crypto/async_tx/async_tx.c

   1 /*
   2  * core routines for the asynchronous memory transfer/transform api
   3  *
   4  * Copyright © 2006, Intel Corporation.
   5  *
   6  *      Dan Williams <dan.j.williams@intel.com>
   7  *
   8  *      with architecture considerations by:
   9  *      Neil Brown <neilb@suse.de>
  10  *      Jeff Garzik <jeff@garzik.org>
  11  *
  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.
  15  *
  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
  19  * more details.
  20  *
  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.
  24  *
  25  */
  26 #include <linux/rculist.h>
  27 #include <linux/kernel.h>
  28 #include <linux/async_tx.h>
  29
  30 #ifdef CONFIG_DMA_ENGINE
  31 static enum dma_state_client
  32 dma_channel_add_remove(struct dma_client *client,
  33         struct dma_chan *chan, enum dma_state state);
  34
  35 static struct dma_client async_tx_dma = {
  36         .event_callback = dma_channel_add_remove,
  37         /* .cap_mask == 0 defaults to all channels */
  38 };
  39
  40 /**
  41  * dma_cap_mask_all - enable iteration over all operation types
  42  */
  43 static dma_cap_mask_t dma_cap_mask_all;
  44
  45 /**
  46  * chan_ref_percpu - tracks channel allocations per core/opertion
  47  */
  48 struct chan_ref_percpu {
  49         struct dma_chan_ref *ref;
  50 };
  51
  52 static int channel_table_initialized;
  53 static struct chan_ref_percpu *channel_table[DMA_TX_TYPE_END];
  54
  55 /**
  56  * async_tx_lock - protect modification of async_tx_master_list and serialize
  57  *      rebalance operations
  58  */
  59 static spinlock_t async_tx_lock;
  60
  61 static LIST_HEAD(async_tx_master_list);
  62
  63 /* async_tx_issue_pending_all - start all transactions on all channels */
  64 void async_tx_issue_pending_all(void)
  65 {
  66         struct dma_chan_ref *ref;
  67
  68         rcu_read_lock();
  69         list_for_each_entry_rcu(ref, &async_tx_master_list, node)
  70                 ref->chan->device->device_issue_pending(ref->chan);
  71         rcu_read_unlock();
  72 }
  73 EXPORT_SYMBOL_GPL(async_tx_issue_pending_all);
  74
  75 /* dma_wait_for_async_tx - spin wait for a transcation to complete
  76  * @tx: transaction to wait on
  77  */
  78 enum dma_status
  79 dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)
  80 {
  81         enum dma_status status;
  82         struct dma_async_tx_descriptor *iter;
  83         struct dma_async_tx_descriptor *parent;
  84
  85         if (!tx)
  86                 return DMA_SUCCESS;
  87
  88         /* poll through the dependency chain, return when tx is complete */
  89         do {
  90                 iter = tx;
  91
  92                 /* find the root of the unsubmitted dependency chain */
  93                 do {
  94                         parent = iter->parent;
  95                         if (!parent)
  96                                 break;
  97                         else
  98                                 iter = parent;
  99                 } while (parent);
 100
 101                 /* there is a small window for ->parent == NULL and
 102                  * ->cookie == -EBUSY
 103                  */
 104                 while (iter->cookie == -EBUSY)
 105                         cpu_relax();
 106
 107                 status = dma_sync_wait(iter->chan, iter->cookie);
 108         } while (status == DMA_IN_PROGRESS || (iter != tx));
 109
 110         return status;
 111 }
 112 EXPORT_SYMBOL_GPL(dma_wait_for_async_tx);
 113
 114 /* async_tx_run_dependencies - helper routine for dma drivers to process
 115  *      (start) dependent operations on their target channel
 116  * @tx: transaction with dependencies
 117  */
 118 void
 119 async_tx_run_dependencies(struct dma_async_tx_descriptor *tx)
 120 {
 121         struct dma_async_tx_descriptor *next = tx->next;
 122         struct dma_chan *chan;
 123
 124         if (!next)
 125                 return;
 126
 127         tx->next = NULL;
 128         chan = next->chan;
 129
 130         /* keep submitting up until a channel switch is detected
