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