2 * Copyright (c) 2010 Isilon Systems, Inc.
3 * Copyright (c) 2010 iX Systems, Inc.
4 * Copyright (c) 2010 Panasas, Inc.
5 * Copyright (c) 2013-2017 Mellanox Technologies, Ltd.
6 * Copyright (c) 2015 Matthew Dillon <dillon@backplane.com>
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
12 * 1. Redistributions of source code must retain the above copyright
13 * notice unmodified, this list of conditions, and the following
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 #ifndef _LINUX_SCATTERLIST_H_
33 #define _LINUX_SCATTERLIST_H_
35 #include <linux/page.h>
36 #include <linux/slab.h>
40 unsigned long page_link;
41 #define SG_PAGE_LINK_CHAIN 0x1UL
42 #define SG_PAGE_LINK_LAST 0x2UL
43 #define SG_PAGE_LINK_MASK 0x3UL
49 CTASSERT((sizeof(struct scatterlist) & SG_PAGE_LINK_MASK) == 0);
52 struct scatterlist *sgl;
54 unsigned int orig_nents;
58 struct scatterlist *sg;
59 unsigned int sg_pgoffset;
67 #define SCATTERLIST_MAX_SEGMENT (-1U & ~(PAGE_SIZE - 1))
69 #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
71 #define SG_MAGIC 0x87654321UL
72 #define SG_CHAIN SG_PAGE_LINK_CHAIN
73 #define SG_END SG_PAGE_LINK_LAST
75 #define sg_is_chain(sg) ((sg)->page_link & SG_PAGE_LINK_CHAIN)
76 #define sg_is_last(sg) ((sg)->page_link & SG_PAGE_LINK_LAST)
77 #define sg_chain_ptr(sg) \
78 ((struct scatterlist *) ((sg)->page_link & ~SG_PAGE_LINK_MASK))
80 #define sg_dma_address(sg) (sg)->address
81 #define sg_dma_len(sg) (sg)->length
83 #define for_each_sg_page(sgl, iter, nents, pgoffset) \
84 for (_sg_iter_init(sgl, iter, nents, pgoffset); \
85 (iter)->sg; _sg_iter_next(iter))
87 #define for_each_sg(sglist, sg, sgmax, iter) \
88 for (iter = 0, sg = (sglist); iter < (sgmax); iter++, sg = sg_next(sg))
90 typedef struct scatterlist *(sg_alloc_fn) (unsigned int, gfp_t);
91 typedef void (sg_free_fn) (struct scatterlist *, unsigned int);
94 sg_assign_page(struct scatterlist *sg, struct page *page)
96 unsigned long page_link = sg->page_link & SG_PAGE_LINK_MASK;
98 sg->page_link = page_link | (unsigned long)page;
102 sg_set_page(struct scatterlist *sg, struct page *page, unsigned int len,
105 sg_assign_page(sg, page);
110 static inline struct page *
111 sg_page(struct scatterlist *sg)
113 return ((struct page *)((sg)->page_link & ~SG_PAGE_LINK_MASK));
117 sg_set_buf(struct scatterlist *sg, const void *buf, unsigned int buflen)
119 sg_set_page(sg, virt_to_page(buf), buflen,
120 ((uintptr_t)buf) & (PAGE_SIZE - 1));
123 static inline struct scatterlist *
124 sg_next(struct scatterlist *sg)
130 sg = sg_chain_ptr(sg);
134 static inline vm_paddr_t
135 sg_phys(struct scatterlist *sg)
137 return (VM_PAGE_TO_PHYS(sg_page(sg)) + sg->offset);
141 sg_virt(struct scatterlist *sg)
144 return ((void *)((unsigned long)page_address(sg_page(sg)) + sg->offset));
148 sg_chain(struct scatterlist *prv, unsigned int prv_nents,
149 struct scatterlist *sgl)
151 struct scatterlist *sg = &prv[prv_nents - 1];
155 sg->page_link = ((unsigned long)sgl |
156 SG_PAGE_LINK_CHAIN) & ~SG_PAGE_LINK_LAST;
160 sg_mark_end(struct scatterlist *sg)
162 sg->page_link |= SG_PAGE_LINK_LAST;
163 sg->page_link &= ~SG_PAGE_LINK_CHAIN;
167 sg_init_table(struct scatterlist *sg, unsigned int nents)
169 bzero(sg, sizeof(*sg) * nents);
170 sg_mark_end(&sg[nents - 1]);
173 static struct scatterlist *
174 sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
176 if (nents == SG_MAX_SINGLE_ALLOC) {
177 return ((void *)__get_free_page(gfp_mask));
179 return (kmalloc(nents * sizeof(struct scatterlist), gfp_mask));
183 sg_kfree(struct scatterlist *sg, unsigned int nents)
185 if (nents == SG_MAX_SINGLE_ALLOC) {
186 free_page((unsigned long)sg);
192 __sg_free_table(struct sg_table *table, unsigned int max_ents,
193 bool skip_first_chunk, sg_free_fn * free_fn)
195 struct scatterlist *sgl, *next;
197 if (unlikely(!table->sgl))
201 while (table->orig_nents) {
202 unsigned int alloc_size = table->orig_nents;
203 unsigned int sg_size;
205 if (alloc_size > max_ents) {
206 next = sg_chain_ptr(&sgl[max_ents - 1]);
207 alloc_size = max_ents;
