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1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SCATTERLIST_H
3 #define _LINUX_SCATTERLIST_H
5 #include <linux/string.h>
6 #include <linux/types.h>
12 unsigned long page_link
;
15 dma_addr_t dma_address
;
16 #ifdef CONFIG_NEED_SG_DMA_LENGTH
17 unsigned int dma_length
;
22 * These macros should be used after a dma_map_sg call has been done
23 * to get bus addresses of each of the SG entries and their lengths.
24 * You should only work with the number of sg entries dma_map_sg
25 * returns, or alternatively stop on the first sg_dma_len(sg) which
28 #define sg_dma_address(sg) ((sg)->dma_address)
30 #ifdef CONFIG_NEED_SG_DMA_LENGTH
31 #define sg_dma_len(sg) ((sg)->dma_length)
33 #define sg_dma_len(sg) ((sg)->length)
37 struct scatterlist
*sgl
; /* the list */
38 unsigned int nents
; /* number of mapped entries */
39 unsigned int orig_nents
; /* original size of list */
42 struct sg_append_table
{
43 struct sg_table sgt
; /* The scatter list table */
44 struct scatterlist
*prv
; /* last populated sge in the table */
45 unsigned int total_nents
; /* Total entries in the table */
49 * Notes on SG table design.
51 * We use the unsigned long page_link field in the scatterlist struct to place
52 * the page pointer AND encode information about the sg table as well. The two
53 * lower bits are reserved for this information.
55 * If bit 0 is set, then the page_link contains a pointer to the next sg
56 * table list. Otherwise the next entry is at sg + 1.
58 * If bit 1 is set, then this sg entry is the last element in a list.
64 #define SG_CHAIN 0x01UL
68 * We overload the LSB of the page pointer to indicate whether it's
69 * a valid sg entry, or whether it points to the start of a new scatterlist.
70 * Those low bits are there for everyone! (thanks mason :-)
72 #define sg_is_chain(sg) ((sg)->page_link & SG_CHAIN)
73 #define sg_is_last(sg) ((sg)->page_link & SG_END)
74 #define sg_chain_ptr(sg) \
75 ((struct scatterlist *) ((sg)->page_link & ~(SG_CHAIN | SG_END)))
78 * sg_assign_page - Assign a given page to an SG entry
83 * Assign page to sg entry. Also see sg_set_page(), the most commonly used
87 static inline void sg_assign_page(struct scatterlist
*sg
, struct page
*page
)
89 unsigned long page_link
= sg
->page_link
& (SG_CHAIN
| SG_END
);
92 * In order for the low bit stealing approach to work, pages
93 * must be aligned at a 32-bit boundary as a minimum.
95 BUG_ON((unsigned long) page
& (SG_CHAIN
| SG_END
));
96 #ifdef CONFIG_DEBUG_SG
97 BUG_ON(sg_is_chain(sg
));
99 sg
->page_link
= page_link
| (unsigned long) page
;
103 * sg_set_page - Set sg entry to point at given page
106 * @len: Length of data
107 * @offset: Offset into page
110 * Use this function to set an sg entry pointing at a page, never assign
111 * the page directly. We encode sg table information in the lower bits
112 * of the page pointer. See sg_page() for looking up the page belonging
116 static inline void sg_set_page(struct scatterlist
*sg
, struct page
*page
,
117 unsigned int len
, unsigned int offset
)
119 sg_assign_page(sg
, page
);
124 static inline struct page
*sg_page(struct scatterlist
*sg
)
126 #ifdef CONFIG_DEBUG_SG
127 BUG_ON(sg_is_chain(sg
));
129 return (struct page
*)((sg
)->page_link
& ~(SG_CHAIN
| SG_END
));
133 * sg_set_buf - Set sg entry to point at given data
136 * @buflen: Data length
139 static inline void sg_set_buf(struct scatterlist
*sg
, const void *buf
,
142 #ifdef CONFIG_DEBUG_SG
143 BUG_ON(!virt_addr_valid(buf
));
145 sg_set_page(sg
, virt_to_page(buf
), buflen
, offset_in_page(buf
));
149 * Loop over each sg element, following the pointer to a new list if necessary
151 #define for_each_sg(sglist, sg, nr, __i) \
152 for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
155 * Loop over each sg element in the given sg_table object.
157 #define for_each_sgtable_sg(sgt, sg, i) \
158 for_each_sg((sgt)->sgl, sg, (sgt)->orig_nents, i)
161 * Loop over each sg element in the given *DMA mapped* sg_table object.
162 * Please use sg_dma_address(sg) and sg_dma_len(sg) to extract DMA addresses
163 * of the each element.
165 #define for_each_sgtable_dma_sg(sgt, sg, i) \
166 for_each_sg((sgt)->sgl, sg, (sgt)->nents, i)
168 static inline void __sg_chain(struct scatterlist
*chain_sg
,
169 struct scatterlist
*sgl
)
172 * offset and length are unused for chain entry. Clear them.
