aboutsummaryrefslogtreecommitdiff
path: root/Documentation/DocBook/device-drivers.tmpl
blob: 7514dbf0a6796c4e216a175fa79db0ed3ff470d9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
	"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>

<book id="LinuxDriversAPI">
 <bookinfo>
  <title>Linux Device Drivers</title>

  <legalnotice>
   <para>
     This documentation is free software; you can redistribute
     it and/or modify it under the terms of the GNU General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later
     version.
   </para>

   <para>
     This program is distributed in the hope that it will be
     useful, but WITHOUT ANY WARRANTY; without even the implied
     warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
     See the GNU General Public License for more details.
   </para>

   <para>
     You should have received a copy of the GNU General Public
     License along with this program; if not, write to the Free
     Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
     MA 02111-1307 USA
   </para>

   <para>
     For more details see the file COPYING in the source
     distribution of Linux.
   </para>
  </legalnotice>
 </bookinfo>

<toc></toc>

  <chapter id="Basics">
     <title>Driver Basics</title>
     <sect1><title>Driver Entry and Exit points</title>
!Iinclude/linux/init.h
     </sect1>

     <sect1><title>Atomic and pointer manipulation</title>
!Iarch/x86/include/asm/atomic.h
     </sect1>

     <sect1><title>Delaying, scheduling, and timer routines</title>
!Iinclude/linux/sched.h
!Ekernel/sched/core.c
!Ikernel/sched/cpupri.c
!Ikernel/sched/fair.c
!Iinclude/linux/completion.h
!Ekernel/timer.c
     </sect1>
     <sect1><title>Wait queues and Wake events</title>
!Iinclude/linux/wait.h
!Ekernel/wait.c
     </sect1>
     <sect1><title>High-resolution timers</title>
!Iinclude/linux/ktime.h
!Iinclude/linux/hrtimer.h
!Ekernel/hrtimer.c
     </sect1>
     <sect1><title>Workqueues and Kevents</title>
!Ekernel/workqueue.c
     </sect1>
     <sect1><title>Internal Functions</title>
!Ikernel/exit.c
!Ikernel/signal.c
!Iinclude/linux/kthread.h
!Ekernel/kthread.c
     </sect1>

     <sect1><title>Kernel objects manipulation</title>
<!--
X!Iinclude/linux/kobject.h
-->
!Elib/kobject.c
     </sect1>

     <sect1><title>Kernel utility functions</title>
!Iinclude/linux/kernel.h
!Ekernel/printk.c
!Ekernel/panic.c
!Ekernel/sys.c
!Ekernel/rcupdate.c
     </sect1>

     <sect1><title>Device Resource Management</title>
!Edrivers/base/devres.c
     </sect1>

  </chapter>

  <chapter id="devdrivers">
     <title>Device drivers infrastructure</title>
     <sect1><title>The Basic Device Driver-Model Structures </title>
!Iinclude/linux/device.h
     </sect1>
     <sect1><title>Device Drivers Base</title>
!Idrivers/base/init.c
!Edrivers/base/driver.c
!Edrivers/base/core.c
!Edrivers/base/syscore.c
!Edrivers/base/class.c
!Idrivers/base/node.c
!Edrivers/base/firmware_class.c
!Edrivers/base/transport_class.c
<!-- Cannot be included, because
     attribute_container_add_class_device_adapter
 and attribute_container_classdev_to_container
     exceed allowed 44 characters maximum
X!Edrivers/base/attribute_container.c
-->
!Edrivers/base/dd.c
<!--
X!Edrivers/base/interface.c
-->
!Iinclude/linux/platform_device.h
!Edrivers/base/platform.c
!Edrivers/base/bus.c
     </sect1>
     <sect1><title>Device Drivers DMA Management</title>
!Edrivers/base/dma-buf.c
!Edrivers/base/dma-coherent.c
!Edrivers/base/dma-mapping.c
     </sect1>
     <sect1><title>Device Drivers Power Management</title>
!Edrivers/base/power/main.c
     </sect1>
     <sect1><title>Device Drivers ACPI Support</title>
<!-- Internal functions only
X!Edrivers/acpi/sleep/main.c
X!Edrivers/acpi/sleep/wakeup.c
X!Edrivers/acpi/motherboard.c
X!Edrivers/acpi/bus.c
-->
!Edrivers/acpi/scan.c
!Idrivers/acpi/scan.c
<!-- No correct structured comments
X!Edrivers/acpi/pci_bind.c
-->
     </sect1>
     <sect1><title>Device drivers PnP support</title>
!Idrivers/pnp/core.c
<!-- No correct structured comments
X!Edrivers/pnp/system.c
 -->
!Edrivers/pnp/card.c
!Idrivers/pnp/driver.c
!Edrivers/pnp/manager.c
!Edrivers/pnp/support.c
     </sect1>
     <sect1><title>Userspace IO devices</title>
!Edrivers/uio/uio.c
!Iinclude/linux/uio_driver.h
     </sect1>
  </chapter>

