1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * A generic kernel FIFO implementation
5 * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
8 #include <linux/kernel.h>
9 #include <linux/export.h>
10 #include <linux/slab.h>
11 #include <linux/err.h>
12 #include <linux/log2.h>
13 #include <linux/uaccess.h>
14 #include <linux/kfifo.h>
17 * internal helper to calculate the unused elements in a fifo
19 static inline unsigned int kfifo_unused(struct __kfifo *fifo)
21 return (fifo->mask + 1) - (fifo->in - fifo->out);
24 int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
25 size_t esize, gfp_t gfp_mask)
28 * round up to the next power of 2, since our 'let the indices
29 * wrap' technique works only in this case.
31 size = roundup_pow_of_two(size);
43 fifo->data = kmalloc_array(esize, size, gfp_mask);
49 fifo->mask = size - 1;
53 EXPORT_SYMBOL(__kfifo_alloc);
55 void __kfifo_free(struct __kfifo *fifo)
64 EXPORT_SYMBOL(__kfifo_free);
66 int __kfifo_init(struct __kfifo *fifo, void *buffer,
67 unsigned int size, size_t esize)
71 if (!is_power_of_2(size))
72 size = rounddown_pow_of_two(size);
83 fifo->mask = size - 1;
87 EXPORT_SYMBOL(__kfifo_init);
89 static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
90 unsigned int len, unsigned int off)
92 unsigned int size = fifo->mask + 1;
93 unsigned int esize = fifo->esize;
102 l = min(len, size - off);
104 memcpy(fifo->data + off, src, l);
105 memcpy(fifo->data, src + l, len - l);
107 * make sure that the data in the fifo is up to date before
108 * incrementing the fifo->in index counter
113 unsigned int __kfifo_in(struct __kfifo *fifo,
114 const void *buf, unsigned int len)
118 l = kfifo_unused(fifo);
122 kfifo_copy_in(fifo, buf, len, fifo->in);
126 EXPORT_SYMBOL(__kfifo_in);
128 static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
129 unsigned int len, unsigned int off)
131 unsigned int size = fifo->mask + 1;
132 unsigned int esize = fifo->esize;
141 l = min(len, size - off);
143 memcpy(dst, fifo->data + off, l);
144 memcpy(dst + l, fifo->data, len - l);
146 * make sure that the data is copied before
147 * incrementing the fifo->out index counter
152 unsigned int __kfifo_out_peek(struct __kfifo *fifo,
153 void *buf, unsigned int len)
157 l = fifo->in - fifo->out;
161 kfifo_copy_out(fifo, buf, len, fifo->out);
164 EXPORT_SYMBOL(__kfifo_out_peek);
166 unsigned int __kfifo_out(struct __kfifo *fifo,
167 void *buf, unsigned int len)
169 len = __kfifo_out_peek(fifo, buf, len);
173 EXPORT_SYMBOL(__kfifo_out);
175 static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
176 const void __user *from, unsigned int len, unsigned int off,
177 unsigned int *copied)
179 unsigned int size = fifo->mask + 1;
180 unsigned int esize = fifo->esize;
190 l = min(len, size - off);
192 ret = copy_from_user(fifo->data + off, from, l);
194 ret = DIV_ROUND_UP(ret + len - l, esize);
196 ret = copy_from_user(fifo->data, from + l, len - l);
198 ret = DIV_ROUND_UP(ret, esize);
201 * make sure that the data in the fifo is up to date before
202 * incrementing the fifo->in index counter
205 *copied = len - ret * esize;
206 /* return the number of elements which are not copied */
210 int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
211 unsigned long len, unsigned int *copied)
215 unsigned int esize = fifo->esize;
221 l = kfifo_unused(fifo);
225 ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
234 EXPORT_SYMBOL(__kfifo_from_user);
236 static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
237 unsigned int len, unsigned int off, unsigned int *copied)
241 unsigned int size = fifo->mask + 1;
242 unsigned int esize = fifo->esize;
250 l = min(len, size - off);
252 ret = copy_to_user(to, fifo->data + off, l);
254 ret = DIV_ROUND_UP(ret + len - l, esize);
256 ret = copy_to_user(to + l, fifo->data, len - l);
258 ret = DIV_ROUND_UP(ret, esize);
261 * make sure that the data is copied before
262 * incrementing the fifo->out index counter
265 *copied = len - ret * esize;
266 /* return the number of elements which are not copied */
270 int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
271 unsigned long len, unsigned int *copied)
275 unsigned int esize = fifo->esize;
281 l = fifo->in - fifo->out;
284 ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
293 EXPORT_SYMBOL(__kfifo_to_user);
295 static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
296 int nents, unsigned int len)
310 page = virt_to_page(buf);
311 off = offset_in_page(buf);
314 while (len >= l + PAGE_SIZE - off) {
319 npage = virt_to_page(buf);
320 if (page_to_phys(page) != page_to_phys(npage) - l) {
321 sg_set_page(sgl, page, l - off, off);
323 if (++n == nents || sgl == NULL)
330 sg_set_page(sgl, page, len, off);
334 static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
335 int nents, unsigned int len, unsigned int off)
