drivers/base/dmapool.c

   1
   2 #include <linux/device.h>
   3 #include <linux/mm.h>
   4 #include <asm/io.h>             /* Needed for i386 to build */
   5 #include <asm/scatterlist.h>    /* Needed for i386 to build */
   6 #include <linux/dma-mapping.h>
   7 #include <linux/dmapool.h>
   8 #include <linux/slab.h>
   9 #include <linux/module.h>
  10 #include <linux/poison.h>
  11
  12 /*
  13  * Pool allocator ... wraps the dma_alloc_coherent page allocator, so
  14  * small blocks are easily used by drivers for bus mastering controllers.
  15  * This should probably be sharing the guts of the slab allocator.
  16  */
  17
  18 struct dma_pool {       /* the pool */
  19         struct list_head        page_list;
  20         spinlock_t              lock;
  21         size_t                  blocks_per_page;
  22         size_t                  size;
  23         struct device           *dev;
  24         size_t                  allocation;
  25         char                    name [32];
  26         wait_queue_head_t       waitq;
  27         struct list_head        pools;
  28 };
  29
  30 struct dma_page {       /* cacheable header for 'allocation' bytes */
  31         struct list_head        page_list;
  32         void                    *vaddr;
  33         dma_addr_t              dma;
  34         unsigned                in_use;
  35         unsigned long           bitmap [0];
  36 };
  37
  38 #define POOL_TIMEOUT_JIFFIES    ((100 /* msec */ * HZ) / 1000)
  39
  40 static DECLARE_MUTEX (pools_lock);
  41
  42 static ssize_t
  43 show_pools (struct device *dev, struct device_attribute *attr, char *buf)
  44 {
  45         unsigned temp;
  46         unsigned size;
  47         char *next;
  48         struct dma_page *page;
  49         struct dma_pool *pool;
  50
  51         next = buf;
  52         size = PAGE_SIZE;
  53
  54         temp = scnprintf(next, size, "poolinfo - 0.1\n");
  55         size -= temp;
  56         next += temp;
  57
  58         down (&pools_lock);
  59         list_for_each_entry(pool, &dev->dma_pools, pools) {
  60                 unsigned pages = 0;
  61                 unsigned blocks = 0;
  62
  63                 list_for_each_entry(page, &pool->page_list, page_list) {
  64                         pages++;
  65                         blocks += page->in_use;
  66                 }
  67
  68                 /* per-pool info, no real statistics yet */
  69                 temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
  70                                 pool->name,
  71                                 blocks, pages * pool->blocks_per_page,
  72                                 pool->size, pages);
  73                 size -= temp;
  74                 next += temp;
  75         }
  76         up (&pools_lock);
  77
  78         return PAGE_SIZE - size;
  79 }
  80 static DEVICE_ATTR (pools, S_IRUGO, show_pools, NULL);
  81
  82 /**
  83  * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
  84  * @name: name of pool, for diagnostics
  85  * @dev: device that will be doing the DMA
  86  * @size: size of the blocks in this pool.
  87  * @align: alignment requirement for blocks; must be a power of two
  88  * @allocation: returned blocks won't cross this boundary (or zero)
  89  * Context: !in_interrupt()
  90  *
  91  * Returns a dma allocation pool with the requested characteristics, or
  92  * null if one can't be created.  Given one of these pools, dma_pool_alloc()
  93  * may be used to allocate memory.  Such memory will all have "consistent"
  94  * DMA mappings, accessible by the device and its driver without using
  95  * cache flushing primitives.  The actual size of blocks allocated may be
  96  * larger than requested because of alignment.
  97  *
  98  * If allocation is nonzero, objects returned from dma_pool_alloc() won't
  99  * cross that size boundary.  This is useful for devices which have
 100  * addressing restrictions on individual DMA transfers, such as not crossing
 101  * boundaries of 4KBytes.
