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authorChris Leech <christopher.leech@intel.com>2006-05-23 20:18:44 -0400
committerDavid S. Miller <davem@sunset.davemloft.net>2006-06-18 00:18:43 -0400
commitc13c8260da3155f2cefb63b0d1b7dcdcb405c644 (patch)
treeecfe02fa44a423a948f5fb5ad76497da2bb7a402 /drivers
parent427abfa28afedffadfca9dd8b067eb6d36bac53f (diff)
[I/OAT]: DMA memcpy subsystem
Provides an API for offloading memory copies to DMA devices Signed-off-by: Chris Leech <christopher.leech@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/Kconfig2
-rw-r--r--drivers/Makefile1
-rw-r--r--drivers/dma/Kconfig13
-rw-r--r--drivers/dma/Makefile1
-rw-r--r--drivers/dma/dmaengine.c408
5 files changed, 425 insertions, 0 deletions
diff --git a/drivers/Kconfig b/drivers/Kconfig
index aeb5ab2391e4..8b11cebe65df 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -72,4 +72,6 @@ source "drivers/edac/Kconfig"
72 72
73source "drivers/rtc/Kconfig" 73source "drivers/rtc/Kconfig"
74 74
75source "drivers/dma/Kconfig"
76
75endmenu 77endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index 447d8e68887a..3c5170310bd0 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -74,3 +74,4 @@ obj-$(CONFIG_SGI_SN) += sn/
74obj-y += firmware/ 74obj-y += firmware/
75obj-$(CONFIG_CRYPTO) += crypto/ 75obj-$(CONFIG_CRYPTO) += crypto/
76obj-$(CONFIG_SUPERH) += sh/ 76obj-$(CONFIG_SUPERH) += sh/
77obj-$(CONFIG_DMA_ENGINE) += dma/
diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
new file mode 100644
index 000000000000..f9ac4bcf8652
--- /dev/null
+++ b/drivers/dma/Kconfig
@@ -0,0 +1,13 @@
1#
2# DMA engine configuration
3#
4
5menu "DMA Engine support"
6
7config DMA_ENGINE
8 bool "Support for DMA engines"
9 ---help---
10 DMA engines offload copy operations from the CPU to dedicated
11 hardware, allowing the copies to happen asynchronously.
12
13endmenu
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
new file mode 100644
index 000000000000..10b739138c93
--- /dev/null
+++ b/drivers/dma/Makefile
@@ -0,0 +1 @@
obj-y += dmaengine.o
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
new file mode 100644
index 000000000000..473c47b6f094
--- /dev/null
+++ b/drivers/dma/dmaengine.c
@@ -0,0 +1,408 @@
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 has a channels list, it's only modified under the client->lock
41 * and in an RCU callback, so it's safe to read under rcu_read_lock().
42 *
43 * Each device has a kref, which is initialized to 1 when the device is
44 * registered. A kref_put is done for each class_device registered. When the
45 * class_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, class_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 single reference is set when on an
55 * ADDED event, and removed with a REMOVE event. Net DMA client takes an
56 * extra reference per outstanding transaction. The relase function does a
57 * kref_put on the device. -ChrisL
58 */
59
60#include <linux/init.h>
61#include <linux/module.h>
62#include <linux/device.h>
63#include <linux/dmaengine.h>
64#include <linux/hardirq.h>
65#include <linux/spinlock.h>
66#include <linux/percpu.h>
67#include <linux/rcupdate.h>
68#include <linux/mutex.h>
69
70static DEFINE_MUTEX(dma_list_mutex);
71static LIST_HEAD(dma_device_list);
72static LIST_HEAD(dma_client_list);
73
74/* --- sysfs implementation --- */
75
76static ssize_t show_memcpy_count(struct class_device *cd, char *buf)
77{
78 struct dma_chan *chan = container_of(cd, struct dma_chan, class_dev);
79 unsigned long count = 0;
80 int i;
81
82 for_each_cpu(i)
83 count += per_cpu_ptr(chan->local, i)->memcpy_count;
84
85 return sprintf(buf, "%lu\n", count);
86}
87
88static ssize_t show_bytes_transferred(struct class_device *cd, char *buf)
89{
90 struct dma_chan *chan = container_of(cd, struct dma_chan, class_dev);
91 unsigned long count = 0;
92 int i;
93
94 for_each_cpu(i)
95 count += per_cpu_ptr(chan->local, i)->bytes_transferred;
96
97 return sprintf(buf, "%lu\n", count);
98}
99
100static ssize_t show_in_use(struct class_device *cd, char *buf)
101{
102 struct dma_chan *chan = container_of(cd, struct dma_chan, class_dev);
103
104 return sprintf(buf, "%d\n", (chan->client ? 1 : 0));
105}
106
107static struct class_device_attribute dma_class_attrs[] = {
108 __ATTR(memcpy_count, S_IRUGO, show_memcpy_count, NULL),
109 __ATTR(bytes_transferred, S_IRUGO, show_bytes_transferred, NULL),
110 __ATTR(in_use, S_IRUGO, show_in_use, NULL),
111 __ATTR_NULL
112};
113
114static void dma_async_device_cleanup(struct kref *kref);
115
116static void dma_class_dev_release(struct class_device *cd)
117{
118 struct dma_chan *chan = container_of(cd, struct dma_chan, class_dev);
119 kref_put(&chan->device->refcount, dma_async_device_cleanup);
120}
121
122static struct class dma_devclass = {
123 .name = "dma",
124 .class_dev_attrs = dma_class_attrs,
125 .release = dma_class_dev_release,
126};
127
128/* --- client and device registration --- */
129
130/**
131 * dma_client_chan_alloc - try to allocate a channel to a client
132 * @client: &dma_client
133 *
134 * Called with dma_list_mutex held.
