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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 |
f7f84f38 RD |
49 | </sect1> |
50 | ||
51 | <sect1><title>Delaying, scheduling, and timer routines</title> | |
52 | !Iinclude/linux/sched.h | |
53 | !Ekernel/sched.c | |
ee2f154a | 54 | !Iinclude/linux/completion.h |
f7f84f38 | 55 | !Ekernel/timer.c |
ee2f154a RD |
56 | </sect1> |
57 | <sect1><title>Wait queues and Wake events</title> | |
58 | !Iinclude/linux/wait.h | |
59 | !Ekernel/wait.c | |
f7f84f38 RD |
60 | </sect1> |
61 | <sect1><title>High-resolution timers</title> | |
62 | !Iinclude/linux/ktime.h | |
63 | !Iinclude/linux/hrtimer.h | |
64 | !Ekernel/hrtimer.c | |
65 | </sect1> | |
66 | <sect1><title>Workqueues and Kevents</title> | |
67 | !Ekernel/workqueue.c | |
68 | </sect1> | |
69 | <sect1><title>Internal Functions</title> | |
70 | !Ikernel/exit.c | |
71 | !Ikernel/signal.c | |
72 | !Iinclude/linux/kthread.h | |
73 | !Ekernel/kthread.c | |
74 | </sect1> | |
75 | ||
76 | <sect1><title>Kernel objects manipulation</title> | |
77 | <!-- | |
78 | X!Iinclude/linux/kobject.h | |
79 | --> | |
80 | !Elib/kobject.c | |
81 | </sect1> | |
82 | ||
83 | <sect1><title>Kernel utility functions</title> | |
84 | !Iinclude/linux/kernel.h | |
85 | !Ekernel/printk.c | |
86 | !Ekernel/panic.c | |
87 | !Ekernel/sys.c | |
88 | !Ekernel/rcupdate.c | |
89 | </sect1> | |
90 | ||
91 | <sect1><title>Device Resource Management</title> | |
92 | !Edrivers/base/devres.c | |
93 | </sect1> | |
94 | ||
95 | </chapter> | |
96 | ||
97 | <chapter id="devdrivers"> | |
98 | <title>Device drivers infrastructure</title> | |
99 | <sect1><title>Device Drivers Base</title> | |
100 | <!-- | |
101 | X!Iinclude/linux/device.h | |
102 | --> | |
103 | !Edrivers/base/driver.c | |
104 | !Edrivers/base/core.c | |
105 | !Edrivers/base/class.c | |
106 | !Edrivers/base/firmware_class.c | |
107 | !Edrivers/base/transport_class.c | |
108 | <!-- Cannot be included, because | |
109 | attribute_container_add_class_device_adapter | |
110 | and attribute_container_classdev_to_container | |
111 | exceed allowed 44 characters maximum | |
112 | X!Edrivers/base/attribute_container.c | |
113 | --> | |
114 | !Edrivers/base/sys.c | |
115 | <!-- | |
116 | X!Edrivers/base/interface.c | |
117 | --> | |
44f28bde | 118 | !Iinclude/linux/platform_device.h |
f7f84f38 RD |
119 | !Edrivers/base/platform.c |
120 | !Edrivers/base/bus.c | |
121 | </sect1> | |
122 | <sect1><title>Device Drivers Power Management</title> | |
123 | !Edrivers/base/power/main.c | |
124 | </sect1> | |
125 | <sect1><title>Device Drivers ACPI Support</title> | |
126 | <!-- Internal functions only | |
127 | X!Edrivers/acpi/sleep/main.c | |
128 | X!Edrivers/acpi/sleep/wakeup.c | |
129 | X!Edrivers/acpi/motherboard.c | |
130 | X!Edrivers/acpi/bus.c | |
131 | --> | |
132 | !Edrivers/acpi/scan.c | |
133 | !Idrivers/acpi/scan.c | |
134 | <!-- No correct structured comments | |
135 | X!Edrivers/acpi/pci_bind.c | |
136 | --> | |
137 | </sect1> | |
138 | <sect1><title>Device drivers PnP support</title> | |
139 | !Idrivers/pnp/core.c | |
140 | <!-- No correct structured comments | |
141 | X!Edrivers/pnp/system.c | |
142 | --> | |
143 | !Edrivers/pnp/card.c | |
144 | !Idrivers/pnp/driver.c | |
145 | !Edrivers/pnp/manager.c | |
146 | !Edrivers/pnp/support.c | |
147 | </sect1> | |
148 | <sect1><title>Userspace IO devices</title> | |
149 | !Edrivers/uio/uio.c | |
150 | !Iinclude/linux/uio_driver.h | |
151 | </sect1> | |
152 | </chapter> | |
153 | ||
154 | <chapter id="parportdev"> | |
155 | <title>Parallel Port Devices</title> | |
156 | !Iinclude/linux/parport.h | |
157 | !Edrivers/parport/ieee1284.c | |
158 | !Edrivers/parport/share.c | |
159 | !Idrivers/parport/daisy.c | |
160 | </chapter> | |
161 | ||
162 | <chapter id="message_devices"> | |
163 | <title>Message-based devices</title> | |
164 | <sect1><title>Fusion message devices</title> | |
165 | !Edrivers/message/fusion/mptbase.c | |
166 | !Idrivers/message/fusion/mptbase.c | |
167 | !Edrivers/message/fusion/mptscsih.c | |
