1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * A generic kernel FIFO implementation
4 *
5 * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
6 */
7
8 #include <linux/dma-mapping.h>
9 #include <linux/err.h>
10 #include <linux/export.h>
11 #include <linux/kfifo.h>
12 #include <linux/log2.h>
13 #include <linux/scatterlist.h>
14 #include <linux/slab.h>
15 #include <linux/uaccess.h>
16
17 /*
18 * internal helper to calculate the unused elements in a fifo
19 */
20 static inline unsigned int kfifo_unused(struct __kfifo *fifo)
21 {
22 return (fifo->mask + 1) - (fifo->in - fifo->out);
23 }
24
25 int __kfifo_alloc(struct __kfifo *fifo, unsigned int size,
26 size_t esize, gfp_t gfp_mask)
27 {
28 /*
29 * round up to the next power of 2, since our 'let the indices
30 * wrap' technique works only in this case.
31 */
32 size = roundup_pow_of_two(size);
33
34 fifo->in = 0;
35 fifo->out = 0;
36 fifo->esize = esize;
37
38 if (size < 2) {
39 fifo->data = NULL;
40 fifo->mask = 0;
41 return -EINVAL;
42 }
43
44 fifo->data = kmalloc_array(esize, size, gfp_mask);
45
46 if (!fifo->data) {
47 fifo->mask = 0;
48 return -ENOMEM;
49 }
50 fifo->mask = size - 1;
51
52 return 0;
53 }
54 EXPORT_SYMBOL(__kfifo_alloc);
55
56 void __kfifo_free(struct __kfifo *fifo)
57 {
58 kfree(fifo->data);
59 fifo->in = 0;
60 fifo->out = 0;
61 fifo->esize = 0;
62 fifo->data = NULL;
63 fifo->mask = 0;
64 }
65 EXPORT_SYMBOL(__kfifo_free);
66
67 int __kfifo_init(struct __kfifo *fifo, void *buffer,
68 unsigned int size, size_t esize)
69 {
70 size /= esize;
71
72 if (!is_power_of_2(size))
73 size = rounddown_pow_of_two(size);
74
75 fifo->in = 0;
76 fifo->out = 0;
77 fifo->esize = esize;
78 fifo->data = buffer;
79
80 if (size < 2) {
81 fifo->mask = 0;
82 return -EINVAL;
83 }
84 fifo->mask = size - 1;
85
86 return 0;
87 }
88 EXPORT_SYMBOL(__kfifo_init);
89
90 static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
91 unsigned int len, unsigned int off)
92 {
93 unsigned int size = fifo->mask + 1;
94 unsigned int esize = fifo->esize;
95 unsigned int l;
96
97 off &= fifo->mask;
98 if (esize != 1) {
99 off *= esize;
100 size *= esize;
101 len *= esize;
102 }
103 l = min(len, size - off);
104
105 memcpy(fifo->data + off, src, l);
106 memcpy(fifo->data, src + l, len - l);
107 /*
108 * make sure that the data in the fifo is up to date before
109 * incrementing the fifo->in index counter
110 */
111 smp_wmb();
112 }
113
114 unsigned int __kfifo_in(struct __kfifo *fifo,
115 const void *buf, unsigned int len)
116 {
117 unsigned int l;
118
119 l = kfifo_unused(fifo);
120 if (len > l)
121 len = l;
122
123 kfifo_copy_in(fifo, buf, len, fifo->in);
124 fifo->in += len;
125 return len;
126 }
127 EXPORT_SYMBOL(__kfifo_in);
128
129 static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
130 unsigned int len, unsigned int off)
131 {
132 unsigned int size = fifo->mask + 1;
133 unsigned int esize = fifo->esize;
134 unsigned int l;
135
136 off &= fifo->mask;
137 if (esize != 1) {
138 off *= esize;
139 size *= esize;
140 len *= esize;
141 }
142 l = min(len, size - off);
143
144 memcpy(dst, fifo->data + off, l);
145 memcpy(dst + l, fifo->data, len - l);
146 /*
147 * make sure that the data is copied before
148 * incrementing the fifo->out index counter
149 */
150 smp_wmb();
151 }
152
153 unsigned int __kfifo_out_peek(struct __kfifo *fifo,
154 void *buf, unsigned int len)
155 {
156 unsigned int l;
157
158 l = fifo->in - fifo->out;
159 if (len > l)
160 len = l;
161
162 kfifo_copy_out(fifo, buf, len, fifo->out);
163 return len;
164 }
165 EXPORT_SYMBOL(__kfifo_out_peek);
