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 SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
69 #define SG_MAGIC 0x87654321UL
71 #define sg_is_chain(sg) ((sg)->page_link & SG_PAGE_LINK_CHAIN)
72 #define sg_is_last(sg) ((sg)->page_link & SG_PAGE_LINK_LAST)
73 #define sg_chain_ptr(sg) \
74 ((struct scatterlist *) ((sg)->page_link & ~SG_PAGE_LINK_MASK))
76 #define sg_dma_address(sg) (sg)->address
77 #define sg_dma_len(sg) (sg)->length
79 #define for_each_sg_page(sgl, iter, nents, pgoffset) \
80 for (_sg_iter_init(sgl, iter, nents, pgoffset); \
81 (iter)->sg; _sg_iter_next(iter))
83 #define for_each_sg(sglist, sg, sgmax, iter) \
84 for (iter = 0, sg = (sglist); iter < (sgmax); iter++, sg = sg_next(sg))
86 typedef struct scatterlist *(sg_alloc_fn) (unsigned int, gfp_t);
87 typedef void (sg_free_fn) (struct scatterlist *, unsigned int);
90 sg_assign_page(struct scatterlist *sg, struct page *page)
92 unsigned long page_link = sg->page_link & SG_PAGE_LINK_MASK;
94 sg->page_link = page_link | (unsigned long)page;
98 sg_set_page(struct scatterlist *sg, struct page *page, unsigned int len,
101 sg_assign_page(sg, page);
106 static inline struct page *
107 sg_page(struct scatterlist *sg)
109 return ((struct page *)((sg)->page_link & ~SG_PAGE_LINK_MASK));
113 sg_set_buf(struct scatterlist *sg, const void *buf, unsigned int buflen)
115 sg_set_page(sg, virt_to_page(buf), buflen,
116 ((uintptr_t)buf) & (PAGE_SIZE - 1));
119 static inline struct scatterlist *
120 sg_next(struct scatterlist *sg)
126 sg = sg_chain_ptr(sg);
130 static inline vm_paddr_t
131 sg_phys(struct scatterlist *sg)
133 return (VM_PAGE_TO_PHYS(sg_page(sg)) + sg->offset);
137 sg_chain(struct scatterlist *prv, unsigned int prv_nents,
138 struct scatterlist *sgl)
140 struct scatterlist *sg = &prv[prv_nents - 1];
144 sg->page_link = ((unsigned long)sgl |
145 SG_PAGE_LINK_CHAIN) & ~SG_PAGE_LINK_LAST;
149 sg_mark_end(struct scatterlist *sg)
151 sg->page_link |= SG_PAGE_LINK_LAST;
152 sg->page_link &= ~SG_PAGE_LINK_CHAIN;
156 sg_init_table(struct scatterlist *sg, unsigned int nents)
158 bzero(sg, sizeof(*sg) * nents);
159 sg_mark_end(&sg[nents - 1]);
162 static struct scatterlist *
163 sg_kmalloc(unsigned int nents, gfp_t gfp_mask)
165 if (nents == SG_MAX_SINGLE_ALLOC) {
166 return ((void *)__get_free_page(gfp_mask));
168 return (kmalloc(nents * sizeof(struct scatterlist), gfp_mask));
172 sg_kfree(struct scatterlist *sg, unsigned int nents)
174 if (nents == SG_MAX_SINGLE_ALLOC) {
175 free_page((unsigned long)sg);
181 __sg_free_table(struct sg_table *table, unsigned int max_ents,
182 bool skip_first_chunk, sg_free_fn * free_fn)
184 struct scatterlist *sgl, *next;
186 if (unlikely(!table->sgl))
190 while (table->orig_nents) {
191 unsigned int alloc_size = table->orig_nents;
192 unsigned int sg_size;
194 if (alloc_size > max_ents) {
195 next = sg_chain_ptr(&sgl[max_ents - 1]);
196 alloc_size = max_ents;
197 sg_size = alloc_size - 1;
199 sg_size = alloc_size;
203 table->orig_nents -= sg_size;
204 if (skip_first_chunk)
205 skip_first_chunk = 0;
207 free_fn(sgl, alloc_size);
215 sg_free_table(struct sg_table *table)
217 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree);
221 __sg_alloc_table(struct sg_table *table, unsigned int nents,
