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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/core.c
54!Ikernel/sched/cpupri.c
55!Ikernel/sched/fair.c
56!Iinclude/linux/completion.h
57!Ekernel/timer.c
58 </sect1>
59 <sect1><title>Wait queues and Wake events</title>
60!Iinclude/linux/wait.h
61!Ekernel/sched/wait.c
62 </sect1>
63 <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/printk.c
88!Ekernel/panic.c
89!Ekernel/sys.c
90!Ekernel/rcu/srcu.c
91!Ekernel/rcu/tree.c
92!Ekernel/rcu/tree_plugin.h
93!Ekernel/rcu/update.c
94 </sect1>
95
96 <sect1><title>Device Resource Management</title>
97!Edrivers/base/devres.c
98 </sect1>
99
100 </chapter>
101
102 <chapter id="devdrivers">
103 <title>Device drivers infrastructure</title>
104 <sect1><title>The Basic Device Driver-Model Structures </title>
105!Iinclude/linux/device.h
106 </sect1>
107 <sect1><title>Device Drivers Base</title>
108!Idrivers/base/init.c
109!Edrivers/base/driver.c
110!Edrivers/base/core.c
111!Edrivers/base/syscore.c
112!Edrivers/base/class.c
113!Idrivers/base/node.c
114!Edrivers/base/firmware_class.c
115!Edrivers/base/transport_class.c
116<!-- Cannot be included, because
117 attribute_container_add_class_device_adapter
118 and attribute_container_classdev_to_container
119 exceed allowed 44 characters maximum
120X!Edrivers/base/attribute_container.c
121-->
122!Edrivers/base/dd.c
123<!--
124X!Edrivers/base/interface.c
125-->
126!Iinclude/linux/platform_device.h
127!Edrivers/base/platform.c
128!Edrivers/base/bus.c
129 </sect1>
130 <sect1><title>Device Drivers DMA Management</title>
131!Edrivers/base/dma-buf.c
132!Edrivers/base/reservation.c
133!Iinclude/linux/reservation.h
134!Edrivers/base/dma-coherent.c
135!Edrivers/base/dma-mapping.c
136 </sect1>
137 <sect1><title>Device Drivers Power Management</title>
138!Edrivers/base/power/main.c
139 </sect1>
140 <sect1><title>Device Drivers ACPI Support</title>
141<!-- Internal functions only
142X!Edrivers/acpi/sleep/main.c
143X!Edrivers/acpi/sleep/wakeup.c
144X!Edrivers/acpi/motherboard.c
145X!Edrivers/acpi/bus.c
146-->
147!Edrivers/acpi/scan.c
148!Idrivers/acpi/scan.c
149<!-- No correct structured comments
150X!Edrivers/acpi/pci_bind.c
151-->
152 </sect1>
153 <sect1><title>Device drivers PnP support</title>
154!Idrivers/pnp/core.c
155<!-- No correct structured comments
156X!Edrivers/pnp/system.c
157 -->
158!Edrivers/pnp/card.c
159!Idrivers/pnp/driver.c
160!Edrivers/pnp/manager.c
161!Edrivers/pnp/support.c
162 </sect1>
163 <sect1><title>Userspace IO devices</title>
164!Edrivers/uio/uio.c
165!Iinclude/linux/uio_driver.h
166 </sect1>
167 </chapter>
168
169 <chapter id="parportdev">
170 <title>Parallel Port Devices</title>
171!Iinclude/linux/parport.h
172!Edrivers/parport/ieee1284.c
173!Edrivers/parport/share.c
174!Idrivers/parport/daisy.c
175 </chapter>
176
177 <chapter id="message_devices">
178 <title>Message-based devices</title>
179 <sect1><title>Fusion message devices</title>
180!Edrivers/message/fusion/mptbase.c
181!Idrivers/message/fusion/mptbase.c
182!Edrivers/message/fusion/mptscsih.c
183!Idrivers/message/fusion/mptscsih.c
184!Idrivers/message/fusion/mptctl.c
185!Idrivers/message/fusion/mptspi.c
186!Idrivers/message/fusion/mptfc.c
187!Idrivers/message/fusion/mptlan.c
188 </sect1>
189 <sect1><title>I2O message devices</title>
190!Iinclude/linux/i2o.h
191!Idrivers/message/i2o/core.h
192!Edrivers/message/i2o/iop.c
193!Idrivers/message/i2o/iop.c
194!Idrivers/message/i2o/config-osm.c
195!Edrivers/message/i2o/exec-osm.c
196!Idrivers/message/i2o/exec-osm.c
197!Idrivers/message/i2o/bus-osm.c
198!Edrivers/message/i2o/device.c
199!Idrivers/message/i2o/device.c
200!Idrivers/message/i2o/driver.c
201!Idrivers/message/i2o/pci.c
202!Idrivers/message/i2o/i2o_block.c
203!Idrivers/message/i2o/i2o_scsi.c
204!Idrivers/message/i2o/i2o_proc.c
205 </sect1>
206 </chapter>
207
208 <chapter id="snddev">
209 <title>Sound Devices</title>
210!Iinclude/sound/core.h
211!Esound/sound_core.c
212!Iinclude/sound/pcm.h
213!Esound/core/pcm.c
214!Esound/core/device.c
215!Esound/core/info.c
216!Esound/core/rawmidi.c
217!Esound/core/sound.c
218!Esound/core/memory.c
219!Esound/core/pcm_memory.c
220!Esound/core/init.c
221!Esound/core/isadma.c
