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 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice unmodified, this list of conditions, and the following 14 * disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #ifndef _LINUX_SCATTERLIST_H_ 32 #define _LINUX_SCATTERLIST_H_ 33 34 #include <linux/string.h> 35 #include <linux/types.h> 36 #include <linux/bug.h> 37 #include <linux/mm.h> 38 #include <asm/io.h> 39 40 /* 41 * SG table design. 42 * 43 * If flags bit 0 is set, then the sg field contains a pointer to the next sg 44 * table list. Otherwise the next entry is at sg + 1, can be determined using 45 * the sg_is_chain() function. 46 * 47 * If flags bit 1 is set, then this sg entry is the last element in a list, 48 * can be determined using the sg_is_last() function. 49 * 50 * See sg_next(). 51 * 52 */ 53 54 struct scatterlist { 55 union { 56 struct vm_page *page; 57 struct scatterlist *sg; 58 } sl_un; 59 unsigned long offset; 60 uint32_t length; 61 dma_addr_t dma_address; 62 uint32_t flags; 63 }; 64 65 struct sg_table { 66 struct scatterlist *sgl; /* the list */ 67 unsigned int nents; /* number of mapped entries */ 68 unsigned int orig_nents; /* original size of list */ 69 }; 70 71 struct sg_page_iter { 72 struct scatterlist *sg; 73 unsigned int sg_pgoffset; /* page index */ 74 unsigned int maxents; 75 }; 76 77 78 /* 79 * Maximum number of entries that will be allocated in one piece, if 80 * a list larger than this is required then chaining will be utilized. 81 */ 82 #define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) 83 84 #define sg_dma_address(sg) (sg)->dma_address 85 #define sg_dma_len(sg) (sg)->length 86 #define sg_page(sg) (sg)->sl_un.page 87 #define sg_scatternext(sg) (sg)->sl_un.sg 88 89 #define SG_END 0x01 90 #define SG_CHAIN 0x02 91 92 static inline void 93 sg_set_page(struct scatterlist *sg, struct vm_page *page, unsigned int len, 94 unsigned int offset) 95 { 96 sg_page(sg) = page; 97 sg_dma_len(sg) = len; 98 sg->offset = offset; 99 if (offset > PAGE_SIZE) 100 panic("sg_set_page: Invalid offset %d\n", offset); 101 } 102 103 #if 0 104 static inline void 105 sg_set_buf(struct scatterlist *sg, const void *buf, unsigned int buflen) 106 { 107 sg_set_page(sg, virt_to_page(buf), buflen, 108 ((uintptr_t)buf) & ~PAGE_MASK); 109 } 110 #endif 111 112 static inline void 113 sg_init_table(struct scatterlist *sg, unsigned int nents) 114 { 115 bzero(sg, sizeof(*sg) * nents); 116 sg[nents - 1].flags = SG_END; 117 } 118 119 static inline struct scatterlist * 120 sg_next(struct scatterlist *sg) 121 { 122 if (sg->flags & SG_END) 123 return (NULL); 124 sg++; 125 if (sg->flags & SG_CHAIN) 126 sg = sg_scatternext(sg); 127 return (sg); 128 } 129 130 static inline vm_paddr_t 131 sg_phys(struct scatterlist *sg) 132 { 133 return sg_page(sg)->phys_addr + sg->offset; 134 } 135 136 /** 137 * sg_chain - Chain two sglists together 138 * @prv: First scatterlist 139 * @prv_nents: Number of entries in prv 140 * @sgl: Second scatterlist 141 * 142 * Description: 143 * Links @prv@ and @sgl@ together, to form a longer scatterlist. 