memless.c
 361      </sect1>
 362      <sect1><title>Multitouch Library</title>
 363 !Iinclude/linux/input/mt.h
 364 !Edrivers/input/input-mt.c
 365      </sect1>
 366      <sect1><title>Polled input devices</title>
 367 !Iinclude/linux/input-polldev.h
 368 !Edrivers/input/input-polldev.c
 369      </sect1>
 370      <sect1><title>Matrix keyboars/keypads</title>
 371 !Iinclude/linux/input/matrix_keypad.h
 372      </sect1>
 373      <sect1><title>Sparse keymap support</title>
 374 !Iinclude/linux/input/sparse-keymap.h
 375 !Edrivers/input/sparse-keymap.c
 376      </sect1>
 377   </chapter>
 378
 379   <chapter id="spi">
 380       <title>Serial Peripheral Interface (SPI)</title>
 381   <para>
 382         SPI is the "Serial Peripheral Interface", widely used with
 383         embedded systems because it is a simple and efficient
 384         interface:  basically a multiplexed shift register.
 385         Its three signal wires hold a clock (SCK, often in the range
 386         of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
 387         a "Master In, Slave Out" (MISO) data line.
 388         SPI is a full duplex protocol; for each bit shifted out the
 389         MOSI line (one per clock) another is shifted in on the MISO line.
 390         Those bits are assembled into words of various sizes on the
 391         way to and from system memory.
 392         An additional chipselect line is usually active-low (nCS);
 393         four signals are normally used for each peripheral, plus
 394         sometimes an interrupt.
 395   </para>
 396   <para>
 397         The SPI bus facilities listed here provide a generalized
 398         interface to declare SPI busses and devices, manage them
 399         according to the standard Linux driver model, and perform
 400         input/output operations.
 401         At this time, only "master" side interfaces are supported,
 402         where Linux talks to SPI peripherals and does not implement
 403         such a peripheral itself.
 404         (Interfaces to support implementing SPI slaves would
 405         necessarily look different.)
 406   </para>
 407   <para>
 408         The programming interface is structured around two kinds of driver,
 409         and two kinds of device.
 410         A "Controller Driver" abstracts the controller hardware, which may
 411         be as simple as a set of GPIO pins or as complex as a pair of FIFOs
 412         connected to dual DMA engines on the other side of the SPI shift
 413         register (maximizing throughput).  Such drivers bridge between
 414         whatever bus they sit on (often the platform bus) and SPI, and
 415         expose the SPI side of their device as a
 416         <structname>struct spi_master</structname>.
 417         SPI devices are children of that master, represented as a
 418         <structname>struct spi_device</structname> and manufactured from
 419         <structname>struct spi_board_info</structname> descriptors which
 420         are usually provided by board-specific initialization code.
 421         A <structname>struct spi_driver</structname> is called a
 422         "Protocol Driver", and is bound to a spi_device using normal
 423         driver model calls.
 424   </para>
 425   <para>
 426         The I/O model is a set of queued messages.  Protocol drivers
 427         submit one or more <structname>struct spi_message</structname>
 428         objects, which are processed and completed asynchronously.
 429         (There are synchronous wrappers, however.)  Messages are
 430         built from one or more <structname>struct spi_transfer</structname>
 431         objects, each of which wraps a full duplex SPI transfer.
 432         A variety of protocol tweaking options are needed, because
 433         different chips adopt very different policies for how they
 434         use the bits transferred with SPI.
 435   </para>
 436 !Iinclude/linux/spi/spi.h
 437 !Fdrivers/spi/spi.c spi_register_board_info
 438 !Edrivers/spi/spi.c
 439   </chapter>
 440
 441   <chapter id="i2c">
 442      <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
 443
 444      <para>
 445         I<superscript>2</superscript>C (or without fancy typography, "I2C")
 446         is an acronym for the "Inter-IC" bus, a simple bus protocol which is
 447         widely used where low data rate communications suffice.
