arch/arm/common/dmabounce.c

   1 /*
   2  *  arch/arm/common/dmabounce.c
   3  *
   4  *  Special dma_{map/unmap/dma_sync}_* routines for systems that have
   5  *  limited DMA windows. These functions utilize bounce buffers to
   6  *  copy data to/from buffers located outside the DMA region. This
   7  *  only works for systems in which DMA memory is at the bottom of
   8  *  RAM, the remainder of memory is at the top and the DMA memory
   9  *  can be marked as ZONE_DMA. Anything beyond that such as discontiguous
  10  *  DMA windows will require custom implementations that reserve memory
  11  *  areas at early bootup.
  12  *
  13  *  Original version by Brad Parker (brad@heeltoe.com)
  14  *  Re-written by Christopher Hoover <ch@murgatroid.com>
  15  *  Made generic by Deepak Saxena <dsaxena@plexity.net>
  16  *
  17  *  Copyright (C) 2002 Hewlett Packard Company.
  18  *  Copyright (C) 2004 MontaVista Software, Inc.
  19  *
  20  *  This program is free software; you can redistribute it and/or
  21  *  modify it under the terms of the GNU General Public License
  22  *  version 2 as published by the Free Software Foundation.
  23  */
  24
  25 #include <linux/module.h>
  26 #include <linux/init.h>
  27 #include <linux/slab.h>
  28 #include <linux/page-flags.h>
  29 #include <linux/device.h>
  30 #include <linux/dma-mapping.h>
  31 #include <linux/dmapool.h>
  32 #include <linux/list.h>
  33 #include <linux/scatterlist.h>
  34
  35 #include <asm/cacheflush.h>
  36
  37 #undef STATS
  38
  39 #ifdef STATS
  40 #define DO_STATS(X) do { X ; } while (0)
  41 #else
  42 #define DO_STATS(X) do { } while (0)
  43 #endif
  44
  45 /* ************************************************** */
  46
  47 struct safe_buffer {
  48         struct list_head node;
  49
  50         /* original request */
  51         void            *ptr;
  52         size_t          size;
  53         int             direction;
  54
  55         /* safe buffer info */
  56         struct dmabounce_pool *pool;
  57         void            *safe;
  58         dma_addr_t      safe_dma_addr;
  59 };
  60
  61 struct dmabounce_pool {
  62         unsigned long   size;
  63         struct dma_pool *pool;
  64 #ifdef STATS
  65         unsigned long   allocs;
  66 #endif
  67 };
  68
  69 struct dmabounce_device_info {
  70         struct device *dev;
  71         struct list_head safe_buffers;
  72 #ifdef STATS
  73         unsigned long total_allocs;
  74         unsigned long map_op_count;
  75         unsigned long bounce_count;
  76         int attr_res;
  77 #endif
  78         struct dmabounce_pool   small;
  79         struct dmabounce_pool   large;
  80
  81         rwlock_t lock;
  82
  83         int (*needs_bounce)(struct device *, dma_addr_t, size_t);
  84 };
  85
  86 #ifdef STATS
  87 static ssize_t dmabounce_show(struct device *dev, struct device_attribute *attr,
  88                               char *buf)
  89 {
  90         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
  91         return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n",
  92                 device_info->small.allocs,
  93                 device_info->large.allocs,
  94                 device_info->total_allocs - device_info->small.allocs -
  95                         device_info->large.allocs,
  96                 device_info->total_allocs,
  97                 device_info->map_op_count,
  98                 device_info->bounce_count);
  99 }
 100
 101 static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL);
 102 #endif
 103
 104
 105 /* allocate a 'safe' buffer and keep track of it */
 106 static inline struct safe_buffer *
 107 alloc_safe_buffer(struct dmabounce_device_info *device_info, void *ptr,
