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Randy Dunlapf7f84f32009-02-22 12:15:45 -08001<?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>
Randy Dunlap88b68032010-03-01 22:06:25 -080048!Iarch/x86/include/asm/atomic.h
Randy Dunlapf7f84f32009-02-22 12:15:45 -080049!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>
Dmitry Torokhovd69249f2009-11-16 22:12:20 -0800296 <sect1><title>Input core</title>
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800297!Iinclude/linux/input.h
298!Edrivers/input/input.c
299!Edrivers/input/ff-core.c
300!Edrivers/input/ff-memless.c
Dmitry Torokhovd69249f2009-11-16 22:12:20 -0800301 </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>
Dmitry Torokhov36203c42009-12-04 10:22:23 -0800309 <sect1><title>Sparse keymap support</title>
310!Iinclude/linux/input/sparse-keymap.h
311!Edrivers/input/sparse-keymap.c
312 </sect1>
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800313 </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>