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         wait_queue_head_t waitq;
  54         struct list_head pools;
  55 };
  56
  57 struct dma_page {               /* cacheable header for 'allocation' bytes */
  58         struct list_head page_list;
  59         void *vaddr;
  60         dma_addr_t dma;
  61         unsigned int in_use;
  62         unsigned int offset;
  63 };
  64
  65 #define POOL_TIMEOUT_JIFFIES    ((100 /* msec */ * HZ) / 1000)
  66
  67 static DEFINE_MUTEX(pools_lock);
  68
  69 static ssize_t
  70 show_pools(struct device *dev, struct device_attribute *attr, char *buf)
  71 {
  72         unsigned temp;
  73         unsigned size;
  74         char *next;
  75         struct dma_page *page;
  76         struct dma_pool *pool;
  77
  78         next = buf;
  79         size = PAGE_SIZE;
  80
  81         temp = scnprintf(next, size, "poolinfo - 0.1\n");
  82         size -= temp;
  83         next += temp;
  84
  85         mutex_lock(&pools_lock);
  86         list_for_each_entry(pool, &dev->dma_pools, pools) {
  87                 unsigned pages = 0;
  88                 unsigned blocks = 0;
  89
  90                 spin_lock_irq(&pool->lock);
  91                 list_for_each_entry(page, &pool->page_list, page_list) {
  92                         pages++;
  93                         blocks += page->in_use;
  94                 }
  95                 spin_unlock_irq(&pool->lock);
  96
  97                 /* per-pool info, no real statistics yet */
  98                 temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
  99                                  pool->name, blocks,
 100                                  pages * (pool->allocation / pool->size),
 101                                  pool->size, pages);
 102                 size -= temp;
 103                 next += temp;
 104         }
 105         mutex_unlock(&pools_lock);
 106
 107         return PAGE_SIZE - size;
 108 }
 109
 110 static DEVICE_ATTR(pools, S_IRUGO, show_pools, NULL);
 111
 112 /**
 113  * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
 114  * @name: name of pool, for diagnostics
 115  * @dev: device that will be doing the DMA
 116  * @size: size of the blocks in this pool.
 117  * @align: alignment requirement for blocks; must be a power of two
 118  * @boundary: returned blocks won't cross this power of two boundary
 119  * Context: !in_interrupt()
 120  *
 121  * Returns a dma allocation pool with the requested characteristics, or
 122  * null if one can't be created.  Given one of these pools, dma_pool_alloc()
 123  * may be used to allocate memory.  Such memory will all have "consistent"
 124  * DMA mappings, accessible by the device and its driver without using
 125  * cache flushing primitives.  The actual size of blocks allocated may be
 126  * larger than requested because of alignment.
 127  *
 128  * If @boundary is nonzero, objects returned from dma_pool_alloc() won't
 129  * cross that size boundary.  This is useful for devices which have
 130  * addressing restrictions on individual DMA transfers, such as not crossing
 131  * boundaries of 4KBytes.
 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
 139         if (align == 0) {
 140                 align = 1;
 141         } else if (align & (align - 1)) {
 142                 return NULL;
 143         }
 144
 145         if (size == 0) {
 146                 return NULL;
 147         } else if (size < 4) {
 148                 size = 4;
 149         }
 150
 151         if ((size % align) != 0)
 152                 size = ALIGN(size, align);
 153
 154         allocation = max_t(size_t, size, PAGE_SIZE);
 155
 156         if (!boundary) {
 157                 boundary = allocation;
 158         } else if ((boundary < size) || (boundary & (boundary - 1))) {
 159                 return NULL;
 160         }
 161
 162         retval = kmalloc_node(sizeof(*retval), GFP_KERNEL, dev_to_node(dev));
 163         if (!retval)
 164                 return retval;
 165
 166         strlcpy(retval->name, name, sizeof(retval->name));
 167
 168         retval->dev = dev;
 169
 170         INIT_LIST_HEAD(&retval->page_list);
 171         spin_lock_init(&retval->lock);
 172         retval->size = size;
 173         retval->boundary = boundary;
 174         retval->allocation = allocation;
 175         init_waitqueue_head(&retval->waitq);
 176
 177         if (dev) {
 178                 int ret;
 179
 180                 mutex_lock(&pools_lock);
 181                 if (list_empty(&dev->dma_pools))
 182                         ret = device_create_file(dev, &dev_attr_pools);
 183                 else
 184                         ret = 0;
 185                 /* note:  not currently insisting "name" be unique */
 186                 if (!ret)
 187                         list_add(&retval->pools, &dev->dma_pools);
 188                 else {
 189                         kfree(retval);
 190                         retval = NULL;
 191                 }
 192                 mutex_unlock(&pools_lock);
 193         } else
 194                 INIT_LIST_HEAD(&retval->pools);
 195
 196         return retval;
 197 }
 198 EXPORT_SYMBOL(dma_pool_create);
 199
 200 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
 201 {
 202         unsigned int offset = 0;
 203         unsigned int next_boundary = pool->boundary;
 204
 205         do {
 206                 unsigned int next = offset + pool->size;
 207                 if (unlikely((next + pool->size) >= next_boundary)) {
 208                         next = next_boundary;
 209                         next_boundary += pool->boundary;
 210                 }
 211                 *(int *)(page->vaddr + offset) = next;
 212                 offset = next;
 213         } while (offset < pool->allocation);
 214 }
 215
 216 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
 217 {
 218         struct dma_page *page;
 219
 220         page = kmalloc(sizeof(*page), mem_flags);
 221         if (!page)
 222                 return NULL;
 223         page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
 224                                          &page->dma, mem_flags);
 225         if (page->vaddr) {
 226 #ifdef  DMAPOOL_DEBUG
 227                 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 228 #endif
 229                 pool_initialise_page(pool, page);
 230                 list_add(&page->page_list, &pool->page_list);
 231                 page->in_use = 0;
 232                 page->offset = 0;
 233         } else {
 234                 kfree(page);
 235                 page = NULL;
 236         }
 237         return page;
 238 }
 239
 240 static inline int is_page_busy(struct dma_page *page)
 241 {
 242         return page->in_use != 0;
 243 }
 244
 245 static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
 246 {
 247         dma_addr_t dma = page->dma;
 248
 249 #ifdef  DMAPOOL_DEBUG
 250         memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 251 #endif
 252         dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
 253         list_del(&page->page_list);
 254         kfree(page);
 255 }
 256
 257 /**
 258  * dma_pool_destroy - destroys a pool of dma memory blocks.
