1 /*
2 * Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License as published by the Free
6 * Software Foundation; either version 2 of the License, or (at your option)
7 * any later version.
8 *
9 * This program is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
12 * more details.
13 *
14 * You should have received a copy of the GNU General Public License along with
15 * this program; if not, write to the Free Software Foundation, Inc., 59
16 * Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * The full GNU General Public License is included in this distribution in the
19 * file called COPYING.
20 */
21
22 /*
23 * This code implements the DMA subsystem. It provides a HW-neutral interface
24 * for other kernel code to use asynchronous memory copy capabilities,
25 * if present, and allows different HW DMA drivers to register as providing
26 * this capability.
27 *
28 * Due to the fact we are accelerating what is already a relatively fast
29 * operation, the code goes to great lengths to avoid additional overhead,
30 * such as locking.
31 *
32 * LOCKING:
33 *
34 * The subsystem keeps two global lists, dma_device_list and dma_client_list.
35 * Both of these are protected by a mutex, dma_list_mutex.
36 *
37 * Each device has a channels list, which runs unlocked but is never modified
38 * once the device is registered, it's just setup by the driver.
39 *
40 * Each client is responsible for keeping track of the channels it uses. See
41 * the definition of dma_event_callback in dmaengine.h.
42 *
43 * Each device has a kref, which is initialized to 1 when the device is
44 * registered. A kref_get is done for each device registered. When the
45 * device is released, the coresponding kref_put is done in the release
46 * method. Every time one of the device's channels is allocated to a client,
47 * a kref_get occurs. When the channel is freed, the coresponding kref_put
48 * happens. The device's release function does a completion, so
49 * unregister_device does a remove event, device_unregister, a kref_put
50 * for the first reference, then waits on the completion for all other
51 * references to finish.
52 *
53 * Each channel has an open-coded implementation of Rusty Russell's "bigref,"
54 * with a kref and a per_cpu local_t. A dma_chan_get is called when a client
55 * signals that it wants to use a channel, and dma_chan_put is called when
56 * a channel is removed or a client using it is unregesitered. A client can
57 * take extra references per outstanding transaction, as is the case with
58 * the NET DMA client. The release function does a kref_put on the device.
59 * -ChrisL, DanW
60 */
61
62 #include <linux/init.h>
63 #include <linux/module.h>
64 #include <linux/mm.h>
65 #include <linux/device.h>
66 #include <linux/dmaengine.h>
67 #include <linux/hardirq.h>
68 #include <linux/spinlock.h>
69 #include <linux/percpu.h>
70 #include <linux/rcupdate.h>
71 #include <linux/mutex.h>
72 #include <linux/jiffies.h>
73
74 static DEFINE_MUTEX(dma_list_mutex);
75 static LIST_HEAD(dma_device_list);
76 static LIST_HEAD(dma_client_list);
77
78 /* --- sysfs implementation --- */
79
80 static ssize_t show_memcpy_count(struct device *dev, struct device_attribute *attr, char *buf)
81 {
82 struct dma_chan *chan = to_dma_chan(dev);
83 unsigned long count = 0;
84 int i;
85
86 for_each_possible_cpu(i)
87 count += per_cpu_ptr(chan->local, i)->memcpy_count;
88
89 return sprintf(buf, "%lu\n", count);
90 }
91
92 static ssize_t show_bytes_transferred(struct device *dev, struct device_attribute *attr,
93 char *buf)
94 {
95 struct dma_chan *chan = to_dma_chan(dev);
96 unsigned long count = 0;
97 int i;
98
99 for_each_possible_cpu(i)
100 count += per_cpu_ptr(chan->local, i)->bytes_transferred;
101
102 return sprintf(buf, "%lu\n", count);
103 }
104
105 static ssize_t show_in_use(struct device *dev, struct device_attribute *attr, char *buf)
106 {
107 struct dma_chan *chan = to_dma_chan(dev);
