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Based on kernel version 3.15.4. Page generated on 2014-07-07 09:02 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/sched/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/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/base/dma-buf.c
132	!Edrivers/base/reservation.c
133	!Iinclude/linux/reservation.h
134	!Edrivers/base/dma-coherent.c
135	!Edrivers/base/dma-mapping.c
136	     </sect1>
137	     <sect1><title>Device Drivers Power Management</title>
138	!Edrivers/base/power/main.c
139	     </sect1>
140	     <sect1><title>Device Drivers ACPI Support</title>
141	<!-- Internal functions only
142	X!Edrivers/acpi/sleep/main.c
143	X!Edrivers/acpi/sleep/wakeup.c
144	X!Edrivers/acpi/motherboard.c
145	X!Edrivers/acpi/bus.c
146	-->
147	!Edrivers/acpi/scan.c
148	!Idrivers/acpi/scan.c
149	<!-- No correct structured comments
150	X!Edrivers/acpi/pci_bind.c
151	-->
152	     </sect1>
153	     <sect1><title>Device drivers PnP support</title>
154	!Idrivers/pnp/core.c
155	<!-- No correct structured comments
156	X!Edrivers/pnp/system.c
157	 -->
158	!Edrivers/pnp/card.c
159	!Idrivers/pnp/driver.c
160	!Edrivers/pnp/manager.c
161	!Edrivers/pnp/support.c
162	     </sect1>
163	     <sect1><title>Userspace IO devices</title>
164	!Edrivers/uio/uio.c
165	!Iinclude/linux/uio_driver.h
166	     </sect1>
167	  </chapter>
168	
169	  <chapter id="parportdev">
170	     <title>Parallel Port Devices</title>
171	!Iinclude/linux/parport.h
172	!Edrivers/parport/ieee1284.c
173	!Edrivers/parport/share.c
174	!Idrivers/parport/daisy.c
175	  </chapter>
176	
177	  <chapter id="message_devices">
178		<title>Message-based devices</title>
179	     <sect1><title>Fusion message devices</title>
180	!Edrivers/message/fusion/mptbase.c
181	!Idrivers/message/fusion/mptbase.c
182	!Edrivers/message/fusion/mptscsih.c
183	!Idrivers/message/fusion/mptscsih.c
184	!Idrivers/message/fusion/mptctl.c
185	!Idrivers/message/fusion/mptspi.c
186	!Idrivers/message/fusion/mptfc.c
187	!Idrivers/message/fusion/mptlan.c
188	     </sect1>
189	     <sect1><title>I2O message devices</title>
190	!Iinclude/linux/i2o.h
191	!Idrivers/message/i2o/core.h
192	!Edrivers/message/i2o/iop.c
193	!Idrivers/message/i2o/iop.c
194	!Idrivers/message/i2o/config-osm.c
195	!Edrivers/message/i2o/exec-osm.c
196	!Idrivers/message/i2o/exec-osm.c
197	!Idrivers/message/i2o/bus-osm.c
198	!Edrivers/message/i2o/device.c
199	!Idrivers/message/i2o/device.c
200	!Idrivers/message/i2o/driver.c
201	!Idrivers/message/i2o/pci.c
202	!Idrivers/message/i2o/i2o_block.c
203	!Idrivers/message/i2o/i2o_scsi.c
204	!Idrivers/message/i2o/i2o_proc.c
205	     </sect1>
206	  </chapter>
207	
208	  <chapter id="snddev">
209	     <title>Sound Devices</title>
210	!Iinclude/sound/core.h
211	!Esound/sound_core.c
212	!Iinclude/sound/pcm.h
213	!Esound/core/pcm.c
214	!Esound/core/device.c
215	!Esound/core/info.c
216	!Esound/core/rawmidi.c
217	!Esound/core/sound.c
218	!Esound/core/memory.c
219	!Esound/core/pcm_memory.c
220	!Esound/core/init.c
221	!Esound/core/isadma.c
222	!Esound/core/control.c
223	!Esound/core/pcm_lib.c
224	!Esound/core/hwdep.c
225	!Esound/core/pcm_native.c
226	!Esound/core/memalloc.c
227	<!-- FIXME: Removed for now since no structured comments in source
228	X!Isound/sound_firmware.c
229	-->
230	  </chapter>
231	
232	  <chapter id="uart16x50">
233	     <title>16x50 UART Driver</title>
234	!Edrivers/tty/serial/serial_core.c
235	!Edrivers/tty/serial/8250/8250_core.c
236	  </chapter>
237	
238	  <chapter id="fbdev">
239	     <title>Frame Buffer Library</title>
240	
241	     <para>
242	       The frame buffer drivers depend heavily on four data structures.
243	       These structures are declared in include/linux/fb.h.  They are
244	       fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
245	       The last three can be made available to and from userland.
246	     </para>
247	
248	     <para>
249	       fb_info defines the current state of a particular video card.
