feat: implement XPI output-enable isolation test and add related testbench

rtl/ip/rib/storage/xpi_core.sv

@@ -77,6 +77,7 @@ module xpi_core (
   logic s_xfer_condi, s_xfer_sta_trg, s_xfer_end_trg;
   logic s_dma_xfer_start, s_dma_xfer_trg;
   logic [7:0] s_dma_xfer_datlen;
+  logic [3:0] s_xpi_io_oe, s_xpi_io_do;
 
 
   assign xpi.sck_o = s_sclk;
@@ -85,6 +86,8 @@ module xpi_core (
     xpi.nss_o[nss_i] = s_nss_q;
   end
   assign xpi.irq_o     = '0;
+  assign xpi.io_oe_o   = s_xpi_io_oe;
+  assign xpi.io_do_o   = s_xpi_io_do;
   assign tx_data_req_o = s_tx_data_req_q;
   assign rx_data_req_o = s_rx_data_req_q;
 
@@ -122,6 +125,82 @@ module xpi_core (
   );
 
 
+  // Keep pad drive independent from the receive-data path. This preserves the
+  // bidirectional pad readback model without creating an input-to-output loop.
+  always_comb begin
+    s_xpi_io_oe    = '0;
+    s_xpi_io_oe[0] = 1'b1;
+    s_xpi_io_do    = '0;
+    unique case (s_fsm_q)
+      FSM_CMD: begin
+        unique case (cmdtyp_i)
+          `XPI_TYPE_SNGL: begin
+            s_xpi_io_oe[0] = 1'b1;
+            s_xpi_io_do[0] = s_xfer_data_q[31];
+          end
+          `XPI_TYPE_DUAL: begin
+            s_xpi_io_oe[1:0] = 2'b11;
+            s_xpi_io_do[1:0] = s_xfer_data_q[31:30];
+          end
+          `XPI_TYPE_QUAD: begin
+            s_xpi_io_oe[3:0] = 4'b1111;
+            s_xpi_io_do[3:0] = s_xfer_data_q[31:28];
+          end
+          default: begin
+            s_xpi_io_oe[0] = 1'b1;
+            s_xpi_io_do[0] = s_xfer_data_q[31];
+          end
+        endcase
+      end
+      FSM_ADDR: begin
+        unique case (adrtyp_i)
+          `XPI_TYPE_SNGL: begin
+            s_xpi_io_oe[0] = 1'b1;
+            s_xpi_io_do[0] = s_xfer_data_q[31];
+          end
+          `XPI_TYPE_DUAL: begin
+            s_xpi_io_oe[1:0] = 2'b11;
+            s_xpi_io_do[1:0] = s_xfer_data_q[31:30];
+          end
+          `XPI_TYPE_QUAD: begin
+            s_xpi_io_oe[3:0] = 4'b1111;
+            s_xpi_io_do[3:0] = s_xfer_data_q[31:28];
+          end
+          default: begin
+            s_xpi_io_oe[0] = 1'b1;
+            s_xpi_io_do[0] = s_xfer_data_q[31];
+          end
+        endcase
+      end
+      FSM_DUM, FSM_RXDATA: begin
+        s_xpi_io_oe = '0;
+      end
+      FSM_TXDATA: begin
+        unique case (dattyp_i)
+          `XPI_TYPE_SNGL: begin
+            s_xpi_io_oe[0] = 1'b1;
+            s_xpi_io_do[0] = s_xfer_data_q[31];
+          end
+          `XPI_TYPE_DUAL: begin
+            s_xpi_io_oe[1:0] = 2'b11;
+            s_xpi_io_do[1:0] = s_xfer_data_q[31:30];
+          end
+          `XPI_TYPE_QUAD: begin
+            s_xpi_io_oe[3:0] = 4'b1111;
+            s_xpi_io_do[3:0] = s_xfer_data_q[31:28];
+          end
+          default: begin
+            s_xpi_io_oe[0] = 1'b1;
+            s_xpi_io_do[0] = s_xfer_data_q[31];
+          end
+        endcase
+      end
+      default: begin
+      end
+    endcase
+  end
+
+
   always_comb begin
     s_fsm_d           = s_fsm_q;
     s_nss_d           = s_nss_q;
@@ -134,10 +213,6 @@ module xpi_core (
     // system
     rx_data_o         = '0;
     done_o            = 1'b0;
-    // xpi if
-    xpi.io_oe_o       = '0;
-    xpi.io_oe_o[0]    = 1'b1;
-    xpi.io_do_o       = '0;
     unique case (s_fsm_q)
       FSM_IDLE: begin
         if (s_xfer_condi) begin
@@ -176,26 +251,18 @@ module xpi_core (
           `XPI_TYPE_SNGL: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd1;
             s_xfer_data_d    = {s_xfer_data_q[30:0], 1'd0};
-            xpi.io_oe_o[0]   = 1'b1;
-            xpi.io_do_o[0]   = s_xfer_data_q[31];
           end
           `XPI_TYPE_DUAL: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd2;
             s_xfer_data_d    = {s_xfer_data_q[29:0], 2'd0};
-            xpi.io_oe_o[1:0] = 2'b11;
-            xpi.io_do_o[1:0] = s_xfer_data_q[31:30];
           end
           `XPI_TYPE_QUAD: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd4;
             s_xfer_data_d    = {s_xfer_data_q[27:0], 4'd0};
-            xpi.io_oe_o[3:0] = 4'b1111;
-            xpi.io_do_o[3:0] = s_xfer_data_q[31:28];
           end
           default: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd1;
             s_xfer_data_d    = {s_xfer_data_q[30:0], 1'd0};
-            xpi.io_oe_o[0]   = 1'b1;
-            xpi.io_do_o[0]   = s_xfer_data_q[31];
           end
         endcase
 
