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_32.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<!-- 74X!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<!-- 97X!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 108X!Edrivers/base/attribute_container.c 109--> 110!Edrivers/base/sys.c 111<!-- 112X!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 122X!Edrivers/acpi/sleep/main.c 123X!Edrivers/acpi/sleep/wakeup.c 124X!Edrivers/acpi/motherboard.c 125X!Edrivers/acpi/bus.c 126--> 127!Edrivers/acpi/scan.c 128!Idrivers/acpi/scan.c 129<!-- No correct structured comments 130X!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 136X!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 208X!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> 264X!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> 274X!Idrivers/video/fbgen.c 275 </sect1> 276KAO --> 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 289X!Idrivers/video/console/fonts.c 290--> 291 </sect1> 292 </chapter> 293 294 <chapter id="input_subsystem"> 295 <title>Input Subsystem</title> 296!Iinclude/linux/input.h 297!Edrivers/input/input.c 298!Edrivers/input/ff-core.c 299!Edrivers/input/ff-memless.c 300 </chapter> 301 302 <chapter id="spi"> 303 <title>Serial Peripheral Interface (SPI)</title> 304 <para> 305 SPI is the "Serial Peripheral Interface", widely used with 306 embedded systems because it is a simple and efficient 307 interface: basically a multiplexed shift register. 308 Its three signal wires hold a clock (SCK, often in the range 309 of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and 310 a "Master In, Slave Out" (MISO) data line. 311 SPI is a full duplex protocol; for each bit shifted out the 312 MOSI line (one per clock) another is shifted in on the MISO line. 313 Those bits are assembled into words of various sizes on the 314 way to and from system memory. 315 An additional chipselect line is usually active-low (nCS); 316 four signals are normally used for each peripheral, plus 317 sometimes an interrupt. 318 </para> 319 <para> 320 The SPI bus facilities listed here provide a generalized 321 interface to declare SPI busses and devices, manage them 322 according to the standard Linux driver model, and perform 323 input/output operations. 324 At this time, only "master" side interfaces are supported, 325 where Linux talks to SPI peripherals and does not implement 326 such a peripheral itself. 327 (Interfaces to support implementing SPI slaves would 328 necessarily look different.) 329 </para> 330 <para> 331 The programming interface is structured around two kinds of driver, 332 and two kinds of device. 333 A "Controller Driver" abstracts the controller hardware, which may 334 be as simple as a set of GPIO pins or as complex as a pair of FIFOs 335 connected to dual DMA engines on the other side of the SPI shift 336 register (maximizing throughput). Such drivers bridge between 337 whatever bus they sit on (often the platform bus) and SPI, and 338 expose the SPI side of their device as a 339 <structname>struct spi_master</structname>. 340 SPI devices are children of that master, represented as a 341 <structname>struct spi_device</structname> and manufactured from 342 <structname>struct spi_board_info</structname> descriptors which 343 are usually provided by board-specific initialization code. 344 A <structname>struct spi_driver</structname> is called a 345 "Protocol Driver", and is bound to a spi_device using normal 346 driver model calls. 347 </para> 348 <para> 349 The I/O model is a set of queued messages. Protocol drivers 350 submit one or more <structname>struct spi_message</structname> 351 objects, which are processed and completed asynchronously. 352 (There are synchronous wrappers, however.) Messages are 353 built from one or more <structname>struct spi_transfer</structname> 354 objects, each of which wraps a full duplex SPI transfer. 355 A variety of protocol tweaking options are needed, because 356 different chips adopt very different policies for how they 357 use the bits transferred with SPI. 358 </para> 359!Iinclude/linux/spi/spi.h 360!Fdrivers/spi/spi.c spi_register_board_info 361!Edrivers/spi/spi.c 362 </chapter> 363 364 <chapter id="i2c"> 365 <title>I<superscript>2</superscript>C and SMBus Subsystem</title> 366 367 <para> 368 I<superscript>2</superscript>C (or without fancy typography, "I2C") 369 is an acronym for the "Inter-IC" bus, a simple bus protocol which is 370 widely used where low data rate communications suffice. 371 Since it's also a licensed trademark, some vendors use another 372 name (such as "Two-Wire Interface", TWI) for the same bus. 373 I2C only needs two signals (SCL for clock, SDA for data), conserving 374 board real estate and minimizing signal quality issues. 375 Most I2C devices use seven bit addresses, and bus speeds of up 376 to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet 377 found wide use. 378 I2C is a multi-master bus; open drain signaling is used to 379 arbitrate between masters, as well as to handshake and to 380 synchronize clocks from slower clients. 381 </para> 382 383 <para> 384 The Linux I2C programming interfaces support only the master 385 side of bus interactions, not the slave side. 386 The programming interface is structured around two kinds of driver, 387 and two kinds of device. 388 An I2C "Adapter Driver" abstracts the controller hardware; it binds 389 to a physical device (perhaps a PCI device or platform_device) and 390 exposes a <structname>struct i2c_adapter</structname> representing 391 each I2C bus segment it manages. 392 On each I2C bus segment will be I2C devices represented by a 393 <structname>struct i2c_client</structname>. Those devices will 394 be bound to a <structname>struct i2c_driver</structname>, 395 which should follow the standard Linux driver model. 396 (At this writing, a legacy model is more widely used.) 397 There are functions to perform various I2C protocol operations; at 398 this writing all such functions are usable only from task context. 399 </para> 400 401 <para> 402 The System Management Bus (SMBus) is a sibling protocol. Most SMBus 403 systems are also I2C conformant. The electrical constraints are 404 tighter for SMBus, and it standardizes particular protocol messages 405 and idioms. Controllers that support I2C can also support most 406 SMBus operations, but SMBus controllers don't support all the protocol 407 options that an I2C controller will. 408 There are functions to perform various SMBus protocol operations, 409 either using I2C primitives or by issuing SMBus commands to 410 i2c_adapter devices which don't support those I2C operations. 411 </para> 412 413!Iinclude/linux/i2c.h 414!Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info 415!Edrivers/i2c/i2c-core.c 416 </chapter> 417 418</book> 419