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 #ifdef CONFIG_DEBUG_SG
13 unsigned long sg_magic
;
15 unsigned long page_link
;
18 dma_addr_t dma_address
;
19 #ifdef CONFIG_NEED_SG_DMA_LENGTH
20 unsigned int dma_length
;
25 * Since the above length field is an unsigned int, below we define the maximum
26 * length in bytes that can be stored in one scatterlist entry.
28 #define SCATTERLIST_MAX_SEGMENT (UINT_MAX & PAGE_MASK)
31 * These macros should be used after a dma_map_sg call has been done
32 * to get bus addresses of each of the SG entries and their lengths.
33 * You should only work with the number of sg entries dma_map_sg
34 * returns, or alternatively stop on the first sg_dma_len(sg) which
37 #define sg_dma_address(sg) ((sg)->dma_address)
39 #ifdef CONFIG_NEED_SG_DMA_LENGTH
40 #define sg_dma_len(sg) ((sg)->dma_length)
42 #define sg_dma_len(sg) ((sg)->length)
46 struct scatterlist
*sgl
; /* the list */
47 unsigned int nents
; /* number of mapped entries */
48 unsigned int orig_nents
; /* original size of list */
52 * Notes on SG table design.
54 * We use the unsigned long page_link field in the scatterlist struct to place
55 * the page pointer AND encode information about the sg table as well. The two
56 * lower bits are reserved for this information.
58 * If bit 0 is set, then the page_link contains a pointer to the next sg
59 * table list. Otherwise the next entry is at sg + 1.
61 * If bit 1 is set, then this sg entry is the last element in a list.
67 #define SG_MAGIC 0x87654321
70 * We overload the LSB of the page pointer to indicate whether it's
71 * a valid sg entry, or whether it points to the start of a new scatterlist.
72 * Those low bits are there for everyone! (thanks mason :-)
74 #define sg_is_chain(sg) ((sg)->page_link & 0x01)
75 #define sg_is_last(sg) ((sg)->page_link & 0x02)
76 #define sg_chain_ptr(sg) \
77 ((struct scatterlist *) ((sg)->page_link & ~0x03))
80 * sg_assign_page - Assign a given page to an SG entry
85 * Assign page to sg entry. Also see sg_set_page(), the most commonly used
89 static inline void sg_assign_page(struct scatterlist
*sg
, struct page
*page
)
91 unsigned long page_link
= sg
->page_link
& 0x3;
94 * In order for the low bit stealing approach to work, pages
95 * must be aligned at a 32-bit boundary as a minimum.
97 BUG_ON((unsigned long) page
& 0x03);
98 #ifdef CONFIG_DEBUG_SG
99 BUG_ON(sg
->sg_magic
!= SG_MAGIC
);
100 BUG_ON(sg_is_chain(sg
));
102 sg
->page_link
= page_link
| (unsigned long) page
;
106 * sg_set_page - Set sg entry to point at given page
109 * @len: Length of data
110 * @offset: Offset into page
113 * Use this function to set an sg entry pointing at a page, never assign
114 * the page directly. We encode sg table information in the lower bits
115 * of the page pointer. See sg_page() for looking up the page belonging
119 static inline void sg_set_page(struct scatterlist
*sg
, struct page
*page
,
120 unsigned int len
, unsigned int offset
)
122 sg_assign_page(sg
, page
);
127 static inline struct page
*sg_page(struct scatterlist
*sg
)
129 #ifdef CONFIG_DEBUG_SG
130 BUG_ON(sg
->sg_magic
!= SG_MAGIC
);
131 BUG_ON(sg_is_chain(sg
));
133 return (struct page
*)((sg
)->page_link
& ~0x3);
137 * sg_set_buf - Set sg entry to point at given data
140 * @buflen: Data length
143 static inline void sg_set_buf(struct scatterlist
*sg
, const void *buf
,
146 #ifdef CONFIG_DEBUG_SG
147 BUG_ON(!virt_addr_valid(buf
));
149 sg_set_page(sg
, virt_to_page(buf
), buflen
, offset_in_page(buf
));
153 * Loop over each sg element, following the pointer to a new list if necessary
155 #define for_each_sg(sglist, sg, nr, __i) \
156 for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
159 * sg_chain - Chain two sglists together
160 * @prv: First scatterlist
161 * @prv_nents: Number of entries in prv
162 * @sgl: Second scatterlist
165 * Links @prv@ and @sgl@ together, to form a longer scatterlist.
168 static inline void sg_chain(struct scatterlist
*prv
, unsigned int prv_nents
,
169 struct scatterlist
*sgl
)
172 * offset and length are unused for chain entry. Clear them.
