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//
// 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
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