diff --git a/example/common/rtl/axi_ram.v b/example/common/rtl/axi_ram.v new file mode 100644 index 000000000..7eea20315 --- /dev/null +++ b/example/common/rtl/axi_ram.v @@ -0,0 +1,373 @@ +/* + +Copyright (c) 2018 Alex Forencich + +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in +all copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +THE SOFTWARE. + +*/ + +// Language: Verilog 2001 + +`resetall +`timescale 1ns / 1ps +`default_nettype none + +/* + * AXI4 RAM + */ +module axi_ram # +( + // Width of data bus in bits + parameter DATA_WIDTH = 32, + // Width of address bus in bits + parameter ADDR_WIDTH = 16, + // Width of wstrb (width of data bus in words) + parameter STRB_WIDTH = (DATA_WIDTH/8), + // Width of ID signal + parameter ID_WIDTH = 8, + // Extra pipeline register on output + parameter PIPELINE_OUTPUT = 0 +) +( + input wire clk, + input wire rst, + + input wire [ID_WIDTH-1:0] s_axi_awid, + input wire [ADDR_WIDTH-1:0] s_axi_awaddr, + input wire [7:0] s_axi_awlen, + input wire [2:0] s_axi_awsize, + input wire [1:0] s_axi_awburst, + input wire s_axi_awlock, + input wire [3:0] s_axi_awcache, + input wire [2:0] s_axi_awprot, + input wire s_axi_awvalid, + output wire s_axi_awready, + input wire [DATA_WIDTH-1:0] s_axi_wdata, + input wire [STRB_WIDTH-1:0] s_axi_wstrb, + input wire s_axi_wlast, + input wire s_axi_wvalid, + output wire s_axi_wready, + output wire [ID_WIDTH-1:0] s_axi_bid, + output wire [1:0] s_axi_bresp, + output wire s_axi_bvalid, + input wire s_axi_bready, + input wire [ID_WIDTH-1:0] s_axi_arid, + input wire [ADDR_WIDTH-1:0] s_axi_araddr, + input wire [7:0] s_axi_arlen, + input wire [2:0] s_axi_arsize, + input wire [1:0] s_axi_arburst, + input wire s_axi_arlock, + input wire [3:0] s_axi_arcache, + input wire [2:0] s_axi_arprot, + input wire s_axi_arvalid, + output wire s_axi_arready, + output wire [ID_WIDTH-1:0] s_axi_rid, + output wire [DATA_WIDTH-1:0] s_axi_rdata, + output wire [1:0] s_axi_rresp, + output wire s_axi_rlast, + output wire s_axi_rvalid, + input wire s_axi_rready +); + +parameter VALID_ADDR_WIDTH = ADDR_WIDTH - $clog2(STRB_WIDTH); +parameter WORD_WIDTH = STRB_WIDTH; +parameter WORD_SIZE = DATA_WIDTH/WORD_WIDTH; + +// bus width assertions +initial begin + if (WORD_SIZE * STRB_WIDTH != DATA_WIDTH) begin + $error("Error: AXI data width not evenly divisble (instance %m)"); + $finish; + end + + if (2**$clog2(WORD_WIDTH) != WORD_WIDTH) begin + $error("Error: AXI word width must be even power of two (instance %m)"); + $finish; + end +end + +localparam [0:0] + READ_STATE_IDLE = 1'd0, + READ_STATE_BURST = 1'd1; + +reg [0:0] read_state_reg = READ_STATE_IDLE, read_state_next; + +localparam [1:0] + WRITE_STATE_IDLE = 2'd0, + WRITE_STATE_BURST = 2'd1, + WRITE_STATE_RESP = 2'd2; + +reg [1:0] write_state_reg = WRITE_STATE_IDLE, write_state_next; + +reg mem_wr_en; +reg mem_rd_en; + +reg [ID_WIDTH-1:0] read_id_reg = {ID_WIDTH{1'b0}}, read_id_next; +reg [ADDR_WIDTH-1:0] read_addr_reg = {ADDR_WIDTH{1'b0}}, read_addr_next; +reg [7:0] read_count_reg = 8'd0, read_count_next; +reg [2:0] read_size_reg = 3'd0, read_size_next; +reg [1:0] read_burst_reg = 2'd0, read_burst_next; +reg [ID_WIDTH-1:0] write_id_reg = {ID_WIDTH{1'b0}}, write_id_next; +reg [ADDR_WIDTH-1:0] write_addr_reg = {ADDR_WIDTH{1'b0}}, write_addr_next; +reg [7:0] write_count_reg = 8'd0, write_count_next; +reg [2:0] write_size_reg = 3'd0, write_size_next; +reg [1:0] write_burst_reg = 2'd0, write_burst_next; + +reg s_axi_awready_reg = 1'b0, s_axi_awready_next; +reg s_axi_wready_reg = 1'b0, s_axi_wready_next; +reg [ID_WIDTH-1:0] s_axi_bid_reg = {ID_WIDTH{1'b0}}, s_axi_bid_next; +reg s_axi_bvalid_reg = 1'b0, s_axi_bvalid_next; +reg s_axi_arready_reg = 1'b0, s_axi_arready_next; +reg [ID_WIDTH-1:0] s_axi_rid_reg = {ID_WIDTH{1'b0}}, s_axi_rid_next; +reg [DATA_WIDTH-1:0] s_axi_rdata_reg = {DATA_WIDTH{1'b0}}, s_axi_rdata_next; +reg s_axi_rlast_reg = 1'b0, s_axi_rlast_next; +reg s_axi_rvalid_reg = 1'b0, s_axi_rvalid_next; +reg [ID_WIDTH-1:0] s_axi_rid_pipe_reg = {ID_WIDTH{1'b0}}; +reg [DATA_WIDTH-1:0] s_axi_rdata_pipe_reg = {DATA_WIDTH{1'b0}}; +reg s_axi_rlast_pipe_reg = 1'b0; +reg s_axi_rvalid_pipe_reg = 1'b0; + +// (* RAM_STYLE="BLOCK" *) +reg [DATA_WIDTH-1:0] mem[(2**VALID_ADDR_WIDTH)-1:0]; + +wire [VALID_ADDR_WIDTH-1:0] s_axi_awaddr_valid = s_axi_awaddr >> (ADDR_WIDTH - VALID_ADDR_WIDTH); +wire [VALID_ADDR_WIDTH-1:0] s_axi_araddr_valid = s_axi_araddr >> (ADDR_WIDTH - VALID_ADDR_WIDTH); +wire [VALID_ADDR_WIDTH-1:0] read_addr_valid = read_addr_reg >> (ADDR_WIDTH - VALID_ADDR_WIDTH); +wire [VALID_ADDR_WIDTH-1:0] write_addr_valid = write_addr_reg >> (ADDR_WIDTH - VALID_ADDR_WIDTH); + +assign s_axi_awready = s_axi_awready_reg; +assign s_axi_wready = s_axi_wready_reg; +assign s_axi_bid = s_axi_bid_reg; +assign s_axi_bresp = 2'b00; +assign s_axi_bvalid = s_axi_bvalid_reg; +assign s_axi_arready = s_axi_arready_reg; +assign s_axi_rid = PIPELINE_OUTPUT ? s_axi_rid_pipe_reg : s_axi_rid_reg; +assign s_axi_rdata = PIPELINE_OUTPUT ? s_axi_rdata_pipe_reg : s_axi_rdata_reg; +assign s_axi_rresp = 2'b00; +assign s_axi_rlast = PIPELINE_OUTPUT ? s_axi_rlast_pipe_reg : s_axi_rlast_reg; +assign s_axi_rvalid = PIPELINE_OUTPUT ? s_axi_rvalid_pipe_reg : s_axi_rvalid_reg; + +integer i, j; + +initial begin + // two nested loops for smaller number of iterations per loop + // workaround for synthesizer complaints about large loop counts + for (i = 0; i < 2**VALID_ADDR_WIDTH; i = i + 2**(VALID_ADDR_WIDTH/2)) begin + for (j = i; j < i + 2**(VALID_ADDR_WIDTH/2); j = j + 1) begin + mem[j] = 0; + end + end +end + +always @* begin + write_state_next = WRITE_STATE_IDLE; + + mem_wr_en = 1'b0; + + write_id_next = write_id_reg; + write_addr_next = write_addr_reg; + write_count_next = write_count_reg; + write_size_next = write_size_reg; + write_burst_next = write_burst_reg; + + s_axi_awready_next = 1'b0; + s_axi_wready_next = 1'b0; + s_axi_bid_next = s_axi_bid_reg; + s_axi_bvalid_next = s_axi_bvalid_reg && !s_axi_bready; + + case (write_state_reg) + WRITE_STATE_IDLE: begin + s_axi_awready_next = 1'b1; + + if (s_axi_awready && s_axi_awvalid) begin + write_id_next = s_axi_awid; + write_addr_next = s_axi_awaddr; + write_count_next = s_axi_awlen; + write_size_next = s_axi_awsize < $clog2(STRB_WIDTH) ? s_axi_awsize : $clog2(STRB_WIDTH); + write_burst_next = s_axi_awburst; + + s_axi_awready_next = 1'b0; + s_axi_wready_next = 1'b1; + write_state_next = WRITE_STATE_BURST; + end else begin + write_state_next = WRITE_STATE_IDLE; + end + end + WRITE_STATE_BURST: begin + s_axi_wready_next = 1'b1; + + if (s_axi_wready && s_axi_wvalid) begin + mem_wr_en = 1'b1; + if (write_burst_reg != 2'b00) begin + write_addr_next = write_addr_reg + (1 << write_size_reg); + end + write_count_next = write_count_reg - 1; + if (write_count_reg > 0) begin + write_state_next = WRITE_STATE_BURST; + end else begin + s_axi_wready_next = 1'b0; + if (s_axi_bready || !s_axi_bvalid) begin + s_axi_bid_next = write_id_reg; + s_axi_bvalid_next = 1'b1; + s_axi_awready_next = 1'b1; + write_state_next = WRITE_STATE_IDLE; + end else begin + write_state_next = WRITE_STATE_RESP; + end + end + end else