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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 </sect1>
50
51 <sect1><title>Delaying, scheduling, and timer routines</title>
52!Iinclude/linux/sched.h
Randy Dunlapb4d20852012-01-21 11:03:24 -080053!Ekernel/sched/core.c
54!Ikernel/sched/cpupri.c
55!Ikernel/sched/fair.c
Randy Dunlapee2f1542010-10-26 14:17:25 -070056!Iinclude/linux/completion.h
Randy Dunlapf7f84f32009-02-22 12:15:45 -080057!Ekernel/timer.c
58 </sect1>
Randy Dunlapee2f1542010-10-26 14:17:25 -070059 <sect1><title>Wait queues and Wake events</title>
60!Iinclude/linux/wait.h
61!Ekernel/wait.c
62 </sect1>
Randy Dunlapf7f84f32009-02-22 12:15:45 -080063 <sect1><title>High-resolution timers</title>
64!Iinclude/linux/ktime.h
65!Iinclude/linux/hrtimer.h
66!Ekernel/hrtimer.c
67 </sect1>
68 <sect1><title>Workqueues and Kevents</title>
69!Ekernel/workqueue.c
70 </sect1>
71 <sect1><title>Internal Functions</title>
72!Ikernel/exit.c
73!Ikernel/signal.c
74!Iinclude/linux/kthread.h
75!Ekernel/kthread.c
76 </sect1>
77
78 <sect1><title>Kernel objects manipulation</title>
79<!--
80X!Iinclude/linux/kobject.h
81-->
82!Elib/kobject.c
83 </sect1>
84
85 <sect1><title>Kernel utility functions</title>
86!Iinclude/linux/kernel.h
87!Ekernel/printk.c
88!Ekernel/panic.c
89!Ekernel/sys.c
90!Ekernel/rcupdate.c
91 </sect1>
92
93 <sect1><title>Device Resource Management</title>
94!Edrivers/base/devres.c
95 </sect1>
96
97 </chapter>
98
99 <chapter id="devdrivers">
100 <title>Device drivers infrastructure</title>
Wanlong Gao880ffb52011-05-05 07:55:36 +0800101 <sect1><title>The Basic Device Driver-Model Structures </title>
102!Iinclude/linux/device.h
103 </sect1>
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800104 <sect1><title>Device Drivers Base</title>
Randy Dunlap13405052012-02-01 18:15:49 -0800105!Idrivers/base/init.c
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800106!Edrivers/base/driver.c
107!Edrivers/base/core.c
Randy Dunlap13405052012-02-01 18:15:49 -0800108!Edrivers/base/syscore.c
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800109!Edrivers/base/class.c
Randy Dunlap13405052012-02-01 18:15:49 -0800110!Idrivers/base/node.c
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800111!Edrivers/base/firmware_class.c
112!Edrivers/base/transport_class.c
113<!-- Cannot be included, because
114 attribute_container_add_class_device_adapter
115 and attribute_container_classdev_to_container
116 exceed allowed 44 characters maximum
117X!Edrivers/base/attribute_container.c
118-->
Randy Dunlap13405052012-02-01 18:15:49 -0800119!Edrivers/base/dd.c
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800120<!--
121X!Edrivers/base/interface.c
122-->
Uwe Kleine-König44f28bd2010-06-21 16:11:44 +0200123!Iinclude/linux/platform_device.h
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800124!Edrivers/base/platform.c
125!Edrivers/base/bus.c
126 </sect1>
Randy Dunlap13405052012-02-01 18:15:49 -0800127 <sect1><title>Device Drivers DMA Management</title>
128!Edrivers/base/dma-buf.c
129!Edrivers/base/dma-coherent.c
130!Edrivers/base/dma-mapping.c
131 </sect1>
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800132 <sect1><title>Device Drivers Power Management</title>
133!Edrivers/base/power/main.c
134 </sect1>
135 <sect1><title>Device Drivers ACPI Support</title>
136<!-- Internal functions only
137X!Edrivers/acpi/sleep/main.c
138X!Edrivers/acpi/sleep/wakeup.c
139X!Edrivers/acpi/motherboard.c
140X!Edrivers/acpi/bus.c
141-->
142!Edrivers/acpi/scan.c
143!Idrivers/acpi/scan.c
144<!-- No correct structured comments
145X!Edrivers/acpi/pci_bind.c
146-->
147 </sect1>
148 <sect1><title>Device drivers PnP support</title>
