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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef _LINUX_SCATTERLIST_H
2#define _LINUX_SCATTERLIST_H
3
Paul Gortmaker187f1882011-11-23 20:12:59 -05004#include <linux/string.h>
5#include <linux/bug.h>
6#include <linux/mm.h>
7
Hugh Dickins85cdffc2007-10-25 09:55:05 +02008#include <asm/types.h>
Herbert Xud32311f2005-09-17 14:41:40 +10009#include <asm/scatterlist.h>
Jens Axboe18dabf42007-10-22 19:57:20 +020010#include <asm/io.h>
11
Jens Axboe0db92992007-11-30 09:16:50 +010012struct sg_table {
13 struct scatterlist *sgl; /* the list */
14 unsigned int nents; /* number of mapped entries */
15 unsigned int orig_nents; /* original size of list */
16};
17
Jens Axboe18dabf42007-10-22 19:57:20 +020018/*
19 * Notes on SG table design.
20 *
21 * Architectures must provide an unsigned long page_link field in the
22 * scatterlist struct. We use that to place the page pointer AND encode
23 * information about the sg table as well. The two lower bits are reserved
24 * for this information.
25 *
26 * If bit 0 is set, then the page_link contains a pointer to the next sg
27 * table list. Otherwise the next entry is at sg + 1.
28 *
29 * If bit 1 is set, then this sg entry is the last element in a list.
30 *
31 * See sg_next().
32 *
33 */
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
Jens Axboed6ec0842007-10-22 20:01:06 +020035#define SG_MAGIC 0x87654321
36
Tejun Heo645a8d92007-11-27 09:30:39 +010037/*
38 * We overload the LSB of the page pointer to indicate whether it's
39 * a valid sg entry, or whether it points to the start of a new scatterlist.
40 * Those low bits are there for everyone! (thanks mason :-)
41 */
42#define sg_is_chain(sg) ((sg)->page_link & 0x01)
43#define sg_is_last(sg) ((sg)->page_link & 0x02)
44#define sg_chain_ptr(sg) \
45 ((struct scatterlist *) ((sg)->page_link & ~0x03))
46
Jens Axboe82f66fb2007-10-22 17:07:37 +020047/**
Jens Axboe642f1492007-10-24 11:20:47 +020048 * sg_assign_page - Assign a given page to an SG entry
49 * @sg: SG entry
50 * @page: The page
Jens Axboe82f66fb2007-10-22 17:07:37 +020051 *
52 * Description:
Jens Axboe642f1492007-10-24 11:20:47 +020053 * Assign page to sg entry. Also see sg_set_page(), the most commonly used
54 * variant.
Jens Axboe82f66fb2007-10-22 17:07:37 +020055 *
56 **/
Jens Axboe642f1492007-10-24 11:20:47 +020057static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
Jens Axboe82f66fb2007-10-22 17:07:37 +020058{
Jens Axboe18dabf42007-10-22 19:57:20 +020059 unsigned long page_link = sg->page_link & 0x3;
60
Jens Axboede261032007-10-23 20:35:58 +020061 /*
62 * In order for the low bit stealing approach to work, pages
63 * must be aligned at a 32-bit boundary as a minimum.
64 */
65 BUG_ON((unsigned long) page & 0x03);
Jens Axboed6ec0842007-10-22 20:01:06 +020066#ifdef CONFIG_DEBUG_SG
67 BUG_ON(sg->sg_magic != SG_MAGIC);
Tejun Heo645a8d92007-11-27 09:30:39 +010068 BUG_ON(sg_is_chain(sg));
Jens Axboed6ec0842007-10-22 20:01:06 +020069#endif
Jens Axboe18dabf42007-10-22 19:57:20 +020070 sg->page_link = page_link | (unsigned long) page;
Jens Axboe82f66fb2007-10-22 17:07:37 +020071}
72
Jens Axboe642f1492007-10-24 11:20:47 +020073/**
74 * sg_set_page - Set sg entry to point at given page
75 * @sg: SG entry
76 * @page: The page
77 * @len: Length of data
78 * @offset: Offset into page
79 *
80 * Description:
81 * Use this function to set an sg entry pointing at a page, never assign
82 * the page directly. We encode sg table information in the lower bits
83 * of the page pointer. See sg_page() for looking up the page belonging
84 * to an sg entry.
