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