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Based on kernel version 3.9. Page generated on 2013-05-02 23:03 EST.

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	<!--
80	X!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.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
117	X!Edrivers/base/attribute_container.c
118	-->
119	!Edrivers/base/dd.c
120	<!--
121	X!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/dma-coherent.c
130	!Edrivers/base/dma-mapping.c
131	     </sect1>
132	     <sect1><title>Device Drivers Power Management</title>
133	!Edrivers/base/power/main.c
134	     </sect1>
135	     <sect1><title>Device Drivers ACPI Support</title>
136	<!-- Internal functions only
137	X!Edrivers/acpi/sleep/main.c
138	X!Edrivers/acpi/sleep/wakeup.c
139	X!Edrivers/acpi/motherboard.c
140	X!Edrivers/acpi/bus.c
141	-->
142	!Edrivers/acpi/scan.c
143	!Idrivers/acpi/scan.c
144	<!-- No correct structured comments
145	X!Edrivers/acpi/pci_bind.c
146	-->
147	     </sect1>
148	     <sect1><title>Device drivers PnP support</title>
149	!Idrivers/pnp/core.c
150	<!-- No correct structured comments
151	X!Edrivers/pnp/system.c
152	 -->
153	!Edrivers/pnp/card.c
154	!Idrivers/pnp/driver.c
155	!Edrivers/pnp/manager.c
156	!Edrivers/pnp/support.c
157	     </sect1>
158	     <sect1><title>Userspace IO devices</title>
159	!Edrivers/uio/uio.c
160	!Iinclude/linux/uio_driver.h
161	     </sect1>
162	  </chapter>
163	
164	  <chapter id="parportdev">
165	     <title>Parallel Port Devices</title>
166	!Iinclude/linux/parport.h
167	!Edrivers/parport/ieee1284.c
168	!Edrivers/parport/share.c
169	!Idrivers/parport/daisy.c
170	  </chapter>
171	
172	  <chapter id="message_devices">
173		<title>Message-based devices</title>
174	     <sect1><title>Fusion message devices</title>
175	!Edrivers/message/fusion/mptbase.c
176	!Idrivers/message/fusion/mptbase.c
177	!Edrivers/message/fusion/mptscsih.c
178	!Idrivers/message/fusion/mptscsih.c
179	!Idrivers/message/fusion/mptctl.c
180	!Idrivers/message/fusion/mptspi.c
181	!Idrivers/message/fusion/mptfc.c
182	!Idrivers/message/fusion/mptlan.c
183	     </sect1>
184	     <sect1><title>I2O message devices</title>
185	!Iinclude/linux/i2o.h
186	!Idrivers/message/i2o/core.h
187	!Edrivers/message/i2o/iop.c
188	!Idrivers/message/i2o/iop.c
189	!Idrivers/message/i2o/config-osm.c
190	!Edrivers/message/i2o/exec-osm.c
191	!Idrivers/message/i2o/exec-osm.c
192	!Idrivers/message/i2o/bus-osm.c
193	!Edrivers/message/i2o/device.c
194	!Idrivers/message/i2o/device.c
195	!Idrivers/message/i2o/driver.c
196	!Idrivers/message/i2o/pci.c
197	!Idrivers/message/i2o/i2o_block.c
198	!Idrivers/message/i2o/i2o_scsi.c
199	!Idrivers/message/i2o/i2o_proc.c
200	     </sect1>
201	  </chapter>
202	
203	  <chapter id="snddev">
204	     <title>Sound Devices</title>
205	!Iinclude/sound/core.h
206	!Esound/sound_core.c
207	!Iinclude/sound/pcm.h
208	!Esound/core/pcm.c
209	!Esound/core/device.c
210	!Esound/core/info.c
211	!Esound/core/rawmidi.c
212	!Esound/core/sound.c
213	!Esound/core/memory.c
214	!Esound/core/pcm_memory.c
215	!Esound/core/init.c
216	!Esound/core/isadma.c
217	!Esound/core/control.c
218	!Esound/core/pcm_lib.c
219	!Esound/core/hwdep.c
220	!Esound/core/pcm_native.c
221	!Esound/core/memalloc.c
222	<!-- FIXME: Removed for now since no structured comments in source
223	X!Isound/sound_firmware.c
224	-->
225	  </chapter>
226	
227	  <chapter id="uart16x50">
228	     <title>16x50 UART Driver</title>
229	!Edrivers/tty/serial/serial_core.c
230	!Edrivers/tty/serial/8250/8250_core.c
231	  </chapter>
232	
233	  <chapter id="fbdev">
234	     <title>Frame Buffer Library</title>
235	
236	     <para>
237	       The frame buffer drivers depend heavily on four data structures.
238	       These structures are declared in include/linux/fb.h.  They are
239	       fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
240	       The last three can be made available to and from userland.
241	     </para>
242	
243	     <para>
244	       fb_info defines the current state of a particular video card.
