| <?xml version="1.0" encoding="UTF-8"?> | 
 | <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" | 
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 |  | 
 | <book id="LinuxKernelAPI"> | 
 |  <bookinfo> | 
 |   <title>The Linux Kernel API</title> | 
 |    | 
 |   <legalnotice> | 
 |    <para> | 
 |      This documentation is free software; you can redistribute | 
 |      it and/or modify it under the terms of the GNU General Public | 
 |      License as published by the Free Software Foundation; either | 
 |      version 2 of the License, or (at your option) any later | 
 |      version. | 
 |    </para> | 
 |        | 
 |    <para> | 
 |      This program is distributed in the hope that it will be | 
 |      useful, but WITHOUT ANY WARRANTY; without even the implied | 
 |      warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. | 
 |      See the GNU General Public License for more details. | 
 |    </para> | 
 |        | 
 |    <para> | 
 |      You should have received a copy of the GNU General Public | 
 |      License along with this program; if not, write to the Free | 
 |      Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, | 
 |      MA 02111-1307 USA | 
 |    </para> | 
 |        | 
 |    <para> | 
 |      For more details see the file COPYING in the source | 
 |      distribution of Linux. | 
 |    </para> | 
 |   </legalnotice> | 
 |  </bookinfo> | 
 |  | 
 | <toc></toc> | 
 |  | 
 |   <chapter id="adt"> | 
 |      <title>Data Types</title> | 
 |      <sect1><title>Doubly Linked Lists</title> | 
 | !Iinclude/linux/list.h | 
 |      </sect1> | 
 |   </chapter> | 
 |  | 
 |   <chapter id="libc"> | 
 |      <title>Basic C Library Functions</title> | 
 |  | 
 |      <para> | 
 |        When writing drivers, you cannot in general use routines which are | 
 |        from the C Library.  Some of the functions have been found generally | 
 |        useful and they are listed below.  The behaviour of these functions | 
 |        may vary slightly from those defined by ANSI, and these deviations | 
 |        are noted in the text. | 
 |      </para> | 
 |  | 
 |      <sect1><title>String Conversions</title> | 
 | !Elib/vsprintf.c | 
 | !Finclude/linux/kernel.h kstrtol | 
 | !Finclude/linux/kernel.h kstrtoul | 
 | !Elib/kstrtox.c | 
 |      </sect1> | 
 |      <sect1><title>String Manipulation</title> | 
 | <!-- All functions are exported at now | 
 | X!Ilib/string.c | 
 |  --> | 
 | !Elib/string.c | 
 |      </sect1> | 
 |      <sect1><title>Bit Operations</title> | 
 | !Iarch/x86/include/asm/bitops.h | 
 |      </sect1> | 
 |   </chapter> | 
 |  | 
 |   <chapter id="kernel-lib"> | 
 |      <title>Basic Kernel Library Functions</title> | 
 |  | 
 |      <para> | 
 |        The Linux kernel provides more basic utility functions. | 
 |      </para> | 
 |  | 
 |      <sect1><title>Bitmap Operations</title> | 
 | !Elib/bitmap.c | 
 | !Ilib/bitmap.c | 
 |      </sect1> | 
 |  | 
 |      <sect1><title>Command-line Parsing</title> | 
 | !Elib/cmdline.c | 
 |      </sect1> | 
 |  | 
 |      <sect1 id="crc"><title>CRC Functions</title> | 
 | !Elib/crc7.c | 
 | !Elib/crc16.c | 
 | !Elib/crc-itu-t.c | 
 | !Elib/crc32.c | 
 | !Elib/crc-ccitt.c | 
 |      </sect1> | 
 |  | 
 |      <sect1 id="idr"><title>idr/ida Functions</title> | 
 | !Pinclude/linux/idr.h idr sync | 
 | !Plib/idr.c IDA description | 
 | !Elib/idr.c | 
 |      </sect1> | 
 |   </chapter> | 
 |  | 
 |   <chapter id="mm"> | 
 |      <title>Memory Management in Linux</title> | 
 |      <sect1><title>The Slab Cache</title> | 
