mm/dmapool.c

   1 /*
   2  * DMA Pool allocator
   3  *
   4  * Copyright 2001 David Brownell
   5  * Copyright 2007 Intel Corporation
   6  *   Author: Matthew Wilcox <willy@linux.intel.com>
   7  *
   8  * This software may be redistributed and/or modified under the terms of
   9  * the GNU General Public License ("GPL") version 2 as published by the
  10  * Free Software Foundation.
  11  *
  12  * This allocator returns small blocks of a given size which are DMA-able by
  13  * the given device.  It uses the dma_alloc_coherent page allocator to get
  14  * new pages, then splits them up into blocks of the required size.
  15  * Many older drivers still have their own code to do this.
  16  *
  17  * The current design of this allocator is fairly simple.  The pool is
  18  * represented by the 'struct dma_pool' which keeps a doubly-linked list of
  19  * allocated pages.  Each page in the page_list is split into blocks of at
  20  * least 'size' bytes.  Free blocks are tracked in an unsorted singly-linked
  21  * list of free blocks within the page.  Used blocks aren't tracked, but we
  22  * keep a count of how many are currently allocated from each page.
  23  */
  24
  25 #include <linux/device.h>
  26 #include <linux/dma-mapping.h>
  27 #include <linux/dmapool.h>
  28 #include <linux/kernel.h>
  29 #include <linux/list.h>
  30 #include <linux/export.h>
  31 #include <linux/mutex.h>
  32 #include <linux/poison.h>
  33 #include <linux/sched.h>
  34 #include <linux/slab.h>
  35 #include <linux/stat.h>
  36 #include <linux/spinlock.h>
  37 #include <linux/string.h>
  38 #include <linux/types.h>
  39 #include <linux/wait.h>
  40
  41 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
  42 #define DMAPOOL_DEBUG 1
  43 #endif
  44
  45 struct dma_pool {               /* the pool */
  46         struct list_head page_list;
  47         spinlock_t lock;
  48         size_t size;
  49         struct device *dev;
  50         size_t allocation;
  51         size_t boundary;
  52         char name[32];
  53         struct list_head pools;
  54 };
  55
  56 struct dma_page {               /* cacheable header for 'allocation' bytes */
  57         struct list_head page_list;
  58         void *vaddr;
  59         dma_addr_t dma;
  60         unsigned int in_use;
  61         unsigned int offset;
  62 };
  63
  64 static DEFINE_MUTEX(pools_lock);
  65
  66 static ssize_t
  67 show_pools(struct device *dev, struct device_attribute *attr, char *buf)
  68 {
  69         unsigned temp;
  70         unsigned size;
  71         char *next;
  72         struct dma_page *page;
  73         struct dma_pool *pool;
  74
  75         next = buf;
  76         size = PAGE_SIZE;
  77
  78         temp = scnprintf(next, size, "poolinfo - 0.1\n");
  79         size -= temp;
  80         next += temp;
  81
  82         mutex_lock(&pools_lock);
  83         list_for_each_entry(pool, &dev->dma_pools, pools) {
  84                 unsigned pages = 0;
  85                 unsigned blocks = 0;
  86
  87                 spin_lock_irq(&pool->lock);
  88                 list_for_each_entry(page, &pool->page_list, page_list) {
  89                         pages++;
  90                         blocks += page->in_use;
  91                 }
  92                 spin_unlock_irq(&pool->lock);
  93
  94                 /* per-pool info, no real statistics yet */
  95                 temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
  96                                  pool->name, blocks,
  97                                  pages * (pool->allocation / pool->size),
  98                                  pool->size, pages);
  99                 size -= temp;
 100                 next += temp;
 101         }
 102         mutex_unlock(&pools_lock);
 103
 104         return PAGE_SIZE - size;
 105 }
 106
 107 static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
 108
 109 /**
 110  * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
 111  * @name: name of pool, for diagnostics
 112  * @dev: device that will be doing the DMA
 113  * @size: size of the blocks in this pool.
 114  * @align: alignment requirement for blocks; must be a power of two
 115  * @boundary: returned blocks won't cross this power of two boundary
 116  * Context: !in_interrupt()
 117  *
 118  * Returns a dma allocation pool with the requested characteristics, or
 119  * null if one can't be created.  Given one of these pools, dma_pool_alloc()
 120  * may be used to allocate memory.  Such memory will all have "consistent"
 121  * DMA mappings, accessible by the device and its driver without using
 122  * cache flushing primitives.  The actual size of blocks allocated may be
 123  * larger than requested because of alignment.
