drivers/dma/dmaengine.c

   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 a global list of dma_device structs it is protected by a
  35  * mutex, dma_list_mutex.
  36  *
  37  * A subsystem can get access to a channel by calling dmaengine_get() followed
  38  * by dma_find_channel(), or if it has need for an exclusive channel it can call
  39  * dma_request_channel().  Once a channel is allocated a reference is taken
  40  * against its corresponding driver to disable removal.
  41  *
  42  * Each device has a channels list, which runs unlocked but is never modified
  43  * once the device is registered, it's just setup by the driver.
  44  *
  45  * See Documentation/dmaengine.txt for more details
  46  */
  47
  48 #include <linux/init.h>
  49 #include <linux/module.h>
  50 #include <linux/mm.h>
  51 #include <linux/device.h>
  52 #include <linux/dmaengine.h>
  53 #include <linux/hardirq.h>
  54 #include <linux/spinlock.h>
  55 #include <linux/percpu.h>
  56 #include <linux/rcupdate.h>
  57 #include <linux/mutex.h>
  58 #include <linux/jiffies.h>
  59 #include <linux/rculist.h>
  60 #include <linux/idr.h>
  61
  62 static DEFINE_MUTEX(dma_list_mutex);
  63 static LIST_HEAD(dma_device_list);
  64 static long dmaengine_ref_count;
  65 static struct idr dma_idr;
  66
  67 /* --- sysfs implementation --- */
  68
  69 /**
  70  * dev_to_dma_chan - convert a device pointer to the its sysfs container object
  71  * @dev - device node
  72  *
  73  * Must be called under dma_list_mutex
  74  */
  75 static struct dma_chan *dev_to_dma_chan(struct device *dev)
  76 {
  77         struct dma_chan_dev *chan_dev;
  78
  79         chan_dev = container_of(dev, typeof(*chan_dev), device);
  80         return chan_dev->chan;
  81 }
  82
  83 static ssize_t show_memcpy_count(struct device *dev, struct device_attribute *attr, char *buf)
  84 {
  85         struct dma_chan *chan;
  86         unsigned long count = 0;
  87         int i;
  88         int err;
  89
  90         mutex_lock(&dma_list_mutex);
  91         chan = dev_to_dma_chan(dev);
  92         if (chan) {
  93                 for_each_possible_cpu(i)
  94                         count += per_cpu_ptr(chan->local, i)->memcpy_count;
  95                 err = sprintf(buf, "%lu\n", count);
  96         } else
  97                 err = -ENODEV;
  98         mutex_unlock(&dma_list_mutex);
  99
 100         return err;
 101 }
 102
 103 static ssize_t show_bytes_transferred(struct device *dev, struct device_attribute *attr,
 104                                       char *buf)
 105 {
 106         struct dma_chan *chan;
 107         unsigned long count = 0;
 108         int i;
 109         int err;
 110
 111         mutex_lock(&dma_list_mutex);
 112         chan = dev_to_dma_chan(dev);
 113         if (chan) {
 114                 for_each_possible_cpu(i)
 115                         count += per_cpu_ptr(chan->local, i)->bytes_transferred;
 116                 err = sprintf(buf, "%lu\n", count);
 117         } else
 118                 err = -ENODEV;
 119         mutex_unlock(&dma_list_mutex);
 120
 121         return err;
 122 }
 123
 124 static ssize_t show_in_use(struct device *dev, struct device_attribute *attr, char *buf)
 125 {
 126         struct dma_chan *chan;
 127         int err;
 128
 129         mutex_lock(&dma_list_mutex);
 130         chan = dev_to_dma_chan(dev);
 131         if (chan)
 132                 err = sprintf(buf, "%d\n", chan->client_count);
 133         else
 134                 err = -ENODEV;
 135         mutex_unlock(&dma_list_mutex);
 136
 137         return err;
 138 }
 139
 140 static struct device_attribute dma_attrs[] = {
 141         __ATTR(memcpy_count, S_IRUGO, show_memcpy_count, NULL),
 142         __ATTR(bytes_transferred, S_IRUGO, show_bytes_transferred, NULL),
 143         __ATTR(in_use, S_IRUGO, show_in_use, NULL),
 144         __ATTR_NULL
 145 };
 146
 147 static void chan_dev_release(struct device *dev)
 148 {
 149         struct dma_chan_dev *chan_dev;
 150
 151         chan_dev = container_of(dev, typeof(*chan_dev), device);
 152         if (atomic_dec_and_test(chan_dev->idr_ref)) {
 153                 mutex_lock(&dma_list_mutex);
 154                 idr_remove(&dma_idr, chan_dev->dev_id);
 155                 mutex_unlock(&dma_list_mutex);
 156                 kfree(chan_dev->idr_ref);
 157         }
 158         kfree(chan_dev);
 159 }
 160
