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
121CRC Functions
122-------------
123
124.. kernel-doc:: lib/crc4.c
125   :export:
126
127.. kernel-doc:: lib/crc7.c
128   :export:
129
130.. kernel-doc:: lib/crc8.c
131   :export:
132
133.. kernel-doc:: lib/crc16.c
134   :export:
135
136.. kernel-doc:: lib/crc32.c
137
138.. kernel-doc:: lib/crc-ccitt.c
139   :export:
140
141.. kernel-doc:: lib/crc-itu-t.c
142   :export:
143
144Base 2 log and power Functions
145------------------------------
146
147.. kernel-doc:: include/linux/log2.h
148   :internal:
149
150Integer power Functions
151-----------------------
152
153.. kernel-doc:: lib/math/int_pow.c
154   :export:
155
156.. kernel-doc:: lib/math/int_sqrt.c
157   :export:
158
159Division Functions
160------------------
161
162.. kernel-doc:: include/asm-generic/div64.h
163   :functions: do_div
164
165.. kernel-doc:: include/linux/math64.h
166   :internal:
167
168.. kernel-doc:: lib/math/div64.c
169   :functions: div_s64_rem div64_u64_rem div64_u64 div64_s64
170
171.. kernel-doc:: lib/math/gcd.c
172   :export:
173
174UUID/GUID
175---------
176
177.. kernel-doc:: lib/uuid.c
178   :export:
179
180Kernel IPC facilities
181=====================
182
183IPC utilities
184-------------
185
186.. kernel-doc:: ipc/util.c
187   :internal:
188
189FIFO Buffer
190===========
191
192kfifo interface
193---------------
194
195.. kernel-doc:: include/linux/kfifo.h
196   :internal:
197
198relay interface support
199=======================
200
201Relay interface support is designed to provide an efficient mechanism
202for tools and facilities to relay large amounts of data from kernel
203space to user space.
204
205relay interface
206---------------
207
208.. kernel-doc:: kernel/relay.c
209   :export:
210
211.. kernel-doc:: kernel/relay.c
212   :internal:
213
214Module Support
215==============
216
217Module Loading
218--------------
219
220.. kernel-doc:: kernel/kmod.c
221   :export:
222
223Inter Module support
224--------------------
225
226Refer to the files in kernel/module/ for more information.
227
228Hardware Interfaces
229===================
230
231DMA Channels
232------------
233
234.. kernel-doc:: kernel/dma.c
235   :export:
236
237Resources Management
238--------------------
239
240.. kernel-doc:: kernel/resource.c
241   :internal:
242
243.. kernel-doc:: kernel/resource.c
244   :export:
245
246MTRR Handling
247-------------
248
249.. kernel-doc:: arch/x86/kernel/cpu/mtrr/mtrr.c
250   :export:
251
252Security Framework
253==================
254
255.. kernel-doc:: security/security.c
256   :internal:
257
258.. kernel-doc:: security/inode.c
259   :export:
260
261Audit Interfaces
262================
263
264.. kernel-doc:: kernel/audit.c
265   :export:
266
267.. kernel-doc:: kernel/auditsc.c
268   :internal:
269
270.. kernel-doc:: kernel/auditfilter.c
271   :internal:
272
273Accounting Framework
274====================
275
276.. kernel-doc:: kernel/acct.c
277   :internal:
278
279Block Devices
280=============
281
282.. kernel-doc:: include/linux/bio.h
283.. kernel-doc:: block/blk-core.c
284   :export:
285
286.. kernel-doc:: block/blk-core.c
287   :internal:
288
289.. kernel-doc:: block/blk-map.c
290   :export:
291
292.. kernel-doc:: block/blk-sysfs.c
293   :internal:
294
295.. kernel-doc:: block/blk-settings.c
296   :export:
297
298.. kernel-doc:: block/blk-flush.c
299   :export:
300
301.. kernel-doc:: block/blk-lib.c
302   :export:
303
304.. kernel-doc:: block/blk-integrity.c
305   :export:
306
307.. kernel-doc:: kernel/trace/blktrace.c
308   :internal:
309
310.. kernel-doc:: block/genhd.c
311   :internal:
312
313.. kernel-doc:: block/genhd.c
314   :export:
315
316.. kernel-doc:: block/bdev.c
317   :export:
318
319Char devices
320============
321
322.. kernel-doc:: fs/char_dev.c
323   :export:
324
325Clock Framework
326===============
327
328The clock framework defines programming interfaces to support software
329management of the system clock tree. This framework is widely used with
330System-On-Chip (SOC) platforms to support power management and various
331devices which may need custom clock rates. Note that these "clocks"
332don't relate to timekeeping or real time clocks (RTCs), each of which
333have separate frameworks. These :c:type:`struct clk <clk>`
334instances may be used to manage for example a 96 MHz signal that is used
335to shift bits into and out of peripherals or busses, or otherwise
336trigger synchronous state machine transitions in system hardware.
337
338Power management is supported by explicit software clock gating: unused
339clocks are disabled, so the system doesn't waste power changing the
340state of transistors that aren't in active use. On some systems this may
341be backed by hardware clock gating, where clocks are gated without being
342disabled in software. Sections of chips that are powered but not clocked
343may be able to retain their last state. This low power state is often
344called a *retention mode*. This mode still incurs leakage currents,
345especially with finer circuit geometries, but for CMOS circuits power is
346mostly used by clocked state changes.
347
348Power-aware drivers only enable their clocks when the device they manage
349is in active use. Also, system sleep states often differ according to
350which clock domains are active: while a "standby" state may allow wakeup
351from several active domains, a "mem" (suspend-to-RAM) state may require
352a more wholesale shutdown of clocks derived from higher speed PLLs and
353oscillators, limiting the number of possible wakeup event sources. A
354driver's suspend method may need to be aware of system-specific clock
355constraints on the target sleep state.
356
357Some platforms support programmable clock generators. These can be used
358by external chips of various kinds, such as other CPUs, multimedia
359codecs, and devices with strict requirements for interface clocking.
360
361.. kernel-doc:: include/linux/clk.h
362   :internal:
363
364Synchronization Primitives
365==========================
366
367Read-Copy Update (RCU)
368----------------------
369
370.. kernel-doc:: include/linux/rcupdate.h
371
372.. kernel-doc:: kernel/rcu/tree.c
373
374.. kernel-doc:: kernel/rcu/tree_exp.h
375
376.. kernel-doc:: kernel/rcu/update.c
377
378.. kernel-doc:: include/linux/srcu.h
379
380.. kernel-doc:: kernel/rcu/srcutree.c
381
382.. kernel-doc:: include/linux/rculist_bl.h
383
384.. kernel-doc:: include/linux/rculist.h
385
386.. kernel-doc:: include/linux/rculist_nulls.h
387
388.. kernel-doc:: include/linux/rcu_sync.h
389
390.. kernel-doc:: kernel/rcu/sync.c
391