2 * Copyright(c) 2004 - 2006 Intel Corporation. All rights reserved.
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)
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
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.
18 * The full GNU General Public License is included in this distribution in the
19 * file called COPYING.
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
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,
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.
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.
40 * Each client is responsible for keeping track of the channels it uses. See
41 * the definition of dma_event_callback in dmaengine.h.
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 corresponding 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 corresponding 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.
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 unregistered. 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.
62 #include <linux/init.h>
63 #include <linux/module.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>
74 static DEFINE_MUTEX(dma_list_mutex
);
75 static LIST_HEAD(dma_device_list
);
76 static LIST_HEAD(dma_client_list
);
78 /* --- sysfs implementation --- */
80 static ssize_t
show_memcpy_count(struct device
*dev
, struct device_attribute
*attr
, char *buf
)
82 struct dma_chan
*chan
= to_dma_chan(dev
);
83 unsigned long count
= 0;
86 for_each_possible_cpu(i
)
87 count
+= per_cpu_ptr(chan
->local
, i
)->memcpy_count
;
89 return sprintf(buf
, "%lu\n", count
);
92 static ssize_t
show_bytes_transferred(struct device
*dev
, struct device_attribute
*attr
,
95 struct dma_chan
*chan
= to_dma_chan(dev
);
96 unsigned long count
= 0;
99 for_each_possible_cpu(i
)
100 count
+= per_cpu_ptr(chan
->local
, i
)->bytes_transferred
;
102 return sprintf(buf
, "%lu\n", count
);
105 static ssize_t
show_in_use(struct device
*dev
, struct device_attribute
*attr
, char *buf
)
107 struct dma_chan
*chan
= to_dma_chan(dev
);
110 if (unlikely(chan
->slow_ref
) &&
111 atomic_read(&chan
->refcount
.refcount
) > 1)
114 if (local_read(&(per_cpu_ptr(chan
->local
,
115 get_cpu())->refcount
)) > 0)
120 return sprintf(buf
, "%d\n", in_use
);
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
),
130 static void dma_async_device_cleanup(struct kref
*kref
);
132 static void dma_dev_release(struct device
*dev
)
134 struct dma_chan
*chan
= to_dma_chan(dev
);
135 kref_put(&chan
->device
->refcount
, dma_async_device_cleanup
);
138 static struct class dma_devclass
= {
140 .dev_attrs
= dma_attrs
,
141 .dev_release
= dma_dev_release
,
144 /* --- client and device registration --- */
146 #define dma_chan_satisfies_mask(chan, mask) \
147 __dma_chan_satisfies_mask((chan), &(mask))
149 __dma_chan_satisfies_mask(struct dma_chan
*chan
, dma_cap_mask_t
*want
)
153 bitmap_and(has
.bits
, want
->bits
, chan
->device
->cap_mask
.bits
,
155 return bitmap_equal(want
->bits
, has
.bits
, DMA_TX_TYPE_END
);
159 * dma_client_chan_alloc - try to allocate channels to a client
160 * @client: &dma_client
162 * Called with dma_list_mutex held.
164 static void dma_client_chan_alloc(struct dma_client
*client
)
166 struct dma_device
*device
;
167 struct dma_chan
*chan
;
168 int desc
; /* allocated descriptor count */
169 enum dma_state_client ack
;
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
))
177 desc
= chan
->device
->device_alloc_chan_resources(
180 ack
= client
->event_callback(client
,
182 DMA_RESOURCE_AVAILABLE
);
184 /* we are done once this client rejects
185 * an available resource
187 if (ack
== DMA_ACK
) {
189 chan
->client_count
++;
190 } else if (ack
== DMA_NAK
