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 * This routine is marked __always_inline so it can be compiled away 35 * when CONFIG_DMA_ENGINE=n 36 */ 37 static __always_inline struct dma_async_tx_descriptor * 38 do_async_xor(struct dma_device *device, 39 struct dma_chan *chan, struct page *dest, struct page **src_list, 40 unsigned int offset, unsigned int src_cnt, size_t len, 41 enum async_tx_flags flags, struct dma_async_tx_descriptor *depend_tx, 42 dma_async_tx_callback cb_fn, void *cb_param) 43 { 44 dma_addr_t dma_dest; 45 dma_addr_t *dma_src = (dma_addr_t *) src_list; 46 struct dma_async_tx_descriptor *tx; 47 int i; 48 unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0; 49 50 pr_debug("%s: len: %zu\n", __func__, len); 51 52 dma_dest = dma_map_page(device->dev, dest, offset, len, 53 DMA_FROM_DEVICE); 54 55 for (i = 0; i < src_cnt; i++) 56 dma_src[i] = dma_map_page(device->dev, src_list[i], offset, 57 len, DMA_TO_DEVICE); 58 59 /* Since we have clobbered the src_list we are committed 60 * to doing this asynchronously. Drivers force forward progress 61 * in case they can not provide a descriptor 62 */ 63 tx = device->device_prep_dma_xor(chan, dma_dest, dma_src, src_cnt, len, 64 dma_prep_flags); 65 if (!tx) { 66 if (depend_tx) 67 dma_wait_for_async_tx(depend_tx); 68 69 while (!tx) 70 tx = device->device_prep_dma_xor(chan, dma_dest, 71 dma_src, src_cnt, len, 72 dma_prep_flags); 73 } 74 75 async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param); 76 77 return tx; 78 } 79 80 static void 81 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset, 82 unsigned int src_cnt, size_t len, enum async_tx_flags flags, 83 struct dma_async_tx_descriptor *depend_tx, 84 dma_async_tx_callback cb_fn, void *cb_param) 85 { 86 void *_dest; 87 int i; 88 89 pr_debug("%s: len: %zu\n", __func__, len); 90 91 /* reuse the 'src_list' array to convert to buffer pointers */ 92 for (i = 0; i < src_cnt; i++) 93 src_list[i] = (struct page *) 94 (page_address(src_list[i]) + offset); 95 96 /* set destination address */ 97 _dest = page_address(dest) + offset; 98 99 if (flags & ASYNC_TX_XOR_ZERO_DST) 100 memset(_dest, 0, len); 101 102 xor_blocks(src_cnt, len, _dest, 103 (void **) src_list); 104 105 async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param); 106 } 107 108 /** 109 * async_xor - attempt to xor a set of blocks with a dma engine. 110 * xor_blocks always uses the dest as a source so the ASYNC_TX_XOR_ZERO_DST 111 * flag must be set to not include dest data in the calculation. The 112 * assumption with dma eninges is that they only use the destination 113 * buffer as a source when it is explicity specified in the source list. 114 * @dest: destination page 115 * @src_list: array of source pages (if the dest is also a source it must be 116 * at index zero). The contents of this array may be overwritten. 117 * @offset: offset in pages to start transaction 118 * @src_cnt: number of source pages 119 * @len: length in bytes 120 * @flags: ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DEST, 121 * ASYNC_TX_ACK, ASYNC_TX_DEP_ACK 122 * @depend_tx: xor depends on the result of this transaction. 