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/export.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}
405EXPORT_SYMBOL(__kfifo_max_r);
406
407#define	__KFIFO_PEEK(data, out, mask) \
408	((data)[(out) & (mask)])
409/*
410 * __kfifo_peek_n internal helper function for determinate the length of
411 * the next record in the fifo
412 */
413static unsigned int __kfifo_peek_n(struct __kfifo *fifo, size_t recsize)
414{
415	unsigned int l;
416	unsigned int mask = fifo->mask;
417	unsigned char *data = fifo->data;
418
419	l = __KFIFO_PEEK(data, fifo->out, mask);
420
421	if (--recsize)
422		l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;
423
424	return l;
425}
426
427#define	__KFIFO_POKE(data, in, mask, val) \
428	( \
429	(data)[(in) & (mask)] = (unsigned char)(val) \
430	)
431
432/*
433 * __kfifo_poke_n internal helper function for storeing the length of
434 * the record into the fifo
435 */
436static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, size_t recsize)
437{
438	unsigned int mask = fifo->mask;
439	unsigned char *data = fifo->data;
440
441	__KFIFO_POKE(data, fifo->in, mask, n);
442
443	if (recsize > 1)
444		__KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
445}
446
447unsigned int __kfifo_len_r(struct __kfifo *fifo, size_t recsize)
448{
449	return __kfifo_peek_n(fifo, recsize);
450}
451EXPORT_SYMBOL(__kfifo_len_r);
452
453unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
454		unsigned int len, size_t recsize)
455{
456	if (len + recsize > kfifo_unused(fifo))
457		return 0;
458
459	__kfifo_poke_n(fifo, len, recsize);
460
461	kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
462	fifo->in += len + recsize;
463	return len;
464}
465EXPORT_SYMBOL(__kfifo_in_r);
466
467static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
468	void *buf, unsigned int len, size_t recsize, unsigned int *n)
469{
470	*n = __kfifo_peek_n(fifo, recsize);
471
472	if (len > *n)
473		len = *n;
474
475	kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
476	return len;
477}
478
479unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
480		unsigned int len, size_t recsize)
481{
482	unsigned int n;
483
484	if (fifo->in == fifo->out)
485		return 0;
486
487	return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
488}
489EXPORT_SYMBOL(__kfifo_out_peek_r);
490
491unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
492		unsigned int len, size_t recsize)
493{
494	unsigned int n;
495
496	if (fifo->in == fifo->out)
497		return 0;
498
499	len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
500	fifo->out += n + recsize;
501	return len;
502}
503EXPORT_SYMBOL(__kfifo_out_r);
504
505void __kfifo_skip_r(struct __kfifo *fifo, size_t recsize)
506{
507	unsigned int n;
508
509	n = __kfifo_peek_n(fifo, recsize);
510	fifo->out += n + recsize;
511}
512EXPORT_SYMBOL(__kfifo_skip_r);
513
514int __kfifo_from_user_r(struct __kfifo *fifo, const void __user *from,
515	unsigned long len, unsigned int *copied, size_t recsize)
516{
517	unsigned long ret;
518
519	len = __kfifo_max_r(len, recsize);
520
521	if (len + recsize > kfifo_unused(fifo)) {
522		*copied = 0;
523		return 0;
524	}
525
526	__kfifo_poke_n(fifo, len, recsize);
527
528	ret = kfifo_copy_from_user(fifo, from, len, fifo->in + recsize, copied);
529	if (unlikely(ret)) {
530		*copied = 0;
531		return -EFAULT;
532	}
533	fifo->in += len + recsize;
534	return 0;
535}
536EXPORT_SYMBOL(__kfifo_from_user_r);
537
538int __kfifo_to_user_r(struct __kfifo *fifo, void __user *to,
539	unsigned long len, unsigned int *copied, size_t recsize)
540{
541	unsigned long ret;
542	unsigned int n;
543
544	if (fifo->in == fifo->out) {
545		*copied = 0;
546		return 0;
547	}
548
549	n = __kfifo_peek_n(fifo, recsize);
550	if (len > n)
551		len = n;
552
553	ret = kfifo_copy_to_user(fifo, to, len, fifo->out + recsize, copied);
554	if (unlikely(ret)) {
555		*copied = 0;
556		return -EFAULT;
557	}
558	fifo->out += n + recsize;
559	return 0;
560}
561EXPORT_SYMBOL(__kfifo_to_user_r);
562
563unsigned int __kfifo_dma_in_prepare_r(struct __kfifo *fifo,
564	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
565{
566	if (!nents)
567		BUG();
568
569	len = __kfifo_max_r(len, recsize);
570
571	if (len + recsize > kfifo_unused(fifo))
572		return 0;
573
574	return setup_sgl(fifo, sgl, nents, len, fifo->in + recsize);
575}
576EXPORT_SYMBOL(__kfifo_dma_in_prepare_r);
577
578void __kfifo_dma_in_finish_r(struct __kfifo *fifo,
579	unsigned int len, size_t recsize)
580{
581	len = __kfifo_max_r(len, recsize);
582	__kfifo_poke_n(fifo, len, recsize);
583	fifo->in += len + recsize;
584}
585EXPORT_SYMBOL(__kfifo_dma_in_finish_r);
586
587unsigned int __kfifo_dma_out_prepare_r(struct __kfifo *fifo,
588	struct scatterlist *sgl, int nents, unsigned int len, size_t recsize)
589{
590	if (!nents)
591		BUG();
592
593	len = __kfifo_max_r(len, recsize);
594
595	if (len + recsize > fifo->in - fifo->out)
596		return 0;
597
598	return setup_sgl(fifo, sgl, nents, len, fifo->out + recsize);
599}
600EXPORT_SYMBOL(__kfifo_dma_out_prepare_r);
601
602void __kfifo_dma_out_finish_r(struct __kfifo *fifo, size_t recsize)
603{
604	unsigned int len;
605
606	len = __kfifo_peek_n(fifo, recsize);
607	fifo->out += len + recsize;
608}
609EXPORT_SYMBOL(__kfifo_dma_out_finish_r);