174 chain_sg
->offset
= 0;
175 chain_sg
->length
= 0;
178 * Set lowest bit to indicate a link pointer, and make sure to clear
179 * the termination bit if it happens to be set.
181 chain_sg
->page_link
= ((unsigned long) sgl
| SG_CHAIN
) & ~SG_END
;
185 * sg_chain - Chain two sglists together
186 * @prv: First scatterlist
187 * @prv_nents: Number of entries in prv
188 * @sgl: Second scatterlist
191 * Links @prv@ and @sgl@ together, to form a longer scatterlist.
194 static inline void sg_chain(struct scatterlist
*prv
, unsigned int prv_nents
,
195 struct scatterlist
*sgl
)
197 __sg_chain(&prv
[prv_nents
- 1], sgl
);
201 * sg_mark_end - Mark the end of the scatterlist
202 * @sg: SG entryScatterlist
205 * Marks the passed in sg entry as the termination point for the sg
206 * table. A call to sg_next() on this entry will return NULL.
209 static inline void sg_mark_end(struct scatterlist
*sg
)
212 * Set termination bit, clear potential chain bit
214 sg
->page_link
|= SG_END
;
215 sg
->page_link
&= ~SG_CHAIN
;
219 * sg_unmark_end - Undo setting the end of the scatterlist
220 * @sg: SG entryScatterlist
223 * Removes the termination marker from the given entry of the scatterlist.
226 static inline void sg_unmark_end(struct scatterlist
*sg
)
228 sg
->page_link
&= ~SG_END
;
232 * sg_phys - Return physical address of an sg entry
236 * This calls page_to_phys() on the page in this sg entry, and adds the
237 * sg offset. The caller must know that it is legal to call page_to_phys()
241 static inline dma_addr_t
sg_phys(struct scatterlist
*sg
)
243 return page_to_phys(sg_page(sg
)) + sg
->offset
;
247 * sg_virt - Return virtual address of an sg entry
251 * This calls page_address() on the page in this sg entry, and adds the
252 * sg offset. The caller must know that the sg page has a valid virtual
256 static inline void *sg_virt(struct scatterlist
*sg
)
258 return page_address(sg_page(sg
)) + sg
->offset
;
262 * sg_init_marker - Initialize markers in sg table
264 * @nents: Number of entries in table
267 static inline void sg_init_marker(struct scatterlist
*sgl
,
270 sg_mark_end(&sgl
[nents
- 1]);
273 int sg_nents(struct scatterlist
*sg
);
274 int sg_nents_for_len(struct scatterlist
*sg
, u64 len
);
275 struct scatterlist
*sg_next(struct scatterlist
*);
276 struct scatterlist
*sg_last(struct scatterlist
*s
, unsigned int);
277 void sg_init_table(struct scatterlist
*, unsigned int);
278 void sg_init_one(struct scatterlist
*, const void *, unsigned int);
279 int sg_split(struct scatterlist
*in
, const int in_mapped_nents
,
280 const off_t skip
, const int nb_splits
,
281 const size_t *split_sizes
,
282 struct scatterlist
**out
, int *out_mapped_nents
,
285 typedef struct scatterlist
*(sg_alloc_fn
)(unsigned int, gfp_t
);
286 typedef void (sg_free_fn
)(struct scatterlist
*, unsigned int);
288 void __sg_free_table(struct sg_table
*, unsigned int, unsigned int,
289 sg_free_fn
*, unsigned int);
290 void sg_free_table(struct sg_table
*);
291 void sg_free_append_table(struct sg_append_table
*sgt
);
292 int __sg_alloc_table(struct sg_table
*, unsigned int, unsigned int,
293 struct scatterlist
*, unsigned int, gfp_t
, sg_alloc_fn
*);
294 int sg_alloc_table(struct sg_table
*, unsigned int, gfp_t
);
295 int sg_alloc_append_table_from_pages(struct sg_append_table
*sgt
,
296 struct page
**pages
, unsigned int n_pages
,
297 unsigned int offset
, unsigned long size
,
298 unsigned int max_segment
,
299 unsigned int left_pages
, gfp_t gfp_mask
);
300 int sg_alloc_table_from_pages_segment(struct sg_table
*sgt
, struct page
**pages
,
301 unsigned int n_pages
, unsigned int offset
,
303 unsigned int max_segment
, gfp_t gfp_mask
);
306 * sg_alloc_table_from_pages - Allocate and initialize an sg table from
308 * @sgt: The sg table header to use
309 * @pages: Pointer to an array of page pointers
310 * @n_pages: Number of pages in the pages array
311 * @offset: Offset from start of the first page to the start of a buffer
