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-mc.h
 233 !Iinclude/media/v4l2-mediabus.h
 234 !Iinclude/media/v4l2-mem2mem.h
 235 !Iinclude/media/v4l2-of.h
 236 !Iinclude/media/v4l2-subdev.h
 237 !Iinclude/media/videobuf2-core.h
 238 !Iinclude/media/videobuf2-v4l2.h
 239 !Iinclude/media/videobuf2-memops.h
 240      </sect1>
 241      <sect1><title>Digital TV (DVB) devices</title>
 242         <sect1><title>Digital TV Common functions</title>
 243 !Idrivers/media/dvb-core/dvb_math.h
 244 !Idrivers/media/dvb-core/dvb_ringbuffer.h
 245 !Idrivers/media/dvb-core/dvbdev.h
 246         </sect1>
 247         <sect1><title>Digital TV Frontend kABI</title>
 248 !Pdrivers/media/dvb-core/dvb_frontend.h Digital TV Frontend
 249 !Idrivers/media/dvb-core/dvb_frontend.h
 250         </sect1>
 251         <sect1><title>Digital TV Demux kABI</title>
 252 !Pdrivers/media/dvb-core/demux.h Digital TV Demux
 253         <sect1><title>Demux Callback API</title>
 254 !Pdrivers/media/dvb-core/demux.h Demux Callback
 255         </sect1>
 256 !Idrivers/media/dvb-core/demux.h
 257         </sect1>
 258         <sect1><title>Digital TV Conditional Access kABI</title>
 259 !Idrivers/media/dvb-core/dvb_ca_en50221.h
 260         </sect1>
 261      </sect1>
 262     <sect1><title>Remote Controller devices</title>
 263 !Iinclude/media/rc-core.h
 264 !Iinclude/media/lirc_dev.h
 265     </sect1>
 266     <sect1><title>Media Controller devices</title>
 267 !Pinclude/media/media-device.h Media Controller
 268 !Iinclude/media/media-device.h
 269 !Iinclude/media/media-devnode.h
 270 !Iinclude/media/media-entity.h
 271     </sect1>
 272
 273   </chapter>
 274
 275   <chapter id="uart16x50">
 276      <title>16x50 UART Driver</title>
 277 !Edrivers/tty/serial/serial_core.c
 278 !Edrivers/tty/serial/8250/8250_core.c
 279   </chapter>
 280
 281   <chapter id="fbdev">
 282      <title>Frame Buffer Library</title>
 283
 284      <para>
 285        The frame buffer drivers depend heavily on four data structures.
 286        These structures are declared in include/linux/fb.h.  They are
 287        fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
 288        The last three can be made available to and from userland.
 289      </para>
 290
 291      <para>
 292        fb_info defines the current state of a particular video card.
 293        Inside fb_info, there exists a fb_ops structure which is a
 294        collection of needed functions to make fbdev and fbcon work.
 295        fb_info is only visible to the kernel.
 296      </para>
 297
 298      <para>
 299        fb_var_screeninfo is used to describe the features of a video card
 300        that are user defined.  With fb_var_screeninfo, things such as
 301        depth and the resolution may be defined.
 302      </para>
 303
 304      <para>
 305        The next structure is fb_fix_screeninfo. This defines the
 306        properties of a card that are created when a mode is set and can't
 307        be changed otherwise.  A good example of this is the start of the
 308        frame buffer memory.  This "locks" the address of the frame buffer
 309        memory, so that it cannot be changed or moved.
 310      </para>
 311
 312      <para>
 313        The last structure is fb_monospecs. In the old API, there was
 314        little importance for fb_monospecs. This allowed for forbidden things
 315        such as setting a mode of 800x600 on a fix frequency monitor. With
 316        the new API, fb_monospecs prevents such things, and if used
 317        correctly, can prevent a monitor from being cooked.  fb_monospecs
 318        will not be useful until kernels 2.5.x.