337 unsigned int size = fifo->mask + 1;
338 unsigned int esize = fifo->esize;
348 l = min(len, size - off);
350 n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
351 n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
356 unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
357 struct scatterlist *sgl, int nents, unsigned int len)
361 l = kfifo_unused(fifo);
365 return setup_sgl(fifo, sgl, nents, len, fifo->in);
367 EXPORT_SYMBOL(__kfifo_dma_in_prepare);
369 unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
370 struct scatterlist *sgl, int nents, unsigned int len)
374 l = fifo->in - fifo->out;
378 return setup_sgl(fifo, sgl, nents, len, fifo->out);
380 EXPORT_SYMBOL(__kfifo_dma_out_prepare);
382 unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
384 unsigned int max = (1 << (recsize << 3)) - 1;
390 EXPORT_SYMBOL(__kfifo_max_r);
392 #define __KFIFO_PEEK(data, out, mask) \
393 ((data)[(out) & (mask)])
395 * __kfifo_peek_n internal helper function for determinate the length of
396 * the next record in the fifo
398 static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
401 unsigned int mask = fifo->mask;
402 unsigned char *data = fifo->data;
404 l = __KFIFO_PEEK(data, fifo->out, mask);
407 l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
412 #define __KFIFO_POKE(data, in, mask, val) \
414 (data)[(in) & (mask)] = (unsigned char)(val) \
418 * __kfifo_poke_n internal helper function for storing the length of
419 * the record into the fifo
421 static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
423 unsigned int mask = fifo->mask;
424 unsigned char *data = fifo->data;
426 __KFIFO_POKE(data, fifo->in, mask, n);
429 __KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
432 unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
434 return __kfifo_peek_n(fifo, recsize);
436 EXPORT_SYMBOL(__kfifo_len_r);
438 unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
439 unsigned int len, size_t recsize)
441 if (len + recsize > kfifo_unused(fifo))
444 __kfifo_poke_n(fifo, len, recsize);
446 kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
447 fifo->in += len + recsize;
450 EXPORT_SYMBOL(__kfifo_in_r);
452 static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
453 void *buf, unsigned int len, size_t recsize, unsigned int *n)
455 *n = __kfifo_peek_n(fifo, recsize);
460 kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
464 unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
465 unsigned int len, size_t recsize)
469 if (fifo->in == fifo->out)
472 return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
474 EXPORT_SYMBOL(__kfifo_out_peek_r);
476 unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
477 unsigned int len, size_t recsize)
481 if (fifo->in == fifo->out)
484 len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
485 fifo->out += n + recsize;
488 EXPORT_SYMBOL(__kfifo_out_r);
490 void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
494 n = __kfifo_peek_n(fifo, recsize);
495 fifo->out += n + recsize;
497 EXPORT_SYMBOL(__kfifo_skip_r);
499 int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
500 unsigned long len, unsigned int *copied, size_t recsize)
504 len = __kfifo_max_r(len, recsize);
506 if (len + recsize > kfifo_unused(fifo)) {
511 __kfifo_poke_n(fifo, len, recsize);
513 ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
518 fifo->in += len + recsize;
521 EXPORT_SYMBOL(__kfifo_from_user_r);
523 int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
524 unsigned long len, unsigned int *copied, size_t recsize)
529 if (fifo->in == fifo->out) {
534 n = __kfifo_peek_n(fifo, recsize);
538 ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
543 fifo->out += n + recsize;
546 EXPORT_SYMBOL(__kfifo_to_user_r);
548 unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
549 struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
553 len = __kfifo_max_r(len, recsize);
555 if (len + recsize > kfifo_unused(fifo))
558 return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
560 EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
562 void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
563 unsigned int len, size_t recsize)
565 len = __kfifo_max_r(len, recsize);
566 __kfifo_poke_n(fifo, len, recsize);
567 fifo->in += len + recsize;
569 EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
571 unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
572 struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
576 len = __kfifo_max_r(len, recsize);
578 if (len + recsize > fifo->in - fifo->out)
581 return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
583 EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
585 void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
589 len = __kfifo_peek_n(fifo, recsize);
590 fifo->out += len + recsize;
592 EXPORT_SYMBOL(__kfifo_dma_out_finish_r);