1 #ifndef _LINUX_SCATTERLIST_H
2 #define _LINUX_SCATTERLIST_H
4 #include <linux/string.h>
5 #include <linux/types.h>
11 #ifdef CONFIG_DEBUG_SG
12 unsigned long sg_magic
;
14 unsigned long page_link
;
17 dma_addr_t dma_address
;
18 #ifdef CONFIG_NEED_SG_DMA_LENGTH
19 unsigned int dma_length
;
24 * These macros should be used after a dma_map_sg call has been done
25 * to get bus addresses of each of the SG entries and their lengths.
26 * You should only work with the number of sg entries dma_map_sg
27 * returns, or alternatively stop on the first sg_dma_len(sg) which
30 #define sg_dma_address(sg) ((sg)->dma_address)
32 #ifdef CONFIG_NEED_SG_DMA_LENGTH
33 #define sg_dma_len(sg) ((sg)->dma_length)
35 #define sg_dma_len(sg) ((sg)->length)
39 struct scatterlist
*sgl
; /* the list */
40 unsigned int nents
; /* number of mapped entries */
41 unsigned int orig_nents
; /* original size of list */
45 * Notes on SG table design.
47 * We use the unsigned long page_link field in the scatterlist struct to place
48 * the page pointer AND encode information about the sg table as well. The two
49 * lower bits are reserved for this information.
51 * If bit 0 is set, then the page_link contains a pointer to the next sg
52 * table list. Otherwise the next entry is at sg + 1.
54 * If bit 1 is set, then this sg entry is the last element in a list.
60 #define SG_MAGIC 0x87654321
63 * We overload the LSB of the page pointer to indicate whether it's
64 * a valid sg entry, or whether it points to the start of a new scatterlist.
65 * Those low bits are there for everyone! (thanks mason :-)
67 #define sg_is_chain(sg) ((sg)->page_link & 0x01)
68 #define sg_is_last(sg) ((sg)->page_link & 0x02)
69 #define sg_chain_ptr(sg) \
70 ((struct scatterlist *) ((sg)->page_link & ~0x03))
73 * sg_assign_page - Assign a given page to an SG entry
78 * Assign page to sg entry. Also see sg_set_page(), the most commonly used
82 static inline void sg_assign_page(struct scatterlist
*sg
, struct page
*page
)
84 unsigned long page_link
= sg
->page_link
& 0x3;
87 * In order for the low bit stealing approach to work, pages
88 * must be aligned at a 32-bit boundary as a minimum.
90 BUG_ON((unsigned long) page
& 0x03);
91 #ifdef CONFIG_DEBUG_SG
92 BUG_ON(sg
->sg_magic
!= SG_MAGIC
);
93 BUG_ON(sg_is_chain(sg
));
95 sg
->page_link
= page_link
| (unsigned long) page
;
99 * sg_set_page - Set sg entry to point at given page
102 * @len: Length of data
103 * @offset: Offset into page
106 * Use this function to set an sg entry pointing at a page, never assign
107 * the page directly. We encode sg table information in the lower bits
108 * of the page pointer. See sg_page() for looking up the page belonging
112 static inline void sg_set_page(struct scatterlist
*sg
, struct page
*page
,
113 unsigned int len
, unsigned int offset
)
115 sg_assign_page(sg
, page
);
120 static inline struct page
*sg_page(struct scatterlist
*sg
)
122 #ifdef CONFIG_DEBUG_SG
123 BUG_ON(sg
->sg_magic
!= SG_MAGIC
);
124 BUG_ON(sg_is_chain(sg
));
126 return (struct page
*)((sg
)->page_link
& ~0x3);
130 * sg_set_buf - Set sg entry to point at given data
133 * @buflen: Data length
136 static inline void sg_set_buf(struct scatterlist
*sg
, const void *buf
,
139 #ifdef CONFIG_DEBUG_SG
140 BUG_ON(!virt_addr_valid(buf
));
142 sg_set_page(sg
, virt_to_page(buf
), buflen
, offset_in_page(buf
));
146 * Loop over each sg element, following the pointer to a new list if necessary
148 #define for_each_sg(sglist, sg, nr, __i) \
149 for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
152 * sg_chain - Chain two sglists together
153 * @prv: First scatterlist
154 * @prv_nents: Number of entries in prv
155 * @sgl: Second scatterlist
158 * Links @prv@ and @sgl@ together, to form a longer scatterlist.