85 *
86 **/
87static inline void sg_set_page(struct scatterlist *sg, struct page *page,
88 unsigned int len, unsigned int offset)
89{
90 sg_assign_page(sg, page);
91 sg->offset = offset;
92 sg->length = len;
93}
94
Tejun Heo645a8d92007-11-27 09:30:39 +010095static inline struct page *sg_page(struct scatterlist *sg)
96{
97#ifdef CONFIG_DEBUG_SG
98 BUG_ON(sg->sg_magic != SG_MAGIC);
99 BUG_ON(sg_is_chain(sg));
100#endif
101 return (struct page *)((sg)->page_link & ~0x3);
102}
Jens Axboe82f66fb2007-10-22 17:07:37 +0200103
Jens Axboe18dabf42007-10-22 19:57:20 +0200104/**
105 * sg_set_buf - Set sg entry to point at given data
106 * @sg: SG entry
107 * @buf: Data
108 * @buflen: Data length
109 *
110 **/
Herbert Xu03fd9ce2006-08-14 23:11:53 +1000111static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
Herbert Xud32311f2005-09-17 14:41:40 +1000112 unsigned int buflen)
113{
Rusty Russellac4e97a2013-05-30 09:19:35 +0200114#ifdef CONFIG_DEBUG_SG
115 BUG_ON(!virt_addr_valid(buf));
116#endif
Jens Axboe642f1492007-10-24 11:20:47 +0200117 sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118}
119
Jens Axboe96b418c2007-05-09 09:02:57 +0200120/*
121 * Loop over each sg element, following the pointer to a new list if necessary
122 */
123#define for_each_sg(sglist, sg, nr, __i) \
124 for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
125
Jens Axboe70eb8042007-07-16 21:17:16 +0200126/**
Jens Axboe70eb8042007-07-16 21:17:16 +0200127 * sg_chain - Chain two sglists together
128 * @prv: First scatterlist
129 * @prv_nents: Number of entries in prv
130 * @sgl: Second scatterlist
131 *
Jens Axboe18dabf42007-10-22 19:57:20 +0200132 * Description:
133 * Links @prv@ and @sgl@ together, to form a longer scatterlist.
Jens Axboe70eb8042007-07-16 21:17:16 +0200134 *
Jens Axboe18dabf42007-10-22 19:57:20 +0200135 **/
Jens Axboe70eb8042007-07-16 21:17:16 +0200136static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
137 struct scatterlist *sgl)
138{
Laura Abbott308c09f2014-08-08 14:23:25 -0700139#ifndef CONFIG_ARCH_HAS_SG_CHAIN
Jens Axboe70eb8042007-07-16 21:17:16 +0200140 BUG();
141#endif
Tejun Heo645a8d92007-11-27 09:30:39 +0100142
143 /*
144 * offset and length are unused for chain entry. Clear them.
145 */
Rusty Russellb801a1e2008-01-11 10:12:55 +0100146 prv[prv_nents - 1].offset = 0;
147 prv[prv_nents - 1].length = 0;
Tejun Heo645a8d92007-11-27 09:30:39 +0100148
Jens Axboe73fd5462007-10-26 09:32:16 +0200149 /*
150 * Set lowest bit to indicate a link pointer, and make sure to clear
151 * the termination bit if it happens to be set.
152 */
153 prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02;
Jens Axboe70eb8042007-07-16 21:17:16 +0200154}
155
Jens Axboe82f66fb2007-10-22 17:07:37 +0200156/**
157 * sg_mark_end - Mark the end of the scatterlist
Jens Axboec46f2332007-10-31 12:06:37 +0100158 * @sg: SG entryScatterlist
Jens Axboe82f66fb2007-10-22 17:07:37 +0200159 *
160 * Description:
Jens Axboec46f2332007-10-31 12:06:37 +0100161 * Marks the passed in sg entry as the termination point for the sg
162 * table. A call to sg_next() on this entry will return NULL.
Jens Axboe82f66fb2007-10-22 17:07:37 +0200163 *
164 **/
Jens Axboec46f2332007-10-31 12:06:37 +0100165static inline void sg_mark_end(struct scatterlist *sg)
Jens Axboe82f66fb2007-10-22 17:07:37 +0200166{
Jens Axboec46f2332007-10-31 12:06:37 +0100167#ifdef CONFIG_DEBUG_SG
168 BUG_ON(sg->sg_magic != SG_MAGIC);
169#endif
170 /*
171 * Set termination bit, clear potential chain bit
172 */
Jens Axboe18dabf42007-10-22 19:57:20 +0200173 sg->page_link |= 0x02;
Jens Axboec46f2332007-10-31 12:06:37 +0100174 sg->page_link &= ~0x01;
Jens Axboe82f66fb2007-10-22 17:07:37 +0200175}
176
Jens Axboe82f66fb2007-10-22 17:07:37 +0200177/**
Paolo Bonzinic8164d82013-03-20 15:37:08 +1030178 * sg_unmark_end - Undo setting the end of the scatterlist
179 * @sg: SG entryScatterlist
180 *
181 * Description:
182 * Removes the termination marker from the given entry of the scatterlist.