 131          * in that case we will be called again as a result of
 132          * processing the interrupt from async_tx_channel_switch
 133          */
 134         while (next && next->chan == chan) {
 135                 struct dma_async_tx_descriptor *_next;
 136
 137                 spin_lock_bh(&next->lock);
 138                 next->parent = NULL;
 139                 _next = next->next;
 140                 if (_next && _next->chan == chan)
 141                         next->next = NULL;
 142                 spin_unlock_bh(&next->lock);
 143
 144                 next->tx_submit(next);
 145                 next = _next;
 146         }
 147
 148         chan->device->device_issue_pending(chan);
 149 }
 150 EXPORT_SYMBOL_GPL(async_tx_run_dependencies);
 151
 152 static void
 153 free_dma_chan_ref(struct rcu_head *rcu)
 154 {
 155         struct dma_chan_ref *ref;
 156         ref = container_of(rcu, struct dma_chan_ref, rcu);
 157         kfree(ref);
 158 }
 159
 160 static void
 161 init_dma_chan_ref(struct dma_chan_ref *ref, struct dma_chan *chan)
 162 {
 163         INIT_LIST_HEAD(&ref->node);
 164         INIT_RCU_HEAD(&ref->rcu);
 165         ref->chan = chan;
 166         atomic_set(&ref->count, 0);
 167 }
 168
 169 /**
 170  * get_chan_ref_by_cap - returns the nth channel of the given capability
 171  *      defaults to returning the channel with the desired capability and the
 172  *      lowest reference count if the index can not be satisfied
 173  * @cap: capability to match
 174  * @index: nth channel desired, passing -1 has the effect of forcing the
 175  *  default return value
 176  */
 177 static struct dma_chan_ref *
 178 get_chan_ref_by_cap(enum dma_transaction_type cap, int index)
 179 {
 180         struct dma_chan_ref *ret_ref = NULL, *min_ref = NULL, *ref;
 181
 182         rcu_read_lock();
 183         list_for_each_entry_rcu(ref, &async_tx_master_list, node)
 184                 if (dma_has_cap(cap, ref->chan->device->cap_mask)) {
 185                         if (!min_ref)
 186                                 min_ref = ref;
 187                         else if (atomic_read(&ref->count) <
 188                                 atomic_read(&min_ref->count))
 189                                 min_ref = ref;
 190
 191                         if (index-- == 0) {
 192                                 ret_ref = ref;
 193                                 break;
 194                         }
 195                 }
 196         rcu_read_unlock();
 197
 198         if (!ret_ref)
 199                 ret_ref = min_ref;
 200
 201         if (ret_ref)
 202                 atomic_inc(&ret_ref->count);
 203
 204         return ret_ref;
 205 }
 206
 207 /**
 208  * async_tx_rebalance - redistribute the available channels, optimize
 209  * for cpu isolation in the SMP case, and opertaion isolation in the
 210  * uniprocessor case
 211  */
 212 static void async_tx_rebalance(void)
 213 {
 214         int cpu, cap, cpu_idx = 0;
 215         unsigned long flags;
 216
 217         if (!channel_table_initialized)
 218                 return;
 219
 220         spin_lock_irqsave(&async_tx_lock, flags);
 221
 222         /* undo the last distribution */
 223         for_each_dma_cap_mask(cap, dma_cap_mask_all)
 224                 for_each_possible_cpu(cpu) {
 225                         struct dma_chan_ref *ref =
 226                                 per_cpu_ptr(channel_table[cap], cpu)->ref;
 227                         if (ref) {
 228                                 atomic_set(&ref->count, 0);
 229                                 per_cpu_ptr(channel_table[cap], cpu)->ref =
 230                                                                         NULL;
 231                         }
 232                 }
 233
 234         for_each_dma_cap_mask(cap, dma_cap_mask_all)
 235                 for_each_online_cpu(cpu) {
 236                         struct dma_chan_ref *new;
 237                         if (NR_CPUS > 1)
 238                                 new = get_chan_ref_by_cap(cap, cpu_idx++);
 239                         else