174 prv
[prv_nents
- 1].offset
= 0;
175 prv
[prv_nents
- 1].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 prv
[prv_nents
- 1].page_link
= ((unsigned long) sgl
| 0x01) & ~0x02;
185 * sg_mark_end - Mark the end of the scatterlist
186 * @sg: SG entryScatterlist
189 * Marks the passed in sg entry as the termination point for the sg
190 * table. A call to sg_next() on this entry will return NULL.
193 static inline void sg_mark_end(struct scatterlist
*sg
)
195 #ifdef CONFIG_DEBUG_SG
196 BUG_ON(sg
->sg_magic
!= SG_MAGIC
);
199 * Set termination bit, clear potential chain bit
201 sg
->page_link
|= 0x02;
202 sg
->page_link
&= ~0x01;
206 * sg_unmark_end - Undo setting the end of the scatterlist
207 * @sg: SG entryScatterlist
210 * Removes the termination marker from the given entry of the scatterlist.
213 static inline void sg_unmark_end(struct scatterlist
*sg
)
215 #ifdef CONFIG_DEBUG_SG
216 BUG_ON(sg
->sg_magic
!= SG_MAGIC
);
218 sg
->page_link
&= ~0x02;
222 * sg_phys - Return physical address of an sg entry
226 * This calls page_to_phys() on the page in this sg entry, and adds the
227 * sg offset. The caller must know that it is legal to call page_to_phys()
231 static inline dma_addr_t
sg_phys(struct scatterlist
*sg
)
233 return page_to_phys(sg_page(sg
)) + sg
->offset
;
237 * sg_virt - Return virtual address of an sg entry
241 * This calls page_address() on the page in this sg entry, and adds the
242 * sg offset. The caller must know that the sg page has a valid virtual
246 static inline void *sg_virt(struct scatterlist
*sg
)
248 return page_address(sg_page(sg
)) + sg
->offset
;
251 int sg_nents(struct scatterlist
*sg
);
252 int sg_nents_for_len(struct scatterlist
*sg
, u64 len
);
253 struct scatterlist
*sg_next(struct scatterlist
*);
254 struct scatterlist
*sg_last(struct scatterlist
*s
, unsigned int);
255 void sg_init_table(struct scatterlist
*, unsigned int);
256 void sg_init_one(struct scatterlist
*, const void *, unsigned int);
257 int sg_split(struct scatterlist
*in
, const int in_mapped_nents
,
258 const off_t skip
, const int nb_splits
,
259 const size_t *split_sizes
,
260 struct scatterlist
**out
, int *out_mapped_nents
,
263 typedef struct scatterlist
*(sg_alloc_fn
)(unsigned int, gfp_t
);
264 typedef void (sg_free_fn
)(struct scatterlist
*, unsigned int);
266 void __sg_free_table(struct sg_table
*, unsigned int, bool, sg_free_fn
*);
267 void sg_free_table(struct sg_table
*);
268 int __sg_alloc_table(struct sg_table
*, unsigned int, unsigned int,
269 struct scatterlist
*, gfp_t
, sg_alloc_fn
*);
270 int sg_alloc_table(struct sg_table
*, unsigned int, gfp_t
);
271 int __sg_alloc_table_from_pages(struct sg_table
*sgt
, struct page
**pages
,
272 unsigned int n_pages
, unsigned int offset
,
273 unsigned long size
, unsigned int max_segment
,
275 int sg_alloc_table_from_pages(struct sg_table
*sgt
, struct page
**pages
,
276 unsigned int n_pages
, unsigned int offset
,
277 unsigned long size
, gfp_t gfp_mask
);
279 #ifdef CONFIG_SGL_ALLOC
280 struct scatterlist
*sgl_alloc_order(unsigned long long length
,
281 unsigned int order
, bool chainable
,
282 gfp_t gfp
, unsigned int *nent_p
);
283 struct scatterlist
*sgl_alloc(unsigned long long length
, gfp_t gfp
,
284 unsigned int *nent_p
);
285 void sgl_free_n_order(struct scatterlist
*sgl
, int nents
, int order
);
286 void sgl_free_order(struct scatterlist
*sgl
, int order
);
287 void sgl_free(struct scatterlist
*sgl
);
288 #endif /* CONFIG_SGL_ALLOC */
290 size_t sg_copy_buffer(struct scatterlist
*sgl
, unsigned int nents
, void *buf
,
291 size_t buflen
, off_t skip
, bool to_buffer
);
293 size_t sg_copy_from_buffer(struct scatterlist
*sgl
, unsigned int nents
,
294 const void *buf
, size_t buflen
);
295 size_t sg_copy_to_buffer(struct scatterlist
*sgl
, unsigned int nents
,
296 void *buf
, size_t buflen
);
298 size_t sg_pcopy_from_buffer(struct scatterlist
*sgl
, unsigned int nents
,
299 const void *buf
, size_t buflen
, off_t skip
);
300 size_t sg_pcopy_to_buffer(struct scatterlist
*sgl
, unsigned int nents
,
301 void *buf
, size_t buflen
, off_t skip
);
302 size_t sg_zero_buffer(struct scatterlist
*sgl
, unsigned int nents
,
303 size_t buflen
, off_t skip
);
306 * Maximum number of entries that will be allocated in one piece, if
307 * a list larger than this is required then chaining will be utilized.