123 * @cb_fn: function to call when the xor completes 124 * @cb_param: parameter to pass to the callback routine 125 */ 126 struct dma_async_tx_descriptor * 127 async_xor(struct page *dest, struct page **src_list, unsigned int offset, 128 int src_cnt, size_t len, enum async_tx_flags flags, 129 struct dma_async_tx_descriptor *depend_tx, 130 dma_async_tx_callback cb_fn, void *cb_param) 131 { 132 struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_XOR, 133 &dest, 1, src_list, 134 src_cnt, len); 135 struct dma_device *device = chan ? chan->device : NULL; 136 struct dma_async_tx_descriptor *tx = NULL; 137 dma_async_tx_callback _cb_fn; 138 void *_cb_param; 139 unsigned long local_flags; 140 int xor_src_cnt; 141 int i = 0, src_off = 0; 142 143 BUG_ON(src_cnt <= 1); 144 145 while (src_cnt) { 146 local_flags = flags; 147 if (device) { /* run the xor asynchronously */ 148 xor_src_cnt = min(src_cnt, device->max_xor); 149 /* if we are submitting additional xors 150 * only set the callback on the last transaction 151 */ 152 if (src_cnt > xor_src_cnt) { 153 local_flags &= ~ASYNC_TX_ACK; 154 _cb_fn = NULL; 155 _cb_param = NULL; 156 } else { 157 _cb_fn = cb_fn; 158 _cb_param = cb_param; 159 } 160 161 tx = do_async_xor(device, chan, dest, 162 &src_list[src_off], offset, 163 xor_src_cnt, len, local_flags, 164 depend_tx, _cb_fn, _cb_param); 165 } else { /* run the xor synchronously */ 166 /* in the sync case the dest is an implied source 167 * (assumes the dest is at the src_off index) 168 */ 169 if (flags & ASYNC_TX_XOR_DROP_DST) { 170 src_cnt--; 171 src_off++; 172 } 173 174 /* process up to 'MAX_XOR_BLOCKS' sources */ 175 xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS); 176 177 /* if we are submitting additional xors 178 * only set the callback on the last transaction 179 */ 180 if (src_cnt > xor_src_cnt) { 181 local_flags &= ~ASYNC_TX_ACK; 182 _cb_fn = NULL; 183 _cb_param = NULL; 184 } else { 185 _cb_fn = cb_fn; 186 _cb_param = cb_param; 187 } 188 189 /* wait for any prerequisite operations */ 190 if (depend_tx) { 191 /* if ack is already set then we cannot be sure 192 * we are referring to the correct operation 193 */ 194 BUG_ON(async_tx_test_ack(depend_tx)); 195 if (dma_wait_for_async_tx(depend_tx) == 196 DMA_ERROR) 197 panic("%s: DMA_ERROR waiting for " 198 "depend_tx\n", 199 __func__); 200 } 201 202 do_sync_xor(dest, &src_list[src_off], offset, 203 xor_src_cnt, len, local_flags, depend_tx, 204 _cb_fn, _cb_param); 205 } 206 207 /* the previous tx is hidden from the client, 208 * so ack it 209 */ 210 if (i && depend_tx) 211 async_tx_ack(depend_tx); 212 213 depend_tx = tx; 214 215 if (src_cnt > xor_src_cnt) { 216 /* drop completed sources */ 217 src_cnt -= xor_src_cnt; 218 src_off += xor_src_cnt; 219 220 /* unconditionally preserve the destination */ 221 flags &= ~ASYNC_TX_XOR_ZERO_DST; 222 223 /* use the intermediate result a source, but remember 224 * it's dropped, because it's implied, in the sync case 225 */ 226 src_list[--src_off] = dest; 227 src_cnt++; 228 flags |= ASYNC_TX_XOR_DROP_DST; 229 } else 230 src_cnt = 0; 231 i++; 232 } 233 234 return tx; 235 } 236 EXPORT_SYMBOL_GPL(async_xor); 237 238 static int page_is_zero(struct page *p, unsigned int offset, size_t len) 239 { 240 char *a = page_address(p) + offset; 241 return ((*(u32 *) a) == 0 && 242 memcmp(a, a + 4, len - 4) == 0); 243 } 244 245 /** 246 * async_xor_zero_sum - attempt a xor parity check with a dma engine. 