Provide simple helper functions to map virtual address range into an array of pfns.
Signed-off-by: Jan Kara jack@suse.cz --- drivers/media/v4l2-core/videobuf2-memops.c | 57 ++++++++++++++++++++++++++++++ include/media/videobuf2-memops.h | 4 +++ 2 files changed, 61 insertions(+)
diff --git a/drivers/media/v4l2-core/videobuf2-memops.c b/drivers/media/v4l2-core/videobuf2-memops.c index 81c1ad8b2cf1..80ade22b920c 100644 --- a/drivers/media/v4l2-core/videobuf2-memops.c +++ b/drivers/media/v4l2-core/videobuf2-memops.c @@ -137,6 +137,63 @@ int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size, EXPORT_SYMBOL_GPL(vb2_get_contig_userptr);
/** + * vb2_create_pfnvec() - 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 pinned_pfns *vb2_create_pfnvec(unsigned long start, unsigned long length, + bool write) +{ + int ret; + unsigned long first, last; + unsigned long nr; + struct pinned_pfns *pfns; + + first = start >> PAGE_SHIFT; + last = (start + length - 1) >> PAGE_SHIFT; + nr = last - first + 1; + pfns = pfns_vector_create(nr); + if (!pfns) + return ERR_PTR(-ENOMEM); + ret = get_vaddr_pfns(start, nr, write, 1, pfns); + if (ret < 0) + goto out_destroy; + /* We accept only complete set of PFNs */ + if (ret != nr) { + ret = -EFAULT; + goto out_release; + } + return pfns; +out_release: + put_vaddr_pfns(pfns); +out_destroy: + pfns_vector_destroy(pfns); + return ERR_PTR(ret); +} +EXPORT_SYMBOL(vb2_create_pfnvec); + +/** + * vb2_destroy_pfnvec() - release vector of mapped pfns + * @pfns: vector of pfns to release + * + * This releases references to all pages in the vector @pfns (if corresponding + * pfns are backed by pages) and frees the passed vector. + */ +void vb2_destroy_pfnvec(struct pinned_pfns *pfns) +{ + put_vaddr_pfns(pfns); + pfns_vector_destroy(pfns); +} +EXPORT_SYMBOL(vb2_destroy_pfnvec); + +/** * vb2_common_vm_open() - increase refcount of the vma * @vma: virtual memory region for the mapping * diff --git a/include/media/videobuf2-memops.h b/include/media/videobuf2-memops.h index f05444ca8c0c..868f9c1cd92d 100644 --- a/include/media/videobuf2-memops.h +++ b/include/media/videobuf2-memops.h @@ -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 +37,8 @@ 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 pinned_pfns *vb2_create_pfnvec(unsigned long start, unsigned long length, + bool write); +void vb2_destroy_pfnvec(struct pinned_pfns *pfns);
#endif