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 static void 34 do_async_xor(struct dma_async_tx_descriptor *tx, struct dma_device *device, 35 struct dma_chan *chan, struct page *dest, struct page **src_list, 36 unsigned int offset, unsigned int src_cnt, size_t len, 37 enum async_tx_flags flags, struct dma_async_tx_descriptor *depend_tx, 38 dma_async_tx_callback cb_fn, void *cb_param) 39 { 40 dma_addr_t dma_addr; 41 enum dma_data_direction dir; 42 int i; 43 44 pr_debug("%s: len: %zu\n", __FUNCTION__, len); 45 46 dir = (flags & ASYNC_TX_ASSUME_COHERENT) ? 47 DMA_NONE : DMA_FROM_DEVICE; 48 49 dma_addr = dma_map_page(device->dev, dest, offset, len, dir); 50 tx->tx_set_dest(dma_addr, tx, 0); 51 52 dir = (flags & ASYNC_TX_ASSUME_COHERENT) ? 53 DMA_NONE : DMA_TO_DEVICE; 54 55 for (i = 0; i < src_cnt; i++) { 56 dma_addr = dma_map_page(device->dev, src_list[i], 57 offset, len, dir); 58 tx->tx_set_src(dma_addr, tx, i); 59 } 60 61 async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param); 62 } 63 64 static void 65 do_sync_xor(struct page *dest, struct page **src_list, unsigned int offset, 66 unsigned int src_cnt, size_t len, enum async_tx_flags flags, 67 struct dma_async_tx_descriptor *depend_tx, 68 dma_async_tx_callback cb_fn, void *cb_param) 69 { 70 void *_dest; 71 int i; 72 73 pr_debug("%s: len: %zu\n", __FUNCTION__, len); 74 75 /* reuse the 'src_list' array to convert to buffer pointers */ 76 for (i = 0; i < src_cnt; i++) 77 src_list[i] = (struct page *) 78 (page_address(src_list[i]) + offset); 79 80 /* set destination address */ 81 _dest = page_address(dest) + offset; 82 83 if (flags & ASYNC_TX_XOR_ZERO_DST) 84 memset(_dest, 0, len); 85 86 xor_blocks(src_cnt, len, _dest, 87 (void **) src_list); 88 89 async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param); 90 } 91 92 /** 93 * async_xor - attempt to xor a set of blocks with a dma engine. 94 * xor_blocks always uses the dest as a source so the ASYNC_TX_XOR_ZERO_DST 95 * flag must be set to not include dest data in the calculation. The 96 * assumption with dma eninges is that they only use the destination 97 * buffer as a source when it is explicity specified in the source list. 98 * @dest: destination page 99 * @src_list: array of source pages (if the dest is also a source it must be 100 * at index zero). The contents of this array may be overwritten. 101 * @offset: offset in pages to start transaction 102 * @src_cnt: number of source pages 103 * @len: length in bytes 104 * @flags: ASYNC_TX_XOR_ZERO_DST, ASYNC_TX_XOR_DROP_DEST, 105 * ASYNC_TX_ASSUME_COHERENT, ASYNC_TX_ACK, ASYNC_TX_DEP_ACK 106 * @depend_tx: xor depends on the result of this transaction. 107 * @cb_fn: function to call when the xor completes 108 * @cb_param: parameter to pass to the callback routine 109 */ 110 struct dma_async_tx_descriptor * 111 async_xor(struct page *dest, struct page **src_list, unsigned int offset, 112 int src_cnt, size_t len, enum async_tx_flags flags, 113 struct dma_async_tx_descriptor *depend_tx, 114 dma_async_tx_callback cb_fn, void *cb_param) 115 { 116 struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_XOR); 117 struct dma_device *device = chan ? chan->device : NULL; 118 struct dma_async_tx_descriptor *tx = NULL; 119 dma_async_tx_callback _cb_fn; 120 void *_cb_param; 121 unsigned long local_flags; 122 int xor_src_cnt; 123 int i = 0, src_off = 0, int_en; 124 125 BUG_ON(src_cnt <= 1); 126 127 while (src_cnt) { 128 local_flags = flags; 129 if (device) { /* run the xor asynchronously */ 130 xor_src_cnt = min(src_cnt, device->max_xor); 131 /* if we are submitting additional xors 132 * only set the callback on the last transaction 133 */ 134 if (src_cnt > xor_src_cnt) { 135 local_flags &= ~ASYNC_TX_ACK; 136 _cb_fn = NULL; 137 _cb_param = NULL; 138 } else { 139 _cb_fn = cb_fn; 140 _cb_param = cb_param; 141 } 142 143 int_en = _cb_fn ? 