axis: Add TID_ROUTE parameter to taxi_axis_demux to faciliate routing replies by TID

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

src/axis/rtl/taxi_axis_demux.sv

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: CERN-OHL-S-2.0
 /*
 
-Copyright (c) 2018-2025 FPGA Ninja, LLC
+Copyright (c) 2018-2026 FPGA Ninja, LLC
 
 Authors:
 - Alex Forencich
@@ -19,6 +19,8 @@ module taxi_axis_demux #
 (
     // Number of AXI stream outputs
     parameter M_COUNT = 4,
+    // route via tid
+    parameter logic TID_ROUTE = 1'b0,
     // route via tdest
     parameter logic TDEST_ROUTE = 1'b0
 )
@@ -53,6 +55,8 @@ localparam logic LAST_EN = s_axis.LAST_EN && m_axis[0].LAST_EN;
 localparam logic ID_EN = s_axis.ID_EN && m_axis[0].ID_EN;
 localparam ID_W = s_axis.ID_W;
 localparam logic DEST_EN = s_axis.DEST_EN && m_axis[0].DEST_EN;
+localparam S_ID_W = s_axis.ID_W;
+localparam M_ID_W = m_axis[0].ID_W;
 localparam S_DEST_W = s_axis.DEST_W;
 localparam M_DEST_W = m_axis[0].DEST_W;
 localparam logic USER_EN = s_axis.USER_EN && m_axis[0].USER_EN;
@@ -61,6 +65,7 @@ localparam USER_W = s_axis.USER_W;
 localparam CL_M_COUNT = $clog2(M_COUNT);
 
 localparam M_DEST_W_INT = M_DEST_W > 0 ? M_DEST_W : 1;
+localparam M_ID_W_INT = M_ID_W > 0 ? M_ID_W : 1;
 
 // check configuration
 if (m_axis[0].DATA_W != DATA_W)
@@ -69,6 +74,17 @@ if (m_axis[0].DATA_W != DATA_W)
 if (KEEP_EN && m_axis[0].KEEP_W != KEEP_W)
     $fatal(0, "Error: Interface KEEP_W parameter mismatch (instance %m)");
 
+if (TID_ROUTE) begin
+    if (!ID_EN)
+        $fatal(0, "Error: TID_ROUTE set requires ID_EN set (instance %m)");
+
+    if (S_ID_W < CL_M_COUNT)
+        $fatal(0, "Error: S_ID_W too small for port count (instance %m)");
+
+    if (TDEST_ROUTE)
+        $fatal(0, "Error: Cannot enable both TID_ROUTE and TDEST_ROUTE (instance %m)");
+end
+
 if (TDEST_ROUTE) begin
     if (!DEST_EN)
         $fatal(0, "Error: TDEST_ROUTE set requires DEST_EN set (instance %m)");
@@ -90,7 +106,7 @@ logic [KEEP_W-1:0]    m_axis_tstrb_int;
 logic [M_COUNT-1:0]   m_axis_tvalid_int;
 logic                 m_axis_tready_int_reg = 1'b0;
 logic                 m_axis_tlast_int;
-logic [ID_W-1:0]      m_axis_tid_int;
+logic [M_ID_W-1:0]    m_axis_tid_int;
 logic [M_DEST_W-1:0]  m_axis_tdest_int;
 logic [USER_W-1:0]    m_axis_tuser_int;
 wire                  m_axis_tready_int_early;
@@ -115,7 +131,15 @@ always_comb begin
 
     if (!frame_reg && s_axis.tvalid && s_axis.tready) begin
         // start of frame, grab select value
-        if (TDEST_ROUTE) begin
+        if (TID_ROUTE) begin
+            if (M_COUNT > 1) begin
+                select_ctl = s_axis.tid[S_ID_W-1:S_ID_W-CL_M_COUNT];
+                drop_ctl = (CL_M_COUNT+1)'(select_ctl) >= (CL_M_COUNT+1)'(M_COUNT);
+            end else begin
+                select_ctl = '0;
+                drop_ctl = 1'b0;
+            end
+        end else if (TDEST_ROUTE) begin
             if (M_COUNT > 1) begin
                 select_ctl = s_axis.tdest[S_DEST_W-1:S_DEST_W-CL_M_COUNT];
                 drop_ctl = (CL_M_COUNT+1)'(select_ctl) >= (CL_M_COUNT+1)'(M_COUNT);
@@ -141,7 +165,7 @@ always_comb begin
     m_axis_tvalid_int = '0;
     m_axis_tvalid_int[select_ctl] = s_axis.tvalid && s_axis.tready && !drop_ctl;
     m_axis_tlast_int  = s_axis.tlast;
-    m_axis_tid_int    = s_axis.tid;
+    m_axis_tid_int    = M_ID_W'(s_axis.tid);
     m_axis_tdest_int  = M_DEST_W'(s_axis.tdest);
     m_axis_tuser_int  = s_axis.tuser;
 end
@@ -170,7 +194,7 @@ logic [KEEP_W-1:0]    m_axis_tkeep_reg  = '0;
 logic [KEEP_W-1:0]    m_axis_tstrb_reg  = '0;
 logic [M_COUNT-1:0]   m_axis_tvalid_reg = '0, m_axis_tvalid_next;
 logic                 m_axis_tlast_reg  = 1'b0;
-logic [ID_W-1:0]      m_axis_tid_reg    = '0;
+logic [M_ID_W-1:0]    m_axis_tid_reg    = '0;
 logic [M_DEST_W-1:0]  m_axis_tdest_reg  = '0;
 logic [USER_W-1:0]    m_axis_tuser_reg  = '0;
 