)
196 enum dma_status
dma_sync_wait(struct dma_chan
*chan
, dma_cookie_t cookie
)
198 enum dma_status status
;
199 unsigned long dma_sync_wait_timeout
= jiffies
+ msecs_to_jiffies(5000);
201 dma_async_issue_pending(chan
);
203 status
= dma_async_is_tx_complete(chan
, cookie
, NULL
, NULL
);
204 if (time_after_eq(jiffies
, dma_sync_wait_timeout
)) {
205 printk(KERN_ERR
"dma_sync_wait_timeout!\n");
208 } while (status
== DMA_IN_PROGRESS
);
212 EXPORT_SYMBOL(dma_sync_wait
);
215 * dma_chan_cleanup - release a DMA channel's resources
216 * @kref: kernel reference structure that contains the DMA channel device
218 void dma_chan_cleanup(struct kref
*kref
)
220 struct dma_chan
*chan
= container_of(kref
, struct dma_chan
, refcount
);
221 chan
->device
->device_free_chan_resources(chan
);
222 kref_put(&chan
->device
->refcount
, dma_async_device_cleanup
);
224 EXPORT_SYMBOL(dma_chan_cleanup
);
226 static void dma_chan_free_rcu(struct rcu_head
*rcu
)
228 struct dma_chan
*chan
= container_of(rcu
, struct dma_chan
, rcu
);
229 int bias
= 0x7FFFFFFF;
231 for_each_possible_cpu(i
)
232 bias
-= local_read(&per_cpu_ptr(chan
->local
, i
)->refcount
);
233 atomic_sub(bias
, &chan
->refcount
.refcount
);
234 kref_put(&chan
->refcount
, dma_chan_cleanup
);
237 static void dma_chan_release(struct dma_chan
*chan
)
239 atomic_add(0x7FFFFFFF, &chan
->refcount
.refcount
);
241 call_rcu(&chan
->rcu
, dma_chan_free_rcu
);
245 * dma_chans_notify_available - broadcast available channels to the clients
247 static void dma_clients_notify_available(void)
249 struct dma_client
*client
;
251 mutex_lock(&dma_list_mutex
);
253 list_for_each_entry(client
, &dma_client_list
, global_node
)
254 dma_client_chan_alloc(client
);
256 mutex_unlock(&dma_list_mutex
);
260 * dma_chans_notify_available - tell the clients that a channel is going away
261 * @chan: channel on its way out
263 static void dma_clients_notify_removed(struct dma_chan
*chan
)
265 struct dma_client
*client
;
266 enum dma_state_client ack
;
268 mutex_lock(&dma_list_mutex
);
270 list_for_each_entry(client
, &dma_client_list
, global_node
) {
271 ack
= client
->event_callback(client
, chan
,
272 DMA_RESOURCE_REMOVED
);
274 /* client was holding resources for this channel so
277 if (ack
== DMA_ACK
) {
279 chan
->client_count
--;
283 mutex_unlock(&dma_list_mutex
);
287 * dma_async_client_register - register a &dma_client
288 * @client: ptr to a client structure with valid 'event_callback' and 'cap_mask'
290 void dma_async_client_register(struct dma_client
*client
)
292 mutex_lock(&dma_list_mutex
);
293 list_add_tail(&client
->global_node
, &dma_client_list
);
294 mutex_unlock(&dma_list_mutex
);
296 EXPORT_SYMBOL(dma_async_client_register
);
299 * dma_async_client_unregister - unregister a client and free the &dma_client
300 * @client: &dma_client to free
302 * Force frees any allocated DMA channels, frees the &dma_client memory
304 void dma_async_client_unregister(struct dma_client
*client
)
306 struct dma_device
*device
;
307 struct dma_chan
*chan
;
308 enum dma_state_client ack
;
313 mutex_lock(&dma_list_mutex
);
314 /* free all channels the client is holding */
315 list_for_each_entry(device
, &dma_device_list
, global_node
)
316 list_for_each_entry(chan
, &device
->channels
, device_node
) {
317 ack
= client
->event_callback(client
, chan
,
318 DMA_RESOURCE_REMOVED
);
320 if (ack
== DMA_ACK
) {
322 chan
->client_count
--;
326 list_del(&client
->global_node
);
327 mutex_unlock(&dma_list_mutex
);
329 EXPORT_SYMBOL(dma_async_client_unregister
);
332 * dma_async_client_chan_request - send all available channels to the
333 * client that satisfy the capability mask
334 * @client - requester