 161 static struct class dma_devclass = {
 162         .name           = "dma",
 163         .dev_attrs      = dma_attrs,
 164         .dev_release    = chan_dev_release,
 165 };
 166
 167 /* --- client and device registration --- */
 168
 169 #define dma_device_satisfies_mask(device, mask) \
 170         __dma_device_satisfies_mask((device), &(mask))
 171 static int
 172 __dma_device_satisfies_mask(struct dma_device *device, dma_cap_mask_t *want)
 173 {
 174         dma_cap_mask_t has;
 175
 176         bitmap_and(has.bits, want->bits, device->cap_mask.bits,
 177                 DMA_TX_TYPE_END);
 178         return bitmap_equal(want->bits, has.bits, DMA_TX_TYPE_END);
 179 }
 180
 181 static struct module *dma_chan_to_owner(struct dma_chan *chan)
 182 {
 183         return chan->device->dev->driver->owner;
 184 }
 185
 186 /**
 187  * balance_ref_count - catch up the channel reference count
 188  * @chan - channel to balance ->client_count versus dmaengine_ref_count
 189  *
 190  * balance_ref_count must be called under dma_list_mutex
 191  */
 192 static void balance_ref_count(struct dma_chan *chan)
 193 {
 194         struct module *owner = dma_chan_to_owner(chan);
 195
 196         while (chan->client_count < dmaengine_ref_count) {
 197                 __module_get(owner);
 198                 chan->client_count++;
 199         }
 200 }
 201
 202 /**
 203  * dma_chan_get - try to grab a dma channel's parent driver module
 204  * @chan - channel to grab
 205  *
 206  * Must be called under dma_list_mutex
 207  */
 208 static int dma_chan_get(struct dma_chan *chan)
 209 {
 210         int err = -ENODEV;
 211         struct module *owner = dma_chan_to_owner(chan);
 212
 213         if (chan->client_count) {
 214                 __module_get(owner);
 215                 err = 0;
 216         } else if (try_module_get(owner))
 217                 err = 0;
 218
 219         if (err == 0)
 220                 chan->client_count++;
 221
 222         /* allocate upon first client reference */
 223         if (chan->client_count == 1 && err == 0) {
 224                 int desc_cnt = chan->device->device_alloc_chan_resources(chan);
 225
 226                 if (desc_cnt < 0) {
 227                         err = desc_cnt;
 228                         chan->client_count = 0;
 229                         module_put(owner);
 230                 } else if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
 231                         balance_ref_count(chan);
 232         }
 233
 234         return err;
 235 }
 236
 237 /**
 238  * dma_chan_put - drop a reference to a dma channel's parent driver module
 239  * @chan - channel to release
 240  *
 241  * Must be called under dma_list_mutex
 242  */
 243 static void dma_chan_put(struct dma_chan *chan)
 244 {
 245         if (!chan->client_count)
 246                 return; /* this channel failed alloc_chan_resources */
 247         chan->client_count--;
 248         module_put(dma_chan_to_owner(chan));
 249         if (chan->client_count == 0)
 250                 chan->device->device_free_chan_resources(chan);
 251 }
 252
 253 enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie)
 254 {
 255         enum dma_status status;
 256         unsigned long dma_sync_wait_timeout = jiffies + msecs_to_jiffies(5000);
 257
 258         dma_async_issue_pending(chan);
 259         do {
 260                 status = dma_async_is_tx_complete(chan, cookie, NULL, NULL);
 261                 if (time_after_eq(jiffies, dma_sync_wait_timeout)) {
 262                         printk(KERN_ERR "dma_sync_wait_timeout!\n");
 263                         return DMA_ERROR;
 264                 }
 265         } while (status == DMA_IN_PROGRESS);
 266
 267         return status;
 268 }
 269 EXPORT_SYMBOL(dma_sync_wait);
 270
 271 /**
 272  * dma_cap_mask_all - enable iteration over all operation types
 273  */
 274 static dma_cap_mask_t dma_cap_mask_all;
 275
 276 /**
 277  * dma_chan_tbl_ent - tracks channel allocations per core/operation
 278  * @chan - associated channel for this entry
 279  */
 280 struct dma_chan_tbl_ent {
 281         struct dma_chan *chan;
 282 };
 283
 284 /**
 285  * channel_table - percpu lookup table for memory-to-memory offload providers
 286  */
 287 static struct dma_chan_tbl_ent *channel_table[DMA_TX_TYPE_END];
 288
 289 static int __init dma_channel_table_init(void)
 290 {
 291         enum dma_transaction_type cap;
 292         int err = 0;
