verilog/rtl/sram/sram_wb_wrapper.sv

//-----------------------------------------------------------------------------
// @file      sram_wb_wrapper.vhd
//
// @brief     This block is a wishbone wrapper for SRAM signal mapping
//
// @details   This wrapper gets signal from master if it is selected
//			  and convey to the SRAM module and vice versa.
//			  
// @author    Sukru Uzun <sukru.uzun@procenne.com>
// @date      10.03.2022
//
// @todo 	  SRAM signalization should be checked
// @warning	  SRAM signalization
//
// @project   https://github.com/Procenne-Digital-Design/secure-memory.git
//
// @revision :
//    0.1 - 10 March 2022, Sukru Uzun
//          initial version
//-----------------------------------------------------------------------------

module sram_wb_wrapper #(
    parameter SRAM_ADDR_WD    = 9,
    parameter SRAM_DATA_WD    = 32,
    parameter SRAM_ADDR_START = 9'h000,
    parameter SRAM_ADDR_END   = 9'h1F8)
    (
    input   logic                       rst_n,
    // Wishbone Interface
    input   logic                       wb_clk_i,  // System clock
    input   logic                       wb_cyc_i,  // strobe/request
    input   logic                       wb_stb_i,  // strobe/request
    input   logic [SRAM_ADDR_WD-1:0]    wb_adr_i,  // address
    input   logic                       wb_we_i,   // write
    input   logic [SRAM_DATA_WD-1:0]    wb_dat_i,  // data output
    input   logic [SRAM_DATA_WD/8-1:0]  wb_sel_i,  // byte enable
    output  wire  [SRAM_DATA_WD-1:0]    wb_dat_o,  // data input
    output  logic                       wb_ack_o   // acknowlegement
);

// Port A
wire                      sram_clk_a;
wire                      sram_csb_a;
wire [SRAM_ADDR_WD-1:0]   sram_addr_a;
wire [SRAM_DATA_WD-1:0]   sram_dout_a;

// Port B
wire                      sram_clk_b;
wire                      sram_csb_b;
wire                      sram_web_b;
wire [SRAM_DATA_WD/8-1:0] sram_mask_b;
wire [SRAM_ADDR_WD-1:0]   sram_addr_b;
wire [SRAM_DATA_WD-1:0]   sram_din_b;

// Memory Write Port
assign sram_clk_b  = wb_clk_i;
assign sram_csb_b  = !wb_stb_i;
assign sram_web_b  = !wb_we_i;
assign sram_mask_b = wb_sel_i;
assign sram_addr_b = wb_adr_i;
assign sram_din_b  = wb_dat_i;

// Memory Read Port
assign sram_clk_a  = wb_clk_i;
assign sram_csb_a  = (wb_stb_i == 1'b1 && wb_we_i == 1'b0 && wb_cyc_i == 1'b1) ? 1'b0 : 1'b1;
assign sram_addr_a = wb_adr_i;

assign wb_dat_o    = sram_dout_a;

sky130_sram_2kbyte_1rw1r_32x512_8 u_sram1_2kb(
`ifdef USE_POWER_PINS
    .vccd1 (vccd1), // User area 1 1.8V supply
    .vssd1 (vssd1), // User area 1 digital ground
`endif
    // Port 0: RW
    .clk0     (sram_clk_b),
    .csb0     (sram_csb_b),
    .web0     (sram_web_b),
    .wmask0   (sram_mask_b),
    .addr0    (sram_addr_b),
    .din0     (sram_din_b),
    .dout0    (),   // dont read from Port B
    // Port 1: R
    .clk1     (sram_clk_a),
    .csb1     (sram_csb_a),
    .addr1    (sram_addr_a),
    .dout1    (sram_dout_a)
);

// Generate once cycle delayed ACK to get the data from SRAM
always @(negedge rst_n or posedge wb_clk_i) 
begin
    if ( rst_n == 1'b0 )
    begin
        wb_ack_o <= 'h0;
    end else
    begin
        wb_ack_o <= (wb_stb_i == 1'b1) & (wb_cyc_i == 1'b1) & (wb_ack_o == 0);
    end
end

endmodule