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/kstrtox.h
28   :functions: kstrtol kstrtoul
29
30.. kernel-doc:: lib/kstrtox.c
31   :export:
32
33.. kernel-doc:: lib/string_helpers.c
34   :export:
35
36String Manipulation
37-------------------
38
39.. kernel-doc:: lib/string.c
40   :export:
41
42.. kernel-doc:: include/linux/string.h
43   :internal:
44
45.. kernel-doc:: mm/util.c
46   :functions: kstrdup kstrdup_const kstrndup kmemdup kmemdup_nul memdup_user
47               vmemdup_user strndup_user memdup_user_nul
48
49Basic Kernel Library Functions
50==============================
51
52The Linux kernel provides more basic utility functions.
53
54Bit Operations
55--------------
56
57.. kernel-doc:: include/asm-generic/bitops/instrumented-atomic.h
58   :internal:
59
60.. kernel-doc:: include/asm-generic/bitops/instrumented-non-atomic.h
61   :internal:
62
63.. kernel-doc:: include/asm-generic/bitops/instrumented-lock.h
64   :internal:
65
66Bitmap Operations
67-----------------
68
69.. kernel-doc:: lib/bitmap.c
70   :doc: bitmap introduction
71
72.. kernel-doc:: include/linux/bitmap.h
73   :doc: declare bitmap
74
75.. kernel-doc:: include/linux/bitmap.h
76   :doc: bitmap overview
77
78.. kernel-doc:: include/linux/bitmap.h
79   :doc: bitmap bitops
80
81.. kernel-doc:: lib/bitmap.c
82   :export:
83
84.. kernel-doc:: lib/bitmap.c
85   :internal:
86
87.. kernel-doc:: include/linux/bitmap.h
88   :internal:
89
90Command-line Parsing
91--------------------
92
93.. kernel-doc:: lib/cmdline.c
94   :export:
95
96Sorting
97-------
98
99.. kernel-doc:: lib/sort.c
100   :export:
101
102.. kernel-doc:: lib/list_sort.c
103   :export:
104
105Text Searching
106--------------
107
108.. kernel-doc:: lib/textsearch.c
109   :doc: ts_intro
110
111.. kernel-doc:: lib/textsearch.c
112   :export:
113
114.. kernel-doc:: include/linux/textsearch.h
115   :functions: textsearch_find textsearch_next \
116               textsearch_get_pattern textsearch_get_pattern_len
117
118CRC and Math Functions in Linux
119===============================
120
121Arithmetic Overflow Checking
122----------------------------
123
124.. kernel-doc:: include/linux/overflow.h
125   :internal:
126
127CRC Functions
128-------------
129
130.. kernel-doc:: lib/crc4.c
131   :export:
132
133.. kernel-doc:: lib/crc7.c
134   :export:
135
136.. kernel-doc:: lib/crc8.c
137   :export:
138
139.. kernel-doc:: lib/crc16.c
140   :export:
141
142.. kernel-doc:: lib/crc32.c
143
144.. kernel-doc:: lib/crc-ccitt.c
145   :export:
146
147.. kernel-doc:: lib/crc-itu-t.c
148   :export:
149
150Base 2 log and power Functions
151------------------------------
152
153.. kernel-doc:: include/linux/log2.h
154   :internal:
155
156Integer power Functions
157-----------------------
158
159.. kernel-doc:: lib/math/int_pow.c
160   :export:
161
162.. kernel-doc:: lib/math/int_sqrt.c
163   :export:
164
165Division Functions
166------------------
167
168.. kernel-doc:: include/asm-generic/div64.h
169   :functions: do_div
170
171.. kernel-doc:: include/linux/math64.h
172   :internal:
173
174.. kernel-doc:: lib/math/div64.c
175   :functions: div_s64_rem div64_u64_rem div64_u64 div64_s64
176
177.. kernel-doc:: lib/math/gcd.c
178   :export:
179
180UUID/GUID
181---------
182
183.. kernel-doc:: lib/uuid.c
184   :export:
185
186Kernel IPC facilities
187=====================
188
189IPC utilities
190-------------
191
192.. kernel-doc:: ipc/util.c
193   :internal:
194
195FIFO Buffer
196===========
197
198kfifo interface
199---------------
200
201.. kernel-doc:: include/linux/kfifo.h
202   :internal:
203
204relay interface support
205=======================
206
207Relay interface support is designed to provide an efficient mechanism
208for tools and facilities to relay large amounts of data from kernel
209space to user space.
210
211relay interface
212---------------
213
214.. kernel-doc:: kernel/relay.c
215   :export:
216
217.. kernel-doc:: kernel/relay.c
218   :internal:
219
220Module Support
221==============
222
223Module Loading
224--------------
225
226.. kernel-doc:: kernel/kmod.c
227   :export:
228
229Inter Module support
230--------------------
231
232Refer to the files in kernel/module/ for more information.