222 unsigned int max_ents, struct scatterlist *first_chunk,
223 gfp_t gfp_mask, sg_alloc_fn *alloc_fn)
225 struct scatterlist *sg, *prv;
228 memset(table, 0, sizeof(*table));
235 unsigned int sg_size;
236 unsigned int alloc_size = left;
238 if (alloc_size > max_ents) {
239 alloc_size = max_ents;
240 sg_size = alloc_size - 1;
242 sg_size = alloc_size;
250 sg = alloc_fn(alloc_size, gfp_mask);
254 table->nents = ++table->orig_nents;
258 sg_init_table(sg, alloc_size);
259 table->nents = table->orig_nents += sg_size;
262 sg_chain(prv, max_ents, sg);
267 sg_mark_end(&sg[sg_size - 1]);
276 sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask)
280 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC,
281 NULL, gfp_mask, sg_kmalloc);
283 __sg_free_table(table, SG_MAX_SINGLE_ALLOC, 0, sg_kfree);
289 sg_alloc_table_from_pages(struct sg_table *sgt,
290 struct page **pages, unsigned int count,
291 unsigned long off, unsigned long size,
294 unsigned int i, segs, cur;
296 struct scatterlist *s;
298 for (segs = i = 1; i < count; ++i) {
299 if (page_to_pfn(pages[i]) != page_to_pfn(pages[i - 1]) + 1)
302 if (__predict_false((rc = sg_alloc_table(sgt, segs, gfp_mask))))
306 for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
307 unsigned long seg_size;
310 for (j = cur + 1; j < count; ++j)
311 if (page_to_pfn(pages[j]) !=
312 page_to_pfn(pages[j - 1]) + 1)
315 seg_size = ((j - cur) << PAGE_SHIFT) - off;
316 sg_set_page(s, pages[cur], min(size, seg_size), off);
326 sg_nents(struct scatterlist *sg)
330 for (nents = 0; sg; sg = sg_next(sg))
336 __sg_page_iter_start(struct sg_page_iter *piter,
337 struct scatterlist *sglist, unsigned int nents,
338 unsigned long pgoffset)
340 piter->internal.pg_advance = 0;
341 piter->internal.nents = nents;
344 piter->sg_pgoffset = pgoffset;
348 _sg_iter_next(struct sg_page_iter *iter)
350 struct scatterlist *sg;
351 unsigned int pgcount;
354 pgcount = (sg->offset + sg->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
357 while (iter->sg_pgoffset >= pgcount) {
358 iter->sg_pgoffset -= pgcount;
361 if (sg == NULL || iter->maxents == 0)
363 pgcount = (sg->offset + sg->length + PAGE_SIZE - 1) >> PAGE_SHIFT;
369 sg_page_count(struct scatterlist *sg)
371 return (PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT);
375 __sg_page_iter_next(struct sg_page_iter *piter)
377 if (piter->internal.nents == 0)
379 if (piter->sg == NULL)
382 piter->sg_pgoffset += piter->internal.pg_advance;
383 piter->internal.pg_advance = 1;
385 while (piter->sg_pgoffset >= sg_page_count(piter->sg)) {
386 piter->sg_pgoffset -= sg_page_count(piter->sg);
387 piter->sg = sg_next(piter->sg);
388 if (--piter->internal.nents == 0)
390 if (piter->sg == NULL)
397 _sg_iter_init(struct scatterlist *sgl, struct sg_page_iter *iter,
398 unsigned int nents, unsigned long pgoffset)
402 iter->sg_pgoffset = pgoffset - 1;
403 iter->maxents = nents;
407 iter->sg_pgoffset = 0;
412 static inline dma_addr_t
413 sg_page_iter_dma_address(struct sg_page_iter *spi)
415 return (spi->sg->address + (spi->sg_pgoffset << PAGE_SHIFT));
418 static inline struct page *
419 sg_page_iter_page(struct sg_page_iter *piter)
421 return (nth_page(sg_page(piter->sg), piter->sg_pgoffset));
425 #endif /* _LINUX_SCATTERLIST_H_ */