2 * core routines for the asynchronous memory transfer/transform api
4 * Copyright © 2006, Intel Corporation.
6 * Dan Williams <dan.j.williams@intel.com>
8 * with architecture considerations by:
9 * Neil Brown <neilb@suse.de>
10 * Jeff Garzik <jeff@garzik.org>
12 * This program is free software; you can redistribute it and/or modify it
13 * under the terms and conditions of the GNU General Public License,
14 * version 2, as published by the Free Software Foundation.
16 * This program is distributed in the hope it will be useful, but WITHOUT
17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
18 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
21 * You should have received a copy of the GNU General Public License along with
22 * this program; if not, write to the Free Software Foundation, Inc.,
23 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
26 #include <linux/kernel.h>
27 #include <linux/async_tx.h>
29 #ifdef CONFIG_DMA_ENGINE
30 static enum dma_state_client
31 dma_channel_add_remove(struct dma_client *client,
32 struct dma_chan *chan, enum dma_state state);
34 static struct dma_client async_tx_dma = {
35 .event_callback = dma_channel_add_remove,
36 /* .cap_mask == 0 defaults to all channels */
40 * dma_cap_mask_all - enable iteration over all operation types
42 static dma_cap_mask_t dma_cap_mask_all;
45 * chan_ref_percpu - tracks channel allocations per core/opertion
47 struct chan_ref_percpu {
48 struct dma_chan_ref *ref;
51 static int channel_table_initialized;
52 static struct chan_ref_percpu *channel_table[DMA_TX_TYPE_END];
55 * async_tx_lock - protect modification of async_tx_master_list and serialize
56 * rebalance operations
58 static spinlock_t async_tx_lock;
60 static LIST_HEAD(async_tx_master_list);
62 /* async_tx_issue_pending_all - start all transactions on all channels */
63 void async_tx_issue_pending_all(void)
65 struct dma_chan_ref *ref;
68 list_for_each_entry_rcu(ref, &async_tx_master_list, node)
69 ref->chan->device->device_issue_pending(ref->chan);
72 EXPORT_SYMBOL_GPL(async_tx_issue_pending_all);
74 /* dma_wait_for_async_tx - spin wait for a transcation to complete
75 * @tx: transaction to wait on
78 dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)
80 enum dma_status status;
81 struct dma_async_tx_descriptor *iter;
82 struct dma_async_tx_descriptor *parent;
87 /* poll through the dependency chain, return when tx is complete */
91 /* find the root of the unsubmitted dependency chain */
92 while (iter->cookie == -EBUSY) {
93 parent = iter->parent;
94 if (parent && parent->cookie == -EBUSY)
100 status = dma_sync_wait(iter->chan, iter->cookie);
101 } while (status == DMA_IN_PROGRESS || (iter != tx));
105 EXPORT_SYMBOL_GPL(dma_wait_for_async_tx);
107 /* async_tx_run_dependencies - helper routine for dma drivers to process
108 * (start) dependent operations on their target channel
109 * @tx: transaction with dependencies
112 async_tx_run_dependencies(struct dma_async_tx_descriptor *tx)
114 struct dma_async_tx_descriptor *dep_tx, *_dep_tx;
115 struct dma_device *dev;
116 struct dma_chan *chan;
118 list_for_each_entry_safe(dep_tx, _dep_tx, &tx->depend_list,
122 /* we can't depend on ourselves */
123 BUG_ON(chan == tx->chan);
124 list_del(&dep_tx->depend_node);
125 tx->tx_submit(dep_tx);
127 /* we need to poke the engine as client code does not
128 * know about dependency submission events
130 dev->device_issue_pending(chan);
133 EXPORT_SYMBOL_GPL(async_tx_run_dependencies);
136 free_dma_chan_ref(struct rcu_head *rcu)
138 struct dma_chan_ref *ref;
139 ref = container_of(rcu, struct dma_chan_ref, rcu);
