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1/*
2 * A generic kernel FIFO implementation
3 *
4 * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 *
20 */
21
22#include <linux/kernel.h>
23#include <linux/module.h>
24#include <linux/slab.h>
25#include <linux/err.h>
26#include <linux/log2.h>
27#include <linux/uaccess.h>
28#include <linux/kfifo.h>
29
30/*
31 * internal helper to calculate the unused elements in a fifo
32 */
33static inline unsigned int kfifo_unused(struct __kfifo *fifo)
34{
35 return (fifo->mask + 1) - (fifo->in - fifo->out);
36}
37
38int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
39 size_t esize, gfp_t gfp_mask)
40{
41 /*
42 * round down to the next power of 2, since our 'let the indices
43 * wrap' technique works only in this case.
44 */
45 if (!is_power_of_2(size))
46 size = rounddown_pow_of_two(size);
47
48 fifo->in = 0;
49 fifo->out = 0;
50 fifo->esize = esize;
51
52 if (size < 2) {
53 fifo->data = NULL;
54 fifo->mask = 0;
55 return -EINVAL;
56 }
57
58 fifo->data = kmalloc(size * esize, gfp_mask);
59
60 if (!fifo->data) {
61 fifo->mask = 0;
62 return -ENOMEM;
63 }
64 fifo->mask = size - 1;
65
66 return 0;
67}
68EXPORT_SYMBOL(__kfifo_alloc);
69
70void __kfifo_free(struct __kfifo *fifo)
71{
72 kfree(fifo->data);
73 fifo->in = 0;
74 fifo->out = 0;
75 fifo->esize = 0;
76 fifo->data = NULL;
77 fifo->mask = 0;
78}
79EXPORT_SYMBOL(__kfifo_free);
80
81int __kfifo_init(struct __kfifo *fifo, void *buffer,
82 unsigned int size, size_t esize)
83{
84 size /= esize;
85
86 if (!is_power_of_2(size))
87 size = rounddown_pow_of_two(size);
88
89 fifo->in = 0;
90 fifo->out = 0;
91 fifo->esize = esize;
92 fifo->data = buffer;
93
94 if (size < 2) {
95 fifo->mask = 0;
96 return -EINVAL;
97 }
98 fifo->mask = size - 1;
99
100 return 0;
101}
102EXPORT_SYMBOL(__kfifo_init);
103
104static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
105 unsigned int len, unsigned int off)
106{
107 unsigned int size = fifo->mask + 1;
108 unsigned int esize = fifo->esize;
109 unsigned int l;
110
111 off &= fifo->mask;
112 if (esize != 1) {
113 off *= esize;
114 size *= esize;
115 len *= esize;
116 }
117 l = min(len, size - off);
118
119 memcpy(fifo->data + off, src, l);
120 memcpy(fifo->data, src + l, len - l);
121 /*
122 * make sure that the data in the fifo is up to date before
123 * incrementing the fifo->in index counter
124 */
125 smp_wmb();
126}
127
128unsigned int __kfifo_in(struct __kfifo *fifo,
129 const void *buf, unsigned int len)
130{
131 unsigned int l;
132
133 l = kfifo_unused(fifo);
134 if (len > l)
135 len = l;
136
137 kfifo_copy_in(fifo, buf, len, fifo->in);
138 fifo->in += len;
139 return len;
140}
141EXPORT_SYMBOL(__kfifo_in);
142
143static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
144 unsigned int len, unsigned int off)
145{
146 unsigned int size = fifo->mask + 1;
147 unsigned int esize = fifo->esize;
148 unsigned int l;
149
150 off &= fifo->mask;
151 if (esize != 1) {
152 off *= esize;
153 size *= esize;
154 len *= esize;
155 }
156 l = min(len, size - off);
157
158 memcpy(dst, fifo->data + off, l);
159 memcpy(dst + l, fifo->data, len - l);
160 /*
161 * make sure that the data is copied before
162 * incrementing the fifo->out index counter
163 */
164 smp_wmb();
165}
166
167unsigned int __kfifo_out_peek(struct __kfifo *fifo,
168 void *buf, unsigned int len)
169{
170 unsigned int l;
171
172 l = fifo->in - fifo->out;
173 if (len > l)
174 len = l;
175
176 kfifo_copy_out(fifo, buf, len, fifo->out);
177 return len;
178}
179EXPORT_SYMBOL(__kfifo_out_peek);
180
181unsigned int __kfifo_out(struct __kfifo *fifo,
182 void *buf, unsigned int len)
183{
184 len = __kfifo_out_peek(fifo, buf, len);
185 fifo->out += len;
186 return len;
187}
188EXPORT_SYMBOL(__kfifo_out);
189
190static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
191 const void __user *from, unsigned int len, unsigned int off,
192 unsigned int *copied)
193{
194 unsigned int size = fifo->mask + 1;
195 unsigned int esize = fifo->esize;
196 unsigned int l;
197 unsigned long ret;
198
199 off &= fifo->mask;
200 if (esize != 1) {
201 off *= esize;
202 size *= esize;
203 len *= esize;
204 }
205 l = min(len, size - off);
206
207 ret = copy_from_user(fifo->data + off, from, l);
208 if (unlikely(ret))
209 ret = DIV_ROUND_UP(ret + len - l, esize);
210 else {
211 ret = copy_from_user(fifo->data, from + l, len - l);
212 if (unlikely(ret))
213 ret = DIV_ROUND_UP(ret, esize);
214 }
215 /*
216 * make sure that the data in the fifo is up to date before
217 * incrementing the fifo->in index counter
218 */
219 smp_wmb();
