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[media] vb2: Provide helpers for mapping virtual addresses 

Provide simple helper functions to map virtual address range into an
array of pfns / pages.

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
This commit is contained in:
Jan Kara 2015-07-13 11:55:46 -03:00 committed by Mauro Carvalho Chehab
parent 8a677b6edd
commit 21fb0cb7ec
3 changed files with 64 additions and 0 deletions
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1
drivers/media/v4l2-core/Kconfig
View File

@ -84,6 +84,7 @@ config VIDEOBUF2_CORE
config VIDEOBUF2_MEMOPS
tristate
select FRAME_VECTOR
config VIDEOBUF2_DMA_CONTIG
tristate

58
drivers/media/v4l2-core/videobuf2-memops.c
View File

@ -136,6 +136,64 @@ int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size,
}
EXPORT_SYMBOL_GPL(vb2_get_contig_userptr);
/**
* vb2_create_framevec() - map virtual addresses to pfns
* @start: Virtual user address where we start mapping
* @length: Length of a range to map
* @write: Should we map for writing into the area
*
* This function allocates and fills in a vector with pfns corresponding to
* virtual address range passed in arguments. If pfns have corresponding pages,
* page references are also grabbed to pin pages in memory. The function
* returns pointer to the vector on success and error pointer in case of
* failure. Returned vector needs to be freed via vb2_destroy_pfnvec().
*/
struct frame_vector *vb2_create_framevec(unsigned long start,
unsigned long length,
bool write)
{
int ret;
unsigned long first, last;
unsigned long nr;
struct frame_vector *vec;
first = start >> PAGE_SHIFT;
last = (start + length - 1) >> PAGE_SHIFT;
nr = last - first + 1;
vec = frame_vector_create(nr);
if (!vec)
return ERR_PTR(-ENOMEM);
ret = get_vaddr_frames(start, nr, write, 1, vec);
if (ret < 0)
goto out_destroy;
/* We accept only complete set of PFNs */
if (ret != nr) {
ret = -EFAULT;
goto out_release;
}
return vec;
out_release:
put_vaddr_frames(vec);
out_destroy:
frame_vector_destroy(vec);
return ERR_PTR(ret);
}
EXPORT_SYMBOL(vb2_create_framevec);
/**
* vb2_destroy_framevec() - release vector of mapped pfns
* @vec: vector of pfns / pages to release
*
* This releases references to all pages in the vector @vec (if corresponding
* pfns are backed by pages) and frees the passed vector.
*/
void vb2_destroy_framevec(struct frame_vector *vec)
{
put_vaddr_frames(vec);
frame_vector_destroy(vec);
}
EXPORT_SYMBOL(vb2_destroy_framevec);
/**
* vb2_common_vm_open() - increase refcount of the vma
* @vma: virtual memory region for the mapping

5
include/media/videobuf2-memops.h
View File

@ -15,6 +15,7 @@
#define _MEDIA_VIDEOBUF2_MEMOPS_H
#include <media/videobuf2-core.h>
#include <linux/mm.h>
/**
* vb2_vmarea_handler - common vma refcount tracking handler
@ -36,5 +37,9 @@ int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size,
struct vm_area_struct *vb2_get_vma(struct vm_area_struct *vma);
void vb2_put_vma(struct vm_area_struct *vma);
struct frame_vector *vb2_create_framevec(unsigned long start,
unsigned long length,
bool write);
void vb2_destroy_framevec(struct frame_vector *vec);
#endif