WIP: add WISHBONE testbench

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>

1 files changed, 346 insertions, 0 deletions

diff --git a/testbench_wb.v b/testbench_wb.v
new file mode 100644
index 0000000..eee3040
--- /dev/null
+++ b/testbench_wb.v
@@ -0,0 +1,346 @@
+`timescale 1 ns / 1 ps
+
+`ifndef VERILATOR
+module testbench #(
+	parameter VERBOSE = 0
+);
+	reg clk = 1;
+	reg resetn = 1;
+	wire trap;
+
+	always #5 clk = ~clk;
+
+	initial begin
+		repeat (100) @(posedge clk);
+		resetn <= 0;
+	end
+
+	initial begin
+		if ($test$plusargs("vcd")) begin
+			$dumpfile("testbench_wb.vcd");
+			$dumpvars(0, testbench);
+		end
+		repeat (1000000) @(posedge clk);
+		$display("TIMEOUT");
+		$finish;
+	end
+
+	wire trace_valid;
+	wire [35:0] trace_data;
+	integer trace_file;
+
+	initial begin
+		if ($test$plusargs("trace")) begin
+			trace_file = $fopen("testbench.trace", "w");
+			repeat (10) @(posedge clk);
+			while (!trap) begin
+				@(posedge clk);
+				if (trace_valid)
+					$fwrite(trace_file, "%x\n", trace_data);
+			end
+			$fclose(trace_file);
+			$display("Finished writing testbench.trace.");
+		end
+	end
+
+	picorv32_wrapper #(
+		.VERBOSE (VERBOSE)
+	) top (
+		.wb_clk(clk),
+		.wb_rst(resetn),
+		.trap(trap),
+		.trace_valid(trace_valid),
+		.trace_data(trace_data)
+	);
+endmodule
+`endif
+
+module picorv32_wrapper #(
+	parameter BOOTROM_MEMFILE = "",
+	parameter BOOTROM_MEMDEPTH = 16384 * 4,
+	parameter VERBOSE = 0
+) (
+	input wb_clk,
+	input wb_rst,
+	output trap,
+	output trace_valid,
+	output [35:0] trace_data
+);
+	wire tests_passed;
+	reg [31:0] irq;
+
+	always @* begin
+		irq = 0;
+		irq[4] = &uut.picorv32_core.count_cycle[12:0];
+		irq[5] = &uut.picorv32_core.count_cycle[15:0];
+	end
+
+wire [31:0] wb_m2s_adr;
+wire [31:0] wb_m2s_dat;
+wire [3:0] wb_m2s_sel;
+wire wb_m2s_we;
+wire wb_m2s_cyc;
+wire wb_m2s_stb;
+//wire [2:0] wb_m2s_cti;
+reg [2:0] wb_m2s_cti = 3'b000;
+wire [1:0] wb_m2s_bte;
+wire [31:0] wb_s2m_dat;
+wire wb_s2m_ack;
+wire wb_s2m_err;
+wire wb_s2m_rty;
+
+	wb_ram #(
+		.depth (16384 * 4),
+		.memfile ("firmware/firmware.hex"),
+		.VERBOSE (VERBOSE)
+	)
+	ram (// Wishbone interface
+		.wb_clk_i(wb_clk),
+		.wb_rst_i(wb_rst),
+
+		.wb_adr_i(wb_m2s_adr),
+		.wb_dat_i(wb_m2s_dat),
+		.wb_stb_i(wb_m2s_stb),
+		.wb_cyc_i(wb_m2s_cyc),
+		.wb_dat_o(wb_s2m_dat),
+		.wb_ack_o(wb_s2m_ack),
+		.wb_sel_i(wb_m2s_sel),
+		.wb_cti_i(wb_m2s_cti),
+		.wb_bte_i(wb_m2s_bte),
+		.wb_we_i(wb_m2s_we),
+		.wb_err_o(),
+
+		.tests_passed(tests_passed)
+		);
+