168 | !Idrivers/message/fusion/mptscsih.c | |
169 | !Idrivers/message/fusion/mptctl.c | |
170 | !Idrivers/message/fusion/mptspi.c | |
171 | !Idrivers/message/fusion/mptfc.c | |
172 | !Idrivers/message/fusion/mptlan.c | |
173 | </sect1> | |
174 | <sect1><title>I2O message devices</title> | |
175 | !Iinclude/linux/i2o.h | |
176 | !Idrivers/message/i2o/core.h | |
177 | !Edrivers/message/i2o/iop.c | |
178 | !Idrivers/message/i2o/iop.c | |
179 | !Idrivers/message/i2o/config-osm.c | |
180 | !Edrivers/message/i2o/exec-osm.c | |
181 | !Idrivers/message/i2o/exec-osm.c | |
182 | !Idrivers/message/i2o/bus-osm.c | |
183 | !Edrivers/message/i2o/device.c | |
184 | !Idrivers/message/i2o/device.c | |
185 | !Idrivers/message/i2o/driver.c | |
186 | !Idrivers/message/i2o/pci.c | |
187 | !Idrivers/message/i2o/i2o_block.c | |
188 | !Idrivers/message/i2o/i2o_scsi.c | |
189 | !Idrivers/message/i2o/i2o_proc.c | |
190 | </sect1> | |
191 | </chapter> | |
192 | ||
193 | <chapter id="snddev"> | |
194 | <title>Sound Devices</title> | |
195 | !Iinclude/sound/core.h | |
196 | !Esound/sound_core.c | |
197 | !Iinclude/sound/pcm.h | |
198 | !Esound/core/pcm.c | |
199 | !Esound/core/device.c | |
200 | !Esound/core/info.c | |
201 | !Esound/core/rawmidi.c | |
202 | !Esound/core/sound.c | |
203 | !Esound/core/memory.c | |
204 | !Esound/core/pcm_memory.c | |
205 | !Esound/core/init.c | |
206 | !Esound/core/isadma.c | |
207 | !Esound/core/control.c | |
208 | !Esound/core/pcm_lib.c | |
209 | !Esound/core/hwdep.c | |
210 | !Esound/core/pcm_native.c | |
211 | !Esound/core/memalloc.c | |
212 | <!-- FIXME: Removed for now since no structured comments in source | |
213 | X!Isound/sound_firmware.c | |
214 | --> | |
215 | </chapter> | |
216 | ||
217 | <chapter id="uart16x50"> | |
218 | <title>16x50 UART Driver</title> | |
219 | !Iinclude/linux/serial_core.h | |
220 | !Edrivers/serial/serial_core.c | |
221 | !Edrivers/serial/8250.c | |
222 | </chapter> | |
223 | ||
224 | <chapter id="fbdev"> | |
225 | <title>Frame Buffer Library</title> | |
226 | ||
227 | <para> | |
228 | The frame buffer drivers depend heavily on four data structures. | |
229 | These structures are declared in include/linux/fb.h. They are | |
230 | fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs. | |
231 | The last three can be made available to and from userland. | |
232 | </para> | |
233 | ||
234 | <para> | |
235 | fb_info defines the current state of a particular video card. | |
236 | Inside fb_info, there exists a fb_ops structure which is a | |
237 | collection of needed functions to make fbdev and fbcon work. | |
238 | fb_info is only visible to the kernel. | |
239 | </para> | |
240 | ||
241 | <para> | |
242 | fb_var_screeninfo is used to describe the features of a video card | |
243 | that are user defined. With fb_var_screeninfo, things such as | |
244 | depth and the resolution may be defined. | |
245 | </para> | |
246 | ||
247 | <para> | |
248 | The next structure is fb_fix_screeninfo. This defines the | |
249 | properties of a card that are created when a mode is set and can't | |
250 | be changed otherwise. A good example of this is the start of the | |
251 | frame buffer memory. This "locks" the address of the frame buffer | |
252 | memory, so that it cannot be changed or moved. | |
253 | </para> | |
254 | ||
255 | <para> | |
256 | The last structure is fb_monospecs. In the old API, there was | |
257 | little importance for fb_monospecs. This allowed for forbidden things | |
258 | such as setting a mode of 800x600 on a fix frequency monitor. With | |
259 | the new API, fb_monospecs prevents such things, and if used | |
260 | correctly, can prevent a monitor from being cooked. fb_monospecs | |
261 | will not be useful until kernels 2.5.x. | |
262 | </para> | |
263 | ||
264 | <sect1><title>Frame Buffer Memory</title> | |
265 | !Edrivers/video/fbmem.c | |
266 | </sect1> | |
267 | <!-- | |
268 | <sect1><title>Frame Buffer Console</title> | |
269 | X!Edrivers/video/console/fbcon.c | |
270 | </sect1> | |
271 | --> | |
272 | <sect1><title>Frame Buffer Colormap</title> | |