 | !Iinclude/linux/slab.h | 
 | !Emm/slab.c | 
 |      </sect1> | 
 |      <sect1><title>User Space Memory Access</title> | 
 | !Iarch/x86/include/asm/uaccess_32.h | 
 | !Earch/x86/lib/usercopy_32.c | 
 |      </sect1> | 
 |      <sect1><title>More Memory Management Functions</title> | 
 | !Emm/readahead.c | 
 | !Emm/filemap.c | 
 | !Emm/memory.c | 
 | !Emm/vmalloc.c | 
 | !Imm/page_alloc.c | 
 | !Emm/mempool.c | 
 | !Emm/dmapool.c | 
 | !Emm/page-writeback.c | 
 | !Emm/truncate.c | 
 |      </sect1> | 
 |   </chapter> | 
 |  | 
 |  | 
 |   <chapter id="ipc"> | 
 |      <title>Kernel IPC facilities</title> | 
 |  | 
 |      <sect1><title>IPC utilities</title> | 
 | !Iipc/util.c | 
 |      </sect1> | 
 |   </chapter> | 
 |  | 
 |   <chapter id="kfifo"> | 
 |      <title>FIFO Buffer</title> | 
 |      <sect1><title>kfifo interface</title> | 
 | !Iinclude/linux/kfifo.h | 
 |      </sect1> | 
 |   </chapter> | 
 |  | 
 |   <chapter id="relayfs"> | 
 |      <title>relay interface support</title> | 
 |  | 
 |      <para> | 
 | 	Relay interface support | 
 | 	is designed to provide an efficient mechanism for tools and | 
 | 	facilities to relay large amounts of data from kernel space to | 
 | 	user space. | 
 |      </para> | 
 |  | 
 |      <sect1><title>relay interface</title> | 
 | !Ekernel/relay.c | 
 | !Ikernel/relay.c | 
 |      </sect1> | 
 |   </chapter> | 
 |  | 
 |   <chapter id="modload"> | 
 |      <title>Module Support</title> | 
 |      <sect1><title>Module Loading</title> | 
 | !Ekernel/kmod.c | 
 |      </sect1> | 
 |      <sect1><title>Inter Module support</title> | 
 |         <para> | 
 |            Refer to the file kernel/module.c for more information. | 
 |         </para> | 
 | <!-- FIXME: Removed for now since no structured comments in source | 
 | X!Ekernel/module.c | 
 | --> | 
 |      </sect1> | 
 |   </chapter> | 
 |  | 
 |   <chapter id="hardware"> | 
 |      <title>Hardware Interfaces</title> | 
 |      <sect1><title>Interrupt Handling</title> | 
 | !Ekernel/irq/manage.c | 
 |      </sect1> | 
 |  | 
 |      <sect1><title>DMA Channels</title> | 
 | !Ekernel/dma.c | 
 |      </sect1> | 
 |  | 
 |      <sect1><title>Resources Management</title> | 
 | !Ikernel/resource.c | 
 | !Ekernel/resource.c | 
 |      </sect1> | 
 |  | 
 |      <sect1><title>MTRR Handling</title> | 
 | !Earch/x86/kernel/cpu/mtrr/main.c | 
 |      </sect1> | 
 |  | 
 |      <sect1><title>PCI Support Library</title> | 
 | !Edrivers/pci/pci.c | 
 | !Edrivers/pci/pci-driver.c | 
 | !Edrivers/pci/remove.c | 
 | !Edrivers/pci/search.c | 
 | !Edrivers/pci/msi.c | 
 | !Edrivers/pci/bus.c | 
 | !Edrivers/pci/access.c | 
 | !Edrivers/pci/irq.c | 
 | !Edrivers/pci/htirq.c | 
 | <!-- FIXME: Removed for now since no structured comments in source | 
 | X!Edrivers/pci/hotplug.c | 
 | --> | 
 | !Edrivers/pci/probe.c | 
 | !Edrivers/pci/slot.c | 
 | !Edrivers/pci/rom.c | 
 | !Edrivers/pci/iov.c | 
 | !Idrivers/pci/pci-sysfs.c | 
 |      </sect1> | 
 |      <sect1><title>PCI Hotplug Support Library</title> | 
 | !Edrivers/pci/hotplug/pci_hotplug_core.c | 
 |      </sect1> | 
 |   </chapter> | 
 |  | 
 |   <chapter id="firmware"> | 
 |      <title>Firmware Interfaces</title> | 
 |      <sect1><title>DMI Interfaces</title> | 
 | !Edrivers/firmware/dmi_scan.c | 
 |      </sect1> | 
 |      <sect1><title>EDD Interfaces</title> | 
 | !Idrivers/firmware/edd.c | 
 |      </sect1> | 
 |   </chapter> | 
 |  | 
 |   <chapter id="security"> | 
 |      <title>Security Framework</title> | 
 | !Isecurity/security.c | 
 | !Esecurity/inode.c | 
 |   </chapter> | 
 |  | 
