crypto/async_tx/async_xor.c

   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");