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dmatest: check for dma mapping error
[~shefty/rdma-dev.git] / 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/dma-mapping.h>
12 #include <linux/dmaengine.h>
13 #include <linux/freezer.h>
14 #include <linux/init.h>
15 #include <linux/kthread.h>
16 #include <linux/module.h>
17 #include <linux/moduleparam.h>
18 #include <linux/random.h>
19 #include <linux/slab.h>
20 #include <linux/wait.h>
21
22 static unsigned int test_buf_size = 16384;
23 module_param(test_buf_size, uint, S_IRUGO);
24 MODULE_PARM_DESC(test_buf_size, "Size of the memcpy test buffer");
25
26 static char test_channel[20];
27 module_param_string(channel, test_channel, sizeof(test_channel), S_IRUGO);
28 MODULE_PARM_DESC(channel, "Bus ID of the channel to test (default: any)");
29
30 static char test_device[20];
31 module_param_string(device, test_device, sizeof(test_device), S_IRUGO);
32 MODULE_PARM_DESC(device, "Bus ID of the DMA Engine to test (default: any)");
33
34 static unsigned int threads_per_chan = 1;
35 module_param(threads_per_chan, uint, S_IRUGO);
36 MODULE_PARM_DESC(threads_per_chan,
37                 "Number of threads to start per channel (default: 1)");
38
39 static unsigned int max_channels;
40 module_param(max_channels, uint, S_IRUGO);
41 MODULE_PARM_DESC(max_channels,
42                 "Maximum number of channels to use (default: all)");
43
44 static unsigned int iterations;
45 module_param(iterations, uint, S_IRUGO);
46 MODULE_PARM_DESC(iterations,
47                 "Iterations before stopping test (default: infinite)");
48
49 static unsigned int xor_sources = 3;
50 module_param(xor_sources, uint, S_IRUGO);
51 MODULE_PARM_DESC(xor_sources,
52                 "Number of xor source buffers (default: 3)");
53
54 static unsigned int pq_sources = 3;
55 module_param(pq_sources, uint, S_IRUGO);
56 MODULE_PARM_DESC(pq_sources,
57                 "Number of p+q source buffers (default: 3)");
58
59 static int timeout = 3000;
60 module_param(timeout, uint, S_IRUGO);
61 MODULE_PARM_DESC(timeout, "Transfer Timeout in msec (default: 3000), "
62                  "Pass -1 for infinite timeout");
63
64 /*
65  * Initialization patterns. All bytes in the source buffer has bit 7
66  * set, all bytes in the destination buffer has bit 7 cleared.
67  *
68  * Bit 6 is set for all bytes which are to be copied by the DMA
69  * engine. Bit 5 is set for all bytes which are to be overwritten by
70  * the DMA engine.
71  *
72  * The remaining bits are the inverse of a counter which increments by
73  * one for each byte address.
74  */
75 #define PATTERN_SRC             0x80
76 #define PATTERN_DST             0x00
77 #define PATTERN_COPY            0x40
78 #define PATTERN_OVERWRITE       0x20
79 #define PATTERN_COUNT_MASK      0x1f
80
81 struct dmatest_thread {
82         struct list_head        node;
83         struct task_struct      *task;
84         struct dma_chan         *chan;
85         u8                      **srcs;
86         u8                      **dsts;
87         enum dma_transaction_type type;
88 };
89
90 struct dmatest_chan {
91         struct list_head        node;
92         struct dma_chan         *chan;
93         struct list_head        threads;
94 };
95
96 /*
97  * These are protected by dma_list_mutex since they're only used by
98  * the DMA filter function callback
99  */
100 static LIST_HEAD(dmatest_channels);
101 static unsigned int nr_channels;
102
103 static bool dmatest_match_channel(struct dma_chan *chan)
104 {
105         if (test_channel[0] == '\0')
106                 return true;
107         return strcmp(dma_chan_name(chan), test_channel) == 0;
108 }
109
110 static bool dmatest_match_device(struct dma_device *device)
111 {
112         if (test_device[0] == '\0')
113                 return true;
114         return strcmp(dev_name(device->dev), test_device) == 0;
115 }
116
117 static unsigned long dmatest_random(void)
118 {
119         unsigned long buf;
120
121         get_random_bytes(&buf, sizeof(buf));
122         return buf;
123 }
124
125 static void dmatest_init_srcs(u8 **bufs, unsigned int start, unsigned int len)
126 {
127         unsigned int i;
128         u8 *buf;
129
130         for (; (buf = *bufs); bufs++) {
131                 for (i = 0; i < start; i++)
132                         buf[i] = PATTERN_SRC | (~i & PATTERN_COUNT_MASK);
133                 for ( ; i < start + len; i++)
134                         buf[i] = PATTERN_SRC | PATTERN_COPY
135                                 | (~i & PATTERN_COUNT_MASK);
136                 for ( ; i < test_buf_size; i++)