309 #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
312 * The maximum number of SG segments that we will put inside a
313 * scatterlist (unless chaining is used). Should ideally fit inside a
314 * single page, to avoid a higher order allocation. We could define this
315 * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The
316 * minimum value is 32
318 #define SG_CHUNK_SIZE 128
321 * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
322 * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
324 #ifdef CONFIG_ARCH_HAS_SG_CHAIN
325 #define SG_MAX_SEGMENTS 2048
327 #define SG_MAX_SEGMENTS SG_CHUNK_SIZE
330 #ifdef CONFIG_SG_POOL
331 void sg_free_table_chained(struct sg_table
*table
, bool first_chunk
);
332 int sg_alloc_table_chained(struct sg_table
*table
, int nents
,
333 struct scatterlist
*first_chunk
);
339 * Iterates over sg entries page-by-page. On each successful iteration,
340 * you can call sg_page_iter_page(@piter) and sg_page_iter_dma_address(@piter)
341 * to get the current page and its dma address. @piter->sg will point to the
342 * sg holding this page and @piter->sg_pgoffset to the page's page offset
343 * within the sg. The iteration will stop either when a maximum number of sg
344 * entries was reached or a terminating sg (sg_last(sg) == true) was reached.
346 struct sg_page_iter
{
347 struct scatterlist
*sg
; /* sg holding the page */
348 unsigned int sg_pgoffset
; /* page offset within the sg */
350 /* these are internal states, keep away */
351 unsigned int __nents
; /* remaining sg entries */
352 int __pg_advance
; /* nr pages to advance at the
356 bool __sg_page_iter_next(struct sg_page_iter
*piter
);
357 void __sg_page_iter_start(struct sg_page_iter
*piter
,
358 struct scatterlist
*sglist
, unsigned int nents
,
359 unsigned long pgoffset
);
361 * sg_page_iter_page - get the current page held by the page iterator
362 * @piter: page iterator holding the page
364 static inline struct page
*sg_page_iter_page(struct sg_page_iter
*piter
)
366 return nth_page(sg_page(piter
->sg
), piter
->sg_pgoffset
);
370 * sg_page_iter_dma_address - get the dma address of the current page held by
372 * @piter: page iterator holding the page
374 static inline dma_addr_t
sg_page_iter_dma_address(struct sg_page_iter
*piter
)
376 return sg_dma_address(piter
->sg
) + (piter
->sg_pgoffset
<< PAGE_SHIFT
);
380 * for_each_sg_page - iterate over the pages of the given sg list
381 * @sglist: sglist to iterate over
382 * @piter: page iterator to hold current page, sg, sg_pgoffset
383 * @nents: maximum number of sg entries to iterate over
384 * @pgoffset: starting page offset
386 #define for_each_sg_page(sglist, piter, nents, pgoffset) \
387 for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
388 __sg_page_iter_next(piter);)
391 * Mapping sg iterator
393 * Iterates over sg entries mapping page-by-page. On each successful
394 * iteration, @miter->page points to the mapped page and
395 * @miter->length bytes of data can be accessed at @miter->addr. As
396 * long as an interation is enclosed between start and stop, the user
397 * is free to choose control structure and when to stop.
399 * @miter->consumed is set to @miter->length on each iteration. It
400 * can be adjusted if the user can't consume all the bytes in one go.
401 * Also, a stopped iteration can be resumed by calling next on it.
402 * This is useful when iteration needs to release all resources and
403 * continue later (e.g. at the next interrupt).
406 #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */
407 #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */
408 #define SG_MITER_FROM_SG (1 << 2) /* nop */
410 struct sg_mapping_iter
{
411 /* the following three fields can be accessed directly */
412 struct page
*page
; /* currently mapped page */
413 void *addr
; /* pointer to the mapped area */
414 size_t length
; /* length of the mapped area */
415 size_t consumed
; /* number of consumed bytes */
416 struct sg_page_iter piter
; /* page iterator */
418 /* these are internal states, keep away */
419 unsigned int __offset
; /* offset within page */
420 unsigned int __remaining
; /* remaining bytes on page */
421 unsigned int __flags
;
424 void sg_miter_start(struct sg_mapping_iter
*miter
, struct scatterlist
*sgl
,
425 unsigned int nents
, unsigned int flags
);
426 bool sg_miter_skip(struct sg_mapping_iter
*miter
, off_t offset
);
427 bool sg_miter_next(struct sg_mapping_iter
*miter
);
428 void sg_miter_stop(struct sg_mapping_iter
*miter
);
430 #endif /* _LINUX_SCATTERLIST_H */