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 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/highmem.h> 37 #include <linux/string.h> 38 #include <linux/types.h> 39 #include <linux/bug.h> 40 #include <linux/mm.h> 41 #include <asm/io.h> 42 43 /* 44 * SG table design. 45 * 46 * If flags bit 0 is set, then the sg field contains a pointer to the next sg 47 * table list. Otherwise the next entry is at sg + 1, can be determined using 48 * the sg_is_chain() function. 49 * 50 * If flags bit 1 is set, then this sg entry is the last element in a list, 51 * can be determined using the sg_is_last() function. 52 * 53 * See sg_next(). 54 * 55 */ 56 57 struct scatterlist { 58 union { 59 struct vm_page *page; 60 struct scatterlist *sg; 61 } sl_un; 62 unsigned long offset; 63 uint32_t length; 64 dma_addr_t dma_address; 65 uint32_t flags; 66 }; 67 68 struct sg_table { 69 struct scatterlist *sgl; /* the list */ 70 unsigned int nents; /* number of mapped entries */ 71 unsigned int orig_nents; /* original size of list */ 72 }; 73 74 struct sg_page_iter { 75 struct scatterlist *sg; 76 unsigned int sg_pgoffset; /* page index */ 77 unsigned int maxents; 78 unsigned int __nents; 79 int __pg_advance; 80 }; 81 82 83 /* 84 * Maximum number of entries that will be allocated in one piece, if 85 * a list larger than this is required then chaining will be utilized. 86 */ 87 #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) 88 89 #define sg_dma_address(sg) (sg)->dma_address 90 #define sg_dma_len(sg) (sg)->length 91 #define sg_page(sg) (sg)->sl_un.page 92 #define sg_scatternext(sg) (sg)->sl_un.sg 93 94 #define SG_END 0x01 95 #define SG_CHAIN 0x02 96 97 static inline void 98 sg_set_page(struct scatterlist *sg, struct vm_page *page, unsigned int len, 99 unsigned int offset) 100 { 101 sg_page(sg) = page; 102 sg_dma_len(sg) = len; 103 sg->offset = offset; 104 if (offset > PAGE_SIZE) 105 panic("sg_set_page: Invalid offset %d\n", offset); 106 } 107 108 static inline void 109 sg_init_table(struct scatterlist *sg, unsigned int nents) 110 { 111 bzero(sg, sizeof(*sg) * nents); 112 sg[nents - 1].flags = SG_END; 113 } 114 115 static inline struct scatterlist * 116 sg_next(struct scatterlist *sg) 117 { 118 if (sg->flags & SG_END) 119 return (NULL); 120 sg++; 121 if (sg->flags & SG_CHAIN) 122 sg = sg_scatternext(sg); 123 return (sg); 124 } 125 126 static inline vm_paddr_t 127 sg_phys(struct scatterlist *sg) 128 { 129 return sg_page(sg)->phys_addr + sg->offset; 130 } 131 132 /** 133 * sg_chain - Chain two sglists together 134 * @prv: First scatterlist 135 * @prv_nents: Number of entries in prv 136 * @sgl: Second scatterlist 137 * 138 * Description: 139 * Links @prv@ and @sgl@ together, to form a longer scatterlist. 140 * 141 **/ 142 static inline void 143 sg_chain(struct scatterlist *prv, unsigned int prv_nents, 144 struct scatterlist *sgl) 145 { 146 /* 147 * offset and length are unused for chain entry. Clear them. 148 */ 149 struct scatterlist *sg = &prv[prv_nents - 1]; 150 151 sg->offset = 0; 152 sg->length = 0; 153 154 /* 155 * Indicate a link pointer, and set the link to the second list. 156 */ 157 sg->flags = SG_CHAIN; 158 sg->sl_un.sg = sgl; 159 } 160 161 /** 162 * sg_mark_end - Mark the end of the scatterlist 163 * @sg: SG entryScatterlist 164 * 165 * Description: 166 * Marks the passed in sg entry as the termination point for the sg 167 * table. A call to sg_next() on this entry will return NULL. 168 * 169 **/ 170 static inline void sg_mark_end(struct scatterlist *sg) 171 { 172 sg->flags = SG_END; 173 } 174 175 /** 176 * __sg_free_table - Free a previously mapped sg table 177 * @table: The sg table header to use 178 * @max_ents: The maximum number of entries per single scatterlist 179 * 180 * Description: 181 * Free an sg table previously allocated and setup with 182 * __sg_alloc_table(). The @max_ents value must be identical to 183 * that previously used with __sg_alloc_table(). 184 * 185 **/ 186 static inline void 187 __sg_free_table(struct sg_table *table, unsigned int max_ents) 188 { 189 struct scatterlist *sgl, *next; 190 191 if (unlikely(!table->sgl)) 192 return; 193 194 sgl = table->sgl; 195 while (table->orig_nents) { 196 unsigned int alloc_size = table->orig_nents; 197 unsigned int sg_size; 198 199 /* 200 * If we have more than max_ents segments left, 201 * then assign 'next' to the sg table after the current one. 202 * sg_size is then one less than alloc size, since the last 203 * element is the chain pointer. 204 */ 205 if (alloc_size > max_ents) { 206 next = sgl[max_ents - 1].sl_un.sg; 207 alloc_size = max_ents; 208 sg_size = alloc_size - 1; 209 } else { 210 sg_size = alloc_size; 211 next = NULL; 212 } 213 214 table->orig_nents -= sg_size; 215 kfree(sgl); 216 sgl = next; 217 } 218 219 table->sgl = NULL; 220 } 221 222 /** 223 * sg_free_table - Free a previously allocated sg table 224 * @table: The mapped sg table header 225 * 226 **/ 227 static inline void 228 sg_free_table(struct sg_table *table) 229 { 230 __sg_free_table(table, SG_MAX_SINGLE_ALLOC); 231 } 232 233 /** 234 * __sg_alloc_table - Allocate and initialize an sg table with given allocator 235 * @table: The sg table header to use 236 * @nents: Number of entries in sg list 237 * @max_ents: The maximum number of entries the allocator returns per call 238 * @gfp_mask: GFP allocation mask 239 * 240 * Description: 241 * This function returns a @table @nents long. The allocator is 242 * defined to return scatterlist chunks of maximum size @max_ents. 243 * Thus if @nents is bigger than @max_ents, the scatterlists will be 244 * chained in units of @max_ents. 245 * 246 * Notes: 247 * If this function returns non-0 (eg failure), the caller must call 248 * __sg_free_table() to cleanup any leftover allocations. 249 * 250 **/ 251 static inline int 252 __sg_alloc_table(struct sg_table *table, unsigned int nents, 253 unsigned int max_ents, gfp_t gfp_mask) 254 { 255 struct scatterlist *sg, *prv; 256 unsigned int left; 257 258 memset(table, 0, sizeof(*table)); 259 260 if (nents == 0) 261 return -EINVAL; 262 left = nents; 263 prv = NULL; 264 do { 265 unsigned int sg_size, alloc_size = left; 266 267 if (alloc_size > max_ents) { 268 alloc_size = max_ents; 269 sg_size = alloc_size - 1; 270 } else 271 sg_size = alloc_size; 272 273 left -= sg_size; 274 275 sg = kmalloc(alloc_size * sizeof(struct scatterlist), M_DRM, gfp_mask); 276 if (unlikely(!sg)) { 277 /* 278 * Adjust entry count to reflect that the last 279 * entry of the previous table won't be used for 280 * linkage. Without this, sg_kfree() may get 281 * confused. 