Post route antenna fix

openroad/scripts/chip.tcl

@@ -296,6 +296,9 @@ detailed_route -output_drc ${report_dir}/${log_id_str}_${proj_name}_route_drc.rp
                -clean_patches \
                -verbose 1
 
+# Post-route antenna fixing
+source scripts/post_route_antenna_fix.tcl
+
 utl::report "Saving detailed route"
 save_checkpoint ${log_id_str}_${proj_name}.drt
 report_metrics "${log_id_str}_${proj_name}.drt"

openroad/scripts/post_route_antenna_fix.tcl

@@ -0,0 +1,153 @@
+# Copyright 2026 ETH Zurich and University of Bologna.
+# Solderpad Hardware License, Version 0.51, see LICENSE for details.
+# SPDX-License-Identifier: SHL-0.51
+
+# Authors:
+# - Tobias Senti      <tsenti@ethz.ch>
+
+## Post-Route Antenna Fix Script
+# This script checks for antenna violations after detailed routing
+# and attempts to fix them by adding antenna diodes to the affected pins.
+# Runs up to $max_iterations or until no violations are found anymore.
+
+# Maximum number of iterations until giving up
+set max_iterations 3
+
+# Counter for unique diode names
+if {![info exists ::antennacounter]} {
+    set ::antennacounter 0
+}
+
+set early_exit 0
+for {set iteration 1} {$iteration <= $max_iterations} {incr iteration} {
+    puts "\n\n=== Antenna Fix Iteration $iteration ==="
+    set report_file_name "post_route_antenna_$iteration.rpt"
+
+    puts "Check for antenna violations"
+    check_antennas -report_file $report_dir/$report_file_name
+
+    puts "Parsing antenna report"
+
+    # Read in report
+    set fp [open $report_dir/$report_file_name]
+    set lines [split [read $fp] "\n"]
+    close $fp
+
+    # Parse report
+    set net_name ""
+    set pin_name ""
+    set has_violation 0
+    set pin_with_violations {}
+    foreach line $lines {
+        # Trim and split line
+        set line [string trim $line]
+        set split_parts [split $line]
+        set parts {}
+        foreach part $split_parts {
+            if { $part ne "" } {
+                lappend parts $part
+            }
+        }
+
+        # Check if it is a net or pin
+        set first_word [lindex $parts 0]
+        if { $first_word eq "Net:" } {
+            set net_name [lindex $parts 1]
+            puts "Processing net: $net_name"
+        }
+        if { $first_word eq "Pin:" } {
+            set pin_name [lindex $parts 1]
+            set has_violation 0
+            puts "  Pin: $pin_name"
+        }
+
+        # Prevent multiple additions of the same pin
+        if { $has_violation eq 0 } {
+            # Check if it is a violation line
+            set last_word [lindex $parts end]
+            if { $last_word eq "(VIOLATED)" } {
+                lappend pin_with_violations $pin_name
+                set has_violation 1
+                puts "    Adding pin $pin_name to violation list"
+            }
+        }
+    }
+
+    puts "\n\n"
+
+    # If no violations, exit loop
+    if { [llength $pin_with_violations] eq 0 } {
+        puts "No antenna violations detected, exiting."
+        set early_exit 1
+        break
+    }
+
+    # Add one antenna diode per pin with violation
+    puts "Add antenna diodes"
+    set block [ord::get_db_block]
+    set ant_master [odb::dbDatabase_findMaster [ord::get_db] "sg13g2_antennanp"]
+    set violation_nets {}
+    foreach pin $pin_with_violations {
+        puts "Pin with antenna violation: $pin"
+        set parts [split $pin "/"]
+        set pin_name [lindex $parts end]
+        set cell_name [join [lrange $parts 0 end-1] "/"]
+
+        # Get instance
+        set inst [odb::dbBlock_findInst $block $cell_name]
+        puts [odb::dbInst_getName $inst]
+
+        # Get iterm (db representation of pin)
+        set iterm [odb::dbInst_findITerm $inst $pin_name]
+
+        # Get net connected to iterm
+        set net [odb::dbITerm_getNet $iterm]
+        set net_name [odb::dbNet_getName $net]
+        # remove backslashes from net name
+        set net_name [string map {"\\" ""} $net_name]
+        lappend violation_nets $net_name
+
+        # Remove routing of the net if it has any
+        set wire [odb::dbNet_getWire $net]
+        if { $wire ne "NULL"} {
+            odb::dbWire_destroy $wire
+        }
+
+        # Create antenna diode instance
+        set ant_name "post_route_ant_diode_[incr ::antennacounter]"
+        set inst [odb::dbInst_create $block $ant_master $ant_name]
+
+        # Connect antenna diode to the net
+        set inst_iterm [odb::dbInst_findITerm $inst "A"]
+        odb::dbITerm_connect $inst_iterm $net
+
+        # Place antenna diode near the pin (gate to protect)
+        set xy [odb::dbITerm_getAvgXY $iterm]
+        puts "Placing antenna diode at $xy"
+        odb::dbInst_setLocation $inst [lindex $xy 1] [lindex $xy 2]
+        odb::dbInst_setPlacementStatus $inst "PLACED"
+    }
+
+    # Refine placement of diodes
+    puts "Detailed placement"
+    detailed_placement
+
+    # Ensure diodes are connected to power
+    puts "Connect power"
+    global_connect
+
+    # Reroute affected nets
+    puts "Detailed route"
+    detailed_route -output_drc ${report_dir}/${log_id_str}_${proj_name}_post_route_antenna_fix_drc.rpt \
+            -droute_end_iter 30 \
+            -drc_report_iter_step 5 \
+            -save_guide_updates \
+            -clean_patches \
+            -verbose 1
+}
+
+# Final antenna check if we have not exited early i.e. fixed all violations
+if {$early_exit eq 0} {
+    puts "Final antenna check"
+    check_antennas -report_file $report_dir/$report_file_name
+}