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:: include/linux/fortify-string.h
40   :internal:
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
124Arithmetic Overflow Checking
125----------------------------
126
127.. kernel-doc:: include/linux/overflow.h
128   :internal:
129
130CRC Functions
131-------------
132
133.. kernel-doc:: lib/crc4.c
134   :export:
135
136.. kernel-doc:: lib/crc7.c
137   :export:
138
139.. kernel-doc:: lib/crc8.c
140   :export:
141
142.. kernel-doc:: lib/crc16.c
143   :export:
144
145.. kernel-doc:: lib/crc32.c
146
147.. kernel-doc:: lib/crc-ccitt.c
148   :export:
149
150.. kernel-doc:: lib/crc-itu-t.c
151   :export:
152
153Base 2 log and power Functions
154------------------------------
155
156.. kernel-doc:: include/linux/log2.h
157   :internal:
158
159Integer power Functions
160-----------------------
161
162.. kernel-doc:: lib/math/int_pow.c
163   :export:
164
165.. kernel-doc:: lib/math/int_sqrt.c
166   :export:
167
168Division Functions
169------------------
170
171.. kernel-doc:: include/asm-generic/div64.h
172   :functions: do_div
173
174.. kernel-doc:: include/linux/math64.h
175   :internal:
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
223Kernel module auto-loading
224--------------------------
225
226.. kernel-doc:: kernel/module/kmod.c
227   :export:
228
229Module debugging
230----------------
231
232.. kernel-doc:: kernel/module/stats.c
233   :doc: module debugging statistics overview
234
235dup_failed_modules - tracks duplicate failed modules
236****************************************************
237
238.. kernel-doc:: kernel/module/stats.c
239   :doc: dup_failed_modules - tracks duplicate failed modules
240
241module statistics debugfs counters
242**********************************
243
244.. kernel-doc:: kernel/module/stats.c
245   :doc: module statistics debugfs counters
246
247Inter Module support
248--------------------
249
250Refer to the files in kernel/module/ for more information.
251
252Hardware Interfaces
253===================
254
255DMA Channels
256------------
257
258.. kernel-doc:: kernel/dma.c
259   :export:
260
261Resources Management
262--------------------
263
264.. kernel-doc:: kernel/resource.c
265   :internal:
266
267.. kernel-doc:: kernel/resource.c
268   :export:
269
270MTRR Handling
271-------------
272
273.. kernel-doc:: arch/x86/kernel/cpu/mtrr/mtrr.c
274   :export:
275
276Security Framework
277==================
278
279.. kernel-doc:: security/security.c
280   :internal:
281
282.. kernel-doc:: security/inode.c
283   :export:
284
285Audit Interfaces
286================
287
288.. kernel-doc:: kernel/audit.c
289   :export:
290
291.. kernel-doc:: kernel/auditsc.c
292   :internal:
293
294.. kernel-doc:: kernel/auditfilter.c
295   :internal:
296
297Accounting Framework
298====================
299
300.. kernel-doc:: kernel/acct.c
301   :internal:
302
303Block Devices
304=============
305
306.. kernel-doc:: include/linux/bio.h
307.. kernel-doc:: block/blk-core.c
308   :export:
309
310.. kernel-doc:: block/blk-core.c
311   :internal:
312
313.. kernel-doc:: block/blk-map.c
314   :export:
315
316.. kernel-doc:: block/blk-sysfs.c
317   :internal:
318
319.. kernel-doc:: block/blk-settings.c
320   :export:
321
322.. kernel-doc:: block/blk-flush.c
323   :export:
324
325.. kernel-doc:: block/blk-lib.c
326   :export:
327
328.. kernel-doc:: block/blk-integrity.c
329   :export:
330
331.. kernel-doc:: kernel/trace/blktrace.c
332   :internal:
333
334.. kernel-doc:: block/genhd.c
335   :internal:
336
337.. kernel-doc:: block/genhd.c
338   :export:
339
340.. kernel-doc:: block/bdev.c
341   :export:
342
343Char devices
344============
345
346.. kernel-doc:: fs/char_dev.c
347   :export:
348
349Clock Framework
350===============
351
352The clock framework defines programming interfaces to support software
353management of the system clock tree. This framework is widely used with
354System-On-Chip (SOC) platforms to support power management and various
355devices which may need custom clock rates. Note that these "clocks"
356don't relate to timekeeping or real time clocks (RTCs), each of which
357have separate frameworks. These :c:type:`struct clk <clk>`
358instances may be used to manage for example a 96 MHz signal that is used
359to shift bits into and out of peripherals or busses, or otherwise
360trigger synchronous state machine transitions in system hardware.
361
362Power management is supported by explicit software clock gating: unused
363clocks are disabled, so the system doesn't waste power changing the
364state of transistors that aren't in active use. On some systems this may
365be backed by hardware clock gating, where clocks are gated without being
366disabled in software. Sections of chips that are powered but not clocked
367may be able to retain their last state. This low power state is often
368called a *retention mode*. This mode still incurs leakage currents,
369especially with finer circuit geometries, but for CMOS circuits power is
370mostly used by clocked state changes.
371
372Power-aware drivers only enable their clocks when the device they manage
373is in active use. Also, system sleep states often differ according to
374which clock domains are active: while a "standby" state may allow wakeup
375from several active domains, a "mem" (suspend-to-RAM) state may require
376a more wholesale shutdown of clocks derived from higher speed PLLs and
377oscillators, limiting the number of possible wakeup event sources. A
378driver's suspend method may need to be aware of system-specific clock
379constraints on the target sleep state.
380
381Some platforms support programmable clock generators. These can be used
382by external chips of various kinds, such as other CPUs, multimedia
383codecs, and devices with strict requirements for interface clocking.
384
385.. kernel-doc:: include/linux/clk.h
386   :internal:
387
388Synchronization Primitives
389==========================
390
391Read-Copy Update (RCU)
392----------------------
393
394.. kernel-doc:: include/linux/rcupdate.h
395
396.. kernel-doc:: kernel/rcu/tree.c
397
398.. kernel-doc:: kernel/rcu/tree_exp.h
399
400.. kernel-doc:: kernel/rcu/update.c
401
402.. kernel-doc:: include/linux/srcu.h
403
404.. kernel-doc:: kernel/rcu/srcutree.c
405
406.. kernel-doc:: include/linux/rculist_bl.h
407
408.. kernel-doc:: include/linux/rculist.h
409
410.. kernel-doc:: include/linux/rculist_nulls.h
411
412.. kernel-doc:: include/linux/rcu_sync.h
413
414.. kernel-doc:: kernel/rcu/sync.c
415