1 : 0; 144 145 tx = device->device_prep_dma_xor( 146 chan, xor_src_cnt, len, int_en); 147 148 if (tx) { 149 do_async_xor(tx, device, chan, dest, 150 &src_list[src_off], offset, xor_src_cnt, len, 151 local_flags, depend_tx, _cb_fn, 152 _cb_param); 153 } else /* fall through */ 154 goto xor_sync; 155 } else { /* run the xor synchronously */ 156 xor_sync: 157 /* in the sync case the dest is an implied source 158 * (assumes the dest is at the src_off index) 159 */ 160 if (flags & ASYNC_TX_XOR_DROP_DST) { 161 src_cnt--; 162 src_off++; 163 } 164 165 /* process up to 'MAX_XOR_BLOCKS' sources */ 166 xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS); 167 168 /* if we are submitting additional xors 169 * only set the callback on the last transaction 170 */ 171 if (src_cnt > xor_src_cnt) { 172 local_flags &= ~ASYNC_TX_ACK; 173 _cb_fn = NULL; 174 _cb_param = NULL; 175 } else { 176 _cb_fn = cb_fn; 177 _cb_param = cb_param; 178 } 179 180 /* wait for any prerequisite operations */ 181 if (depend_tx) { 182 /* if ack is already set then we cannot be sure 183 * we are referring to the correct operation 184 */ 185 BUG_ON(depend_tx->ack); 186 if (dma_wait_for_async_tx(depend_tx) == 187 DMA_ERROR) 188 panic("%s: DMA_ERROR waiting for " 189 "depend_tx\n", 190 __FUNCTION__); 191 } 192 193 do_sync_xor(dest, &src_list[src_off], offset, 194 xor_src_cnt, len, local_flags, depend_tx, 195 _cb_fn, _cb_param); 196 } 197 198 /* the previous tx is hidden from the client, 199 * so ack it 200 */ 201 if (i && depend_tx) 202 async_tx_ack(depend_tx); 203 204 depend_tx = tx; 205 206 if (src_cnt > xor_src_cnt) { 207 /* drop completed sources */ 208 src_cnt -= xor_src_cnt; 209 src_off += xor_src_cnt; 210 211 /* unconditionally preserve the destination */ 212 flags &= ~ASYNC_TX_XOR_ZERO_DST; 213 214 /* use the intermediate result a source, but remember 215 * it's dropped, because it's implied, in the sync case 216 */ 217 src_list[--src_off] = dest; 218 src_cnt++; 219 flags |= ASYNC_TX_XOR_DROP_DST; 220 } else 221 src_cnt = 0; 222 i++; 223 } 224 225 return tx; 226 } 227 EXPORT_SYMBOL_GPL(async_xor); 228 229 static int page_is_zero(struct page *p, unsigned int offset, size_t len) 230 { 231 char *a = page_address(p) + offset; 232 return ((*(u32 *) a) == 0 && 233 memcmp(a, a + 4, len - 4) == 0); 234 } 235 236 /** 237 * async_xor_zero_sum - attempt a xor parity check with a dma engine. 238 * @dest: destination page used if the xor is performed synchronously 239 * @src_list: array of source pages. The dest page must be listed as a source 240 * at index zero. The contents of this array may be overwritten. 241 * @offset: offset in pages to start transaction 242 * @src_cnt: number of source pages 243 * @len: length in bytes 244 * @result: 0 if sum == 0 else non-zero 245 * @flags: ASYNC_TX_ASSUME_COHERENT, ASYNC_TX_ACK, ASYNC_TX_DEP_ACK 246 * @depend_tx: xor depends on the result of this transaction. 247 * @cb_fn: function to call when the xor completes 248 * @cb_param: parameter to pass to the callback routine 249 */ 250 struct dma_async_tx_descriptor * 251 async_xor_zero_sum(struct page *dest, struct page **src_list, 252 unsigned int offset, int src_cnt, size_t len, 253 u32 *result, enum async_tx_flags flags, 254 struct dma_async_tx_descriptor *depend_tx, 255 dma_async_tx_callback cb_fn, void *cb_param) 256 { 257 struct dma_chan *chan = async_tx_find_channel(depend_tx, DMA_ZERO_SUM); 258 struct dma_device *device = chan ? chan->device : NULL; 259 int int_en = cb_fn ? 1 : 0; 260 struct dma_async_tx_descriptor *tx = device ? 261 device->device_prep_dma_zero_sum(chan, src_cnt, len, result, 262 int_en) : NULL; 263 int i; 264 265 BUG_ON(src_cnt <= 1); 266 267 if (tx) { 268 dma_addr_t dma_addr; 269 enum dma_data_direction dir; 270 271 pr_debug("%s: (async) len: %zu\n", __FUNCTION__, len); 272 273 dir = (flags & ASYNC_TX_ASSUME_COHERENT) ? 274 DMA_NONE : DMA_TO_DEVICE; 275 276 for (i = 0; i < src_cnt; i++) { 277 dma_addr = dma_map_page(device->dev, src_list[i], 278 offset, len, dir); 279 tx->tx_set_src(dma_addr, tx, i); 280 } 281 282 async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param); 283 } else { 284 unsigned long xor_flags = flags; 285 286 pr_debug("%s: (sync) len: %zu\n", __FUNCTION__, len); 287 288 xor_flags |= ASYNC_TX_XOR_DROP_DST; 289 xor_flags &= ~ASYNC_TX_ACK; 290 291 tx = async_xor(dest, src_list, offset, src_cnt, len, xor_flags, 292 depend_tx, NULL, NULL); 293 294 if (tx) { 295 if (dma_wait_for_async_tx(tx) == DMA_ERROR) 296 panic("%s: DMA_ERROR waiting for tx\n", 297 __FUNCTION__); 298 async_tx_ack(tx); 299 } 300 301 *result = page_is_zero(dest, offset, len) ? 0 : 1; 302 303 tx = NULL; 304 305 async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param); 306 } 307 308 return tx; 309 } 310 EXPORT_SYMBOL_GPL(async_xor_zero_sum); 311 312 static int __init async_xor_init(void) 313 { 314 return 0; 315 } 316 317 static void __exit async_xor_exit(void) 318 { 319 do { } while (0); 320 } 321 322 module_init(async_xor_init); 323 module_exit(async_xor_exit); 324 325 MODULE_AUTHOR("Intel Corporation"); 326 MODULE_DESCRIPTION("asynchronous xor/xor-zero-sum api"); 327 MODULE_LICENSE("GPL"); 328