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1 : : /* SPDX-License-Identifier: GPL-2.0 */
2 : : #ifndef _LINUX_SCATTERLIST_H
3 : : #define _LINUX_SCATTERLIST_H
4 : :
5 : : #include <linux/string.h>
6 : : #include <linux/types.h>
7 : : #include <linux/bug.h>
8 : : #include <linux/mm.h>
9 : : #include <asm/io.h>
10 : :
11 : : struct scatterlist {
12 : : unsigned long page_link;
13 : : unsigned int offset;
14 : : unsigned int length;
15 : : dma_addr_t dma_address;
16 : : #ifdef CONFIG_NEED_SG_DMA_LENGTH
17 : : unsigned int dma_length;
18 : : #endif
19 : : };
20 : :
21 : : /*
22 : : * Since the above length field is an unsigned int, below we define the maximum
23 : : * length in bytes that can be stored in one scatterlist entry.
24 : : */
25 : : #define SCATTERLIST_MAX_SEGMENT (UINT_MAX & PAGE_MASK)
26 : :
27 : : /*
28 : : * These macros should be used after a dma_map_sg call has been done
29 : : * to get bus addresses of each of the SG entries and their lengths.
30 : : * You should only work with the number of sg entries dma_map_sg
31 : : * returns, or alternatively stop on the first sg_dma_len(sg) which
32 : : * is 0.
33 : : */
34 : : #define sg_dma_address(sg) ((sg)->dma_address)
35 : :
36 : : #ifdef CONFIG_NEED_SG_DMA_LENGTH
37 : : #define sg_dma_len(sg) ((sg)->dma_length)
38 : : #else
39 : : #define sg_dma_len(sg) ((sg)->length)
40 : : #endif
41 : :
42 : : struct sg_table {
43 : : struct scatterlist *sgl; /* the list */
44 : : unsigned int nents; /* number of mapped entries */
45 : : unsigned int orig_nents; /* original size of list */
46 : : };
47 : :
48 : : /*
49 : : * Notes on SG table design.
50 : : *
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.
54 : : *
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.
57 : : *
58 : : * If bit 1 is set, then this sg entry is the last element in a list.
59 : : *
60 : : * See sg_next().
61 : : *
62 : : */
63 : :
64 : : #define SG_CHAIN 0x01UL
65 : : #define SG_END 0x02UL
66 : :
67 : : /*
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 :-)
71 : : */
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)))
76 : :
77 : : /**
78 : : * sg_assign_page - Assign a given page to an SG entry
79 : : * @sg: SG entry
80 : : * @page: The page
81 : : *
82 : : * Description:
83 : : * Assign page to sg entry. Also see sg_set_page(), the most commonly used
84 : : * variant.
85 : : *
86 : : **/
87 : 3 : static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
88 : : {
89 : 3 : unsigned long page_link = sg->page_link & (SG_CHAIN | SG_END);
90 : :
91 : : /*
92 : : * In order for the low bit stealing approach to work, pages
93 : : * must be aligned at a 32-bit boundary as a minimum.
94 : : */
95 : 3 : BUG_ON((unsigned long) page & (SG_CHAIN | SG_END));
96 : : #ifdef CONFIG_DEBUG_SG
97 : : BUG_ON(sg_is_chain(sg));
98 : : #endif
99 : 3 : sg->page_link = page_link | (unsigned long) page;
100 : 3 : }
101 : :
102 : : /**
103 : : * sg_set_page - Set sg entry to point at given page
104 : : * @sg: SG entry
105 : : * @page: The page
106 : : * @len: Length of data
107 : : * @offset: Offset into page
108 : : *
109 : : * Description:
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
113 : : * to an sg entry.