166
167 unsigned int __kfifo_out_linear(struct __kfifo *fifo,
168 unsigned int *tail, unsigned int n)
169 {
170 unsigned int size = fifo->mask + 1;
171 unsigned int off = fifo->out & fifo->mask;
172
173 if (tail)
174 *tail = off;
175
176 return min3(n, fifo->in - fifo->out, size - off);
177 }
178 EXPORT_SYMBOL(__kfifo_out_linear);
179
180 unsigned int __kfifo_out(struct __kfifo *fifo,
181 void *buf, unsigned int len)
182 {
183 len = __kfifo_out_peek(fifo, buf, len);
184 fifo->out += len;
185 return len;
186 }
187 EXPORT_SYMBOL(__kfifo_out);
188
189 static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
190 const void __user *from, unsigned int len, unsigned int off,
191 unsigned int *copied)
192 {
193 unsigned int size = fifo->mask + 1;
194 unsigned int esize = fifo->esize;
195 unsigned int l;
196 unsigned long ret;
197
198 off &= fifo->mask;
199 if (esize != 1) {
200 off *= esize;
201 size *= esize;
202 len *= esize;
203 }
204 l = min(len, size - off);
205
206 ret = copy_from_user(fifo->data + off, from, l);
207 if (unlikely(ret))
208 ret = DIV_ROUND_UP(ret + len - l, esize);
209 else {
210 ret = copy_from_user(fifo->data, from + l, len - l);
211 if (unlikely(ret))
212 ret = DIV_ROUND_UP(ret, esize);
213 }
214 /*
215 * make sure that the data in the fifo is up to date before
216 * incrementing the fifo->in index counter
217 */
218 smp_wmb();
219 *copied = len - ret * esize;
220 /* return the number of elements which are not copied */
221 return ret;
222 }
223
224 int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
225 unsigned long len, unsigned int *copied)
226 {
227 unsigned int l;
228 unsigned long ret;
229 unsigned int esize = fifo->esize;
230 int err;
231
232 if (esize != 1)
233 len /= esize;
234
235 l = kfifo_unused(fifo);
236 if (len > l)
237 len = l;
238
239 ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
240 if (unlikely(ret)) {
241 len -= ret;
242 err = -EFAULT;
243 } else
244 err = 0;
245 fifo->in += len;
246 return err;
247 }
248 EXPORT_SYMBOL(__kfifo_from_user);
249
250 static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
251 unsigned int len, unsigned int off, unsigned int *copied)
252 {
253 unsigned int l;
254 unsigned long ret;
255 unsigned int size = fifo->mask + 1;
256 unsigned int esize = fifo->esize;
257
258 off &= fifo->mask;
259 if (esize != 1) {
260 off *= esize;
261 size *= esize;
262 len *= esize;
263 }
264 l = min(len, size - off);
265
266 ret = copy_to_user(to, fifo->data + off, l);
267 if (unlikely(ret))
268 ret = DIV_ROUND_UP(ret + len - l, esize);
269 else {
270 ret = copy_to_user(to + l, fifo->data, len - l);
271 if (unlikely(ret))
272 ret = DIV_ROUND_UP(ret, esize);
273 }
274 /*
275 * make sure that the data is copied before
276 * incrementing the fifo->out index counter
277 */
278 smp_wmb();
279 *copied = len - ret * esize;
280 /* return the number of elements which are not copied */
281 return ret;
282 }
283
284 int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
285 unsigned long len, unsigned int *copied)
286 {
287 unsigned int l;
288 unsigned long ret;
289 unsigned int esize = fifo->esize;
290 int err;
291
292 if (esize != 1)
293 len /= esize;
294
295 l = fifo->in - fifo->out;
296 if (len > l)
297 len = l;
298 ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
299 if (unlikely(ret)) {
300 len -= ret;
301 err = -EFAULT;
302 } else
303 err = 0;
304 fifo->out += len;
305 return err;
306 }
307 EXPORT_SYMBOL(__kfifo_to_user);
308
309 static unsigned int setup_sgl_buf(struct __kfifo *fifo, struct scatterlist *sgl,
310 unsigned int data_offset, int nents,