 293
 294         bitmap_fill(dma_cap_mask_all.bits, DMA_TX_TYPE_END);
 295
 296         /* 'interrupt', 'private', and 'slave' are channel capabilities,
 297          * but are not associated with an operation so they do not need
 298          * an entry in the channel_table
 299          */
 300         clear_bit(DMA_INTERRUPT, dma_cap_mask_all.bits);
 301         clear_bit(DMA_PRIVATE, dma_cap_mask_all.bits);
 302         clear_bit(DMA_SLAVE, dma_cap_mask_all.bits);
 303
 304         for_each_dma_cap_mask(cap, dma_cap_mask_all) {
 305                 channel_table[cap] = alloc_percpu(struct dma_chan_tbl_ent);
 306                 if (!channel_table[cap]) {
 307                         err = -ENOMEM;
 308                         break;
 309                 }
 310         }
 311
 312         if (err) {
 313                 pr_err("dmaengine: initialization failure\n");
 314                 for_each_dma_cap_mask(cap, dma_cap_mask_all)
 315                         if (channel_table[cap])
 316                                 free_percpu(channel_table[cap]);
 317         }
 318
 319         return err;
 320 }
 321 arch_initcall(dma_channel_table_init);
 322
 323 /**
 324  * dma_find_channel - find a channel to carry out the operation
 325  * @tx_type: transaction type
 326  */
 327 struct dma_chan *dma_find_channel(enum dma_transaction_type tx_type)
 328 {
 329         struct dma_chan *chan;
 330         int cpu;
 331
 332         cpu = get_cpu();
 333         chan = per_cpu_ptr(channel_table[tx_type], cpu)->chan;
 334         put_cpu();
 335
 336         return chan;
 337 }
 338 EXPORT_SYMBOL(dma_find_channel);
 339
 340 /**
 341  * dma_issue_pending_all - flush all pending operations across all channels
 342  */
 343 void dma_issue_pending_all(void)
 344 {
 345         struct dma_device *device;
 346         struct dma_chan *chan;
 347
 348         rcu_read_lock();
 349         list_for_each_entry_rcu(device, &dma_device_list, global_node) {
 350                 if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
 351                         continue;
 352                 list_for_each_entry(chan, &device->channels, device_node)
 353                         if (chan->client_count)
 354                                 device->device_issue_pending(chan);
 355         }
 356         rcu_read_unlock();
 357 }
 358 EXPORT_SYMBOL(dma_issue_pending_all);
 359
 360 /**
 361  * nth_chan - returns the nth channel of the given capability
 362  * @cap: capability to match
 363  * @n: nth channel desired
 364  *
 365  * Defaults to returning the channel with the desired capability and the
 366  * lowest reference count when 'n' cannot be satisfied.  Must be called
 367  * under dma_list_mutex.
 368  */
 369 static struct dma_chan *nth_chan(enum dma_transaction_type cap, int n)
 370 {
 371         struct dma_device *device;
 372         struct dma_chan *chan;
 373         struct dma_chan *ret = NULL;
 374         struct dma_chan *min = NULL;
 375
 376         list_for_each_entry(device, &dma_device_list, global_node) {
 377                 if (!dma_has_cap(cap, device->cap_mask) ||
 378                     dma_has_cap(DMA_PRIVATE, device->cap_mask))
 379                         continue;
 380                 list_for_each_entry(chan, &device->channels, device_node) {
 381                         if (!chan->client_count)
 382                                 continue;
 383                         if (!min)
 384                                 min = chan;
 385                         else if (chan->table_count < min->table_count)
 386                                 min = chan;
 387
 388                         if (n-- == 0) {
 389                                 ret = chan;
 390                                 break; /* done */
 391                         }
 392                 }
 393                 if (ret)
 394                         break; /* done */
 395         }
 396
 397         if (!ret)
 398                 ret = min;
 399
 400         if (ret)
 401                 ret->table_count++;
 402
 403         return ret;
 404 }
 405
 406 /**
 407  * dma_channel_rebalance - redistribute the available channels
 408  *
 409  * Optimize for cpu isolation (each cpu gets a dedicated channel for an
 410  * operation type) in the SMP case,  and operation isolation (avoid
 411  * multi-tasking channels) in the non-SMP case.  Must be called under
 412  * dma_list_mutex.
