drivers/dma/dmatest.c

   1 /*
   2  * DMA Engine test module
   3  *
   4  * Copyright (C) 2007 Atmel Corporation
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/delay.h>
  11 #include <linux/dmaengine.h>
  12 #include <linux/init.h>
  13 #include <linux/kthread.h>
  14 #include <linux/module.h>
  15 #include <linux/moduleparam.h>
  16 #include <linux/random.h>
  17 #include <linux/wait.h>
  18
  19 static unsigned int test_buf_size = 16384;
  20 module_param(test_buf_size, uint, S_IRUGO);
  21 MODULE_PARM_DESC(test_buf_size, "Size of the memcpy test buffer");
  22
  23 static char test_channel[20];
  24 module_param_string(channel, test_channel, sizeof(test_channel), S_IRUGO);
  25 MODULE_PARM_DESC(channel, "Bus ID of the channel to test (default: any)");
  26
  27 static char test_device[20];
  28 module_param_string(device, test_device, sizeof(test_device), S_IRUGO);
  29 MODULE_PARM_DESC(device, "Bus ID of the DMA Engine to test (default: any)");
  30
  31 static unsigned int threads_per_chan = 1;
  32 module_param(threads_per_chan, uint, S_IRUGO);
  33 MODULE_PARM_DESC(threads_per_chan,
  34                 "Number of threads to start per channel (default: 1)");
  35
  36 static unsigned int max_channels;
  37 module_param(max_channels, uint, S_IRUGO);
  38 MODULE_PARM_DESC(max_channels,
  39                 "Maximum number of channels to use (default: all)");
  40
  41 static unsigned int iterations;
  42 module_param(iterations, uint, S_IRUGO);
  43 MODULE_PARM_DESC(iterations,
  44                 "Iterations before stopping test (default: infinite)");
  45
  46 static unsigned int xor_sources = 3;
  47 module_param(xor_sources, uint, S_IRUGO);
  48 MODULE_PARM_DESC(xor_sources,
  49                 "Number of xor source buffers (default: 3)");
  50
  51 static unsigned int pq_sources = 3;
  52 module_param(pq_sources, uint, S_IRUGO);
  53 MODULE_PARM_DESC(pq_sources,
  54                 "Number of p+q source buffers (default: 3)");
  55
  56 /*
  57  * Initialization patterns. All bytes in the source buffer has bit 7
  58  * set, all bytes in the destination buffer has bit 7 cleared.
  59  *
  60  * Bit 6 is set for all bytes which are to be copied by the DMA
  61  * engine. Bit 5 is set for all bytes which are to be overwritten by
  62  * the DMA engine.
  63  *
  64  * The remaining bits are the inverse of a counter which increments by
  65  * one for each byte address.
  66  */
  67 #define PATTERN_SRC             0x80
  68 #define PATTERN_DST             0x00
  69 #define PATTERN_COPY            0x40
  70 #define PATTERN_OVERWRITE       0x20
  71 #define PATTERN_COUNT_MASK      0x1f
  72
  73 struct dmatest_thread {
  74         struct list_head        node;
  75         struct task_struct      *task;
  76         struct dma_chan         *chan;
  77         u8                      **srcs;
  78         u8                      **dsts;
  79         enum dma_transaction_type type;
  80 };
  81
  82 struct dmatest_chan {
  83         struct list_head        node;
  84         struct dma_chan         *chan;
  85         struct list_head        threads;
  86 };
  87
  88 /*
  89  * These are protected by dma_list_mutex since they're only used by
  90  * the DMA filter function callback
  91  */
  92 static LIST_HEAD(dmatest_channels);
  93 static unsigned int nr_channels;
  94
  95 static bool dmatest_match_channel(struct dma_chan *chan)
  96 {
  97         if (test_channel[0] == '\0')
  98                 return true;
  99         return strcmp(dma_chan_name(chan), test_channel) == 0;
 100 }
 101
 102 static bool dmatest_match_device(struct dma_device *device)
 103 {
 104         if (test_device[0] == '\0')
 105                 return true;
 106         return strcmp(dev_name(device->dev), test_device) == 0;
 107 }
 108
 109 static unsigned long dmatest_random(void)
 110 {
 111         unsigned long buf;
 112
 113         get_random_bytes(&buf, sizeof(buf));
 114         return buf;
 115 }
 116
 117 static void dmatest_init_srcs(u8 **bufs, unsigned int start, unsigned int len)
 118 {
 119         unsigned int i;
 120         u8 *buf;
 121
 122         for (; (buf = *bufs); bufs++) {
 123                 for (i = 0; i < start; i++)
