lfsr: Add input and output enable parameters to LFSR module to remove dead code

Signed-off-by: Alex Forencich <alex@alexforencich.com>

src/eth/rtl/taxi_axis_baser_rx_64.sv

@@ -274,7 +274,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(1),
     .LFSR_FEED_FORWARD(0),
     .REVERSE(1),
-    .DATA_W(64)
+    .DATA_W(DATA_W),
+    .DATA_IN_EN(1'b1),
+    .DATA_OUT_EN(1'b0)
 )
 eth_crc (
     .data_in(input_data_d0),

src/eth/rtl/taxi_axis_baser_tx_64.sv

@@ -284,7 +284,9 @@ for (genvar n = 0; n < 8; n = n + 1) begin : crc
         .LFSR_GALOIS(1),
         .LFSR_FEED_FORWARD(0),
         .REVERSE(1),
-        .DATA_W(8*(n+1))
+        .DATA_W(8*(n+1)),
+        .DATA_IN_EN(1'b1),
+        .DATA_OUT_EN(1'b0)
     )
     eth_crc (
         .data_in(s_tdata_reg[0 +: 8*(n+1)]),

src/eth/rtl/taxi_axis_gmii_rx.sv

@@ -198,7 +198,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(1),
     .LFSR_FEED_FORWARD(0),
     .REVERSE(1),
-    .DATA_W(8)
+    .DATA_W(DATA_W),
+    .DATA_IN_EN(1'b1),
+    .DATA_OUT_EN(1'b0)
 )
 eth_crc_8 (
     .data_in(gmii_rxd_d0),

src/eth/rtl/taxi_axis_gmii_tx.sv

@@ -190,7 +190,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(1),
     .LFSR_FEED_FORWARD(0),
     .REVERSE(1),
-    .DATA_W(8)
+    .DATA_W(DATA_W),
+    .DATA_IN_EN(1'b1),
+    .DATA_OUT_EN(1'b0)
 )
 eth_crc_8 (
     .data_in(s_tdata_reg),

src/eth/rtl/taxi_axis_xgmii_rx_32.sv

@@ -206,7 +206,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(1),
     .LFSR_FEED_FORWARD(0),
     .REVERSE(1),
-    .DATA_W(32)
+    .DATA_W(DATA_W),
+    .DATA_IN_EN(1'b1),
+    .DATA_OUT_EN(1'b0)
 )
 eth_crc (
     .data_in(xgmii_rxd_d0),

src/eth/rtl/taxi_axis_xgmii_rx_64.sv

@@ -218,7 +218,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(1),
     .LFSR_FEED_FORWARD(0),
     .REVERSE(1),
-    .DATA_W(64)
+    .DATA_W(DATA_W),
+    .DATA_IN_EN(1'b1),
+    .DATA_OUT_EN(1'b0)
 )
 eth_crc (
     .data_in(xgmii_rxd_d0),

src/eth/rtl/taxi_axis_xgmii_tx_32.sv

@@ -208,7 +208,9 @@ for (genvar n = 0; n < 4; n = n + 1) begin : crc
         .LFSR_GALOIS(1),
         .LFSR_FEED_FORWARD(0),
         .REVERSE(1),
-        .DATA_W(8*(n+1))
+        .DATA_W(8*(n+1)),
+        .DATA_IN_EN(1'b1),
+        .DATA_OUT_EN(1'b0)
     )
     eth_crc (
         .data_in(s_tdata_reg[0 +: 8*(n+1)]),

src/eth/rtl/taxi_axis_xgmii_tx_64.sv

@@ -216,7 +216,9 @@ for (genvar n = 0; n < 8; n = n + 1) begin : crc
         .LFSR_GALOIS(1),
         .LFSR_FEED_FORWARD(0),
         .REVERSE(1),
-        .DATA_W(8*(n+1))
+        .DATA_W(8*(n+1)),
+        .DATA_IN_EN(1'b1),
+        .DATA_OUT_EN(1'b0)
     )
     eth_crc (
         .data_in(s_tdata_reg[0 +: 8*(n+1)]),

src/eth/rtl/taxi_eth_phy_10g_rx_if.sv

@@ -155,7 +155,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(0),
     .LFSR_FEED_FORWARD(1),
     .REVERSE(1),
-    .DATA_W(DATA_W)
+    .DATA_W(DATA_W),
+    .DATA_IN_EN(1'b1),
+    .DATA_OUT_EN(1'b1)
 )
 descrambler_inst (
     .data_in(serdes_rx_data_int),
@@ -176,7 +178,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(0),
     .LFSR_FEED_FORWARD(1),
     .REVERSE(1),
-    .DATA_W(DATA_W+HDR_W)
+    .DATA_W(DATA_W+HDR_W),
+    .DATA_IN_EN(1'b1),
+    .DATA_OUT_EN(1'b1)
 )
 prbs31_check_inst (
     .data_in(~{serdes_rx_data_int, serdes_rx_hdr_int}),