 413  */
 414 static void dma_channel_rebalance(void)
 415 {
 416         struct dma_chan *chan;
 417         struct dma_device *device;
 418         int cpu;
 419         int cap;
 420         int n;
 421
 422         /* undo the last distribution */
 423         for_each_dma_cap_mask(cap, dma_cap_mask_all)
 424                 for_each_possible_cpu(cpu)
 425                         per_cpu_ptr(channel_table[cap], cpu)->chan = NULL;
 426
 427         list_for_each_entry(device, &dma_device_list, global_node) {
 428                 if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
 429                         continue;
 430                 list_for_each_entry(chan, &device->channels, device_node)
 431                         chan->table_count = 0;
 432         }
 433
 434         /* don't populate the channel_table if no clients are available */
 435         if (!dmaengine_ref_count)
 436                 return;
 437
 438         /* redistribute available channels */
 439         n = 0;
 440         for_each_dma_cap_mask(cap, dma_cap_mask_all)
 441                 for_each_online_cpu(cpu) {
 442                         if (num_possible_cpus() > 1)
 443                                 chan = nth_chan(cap, n++);
 444                         else
 445                                 chan = nth_chan(cap, -1);
 446
 447                         per_cpu_ptr(channel_table[cap], cpu)->chan = chan;
 448                 }
 449 }
 450
 451 static struct dma_chan *private_candidate(dma_cap_mask_t *mask, struct dma_device *dev,
 452                                           dma_filter_fn fn, void *fn_param)
 453 {
 454         struct dma_chan *chan;
 455
 456         if (!__dma_device_satisfies_mask(dev, mask)) {
 457                 pr_debug("%s: wrong capabilities\n", __func__);
 458                 return NULL;
 459         }
 460         /* devices with multiple channels need special handling as we need to
 461          * ensure that all channels are either private or public.
 462          */
 463         if (dev->chancnt > 1 && !dma_has_cap(DMA_PRIVATE, dev->cap_mask))
 464                 list_for_each_entry(chan, &dev->channels, device_node) {
 465                         /* some channels are already publicly allocated */
 466                         if (chan->client_count)
 467                                 return NULL;
 468                 }
 469
 470         list_for_each_entry(chan, &dev->channels, device_node) {
 471                 if (chan->client_count) {
 472                         pr_debug("%s: %s busy\n",
 473                                  __func__, dma_chan_name(chan));
 474                         continue;
 475                 }
 476                 if (fn && !fn(chan, fn_param)) {
 477                         pr_debug("%s: %s filter said false\n",
 478                                  __func__, dma_chan_name(chan));
 479                         continue;
 480                 }
 481                 return chan;
 482         }
 483
 484         return NULL;
 485 }
 486
 487 /**
 488  * dma_request_channel - try to allocate an exclusive channel
 489  * @mask: capabilities that the channel must satisfy
 490  * @fn: optional callback to disposition available channels
 491  * @fn_param: opaque parameter to pass to dma_filter_fn
 492  */
 493 struct dma_chan *__dma_request_channel(dma_cap_mask_t *mask, dma_filter_fn fn, void *fn_param)
 494 {
 495         struct dma_device *device, *_d;
 496         struct dma_chan *chan = NULL;
 497         int err;
 498
 499         /* Find a channel */
 500         mutex_lock(&dma_list_mutex);
 501         list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
 502                 chan = private_candidate(mask, device, fn, fn_param);
 503                 if (chan) {
 504                         /* Found a suitable channel, try to grab, prep, and
 505                          * return it.  We first set DMA_PRIVATE to disable
 506                          * balance_ref_count as this channel will not be
 507                          * published in the general-purpose allocator
 508                          */
 509                         dma_cap_set(DMA_PRIVATE, device->cap_mask);
 510                         err = dma_chan_get(chan);
 511
 512                         if (err == -ENODEV) {
 513                                 pr_debug("%s: %s module removed\n", __func__,
 514                                          dma_chan_name(chan));
 515                                 list_del_rcu(&device->global_node);
 516                         } else if (err)
 517                                 pr_err("dmaengine: failed to get %s: (%d)\n",
 518                                        dma_chan_name(chan), err);
 519                         else
 520                                 break;
 521                         chan = NULL;
 522                 }
 523         }