208 sg_size = alloc_size - 1;
210 sg_size = alloc_size;
214 table->orig_nents -= sg_size;
215 if (skip_first_chunk)
216 skip_first_chunk = 0;
218 free_fn(sgl, alloc_size);
226 sg_free_table(struct sg_table *table)
228 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree);
232 __sg_alloc_table(struct sg_table *table, unsigned int nents,
233 unsigned int max_ents, struct scatterlist *first_chunk,
234 gfp_t gfp_mask, sg_alloc_fn *alloc_fn)
236 struct scatterlist *sg, *prv;
239 memset(table, 0, sizeof(*table));
246 unsigned int sg_size;
247 unsigned int alloc_size = left;
249 if (alloc_size > max_ents) {
250 alloc_size = max_ents;
251 sg_size = alloc_size - 1;
253 sg_size = alloc_size;
261 sg = alloc_fn(alloc_size, gfp_mask);
265 table->nents = ++table->orig_nents;
269 sg_init_table(sg, alloc_size);
270 table->nents = table->orig_nents += sg_size;
273 sg_chain(prv, max_ents, sg);
278 sg_mark_end(&sg[sg_size - 1]);
287 sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
291 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
292 NULL, gfp_mask, sg_kmalloc);
294 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree);
300 __sg_alloc_table_from_pages(struct sg_table *sgt,
301 struct page **pages, unsigned int count,
302 unsigned long off, unsigned long size,
303 unsigned int max_segment, gfp_t gfp_mask)
305 unsigned int i, segs, cur, len;
307 struct scatterlist *s;
309 if (__predict_false(!max_segment || offset_in_page(max_segment)))
313 for (segs = i = 1; i < count; ++i) {
315 if (len >= max_segment ||
316 page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) {
321 if (__predict_false((rc = sg_alloc_table(sgt, segs, gfp_mask))))
325 for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
326 unsigned long seg_size;
330 for (j = cur + 1; j < count; ++j) {
332 if (len >= max_segment || page_to_pfn(pages[j]) !=
333 page_to_pfn(pages[j - 1]) + 1)
337 seg_size = ((j - cur) << PAGE_SHIFT) - off;
338 sg_set_page(s, pages[cur], min(size, seg_size), off);
347 sg_alloc_table_from_pages(struct sg_table *sgt,
348 struct page **pages, unsigned int count,
349 unsigned long off, unsigned long size,
353 return (__sg_alloc_table_from_pages(sgt, pages, count, off, size,
354 SCATTERLIST_MAX_SEGMENT, gfp_mask));
358 sg_nents(struct scatterlist *sg)
362 for (nents = 0; sg; sg = sg_next(sg))
368 __sg_page_iter_start(struct sg_page_iter *piter,
369 struct scatterlist *sglist, unsigned int nents,
370 unsigned long pgoffset)
372 piter->internal.pg_advance = 0;
373 piter->internal.nents = nents;
376 piter->sg_pgoffset = pgoffset;
380 _sg_iter_next(struct sg_page_iter *iter)
382 struct scatterlist *sg;
383 unsigned int pgcount;
386 pgcount = (sg->offset + sg->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
389 while (iter->sg_pgoffset >= pgcount) {
390 iter->sg_pgoffset -= pgcount;
393 if (sg == NULL || iter->maxents == 0)
395 pgcount = (sg->offset + sg->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
401 sg_page_count(struct scatterlist *sg)
403 return (PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT);
407 __sg_page_iter_next(struct sg_page_iter *piter)
409 if (piter->internal.nents == 0)
411 if (piter->sg == NULL)
414 piter->sg_pgoffset += piter->internal.pg_advance;
415 piter->internal.pg_advance = 1;
417 while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
418 piter->sg_pgoffset -= sg_page_count(piter->sg);
419 piter->sg = sg_next(piter->sg);
420 if (--piter->internal.nents == 0)
422 if (piter->sg == NULL)
429 _sg_iter_init(struct scatterlist *sgl, struct sg_page_iter *iter,
430 unsigned int nents, unsigned long pgoffset)
434 iter->sg_pgoffset = pgoffset - 1;
435 iter->maxents = nents;
439 iter->sg_pgoffset = 0;
444 static inline dma_addr_t
445 sg_page_iter_dma_address(struct sg_page_iter *spi)
447 return (spi->sg->address + (spi->sg_pgoffset << PAGE_SHIFT));
450 static inline struct page *
451 sg_page_iter_page(struct sg_page_iter *piter)
453 return (nth_page(sg_page(piter->sg), piter->sg_pgoffset));
457 #endif /* _LINUX_SCATTERLIST_H_ */