#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) {
int ret;
down (&pools_lock);
if (list_empty (&dev->dma_pools))
ret = device_create_file (dev, &dev_attr_pools);
else
ret = 0;
/* note: not currently insisting "name" be unique */
if (!ret)
list_add (&retval->pools, &dev->dma_pools);
else {
kfree(retval);
retval = NULL;
}
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);
