1 /* 2 * Copyright (c) 2010 Isilon Systems, Inc. 3 * Copyright (c) 2010 iX Systems, Inc. 4 * Copyright (c) 2010 Panasas, Inc. 5 * Copyright (c) 2013, 2014 Mellanox Technologies, Ltd. 6 * Copyright (c) 2015 Matthew Dillon <dillon@backplane.com> 7 * Copyright (c) 2016 Matt Macy <mmacy@nextbsd.org> 8 * Copyright (c) 2017-2020 François Tigeot <ftigeot@wolfpond.org> 9 * All rights reserved. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice unmodified, this list of conditions, and the following 16 * disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 #ifndef _LINUX_SCATTERLIST_H_ 34 #define _LINUX_SCATTERLIST_H_ 35 36 #include <linux/string.h> 37 #include <linux/types.h> 38 #include <linux/bug.h> 39 #include <linux/mm.h> 40 #include <asm/io.h> 41 42 /* 43 * SG table design. 44 * 45 * If flags bit 0 is set, then the sg field contains a pointer to the next sg 46 * table list. Otherwise the next entry is at sg + 1, can be determined using 47 * the sg_is_chain() function. 48 * 49 * If flags bit 1 is set, then this sg entry is the last element in a list, 50 * can be determined using the sg_is_last() function. 51 * 52 * See sg_next(). 53 * 54 */ 55 56 struct scatterlist { 57 union { 58 struct page *page; 59 struct scatterlist *sg; 60 } sl_un; 61 unsigned long offset; 62 uint32_t length; 63 dma_addr_t dma_address; 64 uint32_t flags; 65 }; 66 67 struct sg_table { 68 struct scatterlist *sgl; /* the list */ 69 unsigned int nents; /* number of mapped entries */ 70 unsigned int orig_nents; /* original size of list */ 71 }; 72 73 struct sg_page_iter { 74 struct scatterlist *sg; 75 unsigned int sg_pgoffset; /* page index */ 76 unsigned int maxents; 77 unsigned int __nents; 78 int __pg_advance; 79 }; 80 81 82 /* 83 * Maximum number of entries that will be allocated in one piece, if 84 * a list larger than this is required then chaining will be utilized. 85 */ 86 #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) 87 88 #define sg_dma_address(sg) (sg)->dma_address 89 #define sg_dma_len(sg) (sg)->length 90 #define sg_page(sg) (sg)->sl_un.page 91 #define sg_scatternext(sg) (sg)->sl_un.sg 92 93 #define SG_END 0x01 94 #define SG_CHAIN 0x02 95 96 static inline void 97 sg_set_page(struct scatterlist *sg, struct page *page, unsigned int len, 98 unsigned int offset) 99 { 100 sg_page(sg) = page; 101 sg_dma_len(sg) = len; 102 sg->offset = offset; 103 if (offset > PAGE_SIZE) 104 panic("sg_set_page: Invalid offset %d\n", offset); 105 } 106 107 static inline void 108 sg_init_table(struct scatterlist *sg, unsigned int nents) 109 { 110 bzero(sg, sizeof(*sg) * nents); 111 sg[nents - 1].flags = SG_END; 112 } 113 114 static inline struct scatterlist * 115 sg_next(struct scatterlist *sg) 116 { 117 if (sg->flags & SG_END) 118 return (NULL); 119 sg++; 120 if (sg->flags & SG_CHAIN) 121 sg = sg_scatternext(sg); 122 return (sg); 123 } 124 125 static inline vm_paddr_t 126 sg_phys(struct scatterlist *sg) 127 { 128 return ((struct vm_page *)sg_page(sg))->phys_addr + sg->offset; 129 } 130 131 /** 132 * sg_chain - Chain two sglists together 133 * @prv: First scatterlist 134 * @prv_nents: Number of entries in prv 135 * @sgl: Second scatterlist 136 * 137 * Description: 138 * Links @prv@ and @sgl@ together, to form a longer scatterlist. 