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/module.h>
  31 #include <linux/mutex.h>
  32 #include <linux/poison.h>
  33 #include <linux/sched.h>
  34 #include <linux/slab.h>
  35 #include <linux/spinlock.h>
  36 #include <linux/string.h>
  37 #include <linux/types.h>
  38 #include <linux/wait.h>
  39
  40 #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
  41 #define DMAPOOL_DEBUG 1
  42 #endif
  43
  44 struct dma_pool {               /* the pool */
  45         struct list_head page_list;
  46         spinlock_t lock;
  47         size_t size;
  48         struct device *dev;
  49         size_t allocation;
  50         size_t boundary;
  51         char name[32];
  52         wait_queue_head_t waitq;
  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 #define POOL_TIMEOUT_JIFFIES    ((100 /* msec */ * HZ) / 1000)
  65
  66 static DEFINE_MUTEX(pools_lock);
  67
  68 static ssize_t
  69 show_pools(struct device *dev, struct device_attribute *attr, char *buf)
  70 {
  71         unsigned temp;
  72         unsigned size;
  73         char *next;
  74         struct dma_page *page;
  75         struct dma_pool *pool;
  76
  77         next = buf;
  78         size = PAGE_SIZE;
  79
  80         temp = scnprintf(next, size, "poolinfo - 0.1\n");
  81         size -= temp;
  82         next += temp;
  83
  84         mutex_lock(&pools_lock);
  85         list_for_each_entry(pool, &dev->dma_pools, pools) {
  86                 unsigned pages = 0;
  87                 unsigned blocks = 0;
  88
  89                 list_for_each_entry(page, &pool->page_list, page_list) {
  90                         pages++;
  91                         blocks += page->in_use;
  92                 }
  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         init_waitqueue_head(&retval->waitq);
 173
 174         if (dev) {
 175                 int ret;
 176
 177                 mutex_lock(&pools_lock);
 178                 if (list_empty(&dev->dma_pools))
 179                         ret = device_create_file(dev, &dev_attr_pools);
 180                 else
 181                         ret = 0;
 182                 /* note:  not currently insisting "name" be unique */
 183                 if (!ret)
 184                         list_add(&retval->pools, &dev->dma_pools);
 185                 else {
 186                         kfree(retval);
 187                         retval = NULL;
 188                 }
 189                 mutex_unlock(&pools_lock);
 190         } else
 191                 INIT_LIST_HEAD(&retval->pools);
 192
 193         return retval;
 194 }
 195 EXPORT_SYMBOL(dma_pool_create);
 196
 197 static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page)
 198 {
 199         unsigned int offset = 0;
 200         unsigned int next_boundary = pool->boundary;
 201
 202         do {
 203                 unsigned int next = offset + pool->size;
 204                 if (unlikely((next + pool->size) >= next_boundary)) {
 205                         next = next_boundary;
 206                         next_boundary += pool->boundary;
 207                 }
 208                 *(int *)(page->vaddr + offset) = next;
 209                 offset = next;
 210         } while (offset < pool->allocation);
 211 }
 212
 213 static struct dma_page *pool_alloc_page(struct dma_pool *pool, gfp_t mem_flags)
 214 {
 215         struct dma_page *page;
 216
 217         page = kmalloc(sizeof(*page), mem_flags);
 218         if (!page)
 219                 return NULL;
 220         page->vaddr = dma_alloc_coherent(pool->dev, pool->allocation,
 221                                          &page->dma, mem_flags);
 222         if (page->vaddr) {
 223 #ifdef  DMAPOOL_DEBUG
 224                 memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 225 #endif
 226                 pool_initialise_page(pool, page);
 227                 list_add(&page->page_list, &pool->page_list);
 228                 page->in_use = 0;
 229                 page->offset = 0;
 230         } else {
 231                 kfree(page);
 232                 page = NULL;
 233         }
 234         return page;
 235 }
 236
 237 static inline int is_page_busy(struct dma_page *page)
 238 {
 239         return page->in_use != 0;
 240 }
 241
 242 static void pool_free_page(struct dma_pool *pool, struct dma_page *page)
 243 {
 244         dma_addr_t dma = page->dma;
 245
 246 #ifdef  DMAPOOL_DEBUG
 247         memset(page->vaddr, POOL_POISON_FREED, pool->allocation);
 248 #endif
 249         dma_free_coherent(pool->dev, pool->allocation, page->vaddr, dma);
 250         list_del(&page->page_list);
 251         kfree(page);
 252 }
 253
 254 /**
 255  * dma_pool_destroy - destroys a pool of dma memory blocks.
