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
99Error Pointers
100--------------
101
102.. kernel-doc:: include/linux/err.h
103   :internal:
104
105Sorting
106-------
107
108.. kernel-doc:: lib/sort.c
109   :export:
110
111.. kernel-doc:: lib/list_sort.c
112   :export:
113
114Text Searching
115--------------
116
117.. kernel-doc:: lib/textsearch.c
118   :doc: ts_intro
119
120.. kernel-doc:: lib/textsearch.c
121   :export:
122
123.. kernel-doc:: include/linux/textsearch.h
124   :functions: textsearch_find textsearch_next \
125               textsearch_get_pattern textsearch_get_pattern_len
126
127CRC and Math Functions in Linux
128===============================
129
130Arithmetic Overflow Checking
131----------------------------
132
133.. kernel-doc:: include/linux/overflow.h
134   :internal:
135
136CRC Functions
137-------------
138
139.. kernel-doc:: lib/crc4.c
140   :export:
141
142.. kernel-doc:: lib/crc7.c
143   :export:
144
145.. kernel-doc:: lib/crc8.c
146   :export:
147
148.. kernel-doc:: lib/crc16.c
149   :export:
150
151.. kernel-doc:: lib/crc32.c
152
153.. kernel-doc:: lib/crc-ccitt.c
154   :export:
155
156.. kernel-doc:: lib/crc-itu-t.c
157   :export:
158
159Base 2 log and power Functions
160------------------------------
161
162.. kernel-doc:: include/linux/log2.h
163   :internal:
164
165Integer power Functions
166-----------------------
167
168.. kernel-doc:: lib/math/int_pow.c
169   :export:
170
171.. kernel-doc:: lib/math/int_sqrt.c
172   :export:
173
174Division Functions
175------------------
176
177.. kernel-doc:: include/asm-generic/div64.h
178   :functions: do_div
179
180.. kernel-doc:: include/linux/math64.h
181   :internal:
182
183.. kernel-doc:: lib/math/gcd.c
184   :export:
185
186UUID/GUID
187---------
188
189.. kernel-doc:: lib/uuid.c
190   :export:
191
192Kernel IPC facilities
193=====================
194
195IPC utilities
196-------------
197
198.. kernel-doc:: ipc/util.c
199   :internal:
200
201FIFO Buffer
202===========
203
204kfifo interface
205---------------
206
207.. kernel-doc:: include/linux/kfifo.h
208   :internal:
209
210relay interface support
211=======================
212
213Relay interface support is designed to provide an efficient mechanism
214for tools and facilities to relay large amounts of data from kernel
215space to user space.
216
217relay interface
218---------------
219
220.. kernel-doc:: kernel/relay.c
221   :export:
222
223.. kernel-doc:: kernel/relay.c
224   :internal:
225
226Module Support
227==============
228
229Kernel module auto-loading
230--------------------------
231
232.. kernel-doc:: kernel/module/kmod.c
233   :export:
234
235Module debugging
236----------------
237
238.. kernel-doc:: kernel/module/stats.c
239   :doc: module debugging statistics overview
240
241dup_failed_modules - tracks duplicate failed modules
242****************************************************
243
244.. kernel-doc:: kernel/module/stats.c
245   :doc: dup_failed_modules - tracks duplicate failed modules
246
247module statistics debugfs counters
248**********************************
249
250.. kernel-doc:: kernel/module/stats.c
251   :doc: module statistics debugfs counters
252
253Inter Module support
254--------------------
255
256Refer to the files in kernel/module/ for more information.