@@ -231,26 +298,18 @@ module xpi_core (
           `XPI_TYPE_SNGL: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd1;
             s_xfer_data_d    = {s_xfer_data_q[30:0], 1'd0};
-            xpi.io_oe_o[0]   = 1'b1;
-            xpi.io_do_o[0]   = s_xfer_data_q[31];
           end
           `XPI_TYPE_DUAL: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd2;
             s_xfer_data_d    = {s_xfer_data_q[29:0], 2'd0};
-            xpi.io_oe_o[1:0] = 2'b11;
-            xpi.io_do_o[1:0] = s_xfer_data_q[31:30];
           end
           `XPI_TYPE_QUAD: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd4;
             s_xfer_data_d    = {s_xfer_data_q[27:0], 4'd0};
-            xpi.io_oe_o[3:0] = 4'b1111;
-            xpi.io_do_o[3:0] = s_xfer_data_q[31:28];
           end
           default: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd1;
             s_xfer_data_d    = {s_xfer_data_q[30:0], 1'd0};
-            xpi.io_oe_o[0]   = 1'b1;
-            xpi.io_do_o[0]   = s_xfer_data_q[31];
           end
         endcase
 
@@ -278,7 +337,6 @@ module xpi_core (
         end
       end
       FSM_DUM: begin
-        xpi.io_oe_o      = '0;
         s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd1;
 
         if (s_xfer_bit_cnt_q == 8'd1) begin
@@ -303,26 +361,18 @@ module xpi_core (
           `XPI_TYPE_SNGL: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd1;
             s_xfer_data_d    = {s_xfer_data_q[30:0], 1'd0};
-            xpi.io_oe_o[0]   = 1'b1;
-            xpi.io_do_o[0]   = s_xfer_data_q[31];
           end
           `XPI_TYPE_DUAL: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd2;
             s_xfer_data_d    = {s_xfer_data_q[29:0], 2'd0};
-            xpi.io_oe_o[1:0] = 2'b11;
-            xpi.io_do_o[1:0] = s_xfer_data_q[31:30];
           end
           `XPI_TYPE_QUAD: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd4;
             s_xfer_data_d    = {s_xfer_data_q[27:0], 4'd0};
-            xpi.io_oe_o[3:0] = 4'b1111;
-            xpi.io_do_o[3:0] = s_xfer_data_q[31:28];
           end
           default: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd1;
             s_xfer_data_d    = {s_xfer_data_q[30:0], 1'd0};
-            xpi.io_oe_o[0]   = 1'b1;
-            xpi.io_do_o[0]   = s_xfer_data_q[31];
           end
         endcase
 
@@ -349,22 +399,18 @@ module xpi_core (
           `XPI_TYPE_SNGL: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd1;
             s_xfer_data_d    = {s_xfer_data_q[30:0], xpi.io_di_i[1]};
-            xpi.io_oe_o      = '0;
           end
           `XPI_TYPE_DUAL: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd2;
             s_xfer_data_d    = {s_xfer_data_q[29:0], xpi.io_di_i[1:0]};
-            xpi.io_oe_o      = '0;
           end
           `XPI_TYPE_QUAD: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd4;
             s_xfer_data_d    = {s_xfer_data_q[27:0], xpi.io_di_i[3:0]};
-            xpi.io_oe_o      = '0;
           end
           default: begin
             s_xfer_bit_cnt_d = s_xfer_bit_cnt_q - 8'd1;
             s_xfer_data_d    = {s_xfer_data_q[30:0], xpi.io_di_i[1]};
-            xpi.io_oe_o      = '0;
           end
         endcase
 
