2 * A generic kernel FIFO implementation.
4 * Copyright (C) 2009 Stefani Seibold <stefani@seibold.net>
5 * Copyright (C) 2004 Stelian Pop <stelian@popies.net>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 * Howto porting drivers to the new generic fifo API:
26 * - Modify the declaration of the "struct kfifo *" object into a
27 * in-place "struct kfifo" object
28 * - Init the in-place object with kfifo_alloc() or kfifo_init()
29 * Note: The address of the in-place "struct kfifo" object must be
30 * passed as the first argument to this functions
31 * - Replace the use of __kfifo_put into kfifo_in and __kfifo_get
33 * - Replace the use of kfifo_put into kfifo_in_locked and kfifo_get
34 * into kfifo_out_locked
35 * Note: the spinlock pointer formerly passed to kfifo_init/kfifo_alloc
36 * must be passed now to the kfifo_in_locked and kfifo_out_locked
37 * as the last parameter.
38 * - All formerly name __kfifo_* functions has been renamed into kfifo_*
41 #ifndef _LINUX_KFIFO_H
42 #define _LINUX_KFIFO_H
44 #include <linux/kernel.h>
45 #include <linux/spinlock.h>
48 unsigned char *buffer
; /* the buffer holding the data */
49 unsigned int size
; /* the size of the allocated buffer */
50 unsigned int in
; /* data is added at offset (in % size) */
51 unsigned int out
; /* data is extracted from off. (out % size) */
55 * Macros for declaration and initialization of the kfifo datatype
59 #define __kfifo_initializer(s, b) \
68 * DECLARE_KFIFO - macro to declare a kfifo and the associated buffer
69 * @name: name of the declared kfifo datatype
70 * @size: size of the fifo buffer
72 * Note: the macro can be used inside struct or union declaration
73 * Note: the macro creates two objects:
74 * A kfifo object with the given name and a buffer for the kfifo
75 * object named name##kfifo_buffer
77 #define DECLARE_KFIFO(name, size) \
80 unsigned char name##kfifo_buffer[size + sizeof(struct kfifo)]; \
84 * INIT_KFIFO - Initialize a kfifo declared by DECLARED_KFIFO
85 * @name: name of the declared kfifo datatype
86 * @size: size of the fifo buffer
88 #define INIT_KFIFO(name) \
89 name = __kfifo_initializer(sizeof(name##kfifo_buffer) - \
90 sizeof(struct kfifo), name##kfifo_buffer)
93 * DEFINE_KFIFO - macro to define and initialize a kfifo
94 * @name: name of the declared kfifo datatype
95 * @size: size of the fifo buffer
97 * Note: the macro can be used for global and local kfifo data type variables
98 * Note: the macro creates two objects:
99 * A kfifo object with the given name and a buffer for the kfifo
100 * object named name##kfifo_buffer
102 #define DEFINE_KFIFO(name, size) \
103 unsigned char name##kfifo_buffer[size]; \
104 struct kfifo name = __kfifo_initializer(size, name##kfifo_buffer)
106 #undef __kfifo_initializer
108 extern void kfifo_init(struct kfifo
*fifo
, unsigned char *buffer
,
110 extern __must_check
int kfifo_alloc(struct kfifo
*fifo
, unsigned int size
,
112 extern void kfifo_free(struct kfifo
*fifo
);
113 extern unsigned int kfifo_in(struct kfifo
*fifo
,
114 const unsigned char *from
, unsigned int len
);
115 extern __must_check
unsigned int kfifo_out(struct kfifo
*fifo
,
116 unsigned char *to
, unsigned int len
);
119 * kfifo_reset - removes the entire FIFO contents
120 * @fifo: the fifo to be emptied.
122 static inline void kfifo_reset(struct kfifo
*fifo
)
124 fifo
->in
= fifo
->out
= 0;
128 * kfifo_reset_out - skip FIFO contents
129 * @fifo: the fifo to be emptied.
131 static inline void kfifo_reset_out(struct kfifo
*fifo
)
134 fifo
->out
= fifo
->in
;
138 * kfifo_size - returns the size of the fifo in bytes
139 * @fifo: the fifo to be used.
141 static inline __must_check
unsigned int kfifo_size(struct kfifo
*fifo
)
147 * kfifo_len - returns the number of used bytes in the FIFO
148 * @fifo: the fifo to be used.
150 static inline unsigned int kfifo_len(struct kfifo
*fifo
)
152 register unsigned int out
;
156 return fifo
->in
- out
;
160 * kfifo_is_empty - returns true if the fifo is empty
161 * @fifo: the fifo to be used.