139 * 140 **/ 141 static inline void 142 sg_chain(struct scatterlist *prv, unsigned int prv_nents, 143 struct scatterlist *sgl) 144 { 145 /* 146 * offset and length are unused for chain entry. Clear them. 147 */ 148 struct scatterlist *sg = &prv[prv_nents - 1]; 149 150 sg->offset = 0; 151 sg->length = 0; 152 153 /* 154 * Indicate a link pointer, and set the link to the second list. 155 */ 156 sg->flags = SG_CHAIN; 157 sg->sl_un.sg = sgl; 158 } 159 160 /** 161 * sg_mark_end - Mark the end of the scatterlist 162 * @sg: SG entryScatterlist 163 * 164 * Description: 165 * Marks the passed in sg entry as the termination point for the sg 166 * table. A call to sg_next() on this entry will return NULL. 167 * 168 **/ 169 static inline void sg_mark_end(struct scatterlist *sg) 170 { 171 sg->flags = SG_END; 172 } 173 174 /** 175 * __sg_free_table - Free a previously mapped sg table 176 * @table: The sg table header to use 177 * @max_ents: The maximum number of entries per single scatterlist 178 * 179 * Description: 180 * Free an sg table previously allocated and setup with 181 * __sg_alloc_table(). The @max_ents value must be identical to 182 * that previously used with __sg_alloc_table(). 183 * 184 **/ 185 void __sg_free_table(struct sg_table *table, unsigned int max_ents); 186 187 /** 188 * sg_free_table - Free a previously allocated sg table 189 * @table: The mapped sg table header 190 * 191 **/ 192 static inline void 193 sg_free_table(struct sg_table *table) 194 { 195 __sg_free_table(table, SG_MAX_SINGLE_ALLOC); 196 } 197 198 int __sg_alloc_table(struct sg_table *table, unsigned int nents, 199 unsigned int max_ents, gfp_t gfp_mask); 200 201 /** 202 * sg_alloc_table - Allocate and initialize an sg table 203 * @table: The sg table header to use 204 * @nents: Number of entries in sg list 205 * @gfp_mask: GFP allocation mask 206 * 207 * Description: 208 * Allocate and initialize an sg table. If @nents@ is larger than 209 * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. 210 * 211 **/ 212 213 static inline int 214 sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) 215 { 216 int ret; 217 218 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, 219 gfp_mask); 220 if (unlikely(ret)) 221 __sg_free_table(table, SG_MAX_SINGLE_ALLOC); 222 223 return ret; 224 } 225 226 static inline int 227 sg_nents(struct scatterlist *sg) 228 { 229 int nents; 230 for (nents = 0; sg; sg = sg_next(sg)) 231 nents++; 232 return nents; 233 } 234 235 static inline void 236 __sg_page_iter_start(struct sg_page_iter *piter, 237 struct scatterlist *sglist, unsigned int nents, 238 unsigned long pgoffset) 239 { 240 piter->__pg_advance = 0; 241 piter->__nents = nents; 242 243 piter->sg = sglist; 244 piter->sg_pgoffset = pgoffset; 245 } 246 247 /* 248 * Iterate pages in sg list. 249 */ 250 static inline void 251 _sg_iter_next(struct sg_page_iter *iter) 252 { 253 struct scatterlist *sg; 254 unsigned int pgcount; 255 256 sg = iter->sg; 257 pgcount = (sg->offset + sg->length + PAGE_MASK) >> PAGE_SHIFT; 258 259 ++iter->sg_pgoffset; 260 while (iter->sg_pgoffset >= pgcount) { 261 iter->sg_pgoffset -= pgcount; 262 sg = sg_next(sg); 263 --iter->maxents; 264 if (sg == NULL || iter->maxents == 0) 265 break; 266 pgcount = (sg->offset + sg->length + PAGE_MASK) >> PAGE_SHIFT; 267 } 268 iter->sg = sg; 269 } 270 271 static inline int 272 sg_page_count(struct scatterlist *sg) 273 { 274 return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; 275 } 276 277 static inline bool 278 __sg_page_iter_next(struct sg_page_iter *piter) 279 { 280 if (piter->__nents == 0) 281 return (false); 282 if (piter->sg == NULL) 283 return (false); 284 285 piter->sg_pgoffset += piter->__pg_advance; 286 piter->__pg_advance = 1; 287 288 while (piter->sg_pgoffset >= sg_page_count(piter->sg)) { 289 piter->sg_pgoffset -= sg_page_count(piter->sg); 290 piter->sg = sg_next(piter->sg); 291 if (--piter->__nents == 0) 292 return (false); 293 if (piter->sg == NULL) 294 return (false); 295 } 296 return (true); 297 } 298 299 /* 300 * NOTE: pgoffset is really a page index, not a byte offset. 301 */ 302 static inline void 303 _sg_iter_init(struct scatterlist *sgl, struct sg_page_iter *iter, 304 unsigned int nents, unsigned long pgoffset) 305 { 306 if (nents) { 307 /* 308 * Nominal case. Note subtract 1 from starting page index 309 * for initial _sg_iter_next() call. 310 */ 311 iter->sg = sgl; 312 iter->sg_pgoffset = pgoffset - 1; 313 iter->maxents = nents; 314 _sg_iter_next(iter); 315 } else { 316 /* 317 * Degenerate case 318 */ 319 iter->sg = NULL; 320 iter->sg_pgoffset = 0; 321 iter->maxents = 0; 322 } 323 } 324 325 static inline struct page * 326 sg_page_iter_page(struct sg_page_iter *piter) 327 { 328 return nth_page(sg_page(piter->sg), piter->sg_pgoffset); 329 } 330 331 static inline dma_addr_t 332 sg_page_iter_dma_address(struct sg_page_iter *spi) 333 { 334 return spi->sg->dma_address + (spi->sg_pgoffset << PAGE_SHIFT); 335 } 336 337 #define for_each_sg_page(sgl, iter, nents, pgoffset) \ 338 for (_sg_iter_init(sgl, iter, nents, pgoffset); \ 339 (iter)->sg; _sg_iter_next(iter)) 340 341 #define for_each_sg(sglist, sg, sgmax, _itr) \ 342 for (_itr = 0, sg = (sglist); _itr < (sgmax); _itr++, sg = sg_next(sg)) 343 344 /* 345 * 346 * XXX please review these 347 */ 348 size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, 349 const void *buf, size_t buflen, off_t skip); 350 351 static inline size_t 352 sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, 353 const char *buf, size_t buflen) 354 { 355 return (sg_pcopy_from_buffer(sgl, nents, buf, buflen, 0)); 356 } 357 358 size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, 359 void *buf, size_t buflen, off_t skip); 360 361 static inline size_t 362 sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, 363 char *buf, size_t buflen) 364 { 365 366 return (sg_pcopy_to_buffer(sgl, nents, buf, buflen, 0)); 367 } 368 369 static inline bool 370 sg_is_last(struct scatterlist *sg) 371 { 372 return (sg->flags & SG_END); 373 } 374 375 static inline bool 376 sg_is_chain(struct scatterlist *sg) 377 { 378 return (sg->flags & SG_CHAIN); 379 } 380 381 static inline struct scatterlist * 382 sg_chain_ptr(struct scatterlist *sg) 383 { 384 return sg->sl_un.sg; 385 } 386 387 static inline int 388 sg_alloc_table_from_pages(struct sg_table *sgt, 389 struct page **pages, unsigned int n_pages, 390 unsigned long offset, unsigned long size, gfp_t gfp_mask) 391 { 392 kprintf("sg_alloc_table_from_pages: Not implemented\n"); 393 return -EINVAL; 394 } 395 396 #endif /* _LINUX_SCATTERLIST_H_ */ 397