 448         Since it's also a licensed trademark, some vendors use another
 449         name (such as "Two-Wire Interface", TWI) for the same bus.
 450         I2C only needs two signals (SCL for clock, SDA for data), conserving
 451         board real estate and minimizing signal quality issues.
 452         Most I2C devices use seven bit addresses, and bus speeds of up
 453         to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
 454         found wide use.
 455         I2C is a multi-master bus; open drain signaling is used to
 456         arbitrate between masters, as well as to handshake and to
 457         synchronize clocks from slower clients.
 458      </para>
 459
 460      <para>
 461         The Linux I2C programming interfaces support only the master
 462         side of bus interactions, not the slave side.
 463         The programming interface is structured around two kinds of driver,
 464         and two kinds of device.
 465         An I2C "Adapter Driver" abstracts the controller hardware; it binds
 466         to a physical device (perhaps a PCI device or platform_device) and
 467         exposes a <structname>struct i2c_adapter</structname> representing
 468         each I2C bus segment it manages.
 469         On each I2C bus segment will be I2C devices represented by a
 470         <structname>struct i2c_client</structname>.  Those devices will
 471         be bound to a <structname>struct i2c_driver</structname>,
 472         which should follow the standard Linux driver model.
 473         (At this writing, a legacy model is more widely used.)
 474         There are functions to perform various I2C protocol operations; at
 475         this writing all such functions are usable only from task context.
 476      </para>
 477
 478      <para>
 479         The System Management Bus (SMBus) is a sibling protocol.  Most SMBus
 480         systems are also I2C conformant.  The electrical constraints are
 481         tighter for SMBus, and it standardizes particular protocol messages
 482         and idioms.  Controllers that support I2C can also support most
 483         SMBus operations, but SMBus controllers don't support all the protocol
 484         options that an I2C controller will.
 485         There are functions to perform various SMBus protocol operations,
 486         either using I2C primitives or by issuing SMBus commands to
 487         i2c_adapter devices which don't support those I2C operations.
 488      </para>
 489
 490 !Iinclude/linux/i2c.h
 491 !Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
 492 !Edrivers/i2c/i2c-core.c
 493   </chapter>
 494
 495   <chapter id="hsi">
 496      <title>High Speed Synchronous Serial Interface (HSI)</title>
 497
 498      <para>
 499         High Speed Synchronous Serial Interface (HSI) is a
 500         serial interface mainly used for connecting application
 501         engines (APE) with cellular modem engines (CMT) in cellular
 502         handsets.
 503
 504         HSI provides multiplexing for up to 16 logical channels,
 505         low-latency and full duplex communication.
 506      </para>
 507
 508 !Iinclude/linux/hsi/hsi.h
 509 !Edrivers/hsi/hsi.c
 510   </chapter>
 511
 512   <chapter id="pwm">
 513     <title>Pulse-Width Modulation (PWM)</title>
 514     <para>
 515       Pulse-width modulation is a modulation technique primarily used to
 516       control power supplied to electrical devices.
 517     </para>
 518     <para>
 519       The PWM framework provides an abstraction for providers and consumers
 520       of PWM signals. A controller that provides one or more PWM signals is
 521       registered as <structname>struct pwm_chip</structname>. Providers are
 522       expected to embed this structure in a driver-specific structure. This
 523       structure contains fields that describe a particular chip.
 524     </para>
 525     <para>
 526       A chip exposes one or more PWM signal sources, each of which exposed
 527       as a <structname>struct pwm_device</structname>. Operations can be
 528       performed on PWM devices to control the period, duty cycle, polarity
 529       and active state of the signal.
 530     </para>
 531     <para>
 532       Note that PWM devices are exclusive resources: they can always only be
 533       used by one consumer at a time.
 534     </para>
 535 !Iinclude/linux/pwm.h
 536 !Edrivers/pwm/core.c
 537   </chapter>
 538
 539 </book>