149!Idrivers/pnp/core.c
150<!-- No correct structured comments
151X!Edrivers/pnp/system.c
152 -->
153!Edrivers/pnp/card.c
154!Idrivers/pnp/driver.c
155!Edrivers/pnp/manager.c
156!Edrivers/pnp/support.c
157 </sect1>
158 <sect1><title>Userspace IO devices</title>
159!Edrivers/uio/uio.c
160!Iinclude/linux/uio_driver.h
161 </sect1>
162 </chapter>
163
164 <chapter id="parportdev">
165 <title>Parallel Port Devices</title>
166!Iinclude/linux/parport.h
167!Edrivers/parport/ieee1284.c
168!Edrivers/parport/share.c
169!Idrivers/parport/daisy.c
170 </chapter>
171
172 <chapter id="message_devices">
173 <title>Message-based devices</title>
174 <sect1><title>Fusion message devices</title>
175!Edrivers/message/fusion/mptbase.c
176!Idrivers/message/fusion/mptbase.c
177!Edrivers/message/fusion/mptscsih.c
178!Idrivers/message/fusion/mptscsih.c
179!Idrivers/message/fusion/mptctl.c
180!Idrivers/message/fusion/mptspi.c
181!Idrivers/message/fusion/mptfc.c
182!Idrivers/message/fusion/mptlan.c
183 </sect1>
184 <sect1><title>I2O message devices</title>
185!Iinclude/linux/i2o.h
186!Idrivers/message/i2o/core.h
187!Edrivers/message/i2o/iop.c
188!Idrivers/message/i2o/iop.c
189!Idrivers/message/i2o/config-osm.c
190!Edrivers/message/i2o/exec-osm.c
191!Idrivers/message/i2o/exec-osm.c
192!Idrivers/message/i2o/bus-osm.c
193!Edrivers/message/i2o/device.c
194!Idrivers/message/i2o/device.c
195!Idrivers/message/i2o/driver.c
196!Idrivers/message/i2o/pci.c
197!Idrivers/message/i2o/i2o_block.c
198!Idrivers/message/i2o/i2o_scsi.c
199!Idrivers/message/i2o/i2o_proc.c
200 </sect1>
201 </chapter>
202
203 <chapter id="snddev">
204 <title>Sound Devices</title>
205!Iinclude/sound/core.h
206!Esound/sound_core.c
207!Iinclude/sound/pcm.h
208!Esound/core/pcm.c
209!Esound/core/device.c
210!Esound/core/info.c
211!Esound/core/rawmidi.c
212!Esound/core/sound.c
213!Esound/core/memory.c
214!Esound/core/pcm_memory.c
215!Esound/core/init.c
216!Esound/core/isadma.c
217!Esound/core/control.c
218!Esound/core/pcm_lib.c
219!Esound/core/hwdep.c
220!Esound/core/pcm_native.c
221!Esound/core/memalloc.c
222<!-- FIXME: Removed for now since no structured comments in source
223X!Isound/sound_firmware.c
224-->
225 </chapter>
226
227 <chapter id="uart16x50">
228 <title>16x50 UART Driver</title>
Randy Dunlapfcf28562011-01-22 19:50:03 -0800229!Edrivers/tty/serial/serial_core.c
Randy Dunlap13405052012-02-01 18:15:49 -0800230!Edrivers/tty/serial/8250/8250.c
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800231 </chapter>
232
233 <chapter id="fbdev">
234 <title>Frame Buffer Library</title>
235
236 <para>
237 The frame buffer drivers depend heavily on four data structures.
238 These structures are declared in include/linux/fb.h. They are
239 fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
240 The last three can be made available to and from userland.
241 </para>
242
243 <para>
244 fb_info defines the current state of a particular video card.
245 Inside fb_info, there exists a fb_ops structure which is a
246 collection of needed functions to make fbdev and fbcon work.
247 fb_info is only visible to the kernel.
248 </para>
249
250 <para>
251 fb_var_screeninfo is used to describe the features of a video card
252 that are user defined. With fb_var_screeninfo, things such as
253 depth and the resolution may be defined.
254 </para>
255
256 <para>
257 The next structure is fb_fix_screeninfo. This defines the
258 properties of a card that are created when a mode is set and can't
259 be changed otherwise. A good example of this is the start of the
260 frame buffer memory. This "locks" the address of the frame buffer
261 memory, so that it cannot be changed or moved.