begin + write_state_next = WRITE_STATE_BURST; + end + end + WRITE_STATE_RESP: begin + if (s_axi_bready || !s_axi_bvalid) begin + s_axi_bid_next = write_id_reg; + s_axi_bvalid_next = 1'b1; + s_axi_awready_next = 1'b1; + write_state_next = WRITE_STATE_IDLE; + end else begin + write_state_next = WRITE_STATE_RESP; + end + end + endcase +end + +always @(posedge clk) begin + write_state_reg <= write_state_next; + + write_id_reg <= write_id_next; + write_addr_reg <= write_addr_next; + write_count_reg <= write_count_next; + write_size_reg <= write_size_next; + write_burst_reg <= write_burst_next; + + s_axi_awready_reg <= s_axi_awready_next; + s_axi_wready_reg <= s_axi_wready_next; + s_axi_bid_reg <= s_axi_bid_next; + s_axi_bvalid_reg <= s_axi_bvalid_next; + + for (i = 0; i < WORD_WIDTH; i = i + 1) begin + if (mem_wr_en & s_axi_wstrb[i]) begin + mem[write_addr_valid][WORD_SIZE*i +: WORD_SIZE] <= s_axi_wdata[WORD_SIZE*i +: WORD_SIZE]; + end + end + + if (rst) begin + write_state_reg <= WRITE_STATE_IDLE; + + s_axi_awready_reg <= 1'b0; + s_axi_wready_reg <= 1'b0; + s_axi_bvalid_reg <= 1'b0; + end +end + +always @* begin + read_state_next = READ_STATE_IDLE; + + mem_rd_en = 1'b0; + + s_axi_rid_next = s_axi_rid_reg; + s_axi_rlast_next = s_axi_rlast_reg; + s_axi_rvalid_next = s_axi_rvalid_reg && !(s_axi_rready || (PIPELINE_OUTPUT && !s_axi_rvalid_pipe_reg)); + + read_id_next = read_id_reg; + read_addr_next = read_addr_reg; + read_count_next = read_count_reg; + read_size_next = read_size_reg; + read_burst_next = read_burst_reg; + + s_axi_arready_next = 1'b0; + + case (read_state_reg) + READ_STATE_IDLE: begin + s_axi_arready_next = 1'b1; + + if (s_axi_arready && s_axi_arvalid) begin + read_id_next = s_axi_arid; + read_addr_next = s_axi_araddr; + read_count_next = s_axi_arlen; + read_size_next = s_axi_arsize < $clog2(STRB_WIDTH) ? s_axi_arsize : $clog2(STRB_WIDTH); + read_burst_next = s_axi_arburst; + + s_axi_arready_next = 1'b0; + read_state_next = READ_STATE_BURST; + end else begin + read_state_next = READ_STATE_IDLE; + end + end + READ_STATE_BURST: begin + if (s_axi_rready || (PIPELINE_OUTPUT && !s_axi_rvalid_pipe_reg) || !s_axi_rvalid_reg) begin + mem_rd_en = 1'b1; + s_axi_rvalid_next = 1'b1; + s_axi_rid_next = read_id_reg; + s_axi_rlast_next = read_count_reg == 0; + if (read_burst_reg != 2'b00) begin + read_addr_next = read_addr_reg + (1 << read_size_reg); + end + read_count_next = read_count_reg - 1; + if (read_count_reg > 0) begin + read_state_next = READ_STATE_BURST; + end else begin + s_axi_arready_next = 1'b1; + read_state_next = READ_STATE_IDLE; + end + end else begin + read_state_next = READ_STATE_BURST; + end + end + endcase +end + +always @(posedge clk) begin + read_state_reg <= read_state_next; + + read_id_reg <= read_id_next; + read_addr_reg <= read_addr_next; + read_count_reg <= read_count_next; + read_size_reg <= read_size_next; + read_burst_reg <= read_burst_next; + + s_axi_arready_reg <= s_axi_arready_next; + s_axi_rid_reg <= s_axi_rid_next; + s_axi_rlast_reg <= s_axi_rlast_next; + s_axi_rvalid_reg <= s_axi_rvalid_next; + + if (mem_rd_en) begin + s_axi_rdata_reg <= mem[read_addr_valid]; + end + + if (!s_axi_rvalid_pipe_reg || s_axi_rready) begin + s_axi_rid_pipe_reg <= s_axi_rid_reg; + s_axi_rdata_pipe_reg <= s_axi_rdata_reg; + s_axi_rlast_pipe_reg <= s_axi_rlast_reg; + s_axi_rvalid_pipe_reg <= s_axi_rvalid_reg; + end + + if (rst) begin + read_state_reg <= READ_STATE_IDLE; + + s_axi_arready_reg <= 1'b0; + s_axi_rvalid_reg <= 1'b0; + s_axi_rvalid_pipe_reg <= 1'b0; + end +end + +endmodule + +`resetall