108 int in_use = 0;
109
110 if (unlikely(chan->slow_ref) &&
111 atomic_read(&chan->refcount.refcount) > 1)
112 in_use = 1;
113 else {
114 if (local_read(&(per_cpu_ptr(chan->local,
115 get_cpu())->refcount)) > 0)
116 in_use = 1;
117 put_cpu();
118 }
119
120 return sprintf(buf, "%d\n", in_use);
121 }
122
123 static struct device_attribute dma_attrs[] = {
124 __ATTR(memcpy_count, S_IRUGO, show_memcpy_count, NULL),
125 __ATTR(bytes_transferred, S_IRUGO, show_bytes_transferred, NULL),
126 __ATTR(in_use, S_IRUGO, show_in_use, NULL),
127 __ATTR_NULL
128 };
129
130 static void dma_async_device_cleanup(struct kref *kref);
131
132 static void dma_dev_release(struct device *dev)
133 {
134 struct dma_chan *chan = to_dma_chan(dev);
135 kref_put(&chan->device->refcount, dma_async_device_cleanup);
136 }
137
138 static struct class dma_devclass = {
139 .name = "dma",
140 .dev_attrs = dma_attrs,
141 .dev_release = dma_dev_release,
142 };
143
144 /* --- client and device registration --- */
145
146 #define dma_chan_satisfies_mask(chan, mask) \
147 __dma_chan_satisfies_mask((chan), &(mask))
148 static int
149 __dma_chan_satisfies_mask(struct dma_chan *chan, dma_cap_mask_t *want)
150 {
151 dma_cap_mask_t has;
152
153 bitmap_and(has.bits, want->bits, chan->device->cap_mask.bits,
154 DMA_TX_TYPE_END);
155 return bitmap_equal(want->bits, has.bits, DMA_TX_TYPE_END);
156 }
157
158 /**
159 * dma_client_chan_alloc - try to allocate channels to a client
160 * @client: &dma_client
161 *
162 * Called with dma_list_mutex held.
163 */
164 static void dma_client_chan_alloc(struct dma_client *client)
165 {
166 struct dma_device *device;
167 struct dma_chan *chan;
168 int desc; /* allocated descriptor count */
169 enum dma_state_client ack;
170
171 /* Find a channel */
172 list_for_each_entry(device, &dma_device_list, global_node)
173 list_for_each_entry(chan, &device->channels, device_node) {
174 if (!dma_chan_satisfies_mask(chan, client->cap_mask))
175 continue;
176
177 desc = chan->device->device_alloc_chan_resources(chan);
178 if (desc >= 0) {
179 ack = client->event_callback(client,
180 chan,
181 DMA_RESOURCE_AVAILABLE);
182
183 /* we are done once this client rejects
184 * an available resource
185 */
186 if (ack == DMA_ACK)
187 dma_chan_get(chan);
188 else if (ack == DMA_NAK)
189 return;
190 }
191 }
192 }
193
194 enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie)
195 {
196 enum dma_status status;
197 unsigned long dma_sync_wait_timeout = jiffies + msecs_to_jiffies(5000);
198
199 dma_async_issue_pending(chan);
200 do {
201 status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
202 if (time_after_eq(jiffies, dma_sync_wait_timeout)) {
203 printk(KERN_ERR "dma_sync_wait_timeout!\n");
204 return DMA_ERROR;
205 }
206 } while (status == DMA_IN_PROGRESS);
207
208 return status;
209 }
210 EXPORT_SYMBOL(dma_sync_wait);
211
212 /**
213 * dma_chan_cleanup - release a DMA channel's resources
214 * @kref: kernel reference structure that contains the DMA channel device
215 */
216 void dma_chan_cleanup(struct kref *kref)
217 {
218 struct dma_chan *chan = container_of(kref, struct dma_chan, refcount);
219 chan->device->device_free_chan_resources(chan);
220 kref_put(&chan->device->refcount, dma_async_device_cleanup);
221 }
222 EXPORT_SYMBOL(dma_chan_cleanup);
223
224 static void dma_chan_free_rcu(struct rcu_head *rcu)
225 {
226 struct dma_chan *chan = container_of(rcu, struct dma_chan, rcu);
227 int bias = 0x7FFFFFFF;
228 int i;
229 for_each_possible_cpu(i)
230 bias -= local_read(&per_cpu_ptr(chan->local, i)->refcount);
231 atomic_sub(bias, &chan->refcount.refcount);
232 kref_put(&chan->refcount, dma_chan_cleanup);
233 }
234
235 static void dma_chan_release(struct dma_chan *chan)
236 {
237 atomic_add(0x7FFFFFFF, &chan->refcount.refcount);
238 chan->slow_ref = 1;
239 call_rcu(&chan->rcu, dma_chan_free_rcu);
240 }
241
242 /**
243 * dma_chans_notify_available - broadcast available channels to the clients