183 *
184 **/
185static inline void sg_unmark_end(struct scatterlist *sg)
186{
187#ifdef CONFIG_DEBUG_SG
188 BUG_ON(sg->sg_magic != SG_MAGIC);
189#endif
190 sg->page_link &= ~0x02;
191}
192
193/**
Jens Axboe82f66fb2007-10-22 17:07:37 +0200194 * sg_phys - Return physical address of an sg entry
195 * @sg: SG entry
196 *
197 * Description:
198 * This calls page_to_phys() on the page in this sg entry, and adds the
199 * sg offset. The caller must know that it is legal to call page_to_phys()
200 * on the sg page.
201 *
202 **/
Hugh Dickins85cdffc2007-10-25 09:55:05 +0200203static inline dma_addr_t sg_phys(struct scatterlist *sg)
Jens Axboe82f66fb2007-10-22 17:07:37 +0200204{
205 return page_to_phys(sg_page(sg)) + sg->offset;
206}
207
208/**
209 * sg_virt - Return virtual address of an sg entry
Jens Axboe18dabf42007-10-22 19:57:20 +0200210 * @sg: SG entry
Jens Axboe82f66fb2007-10-22 17:07:37 +0200211 *
212 * Description:
213 * This calls page_address() on the page in this sg entry, and adds the
214 * sg offset. The caller must know that the sg page has a valid virtual
215 * mapping.
216 *
217 **/
218static inline void *sg_virt(struct scatterlist *sg)
219{
220 return page_address(sg_page(sg)) + sg->offset;
221}
222
Maxim Levitsky2e484612012-09-27 12:45:28 +0200223int sg_nents(struct scatterlist *sg);
Jens Axboe0db92992007-11-30 09:16:50 +0100224struct scatterlist *sg_next(struct scatterlist *);
225struct scatterlist *sg_last(struct scatterlist *s, unsigned int);
226void sg_init_table(struct scatterlist *, unsigned int);
227void sg_init_one(struct scatterlist *, const void *, unsigned int);
228
229typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t);
230typedef void (sg_free_fn)(struct scatterlist *, unsigned int);
231
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200232void __sg_free_table(struct sg_table *, unsigned int, bool, sg_free_fn *);
Jens Axboe0db92992007-11-30 09:16:50 +0100233void sg_free_table(struct sg_table *);
Christoph Hellwigc53c6d62014-04-15 14:38:31 +0200234int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
235 struct scatterlist *, gfp_t, sg_alloc_fn *);
Jens Axboe0db92992007-11-30 09:16:50 +0100236int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
Tomasz Stanislawskiefc42bc2012-06-18 09:25:01 +0200237int sg_alloc_table_from_pages(struct sg_table *sgt,
238 struct page **pages, unsigned int n_pages,
239 unsigned long offset, unsigned long size,
240 gfp_t gfp_mask);
Jens Axboe0db92992007-11-30 09:16:50 +0100241
FUJITA Tomonorib1adaf62008-03-18 00:15:03 +0900242size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
243 void *buf, size_t buflen);
244size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
245 void *buf, size_t buflen);
246
Akinobu Mitadf642ce2013-07-08 16:01:54 -0700247size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
248 void *buf, size_t buflen, off_t skip);
249size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
250 void *buf, size_t buflen, off_t skip);
251
Jens Axboe0db92992007-11-30 09:16:50 +0100252/*
253 * Maximum number of entries that will be allocated in one piece, if
254 * a list larger than this is required then chaining will be utilized.
255 */
256#define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
257
Imre Deaka321e912013-02-27 17:02:56 -0800258/*
259 * sg page iterator
260 *
261 * Iterates over sg entries page-by-page. On each successful iteration,
Imre Deak2db76d72013-03-26 15:14:18 +0200262 * you can call sg_page_iter_page(@piter) and sg_page_iter_dma_address(@piter)
263 * to get the current page and its dma address. @piter->sg will point to the
264 * sg holding this page and @piter->sg_pgoffset to the page's page offset
265 * within the sg. The iteration will stop either when a maximum number of sg
266 * entries was reached or a terminating sg (sg_last(sg) == true) was reached.