 102  */
 103 struct dma_pool *
 104 dma_pool_create (const char *name, struct device *dev,
 105         size_t size, size_t align, size_t allocation)
 106 {
 107         struct dma_pool         *retval;
 108
 109         if (align == 0)
 110                 align = 1;
 111         if (size == 0)
 112                 return NULL;
 113         else if (size < align)
 114                 size = align;
 115         else if ((size % align) != 0) {
 116                 size += align + 1;
 117                 size &= ~(align - 1);
 118         }
 119
 120         if (allocation == 0) {
 121                 if (PAGE_SIZE < size)
 122                         allocation = size;
 123                 else
 124                         allocation = PAGE_SIZE;
 125                 // FIXME: round up for less fragmentation
 126         } else if (allocation < size)
 127                 return NULL;
 128
 129         if (!(retval = kmalloc (sizeof *retval, GFP_KERNEL)))
 130                 return retval;
 131
 132         strlcpy (retval->name, name, sizeof retval->name);
 133
 134         retval->dev = dev;
 135
 136         INIT_LIST_HEAD (&retval->page_list);
 137         spin_lock_init (&retval->lock);
 138         retval->size = size;
 139         retval->allocation = allocation;
 140         retval->blocks_per_page = allocation / size;
 141         init_waitqueue_head (&retval->waitq);
 142
 143         if (dev) {
 144                 int ret;
 145
 146                 down (&pools_lock);
 147                 if (list_empty (&dev->dma_pools))
 148                         ret = device_create_file (dev, &dev_attr_pools);
 149                 else
 150                         ret = 0;
 151                 /* note:  not currently insisting "name" be unique */
 152                 if (!ret)
 153                         list_add (&retval->pools, &dev->dma_pools);
 154                 else {
 155                         kfree(retval);
 156                         retval = NULL;
 157                 }
 158                 up (&pools_lock);
 159         } else
 160                 INIT_LIST_HEAD (&retval->pools);
 161
 162         return retval;
 163 }
 164
 165
 166 static struct dma_page *
 167 pool_alloc_page (struct dma_pool *pool, gfp_t mem_flags)
 168 {
 169         struct dma_page *page;
 170         int             mapsize;
 171
 172         mapsize = pool->blocks_per_page;
 173         mapsize = (mapsize + BITS_PER_LONG - 1) / BITS_PER_LONG;
 174         mapsize *= sizeof (long);
 175
 176         page = kmalloc(mapsize + sizeof *page, mem_flags);
 177         if (!page)
 178                 return NULL;
 179         page->vaddr = dma_alloc_coherent (pool->dev,
 180                                             pool->allocation,
 181                                             &page->dma,
 182                                             mem_flags);
 183         if (page->vaddr) {
 184                 memset (page->bitmap, 0xff, mapsize);   // bit set == free
 185 #ifdef  CONFIG_DEBUG_SLAB
 186                 memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
 187 #endif
 188                 list_add (&page->page_list, &pool->page_list);
 189                 page->in_use = 0;
 190         } else {
 191                 kfree (page);
 192                 page = NULL;
 193         }
 194         return page;
 195 }
 196
 197
 198 static inline int
 199 is_page_busy (int blocks, unsigned long *bitmap)
 200 {
 201         while (blocks > 0) {
 202                 if (*bitmap++ != ~0UL)
 203                         return 1;
 204                 blocks -= BITS_PER_LONG;
 205         }
 206         return 0;
 207 }
 208
 209 static void
 210 pool_free_page (struct dma_pool *pool, struct dma_page *page)
 211 {
 212         dma_addr_t      dma = page->dma;
 213
 214 #ifdef  CONFIG_DEBUG_SLAB
 215         memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
 216 #endif
 217         dma_free_coherent (pool->dev, pool->allocation, page->vaddr, dma);
 218         list_del (&page->page_list);
 219         kfree (page);
 220 }
 221
 222
 223 /**
 224  * dma_pool_destroy - destroys a pool of dma memory blocks.
 225  * @pool: dma pool that will be destroyed
 226  * Context: !in_interrupt()
 227  *
 228  * Caller guarantees that no more memory from the pool is in use,
 229  * and that nothing will try to use the pool after this call.
 230  */
 231 void
 232 dma_pool_destroy (struct dma_pool *pool)
 233 {
 234         down (&pools_lock);
 235         list_del (&pool->pools);
 236         if (pool->dev && list_empty (&pool->dev->dma_pools))
 237                 device_remove_file (pool->dev, &dev_attr_pools);
 238         up (&pools_lock);
 239
 240         while (!list_empty (&pool->page_list)) {
 241                 struct dma_page         *page;
 242                 page = list_entry (pool->page_list.next,
 243                                 struct dma_page, page_list);
 244                 if (is_page_busy (pool->blocks_per_page, page->bitmap)) {
 245                         if (pool->dev)
 246                                 dev_err(pool->dev, "dma_pool_destroy %s, %p busy\n",
 247                                         pool->name, page->vaddr);
 248                         else
 249                                 printk (KERN_ERR "dma_pool_destroy %s, %p busy\n",
 250                                         pool->name, page->vaddr);
 251                         /* leak the still-in-use consistent memory */
 252                         list_del (&page->page_list);
 253                         kfree (page);
 254                 } else
 255                         pool_free_page (pool, page);
 256         }
 257
 258         kfree (pool);
 259 }
 260
 261
 262 /**
 263  * dma_pool_alloc - get a block of consistent memory
 264  * @pool: dma pool that will produce the block
 265  * @mem_flags: GFP_* bitmask
 266  * @handle: pointer to dma address of block
 267  *
 268  * This returns the kernel virtual address of a currently unused block,
 269  * and reports its dma address through the handle.