 319      </para>
 320
 321      <sect1><title>Frame Buffer Memory</title>
 322 !Edrivers/video/fbdev/core/fbmem.c
 323      </sect1>
 324 <!--
 325      <sect1><title>Frame Buffer Console</title>
 326 X!Edrivers/video/console/fbcon.c
 327      </sect1>
 328 -->
 329      <sect1><title>Frame Buffer Colormap</title>
 330 !Edrivers/video/fbdev/core/fbcmap.c
 331      </sect1>
 332 <!-- FIXME:
 333   drivers/video/fbgen.c has no docs, which stuffs up the sgml.  Comment
 334   out until somebody adds docs.  KAO
 335      <sect1><title>Frame Buffer Generic Functions</title>
 336 X!Idrivers/video/fbgen.c
 337      </sect1>
 338 KAO -->
 339      <sect1><title>Frame Buffer Video Mode Database</title>
 340 !Idrivers/video/fbdev/core/modedb.c
 341 !Edrivers/video/fbdev/core/modedb.c
 342      </sect1>
 343      <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
 344 !Edrivers/video/fbdev/macmodes.c
 345      </sect1>
 346      <sect1><title>Frame Buffer Fonts</title>
 347         <para>
 348            Refer to the file lib/fonts/fonts.c for more information.
 349         </para>
 350 <!-- FIXME: Removed for now since no structured comments in source
 351 X!Ilib/fonts/fonts.c
 352 -->
 353      </sect1>
 354   </chapter>
 355
 356   <chapter id="input_subsystem">
 357      <title>Input Subsystem</title>
 358      <sect1><title>Input core</title>
 359 !Iinclude/linux/input.h
 360 !Edrivers/input/input.c
 361 !Edrivers/input/ff-core.c
 362 !Edrivers/input/ff-memless.c
 363      </sect1>
 364      <sect1><title>Multitouch Library</title>
 365 !Iinclude/linux/input/mt.h
 366 !Edrivers/input/input-mt.c
 367      </sect1>
 368      <sect1><title>Polled input devices</title>
 369 !Iinclude/linux/input-polldev.h
 370 !Edrivers/input/input-polldev.c
 371      </sect1>
 372      <sect1><title>Matrix keyboards/keypads</title>
 373 !Iinclude/linux/input/matrix_keypad.h
 374      </sect1>
 375      <sect1><title>Sparse keymap support</title>
 376 !Iinclude/linux/input/sparse-keymap.h
 377 !Edrivers/input/sparse-keymap.c
 378      </sect1>
 379   </chapter>
 380
 381   <chapter id="spi">
 382       <title>Serial Peripheral Interface (SPI)</title>
 383   <para>
 384         SPI is the "Serial Peripheral Interface", widely used with
 385         embedded systems because it is a simple and efficient
 386         interface:  basically a multiplexed shift register.
 387         Its three signal wires hold a clock (SCK, often in the range
 388         of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
 389         a "Master In, Slave Out" (MISO) data line.
 390         SPI is a full duplex protocol; for each bit shifted out the
 391         MOSI line (one per clock) another is shifted in on the MISO line.
 392         Those bits are assembled into words of various sizes on the
 393         way to and from system memory.
 394         An additional chipselect line is usually active-low (nCS);
 395         four signals are normally used for each peripheral, plus
 396         sometimes an interrupt.
 397   </para>
 398   <para>
 399         The SPI bus facilities listed here provide a generalized
 400         interface to declare SPI busses and devices, manage them
 401         according to the standard Linux driver model, and perform
 402         input/output operations.
 403         At this time, only "master" side interfaces are supported,
 404         where Linux talks to SPI peripherals and does not implement
 405         such a peripheral itself.
 406         (Interfaces to support implementing SPI slaves would
 407         necessarily look different.)
 408   </para>
 409   <para>
 410         The programming interface is structured around two kinds of driver,
 411         and two kinds of device.
 412         A "Controller Driver" abstracts the controller hardware, which may
 413         be as simple as a set of GPIO pins or as complex as a pair of FIFOs
 414         connected to dual DMA engines on the other side of the SPI shift
 415         register (maximizing throughput).  Such drivers bridge between
 416         whatever bus they sit on (often the platform bus) and SPI, and
 417         expose the SPI side of their device as a
 418         <structname>struct spi_master</structname>.
 419         SPI devices are children of that master, represented as a
 420         <structname>struct spi_device</structname> and manufactured from
 421         <structname>struct spi_board_info</structname> descriptors which
 422         are usually provided by board-specific initialization code.
 423         A <structname>struct spi_driver</structname> is called a
 424         "Protocol Driver", and is bound to a spi_device using normal
 425         driver model calls.
 426   </para>
 427   <para>
 428         The I/O model is a set of queued messages.  Protocol drivers
 429         submit one or more <structname>struct spi_message</structname>
 430         objects, which are processed and completed asynchronously.
 431         (There are synchronous wrappers, however.)  Messages are
 432         built from one or more <structname>struct spi_transfer</structname>
 433         objects, each of which wraps a full duplex SPI transfer.