161 static inline void sg_chain(struct scatterlist
*prv
, unsigned int prv_nents
,
162 struct scatterlist
*sgl
)
165 * offset and length are unused for chain entry. Clear them.
167 prv
[prv_nents
- 1].offset
= 0;
168 prv
[prv_nents
- 1].length
= 0;
171 * Set lowest bit to indicate a link pointer, and make sure to clear
172 * the termination bit if it happens to be set.
174 prv
[prv_nents
- 1].page_link
= ((unsigned long) sgl
| 0x01) & ~0x02;
178 * sg_mark_end - Mark the end of the scatterlist
179 * @sg: SG entryScatterlist
182 * Marks the passed in sg entry as the termination point for the sg
183 * table. A call to sg_next() on this entry will return NULL.
186 static inline void sg_mark_end(struct scatterlist
*sg
)
188 #ifdef CONFIG_DEBUG_SG
189 BUG_ON(sg
->sg_magic
!= SG_MAGIC
);
192 * Set termination bit, clear potential chain bit
194 sg
->page_link
|= 0x02;
195 sg
->page_link
&= ~0x01;
199 * sg_unmark_end - Undo setting the end of the scatterlist
200 * @sg: SG entryScatterlist
203 * Removes the termination marker from the given entry of the scatterlist.
206 static inline void sg_unmark_end(struct scatterlist
*sg
)
208 #ifdef CONFIG_DEBUG_SG
209 BUG_ON(sg
->sg_magic
!= SG_MAGIC
);
211 sg
->page_link
&= ~0x02;
215 * sg_phys - Return physical address of an sg entry
219 * This calls page_to_phys() on the page in this sg entry, and adds the
220 * sg offset. The caller must know that it is legal to call page_to_phys()
224 static inline dma_addr_t
sg_phys(struct scatterlist
*sg
)
226 return page_to_phys(sg_page(sg
)) + sg
->offset
;
230 * sg_virt - Return virtual address of an sg entry
234 * This calls page_address() on the page in this sg entry, and adds the
235 * sg offset. The caller must know that the sg page has a valid virtual
239 static inline void *sg_virt(struct scatterlist
*sg
)
241 return page_address(sg_page(sg
)) + sg
->offset
;
244 int sg_nents(struct scatterlist
*sg
);
245 int sg_nents_for_len(struct scatterlist
*sg
, u64 len
);
246 struct scatterlist
*sg_next(struct scatterlist
*);
247 struct scatterlist
*sg_last(struct scatterlist
*s
, unsigned int);
248 void sg_init_table(struct scatterlist
*, unsigned int);
249 void sg_init_one(struct scatterlist
*, const void *, unsigned int);
250 int sg_split(struct scatterlist
*in
, const int in_mapped_nents
,
251 const off_t skip
, const int nb_splits
,
252 const size_t *split_sizes
,
253 struct scatterlist
**out
, int *out_mapped_nents
,
256 typedef struct scatterlist
*(sg_alloc_fn
)(unsigned int, gfp_t
);
257 typedef void (sg_free_fn
)(struct scatterlist
*, unsigned int);
259 void __sg_free_table(struct sg_table
*, unsigned int, bool, sg_free_fn
*);
260 void sg_free_table(struct sg_table
*);
261 int __sg_alloc_table(struct sg_table
*, unsigned int, unsigned int,
262 struct scatterlist
*, gfp_t
, sg_alloc_fn
*);
263 int sg_alloc_table(struct sg_table
*, unsigned int, gfp_t
);
264 int sg_alloc_table_from_pages(struct sg_table
*sgt
,
265 struct page
**pages
, unsigned int n_pages
,
266 unsigned long offset
, unsigned long size
,
269 size_t sg_copy_buffer(struct scatterlist
*sgl
, unsigned int nents
, void *buf
,
270 size_t buflen
, off_t skip
, bool to_buffer
);
272 size_t sg_copy_from_buffer(struct scatterlist
*sgl
, unsigned int nents
,
273 const void *buf
, size_t buflen
);
274 size_t sg_copy_to_buffer(struct scatterlist
*sgl
, unsigned int nents
,
275 void *buf
, size_t buflen
);
277 size_t sg_pcopy_from_buffer(struct scatterlist
*sgl
, unsigned int nents
,
278 const void *buf
, size_t buflen
, off_t skip
);
279 size_t sg_pcopy_to_buffer(struct scatterlist
*sgl
, unsigned int nents
,
280 void *buf
, size_t buflen
, off_t skip
);
283 * Maximum number of entries that will be allocated in one piece, if
284 * a list larger than this is required then chaining will be utilized.