 124  *
 125  * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
 126  * cross that size boundary.  This is useful for devices which have
 127  * addressing restrictions on individual DMA transfers, such as not crossing
 128  * boundaries of 4KBytes.
 129  */
 130 struct dma_pool *dma_pool_create(const char *name, struct device *dev,
 131                                  size_t size, size_t align, size_t boundary)
 132 {
 133         struct dma_pool *retval;
 134         size_t allocation;
 135
 136         if (align == 0) {
 137                 align = 1;
 138         } else if (align & (align - 1)) {
 139                 return NULL;
 140         }
 141
 142         if (size == 0) {
 143                 return NULL;
 144         } else if (size < 4) {
 145                 size = 4;
 146         }
 147
 148         if ((size % align) != 0)
 149                 size = ALIGN(size, align);
 150
 151         allocation = max_t(size_t, size, PAGE_SIZE);
 152
 153         if (!boundary) {
 154                 boundary = allocation;
 155         } else if ((boundary < size) || (boundary & (boundary - 1))) {
 156                 return NULL;
 157         }
 158
 159         retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
 160         if (!retval)
 161                 return retval;
 162
 163         strlcpy(retval->name, name, sizeof(retval->name));
 164
 165         retval->dev = dev;
 166
 167         INIT_LIST_HEAD(&retval->page_list);
 168         spin_lock_init(&retval->lock);
 169         retval->size = size;
 170         retval->boundary = boundary;
 171         retval->allocation = allocation;
 172
 173         INIT_LIST_HEAD(&retval->pools);
 174
 175         mutex_lock(&pools_lock);
 176         if (list_empty(&dev->dma_pools) &&
 177             device_create_file(dev, &dev_attr_pools)) {
 178                 kfree(retval);
 179                 return NULL;
 180         } else
 181                 list_add(&retval->pools, &dev->dma_pools);
 182         mutex_unlock(&pools_lock);
 183
 184         return retval;
 185 }
 186 EXPORT_SYMBOL(dma_pool_create);
 187
 188 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
 189 {
 190         unsigned int offset = 0;
 191         unsigned int next_boundary = pool->boundary;
 192
 193         do {
 194                 unsigned int next = offset + pool->size;
 195                 if (unlikely((next + pool->size) >= next_boundary)) {
 196                         next = next_boundary;
 197                         next_boundary += pool->boundary;
 198                 }
 199                 *(int *)(page->vaddr + offset) = next;
 200                 offset = next;
 201         } while (offset < pool->allocation);
 202 }
 203
 204 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
 205 {
 206         struct dma_page *page;
 207
 208         page = kmalloc(sizeof(*page), mem_flags);
 209         if (!page)
 210                 return NULL;
 211         page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
 212                                          &page->dma, mem_flags);
 213         if (page->vaddr) {
 214 #ifdef  DMAPOOL_DEBUG
 215                 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 216 #endif
 217                 pool_initialise_page(pool, page);
 218                 page->in_use = 0;
 219                 page->offset = 0;
 220         } else {
 221                 kfree(page);
 222                 page = NULL;
 223         }
 224         return page;
 225 }
 226
 227 static inline int is_page_busy(struct dma_page *page)
 228 {
 229         return page->in_use != 0;
 230 }
 231
 232 static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
 233 {
 234         dma_addr_t dma = page->dma;
 235
 236 #ifdef  DMAPOOL_DEBUG
 237         memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 238 #endif
 239         dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
 240         list_del(&page->page_list);
 241         kfree(page);
 242 }
 243
 244 /**
 245  * dma_pool_destroy - destroys a pool of dma memory blocks.
 246  * @pool: dma pool that will be destroyed
 247  * Context: !in_interrupt()
 248  *
 249  * Caller guarantees that no more memory from the pool is in use,
 250  * and that nothing will try to use the pool after this call.