 240                                 new = get_chan_ref_by_cap(cap, -1);
 241
 242                         per_cpu_ptr(channel_table[cap], cpu)->ref = new;
 243                 }
 244
 245         spin_unlock_irqrestore(&async_tx_lock, flags);
 246 }
 247
 248 static enum dma_state_client
 249 dma_channel_add_remove(struct dma_client *client,
 250         struct dma_chan *chan, enum dma_state state)
 251 {
 252         unsigned long found, flags;
 253         struct dma_chan_ref *master_ref, *ref;
 254         enum dma_state_client ack = DMA_DUP; /* default: take no action */
 255
 256         switch (state) {
 257         case DMA_RESOURCE_AVAILABLE:
 258                 found = 0;
 259                 rcu_read_lock();
 260                 list_for_each_entry_rcu(ref, &async_tx_master_list, node)
 261                         if (ref->chan == chan) {
 262                                 found = 1;
 263                                 break;
 264                         }
 265                 rcu_read_unlock();
 266
 267                 pr_debug("async_tx: dma resource available [%s]\n",
 268                         found ? "old" : "new");
 269
 270                 if (!found)
 271                         ack = DMA_ACK;
 272                 else
 273                         break;
 274
 275                 /* add the channel to the generic management list */
 276                 master_ref = kmalloc(sizeof(*master_ref), GFP_KERNEL);
 277                 if (master_ref) {
 278                         /* keep a reference until async_tx is unloaded */
 279                         dma_chan_get(chan);
 280                         init_dma_chan_ref(master_ref, chan);
 281                         spin_lock_irqsave(&async_tx_lock, flags);
 282                         list_add_tail_rcu(&master_ref->node,
 283                                 &async_tx_master_list);
 284                         spin_unlock_irqrestore(&async_tx_lock,
 285                                 flags);
 286                 } else {
 287                         printk(KERN_WARNING "async_tx: unable to create"
 288                                 " new master entry in response to"
 289                                 " a DMA_RESOURCE_ADDED event"
 290                                 " (-ENOMEM)\n");
 291                         return 0;
 292                 }
 293
 294                 async_tx_rebalance();
 295                 break;
 296         case DMA_RESOURCE_REMOVED:
 297                 found = 0;
 298                 spin_lock_irqsave(&async_tx_lock, flags);
 299                 list_for_each_entry(ref, &async_tx_master_list, node)
 300                         if (ref->chan == chan) {
 301                                 /* permit backing devices to go away */
 302                                 dma_chan_put(ref->chan);
 303                                 list_del_rcu(&ref->node);
 304                                 call_rcu(&ref->rcu, free_dma_chan_ref);
 305                                 found = 1;
 306                                 break;
 307                         }
 308                 spin_unlock_irqrestore(&async_tx_lock, flags);
 309
 310                 pr_debug("async_tx: dma resource removed [%s]\n",
 311                         found ? "ours" : "not ours");
 312
 313                 if (found)
 314                         ack = DMA_ACK;
 315                 else
 316                         break;
 317
 318                 async_tx_rebalance();
 319                 break;
 320         case DMA_RESOURCE_SUSPEND:
 321         case DMA_RESOURCE_RESUME:
 322                 printk(KERN_WARNING "async_tx: does not support dma channel"
 323                         " suspend/resume\n");
 324                 break;
 325         default:
 326                 BUG();
 327         }
 328
 329         return ack;
 330 }
 331
 332 static int __init
 333 async_tx_init(void)
 334 {
 335         enum dma_transaction_type cap;
 336
 337         spin_lock_init(&async_tx_lock);
 338         bitmap_fill(dma_cap_mask_all.bits, DMA_TX_TYPE_END);
 339
 340         /* an interrupt will never be an explicit operation type.