137                         buf[i] = PATTERN_SRC | (~i & PATTERN_COUNT_MASK);
138                 buf++;
139         }
140 }
141
142 static void dmatest_init_dsts(u8 **bufs, unsigned int start, unsigned int len)
143 {
144         unsigned int i;
145         u8 *buf;
146
147         for (; (buf = *bufs); bufs++) {
148                 for (i = 0; i < start; i++)
149                         buf[i] = PATTERN_DST | (~i & PATTERN_COUNT_MASK);
150                 for ( ; i < start + len; i++)
151                         buf[i] = PATTERN_DST | PATTERN_OVERWRITE
152                                 | (~i & PATTERN_COUNT_MASK);
153                 for ( ; i < test_buf_size; i++)
154                         buf[i] = PATTERN_DST | (~i & PATTERN_COUNT_MASK);
155         }
156 }
157
158 static void dmatest_mismatch(u8 actual, u8 pattern, unsigned int index,
159                 unsigned int counter, bool is_srcbuf)
160 {
161         u8              diff = actual ^ pattern;
162         u8              expected = pattern | (~counter & PATTERN_COUNT_MASK);
163         const char      *thread_name = current->comm;
164
165         if (is_srcbuf)
166                 pr_warning("%s: srcbuf[0x%x] overwritten!"
167                                 " Expected %02x, got %02x\n",
168                                 thread_name, index, expected, actual);
169         else if ((pattern & PATTERN_COPY)
170                         && (diff & (PATTERN_COPY | PATTERN_OVERWRITE)))
171                 pr_warning("%s: dstbuf[0x%x] not copied!"
172                                 " Expected %02x, got %02x\n",
173                                 thread_name, index, expected, actual);
174         else if (diff & PATTERN_SRC)
175                 pr_warning("%s: dstbuf[0x%x] was copied!"
176                                 " Expected %02x, got %02x\n",
177                                 thread_name, index, expected, actual);
178         else
179                 pr_warning("%s: dstbuf[0x%x] mismatch!"
180                                 " Expected %02x, got %02x\n",
181                                 thread_name, index, expected, actual);
182 }
183
184 static unsigned int dmatest_verify(u8 **bufs, unsigned int start,
185                 unsigned int end, unsigned int counter, u8 pattern,
186                 bool is_srcbuf)
187 {
188         unsigned int i;
189         unsigned int error_count = 0;
190         u8 actual;
191         u8 expected;
192         u8 *buf;
193         unsigned int counter_orig = counter;
194
195         for (; (buf = *bufs); bufs++) {
196                 counter = counter_orig;
197                 for (i = start; i < end; i++) {
198                         actual = buf[i];
199                         expected = pattern | (~counter & PATTERN_COUNT_MASK);
200                         if (actual != expected) {
201                                 if (error_count < 32)
202                                         dmatest_mismatch(actual, pattern, i,
203                                                          counter, is_srcbuf);
204                                 error_count++;
205                         }
206                         counter++;
207                 }
208         }
209
210         if (error_count > 32)
211                 pr_warning("%s: %u errors suppressed\n",
212                         current->comm, error_count - 32);
213
214         return error_count;
215 }
216
217 /* poor man's completion - we want to use wait_event_freezable() on it */
218 struct dmatest_done {
219         bool                    done;
220         wait_queue_head_t       *wait;
221 };
222
223 static void dmatest_callback(void *arg)
224 {
225         struct dmatest_done *done = arg;
226
227         done->done = true;
228         wake_up_all(done->wait);
229 }
230
231 static inline void unmap_src(struct device *dev, dma_addr_t *addr, size_t len,
232                              unsigned int count)
233 {
234         while (count--)
235                 dma_unmap_single(dev, addr[count], len, DMA_TO_DEVICE);
236 }
237
238 static inline void unmap_dst(struct device *dev, dma_addr_t *addr, size_t len,
239                              unsigned int count)
240 {
241         while (count--)
242                 dma_unmap_single(dev, addr[count], len, DMA_BIDIRECTIONAL);
243 }
244
245 /*
246  * This function repeatedly tests DMA transfers of various lengths and
247  * offsets for a given operation type until it is told to exit by
248  * kthread_stop(). There may be multiple threads running this function
249  * in parallel for a single channel, and there may be multiple channels
250  * being tested in parallel.
