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<!--
80X!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
120X!Edrivers/base/attribute_container.c
121-->
122!Edrivers/base/dd.c
123<!--
124X!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
146X!Edrivers/acpi/sleep/main.c
147X!Edrivers/acpi/sleep/wakeup.c
148X!Edrivers/acpi/motherboard.c
149X!Edrivers/acpi/bus.c
150-->
151!Edrivers/acpi/scan.c
152!Idrivers/acpi/scan.c
153<!-- No correct structured comments
154X!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
160X!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  </chapter>
194
195  <chapter id="snddev">
196     <title>Sound Devices</title>
197!Iinclude/sound/core.h
198!Esound/sound_core.c
199!Iinclude/sound/pcm.h
200!Esound/core/pcm.c
201!Esound/core/device.c
202!Esound/core/info.c
203!Esound/core/rawmidi.c
204!Esound/core/sound.c
205!Esound/core/memory.c
206!Esound/core/pcm_memory.c
207!Esound/core/init.c
208!Esound/core/isadma.c
209!Esound/core/control.c
210!Esound/core/pcm_lib.c
211!Esound/core/hwdep.c
212!Esound/core/pcm_native.c
213!Esound/core/memalloc.c
214<!-- FIXME: Removed for now since no structured comments in source
215X!Isound/sound_firmware.c
216-->
217  </chapter>
218
219  <chapter id="uart16x50">
220     <title>16x50 UART Driver</title>
221!Edrivers/tty/serial/serial_core.c
222!Edrivers/tty/serial/8250/8250_core.c
223  </chapter>
224
225  <chapter id="fbdev">
226     <title>Frame Buffer Library</title>
227
228     <para>
229       The frame buffer drivers depend heavily on four data structures.
230       These structures are declared in include/linux/fb.h.  They are
231       fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs.
232       The last three can be made available to and from userland.
233     </para>
234
235     <para>
236       fb_info defines the current state of a particular video card.
237       Inside fb_info, there exists a fb_ops structure which is a
238       collection of needed functions to make fbdev and fbcon work.
239       fb_info is only visible to the kernel.
240     </para>
241
242     <para>
243       fb_var_screeninfo is used to describe the features of a video card
244       that are user defined.  With fb_var_screeninfo, things such as
245       depth and the resolution may be defined.
246     </para>
247
248     <para>
249       The next structure is fb_fix_screeninfo. This defines the
250       properties of a card that are created when a mode is set and can't
251       be changed otherwise.  A good example of this is the start of the
252       frame buffer memory.  This "locks" the address of the frame buffer
253       memory, so that it cannot be changed or moved.
254     </para>
255
256     <para>
257       The last structure is fb_monospecs. In the old API, there was
258       little importance for fb_monospecs. This allowed for forbidden things
259       such as setting a mode of 800x600 on a fix frequency monitor. With
260       the new API, fb_monospecs prevents such things, and if used
261       correctly, can prevent a monitor from being cooked.  fb_monospecs
262       will not be useful until kernels 2.5.x.
263     </para>
264
265     <sect1><title>Frame Buffer Memory</title>
266!Edrivers/video/fbdev/core/fbmem.c
267     </sect1>
268<!--
269     <sect1><title>Frame Buffer Console</title>
270X!Edrivers/video/console/fbcon.c
271     </sect1>
272-->
273     <sect1><title>Frame Buffer Colormap</title>
274!Edrivers/video/fbdev/core/fbcmap.c
275     </sect1>
276<!-- FIXME:
277  drivers/video/fbgen.c has no docs, which stuffs up the sgml.  Comment
278  out until somebody adds docs.  KAO
279     <sect1><title>Frame Buffer Generic Functions</title>
280X!Idrivers/video/fbgen.c
281     </sect1>
282KAO -->
283     <sect1><title>Frame Buffer Video Mode Database</title>
284!Idrivers/video/fbdev/core/modedb.c
285!Edrivers/video/fbdev/core/modedb.c
286     </sect1>
287     <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
288!Edrivers/video/fbdev/macmodes.c
289     </sect1>
290     <sect1><title>Frame Buffer Fonts</title>
291        <para>
292           Refer to the file lib/fonts/fonts.c for more information.
293        </para>
294<!-- FIXME: Removed for now since no structured comments in source
295X!Ilib/fonts/fonts.c
296-->
297     </sect1>
298  </chapter>
299
300  <chapter id="input_subsystem">
301     <title>Input Subsystem</title>
302     <sect1><title>Input core</title>
303!Iinclude/linux/input.h
304!Edrivers/input/input.c
305!Edrivers/input/ff-core.c
306!Edrivers/input/ff-memless.c
307     </sect1>
308     <sect1><title>Multitouch Library</title>
309!Iinclude/linux/input/mt.h
310!Edrivers/input/input-mt.c
311     </sect1>
312     <sect1><title>Polled input devices</title>
313!Iinclude/linux/input-polldev.h
314!Edrivers/input/input-polldev.c
315     </sect1>
316     <sect1><title>Matrix keyboars/keypads</title>
317!Iinclude/linux/input/matrix_keypad.h
318     </sect1>
319     <sect1><title>Sparse keymap support</title>
320!Iinclude/linux/input/sparse-keymap.h
321!Edrivers/input/sparse-keymap.c
322     </sect1>
323  </chapter>
324
325  <chapter id="spi">
326      <title>Serial Peripheral Interface (SPI)</title>
327  <para>
328	SPI is the "Serial Peripheral Interface", widely used with
329	embedded systems because it is a simple and efficient
330	interface:  basically a multiplexed shift register.
