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         if (dev) {
 174                 int ret;
 175
 176                 mutex_lock(&pools_lock);
 177                 if (list_empty(&dev->dma_pools))
 178                         ret = device_create_file(dev, &dev_attr_pools);
 179                 else
 180                         ret = 0;
 181                 /* note:  not currently insisting "name" be unique */
 182                 if (!ret)
 183                         list_add(&retval->pools, &dev->dma_pools);
 184                 else {
 185                         kfree(retval);
 186                         retval = NULL;
 187                 }
 188                 mutex_unlock(&pools_lock);
 189         } else
 190                 INIT_LIST_HEAD(&retval->pools);
 191
 192         return retval;
 193 }
 194 EXPORT_SYMBOL(dma_pool_create);
 195
 196 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
 197 {
 198         unsigned int offset = 0;
 199         unsigned int next_boundary = pool->boundary;
 200
 201         do {
 202                 unsigned int next = offset + pool->size;
 203                 if (unlikely((next + pool->size) >= next_boundary)) {
 204                         next = next_boundary;
 205                         next_boundary += pool->boundary;
 206                 }
 207                 *(int *)(page->vaddr + offset) = next;
 208                 offset = next;
 209         } while (offset < pool->allocation);
 210 }
 211
 212 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
 213 {
 214         struct dma_page *page;
 215
 216         page = kmalloc(sizeof(*page), mem_flags);
 217         if (!page)
 218                 return NULL;
 219         page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
 220                                          &page->dma, mem_flags);
 221         if (page->vaddr) {
 222 #ifdef  DMAPOOL_DEBUG
 223                 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 224 #endif
 225                 pool_initialise_page(pool, page);
 226                 page->in_use = 0;
 227                 page->offset = 0;
 228         } else {
 229                 kfree(page);
 230                 page = NULL;
 231         }
 232         return page;
 233 }
 234
 235 static inline int is_page_busy(struct dma_page *page)
 236 {
 237         return page->in_use != 0;
 238 }
 239
 240 static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
 241 {
 242         dma_addr_t dma = page->dma;
 243
 244 #ifdef  DMAPOOL_DEBUG
 245         memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 246 #endif
 247         dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
 248         list_del(&page->page_list);
 249         kfree(page);
 250 }
 251
 252 /**
 253  * dma_pool_destroy - destroys a pool of dma memory blocks.
 254  * @pool: dma pool that will be destroyed
 255  * Context: !in_interrupt()
 256  *
 257  * Caller guarantees that no more memory from the pool is in use,
 258  * and that nothing will try to use the pool after this call.
 259  */
 260 void dma_pool_destroy(struct dma_pool *pool)
 261 {
 262         mutex_lock(&pools_lock);
 263         list_del(&pool->pools);
 264         if (pool->dev && list_empty(&pool->dev->dma_pools))
 265                 device_remove_file(pool->dev, &dev_attr_pools);
 266         mutex_unlock(&pools_lock);
 267
 268         while (!list_empty(&pool->page_list)) {
 269                 struct dma_page *page;
 270                 page = list_entry(pool->page_list.next,
 271                                   struct dma_page, page_list);
 272                 if (is_page_busy(page)) {
 273                         if (pool->dev)
 274                                 dev_err(pool->dev,
 275                                         "dma_pool_destroy %s, %p busy\n",
 276                                         pool->name, page->vaddr);
 277                         else
 278                                 printk(KERN_ERR
 279                                        "dma_pool_destroy %s, %p busy\n",
 280                                        pool->name, page->vaddr);
 281                         /* leak the still-in-use consistent memory */
 282                         list_del(&page->page_list);
 283                         kfree(page);
 284                 } else
 285                         pool_free_page(pool, page);
 286         }
 287
 288         kfree(pool);
 289 }
 290 EXPORT_SYMBOL(dma_pool_destroy);
 291
 292 /**
 293  * dma_pool_alloc - get a block of consistent memory
 294  * @pool: dma pool that will produce the block
 295  * @mem_flags: GFP_* bitmask
 296  * @handle: pointer to dma address of block
 297  *
 298  * This returns the kernel virtual address of a currently unused block,
 299  * and reports its dma address through the handle.
 300  * If such a memory block can't be allocated, %NULL is returned.
 301  */
 302 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
 303                      dma_addr_t *handle)
 304 {
 305         unsigned long flags;
 306         struct dma_page *page;
 307         size_t offset;
 308         void *retval;
 309
 310         might_sleep_if(mem_flags & __GFP_WAIT);
 311
 312         spin_lock_irqsave(&pool->lock, flags);
 313         list_for_each_entry(page, &pool->page_list, page_list) {
 314                 if (page->offset < pool->allocation)
 315                         goto ready;
 316         }
 317
 318         /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
 319         spin_unlock_irqrestore(&pool->lock, flags);
 320
 321         page = pool_alloc_page(pool, mem_flags);
 322         if (!page)
 323                 return NULL;
 324
 325         spin_lock_irqsave(&pool->lock, flags);
 326
 327         list_add(&page->page_list, &pool->page_list);
 328  ready:
 329         page->in_use++;
 330         offset = page->offset;
 331         page->offset = *(int *)(page->vaddr + offset);
 332         retval = offset + page->vaddr;
 333         *handle = offset + page->dma;
 334 #ifdef  DMAPOOL_DEBUG
 335         memset(retval, POOL_POISON_ALLOCATED, pool->size);
 336 #endif
 337         spin_unlock_irqrestore(&pool->lock, flags);
 338         return retval;
 339 }
 340 EXPORT_SYMBOL(dma_pool_alloc);
 341
 342 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
 343 {
 344         struct dma_page *page;
 345
 346         list_for_each_entry(page, &pool->page_list, page_list) {
 347                 if (dma < page->dma)
 348                         continue;
 349                 if (dma < (page->dma + pool->allocation))
 350                         return page;
 351         }
 352         return NULL;
 353 }
 354
 355 /**
 356  * dma_pool_free - put block back into dma pool
 357  * @pool: the dma pool holding the block
 358  * @vaddr: virtual address of block
 359  * @dma: dma address of block
 360  *
 361  * Caller promises neither device nor driver will again touch this block
 362  * unless it is first re-allocated.