247 * @dest: destination page used if the xor is performed synchronously 248 * @src_list: array of source pages. The dest page must be listed as a source 249 * at index zero. The contents of this array may be overwritten. 250 * @offset: offset in pages to start transaction 251 * @src_cnt: number of source pages 252 * @len: length in bytes 253 * @result: 0 if sum == 0 else non-zero 254 * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK 255 * @depend_tx: xor depends on the result of this transaction. 256 * @cb_fn: function to call when the xor completes 257 * @cb_param: parameter to pass to the callback routine 258 */ 259 struct dma_async_tx_descriptor * 260 async_xor_zero_sum(struct page *dest, struct page **src_list, 261 unsigned int offset, int src_cnt, size_t len, 262 u32 *result, enum async_tx_flags flags, 263 struct dma_async_tx_descriptor *depend_tx, 264 dma_async_tx_callback cb_fn, void *cb_param) 265 { 266 struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_ZERO_SUM, 267 &dest, 1, src_list, 268 src_cnt, len); 269 struct dma_device *device = chan ? chan->device : NULL; 270 struct dma_async_tx_descriptor *tx = NULL; 271 272 BUG_ON(src_cnt <= 1); 273 274 if (device && src_cnt <= device->max_xor) { 275 dma_addr_t *dma_src = (dma_addr_t *) src_list; 276 unsigned long dma_prep_flags = cb_fn ? DMA_PREP_INTERRUPT : 0; 277 int i; 278 279 pr_debug("%s: (async) len: %zu\n", __func__, len); 280 281 for (i = 0; i < src_cnt; i++) 282 dma_src[i] = dma_map_page(device->dev, src_list[i], 283 offset, len, DMA_TO_DEVICE); 284 285 tx = device->device_prep_dma_zero_sum(chan, dma_src, src_cnt, 286 len, result, 287 dma_prep_flags); 288 if (!tx) { 289 if (depend_tx) 290 dma_wait_for_async_tx(depend_tx); 291 292 while (!tx) 293 tx = device->device_prep_dma_zero_sum(chan, 294 dma_src, src_cnt, len, result, 295 dma_prep_flags); 296 } 297 298 async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param); 299 } else { 300 unsigned long xor_flags = flags; 301 302 pr_debug("%s: (sync) len: %zu\n", __func__, len); 303 304 xor_flags |= ASYNC_TX_XOR_DROP_DST; 305 xor_flags &= ~ASYNC_TX_ACK; 306 307 tx = async_xor(dest, src_list, offset, src_cnt, len, xor_flags, 308 depend_tx, NULL, NULL); 309 310 if (tx) { 311 if (dma_wait_for_async_tx(tx) == DMA_ERROR) 312 panic("%s: DMA_ERROR waiting for tx\n", 313 __func__); 314 async_tx_ack(tx); 315 } 316 317 *result = page_is_zero(dest, offset, len) ? 0 : 1; 318 319 tx = NULL; 320 321 async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param); 322 } 323 324 return tx; 325 } 326 EXPORT_SYMBOL_GPL(async_xor_zero_sum); 327 328 static int __init async_xor_init(void) 329 { 330 #ifdef CONFIG_DMA_ENGINE 331 /* To conserve stack space the input src_list (array of page pointers) 332 * is reused to hold the array of dma addresses passed to the driver. 333 * This conversion is only possible when dma_addr_t is less than the 334 * the size of a pointer. HIGHMEM64G is known to violate this 335 * assumption. 336 */ 337 BUILD_BUG_ON(sizeof(dma_addr_t) > sizeof(struct page *)); 338 #endif 339 340 return 0; 341 } 342 343 static void __exit async_xor_exit(void) 344 { 345 do { } while (0); 346 } 347 348 module_init(async_xor_init); 349 module_exit(async_xor_exit); 350 351 MODULE_AUTHOR("Intel Corporation"); 352 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api"); 353 MODULE_LICENSE("GPL"); 354