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Commit 98f86c9e authored by Dave Airlie's avatar Dave Airlie Committed by Sumit Semwal
Browse files

dma-buf: add vmap interface 



The main requirement I have for this interface is for scanning out
using the USB gpu devices. Since these devices have to read the
framebuffer on updates and linearly compress it, using kmaps
is a major overhead for every update.

v2: fix warn issues pointed out by Sylwester Nawrocki.

v3: fix compile !CONFIG_DMA_SHARED_BUFFER and add _GPL for now

Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
Reviewed-by: default avatarRob Clark <rob.clark@linaro.org>
Signed-off-by: default avatarSumit Semwal <sumit.semwal@linaro.org>
parent 4c78513e

drivers/base/dma-buf.c

+34 −0
Original line number Diff line number Diff line
@@ -468,3 +468,37 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma, 
	return dmabuf->ops->mmap(dmabuf, vma);

}

EXPORT_SYMBOL_GPL(dma_buf_mmap);



/**

 * dma_buf_vmap - Create virtual mapping for the buffer object into kernel address space. Same restrictions as for vmap and friends apply.

 * @dma_buf:	[in]	buffer to vmap

 *

 * This call may fail due to lack of virtual mapping address space.

 * These calls are optional in drivers. The intended use for them

 * is for mapping objects linear in kernel space for high use objects.

 * Please attempt to use kmap/kunmap before thinking about these interfaces.

 */

void *dma_buf_vmap(struct dma_buf *dmabuf)

{

	if (WARN_ON(!dmabuf))

		return NULL;



	if (dmabuf->ops->vmap)

		return dmabuf->ops->vmap(dmabuf);

	return NULL;

}

EXPORT_SYMBOL_GPL(dma_buf_vmap);



/**

 * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.

 * @dma_buf:	[in]	buffer to vmap

 */

void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)

{

	if (WARN_ON(!dmabuf))

		return;



	if (dmabuf->ops->vunmap)

		dmabuf->ops->vunmap(dmabuf, vaddr);

}

EXPORT_SYMBOL_GPL(dma_buf_vunmap);

include/linux/dma-buf.h

+14 −0
Original line number Diff line number Diff line
@@ -98,6 +98,9 @@ struct dma_buf_ops { 
	void (*kunmap)(struct dma_buf *, unsigned long, void *);



	int (*mmap)(struct dma_buf *, struct vm_area_struct *vma);



	void *(*vmap)(struct dma_buf *);

	void (*vunmap)(struct dma_buf *, void *vaddr);

};



/**
@@ -176,6 +179,8 @@ void dma_buf_kunmap(struct dma_buf *, unsigned long, void *); 


int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,

		 unsigned long);

void *dma_buf_vmap(struct dma_buf *);

void dma_buf_vunmap(struct dma_buf *, void *vaddr);

#else



static inline struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
@@ -264,6 +269,15 @@ static inline int dma_buf_mmap(struct dma_buf *dmabuf, 
{

	return -ENODEV;

}



static inline void *dma_buf_vmap(struct dma_buf *dmabuf)

{

	return NULL;

}



static inline void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)

{

}

#endif /* CONFIG_DMA_SHARED_BUFFER */



#endif /* __DMA_BUF_H__ */