src/eth/rtl/taxi_eth_phy_10g_tx_if.sv

@@ -145,7 +145,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(0),
     .LFSR_FEED_FORWARD(0),
     .REVERSE(1),
-    .DATA_W(DATA_W)
+    .DATA_W(DATA_W),
+    .DATA_IN_EN(1'b1),
+    .DATA_OUT_EN(1'b1)
 )
 scrambler_inst (
     .data_in(encoded_tx_data),
@@ -166,7 +168,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(0),
     .LFSR_FEED_FORWARD(0),
     .REVERSE(1),
-    .DATA_W(DATA_W+HDR_W)
+    .DATA_W(DATA_W+HDR_W),
+    .DATA_IN_EN(1'b0),
+    .DATA_OUT_EN(1'b1)
 )
 prbs31_gen_inst (
     .data_in('0),

src/lfsr/rtl/taxi_lfsr.sv

@@ -27,8 +27,11 @@ module taxi_lfsr #
     parameter logic LFSR_FEED_FORWARD = 1'b0,
     // bit-reverse input and output
     parameter logic REVERSE = 1'b0,
-    // width of data input
+    // width of data ports
-    parameter DATA_W = 8
+    parameter DATA_W = 8,
+    // enable data input and output
+    parameter logic DATA_IN_EN = 1'b1,
+    parameter logic DATA_OUT_EN = 1'b1
 )
 (
     input  wire logic [DATA_W-1:0]  data_in,
@@ -170,7 +173,10 @@ PRBS31      Fibonacci, inverted     31      31'h10000001    any
 
 */
 
-function [LFSR_W+DATA_W-1:0][LFSR_W+DATA_W-1:0] lfsr_mask();
+localparam IN_W = LFSR_W+(DATA_IN_EN ? DATA_W : 0);
+localparam OUT_W = LFSR_W+(DATA_OUT_EN ? DATA_W : 0);
+
+function [OUT_W-1:0][IN_W-1:0] lfsr_mask();
     logic [LFSR_W-1:0] lfsr_mask_state[LFSR_W-1:0];
     logic [DATA_W-1:0] lfsr_mask_data[LFSR_W-1:0];
     logic [LFSR_W-1:0] output_mask_state[DATA_W-1:0];
@@ -270,42 +276,73 @@ function [LFSR_W+DATA_W-1:0][LFSR_W+DATA_W-1:0] lfsr_mask();
         end
     end
 
+    // disable broken linter
+    /* verilator lint_off WIDTH */
     if (REVERSE) begin
         // output reversed
         for (integer i = 0; i < LFSR_W; i = i + 1) begin
             for (integer j = 0; j < LFSR_W; j = j + 1) begin
                 lfsr_mask[i][j] = lfsr_mask_state[LFSR_W-i-1][LFSR_W-j-1];
             end
-            for (integer j = 0; j < DATA_W; j = j + 1) begin
+            if (DATA_IN_EN) begin
-                lfsr_mask[i][j+LFSR_W] = lfsr_mask_data[LFSR_W-i-1][DATA_W-j-1];
+                for (integer j = 0; j < DATA_W; j = j + 1) begin
+                    lfsr_mask[i][j+LFSR_W] = lfsr_mask_data[LFSR_W-i-1][DATA_W-j-1];
+                end
             end
         end
-        for (integer i = 0; i < DATA_W; i = i + 1) begin
+        if (DATA_OUT_EN) begin
-            for (integer j = 0; j < LFSR_W; j = j + 1) begin
+            for (integer i = 0; i < DATA_W; i = i + 1) begin
-                lfsr_mask[i+LFSR_W][j] = output_mask_state[DATA_W-i-1][LFSR_W-j-1];
+                for (integer j = 0; j < LFSR_W; j = j + 1) begin
-            end
+                    lfsr_mask[i+LFSR_W][j] = output_mask_state[DATA_W-i-1][LFSR_W-j-1];
-            for (integer j = 0; j < DATA_W; j = j + 1) begin
+                end
-                lfsr_mask[i+LFSR_W][j+LFSR_W] = output_mask_data[DATA_W-i-1][DATA_W-j-1];
+                if (DATA_IN_EN) begin
+                    for (integer j = 0; j < DATA_W; j = j + 1) begin
+                        lfsr_mask[i+LFSR_W][j+LFSR_W] = output_mask_data[DATA_W-i-1][DATA_W-j-1];
+                    end
+                end
             end
         end
     end else begin
         // output normal
         for (integer i = 0; i < LFSR_W; i = i + 1) begin
-            lfsr_mask[i] = {lfsr_mask_data[i], lfsr_mask_state[i]};
+            if (DATA_IN_EN) begin
+                lfsr_mask[i] = {lfsr_mask_data[i], lfsr_mask_state[i]};
+            end else begin
+                lfsr_mask[i] = lfsr_mask_state[i];
+            end
         end
-        for (integer i = 0; i < DATA_W; i = i + 1) begin
+        if (DATA_OUT_EN) begin
-            lfsr_mask[i+LFSR_W] = {output_mask_data[i], output_mask_state[i]};
+            for (integer i = 0; i < DATA_W; i = i + 1) begin
+                if (DATA_IN_EN) begin
+                    lfsr_mask[i+LFSR_W] = {output_mask_data[i], output_mask_state[i]};
+                end else begin
+                    lfsr_mask[i+LFSR_W] = output_mask_state[i];
+                end
+            end
         end
     end
+    /* verilator lint_on WIDTH */
 endfunction
 