 259  * @pool: dma pool that will be destroyed
 260  * Context: !in_interrupt()
 261  *
 262  * Caller guarantees that no more memory from the pool is in use,
 263  * and that nothing will try to use the pool after this call.
 264  */
 265 void dma_pool_destroy(struct dma_pool *pool)
 266 {
 267         mutex_lock(&pools_lock);
 268         list_del(&pool->pools);
 269         if (pool->dev && list_empty(&pool->dev->dma_pools))
 270                 device_remove_file(pool->dev, &dev_attr_pools);
 271         mutex_unlock(&pools_lock);
 272
 273         while (!list_empty(&pool->page_list)) {
 274                 struct dma_page *page;
 275                 page = list_entry(pool->page_list.next,
 276                                   struct dma_page, page_list);
 277                 if (is_page_busy(page)) {
 278                         if (pool->dev)
 279                                 dev_err(pool->dev,
 280                                         "dma_pool_destroy %s, %p busy\n",
 281                                         pool->name, page->vaddr);
 282                         else
 283                                 printk(KERN_ERR
 284                                        "dma_pool_destroy %s, %p busy\n",
 285                                        pool->name, page->vaddr);
 286                         /* leak the still-in-use consistent memory */
 287                         list_del(&page->page_list);
 288                         kfree(page);
 289                 } else
 290                         pool_free_page(pool, page);
 291         }
 292
 293         kfree(pool);
 294 }
 295 EXPORT_SYMBOL(dma_pool_destroy);
 296
 297 /**
 298  * dma_pool_alloc - get a block of consistent memory
 299  * @pool: dma pool that will produce the block
 300  * @mem_flags: GFP_* bitmask
 301  * @handle: pointer to dma address of block
 302  *
 303  * This returns the kernel virtual address of a currently unused block,
 304  * and reports its dma address through the handle.
 305  * If such a memory block can't be allocated, %NULL is returned.
 306  */
 307 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
 308                      dma_addr_t *handle)
 309 {
 310         unsigned long flags;
 311         struct dma_page *page;
 312         size_t offset;
 313         void *retval;
 314
 315         might_sleep_if(mem_flags & __GFP_WAIT);
 316
 317         spin_lock_irqsave(&pool->lock, flags);
 318  restart:
 319         list_for_each_entry(page, &pool->page_list, page_list) {
 320                 if (page->offset < pool->allocation)
 321                         goto ready;
 322         }
 323         page = pool_alloc_page(pool, GFP_ATOMIC);
 324         if (!page) {
 325                 if (mem_flags & __GFP_WAIT) {
 326                         DECLARE_WAITQUEUE(wait, current);
 327
 328                         __set_current_state(TASK_UNINTERRUPTIBLE);
 329                         __add_wait_queue(&pool->waitq, &wait);
 330                         spin_unlock_irqrestore(&pool->lock, flags);
 331
 332                         schedule_timeout(POOL_TIMEOUT_JIFFIES);
 333
 334                         spin_lock_irqsave(&pool->lock, flags);
 335                         __remove_wait_queue(&pool->waitq, &wait);
 336                         goto restart;
 337                 }
 338                 retval = NULL;
 339                 goto done;
 340         }
 341
 342  ready:
 343         page->in_use++;
 344         offset = page->offset;
 345         page->offset = *(int *)(page->vaddr + offset);
 346         retval = offset + page->vaddr;
 347         *handle = offset + page->dma;
 348 #ifdef  DMAPOOL_DEBUG
 349         memset(retval, POOL_POISON_ALLOCATED, pool->size);
 350 #endif
 351  done:
 352         spin_unlock_irqrestore(&pool->lock, flags);
 353         return retval;
 354 }
 355 EXPORT_SYMBOL(dma_pool_alloc);
 356
 357 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
 358 {
 359         struct dma_page *page;
 360
 361         list_for_each_entry(page, &pool->page_list, page_list) {
 362                 if (dma < page->dma)
 363                         continue;
 364                 if (dma < (page->dma + pool->allocation))
 365                         return page;
 366         }
 367         return NULL;
 368 }
 369
 370 /**
 371  * dma_pool_free - put block back into dma pool
 372  * @pool: the dma pool holding the block
 373  * @vaddr: virtual address of block
 374  * @dma: dma address of block
 375  *
 376  * Caller promises neither device nor driver will again touch this block
 377  * unless it is first re-allocated.