114 : : *
115 : : **/
116 : 0 : static inline void sg_set_page(struct scatterlist *sg, struct page *page,
117 : : unsigned int len, unsigned int offset)
118 : : {
119 : 3 : sg_assign_page(sg, page);
120 : 3 : sg->offset = offset;
121 : 3 : sg->length = len;
122 : 0 : }
123 : :
124 : 0 : static inline struct page *sg_page(struct scatterlist *sg)
125 : : {
126 : : #ifdef CONFIG_DEBUG_SG
127 : : BUG_ON(sg_is_chain(sg));
128 : : #endif
129 : 3 : return (struct page *)((sg)->page_link & ~(SG_CHAIN | SG_END));
130 : : }
131 : :
132 : : /**
133 : : * sg_set_buf - Set sg entry to point at given data
134 : : * @sg: SG entry
135 : : * @buf: Data
136 : : * @buflen: Data length
137 : : *
138 : : **/
139 : 3 : static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
140 : : unsigned int buflen)
141 : : {
142 : : #ifdef CONFIG_DEBUG_SG
143 : : BUG_ON(!virt_addr_valid(buf));
144 : : #endif
145 : 3 : sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
146 : 3 : }
147 : :
148 : : /*
149 : : * Loop over each sg element, following the pointer to a new list if necessary
150 : : */
151 : : #define for_each_sg(sglist, sg, nr, __i) \
152 : : for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
153 : :
154 : : /**
155 : : * sg_chain - Chain two sglists together
156 : : * @prv: First scatterlist
157 : : * @prv_nents: Number of entries in prv
158 : : * @sgl: Second scatterlist
159 : : *
160 : : * Description:
161 : : * Links @prv@ and @sgl@ together, to form a longer scatterlist.
162 : : *
163 : : **/
164 : : static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
165 : : struct scatterlist *sgl)
166 : : {
167 : : /*
168 : : * offset and length are unused for chain entry. Clear them.
169 : : */
170 : 0 : prv[prv_nents - 1].offset = 0;
171 : 0 : prv[prv_nents - 1].length = 0;
172 : :
173 : : /*
174 : : * Set lowest bit to indicate a link pointer, and make sure to clear
175 : : * the termination bit if it happens to be set.
176 : : */
177 : 0 : prv[prv_nents - 1].page_link = ((unsigned long) sgl | SG_CHAIN)
178 : 0 : & ~SG_END;
179 : : }
180 : :
181 : : /**
182 : : * sg_mark_end - Mark the end of the scatterlist
183 : : * @sg: SG entryScatterlist
184 : : *
185 : : * Description:
186 : : * Marks the passed in sg entry as the termination point for the sg
187 : : * table. A call to sg_next() on this entry will return NULL.
188 : : *
189 : : **/
190 : : static inline void sg_mark_end(struct scatterlist *sg)
191 : : {
192 : : /*
193 : : * Set termination bit, clear potential chain bit
194 : : */
195 : 3 : sg->page_link |= SG_END;
196 : 3 : sg->page_link &= ~SG_CHAIN;
197 : : }
198 : :
199 : : /**
200 : : * sg_unmark_end - Undo setting the end of the scatterlist
201 : : * @sg: SG entryScatterlist
202 : : *
203 : : * Description:
204 : : * Removes the termination marker from the given entry of the scatterlist.
205 : : *
206 : : **/
207 : 0 : static inline void sg_unmark_end(struct scatterlist *sg)
208 : : {
209 : 3 : sg->page_link &= ~SG_END;
210 : 0 : }
211 : :
212 : : /**
213 : : * sg_phys - Return physical address of an sg entry
214 : : * @sg: SG entry
215 : : *
216 : : * Description:
217 : : * This calls page_to_phys() on the page in this sg entry, and adds the
218 : : * sg offset. The caller must know that it is legal to call page_to_phys()
219 : : * on the sg page.
220 : : *
221 : : **/
222 : : static inline dma_addr_t sg_phys(struct scatterlist *sg)
223 : : {
224 : : return page_to_phys(sg_page(sg)) + sg->offset;
225 : : }
226 : :
227 : : /**
228 : : * sg_virt - Return virtual address of an sg entry
229 : : * @sg: SG entry
230 : : *
231 : : * Description:
232 : : * This calls page_address() on the page in this sg entry, and adds the
233 : : * sg offset. The caller must know that the sg page has a valid virtual
234 : : * mapping.