163 static inline __must_check
int kfifo_is_empty(struct kfifo
*fifo
)
165 return fifo
->in
== fifo
->out
;
169 * kfifo_is_full - returns true if the fifo is full
170 * @fifo: the fifo to be used.
172 static inline __must_check
int kfifo_is_full(struct kfifo
*fifo
)
174 return kfifo_len(fifo
) == kfifo_size(fifo
);
178 * kfifo_avail - returns the number of bytes available in the FIFO
179 * @fifo: the fifo to be used.
181 static inline __must_check
unsigned int kfifo_avail(struct kfifo
*fifo
)
183 return kfifo_size(fifo
) - kfifo_len(fifo
);
187 * kfifo_in_locked - puts some data into the FIFO using a spinlock for locking
188 * @fifo: the fifo to be used.
189 * @from: the data to be added.
190 * @n: the length of the data to be added.
191 * @lock: pointer to the spinlock to use for locking.
193 * This function copies at most @len bytes from the @from buffer into
194 * the FIFO depending on the free space, and returns the number of
197 static inline unsigned int kfifo_in_locked(struct kfifo
*fifo
,
198 const unsigned char *from
, unsigned int n
, spinlock_t
*lock
)
203 spin_lock_irqsave(lock
, flags
);
205 ret
= kfifo_in(fifo
, from
, n
);
207 spin_unlock_irqrestore(lock
, flags
);
213 * kfifo_out_locked - gets some data from the FIFO using a spinlock for locking
214 * @fifo: the fifo to be used.
215 * @to: where the data must be copied.
216 * @n: the size of the destination buffer.
217 * @lock: pointer to the spinlock to use for locking.
219 * This function copies at most @len bytes from the FIFO into the
220 * @to buffer and returns the number of copied bytes.
222 static inline __must_check
unsigned int kfifo_out_locked(struct kfifo
*fifo
,
223 unsigned char *to
, unsigned int n
, spinlock_t
*lock
)
228 spin_lock_irqsave(lock
, flags
);
230 ret
= kfifo_out(fifo
, to
, n
);
233 * optimization: if the FIFO is empty, set the indices to 0
234 * so we don't wrap the next time
236 if (kfifo_is_empty(fifo
))
239 spin_unlock_irqrestore(lock
, flags
);
244 extern void kfifo_skip(struct kfifo
*fifo
, unsigned int len
);
246 extern __must_check
unsigned int kfifo_from_user(struct kfifo
*fifo
,
247 const void __user
*from
, unsigned int n
);
249 extern __must_check
unsigned int kfifo_to_user(struct kfifo
*fifo
,
250 void __user
*to
, unsigned int n
);
253 * __kfifo_add_out internal helper function for updating the out offset
255 static inline void __kfifo_add_out(struct kfifo
*fifo
,
263 * __kfifo_add_in internal helper function for updating the in offset
265 static inline void __kfifo_add_in(struct kfifo
*fifo
,
273 * __kfifo_off internal helper function for calculating the index of a
276 static inline unsigned int __kfifo_off(struct kfifo
*fifo
, unsigned int off
)
278 return off
& (fifo
->size
- 1);
282 * __kfifo_peek_n internal helper function for determinate the length of
283 * the next record in the fifo
285 static inline unsigned int __kfifo_peek_n(struct kfifo
*fifo
,
286 unsigned int recsize
)
288 #define __KFIFO_GET(fifo, off, shift) \
289 ((fifo)->buffer[__kfifo_off((fifo), (fifo)->out+(off))] << (shift))
293 l
= __KFIFO_GET(fifo
, 0, 0);
296 l
|= __KFIFO_GET(fifo
, 1, 8);
303 * __kfifo_poke_n internal helper function for storing the length of
304 * the next record into the fifo
306 static inline void __kfifo_poke_n(struct kfifo
*fifo
,
307 unsigned int recsize
, unsigned int n
)
309 #define __KFIFO_PUT(fifo, off, val, shift) \
311 (fifo)->buffer[__kfifo_off((fifo), (fifo)->in+(off))] = \
312 (unsigned char)((val) >> (shift)) \
315 __KFIFO_PUT(fifo
, 0, n
, 0);
318 __KFIFO_PUT(fifo
, 1, n
, 8);
323 * __kfifo_in_... internal functions for put date into the fifo
324 * do not call it directly, use kfifo_in_rec() instead
326 extern unsigned int __kfifo_in_n(struct kfifo
*fifo
,
327 const void *from
, unsigned int n
, unsigned int recsize
);
329 extern unsigned int __kfifo_in_generic(struct kfifo
*fifo
,
330 const void *from
, unsigned int n
, unsigned int recsize
);
332 static inline unsigned int __kfifo_in_rec(struct kfifo
*fifo
,
333 const void *from
, unsigned int n
, unsigned int recsize
)
337 ret
= __kfifo_in_n(fifo
, from
, n
, recsize
);
339 if (likely(ret
== 0)) {
341 __kfifo_poke_n(fifo
, recsize
, n
);
342 __kfifo_add_in(fifo
, n
+ recsize
);
348 * kfifo_in_rec - puts some record data into the FIFO
349 * @fifo: the fifo to be used.
