tillitis-key/hw/application_fpga/rtl/fw_ram.v
2022-11-09 15:05:03 +01:00

111 lines
2.9 KiB
Verilog

//======================================================================
//
// fw_ram.v
// --------
// A small 512 x 32 RAM for FW use. With support for access control.
//
// Author: Joachim Strombergson
// Copyright (C) 2022 - Tillitis AB
// SPDX-License-Identifier: GPL-2.0-only
//
//======================================================================
`default_nettype none
module fw_ram(
input wire clk,
input wire reset_n,
input wire fw_app_mode,
input wire cs,
input wire [3 : 0] we,
input wire [7 : 0] address,
input wire [31 : 0] write_data,
output wire [31 : 0] read_data,
output wire ready
);
//----------------------------------------------------------------
// Registers and wires.
//----------------------------------------------------------------
reg [31 : 0] tmp_read_data;
reg [31 : 0] mem_read_data;
reg ready_reg;
reg fw_app_cs;
//----------------------------------------------------------------
// Concurrent assignment of ports.
//----------------------------------------------------------------
assign read_data = tmp_read_data;
assign ready = ready_reg;
assign fw_app_cs = cs && ~fw_app_mode;
//----------------------------------------------------------------
// Block RAM instances.
//----------------------------------------------------------------
SB_RAM40_4K fw_ram0(
.RDATA(mem_read_data[15 : 0]),
.RADDR({3'h0, address}),
.RCLK(clk),
.RCLKE(1'h1),
.RE(fw_app_cs),
.WADDR({3'h0, address}),
.WCLK(clk),
.WCLKE(1'h1),
.WDATA(write_data[15 : 0]),
.WE((|we && fw_app_cs)),
.MASK({{8{~we[1]}}, {8{~we[0]}}})
);
SB_RAM40_4K fw_ram1(
.RDATA(mem_read_data[31 : 16]),
.RADDR({3'h0, address}),
.RCLK(clk),
.RCLKE(1'h1),
.RE(fw_app_cs),
.WADDR({3'h0, address}),
.WCLK(clk),
.WCLKE(1'h1),
.WDATA(write_data[31 : 16]),
.WE((|we && fw_app_cs)),
.MASK({{8{~we[3]}}, {8{~we[2]}}})
);
//----------------------------------------------------------------
// reg_update
//----------------------------------------------------------------
always @(posedge clk)
begin : reg_update
if (!reset_n) begin
ready_reg <= 1'h0;
end
else begin
ready_reg <= cs;
end
end
//----------------------------------------------------------------
// read_mux
//----------------------------------------------------------------
always @*
begin : read_mux;
if (fw_app_cs) begin
tmp_read_data = mem_read_data;
end else begin
tmp_read_data = 32'h0;
end
end
endmodule // fw_ram
//======================================================================
// EOF fw_ram.v
//======================================================================