144 * 145 **/ 146 static inline void 147 sg_chain(struct scatterlist *prv, unsigned int prv_nents, 148 struct scatterlist *sgl) 149 { 150 /* 151 * offset and length are unused for chain entry. Clear them. 152 */ 153 struct scatterlist *sg = &prv[prv_nents - 1]; 154 155 sg->offset = 0; 156 sg->length = 0; 157 158 /* 159 * Indicate a link pointer, and set the link to the second list. 160 */ 161 sg->flags = SG_CHAIN; 162 sg->sl_un.sg = sgl; 163 } 164 165 /** 166 * sg_mark_end - Mark the end of the scatterlist 167 * @sg: SG entryScatterlist 168 * 169 * Description: 170 * Marks the passed in sg entry as the termination point for the sg 171 * table. A call to sg_next() on this entry will return NULL. 172 * 173 **/ 174 static inline void sg_mark_end(struct scatterlist *sg) 175 { 176 sg->flags = SG_END; 177 } 178 179 /** 180 * __sg_free_table - Free a previously mapped sg table 181 * @table: The sg table header to use 182 * @max_ents: The maximum number of entries per single scatterlist 183 * 184 * Description: 185 * Free an sg table previously allocated and setup with 186 * __sg_alloc_table(). The @max_ents value must be identical to 187 * that previously used with __sg_alloc_table(). 188 * 189 **/ 190 static inline void 191 __sg_free_table(struct sg_table *table, unsigned int max_ents) 192 { 193 struct scatterlist *sgl, *next; 194 195 if (unlikely(!table->sgl)) 196 return; 197 198 sgl = table->sgl; 199 while (table->orig_nents) { 200 unsigned int alloc_size = table->orig_nents; 201 unsigned int sg_size; 202 203 /* 204 * If we have more than max_ents segments left, 205 * then assign 'next' to the sg table after the current one. 206 * sg_size is then one less than alloc size, since the last 207 * element is the chain pointer. 208 */ 209 if (alloc_size > max_ents) { 210 next = sgl[max_ents - 1].sl_un.sg; 211 alloc_size = max_ents; 212 sg_size = alloc_size - 1; 213 } else { 214 sg_size = alloc_size; 215 next = NULL; 216 } 217 218 table->orig_nents -= sg_size; 219 kfree(sgl); 220 sgl = next; 221 } 222 223 table->sgl = NULL; 224 } 225 226 /** 227 * sg_free_table - Free a previously allocated sg table 228 * @table: The mapped sg table header 229 * 230 **/ 231 static inline void 232 sg_free_table(struct sg_table *table) 233 { 234 __sg_free_table(table, SG_MAX_SINGLE_ALLOC); 235 } 236 237 /** 238 * __sg_alloc_table - Allocate and initialize an sg table with given allocator 239 * @table: The sg table header to use 240 * @nents: Number of entries in sg list 241 * @max_ents: The maximum number of entries the allocator returns per call 242 * @gfp_mask: GFP allocation mask 243 * 244 * Description: 245 * This function returns a @table @nents long. The allocator is 246 * defined to return scatterlist chunks of maximum size @max_ents. 247 * Thus if @nents is bigger than @max_ents, the scatterlists will be 248 * chained in units of @max_ents. 249 * 250 * Notes: 251 * If this function returns non-0 (eg failure), the caller must call 252 * __sg_free_table() to cleanup any leftover allocations. 253 * 254 **/ 255 static inline int 256 __sg_alloc_table(struct sg_table *table, unsigned int nents, 257 unsigned int max_ents, gfp_t gfp_mask) 258 { 259 struct scatterlist *sg, *prv; 260 unsigned int left; 261 262 memset(table, 0, sizeof(*table)); 263 264 if (nents == 0) 265 return -EINVAL; 266 left = nents; 267 prv = NULL; 268 do { 269 unsigned int sg_size, alloc_size = left; 270 271 if (alloc_size > max_ents) { 272 alloc_size = max_ents; 273 sg_size = alloc_size - 1; 274 } else 275 sg_size = alloc_size; 276 277 left -= sg_size; 278 279 sg = kmalloc(alloc_size * sizeof(struct scatterlist), M_DRM, gfp_mask); 280 if (unlikely(!sg)) { 281 /* 282 * Adjust entry count to reflect that the last 283 * entry of the previous table won't be used for 284 * linkage. Without this, sg_kfree() may get 285 * confused. 