| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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="LinuxKernelAPI"> | 
|  | 6 | <bookinfo> | 
|  | 7 | <title>The Linux Kernel API</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 |  | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 41 | <chapter id="adt"> | 
|  | 42 | <title>Data Types</title> | 
|  | 43 | <sect1><title>Doubly Linked Lists</title> | 
|  | 44 | !Iinclude/linux/list.h | 
|  | 45 | </sect1> | 
|  | 46 | </chapter> | 
|  | 47 |  | 
|  | 48 | <chapter id="libc"> | 
|  | 49 | <title>Basic C Library Functions</title> | 
|  | 50 |  | 
|  | 51 | <para> | 
|  | 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. | 
|  | 57 | </para> | 
|  | 58 |  | 
|  | 59 | <sect1><title>String Conversions</title> | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 60 | !Elib/vsprintf.c | 
|  | 61 | </sect1> | 
|  | 62 | <sect1><title>String Manipulation</title> | 
| Pavel Pisa | 4dc3b16 | 2005-05-01 08:59:25 -0700 | [diff] [blame] | 63 | <!-- All functions are exported at now | 
|  | 64 | X!Ilib/string.c | 
|  | 65 | --> | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 66 | !Elib/string.c | 
|  | 67 | </sect1> | 
|  | 68 | <sect1><title>Bit Operations</title> | 
| Randy Dunlap | a1a739c | 2008-10-25 17:24:36 -0700 | [diff] [blame] | 69 | !Iarch/x86/include/asm/bitops.h | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 70 | </sect1> | 
| Randy Dunlap | 28e83ba | 2006-06-25 05:48:58 -0700 | [diff] [blame] | 71 | </chapter> | 
|  | 72 |  | 
|  | 73 | <chapter id="kernel-lib"> | 
|  | 74 | <title>Basic Kernel Library Functions</title> | 
|  | 75 |  | 
|  | 76 | <para> | 
|  | 77 | The Linux kernel provides more basic utility functions. | 
|  | 78 | </para> | 
|  | 79 |  | 
| Randy Dunlap | 6e1907ff | 2006-06-25 05:48:57 -0700 | [diff] [blame] | 80 | <sect1><title>Bitmap Operations</title> | 
|  | 81 | !Elib/bitmap.c | 
|  | 82 | !Ilib/bitmap.c | 
|  | 83 | </sect1> | 
| Randy Dunlap | 28e83ba | 2006-06-25 05:48:58 -0700 | [diff] [blame] | 84 |  | 
|  | 85 | <sect1><title>Command-line Parsing</title> | 
|  | 86 | !Elib/cmdline.c | 
|  | 87 | </sect1> | 
| Randy Dunlap | 2f72100 | 2006-06-25 05:48:59 -0700 | [diff] [blame] | 88 |  | 
| Jan Nikitenko | ad24152 | 2007-07-17 04:04:03 -0700 | [diff] [blame] | 89 | <sect1 id="crc"><title>CRC Functions</title> | 
|  | 90 | !Elib/crc7.c | 
| Randy Dunlap | 2f72100 | 2006-06-25 05:48:59 -0700 | [diff] [blame] | 91 | !Elib/crc16.c | 
| Jan Nikitenko | ad24152 | 2007-07-17 04:04:03 -0700 | [diff] [blame] | 92 | !Elib/crc-itu-t.c | 
| Randy Dunlap | 2f72100 | 2006-06-25 05:48:59 -0700 | [diff] [blame] | 93 | !Elib/crc32.c | 
|  | 94 | !Elib/crc-ccitt.c | 
|  | 95 | </sect1> | 
| Randy Dunlap | 56083ab | 2010-10-26 14:19:08 -0700 | [diff] [blame] | 96 |  | 
|  | 97 | <sect1 id="idr"><title>idr/ida Functions</title> | 
|  | 98 | !Pinclude/linux/idr.h idr sync | 
|  | 99 | !Plib/idr.c IDA description | 
|  | 100 | !Elib/idr.c | 
|  | 101 | </sect1> | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 102 | </chapter> | 
|  | 103 |  | 
|  | 104 | <chapter id="mm"> | 
|  | 105 | <title>Memory Management in Linux</title> | 
|  | 106 | <sect1><title>The Slab Cache</title> | 
