diff --git a/gbm.h b/gbm.h
index 8ec9349..cc36b72 100644
--- a/gbm.h
+++ b/gbm.h
@@ -275,6 +275,41 @@
 gbm_bo_import(struct gbm_device *gbm, uint32_t type,
               void *buffer, uint32_t usage);
 
+/**
+ * Flags to indicate the type of mapping for the buffer - these are
+ * passed into gbm_bo_map(). The caller must set the union of all the
+ * flags that are appropriate.
+ *
+ * These flags are independent of the GBM_BO_USE_* creation flags. However,
+ * mapping the buffer may require copying to/from a staging buffer.
+ *
+ * See also: pipe_transfer_usage
+ */
+enum gbm_bo_transfer_flags {
+   /**
+    * Buffer contents read back (or accessed directly) at transfer
+    * create time.
+    */
+   GBM_BO_TRANSFER_READ       = (1 << 0),
+   /**
+    * Buffer contents will be written back at unmap time
+    * (or modified as a result of being accessed directly).
+    */
+   GBM_BO_TRANSFER_WRITE      = (1 << 1),
+   /**
+    * Read/modify/write
+    */
+   GBM_BO_TRANSFER_READ_WRITE = (GBM_BO_TRANSFER_READ | GBM_BO_TRANSFER_WRITE),
+};
+
+void *
+gbm_bo_map(struct gbm_bo *bo,
+           uint32_t x, uint32_t y, uint32_t width, uint32_t height,
+           uint32_t flags, uint32_t *stride, void **map_data, size_t plane);
+
+void
+gbm_bo_unmap(struct gbm_bo *bo, void *map_data);
+
 uint32_t
 gbm_bo_get_width(struct gbm_bo *bo);