AuxXxilium/linux_dsm_epyc7002
1
0
Fork 0
mirror of https://github.com/AuxXxilium/linux_dsm_epyc7002.git synced 2025-01-19 21:36:22 +07:00
Code Issues Actions Packages Projects Releases Wiki Activity

dma-mapping: add generic helpers for mapping sgtable objects

Browse Source 
struct sg_table is a common structure used for describing a memory
buffer. It consists of a scatterlist with memory pages and DMA addresses
(sgl entry), as well as the number of scatterlist entries: CPU pages
(orig_nents entry) and DMA mapped pages (nents entry).

It turned out that it was a common mistake to misuse nents and orig_nents
entries, calling DMA-mapping functions with a wrong number of entries or
ignoring the number of mapped entries returned by the dma_map_sg
function.

To avoid such issues, let's introduce a common wrappers operating
directly on the struct sg_table objects, which take care of the proper
use of the nents and orig_nents entries.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Marek Szyprowski 2020-05-13 15:32:08 +02:00 committed by Christoph Hellwig
parent 24085f70a6
commit d9d200bceb
1 changed files with 80 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

80
include/linux/dma-mapping.h
View File

@ -609,6 +609,86 @@ static inline void dma_sync_single_range_for_device(struct device *dev,
return dma_sync_single_for_device(dev, addr + offset, size, dir);
}
/**
* dma_map_sgtable - Map the given buffer for DMA
* @dev: The device for which to perform the DMA operation
* @sgt: The sg_table object describing the buffer
* @dir: DMA direction
* @attrs: Optional DMA attributes for the map operation
*
* Maps a buffer described by a scatterlist stored in the given sg_table
* object for the @dir DMA operation by the @dev device. After success the
* ownership for the buffer is transferred to the DMA domain. One has to
* call dma_sync_sgtable_for_cpu() or dma_unmap_sgtable() to move the
* ownership of the buffer back to the CPU domain before touching the
* buffer by the CPU.
*
* Returns 0 on success or -EINVAL on error during mapping the buffer.
*/
static inline int dma_map_sgtable(struct device *dev, struct sg_table *sgt,
enum dma_data_direction dir, unsigned long attrs)
{
int nents;
nents = dma_map_sg_attrs(dev, sgt->sgl, sgt->orig_nents, dir, attrs);
if (nents <= 0)
return -EINVAL;
sgt->nents = nents;
return 0;
}
/**
* dma_unmap_sgtable - Unmap the given buffer for DMA
* @dev: The device for which to perform the DMA operation
* @sgt: The sg_table object describing the buffer
* @dir: DMA direction
* @attrs: Optional DMA attributes for the unmap operation
*
* Unmaps a buffer described by a scatterlist stored in the given sg_table
* object for the @dir DMA operation by the @dev device. After this function
* the ownership of the buffer is transferred back to the CPU domain.
*/
static inline void dma_unmap_sgtable(struct device *dev, struct sg_table *sgt,
enum dma_data_direction dir, unsigned long attrs)
{
dma_unmap_sg_attrs(dev, sgt->sgl, sgt->orig_nents, dir, attrs);
}
/**
* dma_sync_sgtable_for_cpu - Synchronize the given buffer for CPU access
* @dev: The device for which to perform the DMA operation
* @sgt: The sg_table object describing the buffer
* @dir: DMA direction
*
* Performs the needed cache synchronization and moves the ownership of the
* buffer back to the CPU domain, so it is safe to perform any access to it
* by the CPU. Before doing any further DMA operations, one has to transfer
* the ownership of the buffer back to the DMA domain by calling the
* dma_sync_sgtable_for_device().
*/
static inline void dma_sync_sgtable_for_cpu(struct device *dev,
struct sg_table *sgt, enum dma_data_direction dir)
{
dma_sync_sg_for_cpu(dev, sgt->sgl, sgt->orig_nents, dir);
}
/**
* dma_sync_sgtable_for_device - Synchronize the given buffer for DMA
* @dev: The device for which to perform the DMA operation
* @sgt: The sg_table object describing the buffer
* @dir: DMA direction
*
* Performs the needed cache synchronization and moves the ownership of the
* buffer back to the DMA domain, so it is safe to perform the DMA operation.
* Once finished, one has to call dma_sync_sgtable_for_cpu() or
* dma_unmap_sgtable().
*/
static inline void dma_sync_sgtable_for_device(struct device *dev,
struct sg_table *sgt, enum dma_data_direction dir)
{
dma_sync_sg_for_device(dev, sgt->sgl, sgt->orig_nents, dir);
}
#define dma_map_single(d, a, s, r) dma_map_single_attrs(d, a, s, r, 0)
#define dma_unmap_single(d, a, s, r) dma_unmap_single_attrs(d, a, s, r, 0)
#define dma_map_sg(d, s, n, r) dma_map_sg_attrs(d, s, n, r, 0)