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/module.h> 29 #include <linux/mm.h> 30 #include <linux/dma-mapping.h> 31 #include <linux/raid/xor.h> 32 #include <linux/async_tx.h> 33 34 /* do_async_xor - dma map the pages and perform the xor with an engine */ 35 static __async_inline struct dma_async_tx_descriptor * 36 do_async_xor(struct dma_chan *chan, struct dmaengine_unmap_data *unmap, 37 struct async_submit_ctl *submit) 38 { 39 struct dma_device *dma = chan->device; 40 struct dma_async_tx_descriptor *tx = NULL; 41 dma_async_tx_callback cb_fn_orig = submit->cb_fn; 42 void *cb_param_orig = submit->cb_param; 43 enum async_tx_flags flags_orig = submit->flags; 44 enum dma_ctrl_flags dma_flags = 0; 45 int src_cnt = unmap->to_cnt; 46 int xor_src_cnt; 47 dma_addr_t dma_dest = unmap->addr[unmap->to_cnt]; 48 dma_addr_t *src_list = unmap->addr; 49 50 while (src_cnt) { 51 dma_addr_t tmp; 52 53 submit->flags = flags_orig; 54 xor_src_cnt = min(src_cnt, (int)dma->max_xor); 55 /* if we are submitting additional xors, leave the chain open 56 * and clear the callback parameters 57 */ 58 if (src_cnt > xor_src_cnt) { 59 submit->flags &= ~ASYNC_TX_ACK; 60 submit->flags |= ASYNC_TX_FENCE; 61 submit->cb_fn = NULL; 62 submit->cb_param = NULL; 63 } else { 64 submit->cb_fn = cb_fn_orig; 65 submit->cb_param = cb_param_orig; 66 } 67 if (submit->cb_fn) 68 dma_flags |= DMA_PREP_INTERRUPT; 69 if (submit->flags & ASYNC_TX_FENCE) 70 dma_flags |= DMA_PREP_FENCE; 71 72 /* Drivers force forward progress in case they can not provide a 73 * descriptor 74 */ 75 tmp = src_list[0]; 76 if (src_list > unmap->addr) 77 src_list[0] = dma_dest; 78 tx = dma->device_prep_dma_xor(chan, dma_dest, src_list, 79 xor_src_cnt, unmap->len, 80 dma_flags); 81 82 if (unlikely(!tx)) 83 async_tx_quiesce(&submit->depend_tx); 84 85 /* spin wait for the preceding transactions to complete */ 86 while (unlikely(!tx)) { 87 dma_async_issue_pending(chan); 88 tx = dma->device_prep_dma_xor(chan, dma_dest, 89 src_list, 90 xor_src_cnt, unmap->len, 91 dma_flags); 92 } 93 src_list[0] = tmp; 94 95 dma_set_unmap(tx, unmap); 96 async_tx_submit(chan, tx, submit); 97 submit->depend_tx = tx; 98 99 if (src_cnt > xor_src_cnt) { 100 /* drop completed sources */ 101 src_cnt -= xor_src_cnt; 102 /* use the intermediate result a source */ 103 src_cnt++; 104 src_list += xor_src_cnt - 1; 105 } else 106 break; 107 } 108 109 return tx; 110 } 111 112 static void 113 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset, 114 int src_cnt, size_t len, struct async_submit_ctl *submit) 115 { 116 int i; 117 int xor_src_cnt = 0; 118 int src_off = 0; 119 void *dest_buf; 120 void **srcs; 121 122 if (submit->scribble) 123 srcs = submit->scribble; 124 else 125 srcs = (void **) src_list; 126 127 /* convert to buffer pointers */ 128 for (i = 0; i < src_cnt; i++) 129 if (src_list[i]) 130 srcs[xor_src_cnt++] = page_address(src_list[i]) + offset; 131 src_cnt = xor_src_cnt; 132 /* set destination address */ 133 dest_buf = page_address(dest) + offset; 134 135 if (submit->flags & ASYNC_TX_XOR_ZERO_DST) 136 memset(dest_buf, 0, len); 137 138 while (src_cnt > 0) { 139 /* process up to 'MAX_XOR_BLOCKS' sources */ 140 xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS); 141 xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]); 142 143 /* drop completed sources */ 144 src_cnt -= xor_src_cnt; 145 src_off += xor_src_cnt; 146 } 147 148 async_tx_sync_epilog(submit); 149 } 150 151 /** 152 * async_xor - attempt to xor a set of blocks with a dma engine. 