 270  * If such a memory block can't be allocated, null is returned.
 271  */
 272 void *
 273 dma_pool_alloc (struct dma_pool *pool, gfp_t mem_flags, dma_addr_t *handle)
 274 {
 275         unsigned long           flags;
 276         struct dma_page         *page;
 277         int                     map, block;
 278         size_t                  offset;
 279         void                    *retval;
 280
 281 restart:
 282         spin_lock_irqsave (&pool->lock, flags);
 283         list_for_each_entry(page, &pool->page_list, page_list) {
 284                 int             i;
 285                 /* only cachable accesses here ... */
 286                 for (map = 0, i = 0;
 287                                 i < pool->blocks_per_page;
 288                                 i += BITS_PER_LONG, map++) {
 289                         if (page->bitmap [map] == 0)
 290                                 continue;
 291                         block = ffz (~ page->bitmap [map]);
 292                         if ((i + block) < pool->blocks_per_page) {
 293                                 clear_bit (block, &page->bitmap [map]);
 294                                 offset = (BITS_PER_LONG * map) + block;
 295                                 offset *= pool->size;
 296                                 goto ready;
 297                         }
 298                 }
 299         }
 300         if (!(page = pool_alloc_page (pool, GFP_ATOMIC))) {
 301                 if (mem_flags & __GFP_WAIT) {
 302                         DECLARE_WAITQUEUE (wait, current);
 303
 304                         current->state = TASK_INTERRUPTIBLE;
 305                         add_wait_queue (&pool->waitq, &wait);
 306                         spin_unlock_irqrestore (&pool->lock, flags);
 307
 308                         schedule_timeout (POOL_TIMEOUT_JIFFIES);
 309
 310                         remove_wait_queue (&pool->waitq, &wait);
 311                         goto restart;
 312                 }
 313                 retval = NULL;
 314                 goto done;
 315         }
 316
 317         clear_bit (0, &page->bitmap [0]);
 318         offset = 0;
 319 ready:
 320         page->in_use++;
 321         retval = offset + page->vaddr;
 322         *handle = offset + page->dma;
 323 #ifdef  CONFIG_DEBUG_SLAB
 324         memset (retval, POOL_POISON_ALLOCATED, pool->size);
 325 #endif
 326 done:
 327         spin_unlock_irqrestore (&pool->lock, flags);
 328         return retval;
 329 }
 330
 331
 332 static struct dma_page *
 333 pool_find_page (struct dma_pool *pool, dma_addr_t dma)
 334 {
 335         unsigned long           flags;
 336         struct dma_page         *page;
 337
 338         spin_lock_irqsave (&pool->lock, flags);
 339         list_for_each_entry(page, &pool->page_list, page_list) {
 340                 if (dma < page->dma)
 341                         continue;
 342                 if (dma < (page->dma + pool->allocation))
 343                         goto done;
 344         }
 345         page = NULL;
 346 done:
 347         spin_unlock_irqrestore (&pool->lock, flags);
 348         return page;
 349 }
 350
 351
 352 /**
 353  * dma_pool_free - put block back into dma pool
 354  * @pool: the dma pool holding the block
 355  * @vaddr: virtual address of block
 356  * @dma: dma address of block
 357  *
 358  * Caller promises neither device nor driver will again touch this block
 359  * unless it is first re-allocated.