 363  */
 364 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 365 {
 366         struct dma_page *page;
 367         unsigned long flags;
 368         unsigned int offset;
 369
 370         spin_lock_irqsave(&pool->lock, flags);
 371         page = pool_find_page(pool, dma);
 372         if (!page) {
 373                 spin_unlock_irqrestore(&pool->lock, flags);
 374                 if (pool->dev)
 375                         dev_err(pool->dev,
 376                                 "dma_pool_free %s, %p/%lx (bad dma)\n",
 377                                 pool->name, vaddr, (unsigned long)dma);
 378                 else
 379                         printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
 380                                pool->name, vaddr, (unsigned long)dma);
 381                 return;
 382         }
 383
 384         offset = vaddr - page->vaddr;
 385 #ifdef  DMAPOOL_DEBUG
 386         if ((dma - page->dma) != offset) {
 387                 spin_unlock_irqrestore(&pool->lock, flags);
 388                 if (pool->dev)
 389                         dev_err(pool->dev,
 390                                 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 391                                 pool->name, vaddr, (unsigned long long)dma);
 392                 else
 393                         printk(KERN_ERR
 394                                "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 395                                pool->name, vaddr, (unsigned long long)dma);
 396                 return;
 397         }
 398         {
 399                 unsigned int chain = page->offset;
 400                 while (chain < pool->allocation) {
 401                         if (chain != offset) {
 402                                 chain = *(int *)(page->vaddr + chain);
 403                                 continue;
 404                         }
 405                         spin_unlock_irqrestore(&pool->lock, flags);
 406                         if (pool->dev)
 407                                 dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
 408                                         "already free\n", pool->name,
 409                                         (unsigned long long)dma);
 410                         else
 411                                 printk(KERN_ERR "dma_pool_free %s, dma %Lx "
 412                                         "already free\n", pool->name,
 413                                         (unsigned long long)dma);
 414                         return;
 415                 }
 416         }
 417         memset(vaddr, POOL_POISON_FREED, pool->size);
 418 #endif
 419
 420         page->in_use--;
 421         *(int *)vaddr = page->offset;
 422         page->offset = offset;
 423         /*
 424          * Resist a temptation to do
 425          *    if (!is_page_busy(page)) pool_free_page(pool, page);
 426          * Better have a few empty pages hang around.
 427          */
 428         spin_unlock_irqrestore(&pool->lock, flags);
 429 }
 430 EXPORT_SYMBOL(dma_pool_free);
 431
 432 /*
 433  * Managed DMA pool
 434  */
 435 static void dmam_pool_release(struct device *dev, void *res)
 436 {
 437         struct dma_pool *pool = *(struct dma_pool **)res;
 438
 439         dma_pool_destroy(pool);
 440 }
 441
 442 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
 443 {
 444         return *(struct dma_pool **)res == match_data;
 445 }
 446
 447 /**
 448  * dmam_pool_create - Managed dma_pool_create()
 449  * @name: name of pool, for diagnostics
 450  * @dev: device that will be doing the DMA
 451  * @size: size of the blocks in this pool.
 452  * @align: alignment requirement for blocks; must be a power of two
 453  * @allocation: returned blocks won't cross this boundary (or zero)
 454  *
 455  * Managed dma_pool_create().  DMA pool created with this function is
 456  * automatically destroyed on driver detach.
 457  */
 458 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
 459                                   size_t size, size_t align, size_t allocation)
 460 {
 461         struct dma_pool **ptr, *pool;
 462
 463         ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
 464         if (!ptr)
 465                 return NULL;
 466
 467         pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
 468         if (pool)
 469                 devres_add(dev, ptr);
 470         else
 471                 devres_free(ptr);
 472
 473         return pool;
 474 }
 475 EXPORT_SYMBOL(dmam_pool_create);
 476
 477 /**
 478  * dmam_pool_destroy - Managed dma_pool_destroy()
 479  * @pool: dma pool that will be destroyed
 480  *
 481  * Managed dma_pool_destroy().
 482  */
 483 void dmam_pool_destroy(struct dma_pool *pool)
 484 {
 485         struct device *dev = pool->dev;
 486
 487         WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
 488         dma_pool_destroy(pool);
 489 }
 490 EXPORT_SYMBOL(dmam_pool_destroy);