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1 : : #ifndef _LINUX_SCATTERLIST_H
2 : : #define _LINUX_SCATTERLIST_H
3 : :
4 : : #include <linux/string.h>
5 : : #include <linux/bug.h>
6 : : #include <linux/mm.h>
7 : :
8 : : #include <asm/types.h>
9 : : #include <asm/scatterlist.h>
10 : : #include <asm/io.h>
11 : :
12 : : struct 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 : :
18 : : /*
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 : : */
34 : :
35 : : #define SG_MAGIC 0x87654321
36 : :
37 : : /*
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 : :
47 : : /**
48 : : * sg_assign_page - Assign a given page to an SG entry
49 : : * @sg: SG entry
50 : : * @page: The page
51 : : *
52 : : * Description:
53 : : * Assign page to sg entry. Also see sg_set_page(), the most commonly used
54 : : * variant.
55 : : *
56 : : **/
57 : : static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
58 : : {
59 : 1366431 : unsigned long page_link = sg->page_link & 0x3;
60 : :
61 : : /*
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 [ # # ][ - + ]: 1366431 : BUG_ON((unsigned long) page & 0x03);
[ # # ][ # # ]
[ # # # # ]
[ # # ]
66 : : #ifdef CONFIG_DEBUG_SG
67 : : BUG_ON(sg->sg_magic != SG_MAGIC);
68 : : BUG_ON(sg_is_chain(sg));
69 : : #endif
70 : 1366431 : sg->page_link = page_link | (unsigned long) page;
71 : : }
72 : :
73 : : /**
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 : : **/
87 : : static 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 : 1366431 : sg->offset = offset;
92 : 1366431 : sg->length = len;
93 : : }
94 : :
95 : : static 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 : 1366431 : return (struct page *)((sg)->page_link & ~0x3);
102 : : }
103 : :
104 : : /**
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 : : **/
111 : : static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
112 : : unsigned int buflen)
113 : : {
114 : : #ifdef CONFIG_DEBUG_SG
115 : : BUG_ON(!virt_addr_valid(buf));
116 : : #endif
117 : 0 : sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
118 : : }
119 : :
120 : : /*
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 : :
126 : : /**
127 : : * sg_chain - Chain two sglists together
128 : : * @prv: First scatterlist
129 : : * @prv_nents: Number of entries in prv
130 : : * @sgl: Second scatterlist
131 : : *
132 : : * Description:
133 : : * Links @prv@ and @sgl@ together, to form a longer scatterlist.
134 : : *
135 : : **/
136 : : static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
137 : : struct scatterlist *sgl)
138 : : {
139 : : #ifndef ARCH_HAS_SG_CHAIN
140 : 0 : BUG();
141 : : #endif
142 : :
143 : : /*
144 : : * offset and length are unused for chain entry. Clear them.
145 : : */
146 : : prv[prv_nents - 1].offset = 0;
147 : : prv[prv_nents - 1].length = 0;
148 : :
149 : : /*
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;
154 : : }
155 : :
156 : : /**
157 : : * sg_mark_end - Mark the end of the scatterlist
158 : : * @sg: SG entryScatterlist
159 : : *
160 : : * Description:
161 : : * 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.
163 : : *
164 : : **/
165 : : static inline void sg_mark_end(struct scatterlist *sg)
166 : : {
167 : : #ifdef CONFIG_DEBUG_SG
168 : : BUG_ON(sg->sg_magic != SG_MAGIC);
169 : : #endif
170 : : /*
171 : : * Set termination bit, clear potential chain bit
172 : : */
173 : 789802 : sg->page_link |= 0x02;
174 : 789802 : sg->page_link &= ~0x01;
175 : : }
176 : :
177 : : /**
178 : : * 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 : : **/
185 : : static 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 : 971530 : sg->page_link &= ~0x02;
191 : : }
192 : :
193 : : /**
194 : : * 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 : : **/
203 : 0 : static inline dma_addr_t sg_phys(struct scatterlist *sg)
204 : : {
205 : 0 : return page_to_phys(sg_page(sg)) + sg->offset;
206 : : }
207 : :
208 : : /**
209 : : * sg_virt - Return virtual address of an sg entry
210 : : * @sg: SG entry
211 : : *
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 : : **/
218 : 0 : static inline void *sg_virt(struct scatterlist *sg)
219 : : {
220 : 1366431 : return page_address(sg_page(sg)) + sg->offset;
221 : : }
222 : :
223 : : int sg_nents(struct scatterlist *sg);
224 : : struct scatterlist *sg_next(struct scatterlist *);
225 : : struct scatterlist *sg_last(struct scatterlist *s, unsigned int);
226 : : void sg_init_table(struct scatterlist *, unsigned int);
227 : : void sg_init_one(struct scatterlist *, const void *, unsigned int);
228 : :
229 : : typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t);
230 : : typedef void (sg_free_fn)(struct scatterlist *, unsigned int);
231 : :
232 : : void __sg_free_table(struct sg_table *, unsigned int, sg_free_fn *);
233 : : void sg_free_table(struct sg_table *);
234 : : int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, gfp_t,
235 : : sg_alloc_fn *);
236 : : int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
237 : : int 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);
241 : :
242 : : size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
243 : : void *buf, size_t buflen);
244 : : size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
245 : : void *buf, size_t buflen);
246 : :
247 : : size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
248 : : void *buf, size_t buflen, off_t skip);
249 : : size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
250 : : void *buf, size_t buflen, off_t skip);
251 : :
252 : : /*
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<<4) / sizeof(struct scatterlist))
257 : :
258 : : /*
259 : : * sg page iterator
260 : : *
261 : : * Iterates over sg entries page-by-page. On each successful iteration,
262 : : * 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.
267 : : */
268 : : struct sg_page_iter {
269 : : 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 : :
278 : : bool __sg_page_iter_next(struct sg_page_iter *piter);
279 : : void __sg_page_iter_start(struct sg_page_iter *piter,
280 : : struct scatterlist *sglist, unsigned int nents,
281 : : unsigned long pgoffset);
282 : : /**
283 : : * sg_page_iter_page - get the current page held by the page iterator
284 : : * @piter: page iterator holding the page
285 : : */
286 : : static inline struct page *sg_page_iter_page(struct sg_page_iter *piter)
287 : : {
288 : 0 : 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 : : */
296 : : static 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 : : }
300 : :
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);)
311 : :
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 */
329 : : #define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */
330 : : #define SG_MITER_FROM_SG (1 << 2) /* nop */
331 : :
332 : : struct 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 */
338 : : struct sg_page_iter piter; /* page iterator */
339 : :
340 : : /* these are internal states, keep away */
341 : : unsigned int __offset; /* offset within page */
342 : : unsigned int __remaining; /* remaining bytes on page */
343 : : unsigned int __flags;
344 : : };
345 : :
346 : : void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
347 : : unsigned int nents, unsigned int flags);
348 : : bool sg_miter_next(struct sg_mapping_iter *miter);
349 : : void sg_miter_stop(struct sg_mapping_iter *miter);
350 : :
351 : : #endif /* _LINUX_SCATTERLIST_H */
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