336 void dma_async_client_chan_request(struct dma_client
*client
)
338 mutex_lock(&dma_list_mutex
);
339 dma_client_chan_alloc(client
);
340 mutex_unlock(&dma_list_mutex
);
342 EXPORT_SYMBOL(dma_async_client_chan_request
);
345 * dma_async_device_register - registers DMA devices found
346 * @device: &dma_device
348 int dma_async_device_register(struct dma_device
*device
)
352 struct dma_chan
* chan
;
357 /* validate device routines */
358 BUG_ON(dma_has_cap(DMA_MEMCPY
, device
->cap_mask
) &&
359 !device
->device_prep_dma_memcpy
);
360 BUG_ON(dma_has_cap(DMA_XOR
, device
->cap_mask
) &&
361 !device
->device_prep_dma_xor
);
362 BUG_ON(dma_has_cap(DMA_ZERO_SUM
, device
->cap_mask
) &&
363 !device
->device_prep_dma_zero_sum
);
364 BUG_ON(dma_has_cap(DMA_MEMSET
, device
->cap_mask
) &&
365 !device
->device_prep_dma_memset
);
366 BUG_ON(dma_has_cap(DMA_INTERRUPT
, device
->cap_mask
) &&
367 !device
->device_prep_dma_interrupt
);
369 BUG_ON(!device
->device_alloc_chan_resources
);
370 BUG_ON(!device
->device_free_chan_resources
);
371 BUG_ON(!device
->device_is_tx_complete
);
372 BUG_ON(!device
->device_issue_pending
);
373 BUG_ON(!device
->dev
);
375 init_completion(&device
->done
);
376 kref_init(&device
->refcount
);
377 device
->dev_id
= id
++;
379 /* represent channels in sysfs. Probably want devs too */
380 list_for_each_entry(chan
, &device
->channels
, device_node
) {
381 chan
->local
= alloc_percpu(typeof(*chan
->local
));
382 if (chan
->local
== NULL
)
385 chan
->chan_id
= chancnt
++;
386 chan
->dev
.class = &dma_devclass
;
387 chan
->dev
.parent
= device
->dev
;
388 snprintf(chan
->dev
.bus_id
, BUS_ID_SIZE
, "dma%dchan%d",
389 device
->dev_id
, chan
->chan_id
);
391 rc
= device_register(&chan
->dev
);
394 free_percpu(chan
->local
);
399 /* One for the channel, one of the class device */
400 kref_get(&device
->refcount
);
401 kref_get(&device
->refcount
);
402 kref_init(&chan
->refcount
);
403 chan
->client_count
= 0;
405 INIT_RCU_HEAD(&chan
->rcu
);
408 mutex_lock(&dma_list_mutex
);
409 list_add_tail(&device
->global_node
, &dma_device_list
);
410 mutex_unlock(&dma_list_mutex
);
412 dma_clients_notify_available();
417 list_for_each_entry(chan
, &device
->channels
, device_node
) {
418 if (chan
->local
== NULL
)
420 kref_put(&device
->refcount
, dma_async_device_cleanup
);
421 device_unregister(&chan
->dev
);
423 free_percpu(chan
->local
);
427 EXPORT_SYMBOL(dma_async_device_register
);
430 * dma_async_device_cleanup - function called when all references are released
431 * @kref: kernel reference object
433 static void dma_async_device_cleanup(struct kref
*kref
)
435 struct dma_device
*device
;
437 device
= container_of(kref
, struct dma_device
, refcount
);
438 complete(&device
->done
);
442 * dma_async_device_unregister - unregisters DMA devices
443 * @device: &dma_device
445 void dma_async_device_unregister(struct dma_device
*device
)
447 struct dma_chan
*chan
;
449 mutex_lock(&dma_list_mutex
);
450 list_del(&device
->global_node
);
451 mutex_unlock(&dma_list_mutex
);
453 list_for_each_entry(chan
, &device
->channels
, device_node
) {
454 dma_clients_notify_removed(chan
);
455 device_unregister(&chan
->dev
);
456 dma_chan_release(chan
);
459 kref_put(&device
->refcount
, dma_async_device_cleanup
);
460 wait_for_completion(&device
->done
);
462 EXPORT_SYMBOL(dma_async_device_unregister
);
465 * dma_async_memcpy_buf_to_buf - offloaded copy between virtual addresses
466 * @chan: DMA channel to offload copy to
467 * @dest: destination address (virtual)
468 * @src: source address (virtual)
471 * Both @dest and @src must be mappable to a bus address according to the
472 * DMA mapping API rules for streaming mappings.