282 */ 283 if (prv) 284 table->nents = ++table->orig_nents; 285 286 return -ENOMEM; 287 } 288 289 sg_init_table(sg, alloc_size); 290 table->nents = table->orig_nents += sg_size; 291 292 /* 293 * If this is the first mapping, assign the sg table header. 294 * If this is not the first mapping, chain previous part. 295 */ 296 if (prv) 297 sg_chain(prv, max_ents, sg); 298 else 299 table->sgl = sg; 300 301 /* 302 * If no more entries after this one, mark the end 303 */ 304 if (!left) 305 sg_mark_end(&sg[sg_size - 1]); 306 307 prv = sg; 308 } while (left); 309 310 return 0; 311 } 312 313 /** 314 * sg_alloc_table - Allocate and initialize an sg table 315 * @table: The sg table header to use 316 * @nents: Number of entries in sg list 317 * @gfp_mask: GFP allocation mask 318 * 319 * Description: 320 * Allocate and initialize an sg table. If @nents@ is larger than 321 * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. 322 * 323 **/ 324 325 static inline int 326 sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) 327 { 328 int ret; 329 330 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, 331 gfp_mask); 332 if (unlikely(ret)) 333 __sg_free_table(table, SG_MAX_SINGLE_ALLOC); 334 335 return ret; 336 } 337 338 static inline int 339 sg_nents(struct scatterlist *sg) 340 { 341 int nents; 342 for (nents = 0; sg; sg = sg_next(sg)) 343 nents++; 344 return nents; 345 } 346 347 static inline void 348 __sg_page_iter_start(struct sg_page_iter *piter, 349 struct scatterlist *sglist, unsigned int nents, 350 unsigned long pgoffset) 351 { 352 piter->__pg_advance = 0; 353 piter->__nents = nents; 354 355 piter->sg = sglist; 356 piter->sg_pgoffset = pgoffset; 357 } 358 359 /* 360 * Iterate pages in sg list. 361 */ 362 static inline void 363 _sg_iter_next(struct sg_page_iter *iter) 364 { 365 struct scatterlist *sg; 366 unsigned int pgcount; 367 368 sg = iter->sg; 369 pgcount = (sg->offset + sg->length + PAGE_MASK) >> PAGE_SHIFT; 370 371 ++iter->sg_pgoffset; 372 while (iter->sg_pgoffset >= pgcount) { 373 iter->sg_pgoffset -= pgcount; 374 sg = sg_next(sg); 375 --iter->maxents; 376 if (sg == NULL || iter->maxents == 0) 377 break; 378 pgcount = (sg->offset + sg->length + PAGE_MASK) >> PAGE_SHIFT; 379 } 380 iter->sg = sg; 381 } 382 383 static inline int 384 sg_page_count(struct scatterlist *sg) 385 { 386 return PAGE_ALIGN(sg->offset + sg->length) >> PAGE_SHIFT; 387 } 388 389 static inline bool 390 __sg_page_iter_next(struct sg_page_iter *piter) 391 { 392 if (piter->__nents == 0) 393 return (false); 394 if (piter->sg == NULL) 395 return (false); 396 397 piter->sg_pgoffset += piter->__pg_advance; 398 piter->__pg_advance = 1; 399 400 while (piter->sg_pgoffset >= sg_page_count(piter->sg)) { 401 piter->sg_pgoffset -= sg_page_count(piter->sg); 402 piter->sg = sg_next(piter->sg); 403 if (--piter->__nents == 0) 404 return (false); 405 if (piter->sg == NULL) 406 return (false); 407 } 408 return (true); 409 } 410 411 /* 412 * NOTE: pgoffset is really a page index, not a byte offset. 