[PATCH 4/9] vb2: Provide helpers for mapping virtual addresses

Jan Kara
2015-05-13T13:08:30Z

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

Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
drivers/media/v4l2-core/videobuf2-memops.c | 58 ++++++++++++++++++++++++++++++
include/media/videobuf2-memops.h | 5 +++
2 files changed, 63 insertions(+)

diff --git a/drivers/media/v4l2-core/videobuf2-memops.c b/drivers/media/v4l2-core/videobuf2-memops.c
index 81c1ad8b2cf1..0ec186d41b9b 100644
--- a/drivers/media/v4l2-core/videobuf2-memops.c
+++ b/drivers/media/v4l2-core/videobuf2-memops.c
@@ -137,6 +137,64 @@ 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
*
diff --git a/include/media/videobuf2-memops.h b/include/media/videobuf2-memops.h
index f05444ca8c0c..2f0564ff5f31 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 +37,9 @@ 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
--
2.1.4