 124                         buf[i] = PATTERN_SRC | (~i & PATTERN_COUNT_MASK);
 125                 for ( ; i < start + len; i++)
 126                         buf[i] = PATTERN_SRC | PATTERN_COPY
 127                                 | (~i & PATTERN_COUNT_MASK);
 128                 for ( ; i < test_buf_size; i++)
 129                         buf[i] = PATTERN_SRC | (~i & PATTERN_COUNT_MASK);
 130                 buf++;
 131         }
 132 }
 133
 134 static void dmatest_init_dsts(u8 **bufs, unsigned int start, unsigned int len)
 135 {
 136         unsigned int i;
 137         u8 *buf;
 138
 139         for (; (buf = *bufs); bufs++) {
 140                 for (i = 0; i < start; i++)
 141                         buf[i] = PATTERN_DST | (~i & PATTERN_COUNT_MASK);
 142                 for ( ; i < start + len; i++)
 143                         buf[i] = PATTERN_DST | PATTERN_OVERWRITE
 144                                 | (~i & PATTERN_COUNT_MASK);
 145                 for ( ; i < test_buf_size; i++)
 146                         buf[i] = PATTERN_DST | (~i & PATTERN_COUNT_MASK);
 147         }
 148 }
 149
 150 static void dmatest_mismatch(u8 actual, u8 pattern, unsigned int index,
 151                 unsigned int counter, bool is_srcbuf)
 152 {
 153         u8              diff = actual ^ pattern;
 154         u8              expected = pattern | (~counter & PATTERN_COUNT_MASK);
 155         const char      *thread_name = current->comm;
 156
 157         if (is_srcbuf)
 158                 pr_warning("%s: srcbuf[0x%x] overwritten!"
 159                                 " Expected %02x, got %02x\n",
 160                                 thread_name, index, expected, actual);
 161         else if ((pattern & PATTERN_COPY)
 162                         && (diff & (PATTERN_COPY | PATTERN_OVERWRITE)))
 163                 pr_warning("%s: dstbuf[0x%x] not copied!"
 164                                 " Expected %02x, got %02x\n",
 165                                 thread_name, index, expected, actual);
 166         else if (diff & PATTERN_SRC)
 167                 pr_warning("%s: dstbuf[0x%x] was copied!"
 168                                 " Expected %02x, got %02x\n",
 169                                 thread_name, index, expected, actual);
 170         else
 171                 pr_warning("%s: dstbuf[0x%x] mismatch!"
 172                                 " Expected %02x, got %02x\n",
 173                                 thread_name, index, expected, actual);
 174 }
 175
 176 static unsigned int dmatest_verify(u8 **bufs, unsigned int start,
 177                 unsigned int end, unsigned int counter, u8 pattern,
 178                 bool is_srcbuf)
 179 {
 180         unsigned int i;
 181         unsigned int error_count = 0;
 182         u8 actual;
 183         u8 expected;
 184         u8 *buf;
 185         unsigned int counter_orig = counter;
 186
 187         for (; (buf = *bufs); bufs++) {
 188                 counter = counter_orig;
 189                 for (i = start; i < end; i++) {
 190                         actual = buf[i];
 191                         expected = pattern | (~counter & PATTERN_COUNT_MASK);
 192                         if (actual != expected) {
 193                                 if (error_count < 32)
 194                                         dmatest_mismatch(actual, pattern, i,
 195                                                          counter, is_srcbuf);
 196                                 error_count++;
 197                         }
 198                         counter++;
 199                 }
 200         }
 201
 202         if (error_count > 32)
 203                 pr_warning("%s: %u errors suppressed\n",
 204                         current->comm, error_count - 32);
 205
 206         return error_count;
 207 }
 208
 209 static void dmatest_callback(void *completion)
 210 {
 211         complete(completion);
 212 }
 213
 214 /*
 215  * This function repeatedly tests DMA transfers of various lengths and
 216  * offsets for a given operation type until it is told to exit by
 217  * kthread_stop(). There may be multiple threads running this function
 218  * in parallel for a single channel, and there may be multiple channels
 219  * being tested in parallel.