273 | !Edrivers/video/fbcmap.c | |
274 | </sect1> | |
275 | <!-- FIXME: | |
276 | drivers/video/fbgen.c has no docs, which stuffs up the sgml. Comment | |
277 | out until somebody adds docs. KAO | |
278 | <sect1><title>Frame Buffer Generic Functions</title> | |
279 | X!Idrivers/video/fbgen.c | |
280 | </sect1> | |
281 | KAO --> | |
282 | <sect1><title>Frame Buffer Video Mode Database</title> | |
283 | !Idrivers/video/modedb.c | |
284 | !Edrivers/video/modedb.c | |
285 | </sect1> | |
286 | <sect1><title>Frame Buffer Macintosh Video Mode Database</title> | |
287 | !Edrivers/video/macmodes.c | |
288 | </sect1> | |
289 | <sect1><title>Frame Buffer Fonts</title> | |
290 | <para> | |
291 | Refer to the file drivers/video/console/fonts.c for more information. | |
292 | </para> | |
293 | <!-- FIXME: Removed for now since no structured comments in source | |
294 | X!Idrivers/video/console/fonts.c | |
295 | --> | |
296 | </sect1> | |
297 | </chapter> | |
298 | ||
299 | <chapter id="input_subsystem"> | |
300 | <title>Input Subsystem</title> | |
d69249f4 | 301 | <sect1><title>Input core</title> |
f7f84f38 RD |
302 | !Iinclude/linux/input.h |
303 | !Edrivers/input/input.c | |
304 | !Edrivers/input/ff-core.c | |
305 | !Edrivers/input/ff-memless.c | |
d69249f4 DT |
306 | </sect1> |
307 | <sect1><title>Polled input devices</title> | |
308 | !Iinclude/linux/input-polldev.h | |
309 | !Edrivers/input/input-polldev.c | |
310 | </sect1> | |
311 | <sect1><title>Matrix keyboars/keypads</title> | |
312 | !Iinclude/linux/input/matrix_keypad.h | |
313 | </sect1> | |
36203c4f DT |
314 | <sect1><title>Sparse keymap support</title> |
315 | !Iinclude/linux/input/sparse-keymap.h | |
316 | !Edrivers/input/sparse-keymap.c | |
317 | </sect1> | |
f7f84f38 RD |
318 | </chapter> |
319 | ||
320 | <chapter id="spi"> | |
321 | <title>Serial Peripheral Interface (SPI)</title> | |
322 | <para> | |
323 | SPI is the "Serial Peripheral Interface", widely used with | |
324 | embedded systems because it is a simple and efficient | |
325 | interface: basically a multiplexed shift register. | |
326 | Its three signal wires hold a clock (SCK, often in the range | |
327 | of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and | |
328 | a "Master In, Slave Out" (MISO) data line. | |
329 | SPI is a full duplex protocol; for each bit shifted out the | |
330 | MOSI line (one per clock) another is shifted in on the MISO line. | |
331 | Those bits are assembled into words of various sizes on the | |
332 | way to and from system memory. | |
333 | An additional chipselect line is usually active-low (nCS); | |
334 | four signals are normally used for each peripheral, plus | |
335 | sometimes an interrupt. | |
336 | </para> | |
337 | <para> | |
338 | The SPI bus facilities listed here provide a generalized | |
339 | interface to declare SPI busses and devices, manage them | |
340 | according to the standard Linux driver model, and perform | |
341 | input/output operations. | |
342 | At this time, only "master" side interfaces are supported, | |
343 | where Linux talks to SPI peripherals and does not implement | |
344 | such a peripheral itself. | |
345 | (Interfaces to support implementing SPI slaves would | |
346 | necessarily look different.) | |
347 | </para> | |
348 | <para> | |
349 | The programming interface is structured around two kinds of driver, | |
350 | and two kinds of device. | |
351 | A "Controller Driver" abstracts the controller hardware, which may | |
352 | be as simple as a set of GPIO pins or as complex as a pair of FIFOs | |
353 | connected to dual DMA engines on the other side of the SPI shift | |
354 | register (maximizing throughput). Such drivers bridge between | |
355 | whatever bus they sit on (often the platform bus) and SPI, and | |
356 | expose the SPI side of their device as a | |
357 | <structname>struct spi_master</structname>. | |
358 | SPI devices are children of that master, represented as a | |
359 | <structname>struct spi_device</structname> and manufactured from | |