 360  */
 361 void
 362 dma_pool_free (struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 363 {
 364         struct dma_page         *page;
 365         unsigned long           flags;
 366         int                     map, block;
 367
 368         if ((page = pool_find_page (pool, dma)) == 0) {
 369                 if (pool->dev)
 370                         dev_err(pool->dev, "dma_pool_free %s, %p/%lx (bad dma)\n",
 371                                 pool->name, vaddr, (unsigned long) dma);
 372                 else
 373                         printk (KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
 374                                 pool->name, vaddr, (unsigned long) dma);
 375                 return;
 376         }
 377
 378         block = dma - page->dma;
 379         block /= pool->size;
 380         map = block / BITS_PER_LONG;
 381         block %= BITS_PER_LONG;
 382
 383 #ifdef  CONFIG_DEBUG_SLAB
 384         if (((dma - page->dma) + (void *)page->vaddr) != vaddr) {
 385                 if (pool->dev)
 386                         dev_err(pool->dev, "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 387                                 pool->name, vaddr, (unsigned long long) dma);
 388                 else
 389                         printk (KERN_ERR "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 390                                 pool->name, vaddr, (unsigned long long) dma);
 391                 return;
 392         }
 393         if (page->bitmap [map] & (1UL << block)) {
 394                 if (pool->dev)
 395                         dev_err(pool->dev, "dma_pool_free %s, dma %Lx already free\n",
 396                                 pool->name, (unsigned long long)dma);
 397                 else
 398                         printk (KERN_ERR "dma_pool_free %s, dma %Lx already free\n",
 399                                 pool->name, (unsigned long long)dma);
 400                 return;
 401         }
 402         memset (vaddr, POOL_POISON_FREED, pool->size);
 403 #endif
 404
 405         spin_lock_irqsave (&pool->lock, flags);
 406         page->in_use--;
 407         set_bit (block, &page->bitmap [map]);
 408         if (waitqueue_active (&pool->waitq))
 409                 wake_up (&pool->waitq);
 410         /*
 411          * Resist a temptation to do
 412          *    if (!is_page_busy(bpp, page->bitmap)) pool_free_page(pool, page);
 413          * Better have a few empty pages hang around.
 414          */
 415         spin_unlock_irqrestore (&pool->lock, flags);
 416 }
 417
 418 /*
 419  * Managed DMA pool
 420  */
 421 static void dmam_pool_release(struct device *dev, void *res)
 422 {
 423         struct dma_pool *pool = *(struct dma_pool **)res;
 424
 425         dma_pool_destroy(pool);
 426 }
 427
 428 static int dmam_pool_match(struct device *dev, void *res, void *match_data)
 429 {
 430         return *(struct dma_pool **)res == match_data;
 431 }
 432
 433 /**
 434  * dmam_pool_create - Managed dma_pool_create()
 435  * @name: name of pool, for diagnostics
 436  * @dev: device that will be doing the DMA
 437  * @size: size of the blocks in this pool.
 438  * @align: alignment requirement for blocks; must be a power of two
 439  * @allocation: returned blocks won't cross this boundary (or zero)
 440  *
 441  * Managed dma_pool_create().  DMA pool created with this function is
 442  * automatically destroyed on driver detach.
 443  */
 444 struct dma_pool *dmam_pool_create(const char *name, struct device *dev,
 445                                   size_t size, size_t align, size_t allocation)
 446 {
 447         struct dma_pool **ptr, *pool;
 448
 449         ptr = devres_alloc(dmam_pool_release, sizeof(*ptr), GFP_KERNEL);
 450         if (!ptr)
 451                 return NULL;
 452
 453         pool = *ptr = dma_pool_create(name, dev, size, align, allocation);
 454         if (pool)
 455                 devres_add(dev, ptr);
 456         else
 457                 devres_free(ptr);
 458
 459         return pool;
 460 }
 461
 462 /**
 463  * dmam_pool_destroy - Managed dma_pool_destroy()
 464  * @pool: dma pool that will be destroyed
 465  *
 466  * Managed dma_pool_destroy().
 467  */
 468 void dmam_pool_destroy(struct dma_pool *pool)
 469 {
 470         struct device *dev = pool->dev;
 471
 472         dma_pool_destroy(pool);
 473         WARN_ON(devres_destroy(dev, dmam_pool_release, dmam_pool_match, pool));
 474 }
 475
 476 EXPORT_SYMBOL (dma_pool_create);
 477 EXPORT_SYMBOL (dma_pool_destroy);
 478 EXPORT_SYMBOL (dma_pool_alloc);
 479 EXPORT_SYMBOL (dma_pool_free);
 480 EXPORT_SYMBOL (dmam_pool_create);
 481 EXPORT_SYMBOL (dmam_pool_destroy);