+struct legacy_ring {
+ struct intel_gt *gt;
+ u8 class;
+ u8 instance;
+};
+
+static int legacy_ring_idx(const struct legacy_ring *ring)
+{
+ static const struct {
+ u8 base, max;
+ } map[] = {
+ [RENDER_CLASS] = { RCS0, 1 },
+ [COPY_ENGINE_CLASS] = { BCS0, 1 },
+ [VIDEO_DECODE_CLASS] = { VCS0, I915_MAX_VCS },
+ [VIDEO_ENHANCEMENT_CLASS] = { VECS0, I915_MAX_VECS },
+ };
+
+ if (GEM_DEBUG_WARN_ON(ring->class >= ARRAY_SIZE(map)))
+ return -1;
+
+ if (GEM_DEBUG_WARN_ON(ring->instance >= map[ring->class].max))
+ return -1;
+
+ return map[ring->class].base + ring->instance;
+}
+
+static void add_legacy_ring(struct legacy_ring *ring,
+ struct intel_engine_cs *engine)
+{
+ int idx;
+
+ if (engine->gt != ring->gt || engine->class != ring->class) {
+ ring->gt = engine->gt;
+ ring->class = engine->class;
+ ring->instance = 0;
+ }
+
+ idx = legacy_ring_idx(ring);
+ if (unlikely(idx == -1))
+ return;
+
+ GEM_BUG_ON(idx >= ARRAY_SIZE(ring->gt->engine));
+ ring->gt->engine[idx] = engine;
+ ring->instance++;
+
+ engine->legacy_idx = idx;
+}
+