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