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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>
88b68033 48!Iarch/x86/include/asm/atomic.h
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49 </sect1>
50
51 <sect1><title>Delaying, scheduling, and timer routines</title>
52!Iinclude/linux/sched.h
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53!Ekernel/sched/core.c
54!Ikernel/sched/cpupri.c
55!Ikernel/sched/fair.c
ee2f154a 56!Iinclude/linux/completion.h
be11e6d8 57!Ekernel/time/timer.c
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58 </sect1>
59 <sect1><title>Wait queues and Wake events</title>
60!Iinclude/linux/wait.h
96d5d9d9 61!Ekernel/sched/wait.c
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62 </sect1>
63 <sect1><title>High-resolution timers</title>
64!Iinclude/linux/ktime.h
65!Iinclude/linux/hrtimer.h
be11e6d8 66!Ekernel/time/hrtimer.c
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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
b9ee979e 87!Ekernel/printk/printk.c
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88!Ekernel/panic.c
89!Ekernel/sys.c
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90!Ekernel/rcu/srcu.c
91!Ekernel/rcu/tree.c
92!Ekernel/rcu/tree_plugin.h
93!Ekernel/rcu/update.c
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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>
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104 <sect1><title>The Basic Device Driver-Model Structures </title>
105!Iinclude/linux/device.h
106 </sect1>
f7f84f38 107 <sect1><title>Device Drivers Base</title>
13405059 108!Idrivers/base/init.c
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109!Edrivers/base/driver.c
110!Edrivers/base/core.c
13405059 111!Edrivers/base/syscore.c
f7f84f38 112!Edrivers/base/class.c
13405059 113!Idrivers/base/node.c
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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-->
13405059 122!Edrivers/base/dd.c
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123<!--
124X!Edrivers/base/interface.c
125-->
44f28bde 126!Iinclude/linux/platform_device.h
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127!Edrivers/base/platform.c
128!Edrivers/base/bus.c
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129 </sect1>
130 <sect1><title>Device Drivers DMA Management</title>
35fac7e3 131!Edrivers/dma-buf/dma-buf.c
e941759c 132!Edrivers/dma-buf/fence.c
606b23ad 133!Edrivers/dma-buf/seqno-fence.c
e941759c 134!Iinclude/linux/fence.h
606b23ad 135!Iinclude/linux/seqno-fence.h
04a5faa8 136!Edrivers/dma-buf/reservation.c
786d7257 137!Iinclude/linux/reservation.h
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138!Edrivers/base/dma-coherent.c
139!Edrivers/base/dma-mapping.c
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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>
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193 </chapter>
194
195 <chapter id="snddev">
196 <title>Sound Devices</title>
197!Iinclude/sound/core.h
198!Esound/sound_core.c
199!Iinclude/sound/pcm.h
200!Esound/core/pcm.c
201!Esound/core/device.c
202!Esound/core/info.c
203!Esound/core/rawmidi.c
204!Esound/core/sound.c
205!Esound/core/memory.c
206!Esound/core/pcm_memory.c
207!Esound/core/init.c
208!Esound/core/isadma.c
209!Esound/core/control.c
210!Esound/core/pcm_lib.c
211!Esound/core/hwdep.c
212!Esound/core/pcm_native.c
213!Esound/core/memalloc.c
214<!-- FIXME: Removed for now since no structured comments in source
215X!Isound/sound_firmware.c
216-->
217 </chapter>
218
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219 <chapter id="mediadev">
220 <title>Media Devices</title>
221!Iinclude/media/media-device.h
222!Iinclude/media/media-devnode.h
223!Iinclude/media/media-entity.h
224!Iinclude/media/v4l2-async.h
225!Iinclude/media/v4l2-flash-led-class.h
226!Iinclude/media/v4l2-mem2mem.h
227!Iinclude/media/v4l2-of.h
228!Iinclude/media/v4l2-subdev.h
229!Iinclude/media/rc-core.h
fbefb1a8 230!Idrivers/media/dvb-core/dvb_ca_en50221.h
4f1c1868 231!Idrivers/media/dvb-core/dvb_frontend.h
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232<!-- FIXME: Removed for now due to document generation inconsistency
233X!Iinclude/media/v4l2-ctrls.h
234X!Iinclude/media/v4l2-dv-timings.h
235X!Iinclude/media/v4l2-event.h
236X!Iinclude/media/v4l2-mediabus.h
237X!Iinclude/media/videobuf2-memops.h
238X!Iinclude/media/videobuf2-core.h
239X!Iinclude/media/lirc.h
240X!Edrivers/media/dvb-core/dvb_demux.c
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241X!Idrivers/media/dvb-core/dvbdev.h
242X!Edrivers/media/dvb-core/dvb_net.c
243X!Idrivers/media/dvb-core/dvb_ringbuffer.h
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244X!Idrivers/media/dvb-core/dvb_math.h
245-->
246
247 </chapter>
248
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249 <chapter id="uart16x50">
250 <title>16x50 UART Driver</title>
fcf28564 251!Edrivers/tty/serial/serial_core.c
5448bd8c 252!Edrivers/tty/serial/8250/8250_core.c
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253 </chapter>
254
255 <chapter id="fbdev">
256 <title>Frame Buffer Library</title>
257
258 <para>
259 The frame buffer drivers depend heavily on four data structures.
260 These structures are declared in include/linux/fb.h. They are
261 fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
262 The last three can be made available to and from userland.
263 </para>
264
265 <para>
266 fb_info defines the current state of a particular video card.