251  *
252  * Before each test, the source and destination buffer is initialized
253  * with a known pattern. This pattern is different depending on
254  * whether it's in an area which is supposed to be copied or
255  * overwritten, and different in the source and destination buffers.
256  * So if the DMA engine doesn't copy exactly what we tell it to copy,
257  * we'll notice.
258  */
259 static int dmatest_func(void *data)
260 {
261         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(done_wait);
262         struct dmatest_thread   *thread = data;
263         struct dmatest_done     done = { .wait = &done_wait };
264         struct dma_chan         *chan;
265         const char              *thread_name;
266         unsigned int            src_off, dst_off, len;
267         unsigned int            error_count;
268         unsigned int            failed_tests = 0;
269         unsigned int            total_tests = 0;
270         dma_cookie_t            cookie;
271         enum dma_status         status;
272         enum dma_ctrl_flags     flags;
273         u8                      pq_coefs[pq_sources + 1];
274         int                     ret;
275         int                     src_cnt;
276         int                     dst_cnt;
277         int                     i;
278
279         thread_name = current->comm;
280         set_freezable();
281
282         ret = -ENOMEM;
283
284         smp_rmb();
285         chan = thread->chan;
286         if (thread->type == DMA_MEMCPY)
287                 src_cnt = dst_cnt = 1;
288         else if (thread->type == DMA_XOR) {
289                 src_cnt = xor_sources | 1; /* force odd to ensure dst = src */
290                 dst_cnt = 1;
291         } else if (thread->type == DMA_PQ) {
292                 src_cnt = pq_sources | 1; /* force odd to ensure dst = src */
293                 dst_cnt = 2;
294                 for (i = 0; i < src_cnt; i++)
295                         pq_coefs[i] = 1;
296         } else
297                 goto err_srcs;
298
299         thread->srcs = kcalloc(src_cnt+1, sizeof(u8 *), GFP_KERNEL);
300         if (!thread->srcs)
301                 goto err_srcs;
302         for (i = 0; i < src_cnt; i++) {
303                 thread->srcs[i] = kmalloc(test_buf_size, GFP_KERNEL);
304                 if (!thread->srcs[i])
305                         goto err_srcbuf;
306         }
307         thread->srcs[i] = NULL;
308
309         thread->dsts = kcalloc(dst_cnt+1, sizeof(u8 *), GFP_KERNEL);
310         if (!thread->dsts)
311                 goto err_dsts;
312         for (i = 0; i < dst_cnt; i++) {
313                 thread->dsts[i] = kmalloc(test_buf_size, GFP_KERNEL);
314                 if (!thread->dsts[i])
315                         goto err_dstbuf;
316         }
317         thread->dsts[i] = NULL;
318
319         set_user_nice(current, 10);
320
321         /*
322          * src buffers are freed by the DMAEngine code with dma_unmap_single()
323          * dst buffers are freed by ourselves below
324          */
325         flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT
326               | DMA_COMPL_SKIP_DEST_UNMAP | DMA_COMPL_SRC_UNMAP_SINGLE;
327
328         while (!kthread_should_stop()
329                && !(iterations && total_tests >= iterations)) {
330                 struct dma_device *dev = chan->device;
331                 struct dma_async_tx_descriptor *tx = NULL;
332                 dma_addr_t dma_srcs[src_cnt];
333                 dma_addr_t dma_dsts[dst_cnt];
334                 u8 align = 0;
335
336                 total_tests++;
337
338                 /* honor alignment restrictions */
339                 if (thread->type == DMA_MEMCPY)
340                         align = dev->copy_align;
341                 else if (thread->type == DMA_XOR)
342                         align = dev->xor_align;
343                 else if (thread->type == DMA_PQ)
344                         align = dev->pq_align;
345
346                 if (1 << align > test_buf_size) {
347                         pr_err("%u-byte buffer too small for %d-byte alignment\n",
348                                test_buf_size, 1 << align);
349                         break;
350                 }
351
352                 len = dmatest_random() % test_buf_size + 1;
353                 len = (len >> align) << align;
354                 if (!len)
355                         len = 1 << align;
356                 src_off = dmatest_random() % (test_buf_size - len + 1);
357                 dst_off = dmatest_random() % (test_buf_size - len + 1);
358
359                 src_off = (src_off >> align) << align;
360                 dst_off = (dst_off >> align) << align;
361
362                 dmatest_init_srcs(thread->srcs, src_off, len);
363                 dmatest_init_dsts(thread->dsts, dst_off, len);
364
365                 for (i = 0; i < src_cnt; i++) {
366                         u8 *buf = thread->srcs[i] + src_off;
367
368                         dma_srcs[i] = dma_map_single(dev->dev, buf, len,
