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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/time/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/time/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/dma-buf/dma-buf.c
132!Edrivers/dma-buf/fence.c
133!Edrivers/dma-buf/seqno-fence.c
134!Iinclude/linux/fence.h
135!Iinclude/linux/seqno-fence.h
136!Edrivers/dma-buf/reservation.c
137!Iinclude/linux/reservation.h
138!Edrivers/base/dma-coherent.c
139!Edrivers/base/dma-mapping.c
140 </sect1>
141 <sect1><title>Device Drivers Power Management</title>
142!Edrivers/base/power/main.c
143 </sect1>
144 <sect1><title>Device Drivers ACPI Support</title>
145<!-- Internal functions only
146X!Edrivers/acpi/sleep/main.c
147X!Edrivers/acpi/sleep/wakeup.c
148X!Edrivers/acpi/motherboard.c
149X!Edrivers/acpi/bus.c
150-->
151!Edrivers/acpi/scan.c
152!Idrivers/acpi/scan.c
153<!-- No correct structured comments
154X!Edrivers/acpi/pci_bind.c
155-->
156 </sect1>
157 <sect1><title>Device drivers PnP support</title>
158!Idrivers/pnp/core.c
159<!-- No correct structured comments
160X!Edrivers/pnp/system.c
161 -->
162!Edrivers/pnp/card.c
163!Idrivers/pnp/driver.c
164!Edrivers/pnp/manager.c
165!Edrivers/pnp/support.c
166 </sect1>
167 <sect1><title>Userspace IO devices</title>
168!Edrivers/uio/uio.c
169!Iinclude/linux/uio_driver.h
170 </sect1>
171 </chapter>
172
173 <chapter id="parportdev">
174 <title>Parallel Port Devices</title>
175!Iinclude/linux/parport.h
176!Edrivers/parport/ieee1284.c
177!Edrivers/parport/share.c
178!Idrivers/parport/daisy.c
179 </chapter>
180
181 <chapter id="message_devices">
182 <title>Message-based devices</title>
183 <sect1><title>Fusion message devices</title>
184!Edrivers/message/fusion/mptbase.c
185!Idrivers/message/fusion/mptbase.c
186!Edrivers/message/fusion/mptscsih.c
187!Idrivers/message/fusion/mptscsih.c
188!Idrivers/message/fusion/mptctl.c
189!Idrivers/message/fusion/mptspi.c
190!Idrivers/message/fusion/mptfc.c
191!Idrivers/message/fusion/mptlan.c
192 </sect1>
193 <sect1><title>I2O message devices</title>
194!Iinclude/linux/i2o.h
195!Idrivers/message/i2o/core.h
196!Edrivers/message/i2o/iop.c
197!Idrivers/message/i2o/iop.c
198!Idrivers/message/i2o/config-osm.c
199!Edrivers/message/i2o/exec-osm.c
200!Idrivers/message/i2o/exec-osm.c
201!Idrivers/message/i2o/bus-osm.c
202!Edrivers/message/i2o/device.c
203!Idrivers/message/i2o/device.c
204!Idrivers/message/i2o/driver.c
205!Idrivers/message/i2o/pci.c
206!Idrivers/message/i2o/i2o_block.c
207!Idrivers/message/i2o/i2o_scsi.c
208!Idrivers/message/i2o/i2o_proc.c
209 </sect1>
210 </chapter>
211
212 <chapter id="snddev">
213 <title>Sound Devices</title>
214!Iinclude/sound/core.h
215!Esound/sound_core.c
216!Iinclude/sound/pcm.h
217!Esound/core/pcm.c
218!Esound/core/device.c
219!Esound/core/info.c
220!Esound/core/rawmidi.c
221!Esound/core/sound.c
222!Esound/core/memory.c
223!Esound/core/pcm_memory.c
224!Esound/core/init.c
225!Esound/core/isadma.c
226!Esound/core/control.c
227!Esound/core/pcm_lib.c
228!Esound/core/hwdep.c
229!Esound/core/pcm_native.c
230!Esound/core/memalloc.c
231<!-- FIXME: Removed for now since no structured comments in source
232X!Isound/sound_firmware.c
233-->
234 </chapter>
235
236 <chapter id="uart16x50">
237 <title>16x50 UART Driver</title>
238!Edrivers/tty/serial/serial_core.c
239!Edrivers/tty/serial/8250/8250_core.c
240 </chapter>
241
242 <chapter id="fbdev">
243 <title>Frame Buffer Library</title>
244
245 <para>
246 The frame buffer drivers depend heavily on four data structures.
247 These structures are declared in include/linux/fb.h. They are
248 fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
249 The last three can be made available to and from userland.
250 </para>
251
252 <para>
253 fb_info defines the current state of a particular video card.