| Paul Drynoff | 800590f | 2006-06-23 02:03:48 -0700 | [diff] [blame] | 107 | !Iinclude/linux/slab.h | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 108 | !Emm/slab.c | 
|  | 109 | </sect1> | 
|  | 110 | <sect1><title>User Space Memory Access</title> | 
| Randy Dunlap | a1a739c | 2008-10-25 17:24:36 -0700 | [diff] [blame] | 111 | !Iarch/x86/include/asm/uaccess_32.h | 
| Randy Dunlap | f3cf31a | 2007-10-12 21:17:23 -0700 | [diff] [blame] | 112 | !Earch/x86/lib/usercopy_32.c | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 113 | </sect1> | 
| Pavel Pisa | 4dc3b16 | 2005-05-01 08:59:25 -0700 | [diff] [blame] | 114 | <sect1><title>More Memory Management Functions</title> | 
| Pavel Pisa | 4dc3b16 | 2005-05-01 08:59:25 -0700 | [diff] [blame] | 115 | !Emm/readahead.c | 
|  | 116 | !Emm/filemap.c | 
|  | 117 | !Emm/memory.c | 
|  | 118 | !Emm/vmalloc.c | 
| Randy Dunlap | 88ca3b9 | 2006-10-04 02:15:25 -0700 | [diff] [blame] | 119 | !Imm/page_alloc.c | 
| Pavel Pisa | 4dc3b16 | 2005-05-01 08:59:25 -0700 | [diff] [blame] | 120 | !Emm/mempool.c | 
| Randy Dunlap | a80a438 | 2008-02-06 16:29:55 -0800 | [diff] [blame] | 121 | !Emm/dmapool.c | 
| Pavel Pisa | 4dc3b16 | 2005-05-01 08:59:25 -0700 | [diff] [blame] | 122 | !Emm/page-writeback.c | 
|  | 123 | !Emm/truncate.c | 
|  | 124 | </sect1> | 
|  | 125 | </chapter> | 
|  | 126 |  | 
|  | 127 |  | 
|  | 128 | <chapter id="ipc"> | 
|  | 129 | <title>Kernel IPC facilities</title> | 
|  | 130 |  | 
|  | 131 | <sect1><title>IPC utilities</title> | 
|  | 132 | !Iipc/util.c | 
|  | 133 | </sect1> | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 134 | </chapter> | 
|  | 135 |  | 
|  | 136 | <chapter id="kfifo"> | 
|  | 137 | <title>FIFO Buffer</title> | 
|  | 138 | <sect1><title>kfifo interface</title> | 
|  | 139 | !Iinclude/linux/kfifo.h | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 140 | </sect1> | 
|  | 141 | </chapter> | 
|  | 142 |  | 
| Randy Dunlap | 5b217fa | 2006-09-29 01:59:10 -0700 | [diff] [blame] | 143 | <chapter id="relayfs"> | 
|  | 144 | <title>relay interface support</title> | 
|  | 145 |  | 
|  | 146 | <para> | 
|  | 147 | Relay interface support | 
|  | 148 | is designed to provide an efficient mechanism for tools and | 
|  | 149 | facilities to relay large amounts of data from kernel space to | 
|  | 150 | user space. | 
|  | 151 | </para> | 
|  | 152 |  | 
|  | 153 | <sect1><title>relay interface</title> | 
|  | 154 | !Ekernel/relay.c | 
|  | 155 | !Ikernel/relay.c | 
|  | 156 | </sect1> | 
|  | 157 | </chapter> | 
|  | 158 |  | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 159 | <chapter id="modload"> | 
|  | 160 | <title>Module Support</title> | 
|  | 161 | <sect1><title>Module Loading</title> | 
|  | 162 | !Ekernel/kmod.c | 
|  | 163 | </sect1> | 
|  | 164 | <sect1><title>Inter Module support</title> | 
|  | 165 | <para> | 
|  | 166 | Refer to the file kernel/module.c for more information. | 
|  | 167 | </para> | 
|  | 168 | <!-- FIXME: Removed for now since no structured comments in source | 
|  | 169 | X!Ekernel/module.c | 
|  | 170 | --> | 
|  | 171 | </sect1> | 
|  | 172 | </chapter> | 
|  | 173 |  | 
|  | 174 | <chapter id="hardware"> | 
|  | 175 | <title>Hardware Interfaces</title> | 
|  | 176 | <sect1><title>Interrupt Handling</title> | 