369                                                      DMA_TO_DEVICE);
370                         ret = dma_mapping_error(dev->dev, dma_srcs[i]);
371                         if (ret) {
372                                 unmap_src(dev->dev, dma_srcs, len, i);
373                                 pr_warn("%s: #%u: mapping error %d with "
374                                         "src_off=0x%x len=0x%x\n",
375                                         thread_name, total_tests - 1, ret,
376                                         src_off, len);
377                                 failed_tests++;
378                                 continue;
379                         }
380                 }
381                 /* map with DMA_BIDIRECTIONAL to force writeback/invalidate */
382                 for (i = 0; i < dst_cnt; i++) {
383                         dma_dsts[i] = dma_map_single(dev->dev, thread->dsts[i],
384                                                      test_buf_size,
385                                                      DMA_BIDIRECTIONAL);
386                         ret = dma_mapping_error(dev->dev, dma_dsts[i]);
387                         if (ret) {
388                                 unmap_src(dev->dev, dma_srcs, len, src_cnt);
389                                 unmap_dst(dev->dev, dma_dsts, test_buf_size, i);
390                                 pr_warn("%s: #%u: mapping error %d with "
391                                         "dst_off=0x%x len=0x%x\n",
392                                         thread_name, total_tests - 1, ret,
393                                         dst_off, test_buf_size);
394                                 failed_tests++;
395                                 continue;
396                         }
397                 }
398
399                 if (thread->type == DMA_MEMCPY)
400                         tx = dev->device_prep_dma_memcpy(chan,
401                                                          dma_dsts[0] + dst_off,
402                                                          dma_srcs[0], len,
403                                                          flags);
404                 else if (thread->type == DMA_XOR)
405                         tx = dev->device_prep_dma_xor(chan,
406                                                       dma_dsts[0] + dst_off,
407                                                       dma_srcs, src_cnt,
408                                                       len, flags);
409                 else if (thread->type == DMA_PQ) {
410                         dma_addr_t dma_pq[dst_cnt];
411
412                         for (i = 0; i < dst_cnt; i++)
413                                 dma_pq[i] = dma_dsts[i] + dst_off;
414                         tx = dev->device_prep_dma_pq(chan, dma_pq, dma_srcs,
415                                                      src_cnt, pq_coefs,
416                                                      len, flags);
417                 }
418
419                 if (!tx) {
420                         unmap_src(dev->dev, dma_srcs, len, src_cnt);
421                         unmap_dst(dev->dev, dma_dsts, test_buf_size, dst_cnt);
422                         pr_warning("%s: #%u: prep error with src_off=0x%x "
423                                         "dst_off=0x%x len=0x%x\n",
424                                         thread_name, total_tests - 1,
425                                         src_off, dst_off, len);
426                         msleep(100);
427                         failed_tests++;
428                         continue;
429                 }
430
431                 done.done = false;
432                 tx->callback = dmatest_callback;
433                 tx->callback_param = &done;
434                 cookie = tx->tx_submit(tx);
435
436                 if (dma_submit_error(cookie)) {
437                         pr_warning("%s: #%u: submit error %d with src_off=0x%x "
438                                         "dst_off=0x%x len=0x%x\n",
439                                         thread_name, total_tests - 1, cookie,
440                                         src_off, dst_off, len);
441                         msleep(100);
442                         failed_tests++;
443                         continue;
444                 }
445                 dma_async_issue_pending(chan);
446
447                 wait_event_freezable_timeout(done_wait, done.done,
448                                              msecs_to_jiffies(timeout));
449
450                 status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
451
452                 if (!done.done) {
453                         /*
454                          * We're leaving the timed out dma operation with
455                          * dangling pointer to done_wait.  To make this
456                          * correct, we'll need to allocate wait_done for
457                          * each test iteration and perform "who's gonna
458                          * free it this time?" dancing.  For now, just
459                          * leave it dangling.
