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
  11 /*
  12  * Pool allocator ... wraps the dma_alloc_coherent page allocator, so
  13  * small blocks are easily used by drivers for bus mastering controllers.
  14  * This should probably be sharing the guts of the slab allocator.
  15  */
  16
  17 struct dma_pool {       /* the pool */
  18         struct list_head        page_list;
  19         spinlock_t              lock;
  20         size_t                  blocks_per_page;
  21         size_t                  size;
  22         struct device           *dev;
  23         size_t                  allocation;
  24         char                    name [32];
  25         wait_queue_head_t       waitq;
  26         struct list_head        pools;
  27 };
  28
  29 struct dma_page {       /* cacheable header for 'allocation' bytes */
  30         struct list_head        page_list;
  31         void                    *vaddr;
  32         dma_addr_t              dma;
  33         unsigned                in_use;
  34         unsigned long           bitmap [0];
  35 };
  36
  37 #define POOL_TIMEOUT_JIFFIES    ((100 /* msec */ * HZ) / 1000)
  38 #define POOL_POISON_FREED       0xa7    /* !inuse */
  39 #define POOL_POISON_ALLOCATED   0xa9    /* !initted */
  40
  41 static DECLARE_MUTEX (pools_lock);
  42
  43 static ssize_t
  44 show_pools (struct device *dev, struct device_attribute *attr, char *buf)
  45 {
  46         unsigned temp;
  47         unsigned size;
  48         char *next;
  49         struct dma_page *page;
  50         struct dma_pool *pool;
  51
  52         next = buf;
  53         size = PAGE_SIZE;
  54
  55         temp = scnprintf(next, size, "poolinfo - 0.1\n");
  56         size -= temp;
  57         next += temp;
  58
  59         down (&pools_lock);
  60         list_for_each_entry(pool, &dev->dma_pools, pools) {
  61                 unsigned pages = 0;
  62                 unsigned blocks = 0;
  63
  64                 list_for_each_entry(page, &pool->page_list, page_list) {
  65                         pages++;
  66                         blocks += page->in_use;
  67                 }
  68
  69                 /* per-pool info, no real statistics yet */
  70                 temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
  71                                 pool->name,
  72                                 blocks, pages * pool->blocks_per_page,
  73                                 pool->size, pages);
  74                 size -= temp;
  75                 next += temp;
  76         }
  77         up (&pools_lock);
  78
  79         return PAGE_SIZE - size;
  80 }
  81 static DEVICE_ATTR (pools, S_IRUGO, show_pools, NULL);
  82
  83 /**
  84  * dma_pool_create - Creates a pool of consistent memory blocks, for dma.
  85  * @name: name of pool, for diagnostics
  86  * @dev: device that will be doing the DMA
  87  * @size: size of the blocks in this pool.
  88  * @align: alignment requirement for blocks; must be a power of two
  89  * @allocation: returned blocks won't cross this boundary (or zero)
  90  * Context: !in_interrupt()
  91  *
  92  * Returns a dma allocation pool with the requested characteristics, or
  93  * null if one can't be created.  Given one of these pools, dma_pool_alloc()
  94  * may be used to allocate memory.  Such memory will all have "consistent"
  95  * DMA mappings, accessible by the device and its driver without using
  96  * cache flushing primitives.  The actual size of blocks allocated may be
  97  * larger than requested because of alignment.
  98  *
  99  * If allocation is nonzero, objects returned from dma_pool_alloc() won't
 100  * cross that size boundary.  This is useful for devices which have
 101  * addressing restrictions on individual DMA transfers, such as not crossing
 102  * boundaries of 4KBytes.