144 init_dma_chan_ref(struct dma_chan_ref *ref, struct dma_chan *chan)
146 INIT_LIST_HEAD(&ref->node);
147 INIT_RCU_HEAD(&ref->rcu);
149 atomic_set(&ref->count, 0);
153 * get_chan_ref_by_cap - returns the nth channel of the given capability
154 * defaults to returning the channel with the desired capability and the
155 * lowest reference count if the index can not be satisfied
156 * @cap: capability to match
157 * @index: nth channel desired, passing -1 has the effect of forcing the
158 * default return value
160 static struct dma_chan_ref *
161 get_chan_ref_by_cap(enum dma_transaction_type cap, int index)
163 struct dma_chan_ref *ret_ref = NULL, *min_ref = NULL, *ref;
166 list_for_each_entry_rcu(ref, &async_tx_master_list, node)
167 if (dma_has_cap(cap, ref->chan->device->cap_mask)) {
170 else if (atomic_read(&ref->count) <
171 atomic_read(&min_ref->count))
185 atomic_inc(&ret_ref->count);
191 * async_tx_rebalance - redistribute the available channels, optimize
192 * for cpu isolation in the SMP case, and opertaion isolation in the
195 static void async_tx_rebalance(void)
197 int cpu, cap, cpu_idx = 0;
200 if (!channel_table_initialized)
203 spin_lock_irqsave(&async_tx_lock, flags);
205 /* undo the last distribution */
206 for_each_dma_cap_mask(cap, dma_cap_mask_all)
207 for_each_possible_cpu(cpu) {
208 struct dma_chan_ref *ref =
209 per_cpu_ptr(channel_table[cap], cpu)->ref;
211 atomic_set(&ref->count, 0);
212 per_cpu_ptr(channel_table[cap], cpu)->ref =
217 for_each_dma_cap_mask(cap, dma_cap_mask_all)
218 for_each_online_cpu(cpu) {
219 struct dma_chan_ref *new;
221 new = get_chan_ref_by_cap(cap, cpu_idx++);
223 new = get_chan_ref_by_cap(cap, -1);
225 per_cpu_ptr(channel_table[cap], cpu)->ref = new;
228 spin_unlock_irqrestore(&async_tx_lock, flags);
231 static enum dma_state_client
232 dma_channel_add_remove(struct dma_client *client,
233 struct dma_chan *chan, enum dma_state state)
235 unsigned long found, flags;
236 struct dma_chan_ref *master_ref, *ref;
237 enum dma_state_client ack = DMA_DUP; /* default: take no action */
240 case DMA_RESOURCE_AVAILABLE:
243 list_for_each_entry_rcu(ref, &async_tx_master_list, node)
244 if (ref->chan == chan) {
250 pr_debug("async_tx: dma resource available [%s]\n",
251 found ? "old" : "new");
258 /* add the channel to the generic management list */
259 master_ref = kmalloc(sizeof(*master_ref), GFP_KERNEL);
261 /* keep a reference until async_tx is unloaded */
263 init_dma_chan_ref(master_ref, chan);
264 spin_lock_irqsave(&async_tx_lock, flags);
265 list_add_tail_rcu(&master_ref->node,
266 &async_tx_master_list);
267 spin_unlock_irqrestore(&async_tx_lock,
270 printk(KERN_WARNING "async_tx: unable to create"
271 " new master entry in response to"
272 " a DMA_RESOURCE_ADDED event"
277 async_tx_rebalance();
279 case DMA_RESOURCE_REMOVED:
281 spin_lock_irqsave(&async_tx_lock, flags);
282 list_for_each_entry_rcu(ref, &async_tx_master_list, node)
283 if (ref->chan == chan) {
284 /* permit backing devices to go away */
285 dma_chan_put(ref->chan);
286 list_del_rcu(&ref->node);
287 call_rcu(&ref->rcu, free_dma_chan_ref);
291 spin_unlock_irqrestore(&async_tx_lock, flags);
293 pr_debug("async_tx: dma resource removed [%s]\n",
294 found ? "ours" : "not ours");
301 async_tx_rebalance();
303 case DMA_RESOURCE_SUSPEND:
304 case DMA_RESOURCE_RESUME:
305 printk(KERN_WARNING "async_tx: does not support dma channel"
306 " suspend/resume\n");
318 enum dma_transaction_type cap;
320 spin_lock_init(&async_tx_lock);
321 bitmap_fill(dma_cap_mask_all.bits, DMA_TX_TYPE_END);
323 /* an interrupt will never be an explicit operation type.
