Provide simple helper functions to map virtual address range into an
array of pfns.
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
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
--
2.1.4
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