 524         mutex_unlock(&dma_list_mutex);
 525
 526         pr_debug("%s: %s (%s)\n", __func__, chan ? "success" : "fail",
 527                  chan ? dma_chan_name(chan) : NULL);
 528
 529         return chan;
 530 }
 531 EXPORT_SYMBOL_GPL(__dma_request_channel);
 532
 533 void dma_release_channel(struct dma_chan *chan)
 534 {
 535         mutex_lock(&dma_list_mutex);
 536         WARN_ONCE(chan->client_count != 1,
 537                   "chan reference count %d != 1\n", chan->client_count);
 538         dma_chan_put(chan);
 539         mutex_unlock(&dma_list_mutex);
 540 }
 541 EXPORT_SYMBOL_GPL(dma_release_channel);
 542
 543 /**
 544  * dmaengine_get - register interest in dma_channels
 545  */
 546 void dmaengine_get(void)
 547 {
 548         struct dma_device *device, *_d;
 549         struct dma_chan *chan;
 550         int err;
 551
 552         mutex_lock(&dma_list_mutex);
 553         dmaengine_ref_count++;
 554
 555         /* try to grab channels */
 556         list_for_each_entry_safe(device, _d, &dma_device_list, global_node) {
 557                 if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
 558                         continue;
 559                 list_for_each_entry(chan, &device->channels, device_node) {
 560                         err = dma_chan_get(chan);
 561                         if (err == -ENODEV) {
 562                                 /* module removed before we could use it */
 563                                 list_del_rcu(&device->global_node);
 564                                 break;
 565                         } else if (err)
 566                                 pr_err("dmaengine: failed to get %s: (%d)\n",
 567                                        dma_chan_name(chan), err);
 568                 }
 569         }
 570
 571         /* if this is the first reference and there were channels
 572          * waiting we need to rebalance to get those channels
 573          * incorporated into the channel table
 574          */
 575         if (dmaengine_ref_count == 1)
 576                 dma_channel_rebalance();
 577         mutex_unlock(&dma_list_mutex);
 578 }
 579 EXPORT_SYMBOL(dmaengine_get);
 580
 581 /**
 582  * dmaengine_put - let dma drivers be removed when ref_count == 0
 583  */
 584 void dmaengine_put(void)
 585 {
 586         struct dma_device *device;
 587         struct dma_chan *chan;
 588
 589         mutex_lock(&dma_list_mutex);
 590         dmaengine_ref_count--;
 591         BUG_ON(dmaengine_ref_count < 0);
 592         /* drop channel references */
 593         list_for_each_entry(device, &dma_device_list, global_node) {
 594                 if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
 595                         continue;
 596                 list_for_each_entry(chan, &device->channels, device_node)
 597                         dma_chan_put(chan);
 598         }
 599         mutex_unlock(&dma_list_mutex);
 600 }
 601 EXPORT_SYMBOL(dmaengine_put);
 602
 603 /**
 604  * dma_async_device_register - registers DMA devices found
 605  * @device: &dma_device
 606  */
 607 int dma_async_device_register(struct dma_device *device)
 608 {
 609         int chancnt = 0, rc;
 610         struct dma_chan* chan;
 611         atomic_t *idr_ref;
 612
 613         if (!device)
 614                 return -ENODEV;
 615
 616         /* validate device routines */
 617         BUG_ON(dma_has_cap(DMA_MEMCPY, device->cap_mask) &&
 618                 !device->device_prep_dma_memcpy);
 619         BUG_ON(dma_has_cap(DMA_XOR, device->cap_mask) &&
 620                 !device->device_prep_dma_xor);
 621         BUG_ON(dma_has_cap(DMA_ZERO_SUM, device->cap_mask) &&
 622                 !device->device_prep_dma_zero_sum);
 623         BUG_ON(dma_has_cap(DMA_MEMSET, device->cap_mask) &&
 624                 !device->device_prep_dma_memset);
 625         BUG_ON(dma_has_cap(DMA_INTERRUPT, device->cap_mask) &&
 626                 !device->device_prep_dma_interrupt);
 627         BUG_ON(dma_has_cap(DMA_SLAVE, device->cap_mask) &&
 628                 !device->device_prep_slave_sg);
 629         BUG_ON(dma_has_cap(DMA_SLAVE, device->cap_mask) &&
 630                 !device->device_terminate_all);
 631
 632         BUG_ON(!device->device_alloc_chan_resources);
 633         BUG_ON(!device->device_free_chan_resources);
 634         BUG_ON(!device->device_is_tx_complete);
 635         BUG_ON(!device->device_issue_pending);
 636         BUG_ON(!device->dev);
 637
 638         idr_ref = kmalloc(sizeof(*idr_ref), GFP_KERNEL);
 639         if (!idr_ref)
 640                 return -ENOMEM;
 641         atomic_set(idr_ref, 0);
 642  idr_retry:
 643         if (!idr_pre_get(&dma_idr, GFP_KERNEL))
 644                 return -ENOMEM;
 645         mutex_lock(&dma_list_mutex);
 646         rc = idr_get_new(&dma_idr, NULL, &device->dev_id);