 341          * clearing this bit prevents allocation to a slot in 'channel_table'
 342          */
 343         clear_bit(DMA_INTERRUPT, dma_cap_mask_all.bits);
 344
 345         for_each_dma_cap_mask(cap, dma_cap_mask_all) {
 346                 channel_table[cap] = alloc_percpu(struct chan_ref_percpu);
 347                 if (!channel_table[cap])
 348                         goto err;
 349         }
 350
 351         channel_table_initialized = 1;
 352         dma_async_client_register(&async_tx_dma);
 353         dma_async_client_chan_request(&async_tx_dma);
 354
 355         printk(KERN_INFO "async_tx: api initialized (async)\n");
 356
 357         return 0;
 358 err:
 359         printk(KERN_ERR "async_tx: initialization failure\n");
 360
 361         while (--cap >= 0)
 362                 free_percpu(channel_table[cap]);
 363
 364         return 1;
 365 }
 366
 367 static void __exit async_tx_exit(void)
 368 {
 369         enum dma_transaction_type cap;
 370
 371         channel_table_initialized = 0;
 372
 373         for_each_dma_cap_mask(cap, dma_cap_mask_all)
 374                 if (channel_table[cap])
 375                         free_percpu(channel_table[cap]);
 376
 377         dma_async_client_unregister(&async_tx_dma);
 378 }
 379
 380 /**
 381  * __async_tx_find_channel - find a channel to carry out the operation or let
 382  *      the transaction execute synchronously
 383  * @depend_tx: transaction dependency
 384  * @tx_type: transaction type
 385  */
 386 struct dma_chan *
 387 __async_tx_find_channel(struct dma_async_tx_descriptor *depend_tx,
 388         enum dma_transaction_type tx_type)
 389 {
 390         /* see if we can keep the chain on one channel */
 391         if (depend_tx &&
 392                 dma_has_cap(tx_type, depend_tx->chan->device->cap_mask))
 393                 return depend_tx->chan;
 394         else if (likely(channel_table_initialized)) {
 395                 struct dma_chan_ref *ref;
 396                 int cpu = get_cpu();
 397                 ref = per_cpu_ptr(channel_table[tx_type], cpu)->ref;
 398                 put_cpu();
 399                 return ref ? ref->chan : NULL;
 400         } else
 401                 return NULL;
 402 }
 403 EXPORT_SYMBOL_GPL(__async_tx_find_channel);
 404 #else
 405 static int __init async_tx_init(void)
 406 {
 407         printk(KERN_INFO "async_tx: api initialized (sync-only)\n");
 408         return 0;
 409 }
 410
 411 static void __exit async_tx_exit(void)
 412 {
 413         do { } while (0);
 414 }
 415 #endif
 416
 417
 418 /**
 419  * async_tx_channel_switch - queue an interrupt descriptor with a dependency
 420  *      pre-attached.