 220  *
 221  * Before each test, the source and destination buffer is initialized
 222  * with a known pattern. This pattern is different depending on
 223  * whether it's in an area which is supposed to be copied or
 224  * overwritten, and different in the source and destination buffers.
 225  * So if the DMA engine doesn't copy exactly what we tell it to copy,
 226  * we'll notice.
 227  */
 228 static int dmatest_func(void *data)
 229 {
 230         struct dmatest_thread   *thread = data;
 231         struct dma_chan         *chan;
 232         const char              *thread_name;
 233         unsigned int            src_off, dst_off, len;
 234         unsigned int            error_count;
 235         unsigned int            failed_tests = 0;
 236         unsigned int            total_tests = 0;
 237         dma_cookie_t            cookie;
 238         enum dma_status         status;
 239         enum dma_ctrl_flags     flags;
 240         u8                      pq_coefs[pq_sources + 1];
 241         int                     ret;
 242         int                     src_cnt;
 243         int                     dst_cnt;
 244         int                     i;
 245
 246         thread_name = current->comm;
 247
 248         ret = -ENOMEM;
 249
 250         smp_rmb();
 251         chan = thread->chan;
 252         if (thread->type == DMA_MEMCPY)
 253                 src_cnt = dst_cnt = 1;
 254         else if (thread->type == DMA_XOR) {
 255                 src_cnt = xor_sources | 1; /* force odd to ensure dst = src */
 256                 dst_cnt = 1;
 257         } else if (thread->type == DMA_PQ) {
 258                 src_cnt = pq_sources | 1; /* force odd to ensure dst = src */
 259                 dst_cnt = 2;
 260                 for (i = 0; i < src_cnt; i++)
 261                         pq_coefs[i] = 1;
 262         } else
 263                 goto err_srcs;
 264
 265         thread->srcs = kcalloc(src_cnt+1, sizeof(u8 *), GFP_KERNEL);
 266         if (!thread->srcs)
 267                 goto err_srcs;
 268         for (i = 0; i < src_cnt; i++) {
 269                 thread->srcs[i] = kmalloc(test_buf_size, GFP_KERNEL);
 270                 if (!thread->srcs[i])
 271                         goto err_srcbuf;
 272         }
 273         thread->srcs[i] = NULL;
 274
 275         thread->dsts = kcalloc(dst_cnt+1, sizeof(u8 *), GFP_KERNEL);
 276         if (!thread->dsts)
 277                 goto err_dsts;
 278         for (i = 0; i < dst_cnt; i++) {
 279                 thread->dsts[i] = kmalloc(test_buf_size, GFP_KERNEL);
 280                 if (!thread->dsts[i])
 281                         goto err_dstbuf;
 282         }
 283         thread->dsts[i] = NULL;
 284
 285         set_user_nice(current, 10);
 286
 287         flags = DMA_CTRL_ACK | DMA_COMPL_SKIP_DEST_UNMAP | DMA_PREP_INTERRUPT;
 288
 289         while (!kthread_should_stop()
 290                && !(iterations && total_tests >= iterations)) {
 291                 struct dma_device *dev = chan->device;
 292                 struct dma_async_tx_descriptor *tx = NULL;
 293                 dma_addr_t dma_srcs[src_cnt];
 294                 dma_addr_t dma_dsts[dst_cnt];
 295                 struct completion cmp;
 296                 unsigned long tmo = msecs_to_jiffies(3000);
 297                 u8 align = 0;
 298
 299                 total_tests++;
 300
 301                 /* honor alignment restrictions */
 302                 if (thread->type == DMA_MEMCPY)
 303                         align = dev->copy_align;
 304                 else if (thread->type == DMA_XOR)
 305                         align = dev->xor_align;
 306                 else if (thread->type == DMA_PQ)
 307                         align = dev->pq_align;
 308
 309                 if (1 << align > test_buf_size) {
 310                         pr_err("%u-byte buffer too small for %d-byte alignment\n",
 311                                test_buf_size, 1 << align);
 312                         break;
 313                 }
 314
 315                 len = dmatest_random() % test_buf_size + 1;
 316                 len = (len >> align) << align;
 317                 if (!len)
 318                         len = 1 << align;
 319                 src_off = dmatest_random() % (test_buf_size - len + 1);
 320                 dst_off = dmatest_random() % (test_buf_size - len + 1);
 321
 322                 src_off = (src_off >> align) << align;
 323                 dst_off = (dst_off >> align) << align;