-wire [LFSR_W+DATA_W-1:0][LFSR_W+DATA_W-1:0] mask = lfsr_mask();
+wire [OUT_W-1:0][IN_W-1:0] mask = lfsr_mask();
 
 for (genvar n = 0; n < LFSR_W; n = n + 1) begin : lfsr_state
-    assign state_out[n] = ^({data_in, state_in} & mask[n]);
+    if (DATA_IN_EN) begin
+        assign state_out[n] = ^({data_in, state_in} & mask[n]);
+    end else begin
+        assign state_out[n] = ^(state_in & mask[n]);
+    end
 end
-for (genvar n = 0; n < DATA_W; n = n + 1) begin : lfsr_data
+if (DATA_OUT_EN) begin
-    assign data_out[n] = ^({data_in, state_in} & mask[n+LFSR_W]);
+    for (genvar n = 0; n < DATA_W; n = n + 1) begin : lfsr_data
+        if (DATA_IN_EN) begin
+            assign data_out[n] = ^({data_in, state_in} & mask[n+LFSR_W]);
+        end else begin
+            assign data_out[n] = ^(state_in & mask[n+LFSR_W]);
+        end
+    end
+end else begin
+    assign data_out = '0;
 end
 
 endmodule

src/lfsr/rtl/taxi_lfsr_crc.sv

@@ -155,7 +155,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(LFSR_GALOIS),
     .LFSR_FEED_FORWARD('0),
     .REVERSE(REVERSE),
-    .DATA_W(DATA_W)
+    .DATA_W(DATA_W),
+    .DATA_IN_EN(1'b1),
+    .DATA_OUT_EN(1'b0)
 )
 lfsr_inst (
     .data_in(data_in),

src/lfsr/rtl/taxi_lfsr_descramble.sv

@@ -159,7 +159,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(LFSR_GALOIS),
     .LFSR_FEED_FORWARD('1),
     .REVERSE(REVERSE),
-    .DATA_W(DATA_W)
+    .DATA_W(DATA_W),
+    .DATA_IN_EN(1'b1),
+    .DATA_OUT_EN(1'b1)
 )
 lfsr_inst (
     .data_in(data_in),

src/lfsr/rtl/taxi_lfsr_prbs_check.sv

@@ -165,7 +165,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(LFSR_GALOIS),
     .LFSR_FEED_FORWARD('1),
     .REVERSE(REVERSE),
-    .DATA_W(DATA_W)
+    .DATA_W(DATA_W),
+    .DATA_IN_EN(1'b1),
+    .DATA_OUT_EN(1'b1)
 )
 lfsr_inst (
     .data_in(INVERT ? ~data_in : data_in),

src/lfsr/rtl/taxi_lfsr_prbs_gen.sv

@@ -159,7 +159,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(LFSR_GALOIS),
     .LFSR_FEED_FORWARD('0),
     .REVERSE(REVERSE),
-    .DATA_W(DATA_W)
+    .DATA_W(DATA_W),
+    .DATA_IN_EN(1'b0),
+    .DATA_OUT_EN(1'b1)
 )
 lfsr_inst (
     .data_in('0),

src/lfsr/rtl/taxi_lfsr_scramble.sv

@@ -159,7 +159,9 @@ taxi_lfsr #(
     .LFSR_GALOIS(LFSR_GALOIS),
     .LFSR_FEED_FORWARD('0),
     .REVERSE(REVERSE),
-    .DATA_W(DATA_W)
+    .DATA_W(DATA_W),
+    .DATA_IN_EN(1'b1),
+    .DATA_OUT_EN(1'b1)
 )
 lfsr_inst (
     .data_in(data_in),

src/lfsr/tb/taxi_lfsr/Makefile

@@ -35,6 +35,8 @@ export PARAM_LFSR_GALOIS ?= "1'b1"
 export PARAM_LFSR_FEED_FORWARD ?= "1'b0"
 export PARAM_REVERSE ?= "1'b1"
 export PARAM_DATA_W ?= 8
+export PARAM_DATA_IN_EN ?= "1'b1"
+export PARAM_DATA_OUT_EN ?= "1'b1"
 
 ifeq ($(SIM), icarus)
 	PLUSARGS += -fst

src/lfsr/tb/taxi_lfsr/test_taxi_lfsr.py

@@ -220,6 +220,8 @@ def test_taxi_lfsr(request, lfsr_w, lfsr_poly, lfsr_galois, reverse, data_w):
     parameters['LFSR_FEED_FORWARD'] = "1'b0"
     parameters['REVERSE'] = f"1'b{reverse}"
     parameters['DATA_W'] = data_w
+    parameters['DATA_IN_EN'] = "1'b1"
+    parameters['DATA_OUT_EN'] = "1'b1"
 
     extra_env = {f'PARAM_{k}': str(v) for k, v in parameters.items()}