312 * @size: Number of valid bytes in the buffer (after offset)
313 * @gfp_mask: GFP allocation mask
316 * Allocate and initialize an sg table from a list of pages. Contiguous
317 * ranges of the pages are squashed into a single scatterlist node. A user
318 * may provide an offset at a start and a size of valid data in a buffer
319 * specified by the page array. The returned sg table is released by
323 * 0 on success, negative error on failure
325 static inline int sg_alloc_table_from_pages(struct sg_table
*sgt
,
327 unsigned int n_pages
,
329 unsigned long size
, gfp_t gfp_mask
)
331 return sg_alloc_table_from_pages_segment(sgt
, pages
, n_pages
, offset
,
332 size
, UINT_MAX
, gfp_mask
);
335 #ifdef CONFIG_SGL_ALLOC
336 struct scatterlist
*sgl_alloc_order(unsigned long long length
,
337 unsigned int order
, bool chainable
,
338 gfp_t gfp
, unsigned int *nent_p
);
339 struct scatterlist
*sgl_alloc(unsigned long long length
, gfp_t gfp
,
340 unsigned int *nent_p
);
341 void sgl_free_n_order(struct scatterlist
*sgl
, int nents
, int order
);
342 void sgl_free_order(struct scatterlist
*sgl
, int order
);
343 void sgl_free(struct scatterlist
*sgl
);
344 #endif /* CONFIG_SGL_ALLOC */
346 size_t sg_copy_buffer(struct scatterlist
*sgl
, unsigned int nents
, void *buf
,
347 size_t buflen
, off_t skip
, bool to_buffer
);
349 size_t sg_copy_from_buffer(struct scatterlist
*sgl
, unsigned int nents
,
350 const void *buf
, size_t buflen
);
351 size_t sg_copy_to_buffer(struct scatterlist
*sgl
, unsigned int nents
,
352 void *buf
, size_t buflen
);
354 size_t sg_pcopy_from_buffer(struct scatterlist
*sgl
, unsigned int nents
,
355 const void *buf
, size_t buflen
, off_t skip
);
356 size_t sg_pcopy_to_buffer(struct scatterlist
*sgl
, unsigned int nents
,
357 void *buf
, size_t buflen
, off_t skip
);
358 size_t sg_zero_buffer(struct scatterlist
*sgl
, unsigned int nents
,
359 size_t buflen
, off_t skip
);
362 * Maximum number of entries that will be allocated in one piece, if
363 * a list larger than this is required then chaining will be utilized.
365 #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
368 * The maximum number of SG segments that we will put inside a
369 * scatterlist (unless chaining is used). Should ideally fit inside a
370 * single page, to avoid a higher order allocation. We could define this
371 * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The
372 * minimum value is 32
374 #define SG_CHUNK_SIZE 128
377 * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
378 * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
380 #ifdef CONFIG_ARCH_NO_SG_CHAIN
381 #define SG_MAX_SEGMENTS SG_CHUNK_SIZE
383 #define SG_MAX_SEGMENTS 2048
386 #ifdef CONFIG_SG_POOL
387 void sg_free_table_chained(struct sg_table
*table
,
388 unsigned nents_first_chunk
);
389 int sg_alloc_table_chained(struct sg_table
*table
, int nents
,
390 struct scatterlist
*first_chunk
,
391 unsigned nents_first_chunk
);
397 * Iterates over sg entries page-by-page. On each successful iteration, you
398 * can call sg_page_iter_page(@piter) to get the current page.
399 * @piter->sg will point to the sg holding this page and @piter->sg_pgoffset to
400 * the page's page offset within the sg. The iteration will stop either when a
401 * maximum number of sg entries was reached or a terminating sg
402 * (sg_last(sg) == true) was reached.
404 struct sg_page_iter
{
405 struct scatterlist
*sg
; /* sg holding the page */
406 unsigned int sg_pgoffset
; /* page offset within the sg */
408 /* these are internal states, keep away */
409 unsigned int __nents
; /* remaining sg entries */
410 int __pg_advance
; /* nr pages to advance at the
415 * sg page iterator for DMA addresses
417 * This is the same as sg_page_iter however you can call
418 * sg_page_iter_dma_address(@dma_iter) to get the page's DMA
419 * address. sg_page_iter_page() cannot be called on this iterator.