267 Inside fb_info, there exists a fb_ops structure which is a
268 collection of needed functions to make fbdev and fbcon work.
269 fb_info is only visible to the kernel.
270 </para>
271
272 <para>
273 fb_var_screeninfo is used to describe the features of a video card
274 that are user defined. With fb_var_screeninfo, things such as
275 depth and the resolution may be defined.
276 </para>
277
278 <para>
279 The next structure is fb_fix_screeninfo. This defines the
280 properties of a card that are created when a mode is set and can't
281 be changed otherwise. A good example of this is the start of the
282 frame buffer memory. This "locks" the address of the frame buffer
283 memory, so that it cannot be changed or moved.
284 </para>
285
286 <para>
287 The last structure is fb_monospecs. In the old API, there was
288 little importance for fb_monospecs. This allowed for forbidden things
289 such as setting a mode of 800x600 on a fix frequency monitor. With
290 the new API, fb_monospecs prevents such things, and if used
291 correctly, can prevent a monitor from being cooked. fb_monospecs
292 will not be useful until kernels 2.5.x.
293 </para>
294
295 <sect1><title>Frame Buffer Memory</title>
19757fc8 296!Edrivers/video/fbdev/core/fbmem.c
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297 </sect1>
298<!--
299 <sect1><title>Frame Buffer Console</title>
300X!Edrivers/video/console/fbcon.c
301 </sect1>
302-->
303 <sect1><title>Frame Buffer Colormap</title>
19757fc8 304!Edrivers/video/fbdev/core/fbcmap.c
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305 </sect1>
306<!-- FIXME:
307 drivers/video/fbgen.c has no docs, which stuffs up the sgml. Comment
308 out until somebody adds docs. KAO
309 <sect1><title>Frame Buffer Generic Functions</title>
310X!Idrivers/video/fbgen.c
311 </sect1>
312KAO -->
313 <sect1><title>Frame Buffer Video Mode Database</title>
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314!Idrivers/video/fbdev/core/modedb.c
315!Edrivers/video/fbdev/core/modedb.c
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316 </sect1>
317 <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
f7018c21 318!Edrivers/video/fbdev/macmodes.c
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319 </sect1>
320 <sect1><title>Frame Buffer Fonts</title>
321 <para>
ee89bd6b 322 Refer to the file lib/fonts/fonts.c for more information.
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323 </para>
324<!-- FIXME: Removed for now since no structured comments in source
ee89bd6b 325X!Ilib/fonts/fonts.c
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326-->
327 </sect1>
328 </chapter>
329
330 <chapter id="input_subsystem">
331 <title>Input Subsystem</title>
d69249f4 332 <sect1><title>Input core</title>
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333!Iinclude/linux/input.h
334!Edrivers/input/input.c
335!Edrivers/input/ff-core.c
336!Edrivers/input/ff-memless.c
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337 </sect1>
338 <sect1><title>Multitouch Library</title>
339!Iinclude/linux/input/mt.h
340!Edrivers/input/input-mt.c
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341 </sect1>
342 <sect1><title>Polled input devices</title>
343!Iinclude/linux/input-polldev.h
344!Edrivers/input/input-polldev.c
345 </sect1>
346 <sect1><title>Matrix keyboars/keypads</title>
347!Iinclude/linux/input/matrix_keypad.h
348 </sect1>
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349 <sect1><title>Sparse keymap support</title>
350!Iinclude/linux/input/sparse-keymap.h
351!Edrivers/input/sparse-keymap.c
352 </sect1>
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353 </chapter>
354
355 <chapter id="spi">
356 <title>Serial Peripheral Interface (SPI)</title>
357 <para>
358 SPI is the "Serial Peripheral Interface", widely used with
359 embedded systems because it is a simple and efficient
360 interface: basically a multiplexed shift register.
361 Its three signal wires hold a clock (SCK, often in the range
362 of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
363 a "Master In, Slave Out" (MISO) data line.
364 SPI is a full duplex protocol; for each bit shifted out the
365 MOSI line (one per clock) another is shifted in on the MISO line.
366 Those bits are assembled into words of various sizes on the
367 way to and from system memory.
368 An additional chipselect line is usually active-low (nCS);
369 four signals are normally used for each peripheral, plus
370 sometimes an interrupt.
