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 src_list[0] = tmp; 82 83 84 if (unlikely(!tx)) 85 async_tx_quiesce(&submit->depend_tx); 86 87 /* spin wait for the preceding transactions to complete */ 88 while (unlikely(!tx)) { 89 dma_async_issue_pending(chan); 90 tx = dma->device_prep_dma_xor(chan, dma_dest, 91 src_list, 92 xor_src_cnt, unmap->len, 93 dma_flags); 94 } 95 96 dma_set_unmap(tx, unmap); 97 async_tx_submit(chan, tx, submit); 98 submit->depend_tx = tx; 99 100 if (src_cnt > xor_src_cnt) { 101 /* drop completed sources */ 102 src_cnt -= xor_src_cnt; 103 /* use the intermediate result a source */ 104 src_cnt++; 105 src_list += xor_src_cnt - 1; 106 } else 107 break; 108 } 109 110 return tx; 111 } 112 113 static void 114 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset, 115 int src_cnt, size_t len, struct async_submit_ctl *submit) 116 { 117 int i; 118 int xor_src_cnt = 0; 119 int src_off = 0; 120 void *dest_buf; 121 void **srcs; 122 123 if (submit->scribble) 124 srcs = submit->scribble; 125 else 126 srcs = (void **) src_list; 127 128 /* convert to buffer pointers */ 129 for (i = 0; i < src_cnt; i++) 130 if (src_list[i]) 131 srcs[xor_src_cnt++] = page_address(src_list[i]) + offset; 132 src_cnt = xor_src_cnt; 133 /* set destination address */ 134 dest_buf = page_address(dest) + offset; 135 136 if (submit->flags & ASYNC_TX_XOR_ZERO_DST) 137 memset(dest_buf, 0, len); 138 139 while (src_cnt > 0) { 140 /* process up to 'MAX_XOR_BLOCKS' sources */ 141 xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS); 142 xor_blocks(xor_src_cnt, len, dest_buf, &srcs[src_off]); 143 144 /* drop completed sources */ 145 src_cnt -= xor_src_cnt; 146 src_off += xor_src_cnt; 147 } 148 149 async_tx_sync_epilog(submit); 150 } 151 152 /** 153 * async_xor - attempt to xor a set of blocks with a dma engine. 154 * @dest: destination page 155 * @src_list: array of source pages 156 * @offset: common src/dst offset to start transaction 157 * @src_cnt: number of source pages 158 * @len: length in bytes 159 * @submit: submission / completion modifiers 160 * 161 * honored flags: ASYNC_TX_ACK, ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DST 162 * 163 * xor_blocks always uses the dest as a source so the 164 * ASYNC_TX_XOR_ZERO_DST flag must be set to not include dest data in 165 * the calculation. The assumption with dma eninges is that they only 166 * use the destination buffer as a source when it is explicity specified 167 * in the source list. 168 * 169 * src_list note: if the dest is also a source it must be at index zero. 170 * The contents of this array will be overwritten if a scribble region 171 * is not specified. 172 */ 173 struct dma_async_tx_descriptor * 174 async_xor(struct page *dest, struct page **src_list, unsigned int offset, 175 int src_cnt, size_t len, struct async_submit_ctl *submit) 176 { 177 struct dma_chan *chan = async_tx_find_channel(submit, DMA_XOR, 178 &dest, 1, src_list, 179 src_cnt, len); 180 struct dma_device *device = chan ? chan->device : NULL; 181 struct dmaengine_unmap_data *unmap = NULL; 182 183 BUG_ON(src_cnt <= 1); 184 185 if (device) 186 unmap = dmaengine_get_unmap_data(device->dev, src_cnt+1, GFP_NOIO); 187 188 if (unmap && is_dma_xor_aligned(device, offset, 0, len)) { 189 struct dma_async_tx_descriptor *tx; 190 int i, j; 191 192 /* run the xor asynchronously */ 193 pr_debug("%s (async): len: %zu\n", __func__, len); 194 195 unmap->len = len; 196 for (i = 0, j = 0; i < src_cnt; i++) { 197 if (!src_list[i]) 198 continue; 199 unmap->to_cnt++; 200 unmap->addr[j++] = dma_map_page(device->dev, src_list[i], 201 offset, len, DMA_TO_DEVICE); 202 } 203 204 /* map it bidirectional as it may be re-used as a source */ 205 unmap->addr[j] = dma_map_page(device->dev, dest, offset, len, 206 DMA_BIDIRECTIONAL); 207 unmap->bidi_cnt = 1; 208 209 tx = do_async_xor(chan, unmap, submit); 210 dmaengine_unmap_put(unmap); 211 return tx; 212 } else { 213 dmaengine_unmap_put(unmap); 214 /* run the xor synchronously */ 215 