415 lines
10 KiB
C
415 lines
10 KiB
C
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#include <linux/device.h>
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#include <linux/mm.h>
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#include <asm/io.h> /* Needed for i386 to build */
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#include <asm/scatterlist.h> /* Needed for i386 to build */
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#include <linux/dma-mapping.h>
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#include <linux/dmapool.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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/*
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* Pool allocator ... wraps the dma_alloc_coherent page allocator, so
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* small blocks are easily used by drivers for bus mastering controllers.
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* This should probably be sharing the guts of the slab allocator.
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*/
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struct dma_pool { /* the pool */
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struct list_head page_list;
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spinlock_t lock;
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size_t blocks_per_page;
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size_t size;
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struct device *dev;
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size_t allocation;
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char name [32];
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wait_queue_head_t waitq;
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struct list_head pools;
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};
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struct dma_page { /* cacheable header for 'allocation' bytes */
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struct list_head page_list;
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void *vaddr;
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dma_addr_t dma;
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unsigned in_use;
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unsigned long bitmap [0];
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};
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#define POOL_TIMEOUT_JIFFIES ((100 /* msec */ * HZ) / 1000)
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#define POOL_POISON_FREED 0xa7 /* !inuse */
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#define POOL_POISON_ALLOCATED 0xa9 /* !initted */
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static DECLARE_MUTEX (pools_lock);
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static ssize_t
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show_pools (struct device *dev, struct device_attribute *attr, char *buf)
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{
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unsigned temp;
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unsigned size;
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char *next;
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struct dma_page *page;
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struct dma_pool *pool;
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next = buf;
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size = PAGE_SIZE;
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temp = scnprintf(next, size, "poolinfo - 0.1\n");
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size -= temp;
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next += temp;
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down (&pools_lock);
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list_for_each_entry(pool, &dev->dma_pools, pools) {
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unsigned pages = 0;
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unsigned blocks = 0;
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list_for_each_entry(page, &pool->page_list, page_list) {
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pages++;
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blocks += page->in_use;
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}
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/* per-pool info, no real statistics yet */
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temp = scnprintf(next, size, "%-16s %4u %4Zu %4Zu %2u\n",
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pool->name,
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blocks, pages * pool->blocks_per_page,
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pool->size, pages);
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size -= temp;
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next += temp;
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}
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up (&pools_lock);
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return PAGE_SIZE - size;
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}
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static DEVICE_ATTR (pools, S_IRUGO, show_pools, NULL);
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/**
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* dma_pool_create - Creates a pool of consistent memory blocks, for dma.
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* @name: name of pool, for diagnostics
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* @dev: device that will be doing the DMA
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* @size: size of the blocks in this pool.
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* @align: alignment requirement for blocks; must be a power of two
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* @allocation: returned blocks won't cross this boundary (or zero)
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* Context: !in_interrupt()
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*
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* Returns a dma allocation pool with the requested characteristics, or
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* null if one can't be created. Given one of these pools, dma_pool_alloc()
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* may be used to allocate memory. Such memory will all have "consistent"
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* DMA mappings, accessible by the device and its driver without using
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* cache flushing primitives. The actual size of blocks allocated may be
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* larger than requested because of alignment.
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*
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* If allocation is nonzero, objects returned from dma_pool_alloc() won't
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* cross that size boundary. This is useful for devices which have
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* addressing restrictions on individual DMA transfers, such as not crossing
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* boundaries of 4KBytes.