 108                   size_t size, enum dma_data_direction dir)
 109 {
 110         struct safe_buffer *buf;
 111         struct dmabounce_pool *pool;
 112         struct device *dev = device_info->dev;
 113         unsigned long flags;
 114
 115         dev_dbg(dev, "%s(ptr=%p, size=%d, dir=%d)\n",
 116                 __func__, ptr, size, dir);
 117
 118         if (size <= device_info->small.size) {
 119                 pool = &device_info->small;
 120         } else if (size <= device_info->large.size) {
 121                 pool = &device_info->large;
 122         } else {
 123                 pool = NULL;
 124         }
 125
 126         buf = kmalloc(sizeof(struct safe_buffer), GFP_ATOMIC);
 127         if (buf == NULL) {
 128                 dev_warn(dev, "%s: kmalloc failed\n", __func__);
 129                 return NULL;
 130         }
 131
 132         buf->ptr = ptr;
 133         buf->size = size;
 134         buf->direction = dir;
 135         buf->pool = pool;
 136
 137         if (pool) {
 138                 buf->safe = dma_pool_alloc(pool->pool, GFP_ATOMIC,
 139                                            &buf->safe_dma_addr);
 140         } else {
 141                 buf->safe = dma_alloc_coherent(dev, size, &buf->safe_dma_addr,
 142                                                GFP_ATOMIC);
 143         }
 144
 145         if (buf->safe == NULL) {
 146                 dev_warn(dev,
 147                          "%s: could not alloc dma memory (size=%d)\n",
 148                          __func__, size);
 149                 kfree(buf);
 150                 return NULL;
 151         }
 152
 153 #ifdef STATS
 154         if (pool)
 155                 pool->allocs++;
 156         device_info->total_allocs++;
 157 #endif
 158
 159         write_lock_irqsave(&device_info->lock, flags);
 160         list_add(&buf->node, &device_info->safe_buffers);
 161         write_unlock_irqrestore(&device_info->lock, flags);
 162
 163         return buf;
 164 }
 165
 166 /* determine if a buffer is from our "safe" pool */
 167 static inline struct safe_buffer *
 168 find_safe_buffer(struct dmabounce_device_info *device_info, dma_addr_t safe_dma_addr)
 169 {
 170         struct safe_buffer *b, *rb = NULL;
 171         unsigned long flags;
 172
 173         read_lock_irqsave(&device_info->lock, flags);
 174
 175         list_for_each_entry(b, &device_info->safe_buffers, node)
 176                 if (b->safe_dma_addr == safe_dma_addr) {
 177                         rb = b;
 178                         break;
 179                 }
 180
 181         read_unlock_irqrestore(&device_info->lock, flags);
 182         return rb;
 183 }
 184
 185 static inline void
 186 free_safe_buffer(struct dmabounce_device_info *device_info, struct safe_buffer *buf)
 187 {
 188         unsigned long flags;
 189
 190         dev_dbg(device_info->dev, "%s(buf=%p)\n", __func__, buf);
 191
 192         write_lock_irqsave(&device_info->lock, flags);
 193
 194         list_del(&buf->node);
 195
 196         write_unlock_irqrestore(&device_info->lock, flags);
 197
 198         if (buf->pool)
 199                 dma_pool_free(buf->pool->pool, buf->safe, buf->safe_dma_addr);
 200         else
 201                 dma_free_coherent(device_info->dev, buf->size, buf->safe,
 202                                     buf->safe_dma_addr);
 203
 204         kfree(buf);
 205 }
 206
 207 /* ************************************************** */
 208
 209 static struct safe_buffer *find_safe_buffer_dev(struct device *dev,
 210                 dma_addr_t dma_addr, const char *where)
 211 {
 212         if (!dev || !dev->archdata.dmabounce)
 213                 return NULL;
 214         if (dma_mapping_error(dev, dma_addr)) {