 324
 325                 dmatest_init_srcs(thread->srcs, src_off, len);
 326                 dmatest_init_dsts(thread->dsts, dst_off, len);
 327
 328                 for (i = 0; i < src_cnt; i++) {
 329                         u8 *buf = thread->srcs[i] + src_off;
 330
 331                         dma_srcs[i] = dma_map_single(dev->dev, buf, len,
 332                                                      DMA_TO_DEVICE);
 333                 }
 334                 /* map with DMA_BIDIRECTIONAL to force writeback/invalidate */
 335                 for (i = 0; i < dst_cnt; i++) {
 336                         dma_dsts[i] = dma_map_single(dev->dev, thread->dsts[i],
 337                                                      test_buf_size,
 338                                                      DMA_BIDIRECTIONAL);
 339                 }
 340
 341
 342                 if (thread->type == DMA_MEMCPY)
 343                         tx = dev->device_prep_dma_memcpy(chan,
 344                                                          dma_dsts[0] + dst_off,
 345                                                          dma_srcs[0], len,
 346                                                          flags);
 347                 else if (thread->type == DMA_XOR)
 348                         tx = dev->device_prep_dma_xor(chan,
 349                                                       dma_dsts[0] + dst_off,
 350                                                       dma_srcs, src_cnt,
 351                                                       len, flags);
 352                 else if (thread->type == DMA_PQ) {
 353                         dma_addr_t dma_pq[dst_cnt];
 354
 355                         for (i = 0; i < dst_cnt; i++)
 356                                 dma_pq[i] = dma_dsts[i] + dst_off;
 357                         tx = dev->device_prep_dma_pq(chan, dma_pq, dma_srcs,
 358                                                      src_cnt, pq_coefs,
 359                                                      len, flags);
 360                 }
 361
 362                 if (!tx) {
 363                         for (i = 0; i < src_cnt; i++)
 364                                 dma_unmap_single(dev->dev, dma_srcs[i], len,
 365                                                  DMA_TO_DEVICE);
 366                         for (i = 0; i < dst_cnt; i++)
 367                                 dma_unmap_single(dev->dev, dma_dsts[i],
 368                                                  test_buf_size,
 369                                                  DMA_BIDIRECTIONAL);
 370                         pr_warning("%s: #%u: prep error with src_off=0x%x "
 371                                         "dst_off=0x%x len=0x%x\n",
 372                                         thread_name, total_tests - 1,
 373                                         src_off, dst_off, len);
 374                         msleep(100);
 375                         failed_tests++;
 376                         continue;
 377                 }
 378
 379                 init_completion(&cmp);
 380                 tx->callback = dmatest_callback;
 381                 tx->callback_param = &cmp;
 382                 cookie = tx->tx_submit(tx);
 383
 384                 if (dma_submit_error(cookie)) {
 385                         pr_warning("%s: #%u: submit error %d with src_off=0x%x "
 386                                         "dst_off=0x%x len=0x%x\n",
 387                                         thread_name, total_tests - 1, cookie,
 388                                         src_off, dst_off, len);
 389                         msleep(100);
 390                         failed_tests++;
 391                         continue;
 392                 }
 393                 dma_async_issue_pending(chan);
 394
 395                 tmo = wait_for_completion_timeout(&cmp, tmo);
 396                 status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
 397
 398                 if (tmo == 0) {
 399                         pr_warning("%s: #%u: test timed out\n",
 400                                    thread_name, total_tests - 1);
 401                         failed_tests++;
 402                         continue;
 403                 } else if (status != DMA_SUCCESS) {
 404                         pr_warning("%s: #%u: got completion callback,"
 405                                    " but status is \'%s\'\n",
 406                                    thread_name, total_tests - 1,
