rfnoc: lib: introduce ctrl-port interface and BFM

Original-commit: 886cf97ad5d494b20c6fff0a53113f6096d458c7

lib/rfnoc/utils/ctrlport_if_splitter.sv

@@ -0,0 +1,85 @@
+//
+// Copyright 2025 Ettus Research, a National Instruments Brand
+//
+// SPDX-License-Identifier: LGPL-3.0-or-later
+//
+// Module: ctrlport_if_splitter
+//
+// Description:
+//
+//  This block splits a single control-port interface into multiple. It is used
+//  when you have a single master that needs to access multiple slaves. For
+//  example, a NoC block where the registers are implemented in multiple
+//  submodules that must be read/written by a single NoC shell.
+//
+//  Note that this block does not do any address decoding, so the connected
+//  slaves must use non-overlapping address spaces.
+//
+//  This module takes the request received by its single slave interface and
+//  outputs it on all its master interfaces. In the opposite direction, it takes
+//  the responses received by its multiple master interfaces and combines them
+//  into a single response on its slave interface. This is done by using the ack
+//  bit of each response to mask the other bits of the response, then OR'ing all
+//  of the masked responses together onto a single response bus. This is valid
+//  because only one block is allowed to respond to a single request.
+//
+// Parameters:
+//
+//   NUM_SLAVES : The number of slaves you want to connect to a master.
+//
+
+
+module ctrlport_if_splitter #(
+  int NUM_SLAVES = 2
+) (
+  // Slave Interface
+  ctrlport_if.slave s_ctrlport,
+  // Master Interfaces
+  ctrlport_if.master m_ctrlport [NUM_SLAVES-1:0]
+);
+
+  import ctrlport_pkg::*;
+
+  generate
+    if (NUM_SLAVES == 1) begin : gen_no_split
+      assign m_ctrlport[0].req = s_ctrlport.req;
+      assign s_ctrlport.resp   = m_ctrlport[0].resp;
+    end else begin : gen_splitter
+      //---------------------------------------------------------------------------
+      // Split the requests among the slaves
+      //---------------------------------------------------------------------------
+      for (genvar i = 0; i < NUM_SLAVES; i++) begin : gen_split
+        // No special logic is required to split the requests from the master among
+        // multiple slaves.
+        assign m_ctrlport[i].req = s_ctrlport.req;
+      end
+
+      //---------------------------------------------------------------------------
+      // Decode the responses
+      //---------------------------------------------------------------------------
+      // Take the responses and mask them with their respective ack
+      ctrlport_response_t masked_resp [NUM_SLAVES-1:0];
+      for (genvar i = 0; i < NUM_SLAVES; i++) begin : gen_mask
+          assign masked_resp[i] = m_ctrlport[i].resp.ack ? m_ctrlport[i].resp : '0;
+      end
+
+      // Combine the masked responses by OR'ing them together
+      ctrlport_response_t combined_resp;
+      always_comb begin : response_combine
+        combined_resp = '0;
+        for (int i = 0; i < NUM_SLAVES; i++) begin : gen_or
+          combined_resp = combined_resp | masked_resp[i];
+        end
+      end
+
+      // Register the output to break combinatorial path
+      always_ff @(posedge s_ctrlport.clk) begin : response_reg
+        s_ctrlport.resp <= combined_resp;
+
+        if (s_ctrlport.rst) begin
+          s_ctrlport.resp.ack <= '0;
+        end
+      end
+    end
+  endgenerate
+endmodule