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 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice unmodified, this list of conditions, and the following 13 * disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 */ 29 30#ifndef _LINUX_SCATTERLIST_H_ 31#define _LINUX_SCATTERLIST_H_ 32 33#include <linux/page.h> 34#include <linux/slab.h> 35 36/* 37 * SG table design. 38 * 39 * If flags bit 0 is set, then the sg field contains a pointer to the next sg 40 * table list. Otherwise the next entry is at sg + 1, can be determined using 41 * the sg_is_chain() function. 42 * 43 * If flags bit 1 is set, then this sg entry is the last element in a list, 44 * can be determined using the sg_is_last() function. 45 * 46 * See sg_next(). 47 * 48 */ 49 50struct scatterlist { 51 union { 52 struct page *page; 53 struct scatterlist *sg; 54 } sl_un; 55 dma_addr_t address; 56 unsigned long offset; 57 uint32_t length; 58 uint32_t flags; 59}; 60 61struct sg_table { 62 struct scatterlist *sgl; /* the list */ 63 unsigned int nents; /* number of mapped entries */ 64 unsigned int orig_nents; /* original size of list */ 65}; 66 67/* 68 * Maximum number of entries that will be allocated in one piece, if 69 * a list larger than this is required then chaining will be utilized. 70 */ 71#define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) 72 73#define sg_dma_address(sg) (sg)->address 74#define sg_dma_len(sg) (sg)->length 75#define sg_page(sg) (sg)->sl_un.page 76#define sg_scatternext(sg) (sg)->sl_un.sg 77 78#define SG_END 0x01 79#define SG_CHAIN 0x02 80 81static inline void 82sg_set_page(struct scatterlist *sg, struct page *page, unsigned int len, 83 unsigned int offset) 84{ 85 sg_page(sg) = page; 86 sg_dma_len(sg) = len; 87 sg->offset = offset; 88 if (offset > PAGE_SIZE) 89 panic("sg_set_page: Invalid offset %d\n", offset); 90} 91 92static inline void 93sg_set_buf(struct scatterlist *sg, const void *buf, unsigned int buflen) 94{ 95 sg_set_page(sg, virt_to_page(buf), buflen, 96 ((uintptr_t)buf) & ~PAGE_MASK); 97} 98 99static inline void 100sg_init_table(struct scatterlist *sg, unsigned int nents) 101{ 102 bzero(sg, sizeof(*sg) * nents); 103 sg[nents - 1].flags = SG_END; 104} 105 106static inline struct scatterlist * 107sg_next(struct scatterlist *sg) 108{ 109 if (sg->flags & SG_END) 110 return (NULL); 111 sg++; 112 if (sg->flags & SG_CHAIN) 113 sg = sg_scatternext(sg); 114 return (sg); 115} 116 117static inline vm_paddr_t 118sg_phys(struct scatterlist *sg) 119{ 120 return sg_page(sg)->phys_addr + sg->offset; 121} 122 123/** 124 * sg_chain - Chain two sglists together 125 * @prv: First scatterlist 126 * @prv_nents: Number of entries in prv 127 * @sgl: Second scatterlist 128 * 129 * Description: 130 * Links @prv@ and @sgl@ together, to form a longer scatterlist. 131 * 132 **/ 133static inline void 134sg_chain(struct scatterlist *prv, unsigned int prv_nents, 135 struct scatterlist *sgl) 136{ 137/* 138 * offset and length are unused for chain entry. Clear them. 139 */ 140 struct scatterlist *sg = &prv[prv_nents - 1]; 141 142 sg->offset = 0; 143 sg->length = 0; 144 145 /* 146 * Indicate a link pointer, and set the link to the second list. 147 */ 148 sg->flags = SG_CHAIN; 149 sg->sl_un.sg = sgl; 150} 151 152/** 153 * sg_mark_end - Mark the end of the scatterlist 154 * @sg: SG entryScatterlist 155 * 156 * Description: 157 * Marks the passed in sg entry as the termination point for the sg 158 * table. A call to sg_next() on this entry will return NULL. 159 * 160 **/ 161static inline void sg_mark_end(struct scatterlist *sg) 162{ 163 sg->flags = SG_END; 164} 165 166/** 167 * __sg_free_table - Free a previously mapped sg table 168 * @table: The sg table header to use 169 * @max_ents: The maximum number of entries per single scatterlist 170 * 171 * Description: 172 * Free an sg table previously allocated and setup with 173 * __sg_alloc_table(). The @max_ents value must be identical to 174 * that previously used with __sg_alloc_table(). 