244 */
245 static void dma_clients_notify_available(void)
246 {
247 struct dma_client *client;
248
249 mutex_lock(&dma_list_mutex);
250
251 list_for_each_entry(client, &dma_client_list, global_node)
252 dma_client_chan_alloc(client);
253
254 mutex_unlock(&dma_list_mutex);
255 }
256
257 /**
258 * dma_chans_notify_available - tell the clients that a channel is going away
259 * @chan: channel on its way out
260 */
261 static void dma_clients_notify_removed(struct dma_chan *chan)
262 {
263 struct dma_client *client;
264 enum dma_state_client ack;
265
266 mutex_lock(&dma_list_mutex);
267
268 list_for_each_entry(client, &dma_client_list, global_node) {
269 ack = client->event_callback(client, chan,
270 DMA_RESOURCE_REMOVED);
271
272 /* client was holding resources for this channel so
273 * free it
274 */
275 if (ack == DMA_ACK)
276 dma_chan_put(chan);
277 }
278
279 mutex_unlock(&dma_list_mutex);
280 }
281
282 /**
283 * dma_async_client_register - register a &dma_client
284 * @client: ptr to a client structure with valid 'event_callback' and 'cap_mask'
285 */
286 void dma_async_client_register(struct dma_client *client)
287 {
288 mutex_lock(&dma_list_mutex);
289 list_add_tail(&client->global_node, &dma_client_list);
290 mutex_unlock(&dma_list_mutex);
291 }
292 EXPORT_SYMBOL(dma_async_client_register);
293
294 /**
295 * dma_async_client_unregister - unregister a client and free the &dma_client
296 * @client: &dma_client to free
297 *
298 * Force frees any allocated DMA channels, frees the &dma_client memory
299 */
300 void dma_async_client_unregister(struct dma_client *client)
301 {
302 struct dma_device *device;
303 struct dma_chan *chan;
304 enum dma_state_client ack;
305
306 if (!client)
307 return;
308
309 mutex_lock(&dma_list_mutex);
310 /* free all channels the client is holding */
311 list_for_each_entry(device, &dma_device_list, global_node)
312 list_for_each_entry(chan, &device->channels, device_node) {
313 ack = client->event_callback(client, chan,
314 DMA_RESOURCE_REMOVED);
315
316 if (ack == DMA_ACK)
317 dma_chan_put(chan);
318 }
319
320 list_del(&client->global_node);
321 mutex_unlock(&dma_list_mutex);
322 }
323 EXPORT_SYMBOL(dma_async_client_unregister);
324
325 /**
326 * dma_async_client_chan_request - send all available channels to the
327 * client that satisfy the capability mask
328 * @client - requester
329 */
330 void dma_async_client_chan_request(struct dma_client *client)
331 {
332 mutex_lock(&dma_list_mutex);
333 dma_client_chan_alloc(client);
334 mutex_unlock(&dma_list_mutex);
335 }
336 EXPORT_SYMBOL(dma_async_client_chan_request);
337
338 /**
339 * dma_async_device_register - registers DMA devices found
340 * @device: &dma_device
341 */
342 int dma_async_device_register(struct dma_device *device)
343 {
344 static int id;
345 int chancnt = 0, rc;
346 struct dma_chan* chan;
347
348 if (!device)
349 return -ENODEV;
350
351 /* validate device routines */
352 BUG_ON(dma_has_cap(DMA_MEMCPY, device->cap_mask) &&
353 !device->device_prep_dma_memcpy);
354 BUG_ON(dma_has_cap(DMA_XOR, device->cap_mask) &&
355 !device->device_prep_dma_xor);
356 BUG_ON(dma_has_cap(DMA_ZERO_SUM, device->cap_mask) &&
357 !device->device_prep_dma_zero_sum);
358 BUG_ON(dma_has_cap(DMA_MEMSET, device->cap_mask) &&
359 !device->device_prep_dma_memset);
360 BUG_ON(dma_has_cap(DMA_INTERRUPT, device->cap_mask) &&
361 !device->device_prep_dma_interrupt);
362
363 BUG_ON(!device->device_alloc_chan_resources);
364 BUG_ON(!device->device_free_chan_resources);
365 BUG_ON(!device->device_dependency_added);
366 BUG_ON(!device->device_is_tx_complete);
367 BUG_ON(!device->device_issue_pending);
368 BUG_ON(!device->dev);
369
370 init_completion(&device->done);
371 kref_init(&device->refcount);
372 device->dev_id = id++;
373
374 /* represent channels in sysfs. Probably want devs too */
375 list_for_each_entry(chan, &device->channels, device_node) {
376 chan->local = alloc_percpu(typeof(*chan->local));