350 * @from: the data to be added.
351 * @n: the length of the data to be added.
352 * @recsize: size of record field
354 * This function copies @n bytes from the @from into the FIFO and returns
355 * the number of bytes which cannot be copied.
356 * A returned value greater than the @n value means that the record doesn't
357 * fit into the buffer.
359 * Note that with only one concurrent reader and one concurrent
360 * writer, you don't need extra locking to use these functions.
362 static inline __must_check
unsigned int kfifo_in_rec(struct kfifo
*fifo
,
363 void *from
, unsigned int n
, unsigned int recsize
)
365 if (!__builtin_constant_p(recsize
))
366 return __kfifo_in_generic(fifo
, from
, n
, recsize
);
367 return __kfifo_in_rec(fifo
, from
, n
, recsize
);
371 * __kfifo_out_... internal functions for get date from the fifo
372 * do not call it directly, use kfifo_out_rec() instead
374 extern unsigned int __kfifo_out_n(struct kfifo
*fifo
,
375 void *to
, unsigned int reclen
, unsigned int recsize
);
377 extern unsigned int __kfifo_out_generic(struct kfifo
*fifo
,
378 void *to
, unsigned int n
,
379 unsigned int recsize
, unsigned int *total
);
381 static inline unsigned int __kfifo_out_rec(struct kfifo
*fifo
,
382 void *to
, unsigned int n
, unsigned int recsize
,
392 l
= __kfifo_peek_n(fifo
, recsize
);
399 return __kfifo_out_n(fifo
, to
, l
, recsize
);
403 * kfifo_out_rec - gets some record data from the FIFO
404 * @fifo: the fifo to be used.
405 * @to: where the data must be copied.
406 * @n: the size of the destination buffer.
407 * @recsize: size of record field
408 * @total: pointer where the total number of to copied bytes should stored
410 * This function copies at most @n bytes from the FIFO to @to and returns the
411 * number of bytes which cannot be copied.
412 * A returned value greater than the @n value means that the record doesn't
413 * fit into the @to buffer.
415 * Note that with only one concurrent reader and one concurrent
416 * writer, you don't need extra locking to use these functions.
418 static inline __must_check
unsigned int kfifo_out_rec(struct kfifo
*fifo
,
419 void *to
, unsigned int n
, unsigned int recsize
,
423 if (!__builtin_constant_p(recsize
))
424 return __kfifo_out_generic(fifo
, to
, n
, recsize
, total
);
425 return __kfifo_out_rec(fifo
, to
, n
, recsize
, total
);
429 * __kfifo_from_user_... internal functions for transfer from user space into
430 * the fifo. do not call it directly, use kfifo_from_user_rec() instead
432 extern unsigned int __kfifo_from_user_n(struct kfifo
*fifo
,
433 const void __user
*from
, unsigned int n
, unsigned int recsize
);
435 extern unsigned int __kfifo_from_user_generic(struct kfifo
*fifo
,
436 const void __user
*from
, unsigned int n
, unsigned int recsize
);
438 static inline unsigned int __kfifo_from_user_rec(struct kfifo
*fifo
,
439 const void __user
*from
, unsigned int n
, unsigned int recsize
)
443 ret
= __kfifo_from_user_n(fifo
, from
, n
, recsize
);
445 if (likely(ret
== 0)) {
447 __kfifo_poke_n(fifo
, recsize
, n
);
448 __kfifo_add_in(fifo
, n
+ recsize
);
454 * kfifo_from_user_rec - puts some data from user space into the FIFO
455 * @fifo: the fifo to be used.
456 * @from: pointer to the data to be added.
457 * @n: the length of the data to be added.
458 * @recsize: size of record field
460 * This function copies @n bytes from the @from into the
461 * FIFO and returns the number of bytes which cannot be copied.
463 * If the returned value is equal or less the @n value, the copy_from_user()
464 * functions has failed. Otherwise the record doesn't fit into the buffer.
466 * Note that with only one concurrent reader and one concurrent
467 * writer, you don't need extra locking to use these functions.
