1 /* 2 * xor offload engine api 3 * 4 * Copyright © 2006, Intel Corporation. 5 * 6 * Dan Williams <dan.j.williams@intel.com> 7 * 8 * with architecture considerations by: 9 * Neil Brown <neilb@suse.de> 10 * Jeff Garzik <jeff@garzik.org> 11 * 12 * This program is free software; you can redistribute it and/or modify it 13 * under the terms and conditions of the GNU General Public License, 14 * version 2, as published by the Free Software Foundation. 15 * 16 * This program is distributed in the hope it will be useful, but WITHOUT 17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 18 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 19 * more details. 20 * 21 * You should have received a copy of the GNU General Public License along with 22 * this program; if not, write to the Free Software Foundation, Inc., 23 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. 24 * 25 */ 26 #include <linux/kernel.h> 27 #include <linux/interrupt.h> 28 #include <linux/mm.h> 29 #include <linux/dma-mapping.h> 30 #include <linux/raid/xor.h> 31 #include <linux/async_tx.h> 32 33 /* do_async_xor - dma map the pages and perform the xor with an engine */ 34 static __async_inline struct dma_async_tx_descriptor * 35 do_async_xor(struct dma_chan *chan, struct page *dest, struct page **src_list, 36 unsigned int offset, int src_cnt, size_t len, dma_addr_t *dma_src, 37 struct async_submit_ctl *submit) 38 { 39 struct dma_device *dma = chan->device; 40 struct dma_async_tx_descriptor *tx = NULL; 41 int src_off = 0; 42 int i; 43 dma_async_tx_callback cb_fn_orig = submit->cb_fn; 44 void *cb_param_orig = submit->cb_param; 45 enum async_tx_flags flags_orig = submit->flags; 46 enum dma_ctrl_flags dma_flags; 47 int xor_src_cnt = 0; 48 dma_addr_t dma_dest; 49 50 /* map the dest bidrectional in case it is re-used as a source */ 51 dma_dest = dma_map_page(dma->dev, dest, offset, len, DMA_BIDIRECTIONAL); 52 for (i = 0; i < src_cnt; i++) { 53 /* only map the dest once */ 54 if (!src_list[i]) 55 continue; 56 if (unlikely(src_list[i] == dest)) { 57 dma_src[xor_src_cnt++] = dma_dest; 58 continue; 59 } 60 dma_src[xor_src_cnt++] = dma_map_page(dma->dev, src_list[i], offset, 61 len, DMA_TO_DEVICE); 62 } 63 src_cnt = xor_src_cnt; 64 65 while (src_cnt) { 66 submit->flags = flags_orig; 67 dma_flags = 0; 68 xor_src_cnt = min(src_cnt, (int)dma->max_xor); 69 /* if we are submitting additional xors, leave the chain open, 70 * clear the callback parameters, and leave the destination 71 * buffer mapped 72 */ 73 if (src_cnt > xor_src_cnt) { 74 submit->flags &= ~ASYNC_TX_ACK; 75 submit->flags |= ASYNC_TX_FENCE; 76 dma_flags = DMA_COMPL_SKIP_DEST_UNMAP; 77 submit->cb_fn = NULL; 78 submit->cb_param = NULL; 79 } else { 80 submit->cb_fn = cb_fn_orig; 81 submit->cb_param = cb_param_orig; 82 } 83 if (submit->cb_fn) 84 dma_flags |= DMA_PREP_INTERRUPT; 85 if (submit->flags & ASYNC_TX_FENCE) 86 dma_flags |= DMA_PREP_FENCE; 87 /* Since we have clobbered the src_list we are committed 88 * to doing this asynchronously. Drivers force forward progress 89 * in case they can not provide a descriptor 90 */ 91 tx = dma->device_prep_dma_xor(chan, dma_dest, &dma_src[src_off], 92 xor_src_cnt, len, dma_flags); 93 94 if (unlikely(!tx)) 95 async_tx_quiesce(&submit->depend_tx); 96 97 /* spin wait for the preceding transactions to complete */ 98 while (unlikely(!tx)) { 99 dma_async_issue_pending(chan); 100 tx = dma->device_prep_dma_xor(chan, dma_dest, 101 &dma_src[src_off], 102 xor_src_cnt, len, 103 dma_flags); 104 } 105 106 async_tx_submit(chan, tx, submit); 