413 */ 414 static inline void 415 _sg_iter_init(struct scatterlist *sgl, struct sg_page_iter *iter, 416 unsigned int nents, unsigned long pgoffset) 417 { 418 if (nents) { 419 /* 420 * Nominal case. Note subtract 1 from starting page index 421 * for initial _sg_iter_next() call. 422 */ 423 iter->sg = sgl; 424 iter->sg_pgoffset = pgoffset - 1; 425 iter->maxents = nents; 426 _sg_iter_next(iter); 427 } else { 428 /* 429 * Degenerate case 430 */ 431 iter->sg = NULL; 432 iter->sg_pgoffset = 0; 433 iter->maxents = 0; 434 } 435 } 436 437 static inline struct vm_page * 438 sg_page_iter_page(struct sg_page_iter *piter) 439 { 440 return nth_page(sg_page(piter->sg), piter->sg_pgoffset); 441 } 442 443 static inline dma_addr_t 444 sg_page_iter_dma_address(struct sg_page_iter *spi) 445 { 446 return spi->sg->dma_address + (spi->sg_pgoffset << PAGE_SHIFT); 447 } 448 449 #define for_each_sg_page(sgl, iter, nents, pgoffset) \ 450 for (_sg_iter_init(sgl, iter, nents, pgoffset); \ 451 (iter)->sg; _sg_iter_next(iter)) 452 453 #define for_each_sg(sglist, sg, sgmax, _itr) \ 454 for (_itr = 0, sg = (sglist); _itr < (sgmax); _itr++, sg = sg_next(sg)) 455 456 /* 457 * 458 * XXX please review these 459 */ 460 static inline size_t 461 sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, 462 const void *buf, size_t buflen, off_t skip) 463 { 464 off_t off; 465 int len, curlen, curoff; 466 struct sg_page_iter iter; 467 struct scatterlist *sg; 468 struct vm_page *page; 469 char *vaddr; 470 471 off = 0; 472 for_each_sg_page(sgl, &iter, nents, 0) { 473 sg = iter.sg; 474 curlen = sg->length; 475 curoff = sg->offset; 476 if (skip && curlen >= skip) { 477 skip -= curlen; 478 continue; 479 } 480 if (skip) { 481 curlen -= skip; 482 curoff += skip; 483 skip = 0; 484 } 485 len = min(curlen, buflen - off); 486 page = sg_page_iter_page(&iter); 487 vaddr = (char *)kmap(page) + sg->offset; 488 memcpy(vaddr, (const char *)buf + off, len); 489 off += len; 490 kunmap(page); 491 } 492 493 return (off); 494 } 495 496 497 static inline size_t 498 sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, 499 const char *buf, size_t buflen) 500 { 501 return (sg_pcopy_from_buffer(sgl, nents, buf, buflen, 0)); 502 } 503 504 static inline size_t 505 sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, 506 void *buf, size_t buflen, off_t skip) 507 { 508 off_t off; 509 int len, curlen, curoff; 510 struct sg_page_iter iter; 511 struct scatterlist *sg; 512 struct vm_page *page; 513 char *vaddr; 514 515 off = 0; 516 for_each_sg_page(sgl, &iter, nents, 0) { 517 sg = iter.sg; 518 curlen = sg->length; 519 curoff = sg->offset; 520 if (skip && curlen >= skip) { 521 skip -= curlen; 522 continue; 523 } 524 if (skip) { 525 curlen -= skip; 526 curoff += skip; 527 skip = 0; 528 } 529 len = min(curlen, buflen - off); 530 page = sg_page_iter_page(&iter); 531 vaddr = (char *)kmap(page) + sg->offset; 532 memcpy((char *)buf + off, vaddr, len); 533 off += len; 534 kunmap(page); 535 } 536 537 return (off); 538 } 539 540 static inline size_t 541 sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, 542 char *buf, size_t buflen) 543 { 544 545 return (sg_pcopy_to_buffer(sgl, nents, buf, buflen, 0)); 546 } 547 548 static inline bool 549 sg_is_last(struct scatterlist *sg) 550 { 551 return (sg->flags & SG_END); 552 } 553 554 static inline bool 555 sg_is_chain(struct scatterlist *sg) 556 { 557 return (sg->flags & SG_CHAIN); 558 } 559 560 static inline struct scatterlist * 561 sg_chain_ptr(struct scatterlist *sg) 562 { 563 return sg->sl_un.sg; 564 } 565 566 #endif /* _LINUX_SCATTERLIST_H_ */ 567