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/*
* Copyright (C) 2009-2010 PetaLogix
* 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 <linux/gfp.h>
#include <linux/dma-debug.h>
#include <asm/bug.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 PCI_DRAM_OFFSET.
*/
static unsigned long get_dma_direct_offset(struct device *dev)
{
if (likely(dev))
return (unsigned long)dev->archdata.dma_data;
return PCI_DRAM_OFFSET; /* FIXME Not sure if is correct */
}
#define NOT_COHERENT_CACHE
static void *dma_direct_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t flag)
{
#ifdef NOT_COHERENT_CACHE
return consistent_alloc(flag, size, dma_handle);
#else
void *ret;
struct page *page;
int node = dev_to_node(dev);
/* ignore region specifiers */
flag &= ~(__GFP_HIGHMEM);
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_phys(ret) + get_dma_direct_offset(dev);
return ret;
#endif
}
static void dma_direct_free_coherent(struct device *dev, size_t size,
void *vaddr, dma_addr_t dma_handle)
{
#ifdef NOT_COHERENT_CACHE
consistent_free(size, vaddr);
#else
free_pages((unsigned long)vaddr, get_order(size));
#endif
}
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;
/* FIXME this part of code is untested */
for_each_sg(sgl, sg, nents, i) {
sg->dma_address = sg_phys(sg) + get_dma_direct_offset(dev);
__dma_sync(page_to_phys(sg_page(sg)) + sg->offset,
sg->length, direction);
}
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)
{
return 1;
}
static inline dma_addr_t dma_direct_map_page(struct device *dev,
struct page *page,
unsigned long offset,
size_t size,
enum dma_data_direction direction,
struct dma_attrs *attrs)
{
__dma_sync(page_to_phys(page) + offset, size, direction);
return page_to_phys(page) + offset + get_dma_direct_offset(dev);
}
static inline void dma_direct_unmap_page(struct device *dev,
dma_addr_t dma_address,
size_t size,
enum dma_data_direction direction,
struct dma_attrs *attrs)
{
/* There is not necessary to do cache cleanup
*
* phys_to_virt is here because in __dma_sync_page is __virt_to_phys and
* dma_address is physical address
*/
__dma_sync(dma_address, size, direction);
}
static inline void
dma_direct_sync_single_for_cpu(struct device *dev,
dma_addr_t dma_handle, size_t size,
enum dma_data_direction direction)
{
/*
* It's pointless to flush the cache as the memory segment
* is given to the CPU
*/
if (direction == DMA_FROM_DEVICE)
__dma_sync(dma_handle, size, direction);
}
static inline void
dma_direct_sync_single_for_device(struct device *dev,
dma_addr_t dma_handle, size_t size,
enum dma_data_direction direction)
{
/*
* It's pointless to invalidate the cache if the device isn't
* supposed to write to the relevant region
*/
if (direction == DMA_TO_DEVICE)
__dma_sync(dma_handle, size, direction);
}
static inline void
dma_direct_sync_sg_for_cpu(struct device *dev,
struct scatterlist *sgl, int nents,
enum dma_data_direction direction)
{
struct scatterlist *sg;
int i;
/* FIXME this part of code is untested */
if (direction == DMA_FROM_DEVICE)
for_each_sg(sgl, sg, nents, i)
__dma_sync(sg->dma_address, sg->length, direction);
}
static inline void
dma_direct_sync_sg_for_device(struct device *dev,
struct scatterlist *sgl, int nents,
enum dma_data_direction direction)
{
struct scatterlist *sg;
int i;
/* FIXME this part of code is untested */
if (direction == DMA_TO_DEVICE)
for_each_sg(sgl, sg, nents, i)
__dma_sync(sg->dma_address, sg->length, direction);
}
struct dma_map_ops dma_direct_ops = {
.alloc_coherent = dma_direct_alloc_coherent,
.free_coherent = dma_direct_free_coherent,
.map_sg = dma_direct_map_sg,
.unmap_sg = dma_direct_unmap_sg,
.dma_supported = dma_direct_dma_supported,
.map_page = dma_direct_map_page,
.unmap_page = dma_direct_unmap_page,
.sync_single_for_cpu = dma_direct_sync_single_for_cpu,
.sync_single_for_device = dma_direct_sync_single_for_device,
.sync_sg_for_cpu = dma_direct_sync_sg_for_cpu,
.sync_sg_for_device = dma_direct_sync_sg_for_device,
};
EXPORT_SYMBOL(dma_direct_ops);
/* Number of entries preallocated for DMA-API debugging */
#define PREALLOC_DMA_DEBUG_ENTRIES (1 << 16)
static int __init dma_init(void)
{
dma_debug_init(PREALLOC_DMA_DEBUG_ENTRIES);
return 0;
}
fs_initcall(dma_init);
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