371 </para>
372 <para>
373 The SPI bus facilities listed here provide a generalized
374 interface to declare SPI busses and devices, manage them
375 according to the standard Linux driver model, and perform
376 input/output operations.
377 At this time, only "master" side interfaces are supported,
378 where Linux talks to SPI peripherals and does not implement
379 such a peripheral itself.
380 (Interfaces to support implementing SPI slaves would
381 necessarily look different.)
382 </para>
383 <para>
384 The programming interface is structured around two kinds of driver,
385 and two kinds of device.
386 A "Controller Driver" abstracts the controller hardware, which may
387 be as simple as a set of GPIO pins or as complex as a pair of FIFOs
388 connected to dual DMA engines on the other side of the SPI shift
389 register (maximizing throughput). Such drivers bridge between
390 whatever bus they sit on (often the platform bus) and SPI, and
391 expose the SPI side of their device as a
392 <structname>struct spi_master</structname>.
393 SPI devices are children of that master, represented as a
394 <structname>struct spi_device</structname> and manufactured from
395 <structname>struct spi_board_info</structname> descriptors which
396 are usually provided by board-specific initialization code.
397 A <structname>struct spi_driver</structname> is called a
398 "Protocol Driver", and is bound to a spi_device using normal
399 driver model calls.
400 </para>
401 <para>
402 The I/O model is a set of queued messages. Protocol drivers
403 submit one or more <structname>struct spi_message</structname>
404 objects, which are processed and completed asynchronously.
405 (There are synchronous wrappers, however.) Messages are
406 built from one or more <structname>struct spi_transfer</structname>
407 objects, each of which wraps a full duplex SPI transfer.
408 A variety of protocol tweaking options are needed, because
409 different chips adopt very different policies for how they
410 use the bits transferred with SPI.
411 </para>
412!Iinclude/linux/spi/spi.h
413!Fdrivers/spi/spi.c spi_register_board_info
414!Edrivers/spi/spi.c
415 </chapter>
416
417 <chapter id="i2c">
418 <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
419
420 <para>
421 I<superscript>2</superscript>C (or without fancy typography, "I2C")
422 is an acronym for the "Inter-IC" bus, a simple bus protocol which is
423 widely used where low data rate communications suffice.
424 Since it's also a licensed trademark, some vendors use another
425 name (such as "Two-Wire Interface", TWI) for the same bus.
426 I2C only needs two signals (SCL for clock, SDA for data), conserving
427 board real estate and minimizing signal quality issues.
428 Most I2C devices use seven bit addresses, and bus speeds of up
429 to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
430 found wide use.
431 I2C is a multi-master bus; open drain signaling is used to
432 arbitrate between masters, as well as to handshake and to
433 synchronize clocks from slower clients.
434 </para>
435
436 <para>
437 The Linux I2C programming interfaces support only the master
438 side of bus interactions, not the slave side.
439 The programming interface is structured around two kinds of driver,
440 and two kinds of device.
441 An I2C "Adapter Driver" abstracts the controller hardware; it binds
442 to a physical device (perhaps a PCI device or platform_device) and
443 exposes a <structname>struct i2c_adapter</structname> representing
444 each I2C bus segment it manages.
445 On each I2C bus segment will be I2C devices represented by a
446 <structname>struct i2c_client</structname>. Those devices will
447 be bound to a <structname>struct i2c_driver</structname>,
448 which should follow the standard Linux driver model.
449 (At this writing, a legacy model is more widely used.)
450 There are functions to perform various I2C protocol operations; at
451 this writing all such functions are usable only from task context.
452 </para>
453
454 <para>
455 The System Management Bus (SMBus) is a sibling protocol. Most SMBus
456 systems are also I2C conformant. The electrical constraints are
457 tighter for SMBus, and it standardizes particular protocol messages
458 and idioms. Controllers that support I2C can also support most
459 SMBus operations, but SMBus controllers don't support all the protocol
460 options that an I2C controller will.
461 There are functions to perform various SMBus protocol operations,
462 either using I2C primitives or by issuing SMBus commands to
463 i2c_adapter devices which don't support those I2C operations.
464 </para>
465
466!Iinclude/linux/i2c.h
467!Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
468!Edrivers/i2c/i2c-core.c
469 </chapter>
470
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471 <chapter id="hsi">
472 <title>High Speed Synchronous Serial Interface (HSI)</title>
473
474 <para>
475 High Speed Synchronous Serial Interface (HSI) is a
476 serial interface mainly used for connecting application
477 engines (APE) with cellular modem engines (CMT) in cellular
478 handsets.
479
480 HSI provides multiplexing for up to 16 logical channels,
481 low-latency and full duplex communication.
482 </para>
483
484!Iinclude/linux/hsi/hsi.h
485!Edrivers/hsi/hsi.c
486 </chapter>
487
f7f84f38 488</book>