245	       Inside fb_info, there exists a fb_ops structure which is a
246	       collection of needed functions to make fbdev and fbcon work.
247	       fb_info is only visible to the kernel.
248	     </para>
249	
250	     <para>
251	       fb_var_screeninfo is used to describe the features of a video card
252	       that are user defined.  With fb_var_screeninfo, things such as
253	       depth and the resolution may be defined.
254	     </para>
255	
256	     <para>
257	       The next structure is fb_fix_screeninfo. This defines the
258	       properties of a card that are created when a mode is set and can't
259	       be changed otherwise.  A good example of this is the start of the
260	       frame buffer memory.  This "locks" the address of the frame buffer
261	       memory, so that it cannot be changed or moved.
262	     </para>
263	
264	     <para>
265	       The last structure is fb_monospecs. In the old API, there was
266	       little importance for fb_monospecs. This allowed for forbidden things
267	       such as setting a mode of 800x600 on a fix frequency monitor. With
268	       the new API, fb_monospecs prevents such things, and if used
269	       correctly, can prevent a monitor from being cooked.  fb_monospecs
270	       will not be useful until kernels 2.5.x.
271	     </para>
272	
273	     <sect1><title>Frame Buffer Memory</title>
274	!Edrivers/video/fbmem.c
275	     </sect1>
276	<!--
277	     <sect1><title>Frame Buffer Console</title>
278	X!Edrivers/video/console/fbcon.c
279	     </sect1>
280	-->
281	     <sect1><title>Frame Buffer Colormap</title>
282	!Edrivers/video/fbcmap.c
283	     </sect1>
284	<!-- FIXME:
285	  drivers/video/fbgen.c has no docs, which stuffs up the sgml.  Comment
286	  out until somebody adds docs.  KAO
287	     <sect1><title>Frame Buffer Generic Functions</title>
288	X!Idrivers/video/fbgen.c
289	     </sect1>
290	KAO -->
291	     <sect1><title>Frame Buffer Video Mode Database</title>
292	!Idrivers/video/modedb.c
293	!Edrivers/video/modedb.c
294	     </sect1>
295	     <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
296	!Edrivers/video/macmodes.c
297	     </sect1>
298	     <sect1><title>Frame Buffer Fonts</title>
299	        <para>
300	           Refer to the file drivers/video/console/fonts.c for more information.
301	        </para>
302	<!-- FIXME: Removed for now since no structured comments in source
303	X!Idrivers/video/console/fonts.c
304	-->
305	     </sect1>
306	  </chapter>
307	
308	  <chapter id="input_subsystem">
309	     <title>Input Subsystem</title>
310	     <sect1><title>Input core</title>
311	!Iinclude/linux/input.h
312	!Edrivers/input/input.c
313	!Edrivers/input/ff-core.c
314	!Edrivers/input/ff-memless.c
315	     </sect1>
316	     <sect1><title>Multitouch Library</title>
317	!Iinclude/linux/input/mt.h
318	!Edrivers/input/input-mt.c
319	     </sect1>
320	     <sect1><title>Polled input devices</title>
321	!Iinclude/linux/input-polldev.h
322	!Edrivers/input/input-polldev.c
323	     </sect1>
324	     <sect1><title>Matrix keyboars/keypads</title>
325	!Iinclude/linux/input/matrix_keypad.h
326	     </sect1>
327	     <sect1><title>Sparse keymap support</title>
328	!Iinclude/linux/input/sparse-keymap.h
329	!Edrivers/input/sparse-keymap.c
330	     </sect1>
331	  </chapter>
332	
333	  <chapter id="spi">
334	      <title>Serial Peripheral Interface (SPI)</title>
335	  <para>
336		SPI is the "Serial Peripheral Interface", widely used with
337		embedded systems because it is a simple and efficient
338		interface:  basically a multiplexed shift register.
339		Its three signal wires hold a clock (SCK, often in the range
340		of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
341		a "Master In, Slave Out" (MISO) data line.
342		SPI is a full duplex protocol; for each bit shifted out the
343		MOSI line (one per clock) another is shifted in on the MISO line.
344		Those bits are assembled into words of various sizes on the
345		way to and from system memory.
346		An additional chipselect line is usually active-low (nCS);
347		four signals are normally used for each peripheral, plus
348		sometimes an interrupt.
349	  </para>
350	  <para>
351		The SPI bus facilities listed here provide a generalized
352		interface to declare SPI busses and devices, manage them
353		according to the standard Linux driver model, and perform
354		input/output operations.
