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" []>
5 <book id="LinuxKernelAPI">
7 <title>The Linux Kernel API</title>
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
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.
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,
33 For more details see the file COPYING in the source
34 distribution of Linux.
42 <title>Data Types</title>
43 <sect1><title>Doubly Linked Lists</title>
44 !Iinclude/linux/list.h
49 <title>Basic C Library Functions</title>
52 When writing drivers, you cannot in general use routines which are
53 from the C Library. Some of the functions have been found generally
54 useful and they are listed below. The behaviour of these functions
55 may vary slightly from those defined by ANSI, and these deviations
56 are noted in the text.
59 <sect1><title>String Conversions</title>
61 <?xmlif if excludeextra='1'?>
63 !Finclude/linux/kernel.h kstrtol
64 !Finclude/linux/kernel.h kstrtoul
68 <sect1><title>String Manipulation</title>
69 <!-- All functions are exported at now
74 <sect1><title>Bit Operations</title>
75 !Iarch/x86/include/asm/bitops.h
79 <chapter id="kernel-lib">
80 <title>Basic Kernel Library Functions</title>
83 The Linux kernel provides more basic utility functions.
86 <sect1><title>Bitmap Operations</title>
91 <sect1><title>Command-line Parsing</title>
95 <sect1 id="crc"><title>CRC Functions</title>
103 <sect1 id="idr"><title>idr/ida Functions</title>
104 !Pinclude/linux/idr.h idr sync
105 !Plib/idr.c IDA description
111 <title>Memory Management in Linux</title>
112 <sect1><title>The Slab Cache</title>
113 !Iinclude/linux/slab.h
117 <sect1><title>User Space Memory Access</title>
118 !Iarch/x86/include/asm/uaccess_32.h
119 !Earch/x86/lib/usercopy_32.c
121 <sect1><title>More Memory Management Functions</title>
129 !Emm/page-writeback.c
136 <title>Kernel IPC facilities</title>
138 <sect1><title>IPC utilities</title>
144 <title>FIFO Buffer</title>
145 <sect1><title>kfifo interface</title>
146 !Iinclude/linux/kfifo.h
150 <chapter id="relayfs">
151 <title>relay interface support</title>
154 Relay interface support
155 is designed to provide an efficient mechanism for tools and
156 facilities to relay large amounts of data from kernel space to
160 <sect1><title>relay interface</title>
166 <chapter id="modload">
167 <title>Module Support</title>
168 <sect1><title>Module Loading</title>
171 <sect1><title>Inter Module support</title>
173 Refer to the file kernel/module.c for more information.
175 <!-- FIXME: Removed for now since no structured comments in source
181 <chapter id="hardware">
182 <title>Hardware Interfaces</title>
183 <sect1><title>Interrupt Handling</title>
184 <?xmlif if excludeextra='1'?>
186 !Ekernel/irq/manage.c
190 <sect1><title>DMA Channels</title>
194 <sect1><title>Resources Management</title>
199 <sect1><title>MTRR Handling</title>
200 !Earch/x86/kernel/cpu/mtrr/main.c
203 <sect1><title>PCI Support Library</title>
205 !Edrivers/pci/pci-driver.c
206 !Edrivers/pci/remove.c
207 !Edrivers/pci/search.c
210 !Edrivers/pci/access.c
212 !Edrivers/pci/htirq.c
213 <!-- FIXME: Removed for now since no structured comments in source
214 X!Edrivers/pci/hotplug.c
216 !Edrivers/pci/probe.c
220 !Idrivers/pci/pci-sysfs.c
222 <sect1><title>PCI Hotplug Support Library</title>
223 !Edrivers/pci/hotplug/pci_hotplug_core.c
227 <chapter id="firmware">
228 <title>Firmware Interfaces</title>
229 <sect1><title>DMI Interfaces</title>
230 !Edrivers/firmware/dmi_scan.c
232 <sect1><title>EDD Interfaces</title>
233 !Idrivers/firmware/edd.c
237 <chapter id="security">
238 <title>Security Framework</title>
239 !Isecurity/security.c
244 <title>Audit Interfaces</title>
247 !Ikernel/auditfilter.c
250 <chapter id="accounting">
251 <title>Accounting Framework</title>
255 <chapter id="blkdev">
256 <title>Block Devices</title>
261 !Eblock/blk-settings.c
267 !Eblock/blk-integrity.c
268 !Ikernel/trace/blktrace.c
273 <chapter id="chrdev">
274 <title>Char devices</title>
278 <chapter id="miscdev">
279 <title>Miscellaneous Devices</title>
280 !Edrivers/char/misc.c
284 <title>Clock Framework</title>
287 The clock framework defines programming interfaces to support
288 software management of the system clock tree.
289 This framework is widely used with System-On-Chip (SOC) platforms
290 to support power management and various devices which may need
292 Note that these "clocks" don't relate to timekeeping or real
293 time clocks (RTCs), each of which have separate frameworks.
294 These <structname>struct clk</structname> instances may be used
295 to manage for example a 96 MHz signal that is used to shift bits
296 into and out of peripherals or busses, or otherwise trigger
297 synchronous state machine transitions in system hardware.
301 Power management is supported by explicit software clock gating:
302 unused clocks are disabled, so the system doesn't waste power
303 changing the state of transistors that aren't in active use.
304 On some systems this may be backed by hardware clock gating,
305 where clocks are gated without being disabled in software.
306 Sections of chips that are powered but not clocked may be able
307 to retain their last state.
308 This low power state is often called a <emphasis>retention
310 This mode still incurs leakage currents, especially with finer
311 circuit geometries, but for CMOS circuits power is mostly used
312 by clocked state changes.
316 Power-aware drivers only enable their clocks when the device
317 they manage is in active use. Also, system sleep states often
318 differ according to which clock domains are active: while a
319 "standby" state may allow wakeup from several active domains, a
320 "mem" (suspend-to-RAM) state may require a more wholesale shutdown
321 of clocks derived from higher speed PLLs and oscillators, limiting
322 the number of possible wakeup event sources. A driver's suspend
323 method may need to be aware of system-specific clock constraints
324 on the target sleep state.
328 Some platforms support programmable clock generators. These
329 can be used by external chips of various kinds, such as other
330 CPUs, multimedia codecs, and devices with strict requirements
331 for interface clocking.
334 !Iinclude/linux/clk.h