  <chapter id="parportdev">
     <title>Parallel Port Devices</title>
!Iinclude/linux/parport.h
!Edrivers/parport/ieee1284.c
!Edrivers/parport/share.c
!Idrivers/parport/daisy.c
  </chapter>

  <chapter id="message_devices">
	<title>Message-based devices</title>
     <sect1><title>Fusion message devices</title>
!Edrivers/message/fusion/mptbase.c
!Idrivers/message/fusion/mptbase.c
!Edrivers/message/fusion/mptscsih.c
!Idrivers/message/fusion/mptscsih.c
!Idrivers/message/fusion/mptctl.c
!Idrivers/message/fusion/mptspi.c
!Idrivers/message/fusion/mptfc.c
!Idrivers/message/fusion/mptlan.c
     </sect1>
     <sect1><title>I2O message devices</title>
!Iinclude/linux/i2o.h
!Idrivers/message/i2o/core.h
!Edrivers/message/i2o/iop.c
!Idrivers/message/i2o/iop.c
!Idrivers/message/i2o/config-osm.c
!Edrivers/message/i2o/exec-osm.c
!Idrivers/message/i2o/exec-osm.c
!Idrivers/message/i2o/bus-osm.c
!Edrivers/message/i2o/device.c
!Idrivers/message/i2o/device.c
!Idrivers/message/i2o/driver.c
!Idrivers/message/i2o/pci.c
!Idrivers/message/i2o/i2o_block.c
!Idrivers/message/i2o/i2o_scsi.c
!Idrivers/message/i2o/i2o_proc.c
     </sect1>
  </chapter>

  <chapter id="snddev">
     <title>Sound Devices</title>
!Iinclude/sound/core.h
!Esound/sound_core.c
!Iinclude/sound/pcm.h
!Esound/core/pcm.c
!Esound/core/device.c
!Esound/core/info.c
!Esound/core/rawmidi.c
!Esound/core/sound.c
!Esound/core/memory.c
!Esound/core/pcm_memory.c
!Esound/core/init.c
!Esound/core/isadma.c
!Esound/core/control.c
!Esound/core/pcm_lib.c
!Esound/core/hwdep.c
!Esound/core/pcm_native.c
!Esound/core/memalloc.c
<!-- FIXME: Removed for now since no structured comments in source
X!Isound/sound_firmware.c
-->
  </chapter>

  <chapter id="uart16x50">
     <title>16x50 UART Driver</title>
!Edrivers/tty/serial/serial_core.c
!Edrivers/tty/serial/8250/8250.c
  </chapter>

  <chapter id="fbdev">
     <title>Frame Buffer Library</title>

     <para>
       The frame buffer drivers depend heavily on four data structures.
       These structures are declared in include/linux/fb.h.  They are
       fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
       The last three can be made available to and from userland.
     </para>

     <para>
       fb_info defines the current state of a particular video card.
       Inside fb_info, there exists a fb_ops structure which is a
       collection of needed functions to make fbdev and fbcon work.
       fb_info is only visible to the kernel.
     </para>

     <para>
       fb_var_screeninfo is used to describe the features of a video card
       that are user defined.  With fb_var_screeninfo, things such as
       depth and the resolution may be defined.
     </para>