 421  * @depend_tx: the operation that must finish before the new operation runs
 422  * @tx: the new operation
 423  */
 424 static void
 425 async_tx_channel_switch(struct dma_async_tx_descriptor *depend_tx,
 426                         struct dma_async_tx_descriptor *tx)
 427 {
 428         struct dma_chan *chan;
 429         struct dma_device *device;
 430         struct dma_async_tx_descriptor *intr_tx = (void *) ~0;
 431
 432         /* first check to see if we can still append to depend_tx */
 433         spin_lock_bh(&depend_tx->lock);
 434         if (depend_tx->parent && depend_tx->chan == tx->chan) {
 435                 tx->parent = depend_tx;
 436                 depend_tx->next = tx;
 437                 intr_tx = NULL;
 438         }
 439         spin_unlock_bh(&depend_tx->lock);
 440
 441         if (!intr_tx)
 442                 return;
 443
 444         chan = depend_tx->chan;
 445         device = chan->device;
 446
 447         /* see if we can schedule an interrupt
 448          * otherwise poll for completion
 449          */
 450         if (dma_has_cap(DMA_INTERRUPT, device->cap_mask))
 451                 intr_tx = device->device_prep_dma_interrupt(chan, 0);
 452         else
 453                 intr_tx = NULL;
 454
 455         if (intr_tx) {
 456                 intr_tx->callback = NULL;
 457                 intr_tx->callback_param = NULL;
 458                 tx->parent = intr_tx;
 459                 /* safe to set ->next outside the lock since we know we are
 460                  * not submitted yet
 461                  */
 462                 intr_tx->next = tx;
 463
 464                 /* check if we need to append */
 465                 spin_lock_bh(&depend_tx->lock);
 466                 if (depend_tx->parent) {
 467                         intr_tx->parent = depend_tx;
 468                         depend_tx->next = intr_tx;
 469                         async_tx_ack(intr_tx);
 470                         intr_tx = NULL;
 471                 }
 472                 spin_unlock_bh(&depend_tx->lock);
 473
 474                 if (intr_tx) {
 475                         intr_tx->parent = NULL;
 476                         intr_tx->tx_submit(intr_tx);
 477                         async_tx_ack(intr_tx);
 478                 }
 479         } else {
 480                 if (dma_wait_for_async_tx(depend_tx) == DMA_ERROR)
 481                         panic("%s: DMA_ERROR waiting for depend_tx\n",
 482                               __func__);
 483                 tx->tx_submit(tx);
 484         }
 485 }
 486
 487
 488 /**
 489  * submit_disposition - while holding depend_tx->lock we must avoid submitting
 490  *      new operations to prevent a circular locking dependency with
 491  *      drivers that already hold a channel lock when calling
 492  *      async_tx_run_dependencies.
 493  * @ASYNC_TX_SUBMITTED: we were able to append the new operation under the lock
 494  * @ASYNC_TX_CHANNEL_SWITCH: when the lock is dropped schedule a channel switch
 495  * @ASYNC_TX_DIRECT_SUBMIT: when the lock is dropped submit directly
 496  */
 497 enum submit_disposition {
 498         ASYNC_TX_SUBMITTED,
 499         ASYNC_TX_CHANNEL_SWITCH,
 500         ASYNC_TX_DIRECT_SUBMIT,
 501 };
 502
 503 void
 504 async_tx_submit(struct dma_chan *chan, struct dma_async_tx_descriptor *tx,
 505         enum async_tx_flags flags, struct dma_async_tx_descriptor *depend_tx,
 506         dma_async_tx_callback cb_fn, void *cb_param)
 507 {
 508         tx->callback = cb_fn;
 509         tx->callback_param = cb_param;
 510
 511         if (depend_tx) {
 512                 enum submit_disposition s;
 513
 514                 /* sanity check the dependency chain:
 515                  * 1/ if ack is already set then we cannot be sure
 516                  * we are referring to the correct operation
 517                  * 2/ dependencies are 1:1 i.e. two transactions can
 518                  * not depend on the same parent
 519                  */
 520                 BUG_ON(async_tx_test_ack(depend_tx) || depend_tx->next ||
 521                        tx->parent);
 522
 523                 /* the lock prevents async_tx_run_dependencies from missing
 524                  * the setting of ->next when ->parent != NULL
 525                  */
 526                 spin_lock_bh(&depend_tx->lock);
 527                 if (depend_tx->parent) {
 528                         /* we have a parent so we can not submit directly
 529                          * if we are staying on the same channel: append
 530                          * else: channel switch
 531                          */
 532                         if (depend_tx->chan == chan) {
 533                                 tx->parent = depend_tx;
 534                                 depend_tx->next = tx;
 535                                 s = ASYNC_TX_SUBMITTED;
 536                         } else
 537                                 s = ASYNC_TX_CHANNEL_SWITCH;
 538                 } else {
 539                         /* we do not have a parent so we may be able to submit
 540                          * directly if we are staying on the same channel
 541                          */
 542                         if (depend_tx->chan == chan)
 543                                 s = ASYNC_TX_DIRECT_SUBMIT;
 544                         else
 545                                 s = ASYNC_TX_CHANNEL_SWITCH;
 546                 }
 547                 spin_unlock_bh(&depend_tx->lock);
 548
 549                 switch (s) {
 550                 case ASYNC_TX_SUBMITTED:
 551                         break;
 552                 case ASYNC_TX_CHANNEL_SWITCH:
 553                         async_tx_channel_switch(depend_tx, tx);
 554                         break;
 555                 case ASYNC_TX_DIRECT_SUBMIT:
 556                         tx->parent = NULL;
 557                         tx->tx_submit(tx);
 558                         break;
 559                 }
 560         } else {
 561                 tx->parent = NULL;
 562                 tx->tx_submit(tx);
 563         }
 564
 565         if (flags & ASYNC_TX_ACK)
 566                 async_tx_ack(tx);
 567
 568         if (depend_tx && (flags & ASYNC_TX_DEP_ACK))
 569                 async_tx_ack(depend_tx);
 570 }
 571 EXPORT_SYMBOL_GPL(async_tx_submit);
 572
 573 /**
 574  * async_trigger_callback - schedules the callback function to be run after
 575  * any dependent operations have been completed.