 434         A variety of protocol tweaking options are needed, because
 435         different chips adopt very different policies for how they
 436         use the bits transferred with SPI.
 437   </para>
 438 !Iinclude/linux/spi/spi.h
 439 !Fdrivers/spi/spi.c spi_register_board_info
 440 !Edrivers/spi/spi.c
 441   </chapter>
 442
 443   <chapter id="i2c">
 444      <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
 445
 446      <para>
 447         I<superscript>2</superscript>C (or without fancy typography, "I2C")
 448         is an acronym for the "Inter-IC" bus, a simple bus protocol which is
 449         widely used where low data rate communications suffice.
 450         Since it's also a licensed trademark, some vendors use another
 451         name (such as "Two-Wire Interface", TWI) for the same bus.
 452         I2C only needs two signals (SCL for clock, SDA for data), conserving
 453         board real estate and minimizing signal quality issues.
 454         Most I2C devices use seven bit addresses, and bus speeds of up
 455         to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
 456         found wide use.
 457         I2C is a multi-master bus; open drain signaling is used to
 458         arbitrate between masters, as well as to handshake and to
 459         synchronize clocks from slower clients.
 460      </para>
 461
 462      <para>
 463         The Linux I2C programming interfaces support only the master
 464         side of bus interactions, not the slave side.
 465         The programming interface is structured around two kinds of driver,
 466         and two kinds of device.
 467         An I2C "Adapter Driver" abstracts the controller hardware; it binds
 468         to a physical device (perhaps a PCI device or platform_device) and
 469         exposes a <structname>struct i2c_adapter</structname> representing
 470         each I2C bus segment it manages.
 471         On each I2C bus segment will be I2C devices represented by a
 472         <structname>struct i2c_client</structname>.  Those devices will
 473         be bound to a <structname>struct i2c_driver</structname>,
 474         which should follow the standard Linux driver model.
 475         (At this writing, a legacy model is more widely used.)
 476         There are functions to perform various I2C protocol operations; at
 477         this writing all such functions are usable only from task context.
 478      </para>
 479
 480      <para>
 481         The System Management Bus (SMBus) is a sibling protocol.  Most SMBus
 482         systems are also I2C conformant.  The electrical constraints are
 483         tighter for SMBus, and it standardizes particular protocol messages
 484         and idioms.  Controllers that support I2C can also support most
 485         SMBus operations, but SMBus controllers don't support all the protocol
 486         options that an I2C controller will.
 487         There are functions to perform various SMBus protocol operations,
 488         either using I2C primitives or by issuing SMBus commands to
 489         i2c_adapter devices which don't support those I2C operations.
 490      </para>
 491
 492 !Iinclude/linux/i2c.h
 493 !Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
 494 !Edrivers/i2c/i2c-core.c
 495   </chapter>
 496
 497   <chapter id="hsi">
 498      <title>High Speed Synchronous Serial Interface (HSI)</title>
 499
 500      <para>
 501         High Speed Synchronous Serial Interface (HSI) is a
 502         serial interface mainly used for connecting application
 503         engines (APE) with cellular modem engines (CMT) in cellular
 504         handsets.
 505
 506         HSI provides multiplexing for up to 16 logical channels,
 507         low-latency and full duplex communication.
 508      </para>
 509
 510 !Iinclude/linux/hsi/hsi.h
 511 !Edrivers/hsi/hsi.c
 512   </chapter>
 513
 514   <chapter id="pwm">
 515     <title>Pulse-Width Modulation (PWM)</title>
 516     <para>
 517       Pulse-width modulation is a modulation technique primarily used to
 518       control power supplied to electrical devices.
 519     </para>
 520     <para>
 521       The PWM framework provides an abstraction for providers and consumers
 522       of PWM signals. A controller that provides one or more PWM signals is
 523       registered as <structname>struct pwm_chip</structname>. Providers are
 524       expected to embed this structure in a driver-specific structure. This
 525       structure contains fields that describe a particular chip.
 526     </para>
 527     <para>
 528       A chip exposes one or more PWM signal sources, each of which exposed
 529       as a <structname>struct pwm_device</structname>. Operations can be
 530       performed on PWM devices to control the period, duty cycle, polarity
 531       and active state of the signal.
 532     </para>
 533     <para>
 534       Note that PWM devices are exclusive resources: they can always only be
 535       used by one consumer at a time.
 536     </para>
 537 !Iinclude/linux/pwm.h
 538 !Edrivers/pwm/core.c
 539   </chapter>
 540
 541 </book>