| Randy Dunlap | 8f2709b | 2005-11-07 01:01:05 -0800 | [diff] [blame] | 177 | !Ekernel/irq/manage.c | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 178 | </sect1> | 
|  | 179 |  | 
| Randy Dunlap | eed34d0 | 2006-10-03 01:13:50 -0700 | [diff] [blame] | 180 | <sect1><title>DMA Channels</title> | 
|  | 181 | !Ekernel/dma.c | 
|  | 182 | </sect1> | 
|  | 183 |  | 
| Pavel Pisa | 4dc3b16 | 2005-05-01 08:59:25 -0700 | [diff] [blame] | 184 | <sect1><title>Resources Management</title> | 
| Randy Dunlap | 2b54960 | 2006-07-30 03:03:40 -0700 | [diff] [blame] | 185 | !Ikernel/resource.c | 
| Randy Dunlap | e1ca66d | 2006-10-03 01:13:51 -0700 | [diff] [blame] | 186 | !Ekernel/resource.c | 
| Pavel Pisa | 4dc3b16 | 2005-05-01 08:59:25 -0700 | [diff] [blame] | 187 | </sect1> | 
|  | 188 |  | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 189 | <sect1><title>MTRR Handling</title> | 
| Randy Dunlap | f3cf31a | 2007-10-12 21:17:23 -0700 | [diff] [blame] | 190 | !Earch/x86/kernel/cpu/mtrr/main.c | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 191 | </sect1> | 
| Randy Dunlap | b0ef371 | 2006-06-25 05:49:18 -0700 | [diff] [blame] | 192 |  | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 193 | <sect1><title>PCI Support Library</title> | 
|  | 194 | !Edrivers/pci/pci.c | 
| Pavel Pisa | 4dc3b16 | 2005-05-01 08:59:25 -0700 | [diff] [blame] | 195 | !Edrivers/pci/pci-driver.c | 
|  | 196 | !Edrivers/pci/remove.c | 
| Randy Dunlap | d75763d | 2006-07-30 03:03:41 -0700 | [diff] [blame] | 197 | !Edrivers/pci/search.c | 
| Pavel Pisa | 4dc3b16 | 2005-05-01 08:59:25 -0700 | [diff] [blame] | 198 | !Edrivers/pci/msi.c | 
|  | 199 | !Edrivers/pci/bus.c | 
| Randy Dunlap | cffb2fa | 2009-04-10 15:17:50 -0700 | [diff] [blame] | 200 | !Edrivers/pci/access.c | 
|  | 201 | !Edrivers/pci/irq.c | 
|  | 202 | !Edrivers/pci/htirq.c | 
| Randy Dunlap | f05aab8 | 2005-10-23 11:58:19 -0700 | [diff] [blame] | 203 | <!-- FIXME: Removed for now since no structured comments in source | 
|  | 204 | X!Edrivers/pci/hotplug.c | 
|  | 205 | --> | 
| Pavel Pisa | 4dc3b16 | 2005-05-01 08:59:25 -0700 | [diff] [blame] | 206 | !Edrivers/pci/probe.c | 
| Randy Dunlap | cffb2fa | 2009-04-10 15:17:50 -0700 | [diff] [blame] | 207 | !Edrivers/pci/slot.c | 
| Pavel Pisa | 4dc3b16 | 2005-05-01 08:59:25 -0700 | [diff] [blame] | 208 | !Edrivers/pci/rom.c | 
| Yu Zhao | 15b49be | 2009-03-20 11:25:18 +0800 | [diff] [blame] | 209 | !Edrivers/pci/iov.c | 
| Randy Dunlap | cffb2fa | 2009-04-10 15:17:50 -0700 | [diff] [blame] | 210 | !Idrivers/pci/pci-sysfs.c | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 211 | </sect1> | 
|  | 212 | <sect1><title>PCI Hotplug Support Library</title> | 
|  | 213 | !Edrivers/pci/hotplug/pci_hotplug_core.c | 
|  | 214 | </sect1> | 
|  | 215 | <sect1><title>MCA Architecture</title> | 
|  | 216 | <sect2><title>MCA Device Functions</title> | 
|  | 217 | <para> | 
| Randy Dunlap | f3cf31a | 2007-10-12 21:17:23 -0700 | [diff] [blame] | 218 | Refer to the file arch/x86/kernel/mca_32.c for more information. | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 219 | </para> | 
|  | 220 | <!-- FIXME: Removed for now since no structured comments in source | 
| Randy Dunlap | f3cf31a | 2007-10-12 21:17:23 -0700 | [diff] [blame] | 221 | X!Earch/x86/kernel/mca_32.c | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 222 | --> | 