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*/
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struct dma_pool *
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dma_pool_create (const char *name, struct device *dev,
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size_t size, size_t align, size_t allocation)
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{
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struct dma_pool *retval;
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if (align == 0)
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align = 1;
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if (size == 0)
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return NULL;
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else if (size < align)
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size = align;
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else if ((size % align) != 0) {
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size += align + 1;
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size &= ~(align - 1);
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}
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if (allocation == 0) {
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if (PAGE_SIZE < size)
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allocation = size;
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else
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allocation = PAGE_SIZE;
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// FIXME: round up for less fragmentation
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} else if (allocation < size)
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return NULL;
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if (!(retval = kmalloc (sizeof *retval, SLAB_KERNEL)))
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return retval;
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strlcpy (retval->name, name, sizeof retval->name);
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retval->dev = dev;
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INIT_LIST_HEAD (&retval->page_list);
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spin_lock_init (&retval->lock);
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retval->size = size;
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retval->allocation = allocation;
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retval->blocks_per_page = allocation / size;
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init_waitqueue_head (&retval->waitq);
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if (dev) {
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down (&pools_lock);
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if (list_empty (&dev->dma_pools))
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device_create_file (dev, &dev_attr_pools);
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/* note: not currently insisting "name" be unique */
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list_add (&retval->pools, &dev->dma_pools);
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up (&pools_lock);
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} else
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INIT_LIST_HEAD (&retval->pools);
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return retval;
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}
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static struct dma_page *
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pool_alloc_page (struct dma_pool *pool, gfp_t mem_flags)
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{
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struct dma_page *page;
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int mapsize;
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mapsize = pool->blocks_per_page;
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mapsize = (mapsize + BITS_PER_LONG - 1) / BITS_PER_LONG;
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mapsize *= sizeof (long);
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page = (struct dma_page *) kmalloc (mapsize + sizeof *page, mem_flags);
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if (!page)
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return NULL;
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page->vaddr = dma_alloc_coherent (pool->dev,
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pool->allocation,
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&page->dma,
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mem_flags);
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if (page->vaddr) {
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memset (page->bitmap, 0xff, mapsize); // bit set == free
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#ifdef CONFIG_DEBUG_SLAB
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memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
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#endif
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list_add (&page->page_list, &pool->page_list);
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page->in_use = 0;
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} else {
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kfree (page);
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page = NULL;
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}
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return page;
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}
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static inline int
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is_page_busy (int blocks, unsigned long *bitmap)
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{
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while (blocks > 0) {
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if (*bitmap++ != ~0UL)
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return 1;
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blocks -= BITS_PER_LONG;
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}
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return 0;
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}
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static void
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pool_free_page (struct dma_pool *pool, struct dma_page *page)
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{
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dma_addr_t dma = page->dma;
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#ifdef CONFIG_DEBUG_SLAB
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memset (page->vaddr, POOL_POISON_FREED, pool->allocation);
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#endif
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dma_free_coherent (pool->dev, pool->allocation, page->vaddr, dma);
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list_del (&page->page_list);
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kfree (page);
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}
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/**
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* dma_pool_destroy - destroys a pool of dma memory blocks.
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* @pool: dma pool that will be destroyed
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* Context: !in_interrupt()
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*
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* Caller guarantees that no more memory from the pool is in use,
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* and that nothing will try to use the pool after this call.
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*/
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void
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dma_pool_destroy (struct dma_pool *pool)
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{
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down (&pools_lock);
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list_del (&pool->pools);
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if (pool->dev && list_empty (&pool->dev->dma_pools))
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device_remove_file (pool->dev, &dev_attr_pools);
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up (&pools_lock);
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while (!list_empty (&pool->page_list)) {
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struct dma_page *page;
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page = list_entry (pool->page_list.next,
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struct dma_page, page_list);
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if (is_page_busy (pool->blocks_per_page, page->bitmap)) {
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if (pool->dev)
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dev_err(pool->dev, "dma_pool_destroy %s, %p busy\n",
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pool->name, page->vaddr);
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else
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printk (KERN_ERR "dma_pool_destroy %s, %p busy\n",
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pool->name, page->vaddr);
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/* leak the still-in-use consistent memory */
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list_del (&page->page_list);
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kfree (page);
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} else
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pool_free_page (pool, page);
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}
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kfree (pool);
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}
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/**
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* dma_pool_alloc - get a block of consistent memory
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* @pool: dma pool that will produce the block
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* @mem_flags: GFP_* bitmask
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* @handle: pointer to dma address of block
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*
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* This returns the kernel virtual address of a currently unused block,
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* and reports its dma address through the handle.
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* If such a memory block can't be allocated, null is returned.