175 * 176 **/ 177static inline void 178__sg_free_table(struct sg_table *table, unsigned int max_ents) 179{ 180 struct scatterlist *sgl, *next; 181 182 if (unlikely(!table->sgl)) 183 return; 184 185 sgl = table->sgl; 186 while (table->orig_nents) { 187 unsigned int alloc_size = table->orig_nents; 188 unsigned int sg_size; 189 190 /* 191 * If we have more than max_ents segments left, 192 * then assign 'next' to the sg table after the current one. 193 * sg_size is then one less than alloc size, since the last 194 * element is the chain pointer. 195 */ 196 if (alloc_size > max_ents) { 197 next = sgl[max_ents - 1].sl_un.sg; 198 alloc_size = max_ents; 199 sg_size = alloc_size - 1; 200 } else { 201 sg_size = alloc_size; 202 next = NULL; 203 } 204 205 table->orig_nents -= sg_size; 206 kfree(sgl); 207 sgl = next; 208 } 209 210 table->sgl = NULL; 211} 212 213/** 214 * sg_free_table - Free a previously allocated sg table 215 * @table: The mapped sg table header 216 * 217 **/ 218static inline void 219sg_free_table(struct sg_table *table) 220{ 221 __sg_free_table(table, SG_MAX_SINGLE_ALLOC); 222} 223 224/** 225 * __sg_alloc_table - Allocate and initialize an sg table with given allocator 226 * @table: The sg table header to use 227 * @nents: Number of entries in sg list 228 * @max_ents: The maximum number of entries the allocator returns per call 229 * @gfp_mask: GFP allocation mask 230 * 231 * Description: 232 * This function returns a @table @nents long. The allocator is 233 * defined to return scatterlist chunks of maximum size @max_ents. 234 * Thus if @nents is bigger than @max_ents, the scatterlists will be 235 * chained in units of @max_ents. 236 * 237 * Notes: 238 * If this function returns non-0 (eg failure), the caller must call 239 * __sg_free_table() to cleanup any leftover allocations. 240 * 241 **/ 242static inline int 243__sg_alloc_table(struct sg_table *table, unsigned int nents, 244 unsigned int max_ents, gfp_t gfp_mask) 245{ 246 struct scatterlist *sg, *prv; 247 unsigned int left; 248 249 memset(table, 0, sizeof(*table)); 250 251 if (nents == 0) 252 return -EINVAL; 253 left = nents; 254 prv = NULL; 255 do { 256 unsigned int sg_size, alloc_size = left; 257 258 if (alloc_size > max_ents) { 259 alloc_size = max_ents; 260 sg_size = alloc_size - 1; 261 } else 262 sg_size = alloc_size; 263 264 left -= sg_size; 265 266 sg = kmalloc(alloc_size * sizeof(struct scatterlist), gfp_mask); 267 if (unlikely(!sg)) { 268 /* 269 * Adjust entry count to reflect that the last 270 * entry of the previous table won't be used for 271 * linkage. Without this, sg_kfree() may get 272 * confused. 273 */ 274 if (prv) 275 table->nents = ++table->orig_nents; 276 277 return -ENOMEM; 278 } 279 280 sg_init_table(sg, alloc_size); 281 table->nents = table->orig_nents += sg_size; 282 283 /* 284 * If this is the first mapping, assign the sg table header. 285 * If this is not the first mapping, chain previous part. 286 */ 287 if (prv) 288 sg_chain(prv, max_ents, sg); 289 else 290 table->sgl = sg; 291 292 /* 293 * If no more entries after this one, mark the end 294 */ 295 if (!left) 296 sg_mark_end(&sg[sg_size - 1]); 297 298 prv = sg; 299 } while (left); 300 301 return 0; 302} 303 304/** 305 * sg_alloc_table - Allocate and initialize an sg table 306 * @table: The sg table header to use 307 * @nents: Number of entries in sg list 308 * @gfp_mask: GFP allocation mask 309 * 310 * Description: 311 * Allocate and initialize an sg table. If @nents@ is larger than 312 * SG_MAX_SINGLE_ALLOC a chained sg table will be setup. 313 * 314 **/ 315 316static inline int 317sg_alloc_table(struct sg_table *table, unsigned int nents, gfp_t gfp_mask) 318{ 319 int ret; 320 321 ret = __sg_alloc_table(table, nents, SG_MAX_SINGLE_ALLOC, 322 gfp_mask); 323 if (unlikely(ret)) 324 __sg_free_table(table, SG_MAX_SINGLE_ALLOC); 325 326 return ret; 327} 328 329#define for_each_sg(sglist, sg, sgmax, _itr) \ 330 for (_itr = 0, sg = (sglist); _itr < (sgmax); _itr++, sg = sg_next(sg)) 331 332#endif /* _LINUX_SCATTERLIST_H_ */ 333