 256  * @pool: dma pool that will be destroyed
 257  * Context: !in_interrupt()
 258  *
 259  * Caller guarantees that no more memory from the pool is in use,
 260  * and that nothing will try to use the pool after this call.
 261  */
 262 void dma_pool_destroy(struct dma_pool *pool)
 263 {
 264         mutex_lock(&pools_lock);
 265         list_del(&pool->pools);
 266         if (pool->dev && list_empty(&pool->dev->dma_pools))
 267                 device_remove_file(pool->dev, &dev_attr_pools);
 268         mutex_unlock(&pools_lock);
 269
 270         while (!list_empty(&pool->page_list)) {
 271                 struct dma_page *page;
 272                 page = list_entry(pool->page_list.next,
 273                                   struct dma_page, page_list);
 274                 if (is_page_busy(page)) {
 275                         if (pool->dev)
 276                                 dev_err(pool->dev,
 277                                         "dma_pool_destroy %s, %p busy\n",
 278                                         pool->name, page->vaddr);
 279                         else
 280                                 printk(KERN_ERR
 281                                        "dma_pool_destroy %s, %p busy\n",
 282                                        pool->name, page->vaddr);
 283                         /* leak the still-in-use consistent memory */
 284                         list_del(&page->page_list);
 285                         kfree(page);
 286                 } else
 287                         pool_free_page(pool, page);
 288         }
 289
 290         kfree(pool);
 291 }
 292 EXPORT_SYMBOL(dma_pool_destroy);
 293
 294 /**
 295  * dma_pool_alloc - get a block of consistent memory
 296  * @pool: dma pool that will produce the block
 297  * @mem_flags: GFP_* bitmask
 298  * @handle: pointer to dma address of block
 299  *
 300  * This returns the kernel virtual address of a currently unused block,
 301  * and reports its dma address through the handle.
 302  * If such a memory block can't be allocated, %NULL is returned.
 303  */
 304 void *dma_pool_alloc(struct dma_pool *pool, gfp_t mem_flags,
 305                      dma_addr_t *handle)
 306 {
 307         unsigned long flags;
 308         struct dma_page *page;
 309         size_t offset;
 310         void *retval;
 311
 312         spin_lock_irqsave(&pool->lock, flags);
 313  restart:
 314         list_for_each_entry(page, &pool->page_list, page_list) {
 315                 if (page->offset < pool->allocation)
 316                         goto ready;
 317         }
 318         page = pool_alloc_page(pool, GFP_ATOMIC);
 319         if (!page) {
 320                 if (mem_flags & __GFP_WAIT) {
 321                         DECLARE_WAITQUEUE(wait, current);
 322
 323                         __set_current_state(TASK_INTERRUPTIBLE);
 324                         __add_wait_queue(&pool->waitq, &wait);
 325                         spin_unlock_irqrestore(&pool->lock, flags);
 326
 327                         schedule_timeout(POOL_TIMEOUT_JIFFIES);
 328
 329                         spin_lock_irqsave(&pool->lock, flags);
 330                         __remove_wait_queue(&pool->waitq, &wait);
 331                         goto restart;
 332                 }
 333                 retval = NULL;
 334                 goto done;
 335         }
 336
 337  ready:
 338         page->in_use++;
 339         offset = page->offset;
 340         page->offset = *(int *)(page->vaddr + offset);
 341         retval = offset + page->vaddr;
 342         *handle = offset + page->dma;
 343 #ifdef  DMAPOOL_DEBUG
 344         memset(retval, POOL_POISON_ALLOCATED, pool->size);
 345 #endif
 346  done:
 347         spin_unlock_irqrestore(&pool->lock, flags);
 348         return retval;
 349 }
 350 EXPORT_SYMBOL(dma_pool_alloc);
 351
 352 static struct dma_page *pool_find_page(struct dma_pool *pool, dma_addr_t dma)
 353 {
 354         unsigned long flags;
 355         struct dma_page *page;
 356
 357         spin_lock_irqsave(&pool->lock, flags);
 358         list_for_each_entry(page, &pool->page_list, page_list) {
 359                 if (dma < page->dma)
 360                         continue;
 361                 if (dma < (page->dma + pool->allocation))
 362                         goto done;
 363         }
 364         page = NULL;
 365  done:
 366         spin_unlock_irqrestore(&pool->lock, flags);
 367         return page;
 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         page = pool_find_page(pool, dma);
 386         if (!page) {
 387                 if (pool->dev)