 378  */
 379 void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 380 {
 381         struct dma_page *page;
 382         unsigned long flags;
 383         unsigned int offset;
 384
 385         spin_lock_irqsave(&pool->lock, flags);
 386         page = pool_find_page(pool, dma);
 387         if (!page) {
 388                 spin_unlock_irqrestore(&pool->lock, flags);
 389                 if (pool->dev)
 390                         dev_err(pool->dev,
 391                                 "dma_pool_free %s, %p/%lx (bad dma)\n",
 392                                 pool->name, vaddr, (unsigned long)dma);
 393                 else
 394                         printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
 395                                pool->name, vaddr, (unsigned long)dma);
 396                 return;
 397         }
 398
 399         offset = vaddr - page->vaddr;
 400 #ifdef  DMAPOOL_DEBUG
 401         if ((dma - page->dma) != offset) {
 402                 spin_unlock_irqrestore(&pool->lock, flags);
 403                 if (pool->dev)
 404                         dev_err(pool->dev,
 405                                 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 406                                 pool->name, vaddr, (unsigned long long)dma);
 407                 else
 408                         printk(KERN_ERR
 409                                "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 410                                pool->name, vaddr, (unsigned long long)dma);
 411                 return;
 412         }
 413         {
 414                 unsigned int chain = page->offset;
 415                 while (chain < pool->allocation) {
 416                         if (chain != offset) {
 417                                 chain = *(int *)(page->vaddr + chain);
 418                                 continue;
 419                         }
 420                         spin_unlock_irqrestore(&pool->lock, flags);
 421                         if (pool->dev)
 422                                 dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
 423                                         "already free\n", pool->name,
 424                                         (unsigned long long)dma);
 425                         else
 426                                 printk(KERN_ERR "dma_pool_free %s, dma %Lx "
 427                                         "already free\n", pool->name,
 428                                         (unsigned long long)dma);
 429                         return;
 430                 }
 431         }
 432         memset(vaddr, POOL_POISON_FREED, pool->size);
 433 #endif
 434
 435         page->in_use--;
 436         *(int *)vaddr = page->offset;
 437         page->offset = offset;
 438         if (waitqueue_active(&pool->waitq))
 439                 wake_up_locked(&pool->waitq);
 440         /*
 441          * Resist a temptation to do
 442          *    if (!is_page_busy(page)) pool_free_page(pool, page);
 443          * Better have a few empty pages hang around.
 444          */
 445         spin_unlock_irqrestore(&pool->lock, flags);
 446 }
 447 EXPORT_SYMBOL(dma_pool_free);
 448
 449 /*
 450  * Managed DMA pool
 451  */
 452 static void dmam_pool_release(struct device *dev, void *res)
 453 {
 454         struct dma_pool *pool = *(struct dma_pool **)res;
 455
 456         dma_pool_destroy(pool);
 457 }
 458
 459 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
 460 {
 461         return *(struct dma_pool **)res == match_data;
 462 }
 463
 464 /**
 465  * dmam_pool_create - Managed dma_pool_create()
 466  * @name: name of pool, for diagnostics
 467  * @dev: device that will be doing the DMA
 468  * @size: size of the blocks in this pool.
 469  * @align: alignment requirement for blocks; must be a power of two
 470  * @allocation: returned blocks won't cross this boundary (or zero)
 471  *
 472  * Managed dma_pool_create().  DMA pool created with this function is
 473  * automatically destroyed on driver detach.
 474  */
 475 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
 476                                   size_t size, size_t align, size_t allocation)
 477 {
 478         struct dma_pool **ptr, *pool;
 479
 480         ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
 481         if (!ptr)
 482                 return NULL;
 483
 484         pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
 485         if (pool)
 486                 devres_add(dev, ptr);
 487         else
 488                 devres_free(ptr);
 489
 490         return pool;
 491 }
 492 EXPORT_SYMBOL(dmam_pool_create);
 493
 494 /**
 495  * dmam_pool_destroy - Managed dma_pool_destroy()
 496  * @pool: dma pool that will be destroyed
 497  *
 498  * Managed dma_pool_destroy().
 499  */
 500 void dmam_pool_destroy(struct dma_pool *pool)
 501 {
 502         struct device *dev = pool->dev;
 503
 504         WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
 505         dma_pool_destroy(pool);
 506 }
 507 EXPORT_SYMBOL(dmam_pool_destroy);