     <para>
       The next structure is fb_fix_screeninfo. This defines the
       properties of a card that are created when a mode is set and can't
       be changed otherwise.  A good example of this is the start of the
       frame buffer memory.  This "locks" the address of the frame buffer
       memory, so that it cannot be changed or moved.
     </para>

     <para>
       The last structure is fb_monospecs. In the old API, there was
       little importance for fb_monospecs. This allowed for forbidden things
       such as setting a mode of 800x600 on a fix frequency monitor. With
       the new API, fb_monospecs prevents such things, and if used
       correctly, can prevent a monitor from being cooked.  fb_monospecs
       will not be useful until kernels 2.5.x.
     </para>

     <sect1><title>Frame Buffer Memory</title>
!Edrivers/video/fbmem.c
     </sect1>
<!--
     <sect1><title>Frame Buffer Console</title>
X!Edrivers/video/console/fbcon.c
     </sect1>
-->
     <sect1><title>Frame Buffer Colormap</title>
!Edrivers/video/fbcmap.c
     </sect1>
<!-- FIXME:
  drivers/video/fbgen.c has no docs, which stuffs up the sgml.  Comment
  out until somebody adds docs.  KAO
     <sect1><title>Frame Buffer Generic Functions</title>
X!Idrivers/video/fbgen.c
     </sect1>
KAO -->
     <sect1><title>Frame Buffer Video Mode Database</title>
!Idrivers/video/modedb.c
!Edrivers/video/modedb.c
     </sect1>
     <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
!Edrivers/video/macmodes.c
     </sect1>
     <sect1><title>Frame Buffer Fonts</title>
        <para>
           Refer to the file drivers/video/console/fonts.c for more information.
        </para>
<!-- FIXME: Removed for now since no structured comments in source
X!Idrivers/video/console/fonts.c
-->
     </sect1>
  </chapter>

  <chapter id="input_subsystem">
     <title>Input Subsystem</title>
     <sect1><title>Input core</title>
!Iinclude/linux/input.h
!Edrivers/input/input.c
!Edrivers/input/ff-core.c
!Edrivers/input/ff-memless.c
     </sect1>
     <sect1><title>Multitouch Library</title>
!Iinclude/linux/input/mt.h
!Edrivers/input/input-mt.c
     </sect1>
     <sect1><title>Polled input devices</title>
!Iinclude/linux/input-polldev.h
!Edrivers/input/input-polldev.c
     </sect1>
     <sect1><title>Matrix keyboars/keypads</title>
!Iinclude/linux/input/matrix_keypad.h
     </sect1>
     <sect1><title>Sparse keymap support</title>
!Iinclude/linux/input/sparse-keymap.h
!Edrivers/input/sparse-keymap.c
     </sect1>
  </chapter>