254 Inside fb_info, there exists a fb_ops structure which is a
255 collection of needed functions to make fbdev and fbcon work.
256 fb_info is only visible to the kernel.
257 </para>
258
259 <para>
260 fb_var_screeninfo is used to describe the features of a video card
261 that are user defined. With fb_var_screeninfo, things such as
262 depth and the resolution may be defined.
263 </para>
264
265 <para>
266 The next structure is fb_fix_screeninfo. This defines the
267 properties of a card that are created when a mode is set and can't
268 be changed otherwise. A good example of this is the start of the
269 frame buffer memory. This "locks" the address of the frame buffer
270 memory, so that it cannot be changed or moved.
271 </para>
272
273 <para>
274 The last structure is fb_monospecs. In the old API, there was
275 little importance for fb_monospecs. This allowed for forbidden things
276 such as setting a mode of 800x600 on a fix frequency monitor. With
277 the new API, fb_monospecs prevents such things, and if used
278 correctly, can prevent a monitor from being cooked. fb_monospecs
279 will not be useful until kernels 2.5.x.
280 </para>
281
282 <sect1><title>Frame Buffer Memory</title>
283!Edrivers/video/fbdev/core/fbmem.c
284 </sect1>
285<!--
286 <sect1><title>Frame Buffer Console</title>
287X!Edrivers/video/console/fbcon.c
288 </sect1>
289-->
290 <sect1><title>Frame Buffer Colormap</title>
291!Edrivers/video/fbdev/core/fbcmap.c
292 </sect1>
293<!-- FIXME:
294 drivers/video/fbgen.c has no docs, which stuffs up the sgml. Comment
295 out until somebody adds docs. KAO
296 <sect1><title>Frame Buffer Generic Functions</title>
297X!Idrivers/video/fbgen.c
298 </sect1>
299KAO -->
300 <sect1><title>Frame Buffer Video Mode Database</title>
301!Idrivers/video/fbdev/core/modedb.c
302!Edrivers/video/fbdev/core/modedb.c
303 </sect1>
304 <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
305!Edrivers/video/fbdev/macmodes.c
306 </sect1>
307 <sect1><title>Frame Buffer Fonts</title>
308 <para>
309 Refer to the file lib/fonts/fonts.c for more information.
310 </para>
311<!-- FIXME: Removed for now since no structured comments in source
312X!Ilib/fonts/fonts.c
313-->
314 </sect1>
315 </chapter>
316
317 <chapter id="input_subsystem">
318 <title>Input Subsystem</title>
319 <sect1><title>Input core</title>
320!Iinclude/linux/input.h
321!Edrivers/input/input.c
322!Edrivers/input/ff-core.c
323!Edrivers/input/ff-memless.c
324 </sect1>
325 <sect1><title>Multitouch Library</title>
326!Iinclude/linux/input/mt.h
327!Edrivers/input/input-mt.c
328 </sect1>
329 <sect1><title>Polled input devices</title>
330!Iinclude/linux/input-polldev.h
331!Edrivers/input/input-polldev.c
332 </sect1>
333 <sect1><title>Matrix keyboars/keypads</title>
334!Iinclude/linux/input/matrix_keypad.h
335 </sect1>
336 <sect1><title>Sparse keymap support</title>
337!Iinclude/linux/input/sparse-keymap.h
338!Edrivers/input/sparse-keymap.c
339 </sect1>
340 </chapter>
341
342 <chapter id="spi">
343 <title>Serial Peripheral Interface (SPI)</title>
344 <para>
345 SPI is the "Serial Peripheral Interface", widely used with
346 embedded systems because it is a simple and efficient
347 interface: basically a multiplexed shift register.
348 Its three signal wires hold a clock (SCK, often in the range
349 of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
350 a "Master In, Slave Out" (MISO) data line.
351 SPI is a full duplex protocol; for each bit shifted out the
352 MOSI line (one per clock) another is shifted in on the MISO line.
353 Those bits are assembled into words of various sizes on the
354 way to and from system memory.
355 An additional chipselect line is usually active-low (nCS);
356 four signals are normally used for each peripheral, plus
357 sometimes an interrupt.
358 </para>
359 <para>
360 The SPI bus facilities listed here provide a generalized
361 interface to declare SPI busses and devices, manage them
362 according to the standard Linux driver model, and perform
363 input/output operations.