@@ -448,10 +494,6 @@ module xpi_core (
         // system
         rx_data_o         = '0;
         done_o            = 1'b0;
-        // xpi if
-        xpi.io_oe_o       = '0;
-        xpi.io_oe_o[0]    = 1'b1;
-        xpi.io_do_o       = '0;
       end
     endcase
   end
@@ -524,4 +566,12 @@ module xpi_core (
       s_rx_data_req_q
   );
 
+`ifndef SV_ASSRT_DISABLE
+`ifndef SYNTHESIS
+  a_xpi_read_pad_released :
+  assert property (@(posedge clk_i) disable iff (!rst_n_i)
+      (s_fsm_q == FSM_DUM || s_fsm_q == FSM_RXDATA) |-> s_xpi_io_oe == '0);
+`endif
+`endif
+
 endmodule

tests/rtl/xpi_io_tb.sv

@@ -0,0 +1,111 @@
+`timescale 1ns / 1ps
+
+`include "xpi_define.svh"
+
+module xpi_io_tb;
+  logic                    clk_i = 1'b0;
+  logic                    rst_n_i = 1'b0;
+  logic                    mode_i = 1'b0;
+  logic [`XPI_LNS_NUM-1:0] nss_i = '0;
+  logic [             7:0] clkdiv_i = '0;
+  logic                    rdwr_i = 1'b0;
+  logic                    revdat_i = 1'b0;
+  logic [             1:0] cmdtyp_i = `XPI_TYPE_NONE;
+  logic [             2:0] cmdlen_i = '0;
+  logic [            31:0] cmddat_i = '0;
+  logic [             1:0] adrtyp_i = `XPI_TYPE_NONE;
+  logic [             2:0] adrlen_i = '0;
+  logic [            31:0] adrdat_i = '0;
+  logic [             7:0] tdulen_i = '0;
+  logic [             7:0] rdulen_i = '0;
+  logic [             1:0] dattyp_i = `XPI_TYPE_NONE;
+  logic [             7:0] datlen_i = '0;
+  logic [             2:0] datbit_i = '0;
+  logic [             7:0] hlvlen_i = '0;
+  logic                    tx_data_rdy_i = 1'b0;
+  logic [            31:0] tx_data_i = '0;
+  logic                    rx_data_rdy_i = 1'b0;
+  logic                    start_i = 1'b0;
+  logic [             7:0] tx_elem_num_i = '0;
+  logic                    dma_xfer_done_i = 1'b0;
+  logic                    tx_data_req_o;
+  logic                    rx_data_req_o;
+  logic [            31:0] rx_data_o;
+  logic                    done_o;
+  xpi_if xpi ();
+
+  always #5 clk_i = ~clk_i;
+
+  xpi_core dut (
+      .clk_i          (clk_i),
+      .rst_n_i        (rst_n_i),
+      .mode_i         (mode_i),
+      .nss_i          (nss_i),
+      .clkdiv_i       (clkdiv_i),
+      .rdwr_i         (rdwr_i),
+      .revdat_i       (revdat_i),
+      .cmdtyp_i       (cmdtyp_i),
+      .cmdlen_i       (cmdlen_i),
+      .cmddat_i       (cmddat_i),
+      .adrtyp_i       (adrtyp_i),
+      .adrlen_i       (adrlen_i),
+      .adrdat_i       (adrdat_i),
+      .tdulen_i       (tdulen_i),
+      .rdulen_i       (rdulen_i),
+      .dattyp_i       (dattyp_i),
+      .datlen_i       (datlen_i),
+      .datbit_i       (datbit_i),
+      .hlvlen_i       (hlvlen_i),
+      .tx_data_req_o  (tx_data_req_o),
+      .tx_data_rdy_i  (tx_data_rdy_i),
+      .tx_data_i      (tx_data_i),
+      .rx_data_req_o  (rx_data_req_o),
+      .rx_data_rdy_i  (rx_data_rdy_i),
+      .rx_data_o      (rx_data_o),
+      .start_i        (start_i),
+      .done_o         (done_o),
+      .tx_elem_num_i  (tx_elem_num_i),
+      .dma_xfer_done_i(dma_xfer_done_i),
+      .xpi            (xpi)
+  );
+
+  task automatic expect_pad(input logic [3:0] oe, input logic [3:0] data, input string state);
+    begin
+      #1;
+      if (xpi.io_oe_o !== oe || xpi.io_do_o !== data) begin
+        $fatal(1, "%s pad drive was oe=%b data=%b", state, xpi.io_oe_o, xpi.io_do_o);
+      end
+    end
+  endtask
+
+  initial begin
+    repeat (2) @(posedge clk_i);
+    rst_n_i = 1'b1;
+    force dut.s_xfer_data_q = 32'hABCD_1234;
+
+    force dut.s_fsm_q = 3'd0;
+    expect_pad(4'b0001, 4'b0000, "idle");
+
+    cmdtyp_i = `XPI_TYPE_QUAD;
+    force dut.s_fsm_q = 3'd1;
+    expect_pad(4'b1111, 4'b1010, "command");
+
+    dattyp_i = `XPI_TYPE_DUAL;
+    force dut.s_fsm_q = 3'd4;
+    expect_pad(4'b0011, 4'b0010, "transmit");
+
+    force dut.s_fsm_q = 3'd3;
+    expect_pad(4'b0000, 4'b0000, "dummy");
+
+    force dut.s_fsm_q = 3'd5;
+    xpi.io_di_i = 4'b0000;
+    expect_pad(4'b0000, 4'b0000, "receive low");
+    xpi.io_di_i = 4'b1111;
+    expect_pad(4'b0000, 4'b0000, "receive high");
+
+    release dut.s_fsm_q;
+    release dut.s_xfer_data_q;
+    $display("XPI pad drive isolation test passed");
+    $finish;
+  end
+endmodule

