cvw/src/generic/clockgater.sv

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///////////////////////////////////////////
// clockgater.sv
//
// Written: Ross Thompson 9 January 2021
// Modified:
//
// Purpose: Clock gater model. Must use standard cell for synthesis.
//
// A component of the CORE-V-WALLY configurable RISC-V project.
//
// Copyright (C) 2021-23 Harvey Mudd College & Oklahoma State University
//
// SPDX-License-Identifier: Apache-2.0 WITH SHL-2.1
//
// Licensed under the Solderpad Hardware License v 2.1 (the “License”); you may not use this file
// except in compliance with the License, or, at your option, the Apache License version 2.0. You
// may obtain a copy of the License at
//
// https://solderpad.org/licenses/SHL-2.1/
//
// Unless required by applicable law or agreed to in writing, any work 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.
////////////////////////////////////////////////////////////////////////////////////////////////
module clockgater #(parameter FPGA) (
input logic E,
input logic SE,
input logic CLK,
output logic ECLK
);
if (FPGA) BUFGCE bufgce_i0 (.I(CLK), .CE(E | SE), .O(ECLK));
else begin
// *** BUG
// VERY IMPORTANT.
// This part functionally models a clock gater, but does not necessarily meet the timing constrains a real standard cell would.
// Do not use this in synthesis!
logic enable_q;
always_latch begin
if(~CLK) begin
enable_q <= E | SE;
end
end
assign ECLK = enable_q & CLK;
end
endmodule