220 *copied = len - ret;
221 /* return the number of elements which are not copied */
222 return ret;
223}
224
225int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
226 unsigned long len, unsigned int *copied)
227{
228 unsigned int l;
229 unsigned long ret;
230 unsigned int esize = fifo->esize;
231 int err;
232
233 if (esize != 1)
234 len /= esize;
235
236 l = kfifo_unused(fifo);
237 if (len > l)
238 len = l;
239
240 ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
241 if (unlikely(ret)) {
242 len -= ret;
243 err = -EFAULT;
244 } else
245 err = 0;
246 fifo->in += len;
247 return err;
248}
249EXPORT_SYMBOL(__kfifo_from_user);
250
251static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
252 unsigned int len, unsigned int off, unsigned int *copied)
253{
254 unsigned int l;
255 unsigned long ret;
256 unsigned int size = fifo->mask + 1;
257 unsigned int esize = fifo->esize;
258
259 off &= fifo->mask;
260 if (esize != 1) {
261 off *= esize;
262 size *= esize;
263 len *= esize;
264 }
265 l = min(len, size - off);
266
267 ret = copy_to_user(to, fifo->data + off, l);
268 if (unlikely(ret))
269 ret = DIV_ROUND_UP(ret + len - l, esize);
270 else {
271 ret = copy_to_user(to + l, fifo->data, len - l);
272 if (unlikely(ret))
273 ret = DIV_ROUND_UP(ret, esize);
274 }
275 /*
276 * make sure that the data is copied before
277 * incrementing the fifo->out index counter
278 */
279 smp_wmb();
280 *copied = len - ret;
281 /* return the number of elements which are not copied */
282 return ret;
283}
284
285int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
286 unsigned long len, unsigned int *copied)
287{
288 unsigned int l;
289 unsigned long ret;
290 unsigned int esize = fifo->esize;
291 int err;
292
293 if (esize != 1)
294 len /= esize;
295
296 l = fifo->in - fifo->out;
297 if (len > l)
298 len = l;
299 ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
300 if (unlikely(ret)) {
301 len -= ret;
302 err = -EFAULT;
303 } else
304 err = 0;
305 fifo->out += len;
306 return err;
307}
308EXPORT_SYMBOL(__kfifo_to_user);
309
310static int setup_sgl_buf(struct scatterlist *sgl, void *buf,
311 int nents, unsigned int len)
312{
313 int n;
314 unsigned int l;
315 unsigned int off;
316 struct page *page;
317
318 if (!nents)
319 return 0;
320
321 if (!len)
322 return 0;
323
324 n = 0;
325 page = virt_to_page(buf);
326 off = offset_in_page(buf);
327 l = 0;
328
329 while (len >= l + PAGE_SIZE - off) {
330 struct page *npage;
331
332 l += PAGE_SIZE;
333 buf += PAGE_SIZE;
334 npage = virt_to_page(buf);
335 if (page_to_phys(page) != page_to_phys(npage) - l) {
336 sg_set_page(sgl, page, l - off, off);
337 sgl = sg_next(sgl);
338 if (++n == nents || sgl == NULL)
339 return n;
340 page = npage;
341 len -= l - off;
342 l = off = 0;
343 }
344 }
345 sg_set_page(sgl, page, len, off);
346 return n + 1;
347}
348
349static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
350 int nents, unsigned int len, unsigned int off)
351{
352 unsigned int size = fifo->mask + 1;
353 unsigned int esize = fifo->esize;
354 unsigned int l;
355 unsigned int n;
356
357 off &= fifo->mask;
358 if (esize != 1) {
359 off *= esize;
360 size *= esize;
361 len *= esize;
362 }
363 l = min(len, size - off);
364
365 n = setup_sgl_buf(sgl, fifo->data + off, nents, l);
366 n += setup_sgl_buf(sgl + n, fifo->data, nents - n, len - l);
367
368 return n;
369}
370
371unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
372 struct scatterlist *sgl, int nents, unsigned int len)
373{
374 unsigned int l;
375
376 l = kfifo_unused(fifo);
377 if (len > l)
378 len = l;
379
380 return setup_sgl(fifo, sgl, nents, len, fifo->in);
381}
382EXPORT_SYMBOL(__kfifo_dma_in_prepare);
383
384unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
385 struct scatterlist *sgl, int nents, unsigned int len)
386{
387 unsigned int l;
388
389 l = fifo->in - fifo->out;
390 if (len > l)
391 len = l;
392
393 return setup_sgl(fifo, sgl, nents, len, fifo->out);
394}
395EXPORT_SYMBOL(__kfifo_dma_out_prepare);
396
397unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
398{
399 unsigned int max = (1 << (recsize << 3)) - 1;
400
401 if (len > max)
402 return max;
403 return len;
404}
405
406#define __KFIFO_PEEK(data, out, mask) \
407 ((data)[(out) & (mask)])
408/*
409 * __kfifo_peek_n internal helper function for determinate the length of
410 * the next record in the fifo
411 */
412static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
413{
414 unsigned int l;
415 unsigned int mask = fifo->mask;
416 unsigned char *data = fifo->data;
417
418 l = __KFIFO_PEEK(data, fifo->out, mask);
419
420 if (--recsize)