 215                 dev_err(dev, "Trying to %s invalid mapping\n", where);
 216                 return NULL;
 217         }
 218         return find_safe_buffer(dev->archdata.dmabounce, dma_addr);
 219 }
 220
 221 static int needs_bounce(struct device *dev, dma_addr_t dma_addr, size_t size)
 222 {
 223         if (!dev || !dev->archdata.dmabounce)
 224                 return 0;
 225
 226         if (dev->dma_mask) {
 227                 unsigned long limit, mask = *dev->dma_mask;
 228
 229                 limit = (mask + 1) & ~mask;
 230                 if (limit && size > limit) {
 231                         dev_err(dev, "DMA mapping too big (requested %#x "
 232                                 "mask %#Lx)\n", size, *dev->dma_mask);
 233                         return -E2BIG;
 234                 }
 235
 236                 /* Figure out if we need to bounce from the DMA mask. */
 237                 if ((dma_addr | (dma_addr + size - 1)) & ~mask)
 238                         return 1;
 239         }
 240
 241         return !!dev->archdata.dmabounce->needs_bounce(dev, dma_addr, size);
 242 }
 243
 244 static inline dma_addr_t map_single(struct device *dev, void *ptr, size_t size,
 245                 enum dma_data_direction dir)
 246 {
 247         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 248         struct safe_buffer *buf;
 249
 250         if (device_info)
 251                 DO_STATS ( device_info->map_op_count++ );
 252
 253         buf = alloc_safe_buffer(device_info, ptr, size, dir);
 254         if (buf == NULL) {
 255                 dev_err(dev, "%s: unable to map unsafe buffer %p!\n",
 256                        __func__, ptr);
 257                 return ~0;
 258         }
 259
 260         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 261                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 262                 buf->safe, buf->safe_dma_addr);
 263
 264         if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
 265                 dev_dbg(dev, "%s: copy unsafe %p to safe %p, size %d\n",
 266                         __func__, ptr, buf->safe, size);
 267                 memcpy(buf->safe, ptr, size);
 268         }
 269
 270         return buf->safe_dma_addr;
 271 }
 272
 273 static inline void unmap_single(struct device *dev, struct safe_buffer *buf,
 274                 size_t size, enum dma_data_direction dir)
 275 {
 276         BUG_ON(buf->size != size);
 277         BUG_ON(buf->direction != dir);
 278
 279         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 280                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 281                 buf->safe, buf->safe_dma_addr);
 282
 283         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 284
 285         if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 286                 void *ptr = buf->ptr;
 287
 288                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
 289                         __func__, buf->safe, ptr, size);
 290                 memcpy(ptr, buf->safe, size);
 291
 292                 /*
 293                  * Since we may have written to a page cache page,
 294                  * we need to ensure that the data will be coherent
 295                  * with user mappings.
 296                  */
 297                 __cpuc_flush_dcache_area(ptr, size);
 298         }
 299         free_safe_buffer(dev->archdata.dmabounce, buf);
 300 }
 301
 302 /* ************************************************** */
 303
 304 /*
 305  * see if a buffer address is in an 'unsafe' range.  if it is
 306  * allocate a 'safe' buffer and copy the unsafe buffer into it.
 307  * substitute the safe buffer for the unsafe one.