 103  */
 104 struct dma_pool *
 105 dma_pool_create (const char *name, struct device *dev,
 106         size_t size, size_t align, size_t allocation)
 107 {
 108         struct dma_pool         *retval;
 109
 110         if (align == 0)
 111                 align = 1;
 112         if (size == 0)
 113                 return NULL;
 114         else if (size < align)
 115                 size = align;
 116         else if ((size % align) != 0) {
 117                 size += align + 1;
 118                 size &= ~(align - 1);
 119         }
 120
 121         if (allocation == 0) {
 122                 if (PAGE_SIZE < size)
 123                         allocation = size;
 124                 else
 125                         allocation = PAGE_SIZE;
 126                 // FIXME: round up for less fragmentation
 127         } else if (allocation < size)
 128                 return NULL;
 129
 130         if (!(retval = kmalloc (sizeof *retval, SLAB_KERNEL)))
 131                 return retval;
 132
 133         strlcpy (retval->name, name, sizeof retval->name);
 134
 135         retval->dev = dev;
 136
 137         INIT_LIST_HEAD (&retval->page_list);
 138         spin_lock_init (&retval->lock);
 139         retval->size = size;
 140         retval->allocation = allocation;
 141         retval->blocks_per_page = allocation / size;
 142         init_waitqueue_head (&retval->waitq);
 143
 144         if (dev) {
 145                 down (&pools_lock);
 146                 if (list_empty (&dev->dma_pools))
 147                         device_create_file (dev, &dev_attr_pools);
 148                 /* note:  not currently insisting "name" be unique */
 149                 list_add (&retval->pools, &dev->dma_pools);
 150                 up (&pools_lock);
 151         } else
 152                 INIT_LIST_HEAD (&retval->pools);
 153
 154         return retval;
 155 }
 156
 157
 158 static struct dma_page *
 159 pool_alloc_page (struct dma_pool *pool, gfp_t mem_flags)
 160 {
 161         struct dma_page *page;
 162         int             mapsize;
 163
 164         mapsize = pool->blocks_per_page;
 165         mapsize = (mapsize + BITS_PER_LONG - 1) / BITS_PER_LONG;
 166         mapsize *= sizeof (long);
 167
 168         page = (struct dma_page *) kmalloc (mapsize + sizeof *page, mem_flags);
 169         if (!page)
 170                 return NULL;
 171         page->vaddr = dma_alloc_coherent (pool->dev,
 172                                             pool->allocation,
 173                                             &page->dma,
 174                                             mem_flags);
 175         if (page->vaddr) {
 176                 memset (page->bitmap, 0xff, mapsize);   // bit set == free
 177 #ifdef  CONFIG_DEBUG_SLAB
 178                 memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
 179 #endif
 180                 list_add (&page->page_list, &pool->page_list);
 181                 page->in_use = 0;
 182         } else {
 183                 kfree (page);
 184                 page = NULL;
 185         }
 186         return page;
 187 }
 188
 189
 190 static inline int
 191 is_page_busy (int blocks, unsigned long *bitmap)
 192 {
 193         while (blocks > 0) {
 194                 if (*bitmap++ != ~0UL)
 195                         return 1;
 196                 blocks -= BITS_PER_LONG;
 197         }
 198         return 0;
 199 }
 200
 201 static void
 202 pool_free_page (struct dma_pool *pool, struct dma_page *page)
 203 {
 204         dma_addr_t      dma = page->dma;
 205
 206 #ifdef  CONFIG_DEBUG_SLAB
 207         memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
 208 #endif
 209         dma_free_coherent (pool->dev, pool->allocation, page->vaddr, dma);
 210         list_del (&page->page_list);
 211         kfree (page);
 212 }
 213
 214
 215 /**
 216  * dma_pool_destroy - destroys a pool of dma memory blocks.
 217  * @pool: dma pool that will be destroyed
 218  * Context: !in_interrupt()
 219  *
 220  * Caller guarantees that no more memory from the pool is in use,
 221  * and that nothing will try to use the pool after this call.
 222  */
 223 void
 224 dma_pool_destroy (struct dma_pool *pool)
 225 {
 226         down (&pools_lock);
 227         list_del (&pool->pools);
 228         if (pool->dev && list_empty (&pool->dev->dma_pools))
 229                 device_remove_file (pool->dev, &dev_attr_pools);
 230         up (&pools_lock);
 231
 232         while (!list_empty (&pool->page_list)) {
 233                 struct dma_page         *page;
 234                 page = list_entry (pool->page_list.next,
 235                                 struct dma_page, page_list);
 236                 if (is_page_busy (pool->blocks_per_page, page->bitmap)) {
 237                         if (pool->dev)
 238                                 dev_err(pool->dev, "dma_pool_destroy %s, %p busy\n",
 239                                         pool->name, page->vaddr);
 240                         else
 241                                 printk (KERN_ERR "dma_pool_destroy %s, %p busy\n",
 242                                         pool->name, page->vaddr);
 243                         /* leak the still-in-use consistent memory */
 244                         list_del (&page->page_list);
 245                         kfree (page);
 246                 } else
 247                         pool_free_page (pool, page);
 248         }
 249
 250         kfree (pool);
 251 }
 252
 253
 254 /**
 255  * dma_pool_alloc - get a block of consistent memory
 256  * @pool: dma pool that will produce the block
 257  * @mem_flags: GFP_* bitmask
 258  * @handle: pointer to dma address of block
 259  *
 260  * This returns the kernel virtual address of a currently unused block,
 261  * and reports its dma address through the handle.
 262  * If such a memory block can't be allocated, null is returned.