 251  */
 252 void dma_pool_destroy(struct dma_pool *pool)
 253 {
 254         mutex_lock(&pools_lock);
 255         list_del(&pool->pools);
 256         if (pool->dev && list_empty(&pool->dev->dma_pools))
 257                 device_remove_file(pool->dev, &dev_attr_pools);
 258         mutex_unlock(&pools_lock);
 259
 260         while (!list_empty(&pool->page_list)) {
 261                 struct dma_page *page;
 262                 page = list_entry(pool->page_list.next,
 263                                   struct dma_page, page_list);
 264                 if (is_page_busy(page)) {
 265                         if (pool->dev)
 266                                 dev_err(pool->dev,
 267                                         "dma_pool_destroy %s, %p busy\n",
 268                                         pool->name, page->vaddr);
 269                         else
 270                                 printk(KERN_ERR
 271                                        "dma_pool_destroy %s, %p busy\n",
 272                                        pool->name, page->vaddr);
 273                         /* leak the still-in-use consistent memory */
 274                         list_del(&page->page_list);
 275                         kfree(page);
 276                 } else
 277                         pool_free_page(pool, page);
 278         }
 279
 280         kfree(pool);
 281 }
 282 EXPORT_SYMBOL(dma_pool_destroy);
 283
 284 /**
 285  * dma_pool_alloc - get a block of consistent memory
 286  * @pool: dma pool that will produce the block
 287  * @mem_flags: GFP_* bitmask
 288  * @handle: pointer to dma address of block
 289  *
 290  * This returns the kernel virtual address of a currently unused block,
 291  * and reports its dma address through the handle.
 292  * If such a memory block can't be allocated, %NULL is returned.
 293  */
 294 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
 295                      dma_addr_t *handle)
 296 {
 297         unsigned long flags;
 298         struct dma_page *page;
 299         size_t offset;
 300         void *retval;
 301
 302         might_sleep_if(mem_flags & __GFP_WAIT);
 303
 304         spin_lock_irqsave(&pool->lock, flags);
 305         list_for_each_entry(page, &pool->page_list, page_list) {
 306                 if (page->offset < pool->allocation)
 307                         goto ready;
 308         }
 309
 310         /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
 311         spin_unlock_irqrestore(&pool->lock, flags);
 312
 313         page = pool_alloc_page(pool, mem_flags);
 314         if (!page)
 315                 return NULL;
 316
 317         spin_lock_irqsave(&pool->lock, flags);
 318
 319         list_add(&page->page_list, &pool->page_list);
 320  ready:
 321         page->in_use++;
 322         offset = page->offset;
 323         page->offset = *(int *)(page->vaddr + offset);
 324         retval = offset + page->vaddr;
 325         *handle = offset + page->dma;
 326 #ifdef  DMAPOOL_DEBUG
 327         {
 328                 int i;
 329                 u8 *data = retval;
 330                 /* page->offset is stored in first 4 bytes */
 331                 for (i = sizeof(page->offset); i < pool->size; i++) {
 332                         if (data[i] == POOL_POISON_FREED)
 333                                 continue;
 334                         if (pool->dev)
 335                                 dev_err(pool->dev,
 336                                         "dma_pool_alloc %s, %p (corrupted)\n",
 337                                         pool->name, retval);
 338                         else
 339                                 pr_err("dma_pool_alloc %s, %p (corrupted)\n",
 340                                         pool->name, retval);
 341
 342                         /*
 343                          * Dump the first 4 bytes even if they are not
 344                          * POOL_POISON_FREED
 345                          */
 346                         print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
 347                                         data, pool->size, 1);
 348                         break;
 349                 }
 350         }
 351         memset(retval, POOL_POISON_ALLOCATED, pool->size);
 352 #endif
 353         spin_unlock_irqrestore(&pool->lock, flags);
 354         return retval;
 355 }
 356 EXPORT_SYMBOL(dma_pool_alloc);
 357
 358 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
 359 {
 360         struct dma_page *page;
 361
 362         list_for_each_entry(page, &pool->page_list, page_list) {
 363                 if (dma < page->dma)
 364                         continue;
 365                 if (dma < (page->dma + pool->allocation))
 366                         return page;
 367         }
 368         return NULL;
 369 }
 370
 371 /**
 372  * dma_pool_free - put block back into dma pool
 373  * @pool: the dma pool holding the block
 374  * @vaddr: virtual address of block
 375  * @dma: dma address of block
 376  *
 377  * Caller promises neither device nor driver will again touch this block
 378  * unless it is first re-allocated.