311 unsigned int len, dma_addr_t dma)
312 {
313 const void *buf = fifo->data + data_offset;
314
315 if (!nents || !len)
316 return 0;
317
318 sg_set_buf(sgl, buf, len);
319
320 if (dma != DMA_MAPPING_ERROR) {
321 sg_dma_address(sgl) = dma + data_offset;
322 sg_dma_len(sgl) = len;
323 }
324
325 return 1;
326 }
327
328 static unsigned int setup_sgl(struct __kfifo *fifo, struct scatterlist *sgl,
329 int nents, unsigned int len, unsigned int off, dma_addr_t dma)
330 {
331 unsigned int size = fifo->mask + 1;
332 unsigned int esize = fifo->esize;
333 unsigned int len_to_end;
334 unsigned int n;
335
336 off &= fifo->mask;
337 if (esize != 1) {
338 off *= esize;
339 size *= esize;
340 len *= esize;
341 }
342 len_to_end = min(len, size - off);
343
344 n = setup_sgl_buf(fifo, sgl, off, nents, len_to_end, dma);
345 n += setup_sgl_buf(fifo, sgl + n, 0, nents - n, len - len_to_end, dma);
346
347 return n;
348 }
349
350 unsigned int __kfifo_dma_in_prepare(struct __kfifo *fifo,
351 struct scatterlist *sgl, int nents, unsigned int len,
352 dma_addr_t dma)
353 {
354 unsigned int l;
355
356 l = kfifo_unused(fifo);
357 if (len > l)
358 len = l;
359
360 return setup_sgl(fifo, sgl, nents, len, fifo->in, dma);
361 }
362 EXPORT_SYMBOL(__kfifo_dma_in_prepare);
363
364 unsigned int __kfifo_dma_out_prepare(struct __kfifo *fifo,
365 struct scatterlist *sgl, int nents, unsigned int len,
366 dma_addr_t dma)
367 {
368 unsigned int l;
369
370 l = fifo->in - fifo->out;
371 if (len > l)
372 len = l;
373
374 return setup_sgl(fifo, sgl, nents, len, fifo->out, dma);
375 }
376 EXPORT_SYMBOL(__kfifo_dma_out_prepare);
377
378 unsigned int __kfifo_max_r(unsigned int len, size_t recsize)
379 {
380 unsigned int max = (1 << (recsize << 3)) - 1;
381
382 if (len > max)
383 return max;
384 return len;
385 }
386 EXPORT_SYMBOL(__kfifo_max_r);
387
388 #define __KFIFO_PEEK(data, out, mask) \
389 ((data)[(out) & (mask)])
390 /*
391 * __kfifo_peek_n internal helper function for determinate the length of
392 * the next record in the fifo
393 */
394 static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
395 {
396 unsigned int l;
397 unsigned int mask = fifo->mask;
398 unsigned char *data = fifo->data;
399
400 l = __KFIFO_PEEK(data, fifo->out, mask);
401
402 if (--recsize)
403 l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
404
405 return l;
406 }
407
408 #define __KFIFO_POKE(data, in, mask, val) \
409 ( \
410 (data)[(in) & (mask)] = (unsigned char)(val) \
411 )
412
413 /*
414 * __kfifo_poke_n internal helper function for storing the length of
415 * the record into the fifo
416 */
417 static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
418 {
419 unsigned int mask = fifo->mask;
420 unsigned char *data = fifo->data;
421
422 __KFIFO_POKE(data, fifo->in, mask, n);
423
424 if (recsize > 1)
425 __KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
426 }
427
428 unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
429 {
430 return __kfifo_peek_n(fifo, recsize);
431 }
432 EXPORT_SYMBOL(__kfifo_len_r);
433
434 unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
435 unsigned int len, size_t recsize)
436 {
437 if (len + recsize > kfifo_unused(fifo))
438 return 0;
439
440 __kfifo_poke_n(fifo, len, recsize);
441
442 kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
443 fifo->in += len + recsize;
444 return len;
445 }
446 EXPORT_SYMBOL(__kfifo_in_r);
447
448 static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
449 void *buf, unsigned int len, size_t recsize, unsigned int *n)
450 {
451 *n = __kfifo_peek_n(fifo, recsize);
