From 446dc19fc64f7a7cc76134b350c975df16ca3749 Mon Sep 17 00:00:00 2001
From: Alex Forencich <alex@alexforencich.com>
Date: Sun, 15 Mar 2026 16:01:53 -0700
Subject: [PATCH] axi: When tying AXI interfaces, permit narrowing the address
 bus

Signed-off-by: Alex Forencich <alex@alexforencich.com>
---
 src/axi/rtl/taxi_axi_tie_rd.sv  | 5 ++++-
 src/axi/rtl/taxi_axi_tie_wr.sv  | 5 ++++-
 src/axi/rtl/taxi_axil_tie_rd.sv | 5 ++++-
 src/axi/rtl/taxi_axil_tie_wr.sv | 5 ++++-
 4 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/axi/rtl/taxi_axi_tie_rd.sv b/src/axi/rtl/taxi_axi_tie_rd.sv
index cc9c494..98de758 100644
--- a/src/axi/rtl/taxi_axi_tie_rd.sv
+++ b/src/axi/rtl/taxi_axi_tie_rd.sv
@@ -39,6 +39,9 @@ localparam logic RUSER_EN = s_axi_rd.RUSER_EN && m_axi_rd.RUSER_EN;
 localparam RUSER_W = s_axi_rd.RUSER_W;
 
 // check configuration
+if (m_axi_rd.ADDR_W > ADDR_W)
+    $fatal(0, "Error: Output ADDR_W is wider than input ADDR_W, cannot access entire address space (instance %m)");
+
 if (m_axi_rd.DATA_W != DATA_W)
     $fatal(0, "Error: Interface DATA_W parameter mismatch (instance %m)");
 
@@ -46,7 +49,7 @@ if (m_axi_rd.STRB_W != STRB_W)
     $fatal(0, "Error: Interface STRB_W parameter mismatch (instance %m)");
 
 assign m_axi_rd.arid = s_axi_rd.arid;
-assign m_axi_rd.araddr = s_axi_rd.araddr;
+assign m_axi_rd.araddr = m_axi_wr.ADDR_W'(s_axi_rd.araddr);
 assign m_axi_rd.arlen = s_axi_rd.arlen;
 assign m_axi_rd.arsize = s_axi_rd.arsize;
 assign m_axi_rd.arburst = s_axi_rd.arburst;
diff --git a/src/axi/rtl/taxi_axi_tie_wr.sv b/src/axi/rtl/taxi_axi_tie_wr.sv
index c99c18c..52b0955 100644
--- a/src/axi/rtl/taxi_axi_tie_wr.sv
+++ b/src/axi/rtl/taxi_axi_tie_wr.sv
@@ -41,6 +41,9 @@ localparam logic BUSER_EN = s_axi_wr.BUSER_EN && m_axi_wr.BUSER_EN;
 localparam BUSER_W = s_axi_wr.BUSER_W;
 
 // check configuration
+if (m_axi_wr.ADDR_W > ADDR_W)
+    $fatal(0, "Error: Output ADDR_W is wider than input ADDR_W, cannot access entire address space (instance %m)");
+
 if (m_axi_wr.DATA_W != DATA_W)
     $fatal(0, "Error: Interface DATA_W parameter mismatch (instance %m)");
 
@@ -49,7 +52,7 @@ if (m_axi_wr.STRB_W != STRB_W)
 
 // bypass AW channel
 assign m_axi_wr.awid = s_axi_wr.awid;
-assign m_axi_wr.awaddr = s_axi_wr.awaddr;
+assign m_axi_wr.awaddr = m_axi_wr.ADDR_W'(s_axi_wr.awaddr);
 assign m_axi_wr.awlen = s_axi_wr.awlen;
 assign m_axi_wr.awsize = s_axi_wr.awsize;
 assign m_axi_wr.awburst = s_axi_wr.awburst;
diff --git a/src/axi/rtl/taxi_axil_tie_rd.sv b/src/axi/rtl/taxi_axil_tie_rd.sv
index a0fea61..09d9b72 100644
--- a/src/axi/rtl/taxi_axil_tie_rd.sv
+++ b/src/axi/rtl/taxi_axil_tie_rd.sv
@@ -38,13 +38,16 @@ localparam logic RUSER_EN = s_axil_rd.RUSER_EN && m_axil_rd.RUSER_EN;
 localparam RUSER_W = s_axil_rd.RUSER_W;
 
 // check configuration
+if (m_axil_rd.ADDR_W > ADDR_W)
+    $fatal(0, "Error: Output ADDR_W is wider than input ADDR_W, cannot access entire address space (instance %m)");
+
 if (m_axil_rd.DATA_W != DATA_W)
     $fatal(0, "Error: Interface DATA_W parameter mismatch (instance %m)");
 
 if (m_axil_rd.STRB_W != STRB_W)
     $fatal(0, "Error: Interface STRB_W parameter mismatch (instance %m)");
 
-assign m_axil_rd.araddr = s_axil_rd.araddr;
+assign m_axil_rd.araddr = m_axil_rd.ADDR_W'(s_axil_rd.araddr);
 assign m_axil_rd.arprot = s_axil_rd.arprot;
 assign m_axil_rd.aruser = ARUSER_EN ? s_axil_rd.aruser : '0;
 assign m_axil_rd.arvalid = s_axil_rd.arvalid;
diff --git a/src/axi/rtl/taxi_axil_tie_wr.sv b/src/axi/rtl/taxi_axil_tie_wr.sv
index 98fe7db..086d218 100644
--- a/src/axi/rtl/taxi_axil_tie_wr.sv
+++ b/src/axi/rtl/taxi_axil_tie_wr.sv
@@ -40,6 +40,9 @@ localparam logic BUSER_EN = s_axil_wr.BUSER_EN && m_axil_wr.BUSER_EN;
 localparam BUSER_W = s_axil_wr.BUSER_W;
 
 // check configuration
+if (m_axil_wr.ADDR_W > ADDR_W)
+    $fatal(0, "Error: Output ADDR_W is wider than input ADDR_W, cannot access entire address space (instance %m)");
+
 if (m_axil_wr.DATA_W != DATA_W)
     $fatal(0, "Error: Interface DATA_W parameter mismatch (instance %m)");
 
@@ -47,7 +50,7 @@ if (m_axil_wr.STRB_W != STRB_W)
     $fatal(0, "Error: Interface STRB_W parameter mismatch (instance %m)");
 
 // bypass AW channel
-assign m_axil_wr.awaddr = s_axil_wr.awaddr;
+assign m_axil_wr.awaddr = m_axil_wr.ADDR_W'(s_axil_wr.awaddr);
 assign m_axil_wr.awprot = s_axil_wr.awprot;
 assign m_axil_wr.awuser = AWUSER_EN ? s_axil_wr.awuser : '0;
 assign m_axil_wr.awvalid = s_axil_wr.awvalid;