286 */ 287 if (prv) 288 table->nents = ++table->orig_nents; 289 290 return -ENOMEM; 291 } 292 293 sg_init_table(sg, alloc_size); 294 table->nents = table->orig_nents += sg_size; 295 296 /* 297 * If this is the first mapping, assign the sg table header. 298 * If this is not the first mapping, chain previous part. 299 */ 300 if (prv) 301 sg_chain(prv, max_ents, sg); 302 else 303 table->sgl = sg; 304 305 /* 306 * If no more entries after this one, mark the end 307 */ 308 if (!left) 309 sg_mark_end(&sg[sg_size - 1]); 310 311 prv = sg; 312 } while (left); 313 314 return 0; 315 } 316 317 /** 318 * sg_alloc_table - Allocate and initialize an sg table 319 * @table: The sg table header to use 320 * @nents: Number of entries in sg list 321 * @gfp_mask: GFP allocation mask 322 * 323 * Description: 324 * Allocate and initialize an sg table. If @nents@ is larger than 325 * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. 326 * 327 **/ 328 329 static inline int 330 sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) 331 { 332 int ret; 333 334 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, 335 gfp_mask); 336 if (unlikely(ret)) 337 __sg_free_table(table, SG_MAX_SINGLE_ALLOC); 338 339 return ret; 340 } 341 342 /* 343 * Iterate pages in sg list. 344 */ 345 static inline void 346 _sg_iter_next(struct sg_page_iter *iter) 347 { 348 struct scatterlist *sg; 349 unsigned int pgcount; 350 351 sg = iter->sg; 352 pgcount = (sg->offset + sg->length + PAGE_MASK) >> PAGE_SHIFT; 353 354 ++iter->sg_pgoffset; 355 while (iter->sg_pgoffset >= pgcount) { 356 iter->sg_pgoffset -= pgcount; 357 sg = sg_next(sg); 358 --iter->maxents; 359 if (sg == NULL || iter->maxents == 0) 360 break; 361 pgcount = (sg->offset + sg->length + PAGE_MASK) >> PAGE_SHIFT; 362 } 363 iter->sg = sg; 364 } 365 366 /* 367 * NOTE: pgoffset is really a page index, not a byte offset. 368 */ 369 static inline void 370 _sg_iter_init(struct scatterlist *sgl, struct sg_page_iter *iter, 371 unsigned int nents, unsigned long pgoffset) 372 { 373 if (nents) { 374 /* 375 * Nominal case. Note subtract 1 from starting page index 376 * for initial _sg_iter_next() call. 377 */ 378 iter->sg = sgl; 379 iter->sg_pgoffset = pgoffset - 1; 380 iter->maxents = nents; 381 _sg_iter_next(iter); 382 } else { 383 /* 384 * Degenerate case 385 */ 386 iter->sg = NULL; 387 iter->sg_pgoffset = 0; 388 iter->maxents = 0; 389 } 390 } 391 392 static inline struct vm_page * 393 sg_page_iter_page(struct sg_page_iter *piter) 394 { 395 return nth_page(sg_page(piter->sg), piter->sg_pgoffset); 396 } 397 398 static inline dma_addr_t 399 sg_page_iter_dma_address(struct sg_page_iter *spi) 400 { 401 return spi->sg->dma_address + (spi->sg_pgoffset << PAGE_SHIFT); 402 } 403 404 #define for_each_sg_page(sgl, iter, nents, pgoffset) \ 405 for (_sg_iter_init(sgl, iter, nents, pgoffset); \ 406 (iter)->sg; _sg_iter_next(iter)) 407 408 #define for_each_sg(sglist, sg, sgmax, _itr) \ 409 for (_itr = 0, sg = (sglist); _itr < (sgmax); _itr++, sg = sg_next(sg)) 410 411 #endif /* _LINUX_SCATTERLIST_H_ */ 412