262 </para>
263
264 <para>
265 The last structure is fb_monospecs. In the old API, there was
266 little importance for fb_monospecs. This allowed for forbidden things
267 such as setting a mode of 800x600 on a fix frequency monitor. With
268 the new API, fb_monospecs prevents such things, and if used
269 correctly, can prevent a monitor from being cooked. fb_monospecs
270 will not be useful until kernels 2.5.x.
271 </para>
272
273 <sect1><title>Frame Buffer Memory</title>
274!Edrivers/video/fbmem.c
275 </sect1>
276<!--
277 <sect1><title>Frame Buffer Console</title>
278X!Edrivers/video/console/fbcon.c
279 </sect1>
280-->
281 <sect1><title>Frame Buffer Colormap</title>
282!Edrivers/video/fbcmap.c
283 </sect1>
284<!-- FIXME:
285 drivers/video/fbgen.c has no docs, which stuffs up the sgml. Comment
286 out until somebody adds docs. KAO
287 <sect1><title>Frame Buffer Generic Functions</title>
288X!Idrivers/video/fbgen.c
289 </sect1>
290KAO -->
291 <sect1><title>Frame Buffer Video Mode Database</title>
292!Idrivers/video/modedb.c
293!Edrivers/video/modedb.c
294 </sect1>
295 <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
296!Edrivers/video/macmodes.c
297 </sect1>
298 <sect1><title>Frame Buffer Fonts</title>
299 <para>
300 Refer to the file drivers/video/console/fonts.c for more information.
301 </para>
302<!-- FIXME: Removed for now since no structured comments in source
303X!Idrivers/video/console/fonts.c
304-->
305 </sect1>
306 </chapter>
307
308 <chapter id="input_subsystem">
309 <title>Input Subsystem</title>
Dmitry Torokhovd69249f2009-11-16 22:12:20 -0800310 <sect1><title>Input core</title>
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800311!Iinclude/linux/input.h
312!Edrivers/input/input.c
313!Edrivers/input/ff-core.c
314!Edrivers/input/ff-memless.c
Dmitry Torokhovd69249f2009-11-16 22:12:20 -0800315 </sect1>
Dmitry Torokhov69479f82010-12-09 01:08:26 -0800316 <sect1><title>Multitouch Library</title>
317!Iinclude/linux/input/mt.h
318!Edrivers/input/input-mt.c
319 </sect1>
Dmitry Torokhovd69249f2009-11-16 22:12:20 -0800320 <sect1><title>Polled input devices</title>
321!Iinclude/linux/input-polldev.h
322!Edrivers/input/input-polldev.c
323 </sect1>
324 <sect1><title>Matrix keyboars/keypads</title>
325!Iinclude/linux/input/matrix_keypad.h
326 </sect1>
Dmitry Torokhov36203c42009-12-04 10:22:23 -0800327 <sect1><title>Sparse keymap support</title>
328!Iinclude/linux/input/sparse-keymap.h
329!Edrivers/input/sparse-keymap.c
330 </sect1>
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800331 </chapter>
332
333 <chapter id="spi">
334 <title>Serial Peripheral Interface (SPI)</title>
335 <para>
336 SPI is the "Serial Peripheral Interface", widely used with
337 embedded systems because it is a simple and efficient
338 interface: basically a multiplexed shift register.
339 Its three signal wires hold a clock (SCK, often in the range
340 of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
341 a "Master In, Slave Out" (MISO) data line.
342 SPI is a full duplex protocol; for each bit shifted out the
343 MOSI line (one per clock) another is shifted in on the MISO line.
344 Those bits are assembled into words of various sizes on the
345 way to and from system memory.
346 An additional chipselect line is usually active-low (nCS);
347 four signals are normally used for each peripheral, plus
348 sometimes an interrupt.
349 </para>
350 <para>
351 The SPI bus facilities listed here provide a generalized
352 interface to declare SPI busses and devices, manage them
353 according to the standard Linux driver model, and perform
354 input/output operations.
355 At this time, only "master" side interfaces are supported,
356 where Linux talks to SPI peripherals and does not implement
357 such a peripheral itself.
358 (Interfaces to support implementing SPI slaves would
359 necessarily look different.)
360 </para>
361 <para>
362 The programming interface is structured around two kinds of driver,
363 and two kinds of device.