135 */
136static struct dma_chan *dma_client_chan_alloc(struct dma_client *client)
137{
138 struct dma_device *device;
139 struct dma_chan *chan;
140 unsigned long flags;
141 int desc; /* allocated descriptor count */
142
143 /* Find a channel, any DMA engine will do */
144 list_for_each_entry(device, &dma_device_list, global_node) {
145 list_for_each_entry(chan, &device->channels, device_node) {
146 if (chan->client)
147 continue;
148
149 desc = chan->device->device_alloc_chan_resources(chan);
150 if (desc >= 0) {
151 kref_get(&device->refcount);
152 kref_init(&chan->refcount);
153 chan->slow_ref = 0;
154 INIT_RCU_HEAD(&chan->rcu);
155 chan->client = client;
156 spin_lock_irqsave(&client->lock, flags);
157 list_add_tail_rcu(&chan->client_node,
158 &client->channels);
159 spin_unlock_irqrestore(&client->lock, flags);
160 return chan;
161 }
162 }
163 }
164
165 return NULL;
166}
167
168/**
169 * dma_client_chan_free - release a DMA channel
170 * @chan: &dma_chan
171 */
172void dma_chan_cleanup(struct kref *kref)
173{
174 struct dma_chan *chan = container_of(kref, struct dma_chan, refcount);
175 chan->device->device_free_chan_resources(chan);
176 chan->client = NULL;
177 kref_put(&chan->device->refcount, dma_async_device_cleanup);
178}
179
180static void dma_chan_free_rcu(struct rcu_head *rcu)
181{
182 struct dma_chan *chan = container_of(rcu, struct dma_chan, rcu);
183 int bias = 0x7FFFFFFF;
184 int i;
185 for_each_cpu(i)
186 bias -= local_read(&per_cpu_ptr(chan->local, i)->refcount);
187 atomic_sub(bias, &chan->refcount.refcount);
188 kref_put(&chan->refcount, dma_chan_cleanup);
189}
190
191static void dma_client_chan_free(struct dma_chan *chan)
192{
193 atomic_add(0x7FFFFFFF, &chan->refcount.refcount);
194 chan->slow_ref = 1;
195 call_rcu(&chan->rcu, dma_chan_free_rcu);
196}
197
198/**
199 * dma_chans_rebalance - reallocate channels to clients
200 *
201 * When the number of DMA channel in the system changes,
202 * channels need to be rebalanced among clients
203 */
204static void dma_chans_rebalance(void)
205{
206 struct dma_client *client;
207 struct dma_chan *chan;
208 unsigned long flags;
209
210 mutex_lock(&dma_list_mutex);
211
212 list_for_each_entry(client, &dma_client_list, global_node) {
213 while (client->chans_desired > client->chan_count) {
214 chan = dma_client_chan_alloc(client);
215 if (!chan)
216 break;
217 client->chan_count++;
218 client->event_callback(client,
219 chan,
220 DMA_RESOURCE_ADDED);
221 }
222 while (client->chans_desired < client->chan_count) {
223 spin_lock_irqsave(&client->lock, flags);
224 chan = list_entry(client->channels.next,
225 struct dma_chan,
226 client_node);
227 list_del_rcu(&chan->client_node);
228 spin_unlock_irqrestore(&client->lock, flags);
229 client->chan_count--;
230 client->event_callback(client,
231 chan,
232 DMA_RESOURCE_REMOVED);
233 dma_client_chan_free(chan);
234 }
235 }
236
237 mutex_unlock(&dma_list_mutex);
238}
239
240/**
241 * dma_async_client_register - allocate and register a &dma_client
242 * @event_callback: callback for notification of channel addition/removal
243 */
244struct dma_client *dma_async_client_register(dma_event_callback event_callback)
245{
246 struct dma_client *client;
247
248 client = kzalloc(sizeof(*client), GFP_KERNEL);
249 if (!client)
250 return NULL;
251
252 INIT_LIST_HEAD(&client->channels);
253 spin_lock_init(&client->lock);
254 client->chans_desired = 0;
255 client->chan_count = 0;
256 client->event_callback = event_callback;
257
258 mutex_lock(&dma_list_mutex);
259 list_add_tail(&client->global_node, &dma_client_list);
260 mutex_unlock(&dma_list_mutex);
261
262 return client;
263}
264
265/**
266 * dma_async_client_unregister - unregister a client and free the &dma_client
267 * @client:
268 *
269 * Force frees any allocated DMA channels, frees the &dma_client memory
270 */
271void dma_async_client_unregister(struct dma_client *client)
272{
273 struct dma_chan *chan;
274
275 if (!client)
276 return;
277
278 rcu_read_lock();
279 list_for_each_entry_rcu(chan, &client->channels, client_node)
280 dma_client_chan_free(chan);
281 rcu_read_unlock();
282
283 mutex_lock(&dma_list_mutex);
284 list_del(&client->global_node);
285 mutex_unlock(&dma_list_mutex);
286
287 kfree(client);
288 dma_chans_rebalance();
289}
290
291/**
292 * dma_async_client_chan_request - request DMA channels
293 * @client: &dma_client
294 * @number: count of DMA channels requested
295 *
296 * Clients call dma_async_client_chan_request() to specify how many
297 * DMA channels they need, 0 to free all currently allocated.
