1====================
2The Linux Kernel API
3====================
4
5
6List Management Functions
7=========================
8
9.. kernel-doc:: include/linux/list.h
10   :internal:
11
12Basic C Library Functions
13=========================
14
15When writing drivers, you cannot in general use routines which are from
16the C Library. Some of the functions have been found generally useful
17and they are listed below. The behaviour of these functions may vary
18slightly from those defined by ANSI, and these deviations are noted in
19the text.
20
21String Conversions
22------------------
23
24.. kernel-doc:: lib/vsprintf.c
25   :export:
26
27.. kernel-doc:: include/linux/kernel.h
28   :functions: kstrtol
29
30.. kernel-doc:: include/linux/kernel.h
31   :functions: kstrtoul
32
33.. kernel-doc:: lib/kstrtox.c
34   :export:
35
36.. kernel-doc:: lib/string_helpers.c
37   :export:
38
39String Manipulation
40-------------------
41
42.. kernel-doc:: lib/string.c
43   :export:
44
45.. kernel-doc:: include/linux/string.h
46   :internal:
47
48.. kernel-doc:: mm/util.c
49   :functions: kstrdup kstrdup_const kstrndup kmemdup kmemdup_nul memdup_user
50               vmemdup_user strndup_user memdup_user_nul
51
52Basic Kernel Library Functions
53==============================
54
55The Linux kernel provides more basic utility functions.
56
57Bit Operations
58--------------
59
60.. kernel-doc:: include/asm-generic/bitops/instrumented-atomic.h
61   :internal:
62
63.. kernel-doc:: include/asm-generic/bitops/instrumented-non-atomic.h
64   :internal:
65
66.. kernel-doc:: include/asm-generic/bitops/instrumented-lock.h
67   :internal:
68
69Bitmap Operations
70-----------------
71
72.. kernel-doc:: lib/bitmap.c
73   :doc: bitmap introduction
74
75.. kernel-doc:: include/linux/bitmap.h
76   :doc: declare bitmap
77
78.. kernel-doc:: include/linux/bitmap.h
79   :doc: bitmap overview
80
81.. kernel-doc:: include/linux/bitmap.h
82   :doc: bitmap bitops
83
84.. kernel-doc:: lib/bitmap.c
85   :export:
86
87.. kernel-doc:: lib/bitmap.c
88   :internal:
89
90.. kernel-doc:: include/linux/bitmap.h
91   :internal:
92
93Command-line Parsing
94--------------------
95
96.. kernel-doc:: lib/cmdline.c
97   :export:
98
99Sorting
100-------
101
102.. kernel-doc:: lib/sort.c
103   :export:
104
105.. kernel-doc:: lib/list_sort.c
106   :export:
107
108Text Searching
109--------------
110
111.. kernel-doc:: lib/textsearch.c
112   :doc: ts_intro
113
114.. kernel-doc:: lib/textsearch.c
115   :export:
116
117.. kernel-doc:: include/linux/textsearch.h
118   :functions: textsearch_find textsearch_next \
119               textsearch_get_pattern textsearch_get_pattern_len
120
121CRC and Math Functions in Linux
122===============================
123
124CRC Functions
125-------------
126
127.. kernel-doc:: lib/crc4.c
128   :export:
129
130.. kernel-doc:: lib/crc7.c
131   :export:
132
133.. kernel-doc:: lib/crc8.c
134   :export:
135
136.. kernel-doc:: lib/crc16.c
137   :export:
138
139.. kernel-doc:: lib/crc32.c
140
141.. kernel-doc:: lib/crc-ccitt.c
142   :export:
143
144.. kernel-doc:: lib/crc-itu-t.c
145   :export:
146
147Base 2 log and power Functions
148------------------------------
149
150.. kernel-doc:: include/linux/log2.h
151   :internal:
152
153Integer power Functions
154-----------------------
155
156.. kernel-doc:: lib/math/int_pow.c
157   :export:
158
159.. kernel-doc:: lib/math/int_sqrt.c
160   :export:
161
162Division Functions
163------------------
164
165.. kernel-doc:: include/asm-generic/div64.h
166   :functions: do_div
167
168.. kernel-doc:: include/linux/math64.h
169   :internal:
170
171.. kernel-doc:: lib/math/div64.c
172   :functions: div_s64_rem div64_u64_rem div64_u64 div64_s64
173
174.. kernel-doc:: lib/math/gcd.c
175   :export:
176
177UUID/GUID
178---------
179
180.. kernel-doc:: lib/uuid.c
181   :export:
182
183Kernel IPC facilities
184=====================
185
186IPC utilities
187-------------
188
189.. kernel-doc:: ipc/util.c
190   :internal:
191
192FIFO Buffer
193===========
194
195kfifo interface
196---------------
197
198.. kernel-doc:: include/linux/kfifo.h
199   :internal:
200
201relay interface support
202=======================
203
204Relay interface support is designed to provide an efficient mechanism
205for tools and facilities to relay large amounts of data from kernel
206space to user space.