 647         mutex_unlock(&dma_list_mutex);
 648         if (rc == -EAGAIN)
 649                 goto idr_retry;
 650         else if (rc != 0)
 651                 return rc;
 652
 653         /* represent channels in sysfs. Probably want devs too */
 654         list_for_each_entry(chan, &device->channels, device_node) {
 655                 chan->local = alloc_percpu(typeof(*chan->local));
 656                 if (chan->local == NULL)
 657                         continue;
 658                 chan->dev = kzalloc(sizeof(*chan->dev), GFP_KERNEL);
 659                 if (chan->dev == NULL) {
 660                         free_percpu(chan->local);
 661                         continue;
 662                 }
 663
 664                 chan->chan_id = chancnt++;
 665                 chan->dev->device.class = &dma_devclass;
 666                 chan->dev->device.parent = device->dev;
 667                 chan->dev->chan = chan;
 668                 chan->dev->idr_ref = idr_ref;
 669                 chan->dev->dev_id = device->dev_id;
 670                 atomic_inc(idr_ref);
 671                 dev_set_name(&chan->dev->device, "dma%dchan%d",
 672                              device->dev_id, chan->chan_id);
 673
 674                 rc = device_register(&chan->dev->device);
 675                 if (rc) {
 676                         free_percpu(chan->local);
 677                         chan->local = NULL;
 678                         goto err_out;
 679                 }
 680                 chan->client_count = 0;
 681         }
 682         device->chancnt = chancnt;
 683
 684         mutex_lock(&dma_list_mutex);
 685         /* take references on public channels */
 686         if (dmaengine_ref_count && !dma_has_cap(DMA_PRIVATE, device->cap_mask))
 687                 list_for_each_entry(chan, &device->channels, device_node) {
 688                         /* if clients are already waiting for channels we need
 689                          * to take references on their behalf
 690                          */
 691                         if (dma_chan_get(chan) == -ENODEV) {
 692                                 /* note we can only get here for the first
 693                                  * channel as the remaining channels are
 694                                  * guaranteed to get a reference
 695                                  */
 696                                 rc = -ENODEV;
 697                                 mutex_unlock(&dma_list_mutex);
 698                                 goto err_out;
 699                         }
 700                 }
 701         list_add_tail_rcu(&device->global_node, &dma_device_list);
 702         dma_channel_rebalance();
 703         mutex_unlock(&dma_list_mutex);
 704
 705         return 0;
 706
 707 err_out:
 708         list_for_each_entry(chan, &device->channels, device_node) {
 709                 if (chan->local == NULL)
 710                         continue;
 711                 mutex_lock(&dma_list_mutex);
 712                 chan->dev->chan = NULL;
 713                 mutex_unlock(&dma_list_mutex);
 714                 device_unregister(&chan->dev->device);
 715                 free_percpu(chan->local);
 716         }
 717         return rc;
 718 }
 719 EXPORT_SYMBOL(dma_async_device_register);
 720
 721 /**
 722  * dma_async_device_unregister - unregister a DMA device
 723  * @device: &dma_device
 724  *
 725  * This routine is called by dma driver exit routines, dmaengine holds module
 726  * references to prevent it being called while channels are in use.
 727  */
 728 void dma_async_device_unregister(struct dma_device *device)
 729 {
 730         struct dma_chan *chan;
 731
 732         mutex_lock(&dma_list_mutex);
 733         list_del_rcu(&device->global_node);
 734         dma_channel_rebalance();
 735         mutex_unlock(&dma_list_mutex);
 736
 737         list_for_each_entry(chan, &device->channels, device_node) {
 738                 WARN_ONCE(chan->client_count,
 739                           "%s called while %d clients hold a reference\n",
 740                           __func__, chan->client_count);
 741                 mutex_lock(&dma_list_mutex);
 742                 chan->dev->chan = NULL;
 743                 mutex_unlock(&dma_list_mutex);
 744                 device_unregister(&chan->dev->device);
 745         }
 746 }
 747 EXPORT_SYMBOL(dma_async_device_unregister);
 748
 749 /**
 750  * dma_async_memcpy_buf_to_buf - offloaded copy between virtual addresses
 751  * @chan: DMA channel to offload copy to
 752  * @dest: destination address (virtual)
 753  * @src: source address (virtual)
 754  * @len: length
 755  *
 756  * Both @dest and @src must be mappable to a bus address according to the
 757  * DMA mapping API rules for streaming mappings.
 758  * Both @dest and @src must stay memory resident (kernel memory or locked
 759  * user space pages).
