1 files changed, 47 insertions, 1 deletions

diff --git a/drivers/media/video/uvc/uvc_ctrl.c b/drivers/media/video/uvc/uvc_ctrl.c
index f169f7736677..59f8a9ad3796 100644
--- a/drivers/media/video/uvc/uvc_ctrl.c
+++ b/drivers/media/video/uvc/uvc_ctrl.c
@@ -785,7 +785,7 @@ static void __uvc_find_control(struct uvc_entity *entity, __u32 v4l2_id,
         }
 }
 
-struct uvc_control *uvc_find_control(struct uvc_video_chain *chain,
+static struct uvc_control *uvc_find_control(struct uvc_video_chain *chain,
         __u32 v4l2_id, struct uvc_control_mapping **mapping)
 {
         struct uvc_control *ctrl = NULL;
@@ -944,6 +944,52 @@ done:
         return ret;
 }
 
+/*
+ * Mapping V4L2 controls to UVC controls can be straighforward if done well.
+ * Most of the UVC controls exist in V4L2, and can be mapped directly. Some
+ * must be grouped (for instance the Red Balance, Blue Balance and Do White
+ * Balance V4L2 controls use the White Balance Component UVC control) or
+ * otherwise translated. The approach we take here is to use a translation
+ * table for the controls that can be mapped directly, and handle the others
+ * manually.
+ */
+int uvc_query_v4l2_menu(struct uvc_video_chain *chain,
+        struct v4l2_querymenu *query_menu)
+{
+        struct uvc_menu_info *menu_info;
+        struct uvc_control_mapping *mapping;
+        struct uvc_control *ctrl;
+        u32 index = query_menu->index;
+        u32 id = query_menu->id;
+        int ret;
+
+        memset(query_menu, 0, sizeof(*query_menu));
+        query_menu->id = id;
+        query_menu->index = index;
+
+        ret = mutex_lock_interruptible(&chain->ctrl_mutex);
+        if (ret < 0)
+                return -ERESTARTSYS;
+
+        ctrl = uvc_find_control(chain, query_menu->id, &mapping);
+        if (ctrl == NULL || mapping->v4l2_type != V4L2_CTRL_TYPE_MENU) {
+                ret = -EINVAL;
+                goto done;
+        }
+
+        if (query_menu->index >= mapping->menu_count) {
+                ret = -EINVAL;
+                goto done;
+        }
+
+        menu_info = &mapping->menu_info[query_menu->index];
+        strlcpy(query_menu->name, menu_info->name, sizeof query_menu->name);
+
+done:
+        mutex_unlock(&chain->ctrl_mutex);
+        return ret;
+}
+
 
 /* --------------------------------------------------------------------------
  * Control transactions