355		At this time, only "master" side interfaces are supported,
356		where Linux talks to SPI peripherals and does not implement
357		such a peripheral itself.
358		(Interfaces to support implementing SPI slaves would
359		necessarily look different.)
360	  </para>
361	  <para>
362		The programming interface is structured around two kinds of driver,
363		and two kinds of device.
364		A "Controller Driver" abstracts the controller hardware, which may
365		be as simple as a set of GPIO pins or as complex as a pair of FIFOs
366		connected to dual DMA engines on the other side of the SPI shift
367		register (maximizing throughput).  Such drivers bridge between
368		whatever bus they sit on (often the platform bus) and SPI, and
369		expose the SPI side of their device as a
370		<structname>struct spi_master</structname>.
371		SPI devices are children of that master, represented as a
372		<structname>struct spi_device</structname> and manufactured from
373		<structname>struct spi_board_info</structname> descriptors which
374		are usually provided by board-specific initialization code.
375		A <structname>struct spi_driver</structname> is called a
376		"Protocol Driver", and is bound to a spi_device using normal
377		driver model calls.
378	  </para>
379	  <para>
380		The I/O model is a set of queued messages.  Protocol drivers
381		submit one or more <structname>struct spi_message</structname>
382		objects, which are processed and completed asynchronously.
383		(There are synchronous wrappers, however.)  Messages are
384		built from one or more <structname>struct spi_transfer</structname>
385		objects, each of which wraps a full duplex SPI transfer.
386		A variety of protocol tweaking options are needed, because
387		different chips adopt very different policies for how they
388		use the bits transferred with SPI.
389	  </para>
390	!Iinclude/linux/spi/spi.h
391	!Fdrivers/spi/spi.c spi_register_board_info
392	!Edrivers/spi/spi.c
393	  </chapter>
394	
395	  <chapter id="i2c">
396	     <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
397	
398	     <para>
399		I<superscript>2</superscript>C (or without fancy typography, "I2C")
400		is an acronym for the "Inter-IC" bus, a simple bus protocol which is
401		widely used where low data rate communications suffice.
402		Since it's also a licensed trademark, some vendors use another
403		name (such as "Two-Wire Interface", TWI) for the same bus.
404		I2C only needs two signals (SCL for clock, SDA for data), conserving
405		board real estate and minimizing signal quality issues.
406		Most I2C devices use seven bit addresses, and bus speeds of up
407		to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
408		found wide use.
409		I2C is a multi-master bus; open drain signaling is used to
410		arbitrate between masters, as well as to handshake and to
411		synchronize clocks from slower clients.
412	     </para>
413	
414	     <para>
415		The Linux I2C programming interfaces support only the master
416		side of bus interactions, not the slave side.
417		The programming interface is structured around two kinds of driver,
418		and two kinds of device.
419		An I2C "Adapter Driver" abstracts the controller hardware; it binds
420		to a physical device (perhaps a PCI device or platform_device) and
421		exposes a <structname>struct i2c_adapter</structname> representing
422		each I2C bus segment it manages.
423		On each I2C bus segment will be I2C devices represented by a
424		<structname>struct i2c_client</structname>.  Those devices will
425		be bound to a <structname>struct i2c_driver</structname>,
426		which should follow the standard Linux driver model.
427		(At this writing, a legacy model is more widely used.)
428		There are functions to perform various I2C protocol operations; at
429		this writing all such functions are usable only from task context.
430	     </para>
431	
432	     <para>
433		The System Management Bus (SMBus) is a sibling protocol.  Most SMBus
434		systems are also I2C conformant.  The electrical constraints are
435		tighter for SMBus, and it standardizes particular protocol messages
436		and idioms.  Controllers that support I2C can also support most
437		SMBus operations, but SMBus controllers don't support all the protocol
438		options that an I2C controller will.
439		There are functions to perform various SMBus protocol operations,
440		either using I2C primitives or by issuing SMBus commands to
441		i2c_adapter devices which don't support those I2C operations.
442	     </para>
443	
444	!Iinclude/linux/i2c.h
445	!Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
446	!Edrivers/i2c/i2c-core.c
447	  </chapter>
448	
449	  <chapter id="hsi">
450	     <title>High Speed Synchronous Serial Interface (HSI)</title>
451	
452	     <para>
453		High Speed Synchronous Serial Interface (HSI) is a
454		serial interface mainly used for connecting application
455		engines (APE) with cellular modem engines (CMT) in cellular
456		handsets.
457	
458		HSI provides multiplexing for up to 16 logical channels,
459		low-latency and full duplex communication.
460	     </para>
461	
462	!Iinclude/linux/hsi/hsi.h
463	!Edrivers/hsi/hsi.c
464	  </chapter>
465	
466	</book>
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