#include <linux/device.h> #include <linux/mm.h> #include <asm/io.h> /* Needed for i386 to build */ #include <asm/scatterlist.h> /* Needed for i386 to build */ #include <linux/dma-mapping.h> #include <linux/dmapool.h> #include <linux/slab.h> #include <linux/module.h> #include <linux/poison.h> /* * Pool allocator ... wraps the dma_alloc_coherent page allocator, so * small blocks are easily used by drivers for bus mastering controllers. * This should probably be sharing the guts of the slab allocator. */ struct dma_pool { /* the pool */ struct list_head page_list; spinlock_t lock; size_t blocks_per_page; size_t size; struct device *dev; size_t allocation; char name [32]; wait_queue_head_t waitq; struct list_head pools; }; struct dma_page { /* cacheable header for 'allocation' bytes */ struct list_head page_list; void *vaddr; dma_addr_t dma; unsigned in_use; unsigned long bitmap [0]; }; #define POOL_TIMEOUT_JIFFIES ((100 /* msec */ * HZ) / 1000) static DECLARE_MUTEX (pools_lock); static ssize_t show_pools (struct device *dev, struct device_attribute *attr, char *buf) { unsigned temp; unsigned size; char *next; struct dma_page *page; struct dma_pool *pool; next = buf; size = PAGE_SIZE; temp = scnprintf(next, size, "poolinfo - 0.1\n"); size -= temp; next += temp; down (&pools_lock); list_for_each_entry(pool, &dev->dma_pools, pools) { unsigned pages = 0; unsigned blocks = 0; list_for_each_entry(page, &pool->page_list, page_list) { pages++; blocks += page->in_use; } /* per-pool info, no real statistics yet */ temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n", pool->name, blocks, pages * pool->blocks_per_page, pool->size, pages); size -= temp; next += temp; } up (&pools_lock); return PAGE_SIZE - size; } static DEVICE_ATTR (pools, S_IRUGO, show_pools, NULL); /** * dma_pool_create - Creates a pool of consistent memory blocks, for dma. * @name: name of pool, for diagnostics * @dev: device that will be doing the DMA * @size: size of the blocks in this pool. * @align: alignment requirement for blocks; must be a power of two * @allocation: returned blocks won't cross this boundary (or zero) * Context: !in_interrupt() * * Returns a dma allocation pool with the requested characteristics, or * null if one can't be created. Given one of these pools, dma_pool_alloc() * may be used to allocate memory. Such memory will all have "consistent" * DMA mappings, accessible by the device and its driver without using * cache flushing primitives. The actual size of blocks allocated may be * larger than requested because of alignment. * * If allocation is nonzero, objects returned from dma_pool_alloc() won't * cross that size boundary. This is useful for devices which have * addressing restrictions on individual DMA transfers, such as not crossing * boundaries of 4KBytes. */ struct dma_pool * dma_pool_create (const char *name, struct device *dev, size_t size, size_t align, size_t allocation) { struct dma_pool *retval; if (align == 0) align = 1; if (size == 0) return NULL; else if (size < align) size = align; else if ((size % align) != 0) { size += align + 1; size &= ~(align - 1); } if (allocation == 0) { if (PAGE_SIZE < size) allocation = size; else allocation = PAGE_SIZE; // FIXME: round up for less fragmentation } else if (allocation < size) return NULL; if (!(retval = kmalloc (sizeof *retval, SLAB_KERNEL))) return retval; strlcpy (retval->name, name, sizeof retval->name); retval->dev = dev; INIT_LIST_HEAD (&retval->page_list); spin_lock_init (&retval->lock); retval->size = size; retval->allocation = allocation; retval->blocks_per_page = allocation / size; init_waitqueue_head (&retval->waitq); if (dev) { down (&pools_lock); if (list_empty (&dev->dma_pools)) device_create_file (dev, &dev_attr_pools); /* note: not currently insisting "name" be unique */ list_add (&retval->pools, &dev->dma_pools); up (&pools_lock); } else INIT_LIST_HEAD (&retval->pools); return retval; } static struct dma_page * pool_alloc_page (struct dma_pool *pool, gfp_t mem_flags) { struct dma_page *page; int mapsize; mapsize = pool->blocks_per_page; mapsize = (mapsize + BITS_PER_LONG - 1) / BITS_PER_LONG; mapsize *= sizeof (long); page = (struct dma_page *) kmalloc (mapsize + sizeof *page, mem_flags); if (!page) return NULL; page->vaddr = dma_alloc_coherent (pool->dev, pool->allocation, &page->dma, mem_flags); if (page->vaddr) { memset (page->bitmap, 0xff, mapsize); // bit set == free #ifdef CONFIG_DEBUG_SLAB memset (page->vaddr, POOL_POISON_FREED, pool->allocation); #endif list_add (&page->page_list, &pool->page_list); page->in_use = 0; } else { kfree (page); page = NULL; } return page; } static inline int is_page_busy (int blocks, unsigned long *bitmap) { while (blocks > 0) { if (*bitmap++ != ~0UL) return 1; blocks -= BITS_PER_LONG; } return 0; } static void pool_free_page (struct dma_pool *pool, struct dma_page *page) { dma_addr_t dma = page->dma; #ifdef CONFIG_DEBUG_SLAB memset (page->vaddr, POOL_POISON_FREED, pool->allocation); #endif dma_free_coherent (pool->dev, pool->allocation, page->vaddr, dma); list_del (&page->page_list); kfree (page); } /** * dma_pool_destroy - destroys a pool of dma memory blocks. * @pool: dma pool that will be destroyed * Context: !in_interrupt() * * Caller guarantees that no more memory from the pool is in use, * and that nothing will try to use the pool after this call. */ void dma_pool_destroy (struct dma_pool *pool) { down (&pools_lock); list_del (&pool->pools); if (pool->dev && list_empty (&pool->dev->dma_pools)) device_remove_file (pool->dev, &dev_attr_pools); up (&pools_lock); while (!list_empty (&pool->page_list)) { struct dma_page *page; page = list_entry (pool->page_list.next, struct dma_page, page_list); if (is_page_busy (pool->blocks_per_page, page->bitmap)) { if (pool->dev) dev_err(pool->dev, "dma_pool_destroy %s, %p busy\n", pool->name, page->vaddr); else printk (KERN_ERR "dma_pool_destroy %s, %p busy\n", pool->name, page->vaddr); /* leak the still-in-use consistent memory */ list_del (&page->page_list); kfree (page); } else pool_free_page (pool, page); } kfree (pool); } /** * dma_pool_alloc - get a block of consistent memory * @pool: dma pool that will produce the block * @mem_flags: GFP_* bitmask * @handle: pointer to dma address of block * * This returns the kernel virtual address of a currently unused block, * and reports its dma address through the handle. * If such a memory block can't be allocated, null is returned. */ void * dma_pool_alloc (struct dma_pool *pool, gfp_t mem_flags, dma_addr_t *handle) { unsigned long flags; struct dma_page *page; int map, block; size_t offset; void *retval; restart: spin_lock_irqsave (&pool->lock, flags); list_for_each_entry(page, &pool->page_list, page_list) { int i; /* only cachable accesses here ... */ for (map = 0, i = 0; i < pool->blocks_per_page; i += BITS_PER_LONG, map++) { if (page->bitmap [map] == 0) continue; block = ffz (~ page->bitmap [map]); if ((i + block) < pool->blocks_per_page) { clear_bit (block, &page->bitmap [map]); offset = (BITS_PER_LONG * map) + block; offset *= pool->size; goto ready; } } } if (!(page = pool_alloc_page (pool, SLAB_ATOMIC))) { if (mem_flags & __GFP_WAIT) { DECLARE_WAITQUEUE (wait, current); current->state = TASK_INTERRUPTIBLE; add_wait_queue (&pool->waitq, &wait); spin_unlock_irqrestore (&pool->lock, flags); schedule_timeout (POOL_TIMEOUT_JIFFIES); remove_wait_queue (&pool->waitq, &wait); goto restart; } retval = NULL; goto done; } clear_bit (0, &page->bitmap [0]); offset = 0; ready: page->in_use++; retval = offset + page->vaddr; *handle = offset + page->dma; #ifdef CONFIG_DEBUG_SLAB memset (retval, POOL_POISON_ALLOCATED, pool->size); #endif done: spin_unlock_irqrestore (&pool->lock, flags); return retval; } static struct dma_page * pool_find_page (struct dma_pool *pool, dma_addr_t dma) { unsigned long flags; struct dma_page *page; spin_lock_irqsave (&pool->lock, flags); list_for_each_entry(page, &pool->page_list, page_list) { if (dma < page->dma) continue; if (dma < (page->dma + pool->allocation)) goto done; } page = NULL; done: spin_unlock_irqrestore (&pool->lock, flags); return page; } /** * dma_pool_free - put block back into dma pool * @pool: the dma pool holding the block * @vaddr: virtual address of block * @dma: dma address of block * * Caller promises neither device nor driver will again touch this block * unless it is first re-allocated. */ void dma_pool_free (struct dma_pool *pool, void *vaddr, dma_addr_t dma) { struct dma_page *page; unsigned long flags; int map, block; if ((page = pool_find_page (pool, dma)) == 0) { if (pool->dev) dev_err(pool->dev, "dma_pool_free %s, %p/%lx (bad dma)\n", pool->name, vaddr, (unsigned long) dma); else printk (KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n", pool->name, vaddr, (unsigned long) dma); return; } block = dma - page->dma; block /= pool->size; map = block / BITS_PER_LONG; block %= BITS_PER_LONG; #ifdef CONFIG_DEBUG_SLAB if (((dma - page->dma) + (void *)page->vaddr) != vaddr) { if (pool->dev) dev_err(pool->dev, "dma_pool_free %s, %p (bad vaddr)/%Lx\n", pool->name, vaddr, (unsigned long long) dma); else printk (KERN_ERR "dma_pool_free %s, %p (bad vaddr)/%Lx\n", pool->name, vaddr, (unsigned long long) dma); return; } if (page->bitmap [map] & (1UL << block)) { if (pool->dev) dev_err(pool->dev, "dma_pool_free %s, dma %Lx already free\n", pool->name, (unsigned long long)dma); else printk (KERN_ERR "dma_pool_free %s, dma %Lx already free\n", pool->name, (unsigned long long)dma); return; } memset (vaddr, POOL_POISON_FREED, pool->size); #endif spin_lock_irqsave (&pool->lock, flags); page->in_use--; set_bit (block, &page->bitmap [map]); if (waitqueue_active (&pool->waitq)) wake_up (&pool->waitq); /* * Resist a temptation to do * if (!is_page_busy(bpp, page->bitmap)) pool_free_page(pool, page); * Better have a few empty pages hang around. */ spin_unlock_irqrestore (&pool->lock, flags); } EXPORT_SYMBOL (dma_pool_create); EXPORT_SYMBOL (dma_pool_destroy); EXPORT_SYMBOL (dma_pool_alloc); EXPORT_SYMBOL (dma_pool_free);