473 * Both @dest and @src must stay memory resident (kernel memory or locked
477 dma_async_memcpy_buf_to_buf(struct dma_chan
*chan
, void *dest
,
478 void *src
, size_t len
)
480 struct dma_device
*dev
= chan
->device
;
481 struct dma_async_tx_descriptor
*tx
;
482 dma_addr_t dma_dest
, dma_src
;
486 dma_src
= dma_map_single(dev
->dev
, src
, len
, DMA_TO_DEVICE
);
487 dma_dest
= dma_map_single(dev
->dev
, dest
, len
, DMA_FROM_DEVICE
);
488 tx
= dev
->device_prep_dma_memcpy(chan
, dma_dest
, dma_src
, len
,
492 dma_unmap_single(dev
->dev
, dma_src
, len
, DMA_TO_DEVICE
);
493 dma_unmap_single(dev
->dev
, dma_dest
, len
, DMA_FROM_DEVICE
);
498 cookie
= tx
->tx_submit(tx
);
501 per_cpu_ptr(chan
->local
, cpu
)->bytes_transferred
+= len
;
502 per_cpu_ptr(chan
->local
, cpu
)->memcpy_count
++;
507 EXPORT_SYMBOL(dma_async_memcpy_buf_to_buf
);
510 * dma_async_memcpy_buf_to_pg - offloaded copy from address to page
511 * @chan: DMA channel to offload copy to
512 * @page: destination page
513 * @offset: offset in page to copy to
514 * @kdata: source address (virtual)
517 * Both @page/@offset and @kdata must be mappable to a bus address according
518 * to the DMA mapping API rules for streaming mappings.
519 * Both @page/@offset and @kdata must stay memory resident (kernel memory or
520 * locked user space pages)
523 dma_async_memcpy_buf_to_pg(struct dma_chan
*chan
, struct page
*page
,
524 unsigned int offset
, void *kdata
, size_t len
)
526 struct dma_device
*dev
= chan
->device
;
527 struct dma_async_tx_descriptor
*tx
;
528 dma_addr_t dma_dest
, dma_src
;
532 dma_src
= dma_map_single(dev
->dev
, kdata
, len
, DMA_TO_DEVICE
);
533 dma_dest
= dma_map_page(dev
->dev
, page
, offset
, len
, DMA_FROM_DEVICE
);
534 tx
= dev
->device_prep_dma_memcpy(chan
, dma_dest
, dma_src
, len
,
538 dma_unmap_single(dev
->dev
, dma_src
, len
, DMA_TO_DEVICE
);
539 dma_unmap_page(dev
->dev
, dma_dest
, len
, DMA_FROM_DEVICE
);
544 cookie
= tx
->tx_submit(tx
);
547 per_cpu_ptr(chan
->local
, cpu
)->bytes_transferred
+= len
;
548 per_cpu_ptr(chan
->local
, cpu
)->memcpy_count
++;
553 EXPORT_SYMBOL(dma_async_memcpy_buf_to_pg
);
556 * dma_async_memcpy_pg_to_pg - offloaded copy from page to page
557 * @chan: DMA channel to offload copy to
558 * @dest_pg: destination page
559 * @dest_off: offset in page to copy to
560 * @src_pg: source page
561 * @src_off: offset in page to copy from
564 * Both @dest_page/@dest_off and @src_page/@src_off must be mappable to a bus
565 * address according to the DMA mapping API rules for streaming mappings.
566 * Both @dest_page/@dest_off and @src_page/@src_off must stay memory resident
567 * (kernel memory or locked user space pages).
570 dma_async_memcpy_pg_to_pg(struct dma_chan
*chan
, struct page
*dest_pg
,
571 unsigned int dest_off
, struct page
*src_pg
, unsigned int src_off
,
574 struct dma_device
*dev
= chan
->device
;
575 struct dma_async_tx_descriptor
*tx
;
576 dma_addr_t dma_dest
, dma_src
;
580 dma_src
= dma_map_page(dev
->dev
, src_pg
, src_off
, len
, DMA_TO_DEVICE
);
581 dma_dest
= dma_map_page(dev
->dev
, dest_pg
, dest_off
, len
,
583 tx
= dev
->device_prep_dma_memcpy(chan
, dma_dest
, dma_src
, len
,
587 dma_unmap_page(dev
->dev
, dma_src
, len
, DMA_TO_DEVICE
);
588 dma_unmap_page(dev
->dev
, dma_dest
, len
, DMA_FROM_DEVICE
);
593 cookie
= tx
->tx_submit(tx
);
596 per_cpu_ptr(chan
->local
, cpu
)->bytes_transferred
+= len
;
597 per_cpu_ptr(chan
->local
, cpu
)->memcpy_count
++;
602 EXPORT_SYMBOL(dma_async_memcpy_pg_to_pg
);
604 void dma_async_tx_descriptor_init(struct dma_async_tx_descriptor
*tx
,
605 struct dma_chan
*chan
)
608 spin_lock_init(&tx
->lock
);
610 EXPORT_SYMBOL(dma_async_tx_descriptor_init
);
612 static int __init
dma_bus_init(void)
614 mutex_init(&dma_list_mutex
);
615 return class_register(&dma_devclass
);
617 subsys_initcall(dma_bus_init
);