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