235 : : *
236 : : **/
237 : 0 : static inline void *sg_virt(struct scatterlist *sg)
238 : : {
239 : 0 : return page_address(sg_page(sg)) + sg->offset;
240 : : }
241 : :
242 : : /**
243 : : * sg_init_marker - Initialize markers in sg table
244 : : * @sgl: The SG table
245 : : * @nents: Number of entries in table
246 : : *
247 : : **/
248 : : static inline void sg_init_marker(struct scatterlist *sgl,
249 : : unsigned int nents)
250 : : {
251 : 3 : sg_mark_end(&sgl[nents - 1]);
252 : : }
253 : :
254 : : int sg_nents(struct scatterlist *sg);
255 : : int sg_nents_for_len(struct scatterlist *sg, u64 len);
256 : : struct scatterlist *sg_next(struct scatterlist *);
257 : : struct scatterlist *sg_last(struct scatterlist *s, unsigned int);
258 : : void sg_init_table(struct scatterlist *, unsigned int);
259 : : void sg_init_one(struct scatterlist *, const void *, unsigned int);
260 : : int sg_split(struct scatterlist *in, const int in_mapped_nents,
261 : : const off_t skip, const int nb_splits,
262 : : const size_t *split_sizes,
263 : : struct scatterlist **out, int *out_mapped_nents,
264 : : gfp_t gfp_mask);
265 : :
266 : : typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t);
267 : : typedef void (sg_free_fn)(struct scatterlist *, unsigned int);
268 : :
269 : : void __sg_free_table(struct sg_table *, unsigned int, unsigned int,
270 : : sg_free_fn *);
271 : : void sg_free_table(struct sg_table *);
272 : : int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
273 : : struct scatterlist *, unsigned int, gfp_t, sg_alloc_fn *);
274 : : int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
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, unsigned int max_segment,
278 : : gfp_t gfp_mask);
279 : : int sg_alloc_table_from_pages(struct sg_table *sgt, struct page **pages,
280 : : unsigned int n_pages, unsigned int offset,
281 : : unsigned long size, gfp_t gfp_mask);
282 : :
283 : : #ifdef CONFIG_SGL_ALLOC
284 : : struct scatterlist *sgl_alloc_order(unsigned long long length,
285 : : unsigned int order, bool chainable,
286 : : gfp_t gfp, unsigned int *nent_p);
287 : : struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
288 : : unsigned int *nent_p);
289 : : void sgl_free_n_order(struct scatterlist *sgl, int nents, int order);
290 : : void sgl_free_order(struct scatterlist *sgl, int order);
291 : : void sgl_free(struct scatterlist *sgl);
292 : : #endif /* CONFIG_SGL_ALLOC */
293 : :
294 : : size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
295 : : size_t buflen, off_t skip, bool to_buffer);
296 : :
297 : : size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
298 : : const void *buf, size_t buflen);
299 : : size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
300 : : void *buf, size_t buflen);
301 : :
302 : : size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
303 : : const void *buf, size_t buflen, off_t skip);
304 : : size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
305 : : void *buf, size_t buflen, off_t skip);
306 : : size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
307 : : size_t buflen, off_t skip);
308 : :
309 : : /*
310 : : * Maximum number of entries that will be allocated in one piece, if
311 : : * a list larger than this is required then chaining will be utilized.
312 : : */
313 : : #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
314 : :
315 : : /*
316 : : * The maximum number of SG segments that we will put inside a
317 : : * scatterlist (unless chaining is used). Should ideally fit inside a
318 : : * single page, to avoid a higher order allocation. We could define this
319 : : * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The
320 : : * minimum value is 32
321 : : */
322 : : #define SG_CHUNK_SIZE 128
323 : :
324 : : /*
325 : : * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
326 : : * is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
327 : : */
328 : : #ifdef CONFIG_ARCH_NO_SG_CHAIN
329 : : #define SG_MAX_SEGMENTS SG_CHUNK_SIZE
330 : : #else
331 : : #define SG_MAX_SEGMENTS 2048
332 : : #endif
333 : :
334 : : #ifdef CONFIG_SG_POOL
335 : : void sg_free_table_chained(struct sg_table *table,
336 : : unsigned nents_first_chunk);
337 : : int sg_alloc_table_chained(struct sg_table *table, int nents,
338 : : struct scatterlist *first_chunk,
339 : : unsigned nents_first_chunk);
340 : : #endif
341 : :
342 : : /*
343 : : * sg page iterator
344 : : *
345 : : * Iterates over sg entries page-by-page. On each successful iteration, you
346 : : * can call sg_page_iter_page(@piter) to get the current page.
347 : : * @piter->sg will point to the sg holding this page and @piter->sg_pgoffset to
348 : : * the page's page offset within the sg. The iteration will stop either when a
349 : : * maximum number of sg entries was reached or a terminating sg
350 : : * (sg_last(sg) == true) was reached.
351 : : */
352 : : struct sg_page_iter {
353 : : struct scatterlist *sg; /* sg holding the page */
354 : : unsigned int sg_pgoffset; /* page offset within the sg */
355 : :
356 : : /* these are internal states, keep away */
357 : : unsigned int __nents; /* remaining sg entries */
358 : : int __pg_advance; /* nr pages to advance at the
359 : : * next step */
360 : : };
361 : :
362 : : /*
363 : : * sg page iterator for DMA addresses
364 : : *
365 : : * This is the same as sg_page_iter however you can call
366 : : * sg_page_iter_dma_address(@dma_iter) to get the page's DMA
367 : : * address. sg_page_iter_page() cannot be called on this iterator.
