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/*
* Copyright (C) 2006 Benjamin Herrenschmidt, IBM Corporation
*
* Provide default implementations of the DMA mapping callbacks for
* directly mapped busses.
*/
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <asm/bug.h>
#include <asm/abs_addr.h>
/*
* Generic direct DMA implementation
*
* This implementation supports a per-device offset that can be applied if
* the address at which memory is visible to devices is not 0. Platform code
* can set archdata.dma_data to an unsigned long holding the offset. By
* default the offset is zero.
*/
static unsigned long get_dma_direct_offset(struct device *dev)
{
return (unsigned long)dev->archdata.dma_data;
}
static void *dma_direct_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flag)
{
struct page *page;
void *ret;
int node = dev_to_node(dev);
page = alloc_pages_node(node, flag, get_order(size));
if (page == NULL)
return NULL;
ret = page_address(page);
memset(ret, 0, size);
*dma_handle = virt_to_abs(ret) + get_dma_direct_offset(dev);
return ret;
}
static void dma_direct_free_coherent(struct device *dev, size_t size,
void *vaddr, dma_addr_t dma_handle)
{
free_pages((unsigned long)vaddr, get_order(size));
}
static dma_addr_t dma_direct_map_single(struct device *dev, void *ptr,
size_t size,
enum dma_data_direction direction,
struct dma_attrs *attrs)
{
return virt_to_abs(ptr) + get_dma_direct_offset(dev);
}
static void dma_direct_unmap_single(struct device *dev, dma_addr_t dma_addr,
size_t size,
enum dma_data_direction direction,
struct dma_attrs *attrs)
{
}
static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
int nents, enum dma_data_direction direction,
struct dma_attrs *attrs)
{
struct scatterlist *sg;
int i;
for_each_sg(sgl, sg, nents, i) {
sg->dma_address = sg_phys(sg) + get_dma_direct_offset(dev);
sg->dma_length = sg->length;
}
return nents;
}
static void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sg,
int nents, enum dma_data_direction direction,
struct dma_attrs *attrs)
{
}
static int dma_direct_dma_supported(struct device *dev, u64 mask)
{
/* Could be improved to check for memory though it better be
* done via some global so platforms can set the limit in case
* they have limited DMA windows
*/
return mask >= DMA_32BIT_MASK;
}
struct dma_mapping_ops dma_direct_ops = {
.alloc_coherent = dma_direct_alloc_coherent,
.free_coherent = dma_direct_free_coherent,
.map_single = dma_direct_map_single,
.unmap_single = dma_direct_unmap_single,
.map_sg = dma_direct_map_sg,
.unmap_sg = dma_direct_unmap_sg,
.dma_supported = dma_direct_dma_supported,
};
EXPORT_SYMBOL(dma_direct_ops);
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