233
234Hardware Interfaces
235===================
236
237DMA Channels
238------------
239
240.. kernel-doc:: kernel/dma.c
241   :export:
242
243Resources Management
244--------------------
245
246.. kernel-doc:: kernel/resource.c
247   :internal:
248
249.. kernel-doc:: kernel/resource.c
250   :export:
251
252MTRR Handling
253-------------
254
255.. kernel-doc:: arch/x86/kernel/cpu/mtrr/mtrr.c
256   :export:
257
258Security Framework
259==================
260
261.. kernel-doc:: security/security.c
262   :internal:
263
264.. kernel-doc:: security/inode.c
265   :export:
266
267Audit Interfaces
268================
269
270.. kernel-doc:: kernel/audit.c
271   :export:
272
273.. kernel-doc:: kernel/auditsc.c
274   :internal:
275
276.. kernel-doc:: kernel/auditfilter.c
277   :internal:
278
279Accounting Framework
280====================
281
282.. kernel-doc:: kernel/acct.c
283   :internal:
284
285Block Devices
286=============
287
288.. kernel-doc:: include/linux/bio.h
289.. kernel-doc:: block/blk-core.c
290   :export:
291
292.. kernel-doc:: block/blk-core.c
293   :internal:
294
295.. kernel-doc:: block/blk-map.c
296   :export:
297
298.. kernel-doc:: block/blk-sysfs.c
299   :internal:
300
301.. kernel-doc:: block/blk-settings.c
302   :export:
303
304.. kernel-doc:: block/blk-flush.c
305   :export:
306
307.. kernel-doc:: block/blk-lib.c
308   :export:
309
310.. kernel-doc:: block/blk-integrity.c
311   :export:
312
313.. kernel-doc:: kernel/trace/blktrace.c
314   :internal:
315
316.. kernel-doc:: block/genhd.c
317   :internal:
318
319.. kernel-doc:: block/genhd.c
320   :export:
321
322.. kernel-doc:: block/bdev.c
323   :export:
324
325Char devices
326============
327
328.. kernel-doc:: fs/char_dev.c
329   :export:
330
331Clock Framework
332===============
333
334The clock framework defines programming interfaces to support software
335management of the system clock tree. This framework is widely used with
336System-On-Chip (SOC) platforms to support power management and various
337devices which may need custom clock rates. Note that these "clocks"
338don't relate to timekeeping or real time clocks (RTCs), each of which
339have separate frameworks. These :c:type:`struct clk <clk>`
340instances may be used to manage for example a 96 MHz signal that is used
341to shift bits into and out of peripherals or busses, or otherwise
342trigger synchronous state machine transitions in system hardware.
343
344Power management is supported by explicit software clock gating: unused
345clocks are disabled, so the system doesn't waste power changing the
346state of transistors that aren't in active use. On some systems this may
347be backed by hardware clock gating, where clocks are gated without being
348disabled in software. Sections of chips that are powered but not clocked
349may be able to retain their last state. This low power state is often
350called a *retention mode*. This mode still incurs leakage currents,
351especially with finer circuit geometries, but for CMOS circuits power is
352mostly used by clocked state changes.
353
354Power-aware drivers only enable their clocks when the device they manage
355is in active use. Also, system sleep states often differ according to
356which clock domains are active: while a "standby" state may allow wakeup
357from several active domains, a "mem" (suspend-to-RAM) state may require
358a more wholesale shutdown of clocks derived from higher speed PLLs and
359oscillators, limiting the number of possible wakeup event sources. A
360driver's suspend method may need to be aware of system-specific clock
361constraints on the target sleep state.
362
363Some platforms support programmable clock generators. These can be used
364by external chips of various kinds, such as other CPUs, multimedia
365codecs, and devices with strict requirements for interface clocking.
366
367.. kernel-doc:: include/linux/clk.h
368   :internal:
369
370Synchronization Primitives
371==========================
372
373Read-Copy Update (RCU)
374----------------------
375
376.. kernel-doc:: include/linux/rcupdate.h
377
378.. kernel-doc:: kernel/rcu/tree.c
379
380.. kernel-doc:: kernel/rcu/tree_exp.h
381
382.. kernel-doc:: kernel/rcu/update.c
383
384.. kernel-doc:: include/linux/srcu.h
385
386.. kernel-doc:: kernel/rcu/srcutree.c
387
388.. kernel-doc:: include/linux/rculist_bl.h
389
390.. kernel-doc:: include/linux/rculist.h
391
392.. kernel-doc:: include/linux/rculist_nulls.h
393
394.. kernel-doc:: include/linux/rcu_sync.h
395
396.. kernel-doc:: kernel/rcu/sync.c
397