  <chapter id="spi">
      <title>Serial Peripheral Interface (SPI)</title>
  <para>
	SPI is the "Serial Peripheral Interface", widely used with
	embedded systems because it is a simple and efficient
	interface:  basically a multiplexed shift register.
	Its three signal wires hold a clock (SCK, often in the range
	of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
	a "Master In, Slave Out" (MISO) data line.
	SPI is a full duplex protocol; for each bit shifted out the
	MOSI line (one per clock) another is shifted in on the MISO line.
	Those bits are assembled into words of various sizes on the
	way to and from system memory.
	An additional chipselect line is usually active-low (nCS);
	four signals are normally used for each peripheral, plus
	sometimes an interrupt.
  </para>
  <para>
	The SPI bus facilities listed here provide a generalized
	interface to declare SPI busses and devices, manage them
	according to the standard Linux driver model, and perform
	input/output operations.
	At this time, only "master" side interfaces are supported,
	where Linux talks to SPI peripherals and does not implement
	such a peripheral itself.
	(Interfaces to support implementing SPI slaves would
	necessarily look different.)
  </para>
  <para>
	The programming interface is structured around two kinds of driver,
	and two kinds of device.
	A "Controller Driver" abstracts the controller hardware, which may
	be as simple as a set of GPIO pins or as complex as a pair of FIFOs
	connected to dual DMA engines on the other side of the SPI shift
	register (maximizing throughput).  Such drivers bridge between
	whatever bus they sit on (often the platform bus) and SPI, and
	expose the SPI side of their device as a
	<structname>struct spi_master</structname>.
	SPI devices are children of that master, represented as a
	<structname>struct spi_device</structname> and manufactured from
	<structname>struct spi_board_info</structname> descriptors which
	are usually provided by board-specific initialization code.
	A <structname>struct spi_driver</structname> is called a
	"Protocol Driver", and is bound to a spi_device using normal
	driver model calls.
  </para>
  <para>
	The I/O model is a set of queued messages.  Protocol drivers
	submit one or more <structname>struct spi_message</structname>
	objects, which are processed and completed asynchronously.
	(There are synchronous wrappers, however.)  Messages are
	built from one or more <structname>struct spi_transfer</structname>
	objects, each of which wraps a full duplex SPI transfer.
	A variety of protocol tweaking options are needed, because
	different chips adopt very different policies for how they
	use the bits transferred with SPI.
  </para>
!Iinclude/linux/spi/spi.h
!Fdrivers/spi/spi.c spi_register_board_info
!Edrivers/spi/spi.c
  </chapter>

  <chapter id="i2c">
     <title>I<superscript>2</superscript>C and SMBus Subsystem</title>

     <para>
	I<superscript>2</superscript>C (or without fancy typography, "I2C")
	is an acronym for the "Inter-IC" bus, a simple bus protocol which is
	widely used where low data rate communications suffice.
	Since it's also a licensed trademark, some vendors use another
	name (such as "Two-Wire Interface", TWI) for the same bus.
	I2C only needs two signals (SCL for clock, SDA for data), conserving
	board real estate and minimizing signal quality issues.
	Most I2C devices use seven bit addresses, and bus speeds of up
	to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
	found wide use.
	I2C is a multi-master bus; open drain signaling is used to
	arbitrate between masters, as well as to handshake and to
	synchronize clocks from slower clients.
     </para>

     <para>
	The Linux I2C programming interfaces support only the master
	side of bus interactions, not the slave side.
	The programming interface is structured around two kinds of driver,
	and two kinds of device.
	An I2C "Adapter Driver" abstracts the controller hardware; it binds
	to a physical device (perhaps a PCI device or platform_device) and
	exposes a <structname>struct i2c_adapter</structname> representing
	each I2C bus segment it manages.
	On each I2C bus segment will be I2C devices represented by a
	<structname>struct i2c_client</structname>.  Those devices will
	be bound to a <structname>struct i2c_driver</structname>,
	which should follow the standard Linux driver model.
	(At this writing, a legacy model is more widely used.)
	There are functions to perform various I2C protocol operations; at
	this writing all such functions are usable only from task context.
     </para>

     <para>
	The System Management Bus (SMBus) is a sibling protocol.  Most SMBus
	systems are also I2C conformant.  The electrical constraints are
	tighter for SMBus, and it standardizes particular protocol messages
	and idioms.  Controllers that support I2C can also support most
	SMBus operations, but SMBus controllers don't support all the protocol
	options that an I2C controller will.
	There are functions to perform various SMBus protocol operations,
	either using I2C primitives or by issuing SMBus commands to
	i2c_adapter devices which don't support those I2C operations.
     </para>

!Iinclude/linux/i2c.h
!Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
!Edrivers/i2c/i2c-core.c
  </chapter>

  <chapter id="hsi">
     <title>High Speed Synchronous Serial Interface (HSI)</title>

     <para>
	High Speed Synchronous Serial Interface (HSI) is a
	serial interface mainly used for connecting application
	engines (APE) with cellular modem engines (CMT) in cellular
	handsets.

	HSI provides multiplexing for up to 16 logical channels,
	low-latency and full duplex communication.
     </para>

!Iinclude/linux/hsi/hsi.h
!Edrivers/hsi/hsi.c
  </chapter>

</book>