207
208relay interface
209---------------
210
211.. kernel-doc:: kernel/relay.c
212   :export:
213
214.. kernel-doc:: kernel/relay.c
215   :internal:
216
217Module Support
218==============
219
220Module Loading
221--------------
222
223.. kernel-doc:: kernel/kmod.c
224   :export:
225
226Inter Module support
227--------------------
228
229Refer to the file kernel/module.c for more information.
230
231Hardware Interfaces
232===================
233
234DMA Channels
235------------
236
237.. kernel-doc:: kernel/dma.c
238   :export:
239
240Resources Management
241--------------------
242
243.. kernel-doc:: kernel/resource.c
244   :internal:
245
246.. kernel-doc:: kernel/resource.c
247   :export:
248
249MTRR Handling
250-------------
251
252.. kernel-doc:: arch/x86/kernel/cpu/mtrr/mtrr.c
253   :export:
254
255Security Framework
256==================
257
258.. kernel-doc:: security/security.c
259   :internal:
260
261.. kernel-doc:: security/inode.c
262   :export:
263
264Audit Interfaces
265================
266
267.. kernel-doc:: kernel/audit.c
268   :export:
269
270.. kernel-doc:: kernel/auditsc.c
271   :internal:
272
273.. kernel-doc:: kernel/auditfilter.c
274   :internal:
275
276Accounting Framework
277====================
278
279.. kernel-doc:: kernel/acct.c
280   :internal:
281
282Block Devices
283=============
284
285.. kernel-doc:: block/blk-core.c
286   :export:
287
288.. kernel-doc:: block/blk-core.c
289   :internal:
290
291.. kernel-doc:: block/blk-map.c
292   :export:
293
294.. kernel-doc:: block/blk-sysfs.c
295   :internal:
296
297.. kernel-doc:: block/blk-settings.c
298   :export:
299
300.. kernel-doc:: block/blk-exec.c
301   :export:
302
303.. kernel-doc:: block/blk-flush.c
304   :export:
305
306.. kernel-doc:: block/blk-lib.c
307   :export:
308
309.. kernel-doc:: block/blk-integrity.c
310   :export:
311
312.. kernel-doc:: kernel/trace/blktrace.c
313   :internal:
314
315.. kernel-doc:: block/genhd.c
316   :internal:
317
318.. kernel-doc:: block/genhd.c
319   :export:
320
321Char devices
322============
323
324.. kernel-doc:: fs/char_dev.c
325   :export:
326
327Clock Framework
328===============
329
330The clock framework defines programming interfaces to support software
331management of the system clock tree. This framework is widely used with
332System-On-Chip (SOC) platforms to support power management and various
333devices which may need custom clock rates. Note that these "clocks"
334don't relate to timekeeping or real time clocks (RTCs), each of which
335have separate frameworks. These :c:type:`struct clk <clk>`
336instances may be used to manage for example a 96 MHz signal that is used
337to shift bits into and out of peripherals or busses, or otherwise
338trigger synchronous state machine transitions in system hardware.
339
340Power management is supported by explicit software clock gating: unused
341clocks are disabled, so the system doesn't waste power changing the
342state of transistors that aren't in active use. On some systems this may
343be backed by hardware clock gating, where clocks are gated without being
344disabled in software. Sections of chips that are powered but not clocked
345may be able to retain their last state. This low power state is often
346called a *retention mode*. This mode still incurs leakage currents,
347especially with finer circuit geometries, but for CMOS circuits power is
348mostly used by clocked state changes.
349
350Power-aware drivers only enable their clocks when the device they manage
351is in active use. Also, system sleep states often differ according to
352which clock domains are active: while a "standby" state may allow wakeup
353from several active domains, a "mem" (suspend-to-RAM) state may require
354a more wholesale shutdown of clocks derived from higher speed PLLs and
355oscillators, limiting the number of possible wakeup event sources. A
356driver's suspend method may need to be aware of system-specific clock
357constraints on the target sleep state.
358
359Some platforms support programmable clock generators. These can be used
360by external chips of various kinds, such as other CPUs, multimedia
361codecs, and devices with strict requirements for interface clocking.
362
363.. kernel-doc:: include/linux/clk.h
364   :internal:
365
366Synchronization Primitives
367==========================
368
369Read-Copy Update (RCU)
370----------------------
371
372.. kernel-doc:: include/linux/rcupdate.h
373
374.. kernel-doc:: kernel/rcu/tree.c
375
376.. kernel-doc:: kernel/rcu/tree_exp.h
377
378.. kernel-doc:: kernel/rcu/update.c
379
380.. kernel-doc:: include/linux/srcu.h
381
382.. kernel-doc:: kernel/rcu/srcutree.c
383
384.. kernel-doc:: include/linux/rculist_bl.h
385
386.. kernel-doc:: include/linux/rculist.h
387
388.. kernel-doc:: include/linux/rculist_nulls.h
389
390.. kernel-doc:: include/linux/rcu_sync.h
391
392.. kernel-doc:: kernel/rcu/sync.c
393