250	       Inside fb_info, there exists a fb_ops structure which is a
251	       collection of needed functions to make fbdev and fbcon work.
252	       fb_info is only visible to the kernel.
253	     </para>
254	
255	     <para>
256	       fb_var_screeninfo is used to describe the features of a video card
257	       that are user defined.  With fb_var_screeninfo, things such as
258	       depth and the resolution may be defined.
259	     </para>
260	
261	     <para>
262	       The next structure is fb_fix_screeninfo. This defines the
263	       properties of a card that are created when a mode is set and can't
264	       be changed otherwise.  A good example of this is the start of the
265	       frame buffer memory.  This "locks" the address of the frame buffer
266	       memory, so that it cannot be changed or moved.
267	     </para>
268	
269	     <para>
270	       The last structure is fb_monospecs. In the old API, there was
271	       little importance for fb_monospecs. This allowed for forbidden things
272	       such as setting a mode of 800x600 on a fix frequency monitor. With
273	       the new API, fb_monospecs prevents such things, and if used
274	       correctly, can prevent a monitor from being cooked.  fb_monospecs
275	       will not be useful until kernels 2.5.x.
276	     </para>
277	
278	     <sect1><title>Frame Buffer Memory</title>
279	!Edrivers/video/fbdev/core/fbmem.c
280	     </sect1>
281	<!--
282	     <sect1><title>Frame Buffer Console</title>
283	X!Edrivers/video/console/fbcon.c
284	     </sect1>
285	-->
286	     <sect1><title>Frame Buffer Colormap</title>
287	!Edrivers/video/fbdev/core/fbcmap.c
288	     </sect1>
289	<!-- FIXME:
290	  drivers/video/fbgen.c has no docs, which stuffs up the sgml.  Comment
291	  out until somebody adds docs.  KAO
292	     <sect1><title>Frame Buffer Generic Functions</title>
293	X!Idrivers/video/fbgen.c
294	     </sect1>
295	KAO -->
296	     <sect1><title>Frame Buffer Video Mode Database</title>
297	!Idrivers/video/fbdev/core/modedb.c
298	!Edrivers/video/fbdev/core/modedb.c
299	     </sect1>
300	     <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
301	!Edrivers/video/fbdev/macmodes.c
302	     </sect1>
303	     <sect1><title>Frame Buffer Fonts</title>
304	        <para>
305	           Refer to the file lib/fonts/fonts.c for more information.
306	        </para>
307	<!-- FIXME: Removed for now since no structured comments in source
308	X!Ilib/fonts/fonts.c
309	-->
310	     </sect1>
311	  </chapter>
312	
313	  <chapter id="input_subsystem">
314	     <title>Input Subsystem</title>
315	     <sect1><title>Input core</title>
316	!Iinclude/linux/input.h
317	!Edrivers/input/input.c
318	!Edrivers/input/ff-core.c
319	!Edrivers/input/ff-memless.c
320	     </sect1>
321	     <sect1><title>Multitouch Library</title>
322	!Iinclude/linux/input/mt.h
323	!Edrivers/input/input-mt.c
324	     </sect1>
325	     <sect1><title>Polled input devices</title>
326	!Iinclude/linux/input-polldev.h
327	!Edrivers/input/input-polldev.c
328	     </sect1>
329	     <sect1><title>Matrix keyboars/keypads</title>
330	!Iinclude/linux/input/matrix_keypad.h
331	     </sect1>
332	     <sect1><title>Sparse keymap support</title>
333	!Iinclude/linux/input/sparse-keymap.h
334	!Edrivers/input/sparse-keymap.c
335	     </sect1>
336	  </chapter>
337	
338	  <chapter id="spi">
339	      <title>Serial Peripheral Interface (SPI)</title>
340	  <para>
341		SPI is the "Serial Peripheral Interface", widely used with
342		embedded systems because it is a simple and efficient
343		interface:  basically a multiplexed shift register.
344		Its three signal wires hold a clock (SCK, often in the range
345		of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
346		a "Master In, Slave Out" (MISO) data line.
347		SPI is a full duplex protocol; for each bit shifted out the
348		MOSI line (one per clock) another is shifted in on the MISO line.
349		Those bits are assembled into words of various sizes on the
350		way to and from system memory.
351		An additional chipselect line is usually active-low (nCS);
352		four signals are normally used for each peripheral, plus
353		sometimes an interrupt.
354	  </para>
355	  <para>
356		The SPI bus facilities listed here provide a generalized
357		interface to declare SPI busses and devices, manage them
358		according to the standard Linux driver model, and perform
359		input/output operations.