107 submit->depend_tx = tx; 108 109 if (src_cnt > xor_src_cnt) { 110 /* drop completed sources */ 111 src_cnt -= xor_src_cnt; 112 src_off += xor_src_cnt; 113 114 /* use the intermediate result a source */ 115 dma_src[--src_off] = dma_dest; 116 src_cnt++; 117 } else 118 break; 119 } 120 121 return tx; 122 } 123 124 static void 125 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset, 126 int src_cnt, size_t len, struct async_submit_ctl *submit) 127 { 128 int i; 129 int xor_src_cnt = 0; 130 int src_off = 0; 131 void *dest_buf; 132 void **srcs; 133 134 if (submit->scribble) 135 srcs = submit->scribble; 136 else 137 srcs = (void **) src_list; 138 139 /* convert to buffer pointers */ 140 for (i = 0; i < src_cnt; i++) 141 if (src_list[i]) 142 srcs[xor_src_cnt++] = page_address(src_list[i]) + offset; 143 src_cnt = xor_src_cnt; 144 /* set destination address */ 145 dest_buf = page_address(dest) + offset; 146 147 if (submit->flags & ASYNC_TX_XOR_ZERO_DST) 148 memset(dest_buf, 0, len); 149 150 while (src_cnt > 0) { 151 /* process up to 'MAX_XOR_BLOCKS' sources */ 152 xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS); 153 xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]); 154 155 /* drop completed sources */ 156 src_cnt -= xor_src_cnt; 157 src_off += xor_src_cnt; 158 } 159 160 async_tx_sync_epilog(submit); 161 } 162 163 /** 164 * async_xor - attempt to xor a set of blocks with a dma engine. 165 * @dest: destination page 166 * @src_list: array of source pages 167 * @offset: common src/dst offset to start transaction 168 * @src_cnt: number of source pages 169 * @len: length in bytes 170 * @submit: submission / completion modifiers 171 * 172 * honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST 173 * 174 * xor_blocks always uses the dest as a source so the 175 * ASYNC_TX_XOR_ZERO_DST flag must be set to not include dest data in 176 * the calculation. The assumption with dma eninges is that they only 177 * use the destination buffer as a source when it is explicity specified 178 * in the source list. 179 * 180 * src_list note: if the dest is also a source it must be at index zero. 181 * The contents of this array will be overwritten if a scribble region 182 * is not specified. 183 */ 184 struct dma_async_tx_descriptor * 185 async_xor(struct page *dest, struct page **src_list, unsigned int offset, 186 int src_cnt, size_t len, struct async_submit_ctl *submit) 187 { 188 struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR, 189 &dest, 1, src_list, 190 src_cnt, len); 191 dma_addr_t *dma_src = NULL; 192 193 BUG_ON(src_cnt <= 1); 194 195 if (submit->scribble) 196 dma_src = submit->scribble; 197 else if (sizeof(dma_addr_t) <= sizeof(struct page *)) 198 dma_src = (dma_addr_t *) src_list; 199 200 if (dma_src && chan && is_dma_xor_aligned(chan->device, offset, 0, len)) { 201 /* run the xor asynchronously */ 202 pr_debug("%s (async): len: %zu\n", __func__, len); 203 204 return do_async_xor(chan, dest, src_list, offset, src_cnt, len, 205 dma_src, submit); 206 } else { 207 /* run the xor synchronously */ 208 pr_debug("%s (sync): len: %zu\n", __func__, len); 209 WARN_ONCE(chan, "%s: no space for dma address conversion\n", 210 __func__); 211 212 /* in the sync case the dest is an implied source 213 * (assumes the dest is the first source) 214 */ 215 if (submit->flags & ASYNC_TX_XOR_DROP_DST) { 216 src_cnt--; 217 src_list++; 218 } 219 220 /* wait for any prerequisite operations */ 221 async_tx_quiesce(&submit->depend_tx); 222 223 do_sync_xor(dest, src_list, offset, src_cnt, len, submit); 