368 : : */
369 : : struct sg_dma_page_iter {
370 : : struct sg_page_iter base;
371 : : };
372 : :
373 : : bool __sg_page_iter_next(struct sg_page_iter *piter);
374 : : bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter);
375 : : void __sg_page_iter_start(struct sg_page_iter *piter,
376 : : struct scatterlist *sglist, unsigned int nents,
377 : : unsigned long pgoffset);
378 : : /**
379 : : * sg_page_iter_page - get the current page held by the page iterator
380 : : * @piter: page iterator holding the page
381 : : */
382 : : static inline struct page *sg_page_iter_page(struct sg_page_iter *piter)
383 : : {
384 : 3 : return nth_page(sg_page(piter->sg), piter->sg_pgoffset);
385 : : }
386 : :
387 : : /**
388 : : * sg_page_iter_dma_address - get the dma address of the current page held by
389 : : * the page iterator.
390 : : * @dma_iter: page iterator holding the page
391 : : */
392 : : static inline dma_addr_t
393 : : sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter)
394 : : {
395 : : return sg_dma_address(dma_iter->base.sg) +
396 : : (dma_iter->base.sg_pgoffset << PAGE_SHIFT);
397 : : }
398 : :
399 : : /**
400 : : * for_each_sg_page - iterate over the pages of the given sg list
401 : : * @sglist: sglist to iterate over
402 : : * @piter: page iterator to hold current page, sg, sg_pgoffset
403 : : * @nents: maximum number of sg entries to iterate over
404 : : * @pgoffset: starting page offset
405 : : *
406 : : * Callers may use sg_page_iter_page() to get each page pointer.
407 : : */
408 : : #define for_each_sg_page(sglist, piter, nents, pgoffset) \
409 : : for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
410 : : __sg_page_iter_next(piter);)
411 : :
412 : : /**
413 : : * for_each_sg_dma_page - iterate over the pages of the given sg list
414 : : * @sglist: sglist to iterate over
415 : : * @dma_iter: page iterator to hold current page
416 : : * @dma_nents: maximum number of sg entries to iterate over, this is the value
417 : : * returned from dma_map_sg
418 : : * @pgoffset: starting page offset
419 : : *
420 : : * Callers may use sg_page_iter_dma_address() to get each page's DMA address.
421 : : */
422 : : #define for_each_sg_dma_page(sglist, dma_iter, dma_nents, pgoffset) \
423 : : for (__sg_page_iter_start(&(dma_iter)->base, sglist, dma_nents, \
424 : : pgoffset); \
425 : : __sg_page_iter_dma_next(dma_iter);)
426 : :
427 : : /*
428 : : * Mapping sg iterator
429 : : *
430 : : * Iterates over sg entries mapping page-by-page. On each successful
431 : : * iteration, @miter->page points to the mapped page and
432 : : * @miter->length bytes of data can be accessed at @miter->addr. As
433 : : * long as an interation is enclosed between start and stop, the user
434 : : * is free to choose control structure and when to stop.
435 : : *
436 : : * @miter->consumed is set to @miter->length on each iteration. It
437 : : * can be adjusted if the user can't consume all the bytes in one go.
438 : : * Also, a stopped iteration can be resumed by calling next on it.
439 : : * This is useful when iteration needs to release all resources and
440 : : * continue later (e.g. at the next interrupt).
441 : : */
442 : :
443 : : #define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */
444 : : #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */
445 : : #define SG_MITER_FROM_SG (1 << 2) /* nop */
446 : :
447 : : struct sg_mapping_iter {
448 : : /* the following three fields can be accessed directly */
449 : : struct page *page; /* currently mapped page */
450 : : void *addr; /* pointer to the mapped area */
451 : : size_t length; /* length of the mapped area */
452 : : size_t consumed; /* number of consumed bytes */
453 : : struct sg_page_iter piter; /* page iterator */
454 : :
455 : : /* these are internal states, keep away */
456 : : unsigned int __offset; /* offset within page */
457 : : unsigned int __remaining; /* remaining bytes on page */
458 : : unsigned int __flags;
459 : : };
460 : :
461 : : void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
462 : : unsigned int nents, unsigned int flags);
463 : : bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset);
464 : : bool sg_miter_next(struct sg_mapping_iter *miter);
465 : : void sg_miter_stop(struct sg_mapping_iter *miter);
466 : :
467 : : #endif /* _LINUX_SCATTERLIST_H */
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