1<?xml version="1.0" encoding="UTF-8"?> 2<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" 3 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> 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<!-- 78X!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<!-- 101X!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 112X!Edrivers/base/attribute_container.c 113--> 114!Edrivers/base/sys.c 115<!-- 116X!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 127X!Edrivers/acpi/sleep/main.c 128X!Edrivers/acpi/sleep/wakeup.c 129X!Edrivers/acpi/motherboard.c 130X!Edrivers/acpi/bus.c 131--> 132!Edrivers/acpi/scan.c 133!Idrivers/acpi/scan.c 134<!-- No correct structured comments 135X!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 141X!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 213X!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/serial/serial_core.c 221!Edrivers/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> 269X!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> 279X!Idrivers/video/fbgen.c 280 </sect1> 281KAO --> 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 294X!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>Polled input devices</title> 308!Iinclude/linux/input-polldev.h 309!Edrivers/input/input-polldev.c 310 </sect1> 311 <sect1><title>Matrix keyboars/keypads</title> 312!Iinclude/linux/input/matrix_keypad.h 313 </sect1> 314 <sect1><title>Sparse keymap support</title> 315!Iinclude/linux/input/sparse-keymap.h 316!Edrivers/input/sparse-keymap.c 317 </sect1> 318 </chapter> 319 320 <chapter id="spi"> 321 <title>Serial Peripheral Interface (SPI)</title> 322 <para> 323 SPI is the "Serial Peripheral Interface", widely used with 324 embedded systems because it is a simple and efficient 325 interface: basically a multiplexed shift register. 326 Its three signal wires hold a clock (SCK, often in the range 327 of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and 328 a "Master In, Slave Out" (MISO) data line. 329 SPI is a full duplex protocol; for each bit shifted out the 330 MOSI line (one per clock) another is shifted in on the MISO line. 331 Those bits are assembled into words of various sizes on the 332 way to and from system memory. 333 An additional chipselect line is usually active-low (nCS); 334 four signals are normally used for each peripheral, plus 335 sometimes an interrupt. 336 </para> 337 <para> 338 The SPI bus facilities listed here provide a generalized 339 interface to declare SPI busses and devices, manage them 340 according to the standard Linux driver model, and perform 341 input/output operations. 342 At this time, only "master" side interfaces are supported, 343 where Linux talks to SPI peripherals and does not implement 344 such a peripheral itself. 345 (Interfaces to support implementing SPI slaves would 346 necessarily look different.) 347 </para> 348 <para> 349 The programming interface is structured around two kinds of driver, 350 and two kinds of device. 351 A "Controller Driver" abstracts the controller hardware, which may 352 be as simple as a set of GPIO pins or as complex as a pair of FIFOs 353 connected to dual DMA engines on the other side of the SPI shift 354 register (maximizing throughput). Such drivers bridge between 355 whatever bus they sit on (often the platform bus) and SPI, and 356 expose the SPI side of their device as a 357 <structname>struct spi_master</structname>. 358 SPI devices are children of that master, represented as a 359 <structname>struct spi_device</structname> and manufactured from 360 <structname>struct spi_board_info</structname> descriptors which 361 are usually provided by board-specific initialization code. 362 A <structname>struct spi_driver</structname> is called a 363 "Protocol Driver", and is bound to a spi_device using normal 364 driver model calls. 365 </para> 366 <para> 367 The I/O model is a set of queued messages. Protocol drivers 368 submit one or more <structname>struct spi_message</structname> 369 objects, which are processed and completed asynchronously. 370 (There are synchronous wrappers, however.) Messages are 371 built from one or more <structname>struct spi_transfer</structname> 372 objects, each of which wraps a full duplex SPI transfer. 373 A variety of protocol tweaking options are needed, because 374 different chips adopt very different policies for how they 375 use the bits transferred with SPI. 376 </para> 377!Iinclude/linux/spi/spi.h 378!Fdrivers/spi/spi.c spi_register_board_info 379!Edrivers/spi/spi.c 380 </chapter> 381 382 <chapter id="i2c"> 383 <title>I<superscript>2</superscript>C and SMBus Subsystem</title> 384 385 <para> 386 I<superscript>2</superscript>C (or without fancy typography, "I2C") 387 is an acronym for the "Inter-IC" bus, a simple bus protocol which is 388 widely used where low data rate communications suffice. 389 Since it's also a licensed trademark, some vendors use another 390 name (such as "Two-Wire Interface", TWI) for the same bus. 391 I2C only needs two signals (SCL for clock, SDA for data), conserving 392 board real estate and minimizing signal quality issues. 393 Most I2C devices use seven bit addresses, and bus speeds of up 394 to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet 395 found wide use. 396 I2C is a multi-master bus; open drain signaling is used to 397 arbitrate between masters, as well as to handshake and to 398 synchronize clocks from slower clients. 399 </para> 400 401 <para> 402 The Linux I2C programming interfaces support only the master 403 side of bus interactions, not the slave side. 404 The programming interface is structured around two kinds of driver, 405 and two kinds of device. 406 An I2C "Adapter Driver" abstracts the controller hardware; it binds 407 to a physical device (perhaps a PCI device or platform_device) and 408 exposes a <structname>struct i2c_adapter</structname> representing 409 each I2C bus segment it manages. 410 On each I2C bus segment will be I2C devices represented by a 411 <structname>struct i2c_client</structname>. Those devices will 412 be bound to a <structname>struct i2c_driver</structname>, 413 which should follow the standard Linux driver model. 414 (At this writing, a legacy model is more widely used.) 415 There are functions to perform various I2C protocol operations; at 416 this writing all such functions are usable only from task context. 417 </para> 418 419 <para> 420 The System Management Bus (SMBus) is a sibling protocol. Most SMBus 421 systems are also I2C conformant. The electrical constraints are 422 tighter for SMBus, and it standardizes particular protocol messages 423 and idioms. Controllers that support I2C can also support most 424 SMBus operations, but SMBus controllers don't support all the protocol 425 options that an I2C controller will. 426 There are functions to perform various SMBus protocol operations, 427 either using I2C primitives or by issuing SMBus commands to 428 i2c_adapter devices which don't support those I2C operations. 429 </para> 430 431!Iinclude/linux/i2c.h 432!Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info 433!Edrivers/i2c/i2c-core.c 434 </chapter> 435 436</book> 437