 |   <chapter id="audit"> | 
 |      <title>Audit Interfaces</title> | 
 | !Ekernel/audit.c | 
 | !Ikernel/auditsc.c | 
 | !Ikernel/auditfilter.c | 
 |   </chapter> | 
 |  | 
 |   <chapter id="accounting"> | 
 |      <title>Accounting Framework</title> | 
 | !Ikernel/acct.c | 
 |   </chapter> | 
 |  | 
 |   <chapter id="blkdev"> | 
 |      <title>Block Devices</title> | 
 | !Eblock/blk-core.c | 
 | !Iblock/blk-core.c | 
 | !Eblock/blk-map.c | 
 | !Iblock/blk-sysfs.c | 
 | !Eblock/blk-settings.c | 
 | !Eblock/blk-exec.c | 
 | !Eblock/blk-flush.c | 
 | !Eblock/blk-lib.c | 
 | !Eblock/blk-tag.c | 
 | !Iblock/blk-tag.c | 
 | !Eblock/blk-integrity.c | 
 | !Ikernel/trace/blktrace.c | 
 | !Iblock/genhd.c | 
 | !Eblock/genhd.c | 
 |   </chapter> | 
 |  | 
 |   <chapter id="chrdev"> | 
 | 	<title>Char devices</title> | 
 | !Efs/char_dev.c | 
 |   </chapter> | 
 |  | 
 |   <chapter id="miscdev"> | 
 |      <title>Miscellaneous Devices</title> | 
 | !Edrivers/char/misc.c | 
 |   </chapter> | 
 |  | 
 |   <chapter id="clk"> | 
 |      <title>Clock Framework</title> | 
 |  | 
 |      <para> | 
 | 	The clock framework defines programming interfaces to support | 
 | 	software management of the system clock tree. | 
 | 	This framework is widely used with System-On-Chip (SOC) platforms | 
 | 	to support power management and various devices which may need | 
 | 	custom clock rates. | 
 | 	Note that these "clocks" don't relate to timekeeping or real | 
 | 	time clocks (RTCs), each of which have separate frameworks. | 
 | 	These <structname>struct clk</structname> instances may be used | 
 | 	to manage for example a 96 MHz signal that is used to shift bits | 
 | 	into and out of peripherals or busses, or otherwise trigger | 
 | 	synchronous state machine transitions in system hardware. | 
 |      </para> | 
 |  | 
 |      <para> | 
 | 	Power management is supported by explicit software clock gating: | 
 | 	unused clocks are disabled, so the system doesn't waste power | 
 | 	changing the state of transistors that aren't in active use. | 
 | 	On some systems this may be backed by hardware clock gating, | 
 | 	where clocks are gated without being disabled in software. | 
 | 	Sections of chips that are powered but not clocked may be able | 
 | 	to retain their last state. | 
 | 	This low power state is often called a <emphasis>retention | 
 | 	mode</emphasis>. | 
 | 	This mode still incurs leakage currents, especially with finer | 
 | 	circuit geometries, but for CMOS circuits power is mostly used | 
 | 	by clocked state changes. | 
 |      </para> | 
 |  | 
 |      <para> | 
 | 	Power-aware drivers only enable their clocks when the device | 
 | 	they manage is in active use.  Also, system sleep states often | 
 | 	differ according to which clock domains are active:  while a | 
 | 	"standby" state may allow wakeup from several active domains, a | 
 | 	"mem" (suspend-to-RAM) state may require a more wholesale shutdown | 
 | 	of clocks derived from higher speed PLLs and oscillators, limiting | 
 | 	the number of possible wakeup event sources.  A driver's suspend | 
 | 	method may need to be aware of system-specific clock constraints | 
 | 	on the target sleep state. | 
 |      </para> | 
 |  | 
 |      <para> | 
 |         Some platforms support programmable clock generators.  These | 
 | 	can be used by external chips of various kinds, such as other | 
 | 	CPUs, multimedia codecs, and devices with strict requirements | 
 | 	for interface clocking. | 
 |      </para> | 
 |  | 
 | !Iinclude/linux/clk.h | 
 |   </chapter> | 
 |  | 
 | </book> |