Imre Deaka321e912013-02-27 17:02:56 -0800267 */
268struct sg_page_iter {
Imre Deaka321e912013-02-27 17:02:56 -0800269 struct scatterlist *sg; /* sg holding the page */
270 unsigned int sg_pgoffset; /* page offset within the sg */
271
272 /* these are internal states, keep away */
273 unsigned int __nents; /* remaining sg entries */
274 int __pg_advance; /* nr pages to advance at the
275 * next step */
276};
277
278bool __sg_page_iter_next(struct sg_page_iter *piter);
279void __sg_page_iter_start(struct sg_page_iter *piter,
280 struct scatterlist *sglist, unsigned int nents,
281 unsigned long pgoffset);
Imre Deak2db76d72013-03-26 15:14:18 +0200282/**
283 * sg_page_iter_page - get the current page held by the page iterator
284 * @piter: page iterator holding the page
285 */
286static inline struct page *sg_page_iter_page(struct sg_page_iter *piter)
287{
288 return nth_page(sg_page(piter->sg), piter->sg_pgoffset);
289}
290
291/**
292 * sg_page_iter_dma_address - get the dma address of the current page held by
293 * the page iterator.
294 * @piter: page iterator holding the page
295 */
296static inline dma_addr_t sg_page_iter_dma_address(struct sg_page_iter *piter)
297{
298 return sg_dma_address(piter->sg) + (piter->sg_pgoffset << PAGE_SHIFT);
299}
Imre Deaka321e912013-02-27 17:02:56 -0800300
301/**
302 * for_each_sg_page - iterate over the pages of the given sg list
303 * @sglist: sglist to iterate over
304 * @piter: page iterator to hold current page, sg, sg_pgoffset
305 * @nents: maximum number of sg entries to iterate over
306 * @pgoffset: starting page offset
307 */
308#define for_each_sg_page(sglist, piter, nents, pgoffset) \
309 for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
310 __sg_page_iter_next(piter);)
Tejun Heo137d3ed2008-07-19 23:03:35 +0900311
312/*
313 * Mapping sg iterator
314 *
315 * Iterates over sg entries mapping page-by-page. On each successful
316 * iteration, @miter->page points to the mapped page and
317 * @miter->length bytes of data can be accessed at @miter->addr. As
318 * long as an interation is enclosed between start and stop, the user
319 * is free to choose control structure and when to stop.
320 *
321 * @miter->consumed is set to @miter->length on each iteration. It
322 * can be adjusted if the user can't consume all the bytes in one go.
323 * Also, a stopped iteration can be resumed by calling next on it.
324 * This is useful when iteration needs to release all resources and
325 * continue later (e.g. at the next interrupt).
326 */
327
328#define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */
Sebastian Andrzej Siewior6de7e3562009-06-18 10:19:12 +0200329#define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */
330#define SG_MITER_FROM_SG (1 << 2) /* nop */
Tejun Heo137d3ed2008-07-19 23:03:35 +0900331
332struct sg_mapping_iter {
333 /* the following three fields can be accessed directly */
334 struct page *page; /* currently mapped page */
335 void *addr; /* pointer to the mapped area */
336 size_t length; /* length of the mapped area */
337 size_t consumed; /* number of consumed bytes */
Imre Deak4225fc82013-02-27 17:02:57 -0800338 struct sg_page_iter piter; /* page iterator */
Tejun Heo137d3ed2008-07-19 23:03:35 +0900339
340 /* these are internal states, keep away */
Imre Deak4225fc82013-02-27 17:02:57 -0800341 unsigned int __offset; /* offset within page */
342 unsigned int __remaining; /* remaining bytes on page */
Tejun Heo137d3ed2008-07-19 23:03:35 +0900343 unsigned int __flags;
344};
345
346void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
347 unsigned int nents, unsigned int flags);
Ming Lei0d6077f2013-11-26 12:43:37 +0800348bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset);
Tejun Heo137d3ed2008-07-19 23:03:35 +0900349bool sg_miter_next(struct sg_mapping_iter *miter);
350void sg_miter_stop(struct sg_mapping_iter *miter);
351
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352#endif /* _LINUX_SCATTERLIST_H */