diff options
Diffstat (limited to 'drivers/base/dmapool.c')
| -rw-r--r-- | drivers/base/dmapool.c | 414 |
1 files changed, 414 insertions, 0 deletions
diff --git a/drivers/base/dmapool.c b/drivers/base/dmapool.c new file mode 100644 index 000000000000..f48833df61a2 --- /dev/null +++ b/drivers/base/dmapool.c @@ -0,0 +1,414 @@ + +#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> + +/* + * 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) +#define POOL_POISON_FREED 0xa7 /* !inuse */ +#define POOL_POISON_ALLOCATED 0xa9 /* !initted */ + +static DECLARE_MUTEX (pools_lock); + +static ssize_t +show_pools (struct device *dev, 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, unsigned int __nocast 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, int 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); |