|  | 223 | </sect2> | 
|  | 224 | <sect2><title>MCA Bus DMA</title> | 
| Randy Dunlap | a1a739c | 2008-10-25 17:24:36 -0700 | [diff] [blame] | 225 | !Iarch/x86/include/asm/mca_dma.h | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 226 | </sect2> | 
|  | 227 | </sect1> | 
|  | 228 | </chapter> | 
|  | 229 |  | 
| Randy Dunlap | b0ef371 | 2006-06-25 05:49:18 -0700 | [diff] [blame] | 230 | <chapter id="firmware"> | 
|  | 231 | <title>Firmware Interfaces</title> | 
|  | 232 | <sect1><title>DMI Interfaces</title> | 
|  | 233 | !Edrivers/firmware/dmi_scan.c | 
|  | 234 | </sect1> | 
| Randy Dunlap | 6e8c818 | 2007-02-10 01:46:03 -0800 | [diff] [blame] | 235 | <sect1><title>EDD Interfaces</title> | 
|  | 236 | !Idrivers/firmware/edd.c | 
|  | 237 | </sect1> | 
| Randy Dunlap | b0ef371 | 2006-06-25 05:49:18 -0700 | [diff] [blame] | 238 | </chapter> | 
|  | 239 |  | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 240 | <chapter id="security"> | 
|  | 241 | <title>Security Framework</title> | 
| James Morris | 20510f2 | 2007-10-16 23:31:32 -0700 | [diff] [blame] | 242 | !Isecurity/security.c | 
| Randy Dunlap | 3f23d81 | 2008-08-17 21:44:22 -0700 | [diff] [blame] | 243 | !Esecurity/inode.c | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 244 | </chapter> | 
|  | 245 |  | 
| Randy Dunlap | 862f5f0 | 2006-06-23 02:05:52 -0700 | [diff] [blame] | 246 | <chapter id="audit"> | 
|  | 247 | <title>Audit Interfaces</title> | 
|  | 248 | !Ekernel/audit.c | 
|  | 249 | !Ikernel/auditsc.c | 
|  | 250 | !Ikernel/auditfilter.c | 
|  | 251 | </chapter> | 
|  | 252 |  | 
|  | 253 | <chapter id="accounting"> | 
|  | 254 | <title>Accounting Framework</title> | 
|  | 255 | !Ikernel/acct.c | 
|  | 256 | </chapter> | 
|  | 257 |  | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 258 | <chapter id="blkdev"> | 
|  | 259 | <title>Block Devices</title> | 
| Randy Dunlap | caf03fe | 2008-01-30 11:51:00 -0800 | [diff] [blame] | 260 | !Eblock/blk-core.c | 
| Randy Dunlap | 5d87a05 | 2008-02-20 09:01:22 +0100 | [diff] [blame] | 261 | !Iblock/blk-core.c | 
| Randy Dunlap | caf03fe | 2008-01-30 11:51:00 -0800 | [diff] [blame] | 262 | !Eblock/blk-map.c | 
|  | 263 | !Iblock/blk-sysfs.c | 
|  | 264 | !Eblock/blk-settings.c | 
|  | 265 | !Eblock/blk-exec.c | 
| Mike Snitzer | 4d15290 | 2010-10-21 14:54:19 +0200 | [diff] [blame] | 266 | !Eblock/blk-flush.c | 
|  | 267 | !Eblock/blk-lib.c | 
| Randy Dunlap | caf03fe | 2008-01-30 11:51:00 -0800 | [diff] [blame] | 268 | !Eblock/blk-tag.c | 
| Randy Dunlap | 5d87a05 | 2008-02-20 09:01:22 +0100 | [diff] [blame] | 269 | !Iblock/blk-tag.c | 
| Randy Dunlap | 710027a | 2008-08-19 20:13:11 +0200 | [diff] [blame] | 270 | !Eblock/blk-integrity.c | 
| Randy Dunlap | 88cacbb | 2009-04-05 15:45:34 -0700 | [diff] [blame] | 271 | !Ikernel/trace/blktrace.c | 
| Randy Dunlap | 710027a | 2008-08-19 20:13:11 +0200 | [diff] [blame] | 272 | !Iblock/genhd.c | 
|  | 273 | !Eblock/genhd.c | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 274 | </chapter> | 
|  | 275 |  | 
| Jonathan Corbet | cf3e43d | 2006-09-29 02:00:44 -0700 | [diff] [blame] | 276 | <chapter id="chrdev"> | 
|  | 277 | <title>Char devices</title> | 
|  | 278 | !Efs/char_dev.c | 
