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, SLAB_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                 down (&pools_lock);
 145                 if (list_empty (&dev->dma_pools))
 146                         device_create_file (dev, &dev_attr_pools);
 147                 /* note:  not currently insisting "name" be unique */
 148                 list_add (&retval->pools, &dev->dma_pools);
 149                 up (&pools_lock);
 150         } else
 151                 INIT_LIST_HEAD (&retval->pools);
 152
 153         return retval;
 154 }
 155
 156
 157 static struct dma_page *
 158 pool_alloc_page (struct dma_pool *pool, gfp_t mem_flags)
 159 {
 160         struct dma_page *page;
 161         int             mapsize;
 162
 163         mapsize = pool->blocks_per_page;
 164         mapsize = (mapsize + BITS_PER_LONG - 1) / BITS_PER_LONG;
 165         mapsize *= sizeof (long);
 166
 167         page = (struct dma_page *) kmalloc (mapsize + sizeof *page, mem_flags);
 168         if (!page)
 169                 return NULL;
 170         page->vaddr = dma_alloc_coherent (pool->dev,
 171                                             pool->allocation,
 172                                             &page->dma,
 173                                             mem_flags);
 174         if (page->vaddr) {
 175                 memset (page->bitmap, 0xff, mapsize);   // bit set == free
 176 #ifdef  CONFIG_DEBUG_SLAB
 177                 memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
 178 #endif
 179                 list_add (&page->page_list, &pool->page_list);
 180                 page->in_use = 0;
 181         } else {
 182                 kfree (page);
 183                 page = NULL;
 184         }
 185         return page;
 186 }
 187
 188
 189 static inline int
 190 is_page_busy (int blocks, unsigned long *bitmap)
 191 {
 192         while (blocks > 0) {
 193                 if (*bitmap++ != ~0UL)
 194                         return 1;
 195                 blocks -= BITS_PER_LONG;
 196         }
 197         return 0;
 198 }
 199
 200 static void
 201 pool_free_page (struct dma_pool *pool, struct dma_page *page)
 202 {
 203         dma_addr_t      dma = page->dma;
 204
 205 #ifdef  CONFIG_DEBUG_SLAB
 206         memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
 207 #endif
 208         dma_free_coherent (pool->dev, pool->allocation, page->vaddr, dma);
 209         list_del (&page->page_list);
 210         kfree (page);
 211 }
 212
 213
 214 /**
 215  * dma_pool_destroy - destroys a pool of dma memory blocks.
 216  * @pool: dma pool that will be destroyed
 217  * Context: !in_interrupt()
 218  *
 219  * Caller guarantees that no more memory from the pool is in use,
 220  * and that nothing will try to use the pool after this call.
 221  */
 222 void
 223 dma_pool_destroy (struct dma_pool *pool)
 224 {
 225         down (&pools_lock);
 226         list_del (&pool->pools);
 227         if (pool->dev && list_empty (&pool->dev->dma_pools))
 228                 device_remove_file (pool->dev, &dev_attr_pools);
 229         up (&pools_lock);
 230
 231         while (!list_empty (&pool->page_list)) {
 232                 struct dma_page         *page;
 233                 page = list_entry (pool->page_list.next,
 234                                 struct dma_page, page_list);
 235                 if (is_page_busy (pool->blocks_per_page, page->bitmap)) {
 236                         if (pool->dev)
 237                                 dev_err(pool->dev, "dma_pool_destroy %s, %p busy\n",
 238                                         pool->name, page->vaddr);
 239                         else
 240                                 printk (KERN_ERR "dma_pool_destroy %s, %p busy\n",
 241                                         pool->name, page->vaddr);
 242                         /* leak the still-in-use consistent memory */
 243                         list_del (&page->page_list);
 244                         kfree (page);
 245                 } else
 246                         pool_free_page (pool, page);
 247         }
 248
 249         kfree (pool);
 250 }
 251
 252
 253 /**
 254  * dma_pool_alloc - get a block of consistent memory
 255  * @pool: dma pool that will produce the block
 256  * @mem_flags: GFP_* bitmask
 257  * @handle: pointer to dma address of block
 258  *
 259  * This returns the kernel virtual address of a currently unused block,
 260  * and reports its dma address through the handle.
 261  * If such a memory block can't be allocated, null is returned.