460                          */
461                         pr_warning("%s: #%u: test timed out\n",
462                                    thread_name, total_tests - 1);
463                         failed_tests++;
464                         continue;
465                 } else if (status != DMA_SUCCESS) {
466                         pr_warning("%s: #%u: got completion callback,"
467                                    " but status is \'%s\'\n",
468                                    thread_name, total_tests - 1,
469                                    status == DMA_ERROR ? "error" : "in progress");
470                         failed_tests++;
471                         continue;
472                 }
473
474                 /* Unmap by myself (see DMA_COMPL_SKIP_DEST_UNMAP above) */
475                 unmap_dst(dev->dev, dma_dsts, test_buf_size, dst_cnt);
476
477                 error_count = 0;
478
479                 pr_debug("%s: verifying source buffer...\n", thread_name);
480                 error_count += dmatest_verify(thread->srcs, 0, src_off,
481                                 0, PATTERN_SRC, true);
482                 error_count += dmatest_verify(thread->srcs, src_off,
483                                 src_off + len, src_off,
484                                 PATTERN_SRC | PATTERN_COPY, true);
485                 error_count += dmatest_verify(thread->srcs, src_off + len,
486                                 test_buf_size, src_off + len,
487                                 PATTERN_SRC, true);
488
489                 pr_debug("%s: verifying dest buffer...\n",
490                                 thread->task->comm);
491                 error_count += dmatest_verify(thread->dsts, 0, dst_off,
492                                 0, PATTERN_DST, false);
493                 error_count += dmatest_verify(thread->dsts, dst_off,
494                                 dst_off + len, src_off,
495                                 PATTERN_SRC | PATTERN_COPY, false);
496                 error_count += dmatest_verify(thread->dsts, dst_off + len,
497                                 test_buf_size, dst_off + len,
498                                 PATTERN_DST, false);
499
500                 if (error_count) {
501                         pr_warning("%s: #%u: %u errors with "
502                                 "src_off=0x%x dst_off=0x%x len=0x%x\n",
503                                 thread_name, total_tests - 1, error_count,
504                                 src_off, dst_off, len);
505                         failed_tests++;
506                 } else {
507                         pr_debug("%s: #%u: No errors with "
508                                 "src_off=0x%x dst_off=0x%x len=0x%x\n",
509                                 thread_name, total_tests - 1,
510                                 src_off, dst_off, len);
511                 }
512         }
513
514         ret = 0;
515         for (i = 0; thread->dsts[i]; i++)
516                 kfree(thread->dsts[i]);
517 err_dstbuf:
518         kfree(thread->dsts);
519 err_dsts:
520         for (i = 0; thread->srcs[i]; i++)
521                 kfree(thread->srcs[i]);
522 err_srcbuf:
523         kfree(thread->srcs);
524 err_srcs:
525         pr_notice("%s: terminating after %u tests, %u failures (status %d)\n",
526                         thread_name, total_tests, failed_tests, ret);
527
528         /* terminate all transfers on specified channels */
529         chan->device->device_control(chan, DMA_TERMINATE_ALL, 0);
530         if (iterations > 0)
531                 while (!kthread_should_stop()) {
532                         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wait_dmatest_exit);
533                         interruptible_sleep_on(&wait_dmatest_exit);
534                 }
535
536         return ret;
537 }
538
539 static void dmatest_cleanup_channel(struct dmatest_chan *dtc)
540 {
541         struct dmatest_thread   *thread;
542         struct dmatest_thread   *_thread;
543         int                     ret;
544
545         list_for_each_entry_safe(thread, _thread, &dtc->threads, node) {
546                 ret = kthread_stop(thread->task);
547                 pr_debug("dmatest: thread %s exited with status %d\n",
548                                 thread->task->comm, ret);
549                 list_del(&thread->node);
550                 kfree(thread);
551         }
552
553         /* terminate all transfers on specified channels */
554         dtc->chan->device->device_control(dtc->chan, DMA_TERMINATE_ALL, 0);
555
556         kfree(dtc);
557 }
558
559 static int dmatest_add_threads(struct dmatest_chan *dtc, enum dma_transaction_type type)
560 {
561         struct dmatest_thread *thread;
