summaryrefslogtreecommitdiffstats
path: root/crypto/async_tx/async_tx.c
blob: 035007145e780d2cedd3e38cbb1a34e39345d3c2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
/*
 * core routines for the asynchronous memory transfer/transform api
 *
 * Copyright © 2006, Intel Corporation.
 *
 *	Dan Williams <dan.j.williams@intel.com>
 *
 *	with architecture considerations by:
 *	Neil Brown <neilb@suse.de>
 *	Jeff Garzik <jeff@garzik.org>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */
#include <linux/kernel.h>
#include <linux/async_tx.h>

#ifdef CONFIG_DMA_ENGINE
static enum dma_state_client
dma_channel_add_remove(struct dma_client *client,
	struct dma_chan *chan, enum dma_state state);

static struct dma_client async_tx_dma = {
	.event_callback = dma_channel_add_remove,
	/* .cap_mask == 0 defaults to all channels */
};

/**
 * dma_cap_mask_all - enable iteration over all operation types
 */
static dma_cap_mask_t dma_cap_mask_all;

/**
 * chan_ref_percpu - tracks channel allocations per core/opertion
 */
struct chan_ref_percpu {
	struct dma_chan_ref *ref;
};

static int channel_table_initialized;
static struct chan_ref_percpu *channel_table[DMA_TX_TYPE_END];

/**
 * async_tx_lock - protect modification of async_tx_master_list and serialize
 *	rebalance operations
 */
static spinlock_t async_tx_lock;

static struct list_head
async_tx_master_list = LIST_HEAD_INIT(async_tx_master_list);

/* async_tx_issue_pending_all - start all transactions on all channels */
void async_tx_issue_pending_all(void)
{
	struct dma_chan_ref *ref;

	rcu_read_lock();
	list_for_each_entry_rcu(ref, &async_tx_master_list, node)
		ref->chan->device->device_issue_pending(ref->chan);
	rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(async_tx_issue_pending_all);

/* dma_wait_for_async_tx - spin wait for a transcation to complete
 * @tx: transaction to wait on
 */
enum dma_status
dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)
{
	enum dma_status status;
	struct dma_async_tx_descriptor *iter;

	if (!tx)
		return DMA_SUCCESS;

	/* poll through the dependency chain, return when tx is complete */
	do {
		iter = tx;
		while (iter->cookie == -EBUSY)
			iter = iter->parent;

		status = dma_sync_wait(iter->chan, iter->cookie);
	} while (status == DMA_IN_PROGRESS || (iter != tx));

	return status;
}
EXPORT_SYMBOL_GPL(dma_wait_for_async_tx);

/* async_tx_run_dependencies - helper routine for dma drivers to process
 *	(start) dependent operations on their target channel
 * @tx: transaction with dependencies
 */
void
async_tx_run_dependencies(struct dma_async_tx_descriptor *tx)
{
	struct dma_async_tx_descriptor *dep_tx, *_dep_tx;
	struct dma_device *dev;
	struct dma_chan *chan;

	list_for_each_entry_safe(dep_tx, _dep_tx, &tx->depend_list,
		depend_node) {
		chan = dep_tx->chan;
		dev = chan->device;
		/* we can't depend on ourselves */
		BUG_ON(chan == tx->chan);
		list_del(&dep_tx->depend_node);
		tx->tx_submit(dep_tx);

		/* we need to poke the engine as client code does not
		 * know about dependency submission events
		 */
		dev->device_issue_pending(chan);
	}
}
EXPORT_SYMBOL_GPL(async_tx_run_dependencies);

static void
free_dma_chan_ref(struct rcu_head *rcu)
{
	struct dma_chan_ref *ref;
	ref = container_of(rcu, struct dma_chan_ref, rcu);
	kfree(ref);
}

static void
init_dma_chan_ref(struct dma_chan_ref *ref, struct dma_chan *chan)
{
	INIT_LIST_HEAD(&ref->node);
	INIT_RCU_HEAD(&ref->rcu);
	ref->chan = chan;
	atomic_set(&ref->count, 0);
}

/**
 * get_chan_ref_by_cap - returns the nth channel of the given capability
 * 	defaults to returning the channel with the desired capability and the
 * 	lowest reference count if the index can not be satisfied
 * @cap: capability to match
 * @index: nth channel desired, passing -1 has the effect of forcing the
 *  default return value
 */
static struct dma_chan_ref *
get_chan_ref_by_cap(enum dma_transaction_type cap, int index)
{
	struct dma_chan_ref *ret_ref = NULL, *min_ref = NULL, *ref;

	rcu_read_lock();
	list_for_each_entry_rcu(ref, &async_tx_master_list, node)
		if (dma_has_cap(cap, ref->chan->device->cap_mask)) {
			if (!min_ref)
				min_ref = ref;
			else if (atomic_read(&ref->count) <
				atomic_read(&min_ref->count))
				min_ref = ref;

			if (index-- == 0) {
				ret_ref = ref;
				break;
			}
		}
	rcu_read_unlock();

	if (!ret_ref)
		ret_ref = min_ref;

	if (ret_ref)
		atomic_inc(&ret_ref->count);

	return ret_ref;
}

/**
 * async_tx_rebalance - redistribute the available channels, optimize
 * for cpu isolation in the SMP case, and opertaion isolation in the
 * uniprocessor case
 */
static void async_tx_rebalance(void)
{
	int cpu, cap, cpu_idx = 0;
	unsigned long flags;

	if (!channel_table_initialized)
		return;

	spin_lock_irqsave(&async_tx_lock, flags);