 407                                    status == DMA_ERROR ? "error" : "in progress");
 408                         failed_tests++;
 409                         continue;
 410                 }
 411
 412                 /* Unmap by myself (see DMA_COMPL_SKIP_DEST_UNMAP above) */
 413                 for (i = 0; i < dst_cnt; i++)
 414                         dma_unmap_single(dev->dev, dma_dsts[i], test_buf_size,
 415                                          DMA_BIDIRECTIONAL);
 416
 417                 error_count = 0;
 418
 419                 pr_debug("%s: verifying source buffer...\n", thread_name);
 420                 error_count += dmatest_verify(thread->srcs, 0, src_off,
 421                                 0, PATTERN_SRC, true);
 422                 error_count += dmatest_verify(thread->srcs, src_off,
 423                                 src_off + len, src_off,
 424                                 PATTERN_SRC | PATTERN_COPY, true);
 425                 error_count += dmatest_verify(thread->srcs, src_off + len,
 426                                 test_buf_size, src_off + len,
 427                                 PATTERN_SRC, true);
 428
 429                 pr_debug("%s: verifying dest buffer...\n",
 430                                 thread->task->comm);
 431                 error_count += dmatest_verify(thread->dsts, 0, dst_off,
 432                                 0, PATTERN_DST, false);
 433                 error_count += dmatest_verify(thread->dsts, dst_off,
 434                                 dst_off + len, src_off,
 435                                 PATTERN_SRC | PATTERN_COPY, false);
 436                 error_count += dmatest_verify(thread->dsts, dst_off + len,
 437                                 test_buf_size, dst_off + len,
 438                                 PATTERN_DST, false);
 439
 440                 if (error_count) {
 441                         pr_warning("%s: #%u: %u errors with "
 442                                 "src_off=0x%x dst_off=0x%x len=0x%x\n",
 443                                 thread_name, total_tests - 1, error_count,
 444                                 src_off, dst_off, len);
 445                         failed_tests++;
 446                 } else {
 447                         pr_debug("%s: #%u: No errors with "
 448                                 "src_off=0x%x dst_off=0x%x len=0x%x\n",
 449                                 thread_name, total_tests - 1,
 450                                 src_off, dst_off, len);
 451                 }
 452         }
 453
 454         ret = 0;
 455         for (i = 0; thread->dsts[i]; i++)
 456                 kfree(thread->dsts[i]);
 457 err_dstbuf:
 458         kfree(thread->dsts);
 459 err_dsts:
 460         for (i = 0; thread->srcs[i]; i++)
 461                 kfree(thread->srcs[i]);
 462 err_srcbuf:
 463         kfree(thread->srcs);
 464 err_srcs:
 465         pr_notice("%s: terminating after %u tests, %u failures (status %d)\n",
 466                         thread_name, total_tests, failed_tests, ret);
 467
 468         if (iterations > 0)
 469                 while (!kthread_should_stop()) {
 470                         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wait_dmatest_exit);
 471                         interruptible_sleep_on(&wait_dmatest_exit);
 472                 }
 473
 474         return ret;
 475 }
 476
 477 static void dmatest_cleanup_channel(struct dmatest_chan *dtc)
 478 {
 479         struct dmatest_thread   *thread;
 480         struct dmatest_thread   *_thread;
 481         int                     ret;
 482
 483         list_for_each_entry_safe(thread, _thread, &dtc->threads, node) {
 484                 ret = kthread_stop(thread->task);
 485                 pr_debug("dmatest: thread %s exited with status %d\n",
 486                                 thread->task->comm, ret);
 487                 list_del(&thread->node);
 488                 kfree(thread);
 489         }
 490         kfree(dtc);
 491 }
 492
 493 static int dmatest_add_threads(struct dmatest_chan *dtc, enum dma_transaction_type type)
 494 {
 495         struct dmatest_thread *thread;
 496         struct dma_chan *chan = dtc->chan;
 497         char *op;
 498         unsigned int i;
 499
 500         if (type == DMA_MEMCPY)
 501                 op = "copy";
 502         else if (type == DMA_XOR)
 503                 op = "xor";
 504         else if (type == DMA_PQ)
 505                 op = "pq";
 506         else
 507                 return -EINVAL;
 508
