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