 262  */
 263 void *
 264 dma_pool_alloc (struct dma_pool *pool, gfp_t mem_flags, dma_addr_t *handle)
 265 {
 266         unsigned long           flags;
 267         struct dma_page         *page;
 268         int                     map, block;
 269         size_t                  offset;
 270         void                    *retval;
 271
 272 restart:
 273         spin_lock_irqsave (&pool->lock, flags);
 274         list_for_each_entry(page, &pool->page_list, page_list) {
 275                 int             i;
 276                 /* only cachable accesses here ... */
 277                 for (map = 0, i = 0;
 278                                 i < pool->blocks_per_page;
 279                                 i += BITS_PER_LONG, map++) {
 280                         if (page->bitmap [map] == 0)
 281                                 continue;
 282                         block = ffz (~ page->bitmap [map]);
 283                         if ((i + block) < pool->blocks_per_page) {
 284                                 clear_bit (block, &page->bitmap [map]);
 285                                 offset = (BITS_PER_LONG * map) + block;
 286                                 offset *= pool->size;
 287                                 goto ready;
 288                         }
 289                 }
 290         }
 291         if (!(page = pool_alloc_page (pool, SLAB_ATOMIC))) {
 292                 if (mem_flags & __GFP_WAIT) {
 293                         DECLARE_WAITQUEUE (wait, current);
 294
 295                         current->state = TASK_INTERRUPTIBLE;
 296                         add_wait_queue (&pool->waitq, &wait);
 297                         spin_unlock_irqrestore (&pool->lock, flags);
 298
 299                         schedule_timeout (POOL_TIMEOUT_JIFFIES);
 300
 301                         remove_wait_queue (&pool->waitq, &wait);
 302                         goto restart;
 303                 }
 304                 retval = NULL;
 305                 goto done;
 306         }
 307
 308         clear_bit (0, &page->bitmap [0]);
 309         offset = 0;
 310 ready:
 311         page->in_use++;
 312         retval = offset + page->vaddr;
 313         *handle = offset + page->dma;
 314 #ifdef  CONFIG_DEBUG_SLAB
 315         memset (retval, POOL_POISON_ALLOCATED, pool->size);
 316 #endif
 317 done:
 318         spin_unlock_irqrestore (&pool->lock, flags);
 319         return retval;
 320 }
 321
 322
 323 static struct dma_page *
 324 pool_find_page (struct dma_pool *pool, dma_addr_t dma)
 325 {
 326         unsigned long           flags;
 327         struct dma_page         *page;
 328
 329         spin_lock_irqsave (&pool->lock, flags);
 330         list_for_each_entry(page, &pool->page_list, page_list) {
 331                 if (dma < page->dma)
 332                         continue;
 333                 if (dma < (page->dma + pool->allocation))
 334                         goto done;
 335         }
 336         page = NULL;
 337 done:
 338         spin_unlock_irqrestore (&pool->lock, flags);
 339         return page;
 340 }
 341
 342
 343 /**
 344  * dma_pool_free - put block back into dma pool
 345  * @pool: the dma pool holding the block
 346  * @vaddr: virtual address of block
 347  * @dma: dma address of block
 348  *
 349  * Caller promises neither device nor driver will again touch this block
 350  * unless it is first re-allocated.
 351  */
 352 void
 353 dma_pool_free (struct dma_pool *pool, void *vaddr, dma_addr_t dma)
 354 {
 355         struct dma_page         *page;
 356         unsigned long           flags;
 357         int                     map, block;
 358
 359         if ((page = pool_find_page (pool, dma)) == 0) {
 360                 if (pool->dev)
 361                         dev_err(pool->dev, "dma_pool_free %s, %p/%lx (bad dma)\n",
 362                                 pool->name, vaddr, (unsigned long) dma);
 363                 else
 364                         printk (KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
 365                                 pool->name, vaddr, (unsigned long) dma);
 366                 return;
 367         }
 368
 369         block = dma - page->dma;
 370         block /= pool->size;
 371         map = block / BITS_PER_LONG;
 372         block %= BITS_PER_LONG;
 373
 374 #ifdef  CONFIG_DEBUG_SLAB
 375         if (((dma - page->dma) + (void *)page->vaddr) != vaddr) {
 376                 if (pool->dev)
 377                         dev_err(pool->dev, "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 378                                 pool->name, vaddr, (unsigned long long) dma);
 379                 else
 380                         printk (KERN_ERR "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
 381                                 pool->name, vaddr, (unsigned long long) dma);
 382                 return;
 383         }
 384         if (page->bitmap [map] & (1UL << block)) {
 385                 if (pool->dev)
 386                         dev_err(pool->dev, "dma_pool_free %s, dma %Lx already free\n",
 387                                 pool->name, (unsigned long long)dma);
 388                 else
 389                         printk (KERN_ERR "dma_pool_free %s, dma %Lx already free\n",
 390                                 pool->name, (unsigned long long)dma);
 391                 return;
 392         }
 393         memset (vaddr, POOL_POISON_FREED, pool->size);
 394 #endif
 395
 396         spin_lock_irqsave (&pool->lock, flags);
 397         page->in_use--;
 398         set_bit (block, &page->bitmap [map]);
 399         if (waitqueue_active (&pool->waitq))
 400                 wake_up (&pool->waitq);
 401         /*
 402          * Resist a temptation to do
 403          *    if (!is_page_busy(bpp, page->bitmap)) pool_free_page(pool, page);
 404          * Better have a few empty pages hang around.
 405          */
 406         spin_unlock_irqrestore (&pool->lock, flags);
 407 }
 408
 409
 410 EXPORT_SYMBOL (dma_pool_create);
 411 EXPORT_SYMBOL (dma_pool_destroy);
 412 EXPORT_SYMBOL (dma_pool_alloc);
 413 EXPORT_SYMBOL (dma_pool_free);