 379  */
 380 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 381 {
 382         struct dma_page *page;
 383         unsigned long flags;
 384         unsigned int offset;
 385
 386         spin_lock_irqsave(&pool->lock, flags);
 387         page = pool_find_page(pool, dma);
 388         if (!page) {
 389                 spin_unlock_irqrestore(&pool->lock, flags);
 390                 if (pool->dev)
 391                         dev_err(pool->dev,
 392                                 "dma_pool_free %s, %p/%lx (bad dma)\n",
 393                                 pool->name, vaddr, (unsigned long)dma);
 394                 else
 395                         printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
 396                                pool->name, vaddr, (unsigned long)dma);
 397                 return;
 398         }
 399
 400         offset = vaddr - page->vaddr;
 401 #ifdef  DMAPOOL_DEBUG
 402         if ((dma - page->dma) != offset) {
 403                 spin_unlock_irqrestore(&pool->lock, flags);
 404                 if (pool->dev)
 405                         dev_err(pool->dev,
 406                                 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 407                                 pool->name, vaddr, (unsigned long long)dma);
 408                 else
 409                         printk(KERN_ERR
 410                                "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 411                                pool->name, vaddr, (unsigned long long)dma);
 412                 return;
 413         }
 414         {
 415                 unsigned int chain = page->offset;
 416                 while (chain < pool->allocation) {
 417                         if (chain != offset) {
 418                                 chain = *(int *)(page->vaddr + chain);
 419                                 continue;
 420                         }
 421                         spin_unlock_irqrestore(&pool->lock, flags);
 422                         if (pool->dev)
 423                                 dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
 424                                         "already free\n", pool->name,
 425                                         (unsigned long long)dma);
 426                         else
 427                                 printk(KERN_ERR "dma_pool_free %s, dma %Lx "
 428                                         "already free\n", pool->name,
 429                                         (unsigned long long)dma);
 430                         return;
 431                 }
 432         }
 433         memset(vaddr, POOL_POISON_FREED, pool->size);
 434 #endif
 435
 436         page->in_use--;
 437         *(int *)vaddr = page->offset;
 438         page->offset = offset;
 439         /*
 440          * Resist a temptation to do
 441          *    if (!is_page_busy(page)) pool_free_page(pool, page);
 442          * Better have a few empty pages hang around.
 443          */
 444         spin_unlock_irqrestore(&pool->lock, flags);
 445 }
 446 EXPORT_SYMBOL(dma_pool_free);
 447
 448 /*
 449  * Managed DMA pool
 450  */
 451 static void dmam_pool_release(struct device *dev, void *res)
 452 {
 453         struct dma_pool *pool = *(struct dma_pool **)res;
 454
 455         dma_pool_destroy(pool);
 456 }
 457
 458 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
 459 {
 460         return *(struct dma_pool **)res == match_data;
 461 }
 462
 463 /**
 464  * dmam_pool_create - Managed dma_pool_create()
 465  * @name: name of pool, for diagnostics
 466  * @dev: device that will be doing the DMA
 467  * @size: size of the blocks in this pool.
 468  * @align: alignment requirement for blocks; must be a power of two
 469  * @allocation: returned blocks won't cross this boundary (or zero)
 470  *
 471  * Managed dma_pool_create().  DMA pool created with this function is
 472  * automatically destroyed on driver detach.
 473  */
 474 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
 475                                   size_t size, size_t align, size_t allocation)
 476 {
 477         struct dma_pool **ptr, *pool;
 478
 479         ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
 480         if (!ptr)
 481                 return NULL;
 482
 483         pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
 484         if (pool)
 485                 devres_add(dev, ptr);
 486         else
 487                 devres_free(ptr);
 488
 489         return pool;
 490 }
 491 EXPORT_SYMBOL(dmam_pool_create);
 492
 493 /**
 494  * dmam_pool_destroy - Managed dma_pool_destroy()
 495  * @pool: dma pool that will be destroyed
 496  *
 497  * Managed dma_pool_destroy().
 498  */
 499 void dmam_pool_destroy(struct dma_pool *pool)
 500 {
 501         struct device *dev = pool->dev;
 502
 503         WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
 504 }
 505 EXPORT_SYMBOL(dmam_pool_destroy);