377 if (chan->local == NULL)
378 continue;
379
380 chan->chan_id = chancnt++;
381 chan->dev.class = &dma_devclass;
382 chan->dev.parent = NULL;
383 snprintf(chan->dev.bus_id, BUS_ID_SIZE, "dma%dchan%d",
384 device->dev_id, chan->chan_id);
385
386 rc = device_register(&chan->dev);
387 if (rc) {
388 chancnt--;
389 free_percpu(chan->local);
390 chan->local = NULL;
391 goto err_out;
392 }
393
394 /* One for the channel, one of the class device */
395 kref_get(&device->refcount);
396 kref_get(&device->refcount);
397 kref_init(&chan->refcount);
398 chan->slow_ref = 0;
399 INIT_RCU_HEAD(&chan->rcu);
400 }
401
402 mutex_lock(&dma_list_mutex);
403 list_add_tail(&device->global_node, &dma_device_list);
404 mutex_unlock(&dma_list_mutex);
405
406 dma_clients_notify_available();
407
408 return 0;
409
410 err_out:
411 list_for_each_entry(chan, &device->channels, device_node) {
412 if (chan->local == NULL)
413 continue;
414 kref_put(&device->refcount, dma_async_device_cleanup);
415 device_unregister(&chan->dev);
416 chancnt--;
417 free_percpu(chan->local);
418 }
419 return rc;
420 }
421 EXPORT_SYMBOL(dma_async_device_register);
422
423 /**
424 * dma_async_device_cleanup - function called when all references are released
425 * @kref: kernel reference object
426 */
427 static void dma_async_device_cleanup(struct kref *kref)
428 {
429 struct dma_device *device;
430
431 device = container_of(kref, struct dma_device, refcount);
432 complete(&device->done);
433 }
434
435 /**
436 * dma_async_device_unregister - unregisters DMA devices
437 * @device: &dma_device
438 */
439 void dma_async_device_unregister(struct dma_device *device)
440 {
441 struct dma_chan *chan;
442
443 mutex_lock(&dma_list_mutex);
444 list_del(&device->global_node);
445 mutex_unlock(&dma_list_mutex);
446
447 list_for_each_entry(chan, &device->channels, device_node) {
448 dma_clients_notify_removed(chan);
449 device_unregister(&chan->dev);
450 dma_chan_release(chan);
451 }
452
453 kref_put(&device->refcount, dma_async_device_cleanup);
454 wait_for_completion(&device->done);
455 }
456 EXPORT_SYMBOL(dma_async_device_unregister);
457
458 /**
459 * dma_async_memcpy_buf_to_buf - offloaded copy between virtual addresses
460 * @chan: DMA channel to offload copy to
461 * @dest: destination address (virtual)
462 * @src: source address (virtual)
463 * @len: length
464 *
465 * Both @dest and @src must be mappable to a bus address according to the
466 * DMA mapping API rules for streaming mappings.
467 * Both @dest and @src must stay memory resident (kernel memory or locked
468 * user space pages).
469 */
470 dma_cookie_t
471 dma_async_memcpy_buf_to_buf(struct dma_chan *chan, void *dest,
472 void *src, size_t len)
473 {
474 struct dma_device *dev = chan->device;
475 struct dma_async_tx_descriptor *tx;
476 dma_addr_t dma_dest, dma_src;
477 dma_cookie_t cookie;
478 int cpu;
479
480 dma_src = dma_map_single(dev->dev, src, len, DMA_TO_DEVICE);
481 dma_dest = dma_map_single(dev->dev, dest, len, DMA_FROM_DEVICE);
482 tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len, 0);
483
484 if (!tx) {
485 dma_unmap_single(dev->dev, dma_src, len, DMA_TO_DEVICE);
486 dma_unmap_single(dev->dev, dma_dest, len, DMA_FROM_DEVICE);
487 return -ENOMEM;
488 }
489
490 tx->ack = 1;
491 tx->callback = NULL;
492 cookie = tx->tx_submit(tx);
493
494 cpu = get_cpu();
495 per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
496 per_cpu_ptr(chan->local, cpu)->memcpy_count++;
497 put_cpu();
498
499 return cookie;
500 }
501 EXPORT_SYMBOL(dma_async_memcpy_buf_to_buf);
502
503 /**
504 * dma_async_memcpy_buf_to_pg - offloaded copy from address to page
505 * @chan: DMA channel to offload copy to
506 * @page: destination page
507 * @offset: offset in page to copy to
508 * @kdata: source address (virtual)
509 * @len: length
510 *
511 * Both @page/@offset and @kdata must be mappable to a bus address according
512 * to the DMA mapping API rules for streaming mappings.
