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 static DEFINE_MUTEX(pools_reg_lock);
  66
  67 static ssize_t
  68 show_pools(struct device *dev, struct device_attribute *attr, char *buf)
  69 {
  70         unsigned temp;
  71         unsigned size;
  72         char *next;
  73         struct dma_page *page;
  74         struct dma_pool *pool;
  75
  76         next = buf;
  77         size = PAGE_SIZE;
  78
  79         temp = scnprintf(next, size, "poolinfo - 0.1\n");
  80         size -= temp;
  81         next += temp;
  82
  83         mutex_lock(&pools_lock);
  84         list_for_each_entry(pool, &dev->dma_pools, pools) {
  85                 unsigned pages = 0;
  86                 unsigned blocks = 0;
  87
  88                 spin_lock_irq(&pool->lock);
  89                 list_for_each_entry(page, &pool->page_list, page_list) {
  90                         pages++;
  91                         blocks += page->in_use;
  92                 }
  93                 spin_unlock_irq(&pool->lock);
  94
  95                 /* per-pool info, no real statistics yet */
  96                 temp = scnprintf(next, size, "%-16s %4u %4zu %4zu %2u\n",
  97                                  pool->name, blocks,
  98                                  pages * (pool->allocation / pool->size),
  99                                  pool->size, pages);
 100                 size -= temp;
 101                 next += temp;
 102         }
 103         mutex_unlock(&pools_lock);
 104
 105         return PAGE_SIZE - size;
 106 }
 107
 108 static DEVICE_ATTR(pools, 0444, show_pools, NULL);
 109
 110 /**
 111  * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
 112  * @name: name of pool, for diagnostics
 113  * @dev: device that will be doing the DMA
 114  * @size: size of the blocks in this pool.
 115  * @align: alignment requirement for blocks; must be a power of two
 116  * @boundary: returned blocks won't cross this power of two boundary
 117  * Context: not in_interrupt()
 118  *
 119  * 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  * Return: a dma allocation pool with the requested characteristics, or
 131  * %NULL if one can't be created.
 132  */
 133 struct dma_pool *dma_pool_create(const char *name, struct device *dev,
 134                                  size_t size, size_t align, size_t boundary)
 135 {
 136         struct dma_pool *retval;
 137         size_t allocation;
 138         bool empty = false;
 139
 140         if (align == 0)
 141                 align = 1;
 142         else if (align & (align - 1))
 143                 return NULL;
 144
 145         if (size == 0)
 146                 return NULL;
 147         else if (size < 4)
 148                 size = 4;
 149
 150         if ((size % align) != 0)
 151                 size = ALIGN(size, align);
 152
 153         allocation = max_t(size_t, size, PAGE_SIZE);
 154
 155         if (!boundary)
 156                 boundary = allocation;
 157         else if ((boundary < size) || (boundary & (boundary - 1)))
 158                 return NULL;
 159
 160         retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
 161         if (!retval)
 162                 return retval;
 163
 164         strlcpy(retval->name, name, sizeof(retval->name));
 165
 166         retval->dev = dev;
 167
 168         INIT_LIST_HEAD(&retval->page_list);
 169         spin_lock_init(&retval->lock);
 170         retval->size = size;
 171         retval->boundary = boundary;
 172         retval->allocation = allocation;
 173
 174         INIT_LIST_HEAD(&retval->pools);
 175
 176         /*
 177          * pools_lock ensures that the ->dma_pools list does not get corrupted.
 178          * pools_reg_lock ensures that there is not a race between
 179          * dma_pool_create() and dma_pool_destroy() or within dma_pool_create()
 180          * when the first invocation of dma_pool_create() failed on
 181          * device_create_file() and the second assumes that it has been done (I
 182          * know it is a short window).