298 * The resulting allocations/frees are indicated to the client via the
299 * event callback.
300 */
301void dma_async_client_chan_request(struct dma_client *client,
302 unsigned int number)
303{
304 client->chans_desired = number;
305 dma_chans_rebalance();
306}
307
308/**
309 * dma_async_device_register -
310 * @device: &dma_device
311 */
312int dma_async_device_register(struct dma_device *device)
313{
314 static int id;
315 int chancnt = 0;
316 struct dma_chan* chan;
317
318 if (!device)
319 return -ENODEV;
320
321 init_completion(&device->done);
322 kref_init(&device->refcount);
323 device->dev_id = id++;
324
325 /* represent channels in sysfs. Probably want devs too */
326 list_for_each_entry(chan, &device->channels, device_node) {
327 chan->local = alloc_percpu(typeof(*chan->local));
328 if (chan->local == NULL)
329 continue;
330
331 chan->chan_id = chancnt++;
332 chan->class_dev.class = &dma_devclass;
333 chan->class_dev.dev = NULL;
334 snprintf(chan->class_dev.class_id, BUS_ID_SIZE, "dma%dchan%d",
335 device->dev_id, chan->chan_id);
336
337 kref_get(&device->refcount);
338 class_device_register(&chan->class_dev);
339 }
340
341 mutex_lock(&dma_list_mutex);
342 list_add_tail(&device->global_node, &dma_device_list);
343 mutex_unlock(&dma_list_mutex);
344
345 dma_chans_rebalance();
346
347 return 0;
348}
349
350/**
351 * dma_async_device_unregister -
352 * @device: &dma_device
353 */
354static void dma_async_device_cleanup(struct kref *kref)
355{
356 struct dma_device *device;
357
358 device = container_of(kref, struct dma_device, refcount);
359 complete(&device->done);
360}
361
362void dma_async_device_unregister(struct dma_device* device)
363{
364 struct dma_chan *chan;
365 unsigned long flags;
366
367 mutex_lock(&dma_list_mutex);
368 list_del(&device->global_node);
369 mutex_unlock(&dma_list_mutex);
370
371 list_for_each_entry(chan, &device->channels, device_node) {
372 if (chan->client) {
373 spin_lock_irqsave(&chan->client->lock, flags);
374 list_del(&chan->client_node);
375 chan->client->chan_count--;
376 spin_unlock_irqrestore(&chan->client->lock, flags);
377 chan->client->event_callback(chan->client,
378 chan,
379 DMA_RESOURCE_REMOVED);
380 dma_client_chan_free(chan);
381 }
382 class_device_unregister(&chan->class_dev);
383 }
384 dma_chans_rebalance();
385
386 kref_put(&device->refcount, dma_async_device_cleanup);
387 wait_for_completion(&device->done);
388}
389
390static int __init dma_bus_init(void)
391{
392 mutex_init(&dma_list_mutex);
393 return class_register(&dma_devclass);
394}
395
396subsys_initcall(dma_bus_init);
397
398EXPORT_SYMBOL(dma_async_client_register);
399EXPORT_SYMBOL(dma_async_client_unregister);
400EXPORT_SYMBOL(dma_async_client_chan_request);
401EXPORT_SYMBOL(dma_async_memcpy_buf_to_buf);
402EXPORT_SYMBOL(dma_async_memcpy_buf_to_pg);
403EXPORT_SYMBOL(dma_async_memcpy_pg_to_pg);
404EXPORT_SYMBOL(dma_async_memcpy_complete);
405EXPORT_SYMBOL(dma_async_memcpy_issue_pending);
406EXPORT_SYMBOL(dma_async_device_register);
407EXPORT_SYMBOL(dma_async_device_unregister);
408EXPORT_SYMBOL(dma_chan_cleanup);