 576  * @flags: ASYNC_TX_ACK, ASYNC_TX_DEP_ACK
 577  * @depend_tx: 'callback' requires the completion of this transaction
 578  * @cb_fn: function to call after depend_tx completes
 579  * @cb_param: parameter to pass to the callback routine
 580  */
 581 struct dma_async_tx_descriptor *
 582 async_trigger_callback(enum async_tx_flags flags,
 583         struct dma_async_tx_descriptor *depend_tx,
 584         dma_async_tx_callback cb_fn, void *cb_param)
 585 {
 586         struct dma_chan *chan;
 587         struct dma_device *device;
 588         struct dma_async_tx_descriptor *tx;
 589
 590         if (depend_tx) {
 591                 chan = depend_tx->chan;
 592                 device = chan->device;
 593
 594                 /* see if we can schedule an interrupt
 595                  * otherwise poll for completion
 596                  */
 597                 if (device && !dma_has_cap(DMA_INTERRUPT, device->cap_mask))
 598                         device = NULL;
 599
 600                 tx = device ? device->device_prep_dma_interrupt(chan, 0) : NULL;
 601         } else
 602                 tx = NULL;
 603
 604         if (tx) {
 605                 pr_debug("%s: (async)\n", __func__);
 606
 607                 async_tx_submit(chan, tx, flags, depend_tx, cb_fn, cb_param);
 608         } else {
 609                 pr_debug("%s: (sync)\n", __func__);
 610
 611                 /* wait for any prerequisite operations */
 612                 async_tx_quiesce(&depend_tx);
 613
 614                 async_tx_sync_epilog(cb_fn, cb_param);
 615         }
 616
 617         return tx;
 618 }
 619 EXPORT_SYMBOL_GPL(async_trigger_callback);
 620
 621 /**
 622  * async_tx_quiesce - ensure tx is complete and freeable upon return
 623  * @tx - transaction to quiesce
 624  */
 625 void async_tx_quiesce(struct dma_async_tx_descriptor **tx)
 626 {
 627         if (*tx) {
 628                 /* if ack is already set then we cannot be sure
 629                  * we are referring to the correct operation
 630                  */
 631                 BUG_ON(async_tx_test_ack(*tx));
 632                 if (dma_wait_for_async_tx(*tx) == DMA_ERROR)
 633                         panic("DMA_ERROR waiting for transaction\n");
 634                 async_tx_ack(*tx);
 635                 *tx = NULL;
 636         }
 637 }
 638 EXPORT_SYMBOL_GPL(async_tx_quiesce);
 639
 640 module_init(async_tx_init);
 641 module_exit(async_tx_exit);
 642
 643 MODULE_AUTHOR("Intel Corporation");
 644 MODULE_DESCRIPTION("Asynchronous Bulk Memory Transactions API");
 645 MODULE_LICENSE("GPL");