 183          */
 184         mutex_lock(&pools_reg_lock);
 185         mutex_lock(&pools_lock);
 186         if (list_empty(&dev->dma_pools))
 187                 empty = true;
 188         list_add(&retval->pools, &dev->dma_pools);
 189         mutex_unlock(&pools_lock);
 190         if (empty) {
 191                 int err;
 192
 193                 err = device_create_file(dev, &dev_attr_pools);
 194                 if (err) {
 195                         mutex_lock(&pools_lock);
 196                         list_del(&retval->pools);
 197                         mutex_unlock(&pools_lock);
 198                         mutex_unlock(&pools_reg_lock);
 199                         kfree(retval);
 200                         return NULL;
 201                 }
 202         }
 203         mutex_unlock(&pools_reg_lock);
 204         return retval;
 205 }
 206 EXPORT_SYMBOL(dma_pool_create);
 207
 208 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
 209 {
 210         unsigned int offset = 0;
 211         unsigned int next_boundary = pool->boundary;
 212
 213         do {
 214                 unsigned int next = offset + pool->size;
 215                 if (unlikely((next + pool->size) >= next_boundary)) {
 216                         next = next_boundary;
 217                         next_boundary += pool->boundary;
 218                 }
 219                 *(int *)(page->vaddr + offset) = next;
 220                 offset = next;
 221         } while (offset < pool->allocation);
 222 }
 223
 224 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
 225 {
 226         struct dma_page *page;
 227
 228         page = kmalloc(sizeof(*page), mem_flags);
 229         if (!page)
 230                 return NULL;
 231         page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
 232                                          &page->dma, mem_flags);
 233         if (page->vaddr) {
 234 #ifdef  DMAPOOL_DEBUG
 235                 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 236 #endif
 237                 pool_initialise_page(pool, page);
 238                 page->in_use = 0;
 239                 page->offset = 0;
 240         } else {
 241                 kfree(page);
 242                 page = NULL;
 243         }
 244         return page;
 245 }
 246
 247 static inline bool is_page_busy(struct dma_page *page)
 248 {
 249         return page->in_use != 0;
 250 }
 251
 252 static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
 253 {
 254         dma_addr_t dma = page->dma;
 255
 256 #ifdef  DMAPOOL_DEBUG
 257         memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 258 #endif
 259         dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
 260         list_del(&page->page_list);
 261         kfree(page);
 262 }
 263
 264 /**
 265  * dma_pool_destroy - destroys a pool of dma memory blocks.
 266  * @pool: dma pool that will be destroyed
 267  * Context: !in_interrupt()
 268  *
 269  * Caller guarantees that no more memory from the pool is in use,
 270  * and that nothing will try to use the pool after this call.
 271  */
 272 void dma_pool_destroy(struct dma_pool *pool)
 273 {
 274         bool empty = false;
 275
 276         if (unlikely(!pool))
 277                 return;
 278
 279         mutex_lock(&pools_reg_lock);
 280         mutex_lock(&pools_lock);
 281         list_del(&pool->pools);
 282         if (pool->dev && list_empty(&pool->dev->dma_pools))
 283                 empty = true;
 284         mutex_unlock(&pools_lock);
 285         if (empty)
 286                 device_remove_file(pool->dev, &dev_attr_pools);
 287         mutex_unlock(&pools_reg_lock);
 288
 289         while (!list_empty(&pool->page_list)) {
 290                 struct dma_page *page;
 291                 page = list_entry(pool->page_list.next,
 292                                   struct dma_page, page_list);
 293                 if (is_page_busy(page)) {
 294                         if (pool->dev)
 295                                 dev_err(pool->dev,
 296                                         "dma_pool_destroy %s, %p busy\n",
 297                                         pool->name, page->vaddr);
 298                         else
 299                                 pr_err("dma_pool_destroy %s, %p busy\n",
 300                                        pool->name, page->vaddr);
 301                         /* leak the still-in-use consistent memory */
 302                         list_del(&page->page_list);
 303                         kfree(page);
 304                 } else
 305                         pool_free_page(pool, page);
 306         }
 307
 308         kfree(pool);
 309 }
 310 EXPORT_SYMBOL(dma_pool_destroy);
 311
 312 /**
 313  * dma_pool_alloc - get a block of consistent memory
 314  * @pool: dma pool that will produce the block
 315  * @mem_flags: GFP_* bitmask
 316  * @handle: pointer to dma address of block
 317  *
 318  * Return: the kernel virtual address of a currently unused block,
 319  * and reports its dma address through the handle.
