drm/mode: Add user blob-creation ioctl

Add an ioctl which allows users to create blob properties from supplied
data. Currently this only supports modes, creating a drm_display_mode from
the userspace drm_mode_modeinfo.

v2: Removed size/type checks.
    Rebased on new patches to allow error propagation from create_blob,
    as well as avoiding double-allocation.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@intel.com>
Tested-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index dbeba94..359107a 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -558,4 +558,24 @@
 	__u64 user_data;
 };
 
+/**
+ * Create a new 'blob' data property, copying length bytes from data pointer,
+ * and returning new blob ID.
+ */
+struct drm_mode_create_blob {
+	/** Pointer to data to copy. */
+	__u64 data;
+	/** Length of data to copy. */
+	__u32 length;
+	/** Return: new property ID. */
+	__u32 blob_id;
+};
+
+/**
+ * Destroy a user-created blob property.
+ */
+struct drm_mode_destroy_blob {
+	__u32 blob_id;
+};
+
 #endif