Support FP4 gemm (1/2) (#3899)

sgl-kernel/csrc/gemm/nvfp4_scaled_mm_entry.cu

@@ -0,0 +1,39 @@
+/* Copyright 2025 SGLang Team. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+==============================================================================*/
+
+#include <torch/all.h>
+
+#if defined ENABLE_NVFP4 && ENABLE_NVFP4
+void cutlass_scaled_fp4_mm_sm100a(
+    torch::Tensor& D,
+    torch::Tensor const& A,
+    torch::Tensor const& B,
+    torch::Tensor const& A_sf,
+    torch::Tensor const& B_sf,
+    torch::Tensor const& alpha);
+#endif
+
+void cutlass_scaled_fp4_mm(
+    torch::Tensor& D,
+    torch::Tensor const& A,
+    torch::Tensor const& B,
+    torch::Tensor const& A_sf,
+    torch::Tensor const& B_sf,
+    torch::Tensor const& alpha) {
+#if defined ENABLE_NVFP4 && ENABLE_NVFP4
+  return cutlass_scaled_fp4_mm_sm100a(D, A, B, A_sf, B_sf, alpha);
+#endif
+  TORCH_CHECK_NOT_IMPLEMENTED(false, "No compiled nvfp4 mm kernel.");
+}