364 At this time, only "master" side interfaces are supported,
365 where Linux talks to SPI peripherals and does not implement
366 such a peripheral itself.
367 (Interfaces to support implementing SPI slaves would
368 necessarily look different.)
369 </para>
370 <para>
371 The programming interface is structured around two kinds of driver,
372 and two kinds of device.
373 A "Controller Driver" abstracts the controller hardware, which may
374 be as simple as a set of GPIO pins or as complex as a pair of FIFOs
375 connected to dual DMA engines on the other side of the SPI shift
376 register (maximizing throughput). Such drivers bridge between
377 whatever bus they sit on (often the platform bus) and SPI, and
378 expose the SPI side of their device as a
379 <structname>struct spi_master</structname>.
380 SPI devices are children of that master, represented as a
381 <structname>struct spi_device</structname> and manufactured from
382 <structname>struct spi_board_info</structname> descriptors which
383 are usually provided by board-specific initialization code.
384 A <structname>struct spi_driver</structname> is called a
385 "Protocol Driver", and is bound to a spi_device using normal
386 driver model calls.
387 </para>
388 <para>
389 The I/O model is a set of queued messages. Protocol drivers
390 submit one or more <structname>struct spi_message</structname>
391 objects, which are processed and completed asynchronously.
392 (There are synchronous wrappers, however.) Messages are
393 built from one or more <structname>struct spi_transfer</structname>
394 objects, each of which wraps a full duplex SPI transfer.
395 A variety of protocol tweaking options are needed, because
396 different chips adopt very different policies for how they
397 use the bits transferred with SPI.
398 </para>
399!Iinclude/linux/spi/spi.h
400!Fdrivers/spi/spi.c spi_register_board_info
401!Edrivers/spi/spi.c
402 </chapter>
403
404 <chapter id="i2c">
405 <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
406
407 <para>
408 I<superscript>2</superscript>C (or without fancy typography, "I2C")
409 is an acronym for the "Inter-IC" bus, a simple bus protocol which is
410 widely used where low data rate communications suffice.
411 Since it's also a licensed trademark, some vendors use another
412 name (such as "Two-Wire Interface", TWI) for the same bus.
413 I2C only needs two signals (SCL for clock, SDA for data), conserving
414 board real estate and minimizing signal quality issues.
415 Most I2C devices use seven bit addresses, and bus speeds of up
416 to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
417 found wide use.
418 I2C is a multi-master bus; open drain signaling is used to
419 arbitrate between masters, as well as to handshake and to
420 synchronize clocks from slower clients.
421 </para>
422
423 <para>
424 The Linux I2C programming interfaces support only the master
425 side of bus interactions, not the slave side.
426 The programming interface is structured around two kinds of driver,
427 and two kinds of device.
428 An I2C "Adapter Driver" abstracts the controller hardware; it binds
429 to a physical device (perhaps a PCI device or platform_device) and
430 exposes a <structname>struct i2c_adapter</structname> representing
431 each I2C bus segment it manages.
432 On each I2C bus segment will be I2C devices represented by a
433 <structname>struct i2c_client</structname>. Those devices will
434 be bound to a <structname>struct i2c_driver</structname>,
435 which should follow the standard Linux driver model.
436 (At this writing, a legacy model is more widely used.)
437 There are functions to perform various I2C protocol operations; at
438 this writing all such functions are usable only from task context.
439 </para>
440
441 <para>
442 The System Management Bus (SMBus) is a sibling protocol. Most SMBus
443 systems are also I2C conformant. The electrical constraints are
444 tighter for SMBus, and it standardizes particular protocol messages
445 and idioms. Controllers that support I2C can also support most
446 SMBus operations, but SMBus controllers don't support all the protocol
447 options that an I2C controller will.
448 There are functions to perform various SMBus protocol operations,
449 either using I2C primitives or by issuing SMBus commands to
450 i2c_adapter devices which don't support those I2C operations.
451 </para>
452
453!Iinclude/linux/i2c.h
454!Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
455!Edrivers/i2c/i2c-core.c
456 </chapter>
457
458 <chapter id="hsi">
459 <title>High Speed Synchronous Serial Interface (HSI)</title>
460
461 <para>
462 High Speed Synchronous Serial Interface (HSI) is a
463 serial interface mainly used for connecting application
464 engines (APE) with cellular modem engines (CMT) in cellular
465 handsets.
466
467 HSI provides multiplexing for up to 16 logical channels,
468 low-latency and full duplex communication.
469 </para>
470
471!Iinclude/linux/hsi/hsi.h
472!Edrivers/hsi/hsi.c
473 </chapter>
474
475</book>