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Based on kernel version 3.19. Page generated on 2015-02-13 21:20 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/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	<!--
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/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
120	X!Edrivers/base/attribute_container.c
121	-->
122	!Edrivers/base/dd.c
123	<!--
124	X!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
146	X!Edrivers/acpi/sleep/main.c
147	X!Edrivers/acpi/sleep/wakeup.c
148	X!Edrivers/acpi/motherboard.c
149	X!Edrivers/acpi/bus.c
150	-->
151	!Edrivers/acpi/scan.c
152	!Idrivers/acpi/scan.c
153	<!-- No correct structured comments
154	X!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
160	X!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
232	X!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>
287	X!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>
297	X!Idrivers/video/fbgen.c
298	     </sect1>
299	KAO -->
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
312	X!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>
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