222!Esound/core/control.c
223!Esound/core/pcm_lib.c
224!Esound/core/hwdep.c
225!Esound/core/pcm_native.c
226!Esound/core/memalloc.c
227<!-- FIXME: Removed for now since no structured comments in source
228X!Isound/sound_firmware.c
229-->
230 </chapter>
231
232 <chapter id="uart16x50">
233 <title>16x50 UART Driver</title>
234!Edrivers/tty/serial/serial_core.c
235!Edrivers/tty/serial/8250/8250_core.c
236 </chapter>
237
238 <chapter id="fbdev">
239 <title>Frame Buffer Library</title>
240
241 <para>
242 The frame buffer drivers depend heavily on four data structures.
243 These structures are declared in include/linux/fb.h. They are
244 fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
245 The last three can be made available to and from userland.
246 </para>
247
248 <para>
249 fb_info defines the current state of a particular video card.
250 Inside fb_info, there exists a fb_ops structure which is a
251 collection of needed functions to make fbdev and fbcon work.
252 fb_info is only visible to the kernel.
253 </para>
254
255 <para>
256 fb_var_screeninfo is used to describe the features of a video card
257 that are user defined. With fb_var_screeninfo, things such as
258 depth and the resolution may be defined.
259 </para>
260
261 <para>
262 The next structure is fb_fix_screeninfo. This defines the
263 properties of a card that are created when a mode is set and can't
264 be changed otherwise. A good example of this is the start of the
265 frame buffer memory. This "locks" the address of the frame buffer
266 memory, so that it cannot be changed or moved.
267 </para>
268
269 <para>
270 The last structure is fb_monospecs. In the old API, there was
271 little importance for fb_monospecs. This allowed for forbidden things
272 such as setting a mode of 800x600 on a fix frequency monitor. With
273 the new API, fb_monospecs prevents such things, and if used
274 correctly, can prevent a monitor from being cooked. fb_monospecs
275 will not be useful until kernels 2.5.x.
276 </para>
277
278 <sect1><title>Frame Buffer Memory</title>
279!Edrivers/video/fbmem.c
280 </sect1>
281<!--
282 <sect1><title>Frame Buffer Console</title>
283X!Edrivers/video/console/fbcon.c
284 </sect1>
285-->
286 <sect1><title>Frame Buffer Colormap</title>
287!Edrivers/video/fbcmap.c
288 </sect1>
289<!-- FIXME:
290 drivers/video/fbgen.c has no docs, which stuffs up the sgml. Comment
291 out until somebody adds docs. KAO
292 <sect1><title>Frame Buffer Generic Functions</title>
293X!Idrivers/video/fbgen.c
294 </sect1>
295KAO -->
296 <sect1><title>Frame Buffer Video Mode Database</title>
297!Idrivers/video/modedb.c
298!Edrivers/video/modedb.c
299 </sect1>
300 <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
301!Edrivers/video/macmodes.c
302 </sect1>
303 <sect1><title>Frame Buffer Fonts</title>
304 <para>
305 Refer to the file lib/fonts/fonts.c for more information.
306 </para>
307<!-- FIXME: Removed for now since no structured comments in source
308X!Ilib/fonts/fonts.c
309-->
310 </sect1>
311 </chapter>
312
313 <chapter id="input_subsystem">
314 <title>Input Subsystem</title>
315 <sect1><title>Input core</title>
316!Iinclude/linux/input.h
317!Edrivers/input/input.c
318!Edrivers/input/ff-core.c
319!Edrivers/input/ff-memless.c
320 </sect1>
321 <sect1><title>Multitouch Library</title>
322!Iinclude/linux/input/mt.h
323!Edrivers/input/input-mt.c
324 </sect1>
325 <sect1><title>Polled input devices</title>
326!Iinclude/linux/input-polldev.h
327!Edrivers/input/input-polldev.c
328 </sect1>
329 <sect1><title>Matrix keyboars/keypads</title>
330!Iinclude/linux/input/matrix_keypad.h
331 </sect1>
332 <sect1><title>Sparse keymap support</title>
333!Iinclude/linux/input/sparse-keymap.h
334!Edrivers/input/sparse-keymap.c
335 </sect1>
336 </chapter>
337
338 <chapter id="spi">
339 <title>Serial Peripheral Interface (SPI)</title>
340 <para>
341 SPI is the "Serial Peripheral Interface", widely used with
342 embedded systems because it is a simple and efficient
343 interface: basically a multiplexed shift register.
344 Its three signal wires hold a clock (SCK, often in the range
345 of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
346 a "Master In, Slave Out" (MISO) data line.
