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/*
* Dynamic DMA mapping support.
*
* On i386 there is no hardware dynamic DMA address translation,
* so consistent alloc/free are merely page allocation/freeing.
* The rest of the dynamic DMA mapping interface is implemented
* in asm/pci.h.
*/
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/pci.h>
#include <linux/module.h>
#include <asm/io.h>
/* Dummy device used for NULL arguments (normally ISA). Better would
be probably a smaller DMA mask, but this is bug-to-bug compatible
to i386. */
struct device fallback_dev = {
.bus_id = "fallback device",
.coherent_dma_mask = DMA_32BIT_MASK,
.dma_mask = &fallback_dev.coherent_dma_mask,
};
static int dma_alloc_from_coherent_mem(struct device *dev, ssize_t size,
dma_addr_t *dma_handle, void **ret)
{
struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
int order = get_order(size);
if (mem) {
int page = bitmap_find_free_region(mem->bitmap, mem->size,
order);
if (page >= 0) {
*dma_handle = mem->device_base + (page << PAGE_SHIFT);
*ret = mem->virt_base + (page << PAGE_SHIFT);
memset(*ret, 0, size);
}
if (mem->flags & DMA_MEMORY_EXCLUSIVE)
*ret = NULL;
}
return (mem != NULL);
}
static int dma_release_coherent(struct device *dev, int order, void *vaddr)
{
struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
if (mem && vaddr >= mem->virt_base && vaddr <
(mem->virt_base + (mem->size << PAGE_SHIFT))) {
int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
bitmap_release_region(mem->bitmap, page, order);
return 1;
}
return 0;
}
/* Allocate DMA memory on node near device */
noinline struct page *
dma_alloc_pages(struct device *dev, gfp_t gfp, unsigned order)
{
int node;
node = dev_to_node(dev);
return alloc_pages_node(node, gfp, order);
}
void *dma_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp)
{
void *ret = NULL;
struct page *page;
dma_addr_t bus;
int order = get_order(size);
/* ignore region specifiers */
gfp &= ~(__GFP_DMA | __GFP_HIGHMEM);
if (dma_alloc_from_coherent_mem(dev, size, dma_handle, &ret))
return ret;
if (!dev)
dev = &fallback_dev;
page = dma_alloc_pages(dev, gfp, order);
if (page == NULL)
return NULL;
ret = page_address(page);
bus = page_to_phys(page);
memset(ret, 0, size);
*dma_handle = bus;
return ret;
}
EXPORT_SYMBOL(dma_alloc_coherent);
void dma_free_coherent(struct device *dev, size_t size,
void *vaddr, dma_addr_t dma_handle)
{
int order = get_order(size);
WARN_ON(irqs_disabled()); /* for portability */
if (dma_release_coherent(dev, order, vaddr))
return;
if (dma_ops->unmap_single)
dma_ops->unmap_single(dev, dma_handle, size, 0);
free_pages((unsigned long)vaddr, order);
}
EXPORT_SYMBOL(dma_free_coherent);
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