pr_debug("%s (sync): len: %zu\n", __func__, len); 216 WARN_ONCE(chan, "%s: no space for dma address conversion\n", 217 __func__); 218 219 /* in the sync case the dest is an implied source 220 * (assumes the dest is the first source) 221 */ 222 if (submit->flags & ASYNC_TX_XOR_DROP_DST) { 223 src_cnt--; 224 src_list++; 225 } 226 227 /* wait for any prerequisite operations */ 228 async_tx_quiesce(&submit->depend_tx); 229 230 do_sync_xor(dest, src_list, offset, src_cnt, len, submit); 231 232 return NULL; 233 } 234 } 235 EXPORT_SYMBOL_GPL(async_xor); 236 237 static int page_is_zero(struct page *p, unsigned int offset, size_t len) 238 { 239 return !memchr_inv(page_address(p) + offset, 0, len); 240 } 241 242 static inline struct dma_chan * 243 xor_val_chan(struct async_submit_ctl *submit, struct page *dest, 244 struct page **src_list, int src_cnt, size_t len) 245 { 246 #ifdef CONFIG_ASYNC_TX_DISABLE_XOR_VAL_DMA 247 return NULL; 248 #endif 249 return async_tx_find_channel(submit, DMA_XOR_VAL, &dest, 1, src_list, 250 src_cnt, len); 251 } 252 253 /** 254 * async_xor_val - attempt a xor parity check with a dma engine. 255 * @dest: destination page used if the xor is performed synchronously 256 * @src_list: array of source pages 257 * @offset: offset in pages to start transaction 258 * @src_cnt: number of source pages 259 * @len: length in bytes 260 * @result: 0 if sum == 0 else non-zero 261 * @submit: submission / completion modifiers 262 * 263 * honored flags: ASYNC_TX_ACK 264 * 265 * src_list note: if the dest is also a source it must be at index zero. 266 * The contents of this array will be overwritten if a scribble region 267 * is not specified. 268 */ 269 struct dma_async_tx_descriptor * 270 async_xor_val(struct page *dest, struct page **src_list, unsigned int offset, 271 int src_cnt, size_t len, enum sum_check_flags *result, 272 struct async_submit_ctl *submit) 273 { 274 struct dma_chan *chan = xor_val_chan(submit, dest, src_list, src_cnt, len); 275 struct dma_device *device = chan ? chan->device : NULL; 276 struct dma_async_tx_descriptor *tx = NULL; 277 struct dmaengine_unmap_data *unmap = NULL; 278 279 BUG_ON(src_cnt <= 1); 280 281 if (device) 282 unmap = dmaengine_get_unmap_data(device->dev, src_cnt, GFP_NOIO); 283 284 if (unmap && src_cnt <= device->max_xor && 285 is_dma_xor_aligned(device, offset, 0, len)) { 286 unsigned long dma_prep_flags = 0; 287 int i; 288 289 pr_debug("%s: (async) len: %zu\n", __func__, len); 290 291 if (submit->cb_fn) 292 dma_prep_flags |= DMA_PREP_INTERRUPT; 293 if (submit->flags & ASYNC_TX_FENCE) 294 dma_prep_flags |= DMA_PREP_FENCE; 295 296 for (i = 0; i < src_cnt; i++) { 297 unmap->addr[i] = dma_map_page(device->dev, src_list[i], 298 offset, len, DMA_TO_DEVICE); 299 unmap->to_cnt++; 300 } 301 unmap->len = len; 302 303 tx = device->device_prep_dma_xor_val(chan, unmap->addr, src_cnt, 304 len, result, 305 dma_prep_flags); 306 if (unlikely(!tx)) { 307 async_tx_quiesce(&submit->depend_tx); 308 309 while (!tx) { 310 dma_async_issue_pending(chan); 311 tx = device->device_prep_dma_xor_val(chan, 312 unmap->addr, src_cnt, len, result, 313 dma_prep_flags); 314 } 315 } 316 dma_set_unmap(tx, unmap); 317 async_tx_submit(chan, tx, submit); 318 } else { 319 enum async_tx_flags flags_orig = submit->flags; 320 321 pr_debug("%s: (sync) len: %zu\n", __func__, len); 322 WARN_ONCE(device && src_cnt <= device->max_xor, 323 "%s: no space for dma address conversion\n", 324 __func__); 325 326 submit->flags |= ASYNC_TX_XOR_DROP_DST; 327 submit->flags &= ~ASYNC_TX_ACK; 328 329 tx = async_xor(dest, src_list, offset, src_cnt, len, submit); 330 331 async_tx_quiesce(&tx); 332 333 *result = !page_is_zero(dest, offset, len) << SUM_CHECK_P; 334 335 async_tx_sync_epilog(submit); 336 submit->flags = flags_orig; 337 } 338 dmaengine_unmap_put(unmap); 339 340 return tx; 341 } 342 EXPORT_SYMBOL_GPL(async_xor_val); 343 344 MODULE_AUTHOR("Intel Corporation"); 345 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api"); 346 MODULE_LICENSE("GPL"); 347