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