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*/
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void *
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dma_pool_alloc (struct dma_pool *pool, gfp_t mem_flags, dma_addr_t *handle)
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{
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unsigned long flags;
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struct dma_page *page;
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int map, block;
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size_t offset;
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void *retval;
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restart:
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spin_lock_irqsave (&pool->lock, flags);
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list_for_each_entry(page, &pool->page_list, page_list) {
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int i;
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/* only cachable accesses here ... */
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for (map = 0, i = 0;
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i < pool->blocks_per_page;
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i += BITS_PER_LONG, map++) {
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if (page->bitmap [map] == 0)
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continue;
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block = ffz (~ page->bitmap [map]);
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if ((i + block) < pool->blocks_per_page) {
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clear_bit (block, &page->bitmap [map]);
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offset = (BITS_PER_LONG * map) + block;
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offset *= pool->size;
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goto ready;
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}
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}
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}
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if (!(page = pool_alloc_page (pool, SLAB_ATOMIC))) {
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if (mem_flags & __GFP_WAIT) {
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DECLARE_WAITQUEUE (wait, current);
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current->state = TASK_INTERRUPTIBLE;
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add_wait_queue (&pool->waitq, &wait);
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spin_unlock_irqrestore (&pool->lock, flags);
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schedule_timeout (POOL_TIMEOUT_JIFFIES);
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remove_wait_queue (&pool->waitq, &wait);
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goto restart;
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}
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retval = NULL;
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goto done;
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}
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clear_bit (0, &page->bitmap [0]);
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offset = 0;
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ready:
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page->in_use++;
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retval = offset + page->vaddr;
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*handle = offset + page->dma;
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#ifdef CONFIG_DEBUG_SLAB
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memset (retval, POOL_POISON_ALLOCATED, pool->size);
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#endif
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done:
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spin_unlock_irqrestore (&pool->lock, flags);
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return retval;
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}
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static struct dma_page *
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pool_find_page (struct dma_pool *pool, dma_addr_t dma)
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{
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unsigned long flags;
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struct dma_page *page;
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spin_lock_irqsave (&pool->lock, flags);
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list_for_each_entry(page, &pool->page_list, page_list) {
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if (dma < page->dma)
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continue;
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if (dma < (page->dma + pool->allocation))
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goto done;
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}
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page = NULL;
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done:
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spin_unlock_irqrestore (&pool->lock, flags);
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return page;
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}
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/**
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* dma_pool_free - put block back into dma pool
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* @pool: the dma pool holding the block
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* @vaddr: virtual address of block
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* @dma: dma address of block
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*
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* Caller promises neither device nor driver will again touch this block
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* unless it is first re-allocated.
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*/
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void
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dma_pool_free (struct dma_pool *pool, void *vaddr, dma_addr_t dma)
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{
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struct dma_page *page;
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unsigned long flags;
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int map, block;
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if ((page = pool_find_page (pool, dma)) == 0) {
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if (pool->dev)
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dev_err(pool->dev, "dma_pool_free %s, %p/%lx (bad dma)\n",
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pool->name, vaddr, (unsigned long) dma);
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else
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printk (KERN_ERR "dma_pool_free %s, %p/%lx (bad dma)\n",
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pool->name, vaddr, (unsigned long) dma);
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return;
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}
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block = dma - page->dma;
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block /= pool->size;
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map = block / BITS_PER_LONG;
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block %= BITS_PER_LONG;
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#ifdef CONFIG_DEBUG_SLAB
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if (((dma - page->dma) + (void *)page->vaddr) != vaddr) {
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if (pool->dev)
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dev_err(pool->dev, "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
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pool->name, vaddr, (unsigned long long) dma);
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else
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printk (KERN_ERR "dma_pool_free %s, %p (bad vaddr)/%Lx\n",
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pool->name, vaddr, (unsigned long long) dma);
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return;
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}
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if (page->bitmap [map] & (1UL << block)) {
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if (pool->dev)
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dev_err(pool->dev, "dma_pool_free %s, dma %Lx already free\n",
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pool->name, (unsigned long long)dma);
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else
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printk (KERN_ERR "dma_pool_free %s, dma %Lx already free\n",
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pool->name, (unsigned long long)dma);
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return;
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}
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memset (vaddr, POOL_POISON_FREED, pool->size);
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#endif
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spin_lock_irqsave (&pool->lock, flags);
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page->in_use--;
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set_bit (block, &page->bitmap [map]);
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if (waitqueue_active (&pool->waitq))
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wake_up (&pool->waitq);
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/*
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* Resist a temptation to do
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* if (!is_page_busy(bpp, page->bitmap)) pool_free_page(pool, page);
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* Better have a few empty pages hang around.
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*/
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spin_unlock_irqrestore (&pool->lock, flags);
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}
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EXPORT_SYMBOL (dma_pool_create);
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EXPORT_SYMBOL (dma_pool_destroy);
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EXPORT_SYMBOL (dma_pool_alloc);
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EXPORT_SYMBOL (dma_pool_free);
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