224 225 return NULL; 226 } 227 } 228 EXPORT_SYMBOL_GPL(async_xor); 229 230 static int page_is_zero(struct page *p, unsigned int offset, size_t len) 231 { 232 char *a = page_address(p) + offset; 233 return ((*(u32 *) a) == 0 && 234 memcmp(a, a + 4, len - 4) == 0); 235 } 236 237 static inline struct dma_chan * 238 xor_val_chan(struct async_submit_ctl *submit, struct page *dest, 239 struct page **src_list, int src_cnt, size_t len) 240 { 241 #ifdef CONFIG_ASYNC_TX_DISABLE_XOR_VAL_DMA 242 return NULL; 243 #endif 244 return async_tx_find_channel(submit, DMA_XOR_VAL, &dest, 1, src_list, 245 src_cnt, len); 246 } 247 248 /** 249 * async_xor_val - attempt a xor parity check with a dma engine. 250 * @dest: destination page used if the xor is performed synchronously 251 * @src_list: array of source pages 252 * @offset: offset in pages to start transaction 253 * @src_cnt: number of source pages 254 * @len: length in bytes 255 * @result: 0 if sum == 0 else non-zero 256 * @submit: submission / completion modifiers 257 * 258 * honored flags: ASYNC_TX_ACK 259 * 260 * src_list note: if the dest is also a source it must be at index zero. 261 * The contents of this array will be overwritten if a scribble region 262 * is not specified. 263 */ 264 struct dma_async_tx_descriptor * 265 async_xor_val(struct page *dest, struct page **src_list, unsigned int offset, 266 int src_cnt, size_t len, enum sum_check_flags *result, 267 struct async_submit_ctl *submit) 268 { 269 struct dma_chan *chan = xor_val_chan(submit, dest, src_list, src_cnt, len); 270 struct dma_device *device = chan ? chan->device : NULL; 271 struct dma_async_tx_descriptor *tx = NULL; 272 dma_addr_t *dma_src = NULL; 273 274 BUG_ON(src_cnt <= 1); 275 276 if (submit->scribble) 277 dma_src = submit->scribble; 278 else if (sizeof(dma_addr_t) <= sizeof(struct page *)) 279 dma_src = (dma_addr_t *) src_list; 280 281 if (dma_src && device && src_cnt <= device->max_xor && 282 is_dma_xor_aligned(device, offset, 0, len)) { 283 unsigned long dma_prep_flags = 0; 284 int i; 285 286 pr_debug("%s: (async) len: %zu\n", __func__, len); 287 288 if (submit->cb_fn) 289 dma_prep_flags |= DMA_PREP_INTERRUPT; 290 if (submit->flags & ASYNC_TX_FENCE) 291 dma_prep_flags |= DMA_PREP_FENCE; 292 for (i = 0; i < src_cnt; i++) 293 dma_src[i] = dma_map_page(device->dev, src_list[i], 294 offset, len, DMA_TO_DEVICE); 295 296 tx = device->device_prep_dma_xor_val(chan, dma_src, src_cnt, 297 len, result, 298 dma_prep_flags); 299 if (unlikely(!tx)) { 300 async_tx_quiesce(&submit->depend_tx); 301 302 while (!tx) { 303 dma_async_issue_pending(chan); 304 tx = device->device_prep_dma_xor_val(chan, 305 dma_src, src_cnt, len, result, 306 dma_prep_flags); 307 } 308 } 309 310 async_tx_submit(chan, tx, submit); 311 } else { 312 enum async_tx_flags flags_orig = submit->flags; 313 314 pr_debug("%s: (sync) len: %zu\n", __func__, len); 315 WARN_ONCE(device && src_cnt <= device->max_xor, 316 "%s: no space for dma address conversion\n", 317 __func__); 318 319 submit->flags |= ASYNC_TX_XOR_DROP_DST; 320 submit->flags &= ~ASYNC_TX_ACK; 321 322 tx = async_xor(dest, src_list, offset, src_cnt, len, submit); 323 324 async_tx_quiesce(&tx); 325 326 *result = !page_is_zero(dest, offset, len) << SUM_CHECK_P; 327 328 async_tx_sync_epilog(submit); 329 submit->flags = flags_orig; 330 } 331 332 return tx; 333 } 334 EXPORT_SYMBOL_GPL(async_xor_val); 335 336 MODULE_AUTHOR("Intel Corporation"); 337 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api"); 338 MODULE_LICENSE("GPL"); 339