364 A "Controller Driver" abstracts the controller hardware, which may
365 be as simple as a set of GPIO pins or as complex as a pair of FIFOs
366 connected to dual DMA engines on the other side of the SPI shift
367 register (maximizing throughput). Such drivers bridge between
368 whatever bus they sit on (often the platform bus) and SPI, and
369 expose the SPI side of their device as a
370 <structname>struct spi_master</structname>.
371 SPI devices are children of that master, represented as a
372 <structname>struct spi_device</structname> and manufactured from
373 <structname>struct spi_board_info</structname> descriptors which
374 are usually provided by board-specific initialization code.
375 A <structname>struct spi_driver</structname> is called a
376 "Protocol Driver", and is bound to a spi_device using normal
377 driver model calls.
378 </para>
379 <para>
380 The I/O model is a set of queued messages. Protocol drivers
381 submit one or more <structname>struct spi_message</structname>
382 objects, which are processed and completed asynchronously.
383 (There are synchronous wrappers, however.) Messages are
384 built from one or more <structname>struct spi_transfer</structname>
385 objects, each of which wraps a full duplex SPI transfer.
386 A variety of protocol tweaking options are needed, because
387 different chips adopt very different policies for how they
388 use the bits transferred with SPI.
389 </para>
390!Iinclude/linux/spi/spi.h
391!Fdrivers/spi/spi.c spi_register_board_info
392!Edrivers/spi/spi.c
393 </chapter>
394
395 <chapter id="i2c">
396 <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
397
398 <para>
399 I<superscript>2</superscript>C (or without fancy typography, "I2C")
400 is an acronym for the "Inter-IC" bus, a simple bus protocol which is
401 widely used where low data rate communications suffice.
402 Since it's also a licensed trademark, some vendors use another
403 name (such as "Two-Wire Interface", TWI) for the same bus.
404 I2C only needs two signals (SCL for clock, SDA for data), conserving
405 board real estate and minimizing signal quality issues.
406 Most I2C devices use seven bit addresses, and bus speeds of up
407 to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
408 found wide use.
409 I2C is a multi-master bus; open drain signaling is used to
410 arbitrate between masters, as well as to handshake and to
411 synchronize clocks from slower clients.
412 </para>
413
414 <para>
415 The Linux I2C programming interfaces support only the master
416 side of bus interactions, not the slave side.
417 The programming interface is structured around two kinds of driver,
418 and two kinds of device.
419 An I2C "Adapter Driver" abstracts the controller hardware; it binds
420 to a physical device (perhaps a PCI device or platform_device) and
421 exposes a <structname>struct i2c_adapter</structname> representing
422 each I2C bus segment it manages.
423 On each I2C bus segment will be I2C devices represented by a
424 <structname>struct i2c_client</structname>. Those devices will
425 be bound to a <structname>struct i2c_driver</structname>,
426 which should follow the standard Linux driver model.
427 (At this writing, a legacy model is more widely used.)
428 There are functions to perform various I2C protocol operations; at
429 this writing all such functions are usable only from task context.
430 </para>
431
432 <para>
433 The System Management Bus (SMBus) is a sibling protocol. Most SMBus
434 systems are also I2C conformant. The electrical constraints are
435 tighter for SMBus, and it standardizes particular protocol messages
436 and idioms. Controllers that support I2C can also support most
437 SMBus operations, but SMBus controllers don't support all the protocol
438 options that an I2C controller will.
439 There are functions to perform various SMBus protocol operations,
440 either using I2C primitives or by issuing SMBus commands to
441 i2c_adapter devices which don't support those I2C operations.
442 </para>
443
444!Iinclude/linux/i2c.h
445!Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
446!Edrivers/i2c/i2c-core.c
447 </chapter>
448
Carlos Chineaa4ac73a2010-04-29 13:19:06 +0300449 <chapter id="hsi">
450 <title>High Speed Synchronous Serial Interface (HSI)</title>
451
452 <para>
453 High Speed Synchronous Serial Interface (HSI) is a
454 serial interface mainly used for connecting application
455 engines (APE) with cellular modem engines (CMT) in cellular
456 handsets.
457
458 HSI provides multiplexing for up to 16 logical channels,
459 low-latency and full duplex communication.
460 </para>
461
462!Iinclude/linux/hsi/hsi.h
463!Edrivers/hsi/hsi.c
464 </chapter>
465
Randy Dunlapf7f84f32009-02-22 12:15:45 -0800466</book>