360		At this time, only "master" side interfaces are supported,
361		where Linux talks to SPI peripherals and does not implement
362		such a peripheral itself.
363		(Interfaces to support implementing SPI slaves would
364		necessarily look different.)
365	  </para>
366	  <para>
367		The programming interface is structured around two kinds of driver,
368		and two kinds of device.
369		A "Controller Driver" abstracts the controller hardware, which may
370		be as simple as a set of GPIO pins or as complex as a pair of FIFOs
371		connected to dual DMA engines on the other side of the SPI shift
372		register (maximizing throughput).  Such drivers bridge between
373		whatever bus they sit on (often the platform bus) and SPI, and
374		expose the SPI side of their device as a
375		<structname>struct spi_master</structname>.
376		SPI devices are children of that master, represented as a
377		<structname>struct spi_device</structname> and manufactured from
378		<structname>struct spi_board_info</structname> descriptors which
379		are usually provided by board-specific initialization code.
380		A <structname>struct spi_driver</structname> is called a
381		"Protocol Driver", and is bound to a spi_device using normal
382		driver model calls.
383	  </para>
384	  <para>
385		The I/O model is a set of queued messages.  Protocol drivers
386		submit one or more <structname>struct spi_message</structname>
387		objects, which are processed and completed asynchronously.
388		(There are synchronous wrappers, however.)  Messages are
389		built from one or more <structname>struct spi_transfer</structname>
390		objects, each of which wraps a full duplex SPI transfer.
391		A variety of protocol tweaking options are needed, because
392		different chips adopt very different policies for how they
393		use the bits transferred with SPI.
394	  </para>
395	!Iinclude/linux/spi/spi.h
396	!Fdrivers/spi/spi.c spi_register_board_info
397	!Edrivers/spi/spi.c
398	  </chapter>
399	
400	  <chapter id="i2c">
401	     <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
402	
403	     <para>
404		I<superscript>2</superscript>C (or without fancy typography, "I2C")
405		is an acronym for the "Inter-IC" bus, a simple bus protocol which is
406		widely used where low data rate communications suffice.
407		Since it's also a licensed trademark, some vendors use another
408		name (such as "Two-Wire Interface", TWI) for the same bus.
409		I2C only needs two signals (SCL for clock, SDA for data), conserving
410		board real estate and minimizing signal quality issues.
411		Most I2C devices use seven bit addresses, and bus speeds of up
412		to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
413		found wide use.
414		I2C is a multi-master bus; open drain signaling is used to
415		arbitrate between masters, as well as to handshake and to
416		synchronize clocks from slower clients.
417	     </para>
418	
419	     <para>
420		The Linux I2C programming interfaces support only the master
421		side of bus interactions, not the slave side.
422		The programming interface is structured around two kinds of driver,
423		and two kinds of device.
424		An I2C "Adapter Driver" abstracts the controller hardware; it binds
425		to a physical device (perhaps a PCI device or platform_device) and
426		exposes a <structname>struct i2c_adapter</structname> representing
427		each I2C bus segment it manages.
428		On each I2C bus segment will be I2C devices represented by a
429		<structname>struct i2c_client</structname>.  Those devices will
430		be bound to a <structname>struct i2c_driver</structname>,
431		which should follow the standard Linux driver model.
432		(At this writing, a legacy model is more widely used.)
433		There are functions to perform various I2C protocol operations; at
434		this writing all such functions are usable only from task context.
435	     </para>
436	
437	     <para>
438		The System Management Bus (SMBus) is a sibling protocol.  Most SMBus
439		systems are also I2C conformant.  The electrical constraints are
440		tighter for SMBus, and it standardizes particular protocol messages
441		and idioms.  Controllers that support I2C can also support most
442		SMBus operations, but SMBus controllers don't support all the protocol
443		options that an I2C controller will.
444		There are functions to perform various SMBus protocol operations,
445		either using I2C primitives or by issuing SMBus commands to
446		i2c_adapter devices which don't support those I2C operations.
447	     </para>
448	
449	!Iinclude/linux/i2c.h
450	!Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
451	!Edrivers/i2c/i2c-core.c
452	  </chapter>
453	
454	  <chapter id="hsi">
455	     <title>High Speed Synchronous Serial Interface (HSI)</title>
456	
457	     <para>
458		High Speed Synchronous Serial Interface (HSI) is a
459		serial interface mainly used for connecting application
460		engines (APE) with cellular modem engines (CMT) in cellular
461		handsets.
462	
463		HSI provides multiplexing for up to 16 logical channels,
464		low-latency and full duplex communication.
465	     </para>
466	
467	!Iinclude/linux/hsi/hsi.h
468	!Edrivers/hsi/hsi.c
469	  </chapter>
470	
471	</book>
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