421 struct sg_dma_page_iter
{
422 struct sg_page_iter base
;
425 bool __sg_page_iter_next(struct sg_page_iter
*piter
);
426 bool __sg_page_iter_dma_next(struct sg_dma_page_iter
*dma_iter
);
427 void __sg_page_iter_start(struct sg_page_iter
*piter
,
428 struct scatterlist
*sglist
, unsigned int nents
,
429 unsigned long pgoffset
);
431 * sg_page_iter_page - get the current page held by the page iterator
432 * @piter: page iterator holding the page
434 static inline struct page
*sg_page_iter_page(struct sg_page_iter
*piter
)
436 return nth_page(sg_page(piter
->sg
), piter
->sg_pgoffset
);
440 * sg_page_iter_dma_address - get the dma address of the current page held by
442 * @dma_iter: page iterator holding the page
444 static inline dma_addr_t
445 sg_page_iter_dma_address(struct sg_dma_page_iter
*dma_iter
)
447 return sg_dma_address(dma_iter
->base
.sg
) +
448 (dma_iter
->base
.sg_pgoffset
<< PAGE_SHIFT
);
452 * for_each_sg_page - iterate over the pages of the given sg list
453 * @sglist: sglist to iterate over
454 * @piter: page iterator to hold current page, sg, sg_pgoffset
455 * @nents: maximum number of sg entries to iterate over
456 * @pgoffset: starting page offset (in pages)
458 * Callers may use sg_page_iter_page() to get each page pointer.
459 * In each loop it operates on PAGE_SIZE unit.
461 #define for_each_sg_page(sglist, piter, nents, pgoffset) \
462 for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
463 __sg_page_iter_next(piter);)
466 * for_each_sg_dma_page - iterate over the pages of the given sg list
467 * @sglist: sglist to iterate over
468 * @dma_iter: DMA page iterator to hold current page
469 * @dma_nents: maximum number of sg entries to iterate over, this is the value
470 * returned from dma_map_sg
471 * @pgoffset: starting page offset (in pages)
473 * Callers may use sg_page_iter_dma_address() to get each page's DMA address.
474 * In each loop it operates on PAGE_SIZE unit.
476 #define for_each_sg_dma_page(sglist, dma_iter, dma_nents, pgoffset) \
477 for (__sg_page_iter_start(&(dma_iter)->base, sglist, dma_nents, \
479 __sg_page_iter_dma_next(dma_iter);)
482 * for_each_sgtable_page - iterate over all pages in the sg_table object
483 * @sgt: sg_table object to iterate over
484 * @piter: page iterator to hold current page
485 * @pgoffset: starting page offset (in pages)
487 * Iterates over the all memory pages in the buffer described by
488 * a scatterlist stored in the given sg_table object.
489 * See also for_each_sg_page(). In each loop it operates on PAGE_SIZE unit.
491 #define for_each_sgtable_page(sgt, piter, pgoffset) \
492 for_each_sg_page((sgt)->sgl, piter, (sgt)->orig_nents, pgoffset)
495 * for_each_sgtable_dma_page - iterate over the DMA mapped sg_table object
496 * @sgt: sg_table object to iterate over
497 * @dma_iter: DMA page iterator to hold current page
498 * @pgoffset: starting page offset (in pages)
500 * Iterates over the all DMA mapped pages in the buffer described by
501 * a scatterlist stored in the given sg_table object.
502 * See also for_each_sg_dma_page(). In each loop it operates on PAGE_SIZE
505 #define for_each_sgtable_dma_page(sgt, dma_iter, pgoffset) \
506 for_each_sg_dma_page((sgt)->sgl, dma_iter, (sgt)->nents, pgoffset)
510 * Mapping sg iterator
512 * Iterates over sg entries mapping page-by-page. On each successful
513 * iteration, @miter->page points to the mapped page and
514 * @miter->length bytes of data can be accessed at @miter->addr. As
515 * long as an iteration is enclosed between start and stop, the user
516 * is free to choose control structure and when to stop.
518 * @miter->consumed is set to @miter->length on each iteration. It
519 * can be adjusted if the user can't consume all the bytes in one go.
520 * Also, a stopped iteration can be resumed by calling next on it.
521 * This is useful when iteration needs to release all resources and
522 * continue later (e.g. at the next interrupt).
525 #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */
526 #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */
527 #define SG_MITER_FROM_SG (1 << 2) /* nop */
529 struct sg_mapping_iter
{
530 /* the following three fields can be accessed directly */
531 struct page
*page
; /* currently mapped page */
532 void *addr
; /* pointer to the mapped area */
533 size_t length
; /* length of the mapped area */
534 size_t consumed
; /* number of consumed bytes */
535 struct sg_page_iter piter
; /* page iterator */
537 /* these are internal states, keep away */
538 unsigned int __offset
; /* offset within page */
539 unsigned int __remaining
; /* remaining bytes on page */
540 unsigned int __flags
;
543 void sg_miter_start(struct sg_mapping_iter
*miter
, struct scatterlist
*sgl
,
544 unsigned int nents
, unsigned int flags
);
545 bool sg_miter_skip(struct sg_mapping_iter
*miter
, off_t offset
);
546 bool sg_miter_next(struct sg_mapping_iter
*miter
);
547 void sg_miter_stop(struct sg_mapping_iter
*miter
);
549 #endif /* _LINUX_SCATTERLIST_H */