	/* undo the last distribution */
	for_each_dma_cap_mask(cap, dma_cap_mask_all)
		for_each_possible_cpu(cpu) {
			struct dma_chan_ref *ref =
				per_cpu_ptr(channel_table[cap], cpu)->ref;
			if (ref) {
				atomic_set(&ref->count, 0);
				per_cpu_ptr(channel_table[cap], cpu)->ref =
									NULL;
			}
		}

	for_each_dma_cap_mask(cap, dma_cap_mask_all)
		for_each_online_cpu(cpu) {
			struct dma_chan_ref *new;
			if (NR_CPUS > 1)
				new = get_chan_ref_by_cap(cap, cpu_idx++);
			else
				new = get_chan_ref_by_cap(cap, -1);

			per_cpu_ptr(channel_table[cap], cpu)->ref = new;
		}

	spin_unlock_irqrestore(&async_tx_lock, flags);
}

static enum dma_state_client
dma_channel_add_remove(struct dma_client *client,
	struct dma_chan *chan, enum dma_state state)
{
	unsigned long found, flags;
	struct dma_chan_ref *master_ref, *ref;
	enum dma_state_client ack = DMA_DUP; /* default: take no action */

	switch (state) {
	case DMA_RESOURCE_AVAILABLE:
		found = 0;
		rcu_read_lock();
		list_for_each_entry_rcu(ref, &async_tx_master_list, node)
			if (ref->chan == chan) {
				found = 1;
				break;
			}
		rcu_read_unlock();

		pr_debug("async_tx: dma resource available [%s]\n",
			found ? "old" : "new");

		if (!found)
			ack = DMA_ACK;
		else
			break;

		/* add the channel to the generic management list */
		master_ref = kmalloc(sizeof(*master_ref), GFP_KERNEL);
		if (master_ref) {
			/* keep a reference until async_tx is unloaded */
			dma_chan_get(chan);
			init_dma_chan_ref(master_ref, chan);
			spin_lock_irqsave(&async_tx_lock, flags);
			list_add_tail_rcu(&master_ref->node,
				&async_tx_master_list);
			spin_unlock_irqrestore(&async_tx_lock,
				flags);
		} else {
			printk(KERN_WARNING "async_tx: unable to create"
				" new master entry in response to"
				" a DMA_RESOURCE_ADDED event"
				" (-ENOMEM)\n");
			return 0;
		}

		async_tx_rebalance();
		break;
	case DMA_RESOURCE_REMOVED:
		found = 0;
		spin_lock_irqsave(&async_tx_lock, flags);
		list_for_each_entry_rcu(ref, &async_tx_master_list, node)
			if (ref->chan == chan) {
				/* permit backing devices to go away */
				dma_chan_put(ref->chan);
				list_del_rcu(&ref->node);
				call_rcu(&ref->rcu, free_dma_chan_ref);
				found = 1;
				break;
			}
		spin_unlock_irqrestore(&async_tx_lock, flags);

		pr_debug("async_tx: dma resource removed [%s]\n",
			found ? "ours" : "not ours");

		if (found)
			ack = DMA_ACK;
		else
			break;

		async_tx_rebalance();
		break;
	case DMA_RESOURCE_SUSPEND:
	case DMA_RESOURCE_RESUME:
		printk(KERN_WARNING "async_tx: does not support dma channel"
			" suspend/resume\n");
		break;
	default:
		BUG();
	}

	return ack;
}

static int __init
async_tx_init(void)
{
	enum dma_transaction_type cap;

	spin_lock_init(&async_tx_lock);
	bitmap_fill(dma_cap_mask_all.bits, DMA_TX_TYPE_END);

	/* an interrupt will never be an explicit operation type.
	 * clearing this bit prevents allocation to a slot in 'channel_table'
	 */
	clear_bit(DMA_INTERRUPT, dma_cap_mask_all.bits);

	for_each_dma_cap_mask(cap, dma_cap_mask_all) {
		channel_table[cap] = alloc_percpu(struct chan_ref_percpu);
		if (!channel_table[cap])
			goto err;
	}

	channel_table_initialized = 1;
	dma_async_client_register(&async_tx_dma);
	dma_async_client_chan_request(&async_tx_dma);

	printk(KERN_INFO "async_tx: api initialized (async)\n");

	return 0;
err:
	printk(KERN_ERR "async_tx: initialization failure\n");

	while (--cap >= 0)
		free_percpu(channel_table[cap]);