421 l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
422
423 return l;
424}
425
426#define __KFIFO_POKE(data, in, mask, val) \
427 ( \
428 (data)[(in) & (mask)] = (unsigned char)(val) \
429 )
430
431/*
432 * __kfifo_poke_n internal helper function for storeing the length of
433 * the record into the fifo
434 */
435static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
436{
437 unsigned int mask = fifo->mask;
438 unsigned char *data = fifo->data;
439
440 __KFIFO_POKE(data, fifo->in, mask, n);
441
442 if (recsize > 1)
443 __KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
444}
445
446unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
447{
448 return __kfifo_peek_n(fifo, recsize);
449}
450EXPORT_SYMBOL(__kfifo_len_r);
451
452unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
453 unsigned int len, size_t recsize)
454{
455 if (len + recsize > kfifo_unused(fifo))
456 return 0;
457
458 __kfifo_poke_n(fifo, len, recsize);
459
460 kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
461 fifo->in += len + recsize;
462 return len;
463}
464EXPORT_SYMBOL(__kfifo_in_r);
465
466static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
467 void *buf, unsigned int len, size_t recsize, unsigned int *n)
468{
469 *n = __kfifo_peek_n(fifo, recsize);
470
471 if (len > *n)
472 len = *n;
473
474 kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
475 return len;
476}
477
478unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
479 unsigned int len, size_t recsize)
480{
481 unsigned int n;
482
483 if (fifo->in == fifo->out)
484 return 0;
485
486 return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
487}
488EXPORT_SYMBOL(__kfifo_out_peek_r);
489
490unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
491 unsigned int len, size_t recsize)
492{
493 unsigned int n;
494
495 if (fifo->in == fifo->out)
496 return 0;
497
498 len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
499 fifo->out += n + recsize;
500 return len;
501}
502EXPORT_SYMBOL(__kfifo_out_r);
503
504void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
505{
506 unsigned int n;
507
508 n = __kfifo_peek_n(fifo, recsize);
509 fifo->out += n + recsize;
510}
511EXPORT_SYMBOL(__kfifo_skip_r);
512
513int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
514 unsigned long len, unsigned int *copied, size_t recsize)
515{
516 unsigned long ret;
517
518 len = __kfifo_max_r(len, recsize);
519
520 if (len + recsize > kfifo_unused(fifo)) {
521 *copied = 0;
522 return 0;
523 }
524
525 __kfifo_poke_n(fifo, len, recsize);
526
527 ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
528 if (unlikely(ret)) {
529 *copied = 0;
530 return -EFAULT;
531 }
532 fifo->in += len + recsize;
533 return 0;
534}
535EXPORT_SYMBOL(__kfifo_from_user_r);
536
537int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
538 unsigned long len, unsigned int *copied, size_t recsize)
539{
540 unsigned long ret;
541 unsigned int n;
542
543 if (fifo->in == fifo->out) {
544 *copied = 0;
545 return 0;
546 }
547
548 n = __kfifo_peek_n(fifo, recsize);
549 if (len > n)
550 len = n;
551
552 ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
553 if (unlikely(ret)) {
554 *copied = 0;
555 return -EFAULT;
556 }
557 fifo->out += n + recsize;
558 return 0;
559}
560EXPORT_SYMBOL(__kfifo_to_user_r);
561
562unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
563 struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
564{
565 if (!nents)
566 BUG();
567
568 len = __kfifo_max_r(len, recsize);
569
570 if (len + recsize > kfifo_unused(fifo))
571 return 0;
572
573 return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
574}
575EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
576
577void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
578 unsigned int len, size_t recsize)
579{
580 len = __kfifo_max_r(len, recsize);
581 __kfifo_poke_n(fifo, len, recsize);
582 fifo->in += len + recsize;
583}
584EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
585
586unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
587 struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
588{
589 if (!nents)
590 BUG();
591
592 len = __kfifo_max_r(len, recsize);
593
594 if (len + recsize > fifo->in - fifo->out)
595 return 0;
596
597 return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
598}
599EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
600
601void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
602{
603 unsigned int len;
604
605 len = __kfifo_peek_n(fifo, recsize);
606 fifo->out += len + recsize;
607}
608EXPORT_SYMBOL(__kfifo_dma_out_finish_r);