286 #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
291 * Iterates over sg entries page-by-page. On each successful iteration,
292 * you can call sg_page_iter_page(@piter) and sg_page_iter_dma_address(@piter)
293 * to get the current page and its dma address. @piter->sg will point to the
294 * sg holding this page and @piter->sg_pgoffset to the page's page offset
295 * within the sg. The iteration will stop either when a maximum number of sg
296 * entries was reached or a terminating sg (sg_last(sg) == true) was reached.
298 struct sg_page_iter
{
299 struct scatterlist
*sg
; /* sg holding the page */
300 unsigned int sg_pgoffset
; /* page offset within the sg */
302 /* these are internal states, keep away */
303 unsigned int __nents
; /* remaining sg entries */
304 int __pg_advance
; /* nr pages to advance at the
308 bool __sg_page_iter_next(struct sg_page_iter
*piter
);
309 void __sg_page_iter_start(struct sg_page_iter
*piter
,
310 struct scatterlist
*sglist
, unsigned int nents
,
311 unsigned long pgoffset
);
313 * sg_page_iter_page - get the current page held by the page iterator
314 * @piter: page iterator holding the page
316 static inline struct page
*sg_page_iter_page(struct sg_page_iter
*piter
)
318 return nth_page(sg_page(piter
->sg
), piter
->sg_pgoffset
);
322 * sg_page_iter_dma_address - get the dma address of the current page held by
324 * @piter: page iterator holding the page
326 static inline dma_addr_t
sg_page_iter_dma_address(struct sg_page_iter
*piter
)
328 return sg_dma_address(piter
->sg
) + (piter
->sg_pgoffset
<< PAGE_SHIFT
);
332 * for_each_sg_page - iterate over the pages of the given sg list
333 * @sglist: sglist to iterate over
334 * @piter: page iterator to hold current page, sg, sg_pgoffset
335 * @nents: maximum number of sg entries to iterate over
336 * @pgoffset: starting page offset
338 #define for_each_sg_page(sglist, piter, nents, pgoffset) \
339 for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
340 __sg_page_iter_next(piter);)
343 * Mapping sg iterator
345 * Iterates over sg entries mapping page-by-page. On each successful
346 * iteration, @miter->page points to the mapped page and
347 * @miter->length bytes of data can be accessed at @miter->addr. As
348 * long as an interation is enclosed between start and stop, the user
349 * is free to choose control structure and when to stop.
351 * @miter->consumed is set to @miter->length on each iteration. It
352 * can be adjusted if the user can't consume all the bytes in one go.
353 * Also, a stopped iteration can be resumed by calling next on it.
354 * This is useful when iteration needs to release all resources and
355 * continue later (e.g. at the next interrupt).
358 #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */
359 #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */
360 #define SG_MITER_FROM_SG (1 << 2) /* nop */
362 struct sg_mapping_iter
{
363 /* the following three fields can be accessed directly */
364 struct page
*page
; /* currently mapped page */
365 void *addr
; /* pointer to the mapped area */
366 size_t length
; /* length of the mapped area */
367 size_t consumed
; /* number of consumed bytes */
368 struct sg_page_iter piter
; /* page iterator */
370 /* these are internal states, keep away */
371 unsigned int __offset
; /* offset within page */
372 unsigned int __remaining
; /* remaining bytes on page */
373 unsigned int __flags
;
376 void sg_miter_start(struct sg_mapping_iter
*miter
, struct scatterlist
*sgl
,
377 unsigned int nents
, unsigned int flags
);
378 bool sg_miter_skip(struct sg_mapping_iter
*miter
, off_t offset
);
379 bool sg_miter_next(struct sg_mapping_iter
*miter
);
380 void sg_miter_stop(struct sg_mapping_iter
*miter
);
382 #endif /* _LINUX_SCATTERLIST_H */
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