	return 1;
}

static void __exit async_tx_exit(void)
{
	enum dma_transaction_type cap;

	channel_table_initialized = 0;

	for_each_dma_cap_mask(cap, dma_cap_mask_all)
		if (channel_table[cap])
			free_percpu(channel_table[cap]);

	dma_async_client_unregister(&async_tx_dma);
}

/**
 * async_tx_find_channel - find a channel to carry out the operation or let
 *	the transaction execute synchronously
 * @depend_tx: transaction dependency
 * @tx_type: transaction type
 */
struct dma_chan *
async_tx_find_channel(struct dma_async_tx_descriptor *depend_tx,
	enum dma_transaction_type tx_type)
{
	/* see if we can keep the chain on one channel */
	if (depend_tx &&
		dma_has_cap(tx_type, depend_tx->chan->device->cap_mask))
		return depend_tx->chan;
	else if (likely(channel_table_initialized)) {
		struct dma_chan_ref *ref;
		int cpu = get_cpu();
		ref = per_cpu_ptr(channel_table[tx_type], cpu)->ref;
		put_cpu();
		return ref ? ref->chan : NULL;
	} else
		return NULL;
}
EXPORT_SYMBOL_GPL(async_tx_find_channel);
#else
static int __init async_tx_init(void)
{
	printk(KERN_INFO "async_tx: api initialized (sync-only)\n");
	return 0;
}

static void __exit async_tx_exit(void)
{
	do { } while (0);
}
#endif

void
async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
	enum async_tx_flags flags, struct dma_async_tx_descriptor *depend_tx,
	dma_async_tx_callback cb_fn, void *cb_param)
{
	tx->callback = cb_fn;
	tx->callback_param = cb_param;

	/* set this new tx to run after depend_tx if:
	 * 1/ a dependency exists (depend_tx is !NULL)
	 * 2/ the tx can not be submitted to the current channel
	 */
	if (depend_tx && depend_tx->chan != chan) {
		/* if ack is already set then we cannot be sure
		 * we are referring to the correct operation
		 */
		BUG_ON(depend_tx->ack);

		tx->parent = depend_tx;
		spin_lock_bh(&depend_tx->lock);
		list_add_tail(&tx->depend_node, &depend_tx->depend_list);
		if (depend_tx->cookie == 0) {
			struct dma_chan *dep_chan = depend_tx->chan;
			struct dma_device *dep_dev = dep_chan->device;
			dep_dev->device_dependency_added(dep_chan);
		}
		spin_unlock_bh(&depend_tx->lock);

		/* schedule an interrupt to trigger the channel switch */
		async_trigger_callback(ASYNC_TX_ACK, depend_tx, NULL, NULL);
	} else {
		tx->parent = NULL;
		tx->tx_submit(tx);
	}

	if (flags & ASYNC_TX_ACK)
		async_tx_ack(tx);

	if (depend_tx && (flags & ASYNC_TX_DEP_ACK))
		async_tx_ack(depend_tx);
}
EXPORT_SYMBOL_GPL(async_tx_submit);

/**
 * async_trigger_callback - schedules the callback function to be run after
 * any dependent operations have been completed.
 * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
 * @depend_tx: 'callback' requires the completion of this transaction
 * @cb_fn: function to call after depend_tx completes
 * @cb_param: parameter to pass to the callback routine
 */
struct dma_async_tx_descriptor *
async_trigger_callback(enum async_tx_flags flags,
	struct dma_async_tx_descriptor *depend_tx,
	dma_async_tx_callback cb_fn, void *cb_param)
{
	struct dma_chan *chan;
	struct dma_device *device;
	struct dma_async_tx_descriptor *tx;

	if (depend_tx) {
		chan = depend_tx->chan;
		device = chan->device;

		/* see if we can schedule an interrupt
		 * otherwise poll for completion
		 */
		if (device && !dma_has_cap(DMA_INTERRUPT, device->cap_mask))
			device = NULL;

		tx = device ? device->device_prep_dma_interrupt(chan) : NULL;
	} else
		tx = NULL;

	if (tx) {
		pr_debug("%s: (async)\n", __FUNCTION__);

		async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
	} else {
		pr_debug("%s: (sync)\n", __FUNCTION__);

		/* wait for any prerequisite operations */
		if (depend_tx) {
			/* if ack is already set then we cannot be sure
			 * we are referring to the correct operation
			 */
			BUG_ON(depend_tx->ack);
			if (dma_wait_for_async_tx(depend_tx) == DMA_ERROR)
				panic("%s: DMA_ERROR waiting for depend_tx\n",
					__FUNCTION__);
		}

		async_tx_sync_epilog(flags, depend_tx, cb_fn, cb_param);
	}

	return tx;
}
EXPORT_SYMBOL_GPL(async_trigger_callback);

module_init(async_tx_init);
module_exit(async_tx_exit);

MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("Asynchronous Bulk Memory Transactions API");
MODULE_LICENSE("GPL");
OpenPOWER on IntegriCloud