331	Its three signal wires hold a clock (SCK, often in the range
332	of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
333	a "Master In, Slave Out" (MISO) data line.
334	SPI is a full duplex protocol; for each bit shifted out the
335	MOSI line (one per clock) another is shifted in on the MISO line.
336	Those bits are assembled into words of various sizes on the
337	way to and from system memory.
338	An additional chipselect line is usually active-low (nCS);
339	four signals are normally used for each peripheral, plus
340	sometimes an interrupt.
341  </para>
342  <para>
343	The SPI bus facilities listed here provide a generalized
344	interface to declare SPI busses and devices, manage them
345	according to the standard Linux driver model, and perform
346	input/output operations.
347	At this time, only "master" side interfaces are supported,
348	where Linux talks to SPI peripherals and does not implement
349	such a peripheral itself.
350	(Interfaces to support implementing SPI slaves would
351	necessarily look different.)
352  </para>
353  <para>
354	The programming interface is structured around two kinds of driver,
355	and two kinds of device.
356	A "Controller Driver" abstracts the controller hardware, which may
357	be as simple as a set of GPIO pins or as complex as a pair of FIFOs
358	connected to dual DMA engines on the other side of the SPI shift
359	register (maximizing throughput).  Such drivers bridge between
360	whatever bus they sit on (often the platform bus) and SPI, and
361	expose the SPI side of their device as a
362	<structname>struct spi_master</structname>.
363	SPI devices are children of that master, represented as a
364	<structname>struct spi_device</structname> and manufactured from
365	<structname>struct spi_board_info</structname> descriptors which
366	are usually provided by board-specific initialization code.
367	A <structname>struct spi_driver</structname> is called a
368	"Protocol Driver", and is bound to a spi_device using normal
369	driver model calls.
370  </para>
371  <para>
372	The I/O model is a set of queued messages.  Protocol drivers
373	submit one or more <structname>struct spi_message</structname>
374	objects, which are processed and completed asynchronously.
375	(There are synchronous wrappers, however.)  Messages are
376	built from one or more <structname>struct spi_transfer</structname>
377	objects, each of which wraps a full duplex SPI transfer.
378	A variety of protocol tweaking options are needed, because
379	different chips adopt very different policies for how they
380	use the bits transferred with SPI.
381  </para>
382!Iinclude/linux/spi/spi.h
383!Fdrivers/spi/spi.c spi_register_board_info
384!Edrivers/spi/spi.c
385  </chapter>
386
387  <chapter id="i2c">
388     <title>I<superscript>2</superscript>C and SMBus Subsystem</title>
389
390     <para>
391	I<superscript>2</superscript>C (or without fancy typography, "I2C")
392	is an acronym for the "Inter-IC" bus, a simple bus protocol which is
393	widely used where low data rate communications suffice.
394	Since it's also a licensed trademark, some vendors use another
395	name (such as "Two-Wire Interface", TWI) for the same bus.
396	I2C only needs two signals (SCL for clock, SDA for data), conserving
397	board real estate and minimizing signal quality issues.
398	Most I2C devices use seven bit addresses, and bus speeds of up
399	to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet
400	found wide use.
401	I2C is a multi-master bus; open drain signaling is used to
402	arbitrate between masters, as well as to handshake and to
403	synchronize clocks from slower clients.
404     </para>
405
406     <para>
407	The Linux I2C programming interfaces support only the master
408	side of bus interactions, not the slave side.
409	The programming interface is structured around two kinds of driver,
410	and two kinds of device.
411	An I2C "Adapter Driver" abstracts the controller hardware; it binds
412	to a physical device (perhaps a PCI device or platform_device) and
413	exposes a <structname>struct i2c_adapter</structname> representing
414	each I2C bus segment it manages.
415	On each I2C bus segment will be I2C devices represented by a
416	<structname>struct i2c_client</structname>.  Those devices will
417	be bound to a <structname>struct i2c_driver</structname>,
418	which should follow the standard Linux driver model.
419	(At this writing, a legacy model is more widely used.)
420	There are functions to perform various I2C protocol operations; at
421	this writing all such functions are usable only from task context.
422     </para>
423
424     <para>
425	The System Management Bus (SMBus) is a sibling protocol.  Most SMBus
426	systems are also I2C conformant.  The electrical constraints are
427	tighter for SMBus, and it standardizes particular protocol messages
428	and idioms.  Controllers that support I2C can also support most
429	SMBus operations, but SMBus controllers don't support all the protocol
430	options that an I2C controller will.
431	There are functions to perform various SMBus protocol operations,
432	either using I2C primitives or by issuing SMBus commands to
433	i2c_adapter devices which don't support those I2C operations.
434     </para>
435
436!Iinclude/linux/i2c.h
437!Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info
438!Edrivers/i2c/i2c-core.c
439  </chapter>
440
441  <chapter id="hsi">
442     <title>High Speed Synchronous Serial Interface (HSI)</title>
443
444     <para>
445	High Speed Synchronous Serial Interface (HSI) is a
446	serial interface mainly used for connecting application
447	engines (APE) with cellular modem engines (CMT) in cellular
448	handsets.
449
450	HSI provides multiplexing for up to 16 logical channels,
451	low-latency and full duplex communication.
452     </para>
453
454!Iinclude/linux/hsi/hsi.h
455!Edrivers/hsi/hsi.c
456  </chapter>
457
458</book>
459