 308  * (basically move the buffer from an unsafe area to a safe one)
 309  */
 310 dma_addr_t __dma_map_page(struct device *dev, struct page *page,
 311                 unsigned long offset, size_t size, enum dma_data_direction dir)
 312 {
 313         dma_addr_t dma_addr;
 314         int ret;
 315
 316         dev_dbg(dev, "%s(page=%p,off=%#lx,size=%zx,dir=%x)\n",
 317                 __func__, page, offset, size, dir);
 318
 319         dma_addr = pfn_to_dma(dev, page_to_pfn(page)) + offset;
 320
 321         ret = needs_bounce(dev, dma_addr, size);
 322         if (ret < 0)
 323                 return ~0;
 324
 325         if (ret == 0) {
 326                 __dma_page_cpu_to_dev(page, offset, size, dir);
 327                 return dma_addr;
 328         }
 329
 330         if (PageHighMem(page)) {
 331                 dev_err(dev, "DMA buffer bouncing of HIGHMEM pages is not supported\n");
 332                 return ~0;
 333         }
 334
 335         return map_single(dev, page_address(page) + offset, size, dir);
 336 }
 337 EXPORT_SYMBOL(__dma_map_page);
 338
 339 /*
 340  * see if a mapped address was really a "safe" buffer and if so, copy
 341  * the data from the safe buffer back to the unsafe buffer and free up
 342  * the safe buffer.  (basically return things back to the way they
 343  * should be)
 344  */
 345 void __dma_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
 346                 enum dma_data_direction dir)
 347 {
 348         struct safe_buffer *buf;
 349
 350         dev_dbg(dev, "%s(dma=%#x,size=%d,dir=%x)\n",
 351                 __func__, dma_addr, size, dir);
 352
 353         buf = find_safe_buffer_dev(dev, dma_addr, __func__);
 354         if (!buf) {
 355                 __dma_page_dev_to_cpu(pfn_to_page(dma_to_pfn(dev, dma_addr)),
 356                         dma_addr & ~PAGE_MASK, size, dir);
 357                 return;
 358         }
 359
 360         unmap_single(dev, buf, size, dir);
 361 }
 362 EXPORT_SYMBOL(__dma_unmap_page);
 363
 364 int dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr,
 365                 unsigned long off, size_t sz, enum dma_data_direction dir)
 366 {
 367         struct safe_buffer *buf;
 368
 369         dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
 370                 __func__, addr, off, sz, dir);
 371
 372         buf = find_safe_buffer_dev(dev, addr, __func__);
 373         if (!buf)
 374                 return 1;
 375
 376         BUG_ON(buf->direction != dir);
 377
 378         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 379                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 380                 buf->safe, buf->safe_dma_addr);
 381
 382         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 383
 384         if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL) {
 385                 dev_dbg(dev, "%s: copy back safe %p to unsafe %p size %d\n",
 386                         __func__, buf->safe + off, buf->ptr + off, sz);
 387                 memcpy(buf->ptr + off, buf->safe + off, sz);
 388         }
 389         return 0;
 390 }
 391 EXPORT_SYMBOL(dmabounce_sync_for_cpu);
 392
 393 int dmabounce_sync_for_device(struct device *dev, dma_addr_t addr,
 394                 unsigned long off, size_t sz, enum dma_data_direction dir)
 395 {
 396         struct safe_buffer *buf;
 397
 398         dev_dbg(dev, "%s(dma=%#x,off=%#lx,sz=%zx,dir=%x)\n",
 399                 __func__, addr, off, sz, dir);
 400
 401         buf = find_safe_buffer_dev(dev, addr, __func__);
 402         if (!buf)
 403                 return 1;
 404
 405         BUG_ON(buf->direction != dir);
 406
 407         dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x) mapped to %p (dma=%#x)\n",
 408                 __func__, buf->ptr, virt_to_dma(dev, buf->ptr),
 409                 buf->safe, buf->safe_dma_addr);
 410
 411         DO_STATS(dev->archdata.dmabounce->bounce_count++);
 412
 413         if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL) {
 414                 dev_dbg(dev, "%s: copy out unsafe %p to safe %p, size %d\n",
 415                         __func__,buf->ptr + off, buf->safe + off, sz);
 416                 memcpy(buf->safe + off, buf->ptr + off, sz);
 417         }
 418         return 0;
 419 }