 509         for (i = 0; i < threads_per_chan; i++) {
 510                 thread = kzalloc(sizeof(struct dmatest_thread), GFP_KERNEL);
 511                 if (!thread) {
 512                         pr_warning("dmatest: No memory for %s-%s%u\n",
 513                                    dma_chan_name(chan), op, i);
 514
 515                         break;
 516                 }
 517                 thread->chan = dtc->chan;
 518                 thread->type = type;
 519                 smp_wmb();
 520                 thread->task = kthread_run(dmatest_func, thread, "%s-%s%u",
 521                                 dma_chan_name(chan), op, i);
 522                 if (IS_ERR(thread->task)) {
 523                         pr_warning("dmatest: Failed to run thread %s-%s%u\n",
 524                                         dma_chan_name(chan), op, i);
 525                         kfree(thread);
 526                         break;
 527                 }
 528
 529                 /* srcbuf and dstbuf are allocated by the thread itself */
 530
 531                 list_add_tail(&thread->node, &dtc->threads);
 532         }
 533
 534         return i;
 535 }
 536
 537 static int dmatest_add_channel(struct dma_chan *chan)
 538 {
 539         struct dmatest_chan     *dtc;
 540         struct dma_device       *dma_dev = chan->device;
 541         unsigned int            thread_count = 0;
 542         unsigned int            cnt;
 543
 544         dtc = kmalloc(sizeof(struct dmatest_chan), GFP_KERNEL);
 545         if (!dtc) {
 546                 pr_warning("dmatest: No memory for %s\n", dma_chan_name(chan));
 547                 return -ENOMEM;
 548         }
 549
 550         dtc->chan = chan;
 551         INIT_LIST_HEAD(&dtc->threads);
 552
 553         if (dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask)) {
 554                 cnt = dmatest_add_threads(dtc, DMA_MEMCPY);
 555                 thread_count += cnt > 0 ? cnt : 0;
 556         }
 557         if (dma_has_cap(DMA_XOR, dma_dev->cap_mask)) {
 558                 cnt = dmatest_add_threads(dtc, DMA_XOR);
 559                 thread_count += cnt > 0 ? cnt : 0;
 560         }
 561         if (dma_has_cap(DMA_PQ, dma_dev->cap_mask)) {
 562                 cnt = dmatest_add_threads(dtc, DMA_PQ);
 563                 thread_count += cnt > 0 ?: 0;
 564         }
 565
 566         pr_info("dmatest: Started %u threads using %s\n",
 567                 thread_count, dma_chan_name(chan));
 568
 569         list_add_tail(&dtc->node, &dmatest_channels);
 570         nr_channels++;
 571
 572         return 0;
 573 }
 574
 575 static bool filter(struct dma_chan *chan, void *param)
 576 {
 577         if (!dmatest_match_channel(chan) || !dmatest_match_device(chan->device))
 578                 return false;
 579         else
 580                 return true;
 581 }
 582
 583 static int __init dmatest_init(void)
 584 {
 585         dma_cap_mask_t mask;
 586         struct dma_chan *chan;
 587         int err = 0;
 588
 589         dma_cap_zero(mask);
 590         dma_cap_set(DMA_MEMCPY, mask);
 591         for (;;) {
 592                 chan = dma_request_channel(mask, filter, NULL);
 593                 if (chan) {
 594                         err = dmatest_add_channel(chan);
 595                         if (err) {
 596                                 dma_release_channel(chan);
 597                                 break; /* add_channel failed, punt */
 598                         }
 599                 } else
 600                         break; /* no more channels available */
 601                 if (max_channels && nr_channels >= max_channels)
 602                         break; /* we have all we need */
 603         }
 604
 605         return err;
 606 }
 607 /* when compiled-in wait for drivers to load first */
 608 late_initcall(dmatest_init);
 609
 610 static void __exit dmatest_exit(void)
 611 {
 612         struct dmatest_chan *dtc, *_dtc;
 613         struct dma_chan *chan;
 614
 615         list_for_each_entry_safe(dtc, _dtc, &dmatest_channels, node) {
 616                 list_del(&dtc->node);
 617                 chan = dtc->chan;
 618                 dmatest_cleanup_channel(dtc);
 619                 pr_debug("dmatest: dropped channel %s\n",
 620                          dma_chan_name(chan));
 621                 dma_release_channel(chan);
 622         }
 623 }
 624 module_exit(dmatest_exit);
 625
 626 MODULE_AUTHOR("Haavard Skinnemoen <hskinnemoen@atmel.com>");
 627 MODULE_LICENSE("GPL v2");