153 * @dest: destination page 154 * @src_list: array of source pages 155 * @offset: common src/dst offset to start transaction 156 * @src_cnt: number of source pages 157 * @len: length in bytes 158 * @submit: submission / completion modifiers 159 * 160 * honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST 161 * 162 * xor_blocks always uses the dest as a source so the 163 * ASYNC_TX_XOR_ZERO_DST flag must be set to not include dest data in 164 * the calculation. The assumption with dma eninges is that they only 165 * use the destination buffer as a source when it is explicity specified 166 * in the source list. 167 * 168 * src_list note: if the dest is also a source it must be at index zero. 169 * The contents of this array will be overwritten if a scribble region 170 * is not specified. 171 */ 172 struct dma_async_tx_descriptor * 173 async_xor(struct page *dest, struct page **src_list, unsigned int offset, 174 int src_cnt, size_t len, struct async_submit_ctl *submit) 175 { 176 struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR, 177 &dest, 1, src_list, 178 src_cnt, len); 179 struct dma_device *device = chan ? chan->device : NULL; 180 struct dmaengine_unmap_data *unmap = NULL; 181 182 BUG_ON(src_cnt <= 1); 183 184 if (device) 185 unmap = dmaengine_get_unmap_data(device->dev, src_cnt+1, GFP_NOIO); 186 187 if (unmap && is_dma_xor_aligned(device, offset, 0, len)) { 188 struct dma_async_tx_descriptor *tx; 189 int i, j; 190 191 /* run the xor asynchronously */ 192 pr_debug("%s (async): len: %zu\n", __func__, len); 193 194 unmap->len = len; 195 for (i = 0, j = 0; i < src_cnt; i++) { 196 if (!src_list[i]) 197 continue; 198 unmap->to_cnt++; 199 unmap->addr[j++] = dma_map_page(device->dev, src_list[i], 200 offset, len, DMA_TO_DEVICE); 201 } 202 203 /* map it bidirectional as it may be re-used as a source */ 204 unmap->addr[j] = dma_map_page(device->dev, dest, offset, len, 205 DMA_BIDIRECTIONAL); 206 unmap->bidi_cnt = 1; 207 208 tx = do_async_xor(chan, unmap, submit); 209 dmaengine_unmap_put(unmap); 210 return tx; 211 } else { 212 dmaengine_unmap_put(unmap); 213 /* run the xor synchronously */ 214 pr_debug("%s (sync): len: %zu\n", __func__, len); 215 WARN_ONCE(chan, "%s: no space for dma address conversion\n", 216 __func__); 217 218 /* in the sync case the dest is an implied source 219 * (assumes the dest is the first source) 220 */ 221 if (submit->flags & ASYNC_TX_XOR_DROP_DST) { 222 src_cnt--; 223 src_list++; 224 } 225 226 /* wait for any prerequisite operations */ 227 async_tx_quiesce(&submit->depend_tx); 228 229 do_sync_xor(dest, src_list, offset, src_cnt, len, submit); 230 231 return NULL; 232 } 233 } 234 EXPORT_SYMBOL_GPL(async_xor); 235 236 static int page_is_zero(struct page *p, unsigned int offset, size_t len) 237 { 238 return !memchr_inv(page_address(p) + offset, 0, len); 239 } 240 241 static inline struct dma_chan * 242 xor_val_chan(struct async_submit_ctl *submit, struct page *dest, 243 struct page **src_list, int src_cnt, size_t len) 244 { 245 #ifdef CONFIG_ASYNC_TX_DISABLE_XOR_VAL_DMA 246 return NULL; 247 #endif 248 return async_tx_find_channel(submit, DMA_XOR_VAL, &dest, 1, src_list, 249 src_cnt, len); 250 } 251 252 /** 253 * async_xor_val - attempt a xor parity check with a dma engine. 