+	picorv32_wb #(
+`ifndef SYNTH_TEST
+`ifdef SP_TEST
+		.ENABLE_REGS_DUALPORT(0),
+`endif
+`ifdef COMPRESSED_ISA
+		.COMPRESSED_ISA(1),
+`endif
+		.ENABLE_MUL(1),
+		.ENABLE_DIV(1),
+		.ENABLE_IRQ(1),
+		.ENABLE_TRACE(1)
+`endif
+	) uut (
+		.trap (trap),
+		.irq (irq),
+		.trace_valid (trace_valid),
+		.trace_data (trace_data),
+
+		.wb_clk_i(wb_clk),
+		.wb_rst_i(wb_rst),
+
+		.wbm_adr_o(wb_m2s_adr),
+		.wbm_dat_i(wb_s2m_dat),
+		.wbm_stb_o(wb_m2s_stb),
+		.wbm_ack_i(wb_s2m_ack),
+		.wbm_cyc_o(wb_m2s_cyc),
+		.wbm_dat_o(wb_m2s_dat),
+		.wbm_we_o(wb_m2s_we),
+		.wbm_sel_o(wb_m2s_sel)
+	);
+
+	integer cycle_counter;
+	always @(posedge wb_clk) begin
+		cycle_counter <= !wb_rst ? cycle_counter + 1 : 0;
+		if (!wb_rst && trap) begin
+`ifndef VERILATOR
+			repeat (10) @(posedge wb_clk);
+`endif
+			$display("TRAP after %1d clock cycles", cycle_counter);
+			if (tests_passed) begin
+				$display("ALL TESTS PASSED.");
+				$finish;
+			end else begin
+				$display("ERROR!");
+				if ($test$plusargs("noerror"))
+					$finish;
+				$stop;
+			end
+		end
+	end
+endmodule
+
+module wb_ram
+	#(//Wishbone parameters
+		parameter dw = 32,
+		//Memory parameters
+		parameter depth = 256,
+		parameter aw = 32,
+		parameter memfile = "",
+		parameter VERBOSE = 0
+	)
+	(
+		input wb_clk_i,
+		input wb_rst_i,
+
+		input [aw-1:0] wb_adr_i,
+		input [dw-1:0] wb_dat_i,
+		input [3:0] wb_sel_i,
+		input wb_we_i,
+		input [1:0] wb_bte_i,
+		input [2:0] wb_cti_i,
+		input wb_cyc_i,
+		input wb_stb_i,
+
+		output reg wb_ack_o,
+		output wb_err_o,
+		output reg [dw-1:0] wb_dat_o,
+
+		output reg tests_passed
+	);
+
+	localparam CLASSIC_CYCLE = 1'b0;
+	localparam BURST_CYCLE   = 1'b1;
+
+	localparam READ  = 1'b0;
+	localparam WRITE = 1'b1;
+
+	localparam [2:0]
+		CTI_CLASSIC      = 3'b000,
+		CTI_CONST_BURST  = 3'b001,
+		CTI_INC_BURST    = 3'b010,
+		CTI_END_OF_BURST = 3'b111;
+
+	localparam [1:0]
+		BTE_LINEAR  = 2'd0,
+		BTE_WRAP_4  = 2'd1,
+		BTE_WRAP_8  = 2'd2,
+		BTE_WRAP_16 = 2'd3;
+
+	function wb_is_last;
+	input [2:0] cti;
+	begin
+		case (cti)
+		CTI_CLASSIC      : wb_is_last = 1'b1;
+		CTI_CONST_BURST  : wb_is_last = 1'b0;
+		CTI_INC_BURST    : wb_is_last = 1'b0;
+		CTI_END_OF_BURST : wb_is_last = 1'b1;
+		default : $display("%d : Illegal Wishbone B3 cycle type (%b)", $time, cti);
+		endcase
+	end
+	endfunction
+
+	function [31:0] wb_next_adr;
+	input [31:0] adr_i;
+	input [2:0] cti_i;
+	input [2:0] bte_i;
+	input integer dw;
+
+	reg [31:0] adr;
+	integer shift;
+	begin
+		shift = $clog2(dw/8);