257
258Hardware Interfaces
259===================
260
261DMA Channels
262------------
263
264.. kernel-doc:: kernel/dma.c
265   :export:
266
267Resources Management
268--------------------
269
270.. kernel-doc:: kernel/resource.c
271   :internal:
272
273.. kernel-doc:: kernel/resource.c
274   :export:
275
276MTRR Handling
277-------------
278
279.. kernel-doc:: arch/x86/kernel/cpu/mtrr/mtrr.c
280   :export:
281
282Security Framework
283==================
284
285.. kernel-doc:: security/security.c
286   :internal:
287
288.. kernel-doc:: security/inode.c
289   :export:
290
291Audit Interfaces
292================
293
294.. kernel-doc:: kernel/audit.c
295   :export:
296
297.. kernel-doc:: kernel/auditsc.c
298   :internal:
299
300.. kernel-doc:: kernel/auditfilter.c
301   :internal:
302
303Accounting Framework
304====================
305
306.. kernel-doc:: kernel/acct.c
307   :internal:
308
309Block Devices
310=============
311
312.. kernel-doc:: include/linux/bio.h
313.. kernel-doc:: block/blk-core.c
314   :export:
315
316.. kernel-doc:: block/blk-core.c
317   :internal:
318
319.. kernel-doc:: block/blk-map.c
320   :export:
321
322.. kernel-doc:: block/blk-sysfs.c
323   :internal:
324
325.. kernel-doc:: block/blk-settings.c
326   :export:
327
328.. kernel-doc:: block/blk-flush.c
329   :export:
330
331.. kernel-doc:: block/blk-lib.c
332   :export:
333
334.. kernel-doc:: block/blk-integrity.c
335   :export:
336
337.. kernel-doc:: kernel/trace/blktrace.c
338   :internal:
339
340.. kernel-doc:: block/genhd.c
341   :internal:
342
343.. kernel-doc:: block/genhd.c
344   :export:
345
346.. kernel-doc:: block/bdev.c
347   :export:
348
349Char devices
350============
351
352.. kernel-doc:: fs/char_dev.c
353   :export:
354
355Clock Framework
356===============
357
358The clock framework defines programming interfaces to support software
359management of the system clock tree. This framework is widely used with
360System-On-Chip (SOC) platforms to support power management and various
361devices which may need custom clock rates. Note that these "clocks"
362don't relate to timekeeping or real time clocks (RTCs), each of which
363have separate frameworks. These :c:type:`struct clk <clk>`
364instances may be used to manage for example a 96 MHz signal that is used
365to shift bits into and out of peripherals or busses, or otherwise
366trigger synchronous state machine transitions in system hardware.
367
368Power management is supported by explicit software clock gating: unused
369clocks are disabled, so the system doesn't waste power changing the
370state of transistors that aren't in active use. On some systems this may
371be backed by hardware clock gating, where clocks are gated without being
372disabled in software. Sections of chips that are powered but not clocked
373may be able to retain their last state. This low power state is often
374called a *retention mode*. This mode still incurs leakage currents,
375especially with finer circuit geometries, but for CMOS circuits power is
376mostly used by clocked state changes.
377
378Power-aware drivers only enable their clocks when the device they manage
379is in active use. Also, system sleep states often differ according to
380which clock domains are active: while a "standby" state may allow wakeup
381from several active domains, a "mem" (suspend-to-RAM) state may require
382a more wholesale shutdown of clocks derived from higher speed PLLs and
383oscillators, limiting the number of possible wakeup event sources. A
384driver's suspend method may need to be aware of system-specific clock
385constraints on the target sleep state.
386
387Some platforms support programmable clock generators. These can be used
388by external chips of various kinds, such as other CPUs, multimedia
389codecs, and devices with strict requirements for interface clocking.
390
391.. kernel-doc:: include/linux/clk.h
392   :internal:
393
394Synchronization Primitives
395==========================
396
397Read-Copy Update (RCU)
398----------------------
399
400.. kernel-doc:: include/linux/rcupdate.h
401
402.. kernel-doc:: kernel/rcu/tree.c
403
404.. kernel-doc:: kernel/rcu/tree_exp.h
405
406.. kernel-doc:: kernel/rcu/update.c
407
408.. kernel-doc:: include/linux/srcu.h
409
410.. kernel-doc:: kernel/rcu/srcutree.c
411
412.. kernel-doc:: include/linux/rculist_bl.h
413
414.. kernel-doc:: include/linux/rculist.h
415
416.. kernel-doc:: include/linux/rculist_nulls.h
417
418.. kernel-doc:: include/linux/rcu_sync.h
419
420.. kernel-doc:: kernel/rcu/sync.c
421
422.. kernel-doc:: kernel/rcu/tasks.h
423
424.. kernel-doc:: kernel/rcu/tree_stall.h
425
426.. kernel-doc:: include/linux/rcupdate_trace.h
427
428.. kernel-doc:: include/linux/rcupdate_wait.h
429
430.. kernel-doc:: include/linux/rcuref.h
431
432.. kernel-doc:: include/linux/rcutree.h
433