@@ -179,7 +203,7 @@ logic [KEEP_W-1:0]    temp_m_axis_tkeep_reg  = '0;
 logic [KEEP_W-1:0]    temp_m_axis_tstrb_reg  = '0;
 logic [M_COUNT-1:0]   temp_m_axis_tvalid_reg = '0, temp_m_axis_tvalid_next;
 logic                 temp_m_axis_tlast_reg  = 1'b0;
-logic [ID_W-1:0]      temp_m_axis_tid_reg    = '0;
+logic [M_ID_W-1:0]    temp_m_axis_tid_reg    = '0;
 logic [M_DEST_W-1:0]  temp_m_axis_tdest_reg  = '0;
 logic [USER_W-1:0]    temp_m_axis_tuser_reg  = '0;
 

src/axis/tb/taxi_axis_demux/Makefile

@@ -40,12 +40,14 @@ export PARAM_KEEP_W := $(shell expr \( $(PARAM_DATA_W) + 7 \) / 8 )
 export PARAM_STRB_EN := 0
 export PARAM_LAST_EN := 1
 export PARAM_ID_EN := 1
-export PARAM_ID_W := 8
+export PARAM_M_ID_W := 8
+export PARAM_S_ID_W := $(shell python -c "print($(PARAM_M_ID_W) + ($(PARAM_M_COUNT)-1).bit_length())")
 export PARAM_DEST_EN := 1
 export PARAM_M_DEST_W := 8
 export PARAM_S_DEST_W := $(shell python -c "print($(PARAM_M_DEST_W) + ($(PARAM_M_COUNT)-1).bit_length())")
 export PARAM_USER_EN := 1
 export PARAM_USER_W := 1
+export PARAM_TID_ROUTE := 0
 export PARAM_TDEST_ROUTE := 1
 
 ifeq ($(SIM), icarus)

src/axis/tb/taxi_axis_demux/test_taxi_axis_demux.py

@@ -65,11 +65,11 @@ async def run_test(dut, payload_lengths=None, payload_data=None, idle_inserter=N
 
     tb = TB(dut)
 
-    id_width = len(tb.source.bus.tid)
+    id_width = len(tb.sink[0].bus.tid)
     id_count = 2**id_width
     id_mask = id_count-1
 
-    dest_width = len(tb.sink[0].bus.tid)
+    dest_width = len(tb.sink[0].bus.tdest)
     dest_count = 2**dest_width
     dest_mask = dest_count-1
 
@@ -183,12 +183,14 @@ def test_taxi_axis_demux(request, m_count, data_w, tdest_route):
     parameters['STRB_EN'] = 0
     parameters['LAST_EN'] = 1
     parameters['ID_EN'] = 1
-    parameters['ID_W'] = 8
+    parameters['M_ID_W'] = 8
+    parameters['S_ID_W'] = parameters['M_ID_W'] + (m_count-1).bit_length()
     parameters['DEST_EN'] = 1
     parameters['M_DEST_W'] = 8
     parameters['S_DEST_W'] = parameters['M_DEST_W'] + (m_count-1).bit_length()
     parameters['USER_EN'] = 1
     parameters['USER_W'] = 1
+    parameters['TID_ROUTE'] = 0
     parameters['TDEST_ROUTE'] = tdest_route
 
     extra_env = {f'PARAM_{k}': str(v) for k, v in parameters.items()}

src/axis/tb/taxi_axis_demux/test_taxi_axis_demux.sv

@@ -25,12 +25,14 @@ module test_taxi_axis_demux #
     parameter logic STRB_EN = 1'b0,
     parameter logic LAST_EN = 1'b1,
     parameter logic ID_EN = 1'b0,
-    parameter ID_W = 8,
+    parameter M_ID_W = 8,
+    parameter S_ID_W = M_ID_W+$clog2(M_COUNT),
     parameter logic DEST_EN = 1'b0,
     parameter M_DEST_W = 8,
     parameter S_DEST_W = M_DEST_W+$clog2(M_COUNT),
     parameter logic USER_EN = 1'b1,
     parameter USER_W = 1,
+    parameter logic TID_ROUTE = 1'b0,
     parameter logic TDEST_ROUTE = 1'b0
     /* verilator lint_on WIDTHTRUNC */
 )
@@ -46,7 +48,7 @@ taxi_axis_if #(
     .STRB_EN(STRB_EN),
     .LAST_EN(LAST_EN),
     .ID_EN(ID_EN),
-    .ID_W(ID_W),
+    .ID_W(S_ID_W),
     .DEST_EN(DEST_EN),
     .DEST_W(S_DEST_W),
     .USER_EN(USER_EN),
@@ -60,7 +62,7 @@ taxi_axis_if #(
     .STRB_EN(STRB_EN),
     .LAST_EN(LAST_EN),
     .ID_EN(ID_EN),
-    .ID_W(ID_W),
+    .ID_W(M_ID_W),
     .DEST_EN(DEST_EN),
     .DEST_W(M_DEST_W),
     .USER_EN(USER_EN),
@@ -73,6 +75,7 @@ logic [$clog2(M_COUNT)-1:0] select;
 
 taxi_axis_demux #(
     .M_COUNT(M_COUNT),
+    .TID_ROUTE(TID_ROUTE),
     .TDEST_ROUTE(TDEST_ROUTE)
 )
 uut (