452
453 if (len > *n)
454 len = *n;
455
456 kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
457 return len;
458 }
459
460 unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
461 unsigned int len, size_t recsize)
462 {
463 unsigned int n;
464
465 if (fifo->in == fifo->out)
466 return 0;
467
468 return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
469 }
470 EXPORT_SYMBOL(__kfifo_out_peek_r);
471
472 unsigned int __kfifo_out_linear_r(struct __kfifo *fifo,
473 unsigned int *tail, unsigned int n, size_t recsize)
474 {
475 if (fifo->in == fifo->out)
476 return 0;
477
478 if (tail)
479 *tail = fifo->out + recsize;
480
481 return min(n, __kfifo_peek_n(fifo, recsize));
482 }
483 EXPORT_SYMBOL(__kfifo_out_linear_r);
484
485 unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
486 unsigned int len, size_t recsize)
487 {
488 unsigned int n;
489
490 if (fifo->in == fifo->out)
491 return 0;
492
493 len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
494 fifo->out += n + recsize;
495 return len;
496 }
497 EXPORT_SYMBOL(__kfifo_out_r);
498
499 void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
500 {
501 unsigned int n;
502
503 n = __kfifo_peek_n(fifo, recsize);
504 fifo->out += n + recsize;
505 }
506 EXPORT_SYMBOL(__kfifo_skip_r);
507
508 int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
509 unsigned long len, unsigned int *copied, size_t recsize)
510 {
511 unsigned long ret;
512
513 len = __kfifo_max_r(len, recsize);
514
515 if (len + recsize > kfifo_unused(fifo)) {
516 *copied = 0;
517 return 0;
518 }
519
520 __kfifo_poke_n(fifo, len, recsize);
521
522 ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
523 if (unlikely(ret)) {
524 *copied = 0;
525 return -EFAULT;
526 }
527 fifo->in += len + recsize;
528 return 0;
529 }
530 EXPORT_SYMBOL(__kfifo_from_user_r);
531
532 int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
533 unsigned long len, unsigned int *copied, size_t recsize)
534 {
535 unsigned long ret;
536 unsigned int n;
537
538 if (fifo->in == fifo->out) {
539 *copied = 0;
540 return 0;
541 }
542
543 n = __kfifo_peek_n(fifo, recsize);
544 if (len > n)
545 len = n;
546
547 ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
548 if (unlikely(ret)) {
549 *copied = 0;
550 return -EFAULT;
551 }
552 fifo->out += n + recsize;
553 return 0;
554 }
555 EXPORT_SYMBOL(__kfifo_to_user_r);
556
557 unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
558 struct scatterlist *sgl, int nents, unsigned int len, size_t recsize,
559 dma_addr_t dma)
560 {
561 BUG_ON(!nents);
562
563 len = __kfifo_max_r(len, recsize);
564
565 if (len + recsize > kfifo_unused(fifo))
566 return 0;
567
568 return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize, dma);
569 }
570 EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
571
572 void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
573 unsigned int len, size_t recsize)
574 {
575 len = __kfifo_max_r(len, recsize);
576 __kfifo_poke_n(fifo, len, recsize);
577 fifo->in += len + recsize;
578 }
579 EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
580
581 unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
582 struct scatterlist *sgl, int nents, unsigned int len, size_t recsize,
583 dma_addr_t dma)
584 {
585 BUG_ON(!nents);
586
587 len = __kfifo_max_r(len, recsize);
588
589 if (len + recsize > fifo->in - fifo->out)
590 return 0;
591
592 return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize, dma);
593 }
594 EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
595
596
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