 388                         dev_err(pool->dev,
 389                                 "dma_pool_free %s, %p/%lx (bad dma)\n",
 390                                 pool->name, vaddr, (unsigned long)dma);
 391                 else
 392                         printk(KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
 393                                pool->name, vaddr, (unsigned long)dma);
 394                 return;
 395         }
 396
 397         offset = vaddr - page->vaddr;
 398 #ifdef  DMAPOOL_DEBUG
 399         if ((dma - page->dma) != offset) {
 400                 if (pool->dev)
 401                         dev_err(pool->dev,
 402                                 "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 403                                 pool->name, vaddr, (unsigned long long)dma);
 404                 else
 405                         printk(KERN_ERR
 406                                "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 407                                pool->name, vaddr, (unsigned long long)dma);
 408                 return;
 409         }
 410         {
 411                 unsigned int chain = page->offset;
 412                 while (chain < pool->allocation) {
 413                         if (chain != offset) {
 414                                 chain = *(int *)(page->vaddr + chain);
 415                                 continue;
 416                         }
 417                         if (pool->dev)
 418                                 dev_err(pool->dev, "dma_pool_free %s, dma %Lx "
 419                                         "already free\n", pool->name,
 420                                         (unsigned long long)dma);
 421                         else
 422                                 printk(KERN_ERR "dma_pool_free %s, dma %Lx "
 423                                         "already free\n", pool->name,
 424                                         (unsigned long long)dma);
 425                         return;
 426                 }
 427         }
 428         memset(vaddr, POOL_POISON_FREED, pool->size);
 429 #endif
 430
 431         spin_lock_irqsave(&pool->lock, flags);
 432         page->in_use--;
 433         *(int *)vaddr = page->offset;
 434         page->offset = offset;
 435         if (waitqueue_active(&pool->waitq))
 436                 wake_up_locked(&pool->waitq);
 437         /*
 438          * Resist a temptation to do
 439          *    if (!is_page_busy(page)) pool_free_page(pool, page);
 440          * Better have a few empty pages hang around.
 441          */
 442         spin_unlock_irqrestore(&pool->lock, flags);
 443 }
 444 EXPORT_SYMBOL(dma_pool_free);
 445
 446 /*
 447  * Managed DMA pool
 448  */
 449 static void dmam_pool_release(struct device *dev, void *res)
 450 {
 451         struct dma_pool *pool = *(struct dma_pool **)res;
 452
 453         dma_pool_destroy(pool);
 454 }
 455
 456 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
 457 {
 458         return *(struct dma_pool **)res == match_data;
 459 }
 460
 461 /**
 462  * dmam_pool_create - Managed dma_pool_create()
 463  * @name: name of pool, for diagnostics
 464  * @dev: device that will be doing the DMA
 465  * @size: size of the blocks in this pool.
 466  * @align: alignment requirement for blocks; must be a power of two
 467  * @allocation: returned blocks won't cross this boundary (or zero)
 468  *
 469  * Managed dma_pool_create().  DMA pool created with this function is
 470  * automatically destroyed on driver detach.
 471  */
 472 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
 473                                   size_t size, size_t align, size_t allocation)
 474 {
 475         struct dma_pool **ptr, *pool;
 476
 477         ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
 478         if (!ptr)
 479                 return NULL;
 480
 481         pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
 482         if (pool)
 483                 devres_add(dev, ptr);
 484         else
 485                 devres_free(ptr);
 486
 487         return pool;
 488 }
 489 EXPORT_SYMBOL(dmam_pool_create);
 490
 491 /**
 492  * dmam_pool_destroy - Managed dma_pool_destroy()
 493  * @pool: dma pool that will be destroyed
 494  *
 495  * Managed dma_pool_destroy().
 496  */
 497 void dmam_pool_destroy(struct dma_pool *pool)
 498 {
 499         struct device *dev = pool->dev;
 500
 501         dma_pool_destroy(pool);
 502         WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
 503 }
 504 EXPORT_SYMBOL(dmam_pool_destroy);