tests/test_xpi_io.py

@@ -0,0 +1,78 @@
+"""RTL regression for XPI output-enable isolation during input phases."""
+
+from __future__ import annotations
+
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+
+ROOT = Path(__file__).resolve().parents[1]
+
+
+def test_xpi_releases_data_pads_while_receiving(tmp_path: Path) -> None:
+    iverilog = shutil.which("iverilog")
+    vvp = shutil.which("vvp")
+    if iverilog is None or vvp is None:
+        return
+
+    generated = tmp_path / "generated"
+    subprocess.run(
+        [
+            sys.executable,
+            str(ROOT / "rtl/mini/address_map/generate_memory_map.py"),
+            "--map",
+            str(ROOT / "rtl/mini/address_map/memory_map.json"),
+            "--output-dir",
+            str(generated),
+        ],
+        check=True,
+    )
+    source_list = tmp_path / "xpi_io.fl"
+    source_list.write_text(
+        "\n".join(
+            [
+                "+define+SV_ASSRT_DISABLE",
+                f"+incdir+{generated / 'rtl'}",
+                f"+incdir+{ROOT / 'rtl/ip/rib/storage'}",
+                f"+incdir+{ROOT / 'rtl/managed/clusterip/common/rtl'}",
+                str(ROOT / "rtl/managed/clusterip/common/rtl/interface/rib_if.sv"),
+                str(ROOT / "rtl/managed/clusterip/common/rtl/utils/register.sv"),
+                str(ROOT / "rtl/ip/rib/storage/xpi.sv"),
+                str(ROOT / "rtl/ip/rib/storage/xpi_clkgen.sv"),
+                str(ROOT / "rtl/ip/rib/storage/xpi_core.sv"),
+                str(ROOT / "tests/rtl/xpi_io_tb.sv"),
+                "",
+            ]
+        ),
+        encoding="utf-8",
+    )
+    converted = tmp_path / "xpi_io_tb.v"
+    subprocess.run(
+        [
+            sys.executable,
+            str(ROOT / "rtl/mini/script/convt_sv2v.py"),
+            "-f",
+            str(source_list),
+            "--output",
+            str(converted),
+        ],
+        check=True,
+    )
+    simulation = tmp_path / "xpi_io_tb"
+    subprocess.run(
+        [
+            iverilog,
+            "-g2012",
+            "-s",
+            "xpi_io_tb",
+            "-o",
+            str(simulation),
+            str(converted),
+        ],
+        check=True,
+    )
+    result = subprocess.run([vvp, str(simulation)], text=True, capture_output=True, check=True)
+
+    assert "XPI pad drive isolation test passed" in result.stdout