 760  */
 761 dma_cookie_t
 762 dma_async_memcpy_buf_to_buf(struct dma_chan *chan, void *dest,
 763                         void *src, size_t len)
 764 {
 765         struct dma_device *dev = chan->device;
 766         struct dma_async_tx_descriptor *tx;
 767         dma_addr_t dma_dest, dma_src;
 768         dma_cookie_t cookie;
 769         int cpu;
 770
 771         dma_src = dma_map_single(dev->dev, src, len, DMA_TO_DEVICE);
 772         dma_dest = dma_map_single(dev->dev, dest, len, DMA_FROM_DEVICE);
 773         tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len,
 774                                          DMA_CTRL_ACK);
 775
 776         if (!tx) {
 777                 dma_unmap_single(dev->dev, dma_src, len, DMA_TO_DEVICE);
 778                 dma_unmap_single(dev->dev, dma_dest, len, DMA_FROM_DEVICE);
 779                 return -ENOMEM;
 780         }
 781
 782         tx->callback = NULL;
 783         cookie = tx->tx_submit(tx);
 784
 785         cpu = get_cpu();
 786         per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
 787         per_cpu_ptr(chan->local, cpu)->memcpy_count++;
 788         put_cpu();
 789
 790         return cookie;
 791 }
 792 EXPORT_SYMBOL(dma_async_memcpy_buf_to_buf);
 793
 794 /**
 795  * dma_async_memcpy_buf_to_pg - offloaded copy from address to page
 796  * @chan: DMA channel to offload copy to
 797  * @page: destination page
 798  * @offset: offset in page to copy to
 799  * @kdata: source address (virtual)
 800  * @len: length
 801  *
 802  * Both @page/@offset and @kdata must be mappable to a bus address according
 803  * to the DMA mapping API rules for streaming mappings.
 804  * Both @page/@offset and @kdata must stay memory resident (kernel memory or
 805  * locked user space pages)
 806  */
 807 dma_cookie_t
 808 dma_async_memcpy_buf_to_pg(struct dma_chan *chan, struct page *page,
 809                         unsigned int offset, void *kdata, size_t len)
 810 {
 811         struct dma_device *dev = chan->device;
 812         struct dma_async_tx_descriptor *tx;
 813         dma_addr_t dma_dest, dma_src;
 814         dma_cookie_t cookie;
 815         int cpu;
 816
 817         dma_src = dma_map_single(dev->dev, kdata, len, DMA_TO_DEVICE);
 818         dma_dest = dma_map_page(dev->dev, page, offset, len, DMA_FROM_DEVICE);
 819         tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len,
 820                                          DMA_CTRL_ACK);
 821
 822         if (!tx) {
 823                 dma_unmap_single(dev->dev, dma_src, len, DMA_TO_DEVICE);
 824                 dma_unmap_page(dev->dev, dma_dest, len, DMA_FROM_DEVICE);
 825                 return -ENOMEM;
 826         }
 827
 828         tx->callback = NULL;
 829         cookie = tx->tx_submit(tx);
 830
 831         cpu = get_cpu();
 832         per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
 833         per_cpu_ptr(chan->local, cpu)->memcpy_count++;
 834         put_cpu();
 835
 836         return cookie;
 837 }
 838 EXPORT_SYMBOL(dma_async_memcpy_buf_to_pg);
 839
 840 /**
 841  * dma_async_memcpy_pg_to_pg - offloaded copy from page to page
 842  * @chan: DMA channel to offload copy to
 843  * @dest_pg: destination page
 844  * @dest_off: offset in page to copy to
 845  * @src_pg: source page
 846  * @src_off: offset in page to copy from
 847  * @len: length
 848  *
 849  * Both @dest_page/@dest_off and @src_page/@src_off must be mappable to a bus
 850  * address according to the DMA mapping API rules for streaming mappings.
 851  * Both @dest_page/@dest_off and @src_page/@src_off must stay memory resident
 852  * (kernel memory or locked user space pages).
