drm/amdgpu: move ring_from_fence to common code

Going to need that elsewhere as well.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
index b2df348..78e9b0f 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
@@ -436,6 +436,30 @@
 	}
 }
 
+/**
+ * amdgpu_ring_from_fence - get ring from fence
+ *
+ * @f: fence structure
+ *
+ * Extract the ring a fence belongs to. Handles both scheduler as
+ * well as hardware fences.
+ */
+struct amdgpu_ring *amdgpu_ring_from_fence(struct fence *f)
+{
+	struct amdgpu_fence *a_fence;
+	struct amd_sched_fence *s_fence;
+
+	s_fence = to_amd_sched_fence(f);
+	if (s_fence)
+		return container_of(s_fence->sched, struct amdgpu_ring, sched);
+
+	a_fence = to_amdgpu_fence(f);
+	if (a_fence)
+		return a_fence->ring;
+
+	return NULL;
+}
+
 /*
  * Debugfs info
  */