254 * @dest: destination page used if the xor is performed synchronously 255 * @src_list: array of source pages 256 * @offset: offset in pages to start transaction 257 * @src_cnt: number of source pages 258 * @len: length in bytes 259 * @result: 0 if sum == 0 else non-zero 260 * @submit: submission / completion modifiers 261 * 262 * honored flags: ASYNC_TX_ACK 263 * 264 * src_list note: if the dest is also a source it must be at index zero. 265 * The contents of this array will be overwritten if a scribble region 266 * is not specified. 267 */ 268 struct dma_async_tx_descriptor * 269 async_xor_val(struct page *dest, struct page **src_list, unsigned int offset, 270 int src_cnt, size_t len, enum sum_check_flags *result, 271 struct async_submit_ctl *submit) 272 { 273 struct dma_chan *chan = xor_val_chan(submit, dest, src_list, src_cnt, len); 274 struct dma_device *device = chan ? chan->device : NULL; 275 struct dma_async_tx_descriptor *tx = NULL; 276 struct dmaengine_unmap_data *unmap = NULL; 277 278 BUG_ON(src_cnt <= 1); 279 280 if (device) 281 unmap = dmaengine_get_unmap_data(device->dev, src_cnt, GFP_NOIO); 282 283 if (unmap && src_cnt <= device->max_xor && 284 is_dma_xor_aligned(device, offset, 0, len)) { 285 unsigned long dma_prep_flags = 0; 286 int i; 287 288 pr_debug("%s: (async) len: %zu\n", __func__, len); 289 290 if (submit->cb_fn) 291 dma_prep_flags |= DMA_PREP_INTERRUPT; 292 if (submit->flags & ASYNC_TX_FENCE) 293 dma_prep_flags |= DMA_PREP_FENCE; 294 295 for (i = 0; i < src_cnt; i++) { 296 unmap->addr[i] = dma_map_page(device->dev, src_list[i], 297 offset, len, DMA_TO_DEVICE); 298 unmap->to_cnt++; 299 } 300 unmap->len = len; 301 302 tx = device->device_prep_dma_xor_val(chan, unmap->addr, src_cnt, 303 len, result, 304 dma_prep_flags); 305 if (unlikely(!tx)) { 306 async_tx_quiesce(&submit->depend_tx); 307 308 while (!tx) { 309 dma_async_issue_pending(chan); 310 tx = device->device_prep_dma_xor_val(chan, 311 unmap->addr, src_cnt, len, result, 312 dma_prep_flags); 313 } 314 } 315 dma_set_unmap(tx, unmap); 316 async_tx_submit(chan, tx, submit); 317 } else { 318 enum async_tx_flags flags_orig = submit->flags; 319 320 pr_debug("%s: (sync) len: %zu\n", __func__, len); 321 WARN_ONCE(device && src_cnt <= device->max_xor, 322 "%s: no space for dma address conversion\n", 323 __func__); 324 325 submit->flags |= ASYNC_TX_XOR_DROP_DST; 326 submit->flags &= ~ASYNC_TX_ACK; 327 328 tx = async_xor(dest, src_list, offset, src_cnt, len, submit); 329 330 async_tx_quiesce(&tx); 331 332 *result = !page_is_zero(dest, offset, len) << SUM_CHECK_P; 333 334 async_tx_sync_epilog(submit); 335 submit->flags = flags_orig; 336 } 337 dmaengine_unmap_put(unmap); 338 339 return tx; 340 } 341 EXPORT_SYMBOL_GPL(async_xor_val); 342 343 MODULE_AUTHOR("Intel Corporation"); 344 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api"); 345 MODULE_LICENSE("GPL"); 346