 320  * If such a memory block can't be allocated, %NULL is returned.
 321  */
 322 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
 323                      dma_addr_t *handle)
 324 {
 325         unsigned long flags;
 326         struct dma_page *page;
 327         size_t offset;
 328         void *retval;
 329
 330         might_sleep_if(gfpflags_allow_blocking(mem_flags));
 331
 332         spin_lock_irqsave(&pool->lock, flags);
 333         list_for_each_entry(page, &pool->page_list, page_list) {
 334                 if (page->offset < pool->allocation)
 335                         goto ready;
 336         }
 337
 338         /* pool_alloc_page() might sleep, so temporarily drop &pool->lock */
 339         spin_unlock_irqrestore(&pool->lock, flags);
 340
 341         page = pool_alloc_page(pool, mem_flags & (~__GFP_ZERO));
 342         if (!page)
 343                 return NULL;
 344
 345         spin_lock_irqsave(&pool->lock, flags);
 346
 347         list_add(&page->page_list, &pool->page_list);
 348  ready:
 349         page->in_use++;
 350         offset = page->offset;
 351         page->offset = *(int *)(page->vaddr + offset);
 352         retval = offset + page->vaddr;
 353         *handle = offset + page->dma;
 354 #ifdef  DMAPOOL_DEBUG
 355         {
 356                 int i;
 357                 u8 *data = retval;
 358                 /* page->offset is stored in first 4 bytes */
 359                 for (i = sizeof(page->offset); i < pool->size; i++) {
 360                         if (data[i] == POOL_POISON_FREED)
 361                                 continue;
 362                         if (pool->dev)
 363                                 dev_err(pool->dev,
 364                                         "dma_pool_alloc %s, %p (corrupted)\n",
 365                                         pool->name, retval);
 366                         else
 367                                 pr_err("dma_pool_alloc %s, %p (corrupted)\n",
 368                                         pool->name, retval);
 369
 370                         /*
 371                          * Dump the first 4 bytes even if they are not
 372                          * POOL_POISON_FREED
 373                          */
 374                         print_hex_dump(KERN_ERR, "", DUMP_PREFIX_OFFSET, 16, 1,
 375                                         data, pool->size, 1);
 376                         break;
 377                 }
 378         }
 379         if (!(mem_flags & __GFP_ZERO))
 380                 memset(retval, POOL_POISON_ALLOCATED, pool->size);
 381 #endif
 382         spin_unlock_irqrestore(&pool->lock, flags);
 383
 384         if (mem_flags & __GFP_ZERO)
 385                 memset(retval, 0, pool->size);
 386
 387         return retval;
 388 }
 389 EXPORT_SYMBOL(dma_pool_alloc);
 390
 391 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
 392 {
 393         struct dma_page *page;
 394
 395         list_for_each_entry(page, &pool->page_list, page_list) {
 396                 if (dma < page->dma)
 397                         continue;
 398                 if ((dma - page->dma) < pool->allocation)
 399                         return page;
 400         }
 401         return NULL;
 402 }
 403
 404 /**
 405  * dma_pool_free - put block back into dma pool
 406  * @pool: the dma pool holding the block
 407  * @vaddr: virtual address of block
 408  * @dma: dma address of block
 409  *
 410  * Caller promises neither device nor driver will again touch this block
 411  * unless it is first re-allocated.