562         struct dma_chan *chan = dtc->chan;
563         char *op;
564         unsigned int i;
565
566         if (type == DMA_MEMCPY)
567                 op = "copy";
568         else if (type == DMA_XOR)
569                 op = "xor";
570         else if (type == DMA_PQ)
571                 op = "pq";
572         else
573                 return -EINVAL;
574
575         for (i = 0; i < threads_per_chan; i++) {
576                 thread = kzalloc(sizeof(struct dmatest_thread), GFP_KERNEL);
577                 if (!thread) {
578                         pr_warning("dmatest: No memory for %s-%s%u\n",
579                                    dma_chan_name(chan), op, i);
580
581                         break;
582                 }
583                 thread->chan = dtc->chan;
584                 thread->type = type;
585                 smp_wmb();
586                 thread->task = kthread_run(dmatest_func, thread, "%s-%s%u",
587                                 dma_chan_name(chan), op, i);
588                 if (IS_ERR(thread->task)) {
589                         pr_warning("dmatest: Failed to run thread %s-%s%u\n",
590                                         dma_chan_name(chan), op, i);
591                         kfree(thread);
592                         break;
593                 }
594
595                 /* srcbuf and dstbuf are allocated by the thread itself */
596
597                 list_add_tail(&thread->node, &dtc->threads);
598         }
599
600         return i;
601 }
602
603 static int dmatest_add_channel(struct dma_chan *chan)
604 {
605         struct dmatest_chan     *dtc;
606         struct dma_device       *dma_dev = chan->device;
607         unsigned int            thread_count = 0;
608         int cnt;
609
610         dtc = kmalloc(sizeof(struct dmatest_chan), GFP_KERNEL);
611         if (!dtc) {
612                 pr_warning("dmatest: No memory for %s\n", dma_chan_name(chan));
613                 return -ENOMEM;
614         }
615
616         dtc->chan = chan;
617         INIT_LIST_HEAD(&dtc->threads);
618
619         if (dma_has_cap(DMA_MEMCPY, dma_dev->cap_mask)) {
620                 cnt = dmatest_add_threads(dtc, DMA_MEMCPY);
621                 thread_count += cnt > 0 ? cnt : 0;
622         }
623         if (dma_has_cap(DMA_XOR, dma_dev->cap_mask)) {
624                 cnt = dmatest_add_threads(dtc, DMA_XOR);
625                 thread_count += cnt > 0 ? cnt : 0;
626         }
627         if (dma_has_cap(DMA_PQ, dma_dev->cap_mask)) {
628                 cnt = dmatest_add_threads(dtc, DMA_PQ);
629                 thread_count += cnt > 0 ? cnt : 0;
630         }
631
632         pr_info("dmatest: Started %u threads using %s\n",
633                 thread_count, dma_chan_name(chan));
634
635         list_add_tail(&dtc->node, &dmatest_channels);
636         nr_channels++;
637
638         return 0;
639 }
640
641 static bool filter(struct dma_chan *chan, void *param)
642 {
643         if (!dmatest_match_channel(chan) || !dmatest_match_device(chan->device))
644                 return false;
645         else
646                 return true;
647 }
648
649 static int __init dmatest_init(void)
650 {
651         dma_cap_mask_t mask;
652         struct dma_chan *chan;
653         int err = 0;
654
655         dma_cap_zero(mask);
656         dma_cap_set(DMA_MEMCPY, mask);
657         for (;;) {
658                 chan = dma_request_channel(mask, filter, NULL);
659                 if (chan) {
660                         err = dmatest_add_channel(chan);
661                         if (err) {
662                                 dma_release_channel(chan);
663                                 break; /* add_channel failed, punt */
664                         }
665                 } else
666                         break; /* no more channels available */
667                 if (max_channels && nr_channels >= max_channels)
668                         break; /* we have all we need */
669         }
670
671         return err;
672 }
673 /* when compiled-in wait for drivers to load first */
674 late_initcall(dmatest_init);
675
676 static void __exit dmatest_exit(void)
677 {
678         struct dmatest_chan *dtc, *_dtc;
679         struct dma_chan *chan;
680
681         list_for_each_entry_safe(dtc, _dtc, &dmatest_channels, node) {
682                 list_del(&dtc->node);
683                 chan = dtc->chan;
684                 dmatest_cleanup_channel(dtc);
685                 pr_debug("dmatest: dropped channel %s\n",
686                          dma_chan_name(chan));
687                 dma_release_channel(chan);
688         }
689 }
690 module_exit(dmatest_exit);
691
692 MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
693 MODULE_LICENSE("GPL v2");