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 log and power Functions
166-------------------------------
167
168.. kernel-doc:: include/linux/int_log.h
169
170.. kernel-doc:: lib/math/int_pow.c
171   :export:
172
173.. kernel-doc:: lib/math/int_sqrt.c
174   :export:
175
176Division Functions
177------------------
178
179.. kernel-doc:: include/asm-generic/div64.h
180   :functions: do_div
181
182.. kernel-doc:: include/linux/math64.h
183   :internal:
184
185.. kernel-doc:: lib/math/gcd.c
186   :export:
187
188UUID/GUID
189---------
190
191.. kernel-doc:: lib/uuid.c
192   :export:
193
194Kernel IPC facilities
195=====================
196
197IPC utilities
198-------------
199
200.. kernel-doc:: ipc/util.c
201   :internal:
202
203FIFO Buffer
204===========
205
206kfifo interface
207---------------
208
209.. kernel-doc:: include/linux/kfifo.h
210   :internal:
211
212relay interface support
213=======================
214
215Relay interface support is designed to provide an efficient mechanism
216for tools and facilities to relay large amounts of data from kernel
217space to user space.
218
219relay interface
220---------------
221
222.. kernel-doc:: kernel/relay.c
223   :export:
224
225.. kernel-doc:: kernel/relay.c
226   :internal:
227
228Module Support
229==============
230
231Kernel module auto-loading
232--------------------------
233
234.. kernel-doc:: kernel/module/kmod.c
235   :export:
236
237Module debugging
238----------------
239
240.. kernel-doc:: kernel/module/stats.c
241   :doc: module debugging statistics overview
242
243dup_failed_modules - tracks duplicate failed modules
244****************************************************
245
246.. kernel-doc:: kernel/module/stats.c
247   :doc: dup_failed_modules - tracks duplicate failed modules
248
249module statistics debugfs counters
250**********************************
251
252.. kernel-doc:: kernel/module/stats.c
253   :doc: module statistics debugfs counters
254
255Inter Module support
256--------------------
257
258Refer to the files in kernel/module/ for more information.
259
260Hardware Interfaces
261===================
262
263DMA Channels
264------------
265
266.. kernel-doc:: kernel/dma.c
267   :export:
268
269Resources Management
270--------------------
271
272.. kernel-doc:: kernel/resource.c
273   :internal:
274
275.. kernel-doc:: kernel/resource.c
276   :export:
277
278MTRR Handling
279-------------
280
281.. kernel-doc:: arch/x86/kernel/cpu/mtrr/mtrr.c
282   :export:
283
284Security Framework
285==================
286
287.. kernel-doc:: security/security.c
288   :internal:
289
290.. kernel-doc:: security/inode.c
291   :export:
292
293Audit Interfaces
294================
295
296.. kernel-doc:: kernel/audit.c
297   :export:
298
299.. kernel-doc:: kernel/auditsc.c
300   :internal:
301
302.. kernel-doc:: kernel/auditfilter.c
303   :internal:
304
305Accounting Framework
306====================
307
308.. kernel-doc:: kernel/acct.c
309   :internal:
310
311Block Devices
312=============
313
314.. kernel-doc:: include/linux/bio.h
315.. kernel-doc:: block/blk-core.c
316   :export:
317
318.. kernel-doc:: block/blk-core.c
319   :internal:
320
321.. kernel-doc:: block/blk-map.c
322   :export:
323
324.. kernel-doc:: block/blk-sysfs.c
325   :internal:
326
327.. kernel-doc:: block/blk-settings.c
328   :export:
329
330.. kernel-doc:: block/blk-flush.c
331   :export:
332
333.. kernel-doc:: block/blk-lib.c
334   :export:
335
336.. kernel-doc:: block/blk-integrity.c
337   :export:
338
339.. kernel-doc:: kernel/trace/blktrace.c
340   :internal:
341
342.. kernel-doc:: block/genhd.c
343   :internal:
344
345.. kernel-doc:: block/genhd.c
346   :export:
347
348.. kernel-doc:: block/bdev.c
349   :export:
350
351Char devices
352============
353
354.. kernel-doc:: fs/char_dev.c
355   :export:
356
357Clock Framework
358===============
359
360The clock framework defines programming interfaces to support software
361management of the system clock tree. This framework is widely used with
362System-On-Chip (SOC) platforms to support power management and various
363devices which may need custom clock rates. Note that these "clocks"
364don't relate to timekeeping or real time clocks (RTCs), each of which
365have separate frameworks. These :c:type:`struct clk <clk>`
366instances may be used to manage for example a 96 MHz signal that is used
367to shift bits into and out of peripherals or busses, or otherwise
368trigger synchronous state machine transitions in system hardware.
369
370Power management is supported by explicit software clock gating: unused
371clocks are disabled, so the system doesn't waste power changing the
372state of transistors that aren't in active use. On some systems this may
373be backed by hardware clock gating, where clocks are gated without being
374disabled in software. Sections of chips that are powered but not clocked
375may be able to retain their last state. This low power state is often
376called a *retention mode*. This mode still incurs leakage currents,
377especially with finer circuit geometries, but for CMOS circuits power is
378mostly used by clocked state changes.
379
380Power-aware drivers only enable their clocks when the device they manage
381is in active use. Also, system sleep states often differ according to
382which clock domains are active: while a "standby" state may allow wakeup
383from several active domains, a "mem" (suspend-to-RAM) state may require
384a more wholesale shutdown of clocks derived from higher speed PLLs and
385oscillators, limiting the number of possible wakeup event sources. A
386driver's suspend method may need to be aware of system-specific clock
387constraints on the target sleep state.
388
389Some platforms support programmable clock generators. These can be used
390by external chips of various kinds, such as other CPUs, multimedia
391codecs, and devices with strict requirements for interface clocking.
392
393.. kernel-doc:: include/linux/clk.h
394   :internal:
395
396Synchronization Primitives
397==========================
398
399Read-Copy Update (RCU)
400----------------------
401
402.. kernel-doc:: include/linux/rcupdate.h
403
404.. kernel-doc:: kernel/rcu/tree.c
405
406.. kernel-doc:: kernel/rcu/tree_exp.h
407
408.. kernel-doc:: kernel/rcu/update.c
409
410.. kernel-doc:: include/linux/srcu.h
411
412.. kernel-doc:: kernel/rcu/srcutree.c
413
414.. kernel-doc:: include/linux/rculist_bl.h
415
416.. kernel-doc:: include/linux/rculist.h
417
418.. kernel-doc:: include/linux/rculist_nulls.h
419
420.. kernel-doc:: include/linux/rcu_sync.h
421
422.. kernel-doc:: kernel/rcu/sync.c
423
424.. kernel-doc:: kernel/rcu/tasks.h
425
426.. kernel-doc:: kernel/rcu/tree_stall.h
427
428.. kernel-doc:: include/linux/rcupdate_trace.h
429
430.. kernel-doc:: include/linux/rcupdate_wait.h
431
432.. kernel-doc:: include/linux/rcuref.h
433
434.. kernel-doc:: include/linux/rcutree.h
435