 853  */
 854 dma_cookie_t
 855 dma_async_memcpy_pg_to_pg(struct dma_chan *chan, struct page *dest_pg,
 856         unsigned int dest_off, struct page *src_pg, unsigned int src_off,
 857         size_t len)
 858 {
 859         struct dma_device *dev = chan->device;
 860         struct dma_async_tx_descriptor *tx;
 861         dma_addr_t dma_dest, dma_src;
 862         dma_cookie_t cookie;
 863         int cpu;
 864
 865         dma_src = dma_map_page(dev->dev, src_pg, src_off, len, DMA_TO_DEVICE);
 866         dma_dest = dma_map_page(dev->dev, dest_pg, dest_off, len,
 867                                 DMA_FROM_DEVICE);
 868         tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len,
 869                                          DMA_CTRL_ACK);
 870
 871         if (!tx) {
 872                 dma_unmap_page(dev->dev, dma_src, len, DMA_TO_DEVICE);
 873                 dma_unmap_page(dev->dev, dma_dest, len, DMA_FROM_DEVICE);
 874                 return -ENOMEM;
 875         }
 876
 877         tx->callback = NULL;
 878         cookie = tx->tx_submit(tx);
 879
 880         cpu = get_cpu();
 881         per_cpu_ptr(chan->local, cpu)->bytes_transferred += len;
 882         per_cpu_ptr(chan->local, cpu)->memcpy_count++;
 883         put_cpu();
 884
 885         return cookie;
 886 }
 887 EXPORT_SYMBOL(dma_async_memcpy_pg_to_pg);
 888
 889 void dma_async_tx_descriptor_init(struct dma_async_tx_descriptor *tx,
 890         struct dma_chan *chan)
 891 {
 892         tx->chan = chan;
 893         spin_lock_init(&tx->lock);
 894 }
 895 EXPORT_SYMBOL(dma_async_tx_descriptor_init);
 896
 897 /* dma_wait_for_async_tx - spin wait for a transaction to complete
 898  * @tx: in-flight transaction to wait on
 899  *
 900  * This routine assumes that tx was obtained from a call to async_memcpy,
 901  * async_xor, async_memset, etc which ensures that tx is "in-flight" (prepped
 902  * and submitted).  Walking the parent chain is only meant to cover for DMA
 903  * drivers that do not implement the DMA_INTERRUPT capability and may race with
 904  * the driver's descriptor cleanup routine.
 905  */
 906 enum dma_status
 907 dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx)
 908 {
 909         enum dma_status status;
 910         struct dma_async_tx_descriptor *iter;
 911         struct dma_async_tx_descriptor *parent;
 912
 913         if (!tx)
 914                 return DMA_SUCCESS;
 915
 916         WARN_ONCE(tx->parent, "%s: speculatively walking dependency chain for"
 917                   " %s\n", __func__, dma_chan_name(tx->chan));
 918
 919         /* poll through the dependency chain, return when tx is complete */
 920         do {
 921                 iter = tx;
 922
 923                 /* find the root of the unsubmitted dependency chain */
 924                 do {
 925                         parent = iter->parent;
 926                         if (!parent)
 927                                 break;
 928                         else
 929                                 iter = parent;
 930                 } while (parent);
 931
 932                 /* there is a small window for ->parent == NULL and
 933                  * ->cookie == -EBUSY
 934                  */
 935                 while (iter->cookie == -EBUSY)
 936                         cpu_relax();
 937
 938                 status = dma_sync_wait(iter->chan, iter->cookie);
 939         } while (status == DMA_IN_PROGRESS || (iter != tx));
 940
 941         return status;
 942 }
 943 EXPORT_SYMBOL_GPL(dma_wait_for_async_tx);
 944
 945 /* dma_run_dependencies - helper routine for dma drivers to process
 946  *      (start) dependent operations on their target channel
 947  * @tx: transaction with dependencies
 948  */
 949 void dma_run_dependencies(struct dma_async_tx_descriptor *tx)
 950 {
 951         struct dma_async_tx_descriptor *dep = tx->next;
 952         struct dma_async_tx_descriptor *dep_next;
 953         struct dma_chan *chan;
 954
 955         if (!dep)
 956                 return;
 957
 958         /* we'll submit tx->next now, so clear the link */
 959         tx->next = NULL;
 960         chan = dep->chan;
 961
 962         /* keep submitting up until a channel switch is detected
 963          * in that case we will be called again as a result of
 964          * processing the interrupt from async_tx_channel_switch
 965          */
 966         for (; dep; dep = dep_next) {
 967                 spin_lock_bh(&dep->lock);
 968                 dep->parent = NULL;
 969                 dep_next = dep->next;
 970                 if (dep_next && dep_next->chan == chan)
 971                         dep->next = NULL; /* ->next will be submitted */
 972                 else
 973                         dep_next = NULL; /* submit current dep and terminate */
 974                 spin_unlock_bh(&dep->lock);
 975
 976                 dep->tx_submit(dep);
 977         }
 978
 979         chan->device->device_issue_pending(chan);
 980 }
 981 EXPORT_SYMBOL_GPL(dma_run_dependencies);
 982
 983 static int __init dma_bus_init(void)
 984 {
 985         idr_init(&dma_idr);
 986         mutex_init(&dma_list_mutex);
 987         return class_register(&dma_devclass);
 988 }
 989 arch_initcall(dma_bus_init);
 990
 991