513 * Both @page/@offset and @kdata must stay memory resident (kernel memory or
514 * locked user space pages)
515 */
516 dma_cookie_t
517 dma_async_memcpy_buf_to_pg(struct dma_chan *chan, struct page *page,
518 unsigned int offset, void *kdata, size_t len)
519 {
520 struct dma_device *dev = chan->device;
521 struct dma_async_tx_descriptor *tx;
522 dma_addr_t dma_dest, dma_src;
523 dma_cookie_t cookie;
524 int cpu;
525
526 dma_src = dma_map_single(dev->dev, kdata, len, DMA_TO_DEVICE);
527 dma_dest = dma_map_page(dev->dev, page, offset, len, DMA_FROM_DEVICE);
528 tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len, 0);
529
530 if (!tx) {
531 dma_unmap_single(dev->dev, dma_src, len, DMA_TO_DEVICE);
532 dma_unmap_page(dev->dev, dma_dest, len, DMA_FROM_DEVICE);
533 return -ENOMEM;
534 }
535
536 tx->ack = 1;
537 tx->callback = NULL;
538 cookie = tx->tx_submit(tx);
539
540 cpu = get_cpu();
541 per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
542 per_cpu_ptr(chan->local, cpu)->memcpy_count++;
543 put_cpu();
544
545 return cookie;
546 }
547 EXPORT_SYMBOL(dma_async_memcpy_buf_to_pg);
548
549 /**
550 * dma_async_memcpy_pg_to_pg - offloaded copy from page to page
551 * @chan: DMA channel to offload copy to
552 * @dest_pg: destination page
553 * @dest_off: offset in page to copy to
554 * @src_pg: source page
555 * @src_off: offset in page to copy from
556 * @len: length
557 *
558 * Both @dest_page/@dest_off and @src_page/@src_off must be mappable to a bus
559 * address according to the DMA mapping API rules for streaming mappings.
560 * Both @dest_page/@dest_off and @src_page/@src_off must stay memory resident
561 * (kernel memory or locked user space pages).
562 */
563 dma_cookie_t
564 dma_async_memcpy_pg_to_pg(struct dma_chan *chan, struct page *dest_pg,
565 unsigned int dest_off, struct page *src_pg, unsigned int src_off,
566 size_t len)
567 {
568 struct dma_device *dev = chan->device;
569 struct dma_async_tx_descriptor *tx;
570 dma_addr_t dma_dest, dma_src;
571 dma_cookie_t cookie;
572 int cpu;
573
574 dma_src = dma_map_page(dev->dev, src_pg, src_off, len, DMA_TO_DEVICE);
575 dma_dest = dma_map_page(dev->dev, dest_pg, dest_off, len,
576 DMA_FROM_DEVICE);
577 tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len, 0);
578
579 if (!tx) {
580 dma_unmap_page(dev->dev, dma_src, len, DMA_TO_DEVICE);
581 dma_unmap_page(dev->dev, dma_dest, len, DMA_FROM_DEVICE);
582 return -ENOMEM;
583 }
584
585 tx->ack = 1;
586 tx->callback = NULL;
587 cookie = tx->tx_submit(tx);
588
589 cpu = get_cpu();
590 per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
591 per_cpu_ptr(chan->local, cpu)->memcpy_count++;
592 put_cpu();
593
594 return cookie;
595 }
596 EXPORT_SYMBOL(dma_async_memcpy_pg_to_pg);
597
598 void dma_async_tx_descriptor_init(struct dma_async_tx_descriptor *tx,
599 struct dma_chan *chan)
600 {
601 tx->chan = chan;
602 spin_lock_init(&tx->lock);
603 INIT_LIST_HEAD(&tx->depend_node);
604 INIT_LIST_HEAD(&tx->depend_list);
605 }
606 EXPORT_SYMBOL(dma_async_tx_descriptor_init);
607
608 static int __init dma_bus_init(void)
609 {
610 mutex_init(&dma_list_mutex);
611 return class_register(&dma_devclass);
612 }
613 subsys_initcall(dma_bus_init);
614
615
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