360 | <structname>struct spi_board_info</structname> descriptors which | |
361 | are usually provided by board-specific initialization code. | |
362 | A <structname>struct spi_driver</structname> is called a | |
363 | "Protocol Driver", and is bound to a spi_device using normal | |
364 | driver model calls. | |
365 | </para> | |
366 | <para> | |
367 | The I/O model is a set of queued messages. Protocol drivers | |
368 | submit one or more <structname>struct spi_message</structname> | |
369 | objects, which are processed and completed asynchronously. | |
370 | (There are synchronous wrappers, however.) Messages are | |
371 | built from one or more <structname>struct spi_transfer</structname> | |
372 | objects, each of which wraps a full duplex SPI transfer. | |
373 | A variety of protocol tweaking options are needed, because | |
374 | different chips adopt very different policies for how they | |
375 | use the bits transferred with SPI. | |
376 | </para> | |
377 | !Iinclude/linux/spi/spi.h | |
378 | !Fdrivers/spi/spi.c spi_register_board_info | |
379 | !Edrivers/spi/spi.c | |
380 | </chapter> | |
381 | ||
382 | <chapter id="i2c"> | |
383 | <title>I<superscript>2</superscript>C and SMBus Subsystem</title> | |
384 | ||
385 | <para> | |
386 | I<superscript>2</superscript>C (or without fancy typography, "I2C") | |
387 | is an acronym for the "Inter-IC" bus, a simple bus protocol which is | |
388 | widely used where low data rate communications suffice. | |
389 | Since it's also a licensed trademark, some vendors use another | |
390 | name (such as "Two-Wire Interface", TWI) for the same bus. | |
391 | I2C only needs two signals (SCL for clock, SDA for data), conserving | |
392 | board real estate and minimizing signal quality issues. | |
393 | Most I2C devices use seven bit addresses, and bus speeds of up | |
394 | to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet | |
395 | found wide use. | |
396 | I2C is a multi-master bus; open drain signaling is used to | |
397 | arbitrate between masters, as well as to handshake and to | |
398 | synchronize clocks from slower clients. | |
399 | </para> | |
400 | ||
401 | <para> | |
402 | The Linux I2C programming interfaces support only the master | |
403 | side of bus interactions, not the slave side. | |
404 | The programming interface is structured around two kinds of driver, | |
405 | and two kinds of device. | |
406 | An I2C "Adapter Driver" abstracts the controller hardware; it binds | |
407 | to a physical device (perhaps a PCI device or platform_device) and | |
408 | exposes a <structname>struct i2c_adapter</structname> representing | |
409 | each I2C bus segment it manages. | |
410 | On each I2C bus segment will be I2C devices represented by a | |
411 | <structname>struct i2c_client</structname>. Those devices will | |
412 | be bound to a <structname>struct i2c_driver</structname>, | |
413 | which should follow the standard Linux driver model. | |
414 | (At this writing, a legacy model is more widely used.) | |
415 | There are functions to perform various I2C protocol operations; at | |
416 | this writing all such functions are usable only from task context. | |
417 | </para> | |
418 | ||
419 | <para> | |
420 | The System Management Bus (SMBus) is a sibling protocol. Most SMBus | |
421 | systems are also I2C conformant. The electrical constraints are | |
422 | tighter for SMBus, and it standardizes particular protocol messages | |
423 | and idioms. Controllers that support I2C can also support most | |
424 | SMBus operations, but SMBus controllers don't support all the protocol | |
425 | options that an I2C controller will. | |
426 | There are functions to perform various SMBus protocol operations, | |
427 | either using I2C primitives or by issuing SMBus commands to | |
428 | i2c_adapter devices which don't support those I2C operations. | |
429 | </para> | |
430 | ||
431 | !Iinclude/linux/i2c.h | |
432 | !Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info | |
433 | !Edrivers/i2c/i2c-core.c | |
434 | </chapter> | |
435 | ||
436 | </book> |