+		adr = adr_i >> shift;
+		if (cti_i == CTI_INC_BURST)
+			case (bte_i)
+			BTE_LINEAR   : adr = adr + 1;
+			BTE_WRAP_4   : adr = {adr[31:2], adr[1:0]+2'd1};
+			BTE_WRAP_8   : adr = {adr[31:3], adr[2:0]+3'd1};
+			BTE_WRAP_16  : adr = {adr[31:4], adr[3:0]+4'd1};
+			endcase // case (burst_type_i)
+
+		wb_next_adr = adr << shift;
+	end
+endfunction
+
+	reg verbose;
+	initial verbose = $test$plusargs("verbose") || VERBOSE;
+
+	initial tests_passed = 0;
+
+	reg [aw-1:0] adr_r;
+	wire [aw-1:0] next_adr;
+	wire valid = wb_cyc_i & wb_stb_i;
+	reg valid_r;
+	reg is_last_r;
+
+	always @(posedge wb_clk_i)
+		is_last_r <= wb_is_last(wb_cti_i);
+
+	wire new_cycle = (valid & !valid_r) | is_last_r;
+
+	assign next_adr = wb_next_adr(adr_r, wb_cti_i, wb_bte_i, dw);
+
+	wire [aw-1:0] adr = new_cycle ? wb_adr_i : next_adr;
+
+	always @(posedge wb_clk_i)
+	begin
+		adr_r <= adr;
+		valid_r <= valid;
+		// Ack generation
+		wb_ack_o <= valid & (!((wb_cti_i == 3'b000) | (wb_cti_i == 3'b111)) | !wb_ack_o);
+		if (wb_rst_i)
+		begin
+			adr_r <= {aw{1'b0}};
+			valid_r <= 1'b0;
+			wb_ack_o <= 1'b0;
+		end
+	end
+
+	wire ram_we = wb_we_i & valid & wb_ack_o;
+
+	assign wb_err_o = 1'b0;
+
+	wire [aw-1:0] waddr = adr_r[aw-1:2];
+	wire [aw-1:0] raddr = adr[aw-1:2];
+	wire [3:0] we = {4{ram_we}} & wb_sel_i;
+
+	wire [$clog2(depth/4)-1:0] raddr2 = raddr[$clog2(depth/4)-1:0];
+	wire [$clog2(depth/4)-1:0] waddr2 = waddr[$clog2(depth/4)-1:0];
+
+	reg [31:0] mem [0:depth/4-1] /* verilator public */;
+
+	always @(posedge wb_clk_i) begin
+		if (adr_r[aw-1:0] == 32'h1000_0000 && wb_stb_i && !wb_ack_o)
+		begin
+			$write("%c", wb_dat_i[7:0]);
+		end else
+		if (adr_r[aw-1:0] == 32'h2000_0000 && wb_stb_i && !wb_ack_o) begin
+			if (wb_dat_i[31:0] == 123456789)
+				tests_passed = 1;
+		end
+	end
+
+	always @(posedge wb_clk_i) begin
+
+		if (waddr2 < 64 * 1024 / 4)
+		begin
+			if (we[0])
+				mem[waddr2][7:0] <= wb_dat_i[7:0];
+
+			if (we[1])
+				mem[waddr2][15:8] <= wb_dat_i[15:8];
+
+			if (we[2])
+				mem[waddr2][23:16] <= wb_dat_i[23:16];
+
+			if (we[3])
+				mem[waddr2][31:24] <= wb_dat_i[31:24];
+
+			if (ram_we)
+				if (verbose)
+					$display("WR: ADDR=%08x DATA=%08x STRB=%04b",
+						adr_r, wb_dat_i, we);
+		end
+
+		if (valid & wb_ack_o & !ram_we)
+			if (verbose)
+				$display("RD: ADDR=%08x DATA=%08x%s", adr_r, mem[raddr2], 0 ? " INSN" : "");
+
+		wb_dat_o <= mem[raddr2];
+	end
+
+	generate
+		initial
+		if (memfile != "") begin
+			$readmemh(memfile, mem);
+		end
+	endgenerate
+
+endmodule