 412  */
 413 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 414 {
 415         struct dma_page *page;
 416         unsigned long flags;
 417         unsigned int offset;
 418
 419         spin_lock_irqsave(&pool->lock, flags);
 420         page = pool_find_page(pool, dma);
 421         if (!page) {
 422                 spin_unlock_irqrestore(&pool->lock, flags);
 423                 if (pool->dev)
 424                         dev_err(pool->dev,
 425                                 "dma_pool_free %s, %p/%lx (bad dma)\n",
 426                                 pool->name, vaddr, (unsigned long)dma);
 427                 else
 428                         pr_err("dma_pool_free %s, %p/%lx (bad dma)\n",
 429                                pool->name, vaddr, (unsigned long)dma);
 430                 return;
 431         }
 432
 433         offset = vaddr - page->vaddr;
 434 #ifdef  DMAPOOL_DEBUG
 435         if ((dma - page->dma) != offset) {
 436                 spin_unlock_irqrestore(&pool->lock, flags);
 437                 if (pool->dev)
 438                         dev_err(pool->dev,
 439                                 "dma_pool_free %s, %p (bad vaddr)/%pad\n",
 440                                 pool->name, vaddr, &dma);
 441                 else
 442                         pr_err("dma_pool_free %s, %p (bad vaddr)/%pad\n",
 443                                pool->name, vaddr, &dma);
 444                 return;
 445         }
 446         {
 447                 unsigned int chain = page->offset;
 448                 while (chain < pool->allocation) {
 449                         if (chain != offset) {
 450                                 chain = *(int *)(page->vaddr + chain);
 451                                 continue;
 452                         }
 453                         spin_unlock_irqrestore(&pool->lock, flags);
 454                         if (pool->dev)
 455                                 dev_err(pool->dev, "dma_pool_free %s, dma %pad already free\n",
 456                                         pool->name, &dma);
 457                         else
 458                                 pr_err("dma_pool_free %s, dma %pad already free\n",
 459                                        pool->name, &dma);
 460                         return;
 461                 }
 462         }
 463         memset(vaddr, POOL_POISON_FREED, pool->size);
 464 #endif
 465
 466         page->in_use--;
 467         *(int *)vaddr = page->offset;
 468         page->offset = offset;
 469         /*
 470          * Resist a temptation to do
 471          *    if (!is_page_busy(page)) pool_free_page(pool, page);
 472          * Better have a few empty pages hang around.
 473          */
 474         spin_unlock_irqrestore(&pool->lock, flags);
 475 }
 476 EXPORT_SYMBOL(dma_pool_free);
 477
 478 /*
 479  * Managed DMA pool
 480  */
 481 static void dmam_pool_release(struct device *dev, void *res)
 482 {
 483         struct dma_pool *pool = *(struct dma_pool **)res;
 484
 485         dma_pool_destroy(pool);
 486 }
 487
 488 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
 489 {
 490         return *(struct dma_pool **)res == match_data;
 491 }
 492
 493 /**
 494  * dmam_pool_create - Managed dma_pool_create()
 495  * @name: name of pool, for diagnostics
 496  * @dev: device that will be doing the DMA
 497  * @size: size of the blocks in this pool.
 498  * @align: alignment requirement for blocks; must be a power of two
 499  * @allocation: returned blocks won't cross this boundary (or zero)
 500  *
 501  * Managed dma_pool_create().  DMA pool created with this function is
 502  * automatically destroyed on driver detach.
 503  *
 504  * Return: a managed dma allocation pool with the requested
 505  * characteristics, or %NULL if one can't be created.
 506  */
 507 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
 508                                   size_t size, size_t align, size_t allocation)
 509 {
 510         struct dma_pool **ptr, *pool;
 511
 512         ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
 513         if (!ptr)
 514                 return NULL;
 515
 516         pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
 517         if (pool)
 518                 devres_add(dev, ptr);
 519         else
 520                 devres_free(ptr);
 521
 522         return pool;
 523 }
 524 EXPORT_SYMBOL(dmam_pool_create);
 525
 526 /**
 527  * dmam_pool_destroy - Managed dma_pool_destroy()
 528  * @pool: dma pool that will be destroyed
 529  *
 530  * Managed dma_pool_destroy().
 531  */
 532 void dmam_pool_destroy(struct dma_pool *pool)
 533 {
 534         struct device *dev = pool->dev;
 535
 536         WARN_ON(devres_release(dev, dmam_pool_release, dmam_pool_match, pool));
 537 }
 538 EXPORT_SYMBOL(dmam_pool_destroy);