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
73 #define sg_is_chain(sg) ((sg)->page_link & SG_PAGE_LINK_CHAIN)
74 #define sg_is_last(sg) ((sg)->page_link & SG_PAGE_LINK_LAST)
75 #define sg_chain_ptr(sg) \
76 ((struct scatterlist *) ((sg)->page_link & ~SG_PAGE_LINK_MASK))
78 #define sg_dma_address(sg) (sg)->address
79 #define sg_dma_len(sg) (sg)->length
81 #define for_each_sg_page(sgl, iter, nents, pgoffset) \
82 for (_sg_iter_init(sgl, iter, nents, pgoffset); \
83 (iter)->sg; _sg_iter_next(iter))
85 #define for_each_sg(sglist, sg, sgmax, iter) \
86 for (iter = 0, sg = (sglist); iter < (sgmax); iter++, sg = sg_next(sg))
88 typedef struct scatterlist *(sg_alloc_fn) (unsigned int, gfp_t);
89 typedef void (sg_free_fn) (struct scatterlist *, unsigned int);
92 sg_assign_page(struct scatterlist *sg, struct page *page)
94 unsigned long page_link = sg->page_link & SG_PAGE_LINK_MASK;
96 sg->page_link = page_link | (unsigned long)page;
100 sg_set_page(struct scatterlist *sg, struct page *page, unsigned int len,
103 sg_assign_page(sg, page);
108 static inline struct page *
109 sg_page(struct scatterlist *sg)
111 return ((struct page *)((sg)->page_link & ~SG_PAGE_LINK_MASK));
115 sg_set_buf(struct scatterlist *sg, const void *buf, unsigned int buflen)
117 sg_set_page(sg, virt_to_page(buf), buflen,
118 ((uintptr_t)buf) & (PAGE_SIZE - 1));
121 static inline struct scatterlist *
122 sg_next(struct scatterlist *sg)
128 sg = sg_chain_ptr(sg);
132 static inline vm_paddr_t
133 sg_phys(struct scatterlist *sg)
135 return (VM_PAGE_TO_PHYS(sg_page(sg)) + sg->offset);
139 sg_chain(struct scatterlist *prv, unsigned int prv_nents,
140 struct scatterlist *sgl)
142 struct scatterlist *sg = &prv[prv_nents - 1];
146 sg->page_link = ((unsigned long)sgl |
147 SG_PAGE_LINK_CHAIN) & ~SG_PAGE_LINK_LAST;
151 sg_mark_end(struct scatterlist *sg)
153 sg->page_link |= SG_PAGE_LINK_LAST;
154 sg->page_link &= ~SG_PAGE_LINK_CHAIN;
158 sg_init_table(struct scatterlist *sg, unsigned int nents)
160 bzero(sg, sizeof(*sg) * nents);
161 sg_mark_end(&sg[nents - 1]);
164 static struct scatterlist *
165 sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
167 if (nents == SG_MAX_SINGLE_ALLOC) {
168 return ((void *)__get_free_page(gfp_mask));
170 return (kmalloc(nents * sizeof(struct scatterlist), gfp_mask));
174 sg_kfree(struct scatterlist *sg, unsigned int nents)
176 if (nents == SG_MAX_SINGLE_ALLOC) {
177 free_page((unsigned long)sg);
183 __sg_free_table(struct sg_table *table, unsigned int max_ents,
184 bool skip_first_chunk, sg_free_fn * free_fn)
186 struct scatterlist *sgl, *next;
188 if (unlikely(!table->sgl))
192 while (table->orig_nents) {
193 unsigned int alloc_size = table->orig_nents;
194 unsigned int sg_size;
196 if (alloc_size > max_ents) {
197 next = sg_chain_ptr(&sgl[max_ents - 1]);
198 alloc_size = max_ents;
199 sg_size = alloc_size - 1;
201 sg_size = alloc_size;
205 table->orig_nents -= sg_size;
206 if (skip_first_chunk)
207 skip_first_chunk = 0;
209 free_fn(sgl, alloc_size);
217 sg_free_table(struct sg_table *table)
219 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree);
223 __sg_alloc_table(struct sg_table *table, unsigned int nents,
224 unsigned int max_ents, struct scatterlist *first_chunk,
225 gfp_t gfp_mask, sg_alloc_fn *alloc_fn)
227 struct scatterlist *sg, *prv;
230 memset(table, 0, sizeof(*table));
237 unsigned int sg_size;
238 unsigned int alloc_size = left;
240 if (alloc_size > max_ents) {