469 static inline __must_check
unsigned int kfifo_from_user_rec(struct kfifo
*fifo
,
470 const void __user
*from
, unsigned int n
, unsigned int recsize
)
472 if (!__builtin_constant_p(recsize
))
473 return __kfifo_from_user_generic(fifo
, from
, n
, recsize
);
474 return __kfifo_from_user_rec(fifo
, from
, n
, recsize
);
478 * __kfifo_to_user_... internal functions for transfer fifo data into user space
479 * do not call it directly, use kfifo_to_user_rec() instead
481 extern unsigned int __kfifo_to_user_n(struct kfifo
*fifo
,
482 void __user
*to
, unsigned int n
, unsigned int reclen
,
483 unsigned int recsize
);
485 extern unsigned int __kfifo_to_user_generic(struct kfifo
*fifo
,
486 void __user
*to
, unsigned int n
, unsigned int recsize
,
487 unsigned int *total
);
489 static inline unsigned int __kfifo_to_user_rec(struct kfifo
*fifo
,
490 void __user
*to
, unsigned int n
,
491 unsigned int recsize
, unsigned int *total
)
500 l
= __kfifo_peek_n(fifo
, recsize
);
507 return __kfifo_to_user_n(fifo
, to
, n
, l
, recsize
);
511 * kfifo_to_user_rec - gets data from the FIFO and write it to user space
512 * @fifo: the fifo to be used.
513 * @to: where the data must be copied.
514 * @n: the size of the destination buffer.
515 * @recsize: size of record field
516 * @total: pointer where the total number of to copied bytes should stored
518 * This function copies at most @n bytes from the FIFO to the @to.
519 * In case of an error, the function returns the number of bytes which cannot
521 * If the returned value is equal or less the @n value, the copy_to_user()
522 * functions has failed. Otherwise the record doesn't fit into the @to buffer.
524 * Note that with only one concurrent reader and one concurrent
525 * writer, you don't need extra locking to use these functions.
527 static inline __must_check
unsigned int kfifo_to_user_rec(struct kfifo
*fifo
,
528 void __user
*to
, unsigned int n
, unsigned int recsize
,
531 if (!__builtin_constant_p(recsize
))
532 return __kfifo_to_user_generic(fifo
, to
, n
, recsize
, total
);
533 return __kfifo_to_user_rec(fifo
, to
, n
, recsize
, total
);
537 * __kfifo_peek_... internal functions for peek into the next fifo record
538 * do not call it directly, use kfifo_peek_rec() instead
540 extern unsigned int __kfifo_peek_generic(struct kfifo
*fifo
,
541 unsigned int recsize
);
544 * kfifo_peek_rec - gets the size of the next FIFO record data
545 * @fifo: the fifo to be used.
546 * @recsize: size of record field
548 * This function returns the size of the next FIFO record in number of bytes
550 static inline __must_check
unsigned int kfifo_peek_rec(struct kfifo
*fifo
,
551 unsigned int recsize
)
553 if (!__builtin_constant_p(recsize
))
554 return __kfifo_peek_generic(fifo
, recsize
);
556 return kfifo_len(fifo
);
557 return __kfifo_peek_n(fifo
, recsize
);
561 * __kfifo_skip_... internal functions for skip the next fifo record
562 * do not call it directly, use kfifo_skip_rec() instead
564 extern void __kfifo_skip_generic(struct kfifo
*fifo
, unsigned int recsize
);
566 static inline void __kfifo_skip_rec(struct kfifo
*fifo
,
567 unsigned int recsize
)
572 l
= __kfifo_peek_n(fifo
, recsize
);
574 if (l
+ recsize
<= kfifo_len(fifo
)) {
575 __kfifo_add_out(fifo
, l
+ recsize
);
579 kfifo_reset_out(fifo
);
583 * kfifo_skip_rec - skip the next fifo out record
584 * @fifo: the fifo to be used.
585 * @recsize: size of record field
587 * This function skips the next FIFO record
589 static inline void kfifo_skip_rec(struct kfifo
*fifo
,
590 unsigned int recsize
)
592 if (!__builtin_constant_p(recsize
))
593 __kfifo_skip_generic(fifo
, recsize
);
595 __kfifo_skip_rec(fifo
, recsize
);
599 * kfifo_avail_rec - returns the number of bytes available in a record FIFO
600 * @fifo: the fifo to be used.
601 * @recsize: size of record field
603 static inline __must_check
unsigned int kfifo_avail_rec(struct kfifo
*fifo
,
604 unsigned int recsize
)
606 unsigned int l
= kfifo_size(fifo
) - kfifo_len(fifo
);
608 return (l
> recsize
) ? l
- recsize
: 0;