324 * clearing this bit prevents allocation to a slot in 'channel_table'
326 clear_bit(DMA_INTERRUPT, dma_cap_mask_all.bits);
328 for_each_dma_cap_mask(cap, dma_cap_mask_all) {
329 channel_table[cap] = alloc_percpu(struct chan_ref_percpu);
330 if (!channel_table[cap])
334 channel_table_initialized = 1;
335 dma_async_client_register(&async_tx_dma);
336 dma_async_client_chan_request(&async_tx_dma);
338 printk(KERN_INFO "async_tx: api initialized (async)\n");
342 printk(KERN_ERR "async_tx: initialization failure\n");
345 free_percpu(channel_table[cap]);
350 static void __exit async_tx_exit(void)
352 enum dma_transaction_type cap;
354 channel_table_initialized = 0;
356 for_each_dma_cap_mask(cap, dma_cap_mask_all)
357 if (channel_table[cap])
358 free_percpu(channel_table[cap]);
360 dma_async_client_unregister(&async_tx_dma);
364 * __async_tx_find_channel - find a channel to carry out the operation or let
365 * the transaction execute synchronously
366 * @depend_tx: transaction dependency
367 * @tx_type: transaction type
370 __async_tx_find_channel(struct dma_async_tx_descriptor *depend_tx,
371 enum dma_transaction_type tx_type)
373 /* see if we can keep the chain on one channel */
375 dma_has_cap(tx_type, depend_tx->chan->device->cap_mask))
376 return depend_tx->chan;
377 else if (likely(channel_table_initialized)) {
378 struct dma_chan_ref *ref;
380 ref = per_cpu_ptr(channel_table[tx_type], cpu)->ref;
382 return ref ? ref->chan : NULL;
386 EXPORT_SYMBOL_GPL(__async_tx_find_channel);
388 static int __init async_tx_init(void)
390 printk(KERN_INFO "async_tx: api initialized (sync-only)\n");
394 static void __exit async_tx_exit(void)
401 async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
402 enum async_tx_flags flags, struct dma_async_tx_descriptor *depend_tx,
403 dma_async_tx_callback cb_fn, void *cb_param)
405 tx->callback = cb_fn;
406 tx->callback_param = cb_param;
408 /* set this new tx to run after depend_tx if:
409 * 1/ a dependency exists (depend_tx is !NULL)
410 * 2/ the tx can not be submitted to the current channel
412 if (depend_tx && depend_tx->chan != chan) {
413 /* if ack is already set then we cannot be sure
414 * we are referring to the correct operation
416 BUG_ON(depend_tx->ack);
418 tx->parent = depend_tx;
419 spin_lock_bh(&depend_tx->lock);
420 list_add_tail(&tx->depend_node, &depend_tx->depend_list);
421 if (depend_tx->cookie == 0) {
422 struct dma_chan *dep_chan = depend_tx->chan;
423 struct dma_device *dep_dev = dep_chan->device;
424 dep_dev->device_dependency_added(dep_chan);
426 spin_unlock_bh(&depend_tx->lock);
428 /* schedule an interrupt to trigger the channel switch */
429 async_trigger_callback(ASYNC_TX_ACK, depend_tx, NULL, NULL);
435 if (flags & ASYNC_TX_ACK)
438 if (depend_tx && (flags & ASYNC_TX_DEP_ACK))
439 async_tx_ack(depend_tx);
441 EXPORT_SYMBOL_GPL(async_tx_submit);
444 * async_trigger_callback - schedules the callback function to be run after
445 * any dependent operations have been completed.
446 * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
447 * @depend_tx: 'callback' requires the completion of this transaction
448 * @cb_fn: function to call after depend_tx completes
449 * @cb_param: parameter to pass to the callback routine
451 struct dma_async_tx_descriptor *
452 async_trigger_callback(enum async_tx_flags flags,
453 struct dma_async_tx_descriptor *depend_tx,
454 dma_async_tx_callback cb_fn, void *cb_param)
456 struct dma_chan *chan;
457 struct dma_device *device;
458 struct dma_async_tx_descriptor *tx;
461 chan = depend_tx->chan;
462 device = chan->device;
464 /* see if we can schedule an interrupt
465 * otherwise poll for completion
467 if (device && !dma_has_cap(DMA_INTERRUPT, device->cap_mask))
470 tx = device ? device->device_prep_dma_interrupt(chan) : NULL;
475 pr_debug("%s: (async)\n", __func__);
477 async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
479 pr_debug("%s: (sync)\n", __func__);
481 /* wait for any prerequisite operations */
483 /* if ack is already set then we cannot be sure
484 * we are referring to the correct operation
486 BUG_ON(depend_tx->ack);
487 if (dma_wait_for_async_tx(depend_tx) == DMA_ERROR)
488 panic("%s: DMA_ERROR waiting for depend_tx\n",
492 async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param);
497 EXPORT_SYMBOL_GPL(async_trigger_callback);
499 module_init(async_tx_init);
500 module_exit(async_tx_exit);
502 MODULE_AUTHOR("Intel Corporation");
503 MODULE_DESCRIPTION("Asynchronous Bulk Memory Transactions API");
504 MODULE_LICENSE("GPL");