241 alloc_size = max_ents;
242 sg_size = alloc_size - 1;
244 sg_size = alloc_size;
252 sg = alloc_fn(alloc_size, gfp_mask);
256 table->nents = ++table->orig_nents;
260 sg_init_table(sg, alloc_size);
261 table->nents = table->orig_nents += sg_size;
264 sg_chain(prv, max_ents, sg);
269 sg_mark_end(&sg[sg_size - 1]);
278 sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
282 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
283 NULL, gfp_mask, sg_kmalloc);
285 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree);
291 __sg_alloc_table_from_pages(struct sg_table *sgt,
292 struct page **pages, unsigned int count,
293 unsigned long off, unsigned long size,
294 unsigned int max_segment, gfp_t gfp_mask)
296 unsigned int i, segs, cur, len;
298 struct scatterlist *s;
300 if (__predict_false(!max_segment || offset_in_page(max_segment)))
304 for (segs = i = 1; i < count; ++i) {
306 if (len >= max_segment ||
307 page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1) {
312 if (__predict_false((rc = sg_alloc_table(sgt, segs, gfp_mask))))
316 for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
317 unsigned long seg_size;
321 for (j = cur + 1; j < count; ++j) {
323 if (len >= max_segment || page_to_pfn(pages[j]) !=
324 page_to_pfn(pages[j - 1]) + 1)
328 seg_size = ((j - cur) << PAGE_SHIFT) - off;
329 sg_set_page(s, pages[cur], min(size, seg_size), off);
338 sg_alloc_table_from_pages(struct sg_table *sgt,
339 struct page **pages, unsigned int count,
340 unsigned long off, unsigned long size,
344 return (__sg_alloc_table_from_pages(sgt, pages, count, off, size,
345 SCATTERLIST_MAX_SEGMENT, gfp_mask));
349 sg_nents(struct scatterlist *sg)
353 for (nents = 0; sg; sg = sg_next(sg))
359 __sg_page_iter_start(struct sg_page_iter *piter,
360 struct scatterlist *sglist, unsigned int nents,
361 unsigned long pgoffset)
363 piter->internal.pg_advance = 0;
364 piter->internal.nents = nents;
367 piter->sg_pgoffset = pgoffset;
371 _sg_iter_next(struct sg_page_iter *iter)
373 struct scatterlist *sg;
374 unsigned int pgcount;
377 pgcount = (sg->offset + sg->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
380 while (iter->sg_pgoffset >= pgcount) {
381 iter->sg_pgoffset -= pgcount;
384 if (sg == NULL || iter->maxents == 0)
386 pgcount = (sg->offset + sg->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
392 sg_page_count(struct scatterlist *sg)
394 return (PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT);
398 __sg_page_iter_next(struct sg_page_iter *piter)
400 if (piter->internal.nents == 0)
402 if (piter->sg == NULL)
405 piter->sg_pgoffset += piter->internal.pg_advance;
406 piter->internal.pg_advance = 1;
408 while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
409 piter->sg_pgoffset -= sg_page_count(piter->sg);
410 piter->sg = sg_next(piter->sg);
411 if (--piter->internal.nents == 0)
413 if (piter->sg == NULL)
420 _sg_iter_init(struct scatterlist *sgl, struct sg_page_iter *iter,
421 unsigned int nents, unsigned long pgoffset)
425 iter->sg_pgoffset = pgoffset - 1;
426 iter->maxents = nents;
430 iter->sg_pgoffset = 0;
435 static inline dma_addr_t
436 sg_page_iter_dma_address(struct sg_page_iter *spi)
438 return (spi->sg->address + (spi->sg_pgoffset << PAGE_SHIFT));
441 static inline struct page *
442 sg_page_iter_page(struct sg_page_iter *piter)
444 return (nth_page(sg_page(piter->sg), piter->sg_pgoffset));
448 #endif /* _LINUX_SCATTERLIST_H_ */