 420 EXPORT_SYMBOL(dmabounce_sync_for_device);
 421
 422 static int dmabounce_init_pool(struct dmabounce_pool *pool, struct device *dev,
 423                 const char *name, unsigned long size)
 424 {
 425         pool->size = size;
 426         DO_STATS(pool->allocs = 0);
 427         pool->pool = dma_pool_create(name, dev, size,
 428                                      0 /* byte alignment */,
 429                                      0 /* no page-crossing issues */);
 430
 431         return pool->pool ? 0 : -ENOMEM;
 432 }
 433
 434 int dmabounce_register_dev(struct device *dev, unsigned long small_buffer_size,
 435                 unsigned long large_buffer_size,
 436                 int (*needs_bounce_fn)(struct device *, dma_addr_t, size_t))
 437 {
 438         struct dmabounce_device_info *device_info;
 439         int ret;
 440
 441         device_info = kmalloc(sizeof(struct dmabounce_device_info), GFP_ATOMIC);
 442         if (!device_info) {
 443                 dev_err(dev,
 444                         "Could not allocated dmabounce_device_info\n");
 445                 return -ENOMEM;
 446         }
 447
 448         ret = dmabounce_init_pool(&device_info->small, dev,
 449                                   "small_dmabounce_pool", small_buffer_size);
 450         if (ret) {
 451                 dev_err(dev,
 452                         "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 453                         small_buffer_size);
 454                 goto err_free;
 455         }
 456
 457         if (large_buffer_size) {
 458                 ret = dmabounce_init_pool(&device_info->large, dev,
 459                                           "large_dmabounce_pool",
 460                                           large_buffer_size);
 461                 if (ret) {
 462                         dev_err(dev,
 463                                 "dmabounce: could not allocate DMA pool for %ld byte objects\n",
 464                                 large_buffer_size);
 465                         goto err_destroy;
 466                 }
 467         }
 468
 469         device_info->dev = dev;
 470         INIT_LIST_HEAD(&device_info->safe_buffers);
 471         rwlock_init(&device_info->lock);
 472         device_info->needs_bounce = needs_bounce_fn;
 473
 474 #ifdef STATS
 475         device_info->total_allocs = 0;
 476         device_info->map_op_count = 0;
 477         device_info->bounce_count = 0;
 478         device_info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
 479 #endif
 480
 481         dev->archdata.dmabounce = device_info;
 482
 483         dev_info(dev, "dmabounce: registered device\n");
 484
 485         return 0;
 486
 487  err_destroy:
 488         dma_pool_destroy(device_info->small.pool);
 489  err_free:
 490         kfree(device_info);
 491         return ret;
 492 }
 493 EXPORT_SYMBOL(dmabounce_register_dev);
 494
 495 void dmabounce_unregister_dev(struct device *dev)
 496 {
 497         struct dmabounce_device_info *device_info = dev->archdata.dmabounce;
 498
 499         dev->archdata.dmabounce = NULL;
 500
 501         if (!device_info) {
 502                 dev_warn(dev,
 503                          "Never registered with dmabounce but attempting"
 504                          "to unregister!\n");
 505                 return;
 506         }
 507
 508         if (!list_empty(&device_info->safe_buffers)) {
 509                 dev_err(dev,
 510                         "Removing from dmabounce with pending buffers!\n");
 511                 BUG();
 512         }
 513
 514         if (device_info->small.pool)
 515                 dma_pool_destroy(device_info->small.pool);
 516         if (device_info->large.pool)
 517                 dma_pool_destroy(device_info->large.pool);
 518
 519 #ifdef STATS
 520         if (device_info->attr_res == 0)
 521                 device_remove_file(dev, &dev_attr_dmabounce_stats);
 522 #endif
 523
 524         kfree(device_info);
 525
 526         dev_info(dev, "dmabounce: device unregistered\n");
 527 }
 528 EXPORT_SYMBOL(dmabounce_unregister_dev);
 529
 530 MODULE_AUTHOR("Christopher Hoover <ch@hpl.hp.com>, Deepak Saxena <dsaxena@plexity.net>");
 531 MODULE_DESCRIPTION("Special dma_{map/unmap/dma_sync}_* routines for systems with limited DMA windows");
 532 MODULE_LICENSE("GPL");