347 SPI is a full duplex protocol; for each bit shifted out the
348 MOSI line (one per clock) another is shifted in on the MISO line.
349 Those bits are assembled into words of various sizes on the
350 way to and from system memory.
351 An additional chipselect line is usually active-low (nCS);
352 four signals are normally used for each peripheral, plus
353 sometimes an interrupt.
354 </para>
355 <para>
356 The SPI bus facilities listed here provide a generalized
357 interface to declare SPI busses and devices, manage them
358 according to the standard Linux driver model, and perform
359 input/output operations.
360 At this time, only "master" side interfaces are supported,
361 where Linux talks to SPI peripherals and does not implement
362 such a peripheral itself.
363 (Interfaces to support implementing SPI slaves would
364 necessarily look different.)
365 </para>
366 <para>
367 The programming interface is structured around two kinds of driver,
368 and two kinds of device.
369 A "Controller Driver" abstracts the controller hardware, which may
370 be as simple as a set of GPIO pins or as complex as a pair of FIFOs
371 connected to dual DMA engines on the other side of the SPI shift
372 register (maximizing throughput). Such drivers bridge between
373 whatever bus they sit on (often the platform bus) and SPI, and
374 expose the SPI side of their device as a
375 <structname>struct spi_master</structname>.
376 SPI devices are children of that master, represented as a
377 <structname>struct spi_device</structname> and manufactured from
378 <structname>struct spi_board_info</structname> descriptors which
379 are usually provided by board-specific initialization code.
380 A <structname>struct spi_driver</structname> is called a
381 "Protocol Driver", and is bound to a spi_device using normal
382 driver model calls.
383 </para>
384 <para>
385 The I/O model is a set of queued messages. Protocol drivers
386 submit one or more <structname>struct spi_message</structname>
387 objects, which are processed and completed asynchronously.
388 (There are synchronous wrappers, however.) Messages are
389 built from one or more <structname>struct spi_transfer</structname>
390 objects, each of which wraps a full duplex SPI transfer.
391 A variety of protocol tweaking options are needed, because
392 different chips adopt very different policies for how they
393 use the bits transferred with SPI.
394 </para>
395!Iinclude/linux/spi/spi.h
396!Fdrivers/spi/spi.c spi_register_board_info
397!Edrivers/spi/spi.c
398 </chapter>
399
400 <chapter id="i2c">
401 <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
402
403 <para>
404 I<superscript>2</superscript>C (or without fancy typography, "I2C")
405 is an acronym for the "Inter-IC" bus, a simple bus protocol which is
406 widely used where low data rate communications suffice.
407 Since it's also a licensed trademark, some vendors use another
408 name (such as "Two-Wire Interface", TWI) for the same bus.
409 I2C only needs two signals (SCL for clock, SDA for data), conserving
410 board real estate and minimizing signal quality issues.
411 Most I2C devices use seven bit addresses, and bus speeds of up
412 to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
413 found wide use.
414 I2C is a multi-master bus; open drain signaling is used to
415 arbitrate between masters, as well as to handshake and to
416 synchronize clocks from slower clients.
417 </para>
418
419 <para>
420 The Linux I2C programming interfaces support only the master
421 side of bus interactions, not the slave side.
422 The programming interface is structured around two kinds of driver,
423 and two kinds of device.
424 An I2C "Adapter Driver" abstracts the controller hardware; it binds
425 to a physical device (perhaps a PCI device or platform_device) and
426 exposes a <structname>struct i2c_adapter</structname> representing
427 each I2C bus segment it manages.
428 On each I2C bus segment will be I2C devices represented by a
429 <structname>struct i2c_client</structname>. Those devices will
430 be bound to a <structname>struct i2c_driver</structname>,
431 which should follow the standard Linux driver model.
432 (At this writing, a legacy model is more widely used.)
433 There are functions to perform various I2C protocol operations; at
434 this writing all such functions are usable only from task context.
435 </para>
436
437 <para>
438 The System Management Bus (SMBus) is a sibling protocol. Most SMBus
439 systems are also I2C conformant. The electrical constraints are
440 tighter for SMBus, and it standardizes particular protocol messages
441 and idioms. Controllers that support I2C can also support most
442 SMBus operations, but SMBus controllers don't support all the protocol
443 options that an I2C controller will.
444 There are functions to perform various SMBus protocol operations,
445 either using I2C primitives or by issuing SMBus commands to
446 i2c_adapter devices which don't support those I2C operations.
447 </para>
448
449!Iinclude/linux/i2c.h
450!Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
451!Edrivers/i2c/i2c-core.c
452 </chapter>
453
454 <chapter id="hsi">
455 <title>High Speed Synchronous Serial Interface (HSI)</title>
456
457 <para>
458 High Speed Synchronous Serial Interface (HSI) is a
459 serial interface mainly used for connecting application
460 engines (APE) with cellular modem engines (CMT) in cellular
461 handsets.
462
463 HSI provides multiplexing for up to 16 logical channels,
464 low-latency and full duplex communication.
465 </para>
466
467!Iinclude/linux/hsi/hsi.h
468!Edrivers/hsi/hsi.c
469 </chapter>
470
471</book>