 263  */
 264 void *
 265 dma_pool_alloc (struct dma_pool *pool, gfp_t mem_flags, dma_addr_t *handle)
 266 {
 267         unsigned long           flags;
 268         struct dma_page         *page;
 269         int                     map, block;
 270         size_t                  offset;
 271         void                    *retval;
 272
 273 restart:
 274         spin_lock_irqsave (&pool->lock, flags);
 275         list_for_each_entry(page, &pool->page_list, page_list) {
 276                 int             i;
 277                 /* only cachable accesses here ... */
 278                 for (map = 0, i = 0;
 279                                 i < pool->blocks_per_page;
 280                                 i += BITS_PER_LONG, map++) {
 281                         if (page->bitmap [map] == 0)
 282                                 continue;
 283                         block = ffz (~ page->bitmap [map]);
 284                         if ((i + block) < pool->blocks_per_page) {
 285                                 clear_bit (block, &page->bitmap [map]);
 286                                 offset = (BITS_PER_LONG * map) + block;
 287                                 offset *= pool->size;
 288                                 goto ready;
 289                         }
 290                 }
 291         }
 292         if (!(page = pool_alloc_page (pool, SLAB_ATOMIC))) {
 293                 if (mem_flags & __GFP_WAIT) {
 294                         DECLARE_WAITQUEUE (wait, current);
 295
 296                         current->state = TASK_INTERRUPTIBLE;
 297                         add_wait_queue (&pool->waitq, &wait);
 298                         spin_unlock_irqrestore (&pool->lock, flags);
 299
 300                         schedule_timeout (POOL_TIMEOUT_JIFFIES);
 301
 302                         remove_wait_queue (&pool->waitq, &wait);
 303                         goto restart;
 304                 }
 305                 retval = NULL;
 306                 goto done;
 307         }
 308
 309         clear_bit (0, &page->bitmap [0]);
 310         offset = 0;
 311 ready:
 312         page->in_use++;
 313         retval = offset + page->vaddr;
 314         *handle = offset + page->dma;
 315 #ifdef  CONFIG_DEBUG_SLAB
 316         memset (retval, POOL_POISON_ALLOCATED, pool->size);
 317 #endif
 318 done:
 319         spin_unlock_irqrestore (&pool->lock, flags);
 320         return retval;
 321 }
 322
 323
 324 static struct dma_page *
 325 pool_find_page (struct dma_pool *pool, dma_addr_t dma)
 326 {
 327         unsigned long           flags;
 328         struct dma_page         *page;
 329
 330         spin_lock_irqsave (&pool->lock, flags);
 331         list_for_each_entry(page, &pool->page_list, page_list) {
 332                 if (dma < page->dma)
 333                         continue;
 334                 if (dma < (page->dma + pool->allocation))
 335                         goto done;
 336         }
 337         page = NULL;
 338 done:
 339         spin_unlock_irqrestore (&pool->lock, flags);
 340         return page;
 341 }
 342
 343
 344 /**
 345  * dma_pool_free - put block back into dma pool
 346  * @pool: the dma pool holding the block
 347  * @vaddr: virtual address of block
 348  * @dma: dma address of block
 349  *
 350  * Caller promises neither device nor driver will again touch this block
 351  * unless it is first re-allocated.
 352  */
 353 void
 354 dma_pool_free (struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 355 {
 356         struct dma_page         *page;
 357         unsigned long           flags;
 358         int                     map, block;
 359
 360         if ((page = pool_find_page (pool, dma)) == 0) {
 361                 if (pool->dev)
 362                         dev_err(pool->dev, "dma_pool_free %s, %p/%lx (bad dma)\n",
 363                                 pool->name, vaddr, (unsigned long) dma);
 364                 else
 365                         printk (KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
 366                                 pool->name, vaddr, (unsigned long) dma);
 367                 return;
 368         }
 369
 370         block = dma - page->dma;
 371         block /= pool->size;
 372         map = block / BITS_PER_LONG;
 373         block %= BITS_PER_LONG;
 374
 375 #ifdef  CONFIG_DEBUG_SLAB
 376         if (((dma - page->dma) + (void *)page->vaddr) != vaddr) {
 377                 if (pool->dev)
 378                         dev_err(pool->dev, "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 379                                 pool->name, vaddr, (unsigned long long) dma);
 380                 else
 381                         printk (KERN_ERR "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 382                                 pool->name, vaddr, (unsigned long long) dma);
 383                 return;
 384         }
 385         if (page->bitmap [map] & (1UL << block)) {
 386                 if (pool->dev)
 387                         dev_err(pool->dev, "dma_pool_free %s, dma %Lx already free\n",
 388                                 pool->name, (unsigned long long)dma);
 389                 else
 390                         printk (KERN_ERR "dma_pool_free %s, dma %Lx already free\n",
 391                                 pool->name, (unsigned long long)dma);
 392                 return;
 393         }
 394         memset (vaddr, POOL_POISON_FREED, pool->size);
 395 #endif
 396
 397         spin_lock_irqsave (&pool->lock, flags);
 398         page->in_use--;
 399         set_bit (block, &page->bitmap [map]);
 400         if (waitqueue_active (&pool->waitq))
 401                 wake_up (&pool->waitq);
 402         /*
 403          * Resist a temptation to do
 404          *    if (!is_page_busy(bpp, page->bitmap)) pool_free_page(pool, page);
 405          * Better have a few empty pages hang around.
 406          */
 407         spin_unlock_irqrestore (&pool->lock, flags);
 408 }
 409
 410
 411 EXPORT_SYMBOL (dma_pool_create);
 412 EXPORT_SYMBOL (dma_pool_destroy);
 413 EXPORT_SYMBOL (dma_pool_alloc);
 414 EXPORT_SYMBOL (dma_pool_free);