|  | 279 | </chapter> | 
|  | 280 |  | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 281 | <chapter id="miscdev"> | 
|  | 282 | <title>Miscellaneous Devices</title> | 
|  | 283 | !Edrivers/char/misc.c | 
|  | 284 | </chapter> | 
|  | 285 |  | 
| David Brownell | e275ac4 | 2008-04-28 02:11:56 -0700 | [diff] [blame] | 286 | <chapter id="clk"> | 
|  | 287 | <title>Clock Framework</title> | 
|  | 288 |  | 
|  | 289 | <para> | 
|  | 290 | The clock framework defines programming interfaces to support | 
|  | 291 | software management of the system clock tree. | 
|  | 292 | This framework is widely used with System-On-Chip (SOC) platforms | 
|  | 293 | to support power management and various devices which may need | 
|  | 294 | custom clock rates. | 
|  | 295 | Note that these "clocks" don't relate to timekeeping or real | 
|  | 296 | time clocks (RTCs), each of which have separate frameworks. | 
|  | 297 | These <structname>struct clk</structname> instances may be used | 
|  | 298 | to manage for example a 96 MHz signal that is used to shift bits | 
|  | 299 | into and out of peripherals or busses, or otherwise trigger | 
|  | 300 | synchronous state machine transitions in system hardware. | 
|  | 301 | </para> | 
|  | 302 |  | 
|  | 303 | <para> | 
|  | 304 | Power management is supported by explicit software clock gating: | 
|  | 305 | unused clocks are disabled, so the system doesn't waste power | 
|  | 306 | changing the state of transistors that aren't in active use. | 
|  | 307 | On some systems this may be backed by hardware clock gating, | 
|  | 308 | where clocks are gated without being disabled in software. | 
|  | 309 | Sections of chips that are powered but not clocked may be able | 
|  | 310 | to retain their last state. | 
|  | 311 | This low power state is often called a <emphasis>retention | 
|  | 312 | mode</emphasis>. | 
|  | 313 | This mode still incurs leakage currents, especially with finer | 
|  | 314 | circuit geometries, but for CMOS circuits power is mostly used | 
|  | 315 | by clocked state changes. | 
|  | 316 | </para> | 
|  | 317 |  | 
|  | 318 | <para> | 
|  | 319 | Power-aware drivers only enable their clocks when the device | 
|  | 320 | they manage is in active use.  Also, system sleep states often | 
|  | 321 | differ according to which clock domains are active:  while a | 
|  | 322 | "standby" state may allow wakeup from several active domains, a | 
|  | 323 | "mem" (suspend-to-RAM) state may require a more wholesale shutdown | 
|  | 324 | of clocks derived from higher speed PLLs and oscillators, limiting | 
|  | 325 | the number of possible wakeup event sources.  A driver's suspend | 
|  | 326 | method may need to be aware of system-specific clock constraints | 
|  | 327 | on the target sleep state. | 
|  | 328 | </para> | 
|  | 329 |  | 
|  | 330 | <para> | 
|  | 331 | Some platforms support programmable clock generators.  These | 
|  | 332 | can be used by external chips of various kinds, such as other | 
|  | 333 | CPUs, multimedia codecs, and devices with strict requirements | 
|  | 334 | for interface clocking. | 
|  | 335 | </para> | 
|  | 336 |  | 
|  | 337 | !Iinclude/linux/clk.h | 
|  | 338 | </chapter> | 
|  | 339 |  | 
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 340 | </book> |